Search PubMed⌕ Search

Biomedical subjects

R H Ylikahri

Publications and source records attributed to R H Ylikahri.

At least 19 recordsLinked to original sources
PubMed1987

Inhibition of testosterone biosynthesis by ethanol: multiple sites and mechanisms in dispersed Leydig cells.

Isolated rat Leydig cells were incubated for 2 h in sealed polycarbonate tubes under O2/CO2 atmosphere with 10 mIU/ml human chorionic gonadotropin. 20 mmol/l ethanol reduced the concentration of testosterone (16%, P less than 0.025); raised the concentrations of pregnenolone (60%, P less than 0.001), androstenedione (86%, P less than 0.001) and dehydroepiandrosterone (81%, P less than 0.001); but did not change concentrations of progesterone and 17 alpha-hydroxyprogesterone in the incubation medium. Ethanol also raised the lactate/pyruvate ratio in the Leydig cell suspension. 4-Methylpyrazole (0.5 mmol/l) abolished the ethanol-induced changes. The present results suggest that ethanol inhibits testosterone synthesis in isolated rat Leydig cells at the pregnenolone-to-testosterone pathway by inhibiting 3 beta-hydroxy-5-ene-steroid dehydrogenase/5-ene-4-ene-isomerase catalyzed reactions and the conversion of androstenedione to testosterone. These inhibitions are caused by consequences of ethanol metabolism. A likely mechanism for the former inhibition is that the increase in the NADH/NAD+ ratio in Leydig cells leads to inhibition of reactions catalyzed by 3 beta-hydroxy-5-ene-steroid dehydrogenase/5-ene-4-ene isomerase, but the inhibition mechanism operating at the androstenedione-to-testosterone step remains to be characterized.

3-Hydroxysteroid Dehydrogenases↗
PubMed1984

Inhibition of testosterone biosynthesis by ethanol: relation to the pregnenolone-to-testosterone pathway.

The concentrations of metabolites in the pregnenolone in equilibrium testosterone pathway were determined in freeze-stopped testes in control rats and during ethanol intoxication (2 h after injection of 1.5 g ethanol/kg body wt). Ethanol lowered the mean testicular concentrations of testosterone (by 63-74%), androstenedione (49-81%), 17-hydroxyprogesterone (60-76%), progesterone (29-67%) and pregnenolone (12-25%). 4-Methylpyrazole had no effect on the ethanol-induced changes. The present results reveal no inhibition at the 17-hydroxyprogesterone----androstenedione----testosterone steps, but do not exclude inhibition before the step yielding pregnenolone and at the pregnenolone----progesterone----17-hydroxyprogesterone steps.

17-alpha-Hydroxyprogesterone↗
PubMed1983

Decreased serum selenium in alcoholics--a consequence of liver dysfunction.

The serum concentration of selenium was decreased by 17 and 48% in non-cirrhotic and cirrhotic alcoholics, respectively, as compared to healthy controls. In these alcoholics the serum selenium correlated positively with the serum albumin and plasma prothrombin time and inversely with the serum bilirubin, alkaline phosphatase and gamma-glutamyl transpeptidase. Abstinence from ethanol for two weeks was without effect on the serum selenium level in non-cirrhotic alcoholics and acute alcohol intake did not change the serum selenium concentration in non-alcoholic volunteers. In patients with primary biliary cirrhosis the serum concentration of selenium was similar to that in the alcoholic cirrhotics. In patients with hypoalbuminaemia of renal origin the serum selenium was normal. In conclusion our results show that the deterioration of liver function, irrespective of its aetiology, leads to the decrease in serum selenium levels. Whether a defect in removal of lipoperoxides is associated with this decrease in serum selenium concentration remains to be decided by further studies.

Adult↗
PubMed1983

Inhibition of testosterone biosynthesis by ethanol. Relation to hepatic and testicular acetaldehyde, ketone bodies and cytosolic redox state in rats.

