Transcutaneous oxymetry measurements during acute blood loss

Transcutaneous PO2 (TcPO2) was measured in healthy adult blood donors to test the sensitivity of this method as a noninvasive means of diagnosing occult blood loss. TcPO2, the energy required to heat the electrode (MW), and postural changes in blood pressure and pulse, were measured before and after a 450-ml blood donation. There was a significant increase (P less than .005) in postural pulse of 4.8/min, but no significant change (P greater than .05) in postural blood pressure. There was no significant change (P greater than .05) in TcPO2, but there was a significant decrease (P less than .001) in MW. These MW changes probably reflect physiologic changes associated with blood loss.

Alterations in aldosterone biosynthesis in essential hypertensives

We studied hypertensives with decreased adrenal responsiveness to infused angiotensin II (AII) to assess their responsiveness to other aldosterone secretagogues, ACTH and potassium, which are thought to stimulate aldosterone synthesis in sites different from one another and from AII. All subjects, following sodium restriction, received an infusion of AII in increasing doses (0.1-3 ng/kg per min). The increment in aldosterone between control and the highest infusion dose divided by the increment in plasma AII was used as the index of adrenal responsiveness. All normotensive controls (NC) had a ratio greater than 0.5. Hypertensives with a normal ratio were designated normal responders (NR) and those with a lower ratio were abnormal responders (AbR). The slope of the regression line between aldosterone and AII was significantly less for the AbR (0.02 +/- 0.04) than for the NR (1.20 +/- 0.02, P less than 0.001) and the NC (1.00 +/- 0.03, P less than 0.001) groups. During infusion of cosyntropin in increasing doses (0.05-1.5 mIU/kg per 30 min), the aldosterone response of the AbR was significantly less than that of the NR (P less than 0.016) or the NC (P less than 0.05) groups. Similarly, after infusion of potassium (0.33 mEq/min), the increment in aldosterone in the AbR group (7.6 +/- 2.2 ng/dl) was significantly less than that in the NR (14.2 +/- 2.5 ng/dl, P less than 0.05) and the NC (18 +/- 5 ng/dl, P less than 0.05) groups. Thus hypertensives with decreased aldosterone responsiveness to infused AII also had decreased responsiveness to infused ACTH and potassium, suggesting that their defect lies in the intracellular aldosterone biosynthetic pathway.

Contribution of prostaglandins to the antihypertensive action of captopril in essential hypertension

To determine whether prostaglandins contribute to the depressor response to the converting enzyme inhibitor, captopril, we measured the plasma prostaglandin levels by radioimmunoassy before and after captopril administration, and then examined the effect of prostaglandin synthetase inhibition on captopril's antihypertensive effect. When a single oral captopril dose (25-100 mg) was given to 31 sodium-restricted patients with essential hypertension, the levels of the stable transformation product of prostacyclin remained unmeasurable and that of thromboxane A2 did not change, while the metabolite of PGE2 (PGE-M) increased by 53% (34 +/- 4pg/ml pre-captopril, 52 +/- 5 pg/ml after; p less than 0.001). As expected, blood pressure (BP) and angiotension II (AII levels fell, and kinin levels rose (all changes p less than 0.001). We then blocked prostaglandin synthesis in 18 of these subjects for 24 hours with either indomethacin (n = 10) or aspirin (n = 8) before repeating the captopril dose, to assess the importance of these PGE-M increments. The PGE-M responses to captopril were effectively blocked in nine of 10 subjects receiving indomethacin and four of eight receiving aspirin. In these 13 patients, the depressor response to captopril was significantly blunted (-20 +/- 3mm Hg pre-synthetase inhibition vs - 13 +/- 2 mm Hg post; p less than 0.05). When these agents did not block the PGE-M response to captopril, the BP response was also unchanged (-15 +/- 4mm Hg pre, -18 +/- 5mm Hg post). Neither indomethacin nor aspirin changed the AII or kinin responses to captopril. We conclude that the prostaglandins may be important mediators of captopril's antihypertensive effect in the sodium-restricted state.

