Counterregulatory response to insulin-induced hypoglycemia in trained and nontrained humans.

The aim of the present series of experiments was to investigate the hormonal counterregulatory response to insulin-induced hypoglycemia in trained and nontrained healthy individuals. Five endurance athletes and six controls were administered intravenous insulin infusion at a rate of 0.15 U/kg/h until plasma glucose reached 50 mg/dL. The mean duration of the infusion in the trained and nontrained subjects corresponded to 18.6 and 26.3 minutes (P less than .01), suggesting that the former were characterized by an increased insulin sensitivity. Plasma glucose levels were similar in the two groups at the end of the insulin infusion, as well as during the postinfusion recovery period. Forty-five minutes after the end of the infusion, plasma glucose levels were not significantly different from the preinfusion levels in the two groups. During this period of glycemia recovery, the increases in plasma glucagon, epinephrine, norepinephrine, and growth hormone were at least 50% lower in the trained than in the nontrained subjects. The increase in heart rate and oxygen uptake during the same period of time was significantly higher in the trained subjects. To determine whether this reduced hormonal response to hypoglycemia was due to reduced insulin levels or to an increased sensitivity to counterregulatory hormones, we investigated the effect of epinephrine on plasma glucose in two other groups of trained and nontrained subjects. In response to a constant epinephrine infusion of 0.01 or 0.1 micrograms/kg fat-free mass (FFM)/min, plasma glucose levels increased similarly in the two groups. In conclusion, these results indicate that trained subjects are characterized by a normal recovery from hypoglycemia despite a reduced response of counterregulatory factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Altered plasma free carnitine response to exercise in type 1 diabetic subjects.

The plasma carnitine response to prolonged exercise in 12 postprandial insulin-dependent diabetics was compared with that of eight normal controls. The diabetics reduced their morning dose of intermediate acting insulin and regular insulin to two-thirds and one-half, respectively. Insulin was injected subcutaneously into the abdominal wall. Exercise was performed on a treadmill for 90 min at 60% VO2 max. Respiratory exchange ratios (RER) decreased significantly (p less than 0.0001) during exercise in both the control and diabetic group. However, RER values were higher (p less than 0.05) in the diabetic group during most of the exercise period, corresponding to a significantly (p less than 0.05) lower proportion of the energy utilized from the oxidation of fat. In the diabetic group, mean plasma glucose at rest was 278 +/- 26 mg/dl, and decreased significantly (p less than 0.01) to 107 +/- 12 mg/dl after 90 min of exercise. In the control group, mean resting plasma glucose was 78 +/- 6 mg/dl, and dropped (p less than 0.05) to 67 +/- 3 mg/dl at 30 min of exercise. Thereafter, it showed no change. Mean resting plasma free insulin in the control group was lower compared to the diabetic group (10.2 +/- 2.0 vs 23.5 +/- 2.0 microU/ml, p less than 0.001). During exercise, insulin levels decreased significantly (p less than 0.01) in the control group while there was no change in the diabetic group. In both control and diabetic groups, percent basal total carnitine increased significantly (p less than 0.01) throughout exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

[Somatostatinomas]. / Les somatostatinomes.

Somatostatinomas are endocrine tumors which prevailing secretion is somatostatin. They are localized in the pancreas and digestive tract or not often in tissues unusually secreting somatostatin, as bronchi. Forty three cases have been described until now. The endocrine syndrome, not very spécific and inconstant, is the result of the somatostatin hypersecretion. Diabetes mellitus, cholelithiasis, pancreatic exocrine insufficiency, gastric hypochlorhydria and anemia are the main symptoms of pancreatic somatostatinoma. On the other hand, they are not found in digestive tumors. Somatostatinomas often secrete other hormonal peptides which may change the clinical manifestations. Radioimmunoassay of plasma somatostatin (basal level and/or after stimulation by tolbutamid) is a more successful diagnostic test; but only immunocytochemistry of the tumor can proved the diagnosis. They a bad prognosis but are not a contra-indication to make a curative treatment; surgical resection and chemotherapy by streptozotocin and 5 FU are the two treatments.

[Endocrine pancreatic tumor secreting somatostatin and somatocrinin]. / Tumeur pancréatique endocrine sécrétant de la somatostatine et de la somatocrinine.

A case of endocrine pancreatic tumour secreting the 2 antagonistic peptides that regulate growth hormone, somatostatin and somatocrinin, is reported. Such tumours are extremely rare and only one other case has been published so far, although pancreatic malignant tumours frequently secrete several hormones. In our patient, the association of diabetes with steatorrhoea, hypochlorhydria, anaemia and biliary lithiasis suggested hypersecretion of somatostatin. Acromegaly, suggested by clinical signs, was confirmed by an excess of growth hormone and somatomedin, and pre-operative somatrocrinin assay confirmed its extra-pituitary origin. Finally, the presence of hyperparathyroidism due to parathyroid gland hyperplasia and of a Recklinghausen disease constituted a multiple endocrine neoplasia syndrome. The significance and implications of this double secretion in vivo are discussed.

[Plasma exchange and hyperthyroidism. Current indications]. / Epurations plasmatiques et hyperthyroïdies. Indications actuelles.

Serious thyrotoxicosis must be treated quickly and efficiently. Plasma exchange (PE) takes place when ordinary treatment is not suitable in emergency cases. Several methods of plasma clearing have already been practiced successfully. PE is the best one. It quickly removes a great amount of thyroid hormones and occasionally pathological immunoglobulins. Risks have not to be underestimated. The most serious accidents are particularly linked with the substitution fluids. Hemoperfusion, peritoneal dialysis, transfusion exchanges can be used too. Thyrotoxicosis crisis, as far as life prognosis is concerned, is an appropriate indication of PE, either as a first line treatment or after the classical treatment has failed. Serious hyperthyroidism due to iodine overload is not improved with common treatment. In this case PE might be worthwhile. In malignant exophthalmia, unimproved with an usual treatment PE can be successfully used, every time ocular prognosis is concerned.

[Acute anuric hemolysis caused by antiajmaline antibodies]. / Hémolyse aiguë anurique par anticorps anti-ajmaline.

In a 32-year old woman under ajmaline therapy for cardiac arrhythmia, a sudden episode of acute haemolytic anaemia and renal failure led to the identification of a potent agglutinating, haemolysing and lymphocytotoxic antibody specific to ajmaline and cross-reacting with quinine and quinidine. The immunological features of the antibody and the pathophysiological mechanism of blood cell destruction are presented, together with a brief synopsis of drugs incriminated so far in the induction of specific antibody formation and immune haemolytic anaemia.