Structures de la cabuamine et de la vincorine

Cabuamine is identified as O-methyl-hydrogeno akuammine.     

Affections dermatologiques de la muqueuse genitale masculine et de la verge

A wide variety of infectious, inflammatory or dysplasic disorders may affect both male genital skin and mucous membranes. We review here the clinical patterns or the most common disorders. The diagnosis is based upon the existence of erythematous balanitis, erosions or ulcerations. Among infections, candidiosis, genital herpes, HPV papillomas are the most common. Most of inflammatory skin disorders may affect the male organ, especially psoriasis, lichen planus or erosive lichen planus, allergic dermatitis, auto-immune bullous dermatoses, drug-reactions. Chronic balanitis, or recurrent inflammatory balanitis, lichen sclerosus may lead to the emergence of intraepithelial neoplasias (PIN) or invasive carcinomas. The management of genital lesions needs in fact: the observation or oral mucous membrances and of the skin it-self with a special attention to very peculiar body sites for the presence of typical skin disease lesions; a surgical biopsy for microscopic observation; in some cases immunopathology with direct and indirect immunofluorescence for the diagnosis of auto-immune disorders.     

Baisse de la production et de la qualite spermatique chez l’homme: Facteurs de variation et problemes méthodologiques

In the last few years, the possible decline of human semen quality as well as the important geographical variations of semen quality have been discussed in several scientific articles. In a meta-analysis of 61 publications worldwide, Carlsen et al. found a trend of decreasing sperm count over the past 50 years. This work has been at the origin of many commentaries and controversy. Two kinds of questions were mainly raised: Is the phenomenon real? what could be the reason(s) for such a decline? Many sceptical attitudes facing the conclusions of Carlsen et al. came from the fact that the studies included in the meta-analysis were done in various countries at different times, that the men studied could be very heterogeneous in term of fertility status and that the sample sizes of many studies were very low. It was also advocated that the results could be influenced by cofactors as the man’s age or the duration of sexual abstinence before semen collection or by differences in the methodologies used to analyse the semen samples in the various centers. Interestingly, several retrospective studies from a single centre were published after the meta-analysis of Carlsen reporting data from different groups of men recruited during more than 10 years periods in the last decades. Some of these studies found a decline of sperm concentration while for others, no secular modification of sperm concentration could be observed. It was also noticed important differences between values of semen characteristics in these various studies raising the question of geographical or regional differences besides the secular trend observed. Most of the published studies were very imprecis or poor of information concerning the men included in the study, the technical conditions used for semen analysis, the statistical methods used and the interpretation of the data. We discuss here some of the data of these studies in the context of the actual debate on the modifications of semen quality with the aim to pin-point the methodological bias contributing to the variation in the evaluation of semen quality. Moreover we also discuss the current data on the factors related to the men and their environment which could modulate sperm production and quality. It is mandatory to determine if the man’s reproductive function is influenced by environmental factors and if yes how they act. May be one of the main interest of the ongoing debate will be to develop basic and prospective epidemiological research in the field.     

Évolution horaire au cours d'une journée normale de la photosynthèse, de la transpiration, de la respiration foliaire et racinaire et de la nutrition N.P.K. chez Zea mays

Hourly development during a normal day of photosynthesis, transpiration, leaf and root respiration, and of N.P.K nutrition in Zea mays. Metabolism of Zea mays L. cv. INRA F₇×F₂ can be measured hourly with the “C₂3A system”, under favourable and constant growth conditions. The photosynthesis is especially stable and is submitted only to a development linked with the leaf surface growth. During the vegetative stage the leaf surface increases regularly both in the day and in the night. The water loss does not change during the diurnal period and remains important during the night if humidity is less than 100%. The leaf respiration is nearly stable. The root respiration, measured with O₂ and CO₂, fluctuates according to a typical rhythm with two maxima. Day and night mean rates were about the same. The respiratory quotient is about one during the vegetative stage. There is no decrease in the rate of phosphate absorption during the night, and a very small decrease in the rate of nitrate absorption. Ammonium is totally consumed in the first hours after renewal of the nutrient solution. At the same time the potassium consumption is decreased, and then presents a maximum followed by a night reduction. Under our conditions, all of the observations allowed us to assume the presence of an adequate reserve of assimilates and suggest the existence of a precise regulation process, which can ensure an even day night functioning of the plant metabolism, but which does not preclude the presence of internal rhythms, as indicated by the oscillation of the root respiration.     

