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Biomedical subjects

R Collins

Publications and source records attributed to R Collins.

At least 19 recordsLinked to original sources
PubMed1991

Effects of intravenous magnesium in suspected acute myocardial infarction: overview of randomised trials.

OBJECTIVE: To investigate the effect of intravenous magnesium on mortality in suspected acute myocardial infarction. DESIGN: Systematic overview of all available randomised trials in which patients were allocated to receive either intravenous magnesium or otherwise similar treatment without magnesium. SETTING: Coronary care units of several hospitals. PATIENTS: 1301 patients in seven randomised trials. MAIN OUTCOME MEASURE: Short term mortality. RESULTS: Considering the seven trials collectively there were 25 (3.8%) deaths among 657 patients allocated to receive magnesium and 53 (8.2%) deaths among 644 patients allocated control, generally during hospital follow up. This represents a 55% reduction in the odds of death (p less than 0.001) with 95% confidence intervals ranging from about one third to about two thirds. 70 of 648 patients allocated magnesium compared with 109 of 641 controls had serious ventricular arrhythmias, suggesting that magnesium reduces the incidence, though the definition varied among trials. Other adverse effects were rare in the limited number of patients for whom this data were available. CONCLUSION: Despite the limited number of patients randomised this overview suggests that intravenous magnesium therapy may reduce mortality in patients with acute myocardial infarction. Further large scale trials to confirm (or refute) these findings are desirable.

Hospitalization↗
PubMed1991

Serum cholesterol concentration and coronary heart disease in population with low cholesterol concentrations.

OBJECTIVE: To examine the relation between serum cholesterol concentration and mortality (from coronary heart disease and from other causes) below the range of cholesterol values generally seen in Western populations. DESIGN: Prospective observational study based on 8-13 years of follow up of subjects in a population with low cholesterol concentrations. SETTING: Urban Shanghai, China. SUBJECTS: 9021 Chinese men and women aged 35-64 at baseline. MAIN OUTCOME MEASURE: Death from coronary heart disease and other causes. RESULTS: The average serum cholesterol concentration was 4.2 mmol/l at baseline examination, and only 43 (7%) of the deaths that occurred during 8-13 years of follow up were attributed to coronary heart disease. There was a strongly positive, and apparently independent, relation between serum cholesterol concentration and death from coronary heart disease (z = 3.47, p less than 0.001), and within the range of usual serum cholesterol concentration studied (3.8-4.7 mmol/l) there was no evidence of any threshold. After appropriate adjustment for the regression dilution bias, a 4 (SD 1)% difference in usual cholesterol concentration was associated with a 21 (SD 6)% (95% confidence interval 9% to 35%) difference in mortality from coronary heart disease. There was no significant relation between serum cholesterol concentration and death from stroke or all types of cancer. The 79 deaths due to liver cancer or other chronic liver disease were inversely related to cholesterol concentration at baseline. CONCLUSION: Blood cholesterol concentration was directly related to mortality from coronary heart disease even in those with what was, by Western standards, a "low" cholesterol concentration. There was no good evidence of an adverse effect of cholesterol on other causes of death.

Cerebrovascular Disorders↗
PubMed1991

Phase I immunotoxin trial in patients with B-cell lymphoma.

Fifteen patients with refractory B-cell lymphoma were treated in a Phase I dose escalation clinical trial with a highly potent immunotoxin consisting of the Fab' fragment of a monoclonal anti-CD22 antibody (RFB4) coupled to chemically deglycosylated ricin A chain. All patients had low, intermediate, or high grade non-Hodgkin's lymphoma. The immunotoxin was administered i.v. in two to six doses at 48-h intervals. The peak serum concentration and the t1/2 were not dose dependent among patients and averaged 1.3 micrograms/ml and 86 min, respectively. Three patients made antibody against A chain, and a fourth made antibody against both A chain and mouse immunoglobulin. Antibody responses were low (less than or equal to 85 micrograms/ml) in three patients and were not detected until 1 mo after treatment. The maximum tolerated dose of the immunotoxin was 75 mg/m2. Dose-related toxicities included vascular leak syndrome, fever, anorexia, and myalgia. Dose-limiting toxicities included pulmonary edema and/or effusion, expressive aphasia, and rhabdomyolysis (resulting in reversible kidney failure). There was no evidence of liver dysfunction. Partial responses were achieved in 38% of evaluable patients, and in those patients who had greater than 50% CD22+ tumor cells, 50% of the patients achieved a partial response. Clinical responses were not related to tumor grade and were generally transient, lasting between 1 and 4 mo.

Adult↗
PubMed1991

Holter monitoring of ventricular arrhythmias in a randomised, controlled study of intravenous streptokinase in acute myocardial infarction.

