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Biomedical subjects

K Kraft

Publications and source records attributed to K Kraft.

At least 91 records · Page 5Linked to original sources
PubMed1992

[Advantages of 24-hour ambulatory blood pressure monitoring for the assessment of dose-effect relations and dose-equivalency].

Because of the high variability of blood-pressure, clinical studies using casual measurements require rather large numbers of patients for assessment of pharmacologic efficacy. By the use of blood-pressure monitoring over 24 hours this number can be dramatically reduced. Additional benefits are the precise determination of dose-effect relationships and the more accurate estimate of the response-rate. Comparing two retarded galenic forms of Verapamil we show that even dose-equivalence can be studied with this type of blood-pressure recording.

Blood Pressure↗
PubMed1991

Chronic kappa-opioid receptor antagonism delays the rise in blood pressure in spontaneously hypertensive rats.

A 4-week subcutaneous treatment with the kappa-opioid receptor antagonists, MR 2266 or MR 1452, delayed the age-dependent increase in systolic blood pressure in young spontaneously hypertensive rats (SHR), but not in normotensive rats. The content of beta-endorphin, [Leu5]enkephalin, and catecholamines in various brain tissues was not affected by MR 2266. Specificity of the kappa-opioid receptor antagonism was tested in SHR by injection of the kappa-opioid agonist, MR 2033, and the mu agonist, morphiceptin, after 28 days of MR 1452 or saline and 2 days after the end of treatment. The increase in mean arterial blood pressure (MAP) after MR 2033 did not differ between the two groups at the 28th day of treatment but was higher 2 days later in the previous MR 1452 group, possibly indicating up-regulation of kappa-opioid receptors. Morphiceptin did not alter MAP during or after MR 1452. It is concluded that kappa-opioid receptors may have a tonic influence on the age-dependent increase of blood pressure in SHR but not in normotensive rats.

Adrenal Glands↗
PubMed1991

Inhibition of parathyroid hormone secretion correlates with increased incorporation of 32P into phosphatidylinositol and lysophosphatidylinositol.

We have studied the incorporation of radioactive P (32P) into lipids of bovine parathyroid tissue under conditions of stimulated and inhibited hormone secretion. Utilizing low (0.5 mM) and high (3.0 mM) concentrations of calcium to regulate parathyroid hormone secretion, we initially found that the labeling of the cellular phospholipids with 32P was greater in those tissues incubated in high-calcium medium. Thin-layer chromatography of lipid extracts prepared from tissue incubated in either low- or high-calcium media revealed that the increased incorporation of 32P (high or low) was localized primarily to two phospholipids. To determine whether the increases were due directly to the different calcium concentrations, the experiments were performed in media containing normal calcium concentrations (1.25 mM) and low (0.5) or high (3.0) magnesium concentrations to modulate hormone secretion. The results were identical to those obtained using low and high calcium, indicating that the increased 32P incorporation was not an effect of high calcium but rather correlated with the inhibition of hormone secretion. The use of other secretagogues confirmed this correlation. The identity of the two phospholipids was established, by two-dimensional thin-layer chromatography, to be phosphatidylinositol (PI) and lysophosphatidylinositol (LPI). The correlation of increased 32P incorporation with inhibition of secretion led us next to examine isolated secretory granules from tissues exposed to either high-or low-calcium conditions. Thin-layer chromatography of granule lipid extracts yielded chromatograms containing PI and LPI, and the radioactivity of each was greater in the high-calcium sample than in the low-calcium sample.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Long-term opiate receptor antagonism in a patient with panhypopituitarism: effects on appetite, prolactin and demand for vasopressin.

As endogenous opiates are known to be involved in regulation of appetite, an obese patient with panhypopituitarism and frequent episodes of ravenous hunger was treated with the oral opiate antagonist naltrexone for 13 months. This resulted in loss of body weight and attacks of severe hunger. The increased serum prolactin concentration and the dose of vasopressin required for substitution could be reduced. Long-term application of opiate antagonists may be useful in related cases.