In experiments in which liver and testis freeze-stops were performed on pentobarbital-anaesthetized rats, ethanol (1.5 g/kg body wt.) reduced plasma testosterone concentration from 13.1 to 3.2 nmol/litre. 4-Methylpyrazole abolished the ethanol-induced hepatic and testicular increase in the lactate/pyruvate ratio, and the testicular acetaldehyde level, but did not diminish the reduction in plasma testosterone concentration. In testes, but not in liver, ethanol decreased the 3-hydroxybutyrate/acetoacetate ratio, and 4-methylpyrazole did not prevent this effect. In experiments in which freeze-stop was performed after cervical dislocation, ethanol decreased the testis testosterone concentration from 590 to 220 pmol per g wet wt. The effects of ethanol and 4-methylpyrazole on testis acetaldehyde, lactate/pyruvate and 3-hydroxybutyrate/acetoacetate ratios were the same as found during anaesthesia. The NAD+-dependent ethanol oxidation capacity in testis ranged from 0.1 to 0.2 mumol/min per g wet wt. and seemed to be inhibited by 4-methylpyrazole both in vivo and in vitro. In additional experiments, ethanol doses between 0.3 and 0.9 g/kg body wt. did not alter the plasma testosterone concentration in rats treated, or not treated, with cyanamide, which induced elevated acetaldehyde levels in blood and testes. The results suggest that ethanol-induced inhibition of testosterone biosynthesis was not caused by extratesticular redox increases, or by extra- or intra-testicular acetaldehyde per se. The inhibition is accompanied by changes in testicular ketone-body metabolism.

Acetaldehyde↗
PubMed1980

Hormonal changes during alcohol intoxication and withdrawal.

The endocrine effects of alcohol are briefly reviewed. Alcohol enhances glucose-induced insulin secretion and may thus cause reactive hypoglycemia. However, inappropriate insulin secretion is not the reason for alcohol-induced hypoglycemia in fasted subjects. The direct effects of alcohol in thyroid function in humans are small, although alcoholics often have low concentrations of thyroid hormones in their plasma because of liver damage. Alcohol increases cortisol secretion from adrenal cortex either by increasing ACTH secretion or, more probably, by directly stimulating the adrenals. Alcohol also increases aldosterone secretion. The production of epinephrine and norepinephrine by the adrenal medulla is increased during alcohol intoxication and withdrawal. Plasma testosterone concentration is decreased during hangover and during alcohol withdrawal. The decrease is due to direct effects of alcohol on the testes, because plasma LH concentration is increased simultaneously. Alcohol has no significant effect on the LRH-induced secretion of LH. Plasma growth hormone concentration is decreased during alcohol intoxication and increased during hangover. TRH-induced secretion of prolactin is increased during alcohol intoxication and inhibited during hangover and withdrawal. The last finding suggests that there is dopaminergic overactivity in hypothalamus during alcohol withdrawal.

Alcoholic Intoxication↗
PubMed1979

Effect of clofibrate and gemfibrozil on the activities of mitochondrial carnitine acyltransferases in rat liver. Dose--response relations.

The effects of different doses of clofibrate and gemfibrozil on liver size, serum triglyceride concentration and the activities of hepatic mitochondrial alpha-glycerophosphate dehydrogenase (alpha-GPD) and carnitine acyltransferases were studied in male rats. Both clofibrate and gemfibrozil treatment effectively decreased the fructose-induced hypertriglyceridaemia and increased the liver to body weight ratio. Clofibrate treatment also induced an increase of many times in the activities of mitochondrial alpha-GPD and carnitine acyltransferases, the effect increasing with the dose used. The effect of gemfibrozil on the activities of the enzymes was significantly smaller. There was no correlation between the decrease in serum triglyceride concentration and the changes in the activities of the enzymes. Only clofibrate increased the rate of fatty acylcarnitine oxidation in isolated mitochondria. It is concluded that both drugs increased the size of the rat liver, but that only clofibrate influenced the mitochondrial enzyme activities of mitochondrial carnitine acyltransferases and the accelerated mitochondrial oxidation of fatty acids are not the mechanisms by which these drugs lower serum lipid levels.

Acyltransferases↗
PubMed1979

Metabolic interactions of xylitol and ethanol in healthy males.

The effects of oral administration of xylitol on the rate of ethanol elimination and on the ethanol-induced changes in blood concentrations of lactate and pyruvate were studied in seven healthy male subjects. Xylitol (1.0 g/kg body weight) was administered orally and ethanol (0.8 g/kg body weight) intravenously. In the control experiments glucose was given instead of xylitol. Xylitol had no significant effect on the rate of ethanol elimination or on the ethanol-induced increase in the blood lactate concentration. The ethanol-induced changes in the lactate/pyruvate ratio were not affected by xylitol. It is suggested that the ineffectiveness of xylitol is due to its low concentration in the liver after oral administration. Ethanol induced a 5--10 fold increase in the blood concentration of xylitol. This is most probably due to inhibition of xylitol oxidation in the liver by the ethanol-induced reduction in the hepatic redox state. The clinical significance of this finding is unknown.

Adolescent↗
PubMed1978

Acute effects of alcohol on anterior pituitary secretion of the tropic hormones.

