[Neoplastic effect of indomethacin in N-methyl-N-nitrosourea induced mammary carcinogenesis in female rats].

Background: High levels of prostaglandins found in many neoplastic tissues, especially in colon cancer and breast cancer, suggest a role of cyclooxygenase in the process of carcinogenesis.

Material And Methods: The aim of this study was to analyse the chemopreventive potential of non-steroidal inflammatory drug indomethacin and its combination with pineal hormone melatonin in rat mammary carcinogenesis induced by N-methyl-N-nitrosourea. Indomethacin was administered 3 times a week and melatonin 4 times a week, both substances in a concentration of 20 µg/ml of drinking water.

The prevalence of cigarette smoking and its relation to certain risk predictors of cardiovascular diseases in central-Slovakian Roma children and adolescents.

The objective of the study was to determine some Cardiovascular Disease (CVD) risk factors in relation to cigarette smoking in 174 Roma children and adolescents (88 males and 86 females) and 131 non-Roma probands (males and females) aged 7-18 in central Slovakia. In this biethnic study, 26.4% of the Roma children and adolescents (more than twice contrary to the control group) were smokers.

Metabolic effects of pioglitazone in chemically-induced mammary carcinogenesis in rats.

In this paper, the effect of peroral antidiabetic pioglitazone, a thiazolidinedione derivate, on selected parameters of carbohydrate and lipid metabolism in N-methyl-N-nitrosourea-induced mammary carcinogenesis in female Sprague-Dawley rats was evaluated. Pioglitazone was administered in the diet at two concentrations (10 ppm and 100 ppm), the chemoprevention was initiated 12 days before carcinogenesis induction and lasted until the termination of the experiment. The experiment was terminated 17 weeks after carcinogenesis induction, selected organs and tissues were removed and weighed and basic metabolic and hormonal parameters were determined.

Cardiovascular risk predictors in central Slovakian Roma children and adolescents: regional differences.

The objective of the study was to determine some Cardiovascular Disease (CVD) risk factors in 174 Roma children and adolescents (88 males and 86 females) aged 7-18 in 3 Central Slovakian cities (44 from Zilina, 39 from Bansk, Bystrica and 91 from Rimavská Sobota). Venous blood samples were drawn in the morning, after a 12 hour overnight fast for biochemical analysis. Total cholesterol (TC) and triglycerides (TG) were determined enzymatically.

Pioglitazone in chemically induced mammary carcinogenesis in rats.

Data available from in-vitro and in-vivo studies suggest oncostatic properties of peroral antidiabetics, thiazolidinediones, in many types of cancer. This study is the first report on the chemopreventive effect of pioglitazone in mammary carcinogenesis in rats. Mammary carcinogenesis was induced by N-methyl-N-nitrosourea administered in two intraperitoneal doses per 50 mg/kg bodyweight on the 43rd and 50th postnatal days.

Metformin in chemically-induced mammary carcinogenesis in rats.

In this paper the chemopreventive effect of peroral antidiabetic metformin in mammary carcinogenesis in female Sprague-Dawley rats was evaluated. Mammary carcinogenesis was induced by N-methyl-N-nitrosourea (NMU) administered in two intraperitoneal doses each per 50 mg/kg b.w.

Celecoxib and melatonin in prevention of female rat mammary carcinogenesis.

The present experiment aims to evaluate tumor suppressive effects of a selective inhibitor of cyclooxygenase-2 (COX-2) celecoxib (Celebrex, Pfizer) administered alone and in combination with melatonin in the prevention of N-methyl-N-nitrosourea (NMU)-induced mammary carcinogenesis in Sprague-Dawley female rats. Celecoxib was administered daily at a concentration of 1.666 g/kg diet to two groups during 20 weeks (starting a week before first NMU application).

Prolonged melatonin administration in 6-month-old Sprague-Dawley rats: metabolic alterations.

The aim of this work was to evaluate the effect of prolonged melatonin administration on chosen metabolic and hormonal variables in male and female Sprague-Dawley rats. Melatonin was administered in tap water (4 microg/ml) daily from the 6th month of age. Rats were fed a standard type of diet ad libitum and were kept in a light regimen L:D--12:12h.

