Variations de quelques aclivités enzymatiques (peroxydase, catalase, AIA-oxydase) et de la teneur en polyphénols au cours de la germination de I'Orge. Influence de la kinétine

Peroxidase catalase, IAA-oxidase and polyphenol content of growing barley coleoptile. Effect of kinetin. - Kinetin strongly inhibits root and coleoptile growth of germinating barley in the dark. Treated coleoptiles become senescent before the untreated ones. Soluble proteins content, peroxidase, catalase and IAA-oxidase activity were greatly increased in treated coleoptiles while the level of polyphenols was reduced. These biochemical effects joined with the other property of kinetin to diminish α-amylase synthesis in the endosperm are discussed in relation to growth and in connection with the classic view of a cytokinin retarded senescence.     

Influence de la densité de population larvaire sur la taille des adultes,la durée de développement et la fréquence de la diapause chezPteromalus puparum L. [Hym., Chalcidien]

Summary The parasitoid waspPteromalus puparum was reared for many generations under controlled laboratory conditions: larval development in diapausing pupae ofPieris brassicae, 14 hours photoperiod, temperature of 21 °C or 25 °C. The fluctuations in the density of population appear to be the main source of variation for larval development. An increase in the number of larvae living in the same host pupa results in a decrease of adult size, a reduction of developmental time and a diminution of incidence of larval diapause. According to these results, it appears that a high population density hastens the occurrence of metamorphosis and makes it easier. It is suggested that various nervous stimulations, such as food shortage and interactions between larvae, may induce the onset of neurosecretion by the brain.      

Malladaites nov. gen. et Spinammatoceras (Hammatoceratidae,Ammonitina) de l'Aalénien de la zone subbétique,Sud de l'Espagne

The aim of this paper is to remark some morphologicaldifferences among the type-species of the genus ZurcheriaDouvillé and those species attributed to this genuf by Buckman & Brasil: the group of H. pugnaxVacek for which Schindewolf (1964) defined the genus Spinammatoceras, and the group of H. pertinaxVacek for which we propose Malladaites gen. nov.; new species of both genera are described. The stratigraphical range of these species is established in the Betic Cordillera.     

Influence comparée de l'(±)-acide abscissique,de la coumarine,de l'acide p-coumarique et de certains de leurs dérivés sur la croissance de la première feuille de blé

Summary The activities of (±)-abscisic acid and a number of compounds derived from p-coumaric acid and coumarin and their interaction with gibberellic acid in the control of the elongation of the first wheat leaf are examined. (±)-Abscisic acid strongly inhibits leaf growth in the presence as well as in the absence of gibberellic acid, but the inhibition is greater in the presence of gibberellic acid (3 g/l already have an observable effect). Among other compounds, only ferulic acid and coumarin significantly reduce leaf elongation, and they are effective only at high concentrations (1.44 · 10^-4 M/l).     

Conséquences de la chimiothérapie anticancéreuse sur la fertilité de la femme

Sterility is a potential toxic effect of chemotherapy. This risk is well established for alkylating agents, but is less clearly defined for anthracyclines, methotrexate and fluorouracil and poorly defined for alkaloids, platinum, etoposide and taxanes. The main predictive factors for ovarian toxicity are the additive effect of cytotoxic drugs, the cumulative dose of each drug and the patient’s age. This effect of chemotherapy is evaluated on menstrual cycles, hormonal assays and the number of pregnancies observed in patient cohorts. Chemotherapy induces destruction of oocytes and granulosa cells. In mice, it has been shown that adriamycin may induce oocyte apoptosis, which can be prevented by modulation of cycle cell signalling (dysregulation of Bax gene or, on the contrary, expression of its antagonist gene Bcl-2 or inhibition of apoptosis with sphingosine-1-phosphate or caspase inhibitors). Clinical data in the literature are usually based on retrospective studies and are somewhat confused: global fertility after MOPP chemotherapy for Hodgkin’s disease is about 20%, adjuvant chemotherapy with CMF, F(A)C or TAC for breast cancer induces amenorrhea in 50% to 70% of cases, PVB or BEP chemotherapy for ovarian germ cell tumors has little effect on fertility when the uterus and one ovary can be preserved, and the majority of women treated with methotrexate, actinomycin D or various combinations for persistent trophoblastic disease remain fertile. Preservation of fertility is a major goal for cancer patients receiving chemotherapy: in vitro fertilization could preserve the couple’s fertility, but is usually not feasible as it would delay initiation of chemotherapy until after stimulation of ovulation; oocyte or ovarian tissue cryopreservation is at the stage of research; oral contraceptives have not been demonstrated to be effective to preserve ovarian function; gonadotropin releasing hormone (GnRH) agonists prevent cyclophosphamide toxicity in rat and monkey ovaries, and a few pilot clinical studies suggest that chemotherapy-induced amenorrhea could be prevented by administration of GnRH analogues simultaneously to chemotherapy, but randomised studies are necessary.     

