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Biomedical subjects

S Fletcher

Publications and source records attributed to S Fletcher.

At least 145 records · Page 8Linked to original sources
PubMed1978

The affinity chromatography of transketolase.

A number of possible affinity adsorbents for transketolase (sedoheptulose-7-phosphate:D-glyceraldehyde-3-phosphateglycolaldehydetransferase, EC 2.2.1.1) were prepared. The behaviour of the enzyme from Candida utilis and from Baker's yeast on columns of these and of Blue Sepharose CL-6B was examined, together with the behaviour of the contaminating enzyme, ribulose 5-phosphate 3-epimerase (EC 5.1.3.1). A procedure for removing bound thiamine pyrophosphate by dialysis against EDTA was developed. The competitive inhibition of transketolase by oxythiamine and neopyrithiamine was measured and the Ki values obtained of 1.4 and 4.3 mM, respectively, were compared with the affinity of adsorbents prepared from these two inhibitors. Adsorbents containing bound thiamine pyrophosphate were relatively ineffective but those containing epoxy-linked neopyrithiamine and D-ribose 5-phosphate adsorbed the enzyme at pH 7.4 and it could be eluted in a specific manner.

Candida↗
PubMedDate not supplied

Haptoglobin typing in Zimbabwe.

The value of haptoglobins as a method of typing negroid blood in Zimbabwe has been evaluated. three hundred sixty-nine blood samples from negroid people were examined using gradient polyacrylamide gel electrophoresis. The method provides good differentiation of all phenotypes including the 2-1M variant. In addition data on haptoglobin types of animals, both domestic and wild, are presented.

Animals↗
PubMedDate not supplied

The spectrum of thromboembolization in the central circulation.

The right heart and great veins can be the harbinger of septic and aseptic thromboemboli, which can result in a spectrum of clinical syndromes. This report presents five distinct clinical scenarios of thromboembolization, the occurrence of which in the central circulation resulted in life-threatening sepsis and hemodynamic and pulmonary insufficiency. Recommendations for therapeutic intervention and a review of the literature also are presented.

Adult↗
PubMedDate not supplied

Specific cloning of DNA fragments unique to the dog Y chromosome.

A novel technique that enabled the specific cloning of a DNA fragment unique to the dog Y chromosome is described. The method involves competitive hybridization of DNA prepared from male dog lymphocytes with biotin-labeled DNA prepared from female dog lymphocytes. The biotinylated female-female and male-female hybrid DNA fragments were removed by capture with streptavidin-coated paramagnetic particles. Full-length double-stranded DNA was generated from the remaining fragments by using the Klenow fragment of DNA polymerase I, followed by direct cloning using a low-background ligation technique. Analysis of putative recombinant clones derived by this method has led to the identification of a fragment that hybridizes specifically to male dog DNA. The clones were selected initially on the basis of a differential signal obtained when hybridized to dilutions of male and female dog DNA immobilized on neural nylon membrane. To evaluate its suitability as a probe for trans-sexually grafted cells in transplantation studies, the fragment was labeled with digoxigenin and hybridized in situ to male and female dog tissue sections. The clone designated number 6.2 hybridized strongly to male dog nuclei. The cloning strategy employed could be extended to other studies in which competitive reassociation can be used to identify unique DNA sequences.

Animals↗
PubMedDate not supplied

Factors influencing maternal behavior in the hubb/hubb mutant mouse.

We examined the maternal behavior of hubb/hubb mutant mice and normal control (+/hubb) siblings. From previous observations we noted that mutants groom their pups less, suckle less than normal, and often cannibalize the young. To date, these observations had not been quantified. Although prolactin (PRL) is linked to maternal behavior, it was difficult to measure because of the hyperirratibility of the mutant mice. Consequently, dopamine (DA) and its metabolite, dihydroxyphenylacetic acid (DOPAC), were measured in the median eminence in brains of both normal and mutant mice. Tyrosine hydroxylase, the rate-determining step in dopamine synthesis, was localized in the brain by immunohistochemistry. Five mutant and nine normal dams were observed for pup retrieval and crouching. Mean time for pup retrieval was slower (p < 0.06) for mutants (28.09 s) than for normal dams (18.49 s). Crouching was the same for both strains. Mutant pups were cold to the touch, and not well groomed. Brains from both strains were examined at Day 11 and Day 18 of gestation and Day 2 and Day 11 of lactation. Qualitatively, tyrosine hydroxylase localization in the arcuate nucleus and median eminence was the same in both strains for the gestation samples. The decrease in staining observed from gestation to lactation in the normal mice was increased in the mutants. Dopamine was similar in both strains at all stages, but DOPAC was significantly higher at early lactation in the mutants. We do not assume an absolute inverse relationship between dopaminergic activities and prolactin, but it is likely that the increase in DOPAC in the mutant reflects a decrease in prolactin, which could contribute to the diminished maternal care in the mutants.

