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Biomedical subjects

M Manin

Publications and source records attributed to M Manin.

32 records · Page 2Linked to original sources
PubMed1988

Chronic intracerebroventricular infusion of insulin failed to alter brain insulin-binding sites, food intake, and body weight.

The present study was performed to explore the role of exogenous insulin in CSF in the control of energy balance in the rat. For this purpose, adult male Sprague-Dawley rats carrying an indwelling cannula in the right lateral cerebral ventricle were infused for a maximum of 10 days with insulin (Actrapid) at various rates (starting at 0, 45, 85, 170, and 600 ng/day) or anti-insulin antibody (IgG fraction; diluted 1:10 wt/vol) with an osmotic minipump. All those treatments did not modify the growing rates; neither total daily food intake nor the circadian rhythm of food intake was further modified. The chronic insulin infusion starting at 600 ng/day resulted in a chronic significant increase in CSF insulin levels without changing the plasma insulin level. It failed to alter specific insulin binding sites to Triton X-100 solubilized microsomal membranes from various brain areas (cerebral cortex, olfactory bulbs, and lateral and medial hypothalami) at the end of the 5- or 10-day period of insulin infusion. Purification of insulin receptors on a wheat germ agglutinin did not reveal any further effect of insulin. From these results, it seems unlikely that the input to the brain insulin-effector systems could arise from CSF insulin.

Animals↗
PubMed1987

The influence of acute hyperinsulinemia on the insulin-related material in brain, testis, liver, and kidney.

Insulin-related material was measured in acid ethanol extracts of brain, testis, liver, and kidney from adult rats acutely injected with insulin or saline. Insulin injection resulted in a twofold to threefold increase in plasma insulin during a two-hour period after injection. Plasma glucose was greatly depressed. Insulin injection had no effect on the insulin-related material in most areas of brain (cerebral cortex, olfactory bulbs, and medial hypothalamus) and the cerebrospinal fluid; lateral hypothalamus was an exception and paradoxically exhibited a decrease of this material. The testis insulin-related material was unaffected; purification of the testis extracts using the C18 Sep pak method revealed no further difference between the animals. In liver, the insulin-related material was not significantly different in the control and the insulin-injected group; however, we found a significant correlation between this material and plasma insulin within the insulin-injected group. In contrast, insulin injection resulted in an important increase in kidney insulin-related material that paralleled the change in plasma insulin. Thus, like chronic experiments, acute hyperinsulinemia revealed that the insulin-related material was largely independent from blood insulin in tissues that exhibit very different insulin uptake from the blood; kidney appeared to be an exception.

Animals↗
PubMed1986

[Hormonal control of hepatic metabolism in ruminants].

Insulin/glucagon control of hepatic metabolism, i.e. a endocrine-nervous system, is one of the general systems of integration in vertebrates. In this system, substrates coming from the digestive tract or from extrahepatic metabolism are important messenger molecules. Liver uptake of insulin and glucagon mainly accounts for high metabolic clearance rates of these hormones in both ruminants and non-ruminants. Glucagon infusion into ruminants results in an increase in the net hepatic uptake of glucose precursors and gluconeogenesis. Glucagon effects have also been demonstrated in isolated hepatocytes. Glucagon, through its effect on pyruvate carboxylase (EC 6.4.1.1.) may regulate gluconeogenesis. Insulin infusion induces hypoglycaemia. As a result, glucagon secretion increases and counterregulates insulin action. However, it has been shown that hepatic gluconeogenesis decreases during euglycaemic hyperinsulin clamp, mainly due to a decrease in the hepatic supply of glucose precursors following insulin action in extrahepatic tissues. Insulin fails to elicit any significant effect in vitro. Hepatocytes exhibit insulin and glucagon receptors. The apparent characteristics of hormone binding in vitro are similar in ruminants and non-ruminants, but the characteristics of postreceptor events are unknown in the former. Glucagon, which influences hepatic glucose synthesis, may be a major hormone in ruminants.

