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Biomedical subjects

C Thomas

Publications and source records attributed to C Thomas.

At least 415 records · Page 23Linked to original sources
PubMed1988

Neurologic outcome in aged rats after incomplete cerebral ischemia.

The effect of age on outcome after induced cerebral ischemia was tested in rats. Cerebral ischemia was produced by unilateral carotid ligation and hemorrhagic hypotension to 30 mm Hg (moderate ischemia) or 25 mm Hg (severe ischemia) in young (6 month) and old (26-28 month) rats anesthetized with 1 MAC halothane. Young rats had significantly better neurologic outcomes than old rats after similar ischemic challenges. This advantage disappears, however, when the inspired oxygen tension is altered to produce similar PaO2 in both age groups during ischemia. Measures of regional CBF with radioactive microspheres showed a 70% decrease in cortical blood flow in the ischemic cerebral hemisphere in both young and old rats. Plasma glucose concentrations increased from 150 to 250 mg/100 mL during ischemia in both age groups. Histologically, the brains showed similar signs of focal ischemic damage in striatum, hippocampus, and cortex in young and old rats. These results indicate that when blood pressure and respiratory factors are controlled experimentally during ischemia, young and aged rats have similar neurologic outcomes after cerebral ischemia.

Aging↗
PubMed1987

Giant axonal neuropathy: correlation of clinical findings with postmortem neuropathology.

We report the clinical and postmortem neuropathological findings in a case of long-standing giant axonal neuropathy. The patient, a caucasian male with kinky hair, was first seen at 4 years of age because of increasing unsteadiness of gait. Clinical examination showed nystagmus, cerebellar ataxia, distal sensory loss, and weakness. A sural nerve biopsy at 8 years of age revealed giant axonal neuropathy. The patient became increasingly demented and was incapacitated by weakness and ataxia; he died at 18 years of age. Histological examination of the brain and spinal cord showed numerous Rosenthal fibers, a distal axonopathy that most severely affected the corticospinal tracts, middle cerebellar peduncles, and posterior columns, and olivocerebellar degeneration.

Adolescent↗
PubMed1987

Luteal function in ectopic pregnancy.

Human chorionic gonadotropin, estradiol, progesterone, and 17-hydroxyprogesterone have been measured in the serum of 46 patients with ectopic pregnancy. All these hormones were significantly lower than in normal pregnancy. Unruptured ectopic pregnancy differed from the ruptured state by a lower serum human chorionic gonadotropin concentration, a slower human chorionic gonadotropin increment, a higher incidence of metrorrhagia, and an earlier diagnosis. The concentration of estradiol, progesterone, and 17-hydroxyprogesterone in the serum of patients with ectopic pregnancy was lower than could be expected from the decrease of human chorionic gonadotropin, often lower than in a normal luteal phase. It is suggested that, as long as ultrasonography fails to show an intrauterine pregnancy, the simultaneous determination of serum human chorionic gonadotropin and progesterone could aid in the early diagnosis of ectopic pregnancy and in the improvement of subsequent fertility; to that regard any progesterone level below 15 ng/ml in the presence of detectable amounts of human chorionic gonadotropin is highly suggestive of either a threatened abortion or an ectopic pregnancy, whatever the gestational age.

17-alpha-Hydroxyprogesterone↗
PubMed1987

Psychological effects of stomas--I. Psychosocial morbidity one year after surgery.

Sixty eight subjects who had undergone stoma surgery 12 months previously were assessed as to their psychiatric and social outcome. They had been previously also assessed at the 3rd month postoperatively. The majority had a diagnosis of bowel cancer (38) and smaller numbers had inflammatory bowel disease (15) or diverticular disease (15). 22% of the subjects had moderate or severe psychiatric symptoms and most of these had also shown similar disturbance at the 3 month assessment, indicating that the condition was longstanding. There was no significant difference in outcome between the diagnostic groups. The results also showed that ability to perform housework, leisure and sexual activities was affected in a number of subjects.

Adaptation, Psychological↗
PubMed1987

Psychological effects of stomas--II. Factors influencing outcome.

Sixteen patients with a moderate or severe anxiety and/or depression one year after stoma surgery were compared with 52 patients who had made a good psychiatric adjustment. Factors that were associated with an increased risk of psychiatric morbidity included a previous psychiatric history, postoperative physical symptoms and complications, inadequate advice and personality traits of neuroticism, anxiety and obsessionality.

Adaptation, Psychological↗
PubMed1987

H2, a temperate bacteriophage isolated from Bacillus amyloliquefaciens strain H.

Bacillus amyloliquefaciens strain H is lysogenic for a large temperate phage we call H2. H2 has a polyhedral head 85 nm in diameter and a tail of about 17 x 434 nm. H2 lysogenizes Bacillus subtilis between the tyrA and metB genes, and gives specialized transduction of metB and, at lower frequencies, of ilvD and ilvA. The phage carries a thymidylate synthase gene and converts thymine auxotrophs of B. subtilis to prototrophy. The H2 genome is a linear DNA molecule about 129 kb in length. DNA extracted from phage particles grown in B. subtilis is not cut by the restriction endonucleases HaeIII, Fnu4HI, Bsp1286I, and BamHI; the latter enzyme is produced by B. amyloliquefaciens strain H. The prophage in lysogenic B. subtilis cells can be cut by these enzymes. We have isolated H2 mutants that carry the transposon Tn917, or a mutation resulting in clear-plaque morphology, or both.

