Biomedical subjects

M Haluzík

Publications and source records attributed to M Haluzík.

At least 55 records · Page 3Linked to original sources

PubMed2000

The regulation of adenohypophyseal prolactin secretion: effect of triiodothyronine and methylene blue on estrogenized rat adenohypophysis.

Estrogens and thyroid hormones contribute importantly to cell proliferation and tumor transformation in the pituitary gland. We found that methylene blue antagonized estrogen-promoted adenohypophyseal enlargement and the enhancement of prolactin secretion. The purpose of the present article is to provide a review about neurotransmitters and their receptors involved in estrogen-induced anterior pituitary growth and in the antagonistic effects of triiodothyronine (T3) and methylene blue (MB). Central dopaminergic and noradrenergic systems are the most important factors regulating pituitary growth and function. Recently nitric oxide (NO) was added to the list of the neurotransmitters and neuropeptides involved in the control of the anterior pituitary secretion. Our data suggest that estrogen-induced anterior pituitary growth is associated with decreased synthesis and metabolism of central catecholamines, reduction of adenohypophyseal beta-adrenergic receptors and increase of dopamine DA-2 receptors. We found that the treatment with T3 or MB prevented both estrogen-induced catecholaminergic inhibition and dopamine DA-2 receptor increment in the anterior pituitary. In contrast to T3, MB given alone also slightly decreased the anterior pituitary weight. Serum levels and anterior pituitary content of prolactin were increased after treatment with estradiol benzoate (EB), whereas T3 or MB partially attenuated prolactin hypersecretion after estrogen administration. This is in accord with the attenuation of EB-induced inhibition of dopaminergic system by T3 and MB. MB given in combination with EB also partially attenuated EB-promoted rise of adenohypohyseal NO synthase activity which plays an important role in the regulation of prolactin secretion. Further studies on central catecholaminergic systems, pituitary receptors, the nitrergic system and mechanisms of intracellular signal transduction are necessary for better understanding of pituitary tumor transformation and possibly for the discovery of new approaches towards treating patients with these diseases.

Adrenergic beta-Agonists↗

PubMed2000

The role of nitric oxide in the development of streptozotocin-induced diabetes mellitus: experimental and clinical implications.

The overproduction of the free radical nitric oxide (NO) by activated immunocompetent cells with subsequent development of local oxidative stress is supposed to be one of the possible pathophysiological mechanisms of beta-cell damage during streptozotocin-induced diabetes. The blockade of increased NO production by simultaneous administration of NO-synthase inhibitors partially suppresses the hyperglycemia and the increase of glycated hemoglobin concentration. Here we summarize the current state of knowledge concerning the modulation of streptozotocin-induced diabetes development by treatment with NO-synthase inhibitors including the partial inhibition of the changes in serum leptin levels. The differences in the reaction to streptozotocin administration between wild type mice and inducible NO-synthase knockout mice are also discussed. The overproduction of NO during the development of streptozotocin-induced diabetes is probably an important part of the complex autoimmune reaction which leads to the destruction of pancreatic beta-cells. Further clarification of the role of nitric oxide in streptozotocin-induced diabetes development could have important clinical implications.

Animals↗

PubMed2000

Serum leptin levels in patients with sideropenic and pernicious anemia: the influence of anemia treatment.

Leptin is a 16 kDa protein hormone involved in food intake, energy expenditure regulation and numerous other physiological processes. Recently, leptin has been demonstrated to stimulate hematopoietic stem cells in vitro. The aim of our study was to measure serum leptin and erythropoietin levels in patients with sideropenic (n = 18) and pernicious anemia (n=7) before and during anemia treatment. Blood samples for the blood count, leptin and erythropoietin determinations were obtained by venepunction at the time of the diagnosis of anemia and after partial and complete anemia recovery. The relationships of serum leptin levels to erythropoietin levels and blood count parameters were also studied. No significant differences in serum leptin levels between the groups studied were found. The serum leptin levels in none of groups were modified by treatment of anemia (basal levels, the levels during treatment and after anemia recovery were 13.1+/-14.5 vs 12.8+/-15.6 vs 12.0+/-14.8 ng/ml in patients with sideropenic anemia and 7.8+/-8.5 vs 9.5+/-10.0 vs 8.9+/-6.6 ng/ml in patients with pernicious anemia). The erythropoietin levels were higher at the time of anemia in both groups and decreased significantly after partial or complete recovery. Serum leptin levels in both groups correlated positively with the body mass index. No significant relationships were found between serum leptin levels and erythropoietin values or various parameters of the peripheral blood count. We conclude that serum leptin levels in patients with sideropenic and pernicious anemia positively correlate with the body mass index but are not influenced by the treatment of anemia.

