Exposure to a combination of heat and hyperoxia during cycling at submaximal intensity does not alter thermoregulatory responses

In this study, we tested the hypothesis that breathing hyperoxic air (F_inO₂ = 0.40) while exercising in a hot environment exerts negative effects on the total tissue level of haemoglobin concentration (tHb); core (T_core) and skin (T_skin) temperatures; muscle activity; heart rate; blood concentration of lactate; pH; partial pressure of oxygen (P_aO₂) and carbon dioxide; arterial oxygen saturation (S_aO₂); and perceptual responses. Ten well-trained male athletes cycled at submaximal intensity at 21°C or 33°C in randomized order: first for 20 min while breathing normal air (F_inO₂ = 0.21) and then 10 min with F_inO₂ = 0.40 (HOX). At both temperatures, S_aO₂ and P_aO₂, but not tHb, were increased by HOX. Tskin and perception of exertion and thermal discomfort were higher at 33°C than 21°C (p < 0.01), but independent of F_inO₂. T_core and muscle activity were the same under all conditions (p > 0.07). Blood lactate and heart rate were higher at 33°C than 21°C. In conclusion, during 30 min of submaximal cycling at 21°C or 33°C, T_core, T_skin and T_body, tHb, muscle activity and ratings of perceived exertion and thermal discomfort were the same under normoxic and hyperoxic conditions. Accordingly, breathing hyperoxic air (F_inO₂ = 0.40) did not affect thermoregulation under these conditions.     

Ultrastructural localization of the high molecular weight proteins associated with in vitro-assembled brain microtubules

Microtubules isolated from brain extracts by in vitro assembly (1, 19, 23) are composed principally of two tubulins and two high molecular weight proteins (microtubule-associated proteins [MAPS] 1 and 2) (2,5,7,20). Recently, it was demonstrated that in vitro-assembled brain microtubules (neurotubules) are coated with filaments (5, 7) which are similar to the filaments attached to neurotubules in situ (4, 15, 21, 24, 25), and it was suggested that the filaments are composed of the higher molecular weight MAPs (5, 7, 12). In this study, microtubules were assembled in the presence and absence of the MAPs, and thin sections of the microtubules were examined by electron microscopy. The results show that the filaments only occur on microtubules assembled in the presence of the MAPs and it is therefore concluded that the filaments are composed of the high molecular weight MAP's.     

Adaptation to Hypoxia by Increased HbO<Subscript>2</Subscript> Affinity and Decreased Red Cell ATP Concentration

THERE is a decrease in the O₂ affinity of mammalian haemoglobin (Hb) as the levels of 2,3-DPG or ATP are increased, which is explained by an allosteric effect on the HbO₂ binding^1,2. Similar observations on amphibians³ and fish⁴, which have molar ratios of ATP to Hb similar to those of DPG to Hb in mammals, suggest that red cell organic phosphates modulate Hb function in all vertebrates. The adaptation of mammals to various hypoxic stresses involves reduced HbO₂ affinity^5–9, the attendant increase in O₂ “unloading” capacity being mediated by an increase in the concentration of red cell 2,3-DPG. We have found the opposite response in hypoxic fish and suggest that an increased O₂ affinity results in increased O₂ transport for the fish.     

THE ADAPTATION OF FUNGI TO FUNGICIDES: ADAPTATION TO COPPER AND MERCURY SALTS

The susceptibility of Botrytis cinerea to copper sulphate in liquid media increased when the volume, and therefore the depth, of the medium in culture bottles exceeded certain values; when the volume was 40 ml. the maximum concentration allowing growth was 300 p.p.m.
By growing mycelium in media containing progressively higher concentrations of copper sulphate a strain was produced which grew at a concentration of 750 p.p.m.
In high concentrations of copper sulphate growth always started at the edge of the liquid, and inocula grew only if they were placed in this position.
In germination tests spores from the resistant strain were more resistant to copper sulphate than were spores of the parent strain.
The resistance of mycelium, and to a lesser extent of spores, was retained after growth of the resistant strain for six months in fungicide-free media.
Spore and mycelial inocula grew in much higher concentrations of copper sulphate when nutrient media were solidified with agar.
The strain resistant in liquid media was no more resistant than the parent strain on agar media.
The resistance of the fungus was not increased after growth for long periods on agar containing high concentrations of copper sulphate. The resistance of the strain resistant in liquid media was not lost after growth on agar media for 3 months.
Attempts to produce strains more resistant than the parent to mercuric chloride were unsuccessful.
The results obtained with phenyl-mercuric acetate were essentially similar to those obtained with copper sulphate, but relatively much more resistant strains were produced.     

Interet diagnostique d’une injection intracaverneuse de 20 μg de Prostaglandine E1 dans l’impuissance

Intracavernous injection of 20 μg of prostaglandin E1 (PGE1) was carried out in 130 impotent patients. The erectile response was compared to the results of arteriological investigations including nocturnal penile tumescence and rigidity monitoring (NPTR) in 59 patients. The response of 60 patients positively categorized as exclusively psychogenic or vasculogenic was also compared to the pattern of the response to 80 mg of papaverine observed in a previous study by the same authors. The PGE1 test may not discriminate psychogenic from wholly organic patients since its results are not correlated to those of NPTR. It helps for the screening of vasculogenic impotence. Lack of response or a partly rigid response is consistent with this actiology but is not specific for it. A fully response makes it unlikely. Compared to papaverine, PGE1 induces less non rigid responses in psychogenic patients (15% versus 35% with papaverine) and more fully rigid responses in vasculogenic patients (respectively 12% and 5 %). Consequently the specificity of the PGE1 test is higher but its sensitivity lower than that of papaverine so that there is no clear difference in the effectiveness of the tests. Nevertheless the PGE1 test should be preferred, because it is safer. Prolonged erections occured in only 5 patients, and all ceased spontaneously. However 4 presented severely painful erections.