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Biomedical subjects

C Kellner

Publications and source records attributed to C Kellner.

26 records · Page 2Linked to original sources
PubMed1986

Effective hydraulic permeability of the glomerular capillary wall in rats after uninephrectomy.

The effective hydraulic permeability (k) of glomerular capillaries was studied in 2-month-old Wistar rats 4 weeks after uninephrectomy in comparison to age-matched control rats. Isolated kidneys were perfused with a cell-free solution containing 5% albumin. In this preparation the rise of colloid osmotic pressure along the glomerular capillaries can be neglected because the filtration fraction is low (3%) due to high perfusion rates at normal filtration rates. Single nephron filtration rates (SNGFR) and effective filtration pressures were estimated by micropuncture to calculate the ultrafiltration coefficient (Kf). Glomerular capillary surface area was measured morphometrically to obtain k (k = Kf/S). We found that the effective hydraulic permeability in uninephrectomized rats was higher than in rats of comparable age (26.0 vs 18.0 nl/mm Hg X s X cm2). This can contribute to the adaptive rise in SNGFR after uninephrectomy.

Animals↗
PubMed1985

Successful treatment of Cushing's syndrome with the glucocorticoid antagonist RU 486.

A patient with Cushing's syndrome due to ectopic ACTH secretion was treated successfully with the new glucocorticoid antagonist RU 486 [17 beta-hydroxy-11 beta-(4-dimethylamino phenyl) 17 alpha-(1-propynyl)estra-4,9-dien-3-one]. This compound is a 19-nor steroid with substitutions at positions C11 and C17 which antagonizes cortisol action competitively at the receptor level. Oral RU 486 was given in increasing doses of 5, 10, 15, and 20 mg/kg . day for a 9-week period. Treatment efficacy was monitored by assessment of clinical status and by measuring several glucocorticoid-sensitive variables, including fasting blood sugar, blood sugar 120 min after oral glucose administration, and plasma concentrations of TSH, corticosteroid-binding globulin, LH, testosterone-estradiol-binding globulin, and total and free testosterone. With therapy, the somatic features of Cushing's syndrome (buffalo hump, central obesity, and moon facies) ameliorated, mean arterial blood pressure normalized, suicidal depression resolved, and libido returned. All biochemical glucocorticoid-sensitive parameters normalized. No side-effects of drug toxicity were observed. We conclude that RU 486 may provide a safe, well tolerated, and effective medical treatment for hypercortisolism.

Adrenocorticotropic Hormone↗
PubMed1984

Effects of active and passive wall stress changes on the rhythmic mechanical activity of the pressurized rat tail artery.

Rhythmic mechanical activity was recorded in vitro in isolated rat tail arteries. Pressurized cylindrical segments of this artery, stretched to their in situ length, exhibit well-synchronized rhythmic contractions. Frequency and amplitude of the rhythmic activity can be modified by (1) passive stretch at a given constrictor agonist concentration, as well as by (2) active wall stress changes induced by varying doses of constrictor agonists. At a norepinephrine concentration of 0.5 microM, the frequency (f) of rhythmic contractions increases from 0.2 to 0.65 [sec-1], when the mean circumferential wall stress (sigma) is increased from 1 . 10(5) to 1 . 10(6) dyn/cm2. The relationship between f and sigma is, at a constant smooth muscle tone, virtually independent of the rate and also of the direction of the applied stress changes. Changes of the smooth muscle tone (i.e. changes of the actively developed wall stress), induced by vasoactive agents or other stimuli, lead to virtually parallel shifts of the sigma-f relationship, which is obtained by passive stretching. It is concluded that the actual stimulus for the stretch-sensing structure in the arterial smooth muscle is the change in wall stress rather than the change in strain. Since rhythmic contractions may still be observed 30-60 min after withdrawal of Ca++ from the bath solution, extracellular Ca++ seems not to be primarily involved in this rhythmicity.

Animals↗
PubMed1984

Psychiatric implications of basic and clinical studies with corticotropin-releasing factor.

Corticotropin-releasing factor (CRF) is a newly sequenced neuropeptide thought to be a principal stimulus to pituitary corticotropin (ACTH) secretion. Evidence obtained from laboratory animals and primates is reviewed which indicates that CRF not only stimulates the pituitary-adrenal axis but also influences several aspects of CNS function which may be of relevance to psychiatric illness. Clinically, experience in administering ovine CRF to more than 150 individuals shows that CRF can be helpful in resolving differential diagnostic dilemmas in patients with various disorders of the hypothalamic-pituitary-adrenal axis and in furthering an understanding of the pathophysiology of conditions such as Cushing's disease and depression.

Adrenocorticotropic Hormone↗
PubMed1984

Selective response to the anticonvulsant carbamazepine in manic-depressive illness: a case study.

Acute and prophylactic effects of carbamazepine are documented in a double-blind clinical trial in a 55-year-old treatment-refractory, lithium-non-responsive, manic-depressive patient. Double-blind crossover to two other anticonvulsants was also achieved; the patient showed no evidence of response to phenytoin or valproic acid. The clinical and theoretical issues raised by the selective response to carbamazepine in this patient are discussed.

Bipolar Disorder↗
PubMed1983

Endothelial cells are involved in the vasodilatory response to hypoxia.

The role of endothelial cells in the dilatory response of arteries to hypoxia was studied in vitro using perfused arterial segments of rat and dog. The pO2 of the intra- and extraluminal perfusate could be varied separately. Intraluminal hypoxia (pO2 of 40 mmHg) induced a dilation irrespective of extraluminal pO2 level. On the contrary extraluminal hypoxia could not elicit a dilation during intraluminal normoxic perfusion. Dilation during extraluminal hypoxia could only be induced if the segment was not intraluminally perfused. The dilatory response to intraluminal hypoxia was abolished after enzymatical or mechanical removal of the endothelium. While theophylline and lipoxygenase inhibitors did not influence this endothelium-induced dilation, a significant reduction of the response could be observed after incubation with indomethacin. These results support the concept that prostacyclin (PGI2) might be involved in the hypoxic endothelium-induced dilation.

Acetylcholine↗