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Biomedical subjects

B I Joffe

Publications and source records attributed to B I Joffe.

At least 55 records · Page 3Linked to original sources
PubMed1995

Microalbuminuria is not associated with cardiovascular disease in patients with homozygous familial hypercholesterolaemia.

Microalbuminuria is thought to be a predictor of cardiovascular disease (CVD). A high prevalence of microalbuminuria might therefore be expected in patients with homozygous familial hypercholesterolaemia (HFH), as they develop severe premature atherosclerosis. We tested for this in 15 HFH patients (M = 9, F = 6; mean age 19.3 years). Urinary albumin excretion (UAER) were normal in all patients [corrected]. In addition, there was no difference in the mean urinary albumin excretion rate (UAER) between those with documented CVD (n = 8; UAER = 5.17 micrograms/min) and those without (n = 7; UAER = 3.60 micrograms/min). There is therefore no association between microalbuminuria and CVD in HFH.

Adolescent↗
PubMed1994

Effects of inspired air conditions on catecholamine response to exercise in asthma.

The influence of different inspired air conditions on exercise-induced bronchoconstriction (EIB) is well appreciated. However, the mechanism by which this influence is exerted is uncertain. To determine if varied inspired air conditions during exercise could affect the catecholamine response to physical exercise, we had 13 asthmatic and 6 healthy children (aged 10-18 years) undergo two bouts of cycle ergometry tests under different air conditions. One test was done while breathing cold dry (CD) air (temperature, -20.2 degrees C; relative humidity, 0%) and the other while breathing warm humid (WH) air (temperature, 34.3 degrees C; relative humidity, 100%). Forced expiratory volume in 1 second (FEV1) and plasma catecholamine concentrations were recorded before and after exercise. Marked EIB (48 +/- 5% SEM fall in FEV1 from baseline) developed in all asthmatics after the CD exercise, but no EIB was noted after the WH exercise. Normal controls had no EIB under either test conditions. Plasma levels of catecholamines at rest, and the changes that occurred during and after exercise, were comparable within as well as between the groups in both tests. Catecholamines did not rise in asthmatics following development of EIB. These data demonstrate that inspired air conditions do not influence the sympathoadrenal response to exercise, at least as reflected in plasma catecholamine levels. In fact, this response did not differ between asthmatics and normals, irrespective of the development of EIB. These results are consistent with previous reports about impaired catecholamine response of asthmatics to bronchoconstriction.

Adolescent↗
PubMed1994

Lack of effect of high dose vitamin E on xanthoma regression in homozygous familial hypercholesterolaemia.

There is increasing evidence that oxidative modification of low-density lipoprotein (LDL) plays an important role in the pathogenesis of atherosclerosis. Homozygous familial hypercholesterolaemia (HFH) is characterized by premature, severe atherosclerosis. Drugs available at present are ineffective in lowering the markedly elevated LDL levels in this condition; antioxidant therapy to protect the LDL against oxidation may be of benefit. Probucol, the only drug shown to induce xanthoma regression in HFH, is a potent antioxidant, but it also lowers high-density lipoprotein cholesterol (HDL-C) levels, causing some concern. Vitamin E is a naturally occurring antioxidant that does not affect HDL-C levels. We have therefore evaluated the effect of long-term high dose vitamin E on xanthoma regression in HFH. Ten subjects with HFH, mean age 17 years (range 4-34), received vitamin E (400-1000 mg/dl alpha-tocopherol acetate/day) for a period of 23 months (range 12-27). There was a 4.2-fold increase in the mean serum vitamin E level (mean (S.D.) 49.7 (19.9) to 177.9 (45.6) mumol/l; P < 0.005), but no change in serum lipid or lipoprotein concentrations. Although there was an increase in the in vitro resistance of LDL to oxidation as determined by the duration of the lag phase during copper-mediated oxidation (116 (8.34) vs. 141.5 (9.23) min; P < 0.005) there was no xanthoma regression; in fact they progressed in 4 subjects. Unlike probucol, high dose long-term vitamin E has no demonstrable effect on xanthoma regression in HFH.

