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Biomedical subjects

T Shaw

Publications and source records attributed to T Shaw.

At least 73 records · Page 4Linked to original sources
PubMed1987

Attitudes towards mental illness: the influence of education and experience.

Female nursing students who had completed an instructional and experiential training program were compared on their perception, beliefs and opinions about mental illness with students who had just entered the same program. The results showed that students who had completed their training were better able to perceive the presence and severity of mental illness. Both groups favoured psychosocial etiology and psychosocial forms of treatment. There was no difference in their attitudes towards the mentally ill and both groups shared an overall optimism about prognosis. The implications of the lack of sophisticated knowledge about psychiatric disorders among mental health professionals are discussed.

Adult↗
PubMed1987

Development of a computerized sexual assessment laboratory.

Computer-assisted psychological assessment has been operational for 25 years. It has been well received by patients and shows a degree of reliability that is comparable to that of conventional testing. The authors report on the development of a computerized psychosexual assessment laboratory in a forensic facility housing convicted sex offenders who volunteered for treatment. The development of the laboratory was in response to the need for uniform psychosocial data on each resident that can be used for making better diagnoses, developing personalized treatment programs, and assessing treatment outcome. The process of selecting the psychological tests and programming them for interactive administration is described, as are the testing procedures using the penile plethysmograph with stimuli based on the Tanner developmental stages. A computer-assisted psychosocial assessment that produces a psychosocial history was developed. The laboratory's overall value in the treatment program is assessed.

Arousal↗
PubMed1986

Rapid and complete degradation of thymidine by human peripheral blood platelets: implications for genotoxicity assays.

Small-scale washed cell preparations obtained by Percoll density-gradient fractionation of whole blood were used to study the metabolic fate of [3H]thymidine supplied to isolated human blood mononuclear cells and platelets incubated for up to 24 h in vitro. Two cell fractions were monitored: low molecular weight compounds which were soluble in Triton X-100 and TCA were investigated by thin-layer chromatography, and high molecular weight components, distinguished by their Triton and TCA insolubility, were examined by agarose-gel electrophoresis. Under the conditions used, greater than 99% of added [3H]thymidine was very rapidly degraded. Catabolites were recovered in the Triton-soluble (cytoplasmic) fraction and the extracellular medium. A negligible proportion of added label was associated with Triton- and TCA-insoluble cell fractions. These results confirm and clarify previous data and have important implications for genotoxicity tests which employ in vitro leukocyte cultures.

Blood Platelets↗
PubMed1984

In vitro synthesis of low molecular weight proteins in human platelets: absence of labelled release products.

Isolated human blood platelets incubated at 37 degrees C in vitro incorporated labelled amino acids into compounds which included some low molecular weight (less than 80KDa) proteins, as determined by autoradiography after sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) under reducing conditions. Non-dialysable plasma factor(s) inhibited both uptake and incorporation, which although unaffected by Actinomycin D, was inhibited partly by Chloramphenicol and almost completely by Puromycin and Cycloheximide, results which confirm that synthesis is directed by pre-existing mRNAs, some of which is mitochondrial. Assuming that the mRNA coding for proteins which are truly "platelet specific" must be present in megakaryocyte cytoplasm, we investigated the possibility that such RNA may be sufficiently stable for its translation to continue in platelets. Although leakage from platelet alpha-granules and cytoplasm during incubation was negligible and platelets retained their secretory potential we were unable to detect radiolabelled proteins in thrombin-released material after incubation. We conclude that either alpha-granule proteins are not synthesised in platelets or their megakaryocyte progenitors, or that their mRNAs become degraded by the time platelets reach the peripheral circulation. Alternatively, the mechanism which concentrates these proteins in granules does not function in circulating platelets.

Amino Acids↗
PubMed1983

Cerebral vasomotor responsiveness during 100% oxygen inhalation in cerebral ischemia.

Cerebral vasoconstrictor responsiveness to 100% oxygen inhalation was measured in 149 subjects, including normal healthy volunteers and those with risk factors for cerebral arteriosclerosis (N = 87). Test results were compared among patients with hemispheric stroke and vertebrobasilar insufficiency (N = 62) with the 133Xe inhalation method. Normal volunteers without risk factors (N = 49), aged 25 to 86 years, showed symmetrical vasoconstriction. Asymptomatic subjects with risk factors (N = 38) and those with vertebrobasilar insufficiency (N = 25) had decreased hemispheric gray matter flow (Fg) values during rest, but vasoconstrictor responsiveness to 100% oxygen inhalation was not significantly reduced. In patients with acute hemispheric infarction, regional vasoconstrictor responsiveness to 100% oxygen inhalation was lost and/or paradoxically reversed; in patients with chronic hemispheric infarction, it was decreased. Testing vasomotor responses during hyperoxia is safe, clinically helpful, and demonstrates impaired vasomotor reactivity in infarcted regions.

