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11098806 | Emerging homosexual conduct during hospitalization among chronic schizophrenia patients. | The study investigated the emerging homosexual conduct during hospitalization among chronic schizophrenia patients. |
11098807 | Differences between patients with identified and not identified psychiatric disorders in primary care. | The aim of this study was to discover the differences between the primary care patients with a psychiatric disorder whose illness was detected and the patients whose disorder was not detected. |
11098808 | The relationship between depressive and vital exhaustion symptomatology post-myocardial infarction. | Many peri-myocardial infarction patients experience decreased wellbeing, which is either conceptualized as depression or as vital exhaustion. The objective of the present study is to investigate whether or not depression and vital exhaustion are separate entities. It was hypothesized that, if depression and vital exhaustion are separate phenomena, the correlation between two depression questionnaires would be higher than those between either of the two depression questionnaires and a vital exhaustion questionnaire. |
11098809 | The perception of needs for care in staff and patients in community-based mental health services. The South-Verona Outcome Project 3. | The present study aims to assess needs for care rated by patients and staff and their agreement on needs assessment in munity-based mental health service by using the Camberwell Assessment of Need (CAN). |
11098810 | Social networks and functional status in patients with psychosis. | To investigate whether large social networks are associated with better functional e in psychotic disorders. |
11098811 | Prolactin and beta-endorphin serum elevations after ECT in manic patients. | Alterations in prolactin and beta-endorphin serum levels after ECT are well-established findings in depression. The present study focuses on electroconvulsive therapy (ECT) response patterns of the mentioned parameters in patients suffering from acute mania. |
11098812 | Augmentation with sulpiride for a schizophrenic patient partially responsive to clozapine. | Schizophrenic patients who are only partially responsive to clozapine pose a therapeutic challenge. In these circumstances some clinicians would consider adding in a second antipsychotic. We present a case report and review evidence for the efficacy of such augmentation strategies. |
11098815 | Anachelin, the siderophore of the cyanobacterium Anabaena cylindrica CCAP 1403/2A. | A catecholate siderophore - anachelin - has been isolated from the cyanobacterium Anabaena cylindrica CCAP 1403/2A. The central part of the siderophore is a tripeptide consisting of L-Thr, D-Ser and L-Ser. Its C-terminus is linked amidically to a 1,1-dimethyl-3-amino-1,2,3,4-tetrahydro-7,8-dihydroxyquinolinium system and its N-terminus to 6-amino-3,5,7-trihydroxyheptanoic acid. The 7-hydroxyl group of the latter is esterified with salicylic acid whose carboxyl group is condensed with the 6-amino group to an oxazoline ring. Anachelin is the first genuine siderophore of a cyanobacterium whose structure has been elucidated. |
11098814 | The siderophores of Pseudomonas fluorescens 18.1 and the importance of cyclopeptidic substructures for the recognition at the cell surface. | The structure of the pyoverdin siderophore of Pseudomonas fluorescens 18.1 was elucidated by spectroscopic methods and chemical degradation. By cross feeding studies structurally closely related pyoverdins containing a C-terminal cyclopeptidic substructure were tested regarding the mutual recognition by the producing strains. Partial recognition of foreign pyoverdins was observed. |
11098817 | Two new eudesmane alcohols from Jasonia glutinosa. | Two new sesquiterpene alcohols have been isolated from the aerial parts of Jasonia glutinosa D. C. The structure of these sesquiterpenes were characterized by 1D and 2D NMR techniques (DQCOSY. TOCSY, NOESY, HMQC and HMBC) as (11R)-eudesm-4-en-11,12-diol and (11R)-eudesmane-5alpha, 11,12-triol. |
11098816 | Major constituents of the foliar epicuticular waxes of species from the Caatinga and Cerrado. | The epicuticular waxes of leaves of four species (Aspidosperma pyrifolium, Capparis yco, Maytenus rigida and Ziziphus joazeiro) from the Caatinga, (a semi-arid ecosystem of Northeast Brazil) and four species (Aristolochia esperanzae, Didymopanax vinosum, Strychnos pseudoquina and Tocoyena formosa) from the Cerrado, (a savanna ecosystem covering one third of the Brazilian territory), were analyzed. Six species contained a high content (above 60 microg x cm(-2)) of wax, four of them from the Caatinga. Triterpenoids and n-alkanes were the most frequent and abundant constituents found in the species from both habitats. The distribution of n-alkanes predominated by homologues with 27, 29, 31 and 33 carbon atoms, displayed no consistent differences between species from the two habitats. Lupeol, beta-amyrin, epifriedelinol and ursolic acid were the triterpenoids found. Triterpenoids clearly predominate over alkanes in the waxes from the Cerrado species. The waxes of two evergreen species from the Caatinga yielded n-alkanes as predominant constituents. parison of foliar epicuticular waxes of native plants from ecosystems with different hydric constraints is discussed. |
11098818 | Sesquiterpene lactones from Inula montana L. | Aerial parts of Inula montana were investigated for its position. Five sesquiterpene lactones, isoinuviscolide, gaillardin, 1beta-hydroxy-3beta-acetoxy-eudesm-4(15), 11(13)-dien-12-8beta-olide, pulchellin-C and pulchellin-E were identified for the first time in this plant. One of them, 1beta-hydroxy-3beta-acetoxy-eudesm-4(15),11(13)-dien-1 2-8beta-olide, is a novel natural product. The structures of pounds were established by 1D and 2D-NMR spectroscopy. |
11098820 | Copper accumulation and phosphatase activities of Aspergillus and Rhizopus. | Copper accumulation and phosphatase activities of three Aspergillus species resistant to copper pared to three copper-sensitive Rhizopus species. High level of acid phosphatases and decreased Cu2+-uptake were found with resistant in contrast to sensitive strains. The presence of copper(II) ions in the medium increased the production of acid phosphatases in the resistant A. niger and decreased their activity in the sensitive R. delemar. Copper ions inhibited the activity of A. niger cellular acid phosphatase with a Ki of 8.9x10(-4) M and slightly activated the R. delemar enzyme. |
11098822 | Elicitor-induced defence reactions in cell suspension cultures of soybean cultivars. | Suspension cultured soybean (Glycine max [L.] Merr.) cells of four cultivars (Wilis, Lumut, Kalmit, Doko RC) pared for their response to different fungal and bacterial elicitors. Cells were treated either with crude cell wall extracts of the fungal pathogens Phytophthora sojae (Pmg-elicitor) and Rhizoctonia solani (Riso-elicitor) or with two isolates of the bacterial pathogen Pseudomonas syringae pv. glycinea (Psg01/02) and a broad spectrum of antimicrobial defence reactions was measured. Cells of all four cultivars showed the same elicitor-induced rapid (H2O2 accumulation, alkalinization of the culture medium, peroxidative cross-linking of cell wall proteins) and slow (activation of phenylpropanoid metabolism, accumulation of pounds, induction of PR-proteins) defence responses. However, the reactivity of the cultivars was not identical in terms of time courses and intensities. Furthermore, the ability of the various elicitors to induce defence responses varied markedly. These differences indicate that (1) cells of the same species but of different cultivars are equipped with the same array of perception systems to recognise various stimuli but (2) the sensitivity of these perception systems or later steps in the signal transduction seem to be stimulated to a different extent in the analysed cultivars. |
11098823 | Induction of DNA-protein cross-links by platinum compounds. | The differences between cis- and trans-diamminedichloroplatinum II (DDP) in forming DNA-protein cross-links in isolated human lymphocytes were investigated. Both cis- and trans-DDP can induce DNA-protein cross-links. We show that cis-DDP plexes between DNA and proteins faster than trans-DDP. This results from an increase in the quantity of DNA and platinum together with an increase in drug concentration. Under the same conditions trans-DDP causes a decrease in plexes with proteins. After a 12 h incubation of lymphocytes we observe a similar level of DNA in DNA-protein cross-links induced by DDP isomers, but more platinum appears plexes induced by trans-DDP. The results obtained demonstrate that the antitumor drug - cis-DDP and the clinically ineffective trans-DDP induce links between DNA and proteins in a different manner. We suggest that the therapeutic activity of cis-DDP can in part arise from rapidly forming plexes which can destroy the most important cellular processes, such as replication and transcription. |
11098821 | Biotransformation of two cytotoxic terpenes, alpha-santonin and sclareol by Botrytis cinerea. | Two cytotoxic terpenes, alpha-santonin (1) and sclareol (3) were biotransformed by a plant pathogenic fungus Botrytis cinerea to produce oxidized metabolites in high yields. Alpha-Santonin (1) on fermentation with the fungus for ten days afforded a hydroxylated metabolite identified as 11beta-hydroxy-alpha-santonin (2) in a high yield (83%), while sclareol (3) was metabolized to epoxysclareol (4) (64%) and a pound 8-deoxy-14,15-dihydro-15-chloro-14-hydroxy-8,9-dehydrosclareol (5) (7%), representing a rare example of microbial halogenation. |
11098825 | Complexation of membrane-bound enzyme systems. | The effect of changes in the N-terminal membrane-binding domain of cytochrome P450 forms and NADPH-cytochrome P450 reductase types on the cytochrome P450-dependent monooxygenase activities, has been examined. The nifedipine oxidase activity of two human P450 forms (CYP3A4, CYP3A4NF14) which differ only in their primary structure by ten amino acid residues in the N-terminal membrane-binding domain, yields nearly the same catalytic cycle time tau =2.65 +/- 0.15 s, due to their identical cytosolic catalytic protein structure. In contrast, plex formation process ([P450]+[reductase] <--> [complex]) described by the dissociation constant KD, at high substrate concentration ([S]>>KS) and low product concentration ([P]<<KP) is determined to be KD/[P4501]o = 0.3 and 2.0, respectively. These values reflect large differences in the affinity of both P450 forms for the same type of reductase which is only due to their modified membrane-binding domains. In the present work, it has been shown for the first time, that the membrane-binding domain of cytochrome P450 enzymes determines plexation process of the binary P450:reductase system. Furthermore, the nifedipine oxidase activity of the human CYP3A4 form reconstituted with two different types of reductase from human and rabbit also has the same catalytic cycle time tau = 2.65 +/- 0.15 s. This result is based on the similarity of the primary structure of the cytosolic catalytic domain of both reductase types. However, plex was formed with different dissociation constants of KD/[P450]o = 0.3 and 4.7, respectively. This different affinity of both reductase types to the same P450 form is interpreted as a consequence of the substantial alteration of the amino acids in the N-terminal primary structure of their membrane-binding domains. 7-Ethoxycoumarin O-deethylase activity of two rat P450 forms (CYP2B1 and CYP1A1) were reconstituted with the same rat reductase. The catalytic cycle time for each P450 form is tau = 1.8 and 0.6 s, respectively. Correspondingly, plex formation process controlled by the dissociation constant KD has changed from KD/[P450]o = 2.3 to 1.7, respectively. This is because both forms differ in their cytosolic as well as in their membrane-binding domains. |
