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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. [ABSTRACT FROM AUTHOR]

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 andlor clinically documented, with a mean age of 43.4, range 16–78 years; group 3, 25 control subjects with a mean age of2.64, 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 and 150. min; atrial stimulation for 10 s at a rate of 200–300–400–500–600. min 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 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 27149 patients (55.1%); this was sustained in 13149 (26.5%) and non-sustained in 14149 (28.5%); in group 2, atrial fibrillation was induced in 22151 patients (43.0%); it was sustained in 7151 (13.7%) and non-sustained in 15151 (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. [ABSTRACT FROM PUBLISHER]

Eight young healthy male subjects, members of a Himalayan expedition, underwent 24 h Holier 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 [a]-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. [ABSTRACT FROM PUBLISHER]