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Biomedical subjects

J Brown

Publications and source records attributed to J Brown.

At least 973 records · Page 54Linked to original sources

Normal response to pregnancy in rats cured of streptozotocin diabetes by transplantation of one fetal pancreas.

We have investigated glucose homeostasis and insulin response to glucose in seven rats before, during and after pregnancy, who were previously successfully transplanted with a single fetal pancreas. Increased need for insulin during pregnancy provides an opportunity to test the reserve capacity of the transplanted organ. Plasma glucose in seven rats was normal before pregnancy (7.3 +/- 0.7 mmol/l), during pregnancy (6.6 +/- 1 mmol/l) and after parturition (6.7 +/- 0.3 mmol/l). Fasting plasma glucose was lower after parturition (5.1 +/- 1 mmol/l) than before pregnancy (6.1 +/- 0.7 mmol/l). The disappearance rate of injected glucose was the same before (2.3 +/- 0.2%/min) as after pregnancy (2.6 +/- 0.2%/min). Basal plasma insulin before pregnancy was elevated and there was no rise from glucose; after parturition the basal and pattern of response was normal. The total insulin content of the transplants (859 +/- 154 mU) was only 21% of that of normal rats; we conclude that this provides a reserve adequate for the needs of pregnancy.

Animals↗

Iridocyclitis.

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Complement System Proteins↗

The measurement of urinary steroid glucuronides as indices of the fertile period in women. World Health Organization, Task Force on Methods for the Determination of the Fertile Period, special programme of research, development and research training in human reproduction.

The concentrations of various estrogen glucuronides and pregnanediol-3 alpha-glucuronide have been measured in daily samples of early morning urine (EMU) and 24 h pooled collections throughout a total of 70 menstrual cycles (58 subjects). The immediate objective was to identify and assess the potential value of measuring hormone metabolites to locate the fertile period in women, with the ultimate aim of developing a non-invasive immunochemical test. The project was undertaken in five centres and the results showed that: (i) there was good agreement in the patterns and mean concentrations of metabolites between the centres; (ii) estrone-3-glucuronide should be the estrogen glucuronide selected for further study; (iii) the analysis of EMU provided information that was as useful as the corresponding measurements on pooled collections for 24 h; (iv) a rise in the concentration of estrone-3-glucuronide (50% over the mean of three preceding values) could be used to locate the start of the fertile period in greater than 90% of the ovarian cycles (from day LHmax -- 3 to day LHmax -- 7); attempts to locate the end of the fertile period by a threshold value or a defined rise in the level of pregnanediol-3 alpha-glucuronide were disappointing. A 50% rise over the mean of three preceding values in the derived concentration ratio of estrone-3-glucuronide/pregnanediol-3 alpha-glucuronide could be used to indicate the start of the fertile period, and a 50% decrease plus two days the start of the infertile period in greater than 80% of the ovarian cycles. The limitations, implications and future developments are discussed.

Adolescent↗

Effects on the 5-hydroxytryptamine-induced head-twitch of drugs with selective actions on alpha1 and alpha2-adrenoceptors.

Effects of agents with selectivity for the alpha1- or alpha2-adrenoceptor have been investigated on the head twitches induced by 5-HT injected into the cerebral ventricles in the mouse. Alpha-adrenoceptor agonists inhibited head-twitching with a rank order of potency: guanabenz, clonidine, phenylephrine, methoxamine. The antagonists yohimbine and piperoxane, potentiated the head-twitch frequency. These results suggest that there may be an involvement of an alpha2-adrenoceptor. Small doses of phenylephrine (s.c.) potentiated the head-twitch. Methoxamine, injected intracerebroventricularly potentiated the head-twitch only when alpha2-adrenoceptors were blocked by a small dose of yohimbine. Prazosin and thymoxamine inhibited the head-twitch, suggesting that alpha1-adrenoceptors also modulate this phenomenon. Yohimbine and phenylephrine increased the incidence of spontaneous head-twitches. A tonic noradrenergic input may be necessary for the occurrence of the head-twitch induced by 5-HT.

Adrenergic alpha-Agonists↗

A comparison between transient amnesias induced by two drugs (diazepam or lorazepam) and amnesia of organic origin.

The transient amnesias produced by drugs may have much in common with the more permanent amnesias associated with organic brain damage. This possibility was investigated using two benzodiazepines, diazepam and lorazepam, with medical student volunteers. In Experiment 1, 27 subjects received a 2ml intravenous injection of either diazepam (7.5 mg) or of lorazepam (3.0 mg) or of normal saline. In Experiment 2, a further 13 subjects were given lorazepam (2.5 mg) or saline. A double blind procedure was used. Neither drug had an appreciable effect on span-type short-term memory (except with 2-channel presentation). Both drugs produced severe anterograde amnesia in other forms of memory test: the amnesic effect of lorazepam lasted for several hours. This amnesia was not attributable to failures of perception. Lorazepam appeared to affect recognition even more than recall. In a test with lorazepam no evidence was obtained that the drug increases susceptibility to proactive interference. With both drugs, recall and recognition were unimpaired of material presented about 10 min before the injection; this shows that the drugs did not affect retrieval mechanisms.

Adult↗

In vitro demonstration of pyrimethamine resistance of "wild" Plasmodium falciparum in The Gambia.