11098827 | Different effects of di- and triphenyltin compounds on lipid bilayer dithionite permeabilization. | Phenyltins are chemicals widely used in industry, hence their occurrence in the human environment is frequent and widespread. pounds include hydrophobic phenyl rings bonded to positively charged tin. This molecular structure makes them capable of adsorbing onto and penetrating through biological membranes, hence they are potentially hazardous. Two pounds, diphenyltin and triphenyltin, show different steric constraints when interacting with the lipid bilayer. It has been demonstrated that pounds are positioned at different locations within model lipid bilayers, causing dissimilarity in their ability to affect membrane properties. In this paper we present a study regarding the ability of these two phenyltins to facilitate the transport of S2O4(-2) ions across the lipid bilayer, evaluated by a fluorescence quenching assay. In concentration range of up-to 60 microM pounds do not affect lipid bilayer topology, when evaluated by vesicle size distribution. Both phenyltins facilitate the transfer of S2O4(-2) across the model lipid bilayer, but the dependence of dithionite transport on phenyltin concentration is different for both. In principle, above 20 microM triphenyltin is more efficient in transferring ions across the lipid bilayer than diphenyltin. |
11098819 | Occurrence and characterization of a UDP-glucose:hydroxamic acid glucosyltransferase isolated from wheat (Triticum aestivum) seedlings. | Cyclic hydroxamic acid glucosides are present at high concentrations immediately after germination in wheat (Triticum aestivum L.). Changes in the activity of UDP-Glucose:cyclic hydroxamic acid glucosyltransferase (EC 2.4.1.-) in wheat were investigated using the cyclic hydroxamic acids 2.4-dihydroxy-1,4-benzoxazin-3-one (DIBOA) and its 7-methoxy derivative (DIMBOA) as sugar acceptors. Glucosyltransferase activity on both substrates was detected in dry seeds, with activity increasing after imbibition, peaking in shoots and roots 36-48 hours after imbibition and decreasing thereafter. The transience of glucosyltransferase activity was concurrent with the transient occurrence of the hydroxamic acid glucosides [Nakagawa E., Amano T., Hirai N., and Iwamura H. (1995) Phytochemistry 38, 1349-1354], suggesting that glucosyltransferases regulate the accumulation of hydroxamic acid glucosides in wheat seedlings. Two peaks in activity of UDP-Glucose:DIMBOA glucosyltransferase were detected using a Mono Q column, indicating the presence of at least two isozymes of this glucosyltransferase. The enzyme in the major peak was purified about 1500-fold and shown to be in a monomeric form with a molecular mass of 47 or 49 kDa. The enzyme reacted strongly with DIMBOA, less so with DIBOA. The enzyme of the minor peak on the Mono Q chromatogram, which was also a monomeric enzyme with a molecular mass of 47 kDa, showed similar substrate specificity to that of the major peak enzyme. |
11098826 | Influence of dodecyltrimethylammonium halides on thermotropic phase behaviour of phosphatidylcholine/cholesterol bilayers. | Effects of dodecyltrimethylammonium chloride (DTAC), dodecyltrimethylammonium bromide (DTAB) and dodecyltrimethylammonium iodide (DTAI) on thermotropic phase behaviour of phosphatidylcholine bilayers containing cholesterol as well as on 1H NMR spectra were studied. Two series of experiments were performed. In the first one the surfactants were added to the water phase while in the other directly to the lipid phase (a mixed film from cholesterol, surfactant and phosphatidylcholine was formed). The effects of particular surfactants on the main phase transition temperature, Tm, were more pronounced when added to the lipid phase (2nd method) than to the water phase (1st method); the opposite happened when cholesterol was absent (Rózycka-Roszak and Pruchnik 2000, Z. Naturforsch. 55c, 240-244). Furthermore, in the case of the first method the transitions were asymmetrical while in the second method nearly symmetrical. It is suggested that surfactant poor and surfactant rich domains are formed when surfactants are added to the water phase. |
11098829 | Kinetic attributes of Na+, K+ ATPase and lipid/phospholipid profiles of rat and human erythrocyte membrane. | Kinetic properties of Na+, K+ ATPase of membranes from rat and human erythrocytes were examined. The enzyme stability decreased with incubation time. The Vmax of the human enzyme was about 4 times lower than the values of the rat enzyme. However the energies of activation were higher. Phase transition temperature for the rat and the human enzyme was 24 degrees C and 17 degrees C, respectively. The human erythrocyte membranes were characterized by lower total phospholipid and cholesterol contents and were relatively more fluid. The human membranes contained lower proportions of acidic phospholipids which correlated well with the lower Vmax of the enzyme; the proportion of lysophosphoglyceride and sphingomyelin was higher in the human membrane. |
11098824 | The influence of formamide on thermal denaturation profiles of DNA and metaphase chromosomes in suspension. | Systematic photometric studies are presented to analyze the thermal denaturation behaviour with and without formamide of metaphase chromosome suspensions parison to DNA solutions. Temperature dependent hyperchromicity measurements at 256 nm and 313 nm were performed using an appropriately puter-controlled photometer device. Due to an upright optical axis, this allowed absorbance measurements with negligible sedimentation effects not only for solutions of pure DNA, but also for particle suspensions of isolated metaphase chromosomes. This device has a temperature resolution of +/- 0.5 degrees C and an optical sensitivity of 10(-3) to 10(-4) optical density. For calf thymus DNA the reduction of the melting point with the increase of formamide in the solution was measured at pH 7.0 and pH 3.2. The good correlation of the theoretical approximation to experimental data indicated the suitability of the apparatus to quantitatively describe DNA conformation changes induced by thermal denaturation. For metaphase chromosome preparations of Chinese hamster culture cells, absorbance changes were measured between 20 degrees C and 95 degrees C with a temperature gradient of 1 degrees C/min. These measurements were performed at pH 7.0 and at pH 3.2. The denaturation profiles (= first derivative of the absorbance curve) resulted in a highly variable peak pattern at 256 nm and 313 nm plex conformation changes. A statistical evaluation of the temperature values of the peak maxima resulted in temperature ranges typical for chromosomal conformation changes during thermal treatment. Especially the range of highest temperature values was independent from pH modifications. For pH 3.2 the influence of formamide on the denaturation behaviour of metaphase chromosome preparations was analyzed. In contrast to pure DNA solutions, a reduction of the "melting point" (i.e. the maximum temperature at which a conformation change takes place) was not found. However, the denaturation behaviour depended on the duration of formamide treatment before the measurement. |
11098828 | Influence of triphenyllead chloride on biological and model membranes. | The physiological and hemolytic toxicities of triphenyllead chloride (TPhL) as well as its modifying influence on model lipid membranes were studied. The experiments allowed the determination of TPhL concentrations causing 50% inhibition of growth of Spirodela oligorrhiza, Lemna minor and Salvinia natans (EC50), 100% hemolysis of pig erythrocytes (C100) and destabilization of planar lipid membranes (CC). Also, fluidity of erythrocyte ghosts was measured by fluorescence technique and osmotic sensitivity of erythrocytes to the presence of TPhL. All parameters studied were found to be dependent on pH, of experimental solutions and the concentration of TPhL. Acidic conditions increased EC50 C100 and CC concentrations of TPhL. Fluorescence and osmotic measurements showed that osmotic stability and fluidity decreased with increasing trimethyllead concentration. A possible mechanism of TPhL toxicity is discussed. It is assumed that TPhL is interacting with the lipid phase of the models used. It is also assumed that there may exist various, ionic and nonionic, forms of TPhL as a result of its speciation under different experimental conditions. These species, due to their differentiated lipophilicity, may exert different effects on the model membranes studied. |
11098830 | Study on propolis quality from China and Uruguay. | position, bacteriostatic and ROO*-scavenging potential activities of fifteen propolis samples from various botanic and geographic origins were determined to obtain objective information related to propolis quality. Variance analysis showed significant differences (p < or = 0.05) in the contents of polyphenols, flavonoids and ponents between fresh and aged propolis. The state of the product (fresh or aged) could be differentiate by using flavonoid pattern and biological activities. A minimum propolis concentration of 80 microg/ml was required inhibit Bacillus subtilis and Staphylococcus aureus while 800 microg/ml was required to inhibit Escherichia coli using fresh propolis. Aged propolis inhibit B. subtilis and S. aureus at concentration of 100 microg/ml and E. coli at 1000 microg/ml. A minimum flavonoids percentage of 18 g/100 g and a maximum ROO*-scavenging potential activity of 4.3 microg/ml were determined in fresh propolis. Flavonoids levels in aged propolis were approximately 20% lower than in fresh propolis. A maximum flavonoids percentage of 19.8 g/100 g and a ROO*-scavenging potential activity between 5.7 to 6.4 microg/ml in aged propolis were quantified. Another objective was to assess the use of ROO*-scavenging potential activity in propolis quality. |
11098831 | Chemical composition and biological activity of propolis from Brazilian meliponinae. | Twenty-one propolis samples produced by 12 different Meliponinae species were analyzed by GC-MS. Several chemical types of stingless bees' propolis could be grouped, according to the prevailing type pounds like: 'gallic acid", "diterpenic" and "triterpenic" types. The results confirm that neither the bee species nor the geographical location determine the position of Meliponinae propolis and the choice of its plant source, respectively. This could be explained by the fact that Meliponinae forage over short distances (maximum 500 m) and thus use as propolis source the first plant exudate they encounter during their flights. The antibacterial, antifungal and cytotoxic activities of the samples were also investigated. Most samples had weak or no activity against E. coli, weak action against Candida albicans. Some of them showed significant activity against St. aureus., presumably connected to the high concentration of diterpenic acids. Samples rich in diterpenic acids possessed also high cytotoxic activity (Artemia salina test). |
11098832 | Propolis from the Mediterranean region: chemical composition and antimicrobial activity. | The position of propolis from Bulgaria, Turkey, Greece and Algeria was investigated by GC-MS. All of them contained mainly flavonoids and esters of caffeic and ferulic acids, which indicated that their main source are buds of poplars of the taxonomic section Aegieros. Some Turkish samples contained a low percent of diterpenic acids, while in Algerian samples significant amounts of a hydroxyditerpenic acid (M=322, its structure not determined by its MS) were found. All samples showed significant antibacterial and weak to moderate antifungal activity. |
