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Biomedical subjects

G Slama

Publications and source records attributed to G Slama.

At least 199 records · Page 11Linked to original sources

[The normalisation of blood sugar using a non-miniaturised artifical pancreas. Application for 24 hours in 7 insulin-dependent diabetics (author's transl)].

Seven insulin-dependent diabetic were treated for 24 to 36 hours by intravenous injections of insulin adapted to variations in blood glucose using a fairly voluminous automatic regulation device. This artificial pancreas consists of a modified Technicon blood sugar apparatus which provides continuous estimation of blood glucose using non-haemolysed whole blood by a glucose oxidase method with an inertia time of 6 minutes, a table calculator and a newly developed interpretation and command electronic unit (GlucostatR). Normalisation of blood glucose was obtained for at least 24 hours, during and between meals, during a period following an oral glucose load and throughout the night.

Artificial Organs↗

Continuous extracorporeal monitoring of animal blood using the glucose electrode.

A continuous extracorporeal monitoring system for blood glucose employing an electrochemical sensor is described. The sensor, about the size of a nickel, is rapid, is specific for glucose, generates its own power, and consists of two galvanic oxygen electrodes. Over one oxygen electrode is affixed a plastic matrix to which glucose oxidase is covalently bound; a blank matrix is over the other, which serves as a reference. Oxygen is consumed in the glucose-oxidase-containing matrix, decreasing the current from the underlying oxygen electrode. The current decrease is nonlinearly proportional to the glucose concentration. The sensor is clamped between small blocks of plastic fitted with inlet and outlet nipples so that blood pumped from the animal passes over the two electrodes and thence to an automated chemical analysis for comparison. Blood is collected and anticoagulant added in a double-lumen catheter. Blood is withdrawn at the rate of 1 cc. per hour. Results obtained by use of the system in rabbits are reported. The capacity of the system to continuously monitor changes in blood glucose produced by repeated glucose tolerances is shown in hypo-, normo-, and hyperglycemic animals. Some properties of the system and its calibration are discussed.

Animals↗

[Sex differences in the blood glucose fall induced by short fasts (author's transl)].

Overnight fasting venous plasma glucose concentration was lower in premenopausal women than in men. This difference increased during a low caloric and low carbohydrate diet and above all after a 48 h fasting period. Venous blood glucose variation during this period of fasting was the same in post-menopausal women as in men. These facts and the previous observation by our group of a fall in fasting and post absorptive venous blood glucose after intramuscular injection of oestradiol benzoate (10) indicate that sex variations in the blood glucose fall following a period of fasting are at least partly linked to the oestrogenic status of the premenopausal woman.

Blood Glucose↗

Study of glucagon secretion using in vitro perifusion of rat pancreas pieces.

The in vitro perifusion technique of rat pancreatic tissue has been studied in respect of sensitivity and reproducibility regarding alpha-2-cell function. Convenient and quickly performed, it allows the kinetic analysis of humoral factors of glucagon release when the blood vessels are too small to be cannulated, for instance in case of fetal pancreas and of tumor tissue. A2 cells in the perifused pancreatic tissue release glucagon in response to arginine, norepinephrine and the decrease of glucose concentration in the medium. The sensitivity of this preparation is lower than that of the perfused pancreas: this may be related to unphysiological conditions of fluid circulation, of the degradation of the stimuli and degradation of the hormone released. Satisfactory conditions of perifusion flow rate and amount of panceatic tissue have been defined and several protective agents have been tested.

Acetylcholine↗

Lack of detectable deleterious effects on metabolic control of daily fructose ingestion for 2 mo in NIDDM patients.

The effects of a daily intake of 30 g fructose on blood glucose regulation, erythrocyte insulin receptors, and lipid metabolism have been studied in type II (non-insulin-dependent) diabetic subjects. Eight well-controlled patients received, in a randomly assigned crossover design over two 2-mo study periods, 30 g of fructose in exchange for an isocaloric amount of starch. Fructose could be taken at any time during the day as part of the 1400-1600 kcal allowed diet (50% carbohydrate, 30% fat, 20% protein). No significant difference was observed concerning body weight, HbA1c, fasting plasma glucose, fasting plasma insulin, uric acid, total cholesterol, high-density lipoprotein cholesterol, and triglycerides, nor was there any change in insulin binding to erythrocytes between the fructose and the control starch period. However, the mean plasma triglyceride levels after the fructose period, although still in the normal range, were significantly higher than baseline values (P less than .05). We conclude that moderate amounts of fructose incorporated into the diet of well-controlled type II diabetic subjects have no significant deleterious effect on glycemic control, insulin receptors of erythrocytes, or lipid metabolism.

Blood Glucose↗

Relative sweetness of fructose compared with sucrose in healthy and diabetic subjects.

Fructose is credited with some advantages over sucrose: it causes less of an increment in plasma glucose and insulin response, and the taste is sweeter. We reevaluated the latter property with a new methodology (the "up and down" method adapted from Dixon) in 33 healthy subjects, 17 insulin-dependent diabetes mellitus (IDDM) patients, and 12 non-insulin-dependent diabetes mellitus (NIDDM) patients. Sweetening potency was determined over 2-3 test sessions in each subject. Results are expressed in percent as the relative sweetness (R) of fructose (F) over sucrose (S), taken as reference. In the first set of experiments, with a 30-g/L sucrose-water solution at pH 7, we found that R values were similar for healthy subjects (102 +/- 8%) and diabetic subjects (106 +/- 7%) (P less than .05). No significant difference between IDDM and NIDDM patients was observed. In a second set of experiments, performed in healthy subjects only, R was increased in acid water (114%; P less than .01), in lemon juice (136%; P less than .001), in water at 2 degrees C (130%; P less than .001), and in coffee at 2 degrees C (120%; P less than .02); mean values were decreased in grapefruit juice (77%; P less than .001), in water at 43 degrees C (88%; P less than .01), and in coffee at 53 degrees C (87%; P less than .001). We found that the test methodology had a very satisfactory intrasubject reproducibility (coefficient of variation [C.V.] less than 8%) but a very wide intersubject variability (C.V. congruent to 32%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Plasma insulin and C-peptide levels during continuous subcutaneous insulin infusion.

A study was performed to estimate the absorption kinetics of insulin infused subcutaneously. Four insulin-dependent diabetic subjects had their insulin pumped through a subcutaneously implanted fine polyethylene catheter at a constant rate of 5.0 +/- 0.3 ml/h but at two different insulin concentrations: 218 mU/ml between meals, and 2400 mU/ml at the start of breakfast, lunch, and dinner (lasting 20, 30, and 30 min, respectively). The amount (40 U/day) and distribution of insulin delivered was identical in the four patients in order to facilitate comparison between the subjects. No attempt was made to normalize their blood glucose during the study period. A study of the kinetics of insulin absorption was made by assaying plasma insulin levels; lack of plasma anti-insulin antibodies was verified; plasma C-peptide levels were measured and were far below values observed in the fed state in nondiabetic patients. The mean maximum insulin level reached after switching from low to high concentration insulin was observed 87 +/- 2 min after breakfast, 117 +/- 22 min after lunch, and 125 +/- 20 min after dinner. Differences observed are not significant. These values are similar to those observed after subcutaneous injection of 40 U/ml Regular insulin as a single bolus. After switching from high to low concentration, plasma insulin levels did not return to their basal values before the third or fourth hour. Subcutaneous insulin infusion could be a safe and easy way of insulin administration in an open-loop system; however, this method does not seem to be suitable for a closed-loop system.

Blood Glucose↗