Adult↗

PubMed1999

[The effect of partial refeeding on serum levels of leptin and resting energy expenditure in female patients with anorexia nervosa].

BACKGROUND: Serum leptin levels and resting energy expenditure are significantly decreased in patients with anorexia nervosa compared to healthy subjects. Partial realimentation of patients with anorexia nervosa increases both these parameters. However, there so far are no data concerning the relationship of serum leptin levels and resting energy expenditure in patients with anorexia nervosa. The aim of our study was to follow the relationship of serum leptin levels and resting energy expenditure in patients with anorexia nervosa before and after refeeding. METHODS AND RESULTS: It was found that serum leptin levels in patients with anorexia nervosa both before and after partial realimentation were significantly lower compared to healthy subjects (0.86 +/- 0.9 ng.ml-1 and 1.77 +/- 1.9 ng.ml-1 vs 6.85 +/- 3.0 ng.ml-1, p < 0.05). The total resting energy expenditure in patients with anorexia nervosa both before and after realimentation were significantly lower than in the control group (4973 +/- 979 and 5263 +/- 899 vs 6401 +/- 827 kJ/day, p < 0.05). When expressed per body weight the resting energy expenditure in patients with anorexia nervosa was significantly higher in comparison with the control group (122.3 +/- 20.6 and 121.5 +/- 14.2 vs 104.2 +/- 14.6 kJ/day, p < 0.05). The differences in resting energy expenditure in patients with anorexia nervosa before and after refeeding did not reach statistical significance. The body mass and the body fat content increased significantly after realimentation index (14.5 +/- 1.4 vs 15.6 +/- 1.5 kg.(m2)-1 and 14.9 +/- 3.4 vs 16.6 +/- 3.7, p < 0.05) but remained still below of those of control group (BMI 22.3 +/- 2.7, body fat content 26.9 +/- 4.2). CONCLUSIONS: Our study confirmed the reduced serum leptin levels and the total resting energy expenditure in patients with anorexia nervosa compared to healthy age-matched subjects. No statistically significant relationships were found between serum leptin levels and resting energy expenditure either in healthy subjects or in patients with anorexia nervosa before or after partial realimentation respectively.

Adolescent↗

PubMed1999

[Nutritional status of drug addicts in a methadone program].

BACKGROUND: Substitution treatment of drug addicts with methadone has been used in many countries for more than 35 years. In our country it was started in 1997. The objective was above all to evaluate the nutritional status and some biochemical parameters before and after 18 months of methadone substitution. METHODS AND RESULTS: A total of 14 patients were examined (9 men, 5 women), mean age 35 years, range 26-44 years, highly dependent on opiates: heroin, codeine and its derivatives). The examination was made before onset of treatment and after 18 months of treatment. The subjective feeling of all patients improved, they felt more active and efficient. The Kehlet score declined from 5.8 +/- 1.9 to 3.8 +/- 1.5. The body weight increased from 69.3 +/- 14.8 to 78.6 +/- 19.7 kg. BMI from 22.8 +/- 3.2 to 25.5 +/- 5.0 (kg/m2), the skinfold above the triceps muscle from 11.9 to 16.6 mm, prealbumin from 0.17 +/- 0.05 to 0.22 +/- 0.66 g/l). The handgrip strength did not increase, no significant changes were recorded in albumin and transferrin levels. The raised serum aminotransferase levels did not change (due to chronic hepatitis). CONCLUSIONS: Substitution treatment of drug addicts with methadone leads not only to improvement of the subjective state but also to objective signs of a better nutritional status.

