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Biomedical subjects

B Marin

Publications and source records attributed to B Marin.

At least 37 records · Page 2Linked to original sources
PubMed1986

Reduced ethanol consumption during cyproheptadine administration in rats from a long-term alcohol-treated colony.

The influence of cyproheptadine (CPH) on forced and voluntary ethanol intake was studied in long-term alcohol-treated rats. Wistar rats from a colony (WAC) that have been drinking alcohol as their only liquid fluid for the 25 previous generations and from a genetically related colony (WN) that had never been given alcohol were used. In the first experiment, daily IP doses of 15 mg/kg CPH were found to reduce forced ethanol consumption during CPH treatment in both WAC and WN rats which had been drinking ethanol for six months. In two additional groups of WAC and WN rats which were not given ethanol, water intake was not affected by CPH administration. In a second experiment, alcohol preference was reduced both during and after CPH, but total fluid intake (ethanol + water) was not affected. These findings suggest that the effect of CPH could be specific to ethanol. The decrease in ethanol consumption was associated with a significant body weight loss; this result may support the hypothesis of a link between the serotoninergic system, food intake, and alcohol drinking behavior that has been considered by earlier investigators.

Alcohol Drinking↗
PubMed1986

The tonoplast proton-translocating ATPase of higher plants as a third class of proton-pumps.

Taken together, all the data reported recently in the literature suggest that tonoplast ATPase belongs to a new class of proton pumps. To date, the most studied system is the proton-pumping ATPase from the tonoplast of Hevea latex. Its main characteristics are presented. It resembles the mitochondrial ATPase in its specificity, its substrate affinity, and its sensitivity to different inhibitors. However, for some aspects, it resembles the plasma membrane system in its response to other inhibitors tested (quercetin for example). It differs from both ATPases in its sensitivity to nitrate as well as by its molecular structure, i.e. a complex exhibiting a least 4 or 5 polypeptides. These results favor the existence of a third class of proton pumps, intermediate between the F1F0-class and the E1E2-class.

Adenosine Triphosphate↗
PubMed1985

Solubilization and purification of the ATPase from the tonoplast of Hevea.

The tonoplast-bound ATPase of Hevea brasiliensis (caoutchouc tree) was solubilized with dichloromethan and purified 100-fold with two ammonium sulfate precipitation steps and a G-200 gel filtration step. The resulting ATPase activity eluted according to a molecular mass of approximately 200 kDa and chromatographed at an isoelectric pH of 5.3. Subunits of molecular mass 110 kDa, 68 kDa, 24 kDa and 12 kDa appeared after treatment with 1% sodium dodecyl sulfate or spontaneously during storage of the solubilized ATPase. Dodecyl sulfate/polyacrylamide gel electrophoresis yielded four polypeptides of molecular mass 54 kDa, 66 kDa, 23 kDa and 13 kDa. From protein determination by ultraviolet absorption and Coomassie stain it appears that the 54-kDa and the 66-kDa polypeptides exist in multiple copies. No close resemblance to the membrane-bound ATPase of mitochondria, plastids, plasmalemma, chromaffin granules and synaptic vesicles is seen. No antibody cross-reaction to F1 of bacteria is observed. Therefore it is concluded that the vacuolar ATPase represents a novel type of ATPase. Many properties of the tonoplast-bound ATPase such as pH-dependence, substrate specificity, ion-dependence and inhibitor sensitivity did not change when the enzyme had been solubilized and purified. The phosphatase activity was lost during the purification procedure. The stimulation of ATP-hydrolysis in tonoplast vesicles by uncouplers and ionophores was absent in the solubilized ATPase, and also the stimulation by chloride was significantly reduced. Anion channel blockers, such as triphenyltin and 4,4'-diisothiocyano-2,2'-disulfonic acid stilbene, which are strong inhibitors of membrane-bound ATPase, fully or partly lost their inhibiting effect after solubilization of the ATPase. These results are interpreted to indicate that ionophores do not directly affect the ATPase molecule, whereas chloride might have a small direct effect on the ATPase besides its effect as a permeating anion.

Adenosine Triphosphatases↗
PubMed1985

Sex differences in the effect of extirpation of the submandibular salivary glands in rats.

Because of the known interaction between the endocrine system and the structure and function of submandibular glands, the effects 3 months after extirpation of these glands in male and female rats were studied including the following parameters: change of body weight, sexual maturity (in females), sexual behaviour (in males), blood sugar, total proteins, haematocrit, the weight of various glands and oxygen uptake of various cerebral and glandular structures. The response in the two sexes was in each case different.

Animals↗
PubMed1985

Effects of low stress during pregnancy on certain parameters of the offspring.