3,4-Dihydroxyphenylacetic Acid↗
PubMedDate not supplied

Strokes in the elderly - higher acute and 3-month mortality - an explanation.

AIM: Stroke is common in older people. The objective of the study was to determine if older stroke patients have a higher mortality and disability compared with younger patients for comparable stroke severity and pathology and whether there is an explanation for the difference. METHODS: A prospective study was undertaken in 296 consecutive patients admitted with acute stroke. Patients were studied for neurological features, pre-stroke functional disability, severity of stroke defined by stroke syndromes and pathology of stroke on CT scans (202 patients). Post-stroke disability was defined according to the functional status within 72 h of admission. A record was made of the intercurrent illness while the patients were in acute wards and of the risk factors. Patients were dichotomized into two age groups: younger group - up to 75 years (163 patients) and older group - over 75 years (133 patients). Outcome was measured according to (1) discharge status from acute wards, i.e., dead or alive, and (2) mortality at 3 months. RESULTS: Although there was no significant difference in severe clinical stroke syndromes (p = 0.72), CT scan features (p = 0.68) and pyrexia (0.38) between the two age groups, the older patients had significantly more disabling strokes as defined on Barthel Index (p = 0.015) and a higher mortality in the acute phase (p < 0.01) and at 3 months (p = 0.001). The older stroke patients had more severe pre-stroke disability (p < 0.001) and more severe neurological impairment for similar stroke severity and pathology. Early mortality was more influenced by pre-stroke global health than age whereas 3-month mortality was influenced by age to the exclusion of all other known prognostic factors. CONCLUSION: The older stroke patients have more disabling stroke and an increased mortality for a similar spectrum of stroke severity and pathology. The explanation for higher mortality of the older patients is the poor pre-stroke health and higher immediate post-stroke disability.

Acute Disease↗
PubMedDate not supplied

Extracorporeal whole body hyperthermia treatment of HIV patients, a feasibility study.

The literature supports that the retrovirus, Human Immunodeficiency Virus (HIV), which is thought to cause Acquired Immunodeficiency Syndrome (AIDS), is heat sensitive at temperatures which can be achieved in man. Invasive or non-invasive induction of whole body hyperthermia (WBH) has been used to treat an array of illnesses, primarily in the field of oncology, until recently. Non-invasive methods have proven to be less toxic than invasive means. However, new technology and refined patient management have shown a dramatic decrease in the side effects with extracorporeal whole body hyperthermia (EWBH). The Food and Drug Administration granted a prospective trial for six HIV positive/AIDS patients to undergo a single treatment of EWBH, with patients randomized to a core temperature of either 41 or 42 degrees C. All patients had failed antiretrovirals and experienced at least one episode of an opportunistic infection. Organetics, Ltd., PS-1 extracorporeal, centrifugal pump device was used to induce EWBH. Results of this feasibility study demonstrated the ability of this equipment and technique to induce EWBH with acceptable toxicity. It was not possible to assess efficacy in this small study.

Adult↗
PubMedDate not supplied

Management of myocardial infarction in the elderly: admission and outcome on a coronary care unit.

A data base of 1,511 patients admitted to a single Coronary Care Unit was analysed to examine the potential impact of thrombolytic therapy in elderly patients with myocardial infarction. Age was confirmed as a highly significant prognostic factor, and cost utility analysis showed that the cost of thrombolytic therapy with streptokinase in the elderly was lower per quality adjusted life year than in younger patients. However, median delay time of admission from onset of symptoms was significantly greater in this age-group, suggesting a need for a greater awareness of the benefits of thrombolytic therapy in elderly people.

Aged↗