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Biomedical subjects

R Collins

Publications and source records attributed to R Collins.

At least 181 records · Page 10Linked to original sources
PubMed1990

Stereoselective and nonstereoselective inhibition exhibited by the enantiomers of verapamil.

The interaction of the isomers of verapamil with sites on the calcium channel and alpha 1-adrenergic receptor has been examined. The inhibitory potency of these enantiomers differ with respect to the agonist. KCl- or clonidine-induced contractions of rabbit aortic rings were inhibited in a stereoselective manner by the enantiomers of verapamil with the (-)-isomer being more potent than the (+)-isomer. Similarly, (-)-verapamil was also more potent at displacing (-)-[N-methyl-3H]desmethoxyverapamil than was the (+)-isomer. In contrast, the inhibition of norepinephrine- or phenylephrine-induced aortic contractions was not stereoselective. Differences in enantiomer potency were also observed in vivo. The ability of clonidine to increase blood pressure in the anesthetized rat was blocked in a stereoselective manner by the verapamil enantiomers, while inhibition of the pressor actions of phenylephrine was not. In summary, for agents that rely heavily on calcium channel function (KCl, clonidine), stereoselective inhibition was observed. Stereoselective inhibition was not observed against high efficacy alpha 1-agonists. This difference in stereochemistry argues that verapamil does not act at the same site when inhibiting clonidine or KCl action when compared with norepinephrine or phenylephrine.

Anesthesia↗
PubMed1989

Granulomatous angiitis masquerading as a mass lesion. Magnetic resonance imaging and stereotactic biopsy findings in a patient with occult Hodgkin's disease.

Granulomatous angiitis is a frequently fatal central nervous system vasculitis of unknown pathogenesis sporadically associated with Hodgkin's disease, mixed cellularity type. We describe a 58-year-old woman presenting with headaches, progressive spastic paraparesis, equivocal computed tomography findings, and magnetic resonance imaging findings of increased signal intensity biparietally on T2-weighted imaging in a relatively discrete pattern. Magnetic resonance imaging-directed serial stereotactic biopsies revealed granulomatous angiitis throughout the right parieto-occipital region and splenium. Simultaneous biopsy of an enlarged submandibular mass revealed Hodgkin's disease, lymphocyte-predominant type. This case shows that granulomatous angiitis may be associated with magnetic resonance imaging findings suggesting a mass lesion in lymphocyte-predominant as well as mixed cellularity Hodgkin's disease.

Brain↗
PubMed1989

A randomized study of high-dose versus low-dose cis-platinum combined with cyclophosphamide in the treatment of advanced ovarian cancer. Hong Kong Ovarian Carcinoma Study Group.

A randomized clinical study of patients with advanced epithelial ovarian cancer after debulking surgery showed that high-dose (120 mg/m2) cis-platinum (DDP) in combination with cyclophosphamide (600 mg/m2) had a significantly higher response and survival rate than the low-dose DDP (60 mg/m2) and cyclophosphamide combination. The 3-year actuarial survival rate of the high-dose group was 60% and that of the low-dose group was 30%. Though moderate to severe marrow toxicity was evident in 80% of the patients in the high-dose group and 40% of the low-dose group, no serious sepsis or death developed as a result of the marrow depression. Mild neurotoxicity was observed in 55% of the patients in the high-dose group and only 20% in the low-dose group. Mild nephrotoxicity was seen in 25 and 17% of patients in the high- and low-dose groups, respectively. It was concluded that the 120 mg/m2 dose DDP and cyclophosphamide combination should be used in the treatment of carcinoma of the ovary in spite of its toxicities. However, it should only be used in institutions with supportive facilities in the management of patients with severe marrow depression.

Adolescent↗
PubMed1989

Maternal brain death and prolonged fetal survival.

A 30-year-old woman suffered massive brain injuries after a motor vehicle accident at 15 weeks' gestation. The patient was diagnosed as brain-dead on her tenth hospital day. She was supported with intensive care for 107 days after this diagnosis, and a normal 1555-g male infant was delivered at approximately 32 weeks' gestation by repeat cesarean section. The child is developing normally at 11 months of age. This represents the longest reported case of prolongation of pregnancy after brain death.