Evolution de l'activite auxines-oxydasique et peroxydasique lors de l'induction photoperiodique et de la sexualisation de l'epinard

(Evolution of the auxin-oxidase and peroxidase activity duringthe spinach's photo-periodic induction and sexualisation) Protein extracts, prepared from spinach leaves, are analysedafter a gel chromatography on Sephadex G-100 and SE-SephadexC-50. The photoperiodic induction seems related with a fallof the auxin-oxidase and peroxidase activities we observe achange in the isozyme number and pattern. The female plants have more isozymes, but the enzymatic activityis higher in the male plants. The destruction of the indole-3-acetic acid, in spinach, isnot strictly related to the peroxidases. (Received September 14, 1971; )     

Evolution de la temperature de l'oxygene dissous et de la transparence dans la baie Nord du lac Tanganika

Resume Nous décrivons dans ce travail l'évolution de la température de l'oxygène dissous et de la transparence dans le bassin N. du lac Tanganika.La température de l'eau ne subit des fluctuations intéressantes au cours de l'année que dans les 100 premiers mètres de la surface. Les eaux du Tanganika offrent une temperature élevée jusqu' à ses plus grandes profondeurs; à 1.400 m. la température de l'eau est encore de 23.35° C. La température des eaux superficielles dépend de l'insolation journalière et les variations saisonnières n'affectent qu'une épaisseur d'eau d'une centaine de mètres. La couche oxygénée de l'eau est très faible par rapport aux énormes profondeurs du lac. Dans le bassin N. elle varie au cours de l'année entre les extrêmes de 45 m. et de 115 m.; la plupart du temps la limite de l'oxygène dissous se situant à 75–80 m de profondeur.Les eaux superficielles sont fortement oxygénées, leur teneur en oxygène dissous oscille autour de 100% de satuation, jusqu'au thermocline elles sont encore oxygénées à 80–90%.Le thermocline est toujours plus haut que la limite de l'oxygène dissous et ne présente absolument pas une barrière biologique comme c'est le cas dans la plupart des lacs des régions tempérées.La transparence des eaux du lac Tanganika est considérable, elle atteint souvent 20 m; la moyenne au cours de l'année se situant aux environs de 15 m.

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Summary The author describes the temperature, oxygen and transparency conditions in the Northern basin of Lake Tanganyika.The fluctuations in the temperature of the waters in the course of the year is of interest only down to a depth of 100 m.The temperature of water in Lake Tanganyika is high even in the greatest depths; at 1.400 m depth the temperature of the water is still 23.35° C. The temperature of surface water depends on the daily solar radiation. The influence of seasonal variations is felt only down to a depth of about one hundred meters.The oxygenated layer of water is very thin in comparison with the very great depth of the lake. In the northern basin, this layer varies in thickness between 45 and 115 m, the limit of dissolved oxygen being at a depth of about 75 m most of the time.The oxygen concentration in superficial waters is very high and nearly reaches the saturation point. Down to the thermoclinal point, the concentration is still 80–90 % The thermocline is always higher than the limit of dissolved oxygen, it does not at all constitute a biological barrier as it does in most lakes in temperate climates. The waters of Lake Tanganyika are very transparent, their transparency often reaches the depth of 20 m, the average for the year being 15 m.

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Centre de Recherches du Tanganika (Uvira) Institut pour la Recherche Scientifique en Afrique Centrale I.R.S.A.C.