The in vitro response of wild Gambian Plasmodium falciparum to pyrimethamine is described. Parasites were grown in 100 microliter cultures through schizogony. The number of rings present after 48 hours in drug-treated cultures was expressed as a percentage of the controls. Neither a medium and drug change after 24 hours nor different starting parasitaemias were found to affect the outcome of the assay, although a medium and drug change did increase the multiplication rate. 60 randomly taken pure P. falciparum infections were studied. 57 were sensitive. The ID50 and ID90 of drug-sensitive infections were 1.7 X 10(-9) M and 4.5 X 10(-9) M pyrimethamine respectively. Three infections were resistant (5%) with individual ID50 values of greater than 10(-6) M, 3 and 4 X 10(-9) M and ID90 values of greater than 10(-6) M, 8 and 9 X 10(-7) M.

Animals↗

Effect of postoperative immobilization after coronary artery bypass surgery.

Pulmonary complications, particularly atelectasis, occur frequently after coronary artery bypass (CAB) surgery. To determine the effect of early postoperative immobility on pulmonary complications, the authors randomly assigned 35 patients into two groups. One group remained in the supine position for the first 24 h. The second group had their body position systematically turned every 2 h for the first 24 h. Turning resulted in a significant decrease in postoperative fever (p less than 0.001) and a 32% reduction in the duration of the stay in the Surgical Intensive Care Unit (SICU). Turning did not affect the patient's hemodynamic stability or arterial blood gas measurements. The authors conclude that systematic turning of CAB patients can reduce postoperative morbidity.

Clinical Trials as Topic↗

Computers.

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Computers↗

Variation in alcoholism treatment orientation: differential impact upon specific subpopulations.

Treatment programs across the State of New York were studied to determine the differential impact of treatment orientations upon various types of alcoholism clients. 1340 patients from 17 alcoholism treatment programs were treated and followed up 3 and 8 months after treatment. The majority of the clients were categorized as either Behaviorally Impaired Drinkers (n = 205) or Alcoholics (n = 814). Each of the treatment programs were classified according to either Peer Group, Rehabilitation Professional, or Medical Orientations. Three different outcome measures were examined: abstinence, amount of alcohol consumed at follow-up, and improvement (life and drinking) at follow-up. The generalizable conclusions were that females had significantly better outcome (78% abstinent) when treated according to a medical orientation. Male Behaviorally Impaired Drinkers had better outcomes when treated in Rehabilitation Professional Orientation (74% abstinent) and male alcoholics had the best outcome in Peer Group (60% abstinent), although male alcoholics achieved similar abstinence rates in Medical (59.5%) and Rehabilitation (55%) orientations.

Alcohol Drinking↗

Calcium metabolism during rifampicin and isoniazid therapy for tuberculosis.

Calcium metabolism was studied in 83 patients during eighteen months' rifampicin and isoniazid therapy for tuberculosis by measurements including calcium, alkaline phosphatase and 25-hydroxycholecalciferol (25-HCC). Five out of 52 Indian patients in the series were found to have osteomalacia, a prevalence probably no higher than in the Asian population in the UK at large. Moreover, osteomalacia responded to physiological supplementation with vitamin D. One European out of 31 had osteomalacia due to low vitamin D intake. Serum calcium was compared in 17 patients before and after six months of antituberculous chemotherapy but no significant difference was detected (P greater than 0.1). Two Indian patients were in positive calcium balance with low to normal plasma 25-HCC levels, indicating that an effect on 1,25 dihydroxyvitamin D activity during therapy was unlikely. It is concluded that rifampicin when combined with isoniazid has no significant effect on calcium metabolism over an eighteen-month treatment period.

Adolescent↗

Expression of HLA-DR antigens in human fetal pancreas tissue.

The expression of HLA-DR antigens in human fetal pancreas tissue was studied using four independently derived monoclonal antibodies recognizing nonpolymorphic HLA-DR antigens. Immunoperoxidase staining of frozen sections revealed numerous DR-antigen-positive cells. Two major cell types could be distinguished. Large, strongly DR-positive cells with dendritic morphology were distributed throughout the dendritic morphology were distributed throughout the pancreatic parenchyma and interstitial connective tissue. Dual staining of DR antigens and insulin using a two-color immunoperoxidase technique clearly showed that some of these DR-positive dendritic cells were located within and in close association with insulin-producing islets. Also observed as a regular feature of fetal pancreas tissue sections were large clusters of DR-positive cells with lymphoid morphology. Positive staining of many cells within these clusters with monoclonal antibodies against T-cell marker (Leu-1) and T-cell subset markers (Leu-2 and -3) supported their classification as lymphoid cells. In contrast, no positive staining with anti-T-cell antibodies was observed outside of lymphoid cell clusters, confirming the distinction between these cells and the DR-positive cells distributed throughout the pancreas. The presence of other DR-bearing cell types in fetal pancreas could not be excluded, but most endothelial cells appeared to be DR-negative. The demonstration of numerous DR-bearing cells associated with fetal pancreas tissue may require that we alter our views on DR-antigen ontogeny and develop new strategies for fetal pancreas transplantation.

Antibodies, Monoclonal↗

Lymphocyte blastogenesis in dogs with lymphosarcoma.

Mitogen-stimulated lymphocyte blastogenesis was evaluated, using lymphocytes from 37 dogs with multicentric lymphosarcoma. The majority of the test results was within a normal range, even for those dogs with more advanced disease. However, depressed lymphocyte blastogenesis, when present, almost always occurred in lymphocytes from dogs with clinical stage IV-B and V-B disease. Dogs weighing greater than 25 kg had a significantly (P = 0.04) higher occurrence of clinical stage IV or V disease as compared with dogs weighing less than 15 kg. Dogs with diffuse lymphocytic well-differentiated lymphoma were statistically more likely to be designated clinical stage III at the time of diagnosis, as compared with dogs with diffuse lymphocytic poorly differentiated lymphoma.

Animals↗