11098834 | Superoxide production by phagocytes in myeloid Graffi tumor-bearing hamsters. | A progressive suppression of the phagocytic ability of peritoneal macrophages and polymorphonuclears (PMNs) in hamsters with transplanted myeloid tumors was previously established. The i.p. application of Cu/Zn SOD, isolated from the fungal strain Humicola lutea (HLSOD) (2 injections before and 5 injections after tumor transplantation) induced the mean survival time of the animals as well as a temporally stimulating action on the macrophage and PMNs phagocyting indices. In the present work, the superoxide production of peritoneal macrophages and PMNs during 30 days of tumor progression was followed. Effects of the application of HLSOD in an optimal protective dose on the superoxide production in peritoneal macrophages and blood PMNs were examined. The spontaneous and phorbol-myristate acetate (PMA)-inducible O2- production in both types of phagocytes was 4-5-fold increased in tumor-bearing hamsters (TBH), pared to the controls, at day 14 after tumor transplantation (the day of tumor appearance in transplanted animals). Furthermore, O2- production was also similar to the control values for the following days of observation. HLSOD treatment of TBH induced a normalization of superoxide production in macrophages and PMNs. Therefore, the established decrease of superoxide anions in phagocyting cells of TBH indicates possible effects of HLSOD on the host antioxidant defense. |
11098835 | Exogenous melatonin elevates the plasma leptin and thyroxine concentrations of the mink (Mustela vison). | Eight male and eight female minks were given exogenous melatonin as subcutaneous implants. The plasma leptin and thyroxine concentrations were measured. The leptin concentrations showed clear seasonal variations and differences between the experimental groups. In September most of the control females had undetectable plasma leptin concentrations, but the melatonin-treated females had detectable concentrations significantly higher than the leptin levels of the controls. Most of the males had undetectable leptin concentrations, too. In October the plasma leptin levels had increased significantly in all the groups except the control males. The melatonin-treated minks had significantly higher leptin levels than the controls. There was a significant rise in the thyroxine levels from September to October and the melatonin-treated groups had significantly higher thyroxine levels than the controls. The effects of exogenous melatonin are very pronounced in the mink. Melatonin elevates the plasma leptin and thyroxine levels possibly by direct and indirect mechanisms. |
11098833 | Chemical composition of the lipophylic extract from the tunicate Botryllus schlosseri. | Eighteen sterols were identified in Botryllus schlosseri, stanols being the main sterols. The position is in agreement with our recent paper on taxonomic separation of tunicates into three groups. Again we found in invertebrates of the Black Sea sterols with a (22Z)-double bond. This confirms the presence of such sterols in nature. position of the phospholipids appeared to plex, and twelve groups of them were identified in Botryllus schlosseri. The main representatives of phospholipids appeared to be phosphatidylcholine and phosphatidylethanolamine. Only four pounds were identified, which is unusual for marine invertebrates. |
11098837 | I3-naringenin-II8--4'OMe-eriodictyol: a new potential analgesic agent isolated from Rheedia gardneriana leaves. | This paper describes the isolation, identification and analgesic activity of a new biflavonoid from Rheedia gardneriana leaves, which correspond to I3-naringenin-II8-4'-OMe-eriodictyol (GB-2a-II-4'-OMe) (1), with a methoxyl group in position 4 of ring-II. Its structure was determined by spectroscopic data and confirmed by an alkaline hydrolysis. Its analgesic effect was evaluated in a writhing test and a formalin test in mice. It was found that pound exhibits potent and dose-related analgesic action in both experimental models, with ID50's values of 4.5 micromol/kg against the writhing test and 8.2 and 6.8 micromol/kg against the first and second phase of the formalin test, respectively. It was several times more potent than some well-known analgesic drugs used as reference. |
11098839 | Antiherpes virus effect of the red marine alga Polysiphonia denudata. | The water extract from the red marine alga Polysiphonia denudata (Dillwyn) Kutz. from the Bulgarian Black Sea coast selectively inhibited the reproduction of herpes virus type 1 and type 2 in cell cultures (EC50=8.7 to 47.7 mg/ml) as shown by the reduction of virus-induced cytopathic effect and viral infectivity. The virus-inhibitory effect was dose-related, strain-specific and depended on virus inoculum. The inhibition affected adsorption as well as the intracellular stages of viral replication. The presence of the extract throughout the whole replicative cycle was necessary for the full expression of the antiviral effect. In higher concentrations (MIC90=6.5 mg/ml) the extract exhibited strong extracellular virus inactivating activity. |
11098836 | Effect of minor components of virgin olive oil on topical antiinflammatory assays. | Interest in the health-promoting effects of virgin olive oil, an important part of the "Mediterranean diet", prompted us to determine the antiinflammatory effects of erythrodiol, beta-sitosterol and squalene, identified as ponents of the so-called "unsaponifiable fraction" of virgin olive oil, as well as of the pounds from the "polar fraction": oleuropein, tyrosol, hydroxytyrosol and caffeic acid. Their activities pared to those of both, total unsaponifiable and polar fractions. This study was designed to analyse the antiinflammatory effect of these pounds from virgin olive oil on edema in mice induced by either arachidonic acid (AA) or 12-O-tetradecanoylphorbol acetate (TPA). The inhibition of the myeloperoxidase (MPO), marker enzyme of the accumulation of neutrophils in the inflamed tissue, was also investigated by the TPA model. The topical application of the olive pounds (0.5 mg/ear) produced a variable degree of antiinflammatory effect with both assays. In the auricular edema induced by TPA, beta-sitosterol and erythrodiol from the unsaponifiable fraction of the oil showed a potent antiedematous effect with a 61.4% and 82.1% of inhibition respectively, values not very different to that of the reference indomethacin (85.6%) at 0.5 mg/ear. The four phenolics exerted a similar range of inhibition (33-45%). pounds strongly inhibited the enzyme myeloperoxidase, indicating a reduction of the neutrophil influx in the inflamed tissues. The strongest inhibitor of AA edema was the total unsaponifiable fraction which inhibition was 34%, similar to that obtained by the reference drug dexamethasone at 0.05 mg/ear. Among the phenolics, oleuropein also produced an inhibition of about 30% with the same dose, but all the ponents were found less active in this assay. The anti-inflammatory effects exerted by both unsaponifiable and pounds might contribute to the potential biological properties reported for virgin olive oil against different pathological processes. |
11098846 | Effect of bcl-2 deficiency on the radiation response of clonogenic cells in small and large intestine, bone marrow and testis. | Overexpression of bcl-2 protects against radiation induced apoptosis in lymphohaematopoietic cell types in vivo, whilst bcl-2 deficiency radiosensitizes murine T-lymphocytes in vitro. However, there are few data regarding the influence of bcl-2 deficiency on the radiosensitivity of non-lymphoid cell types. The purpose of this study was to investigate the role of bcl-2 in the clonogenic radiation response of intestinal crypts, bone marrow progenitor cells and testicular stem cells. |
11098838 | Antioxidant properties of rimantadine in influenza virus infected mice and in some model systems. | Influenza virus infection is associated with development of oxidative stress in lung and blood plasma, viz. increase of primary and secondary lipid peroxidation products. It was established that rimantadine treatment led to a decrease of the products of lipid peroxidation in tissues of mice experimentally infected with influenza virus A/Aichi/2/68 (H3N2). The effect is strongest in blood plasma (a decrease of about 50%) and weaker in the lung (about 20%). To elucidate the mechanism of this action of rimantadine, experiments were carried out with some model systems. The capability of rimantadine to scavenge superoxide radicals (scavenging properties) was studied in a system of xanthine-xanthine oxidase to generate superoxide. The amount of superoxide was measured spectrophotometrically by the NBT-test and chemiluminesce. Rimantadine does not show scavenging properties and its antioxidant effect observed in vivo, is not a result of its direct action on the processes of lipid peroxidation and/or interaction with antioxidant enzymes. The antioxidant properties of rimantadine were investigated by measurement of induced lipid peroxidation in a Fe2+ and (Fe2+ - EDTA) system with an egg liposomal suspension. Our findings with model systems do not prove an antioxidant or prooxidant effect of the drug on the processes of lipid peroxidation. Apparently, the observed antioxidant effect of rimantadine in vivo is not connected directly with free radical processes in the organism. |
11098847 | NF-kappaB and AP-1 are responsible for inducibility of the IL-6 promoter by ionizing radiation in HeLa cells. | To investigate the mechanisms leading to initiation by ionizing radiation of IL-6 transcription in HeLa cells. |
11098842 | Fatty acids and sterols from Cymbopogon martinii var. motia roots. | The hexane and methanol extracts of the roots of Cymbopogon martinii var. motia have been investigated to afford mainly fatty acids mon sterols. A new hydroxy unsaturated fatty acid, namely, 16-hydroxypentacos-14(z)-enoic acid, has also been isolated. |
11098843 | Production and secretion of 5-n-alkylresorcinols by Fusarium culmorum. | Fusarium culmorum F1 was found to produce and secrete into the culture medium several of 5-n-alkylresorcinols. The amount of resorcinolic lipids was 5.3 microg/g and 0.9 microg/l in mycelium and in post-culture liquid, respectively. First of all F. culmorum F1 produces saturated homologues with C15 to C25 side chains. The extract from the medium contained only homologues with shorter carbon chains (C13 to C17). |
11098841 | Terpenoids from Achillea setacea. | The aerial parts of Achillea setacea afforded, in addition of a rare monoterpene triol and 12 known sesquiterpene lactones, a new guaianolide containing an endoperoxide ring. Its structure was elucidated by spectral methods. |
11098848 | Modulation of calmodulin by UV and X-rays in primary human endothelial cell cultures. | Previous studies by the present authors and others have shown that the expression of many genes is modulated by radiation. The purpose of this study is to identify additional genes that are affected by UV and X-radiation. Identification of specific genes affected by radiation may allow the determination of pathways important in radiation responses as well as an examination of transcriptional elements that are involved in the process. |
11098849 | Kinetics of DSB rejoining and formation of simple chromosome exchange aberrations. | To investigate the role of kinetics in the processing of DNA double strand breaks (DSB), and the formation of simple chromosome exchange aberrations following X-ray exposures to mammalian cells based on an enzymatic approach. |
11098844 | Iron(II)-mimosine catalyzed cleavage of DNA. | Mimosine, DNA breaKs, Free Radicals, Fenton Reaction Supercoiled plasmid DNA was treated in vitro with H2O2, DTT and either Fe (II), Fe (II)-EDTA or Fe (II)-mimosine. The rate of DNA break formation was followed by the conversion of the supercoiled form into relaxed-circular and linear forms. In the concentration interval of 0-4 microM Fe (II), Fe (II)-EDTA slowed-down the formation of DNA breaks, while Fe (II)-mimosine enhanced the rate of break formation up to several times. A conclusion is drawn that this enhancement is due to the increased affinity of the Fe plex to DNA. |