Administration, Oral↗
PubMed1994

Perindopril and physiologic responses to exercise.

Cardiovascular drugs have varying effects on hemodynamic, metabolic, and hormonal responses to exercise. To evaluate the effects of the novel angiotensin-converting enzyme (ACE) inhibitor, perindopril on these exercise-related responses, we studied 9 healthy volunteers in a double-blind, randomized, placebo-controlled trial. After a week of perindopril 4 mg orally daily or placebo therapy, volunteers performed a treadmill effort test; the sequence was repeated after a 1-week washout period. Perindopril caused a significant reduction in mean resting systolic and diastolic blood pressure (SBP, DBP) without increasing resting heart rate (HR); 15-min post-exercise SBP was also significantly reduced. There were no significant differences between the perindopril and placebo effort tests with respect to metabolic indexes studied (serum K+, plasma glucose, plasma free fatty acids) or plasma hormonal concentrations measured (ACTH and cortisol, norepinephrine (NE) and epinephrine (EPI), glucagon and insulin, growth hormone and prolactin, renin activity). In the perindopril arm of the study, however, there were modest but significant increases in mean serum K+ before exercise to immediately after exercise (0.4 +/- 0.1 mM, p < 0.01) and mean plasma glucose from before exercise to 5 min (0.6 +/- 0.2 mM, p < 0.01) and 15 min (0.5 +/- 0.2 mM, p < 0.05) after exercise. These data show that perindopril does not impair the hormonal changes associated with exercise in healthy subjects but induces a more consistent increase in blood K+ and glucose concentrations.

Adrenocorticotropic Hormone↗
PubMed1994

Insulin-mediated glucose disposal in black south Africans with essential hypertension.

We used the hyperinsulinaemic euglycaemic clamp method to assess insulin-mediated glucose disposal in ten black South African patients with newly-diagnosed essential hypertension, compared to ten normotensive controls. The patients were all nonobese with normal glucose tolerance. Comparisons were made before and 12 weeks after treatment with a long-acting ACE inhibitor. The mean glucose disposal (M) and disposal expressed as glucose sensitivity index (M/I) were significantly reduced in the hypertensives vs. controls (M: 6.8 +/- 0.9 vs. 9.7 +/- 0.8 mg/kg/min; MI: 7.1 +/- 1.0 vs. 12.5 +/- 1.7 mg/kg/min/mU/l x 100) (p = 0.03 and 0.01, respectively). Following therapy, M/I increased in the patients to values not significantly different to those of the controls. Insulin resistance is an independent feature of essential hypertension in black South African patients, and is partially corrected by treatment with a long-acting ACE inhibitor.

Adult↗
PubMed1994

On the distribution of catecholamines in Promesostoma balticum (Turbellaria, Neorhabdocoela, Promesostomatidae).

The distribution of putative catecholamines has been previously studied in the nervous system of three Promesostoma species using the glyoxylic-acid-induced fluorescence (GAIF) method. In this communication, the results are reported of a similar study of Promesostoma balticum, which is classified to another group of species in the genus. Promesostoma species from two different species groups differed in the position of neurons associated with the ventral and lateral cords. All the studied species of Promesostoma demonstrated doubled dorsal neurons in so called anterior complex (AnDo), a character which differentiates this genus from the other studied Typhloplanoida.

Animals↗
PubMed1993

Selected risk factors for coronary heart disease in male scholars from the major South African population groups.