Amino Acids↗
PubMed1984

Dynamic measure of production rate of cortisol in the mature guinea-pig in response to the stress of anesthesia: effect of estradiol.

The effect of estradiol on adrenal secretion rate of cortisol in response to a stress induced by anesthesia, was examined by comparing the metabolic clearance rate and the production rate of cortisol between males and females and after estradiol administration in castrated animals. Metabolic clearance rates of cortisol (MCR) were significantly higher (+30%) in males than in females. Castration lowered the MCR of cortisol in males and had no significant effect in females. After estradiol administration, a fall in the MCR of cortisol concomitant with a rise in blood cortisol level was observed especially in males in which the effect of treatment was more marked than in females and highly significant. The production rate of cortisol was identical in males and females and was slightly increased in estradiol-treated males and females. The data indicate that estradiol had an inhibitory effect on metabolic clearance of cortisol, which caused an important rise of blood cortisol levels in response to stress and which prevented an increase in the adrenal response to the stress. Since the pituitary adrenal cortex can respond in a normal way to stress, the low value of MCR of cortisol could be the limiting factor in the adrenal secretion rate of cortisol in estrogen-treated guinea-pigs.

Adrenal Glands↗
PubMed1983

The splanchnic removal of cortisol from plasma of anaesthetized adult guinea-pigs.

To evaluate the role of the liver in cortisol catabolism the extraction ratio of both cortisol and cortisone by the organs of the splanchnic area was estimated in guinea-pigs anaesthetized with pentobarbitone. The [3H]cortisol and [3H]cortisone concentrations were measured in portal and sus hepatic venous plasma during a constant infusion of [3H]cortisol or [3H]cortisone. The extraction ratio of cortisol was estimated to be 10-14% in the splanchnic area and the viscera, while in the liver it had a small negative value suggesting that the liver had produced as much or more cortisol than it had taken up. All the cortisone (95%) formed from cortisol in the viscera was eliminated from the plasma compartment by the liver. Some 75-80% of the infused cortisone was converted to cortisol; rather less of the infused cortisol was converted to cortisone (32%). Using estimates of plasma flow derived from sham-operated animals, the uptake of cortisol by the various organs was calculated. The splanchnic area extracted 41% of the infused cortisol from the plasma: 25-27% as cortisol and 13-16% as cortisone. The liver appeared to take up cortisone preferentially. The conversion of cortisone into cortisol within the liver seems to be important in limiting the amount of cortisol removed from the plasma by the splanchnic area. The liver is also important in inactivating the steroids although other sites are probably also involved.

Animals↗
PubMed1982

Measurement of the rate of secretion, peripheral metabolism and interconversion of cortisol and cortisone in adult conscious male guinea-pigs.

Metabolism of the cortisol (F) and the cortisone (E) was studied by continuous infusion of [14C]-F and [3H]-E in adult conscious male guinea-pigs. Parameters, calculated from the specific activities of F and E, are expressed in mumoles/24 h : production rate of F (PRF) = 8 +/- 1 and E (PRE) = 4.9 +/- 0.7 ; secretion rate of F (QF) = 7.1 +/- 0.9 and E (QE) = 0.9 +/- 0.4 ; rate of irreversible metabolism of F (rF) = 6.2 +/- 0.9 and E (rE) = 1.8 +/- 0.3 ; percentage of transfer of F into E = 59 +/- 4% and E into F = 80 +/- 3%. These results demonstrate that adrenal gland in the adult male guinea-pig secretes essentially cortisol and little or no cortisone. Practically all the pool of E is derived from transformation of F into E ; the major part of E production is reconverted into F.

Animals↗
PubMed1981

Effects of acute neurotrophic stress on peripheral metabolism of cortisol in conscious male guinea-pigs.