Adult↗

PubMed1999

[Effect of aerobic training in top athletes on serum leptin: comparison with healthy non-athletes].

Leptin is a protein hormone produced by adipocytes. Its serum concentration in the most of cases precisely reflect the total body fat content. The aim of our study was to follow up the influence of regular aerobic training on serum leptin levels. Therefore the serum leptin levels, basic anthropometric parameters and serum lipids were compared in 11 intensively trained race walkers and 10 age-matched non sporting control subjects. We have found, that serum levels, body weight, body mass index, body fat content, total and LDL-cholesterol were significantly decreased in walkers group in comparison with control subjects. Serum leptin levels positively correlated with body fat content and body mass index only in control group, in the walkers group the correlation was non-significant. The results of our study demonstrate, that regular aerobic training accompanied with the decrease of body fat content leads to the significant drop of serum leptin levels.

Adipose Tissue↗

PubMed1999

Serum leptin levels in patients with anorexia nervosa before and after partial refeeding, relationships to serum lipids and biochemical nutritional parameters.

Leptin is a protein hormone produced by adipocytes that provide information about the body fat content. It was previously reported that serum leptin levels were decreased in patients with anorexia nervosa in comparison with healthy control subjects. The aim of our study was to compare serum leptin levels in patients with anorexia nervosa (n=11, initial mean BMI=15.4 kg/m2) before and after partial recovery with control age-matched subjects (n=11, mean BMI= 20.3 kg/m2) and to study the relationships of leptin levels, serum lipids and biochemical nutritional parameters. We found that serum leptin concentrations in patients with anorexia nervosa were significantly reduced in comparison with control subjects (3.61 vs 9.37 ng.ml(-1), p<0.01). Serum cholesterol, triglycerides, total protein and albumin in patients with anorexia nervosa either before or after partial recovery did not differ from the control group. After partial recovery, a significant increase in serum leptin was observed (4.83 vs 3.61 ng.ml(-1), p<0.05), but the values still remained significantly lower than in the control group (p<0.01) Leptin levels correlated positively with the body mass index in the control group and anorexia nervosa group before recovery. The correlation with BMI in the anorexia nervosa group after refeeding was not significant. No significant correlation was found between leptin concentrations and serum lipids, total protein, albumin and prealbumin, respectively. Serum leptin thus represents a sensitive parameter that reflects the nutritional status in patients with anorexia nervosa suitable for long-term follow up during refeeding therapy.

Adult↗

PubMed1999

Serum leptin concentrations in patients with combined hyperlipidemia: relationship to serum lipids and lipoproteins.

Leptin is a protein hormone produced predominantly by adipocytes. Serum leptin concentrations in healthy individuals positively correlate with the body fat content and body mass index, i.e. they are higher in obese than in lean subjects. The relations between serum leptin concentration and serum lipids and lipoproteins is not yet clear. The aim of our study was to compare serum leptin concentrations in 22 randomly selected patients with untreated combined hyperlipidemia and 19 healthy control subjects matched for age and the body mass index. The relationship was studied between serum leptin concentrations and serum lipids (total, HDL, LDL cholesterol and triglycerides) and lipoproteins (lipoprotein (a), apolipoprotein B). It was found that serum leptin levels in patients with combined hyperlipidemia did not significantly differ from those of control subjects (6.69+/-4.3 vs 5.78+/-3.2 ng.ml(-1)). Serum leptin concentrations in both groups correlated positively with the body mass index. The relationship between leptin concentrations and lipid or lipoprotein levels found in any of the studied groups was not statistically significant. We conclude that serum leptin concentrations in patients with combined hyperlipidemia as well as in healthy control subjects reflect the body fat content and have no significant relation to serum lipids or lipoproteins.

Adult↗

PubMed1999

[Relation of serum leptin levels and regulation of resting energy expenditure].