In recent years the effect of intense stress applied during pregnancy has been studied. In this work, we exposed the mother to low immobilization stress throughout the entire pregnancy. This treatment that increased the sexual capacity in males had no detectable effects on the reproductive behavior of females. A positive role of this phenomenon in nature is suggested, as the offspring of stressed mothers would be more capable of facing difficult and selective environments.

Animals↗
PubMed1983

Sensitivity of tonoplast-bound adenosine-triphosphatase from hevea to inhibitors.

The tonoplast-bound H(+)-translocating ATPase from Hevea latex was found to be insensitive to vanadate, diethylstilbestrol, and octylguanidine, which are specific inhibitors of the plasma membrane ATPase. The inhibitors of the mitochondrial ATPase, oligomycin and azide, and also rotenone and antimycin A, were all without effect. In contrast, trimethyltin chloride strongly inhibited the activity of Hevea tonoplast ATPase.Among the different carbodiimides tested, which strongly inhibit the Hevea tonoplast ATPase, N,N'-dicyclohexylcarbodiimide was the most inhibitory. N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline was also an efficient inhibitor.This unique inhibitor sensitivity of the Hevea tonoplast H(+)-translocating ATPase suggests that this enzyme differs in its mode of operation from all other known H(+)-translocating ATPases.

Journal Article↗
PubMed1981

The protonmotive potential difference across the vacuo-lysosomal membrane of Hevea brasiliensis (rubber tree) and its modification by a membrane-bound adenosine triphosphatase.

The vacuo-lysosomes of Hevea brasiliensis (rubber tree) constitute a suitable model system for the study of active transport and energization at the level of the membrane of plant vacuoles. The pH gradient (delta pH) and the membrane potential (delta psi) of vacuo-lysosomes were determined by means of the weak base methylamine and the lipophilic cation tetraphenylphosphonium. The values obtained depended strongly on the experimental conditions such as medium pH or K+ concentration. Under experimental conditions, i.e., pH 7.5 outside and low K+, the delta pH amounts to about 0.9 unit, interior acid, and the delta psi to -120 mV, interior negative. The delta psi is presumably caused by the imposed K+ gradient, and the internal acidification might be a consequence of the passive proton inflow along the electric field. This explanation is sustained by the ineffectiveness of carbonyl cyanide p-trifluoromethoxyphenylhydrazone in destroying the delta pH and delta psi, whereas higher K+ concentration decreased both. Under conditions existing in vivo, the membrane potential might be significantly lower. The presence of ATP increased the acidification of the intravesicular space by 0.5pH unit to a delta pH of up to 1.4 and shifts the membrane potential at least 60mV to a more positive value. The change of the protonmotive potential did not occur with ADP; the pH-dependence of the change was identical with the pH-dependence of a vacuo-lysosomal membrane-bound ATPase, and the effect of ATPase was prevented by the presence of the uncoupler carbonyl cyanide p-trifluoromethoxyphenylhydrazone. The change of protonmotive potential difference, brought about by the ATPase, was at least 90 mV. This is evidence that a vacuo-lysosomal ATPase in plants can function as an electrogenic proton pump that transfers protons into the vacuo-lysosomal space.

Adenosine Triphosphatases↗
PubMed1981

Use of resident physicians: an evaluation of the effects of a significant increase.

Medical school graduates have become increasingly dependent on former community hospitals for residency programs because charitable institutions attached to medical schools are disappearing. It is not known what impact residencies have on hospitals that were community hospitals. We interviewed private practice physicians, residents, nurses, patients, and other groups in a large former community hospital. Overall, the interviews indicated good support for the hospital's new teaching function. Furthermore, the residents were viewed in very favorable terms by all groups. There were two problem areas. One, some residents seem less sensitive to human relations than private practice physicians and other hospital groups. Two, many private practice physicians are concerned over the number of hospital-salaried physicians and the outpatient care offered by residents supervised by hospital-salaried physicians. This research suggested several recommendations that, if followed, would serve to increase the value of the residency in meeting patient needs in the most effective manner.

Evaluation Studies as Topic↗
PubMed1979

Effects of ovariectomy on the oxidative metabolism of the central nervous system and adrenal glands in female hamster (Mesocricetus auratus).

We have studied the influence of ovariectomy on the oxidative activity of hypophysis, hypothalamus, posterior cortex, septal area, amygdala and adrenal glands, in female hamsters, because their neuroendocrine behavior seems to differ from that of rats. Our results show a decreasing the O2 uptake in the hypothalamus and adrenal glands and an increase in the rest of the structures.

Adrenal Glands↗