11098845 | The effect of galactose metabolic disorders on rat brain acetylcholinesterase activity. | To evaluate whether in classical galactosemia galactose (Gal), galactose-1-phosphate (Gal-1-P) and galactitol (Galtol) affect brain acetylcholinesterase (AChE) activity, various concentrations (1-16 mM) of pounds were preincubated with brain homogenates of suckling rats as well as with pure eel Electroforus electricus AChE at 37 degrees C for 1 h. Initially, Galtol (up to 2.0 mM) increased (25%) AChE activity which decreased. thereafter, reaching the control value in high Galtol concentrations. Gal-1-P decreased gradually the enzyme activity reaching a plateau (38%), when incubated with 8-16 mM. However, when the usually found 2 mM of Galtol and 2 mM of Gal-1-P, concentrations in galactosemia were added in the incubation mixture simultaneously, brain AChE was stimulated (16%). Galtol or Gal-1-P modulated brain AChE as well as enzyme activity of E.electricus in the same way. Gal, Glucose (Glu) and glucose-1-phosphate (Glu-1-P) had no effect on AChE activity. It is suggested that Galtol as well as Gal-1-P can affect acetylcholine degradation acting directly on AChE molecule. Consequently the direct action of these substances on the enzyme might explain the brain cholinergic dysfunction in untreated galactosemia patients. |
11098851 | Inhibition of repair of X-ray-induced DNA double-strand breaks in human lymphocytes exposed to sodium butyrate. | Sodium butyrate is known to inhibit histone deacetylase enzymes and to enhance the frequencies of X-ray-induced dicentrics and rings in human lymphocytes. In this study an investigation was made of the mechanisms underlying this enhancement by assessing the effect of sodium butyrate on the extent of X-ray-induced DNA damage and its repair in human peripheral blood lymphocytes. |
11098850 | DNA strand-break yields after post-irradiation incubation with base excision repair endonucleases implicate hydroxyl radical pairs in double-strand break formation. | To determine the increases in SSB and DSB yields after post gamma-irradiation incubation of plasmid DNA with the Escherichia coli base excision repair endonucleases formamidopyrimidine-DNA N-glycosylase (FPG) and endonuclease III (endo III). |
11098840 | The complex structure of ferri-ferribactins. | parison of the NMR data of the ferribactins from Pseudomonas chlororaphis ATCC 9446 and of P. fluorescens 18.1 with those of their plexes as models for the plexes it will be shown that only two bidentate ligands are provided plexation, both located in the peptide chain. The two remaining free sites of the octahedral metal ion are probably occupied by solvent molecules. |
11098852 | Determination of the initial DNA damage and residual DNA damage remaining after 12 hours of repair in eleven cell lines at low doses of irradiation. | To determine the relationship between DNA damage and radiosensitivity at low doses (1-10 Gy) for the initial DNA damage and residual DNA damage remaining after 12-h repair. |
11098853 | Radiation-induced double-strand breaks in mammalian DNA: influence of temperature and DMSO. | To investigate the effects of subphysiological irradiation temperature (2 28 degrees C) and the influence of the radical scavenger DMSO on the induction of double-strand breaks (DSB) in chromosomal DNA from a human breast cancer cell line (MCF-7) as well as in intact cells. The rejoining of DSB in cells irradiated at 2 degrees C or 37 degrees C was also investigated. |
11098854 | The effects of weak magnetic fields on radical recombination reactions in micelles. | To demonstrate the effects of weak magnetic fields (> approximately 1 mT) on chemical reactions involving free radicals, in the context of possible effects of environmental electromagnetic radiation on biological systems. |
11098855 | Oxidation of cellular thiols by hydroxyethyldisulphide inhibits DNA double-strand-break rejoining in G6PD deficient mammalian cells. | We investigated the effect of protein- and non protein-thiol oxidation on DNA double-strand-break (DSB) rejoining after irradiation and its relevance in the survival of CHO cells. |
11098856 | Coming of age: 'dysgenetics'--a theory connecting induction of persistent delayed genomic instability with disturbed cellular ageing. | In recent years a new phenomenon has manifested itself: delayed, persistent genomic instability. When cells are treated with carcinogens not only direct induction of chromosome aberrations and mutations takes place, but there is also an indirect induction: in the distant progeny of treated cells persistently enhanced levels of new chromosome aberrations and enhanced mutation rates are found. This persistent enhanced genomic instability is not due to the presence of lesions in the DNA induced by the treatment because the response can be transmitted to untreated cells. Apparently it is caused by a persistent dysfunctioning of the cell as a whole. Due to these findings a new model for multistep carcinogenesis emerges. According to this model the initiation of carcinogenesis is the induction of a state of persistent genomic instability that not only is responsible for enhanced mutation rates of oncogenes and tumor suppressor genes, but also predisposes to immortalization. This view could lead to a radical change in our views on carcinogenesis. Therefore understanding the mechanism is of utmost importance. |
11098857 | Mathematical methods in biological dosimetry: the 1996 Iranian accident. | To report 18 months of cytogenetic follow-up for an Iranian worker accidentally overexposed to 192Ir, the mathematical extrapolation parison with clinical data. |
11098858 | Radiation effects in spheroids of cells exposed to alpha emitters. | To simulate spheroids of cells and use the spheroid models to establish methods of calculating cell survival following exposure to alpha irradiation from decays of 211At and 213Bi. |
11098859 | Influence of acetylsalicylic acid on development of radiation-induced nephropathy. | Previous studies have demonstrated that long-term treatment with acetylsalicylic acid (ASA) can significantly reduce the renal functional impairment that develops after high doses of irradiation. The effect is hypothesized to be mediated by selective inhibition of thromboxane A2 synthesis and inhibition of platelet aggregation. The present study was undertaken to investigate this phenomenon further using more clinically relevant fractionated and re-irradiation schedules. |
11098860 | State-specific prevalence of current cigarette smoking among adults and the proportion of adults who work in a smoke-free environment--United States, 1999. | Tobacco use in the United States causes approximately 430,000 deaths each year, including an estimated 3000 deaths from lung cancer among nonsmokers exposed to environmental tobacco smoke (ETS). In addition, an estimated 62,000 coronary heart disease deaths annually among nonsmokers exposed to ETS. The detrimental health effects of exposure to ETS are well documented and include, in addition to lung cancer and coronary heart disease among adults, low birthweight and sudden infant death syndrome from exposure during and after pregnancy and asthma, bronchitis, and pneumonia in children. This report summarizes the 1999 prevalence of current cigarette smoking among adults by state and the proportion of persons who work indoors and who report that their workplaces have smoke-free policies. The findings indicate that in 1999, adult smoking prevalence differed more than two-fold across states (13.9%-31.5%) and that the proportion of persons who reported that their workplace had an official smoke-free policy ranged from 61.3%-82.1%. As the respondents' level of education increased, they were more likely to report working under a smoke-free policy. |
11098861 | Update: outbreak of Rift Valley Fever--Saudi Arabia, August-November 2000. | On September 10, 2000, the Ministry of Health (MOH), Kingdom of Saudi Arabia and subsequently, the MOH of Yemen began receiving reports of unexplained hemorrhagic fever in humans and associated animal deaths and abortions from the far western Saudi-Yemeni border region. These cases subsequently were confirmed as Rift Valley fever (RVF), the first such cases on the Arabian peninsula. This report updates the findings of the ongoing investigation conducted by the Saudi Arabian MOH in collaboration with CDC and the National Institute of Virology, South Africa. |
11098862 | Progress toward interrupting indigenous measles transmission--Region of the Americas, January 1999-September 2000. | In 1994, countries in the Region of the Americas set a goal of interrupting indigenous measles transmission by the end of 2000. From 1990 to 1996, measles cases declined from approximately 250,000 to an all-time low of 2109 confirmed cases. However, a resurgence began in 1997, with 52,284 confirmed cases reported from Brazil and in 1998, with 14,330 confirmed cases reported from 16 (39%) of the 41 countries that report to the Pan American Health Organization (PAHO). This report summarizes the measles control strategies implemented in the region and measles incidence during 1999-2000 and indicates that the region has made important progress towards interrupting indigenous measles transmission and that achieving this goal is within reach. |
11098863 | Introduction: Listening to the Voice of the C/S/X: Consumer/Survivor/Expatient. | People who are receiving services for professionally diagnosed psychological disabilities often are not consulted about the nature of those services, or their willingness to participate in them. This issue of the journal presents the autobiographical accounts of four such people, followed mentaries about those accounts by three professional service-givers. This collection emphasizes the need to obtain informed consent for any psychological services that are offered, for ethical, humane, and professional reasons. |
11098864 | Agents, not objects: our fights to be. | People who have been diagnosed and treated for major mental illness have an insider expertise that can provide invaluable insight into the mysteries of people's often inexplicable movement in and out of madness. The author vividly describes his passages from identity-seeking young adult to mental hospital patient to psychologist and mental health system critic. The harmful, life-threatening treatments he experienced are examined as part of our society's propensity to treat people who are different as deviant and relegate them to ineffective and harmful medical interventions. Alternatives to psychiatric hospitalizations are promoted as more positive options for people going through confusing and frightening life-changing experiences. The article concludes with the author's ideas about what is necessary and helpful when working with someone who has been labeled with a major mental illness and what is counterproductive and harmful. |
11098865 | Psychology practitioners and schizophrenia: a view from both sides. | In recent years some few psychologists, psychiatrists, and other mental health professionals have begun to reveal their own experiences as persons who have been diagnosed with various forms of serious mental illnesses. This article gives a brief background of one such person, a practicing psychologist who was diagnosed early in his adult life with schizophrenia. Despite numerous breakdowns and hospitalizations he was able to establish a career as a practitioner and as an advocate. The article also offers a number of mendations for professionals in this field based on the author's experiences as both a recipient and a provider of psychological services to persons with schizophrenia and other serious mental illnesses. |
11098866 | The long road back. | "The Long Road Back" captures the undulating path of the recovery process from sexual abuse and bipolar disorder in the public mental heath system. It highlights ways the traditional mental health system can help and harm. Even more so. it highlights for the author the importance of involvement in the peer self-help movement. Role modeling, hope, and recovery by fellow recipients of services enabled movement toward life-engaging functions such as volunteerism, school and career possibilities. and mitment to advocacy on behalf of her peers still in the public mental health system. The peer perspective can especially enhance care. Utilizing peer self-help and carefully listening to the voices of those in the system can make mental health services more responsive to our needs. |
