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Biomedical subjects

G Slama

Publications and source records attributed to G Slama.

At least 91 records · Page 5Linked to original sources
PubMed1996

Effects of long-term low-glycaemic index starchy food on plasma glucose and lipid concentrations and adipose tissue cellularity in normal and diabetic rats.

The present study aimed to assess the metabolic consequences of the chronic ingestion of two starches giving different postprandial glycaemic responses in normal and diabetic rats. The two starches chosen were mung-bean (Phaseolus aureus) starch (97% pure starch) and wheat starch presented as ground French toast. First, we studied the characteristics of these two starches. In vitro the alpha-amylase (EC 3.2.1.1) digestibilities of these starches were 40 (SE 3) and 62 (SE 4)% respectively at 30 min, whereas the contents of resistant starch were 77 (SE 4) and 22 (SE 4) g/kg respectively. In vivo the mung-bean starch produced lower postprandial glycaemic responses than the wheat starch (areas under the curve were: 91 (SE 28) and 208 (SE 33) mmol.min/l, P < 0.05) in normal rats (n 8). We then submitted twenty-eight normal and twenty-eight diabetic (neonatal streptozotocin on second day of birth) male Sprague-Dawley rats (6 weeks old) to a diet containing 570 g starch/kg as either mung-bean starch or wheat starch (n 14 rats/group). After 5 weeks on the diets food intakes and body weights were identical in each group. Liver and kidney weights were comparable when expressed as relative weight. The mung-bean-starch diet slightly decreased epididymal fat-pad weight (P < 0.14, ANOVA) and led to a marked decrease in adipocyte volume (P < 0.05). Plasma triacylglycerol and phospholipid concentrations were lower after the mung-bean-starch diet than after the wheat-starch diet in both normal and diabetic rats, whereas free fatty acid concentrations were lower only in normal rats. Similarly, non-fasting plasma glucose concentrations decreased (P < 0.05) in normal rats fed on mung-bean starch but not in diabetic ones (P < 0.14). Insulin levels tended to be lower, but not significantly, after mung-bean-starch feeding than after wheat starch. We conclude that the replacement of 570 g wheat starch/kg diet with mung-bean starch for 5 weeks resulted in (1) lowered non-fasting plasma glucose and free fatty acid levels in normal but not in diabetic rats, (2) a reduction in plasma triacylglycerol concentration and adipocyte volume in both normal and diabetic rats. Thus, the type of starch mixed into the diet may have important metabolic consequences in normal and diabetic rats.

Adipocytes↗
PubMed1996

Chronic consumption of short-chain fructooligosaccharides by healthy subjects decreased basal hepatic glucose production but had no effect on insulin-stimulated glucose metabolism.

We aimed to study the effects of chronic ingestion of short-chain fructooligosaccharides (FOS), an indigestible carbohydrate, on hepatic glucose production, insulin-mediated glucose metabolism, erythrocyte insulin binding, and blood lipids in healthy subjects. Twelve healthy volunteers received either 20 g FOS/d or sucrose for 4 wk in a double-blind crossover design. FOS did not modify fasting plasma glucose and insulin concentrations. Mean (+/- SEM) basal hepatic glucose production was lower after FOS than after sucrose consumption (2.18 +/- 0.10 compared with 2.32 +/- 0.09 mg.kg-1, min-1, respectively; P < 0.02, paired Student's t test). However, neither insulin suppression of hepatic glucose production nor insulin stimulation of glucose uptake measured by hyperinsulinemic clamp was significantly different between the two dietary periods. Erythrocyte insulin binding was also comparable. Serum triacylglycerols, total and high-density- lipoprotein cholesterol, apolipoproteins A-I and B, and lipoprotein(a) were not modified by FOS. To try to understand why FOS did not increase serum lipids, the in vitro production of short-chain fatty acids from FOS was evaluated by using human fecal inoculum and compared with that from lactulose, which was found to increase serum lipids. FOS produced an acetate-propionate ratio two times lower than that of lactulose. We conclude that 4 wk of 20 g FOS/d decreased basal hepatic glucose production but had no detectable effect on insulin-stimulated glucose metabolism in healthy subjects. The colonic fermentation pattern of undigestible carbohydrates may be relevant to predicting their metabolic effects.

Adult↗
PubMed1996

Dietary (n-3) polyunsaturated fatty acids improve adipocyte insulin action and glucose metabolism in insulin-resistant rats: relation to membrane fatty acids.

