Annals of clinical research最新文献

The mechanisms by which sulphonylureas lower blood glucose are complex. Sulphonylureas increase insulin secretion and possibly also decrease glucagon release from the pancreas. In the periphery, they increase insulin binding to its receptors through direct or indirect mechanisms, primarily by increasing receptor number. Sulphonylureas also potentiate the action of insulin in peripheral glucose uptake and metabolism, even when no measurable effects on insulin receptors can be demonstrated. This post-receptor mode of action seems to play an important role in the spectrum of sulphonylurea effects.

Twelve moderately obese middle-aged male out-patients with untreated mild hypertension reduced their sodium intake by about 120 mmol/day during 4-6 weeks. The low sodium diet period was followed by a period of energy reduction as well as sodium restriction for 15 weeks. Mean body mass was then reduced by 7.5 +/- 1.0 kg. Intraerythrocyte sodium (IeNa), sodium influx (Na-influx) and sodium efflux rate constant (Na-efflux rate), were measured before intervention, during salt restriction and during salt and energy restriction. Plasma renin activity (PRA) and urinary excretion of aldosterone (U-Aldo) and noradrenaline (U-NA) were also determined during the three observation periods. During sodium restriction there was a significant increase in PRA and U-Aldo, but no change was seen in IeNa, Na-influx or Na-efflux rate constant. During sodium restriction there was a significant positive correlation between PRA and both Na-influx and Na-efflux rate constant. When energy reduction was combined with sodium restriction, PRA and U-NA both diminished significantly. Na-influx and Na-efflux rate also exhibited a significant decrease while IeNa did not change. Sodium restriction caused a significant fall in mean arterial blood pressure and a tendency to a further decrease was seen when energy intake was also reduced. No significant correlation could be found between the fall in blood pressure and changes in cellular sodium transport. These data indicate that the renin-angiotensin-aldosterone system and sympathetic activity influence the regulation of erythrocyte sodium turnover during sodium and energy restriction in obese hypertensive men.

With aging, several functions related to the locomotor system will deteriorate. Still, there is a rather well-maintained adaptability for increasing physical activity and for training in the elderly with respect to strength as well as endurance. Part of the observed reduction in muscle function with age could therefore be caused by inactivity. Evidently, however, there is a reduction in muscle mass with age due to loss of motor units. Muscle strength and aerobic power will fall fairly proportionally to the reduction in muscle mass. The muscle changes are, at least up to around the age of 70, more quantitative than qualitative. There is a reduction in the size of the fast-twitch (type II) fibers in the quadriceps, but not in other muscles such as the biceps brachii, presumably due to differences in activity pattern and motor unit recruitment. Aging per se may not reduce oxidative enzymatic capacity in the skeletal muscle. There is maintained potential for increase with endurance training. Thus, as an extreme example in very well trained elderly endurance athletes, high activity of citrate synthase is found and, in connection with that, also low plasma insulin values at baseline as well as after glucose intake. Limitations to aerobic capacity besides the reduced muscle mass are mainly located in the central circulatory and respiratory systems. Comparing the oxygen cost of activities in daily living, such as walking, and the aerobic power of the elderly, suggestions will be given on the choice of training activities.

In order to evaluate if left ventricular structural changes are present in young subjects with increased risk of developing essential hypertension, we have investigated young normotensive and borderline hypertensives with and without hypertensive parents. Our results showed, that left ventricular hypertrophy (LVH) was found in these risk subjects and that LVH was associated to borderline hypertension.

The antihypertensive effect of verapamil administered either two or three times daily was compared in a double blind, cross over study in 15 patients with mild to moderate essential hypertension. During the dose titration period with t.i.d. administration, normotension was obtained with daily doses of 240 mg in 7 patients, 360 mg in 7 patients and with 480 mg in one patient. Systolic and diastolic blood pressures (BP) in the supine (13/14 mmHg) and standing (14/14 mmHg) positions were significantly (p less than 0.001) reduced during the dose titration period. There was no statistically significant difference in the BP values between the twice and three times a day regimens. Five to 7-fold individual variations in the serum verapamil concentrations between individuals were observed. No significant correlations were found between serum drug concentrations and the change in mean arterial BP. There was no significant difference in the incidence of side effects between the two treatment regimens. Our results suggest that verapamil administered twice daily is effective in mild to moderate hypertension.