11098867 | It has to be about choice. | My time in the mental health system began a little over 20 years ago, when I was seven. Over the past eight years I have been fighting for, demanding that, respect and ethics play a part in psychology and all that falls under it. I realized that for all the reasons that have been given, for all the excuses that have been made, for a long time I acted as little more than an apologist for a system that refused to change. I learned that it is impossible to make any great systemic changes without the change being wanted-no matter how warranted it is. A system may desperately need to be overhauled, gutted out, and rebuilt. However, inside of that system are the people who work for it, who need the consistency that they have e used to. Psychology, to me, is a self-perpetuating institution. It creates the laws and then defines who breaks them. I am no longer an apologist for the mental health system. Candidly, I have not yet learned how to put a pretty bow on all of my views, which are a direct result of my voluntary and involuntary time in the system. both personally and professionally. All I know is that it has to be about choice. |
11098868 | Personal accounts of consumer/survivors: insights and implications. | The personal accounts of people diagnosed with mental illness have much to teach practitioners. Based on the four articles in this issue, the expanding literature of personal accounts, and the relevant professional literature, some of the salient themes are discussed. Initially, the human context of mental illness is explored, including the diversity among those diagnosed with mental illness and the cataclysmic impact of such a diagnosis on individuals. The recovery process also is examined, including the role of hope, locus of control, coping skills and strategies, and social support and self-help. Finally, the mental health system is considered, including the limitations of the system, patienthood, professional roles and relationships, and psychotherapy. Implications for practitioners are noted. |
11098869 | Commentary: listening to the message. | The first-person accounts of c/s/x experiences with the mental health system have mon threads that run through them. These are: (1) labels are stigmatizing; (2) pathology-based models are destructive: (3) it is important to value individuality; (4) alternative treatments are valuable: (5) peer support and self-help are important; (6) therapist training must be reconsidered; and (7) services should be recovery-oriented. In order to be as helpful as possible, mental health professionals must enter into creative partnerships with those in the c/s/x movement, and must consider incorporating these issues in their own functioning and in the training of future professionals. |
11098871 | Intensive behavioral/psychoeducational treatments for autism: research needs and future directions. | It is widely acknowledged that, to date, the forms of treatment enjoying the broadest empirical validation for effectiveness with individuals with autism are those treatments based upon a behavioral model and that such treatments are best implemented intensively and early in the child's development. This paper describes several features important in the success of this model and presents remaining issues to be addressed for improving treatment effectiveness. While it is appreciated that there is no "one size fits all" treatment for children with autism, there is as yet no established protocol for relating specific child, family, target behavior, and treatment variables to individualized treatment regimens. Future research needs to include well-conceived and methodologically rigorous investigations allowing for the determination of these important variables. |
11098870 | Consumers' perspectives on helpful and hindering factors in mental health treatment. | We summarize the four papers in this issue by consumers evaluating their mental health treatment, focusing on aspects of their treatment that they collectively found helpful and hindering. These factors include the context of treatment, the therapy relationship, interventions used and issues addressed, helpful experiences outside the mental health system, and hindering views of mental illness and treatment. We then ments by two clients in outpatient therapy on the same topic. Research on clients' perceptions of their outpatient psychotherapy is discussed in reference to these six consumer perspectives, and future directions for therapists and researchers are suggested. |
11098873 | Interventions to facilitate communication in autism. | The purpose of this article is to discuss research opportunities arising from the current literature in the area munication. Six general themes are discussed, including (a) increasing spontaneity, initiations, and the variety of functions of language verbal and nonverbal children with autism exhibit; (b) assessing and teaching precursors relating to positive e; (c) the importance of family involvement in intervention programs; (d) best practices for implementation municative interventions; (e) the interrelationship between language and other behavioral symptoms of autism; and (f) the social and pragmatic use of language. These areas are discussed in terms of improving assessment and intervention practices to produce greater municative es for individuals with autism. |
11098875 | Interventions that facilitate socialization in children with autism. | Social dysfunction is perhaps the most defining and handicapping feature of autism. Improved social functioning has long been considered one of the most important intervention es. A variety of social interventions have been designed, empirically examined, and published in the autism literature. Children with autism have been found to be responsive to a wide variety of interventions aimed at increasing their social engagement with others, both adults and peers. Successful strategies employing peer-mediated approaches and peer tutoring have involved typically developing peers. Furthermore, several studies have demonstrated that social engagement directly affects other important behaviors like language, even when these behaviors are not specifically targeted by the teaching program. Thus, while an area of severe involvement, social behavior is also responsive to intervention. |
11098877 | Interventions to facilitate auditory, visual, and motor integration in autism: a review of the evidence. | Evidence is reviewed on the prevalence of sensory and motor abnormalities in autism and the effectiveness of three interventions designed to address such abnormalities--sensory integration therapy, traditional occupational therapy, and auditory integration training. Although sensory processing and motor abnormalities are neither universal nor specific to autism, the prevalence of such abnormalities in autism is relatively high. There is, however, little controlled research on the effectiveness of interventions designed to address these abnormalities. Four objective e studies of sensory integration therapy were identified. These were of such small scale that no firm conclusions regarding efficacy could be made. No empirical studies of traditional occupational therapy in autism were found. Five studies of auditory integration training were found. Results of these studies provided no, or at best equivocal, support for the use of auditory integration training in autism. |
11098879 | Repetitive thoughts and behavior in pervasive developmental disorders: treatment with serotonin reuptake inhibitors. | Repetitive thoughts and behavior are considered integral and ponents of autistic disorder. Results from recent studies suggest that the types of repetitive thoughts and behavior of adults with autism and those with pulsive disorder (OCD) may be different. Serotonin reuptake inhibitors (SRIs), the primary drug treatment for patients with OCD, may reduce the repetitive phenomena of some autistic patients. Two controlled studies of the nonselective SRI clomipramine have shown the drug to be more efficacious than the relatively selective norepinephrine reuptake inhibitor desipramine and placebo in children with autism. One controlled study of the selective SRI fluvoxamine found it to be significantly better than placebo for reducing repetitive phenomena and aggression in adults with autistic disorder. Additional research is needed. |
11098881 | Pharmacological treatment of mood disturbances, aggression, and self-injury in persons with pervasive developmental disorders. | Aggression, self-injury, and mood disturbances in persons with autistic disorders, while not mon, do not constitute core features of autism. Moreover, these problems can occur for a variety of reasons, which need to be assessed in order to plan appropriate and bined (behavioral-pharmacological) treatments. Drugs acting primarily in the dopaminergic, serotonergic, adrenergic, opioidergic, and glutamatergic systems all have been explored in the treatment of aggression and self-injury. While no single drug or class of medication has yet emerged as consistently effective, a number of drugs appear promising. Advances in the assessment of aggressive behaviors, the identification of predictors of drug response, and additional controlled clinical drug trials specifically aimed at these target behaviors are essential in improving the approach to these problematic behaviors in the context of autistic disorder. |
11098883 | Pharmacotherapy for hyperactivity in children with autism and other pervasive developmental disorders. | We reviewed pharmacological treatments used in children with autism and PDD-NOS who present with hyperactive symptoms. Some 41 studies were identified from the following drug categories: antipsychotics (n = 13), serotonin reuptake inhibitors (n = 3), antianxiety drugs (n = 4), psychostimulants (n = 10), alpha adrenergic agonists (n = 2), opiate blockers (n = 7), and other drugs (n = 2). Empirical evidence for significant reductions in hyperactive symptoms was strongest for the antipsychotics, psychostimulants, and naltrexone. Most studies have focused on the reduction of overactivity, and more emphasis needs to be placed on distractibility and attentional variables. A theoretical model was proposed in which participants' attentional performance may be used to predict clinical response to psychostimulants. More carefully controlled prehensive studies of hyperactivity are badly needed in these children. |
11098885 | Metabolic approaches to the treatment of autism spectrum disorders. | Although the exact prevalence of metabolic abnormalities in autism spectrum disorders is unknown, several metabolic defects have been associated with autistic symptoms. These include phenylketonuria, histidinemia, adenylosuccinate lyase deficiency, dihydropyrimidine dehydrogenase deficiency, 5'-nucleotidase superactivity, and phosphoribosylpyrophosphate synthetase deficiency. When the metabolic consequences of an enzyme defect are well defined (e.g., phenylketonuria, 5'-nucleotidase superactivity), treatment with diet, drugs, or nutritional supplements may bring about a dramatic reduction in autistic symptoms. This review evaluates evidence for metabolic etiologies in autism spectrum disorders, as well as for the efficacy of dietary and vitamin treatments. The relationship between gastrointestinal abnormalities and autism spectrum disorders is also considered. |
11098887 | Immunological treatments for autism. | Several investigators, including ourselves, have reported significant changes in various immune responses in children with autism. These changes demonstrate dysregulation of the immune system (deficiency in ponents of the immune system and excesses in others). In addition, certain genes in the major plex (that regulates immune responses) appear to be involved in autism. Based upon immunological abnormalities, various treatment modalities have been applied to children with autism. In this brief review, these immunological changes and various biological therapies are analyzed and summarized. |
