Physiopathologie des troubles de l’érection chez l’homme paraplégique

Peripheral mechanisms responsible for penile erection are dependant upon a complex control by the nervous system, including peripheral nervous pathways, spinally mediated reflex loops and supraspinal nervous structures. Spinal cord injury is accompanied by a partial or a complete modification of these controls. In relation to the reflexogenic or psychogenic origin of penile erection, spinal cord injury does not cause the same effects. Reflexogenic erections sitll occur after spinal cord injury at a suprasacral level. After lesions at a level lower than the thoracolumbar spinal cord, tumescence following psychogenic stimulation has been observed. The hypotheses resulting from clinical and experimental observations and explaining the differences at the origin of these response are detailed. The recent developments in the neurophysiology of penile erection and the role of neurotransmitters allow a more analytical approach of the phenomenous and also bring new insights into possible compensatory pathways following spinal cord injury.     

Seed germination of the Australian desert shrubEremophila (Myoporaceae)

Eremophila is an Australian genus of 212 species ranging from prostrate shrubs to small trees, the great majority of which occur in Western Australia. Recent interest in the genus’s germination strategies developed out of a need to seek rehabilitation techniques for mine-site and rangeland areas. The genus is of special interest because of its broad geographic range and prominence in vegetation associations of the arid zone, especially in Western Australia, where it often dominates or codominates over wide areas. ManyEremophila species are known to be tolerant of drought, fire, frost, grazing, and salinity, and would be very suitable for revegetation programmes; however, the genus germinates poorly, for reasons that are not fully understood. During the early 1980s attempts were made, with limited success, to rehabilitate open-cut mine-site waste dumps at Mt. Newman using broadcast seed and rooted cuttings and transplanted seedlings at the Pilbara mine venture at Paraburdoo. Tissue culture and grafting have also been attempted, but environmental management acknowledges that the broadcast seed method is the only cost-effective means of mine-site rehabilitation. Under field conditions the germination ofEremophila occurs in response to heavy rain in autumn and winter, especially with milder temperatures; however, up until now the use ofEremophila in rehabilitation practices has been limited because of the high percentage of seeds that fail to germinate. Two causes for this have been postulated. First, the environmental conditions may not be appropriate for germination. Physical dormancy resulting from the hard woody fruits may be overcome by using a scarification pre-treatment. Second, seed may still fail to germinate even though favourable conditions exist; a secondary chemical mechanism in the form of inhibitors associated with the fruit wall is hypothesised. Chemical properties of the seed, seed coat, or fruit may regulate germination until the fruit wall has been effectively worn away and the chemicals leached out. Few experimental procedures have been carried out to verify these hypotheses, and few studies have examined either fruit productivity (seeds per fruit) or seed viability. Eremophila fruit are dry with a papery exocarp or drupaceous with a fleshy or succulent mesocarp and a woody or crustaceous endocarp and contain between 2 and 12 seeds. Seed viability inE. maculata ranges from 74% to 92% in the first 3 years after fruit maturity, decreasing markedly to 8% after 13 years. Similar patterns have been recorded forE. goodwinii. Effective environmental management utilisingEremophila may be approached in three ways. First, scarify fruit to promote the uptake of water and oxygen; second, use fruit between 1 and 5 years to ensure the highest viability rating; and third, collect fruit from healthy shrubs showing no evidence of insect or fungal attack to ensure quality of fruit. Further research on the genus should include ecological studies, currently poorly understood, and edaphic and soil amelioration projects (e.g., on post mine-site tailings) in an attempt to optimise the vegetation potential ofEremophila.     

Detection of plum pox virus in leaves and aphids by SIBA and DAS-ELISA assays

The slot-immunobinding assay (SIBA) was adapted for detection of plum pox virus (PPV) and compared with DAS-ELISA. SIBA was easy to perform and as sensitive as DAS-ELISA in detection of various PPV isolates in herbaceous and woody plants, but not in aphids (Myzus persicae).     

Plant radioresistance and DNA repair efficiency inChlamydomonas reinhardtii andPisum sativum

This paper compares the repair of DNA single strand breaks (ssb) induced by γ-radiation in two strains ofChlamydomonas reinhardtii (137C/+/ and UVS-I) and three lines ofPisum sativum (NN 131, 198, 140) differing in the degree of radioresistance. DNA ssb in cells exposed to γ-rays (50, 100, 200, 500 Gy) were measured by electrophoresis and alkaline unwinding method with subsequent chromatography on hydroxyapatite immediately after irradiation and after 30 min of post-irradiation incubation at 25°C. An increase of double-strand DNA (in%) was found in cells after 30 min post-irradiation incubation.C. reinhardtii strains displayed an equal level of DNA degradation and repair efficiency in the DNA single strand breaks. The radioresistant line N 198 ofP. sativum is characterized by a lower level of induced DNA ssb and higher efficiency of repair of these breaks as compared with less radioresistant lines NN 131 and 140.     

