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Biomedical subjects

R Thompson

Publications and source records attributed to R Thompson.

At least 235 records · Page 13Linked to original sources

An experimental evaluation of a model child life program.

A model child life program for hospitalized children between the ages of 3 and 13 was systematically developed and tested on a large number of stress, coping, adjustment, and surgical recovery variables. The results indicated that children who participated in the experimental program (N = 68) scored significantly better on 18 of the 21 outcome variables than did control children (N = 160) who did not participate in a full child life program. As in previous research and within the limitations of a quasiexperimental design, the results suggest that this type of systematic child life care has a significant, positive impact on hospitalized children.

Adaptation, Psychological↗

The Australian Mesothelioma Surveillance Program 1979-1985.

The Australian Mesothelioma Surveillance Program was planned in 1977 in order to improve diagnostic criteria, to monitor the incidence of the disease, to develop methods of counting lung fibres, and to explore occupational and other associations of mesothelioma. This paper presents a preliminary analysis of data that were collected between January 1, 1980 and December 31, 1985 on the pathological findings and the work and environmental history of 858 cases of mesothelioma. The annual incidence rate of mesothelioma in Australia was 15 per million population who were aged 20 years and over. This is more than the incidence rate of mesothelioma in any other country for which data are available. However, uncertainty over diagnostic criteria and the degree of ascertainment of cases places doubt on the validity of such comparisons. In 69% of cases, a history of work with or other exposure to asbestos was obtained. Due to the long interval between the first exposure to asbestos and the provisional diagnosis of a mesothelioma (up to 60 years), more than three-quarters of the 456 exposed cases first contacted asbestos in the years of its heavy use between 1930 and 1959. This article analyses cases by the industry and the occupation in which exposure to asbestos first occurred.

Adult↗

Clinical, biochemical and pathological study of perinatal lambs in a commercial flock.

The birth and fate of 818 lambs born to 571 ewes on a low-ground farm in the Scottish Borders with a history of substantial perinatal mortality were monitored with a range of physiological, biochemical and pathological measurements. In lambs which survived, the rectal temperature, birthweight and plasma concentrations of fructose, insulin, thyroxine and the third component of complement at birth, and the weight at four months of age, decreased with litter size. One hundred and thirty-seven lambs were stillborn or died within four days and seven others died later. The mothers of 77 per cent of these lambs had low condition scores, but the lamb deaths did not correlate significantly with the condition scores. From data relating to birthweight, temperature, packed cell volume and plasma composition it was deduced that placental insufficiency was involved in 24 per cent of these deaths; acute hypoxaemia at birth accounted for 35 per cent, inadequate thermogenesis for 12 per cent and starvation for 13 per cent. The remaining 16 per cent of dead lambs could not be assigned to any of these categories. Using only clinicopathological criteria, 37 per cent of the lamb deaths were attributed to antenatal influences which included immaturity, developmental anomalies, and degenerative or inflammatory changes. Thirty-three per cent of the deaths were due to post natal factors which included, in declining order of frequency, starvation, enteritis, misadventure, pneumonia, navel infections and septicaemia. No conclusions could be drawn from the pathological examinations alone in the remaining 30 per cent, although almost half of these had low rectal temperatures after birth, death being attributed to hypothermia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Do smoking prevention programs really work? Attrition and the internal and external validity of an evaluation of a refusal skills training program.

This study investigated the effects of a smoking prevention program that emphasized refusal skills training on 1730 adolescents in three high schools and six middle schools. Classes within these schools were randomly assigned to treatment or no-treatment conditions to avoid confounding schools with treatment condition. The effects of attrition on the internal and external validity of the study were examined. Although the results indicated an apparent effect of the program at the 1-year follow-up in deterring continued smoking among those who were smoking at pretest, this result may have been due to a higher rate of attrition among high-rate smokers in the treatment condition than in the control condition. Attrition also affected external validity. Across both conditions, subjects who were smoking at pretest and who were at risk to smoke were more likely to be missing at follow-up. The program did have an effect on the refusal skills of participants and the validity of this effect was not jeopardized by differential attrition.