Adult↗
PubMed1983

Cerebral vasomotor responses during oxygen inhalation. Results in normal aging and dementia.

Resting-state regional gray matter flow (Fg) values and cerebral vasoconstrictor responses induced by 100% oxygen inhalation were measured with the 133 Xe inhalation method in normal healthy volunteers aged between 15 and 86 years and in patients with senile dementia of Alzheimer's type (SDAT) or multi-infarct dementia (MID). Cross-sectional analysis revealed that there were linear decreases of oxygen responses with advancing age in 84 normal volunteers between the second to ninth decades. Eleven patients with SDAT showed bilateral and symmetrical reductions of resting-state Fg values compared with 22 age-matched normal healthy volunteers. Eight patients with MID showed no significant reduction of mean Fg values compared with normal controls and patients with SDAT. Oxygen vasoconstrictive responses in SDAT were symmetrical and similar to those seen in age-matched controls. Compared with patients with SDAT, patients with MID showed reduced oxygen vasoconstrictive responses that were asymmetrical between hemispheres as well as heterogeneous within hemispheres. Testing cerebral vasoconstrictor responses by 100% oxygen inhalation is helpful for differentiating SDAT from MID.

Aged↗
PubMed1983

Measurement of the density of human platelets and its relationship to volume.

New methods are described for platelet isolation and buoyant density determination using low-speed centrifugation in continuous density gradients of Percoll. The conditions used do not induce loss of granule or cytoplasmic markers and enable reproducible platelet frequency distributions to be obtained in linear density gradients. Such frequency distributions are normal with a mode of 1.0645 +/- 0.0015 g cm-3 (mean +/- SD, n=20). Platelets fixed in 0.1% glutaraldehyde show a modal density of 1.0712 +/- 0.0005 g cm-3. Content of protein, lactate dehydrogenase, beta-thromboglobulin and 3H-serotonin correlate closely with platelet numbers throughout the density distribution. The frequency distribution of platelet volume between 2.2 and 21 fl fits a log normal model and cell volume in density subfractions from the most dense to the least dense also approximate log normality. There is a positive correlation between mean platelet volume and buoyant density with a small increment between the least and the most dense extremes. Platelet subfractions separated by volume using a FACS II cell sorter differ substantially from each other in cell volume but the difference in mean density of four different volume fractions in negligible. In discontinuous density gradients of Stractan factors other than platelet density must influence the separation of platelets, as rebanding of platelets from interfaces shows a wide variation in buoyant density when analysed in continuous gradients. It is concluded that analysis of platelet buoyant density in continuous Percoll gradients supports the view that platelet density, like platelet volume, is determined primarily during thrombocytopoiesis and that volume and density are largely independent elements of platelet heterogeneity.

Adult↗
PubMed1982

Lecithin and memory training in suspected Alzheimer's disease.

Ten patients diagnosed clinically as having Alzheimer's disease (age range 54 to 73 years) were given 35 g/day of a 53% lecithin mixture for two weeks, in a double-blind crossover design. Patients received memory training during the lecithin condition and "placebo training" during the placebo drug condition. Repeated assessment with Buschke's Selective Reminding Procedure provided no evidence of a therapeutic lecithin effect either during the two week clinical trial or during longer follow-up trials. Noninvasive measurement of regional cerebral blood flow (nr CBF) by the 133Xe-inhalation method, and repeated EEG's also failed to demonstrate a therapeutic effect. These latter indices reflected a decline in cerebral function over the course of the study, a finding which paralleled clinical impressions in four of the patients. Follow-up trials of memory training under placebo and lecithin conditions provided some suggestion that memory training may lead to some immediate improvement in list-learning ability, but the improvement was not well maintained overtime.

Aged↗
PubMed1982

Stable xenon CT cerebral blood flow measurements computed by a single compartment--double integration model in normal aging and dementia.

Programs have been developed, using a single compartmental analysis model, that provide rapid computer derivation for values of both local cerebral blood flows (LCBF) and local tissue: blood partition coefficients (L lambda) using inhaled stable xenon gas (Xes) as the indicator. These programs are planned for utilization of raw data points derived from serial computed tomography scans made between the 3rd and 9th min after 35% Xes inhalation, while concentrations of end-tidal Xes (PEXes) are concurrently monitored. Double integration and least squares fitting permitted estimation of corresponding arterial (assumed from PEXes) and tissue Xes concentrations at each scanning interval during Xes saturation. Derived estimates for L lambda and LCBF values for each region of interest mathematically approximate values saturated to infinity. The method described can be utilized for any freely diffusible indicator. Cross-sectional analysis of results obtained in 13 normal healthy volunteers between 20 and 80 years of age showed no age-related changes in L lambda values but progressive decreases in blood flow of cortex, basal ganglia, and white matter with advancing age. In senile dementia of Alzheimer's type (SDAT, n = 8) L lambda values were likewise found to be unchanged, but cortical and thalamic gray matter LCBF values were significantly reduced compared to age-matched normal volunteers.

