Radicaux libres et spermatozoïdes humains: physiologie et physiopathologie

The role of reactive oxygen species in the physiopathology of human sperm function has been emphasized in recent years. Their production in semen has been associated with loss of motility, decreased capacity for spermoocyte fusion and loss of fertility. In semen preparations, there are two major sources of reactive oxygen species: leucocytes and spermatozoa themselve. It has been proposed that reactive oxygen species production by human spermatozoa was dependent upon a membrane-bound NADPH oxidase or a mitochondrial diaphorase. Hydrogen peroxide produced by the dismutation of superoxide anion has been recognized as the most toxic oxidizing species for human spermatozoa. Owing to their high content of polyunsaturated fatty acids, it has been proposed that lipid peroxidation of the sperm plasma membrane is largely responsible for defective sperm function. Reactive oxygen species also affect the sperm axoneme as a result of ATP depletion, inhibit mitochondrial functions, and synthesis of DNA, RNA and proteins, produce cytoskeletal modifications and inhibit sperm-oocyte fusion. Human spermatozoa possess enzymatic defence systems such as superoxide dismutase, glutathion peroxidas/reductase and catalase to counteract the toxic effects induced by reactive oxygen species. Correlations have been reported between their effectiveness and the duration of sperm motility. If the excessive production of reactive oxygen species is detrimental for human spermatozoa, they could also participate in the physiological function of the spermatozoa when present at low concentrations. Indeed, reactive oxygen species have been shown to be involved in the activation of several enzymes. Furthermore, sperm capacitation, acrosome reaction and sperm-zona interaction would be enhanced by reactive oxygen species.     

Blessures dans la filiation et infertilité masculine : étude comparative et psychodynamique

The family history of a set of infertile men was the aim of the present study, through a filiation events grid based on a psychoanalytical approach. During the genetic counselling before ICIS procedure, the family chart was established and the filiation grid applied to a group of 30 infertile men requiring assisted reproductive procedures, as well as to a control group of 30 fertile men recruited in a maternity hospital after birth of their child. The filiation events differed significantly between two groups. It can be therefore assumed that difficulties in the past generation may play a part in some cases of infertility. A psychodynamic approach is then developed to highlight the hypothesis of a link between the traumatic impact of these filiation events on these men and its translation as a somatic expression.     

5α-Réductases: Physiologie et pathologie

In most androgen target tissues, the first step of androgen action is the 5α-reduction of testostérone to DHT which binds to the androgen receptor wih an affinity 3 to 4 fold higher than testostérone. Two genes, encoding two isozymes of 5α-reductase (5α-R) have been cloned. The two isoforms, 5α-R1 and 5α-R2 are located on chromosome 5 and 2 respectively and differ in optimal pH, substrate and inhibitor affinities and tissue expression. 5α-R2 is responsible for sexual différenciation. It is the major form expressed in the prostate where it seems necessary for embryonic growth and development. In this tissue, as in human skin, 5α-R2 is stimulated by androgens thus amplifying androgen action. 5α-reductase deficiency results in androgen insensitivity due to abnormal 5α-R2. Affected patients are XY individuals with a very peculiar form of male pseudohermaphroditism: they have feminine genitalia at birth and masculinize at puberty. Different mutations, spannning the whole coding portion of the gene, have been described; correlation between mutations and enzyme activity have led to the tentative localization of the substrate binding site in exon 1 and the cofactor binding site in exon 4. In contrast to androgen insensitivity due to 5α-reductase deficiency, increased 5α-reductase activity can result in androgen hypersensitivity as described in idiopathic hirsutism or benign prostatic hyperplasia. In these case antiandrogen therapy, using 5α-reductase inhibitors, can be considered.     

Cancer du testicule: BEP et spermatogenèse

The sperm characteristics of 44 men treated with two or more courses of BEP chemotherapy for non seminomatous germ cell testicular tumours were investigated before and 25.2 ± 19.4 months after chemotherapy. Before treatment, 54.5% of patients were oligozoospermic. The mean sperm characteristics did not differ before and after chemotherapy. However, following chemotherapy, the recovery of initial sperm count was more frequent after one year than before. During the first year, recovery was more frequent in patients treated with two than in those treated with more than two BEP cycles. In patients with good pre-treatment sperm count, sperm production was reduced by half after chemotherapy. In a subgroup of men who provided two sperm samples after chemotherapy, sperm production was better in the second sample than in the first. Our data suggest that sperm recovery is related to testicular function prior to therapy, to the time elapsed after chemotherapy and in the first year to the number of chemotherapy cycles. In conclusion, our study is reassuring concerning the long-term male reproductive toxicity of BEP. However, further studies are required to analyse the possible effects on sperm genetic material during the recovery period.     

Acquérir l’ivoire vrai et lui donner forme : contraintes pratiques et techniques

Dealing with objects made on osseous materials as mammoth ivory involves questions about the availability of this raw material within the territories occupied by palaeolithic societies. In the case of green ivory procurement, this availability is directly linked with the geographical distribution of mammoth populations. The ways of procurement of this raw material seem to be guided also by some cultural traditions. The authors propose a reflexion about these zooarchaeological issues and the first technical gestures, which come in the initial stages of any exploitation of true ivory.     