The plasma or serum concentrations of GH, TSH, LH, PRL, testosterone, cortisol, T4, and T3, and the values of the T3 uptake test were monitored in 12 healthy male volunteers for a period of 20 h after administration of one large dose of ethanol (1.5 g/kg BW). The effects of TRH and LRH on the secretion of TSH, PRL, and LH were studied in these subjects once during the period of acute alcohol intoxication (4 h after the start of drinking) and once during the hangover period (14 h after the start of drinking). Each subject served as his own control by drinking water only during another experimental session. Alcohol had no significant effect on basal concentrations of GH, TSH, LH, T4, T3, or testosterone. The concentration of cortisol in plasma was elevated during the whole 20-h period after ingestion of alcohol, as compared with the control values. Alcohol also did not significantly alter the effects of TRH and LRH on plasma TSH and LH levels at 4 and 14 h. During the hangover period, the PRL response to TRH was totally blocked, but during alcohol intoxication, there was a slight increase in the PRL response to TRH. The lack of response of PRL to TRH during the hangover suggests that withdrawal symptoms are associated with increased dopaminergic activity in the hypothalamus.

Adolescent↗
PubMed1977

Selection of multiresistant coliforms by long-term treatment of hypercholesterolaemia with neomycin.

Patients with hypercholesterolaemia are often treated with the antimicrobial agent neomycin. Such treatment is potentially dangerous, however, as it may favour the emergence of multiresistant, R-factor-carrying, enteric bacteria among the intestinal flora. In 11 out of 14 patients who had received neomycin for three months to eight years most of the faecal coliforms were resistant to at least four antimicrobial drugs and capable of transferring this resistance to others. In contrast, only one out of nine patients who were treated with other lipid-lowering drugs had resistant bacteria in their faeces. Neomycin may cause multiresistant strains to emerge because, like tetracycline, it forms high concentrations in the gut. Long-term treatment of non-infectious conditions like hypercholesterolaemia with neomycin is potentially dangerous not only to the patient but also to the community because of the creation of a reservoir of multiresistant organisms.

Drug Resistance, Microbial↗
PubMed1976

Effects of fructose and glucose on ethanol-induced metabolic changes and on the intensity of alcohol intoxication and hangover.

The effects of fructose and glucose on the metabolic changes induced by ethanol and on the intensity of alcohol intoxication and hangover were studied in 109 healthy male volunteers. After 10 hours of fasting, the subjects were given 1.75 g of ethanol per kg body wt during 3 hours under controlled laboratory conditions. Fructose or glucose were adminstered either simultaneously with ethanol or 12 hours later during the hangover period. The intensity of alcohol intoxication and hangover were estimated 10 times during the experimental period of 20 hours using subjective and objective rating scales. Sequential determinations of blood ethanol, acetaldehyde, glucose, lactate, free fatty acids, triglycerides, ketone bodies and capillary blood acid-base balance were also made during the experiment. Under these experimental conditions neither fructose nor glucose had any significant effect on the intensity of alcohol intoxication and hangover. The sugars also had no significant effect on the rate of ethanol elimination or on the blood acetaldehyde concentration during the course of the experiment. Blood glucose concentration was decreased and blood lactate, free fatty acid and ketone body concentrations were increased during the hangover period in the subjects who had been given only ethanol. These subjects also had a marked metabolic acidosis during hangover. Glucose and fructose significantly inhibited the metabolic alterations induced by ethanol. In this respect fructose was more effective than glucose. The results indicate that both fructose and glucose effectively inhibit the metabolic disturbances induced by ethanol but they do not affect the symptoms or signs of alcohol intoxication and hangover. The results support the view that hangover is not directly related to the metabolic effects of ethanol or to its metabolic products.

Acetaldehyde↗
PubMed1976

Electroencephalographic changes during experimental hangover.

The EEG was recorded in 27 subjects during hangover. Male healthy volunteers drank 1.75 g/kg body weight of ethanol in 3 h and the EEG was recorded 14-16 h later when the degree of hangover was highest. For control purposes a second EEG was recorded after a similar session when subjects drank water instead of ethanol. A third record was taken in normal laboratory conditions. T5-A1 and O1-A1 derivations were subjected to computer analysis from which spectral and frequency parameters were calculated. Visual analysis of the EEG during hangover showed a decrease and slowing of alpha activity and an increase in theta activity. Spectral analysis of the EEG gave a statistically significant increase in 7-8 c/sec activity during hangover. The EEG change could not be explained in terms of blood alcohol level, hypoglycaemia or acidosis. Also fatigue could be excluded as a cause of EEG change by means of "water controls". The conclusion is that the slowing of the EEG during hangover is caused by the depressant action of ethanol, or its metabolites, on cortical function.

Adolescent↗