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Biomedical subjects

R Allen

Publications and source records attributed to R Allen.

At least 253 records · Page 14Linked to original sources
PubMed1981

The effects of neuroleptic drugs on 5-hydroxytryptamine induced platelet aggregation in schizophrenic patients.

1 The effects of treatment with a range of neuroleptic drugs on 5-hydroxytryptamine (5-HT) induced platelet aggregation in vivo were examined in a group of recently admitted psychiatric patients and in a larger group of chronic schizophrenic patients. 2 Five of seven recently admitted patients treated with chlorpromazine showed enhanced aggregation. Four of seven patients treated with fluphenazine, flupenthixol, trifluoperazine and haloperidol showed enhancement. 3 Enhanced aggregation responses were observed in only 20% of chronic schizophrenic patients being treated with a neuroleptic drug. 4 The relationship between changes in platelet aggregation and clinical changes in recently admitted patients was variable and platelet aggregation responses were not predictive of response to treatment. 5 Chronic schizophrenic patients with enhanced aggregation showed significant week to week variation in platelet aggregation response. Variability of responses was not related to the drug used or to the dose administered. There was some evidence that higher plasma concentrations of neuroleptic drugs were associated with enhanced platelet aggregation responses. 6 Treatment with neuroleptic drugs leads to enhancement of platelet aggregation responses induced by 5-HT. The frequency and reliability with which such responses can be elicited is unpredictable and the value of platelet aggregation responses as an empirical guide to treatment with neuroleptic drugs is therefore open to question.

Antipsychotic Agents↗
PubMed1981

The reliability of 5-hydroxytryptamine induced platelet aggregation responses in schizophrenic patients treated with neuroleptic drugs.

1 The reliability of 5-hydroxytryptamine induced platelet aggregation responses in psychiatric patients treated with neuroleptic drugs was investigated by examining the effects of a number of technical factors which could account for the variability of responses observed in some patients. 2 Variation in incubation time, temperature, aggregometer stirrer speed, and in the time interval between withdrawal of the blood sample and testing, had no significant effects on the consistency of responses. 3 Dilution of platelet rich plasma (PRP) led to enhanced platelet aggregation responses becoming non-enhanced. 4 Overcentrifugation of blood samples during the preparation of PRP caused a decrease in the incidence of enhanced platelet aggregation responses observed in chronic schizophrenic patients receiving chlorpromazine. 5 The reliability of platelet aggregation responses as indices of the action of neuroleptic drugs in psychiatric patients remains doubtful.

Antipsychotic Agents↗
PubMed1981

Clonal analysis of the integration and expression of endogenous avian retroviral DNA acquired by exogenous viral infection.

Rous-associated virus-0 is one of several endogenous avian retroviruses that are transmitted vertically and that can be isolated from different inbred lines of chickens. These viruses, referred to here as induced-leukosis viruses bearing a subgroup E glycoprotein (ILV-E), are all closely related. Clonal populations of fibroblasts from line 15B and line 100 inbred chickens have been examined for the presence and expression of exogenously acquired ILV-E sequences. Restriction enzyme analysis of uniform populations of line 15B fibroblasts, prepared by cloning cells either before or after infection with ILV-E, indicates that viral sequences were inserted at multiple sites within the cell genome. Analysis of 49 clonal populations of line 100 fibroblasts containing between one and five copies of exogenous ILV-E sequences demonstrated that each clone was characterized by a unique set of viral DNA insertions within the cell genome. The expression of the exogenous ILV-E sequences within these fibroblast clones was examined by using reverse transcriptase activity as a measure of virus production. Some clones produced an amount of virus equivalent to that produced by an equal number of the uncloned ILV-E-infected parental fibroblasts. Other clones produced 5- to 10-fold less virus. Still other clones produced no detectable virus at all. Among nine clones derived from cells containing a single copy of the ILV-E provirus, the level of virus production differed more than 100-fold. DNA from these clones was analyzed with several different restriction endonucleases to characterize the location and arrangement of the ILV-E sequences. All nine clones consisted of cells that appeared to contain a complete provirus inserted (i) in a different site within the cellular DNA and (ii) in an orientation that was colinear with the viral genomic RNA. It was observed that several cleavage sites potentially affected by methylation were equally available for cleavage in all clones regardless of the level of viral production.

Animals↗
PubMed1981

Corticotropin/beta-lipotropin biosynthesis, processing, and release in Nelson's syndrome.

Biosynthesis and processing of ACTH/beta-lipotropin was studied in Nelson's syndrome pituitary tumor tissue grown in monolayer culture. Radiolabeled peptides were immunoprecipitated and fractionated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS/PAGE). Important findings include: 1) a virtual absence of 13K ACTH or 3.5K beta-endorphin production; 2) evidence indicating the presence of a 24-26K ACTH and beta-LPH containing intermediate (which implies a different order of processing from that reported in the mouse); 3) An extremely rapid rate of turnover and release of ACTH and beta-lipotropin (beta-LPH) similar to that of the mouse AtT20/D16v pituitary tumors. The latter finding is consistent with an intrinsic pituitary cell defect in the pathogenesis of this disorder.

Adrenocorticotropic Hormone↗
PubMed1981

Biochemical and cytochemical comparison of surface membranes from normal and dystrophic chickens.