Leptin is a protein hormone produced by adipocytes. Its serum concentrations in the most of cases positively correlate with total body fat content and body mass index (BMI). Leptin plays a role in the food intake regulation. It also increases resting energy expenditure in hypoleptinaemic ob/ob mice. Its relationship to resting energy expenditure in human is less clear. The aim of our study was to follow the serum leptin levels in healthy females (n = 12) and males (n = 14) and their relationship to resting energy expenditure, body fat content, other antropometric and nutritional biochemical parameters. It was found that serum leptin levels were significantly higher in females comparing to males (6.8 +/- 3 ng.ml-1 vs. 2.6 +/- 1 ng.ml-1, p < 0.05). The serum leptin levels correlated positively with body fat content and body mass index in both groups. In females the positive correlation between body weight and serum leptin levels was found. No statistically significant relationship between serum leptin levels and resting energy expenditure, serum total protein, albumin or prealbumin concentration was found in any of studied groups. The results of our study do not testify to direct relationship between serum leptin levels and resting energy expenditure in young healthy individuals.

Adult↗

PubMed1999

[Serum leptin levels in female patients with protein-calorie malnutrition and its relation to biochemical indicators of nutritional status].

Leptin is a protein hormone produced by adipocytes. Its serum concentrations in the most of cases positively correlate with total body fat content. Serum leptin levels are increased in obese in comparison with lean subjects. Leptin levels in females are two or three times higher than in body mass index and age-matched males. The aim of our study was to investigate the serum leptin concentrations in females with protein-caloric malnutrition of various aetiology, the relationship between leptin levels and biochemical nutritional parameters and to compare the values with those of age-matched control group. Totally 12 patients with malnutrition of various aetiology and 14 control age-matched healthy subjects were included into the study. It was found that serum leptin levels were significantly decreased in malnutrition group in comparison with control group (3.09 +/- 1.33 ng.ml-1 vs 9.42 +/- 2.76 ng.,l-1, p < 0.05). A significant decrease in body mass index, serum total protein, albumin, prealbumin, cholesterol and triglycerides concentration was also found in malnutrition in comparison with control group. While a strong positive correlation between leptin concentrations and body mass index was found in control group (r = 0.72, p < 0.05), no statistically significant relation between leptin and body mass index was observed in malnutrition group. Furthermore, no significant relationship was found between serum leptin levels and serum total protein, albumin, prealbumin, cholesterol and triglycerides neither in control or in malnutrition group. We conclude that serum leptin levels in patients with malnutrition are significantly decreased in comparison with age-matched healthy control subjects. The loss of positive correlation between leptin and body mass index in malnutrition group is explainable by the changes of body composition in patient with malnutrition. The body mass index value in these patients reflects the total body fat content less precisely than in healthy controls.

Biomarkers↗

PubMed1999

The influence of methylene blue and L-NAME on the development of streptozotocin-induced diabetes in rats.

The cytokine-induced overproduction of nitric oxide by immunocompetent cells with subsequent development of oxidative stress is suggested to be one of important pathophysiological mechanisms of the pancreatic beta cells damage in streptozotocin-induced experimental diabetes. The aim of our study was to compare the influence of two nitric oxide inhibiting compounds: methylene blue and L-NAME (N-omega-nitro-L-arginine-methyl ester) on the streptozotocin diabetes development and the oxidative stress parameters in male rats. Blood glucose, glycated haemoglobin, serum malondialdehyde concentration and erythrocyte superoxide dismutase activity were measured in control, diabetic (streptozotocin 70 mg/kg i.p.), methylene blue (50 mg/kg in the food), and diabetic group treated simultaneously with methylene blue (10 animals in each group). In the second experiment the L-NAME was used instead of methylene blue. It was found that both methylene blue and L-NAME partially suppressed the development of diabetes, but did not unambiguously influence the oxidative stress parameters. We conclude, that both methylene blue and L-NAME partially suppress the development of streptozotocin-induced diabetes in rats. The precise mechanism of this effect is not clear. We failed to demonstrate clear effect of methylene blue and/or L-NAME on oxidative stress development in diabetic rats.

Animals↗

PubMed1999

Effect of exogenous estrogen on male rats bone.

Not only androgens however but also estrogens may be important for the growth and maintenance of the male skeleton. The estradiol treatment of intact male rats significantly decreased serum testosterone concentrations and the weight of seminal vesicles, however, not to the level of castrated animals. In spite of a low serum testosterone the administration of estradiol did not produce changes in the density, ash weight and mineral content of the tibia. In castrated rats with low serum testosterone bone density, ash weight and mineral content of the tibia were decreased, compared with intact controls. These our observation indicate that estrogen has a important role to retain bone mass in males as well as females.