Cortisol metabolism was studied in conscious adult male guinea-pigs subjected to a neurotrophic stress (immobilization and stimulation by light for 3 h). The disappearance curves of tracer quantities of [3H]cortisol were represented by a two-pool model. In stressed animals, there was marked increase in the mean plasma level of cortisol (184% of control value; P less than 0.001) and in the metabolic clearance rate (MCR; 17% of control value; 0.001 less than P less than 0.001). This rise in the MRC of plasma cortisol resulted from an increase in the mean total apparent volume of distribution (49%, P less than 0.001). The lack of significant differences in the slopes of the second exponential phase of the disappearance curves indicated that the stress did not significantly increase the half-lie of cortisol. The mean binding capacity of transcortin for cortisol (ST) was significantly higher in the animals which had been subjected to the neurotrophic stress than in the control guinea-pigs (0.02 less than P less than 0.05). However, ST values remained very low and accounted for the very high levels of free cortisol found after the stress. The results suggest that the raised concentrations of unbound cortisol found in the plasma of conscious adult male guinea-pigs in response to neurotrophic stress reflect a hypersecretion of corticosteroid.

Animals↗
PubMed1980

Influence of dexamethasone on peripheral metabolic parameters of cortisol in the adult male conscious guinea-pig.

The influence of dexamethasone on distribution, metabolism and protein binding of cortisol was studied in conscious adult male guinea-pigs, under chronic cannulation, by a single injection technique for cortisol metabolic parameters and Sephadex equilibrium dialysis procedure for protein binding. The results showed that biological half-life of cortisol (51-55 min) was identical in control and in dexamethasone-treated guinea-pigs (low plasma cortisol level). The apparent volume of distribution of cortisol, which was higher in control (550 +/- 20 ml) than in dexamethasone-treated animals (380 +/- 30 ml), was related to the higher plasma cortisol level in controls (0.96 +/- 0.07 mumole/l) as compared to dexamethasone-treated animals (0.12 +/- 0.02 mole/l). When a high cortisol concentration was infused in dexamethasone-treated guinea-pigs in order to produce hig plasma cortisol level, plasma cortisol MCR increased by 80% (P less than 0.001) reflecting increases of 50% (P less than 0.001) in the apparent volume of distribution and decreases of 19% (0.01 less than P less 0.02) in the half-life cortisol compared to dexamethasone-treated animals (low plasma cortisol level). Although the plasma cortisol level was higher (P less than 0.001) in dexamethasone-treated animals infused with non-labelled cortisol (2.9 +/- 0.02 mumol/l) than in controls (0.96 +/- 0.07 mumol/l), the identical values of the apparent volume of distribution in dexamethasone-treated animals infused with non-labelled cortisol and in controls suggested that dexamethasone could alter the distribution of cortisol, and therefore its metabolism. Dexamethasone did not modify the transcortin-binding capacity and did not complete with cortisol on transcortin sites in guinea-pig plasma.

Animals↗
PubMed1978

[Relationship between cortisol metabolic clearance rate and cortisol concentrations in adult male dexamethasone treated guinea-pigs (author's transl)].

Continuous infusion of increasing unlabelled cortisol concentrations and tritiated cortisol was used to state precisely the relation between metabolic clearance rate of cortisol (MCR) and blood cortisol levels, on conscious male adult guinea-pigs under chronic cannulation and treated by dexamethasone. The MCR of cortisol depends on blood cortisol levels : constant for low values of cortisol concentrations (5 and 20 micrograms/100 ml), it rises 50 % between 20 and 50 micrograms/100 ml : from cortisol levels of 50 to 300 micrograms/100 ml, it reaches a maximala and constant value.

Animals↗
PubMedDate not supplied

Metabolic clearance of insulin from the cerebrospinal fluid in the anesthetized rat.

