Seasonal depth-related gradients in virioplankton: standing stock and relationships with microbial communities in Lake Pavin (France).

This study presents a depth-related survey of virioplankton abundance in Lake Pavin (Massif Central, France), in relation to the abundances of heterotrophic prokaryotes, picocyanobacteria (Pcy), autotrophic picoeukaryotes (Peu), and of autotrophic (ANF) and heterotrophic (HNF) nanoflagellates. The sampling strategy was designed to be representative of the physico-chemical gradients of the whole water column of the lake, and the seasonal variability as well. In mixolimnic surface waters, all communities were present and viral abundance peaked in summer and autumn. Viral abundance was significantly correlated (p < 0.001) with Pcy, Peu, and ANF, indicating that cyanophages and perhaps other phytoplankton viruses represent a significant pool of viral standing stocks in the mixolimnion of Lake Pavin. Microautotrophs were absent in the deep monimolimnic water masses, where viruses and heterotrophic prokaryotes exhibited highest seasonal abundances in summer and/or autumn and were significantly correlated (p < 0.001) to each other. This indicates that the anoxic monimolimnion of Lake Pavin is an exclusive habitat for viruses and heterotrophic prokaryotes. We conclude that in this habitat, host availability is prevalent over other factors (temperature, oxygen, nutrients, grazers) in favoring viral proliferation.

Estrogen receptor cofactors expression in breast and endometrial human cancer cells.

In order to approach the molecular basis of the tissue-specific agonistic activity of antioestrogens, we have compared, at the mRNA level, the expression of various transcriptional cofactors (activators or repressors) of estrogen receptors in different breast (MCF7, ZR75-1, T47D, MDA-MB231) and endometrial (Ishikawa, RL-95-2 and HEC1A) human cancer cell lines. We showed that for SRC-1, CBP, TIF1alpha, RIP140, N-CoR, and SMRT, no significant differences in the expression levels were observed between breast and endometrial cells. For TIF1alpha mRNA, both isoforms were also detected at similar levels in all the cells tested. By contrast, over-expression of AIB1 mRNA was observed in MCF7 cells, but not in other breast or endometrial cells, irrespective of their ER-status. We then used protein-protein interaction assay (far-Western blot) to confirm the increased expression of at least one of the p160 proteins in MCF7 cells. Finally, we demonstrated that RIP140 mRNA is directly induced by estrogens in ER-positive MCF7 breast cancer cell lines but not in Ishikawa endometrial cells. Together these results indicate that some differences exist between breast and endometrial cancer cell lines at the level of estrogen receptor transcription cofactor expression.

The inhibition of rat adrenal cytochrome P-45011 beta gene expression by androgens.

The synthetic androgen methylandrostenediol (MAD) and the naturally occurring one, testosterone, both bring about hypertensive cardiovascular disease when chronically administered to rats. The pathogenesis of this form of experimental hypertension is thought to result from inhibition of steroid 11 beta-hydroxylase activity. In contrast to the above androgens, 19-nortestosterone, androstenedione and dehydroepiandrosterone (DHEA) have been reported to be without effect in elevating blood pressure. To examine the mechanism(s) involved, we have in this study compared the effects of a number of androgens on adrenal cytochrome P- 45011 beta enzyme and mRNA steady state levels. These parameters were also correlated with the ability of adrenal mitochondria isolated from these groups to hydroxylate 11-deoxycorticosterone (DOC) to corticosterone and 18-hydroxy-11-deoxycorticosterone (18-hydroxy-DOC). Rats treated for seven days with 10 mg per day of dihydrotestosterone, testosterone, 19-nortestosterone or MAD showed a profound decrease in cytochrome P-45011 beta mRNA levels (to less than 20% of controls). This was accompanied by similar changes in both the level and activity of the enzyme. Androstenedione and DHEA were less potent in effecting these changes. In addition, for MAD and testosterone we tested the dose dependence of these changes and found that increasing doses (0.1 mg to 10 mg per day) of either androgen caused progressive decreases in the parameters measured. To assess selectivity we also determined the steady state level of cytochrome P-450scc mRNA in rats treated with the various androgens. In contrast to what was found with cytochrome P-45011 beta, the mRNA transcript for cytochrome P-450scc was equal to or above control levels. We conclude that, in general, the extent of inhibition of cytochrome P-45011 beta enzyme and mRNA level by a given androgen correlates with its reported facility in producing hypertension in rats. Increased secretion of DOC continues to be a likely mechanism for the development of this hypertension but with some androgens extra-adrenal effects may be involved.

