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Biomedical subjects

L Villard

Publications and source records attributed to L Villard.

66 records · Page 4Linked to original sources
PubMed1987

Dietary intake of vitamin A precursors by rural Gambian pregnant and lactating women.

In view of the apparent paradox of low dietary intakes of vitamin A by rural Gambian women, which is not accompanied by deficient biochemical or physiological indices (Bates, 1983), a detailed study was undertaken, in which dietary intake was remeasured by direct weighed food intakes, coupled with chemical analysis of the carotene content of key food components. This was combined with recall data on dietary patterns in order to obtain a precise picture of carotene intakes throughout a twelve month period, with supplementary information spanning 4 years. Major contributors to dietary carotene intake were mangos (brief period of local availability during the dry season), leaf sauces (mainly rainly season), and small amounts of red palm oil (purchased by the more wealthy families). Preformed vitamin A made only a very small contribution to the diet. For 35 subjects studied during pregnancy in the village of Manduar, the geometric mean home food carotene intake was 0.81 mg/day, and for 61 pregnant subjects from the village of Keneba, the geometric mean home food carotene intake was 0.62 mg/day. However, there were large individual variations. While the efficiency of conversion of carotene to retinol is not known precisely, it is clear that these intakes are considerably below the current recommended dietary allowance for vitamin A during pregnancy, and especially during lactation.

Carotenoids↗
PubMed1987

Effect of vitamin A supplementation on plasma and breast milk vitamin A levels in poorly nourished Gambian women.

Plasma and breast milk vitamin A and plasma carotenoids were measured in groups of pregnant and lactating women in two neighbouring rural Gambian villages. One of the groups (Keneba) received a 650 micrograms daily vitamin A supplement. During pregnancy, plasma retinol values were significantly (19 per cent) higher in the supplemented group. During lactation, breast milk values were significantly (23 per cent) higher in the supplemented group. Changes in plasma and breast milk vitamin A levels during the cycle of pregnancy and lactation and with season are also described, and the value of a combined index of plasma retinol and plasma carotenoids is illustrated. The significant effect of a prolonged low level vitamin A supplement to pregnant and lactating women has important implications for nutrition intervention programmes.

Adult↗
PubMed1986

Carotene dioxygenase (EC 1.13.11.21) activity in rat intestine: effects of vitamin A deficiency and of pregnancy.

1. Female weanling rats were fed on a purified diet containing either no vitamin A, apart from traces present in casein (deficient groups), or the same diet containing 1.55 mg retinol as retinyl acetate/kg (control groups). In one experiment the deficient groups were given 1 microgram retinol/d after 10 weeks, to permit successful reproduction under conditions of marginal vitamin A status. A proportion were mated at 11 weeks after weaning, and fetal development was permitted for 7 d or for 20 d before killing. 2. Carotene dioxygenase (EC 1.13.11.21) activity was measured in a supernatant fraction from intestinal mucosal scrapings. For each group, activity was 20-30% greater in the vitamin-A-deficient animals than in the controls, and the difference reached statistical significance for the virgin and 7 d pregnant animals in the first experiment (severe deficiency) and for the 20 d pregnant animals in the second experiment (less-severe deficiency). 3. It is suggested that low tissue vitamin A levels may feedback to increase carotene dioxygenase activity, by mechanisms at present unknown, presumably to ensure a more efficient use of precursor dietary carotenoids.

Animals↗
PubMed1986

Dark adaptation in pregnant and lactating Gambian women: feasibility of measurement and relation to vitamin A status.

The feasibility of dark adaptation measurement, using a Friedmann Visual Field Analyser, was assessed under field conditions in an isolated rural community in The Gambia, West Africa. It was found to be possible to obtain meaningful and reliable measurements on nearly all of the 117 subjects tested in two communities. Measurements were made throughout the cycle of pregnancy and in early lactation. No deterioration was observed in the later stages of pregnancy, in contrast to the deterioration reported previously in some vitamin A-deficient communities. Nearly all measurements were within the normal range quoted by the manufacturer. No evidence of improved adaptation was detected in women receiving a food supplement containing vitamin A. There were moderate variations with age of subject and with season, although the latter were not closely correlated with variations in vitamin A intake. Better nourished Gambian and Caucasian subjects showed slightly better performance than the village subjects, but this seems simply to reflect their better understanding of the test, since a small learning effect was observed. It is concluded that, despite limited comprehension of the nature of the test, reliable measurements could, with care, be obtained on illiterate adults from an unsophisticated society, and that in the marginally nourished community studied, a substantial increase in vitamin A intake had no discernible effect in improving dark adaptation performance.