Adult↗
PubMed1988

Effects of prophylactic lidocaine in suspected acute myocardial infarction. An overview of results from the randomized, controlled trials.

The effects of prophylactic lidocaine hydrochloride on early ventricular fibrillation and death in patients with suspected acute myocardial infarction were investigated in an overview of 14 randomized trials. During follow-up intervals of one to four hours in the trials of intramuscular lidocaine infusion (6961 patients) and 24 to 48 hours in the trials of intravenous lidocaine injection (2194 patients), a total of 103 cases of ventricular fibrillation and 137 deaths were recorded. Overall, allocation to lidocaine was associated with a reduction in the odds of ventricular fibrillation of about one third, with a 95% confidence interval that ranged from a 3% to a 56% reduction. There was no evidence of any beneficial effect on early mortality; indeed, the odds of early death were about one third greater among patients allocated lidocaine, though this difference was not statistically significant (95% confidence interval, 2% reduction to 95% increase). Because of the small numbers of reported events, the short follow-up periods, and the unavailability of data for some specific causes of death, even an overview of all the trial results does not provide good evidence as to whether prophylactic lidocaine is likely to be helpful or harmful. To answer this question reliably, future trials will need to involve large numbers of patients and prolonged follow-up.

Clinical Trials as Topic↗
PubMed1988

Characterization of the cross-reacting determinant (CRD) of the glycosyl-phosphatidylinositol membrane anchor of Trypanosoma brucei variant surface glycoprotein.

The cross-reacting determinant (CRD epitope) of the glycosyl-phosphatidylinositol (GPI) membrane anchor of Trypanosoma brucei variant surface glycoprotein has been analysed by selective chemical and enzymic modification of the isolated GPI structure combined with the use of a competitive ELISA inhibition assay for the detection of CRD epitopes. The data show that the CRD consists of at least three overlapping epitopes involving different regions of the molecule including the inositol 1,2-cyclic phosphate, the non-N-acetylated-glucosamine residue and the galactose branch. Although the presence of all three of these structural features is required for quantitative binding of anti-CRD antibodies in ELISA and Western blotting, the Western blot reaction obtained in the presence of any one epitope is still significant. The use of anti-CRD antibodies for the detection of GPI anchors is discussed.

Animals↗
PubMed1988

Effect of intravenous nitrates on mortality in acute myocardial infarction: an overview of the randomised trials.

About 2000 patients have been randomised in ten trials of intravenous nitroglycerin or nitroprusside in acute myocardial infarction. Taken separately, the individual trials have all been too small to provide a reliable estimate of the effects of treatment on mortality, but collectively they provide strong evidence of benefit. In total there have been 136 nitrate and 193 control deaths, and an appropriate overview of the separate trial results indicated a "typical" reduction of 35% (SD 10) in the odds of death (2p less than 0.001, with 95% confidence limits of about one-sixth to one-half). Both nitroglycerin and nitroprusside reduced mortality, the reduction being non-significantly greater with nitroglycerin than with nitroprusside. The greatest reduction in mortality occurred during the first week or so of follow-up, with a non-significant further reduction after this early period. This suggests that the early benefit is not rapidly lost.

Clinical Trials as Topic↗
PubMed1988

Randomised trial of prophylactic daily aspirin in British male doctors.

A six year randomised trial was conducted among 5139 apparently healthy male doctors to see whether 500 mg aspirin daily would reduce the incidence of and mortality from stroke, myocardial infarction, or other vascular conditions. Though total mortality was 10% lower in the treated than control group, this difference was not statistically significant and chiefly involved diseases other than stroke or myocardial infarction. Likewise, there was no significant difference in the incidence of non-fatal myocardial infarction or stroke--indeed, disabling strokes were somewhat commoner among those allocated aspirin. The lower confidence limit for the effect of aspirin on non-fatal stroke or myocardial infarction, however, was a substantial 25% reduction. Migraine and certain types of musculoskeletal pain were reported significantly less often in the treated than control group, but as the control group was not given a placebo the relevance of these findings was difficult to assess. There was no apparent reduction in the incidence of cataract in the treated group. The lack of any apparent reduction in disabling stroke or vascular death contrasts with the established value of antiplatelet treatment after occlusive vascular disease.

Aspirin↗