Adolescent↗

How generalizable are the effects of smoking prevention programs? Refusal skills training and parent messages in a teacher-administered program.

This study investigated both substantive and methodological issues associated with school-based smoking prevention programs. Substantive issues included the efficacy of a refusal skills training curriculum and of parent messages mailed to students' homes. Methodological issues included the effects of assigning classrooms versus entire schools to experimental conditions and determination of the effects of attrition on internal and external validity. Results revealed differential impact for different subgroups of adolescents. The refusal skills program produced lower rates of smoking than the control condition for students who were smokers at the pretreatment assessment but may have produced detrimental effects among males who were nonsmokers at pretest. The provision of parent messages did not affect outcome. Method of assignment (schools versus classrooms) failed to produce significant effects, and attrition did not affect internal validity. However, the above differential findings, as well as the impact of attrition on external validity, raise questions concerning the generalizability of smoking prevention programs.

Adolescent↗

Risk factors and the Child Behavior Checklist in a child mental health center setting.

The relationship between risk factors and the severity and type of childhood disorder, as measured by parent-completed Child Behavior Checklists, was examined for 768 children, ages 4-16, seen at a child mental health center. Regression analyses revealed no significant relationships between any combination of risk factors and the total number of behavior problems, internalizing, or externalizing scores for the entire group, males and females separately, or for the age and sex groupings of 6- to 11- and 12- to 16-year-olds. Chi-square tests revealed no relationship of profile type with any risk factor or with total number of risk factors. Implications for broad-based child assessment and risk factor research within a clinical population are discussed.

Adolescent↗

Impact of neodecortication on colon motor response to a meal in the rat.

The colon motor response to a meal consisting of 100 mM of sodium oleate was assessed before and after neodecortication in male Sprague-Dawley rats. Recording probes were anchored surgically in the ascending and descending colon. Pressure changes were recorded on a dynograph using a low-compliance perfusion system. A motility index took into account the amplitude, duration, and frequency of contractions. Neodecortication increased the motility index of the distal colon in the fasting state. However, removal of the cerebral cortex did not affect significantly the colon motor response to a meal. Meal stimulation increased the motility index before and after neodecortication. These findings suggest that resting colonic motor activity is increased after neodecortication, probably through the loss of an inhibitory influence of the central nervous system; and the cerebral cortex is not required for the colon response to a meal in the rat.

Animals↗

Comparative toxicity and carcinogenicity of two chlorinated paraffins in F344/N rats and B6C3F1 mice.

The toxicity and carcinogenicity of chlorinated paraffins containing C12 with 60% Cl, and C23 with 43% Cl, were assessed in prechronic and 2-year gavage studies using F344/N rats and B6C3F1 mice of both sexes. Single administrations of chlorinated paraffins were nonlethal in rats and mice, but repeated-dose and 2-year studies demonstrated toxic responses that differed with the paraffins. The C23,Cl43% paraffin produced a granulomatous inflammation in the liver of female rats in 13-week studies, while the C12,Cl60% paraffin caused deaths of rats and mice in 16-day studies and marked liver enlargement in 13-week studies. In 2-year studies, the C23,Cl43% paraffin caused hepatic and lymphatic granulomatous inflammation and hyperplasia in both sexes of rats, and was associated with marginal increases in adrenal medullary pheochromocytomas in female rats and hepatocellular neoplasms in female mice and with clear increases in malignant lymphomas in male mice. The C12,Cl60% paraffin caused marked liver enlargement in rats and increased the severity of nephropathy in male rats and the incidence of nephropathy in female rats. C12,Cl60% also caused hepatocellular neoplasms in both sexes of rats and mice: kidney tubular cell adenomas and adenocarcinomas in male rats, thyroid follicular cell neoplasms in female rats and female mice, and a marginal increase in mononuclear cell leukemia in male rats. Thus, the short-chain, heavily chlorinated paraffin appears to have a greater potential for chronic toxicity and carcinogenicity than the longer-chain, lightly chlorinated paraffin. Both paraffins have been reported to be nonmutagenic in bacteria. (National Toxicology Program (1986) Technical Report, NIH Publications 86-2561 and 86-2564).