Expression of adrenal cytochromes P-450 in testosterone-induced hypertension.

Chronic treatment of rats with the naturally occurring androgen, testosterone, leads to hypertension and cardiovascular disease. This effect is believed to be mediated through the adrenal gland and in particular by action on the steroid 11 beta-hydroxylase enzyme system. To study the possible mechanism of this effect, the enzyme system was examined at several time periods up to the time that hypertension develops. Rats were treated with testosterone (10 mg/day) for 3, 7, 21, and 42 days. Levels of cytochrome P-450(11) beta enzyme and messenger RNA (mRNA) were determined as well as 11 beta-hydroxylase enzyme activity. A significant decrease in enzyme activity was observed after 3 days of treatment. This correlates with a profound decrease in the level of cytochrome P-450(11) beta enzyme as determined by Western blot analysis. A large decrease in cytochrome P-450(11) beta mRNA was also observed after 3 days of treatment. All three parameters remained low throughout the treatment period. The decrease in 11 beta-hydroxylase enzyme activity appears to result from a lower enzyme level brought about by decreased concentrations of mRNA transcripts.

Stimulation of intestinal basolateral membrane calcium-pump activity by recombinant synthetic calbindin-D9k and specific mutants.

Calcium transport by the Ca2(+)-pumping ATPase in rat duodenal basolateral-enriched membrane vesicles was stimulated by synthetic calbindin-D9k in a similar fashion to the purified natural protein. In order to elucidate the mechanism of this effect, various synthetic mutant proteins were studied. Proteins with modifications to the N-terminal Ca2(+)-binding domain, or to a cluster of negatively-charged surface residues had altered Ca2(+)-binding but these changes did not affect the stimulation of vesicular Ca2+ transport. It appears that these domains are not essential for the interaction between calbindin-D9k and the intestinal basolateral Ca2(+)-pump.

The prevalence of diabetes mellitus in a traditional-living Polynesian population: the Wallis Island survey.

The prevalence of diabetes mellitus in the traditional-living population of Wallis Island was low and comparable with that found in other rural Polynesian societies. The diabetes prevalence was 1.9% in men and 3.5% in women; impaired glucose tolerance occurred in 5.0% of men and 8.4% of women. The prevalence of obesity was significantly greater in women than in men (37.4% versus 12%, respectively, were equal to or greater than 140% ideal weight). Subjects with diabetes tended to be more obese and less active than normal subjects, but these differences, although appreciable, were not usually statistically significant. The population engages in considerable physical activity, and this, along with the traditional diet, may be responsible for the relatively low diabetes prevalence.

[Prevalence of diabetes mellitus and glucose tolerance abnormality in Melanesians and subjects of Polynesian descent in the rural areas of New Caledonia and at Ouvea (Loyalty Islands)]. / Prévalence du diabète sucré et de l'anomalie de la tolérance au glucose chez les Mélanésiens et les sujets d'origine polynésienne dans les zones rurales de Nouvelle-Calédonie et à Ouvea (Iles Loyauté).

The screening of different ethnic groups who live in the same natural system have enabled the authors to study interaction between genetic and environmental factors as a part of etiology of diabetes mellitus. In New Caledonian country areas, the prevalences of glucose tolerance abnormality (GTA) and diabetes mellitus (DM) have been higher with people of polynesian descent than with Melanesians. GTA 7.6 p. ct. versus 5.1 p. ct. DM 6.5 p. ct. versus 2.2 p. ct. The prevalence of these combined diseases have been 14 p. ct. with the Polynesians and 7.2 p. ct. with Melanesians. These two ethnic groups have shown mean ages and obesity rates similar enough to lead the authors to deny these two factors a major part in the difference between the ethnic prevalences of DM. Besides, the mean plasmatic glycemia two hours after a dose of glucose and the relative risk of DM and GTA according to age and obesity rate have shown that the slight differences between these groups are not involved in the different prevalences of DM. This inter-ethnic difference may be due to genetic factors. However, some environment linked factors besides obesity (such as diet and daily life activity) may share a major part in this difference.

The prevalence of diabetes mellitus and impaired glucose tolerance in Melanesians and part-Polynesians in rural New Caledonia and Ouvea (Loyalty Islands).