A number of risk factors for coronary heart disease (CHD) in 7 groups of South African male scholars aged between 15 and 20 years were surveyed. Selection of the groups was based on socioeconomic status and comprised urban and rural blacks, Indians of higher and lower socio-economic status, coloureds of higher and lower socioeconomic status, and middle-class whites. Both Indian groups, both coloured groups and the whites had a much greater prevalence and severity of CHD risk factors than the two black groups. This held for total cholesterol, low-density lipoprotein cholesterol (LDLC), high-density lipoprotein cholesterol (HDLC), the HDLC/LDLC ratio, apolipoprotein B, apolipoprotein A-I, insulin, fibrinogen and mass. One exception was lipoprotein a, levels of which were higher in both black groups. In general the CHD risk factor profile was worse in the higher socio-economic groups, and it also tended to be worse in urban than in rural blacks. These findings stress the need to reduce CHD risk factors in our developed populations and to prevent their emergence in our developing peoples.

Adolescent↗
PubMed1992

Pathogenesis of non-insulin-dependent diabetes mellitus in the black population of southern Africa.

Non-insulin-dependent diabetes mellitus (NIDDM) is an important health problem in the black population of southern Africa. Whether the primary cause of NIDDM is insulin secretory dysfunction or peripheral insulin resistance is unknown. In westernised populations it is believed that insulin resistance and hyperinsulinaemia occur in the early stages of disease, followed later by progressive impairment of insulin secretion. However, we suggest that in the southern African black population a decrease in the mass of functioning beta cells is an important event, making these people vulnerable to the deleterious effects of insulin resistance induced by obesity and other factors. These abnormalities are, in turn, associated with insulin receptor down-regulation. An accelerated decline in beta-cell function then follows in susceptible individuals, ultimately producing striking insulinopenia. Insulinopenic NIDDM in black southern Africans may partly explain why this population has a comparatively low incidence of macrovascular complications and also predicts a short-lived therapeutic response to oral sulphonylureas in most patients.

Black or African American↗
PubMed1992

Autonomic dysfunction in systemic sclerosis: sympathetic overactivity and instability.

PURPOSE: This study was designed to assess the prevalence and nature of autonomic dysfunction (AD) in 34 patients with systemic sclerosis (SSc). PATIENTS AND METHODS: Patients were questioned for current symptoms possibly related to AD. Five noninvasive cardiovascular autonomic function tests and sequential plasma catecholamine estimations at rest, during standing, and during sustained handgrip were performed. Seven patients with manometrically documented esophageal involvement and high resting plasma adrenaline levels were treated with clonidine (75 to 375 micrograms/d). One month later, resting plasma catecholamine estimations and esophageal motility studies were repeated. RESULTS: Autonomic testing revealed AD in each patient, while symptoms were experienced by 33 of them. Findings on two of the three heart rate tests and both blood pressure tests were significantly impaired as compared with those in 25 matched control subjects. Mean resting plasma adrenaline levels were 18 times higher than in 10 matched controls (p less than 0.001). Plasma catecholamine (adrenaline, noradrenaline, and dopamine) concentrations and mean arterial blood pressures fluctuated inappropriately during standing and sustained handgrip in 28 (82%) of the patients. The presence of headaches correlated significantly with sympathetic overactivity and instability (p less than 0.05). Resting plasma adrenaline concentrations correlated inversely with disease duration (p less than 0.05). Significant suppression of sympathetic overactivity and increases in resting lower esophageal sphincter pressures were observed in the seven patients treated with clonidine. CONCLUSION: AD is extremely common in SSc. It is characterized by parasympathetic impairment and marked sympathetic overactivity, particularly in early disease. The potential role of AD in the pathogenesis of SSc deserves further study.

Adult↗
PubMed1992

Insulin-receptor activity in nondiabetic and diabetic urbanized South African black women.

