Search PubMed⌕ Search

Biomedical subjects

E Mezey

Publications and source records attributed to E Mezey.

At least 163 records · Page 9Linked to original sources
PubMed1986

Demonstration of the vasopressin associated glycopeptide in the brain and peripheral tissues of the Brattleboro rat.

An antibody that recognizes the C-terminal portion of the vasopressin precursor was used to visualize this peptide (CPP) in the brain and peripheral tissues of the Brattleboro rat. CPP-immunoreactivity was detected in adrenal medullary cells and in Leydig and Sertoli cells of the testis. In addition, CPP positive cells were found in the supraoptic and paraventricular hypothalamic nuclei of colchicine treated and adrenalectomized rats. These results suggest that Brattleboro rats may make a small amount of normal vasopressin precursor.

Adrenal Medulla↗
PubMed1986

Vasopressin and oxytocin mRNAs in adrenalectomized and Brattleboro rats: analysis by quantitative in situ hybridization histochemistry.

35S-labeled synthetic oligodeoxyribonucleotide probes were used to measure levels of vasopressin (VP) and oxytocin (OT) mRNAs in rat hypothalamus by quantitative in situ hybridization histochemistry (ISHH). VP and OT mRNA-containing cells were seen in the paraventricular (PVN) and supraoptic (SON) nuclei. VP mRNA was found to increase five-fold in the parvocellular region of the PVN after adrenalectomy while no changes occurred in magnocellular VP or OT mRNA levels. In the Brattleboro rat, VP mRNA levels were decreased and OT mRNA levels increased in the magnocellular regions. RNA species containing the VP introns were present at one fortieth of the level of processed VP mRNA in control rats. We also performed ISHH followed by immunohistochemistry on the same sections. We found that VP and its encoding mRNA were always located together as were OT-neurophysin and its encoding mRNA. In this study, we extend previous work by showing the characteristic distributions in the PVN and SON of VP and OT mRNA-containing cells and by measuring neuropeptide mRNA changes.

Animals↗
PubMed1986

Effect of glucagon on alcohol dehydrogenase activity in rat hepatocyte culture.

The effect of glucagon on the activity of alcohol dehydrogenase in rat hepatocyte culture was determined. Glucagon concentrations of 0.1 nM enhanced, whereas concentrations greater than 1 nM decreased, alcohol dehydrogenase. These effects became apparent after exposure of the cultures to glucagon for 4 or more days. The presence of corticosterone (1 microM) prevented the enhancing effect of 0.1 nM glucagon on alcohol dehydrogenase activity. The changes in alcohol dehydrogenase caused by glucagon were associated with parallel changes in the rate of ethanol elimination. Alcohol dehydrogenase appears to be rate-limiting for ethanol oxidation, as uncoupling of oxidative phosphorylation did not modify the rate of ethanol elimination. These studies suggest a physiologic role of glucagon in enhancing liver alcohol dehydrogenase activity, whereas higher pharmacologic concentrations of glucagon have an opposite, depressant effect.

Alcohol Dehydrogenase↗
PubMed1986

Role of cholecystokinin in corticotropin release: coexistence with vasopressin and corticotropin-releasing factor in cells of the rat hypothalamic paraventricular nucleus.

Cholecystokinin-8 (CCK8)-containing cell bodies in the parvocellular region of the rat paraventricular nucleus (PVN) contain vasopressin and corticotropin-releasing factor (CRF). The CCK8 and vasopressin in these cells can readily be visualized in adrenalectomized, but not in shamoperated animals. Furthermore, CCK8 levels as measured by RIA change in the PVN and in the median eminence in response to adrenalectomy. CCK8 has a stimulatory effect on corticotropin (ACTH) release from primary cultures of the anterior pituitary. This stimulation is additive with that produced by vasopressin; CCK8 plus vasopressin have an effect as great as CRF in stimulating ACTH release. Our results suggest that CCK8 may participate in the regulation of ACTH release under certain physiological conditions.

Adrenalectomy↗
PubMed1986

Changes in plasma amino acids during sobriety in alcoholic patients with and without liver disease.

Plasma amino acid profiles of alcoholic subjects without clinically apparent liver disease, alcoholic patients with biopsy-proven alcoholic hepatitis, and nonalcoholic controls were compared. Differences in the plasma aminograms of alcoholic subjects with and without liver disease appear to be due predominantly to differences in liver function whereas differences in plasma amino acid levels between the alcoholic subjects and nonalcoholic controls may be related to inadequate dietary-protein intake and pyridoxine deficiency in the alcoholic groups.

Alcoholism↗
PubMed1986

Effect of acute alcohol administration on erythrocyte aldehyde dehydrogenase activity in man.

The acute oral administration of ethanol to normal subjects resulted in an increase in erythrocyte aldehyde dehydrogenase activity. Incubation of blood with ethanol at 37 degrees C for 2 hr also increased the enzyme activity. By contrast, addition of ethanol directly to the enzyme after its partial purification had no effect on the enzyme activity. The increase in erythrocyte aldehyde dehydrogenase activity following acute ethanol administration is directly opposite to the effect of chronic ethanol consumption in decreasing the enzyme activity in alcoholics. The mechanism for this effect is unknown but may be related to alterations in the erythrocyte membrane and its interaction with the enzyme.

