Biomedical subjects

E Vara

Publications and source records attributed to E Vara.

61 records · Page 4Linked to original sources

PubMed1986

Effects of L-leucine on palmitate metabolism and insulin release by isolated islets of fed and starved rats.

The occurrence of lipid metabolic changes associated with L-leucine (10 mM) stimulation of insulin release was investigated in isolated islets from either fed or starved rats. L-Leucine-stimulated secretion was potentiated by 3 mM glucose and/or 0.5 mM palmitate and was unaffected by 48 h of starvation. Islet palmitate oxidation showed a maximum rate at 3 mM glucose, and starvation increased it almost 2-fold. Regardless of the nutritional state, L-leucine strongly reduced the oxidation of palmitate and increased its incorporation into islet triacylglycerols and phospholipids at 3 mM glucose. This shift of fatty acid metabolism toward esterification might play a role in the mechanism of potentiation of the islet secretory response to L-leucine by glucose and palmitate.

Animals↗

PubMed1985

Antigenic specificity of a new and potent somatostatin antiserum.

The specificity of a new somatostatin antiserum (Ab 6) has been investigated using eight different peptide analogues. For this purpose, somatostatin and all the analogues were tested, in an equimolar concentration range, for their ability to displace 125I-tyr1-somatostatin from its binding to antibodies. Analysis of the displacement curves shows that antiserum Ab 6 predominantly recognizes changes at the central aminoacid sequence of the somatostatin molecule. Its ligand specificity seems to be similar to that of other somatostatin antisera previously described (R-141 and A-101).

Animals↗

PubMed1984

Starvation-induced changes of palmitate metabolism and insulin secretion in isolated rat islets stimulated by glucose.

The influence of 48 h starvation on glucose-induced changes of palmitate metabolism and insulin release in isolated rat islets was investigated. (1) Islet insulin response to 20 mM-glucose was abolished after 48 h starvation, and it was restored by 0.25 mM-2-bromostearate, an inhibitor of fatty acid oxidation. (2) The increase in glucose concentration from 3 to 20 mM was accompanied by a 50% decrease in the oxidation rate of 0.5 mM-[U-14C]palmitate in control (fed) islets, and a concomitant increase (100%) in its incorporation into triacylglycerol and phospholipid fractions. (3) Starvation induced a higher basal (3 mM-glucose) rate of palmitate oxidation, which was resistant to inhibition by 20 mM-glucose. The latter also failed to increase palmitate incorporation into islet triacylglycerols and phospholipids. (4) 2-Bromostearate (0.25 mM) strongly inhibited the high oxidation rate of palmitate in islets of starved rats, and allowed a normal stimulation of its incorporation rate into islet lipids by 20mM-glucose. (5) The results suggest that starvation restricts islet esterification of fatty acids by inducing a higher rate of their oxidative degradation that is insensitive to regulation by glucose.

Animals↗

PubMed1984

Starvation-induced secretory changes of insulin, somatostatin, and glucagon and their modification by 2-bromostearate.

The hypothesis was made of an increased oxidation of fatty acids (FFA) and a decrease of their esterification rate contributing to the islet secretory defect during starvation. 2-Bromostearate (BrS), a FFA-oxidation inhibitor, was therefore tested on the islet secretion of insulin, glucagon and somatostatin stimulated by glucose or palmitate under fasted or fed conditions. Starvation for 48 h blocked both the glucose-induced stimulation and inhibition of insulin and somatostatin and the glucagon secretion. BrS completely restored the insulin response and stimulated both somatostatin and glucagon-basal release, the latter inhibition by glucose being partially recovered. Palmitate transient stimulation of insulin and somatostatin and inhibition of glucagon release was turned into a sustained increase in all three cases by addition of BrS. The potentiation by BrS of palmitate secretory effects in "fed" islets and of hormone release in "fasted" islets, apparently suggest that inhibition of FFA-oxidation may play a role in the regulation of islet secretion.

Animals↗

PubMedDate not supplied

Twenty-four hour rhythms of hypothalamic corticotropin-releasing hormone, thyrotropin-releasing hormone, growth hormone-releasing hormone and somatostatin in rats injected with Freund's adjuvant.