To study the effects of dietary fish oil on insulin-stimulated glucose metabolism in adipocytes of insulin-resistant rats (rats fed 50% sucrose and 30% fat), eighteen 5-wk-old Sprague-Dawley rats were fed, for 6 wk, a diet containing 30% fat as either fish oil (FO) or a mixture of vegetable and animal oils [control oils (CO)]. A third reference group was fed a standard diet (62% corn starch and 13% fat). At the end of the 6-wk period, the two experimental groups had comparable plasma glucose concentrations that were higher than that found in the reference group. FO feeding corrected the hyperinsulinemia of the experimental rats (P < 0.05) to reach values in the reference group. Plasma triacylglycerol (P < 0.01) and cholesterol (P < 0.001) concentrations were also lower in rats fed FO than in those fed CO. The body weights of FO-fed rats were similar to that of CO-fed rats, but epididymal adipose tissue weight was lower (P < 0.01). Adipocytes of FO-fed rats, compared with those of CO-fed rats, had high insulin-stimulated glucose transport (P < 0.05), oxidation (P < 0.001) and incorporation into total lipids (P < 0.05). The incorporation of (n-3) polyunsaturated fatty acids in adipocyte membrane phospholipids was higher in FO-fed rats than in those fed CO (P < 0.0001). Insulin action was positively correlated with the fatty acid unsaturation index in membrane phospholipids. Thus dietary fish oil has beneficial effects on insulinemia, plasma lipids and insulin-stimulated glucose metabolism in insulin-resistant slightly diabetic rats.

Adipocytes↗
PubMed1996

Lack of effect of an acute ileal perfusion of short-chain fatty acids on glucose metabolism in healthy men.

Dietary fiber intake is associated with several beneficial effects on carbohydrate metabolism. Some authors have speculated that this improvement may be due to short-chain fatty acids (SCFA) produced by the colonic fermentation of dietary fibers. To test this hypothesis, six healthy men aged 26 +/- 2 (SE) yr with a body mass index of 20.9 +/- 0.7 received on three occasions an 18-h ileal perfusion infused at a flow rate of 3.3 ml/min, containing either 90 mmol/l of SCFA (60% acetate, 25% propionate, and 15% butyrate) (A), SCFA during the first 12 h and then a saline solution (A/S), or a saline solution (S). Basal hepatic glucose production (BHGP), insulin sensitivity (3-step euglycemic-hyperinsulinic clamp), and erythrocyte insulin binding (EIB) were studied 12 h after the beginning of the ileal perfusion. There was no change in BHGP or insulin sensitivity. However, maximal EIB was significantly different: 7.1 +/- 0.1 (A), 6.8 +/- 0.1 (A/S), vs. 6.5 +/- 0.1% (S) (P = 0.03). We conclude that acute administration of SCFA does not significantly alter glucose metabolism in healthy subjects.

Acetates↗
PubMed1996

Laboratory diagnosis of HIV infection in Papua New Guinea.

In Papua New Guinea, the laboratory diagnosis of HIV infection is based on proof of HIV antibody in the patient's serum. Under the government scheme, the testing is done in 30 laboratories, including the Papua New Guinea HIV Reference Laboratory (NRL), the Red Cross Blood Transfusion Service in Port Moresby, and 19 provincial and 9 district laboratories. An alternative testing strategy was adopted in 1993 based on a WHO recommendation, replacing the classical testing strategy (enzyme immunoassay + Western blot). The alternative testing strategy uses several EIA, rapid or simple HIV antibody assays for the detection and confirmation of the HIV antibody. This approach is faster and cheaper, with the same sensitivity and specificity as the classical testing algorithm. Except for the NRL, the Serodia Fujirebio HIV-1 gelatin particle agglutination assay is used throughout the country as the screening test. The PNG National HIV Reference Laboratory is the only laboratory authorized to perform confirmatory testing and to release positive results. Therefore, all serum samples reactive in the screening assay are sent to the NRL for confirmation by the battery of EIA, rapid or simple assays in accordance with the alternative testing strategy adopted. The paper explains the alternative testing strategy and highlights the principle of each individual test that is employed.

AIDS Serodiagnosis↗
PubMed1995

Low-fat (41%) butter consumption decreases total energy and lipid intake in diabetic patients under acute conditions.

Decreasing fat intake in subjects at risk of cardiovascular diseases and particularly diabetics is a major issue. To investigate whether low-fat (41%) butter (LFB) is of any benefit compared to regular butter (RB), 97 hospitalized diabetics (41 insulin-dependent) were studied on four consecutive days. Breakfast (bread, butter and drink) was served at 0830 hrs, on successive mornings. LFB and RB were presented ad libitum, on alternate days. Satiety was assessed at 10 and 12 h, using line rating scales. At 1230 hrs lunch was served, with large servings corresponding to 130% of the recommended lunch intake, so that carry-over effects from the breakfast manipulation could be measured. At breakfast, LFB was consumed in higher amounts, 27 vs. 21 g, F(1,96) = 33.24, p < 0.0001, than RB; however, the energy intake was significantly lower (by about -38%) on LFB days, F(1,96) = 158.3, p = 0.0001. Hunger at 10 h but not at 12 h was affected by breakfast conditions. Lunch intake was comparable following LFB and RB breakfasts. In conclusion, LFB utilization under acute conditions seems to benefit diabetics by reducing caloric and fat intake.