Animals↗

PubMed1998

[Nitric oxide--its effects and significance in the human body].

Nitric oxide is a reactive gas with series of important functions in human body. An important deal of nitric oxide in the etiology and pathogenesis of series of autoimmune diseases, degenerative diseases of central nervous system etc. is suggested. This article summarizes the current knowledge about NO mean in medicine with impact to a perspective possibility of influence of any diseases by modulation of nitric oxide synthesis.

Humans↗

PubMed1998

The changes of the thyroid function and serum testosterone levels after long-term L-NAME treatment in male rats.

Nitric oxide is a highly reactive gas that is produced by many tissues and exerts a series of physiological and pathophysiological effects. We studied the changes of the serum testosterone, thyroxine and thyrotropin levels, thyroid and anterior pituitary weights and thyroid cGMP concentrations in male Wistar strain rats treated with estradiol benzoate (EB) (1 mg/kg, im twice a week) and nonselective NO-synthase inhibitor L-NAME (N-omega-nitro-L-arginine methyl ester) alone and with combination of these substances. We have found that L-NAME in a dose 100 mg/kg/day but not in a dose 50 mg/kg/day increased the serum thyroxine and testosterone levels and in the case of testosterone in a higher dose partially blocked its drop when administered simultaneously with EB. The serum thyrotropin levels significantly fell after L-NAME and EB treatment. The cGMP thyroid levels changed only slightly in groups treated EB and L-NAME alone and were significantly decreased in group treated with combination of these substances. The nitric oxide thus seems to be an important modulator of thyroid and testicular function. The cGMP activation cascade is not probably involved in the nitric oxide induced changes of thyroid function.

Animals↗

PubMed1998

Lower serum leptin concentrations in rugby players in comparison with healthy non-sporting subjects--relationships to anthropometric and biochemical parameters.

Leptin is a protein hormone synthesized by adipocytes. Its serum concentrations reflect the total body fat content. Serum leptin concentrations are significantly higher in obese than in lean people and in women than in men. However little information about the influence of physical activity on serum leptin concentrations is available. We have compared the body weight, the body mass index (BMI), the body fat content (measured by caliper as skinfold thickness) and the serum concentrations of leptin, triglycerides, total, high density and low density lipoprotein (LDL) cholesterol in 14 top rugby players and 10 healthy controls. We found that serum leptin, total and LDL cholesterol concentrations were significantly lower in the rugby players group than in the control subjects. The body weight and BMI were significantly higher in the rugby players, while the body fat content was only slightly (non-significantly) higher in the control group. The serum leptin concentrations in both groups positively correlated with the BMI and body fat content and also with LDL concentrations in the control group. The serum leptin concentrations in the rugby players were lower than in the non-sporting subjects despite a similar body fat content in both groups. We would therefore suggest the possibility that regular hard physical training decreases serum leptin concentrations not only by the decrease of total body fat content, but also by a separate mechanism, which is not directly dependent on the changes in the amount of body adipose tissue.

Adipose Tissue↗

PubMed1998

Estrogenic effect of estradiol-sulfamate on the male rat anterior pituitary.

Estrogen sulfamates (ES) are used for a new treatment strategy to avoid liver-hormone and hormone-liver interactions. ES represent new synthetic steroids having an increased systemic and reduced hepatic estrogenicity when given orally [1,2]. In the present study effects of ES and estradiol-benzoate (EB) on adenohypophyseal (AP) and serum concentrations of prolactin (PRL), luteinizing hormone (LH), and pituitary contents of cAMP and cGMP in the male rat are demonstrated. The weight gain of experimental animals treated by ES, EB or both hormones simultaneously was significantly lower compared to controls. EB but not ES significantly increased the weight of the AP. The amounts of PRL in the AP and serum were significantly increased after EB administration. ES significantly increased only AP content of PRL. EB administered simultaneously with ES exhibited an additive effect on the AP plasma concentrations of PRL. The EB or ES significantly decreased AP and serum concentrations of LH. ES given simultaneously with EB further decreased AP and serum concentrations of LH. After administration of either ES or EB, AP contents of cAMP and cGMP were significantly increased. An additive effect of these estrogens on the cGMP content was found. ES given simultaneously with EB further increased cGMP content in the AP but partially inhibited the effect of EB on the AP cAMP content. The present results demonstrate that the effects of ES on the AP content of PRL, LH, cAMP, and cGMP differ from the effects of EB. Whether this is due to lower levels of estradiol after the administration of ES secondary to its different absorption when compared to EB is unknown. Thus, our data support the concept that the ES has a lesser estrogenic effect on the AP function.

