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Biomedical subjects

B A Wilson

Publications and source records attributed to B A Wilson.

At least 109 records · Page 6Linked to original sources
PubMed1993

E1A oncogene expression level in sarcoma cells: an independent determinant of cytolytic susceptibility and tumor rejection.

Ad2/5 E1A oncogene expression induces cytolytic susceptibility of rodent cells to natural killer lymphocytes. To determine whether the requisite thresholds of E1A oncoprotein expression differ for induction of cytolytic susceptibility as compared with other E1A-related activities, sarcoma cells expressing low or normal levels of E1A oncoproteins were compared for differences in morphological transformation, transactivation of viral genes, cytolytic susceptibility and tumorigenicity. Low-level E1A expression transformed sarcoma cells and transactivated the Ad5 E2A gene but did not induce the increased cytolytic susceptibility observed with normal levels of E1A expression. Furthermore, low-level E1A expressers retained the tumorigenicity of parental cells, whereas normal-level expressers were non-tumorigenic in hosts with intact natural killer (NK)-cell responses. In contrast to E1A, E1B oncogene expression caused no changes in morphological, cytolytic or tumorigenic phenotypes in these sarcoma cells. These data define an expression threshold for E1A-induced cytolytic susceptibility and associated NK-cell-dependent tumor rejection. The results suggest that the cellular mechanisms involved in E1A induction of cytolytic susceptibility differ from those involved in E1A-mediated cellular transformation and viral gene transactivation.

Adenovirus E1A Proteins↗
PubMed1992

MR imaging of diplomyelia.

We present an unusual case of duplication of the fifth lumbar vertebra and sacrum in a 6-year-old boy. The spinal cord was also duplicated and tethered by bone spurs bilaterally. The imaging features and the embryological basis of diplomyelia are discussed.

Abnormalities, Multiple↗
PubMed1991

E1A oncogene induction of cytolytic susceptibility eliminates sarcoma cell tumorigenicity.

The manner in which oncogenes influence tumorigenicity beyond their ability to immortalize cells is uncertain. We tested the hypothesis that, in addition to subverting cellular growth controls, oncogenes can actively determine tumor-inducing capacity by affecting neoplastic cell susceptibility to destruction by the host cellular immune response. The adenovirus type 5 E1A oncogene, which induces susceptibility to lysis by natural killer cells and encodes epitopes recognized by cytotoxic T lymphocytes, was transfected into highly tumorigenic sarcoma cells. E1A expression in these sarcoma cells eliminated their tumorigenicity in recipients with natural killer cell activity that was competent to lyse these E1A-positive targets. Thymus-dependent responses were not required for tumor rejection. These results indicate that oncogene-regulated cellular pathways that affect neoplastic cell susceptibility to natural killer cell lytic mechanisms may influence tumor development in the immunocompetent host.

Adenovirus Early Proteins↗
PubMed1991

Computer anxiety in nursing students.

The purpose of the study was to estimate the prevalence and severity of computer anxiety in beginning AD and BS nursing students and to determine the effect of hands-on computer experience on computer anxiety. The sample consisted of 272 volunteer subjects from five schools of nursing in a central southern state. Computer anxiety was measured using the Computer Anxiety Index by Maurer and Simonson. Factor analysis of the index was carried out to provide construct validity for the tool. Twenty-one percent of the subjects were found to have high computer anxiety. No significant difference in computer anxiety was demonstrated between associate degree (AD) and baccalaureate (BS) students. However, subjects with more hands-on computer experience had significantly less computer anxiety.

Adolescent↗
PubMed1990

Active-site mutations of diphtheria toxin: effects of replacing glutamic acid-148 with aspartic acid, glutamine, or serine.

Glutamic acid-148, an active-site residue of diphtheria toxin identified by photoaffinity labeling with NAD, was replaced with aspartic acid, glutamine, or serine by directed mutagenesis of the F2 fragment of the toxin gene. Wild-type and mutant F2 proteins were synthesized in Escherichia coli, and the corresponding enzymic fragment A moieties (DTA) were derived, purified, and characterized. The Glu----Asp (E148D), Glu----Gln (E148Q), and Glu----Ser (E148S) mutations caused reductions in NAD:EF-2 ADP-ribosyltransferase activity of ca. 100-, 250-, and 300-fold, respectively, while causing only minimal changes in substrate affinity. The effects of the mutations on NAD-glycohydrolase activity were considerably different; only a 10-fold reduction in activity was observed for E148S, and the E148D and E148Q mutants actually exhibited a small but reproducible increase in NAD-glycohydrolytic activity. Photolabeling by nicotinamide-radiolabeled NAD was diminished ca. 8-fold in the E148D mutant and was undetectable in the other mutants. The results confirm that Glu-148 plays a crucial role in the ADP-ribosylation of EF-2 and imply an important function for the side-chain carboxyl group in catalysis. The carboxyl group is also important for photochemical labeling by NAD but not for NAD-glycohydrolase activity. The pH dependence of the catalytic parameters for the ADP-ribosyltransferase reaction revealed a group in DTA-wt that titrates with an apparent pKa of 6.2-6.3 and is in the protonated state in the rate-determining step.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Diphosphate Ribose↗
PubMed1990

Effect of acidosis on skeletal muscle metabolism with and without propranolol.