Surveillance de la santé à l'école maternelle.

In contrast to the traditional program of health assessment of schoolchildren based on periodic physical examination, the program described in this paper is based on the integration of information and data obtained by observation through the school year from parents, teachers and the school nurse, who coordinates the program. The numbers and the types of problems and the date on which they were identified are compared in an experimental group of 557 kindergarten children and a matched control group of 498 children in whom the traditional program was maintained. For problems of hearing, enuresis, learning and behaviour the number of cases detected was significantly greater in the experimental group than in the control group. Each element of the proposed program is analysed and the advantages of an integrated approach to health assessment of schoolchildren are underlined.     

Testostérone circulante et cancer de la prostate. Revue de données récentes

In vitro andin vivo studies show that androgens stimulate prostate cancer. However, evidence from epidemiological studies of an association between circulating levels of androgens and prostate cancer risk has been inconsistent, but most studies have likely been undersized given that the association may be relatively weak. We review prospective studies on the association of serum levels of free and total testosterone, the principal androgen in circulation with risk of prostate cancer. No significant association between total or free testosterone and risk of prostate cancer was found in studies that together included 1,525 cases of prostate cancer and 4,349 controls. No support was found for the hypothesis that high levels of circulating testosterone within a physiological range stimulate development and growth of prostate cancer. Intraprostatic androgen metabolism may still be of importance for prostate cancer development.     

Production primaire dans les eaux de surface de la Méditerranée occidentale. Calcul de la production journalière

We have found a relationship between the net absorption of carbon at time t divided by the net absorption of carbon in 24 h (A_N(t)/A_N(24)) and the incubation duration after sunrise, in surface waters of the western Mediterranean sea. This ratio is quite similar whatever the sample location, the sample depth and the 24-h net-absorption level. Considering this result, we have established a correction factor which may be used to convert primary production rates obtained from incubation durations ≤ 24 h to daily rates (24 h dawn-to-dawn).     

Étude de l'effet de la température sur la division des cellules séparées de feuilles deCalystegia sepium (L.) R.Br.

Cells mechanically isolated from homogenized leaves ofC. sepium dividein vitro. The rate of cell division is strongly influenced by temperature with the optimum between 31 and 34 °C. The rate of cell division increases proportionally with a rise in temperature up to 31 °C and is accompanied by a reduction in the length of the preparatory phase of the division. A supraoptimal temperature (40 °C) inhibits or stops the cell division which can be restored provided that the cells are transferred to 31 °C. If the preparatory phase to the commencement of cell division is accomplished at 17 °C the cells then exposed to 31 °C divide more rapidly than if they are exposed directly to 31 °C.     

Ultrastructure des disques de patte de drosophile cultivésin vitro. Evagination,sécrétion de la cuticule nymphale et apolysis

Summary Ultrastructural observations were made on imaginal leg discs ofDrosophila cultured in vitro in Mandaron's medium M in the presence of - or -ecdysone.During evagination of discs in vitro the tight epidermal folds of the disc flatten out progressively and the cells change their shape.As the discs evaginate, the pupal cuticle is secreted at the apex of the cells: it comprises a three-layered cuticulin, an epicuticle and a thick endocuticle. Secretion of pupal cuticle always starts by the appearance of dense deposits at the apex of microvilli. Only the latter apparently participate in the construction of the three successive layers of the pupal cuticle.During disc development an abundant rough endoplasmic reticulum is formed. Nuclei and nucleoli become progressively enlarged. At the same time, the nucleus, initially located near the base of the cell, moves closer to the apical cell surface. Microtubules become fragmented as soon as evagination begins and are reorientated parallel to the cell surface (i.e. parallel to the new long axis of the cell) at the end of evagination.