Adult↗
PubMed1995

Low-fat (41%) butter use decreases butter lipid intake over 4-week trials in healthy persons.

All members of 18 families (n = 75; ages from 1 to 65 years) participated in a cross-over study of butter usage. Two types of butter were compared: regular (82%) fat) and low-fat (41%) butter. Butter was supplied to the families by the laboratory for use in raw (spread) form over two successive periods of 5 weeks (first week served as training). No other butter was allowed. The number of consumers (75) remained constant throughout the study. Over four consecutive weeks, the families consumed as much low-fat as regular butter (10.70 +/- 1 g versus 10.06 +/- 1.17 g per day per person). However, lipid intake from butter was significantly reduced during the low-fat butter period as compared to the regular butter period (4.39 +/- 0.41 g versus 8.25 +/- 0.96 g per day per person, p = 0.0005). Since previous studies showed that nutrient-specific compensatory intake is unlikely, it is suggested that use of low-fat butter can facilitate a reduction in fat intake over extended periods of time in healthy persons.

Adolescent↗
PubMed1995

Effects of dietary propionate on hepatic glucose production, whole-body glucose utilization, carbohydrate and lipid metabolism in normal rats.

Increased intake of dietary fibres is associated with several beneficial effects on carbohydrate and lipid metabolism. The colonic fermentation of dietary fibres produces short-chain fatty acids (SCFA; acetate, propionate and butyrate). Some authors have suggested that SCFA could be partly responsible for the effects of dietary fibres. The purpose of the present study was to test the effects of one of the SCFA, propionate. The effects of moderate amounts of dietary propionate on insulin sensitivity and hepatic glucose production were studied in male Sprague-Dawley rats. Two groups of twenty-one adult rats were fed for 3 weeks on a diet containing 78 g propionate/kg (P) or 78 g/kg of a poorly fermentable cellulose (control group; C). Feed intake, body weight, fasting plasma glucose, insulin, free fatty acids, alanine, lactate, glycerol and beta-hydroxybutyrate levels were measured weekly in anaesthetized rats. At the end of the feeding period basal hepatic glucose production (BHGP) was measured with a primed continuous infusion of [3-3H]glucose and the in vivo insulin sensitivity in rats was quantified by the euglycaemic-hyperinsulinaemic clamp technique (0.6 and 2 U/kg per h). At that time fasting plasma glucose measured in anaesthetized rats was significantly lower in group P than in group C: 7.7 (SE 0.2) v. 8.5 (SE 0.2) mmol/l respectively (P < 0.002); plasma insulin levels were not significantly different. Neither the BHGP (mg/min per kg; C 14.8 (SE 1.3), P 15.1 (SE 1.3); n 7, not significant) nor the basal metabolic clearance (ml/min per kg; 8.9 (SE 0.8) v. 9.9 (SE 1.1); not significant) were different between treatments. Hepatic glucose production and glucose utilization at the two insulin concentrations (approximately 500 and 1500 mU/l respectively, n 7) did not differ significantly between the two groups. These results show that dietary propionate chronically ingested by normal rats could decrease fasting glycaemia, but from our findings, no effect on hepatic glucose production and whole-body glucose utilization could be clearly demonstrated.

Animals↗
PubMed1995

A fructose-rich diet decreases insulin-stimulated glucose incorporation into lipids but not glucose transport in adipocytes of normal and diabetic rats.

To study the cellular mechanisms underlying fructose-induced insulin resistance in rats, the effects of fructose feeding on insulin-stimulated glucose transport, oxidation and incorporation into lipids in epididymal adipocytes were evaluated in 27 normal and 27 noninsulin-dependent diabetic male Sprague-Dawley rats. Diabetes was induced by streptozotocin injection 2 d after birth. At 5 wk of age, both normal and diabetic rats were fed a diet containing 62% carbohydrate as fructose, dextrose or cornstarch. Fructose feeding for 6 wk induced glucose intolerance in normal rats (P < 0.05) and aggravated that of diabetic rats (P < 0.05). Plasma triacylglycerol concentration was higher in fructose-fed than in starch-fed or dextrose-fed rats (P < 0.05). Adipocytes of fructose-fed rats had significantly lower maximum insulin-stimulated glucose incorporation into total lipids than those of rats fed starch, and tended (P = 0.22) to have lower production of CO2 from glucose than adipocytes of the other dietary groups. Glucose transport in adipocytes of dextrose-, starch- and fructose-fed rats did not differ. We conclude that in both normal and diabetic rats, a chronic fructose-rich diet induced hypertriacylglycerolemia, glucose intolerance and insulin resistance of adipocytes.