Adult↗
PubMed1980

Noninvasive regional cerebral blood flow measurements in dementia.

Regional cerebral blood flow measured in patients with dementias (N = 60) using xenon Xe 133 inhalation was compared with measurements in health volunteers (N = 70). Volunteers were age-matched (N = 15); another group was younger. In normal aging, there is progressive, diffuse reduction of weight and flow of gray matter (F1) but not of white matter. Therefore, age-matched control subjects are necessary in studies of dementia. In Alzheimer's disease (AD), F1 shows bilateral and symmetrical reduction. The F1 reduction correlated with atrophy estimated by computerized tomography, and duration and severity of dementia. In multi-infarct dementia (MID), bilateral hemispheric F1 was patchily reduced. Cerebral vasodilator response to 5 percent carbon dioxide inhalation was reduced in patients with MID but was normal in patients with AD. Patients with Wernicke-Korsakoff's dementia showed normal values. Patients with dementia due to multiple sclerosis showed significant F1 reduction compared with normal subjects. Standard behavioral activation in all patients with moderate to severe dementia failed to produce normal F1 increases.

Adult↗
PubMed1979

Effects of advancing age on regional cerebral blood flow. Studies in normal subjects and subjects with risk factors for atherothrombotic stroke.

Regional cerebral blood flow (rCBF) was measured by 133Xe inhalation in 46 normal volunteers, aged 21 to 63 years, and 14 neurologically asymptomatic subjects above age 40 with risk factors for atherothrombotic stroke, including hypertension, diabetes mellitus, and hyperlipidemia. In normal volunteers, there was diffuse and progresive reduction of gray matter flow and weight as well as increases of cerebrovascular resistance (CVR) with advancing age. Reduction of gray matter flow with advancing age appears to be attributed in part to neuronal atrophy and in part to cerebral arteriosclerosis. Regional increases of CVR and reduction of gray matter flow with advancing age were most evident in the middle cerebral arterial (MCA) distribution and were enhanced by the association of risk factors. Development of cerebral arteriosclerosis with age and/or risk factors appears to be most evident in MCA distribution.

Adult↗
PubMed1979

Regional cerebral blood flow measured by 133Xe inhalation in tracheostomized and laryngectomized men and women.

The question of contamination of cerebral clearance curves utilized for measuring regional cerebral blood flow by radioactivity derived from the nasopharyngeal air passages following inhalation of 133Xe was tested in patients with chronic tracheostomy. The peak counts for head curves were 5--9% higher when 133Xe was inhaled via a face mask than when inhaled via the tracheal stoma. Calculated flow values using standard recommended start-fit-times were not significantly different between these two different methods. Present results indicate that neither overestimation of fast flow values due to contamination from rapid 133Xe washout recorded from the air passages nor the underestimation of slow flow due to contamination from 133Xe trapped in the air sinuses produced significant measurement errors. However, if earlier start-fit-times were used, flow values were artificially high, particularly for brain stem/cerebellar probes because of an initial rapid decline in the head desaturation curves due to an arterial peak believed to be derived from the basilar artery.

Adult↗
PubMed1979

Noninvasive measurement of cerebral vasopasm in patients with subarachnoid hemorrhage.

Regional cerebral blood flow (rCBF) was measured as fast flow clearance (F1) and the initial slope index (ISI2) after inhalation of 133Xe in 30 patients with subarachnoid hemorrhage (SAH). Vasomotor responsiveness to reduction in end-tibal PECO2 was examined in those patients who could carry out this procedure satisfactorily as a test for the presence or absence of vasospasm. F1 and ISI2 were significantly reduced in patients with recent SAH compared to 35 age-matched normal volunteers. The degree of reduction of F1 and ISI2 correlated directly with severity of the neurological deficit graded according to the Hunt and Hess rating scale. Topographic reductions of rCBF correlated with angiographically demonstrated vasospasm or intracerebral hematoma. The degree of impairment of cerebral vasomotor responsiveness to reduction of PECO2 by hyperventilation also correlated with the severity of vasospasm demonstrated angiographically in 16 patients. The reductions of rCBF values were maximal during the first week after SAH but returned gradually toward normal by the 5th week. Individual patients with SAH whose lowest F1 values were above 50 ml/100 g brain/min tolerated surgical intervention best. Non-invasive measurements of rCBF after SAH appear to be helpful in estimating the presence and time course of vasospasm, in recognizing the development of normal pressure hydrocephalus, and in planning medical and surgical management.

Adolescent↗
PubMed1975

Characteristics of a Kenyan camelpox virus.

A virus was isolated from pock-like vesicular eruptions of camels in Northern Kenya. This virus was shown to be a pox virus with many characteristics of members of the Orthopox group. It appears to be identical with camelpox strains from Iran and has similar properties to certain East African variola strains.

Animals↗