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Biomedical subjects

B Baranowska

Publications and source records attributed to B Baranowska.

At least 55 records · Page 3Linked to original sources
PubMed1984

The influence of inorganic phosphate and ATP on the kinetics of bovine heart muscle pyruvate kinase.

The mechanism of activation by inorganic phosphate and ATP of cardiac muscle pyruvate kinase was studied with the aid of steady-state kinetics. The enzyme was purified to homogeneity to a final specific activity of 400 units/mg (phosphate buffer, pH 7.6, 25 degrees C). At pH 7.6 the enzyme displays Michaelis-Menten kinetics with respect to both its substrates, phosphoenolpyruvate and ADP. Substrate kinetic constants are: app.Km(phosphoenolpyruvate) = 0.04 mM, app.Km(ADP) = 0.22 mM. Under the conditions used in the standard assay the specific activity is greatly enhanced by inorganic phosphate (50 mM) or ATP (2.5 mM). Each of these modifiers, acting separately, increases the Vmax without seriously affecting Michaelis constants and Hill coefficients. In the presence of both Pi and ATP, only a decrease in Vmax was observed. The kinetics of activation by inorganic phosphate of pyruvate kinase was examined. Studying the effect of varying concentrations of Pi on the initial rate we obtained a hyperbolic saturation curve with the app.Km(Pi) = 20 mM and Vmax = 167 units/mg. The evidence is presented that inorganic phosphate is a substrate for a side reaction catalyzed by cardiac pyruvate kinase. It is shown that in the presence of pyruvate, inorganic phosphate and ATP in the assay system, Pi is incorporated into acid-labile products of this reaction, inorganic pyrophosphate being one of them. These findings indicate the existence of an alternative reaction catalyzed by pyruvate kinase by which energy may be stored in the form of inorganic pyrophosphate.

Adenosine Triphosphate↗
PubMed1984

The role of endogenous opiates in the mechanism of inhibited luteinizing hormone (LH) secretion in women with anorexia nervosa: the effect of naloxone on LH, follicle-stimulating hormone, prolactin, and beta-endorphin secretion.

The aim of this study was to evaluate the role of endogenous opiates in the mechanism of decreased LH secretion in women with anorexia nervosa. For this purpose the effect of opiate receptor blockade with naloxone on LH, FSH, PRL, and beta-endorphins secretion was studied in 24 women with anorexia nervosa and 7 normal women. Serum LH, FSH, PRL, beta-endorphin-like substance, ACTH, and cortisol concentrations were measured before and after opiate receptor blockade after a single iv dose of 0.2 mg/kg naloxone or saline. Mean serum LH and FSH concentrations increased significantly after naloxone in the normal women. Eleven patients had a significant increase in serum LH concentrations in response to naloxone and 13 did not respond to naloxone with an increase in LH concentration. In the first group the basal LH values were higher than those in the second group. In the majority of patients in the first group amenorrhea preceded the wt loss, whereas in most patients in the second group amenorrhea appeared during the phase of wt loss. Naloxone did not alter pulsatile LH secretion in 6 women. No effect of naloxone on serum FSH and PRL concentrations was found. A significant increase in beta-endorphin-like substance levels after naloxone administration occurred in patients with anorexia nervosa. However, serum ACTH and cortisol concentrations were not altered in response to naloxone. In conclusion, the increase in LH release after opiate receptor blockade by naloxone suggests that endogenous opiates may play a role in the mechanism of inhibited LH secretion at least, in the majority of those women with anorexia nervosa in whom amenorrhea preceded wt loss. The results also point to a different mechanism of ACTH and beta-endorphin secretion in patients with anorexia nervosa.

Adolescent↗
PubMed1984

The effect of D-Trp6-LRH upon secretion of gonadotrophin--a possible therapeutic application in anorexia nervosa.