Animals↗

PubMed1998

The influence of NO synthase inhibitor and free oxygen radicals scavenger--methylene blue--on streptozotocin-induced diabetes in rats.

The excessive production of nitric oxide (NO) and the subsequent increase of local oxidative stress is suggested as one of the pathophysiological mechanisms of streptozotocin-induced diabetes. It was reported that the administration of NO synthase inhibitors partially attenuated the development of streptozotocin-induced diabetes and reduced hyperglycaemia. Here we have studied the influence of methylene blue, which combines the properties of NO synthase inhibitor with antioxidant effects. The experiments were performed on male rats divided into four groups: control, diabetic (single dose of 70 mg of streptozotocin/kg i.p.), methylene blue (50 mg/kg in the food) and diabetic simultaneously fed with methylene blue. After 45 days the experiments were discontinued by decapitation. Serum glycaemia, glycated haemoglobin and oxidative stress parameters (plasma malondialdehyde concentration and erythrocyte superoxide dismutase activity) were significantly higher in the diabetic group. Simultaneous methylene blue administration partially reduced glycaemia and glycated haemoglobin, but did not decrease oxidative stress. We conclude that NO synthase inhibitor methylene blue partially attenuates the development of streptozotocin-induced diabetes in male rats, but does not reduce the development of oxidative stress in the diabetic group.

Animals↗

PubMed1998

Independence of estrogen-induced pituitary proliferation on local IGF-I mRNA and EGF mRNA expression. Modifying effects of tamoxifen and terguride.

Pituitary hyperplasia as well as proliferation of the endometrium are typical responses to estrogen administration in rodents. Both insulin-like growth factor-I (IGF-I) and epidermal growth factor (EGF) have been implicated as paracrine mediators and amplifiers of estrogen action in the rodent uterus. The auto/paracrine role of IGF-I, EGF, their receptors and IGF binding proteins in pituitary proliferation has not yet been solved. Here we have used a semi-quantitative reverse transcription polymerase chain reaction (RT PCR) assay to demonstrate the changes in IGF-I mRNA and EGF mRNA abundance in the proliferating male rat pituitary in response to estradiol benzoate (EB; 1 mg/kg b.w. twice weekly i.m. for 3 weeks) and modifying effect of drugs antagonizing the pituitary enlargement - antiestrogen tamoxifen (TAM, 5 mg/kg b.w. daily) and also the dopaminergic agonist terguride (TER, 0.66 mg/kg b.w. daily, routinely used for the treatment of prolactinomas). In three separate experiments, EB induced a 2.2-2.5 fold increase in pituitary weight. The abundance of IGF-I and EGF mRNAs in pituitaries of EB-treated animals did not differ from the controls in two experiments and in the third series with the most marked pituitary hyperplasia mRNAs of both growth factors were even significantly decreased. Antiestrogen TAM administered with EB partially blocked the EB-induced proliferation and significantly stimulated IGF-I mRNA (p=0.003) and EGF mRNA (p=0.023) expression, while EB or TAM alone did not stimulate mRNAs of the studied growth factors. Significant antiproliferative effect of dopaminergic agonist TER on EB-induced pituitary proliferation (p=0.006) was accompanied with decreased IGF-I mRNA (p=0.025), but not EGF mRNA abundance. Our results suggest that the estrogen-induced pituitary proliferation is independent of the local expression of IGF-I and EGF mRNAs.

Animals↗