Systématique des Saccharomyces: Osidases et besoins vitaminiques

A study of the genus Saccharomyces by new biocharacters demonstrates indirectly the genotype of each species; intracellular osidases (lactose — maltose — cellobiase — melibiase — invertase — trehalase) and vitamine requirements (biotin — folic acid — inositol — niacine — pantothénate —para-aminobenzoïc acid — pyridoxine — thiamine) reveal some phylogenetic links between the species. It appears that Van der Walt's group I is very homogeneous and must be restricted to only 7 species. The Torulospora group seems very similar to the genus Debaryomyces when vitamine needs and osidases are considered; the relations between the 2 groups are discussed. When other biocharacters are studied (nitrite reductase-immunological properties, etc. ...) the value in the GC content (4–5% lower in Debaryomyces) will be established.These results confirm that intracellular osidases and vitamine needs are very valuable tools for systematic criteria.

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Collaboration technique: Mme Billon-Grand.     

Terre et Vie : des histoires imbriquées

The Earth's history consists in recurrent flashbacks of similar events and scenarios: redistribution of continents, orogenic cycles, glaciations, marine transgressions and regressions, etc. In contrast, Life's history evolves according to a succession of stages: prokaryotic stage, eukaryotic cell stage, pluricellular organism stage, terrestrialization, development of animal societies, hominization. With each successive stage the biosphere rises to a higher level of organization and complexity. This evolution results from the natural trend of living organisms to extend their control over the entire planet while they progressively escape the constraints of the aquatic environments and climates. During the last four billion years close and complex interactions prevailed between the history of both the Earth and Life. Living organisms have a profound effect on their environment and on the processes of the Earth dynamics, while the planetary environment controls the evolution of living species. Nevertheless, from time to time, the fragile equilibrium established between Earth's and Life's dynamics breaks down and triggers mass extinctions. It is presently the case of the increasing impact of human activities on the integrity of our planet, a major challenge for humankind during the 21st century.     

Dysfonction érectile et diabète : fréquence et profil clinique à partir de 200 observations

Purpose

Erectile dysfunction is one of the most frequent complications in diabetes and also the most often under diagnosed. We report the prevalence of erectile dysfunction in 200 diabetic patients.

Patients and methods

Prevalence was estimated by the French version of the International Index of Erectile Function 5 (IIEF5).

Results

146 patients were included. Erectile dysfunction concerned 74 patients; a severe form was observed in 21.6%, a moderate in 37.8% and a mild one in 40.6%. The patients who presented erectile dysfunction were significantly older and displayed longer duration of diabetes.

Conclusion

Erectile dysfunction is frequent and severe among diabetic patients. The medical staff plays an essential role to initiate early diagnosis, promote psychological support and provide medication, when possible.     

Localisation ultimobranchiale et thyroidienne des cellules C (cellules à calcitonine) chez deux Columbidae: le pigeon et le tourtereau

Résumé Chez les deux Columbidae étudiés, les cellules C sont présentes à la fois dans les corps ultimobranchiaux et dans la thyroïde. Les corps ultimobranchiaux sont constitués de cordons renfermant des cellules glandulaires et des cellules bordantes. Dans certaines zones périphériques de la thyroïde, des cordons ultimobranchiaux typiques sont localisés dans les espaces interfolliculaires et sous-capsulaires. Des cellules C folliculaires basales analogues à celles de la thyroïde du mammifère sont rarement observées.Les caractères morphologiques des cellules C sont identiques quelle que soit leur localisation: ultimobranchiale, thyroidienne extrafolliculaire ou folliculaire basale. Les granules sécrétoires diffèrent légèrement par leur forme chez le pigeon et le tourtereau; leur diamètre moyen est plus variable d'une cellule à l'autre chez le pigeon.Des contacts neuroglandulaires existent au niveau des cordons glandulaires localisés dans les corps ultimobranchiaux et dans la thyroïde. Leur signification reste obscure.

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Ultimobranchial and thyroidian localization of C cells in two Columbidae: the pigeon and the turtle-doveAn electron microscopic study

Summary In the two Columbidae we studied, C cells are present both in the ultimobranchial bodies and in the thyroid. Ultimobranchial bodies consist of cords which are made up of glandular cells and limiting cells. In certain peripheral regions of the thyroid, typical ultimobranchial cords are situated in the interiollicular and infracapsular spaces. Basal follicular C cells similar to those of the mammalian thyroid are rarely observed.The morphological characteristics of the C cells are identical whatever their situation may be: ultimobranchial or thyroidian, be it extrafollicular or basal follicular. The secretory granules differ slightly by their shape in the pigeon and the turtle-dove; their medium diameter varies more from one cell to another in the pigeon.Neuroglandular contacts exist at the level of the glandular cords situated in the ultimobranchial body and in the thyroid. Their signification is not clearly understood.

     

Traitements discontinus par le BrdU et coloration par l'acridine orange: obtention de marquages R,Q et intermëdiaires

Discontinued treatments with BudR at different periods of the cellular cycle produce various chromosome banding after staining with acridine orange. In particular, it is possible to observe R- or Q- or an intermediary banding, simply by varying the time of incorporation of BudR. This implies that the amount of AT or GC bases present locally in DNA is not directly responsible for the banding observed. Furthermore it appears that a precise correlation exists between replication and R- or Q-banding: the DNA located at each group of bands replicates either early (R-bands) or late (Q-bands). But these timings overlap towards the middle of phase S: if the treatment is given at that time, it is possible to observe aspects intermediary between Q and R.