Biomedical subjects
B Slavin
Publications and source records attributed to B Slavin.
Obscure splenomegaly in the tropics that is not the tropical splenomegaly syndrome.
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Hypocholesterolaemia and non-cardiovascular disease: metabolic studies on subjects with low plasma cholesterol concentrations.
Some epidemiological studies have suggested an inverse relation between serum cholesterol concentration and mortality from cancer. Two hypotheses that might explain such a relation were investigated. To assay potentially deleterious effects of hypocholesterolaemia on cell membranes the lipid content and fluidity of blood mononuclear cells were measured in healthy male volunteers with a wide range of serum cholesterol concentration (3.2-10.0 mmol/l (124-387 mg/100 ml)). Fluidity, unesterified cholesterol content, and the ratio of cholesterol to phospholipid were unrelated to serum cholesterol and to low density lipoprotein cholesterol concentrations. Similar measurements were made on fibroblasts and mononuclear cells incubated with a range of concentrations of low density lipoprotein; fluidity was altered only at extremely low concentrations, suggesting that changes in cell membranes are unlikely to occur at serum cholesterol concentrations attainable by dietary or drug treatment of hyperlipidaemia. In the same population direct relations were confirmed between low density lipoprotein concentration and plasma concentrations of retinol and beta carotene. This is compatible with the suggestion that an association between low cholesterol concentration and cancer may be secondary to a relation between low retinoid concentrations and cancer.
The effect of ionized calcium, pH, and temperature on bioactive parathyroid hormone during and after open-heart operations.
Normal myocardial function is dependent on the metabolic balance of a number of electrolytes and hormones. The calcium ion plays a major role in muscle contraction and is rigorously controlled within narrow limits. Open-heart surgery imposes metabolic disturbances on both electrolytes and hormones, especially ionized calcium. Normally, ionized calcium levels are controlled by parathyroid hormone with a negative feedback from the ionized calcium controlling the system, but the results from this study suggest that during open-heart procedures, ionized calcium does not impose its normal negative feedback on bioactive parathyroid hormone secretion. The low blood pH levels that occurred during the operative conditions of the patients studied and the level of hypothermia imposed on the circulating blood during cardiopulmonary bypass appeared to influence the control of parathyroid hormone secretion, causing high levels of hormone to be secreted during this period.
Effect of the antitussive glaucine on bronchomotor tone in man.
In view of the observation that the antitussive agent glaucine prevents histamine-induced bronchoconstriction in guinea pigs we investigated this agent for a possible peripheral action in man, using a new method for measuring changes in bronchomotor tone. The forced airflow oscillation method was used to determine respiratory resistance (Rrs) over a range of lung volumes (VL) in seven healthy supine subjects. Computer analysis of the hyperbolic relationship between Rrs and VL was used to determine the asymptotic resistance and yield estimates of lower airways conductance (Glaw). Specific lower airways conductance (sGlaw) was expressed as the slope of the linear plot of Glaw against VL and is a sensitive index of bronchomotor tone. After baseline measurements of sGlaw subjects received placebo or 60 mg glaucine orally according to a double-blind crossover protocol. Histamine, 500 micrograms, was inhaled 45 minutes later. Measurements of sGlaw were repeated every 10 minutes for two hours. Although there was a trend towards bronchodilatation after glaucine administration (sGlaw = 130% of baseline) there was no significant difference from the effect of placebo (sGlaw = 89% of baseline). After inhalation of histamine sGlaw fell to 26% of baseline after both glaucine and placebo (p less than 0.01). In a further study three subjects received glaucine and placebo according to an identical protocol except that the histamine was omitted. Again the increase in sGlaw failed to achieve significance. Glaucine does not affect the bronchoconstrictor response to histamine in man and there is no convincing evidence of an effect on resting bronchomotor tone.
Myelomatosis with type III hyperlipoproteinemia: clinical and metabolic studies.
We investigated the metabolism of intermediate-density lipoproteins (IDL [1.006 to 1.019 g per milliliter]) and low-density lipoproteins (LDL [1.019 to 1.063 g per milliliter]) in two men with Type III hyperlipoproteinemia associated with myelomatosis. In vivo kinetic studies using radiolabeled autologous lipoproteins demonstrated a greatly reduced fractional catabolic rate of IDL, relative to control values (patients vs. normal, 0.006 and 0.025 per hour vs. 0.20 +/- 0.08 per hour [mean +/- S.E.M]) and a greatly prolonged IDL-to-LDL conversion time (45 and 17 hours vs. 5.4 +/- 1.6 hours). In studies in vitro, LDL from both patients failed to bind to the LDL receptor of normal blood lymphocytes, whereas LDL from subjects with familial Type III hyperlipoproteinemia bound normally to the receptor. In one patient immunoglobulin was shown to be associated with IDL and LDL. Thus, hyperlipoproteinemia reflected an impaired metabolism of IDL, probably secondary to the binding of immunoglobulin to the lipoproteins. A similar impairment of receptor-mediated LDL catabolism did not elevate the plasma LDL concentration because of the low IDL-to-LDL conversion rate.
Spontaneous hyperglycemia and impaired glucose tolerance in athymic nude BALB/c mice.