Animals↗

Further lesion studies on the neuroanatomy of mental retardation in the white rat.

Prompted by recent findings suggesting that the basal ganglia and possibly the limbic midbrain area and brainstem reticular formation may be represented within the general learning system of the rat brain, the current study was undertaken to assess the learning ability of different groups of young rats prepared with bilateral lesions to either the caudatoputamen, nucleus accumbens, ventral pallidum, ventromedial thalamus, habenula, subthalamic nucleus, pedunculopontine tegmental nucleus, dorsal raphe, ventral tegmental area, anterior pretectal nucleus, superior colliculus, inferior colliculus, or red nucleus. The test battery included both appetitively (three distinct climbing detour problems) and aversively (visual discrimination, three cul maze, and an inclined plane discrimination) motivated learning tasks. Only those animals with lesions to the posterodorsal caudatoputamen, ventral tegmental area of Tsai, or superior colliculus were deficient in acquiring all six problems (suggestive of a generalized learning impairment) and therefore were viewed as being mentally retarded. The overall findings pertaining to the general learning system are interpreted within a conceptual framework based upon Spearman's two-factor theory of intelligence. The significance of these data for a brain-injured animal model of mental retardation is also discussed.

Animals↗

Varicella-zoster virus specifies a thymidylate synthetase.

A homology search of proteins predicted from the recently reported complete DNA sequence of varicella-zoster virus (VZV) revealed that the product of gene 13 was highly homologous to eukaryotic and prokaryotic thymidylate synthetases (TSs). The VZV protein was shown to be a TS by three functional tests. Firstly, a plasmid designed to express the native protein was able to complement a strain of Escherichia coli in which the natural TS gene is deleted. Secondly, in an enzyme assay for TS, extracts of the complemented strain were capable of releasing tritiated water from 2'-deoxy[5-3H]uridylate. Thirdly, these extracts contained a protein that bound isotopically labelled 5-fluoro-2'-deoxyuridylate, a ligand specific for the active site of TS. In addition, a novel ligand-binding protein was detected in human cells infected with VZV.

Base Sequence↗

Cardiac function: evaluation with fast-echo MR imaging.

Magnetic resonance (MR) imaging of the heart has, to date, been limited in its ability to evaluate cardiac function. The authors have implemented a technique for functional assessment of the heart using shorter echo times than those generally used for conventional spin-echo imaging. With these short echo times, multiple images can be obtained in a multisection mode approximately within the isovolumetric phases of the cardiac cycle. This permits a pair of image stacks to be obtained, one in end systole and the other in end diastole. With the use of a modified Simpson rule, left ventricular volume and ejection fraction were calculated and compared with results obtained from contrast material-enhanced ventriculography. Preliminary results indicate that this method has promise for the evaluation of a variety of functional parameters in the heart. The short acquisition times for this functional study permit it to be combined with a tissue characterization study within the time constraints of a clinical MR imaging session.

Heart Function Tests↗

Recombinant interferon alfa-2b in plaque-phase mycosis fungoides. Intralesional and low-dose intramuscular therapy.

A two-part clinical trial was conducted to determine the therapeutic efficacy of recombinant interferon alfa-2b in plaque-phase mycosis fungoides. In an initial randomized double-blind study, each of six patients had two representative plaques injected intralesionally with 1 X 10(6) U of recombinant interferon alfa-2b per site and two control plaques injected with placebo three times weekly for four consecutive weeks. Complete clinical regression of disease was observed at ten of 12 recombinant interferon alfa-2b sites compared with one of 12 placebo-treated sites four weeks after treatment with injections was stopped. Subsequently, in an open-labeled study, five of these patients were treated intramuscularly with 5 X 10(6) U of recombinant interferon alfa-2b three times weekly for four weeks and two patients were treated with a second, more extended course of therapy lasting 12 to 16 weeks. Three of the five patients treated systemically showed some improvement overall, but the responses were judged not to be clinically significant. The differential response observed from intralesional and intramuscular injections may be related to differences in concentration of recombinant interferon alfa-2b achieved in lesional skin by the two methods of administration.