Among the 5 main motor functions of coordination, flexibility, strength, velocity, and endurance, mainly the last one is of essential preventive cardiological significance. There are peripheral and central metabolic and haemodynamic adaptations which can reduce the oxygen demand of the heart muscle. The flow properties of the blood are improved combined with an antithrombotic effect. Endurance training induces alterations in the lipoprotein metabolism which could be useful for protection against arteriosclerosis. Effects of training on some hormones are described in connection with silent heart ischaemia. The listed protective results of endurance training are the sum of all possibilities of training related to different sports events, exercise intensities and duration. A recommendation is given for a minimum training program based on practical experience.

We assessed a highly sensitive immunoradiometric thyrotropin (TSH) assay in screening thyroid dysfunction in 130 consecutive outpatients from a department of medicine and 224 patients from a municipal health centre. In addition to clinical examination, three routine tests were done: a thyroxine radioimmunoassay, an analogue-based free thyroxine assay and an immunoradiometric TSH assay. Triiodothyronine and the TRH test were done, if the findings were discrepant. Discrepancy existed in 24% of cases. The TSH assay had no false negative results (sensitivity 100%). Therefore TSH could screen all patients with thyroid dysfunction. Free thyroxine was the most specific assay (specificity 96%), but many subclinically or overtly hypothyroid patients would have been missed, if that assay had been used alone. We conclude that TSH(IRMA) is the best first-line measurement for thyroid dysfunction testing among outpatients. An abnormal TSH result alone is not diagnostic, but should be followed by the measurement of thyroxine or free thyroxine.

Sixteen healthy young volunteers were studied with echocardiography and systolic time intervals at rest and after three minutes' isometric exercise before and during autonomic blockade with atropine and propranolol. Isometric exercise increased cardiac output by raising the heart rate from 64 +/- 3 to 72 +/- 4 bpm (SEM) (p less than 0.01). Mean blood pressure increased from 86 +/- 2 to 104 +/- 3 mmHg (p less than 0.001) without any changes in the calculated total peripheral vascular resistance. Afterload (left ventricular systolic wall stress) rose but preload (left ventricular end-diastolic diameter, LVEDD) did not change. There was no variation in fractional shortening, maximal velocity of circumfertial fibre shortening (VCFmax) or pre-ejection period (PEP) despite increased afterload. This indicates stimulated intropy during isometric exercise. Autonomic blockade enhanced cardiac output by increasing heart rate from 64 +/- 3 to 97 +/- 2 bpm (p less than 0.001). Mean blood pressure rose from 86 +/- 2 to 93 +/- 2 mmHg (p less than 0.01) while vascular resistance fell. Afterload did not change but LVEDD shortened form 45.5 +/- 0.9 to 43.5 +/- 0.9 mm (p less than 0.001). Preload-independent VCFmax did not increase despite raised heart rate. PEP rose from 99 +/- 4 to 107 +/- 3 ms (p less than 0.01) and fractional shortening fell from 29 +/- 1 to 25 +/- 1% (p less than 0.001); these changes were greater than expected from the reduced preload. Consequently autonomic blockade seems to impair myocardial contractility despite vagal dominance at rest. Heart rate and cardiac output were not influenced by isometric exercise during autonomic blockade.(ABSTRACT TRUNCATED AT 250 WORDS)

Sauna bathing does not appear to affect fertility in men. Nor is the sauna teratogenic. The haemodynamic changes brought about by the sauna are similar in non-pregnant and pregnant women, regardless of the duration of pregnancy. There are, however, differences in the hormonal responses. Pregnant women adapt well to the thermal stress of the sauna, which is also true of the fetus, provided that it is healthy. Although the fetal heart rate rises during maternal hyperthermia, cardiotocographic tracings remain normal during and after maternal thermal stress. Healthy pregnant women may safely have sauna baths throughout their pregnancy.