The study of different ethnic groups living in the same physical environment provides the opportunity to examine interaction of genetic and environmental factors in the aetiology of diabetes mellitus. In rural New Caledonia, the prevalence of diabetes was higher in part-Polynesians than in Melanesians: males - 6.6 versus 0.5%; females - 6.3 versus 3.5% respectively. The prevalence of abnormal glucose tolerance (impaired glucose tolerance and diabetes) was 11.5 and 15.7% in part-Polynesian males and females, respectively, and 4.7 and 9.2% in Melanesian males and females. Mean age and degree of obesity in these ethnic groups were sufficiently similar to suggest that these factors played no significant role in the difference in diabetes prevalence. Furthermore, adjustment of relative risk of impaired glucose tolerance and diabetes for age and obesity indicated that the modest differences between groups were not responsible for the observed variation in diabetes prevalence. The differences in prevalence of impaired glucose tolerance and diabetes between Melanesians and part-Polynesians may be genetically determined, although the role of certain environmental factors other than obesity, e.g. differences in physical activity or qualitative aspects of diet, cannot be excluded.

HLA antigens in four Pacific populations with non-insulin-dependent diabetes mellitus.

HLA antigen distributions in persons with normal and abnormal glucose tolerance were compared in four Pacific populations. The populations included Melanesians from the Fijian Islands, Loyalty Islands and mainland New Caledonia and Polynesians from the Wallis Islands. HLA-DR results are provided for the first time for Pacific groups. In Polynesians, HLA-B22 was increased in frequency in patients with non-insulin-dependent diabetes mellitus and also in persons with impaired glucose tolerance. However, the association was not statistically significant when corrected for the number of antigens tested. A similar increase in HLA-B22, although not significant, was seen in each of the three Melanesian populations with abnormal glucose tolerance. No other consistent increase in any HLA antigen occurred in persons with abnormal plasma glucose concentrations.

[Wuchereria bancrofti human aperiodic filariasis in French territory of Wallis and Futuna (author's transl)]. / Filariose humaine apériodique à Wuchereria bancrofti à Wallis et Futuna.

Human filariasis caused by the aperiodic form of Wuchereria bancrofti is one of the main epidemiological problems in Wallis and Futuna Islands. The ecologic features and the Public-health Service actions for survey and control of this endemic disease are described. Biological and clinical results were very satisfactory.

[Epidemiological data on amebiasis in New Caledonia]. / Données épidémiologiques sur l'amibiase en Nouvelle-Calédonie.

The present study permits to set up the following conclusions: A) The hygienic level of New-Caledonia and Dependences, concerning both running water feeding and installation of water-closets inside housings, is extremely disparate according to the parishes. On that account, the hygienic level is low on the East Coast of the "Grande-Terre" and in the islands. Most of European inhabitants are found in the district of Noumea whereas Melanesians live in tribes mainly on the East Coast and in the islands. Therefore, there is a real difference of hygienic level between the two main ethnic groups.

[Immunization campaign in Ethiopia (author's transl)]. / Campagne médicale en Ethiopie.

In the framework of the smallpox eradication worldwide programme, WHO, the Ethiopian, and the French governments signed a cooperation agreement by which the French Army Medical Service, based in the French Afars and Issas Territory (TFAI), was designated to carry out an immunization campaign in the ethiopian districts along the border with TFAI. With the every-day collaboration of the ethiopian governmental and traditional authorities, 44,000 people were immunized by the medical and paramedical personnel of 5 "ground teams" with heavy equipment and all-track vehicles and 1 "air-team" with helicopteres. In the same time (7 Feb. - 8 March 1974), the teams collected epidemiological informations on five selected tropical diseases: tuberculosis, malaria, bilharziosis, cholera, small-pox; a team from the TFAI Hygiene and Epidemiological Service investigated thoroughly the Kalo area. The ethiopian border districts are under-equiped with medical and hygiene facilities, and the population is used to go to the TFAI dispensaries and hospitals. TFAI being free of malaria, bilharziosis and smallpox, the French Medical Service has to maintain a firm grip on possible spreading. Kalo area might be a favorable reservoir due to the prevailing ecological conditions. Tuberculosis is so widely common that any control in the TFAI would imply a BCG campaign on both sides of the border within an inter-governmental plan of operations.