Infusion of 125I-(Tyr A14)-insulin at tracer doses into the cerebrospinal fluid (CSF) resulted in a slow rate of increase in the CSF-labeled insulin during the first 2 hours with a plateau thereafter. Labeled insulin was cleared from the CSF at a higher rate than 3H-inulin, a marker of CSF bulk flow. The labeled insulin was mainly distributed in all the ventricular and periventricular brain regions. Small amounts of degraded insulin appeared in the CSF. Coinfusion with an excess of unlabeled insulin impaired the clearance and degradation of labeled insulin. It also inhibited the labeling in medial hypothalamus, olfactory bulbs and brain stem. In contrast, coinfusion of ribonuclease B (used to test the specificity of uptake) was without any effect. It was concluded that there is an active insulin intake from CSF into brain specific compartments that is presumably essential for the effects of insulin on brain function.

Anesthesia↗
PubMedDate not supplied

Acquisition of androgen-mediated expression of mouse vas deferens protein (MVDP) gene in cultured epithelial cells and in vas deferens during postnatal development.

We used cultured vas deferens epithelial cells (VDECs) as a model system to determine the conditions that allow mouse vas deferens protein (MVDP) gene expression and acquisition of androgen responsiveness. On the basis of Northern blot analysis, the mvdp gene is constitutively expressed at very low levels in prepubertal VDECs grown on collagen-coated plastic or on microporous membrane inserts. In the presence of dihydrotestosterone (DHT), mvdp messenger RNA levels dramatically increased in cells cultured on microporous membrane inserts and stayed unchanged in cells grown on matrix-coated plastic. Epithelial cells derived from fetal vas deferens were able to synthesize MVDP in response to DHT, and the presence of fetal mesenchymal cells did not influence MVDP production. Providing the cells with a culture procedure that permits access to the basolateral membranes and caters to the polarity requirements of the cell is a prerequisite for androgen induction of MVDP gene expression. The results also point to a role for epidermal growth factor, insulin, and tyrosine kinase activity in mediating the action of androgen on mvdp gene expression. In vivo studies show that the first expression of the mvdp gene between 5 and 7 days postpartum is not associated with major structural changes in the epithelium. The acquisition of a mature phenotype by epithelial and peritubular contractile cells, between 10 and 20 days, correlates with androgen dependency of the mvdp gene. We propose that cell differentiation and polarization on a matrix-coated microporous membrane reproduces some of the events that are necessary for acquisition of androgenic responsiveness of the mvdp gene during postnatal development.

3T3 Cells↗
PubMedDate not supplied

[Three therapeutic recipes from the pages of the baptismal record book of the Kastel Parish in Istria].

In Croatian archives a rich collection of registers is preserved. Among the oldest and best-conserved collections of such valuable sources in Europe, are those from the territory of Istria. Investigating these sources we focused our attention on three recipes for treatment of calculi and cuts found on pages of Kastel baptismal's record (1749-1815) in Istria. Similar to other recipes found in various other recipe collections they mirror interlace of folk experience and theurgical views of healing which was detected unexpectedly sometimes on unconventional places, have survived on Croatian territory throughout centuries.

Croatia↗
PubMedDate not supplied

Mouse seminal vesicle secretory protein of 99 amino acids (MSVSP99): characterization and hormonal and developmental regulation.

Polyclonal antibodies have been generated to investigate the localization, tissue and species distribution, androgen regulation, and ontogeny of a protein secreted by mouse seminal vesicle, designated as MSVSP99 (ie, mouse seminal vesicle secretory protein of 99 amino acids). MSVSP99 is a polymorphic compound with a molecular weight of around 14 kilodaltons and a positive immunoreactivity range of 5.23 to 5.70. Positive immunoreactivity was restricted to the epithelial cells of the seminal vesicle. Western blot analysis showed organ specificity for MSVSP99, which could not be detected in several organs in the mouse. Time course decrease of MSVSP99 after castration closely followed that of its mRNA. In contrast, the length of time required to restore control levels after testosterone treatment was higher for the protein than it was for its mRNA. Whereas the MSVSP99 gene is already active in 10-day-old males, MSVSP99 is first detected at 27 days. Then, we conclude that factors other than the accumulation of the mRNA regulate MSVSP99 expression.

Amino Acid Sequence↗