Does the stimulatory effect of circulating catecholamines counteract the inhibitory effect of acidosis on skeletal muscle metabolism? To investigate this possibility, we studied gastrocnemii in dogs breathing either air (n = 10) or 4% carbon dioxide in air (n = 10) at rest and during contractions. In five dogs from each group, we infused propranolol into the arterial supply of the right and left muscles for 40 min. After 30 min of infusion, the left muscle was stimulated at 3 Hz for 10 min. During the 10th min of contractions, we removed and froze both muscles in liquid nitrogen. Oxygen uptake and blood flow to the left muscle prior to or during stimulation was not affected by acidosis either with or without propranolol. Glycogen concentration in resting muscle was unaffected by acidosis with or without propranolol. There was an acidosis related decrease of approximately 50% in the glycolytic intermediates (glucose 6-phosphate, fructose 1,6-diphosphate, alpha-glycerol phosphate, and dihydroxyacetone phosphate) in unstimulated muscles without beta-blockade. At rest, acidosis decreased muscle lactate by 50% with and 64% without propranolol, but lactate release was decreased only with acidosis without propranolol (1.4-0.1 mumols/kg.s). Acidosis without propranolol had no effect on the changes in glycogen concentration or the change in the concentration of glycolytic intermediates resulting from contractions. In beta-blocked muscle, the difference between stimulated and unstimulated concentrations of glycogen and glycolytic intermediates including lactate was 20-50% smaller with acidosis. Thus, with beta-blockade, the acidotic effects at rest disappeared and an inhibition of the metabolic adjustment to contractions appeared, indicating that circulating catecholamines do modify some metabolic effects of acidosis.

Acidosis↗
PubMed1990

Effects of humid air breathing during arm or treadmill exercise on exercise-induced bronchoconstriction and refractoriness.

Although it has been reported that inhibitory prostaglandins may be a causal factor in exercise refractoriness, it is still unclear whether exercise-induced bronchoconstriction (EIB) and/or other specific "exercise factors" are necessary to trigger their release and render a subject refractory to subsequent exercise. The purpose of this study was to determine whether non-EIB-producing exercise with the legs or arms could produce refractoriness to a standard treadmill challenge. Eight asthmatic subjects with EIB completed three sessions consisting of two exercise challenges separated by a 30-min rest. In all sessions, the second challenge was done on a treadmill while breathing dry air. Conditions for Challenge 1 were the following: Session A = treadmill, dry air; Session B = treadmill, humid air; Session C = arm cranking, humid air. All three conditions produced a significant degree of refractoriness. There was a tendency for the percent protection index to be greater for Session A; however, no significant differences were found among the three sessions. Therefore, it can be concluded that although both exercise and bronchoconstriction may play a role in producing the refractory period, neither severe bronchoconstriction nor intense exercise with the same muscle groups are required to produce refractoriness.

Adult↗
PubMed1990

Blood flow in the gluteus maximus of seated individuals during electrical muscle stimulation.

Blood flow was measured under the ischial tuberosites of seated individuals during electrical stimulation of the gluteus maximus muscles. Eight able-bodied and six spinal cord injured subjects were studied. Muscle blood flow was measured via radioactive tracer (133xenon) clearance. Retention of xenon in adipose tissue prevented accurate measurement of blood flow in cutaneous and subcutaneous tissue. Average muscle blood flow for both subject groups was increased during stimulation as compared to rest. All subjects showed an increase in muscle blood flow during stimulation. The statistical significance from a paired student t-test was greater for able-bodied subjects (p less than .05) than for spinal cord injured subjects (p = .12). The increase in muscle blood flow produced by electrical muscle stimulation in seated individuals supports the hypothesis that electrical muscle stimulation can help prevent pressure sores.

Buttocks↗
PubMed1989

Role of tumor necrosis factor-alpha in E1A oncogene-induced susceptibility of neoplastic cells to lysis by natural killer cells and activated macrophages.