Cytochemical and biochemical characteristics of the surface membrane components of avian dystrophic muscle were examined. A Mg2+- or Ca2+-activated ("basic") adenosine triphosphate (ATPase) was localized cytochemically in fixed, intact dystrophic muscle slices in a medium containing Mg2+ or Ca2+, adenosine triphosphate (ATP), and 1 microM free Pb2+ to capture enzymatically released phosphate ions. Electron-dense staining precipitates were found to be associated with the plasmalemma and its tortuous invaginations, and the transverse components of the T-system membrane and its associated proliferated networks. Enzymatic analysis of microsomal fractions isolated from 7-day-old and 90-day-old normal and dystrophic muscle showed a complex behavior. Specific activity of "basic" ATPase decreased with maturity in normal and dystrophic animals. The specific activities of the surface membrane associated enzymes, leucyl beta-naphthylamidase, adenylate cyclase, and guanylate cyclase, remained at various elevated levels in the mature dystrophic animals, in contrast to the normal muscle, which showed decreases in the specific activity of all three enzymes with maturation. The persistent high levels in some but not all enzyme activities in 90-day-old dystrophic muscle indicates a complicated developmental pattern in the dystrophic chicken muscle.

Adenosine Triphosphatases↗
PubMed1980

A distributed computer network using microcomputers for on-line data processing in clinical monitoring and medical research.

Microelectronic technology has made possible a rapid expansion in the exploitation of the digital computer in medicine, but software development remains an increasingly significant problem. This paper describes a distributed computer network which combines the low cost computing power of the microcomputer with the highly developed features of a minicomputer. Powerful data processing facilities are provided through centralization of major resources on the minicomputer. Parallel real-time computing is assigned to microcomputers which have access to the minicomputer filestore, and to its comprehensive software development aids.

Animals↗
PubMed1980

Nontropical chyluria associated with pelvic lipomatosis.

A patient never exposed to filarial parasites presented with intermittent chyluria and was found to have coincidental pelvic lipomatosis. The pathophysiology of chyluria and pelvic lipomatosis are reviewed and their possible relationship in the present case is discussed.

Aged↗
PubMed1980

Pneumocystis pneumonia in hospitals: outbreaks or improved recognition?

A presumed outbreak of Pneumocystis carinii pneumonitis occurred at a large teaching hospital. The diagnosis was made by lung biopsy or at autopsy in seven patients over a 22 1/2-year period and only by percutaneous lung aspirate in seven patients over a 2 1/2-year period. Apparent outbreaks may be related to both an increase in the number of cases of disease and improved diagnostic methods.

Adult↗
PubMed1980

Protease inhibitor profiles in urticaria and angio-oedema.

Plasma levels of six protease inhibitors have been measured in patients with chronic urticaria, chronic urticaria with angio-oedema, cold and cholinergic urticaria. In chronic urticaria C1 esterase inhibitor activity was increased compared with a reference control population but there was no detectable abnormality of any other protease inhibitor. Patients with chronic urticaria/angio-oedema showed a reduction in inter-alpha trypsin inhibitor. They also manifested a rise in C1 esterase inhibitor. In cold urticaria there was a significant lowering of alpha 1 antichymotrypsin. The reduction in alpha 1 antitrypsin in this group probably reflects a genetic difference compared with the control population. Patients with cholinergic urticaria also showed a reduction of alpha 1 antichymotrypsin. The elevated levels of alpha 2 macroglobulin in the three groups are probably due to differences in the mean age of these groups compared with the reference population. Comparison of levels of subgroups of patients with and without active lesions suggest that a consumptive effect may contribute to the reduced values, although it seems unlikely to account for them entirely. The results suggest that involvement of pharmacologically active products of protein digestion may be involved in the pathogenesis of urticaria and should prompt attempts to identify these agents and encourage trial of medications which lead to inhibition of proteolytic activity in urticaria.

Adolescent↗
PubMed1980

A clinical evaluation of serum angiotensin converting enzyme in sarcoidosis.

Angiotensin converting enzyme was measured in the serum of 52 patients with sarcoidosis, 67 healthy control subjects and 64 patients with pulmonary and non-pulmonary diseases. The patients with sarcoidosis were classified on clinical grounds as having active or inactive disease. In 26 patients with active sarcoidosis not taking corticosteroids the mean serum ACE was significantly higher than in normal controls (P less than 0 . 001). 73% of these patients had elevated serum ACE. Only two out of 12 (17%) patients with inactive sarcoidosis not taking corticosteroids had elevated serum ACE. Serum ACE was normal in patients taking oral corticosteroids for longer than two weeks. Eighty per cent of patients with active sarcoidosis with radiological evidence of pulmonary parenchymal involvement had an elevated serum ACE compared to 25% in patients with normal chest X-rays and 60% of those with bilateral hilar lymphadenopathy. All sarcoid patients with hypercalcaemia had elevated serum ACE whereas only half of those with normal serum calcium had elevated ACE. In the patients with other thoracic and granulomatous conditions serum ACE was normal or rarely marginally elevated. Serum ACE appears to be of value in the diagnosis of active sarcoidosis.

Adolescent↗