Left ventricular filling behaviour in ultra endurance and amateur athletes: a stress Doppler-echo study.

To evaluate the impact of different training levels on left ventricular (LV) filling dynamics, Doppler mitral flow was derived in 25 amateur endurance-trained athletes (amateurs) aged 31 +/- 9 years, with a personal marathon record > 200 min, and in 26 ultra endurance athletes (top athletes) aged 32 +/- 8 years, with a personal marathon record < 170 min, during bicycle exercise in supine position. In particular atrial filling fraction as the relative share of atrial contribution to LV filling was measured. During exercise (150 watt) atrial filling fraction increased significantly more in amateurs from 25% to 34% compared to top athletes from 25% to 29% (p < 0.001). Two min post exercise atrial filling fraction already reached baseline values in top athletes (25%), while it remained significantly elevated in amateurs compared to baseline values (29%, p < 0.001). Only ten min post exercise atrial filling fraction showed baseline values in amateurs (26%). Rate pressure product was not significantly different at all levels of exercise. Thus, while atrial filling fraction rose in both study groups during exercise, it returned earlier to baseline values in top athletes than in amateurs. This indicates a better cardiac adaptation to physical stress and a better diastolic performance during exercise in endurance athletes with a higher training level.     

Doppler echocardiography in the diagnosis of pulmonary hypertension

Review of the current state of knowledge about Doppler diagnosis of pulmonary hypertension is presented. The authors compare the findings of numerous studies with their own data and analyse the causes of discrepancies and controversies that have remained to date. Doppler estimation of mean pulmonary artery pressure (PAP) using acceleration time (ACT) measurement in the right ventricular outflow tract or main pulmonary artery has been shown to correlate closely with simultaneously measured values of PAP both at rest and during exercise (r = -0.92 and -0.94, respectively). ACT values show sufficient sensitivity for the detection of pulmonary hypertension (89%), at maximum (100%) specificity. However, Doppler values not obtained simultaneously do not necessarily correlate with PAP in view of rapid physiological variations of PAP. For everyday diagnostic practice in cardiology, prediction based upon mere qualitative estimation of the type of velocity curve seems sufficient. Doppler diagnosis of pulmonary hypertension, little demanding on both technical skills and equipment, is gaining a priority status among the non-invasive methods available.     

Studies on antifungal agents. In vitro activity of novel cis-5-alkoxy (or acyloxy)alkyl-3-phenyl-3-(1H-imidazol-1-ylmethyl)-2-methylisoxazolidine derivatives

The synthesis and in vitro antifungal activity of a novel series of cis-5-alkoxy(or acyloxy)alkyl-3-phenyl-3-(1H-imidazol-1-ylmethyl)- 2-methylisoxazolidine derivatives (6a-n) are described. The 5-[(4-chlorobenzyloxy)methyl] analogue 6h and the two 5-acyloxymethyl derivatives 6k,l demonstrated the best overall potency. Against Candida stellatoidea, the minimum inhibitory concentrations (MIC's) for 6h,k,l ranged between 0.7 and 2.0 micrograms/ml. The corresponding value for the standard drug ketoconazole was 7-20 micrograms/ml.     

New synthetic analogs of lipid A as lipopolysaccharide agonists or antagonists of B lymphocyte activation.

We have studied the ability of synthetic analogs of lipid A to mimic lipopolysaccharide (LPS) for activation of 70Z/3 pre-B cells (expression of surface Igs) or to antagonize this effect. The results indicate that the presence of glucosamine (mono- or disaccharide) as a 'backbone' for the attachment of fatty acids is not necessary for activation of cells of the B lineage. Phosphate groups are not necessary either. Other structural features such as the configuration of particular asymmetric carbons, and the distance between an anionic group and an N-acyl chain, seem to be much more critical parameters for activation of B cells. Among the synthetic lipids which were unable to activate 70Z/3 cells, one compound, consisting of N,N-acylated and bisphosphorylated 2,3-dideoxy-2,3-diamino-D-glucose, behaved as a specific LPS antagonist and blocked also the activation triggered by the other synthetic inducers. The influence of the synthetic lipids on the entry of mature mouse B lymphocytes into the G1A phase of the cell cycle (cell enlargement) was also investigated. A high correlation was observed between the potency to activate pre-B cells and the ability to induce blast formation in mature B cells.     

Effect of anti-interferon-γ and anti-interleukin-2 monoclonal antibody treatment on the development of actively and passively induced experimental allergic encephalomyelitis in the SJL/J mouse

SJL/J mice challenged with myelin basic protein (MBP) in complete Freund's adjuvant (CFA) developed only mild chronic-relapsing experimental allergic encephalomyelitis (EAE) with very low incidence. However, treatment of challenged mice with anti-infeferonγ (IFN-γ) monoclonal antibody (mAb) determined severe disease in all cases. Similarly, in passive EAE, the addition of anti-IFN-γ to the in vitro MBP-activated cells at the time of transfer led to significant disease exacerbation in all recipients. The disease enhancing effect was observed only when the mAb was given at the time of active challenge or of passive transfer, but not at later times. Anti-interleukin-2 (IL-2) antibody had only a marginal effect in the active induction, but drastically reduced the manifestations of passive EAE, even when mixed with a disease-enhancing dose of anti-IFN-γ. These findings support the notion that IL-2 is required for disease induction whereas IFN-γ plays a disease-limiting role early in the development of EAE.     

Bronchial response to breathing dry gas at 3.7 MPa ambient pressure

In diving, pulmonary mechanical function is limited by the increased density of the gas breathed. Breathing cold and dry gas may cause an additional increase in airways resistance. We have measured forced vital capacity, forced expired volume in 1 s (FEV₁) and forced midexpiratory flow rate (FEF_25%–75%) before and after breathing dry or humid gas at 29–32°C during a standardized exercise intensity on a cycle ergometer at an ambient pressure of 3.7 MPa. The atmosphere was a helium and oxygen mixture with a density of 6.8 kg · m^–3. Six professional saturation divers aged 26–37 years participated in the study. There were no significant differences in convective respiratory heat loss between the exposures. The mean evaporative heat loss was 67 W (range 59–89) breathing dry gas and 37 W (range 32–43) breathing humid gas, corresponding to water losses of 1.7 g · min^–1 (range 1.5–2.2) and 0.9 g · min^–1 (range 0.8–1.1), respectively. There was a significant reduction in FEV₁ of 4.6 (SD 3.6)% (P<0.05), and in FEF_25%–75% of 5.8 (SD 4.7)% (P<0.05) after breathing dry gas. There were no changes after breathing humid gas. By warming and humidifying the gas breathed in deep saturation diving bronchoconstriction may be prevented.