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Biomedical subjects

J Kolanowski

Publications and source records attributed to J Kolanowski.

At least 55 records · Page 3Linked to original sources
PubMed1983

The stimulatory effect of corticotropin on cortisol biosynthetic pathway in guinea-pig adrenocortical cells.

The mechanism of the prolonged stimulatory effect of corticotropin (ACTH) on adrenocortical synthesis of cortisol was studied in guinea-pig adrenocortical cells harvested from control animals and from guinea-pigs submitted 24 h before the sacrifice to a prolonged ether anesthesia in an attempt to induce a release of endogenous ACTH. As a result of this in vivo exposure to endogenous ACTH, the maximal capacity to produce glucocorticoids (by 1 X 10(5) cells incubated during 2 h) in response to ACTH increased from 579 +/- 111 ng (control group) to 915 +/- 143 ng for cells from treated animals, whereas the apparent affinity of the steroidogenic response to ACTH remained unchanged. This hyper-reactivity of cells from anesthetized animals was also evident in the presence of dibutyryl cyclic AMP. Moreover, there was increased conversion of exogenous pregnenolone into cortisol by cells from previously anesthetized animals. It was therefore concluded that ACTH increases in a lasting way the activity of steroidogenic pathway leading to cortisol synthesis by adrenocortical cells at sites distal to cyclic AMP generation. Besides an obvious increase of formation of pregnenolone in response to ACTH, it seems that this ACTH-induced enhancement in the capacity of the steroidogenic response to ACTH also implies a prolonged stimulatory influence of the peptide on the post-pregnenolone steroidogenic pathway leading to cortisol synthesis.

Adrenal Cortex↗
PubMed1983

Ontogeny of cell proliferation and DNA synthesis in rat colon: role of glucocorticoids.

This study was undertaken to determine whether the rat colon exhibits ontogenic changes in epithelial cell proliferation and DNA synthesis during growth. DNA synthesis was measured at intervals after birth in four colonic segments by the incorporation rates of [3H]thymidine. The labeled crypt cell index was determined by radioautography. New findings from our study are that 1) in each colonic segment of suckling rats, [3H]thymidine incorporation rate overshot the adult levels (49-119%) with a peak occurring at day 14 postpartum, 2) between days 14 and 20, the incorporation rates declined sharply to adult values and remained thereafter unchanged until adulthood; during the same period, the labeled and mitotic index decreased, respectively, from 52 to 19% and from 3.58 to 1.43%, 3) the decrease in DNA synthesis and in cell proliferation rates was concomitant with an upsurge in plasma total corticosterone initiated on day 14, and 4) treatment of 10-day-old sucklings with physiological doses of hydrocortisone for 4 consecutive days significantly depressed (P less than 0.01) colonic DNA content and DNA synthesis rates to levels about 45-67% of the control values. These data indicate that growth of the colon may be under the control of glucocorticoid secretion at the weaning period.

Aging↗
PubMed1983

[Evaluation of tolerance of a modified protein diet in obese subjects].

The purpose of this investigation was to evaluate the benefits and the potential risks of a very low calorie protein-diet in obese patients with metabolic abnormalities and at increased cardiovascular risk. To this end, the 420 kcal diet (with 50% of energy as protein) was administered for 10 days to 10 grossly obese subjects with glucose intolerance, hyperlipemia, arterial hypertension, ischemic cardiopathy and thrombotic risk related to high levels of fibrinogen factor VIII and reduced fibrinolytic activity. Weights loss averaged 360 g/day with a mean protein loss of 17 g/day occurring essentially during the very early phase of the diet. There was a rapid normalisation of blood pressure, plasma lipids and glycaemia. With the exception of a slightly negative potassium balance other ion remained in balance. There was no change in electrocardiogram, in parameters of blood coagulation or in hepatic and renal function. There was only a moderate increase in ketonaemia and plasma urate. It appears therefore, that an 8 to 10 day very low calorie protein-diet is well tolerated even in obese patients with increased cardiovascular risk, and that it corrects of several metabolic abnormalities without alteration in cardiac, hepatic or renal function.

Blood Coagulation↗
PubMed1982

Adrenocortical function and responsiveness to tetracosactrin infusions after intra-articular treatment with triamcinolone acetonide and hydrocortisone acetate.

The urinary free cortisol (UFC) output, considered a parameter of the action of the exogenous corticosteroid on the hypothalamo-pituitary axis, was followed in five patients who received a total of 12 intra-articular (i.a.) injections of 40 mg of triamcinolone acetonide (TCA) distributed over eight treatment sessions. The effect of intra-articular TCA injections on UFC output was null after three treatment sessions, transient (48 hr) after another three, and more prolonged (6 days), although slight, after the remaining two sessions. These results contrast with the lasting and profound inhibition of the UFC output induced either by the same TCA dose given intramuscularly, or by oral administration of dexamethasone to 30 normal subjects, 0.75 mg at 8-hourly periods for 48 hours. Adrenocortical reactivity, as measured by the response to synthetic ACTH (tetracosactrin) of both plasma cortisol levels and UFC output, was studied in another five patients prior to and after eight i.a. injections of 40 mg of TCA, and in three patients after six i.a. injections of 25-100 mg of hydrocortisone acetate. No decrease was observed after the i.a. injections of HCA. Considered as a group the response to tetracosactrin after TCA injections was not significantly altered. Two patients showed a decreased response of both UFC and plasma cortisol, although their values remained within the limits of those obtained in 44 normal control subjects. In contrast, profound inhibition of the tetracosactrin induced response occurred in a control group of 30 subjects given 0.75 mg of dexamethasone orally at 8-hourly periods for 48 hours.