OBJECTIVE: To evaluate insulin receptor binding characteristics of urbanized South African black women with normal glucose tolerance and of patients with newly diagnosed untreated non-insulin-dependent diabetes mellitus (NIDDM). RESEARCH DESIGN AND METHODS: Four groups of 10 subjects each were selected by the following criteria: group A, young (20-39 yr) nonobese (body mass index [BMI] 19.0-24.9 kg/m2) nondiabetic women; group B, middle-aged (40-60 yr) nonobese nondiabetic women; group C, middle-aged obese (BMI greater than 30.0 kg/m2) nondiabetic women; and group D, middle-aged obese newly diagnosed but untreated female patients with NIDDM. Insulin binding to monocyte receptors was determined by radioreceptor assay. Fasting plasma samples were analyzed for glucose, insulin, C-peptide, and nonesterified fatty acids. RESULTS: In the four groups studied, maximum specific binding and receptor concentration were highest in group A, with a progressive and significant decrease in values through groups B and C to group D. Significant inverse correlations were obtained between maximum specific binding, 50% inhibition dose, and total receptor concentration on the one hand and glucose, insulin, and NEFA on the other. CONCLUSIONS: Our study of urban South African black women showed decreasing insulin-receptor activity with obesity and glucose intolerance. In patients with NIDDM, hyperglycemia and beta-cell dysfunction were associated with a reduction in receptor concentration. In this regard, our findings in South African blacks are consistent with results of similar studies of NIDDM in other communities.

Adult↗
PubMed1992

Relationship between plasma insulin and blood pressure in South African black women in Johannesburg.

OBJECTIVE: To examine the relationship between fasting plasma insulin and blood pressure (BP) in 40 urbanized normotensive South African black women aged 24-60 yr, and to assess the effects of body mass index (BMI) and fasting plasma glucose on BP. RESEARCH DESIGN AND METHODS: The women comprised equal numbers of young nonobese nondiabetic subjects, middle-aged nonobese nondiabetic subjects, middle-aged obese nondiabetic subjects, and middle-aged obese newly diagnosed non-insulin-dependent diabetic subjects. Systolic and diastolic BPs were recorded (in duplicate) after 15 min of recumbency, and fasting plasma glucose and insulin levels were determined thereafter. The data were analyzed by simple and multivariate regression. RESULTS: There was a wide distribution of individual physical and biochemical features. With simple correlations, systolic BP correlated significantly with age, BMI, and fasting glucose but not with insulin. Diastolic BP correlated significantly with all four variables (r = 0.37, P less than 0.05). When adjusted for age, BMI, and glucose, however, the significant correlation between diastolic BP and insulin diminished (r = -0.04). CONCLUSIONS: As in other nonwhite communities, plasma insulin does not appear to play a major role in regulating the BP of South African black women.

Adult↗
PubMed1991

Glycaemic responses to different carbohydrate foods in healthy and diabetic blacks in Soweto.

Diabetes mellitus is uncommon in rural southern African blacks. With urbanisation and lifestyle changes, incidence rises to that in western populations. To assess associated changes in carbohydrate metabolism, glycaemic responses to glucose, refined maize, refined rice and bread were studied in 8 healthy and 8 non-insulin-dependent diabetic urban blacks. Additionally, in the healthy group serum insulin responses were measured. In the healthy, maize (the staple food of blacks) elicited the highest glucose response (207 mmol/l/min) and bread the lowest (107 mmol/l/min). The glycaemic indices of maize and glucose were similar. Serum insulin responses to maize were significantly lower than that of bread at 90 minutes (maize 66 muU/ml; bread 93 muU/ml; P = 0.02). In diabetics, maize and glucose elicited similar glycaemia (928 mmol/l/min and 921 mmol/l/min respectively). The high glucose response to maize could relate to its processing and physical form. The low insulin secretion could be due to inadequate stimulation by the 'entero-insular' axis. Moreover, variability in glucose insulin responses could stem from ethnic or genetic reasons. In the dietary management of black diabetics, refined maize should be replaced by other cereals.

Adult↗
PubMed1991

Hypoglycemia in hepatocellular carcinoma: failure of short-term growth hormone administration to reduce enhanced glucose requirements.