Adult↗
PubMed1986

Vasoactive intestinal polypeptide immunopositive neurons in the paraventricular nucleus of homozygous Brattleboro rats.

Colchicine treatment reveals a population of vasoactive intestinal polypeptide (VIP) positive cell bodies in the hypothalamic paraventricular nucleus (PVN) of the vasopressin-deficient Brattleboro rat. These immunoreactive perikarya in the PVN cannot be detected in colchicine-treated Long-Evans animals. When Brattleboro rats are administered vasopressin, there is a significant decrease in the number of VIP-immunopositive cell bodies in the PVN. Evidently, an alteration in the synthesis and/or release of VIP occurs in the absence of the antidiuretic hormone.

Animals↗
PubMed1986

Serotonin-containing elements of the rat pituitary intermediate lobe.

The source and location of serotonin in the intermediate lobe of the rat pituitary were determined by high performance liquid chromatography and immunohistochemistry. Serotonin is present in the intermediate lobe in nerve fibers and terminals, in mast cells and in elements in the blood circulating in vessels on the surface of the lobe.

Animals↗
PubMed1986

Tyrosine hydroxylase in magnocellular neurosecretory neurons. Response to physiological manipulations.

Tyrosine hydroxylase (TH) immunoreactivity is present in a few magnocellular neurons in the supraoptic and paraventricular nuclei of normal Sprague-Dawley and heterozygous Brattleboro rats. Manipulations commonly used to enhance immunostaining of cell bodies, such as colchicine treatment or lesioning of efferent fibers, induced only a slight increase in TH of magnocellular neurons in Sprague-Dawley rats. Seven days after bilateral midbrain transections, which destroyed ascending afferents to paraventricular and supraoptic nuclei from the lower brainstem, there was a substantial increase in TH immunoreactivity in magnocellular neurons. The lesions resulted in a marked increase in the intensity of the staining and in the number of stained cells. Similar increases were induced by giving animals 2% NaCl to drink for 5 days. Neurons in the supraoptic and paraventricular nuclei of homozygous Brattleboro rats show markedly more TH staining than those of normal rats. Vasopressin treatment lowered TH immunoreactivity in magnocellular neurons of Brattleboro rats to normal levels. These observations suggest that extracellular factors, probably afferent inputs, regulate the level of TH immunoreactivity in magnocellular neurons.

Afferent Pathways↗
PubMed1985

Topographical distribution of pro-opiomelanocortin-derived peptides (ACTH/beta-END/alpha-MSH) in the rat median eminence.

The detailed distribution of adrenocorticotropin (ACTH), beta-endorphin (beta-END) and alpha-melanotropin (alpha-MSH) immunoreactivity was examined in the rat median eminence (ME) and pituitary stalk using light microscopic immunocytochemistry and radioimmunoassay (RIA). Nerve fibers and varicosities immunoreactive for ACTH/beta-END/alpha-MSH had identical distributions in the ME suggesting that they are part of the same arcuate proopiomelanocortin neuronal (POMC) system. The quantitative image analysis of POMC immunoreactive varicosities in the ME indicates no significant differences between the various rostro-caudal segments. In the main (preinfundibular) portion of the ME, a moderate density of immunoreactive elements was located in the lateral part of the internal zone and throughout the postinfundibular ME. Very few scattered varicosities were observed in the neurohemal (external) zone and in the pituitary stalk. By RIA, alpha-MSH is present in a substantially higher concentration than ACTH and beta-END throughout the ME. Knife cuts between the arcuate nucleus and ME indicate that proopiomelanocortin (POMC) fibers enter the ME in its whole rostro-caudal extent. Thus POMC neurons seem to provide innervation of structures in the internal zone but not in the neurohemal/external/zone where the portal capillary system is located. Moreover, the observation that the density of immunoreactive elements is substantially lower in the pituitary stalk than in the ME, suggests that the majority of immunoreactive fibers in the internal zone are not fibers of passage directed towards the neurohypophysis.

Adrenocorticotropic Hormone↗
PubMed1985

Distribution of the pro-opiomelanocortin derived peptides, adrenocorticotrope hormone, alpha-melanocyte-stimulating hormone and beta-endorphin (ACTH, alpha-MSH, beta-END) in the rat hypothalamus.

Rat hypothalamic nuclei were removed and assayed for adrenocorticotropic hormone (ACTH), beta-endorphin (beta-END) and alpha-melanocyte-stimulating hormone (alpha-MSH) content by radioimmunoassay, from the same samples. We also performed immunostaining for these 3 pro-opiomelanocortin (POMC) derived peptides on paraffin embedded serial sections of the hypothalamus. Areas known to project to the external zone of the median eminence receive a dense POMC innervation while those projecting to the posterior pituitary are not innervated. In addition, hypothalamic areas previously suggested to project to medullary autonomic centers are densely innervated. This innervation pattern may provide the morphological basis for the involvement of POMC peptides in neuroendocrine and autonomic functions. The biochemical data raise the possibility that the POMC precursor is processed differently in various brain regions.