Basal plasma glucose, glucose tolerance, and insulin secretion were investigated in young and mature athymic nude BALB/c mice and in age-matched controls. Basal plasma glucose levels in male athymic nude mice were similar to those of controls at 1, 3, and 4 wk of age. At 6, 8, and 12 wk of age, male athymic nudes had significantly higher basal plasma glucose levels when compared with controls (P less than 0.01). Plasma immunoreactive insulin concentrations were similar in athymic nudes and controls at 1 wk of age, but at 3 wk of age and subsequently at 6, 8, and 12 wk athymic nude mice had significantly decreased insulin levels when compared with their age-matched controls (P less than 0.05). We found impaired glucose tolerance in male athymic nude mice at all age groups when compared with both female athymic nudes and control BALB/c mice. The discovery of a spontaneous diabetic syndrome (hyperglycemia, impaired glucose tolerance, and decreased insulin secretion) in a colony of athymic nude mice may provide an excellent model for studying the genetics and interactions between the immune and endocrine systems.
Dietary fiber and blood lipids: treatment of hypercholesterolemia with guar crispbread.
Eleven hyperlipidemic patients took an average of 13 g guar in crispbread form over 2- to 8-week periods. Eight weeks' treatment (seven patients) reduced total serum cholesterol by 13% (P less than 0.002) while high-density lipoprotein cholesterol was unchanged. A 13% nonsignificant reduction was also seen in serum triglyceride. Comparison of blood lipid changes over 2-week periods showed guar crispbread to be as effective as guar given in hydrated (eight patients) or semihydrated form (four patients). In addition total serum cholesterol was lowered significantly (11%, P less than 0.05) in five patients where cholestyramine was ineffective. Due to its acceptability, guar crispbread is likely to prove a useful cholesterol-lowering agent.
Dietary fiber and blood lipids: reduction of serum cholesterol in type II hyperlipidemia by guar gum.
Guar gum, a storage polysaccharide galactomannan and a form of dietary fiber, was administered to 10 patients with type II a or b hyperlipidemia for 2 weeks. Five grams of gum was given before each of three meals daily, either in a specially prepared soup or mixed with fruit juice or milk. No other deliberate change of diet was made. Three patients had been taking 12 to 16 g/day of cholestyramine for more than 2 years and one had been taking 1000 mg of clofibrate daily. These drugs were continued throughout the trial. Serum cholesterol levels of all 10 patients had been stable for 6 to 18 months before the trial at the start of which the mean level was 345 +/- 15 mg/dl. After 2 weeks of guar gum the mean was 308 +/- 16 mg/dl, a fall of 10.6% (P less than 0.01). Serum triglyceride was not changed significantly. Guar gum, which can be incorporated into foods, merits further study as a potential hypocholesterolemic agent.
Reduction of blood lipids by guar crispbread.
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Reduction of serum cholesterol in type II hyperlipidaemia by guar gum.
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Effect of dietary fiber on complications of gastric surgery: prevention of postprandial hypoglycemia by pectin.
The dumping syndrome is a very troublesome problem to some patients after gastric surgery. Gel-forming carbohydrates have recently been used to modify glucose absorption. The addition of 14.5 g of pectin to a 50-g oral glucose load prevented the occurrence of hypoglycemic symptoms and maintained the blood glucose levels above control values by 64% at 90 min (P less than 0.002) and 46% at 120 min (P less than 0.01) in postgastric surgery patients whose 120-min values after 50 g of glucose alone had fallen below 50 mg per 100 ml (2.8 mmoles per liter). Breath H2 production, used as an index of bacterial fermentation of glucose, was abolished or reduced by pectin in all 5 cases in which this had previously occurred. A trial of 10 g of pectin per day prevented recurrent postprandial hypoglycemic attacks in the most severely affected individual. Pectin and perhaps other unabsorbable polysaccharides are likely to prove useful in the treatment of abnormal carbohydrate absorption after gastric surgery.
Guar gum in hyperlipidaemia.
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Letter: Fetomaternal haemorrhage and fetofetal transfusion syndrome.
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Serum immunoglobulins in multiple pregnancy.
The concentrations of immunoglobulins (Ig) G.A.M. and E were determined in paired umbilical cord and maternal sera in 50 twin pregnancies. Mean IgG levels were higher in cord than maternal sera and in most cases the cord IgG level related more closely to that of the other twin than to either maternal level or birthweight, and was in the range for singletons of the same gestational age. The three cases of fetofetal transfusion syndrome were exceptional in the large difference between IgG concentrations in recipient and donor twins. The discrepancy was much greater than that found between the levels of proteins produced by the fetus, suggesting a disturbance in maternofetal placental transfer. IgM was detected in all cord sera, with one exception, and the level was not related to order of birth. IgA was detected in 16% of cord sera, 13% in sera from first borns. IgE was detected in only 8% of cord sera and there was no evidence of placental transfer.
Serum IgG levels in feto-fetal transfusion syndrome.
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Evaluation of an Audiovisual Diabetes Education Program: negative results of a randomized trial of patients with non-insulin-dependent diabetes mellitus.
A randomized controlled trial was conducted to determine whether an education program specifically designed for patients with non-insulin-dependent diabetes and limited literacy could improve and sustain glucose and weight control. From a referral clinic, 120 obese (greater than 130 per cent of ideal body weight) diabetic patients who were not taking insulin were recruited. Of these, 55 per cent were female and 49 per cent were black; the mean age was 53 years. Mean glycosylated hemoglobin (HbA1%) was 10.2 per cent. Each subject was assigned to one of three groups: monthly group sessions with videotapes for diabetic persons with low literacy skills; monthly group sessions without videotapes; or no monthly sessions. After seven months, there had been 16 dropouts (13 per cent). Differences in weight changes between groups were significant (p less than 0.05); group 1 lost a median of 1 kg of weight (p less than 0.05) compared with a 0.1-kg loss and no change in groups 2 and 3, respectively. This weight loss was not sustained at 11 months. There was no significant change in HbA1%. Age, education, and compliance beliefs did not predict outcome. The authors conclude that the patient education programs did not result in sustained glucose or weight control.