The occurrence of ventricular arrhythmias attributed to streptokinase treatment in acute myocardial infarction is not well defined. Holter monitoring was performed for 24 hours in 81 patients with suspected acute myocardial infarction randomised in a ratio of 2:1 to intravenous streptokinase 1.5 x 10(6) IU (n = 55) or placebo infusion (n = 26) 6.7 hours (mean) after the onset of symptoms. No episodes of ventricular fibrillation were recorded. For the whole 24 hour period and during the first three hours after the start of treatment the incidence and frequency of ventricular arrhythmias were similar in the patients randomised to streptokinase and to placebo. But when the results in patients randomised "early" after the onset of symptoms of suspected acute myocardial infarction were analysed separately the frequency of abnormal complexes, pairs, runs, and repetitive arrhythmias seemed to be higher in patients allocated to streptokinase. This may reflect arrhythmias associated with reperfusion.

Arrhythmias, Cardiac↗
PubMed1991

British Heart Foundation surveys (1987 and 1989) of United Kingdom treatment policies for acute myocardial infarction.

Consultant physicians and cardiologists were surveyed early in 1987 and 1989 to document the management policies for the treatment of acute myocardial infarction in United Kingdom hospitals and to assess the influence of major clinical trials on these policies. The response rate to both these surveys was high (84% (1178 physicians) in 1987 and 76% (982 physicians) in 1989). The percentage of physicians that reported using antiplatelet therapy "routinely" in acute myocardial infarction rose from 9% in 1987 to 84% in 1989 while those who reported using it "rarely or never" fell from 42% to 3%. Similarly, "routine" use of fibrinolytic therapy rose from 2% to 68%, and use "rarely or never" fell from 53% to 3%. This increase in the reported use of fibrinolytic therapy was accompanied by greater certainty about its efficacy and relative safety and by a general widening of the indications for its use. The use of other treatments in acute myocardial infarction (for example, the general use of anticoagulants, beta blockers, nitrates, calcium antagonists, or prophylactic antiarrhythmic agents) seemed to change little during this period, although the routine use of coronary angiography and oral anticoagulants after fibrinolytic therapy fell substantially between 1987 and 1989 (from 23% to 4%, and from 24% to 7% respectively). Fibrinolytic and antiplatelet therapy were accepted into the routine management of myocardial infarction during a relatively short period that coincided with the reporting of several positive controlled trial results. Clinical trials have rarely been seen to have had such a great impact on practice. In this case the rapid acceptance of the trial results may have been due to the consistency and reliability of the estimates of the size of the benefits (and risks) of therapy seen in these unusually large studies.

Adult↗
PubMed1991

How to share control with workshop participants.

The authors discuss the five steps they have used to share control with participants over the planning, implementation and evaluation of a workshop: (1) establish a co-operative learning climate; (2) provide resources for participants to identify their individual learning needs; (3) assist participants in organizing learning groups and defining objectives for each workshop session; (4) provide support for participants to manage the workshop sessions themselves; and (5) encourage participants to reflect on and evaluate their learning.

Education, Medical, Continuing↗
PubMed1991

Design and compliance of HBV vaccination trial on newborns to prevent hepatocellular carcinoma and 5-year results of its pilot study.

A large-scale, controlled study of universal immunization of newborns against HBV infection has been conducted in the high incidence area of hepatocellular carcinoma, Qidong County of China. This area has a stable population, standardized cancer registration system, and an epidemiological base for measurements of liver cancer prevention by vaccine. Randomization was done on the community level. The vaccination and the control group each will consist of 38,000 children by the end of 1990. It is anticipated that the design will provide high statistical power to detect 50% reduction in the prevalence rate of chronic hepatitis among the vaccinees vs. the controls at 6 to 10 years of age, and 50% reduction in the incidence rate of hepatocellular carcinoma at 35 to 40 years of age. The vaccine used is Hep-B Vax, donated by Merck and Co. through WHO. The vaccine was administered at 0, 1, and 6 months after birth, the dosage of 5 or 2.5 micrograms in the pilot study as used before 1985 and of 5 micrograms dose level during the main study starting from January 1, 1985. About 85% of the cohorts have now entered the protocol. The vaccination coverage during 1984 to 1989 was 98.0% (35,064/35,789). Follow-up of the vaccinees and the age-matched controls at 5 years has exceeded 97%. The cumulative mortality in the vaccinated group up to 1988 was 1.29% (354/27,450). No single death nor serious adverse reaction was found that was associated with vaccination. The use of HBV vaccine at a reduced dose was especially important for the developing countries at the present time in order to achieve widespread immunization. Five-year results of the pilot study of this vaccination project showed that significant protection against HBV infection was achieved with the 5 or 2.5 micrograms per dose regimen plus a booster of 5 micrograms given at 3.5 to 4 years of age.(ABSTRACT TRUNCATED AT 250 WORDS)

Carcinoma, Hepatocellular↗
PubMed1990

Blood pressure, stroke, and coronary heart disease. Part 2, Short-term reductions in blood pressure: overview of randomised drug trials in their epidemiological context.