The mechanism of tumor-associated hypoglycemia was investigated in 10 (six hypoglycemic and four normoglycemic) southern African blacks with hepatocellular carcinoma. The mean basal blood glucose concentration was significantly lower (2.4 +/- 0.1 v 3.6 +/- 0.2 mmol/L; P less than .01) and steady-state exogenous glucose requirements were increased fourfold (3.6 +/- 0.6 v 0.97 +/- 0.2 mg/kg/min; P less than .01) in the hypoglycemic compared with the normoglycemic patients. Plasma insulin and C-peptide levels were suppressed to the lower limit of sensitivity of each of the assays in both groups of patients. The concentrations of insulin-like growth factors (IGF) I and II were lower (19 +/- 1.6 v 25 +/- 4.6 insulin-like growth factors (IGF) I and II were lower (19 +/- 1.6 v 25 +/- 4.6 ng/L) and higher (230 +/- 42 v 173 +/- 40 ng/L), respectively, in the hypoglycemic patients, although the differences were not statistically significant. Of the counterregulatory hormones measured, only the growth hormone (GH) concentration was significantly lower in the hypoglycemic patients (0.9 +/- 0.2 v 18.6 +/- 5.6 micrograms/L; P less than .01). Correction of the plasma GH level into the high-normal physiological range in two hypoglycemic patients failed to reduce steady-state exogenous glucose requirements. However, the glucose requirements were reduced from 2.6 to 1.1 mg/kg/min in the same two patients when "acromegalic" plasma concentrations of GH were achieved. We conclude that steady-state glucose requirements are increased in black patients with hypoglycemia complicating hepatocellular carcinoma, and that short-term correction of the associated hyposomatotropism fails to reduce the enhanced requirements.

Blood Glucose↗
PubMed1990

The effect of magnesium sulphate infusion on circulating catecholamine levels in severe gestational proteinuric hypertension. A report of 8 cases.

The effect of magnesium sulphate (MgSO4) infusion on blood pressure and circulating venous catecholamine levels in 8 patients with severe gestational proteinuric hypertension is described. A significant fall in blood pressure was noted after MgSO4 infusion; the maximal fall in diastolic blood pressure correlated with the greatest rise in serum magnesium levels (P less than 0.04). No significant change was observed in mean venous plasma adrenaline or noradrenaline levels after MgSO4 infusion, although the mean dopamine concentration declined significantly. It is concluded that the decrease in systemic vascular resistance after MgSO4 infusion in gestational proteinuric hypertension is mediated predominantly by mechanisms other than a change in circulating catecholamine levels.

Adult↗
PubMed1990

Methaemoglobinaemia due to accidental sodium nitrite poisoning. Report of 10 cases.

Nitrates and nitrites are widely used in the food and chemical industry. Poisoning with these agents may be potentially life-threatening as a result of the production of methaemoglobin. A group of 10 patients suffering from moderate to severe methaemoglobinaemia after accidental intoxication with a sodium nitrite salt is described. One patient died but the other 9 recovered rapidly. The low mortality rate was attributed to prompt diagnosis and institution of appropriate therapy with methylene blue and ascorbic acid.

Adult↗
PubMed1990

Growth hormone response to exercise in asthmatic and normal children.

Maximal growth hormone (GH) increments following exercise were compared in asthmatic (n = 14) and normal (n = 8) children. Exercise, which consisted of 6 min ergometer cycling while breathing cold dry (CD) air, induced asthma in all asthmatic patients but not in normal subjects. Baseline plasma GH levels were similar in both groups. Following exercise, however, asthmatic patients had significantly higher mean GH increments than normal subjects (14.8 vs 4.9 ng/ml, P less than 0.025). To evaluate the possible role of bronchoconstriction in the GH response all subjects exercised again, this time while breathing warm humid (WH) air. Despite the absence of exercise-induced asthma (EIA) while breathing WH air, asthmatic patients still had significantly higher mean GH increments than normal subjects (9.2 vs 2.3 ng/ml, P less than 0.05). We conclude that some asthmatic children show excessive GH secretion after exercise regardless of inspired air conditions or the development of EIA.

Adolescent↗