Bacillus↗
PubMed1987

A differentiation-defective concanavalin-A-resistant variant of a pluripotent embryonal carcinoma cell line.

A concanavalin-A(Con A)-resistant variant of the pluripotent mouse embryonal carcinoma cell line, PSA1-NG2, was isolated. This variant, designated NG2-2.16, fails to exhibit the extensive spontaneous differentiation displayed by PSA1-NG2 in colonies in vitro and in tumours in vivo. The molecular nature of the defect in NG2-2.16 cells was not revealed by quantitative studies of the binding, uptake and metabolism of tritiated Con A, or by Western blotting of membrane and whole cell homogenates, thus indicating the defect to be the result of a more subtle molecular alteration. Statistical evidence suggests that the same mutation is responsible for both the Con A resistance and the lack of spontaneous differentiation. NG2-2.16 cells were induced to differentiate by exposure to retinoic acid, suggesting that the mutation affects the regulation of differentiation rather than the potential for differentiation.

Animals↗
PubMed1987

Evaluating borderline students.

While it was difficult for our faculty to face the disparity which arose in deciding whether or not to pass Anne, many important points were raised which strengthened the evaluation process particularly in the case of the borderline student. Newer faculty members related uneasiness in being specific and directive with "borderline" students. Experienced faculty offered suggestions on overcoming this fear and finding support among peers. Open discussion provided a forum for the exchange of ideas and philosophies. Though no definitive solutions were uncovered we judged this workshop to be a valuable learning experience with broad appeal across a very diverse faculty.

Clinical Competence↗
PubMed1986

Improved high-affinity monoclonal antibody to iododeoxyuridine.

Three monoclonal antibodies (Mabs), IU-1, IU-4, and B-44 were evaluated in enzyme immunoassays (ELISA) and by flow cytometry for their abilities to recognize bromodeoxyuridine (BrdUrd)- and iododeoxyuridine (IdUrd)-substituted DNA's, nucleotides, and nucleosides. IU-4 is a new Mab, derived from mice immunized with 5-iodo-2'-deoxyuridine-5'-monophosphate (IdUMP) conjugated (IdUMP) conjugated through the phosphate group to albumin. This immunogen was selected to resemble IdUMP in DNA. In competition ELISA assays, IU-4 prefers IdUrd to BrdUrd and prefers halogenated nucleotides over the corresponding nucleosides. In both ELISA and flow analysis, IU-4 recognizes IdUrd in DNA at substitution frequencies at least as low as one IdUrd one per 1,000 normal bases. The high affinity of IU-4 for IdUrd-DNA contrasts with IU-1 and B-44, which show a strong binding dependency on the frequency of base substitution and require DNA that is essentially fully substituted with BrdUrd for binding in both flow and ELISA assays. The high affinity of IU-4 for IdUrd in DNA and its independence of IdUrd residue spacing make it a superior reagent for the quantitative labeling of halogenated thymidine analogues in whole cells.

Animals↗
PubMed1986

Graft-versus-host disease in the rat: cellular changes and major histocompatibility complex antigen expression in the liver.

Cellular changes in the liver were studied during an acute lethal graft-versus-host (GVH) disease in relation to the expression of major histocompatibility complex (MHC) antigens on different liver cells. Screening for MHC antigen expression revealed that control livers contained very few Ia+ cells: mainly cells in the portal tract interstitium and a small percentage of the Kupffer cells. The changes during an ongoing GVH reaction could be separated into those related to the sinusoid-associated cells, including the liver parenchyma, and those related to the portal-tract-associated cells, including periportal hepatocytes. In the sinusoids an increase in the number of Kupffer cells was seen, now all expressing Ia antigens. No damage to hepatocytes or other sinusoid-associated cells was observed. It is postulated that the increase in both number and Ia expression of the Kupffer cells is most probably due to an increased phagocytic uptake of blood-borne cellular debris and is not a result of extensive damage to hepatocytes. In the portal tracts expanding infiltrates were found composed of Ia+ T cells and macrophages (ratio 2:1). These infiltrates are probably due to a local accumulation of lymphocytes and macrophages as a result of an interaction of migrating donor-type alloreactive T cells with recipient type Ia+ cells present in the portal tract interstitium, which also interfered with normal recipient lymphocyte and macrophage traffic. Damage to portal-tract-associated cells was slight and confined to bile duct epithelial cells, which now expressed Ia antigens, and to periportal hepatocytes. In conclusion, these data do not indicate that damage to liver parenchyma plays a major role in the pathogenesis of an acute GVH reaction.

Acute Disease↗