Adult↗
PubMed1991

Influence of chronic opioid delta receptor antagonism on blood pressure development and tissue contents of catecholamines and endogenous opioids in spontaneously hypertensive rats.

Opioid delta receptors seem to be involved in blood pressure regulation of spontaneously hypertensive rats (SHR), possibly by an interaction with the sympathetic nervous system. In the present study the effect of four weeks' chronic delta receptor antagonism with ICI 154 129 on development of blood pressure was evaluated in young SHR. Contents of adrenaline and noradrenaline and the opioid peptides beta-endorphin and leucine-enkephalin were measured in brain stem, mid brain, hypothalamus, and adrenal glands. After four weeks' treatment, systolic blood pressure was lower when compared with control SHR. During chronic delta antagonism, concentrations of adrenaline were higher in hypothalamus, mid brain and adrenal glands, contents of noradrenaline were higher in hypothalamus and adrenal glands than in control rats, contents of opioid peptides were not altered with the exception of an increase of beta-endorphin concentration in the hypothalamus. The changes in concentrations of catecholamines following chronic delta antagonism may reflect an alteration of sympathetic activity and could contribute to the retardation of blood pressure development.

Animals↗
PubMed1991

Short-term dietary sodium restriction increases serum lipids and insulin in salt-sensitive and salt-resistant normotensive adults.

Evidence suggests that dietary salt reduction similar to diuretic therapy may adversely affect lipid and glucose metabolism. We studied 147 non-obese normotensive subjects (60 females and 87 males) aged 19-78 years who entered a single-blind crossover trial and were randomly assigned to a low salt diet of 20 mmol or a high salt diet of 300 mmol sodium per day, for 7 days each. Sodium restriction lowered mean arterial blood pressure (MAP) by a mean of 7.5 mmHg in 17% (salt-sensitive), had no hemodynamic effect in 67% (salt-resistant) and raised MAP by a mean of 6 mmHg in 16% of the subjects (reverse reactors). With dietary salt restriction serum total- and LDL-cholesterol as well as serum insulin and uric acid concentrations increased significantly in all three groups. The largest increases in total (10%) and LDL- (12%) cholesterol occurred in the reverse reactors. Salt-sensitives had significant higher lipoprotein(a) values than the other two groups. Salt-restriction had no significant effect on this parameter. Plasma renin activity, as well as plasma aldosterone and noradrenaline concentrations rose in all three groups during the low salt diet, the largest increases being observed in the reverse reactors. Short-term sodium restriction in normotensive adults has unfavourable effects on lipid and glucose metabolism, especially in subjects who do not derive hemodynamic benefit. Further studies are necessary to examine the effects of more moderate salt reduction for longer periods on the risk factor profile for cardiovascular disease before a low salt diet can be regarded as a safe public health measure for the general population.

Adult↗
PubMed1990

Pseudohypertension in hypertensive patients on multiple drug therapy.

Differences in blood pressure between direct intra-arterial and indirect cuff measurements have been reported, especially in elderly patients. We investigated the incidence of pseudohypertension among hypertensives with a poor response to drug therapy. We studied 24 patients, aged between 18 and 65 years, whose blood pressure could not be normalized with a combination of at least two antihypertensive drugs. We found no difference in systolic blood pressure but diastolic blood pressure was significantly (P less than 0.001) lower when measured intra-arterially. The mean difference between the direct and the indirect blood pressure determination was 16.2 +/- 1.5 mmHg (s.e.m.), and the range was 2.3-39.6 mmHg. Age, duration of hypertension and left ventricular hypertrophy was not correlated with the incidence and extent of pseudohypertension. We conclude that in hypertensives with a poor response to drug therapy, blood pressure measurements should be taken intra-arterially in order to avoid the hazards of overtreatment.

Adolescent↗
PubMed1989

[Diagnosis of very early arteriosclerosis vascular changes using Duplex sonography].