Diabetic retinopathy: update on therapeutic advances

It is clear that real advances have occurred in the therapy of diabetic retinopathy. However, this complication of diabetes can and does lead to blindness in the older patient. The present treatment modalities offer a means of maintaining or, in some patients, improving the visual performance of the patient. Laser photocoagulation and vitrectomy are the major new therapies. The future will hopefully give us a better understanding of the cause of diabetic retinopathy so that it may be prevented and cured. However, in the interim, all patients with diabetes mellitus should be urged to see on ophthalmologist yearly in order to obtain the best available therapy.

Effects of long term sulfonylurea therapy on plasma insulin and fasting lipid levels

Insulin secretion was studied before and after the control of hyperglycemia in fourteen maturity onset male non-obese diabetics. Optimum control of hyperglycemia was achieved by the addition of the sulfonylurea chlorpropamide to dietary treatment. One patient was a primary treatment failure, but nine out of thirteen had excellent control of hyperglycemia. A standardized oral glucose tolerance test (GTT) was performed before and after eight months of individualized therapy with the sulfonylurea. The GTT was repeated with each patient taking his usual dose of chlorpropamide 90 min prior to the administrationo f the glucose load. In the baseline test glucose levels rose from 135.6 +/- 9.9 mg/dl to a peak level of 268.8 +/- 17.7 mg/dl at 120 min. After control of hyperglycemia glucose levels were significantly lower at 0, 30 and 60 min, and rose from 106.8 +/- 8.5 mg/dl to a maximum of 224.5 +/- 17.3 mg/dl at 120 min. Plasma insulin response was unchanged. Fasting serum cholesterol, triglyceride and total lipid levels changed only minimally during therapy. It is concluded that lowered serum glucose levels after long term treatment with chlorpropamide occured while plasma insulin response to glucose was no greater than before treatment. These findings may be explained by an extrapancreatic effect of the drug or by an indirect result of chlorpropamide induced insulin release which occured earlier in the course of therapy.

Hyperosmolar nonketotic coma in the elderly diabetic

The gravity of this syndrome of severe diabetic stupor without ketosis may not be recognized because patients are usually middle-aged or elderly with mild diabetes. A lack of urgency in treating these patients is probably the cause of the widely reported mortality of 40 to 70 per cent.

Absence of sleep-related growth hormone elevations in myotonic dystrophy

There is evidence that in myotonic dystrophy, the endocrine and central nervous systems are affected. To study a possible relationship between both defects, we investigated nocturnal sleep patterns and associated growth hormone secretion in two men and three women with myotonic dystrophy. In three patients who were clinically the most severely affected by myotonic dystrophy, plasma growth hormone elevations related to the slow-wave phase of sleep were absent. The two least severely affected patients had plasma growth hormone increases of low magnitude and brief duration (from 0.4 ng per milliliter to 13.0 ng per milliliter). These data suggest a failure of integration at a subcortical level of the slow-wave phase of sleep with the hypothalamic-pituitary mechanisms of growth hormone secretion. Thalamic neuronal lesions occurring in myotonic dystrophy could be responsible for such failure.

Abnormal glucose tolerance and arginine tolerance tests in Huntington's disease

Neuropathological studies of Huntington's disease reveal neuronal atrophy, lipofuscin accumulation and other findings characteristic of the aged brain, although the onset of disease is only the fourth decade. The pathology is limited to specific areas such as the caudate nucleus, cerebral cortex and hypothalamus. 14 patients with documented Huntington's disease (mean age of 44.4 years with a range of 27-79 years) were studied by oral glucose tolerance tests (GTT) and intravenous arginine tolerance tests performed under standardized metabolic conditions. Seven of the 14 patients had impaired carbohydrate tolerance. Mean plasma glucose level at 2h was 90.4+/-6.2 mg/100 ml in the patients with a normal GTT and 148.1+/-8.9 mg/100 ml in the patients with a diabetic type GTT. Mean peak insulin level in the nondiabetic group occurred at 1/2 h and was 60.2+/-10.1 muU/ml, but in the diabetic group the peak insulin level occurred at 2h and was 155.9+/-33.8 mgU/ml. There was failure of suppression of growth hormone during the GTT, with a rise to abnormally high levels at 5h (18.6+/-5.6 ng/ml). Arginine infusion resulted in normal glucose and insulin rise in the nondiabetic patients with Huntington's disease. However, arginine infusion provoked an elevated insulin response in those with a diabetic GTT, and an exaggerated growth hormone response in the majority of the patients. It is uncertain whether these observations are related to abnormal cerebral aging per se, direct hypothalamic neuronal degeneration, or perhaps a relative imbalance of intracerebral neurotransmitters including dopamine.