Superoxide dismutase level in response to paraquat and high temperature in the cyanobacteriumGloeocapsa sp

Paraquat (methylviologen) at concentrations above 0.05 mM inhibited the growth of photoautotrophic cyanobacteriumGleeocapsa sp. in axenic cultures. The growth rate was not affected by concentrations of 0.01 mM or less. This concentration resulted after a lag period in a moderate increase in superoxide dismutase level. After removal of paraquat, the cyanobacterium continued to generate higher levels of superoxide dismutase. There was a lag period of one hour before resumption of normal enzyme activity. Addition of puromycin at concentration of 0.5 mg cm^?3 had no effect on cell survival, but greatly enhanced the sensitivity of the culture to the toxicity of paraquat. The data showed an increase of SOD activity by temperatures above the normal growth temperature level. However, this increase was suppressed by chloramphenicol which revealed that the induction of superoxide dismutase by high temperatures was associated withde novo protein synthesis.     

Variation in species richness: Towards a unification of hypotheses

The question, “why do areas vary in species richness?” has been important throughout the history of ecology. It is difficult to answer definitively because we have so many (at least 120) plausible hypotheses. This abundance of hypotheses has led to a number of attempts to classify them. Unfortunately, richness hypotheses often defy such categorization. Instead of placing species richness hypotheses into categories, I suggest an alternative approach: to treat species richness hypotheses as violations of the assumptions of Gause’s Competitive Exclusion Principle. This is a very similar approach to the pedagogy of population genetics: evolution occurs if and only if at least one assumption of the Hardy-Weinberg principle is violated. The classification of hypotheses advocated here treats interspecific competition as a central organizing concept in community theory. However, it does not treat competition as an organizing concept in communities: indeed, the relaxation or disruption of competition is considered to be the status quo in the majority of communities.     

Diversity in two candidate malaria vaccine antigens in different Indian strains ofPlasmodium falciparum

Polymorphism in two malarial antigens, merozoite surface antigen-1 (MSA-1) and ring erythrocyte surface antigen (RESA), has been characterized in four different Indian strains ofPlasmodium falciparum. The Indian strains were obtained from two malaria endemic regions of India, viz. Surat (Gujarat) and Delhi, and established in culture. Monoclonal and polyclonal antibodies raised against different domains of these antigens were used in the study. In MSA-1 a novel intragenic crossover was detected in the central conserved domain in two of the Indian strains. The repeat domain of RESA was found to be absent in the two strains ofP. falciparum isolated from Surat. These differences in immunoreactivity have been extended to the DNA level by appropriate PCR studies. MSA-1 and RESA are candidate vaccine antigens and these diversities will have an important bearing on the design of a suitable malaria vaccine.     

Detection of proteins and sialoglycoproteins in polyacrylamide gels using eosin Y stain

An eosin Y staining technique that permits detection of various proteins, including membrane sialoglycoproteins, in polyacrylamide gels is described. The sensitivity of the eosin Y staining method is comparable to silver staining. In addition, there is an added advantage of the antigen icily of the stained proteins being retained in a Western blot. Details of the procedure to obtain optimal staining results are described.     

Malposition épididymaire et oligospermie

In the course of investigation of men suffering from severe oligospermia the author has met with cases were spermatogenesis was normal in testicular biopsies, contrasting with repeatedly severe oligospermia, the situation being accompanied by an obvious malposition of the epididymis. The main anomaly of the epididymis was the absence of its habitual caudal structure. There is no clear physiopathological explanation for biopsy/sperm discrepancy linked to epididymal malposition, but experimental work concerning cryptepididymal situations may offer a clue.     

Mechanism of neurofibrillary degeneration in Alzheimer's disease

Neurofibrillary degeneration associated with the formation of intraneuronal neurofibrillary tangles of paired helical filaments (PHF) and 2.1 nm τ filaments is one of the most characteristic brain lesions of Alzheimer's disease. The major polypeptides of PHF are the microtubule associated protein, τ. τ, in PHF is present in abnormally phosphorylated forms. In addition to the PHF, the abnormal τ is present in soluble non-PHF form in the alzheimer's disease brain. The level of τ in Alzheimer's disease neocortex is severalfold higher than in aged control brain, and this increase is in the form of the abnormally phosphorylated protein. The abnormally phosphorylated τ does not promote the assembly of tubulin into microtubules in vitro, and it inhibits the normal τ-stimulated microtubule assembly. After in vitro dephosphorylation both PHF and non-PHF abnormal τ stimulate the assembly of tubulin into microtubules. The activities of phosphoseryl/phosphothreonyl protein phosphatase 2A and nonreceptor phosphotyrosyl phosphatase(s) are decreased in AD brain. It is suggested that

1. A defect(s) in the protein phosphorylation/dephosphorylation system is one of the early events in the neurofibrillary pathology in AD;
2. A decrease in protein phosphatase, activities, at least in part, allows the hyperphosphorylation of τ; and
3. Abnormal phosphorylation and polymerization of τ into PHF most probably lead to a breakdown of the microtubule system and consequently to neuronal degeneration.