Adolescent↗
PubMed1981

Influence of insulin and glucagon on sodium balance in obese subjects during fasting and refeeding.

To delineate the hormonal mechanism of dietary-induced changes in sodium balance, the role of insulin and glucagon in natriuresis of fast was evaluated in obese subjects submitted to a total starvation and given either glucagon or somatostatin infusion on day 4 of fast. While large amounts of glucagon (1 mg over 6 h) stimulated concomitantly ketonaemia, ketonuria and renal sodium losses, the ten-times lower amounts of glucagon induced an increase in renal ketone body and sodium excretion without any significant change in ketonaemia. It was concluded, therefore, that elevated plasma glucagon level may enhance renal sodium loss in ketotic states, through a direct renal effect reducing tubular ketone body reabsorption, hence increased ketonuria and natriuresis. It appears nevertheless that decreased insulin secretion, rather than an increase in plasma glucagon level must be considered as a key hormonal factor responsible for natriuresis attending starvation. Indeed, the concomitant reduction in plasma glucagon and insulin levels, resulting from somatostatin infusion on day 4 of fast, was followed by significant increase in natriuresis. The latter observation supports several previous studies indicating that insulin stimulates sodium reabsorption by the kidney and that the reduction in insulin secretion may induce an increase in renal sodium excretion. It was concluded, therefore, that not only sodium intake but also the carbohydrate content of the diet should be reduced in an attempt to induce a negative sodium balance and to correct hypertension in obese subjects.

3-Hydroxybutyric Acid↗
PubMed1977

Influence of glucagon on natriuresis and glucose-induced sodium retention in the fasting obese subject.

The role which glucagon could play in the mechanism of fasting natriuresis and renal sodium retention associated with carbohydrate refeeding was studied in thirty-seven non-diabetic obese subjects. In nine obese subjects undergoing a 7 day fast without any additional treatment (control group), the renal sodium excretion exceeded intake through the whole experimental period, with maximal natriuresis on day 2 of the fast. Blood glucose and plasma insulin (IRI) levels fell rapidly from the first day of fast on, while pancreatic glucagon (IRG) titres rose from day 1 to day 4, declining slightly thereafter. When additional subjects received intravenous glucose on day 4 (n = 6), there was a rise in blood glucose concentration and in IRI associated with a rapid drop in IRG restricted to the period of glucose infusion. The resulting antinatriuresis occurred essentially during the following 36 h, while IRG and IRI levels had returned to fasting levels. A comparable glucose load on day 4 associated with 0.1 mg glucagon (n = 5) still led to the glucose-induced antinatriuresis while 1 mg glucagon added to a similar glucose infusion completely abolished its antinatriuretic effect (n = 6). Glucagon infused alone on day 4 of fast aggravated fasting natriuresis (n = 5) but was devoid of this effect when administered 24 h after the glucose load (n = 6). These data indicate that fasting hyperglucagonaemia or its reduction upon glucose refeeding, cannot be considered as directly involved in renal mechanism(s) responsible for fasting natriuresis of antinatriuretic effects of carbohydrate. It is suggested that the role of glucagon is indirect, possibly through its influence on ketogenesis which in turn may alter renal sodium handling.

Adult↗
PubMed1976

Sodium balance and renal tubular sensitivity to aldosterone during total fast and carbohydrate refeeding in the obese.

In man the first days of fasting are characterized by enhanced natriuresis despite an increase in aldosterone secretion. Therefore the possibility of a decreased renal tubular sensitivity to this hormone was considered. The response to aldosterone infused before a fast and again on day 4 of fasting was evaluated in 12 starving obese women in terms of urinary sodium, chloride and potassium excretion. The data were compared to those obtained from 20 untreated starving obese women. In addition, salivary flow and sodium output were measured before and after aldosterone infusion in 4 out of the 12 patients treated. The involvement of aldosterone in the mechanism of fasting natriuresis and glucose-induced sodium retention was evaluated by means of spironolactone treatment (Aldactone A; 300 mg/day p.o.) on days 6 to 8 of the fast, with an oral glucose load (100 g) on day 7. Aldosterone infused on day 4 of the fast caused on average only 40% of the antinatriuretic effect it achieved before the fast. On the other hand even before aldosterone infusion, salivary sodium output was markedly reduced during the fast to levels comparable to those observed after aldosterone treatment in the pre-fast period. Furthermore, spironolactone administration on day 6 of the fast was associated with a prompt and marked increase in natriuresis. These 3 sets of facts indicate a definite biological activity of aldosterone during the initial phase of fasting with factor(s) interfering at the renal level with the normal expression of the hormonal action on sodium balance. There was still a distinct antinatiuretic effect of glucose in the presence of spironolactone, but less pronounced than when glucose was administered alone. The well-documented hyperaldosteronism of a total fast may represent a compensatory mechanism to decrease sodium loss at the end of a week-long fast. In addition a marked sodium-retaining effect of glucose can be demonstrated after aldosterone action is blocked by spironolactone. This provides another indication that glucose stimulates sodium retention through mechanism(s) which do not involve aldosterone.

Aldosterone↗