Adolescent↗
PubMed1984

Seasonal variations in plasma retinol and carotenoid levels in rural Gambian women.

Plasma carotenoid levels exhibited a major seasonal variation in pregnant and lactating women in Keneba, a rural Gambian village. This is probably due mainly to the seasonally related contribution of mangoes, which are a major dietary component during May and June, but are essentially unavailable for the remainder of the year. Plasma retinol levels, on the other hand, exhibited much less seasonal variation, although a trend towards higher levels in May and June was just discernible. Plasma retinol levels were significantly lower than those observed in a group of pregnant and lactating women living in the UK.

Carotenoids↗
PubMed1982

Physiological tests during an improvement in riboflavin status in lactating Gambian women.

During several weeks riboflavin supplementation of lactating African women, which reduced their mean activation coefficient of erythrocyte glutathione reductase (EGRAC) from 1.65 to 1.21 and initiated an improvement in clinical deficiency signs, measurements were made of physiological functions which may be connected with riboflavin status. No specific response to the supplement could be detected in body weight, grip strength, haematological parameters, osmotic fragility and resistance to oxidative stress of erythrocytes, plasma iron levels and related indices, or plasma hormone levels. There was a cross-sectional relationship between erythrocyte distribution on Percoll density gradients and EGRAC before supplementation, and between the Percoll pattern and total haemoglobin concentration. It is not yet known, however, whether a direct causal relationship exists between these variables.

Adult↗
PubMedDate not supplied

Spectrum and distribution of MECP2 mutations in 424 Rett syndrome patients: a molecular update.

Mutations in the MECP2 (Methyl-CpG-binding protein) gene have been reported to cause Rett syndrome (RTT), an X-linked progressive encephalopathy. Recent studies have identified large gene rearrangements that escape the common PCR-based mutation screening strategy and mutations in a novel MeCP2 isoform (named MECP2B). We have collected the results of MECP2 mutational analysis concerning 424 RTT patients conducted in eight laboratories in France. In total, 121 different MECP2 mutations were identified. R168X (11.5%) is the most common of MECP2 mutations, followed by R270X (9%), R255X (8.7%), T158 M (8.3%) and R306C (6.8%). Only eight mutations had relative frequency>3%. Large and complex rearrangements not previously detected using only a PCR-based strategy represent 5.8% of MECP2 mutations. On the contrary, mutation in exon 1 appears to be rare (less than 0.5%). These data demonstrate the high allelic heterogeneity of RTT in France and suggest that routine mutation screening in MECP2 should include quantitative analysis of the MECP2 gene. This study represents an important instrument for molecular diagnosis strategy and genetic counseling in RTT families.

Cohort Studies↗
PubMedDate not supplied

Ribotyping of Staphylococcus caprae isolated from goat milk.

The usefulness of the API-STAPH system and a method based on ribosomal fingerprinting was evaluated by studying 89 coagulase-negative staphylococci isolated from goat milk. The bacteria were supposed to belong to the species Staphylococcus caprae. The results obtained from the API-STAPH system showed variations in their phenotypic features. DNA cleavage with EcoRI yielded six ribotypes and three distinct patterns were generated when the DNA of the strains was digested with HindIII. Forty-six strains were correctly characterized as S. caprae by the two methods. In addition, 37 isolates having atypical biochemical profiles with the API-STAPH system were confirmed as being S. caprae by the ribotyping. Three strains remained unclassified by both methods. Ribotypes generated by HindIII were found to be the most informative for species determination, whereas the number of bands generated by EcoRI indicated the usefulness of this enzyme in S. caprae typing.

Animals↗