     

Trace-elements status in camels

Data relating to trace-elements status in camels is scarce, from both a clinical and biochemical point of view. Clinical deficiency or toxicity has rarely been described in this species. However, there is a some evidence that camels are sensitive to trace element disorders in the same way as other ruminants. For example, copper deficiency in camels has been reported in East Africa. Normal plasma level is comparable to cattle (70–120 mg/100 mL). Camels appear to maintain zinc levels at a lower value than other domestic ruminants (<60μg/100 mL). Iron metabolism is more active in the liver than in the spleen. Data concerning manganese levels are possibly unreliable. Some cases of selenium deficiency (white muscle disease) have been reported. No data are available for cobalt status in camels. Finally, camels appear to be more sensitive to iodine deficiency than the other domestic ruminants.     

Techniques and high resolution DNA size markers for pulsed field gel electrophoresis

High resolution DNA size markers are described for pulsed field gel electrophoresis (PFGE). These markers provide resolution of 10–20 kbp over a size range from 10 kbp to more than 400 kbp and are produced by partial restriction digestion of lambda phage DNA concatemers (λ ladder). High resolution markers extending to over 400 kbp are made by partial restriction digestion of λ ladder embedded in agarose. Detailed methods are described for marker production and for DNA separation by contour-clamped homogeneous electric field (CHEF) electrophoresis. These markers and methods are useful for a variety of high resolution DNA mapping by PFGE.     

Etats épididymaire,prostatique et vésiculaire en relation avec les paramètres du spermogramme chez les hommes consultant pour infertilité

The semen results from the mixture on ejaculation of various secretions from the testicle, the genital tract and the adnex glands. It consists on a cellular phase: spermatozoa and a liquidian phase: the seminal plasma. The spermogram is the first exam to make in order to set diagnosis of male infertility. It is completed with a biochemical study of the semen to find an excretory origin to infertility. In this work, we have studied the frequences of prostatic, vesicular and epididymious anomalys, through dosage of their markers in the semen, in 146 males consulting for infertility and eventual relationships between these markers and the characteristics of the spermogram. We found out that the prostate is the most hurt portion of the genital tract in infertile males and presents a dysfunctioning in 32,26% of cases, most often resulting in an inflammatory states of this gland. The epididymious obstruction is detected in 35% of azoospermia cases. In all the cases, we found out significant statistical correlation between the semen volume and the activity of alpha 1–4 glucosidase and also the pH of the semen and the seminal citric acid. For patients having a high leucospermia we didn’t find any relationship between the leucocytes rate in the semen and the different biochemical markers. If the seminal fructose rate has no effect on the initial mobility of spermatozoa, it has a statistically significant effect on their survival. In fact, the diminution of seminal fructose coincides with a bad survival of spermatozoa, which shows the importance of this spermatic substrate on the maintaining of spermatozoa mobility.     

Cytological relationships of selected species ofPanicum L.

The cytological investigation of 12 taxa ofPanicum L. revealed that the vast majority of them have the basic number x=9 at different ploidy levels. The basic number x=8 was recorded only in the tetraploid speciesP. maximum with 2n=32. The diploid number 2n=18 was encountered inP. capillare, P. laevifolium, P. antidotale andP. coloratum (2) with 3B-chromosomes recorded in the latter species. The tetraploid chromosome number 2n=36 was found to exist inP. miliaceum, P. miliare, P. coloratum (1) andP. virgatum. The hexaploid number 2n=54 was recorded inP. bulbosum, P. dichotomiflorum andP. esculentum. The karyotypes of all accessions were mostly symmetrical and mainly comprised of meta- and submetacentric chromosomes with little variation in length among them within each karyotype. Investigation of chromosome association during metaphase I of meiosis revealed that the frequency of bivalents/cell was the highest among all investigated diploid, tetraploid and hexaploid accessions. Univalents were also frequently encountered in various accessions. These results may indicate that segmental alloploidy has been the major process by which polyploid species have originated.     