Effect of prolonged psychoemotional stress and melatonin on experimental mammary carcinogenesis in female rats.

The aim of the present study was to determine whether prolonged stress repeated immobilization in boxes during the period of 18 weeks (IMS) influenced development and progression of N-methyl-N-nitrosourea (NMU)-induced mammary tumors in female Sprague-Dawley rats and whether long-term MEL application affected changes caused by stress. NMU was applied intraperitoneally in two doses each of 50 mg/kg b.w.

NMU-induced mammary carcinogenesis in female rats is influenced by repeated psychoemotional stress.

Epidemiological and experimental studies indicate psychoemotional stress as an important factor in carcinogenesis. The aim of this study was to evaluate the effect of restraint stress on N-nitroso-N-methylurea (NMU)-induced mammary carcinogenesis. Female Sprague-Dawley rats were injected with two intraperitoneal NMU doses each per 50 mg/kg b.

Chemoprevention of mammary carcinogenesis in female rats by rofecoxib.

Epidemiological and experimental studies indicate that non-steroidal anti-inflammatory drugs play role in the prevention of human neoplasia including mammary gland cancer. In this study, tumour suppressive effects of a selective inhibitor of cyclooxygenase-2 (COX-2) rofecoxib in the prevention of N-methyl-N-nitrosourea (NMU)-induced mammary carcinogenesis in female Sprague-Dawley rats were evaluated. Rofecoxib was dietary administered in two concentrations-0.

Variability of mammary carcinogenesis induction in female Sprague-Dawley and Wistar:Han rats: the effect of season and age.

It is important to determine and clarify the variability of mammary carcinogenesis induction in animal experimental studies particularly in connection with chemoprevention projects. The circannual seasonal rhythms of hormone levels or various parameters within the immune system may involve factors participating in mammary gland carcinogenesis. In our study, 19 experiments were conducted and all of them lasted for about 25 weeks after chemical carcinogen administration (DMBA or NMU) under standard laboratory conditions.

Nimesulide and melatonin in mammary carcinogenesis prevention in female Sprague-Dawley rats.

Tumorsuppressive effects of a selective inhibitor of cyclooxygenase-2 (COX-2) nimesulide (NIM) activity and pineal hormone melatonin (MEL) and their combination in two chemopreventive studies of mammary carcinogenesis were evaluated. Mamary tumors in female Sprague-Dawley rats were induced by N-methyl-N-nitrosourea (NMU) and by 7,12-dimethylbenz(a)anthracene (DMBA), respectively. The treatment with NIM (applied subcutaneously twice a week in the dose of 5 mg/kg b.

Effect of K, MG aspartate on some biological parameters of aging rats.

The effect of K and Mg salts of aspartic acid (Cardilan) on the serum concentration of selected proteins and phagocytic activity in aging male Wistar rats was investigated. Cardilan was administered in tap water for 7 days a month for 3 months before the last observed interval (12, 18 and 24 month). In a part of animals, the aging process was accelerated by sublethally gamma-irradiation.

Preventive effects of raloxifene and melatonin in N-methyl-N-nitrosourea-induced mammary carcinogenesis in female rats.

The aim of this study was to evaluate preventive effects of raloxifene (RAL), melatonin (MEL) and their combination in N-methyl-N-nitrosourea (NMU)-induced rat mammary carcinogenesis. MEL-treatment began 12 days and RAL treatment began 10 days prior to carcinogen administration and continued till the end of experiment (24 weeks after first carcinogen administration). RAL was administered subcutaneously twice a week in the dose of 5 mg/kg b.

Preventive effect of indomethacin and melatonin on 7, 12-dimethybenz/a/anthracene-induced mammary carcinogenesis in female Sprague-Dawley rats. A preliminary report.

The aim of the experiment was to analyse the oncostatic effect of nonsteroidal antiinflammatory drug INDO, hormone MEL and combination of both substances in DMBA-induced mammary carcinogenesis in female SD rats. Chemoprevention started 10 days before the application of the first dose of DMBA to 35-day-old rats. INDO was administered in tap water (20 microg/ml of water) for 3 days in a week (days 2, 4 and 6), MEL solution in the concentration of 20 microg/ml of tap water was administered between 3 p.