NIH-3T3 cells transfected with adenovirus E1A oncogene cDNA were found to exhibit cytolytic susceptibility to murine NK cells and activated macrophages associated with a threshold level of oncogene product expression exceeding that required for morphological transformation. A similar correlation was observed between threshold levels of E1A gene product expression and target cell susceptibility to direct cytotoxicity by rTNF. Inhibition of splenic NK cell and peritoneal macrophage cytolysis by antisera specific for murine rTNF confirmed the importance of E1A-induced TNF susceptibility as one determinant of target cell cytolytic susceptibility. Anti-TNF antibody was, however, unable to block killing of E1A-expressing targets by the NK cell line, NKB61A2. These results suggest a direct link between the functions of E1A oncogene products and cellular mechanisms of action of TNF elaborated by host effector cells and indicate that E1A expression also affects target cell susceptibility to TNF-independent cytolytic mechanisms.

Adenoviridae↗
PubMed1989

How do old dogs learn new tricks: teaching a technological skill to brain injured people.

Little is known about the way people learn technological skills. This investigation was carried out to see how 100 brain injured, 50 controls and two amnesic patients performed on a task requiring them to learn a six-step programme for an electronic memory aid. Performance was correlated with other measures of memory to determine whether the technological skill was similar to a procedural learning task, a spatial memory task, a visual task, a verbal task or an amalgam of these. All controls but only 59 percent of the patients learned the task within three trials. The two amnesic patients also failed to learn the new skill. There was a high correlation between overall performance on a standardized test of everyday memory (the Rivermead Behavioural Memory Test) but little evidence that the technological skill was similar to a procedural learning task; nor was it specifically related to visual, verbal or spatial memory. It is concluded that a combination of skills is required to learn the technological task. Implications for the concept of procedural learning are discussed.

Adolescent↗
PubMed1989

The autobiographical memory interview: a new assessment of autobiographical and personal semantic memory in amnesic patients.

This paper describes a new technique for assessing "autobiographical" and "personal semantic" memory in amnesic patients and healthy controls. It provides evidence of the reliability and validity of the procedure, and reports an age-related temporal gradient in amnesic patients. The results are considered in terms of the severity, the rate of onset, and the duration of the amnesia; and a preliminary analysis is given of the findings in different diagnostic groups. The findings indicate that autobiographical and personal semantic memory show a consistent pattern of impairment, when a comparison is made which controls for the age of the memories and the subject's own past experience.

Adult↗
PubMed1989

Differential induction of cytolytic susceptibility by E1A, myc, and ras oncogenes in immortalized cells.

The E1A oncogene of adenovirus serotypes 2 and 5 induces susceptibility to the cytolytic effects of natural killer lymphocytes and activated macrophages when expressed in infected and transformed mammalian cells (cytolysis-susceptible phenotype). E1A and the oncogenes v-myc, long-terminal-repeat-promoted c-myc, and activated c-ras share the ability to immortalize transfected low-passage rodent cells. The cytolytic phenotypes of well-characterized rodent cell lines immortalized by these three oncogenes were defined. In contrast to target cells expressing the intact E1A gene, myc- and ras-expressing, immortalized primary transfectants were resistant to lysis by both types of killer cell populations. The same patterns of susceptibility (E1A) and resistance (myc and ras) to cytolysis were observed in oncogene-transfected continuous rat (REF52) and mouse (NIH 3T3) cell lines, indicating that differences in the cytolytic phenotypes associated with expression of these oncogenes are not due to cell selection during immortalization. The results suggest that the E1A oncogene may possess a functional domain that is different from those of other oncogenes, such as myc and ras, and that the activity linked to this postulated domain is dissociable from the process of immortalization.

Adenovirus Early Proteins↗
PubMed1987

Gender differences in cardiovascular and metabolic responses to cold and exercise.

This study was conducted because of the paucity of information concerning gender differences in the cardiovascular and metabolic responses to cold stress. Lightly clad men (n = 8) and women (n = 8) were tested in 21 and 5 degrees C environments during a 20-min rest, followed by 20 min each of 50, 100, and 150 W of exercise. At 21 degrees C there was no gender differences in VO2 or cardiac output. Cold lowered skin temperature more in women than in men, but women demonstrated no differences in heart rate, stroke volume, or VO2 at 5 and 21 degrees C. The women's noradrenaline levels in the cold were higher than comparable 21 degrees C data at rest and 50 W and increased with work intensity in both tests. In contrast, men had a lower heart rate, higher stroke volume, and higher VO2 throughout the 5 degrees C treatment compared with 21 degrees C. The men's noradrenaline response to 5 degrees C was similar to that of women at rest and 50 W, but the level subsequently declined at 100 and 150 W. Thus, the women do not show a heart rate-stroke volume shift in either resting or exercising states in cold environments. Furthermore, the data fail to support that either skin cooling or changes in noradrenaline cause the bradycardia and enhanced stroke volume seen in men.

Adult↗