Improvement of growth hormone response to stimulation in primary aldosteronism with correction of potassium deficiency

Potassium depletion frequently occurs in primary aldosteronism and has been implicated as the cause of the impaired carbohydrate tolerance frequently associated with this syndrome. Glucose, insulin, and growth hormone regulation were studied in a 42-yr-old, male patient with an aldosterone-secreting adenoma when the patient was potassium-depleted and again after potassium repletion. Potassium repletion was documented by serial body potassium measurements, with an increase in body potassium from 2400 mEq to 2850 mEq after 400 mg spironolactone and 80 mEq supplemental potassium chloride were administered daily for 7 days. Potassium repletion resulted in improvement of the patient's glucose tolerance test, with a decrease in the peak glucose level from 184 mg/100ml to 130 mg/100ml and an increase in the peak insulin level from 46 muU/ml to 85 muU/ml. Intravenous administration of arginine resulted in a subnormal insulin response of 28 muU/ml in the base-line test and an increase to 59 muU/ml after potassium stores were repleted. Growth hormone response to arginine infusion was also initially minimal at 12.5 ng/ml, increasing markedly to 26 ng/ml after potassium replenishment. Insulin-induced hypoglycemia resulted in a depressed growth hormone response of 8 ng/ml when the patient was potassium-deficient, but a normal response of 30 ng/ml after potassium repletion. These observations demonstrate that impairment of both insulin and growth hormone responses to stimulation occur in primary aldosteronism with potassium depletion. These abnormalities may be reversed by potassium repletion.

Age, smoking inhalation, and pulmonary function

This study examined the relative effects of age and smoking on pulmonary function. Smoking was measured by six smoking variables, taken singly and as a composite. Subjects were 1,516 male participants in the Normative Aging Study. A stepwise multiple regression with vital capacity (VC) and forced expiratory volume at one second (FEV1.0) as the criteria accounted for 24.4% and 28.3% of the variance, respectively. Two-way analyses of variance showed that the age decline in pulmonary function was substantially greater for high inhalers than it was for low inhalers or nonsmokers. Age and the inhalation index were also noticeably and independently related to a decline in pulmonary function.

Exaggerated growth hormone response to arginine infusion in Huntington's disease

Growth hormone regulation was studied in 10 patients with Huntington's disease after intravenous administration of arginine. In 20 control subjects arginine infusion resulted in a rise of plasma growth hormone levels from a mean baseline value of 3.2+/-0.6 ng/ml to a peak level of 17.6+/-2.7 ng/ml at 60 min. Growth hormone rise in the majority of patients with Huntington's disease was clearly intact and significantly greater than normal in magnitude, increasing from the baseline level of 2.6+/-0.5 ng/ml to a peak level of 28.3+/-3.7 ng/ml at 60 min (P = less than 0.05). Carbohydrate tolerance of these patients was previously examined, and 4 with normal glucose tolerance and normal insulin responses to arginine infusion had growth hormone levels significantly higher than controls at 30 min. Six patients with impaired carbohydrate tolerance and exaggerated insulin responses to arginine had significantly higher growth hormone responses at 30 min and also at 60 min. Neuronal degeneration of several hypothalamic nuclei has been reported in Huntington's disease. The observations that growth hormone responds in an exaggerated fashion to stimulation by arginine infusion or falling glucose levels as previously described may be explained by intrahypothalamic dysfunction such as impairment of somatostatin secretion.