Effects of tamoxifen and melatonin on mammary gland cancer induced by N-methyl-N-nitrosourea and by 7,12-dimethylbenz(a)anthracene, respectively, in female Sprague-Dawley rats.

Chemopreventive effects were analysed of antioestrogen TAM and of MEL on NMU- or DMBA-induced mammary gland cancer, respectively, in female Sprague-Dawley rats. NMU was administered intraperitoneally in two doses each of 50 mg/kg b.w.

Repeated administration of carcinogen in critical developmental periods increases susceptibility of female Wistar: han rats to mammary carcinogenesis induction.

Analysis and knowledge of individual strain susceptibility of experimental animals to induction of carcinogenesis is important especially in regard to possibility of transfer of these facts to human pathology, first of all to chemopreventive projects. Our group (AHLERS et al. [1]) reported very low sensitivity of female Wistar:Han rats to induction of mammary carcinogenesis by 7,12-dimethylbenz(a)anthracene (DMBA) and by N-methyl-N-nitrosourea (NMU).

Mammary carcinogenesis induced in Wistar:han rats by the combination of ionizing radiation and dimethylbenz(a)anthracene: prevention with melatonin.

The primary cancer chemoprevention is an important topic of experimental oncology. We have analyzed the possible oncostatic properties ofmelatonin in a combined model of radiation plus chemocarcinogen-induced mammary carcinogenesis. Virgin female rats of Wistar:Han strain were continuously irradiated with daily dose 96 mGy of gamma rays up to 15 days.

Effects of retinyl acetate and melatonin on N-methyl-N-nitrosourea-induced mammary carcinogenesis in rats. A preliminary report.

The aim of this project was to evaluate the effect of retinyl acetate (RA), melatonin (Mel) and their combination on N-methyl-N-nitrosourea (NMU)-induced rat mammary carcinogenesis. Female Sprague-Dawley rats were given two intraperitoneal doses of NMU, each of 50 mg/kg of b.w.

Melatonin and retinyl acetate as chemopreventives in DMBA-induced mammary carcinogenesis in female Sprague-Dawley rats.

One goal of experimental oncology is to find and test effective chemopreventive substances which can suppress malignant transformation of the cells, their accumulation and invasion. Mammary gland tumours were induced by DMBA applied intragastrically (10 mg/rat, three times) every three days between postnatal days 50 and 60 in female Sprague-Dawley rats. One day after the last dose we started chemoprevention with Mel, RA and combination of both drugs, which lasted 25 weeks.

Daily rhythm in rat pineal catecholamines.

A daily rhythm in the oscillations of pineal dopamine, norepinephrine and epinephrine content was found in male Wistar: Han rats. The acrophases of the oscillations were localized in the first half of the dark period and generally higher values were found in the dark part of the day.

Two-phase response of rat pineal melatonin to lethal whole-body irradiation with gamma rays.

Male Wistar rats adapted to artificial light:dark (LD) regimen 12:12 h were whole-body irradiated with a single dose of 9.6 Gy of gamma rays and sham/irradiated in the night in darkness. The rats were examined 60 min, 1, 3 and 5 days after exposure between 22:00 and 01:30 h in the darkness.

Very low sensitivity of Wistar:Han female rats to chemocarcinogens in mammary carcinogenesis induction.

Recently a great variability of various mouse and rat strains in the sensitivity for mammary tumors induction by means of physical (ionizing radiation) or chemical (mostly 7,12-dimethylbenz/a/anthracene, DMBA and N-methyl-N-nitrosourea, NMU) initiating agents was noted. The categorization into four groups was recommended in rats; the first group with high sensitivity (the incidence of tumors practically 100%, the frequency of tumors per entire treated group 2.0), the second with average type of sensitivity (incidence below 100%, frequency between 1.

Reduced pineal melatonin biosynthesis in fractionally irradiated rats.

The effects of ionizing radiation on pineal melatonin and on key enzymes of its metabolism have been studied in our laboratory. After adaptation to an artificial light/dark cycle of 12:12 h, male Wistar rats were fractionally whole-body irradiated with a dose of 2.4 Gy of gamma-rays twice a week up to total doses of 4.