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Ce travail a été réalisé avec l'aide du CNRS (Action thématique programmée) «Différenciation cellulaire», contrat n^o A 6554324.

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Ce mémoire représente une partie de la thèse qui sera soutenue par l'auteur devant l'Université Scientifique et Médicale de Grenoble.     

Effets de la température sur la croissance de deux algues vertes du fleuve St-Laurent,secteur de Gentilly,Québec

Two abundant phytoplankters from the St-Lawrence river: Scenedesmus spinosus Chodat 1913 and Pediastrum boryanum (Turp.) Menegh (Chlorophyta, Chlorococca) were sampled, isolated and cultured in monospecific culture. Growth responses were measured after acclimation to different temperatures and after thermal shock treatments.Post-acclimation specific growth rates followed similar patterns with optimal temperatures at about 24°C (S. spinosus) and 26°C (P. boryanum). Final densities were much less influenced by temperature in S. spinosus than in P. boryanum. Post-treatment responses depended on the temperature level maintained after treatment rather than on treatment conditions. No treatment seemed to delay the exponential growth phase. The time needed to reach final densities corresponding to stationary growth phase was not influenced by any thermal treatment. In situ thermal effects at Gentilly nuclear site could be more severe, due to differences in time-temperature history experienced by the algae.

     

Étude expérimentale des variations de la teneur en eau au cours de la déshydratation et de la réhydratation chez la Fougère:Notochlaena vellea R. Br.

Experimental Study of changes in water content during dehydration and rehydration of the Fern: Notochlaena vellea R. Br.—This study takes place after studies made on otherPolypodiaceen Ferns. We have shown that, in these ferns, the survival duration was longer for the subterranean organs than for aerial ones. The problem was to show that this difference is due to a lower dehydration of the subterranean tissues. As far as we looked at the total water deficiency, we did not find any significant difference between the leaves and the meristematic parts of the subterranean organs: the main difference is the rate of rehydration which is higher in subterranean parts.     

Étude de la variabilité de la clairance hépatique de la mébrofénine-99mTc en scintigraphie hépatobiliaire

AimThe purpose of this study was to investigate some of the parameters likely to influence mebrofenin-^99mTc hepatic clearance calculation and inter-and intra-observers reproducibility.Materials and methodsHepatic clearance (%/min m²) of 30 scintigraphies was calculated from the values of hepatic, cardiac, and total activities, according to the method recommended in the literature. We studied: 1) impact of injection–acquisition delay variations; 2) acquisition type: anterior face only (FA) or geometric mean (GM); 3) clearances calculated according to four different body surface area (BSA) formulas; 4) intra-and inter-observers reproducibility for three observers (two evaluations for each observer).Results1) Clearance differences between different studied intervals were statistically significant, more important if the studied interval was far from reference interval (150–350 secondes) and even more when the interval studied was too early (110–310 secondes). 2) There was a statistically significant difference between clearance calculated using either FA or GM datasets (0.85 %/min m²). 3) There were small but statistically significant differences for four of the clearance comparisons using different BSA formulas. 4) Despite differences in size of cardiac and hepatic regions of interest (ROI), intra-observer reproducibility of hepatic clearance was excellent for each observer. Inter-observers reproducibility was also excellent (r = 0.982).ConclusionHepatic clearance of mebrofenin-^99mTc appears to be a highly reproducible method provided that acquisition and clearance calculation are standardized. It provides additionnal functional information to morphological and biological data usually performed before major hepatectomy. Thereby, the definition of a standardized protocol would enable realization of multicentric studies.