Adipocytes↗
PubMed1995

Symptoms, hormones, and glucose fluxes during a gradual hypoglycaemia induced by intraperitoneal vs venous insulin infusion in Type I diabetes.

Intraperitoneal (IP) insulin infusion with programmable implantable pumps is associated with a reduction in hypoglycaemic events when compared to intensive diabetes management with subcutaneous insulin in patients with Type 1 diabetes mellitus. The mechanism may involve more physiological insulin kinetics, lower peripheral insulin levels or a specific hepatic action of portal insulin on hypoglycaemic counter regulation. To investigate the latter two hypotheses, we performed two hypoglycaemic clamps (controlled blood glucose decrement to 2.2 mmol l-1) in random order in 12 Type 1 diabetic patients. Insulin was infused either IP or IV for 150 min, at rates chosen to generate similar peripheral insulin levels (1 mU/kg-1 min-1 IV or 2 mU/kg-1 min-1 IP, n = 6) to evaluate direct hepatic action, or at similar rates (1 mU/kg-1 min-1 IV and IP, n = 6) to evaluate IP indirect effects via lower peripheral insulinaemia. Hepatic glucose production and glucose utilization were measured by [6.6 2H] glucose dilution technique. Glucose production was lower (1.7 +/- 0.4 vs 0.5 +/- 0.4 mg kg-1 min-1, p < 0.05), and utilization was similar at the end of the matched-insulinaemia IV and IP clamps, respectively. By contrast, glucose production was higher (1.7 +/- 0.5 IV vs 2.7 +/- 0.3 IP mg kg-1 min-1, p < 0.01) and glucose utilization lower (4.4 +/- 1.0 IV vs 3.3 +/- 0.2 IP mg kg-1 min-1, p < 0.05) with IP delivery at the end of the matched-dose clamps. Counterregulatory hormones and hypoglycaemic symptoms increased similarly in all clamps. In summary, IP insulin, when compared to IV insulin at similar delivery rates, but not at similar insulinaemia, is associated with a less negative glucose balance (glucose production-glucose utilization) during hypoglycaemia. Such a mechanism may play a role in the reduced hypoglycaemic risk seen with IP implantable pumps.

Adult↗
PubMed1995

[Prevention of late complications of insulin dependent diabetes. How far and at what price?].

The essential role of chronic hyperglycaemia in the development of complications was suspected and accepted in Europe more than 20 years ago. A large number of epidemiological, clinical biochemical and experimental arguments together with certain clinical trials have demonstrated the importance of the best possible glycaemic control in patients with diabetes mellitus. Changing ideas, the development of new equipment (pumps, pens, single-use seringues) and the widespread use of self-measurement techniques has confirmed the validity of this attitude. Recent results of the American study (DCCT Diabetes Control and Complications Trial) has recently clearly confirmed this position which is now firmly established and no longer a subject of debate. There are nevertheless, certain limitations: the aim of glucose normalization should not be limited to patients with a risk of late microvascular complications, i.e. in patients with a sufficiently long life-expectancy, or those whose short-term survival is not threatened and who do not have a life-threatening intercurrent disease. An increased risk for hypoglycaemia, including the most severe episodes, is the price to pay for intensifying treatment. This risk cannot be totally eliminated, but can be minimized by intensifying patient training and, perhaps, by using new tools such as external pumps or implantable pumps. In any case, no matter how much time and effort are spent, the fact that the basic tool is imperfect (peripherally administered insulin without feedback control) means that further research is required to find other ways administering insulin.(ABSTRACT TRUNCATED AT 250 WORDS)

Diabetes Mellitus, Type 1↗
PubMed1995

[Current methods for optimal insulin therapy].

The DCCT study confirmed the importance of optimizing insulin therapy to reduce the microvascular risks of diabetes mellitus. Optimization requires improving the methods already in use. Recent results must be used to improve patient motivation. Control of blood glucose levels must include improving the frequency and/or the quality of follow-up (pluridisciplinary consultations). Follow-up must be improved, taking advantage of the recent developments such as rapid glycosylated haemoglobin assay and computerized glucose meters. Of course, improvement in blood glucose must aim at normal levels, accepting the increased risk of hypoglycaemia. The insulin-tool itself must be improved on the basis of recent developments including ultra-rapid analogues and external and implantable insulin pumps. Finally, a major challenge is to develop these improvements without increasing too greatly the patient's short-term costs and without causing further discomfort.

Blood Glucose↗