11098889 | Treatment of seizure disorders and EEG abnormalities in children with autism spectrum disorders. | The treatment of seizure disorders EEG epileptiform abnormalities without epilepsy in children with autism spectrum disorders (ASD) is considered within the context of the relationship of epilepsy and epileptiform disorders to language, behavior, and cognition. There is an increased prevalence of both epilepsy and abnormal potentially epileptogenic activity in children with ASD. Anecdotal evidence suggests that the use of anticonvulsants to treat epileptiform discharges thought to be producing dysfunction in selected aspects of cognition, language, or behavior makes a positive difference in a subgroup of children with ASD, but there is inadequate evidence on which to base specific mendations. There is, at present, no scientific justification for considering epilepsy surgery in children with ASD in the absence of intractable clinical seizures. |
11098891 | The basis of hyperspecificity in autism: a preliminary suggestion based on properties of neural nets. | This article reviews a few key ideas about the representation of information in neural networks and uses these ideas to address one aspect of autism, namely, the apparent hyperspecificity that is often seen in autistic children's application of previously acquired information. Hyperspecificity is seen as reflecting a possible feature of the neural codes used to represent concepts in the autistic brain. |
11098894 | EPR imaging from projections: errors due to misalignment of projection centres and their rectification by a novel acquisition modality. | Continuous wave and pulsed wave electron paramagnetic resonance imaging (EPRI) makes use of classical methods of acquisition of projections. Acquisition/reconstruction techniques, such as spin-echo, gradient-echo, etc, cannot be applied to EPRI because they would require very short switching times for the gradient coils. Due to the use of the polar acquisition technique, it is necessary to define a centre of rotation about which the measured projections are rotated during the reconstruction process. This centre represents the point at which the field gradient coils must produce zero magnetic field. Due to the presence of a magnetic field control system that serves pensate for field variations, principally due to heating, some interference can occur in the control system between the main magnetic field and the magnetic field produced by the gradient coils. The effect changes as the orientation changes. This results in a shift of the centres of the projections as a function of the variation of magnetic field produced by the gradient coils on the control Hall probe. If this condition is present, some artefacts can appear on the reconstructed image. This effect is irrelevant when EPR is used for imaging of paramagnetic probes whose linewidths are of the order of 10(-4) T, while it can be significant in the case of linewidths of the order of 10(-5) T or lower or when EPR is used in microimaging applications (i.e. for high values of magnetic field gradient). We describe the effects that misalignments of the projections have on the reconstructed images. We present a useful method for estimating the real position of the centre and correcting the measured projections before the application of the reconstruction algorithm. Moreover, we demonstrate the functioning of our technique by presenting some examples of EPR reconstruction collected by an X-band EPR imaging apparatus. |
11098893 | High-resolution image reconstruction method for time-of-flight positron emission tomography. | We present a new image reconstruction method for time-of-flight positron emission tomography (TOF-PET). The TOF-PET measurement system is modelled using the continuous-discrete mapping model, and images are reconstructed using an algebraic technique. The proposed method can produce images with better spatial resolution than conventional methods based on the filtered backprojection method. Numerical simulation results show that accurate modelling of the measurement system improves the spatial resolution and the contrast recovery, while the utilization of TOF information improves the signal-to-noise ratios of images. |
11098895 | Brain perfusion monitoring with frequency-domain and continuous-wave near-infrared spectroscopy: a cross-correlation study in newborn piglets. | The newborn piglet brain model was used to correlate continuous-wave (CW) and frequency-domain (FD) near-infrared spectroscopy. Six ventilated and instrumented newborn piglets were subjected to a series of manipulations in blood oxygenation with the effects on brain perfusion known to be associated with brain hypoxia-ischaemia. An excellent agreement between the CW and FD was demonstrated. This agreement improved when the scattering properties (determined by the FD device) were employed to calculate the differential pathlength factor, an important step in CW data processing. |
11098896 | Backscatter towards the monitor ion chamber in high-energy photon and electron beams: charge integration versus Monte Carlo simulation. | In some linear accelerators, the charge collected by the monitor ion chamber is partly caused by backscattered particles from ponents downstream from the chamber. This influences the output of the accelerator and also has to be taken into account when output factors are derived from Monte Carlo simulations. In this work, the contribution of backscattered particles to the monitor ion chamber response of a Varian 2100C linac was determined for photon beams (6, 10 MV) and for electron beams (6, 12, 20 MeV). The experimental procedure consisted of charge integration from the target in a photon beam or from the monitor ion chamber in electron beams. The Monte Carlo code EGS4/BEAM was used to study the contribution of backscattered particles to the dose deposited in the monitor ion chamber. Both measurements and simulations showed a linear increase in backscatter fraction with decreasing field size for photon and electron beams. For 6 MV and 10 MV photon beams, a 2-3% increase in backscatter was obtained for a 0.5 x 0.5 cm2 pared to a 40 x 40 cm2 field. The results for the 6 MV beam were slightly higher than for the 10 MV beam. For electron beams (6, 12, 20 MeV), an increase of similar magnitude was obtained from measurements and simulations for 6 MeV electrons. For higher energy electron beams a smaller increase in backscatter fraction was found. The problem is of less importance for electron beams since large variations of field size for a single electron energy usually do not occur. |
11098897 | A Monte Carlo track structure code for electrons (approximately 10 eV-10 keV) and protons (approximately 0.3-10 MeV) in water: partitioning of energy and collision events. | An event-by-event Monte Carlo simulation code for track structure studies is described. In the present form the code transports protons (approximately 0.3-10 MeV) and electrons (approximately 10 eV-10 keV) in a water medium in the gas phase approximation. For the type of particles and energy range considered, ionization, electronic excitation and electron elastic scattering are the most important collision events accounted for in the transport simulation. Efforts were made to ensure that the analytic representation of the various interaction cross sections rests on well established experimental data and theory. For example, the secondary-electron spectrum as well as partial and total ionization cross sections are represented by a semitheoretical bining Bethe's asymptotic expansion and binary-encounter theory. Binding effects for five levels of ionization and eight levels of electronic excitation of the water molecule are explicitly considered. The validity of the model cross sections is examined against available experimental data and theoretical predictions from other similar studies. Results pertaining to the partitioning of energy loss and interaction events for the first-collision probability and nanometre-size track segments are presented. |
11098898 | Comparison of dosimetry recommendations for clinical proton beams. | The formalism and data in the two most recent dosimetry mendations for clinical proton beams, ICRU Report 59 and the ing IAEA Code of Practice, pared. Chamber calibrations in terms of air kerma and absorbed dose to water are considered, including five different cylindrical ionization chamber monly used in proton beam dosimetry. The methodology for both types of calibration for ionization chambers is described in ICRU Report 59. The procedure based on air kerma calibrations pared with an alternative formalism based on IAEA Codes of Practice (TRS-277, TRS-381), modified for proton beams. The new IAEA Code of Practice is exclusively based on calibrations in terms of absorbed dose to water and a parison with ICRU Report 59 mendations is made. Common to the two formalisms are the fundamental quantities Wair and w(air) and their atmospheric conditions of applicability. The difference in the mended values of the ratio w(air)/Wair (protons to 60Co) is as large as 2.3%. The use of Wair and w(air) values for dry air (IAEA) and for ambient air (ICRU) is a contribution to the discrepancy, and the ICRU usage is questioned. For air kerma based chamber calibrations, ICRU Report 59 does not take into account the effect of positions of the build-up cap and chamber wall on the calibration beam quality. For the chamber types included in the study, this introduces discrepancies of up to 1.1%. Combined with differences in the mended basic data, discrepancies in absorbed dose determination in proton beams of up to 2.1% are found. For the absorbed dose to water based formalism, differences in the formalism, notably the omission of perturbation factors for 60Co in ICRU 59, and data yield discrepancies in calculated kQ factors, and in absorbed dose determinations, between -1.5% and +2.6%, depending on the chamber type and the proton beam quality. |
11098899 | A modified polymer gel for radiotherapy dosimetry: assessment by MRI and MRS. | The characteristics of a new formulation of polymer gel are assessed for MRI-based radiotherapy dosimetry. The gel, based on the first BANG gel formulation, replaces acrylamide with the less toxic monomer sodium methacrylate. The relationship between MR T2 relaxation time and radiation dose for the gel formulation was studied using spin-echo imaging. Proton magnetic resonance spectroscopy was also used to assess the position as a function of dose. The effect of gel pH on the dose-response and baseline R2 was then investigated. A calibration performed on gel without pH modulation (pH = 6.6) revealed a dose-response of 0.14 s(-1) Gy(-1) within the range 0-8 Gy. The baseline R2 increases with pH above neutrality, rising from 1.2 s(-1) at pH = 5.1 to 5.0 s(-1) at pH = 10.1. The dose-response is also pH dependent, having a minimum value of 0.09 s(-1) Gy(-1) at pH = 10.1 and peaking at 0.21 s(-1) Gy(-1) at pH = 7.7. Undertaking proton spectroscopy on the gels enabled resonances associated with the monomer and co-monomer to be studied. By integrating the peaks from the respective monomers and normalizing to the signal at 0 Gy it was shown that only 50% of the methacrylate monomer was used at 10 Gy, whereas 80% of the co-monomer was used at this dose. The data indicate that this gel has a reduced toxicity and parable dose response to the previously reported BANG gel. In addition, the performance of the gel can be optimized by controlling the pH. MR spectroscopy revealed that the crosslinking co-monomer is consumed more readily than the monomer, which is in agreement with positional studies. |