The aim of this study was to evaluate the effect of the agonistic LRH analogue (D-Trp6-LRH) on LH, FSH and prolactin secretion, and its possible efficacy in female patients with anorexia nervosa. The study included 18 female patients with anorexia nervosa and 7 healthy women in the same age group. The patients with anorexia nervosa were divided into two groups of 9 women each. The first group consisted of patients in the weight loss phase of the disorder and the second of 9 women who had achieved normal body weight. Additionally, in 6 women with anorexia nervosa serum LH concentration was determined in response to native LRH before and 14 days after the treatment with D-Trp6-LRH. Serum LH, FSH, prolactin concentrations were determined before and 5, 10, 24 and 48 h after administration of D-Trp6-LRH in a dose of 5 micrograms. The serum LH response to D-Trp6-LRH in the second group did not differ from that of the control group. However, in women with anorexia nervosa in the weight loss phase, LH release in response to administration of the analogue was significantly lower. FSH release after LRH analogue administration in both groups of patients with anorexia nervosa did not differ from that in the control group. The increased LH secretion in response to native LRH after treatment indicates that D-Trp6-LRH in low doses did not inhibit pituitary responsiveness. A dose of 5 micrograms of D-Trp6-LRH was administered in a therapeutic regimen every 48 h from 1 to 3 months to 7 of 9 patients with anorexia nervosa who exhibited amenorrhoea in spite of normalization of body weight.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1983

Enhanced serum prolactin concentration after metoclopramide stimulation in idiopathic oligozoospermia and azoospermia.

The aim of the study was to evaluate the hormonal pattern in men with idiopathic oligozoospermia and azoospermia. Material consisted of 13 sterile men, 21-34 years old (the mean - 27 years). Three of 13 patients had the third degree oligozoospermia, 3 - extreme oligozoospermia and 7 - azoospermia. The control group consisted of 11 healthy men who were found to have normozoospermia. In all patients and in control subjects the estimation of LH, FSH, prolactin (PRL), testosterone and dihydrotestosterone (DHT) in basal conditions and also PRL determination at 15, 30, 60 min after stimulation with metoclopramide (MCP 10 mg i.v.) were performed by radioimmunoassay. The results indicate that men with idiopathic oligo- or azoospermia have significantly higher prolactin level in response to dopaminergic receptor blockade with metoclopramide and significantly lower serum testosterone and DHT concentrations.

Adult↗
PubMed1983

Methodologic basis for the radioimmunoassay of endogenous LH-like activity in human prostatic tissue.

The aim of this study was to develop a technique for the radioimmunological determination of the activity of LH-like substances in the human prostate. The material comprised 19 specimens of prostatic tissue obtained during transbladder extirpation in patients with benign prostatic hyperplasia. Tissues of human testes and human sceletal muscle were used as controls. The method adopted for LH extraction from the membrane fraction of human prostatic tissue appeared to be sufficiently specific, accurate and sensitive for routine laboratory investigations. The concentrations of the LH-like immunoreactivity in human testicular tissue was found to be 57, 46 and 70 mU per g of the membrane fraction while those of the prostatic gland tissues ranged from 34 to 155 mU per g of the membrane fraction. However such LH-like substance was not found in human sceletal muscle tissue. It seems that the LH-type activity is an indirect proof for the existence of LH receptors in the human prostate.

Aged↗
PubMed1983

[Increased secretion of prolactin after inhibition of dopaminergic receptors by metoclopramide in patients with cancer of the prostate].

The authors begin by stressing the importance of the role of prolactin in the metabolism of testosterone in the cells of the prostate. They studied three groups of patients: 9 patients with prostatic cancer, 15 patients with benign prostatic adenoma and 11 healthy young men. Inhibition of the dopaminergic receptors by metoclopramide only resulted in a significant increase in serum prolactin in the patients with prostatic cancer, while the serum prolactin level remained unchanged in the young men and in the patients with prostatic adenoma. The authors believe that this increased secretion of prolactin in patients with prostatic cancer is related to a decrease in the testosterone: oestradiol ratio. They suggest the use of bromocriptine in patients with prostatic cancer no longer responding to oestrogen therapy in the event of prolactin over-secretion. Some papers have reported the beneficial effect of bromocriptine on the general health of these patients.

Adult↗
PubMed1983

[Interdependence between hormonal disorders, staging and degree of malignancy of prostatic gland cancer. 2].

The aim of this study was to estimate the relations between oestrogen, progesterone, prolactin (PRL) and gonadotrophin levels and the degree of advancement as well as that of malignancy of carcinoma of the prostate. Serum LH and FSH levels were determined under baseline conditions and after stimulation with LH-RH. In patients with metastases and in less differentiated forms of carcinoma the level of oestradiol (E2) was significantly higher. The testosterone/oestradiol ratio was notably lower in patients without metastases and in more differentiated forms. Serum progesterone was significantly higher in less differentiated forms of carcinoma. The concentration of LH in response to the administration of LH-RH was significantly higher in patients with metastases. Measurement of hormone levels at certain stages in the course of carcinoma of the prostate may be of practical value in the choice of appropriate hormone treatment.

Aged↗