Adult↗

Motor learning: nonspecific subcortical mechanisms in rats.

Adult rats with bilateral lesions in the globus pallidus, substantia nigra, median raphe, midbrain central gray, or pontine reticular formation were tested for novel motor skill learning (sliding a barrel bolt to the right in order to open a door leading to a reward). Significantly impaired learning was found in animals with lesions to globus pallidus, substantia nigra, median raphe, or pontine reticular formation. These results combined with earlier findings suggest that the foregoing subcortical structures along with the regions of the ventrolateral and parafascicular nuclei of the thalamus constitute a nonspecific mechanism involved not only in motor learning but in discrimination and maze learning as well. This mechanism is contrasted with the more fashionable specific mechanisms which are involved in particular classes of learning; the sensorimotor cortex, for example, would be a component of the specific mechanism underlying motor learning. A subcortical nonspecific learning mechanism may also inhabit the human brain, as suggested by the clinical condition of "subcortical dementia."

Animals↗

Interaction between L-threonine dehydrogenase and aminoacetone synthetase and mechanism of aminoacetone production.

A mixture of threonine dehydrogenase and aminoacetone synthetase will catalyze the conversion of L-threonine to glycine. The overall reaction likely involves the conversion of L-threonine, NAD+, and CoA to glycine, NADH, and acetyl-CoA. Physical separation of L-threonine dehydrogenase from aminoacetone synthetase results in the formation of aminoacetone and CO2 from their substrates. A physical interaction between threonine dehydrogenase and aminoacetone synthetase has been demonstrated by gel permeation chromatography and fluorescence polarization. Polarization of fluorescence measurements of threonine dehydrogenase and aminoacetone synthetase labeled with fluorescein isothiocyanate indicated the formation of a soluble active complex, with an apparent dissociation constant (Kd) of 5-10 nM and an apparent stoichiometry of 2 aminoacetone synthetase dimers/1 threonine dehydrogenase tetramer. Chemical experiments have identified aminoacetone as the enzymatic product of L-threonine dehydrogenase acting on L-threonine. These experiments involved trapping pyrrole derivatives, [3H]NaBH4 reduction, and coupling with plasma amine oxidase. Kinetic experiments also showed NADH, CO2, and aminoacetone to inhibit threonine dehydrogenase in a manner consistent with an ordered Bi-Ter kinetic mechanism. NAD+ is the lead substrate followed by threonine, and the products are released in the order: CO2, aminoacetone, and NADH.

Acetone↗

Detection of cerebral injury after total circulatory arrest and profound hypothermia by estimation of specific creatine kinase isoenzyme levels using monoclonal antibody techniques.

New 2-site labeled monoclonal antibody techniques were used to measure serially plasma levels of brain-type creatine kinase (CK-BB), heart-type creatine kinase (CK-MB) and muscle-type creatine kinase (CK-MM) during a 20-hour postoperative period in 24 infants after deep hypothermia and total circulatory arrest used in pediatric cardiac surgery. A control group of 7 children undergoing cardiovascular procedures without extracorporeal circulation or circulatory arrest also were studied. There were marked increases in CK-MB and CK-BB levels in the circulatory arrest group but not in the closed group. CK-BB increased from 3.2 +/- 0.5 to 27 +/- 10 ng/ml and CK-MB from 5.9 +/- 2.1 to 137 +/- 12 ng/ml. The CK-MM concentrations increased from 299 +/- 91 and 194 +/- 49 ng/ml to 1,220 +/- 274 and 1,322 +/- 142 ng/ml in the closed and circulatory arrest groups, respectively. Peak levels of CK-MB and CK-BB occurred an average of 133 and 127 minutes, respectively, after reperfusion. The half-time of CK-BB differed significantly from that of CK-MB (149 +/- 15 vs 359 +/- 20 minutes). The arrest time had a more marked effect on CK-BB concentration than on CK-MB and CK-MM concentrations. Arteriointernal jugular venous concentration differences were consistently negative for CK-BB in the circulatory arrest group, but not for CK-MM and CK-MB.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