11098900 | Additional factors for the estimation of mean glandular breast dose using the UK mammography dosimetry protocol. | The UK and European protocols for mammographic dosimetry use conversion factors that relate incident air kerma to the mean glandular dose (MGD) within the breast. The conversion factors currently used were obtained puter simulation of a model breast with position of 50% adipose and 50% glandular tissues by weight (50% glandularity). Relative conversion factors have been calculated which allow the extension of the protocols to breasts of varying glandularity and for a wider range of mammographic x-ray spectra. The data have also been extended to breasts of pressed thickness of 11 cm. To facilitate the calculation of MGD in patient surveys, typical breast glandularities are tabulated for women in the age ranges 40-49 and 50-64 years, and for breasts in the thickness range 2-11 cm. In addition, tables of equivalent thickness of polymethyl methacrylate have been provided to allow the simulation for dosimetric purposes of typical breasts of various thicknesses. |
11098901 | Estimation of mean glandular dose for mammography of augmented breasts. | The standard quantity used to relate breast surface exposure to radiation risk is the mean dose received by the radiation sensitive tissue contained within the female breast, the mean glandular dose (MGD). At present, little is known about the MGD received by women with breast implants as there is no technique available to facilitate its calculation. The present work has involved modification of the conventional method for MGD estimation to make it applicable to women with augmented breasts. The technique was used to calculate MGDs for a cohort of 80 women with breast implants, which pared with similar data calculated for a total of 1258 non-augmented women. Little difference was found in median MGD at pressed breast thickness. At high breast thickness, however, the MGDs received by women with augmented breasts were found to be considerably lower than those relating to their non-augmented counterparts. |
11098902 | A comparison of normalization effects on three whole-body cylindrical 3D PET systems. | Normalization coefficients in three-dimensional positron emission tomography (3D PET) are affected by parameters such as camera geometry and the design and arrangement of the block detectors. In this work, ponents for three whole-body 3D-capable tomographs (the GE Advance, the Siemens/CTI962/HR+ and the Siemens/CTI951R) pared by means of a series of scans using uniform cylindrical and rotating line sources. Where applicable, the manufacturers' normalization methods are validated, and it is shown that these methods can be improved upon by using previously published normalization protocols. Those architectural differences between the three tomographs that affect normalization are discussed with a view to drawing more general conclusions about the effect of machine architecture on normalization. The data presented suggest that uniformity of system response es easier to achieve as the uniformity of crystal response within the detector block is improved. |
11098903 | Simultaneous reconstruction of internal tissue region boundaries and coefficients in optical diffusion tomography. | In this paper we propose a new numerical method to the inverse problem in optical diffusion tomography. We consider the reconstruction of the diffusion and absorption coefficients (kappa, mu(a)) within a domain omega which is known to consist of a set of disjoint regions of distinct tissue types. The assumption is that the regions of different tissues are bounded by smooth boundary curves and have constant absorption and diffusion coefficients. The goal in the proposed method is to reconstruct simultaneously the boundaries of the tissue regions together with the absorption and diffusion coefficients within these regions. The solution of the problem is based on the finite element method and subdivision of the elements. The performance of the proposed method is evaluated by simulations in which the optical parameters (kappa, mu(a)) are relevant in medical applications of optical tomography. It is shown that the proposed method is able to recover both the boundaries and the coefficients with good accuracy. |
11098904 | Dielectrospectroscopic monitoring of early embryogenesis in single frog embryos. | Dielectric spectroscopy has been used to monitor the early embryogenesis of frog (Xenopus laevis) eggs. The dielectric spectra of a single egg in suspension over the frequency range 10 Hz to 10 MHz were collected at various stages of its development. The uncleaved egg showed a dielectric dispersion with a narrow distribution of relaxation times. After the first cleavage, the dielectric spectra were posed of two subdispersions. In the cleavage process, up to the morula stage, changes in the spectra were quantitatively simulated by the 'cell-aggregate' model in which the embryo is regarded as a concentrated suspension of shell-spheres that correspond to the blastomeres (i.e. the cells within the embryo). In the stages from the morula to the blastula, the changes in the dielectric spectra were explained as due to a reduction in the size of the blastomere panied by an expansion of the blastocoel (i.e. the central cavity in the embryo) using the 'vesicle-inclusion' model that is a cell aggregate covered with a less conducting shell corresponding to the outermost layer of tightly interconnected cells. |
11098906 | Treatment planning for heavy-ion radiotherapy: calculation and optimization of biologically effective dose. | We describe a novel approach to treatment planning for heavy-ion radiotherapy based on the local effect model (LEM) which allows us to calculate the biologically effective dose not only for the target region but also for the entire irradiation volume. LEM is ideally suited for use as an integral part of treatment planning code systems for active dose shaping devices like the GSI raster scan system. Thus it has been incorporated into our standard treatment planning system for ion therapy (TRiP). Single intensity modulated fields can be optimized with respect to a homogeneous biologically effective dose. The relative biological effectiveness (RBE) is calculated separately for each voxel of the patient CT. Our radiobiologically oriented code system has been used since 1995 for the planning of irradiation experiments with cell cultures and animals such as rats and minipigs. It has been in regular and successful use for patient treatment planning since 1997. |
11098905 | Treatment planning for heavy-ion radiotherapy: physical beam model and dose optimization. | We describe a novel code system, TRiP, dedicated to the planning of radiotherapy with energetic ions, in particular 12C. The software is designed to cooperate with three-dimensional active dose shaping devices like the GSI raster scan system. This unique beam delivery system allows us to select bination from a list of 253 individual beam energies, 7 different beam spot sizes and 15 intensity levels. The software includes a beam model adapted to and verified for carbon ions. Inverse planning techniques are implemented in order to obtain a uniform target dose distribution from clinical input data, i.e. CT images and patient contours. This implies the automatic generation of intensity modulated fields of heavy ions with as many as 40000 raster points, where each point corresponds to a specific beam position, energy and particle fluence. This set of data is directly passed to the beam delivery and control system. The treatment planning code has been in clinical use since the start of the GSI pilot project in December 1997. Forty-eight patients have been successfully planned and treated. |
11098907 | The width of margins in radiotherapy treatment plans. | Publication of ICRU Reports 50 and 62 has highlighted the need to devise protocols for the process of drawing the planning target volume (PTV) around the clinical target volume (CTV). The margin surrounding the CTV should be wide enough to account for all geometric errors so that no part of the CTV accumulates a dose less than, for instance, 95% of that prescribed. One approach to the problem has been to draw a margin around the CTV delineated at the treatment preparation stage which is sufficiently wide that the mean position of the CTV will be passed in a specific percentage of cases, for example 90%. This accounts for the systematic errors. A further margin is then drawn to account for random set-up and organ-motion uncertainties during treatment. The width of this second margin has previously been shown to be 1.64(sigma - sigmap). Here sigma, a vector quantity, is the standard deviation which results from convolving the penumbra spread function of standard deviation sigmap with the Gaussian distributions of the daily positional uncertainties of organ motion and set-up error. However, it is shown in this paper that the calculation should take into account the beam configuration of the treatment plan. In a typical coplanar multibeam plan, usually in the transverse plane, any given edge of the target volume is normally defined by a single beam or two parallel and opposed beams. However, because of the presence of the other beams, the effect of the blurring of the edge-defining beam(s) is reduced, which changes the value of the required margin to beta (sigma - sigmap) where, for example, beta can be as low as 1.04 in the transverse plane of a three-beam plan. The width of the required margins is calculated for up to six beams and presented in a table. It is shown that, while the table was derived using an idealized plan of equally weighted plane beams irradiating a spherical target, it is also valid for non-uniform beam weightings, wedged-beam plans, target volumes of general shape and intensity-modulated radiotherapy (IMRT). |
11098908 | A new concept of multileaf collimator (the shuttling MLC)--an interpreter for high-efficiency IMRT. | This paper proposes a radically new concept for a multileaf collimator for a photon linear accelerator for delivering IMRT with high monitor-unit efficiency. The concept is to consider each M (rows) x N (columns) two-dimensional intensity-modulated beam (2D IMB) as a set of N/2 M (rows) x 2 (columns) areas of modulation. Each area is then delivered by a set of M shuttling attenuating elements (called here the shuttling MLC) with a very high monitor-unit efficiency. The elements shuttle between each of the two prising the M x 2 area and the modulation is provided by the variation in dwell time of the elements. The principles of this shuttling multileaf collimator are discussed and examples illustrating its operation are given. The main achievement reported in this paper is the development and robust testing of an interpreter which describes the position-time course of movement of the elements as a function of monitor units. This interpreter fully accounts for leakage transmission through the elements. pletely avoids the across-the-rows tongue-and-groove underdose. A large number of ID and 2D IMBs have been subjected to this interpreter and it is shown that for random patterns of fluence the SMLC is more monitor-unit efficient than the Bortfeld-Boyer technique (the most efficient with a conventional MLC) when the modulation is highly structured. |
11098909 | Elimination of field size dependence of enhanced dynamic wedge factors. | Enhanced dynamic wedge factors (EDWF) are characterized by a strong field size dependence. In contrast to physical wedge factors, the EDWF decrease as the field size is increased: for 6 MV 60 degrees wedge, the EDWF decreases by 50% when the field size is increased from 4 x 4 cm2 to 20 x 20 cm2. A method that eliminates the field size dependence of EDWF was developed and investigated in this work. In this method, the wedged field shape is determined by a multileaf collimator. The initial position of the moving Y jaw is determined by the field size and the stationary Y jaw is kept fixed at 10 cm for field sizes < or = 20 cm in the wedged direction. For all other fields, the stationary Y jaw setting is determined by the field size. The modified method results in EDWF that are independent of field size, with no change in the wedge dose distribution pared with the conventional use of EDW. |