The effect of Freund's adjuvant injection on 24-hour variation of hypothalamic corticotropin-releasing hormone (CRH), thyrotropin-releasing hormone (TRH), GH-releasing hormone (GRH) and somatostatin levels was examined in adult rats kept under light between 0800 and 2000 h daily. Groups of rats receiving Freund's complete adjuvant or its vehicle 3 days before sacrifice were killed at six different time intervals throughout a 24-hour cycle. In the median eminence, adjuvant vehicle-injected rats exhibited significant 24-hour variations for the four hormones examined, with maxima at noon. These 24-hour rhythms were inhibited or suppressed by Freund's adjuvant injection. In the anterior hypothalamus of adjuvant vehicle-treated rats, CRH content peaked at 1600 h, while two peaks were found for TRH and GRH levels, i.e., at 2400-0400 h and 1600 h. Freund's adjuvant injection suppressed 24-hour rhythm of anterior hypothalamic CRH, TRH and GRH content and uncovered a peak in anterior hypothalamic somatostatin levels at 0400 h. In the medial hypothalamus of adjuvant vehicle-treated rats, significant 24-hour variations were detectable for TRH (peaks at 1600 and 2400 h) and somatostatin (peak at 2400 h) which disappeared after Freund's adjuvant injection. In the posterior hypothalamus of adjuvant vehicle-treated rats, two peaks were apparent for CRH, TRH and somatostatin levels, i.e. at 1600 h and 2400-0400 h, this hormonal profile remaining unmodified after Freund's adjuvant administration. The administration of the immunosuppressant drug cyclosporine (5 mg/kg, 5 days) impaired the depressing effect of Freund's adjuvant injection on CRH, TRH and somatostatin content in median eminence, but not that on GRH. In the anterior hypothalamus, cyclosporine generally prevented the effect of immunization on hormone levels an revealed a second maximum in TRH at 0400 h. Cyclosporine also restored 24-hour variations in TRH and somatostatin levels of medial hypothalamus of Freund's adjuvant-injected rats but was unable to modify them in the posterior hypothalamus. The results further support the existence of a significant effect of immune-mediated inflammatory response at an early phase after Freund's adjuvant injection on hypothalamic levels which was partially sensitive to immunosuppression by cyclosporine.

Animals↗

PubMedDate not supplied

[Prevalence of smoking, awareness and evaluation of cessation methods amongst medical students].

This work describes and analyses the prevalence of smoking amongst medical students, their awareness of the methods of smoking cessation and the effectiveness they attribute to these methods and to medical advice. A questionnaire was distributed to students of medicine at the University of Navarra with open questions on the methods of smoking cessation of which they were aware, the effectiveness attributed to each of these and the effectiveness attributed to medical advice. Information was also gathered on: sex, year of study, smoking habit, average number of cigarettes smoked per day and the length of exposure to tobacco. Of 480 valid interviews, the prevalence of active smokers was 27.5% (CI 95%: 23.5-31.9); 4.2% ex-smokers and 68.3% who had never smoked. 42.7% named nicotine patches as a method of cessation and 25.2% nicotine chewing gum. With respect to the effectiveness attributed to each method, a median and interquartile range (IQR) of 20% (0-50) for the nicotine patches, 10% (0-40) for nicotine chewing gum and 20% (1-50) for medical advice. The more senior students and those that had been smoking for longer mentioned nicotine patches more frequently; more women than men knew about nicotine chewing gum. The senior students attributed greater effectiveness to nicotine patches. A future reduction is predicted in the number of active smokers in the medical sector. Amongst medical students the effectiveness of medical advice is overestimated. It is necessary to increase awareness of the methods for smoking cessation amongst medical students.

English Abstract↗

PubMedDate not supplied

[Predictors of tobacco addiction in young adults].

To identify smoking dependence predictors, 150 active smokers were interviewed. To assess tobacco dependence Fagerström's test was used. The potential associations between smoking dependence and some variables related to life style were investigated. In a case-control study design an induction period > or = 2 months was assumed. After estimating crude odds ratios, a logistic regression model was fitted. The dependent variable was dependence to tobacco smoking. In the multivariate analysis independent predictors, in addition to age, were: a) an earlier hour for starting smoking (OR: 6.08; 95% CI: 2.29-16.2), b) thinking that smoking avoids getting fat (OR: 4.36; 95% CI: 1.50-12.7) and c) not knowing any person with smoking-related pathology (OR: 3.75; 95% CI: 1.36-10.3). Exercise appeared to protect against smoking addiction (OR: 0.36; 95% CI: 0.13-0.98). The knowledge of these factors could help to avoid the development of smoking addiction.

Adolescent↗