The technical evolution of ultrasonic equipment provides a high resolution imaging analysis of the vessel wall and thereby offers new possibilities in diagnosing very early atherosclerotic changes. The typical B-mode image in human and animal arteries shows parallel wall contures enclosing a hypoechoic space. In this study in Vitro- and in Vivo-experiments in rabbit aortas document the distance between these contures correlating histologically with a high cholesterol diet caused a broadening of the hypoechoic space in the rabbit aortic vessel wall. The data demonstrate that high resolution Duplex Sonography is a usefull noninvasive approach for the detection of very early atherosclerotic changes in arterial vessel walls in a stage before plaques can be identified.

Animals↗
PubMed1989

[Adynamia, finger paresthesias].

A 40-year-old woman was admitted for investigation of weakness and angina pectoris. She had generalised weakness of muscles, cold intolerance and a reduced physical performance. A previous neurological examination had already revealed a carpal-tunnel syndrome of the right hand. This syndrome, combined with a rough, cool skin and a periorbital edema, lead to the assumption of hypothyroidism. The diagnosis was confirmed by a combination of very high concentrations of TSH and decreased concentrations of the thyroid hormones. Replacement therapy by oral administration of L-thyroxin resulted in a gradual improvement of the patient's state.

Adult↗
PubMed1989

Altered plasma leucine-enkephalin concentrations in patients with established hypertension may be involved in impaired regulation of blood pressure.

Leucine-enkephalin is known to modulate cardiovascular activity. In the present study we determined plasma leucine-enkephalin and noradrenaline concentrations in young men with essential hypertension and in normotensives at rest and after bicycle exercise. The essential hypertensive patients had a lower concentration level of resting leucine-enkephalin than the normotensives. Exercise increased leucine-enkephalin in both groups. Noradrenaline was significantly higher in the essential hypertensives than in the normotensives. The central alpha 2-agonist clonidine reduced leucine-enkephalin at rest in the normotensives and prevented its increase during exercise, but had no effect on leucine-enkephalin in the essential hypertensives. These results may reflect an altered interaction between leucine-enkephalin and noradrenaline in essential hypertensives compared to normotensives, possibly contributing to hypertension.

Adult↗
PubMed1987

Normalization of blood pressure and plasma concentrations of beta-endorphin and leucine-enkephalin in patients with primary hypertension after treatment with clonidine.

Opioid peptides are thought to be involved in blood pressure regulation, possibly via an interaction with the sympathetic nervous system (CNS). To further elucidate this hypothesis the plasma concentrations of beta-endorphin, leucine-enkephalin and noradrenaline were determined overnight (9 p.m. to 8 a.m.) in young patients with mild essential hypertension and then compared to normotensive controls. The mean concentrations of beta-endorphin during the early night (9 p.m. to 2 a.m.) and leucine-enkephalin were lower (p less than 0.05, p less than 0.01, respectively) than in the normotensive subjects, but the noradrenaline concentration was higher. After 14 days of treatment with clonidine, which decreases sympathetic activity via a central action, beta-endorphin, leucine-enkephalin, and noradrenaline concentrations did not differ between both groups. It is concluded that the lower plasma concentrations of beta-endorphin and leucine-enkephalin in the hypertensive group could reflect reduced opioidergic activity in the CNS and in the peripheral sympathetic neurons and also could be involved in the increased sympathetic activity of these patients. Besides via sympathetic inhibition, clonidine also may reduce the increased blood pressure further by normalizing central beta-endorphin release.

Adult↗
PubMed1987

The effects of orchidectomy and testosterone replacement therapy on plasma and brain oxytocin in normal rats.

In male rats, two-week orchidectomy induced a significant increase in the pituitary content of oxytocin-immunoreactivity and a significant fall in its hypothalamic concentration, without detectable changes in plasma. Testosterone replacement therapy in castrated animals abolished the stimulant effect of orchidectomy on pituitary accumulation of oxytocin. The present study demonstrates an inhibitory effect of testicular androgens on oxytocin release. These results and previous observations suggest that the neurohypophysial hormone oxytocin may play a role in male reproductive system.

Animals↗