11098910 | Modified sector-integration method for predicting the output factors of electron beams including extended source to surface distance. | A modified sector-integration method is presented that can predict the output factors of irregular shaped electron fields even in the case of extended source to surface distance (SSD). The model takes as input measured output factors for circular inserts of various radii. These circular fields were measured at SSDs of 100, 105 and 110 cm to determine the effective source distance as a function of radius (ESD(r)). For an arbitrary electron field at any SSD, the shape is divided into small sectors, and the contribution calculated from the radius and ESD(r). The calculated output factors were verified by direct measurements of various types of electron fields mainly based on clinical use. The energies modelled were 8, 10 and 12 MeV for applicator sizes of 10 cm x 10 cm and 14 cm x 14 cm (defined at 95 cm). The calculated values agreed with the measured data within 1% for the various rectangular cutouts including extended source to surface distance. We retrospectively modelled 97 patient inserts of irregular shape, and found agreement within 2% of measured values. |
11098911 | The feasibility of MRI-guided whole prostate ablation with a linear aperiodic intracavitary ultrasound phased array. | Over the past decade, numerous minimally invasive thermal procedures have been investigated to treat benign prostate hyperplasia and prostate cancer. Of these methods, ultrasound has shown considerable promise due to its ability to produce more precise and deeper thermal foci. In this study, a linear, transrectal ultrasound phased array capable of ablating large tissue volumes was fabricated and evaluated. The device was designed to patible for use with MRI guidance and thermometry. The intracavitary applicator increases treatable tissue volume by using an ultrasonic motor to provide a mechanical rotation angle of up to 100 degrees to a 62-element 1D ultrasound array. An aperiodic array geometry was used to reduce grating lobes. In addition, a specially designed Kapton interconnect was used to reduce cable crosstalk and hence also improve the acoustic efficiency of the array. MRI-guided in vivo and ex vivo experiments were performed to verify the array's large-volume ablative capabilities. Ex vivo bovine experiments were performed to assess the focusing range of the applicator. The array generated foci in a 3 cm (2 to 5 cm from the array surface along the axis normal to the array) by 5.5 cm (along the long axis of the array) by 6 cm (along the transverse axis of the array at a depth of 4 cm) volume. In vivo rabbit thigh experiments were performed to evaluate the lesion producing capabilities in perfused tissue. The array generated 3 cm x 2 cm x 2 cm lesions with 8 to 12 half-minute sonications equally spaced in the volume. The results indicate that transrectal ultrasound coagulation of the whole prostate is feasible with the developed device. |
11098912 | How to apply a discrete vessel model in thermal simulations when only incomplete vessel data are available. | For accurate predictions of the temperature distribution during hyperthermia treatment a thermal model should incorporate the individual impact of discrete vessels. In clinical practice not all vessels can be reconstructed individually. This paper investigates five possible strategies to model the thermal impact of these missing vessels. A tissue volume with a detailed, realistic, counter-current discrete vasculature is heated and the steady-state temperature distribution is calculated using our Discrete Vasculature (DIVA) thermal model. To mimic plete discrete vasculatures the full tree is gradually stripped, that is, the number of discretely described vessels is reduced in four steps until no discrete vessels are left. At each strip level the steady state temperature distribution is calculated for five different strategies to model the missing vessels. The strategies all use a local or global heat sink model in addition to the discrete vasculature. The resulting temperature distributions pared with the full tree simulation. With increasing strip level the correspondence with the full tree simulation deteriorated for all strategies. An optimal strategy was found to model the missing vessels depending on the available angiographic data. It was also found that simulations with a decreased number of discrete vessels, or no vessels at all, yield temperatures which are too high. Theoretically this can pensated by increasing the thermal conductivity; finding the optimal value is done empirically. |
11098913 | Decreased entropy of symbolic heart rate dynamics during daily activity as a predictor of positive head-up tilt test in patients with alleged neurocardiogenic syncope. | Entropy measures of RR interval variability during daily activity over a 24h period pared in 30 patients with a positive head-up tilt (HUT) test and 30 patients with a negative HUT test who had a history of alleged neurocardiogenic syncope. Two different entropies, approximate entropy (ApEn) and entropy of symbolic dynamics (SymEn), were employed. In patients showing a positive HUT test, the entropies were significantly decreased pared with the patients with a negative HUT test. In addition, SymEn in the patients with a negative HUT test was significantly lower than in the normal controls. Discriminant analysis using SymEn could correctly identify 89.3% (520/582) of the 1 h RR interval data of the patients with a positive HUT test regardless of the time of day. Baseline entropies of heart rate dynamics during daily activity were found to be significantly lower in patients with alleged neurocardiogenic syncope and a positive HUT test than in those with the same history but with a negative HUT test. The decreased entropy of symbolic heart rate dynamics may be of predictive value of a positive HUT test in patients with alleged neurocardiogenic syncope. |
11098914 | Direct recovery of regional tracer kinetics from temporally inconsistent dynamic ECT projections using dimension-reduced time-activity basis. | We present an algorithm of putational cost which is able to estimate kinetic model parameters directly from dynamic ECT sinograms made up of temporally inconsistent projections. The algorithm exploits the extreme degree of parameter redundancy inherent in binations of the exponential functions which represent the modes of partmental systems. The singular value position is employed to find a small set of orthogonal functions, the binations of which are able to accurately represent all modes within the physiologically anticipated range in a given study. The reduced dimension basis is formed as the convolution of this orthogonal set with a measured input function. The Moore-Penrose pseudoinverse is used to find coefficients of this basis. Algorithm performance is evaluated at realistic count rates using MCAT phantom and clinical 99mTc-teboroxime myocardial study data. Phantom data are modelled as originating from a Poisson process. For estimates recovered from a single slice projection set containing 2.5 x 10(5) total counts, recovered tissue pare favourably with those obtained using putationally intensive methods. The corresponding kinetic parameter estimates (coefficients of the new basis) exhibit negligible bias, while parameter variances are low, falling within 30% of the Cramér-Rao lower bound. |
11098915 | Dual-window scatter correction and energy window setting in cerebral blood flow SPECT: a Monte Carlo study. | The image quality in SPECT studies of the regional cerebral blood flow (rCBF) performed with 99mTc-HMPAO is degraded by scattered photons. The finite energy resolution of the gamma camera makes the detection of scattered photons unavoidable, and this is observed in the image as an impaired contrast between grey and white matter structures. In this work, a Monte Carlo simulated SPECT study of a realistic voxel-based brain phantom was used to evaluate the resulting contrast-to-noise ratio for a number of energy window settings, with and without the dual-window scatter correction. Values of the scaling factor k, used to obtain the fraction of scattered photons in the photopeak window, were estimated for each energy window. The use of a narrower, asymmetric, energy discrimination window improved the contrast, with a subsequent increase in statistical noise due to the lower number of counts. The photopeak-window setting giving the best contrast-to-noise ratio was found to be the same whether or not scatter correction was applied. Its value was 17% centred at 142 keV. At the optimum photopeak-window setting, the contrast was improved by using scatter correction, but the contrast-to-noise ratio was made worse. |
11098916 | Ring filter to locate external boundaries in SPECT using scattered radiation. | A novel form of filter for SPECT is described, in which, after back projection and summation, the reconstructed signal is a measure of the total activity within a ring of specified radius, centre and width. The filter is applied to the problem of using Compton scattered radiation to locate external boundaries. In the simple case of the determination of the radius of a circular scattering body of known centre, the filter output would identify a transition region and define an appropriate threshold as the boundary was crossed. However it can also be applied to locate the boundaries seen in individual SPECT projections and hence trace out the envelope of the scattering body. Monte Carlo simulation based on 99mTc is used to test the performance of the filter in a range of situations, with encouraging results. |
11098917 | A three-dimensional ray-driven attenuation, scatter and geometric response correction technique for SPECT in inhomogeneous media. | The qualitative and quantitative accuracy of SPECT images is degraded by physical factors of attenuation, Compton scatter and spatially varying collimator geometric response. This paper presents a 3D ray-tracing technique for modelling attenuation, scatter and geometric response for SPECT imaging in an inhomogeneous attenuating medium. The model is incorporated into a three-dimensional projector-backprojector and used with the maximum-likelihood expectation-maximization algorithm for reconstruction of parallel-beam data. A transmission map is used to define the inhomogeneous attenuating and scattering object being imaged. The attenuation map defines the probability of photon attenuation between the source and the scattering site, the scattering angle at the scattering site and the probability of attenuation of the scattered photon between the scattering site and the detector. The probability of a photon being scattered through a given angle and being detected in the emission energy window is approximated using a Gaussian function. The parameters of this Gaussian function are determined using physical measurements of parallel-beam scatter line spread functions from a non-uniformly attenuating phantom. The 3D ray-tracing scatter projector-backprojector produces the scatter and ponents. Then, a 3D ray-tracing projector-backprojector is used to model the geometric response of the collimator. From Monte Carlo and physical phantom experiments, it is shown that the best results are obtained by simultaneously correcting attenuation, scatter and geometric pared with results obtained with only one or two of the three corrections. It is also shown that a 3D scatter model is more accurate than a 2D model. A transmission map is useful for obtaining measurements of attenuation and scatter in SPECT data, which can be used together with a model of the geometric response of the collimator to obtain corrected images with quantitative and diagnostically accurate information. |
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