Effect of age on the response of blood lipids, body composition, and aerobic power to physical conditioning and deconditioning.

The influence of age on the response of plasma lipids, body composition, and cardiovascular performance to physical training and detraining was studied in 12 older and 12 young adult male cyclists. The athletes were first examined at the peak of their seasonal preparation and then again 2 months after its suspension. Sedentary males matched for age, weight, and height comprised the respective control groups. During training, body fat mass (BFM) was significantly lower and maximum oxygen consumption (VO2max) higher in both groups of cyclists as compared with controls. No differences in serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), apolipoprotein (apo) B, apo A-II, and fibrinogen were found. During the same phase, triglycerides (TG) and the LDL-C to high-density lipoprotein cholesterol (HDL-C) ratio were significantly lower and apo A-I, HDL-C, HDL3-C, and the apo A-I/apo B ratio were significantly higher in the athletes than in their corresponding sedentary controls. After physical deconditioning, BFM increased and VO2max decreased significantly in both groups of athletes. TG, very-low-density lipoprotein cholesterol (VLDL-C), and fibrinogen increased in young athletes while the LDL-C/HDL-C ratio increased, and apo A-I, HDL-C, HDL2-C, and HDL3-C decreased significantly in both young and older athletes. Thus, an aerobic training program induced an antiatherogenic lipoprotein profile and beneficial modifications in body composition and aerobic power in both older and younger subjects; a 2-month interruption in the program changed these parameters unfavorably in both groups. Age does not seem to influence significantly the plasma lipid response to physical deconditioning.

Economic evaluation for conservation of farm animal genetic resources.

The decline in biodiversity of farm animal genetic resources (AnGR) has come to the forefront of concern in the discussion of animal conservation and breeding programmes. To improve decision-making regarding conservation and breeding programmes, a number of evaluation techniques of farm AnGR are available. This paper presents an overview of the different values associated to AnGR and of the techniques for their measurement being employed in the economic literature. Those include linear programming and farm simulation models, dynamic models estimating the value of research and development and econometric models estimating the demand for breed characteristics. While farm programming and simulation models are fairly well developed, they do have large data requirements. Alternatively, contingent valuation methods are available, in particular when the goal is to capture non-market values embedded in breeds.

Plasma FSH, LH and prolactin levels in postmenopausal women undergoing cyclofenil treatment.

Ten postmenopausal women were studied in an attempt to identify the mechanism of action of cyclofenil, a non-steroidal anti-estrogen which has proved to be effective in the climacteric syndrome. A double-blind inter-patient clinical investigation was undertaken, with patients assigned randomly to treatment for 10 days with cyclofenil, 400 mg/day, or else conjugated estrogens, 1.25 mg/day, always given orally at 8 a.m. Serum FSH, LH and PRL levels were determined daily 2 days before, during and for 2 days after treatment. On the first and tenth day of treatment, five blood samples were drawn between 8 a.m. and 4 p.m. to ascertain if there was any drug-induced variation in the hormonal secretory patterns. Furthermore, endometrial biopsies of all patients were taken before and immediately after the 10-day treatment. In 5 patients, endometrial biopsies were repeated after 3-6 months of therapy with cyclofenil. The results indicate that cyclofenil has two opposing actions on the hypothalamic-hypophyseal axis, one estrogen-like, in that it depresses serum FSH levels, and the other antiestrogen-like, in that it depresses serum PRL levels. They also show that at both the peripheral and the central level cyclofenil is a drug of first choice for postmenopausal women at risk for endometrial and mammary neoplastic pathology.

Cardiovascular neural regulation during and after prolonged high altitude exposure.

Eight young healthy male subjects, members of a Himalayan expedition, underwent 24 h Holter monitoring before departure, after 1 and 4 weeks at high altitude (5000 m) and after return to sea level. At high altitude, the circadian reciprocal changes in low and high frequency (LF, HF) were absent, with no significant reduction in the LF to HF ratio over the 24 h; moreover, the proportion of adjacent R-R intervals that differed by more than 50 ms (pNN50) decreased significantly and remained lower after return to sea level. Urine catecholamines increased at high altitude, but only norepinephrine, after 1 week of exposure, rose significantly. Upon return to sea level the density, but not the affinity, of [alpha]2-adrenergic receptors on platelets decreased significantly compared to pre-expedition values. At high altitude increased sympathetic activity was indicated by elevation of urine norepinephrine and by the loss of circadian rhythm in spectral components. The simultaneous reduction of HF and pNN50 demonstrated decreased vagal tone. The persistence of increased sympathetic activity could explain the downregulation of adrenergic receptors after prolonged high altitude exposure.

Evaluation of atrial vulnerability with transoesophageal stimulation in patients with atrioventricular junctional reentrant tachycardia. Comparison with patients with ventricular pre-excitation and with normal subjects.

The aim of our work was to evaluate the inducibility of atrial fibrillation in a group of patients with atrioventricular junctional reentrant tachycardia and to compare it with that of patients with a Kent-type ventricular pre-excitation (Wolff-Parkinson-White syndrome) and a control group. One hundred and twenty-five subjects were separated into groups. Group 1 comprised 49 Wolff-Parkinson-White patients, with a mean age of 26.4, range 10-66 years; group 2, 51 patients with atrioventricular junctional reentrant tachycardia inducible by transoesophageal atrial stimulation and/or clinically documented, with a mean age of 43.4, range 16-78 years; group 3, 25 control subjects with a mean age of 26.4, range 13-76 years. Each subject underwent atrial transoesophageal stimulation with the following protocol: programmed atrial stimulation with 1 and 2 stimuli during atrial pacing of 100.min-1 and 150.min-1; atrial stimulation for 10 s at a rate of 200-300-400-500-600.min-1 with intervals of 10 s between stimulations, five successive 'ramp-up' atrial stimulations for 9 s with the rate increasing from 100 to 800.min-1 with intervals of 10 s between stimulations. The end point was the completion of the protocol or induction of sustained atrial fibrillation (> 1 min). The chi-square test was used for statistical analysis. Our results showed that in group 1 atrial fibrillation was induced in 27/49 patients (55.1%); this was sustained in 13/49 (26.5%) and non-sustained in 14/49 (28.5%); in group 2, atrial fibrillation was induced in 22/51 patients (43.0%); it was sustained in 7/51 (13.7%) and non-sustained in 15/51 (29.4%); in group 3, sustained atrial fibrillation was not induced in any subject and in only one subject was a non-sustained atrial fibrillation (4 s) induced. The chi-square test showed that group 2 vs group 1 were non-significant, while group 2 vs group 3 and group 1 vs group 3 were significant (P < 0.003 and P < 0.0007, respectively). Therefore group 2 patients showed a greater atrial vulnerability in comparison to the control subjects and a similar vulnerability to group 1 patients. It is possible that the greater atrial vulnerability in the patients of group 2 was due to the double nodal pathway.