Adrenocorticotropic Hormone↗
PubMed1985

Effect of castration on the turnover of rat liver alcohol dehydrogenase.

Castration increased liver alcohol dehydrogenase activity and enzyme protein in male rats. The turnover of alcohol dehydrogenase determined from the decline in radioactivity present in immunoprecipitated enzyme after injection of NaH14CO3 was decreased after castration. The fractional rate of degradation (Kd) for the enzyme was 0.11 . day-1 in the castrated as compared with 0.13 . day-1 in the control animals (P less than 0.05). The fractional rate of synthesis (Ks) of the enzyme was not affected by castration, while the absolute rate of synthesis was increased slightly. This study shows that a decrease in the rate of degradation is the principal cause for the increase in liver alcohol dehydrogenase following castration.

Alcohol Dehydrogenase↗
PubMed1985

Serum gamma-glutamyl transpeptidase and chronic alcoholism. Influence of alcohol ingestion and liver disease.

Serum gamma-glutamyl transpeptidase was determined in 123 alcoholic patients and found elevated in all patients with liver disease but in only 52% of patients without significant liver disease. In patients without clinically obvious liver disease, the elevations were two to three times the upper limit of normal and decreased to normal in 80% of patients, eight weeks after abstinence. By contrast, in patients with liver disease, the elevations of serum gamma-glutamyl transpeptidase were of the order of eight to 10 times above normal and persisted at these high levels following eight weeks of abstinence. The degree of abnormality of the serum enzyme did not correlate with the daily amount of alcohol ingested or with the total length of time of alcohol consumption in these alcoholic patients. This study shows that serum gamma-glutamyl transpeptidase is persistently elevated in patients with clinically obvious liver injury, but only in 22% of chronic alcoholics without significant liver disease.

Adult↗
PubMed1985

Vasoactive intestinal peptide-containing neurons in the paraventricular nucleus may participate in regulating prolactin secretion.

Vasoactive intestinal polypeptide (VIP) immunoreactivity is present in varicosities and fibers in the hypothalamic paraventricular nucleus (PVN) in normal control animals. Adrenalectomy and lactation combined with colchicine treatment results in the appearance of a large population of VIP-immunopositive cell bodies in the parvocellular part of the PVN. Adrenalectomy, as well as lactation, significantly increases the number of VIP-positive fibers in the external zone of the median eminence. These observations suggest that the VIP-immunopositive neurons in the PVN may participate in regulating prolactin and corticotropin secretion.

Adrenalectomy↗
PubMed1985

Immunochemical characterization of carboxypeptidase B-like peptide-hormone-processing enzyme.

Specific rabbit antisera against purified bovine pituitary carboxypeptidase processing enzyme (which has also been referred to as "enkephalin convertase") have been prepared and characterized. The antisera recognized both the purified soluble and the membrane-bound forms of the enzyme with equal affinity, suggesting that these two forms of the enzyme may possess many regions of structural homology. Since the antisera did not crossreact with carboxypeptidases B, N, A, Y, and P, the carboxypeptidase processing enzyme may be a structurally distinct form of carboxypeptidase. Carboxypeptidase immunostaining, as seen by light microscopy, was found throughout the rat brain and in bovine adrenal medulla, reflecting the widespread distribution of neuropeptides. Electron microscopic immunocytochemistry of rat paraventricular nucleus and other brain areas showed that the enzyme was present in some dendrites and nerve terminals, which contain storage vesicles. These findings support the hypothesis that this carboxypeptidase is involved in the processing of many peptide hormone precursors.

Adrenal Medulla↗
PubMed1985

Metabolic effects of alcohol.

The metabolic effects of ethanol are due to a direct action of ethanol or its metabolites, changes in the redox state occurring during its metabolism, and modifications of the effects of ethanol by nutritional factors. Ethanol causes hyperglycemia or hypoglycemia depending on whether glycogen stores are adequate, inhibits protein synthesis, and results in fatty liver and in elevations in serum triglyceride levels. Increases in high-density lipoprotein cholesterol after ethanol ingestion may explain the lower risk of myocardial infarction and death from coronary disease after moderate drinking. Increases in serum lactate, resulting from the increased NADH/NAD+ ratio, and hyperuricemia, most likely the result of increased turnover of adenine nucleotides, are common transient effects of ethanol ingestion. Causes of vitamin deficiencies in alcoholism are decreased dietary intake, decreased intestinal absorption, and alterations in vitamin metabolism. Ethanol decreases thiamine absorption and decreases the enterohepatic circulation of folate. Acetaldehyde increases the degradation of pyridoxal 5'-phosphate by displacing it from its binding protein and making it susceptible to hydrolysis by membrane-bound alkaline phosphatase. Ethanol decreases hepatic vitamin A concentration and its conversion to active retinal, and modifies renal metabolism of vitamin D.

Amino Acids↗