Hormone-like product of vascular tissue stimulating starch accumulation in pith explants of kale and endogenous cytokinins

When stem explants of kale (Brassica oleracea L. var.medullosa), containing pith parenchyma and a strip of vascular tissue, were cultured on simple sucrose medium, a hormone-like factor was transported from the vascular tissue to the adjacent pith, where it stimulated accumulation of starch. Similarly, up to a sevenfold increase of starch content in explants could be induced by cytokinins added to the culture medium. The relative stimulatory effect of several cytokinins (5×10^?6 M) and hormone-like product of vascular tissue (HPVT) in a typical experiment were: control (1.0), trans-zeatin (6.7), HPVT (6.2), N⁶-[2-isopentenyl]adenine (5.4), transzeatin riboside (5.2), N⁶-[2-isopentenyl]adenosine (5.4), kinetin (3.6), 6-benzylaminopurine (3.5), and adenine (2.1). Concentration of endogenous cytokinins was determined using ELISA (trans-zeatin, N⁶-[2-isopentenyl]adenine and their ribosides) andAmaranthus bioassay (total cytokinins). No effect of vascular tissue on the level of endogenous cytokinins in explants was found. The results support the conclusions of previous experiments that the HPVT stimulating starch accumulation is not a cytokinin.     

Techniques de détection du VIH dans les milieux biologiques: Application à la recherche du virus dans le sperme

Growing numbers of HIV seronegative women want to have children with HIV infected partners by artificial insemination. The most sensitive assays for showing the presence of the virus are the coculture method and the DNA-PCR that are able to detect proviral load. HIV is detected from non spermatozoal mononuclear cells, seminal fluid but it was not found in spermatozoa fraction. But we know, by in vitro studies, that HIV can bound to and enter spermatozoa. Thus artificial insemination between HIV seropositive man and seronegative woman lead to a risk of contamination even with purified spermatozoa. Today, any virological assay is able to affirm that specimen is not infectious.     

Testicule et sperme dans le Syndrome de Klinefelter chez l'adulte

Klinefelter's syndrome is characterised by azoospermia, gynecomastia and hypogonadotropic hypogonadism. The testes are reduced in volume. Microscopically, seminiferous tubules show a reduced diameter and a thickening of peritubular sheath. The seminiferous epithelium contains Sertoli cells with a clear typical nucleus and a heterogeneous nucleolus. Usually there are no germ cells. When present they degenerate at the spermatocyte stage. Very few achieve a complete maturation until the spermatozoon form. The interstitial gland appears relatively hypertrophied, due to the decrease in volume in the other components of the testis. Sometimes Leydig cells display an adenomatous morphology. Therefore the steroidogenic function is impaired. Azoospermia is a major event in Klinefelter's syndrome but sometimes restricted to severe oligozoospermia. In that cases, fertility may be somewhat preserved, and the caryotype usually reveals a mosaicism, 47,XY/47,XXY with a better prognosis than in pure syndrome.     

Yeast artificial chromosome cloning

Yeast artificial chromosome (YAC) cloning systems enable the cloning of DNA stretches of 50 to well over 2000 kb. This makes it possible to study large intact regions of DNA in detail, by restriction mapping the YAC to produce a physical map and by examining the YAC for coding sequences or genes. YACs are important for their ability to clone the complete sequences of large genes or gene complexes that exceed the size limit for cloning in conventional bacterial cloning vectors like plasmids (up to 10 kb), bacteriophage (15 kb), and cosmids (50 kb). A major advantage of cloning in yeast, a eukaryotc. is that many sequences that are unstable, underrepresented, or absent when cloned into prokaryotic systems, remain stable and intact in YAC clones. It is possible to reinlroduce YACs intact into mammalian cells where the introduced mammalian genes are expressed and used to study the functions of genes in the context of flanking sequences. The correct prolein processing mechanisms are present in the mammalian cells to ensure that a viable protein product is produced.     

A search for mutations that affect the non-oxidative pentose phosphate pathway inSaccharomyces cerevisiae

A number of selection strategies have been devised to obtain mutations in the non-oxidative pentose phosphate pathway in the yeastSaccharomyces cerevisiae. Some of these schemes exploit the bidirectionality of this pathway by selecting for mutants that can grow on a mixture of two carbon sources, which allow the pathway to function in opposite directions, while failing to utilize either of them alone. Other strategies select for mutations that prevent growth on glucono-5-lactone or xylulose, compounds metabolized exclusively through the pentose phosphate pathway. In the present study, these schemes yielded 35 mutants that define 11 genetic complementation groups. None of these mutations, however, affected the activity of the pathway enzymes, assayed in cell-free extracts. Nevertheless, the mutants were deficient in various aspects of carbohydrate metabolism and in the biosynthesis of the aromatic amino acids. The problems associated with the selection of mutants directly affected in the functioning of the enzymes of the non-oxidative pentose phosphate pathway have been discussed.