There are 14 unconfounded randomised trials of antihypertensive drugs (chiefly diuretics or beta-blockers): total 37,000 individuals, mean treatment duration 5 years, mean diastolic blood pressure (DBP) difference 5-6 mm Hg. In prospective observational studies, a long-term difference of 5-6 mm Hg in usual DBP is associated with about 35-40% less stroke and 20-25% less coronary heart disease (CHD). For those dying in the trials, the DBP difference had persisted only 2-3 years, yet an overview showed that vascular mortality was significantly reduced (2p less than 0.0002); non-vascular mortality appeared unchanged. Stroke was reduced by 42% SD 6 (95% confidence interval 35-50%; 289 vs 484 events, 2p less than 0.0001), suggesting that virtually all the epidemiologically expected stroke reduction appears rapidly. CHD was reduced by 14% SD 5 (95% CI 4-22%; 671 vs 771 events, 2p less than 0.01), suggesting that just over half the epidemiologically expected CHD reduction appears rapidly. Although this significant CHD reduction could well be worthwhile, its size remains indefinite for most circumstances (though beta-blockers after myocardial infarction are of substantial benefit). At present, therefore, a sufficiently high risk of stroke (perhaps because of age, blood pressure, or, in particular, history of cerebrovascular disease) may be the clearest indication for antihypertensive treatment.

Antihypertensive Agents↗
PubMed1990

Blood pressure, stroke, and coronary heart disease. Part 1, Prolonged differences in blood pressure: prospective observational studies corrected for the regression dilution bias.

The associations of diastolic blood pressure (DBP) with stroke and with coronary heart disease (CHD) were investigated in nine major prospective observational studies: total 420,000 individuals, 843 strokes, and 4856 CHD events, 6-25 (mean 10) years of follow-up. The combined results demonstrate positive, continuous, and apparently independent associations, with no significant heterogeneity of effect among different studies. Within the range of DBP studied (about 70-110 mm Hg), there was no evidence of any "threshold" below which lower levels of DBP were not associated with lower risks of stroke and of CHD. Previous analyses have described the uncorrected associations of DBP measured just at "baseline" with subsequent disease rates. But, because of the diluting effects of random fluctuations in DBP, these substantially underestimate the true associations of the usual DBP (ie, an individual's long-term average DBP) with disease. After correction for this "regression dilution" bias, prolonged differences in usual DBP of 5, 7.5, and 10 mm Hg were respectively associated with at least 34%, 46%, and 56% less stroke and at least 21%, 29%, and 37% less CHD. These associations are about 60% greater than in previous uncorrected analyses. (This regression dilution bias is quite general, so analogous corrections to the relations of cholesterol to CHD or of various other risk factors to CHD or to other diseases would likewise increase their estimated strengths.) The DBP results suggest that for the large majority of individuals, whether conventionally "hypertensive" or "normotensive", a lower blood pressure should eventually confer a lower risk of vascular disease.

Adult↗
PubMed1990

Klinefelter's syndrome and primary central nervous system lymphoma.

Klinefelter's syndrome is known to be associated with various malignancies including male breast cancer and germ cell tumour. We report a patient with Klinefelter's syndrome who developed a primary B-cell lymphoma of the central nervous system (CNS). To the best of our knowledge, this is the first case of primary CNS lymphoma in Klinefelter's syndrome.

Adult↗
PubMed1990

Renal vasodilatory response to intravenous glycine in the aging rat kidney.

Studies were performed in the awake, chronically catheterized male Sprague-Dawley rat to investigate renal hemodynamics in the baseline state and also in response to a large intravenous (IV) amino acid (glycine) load. Studies were performed in young adult rats (age 3 to 4 months), old rats (age 18 months), and senescent rats (age 22 to 24 months). Histologic evaluation of the kidney permitted a correlation between structural and functional changes with aging. Histology showed progressive glomerular damage (sclerosis) with aging. In 18-month-old rats, the glomerular filtration rate (GFR) was normal, which, considering the level of glomerular injury (only 64% normal glomeruli), must indicate heterogeneity of glomerular function, with some hyperfunctioning glomeruli. By 22 to 24 months of age (at which time approximately 50% mortality has occurred in males of this strain), GFR is substantially reduced, as is renal plasma flow rate (RPF). Severe glomerular damage was observed histologically (only 34% normal glomeruli), indicating widespread heterogeneity of glomerular function. Young adult rats displayed a substantial renal vasodilation in response to acute IV glycine infusion, which resulted in approximately 25% increases in GFR and RPF. The renal vascular responsivity to glycine was diminished at 18 months and was completely absent in 22- to 24-month-old rats. This altered renal vasodilatory response to glycine probably reflects both structural changes associated with aging and also the compensatory vasodilation of intact hyperfunctioning remnant nephrons as other nephrons are lost due to aging.

Aging↗
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↗