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Biomedical subjects

C Carlier

Publications and source records attributed to C Carlier.

At least 19 recordsLinked to original sources
PubMed1992

Efficacy of massive oral doses of retinyl palmitate and mango (Mangifera indica L.) consumption to correct an existing vitamin A deficiency in Senegalese children.

Administration of large oral doses of retinyl palmitate has become the most widely practised vitamin A deficiency prevention strategy in developing countries. We conducted a follow-up study among 220 Senegalese children aged 2-7 years suffering from moderate undernutrition to determine the efficacy of vitamin A treatment on their vitamin A status assessed by biochemical and cytological (impression cytology with transfer) methods. The first examination (T = 0 m[onth]) was carried out during April 1989, before the mango (Mangifera indica L,) harvest. The second examination (T = 2 m) was carried out 2 months after vitamin A treatment during June 1989 when ripe mangoes become widely available. Conjunctival cells of the eyes of the children with or without ocular inflammation were responsive to vitamin A administration (P < 0.01). There was a significant increase (P < 0.001) in mean serum retinol and beta-carotene levels between T = 0 m and T = 2 m. Mean serum retinol-binding protein (RBP) and transthyretin (TTR) levels did not differ significantly (P > 0.05) at T = 0 m and T = 2 m. Despite the intake of vitamin A, 54% of the children who had abnormal cytology at T = 0 m remained abnormal at T = 2 m. This was due to inadequate levels of TTR and RBP, presumably due to the cereal diet eaten by the Senegalese population. children with abnormal eye cytology had lower serum retinol levels than those with normal eyes at T = 0 m, and beta-carotene values did not correlate with eye cytological abnormalities at T = 0 m. Children with normal cytology had higher serum retinol and also beta-carotene levels than those with abnormal cytology after massive oral doses of vitamin A and consumption of mangoes at T = 2 m. Retinyl palmitate may, therefore, only lead to partial cytological improvement due to a lack of retinol-carrier proteins but dietary beta-carotene may also be involved.

Carotenoids↗
PubMed1992

Conjunctival impression cytology with transfer as a field-applicable indicator of vitamin A status for mass screening.

The increasing importance of vitamin A deficiency in even its mild subclinical form underlines the need for a mass screening test. Clinical, biochemical and cytological methods of assessing vitamin A deficiency in a public health setting have been described and widely used. The cytological method shows promise because it enables early detection of vitamin A deficiency. However interpretation is problematic since histopathological changes are gradual with the progressive disappearance of goblet cells and appearance of enlarged epithelial cells. The reliability and validity of the impression cytology with transfer (ICT) test were assessed in order to produce a meaningful standard for this cytological method. The ICT test was performed in Senegal on 1451 children, in the course of two surveys conducted in 1989 and 1990 in rural areas. Reliability, estimated by Cohen's kappa test for evaluating intra-reader variability, and sensitivity were highest for the abnormal-normal classification (kappa = 0.91; 95% confidence interval (CI): 0.89-0.93; and sensitivity = 74%; 95% CI 66-82%). The ICT method is a cheap, noninvasive and easy test to perform in the field. This method is also reproducible and fairly sensitive according to the abnormal-normal classification. As illustrated by our proposed 50% cutoff of abnormal cytology calculated in relation to 5% of serum retinol values below 0.35 mumol/L criterion, ICT only requires a small sample for the assessment of the overall health of a community in contrast to xerophthalmia and blood vitamin A deficiency tests.

Adolescent↗
PubMed1992

Genetic basis of tetracycline resistance in clinical isolates of Listeria monocytogenes.

The genetic basis of tetracycline resistance was studied in 25 clinical isolates of Listeria monocytogenes. Resistance to tetracycline was associated with resistance to minocycline and due to the presence of the tet(M) gene in 24 strains. Association of tet(M) with int-Tn, the gene encoding the protein required for the movements of Tn1545-like conjugative transposons, was found in all strains. Cotransfer of tet(M) and int-Tn among L. monocytogenes cells and from L. monocytogenes to Enterococcus faecalis was detected in 7 of the 12 strains studied at frequencies similar to those obtained with the prototype element Tn1545. tet(L), the second most prevalent tetracycline resistance gene in enterococci and streptococci, was detected in the remaining strain, where it was borne by a 5-kb plasmid. These observations indicate that two types of movable genetic elements, transposons and plasmids, in enterococci and streptococci are responsible for emergence of drug resistance in L. monocytogenes.

Culture Media↗
PubMed1992

Assessment of the vitamin A status of preschool and school age Senegalese children during a cross-sectional study.

The increasing concern about vitamin A deficiency in even its mild subclinical form has created the need for a mass screening test. Various clinical, biochemical and cytological methods for assessing the vitamin A status have been widely used but all are unsatisfactory for technical, ethical or public health reasons. The two prevalence criteria defined by the World Health Organization (WHO) for a vitamin A deficiency problem of public health significance are xerophthalmia and serum retinol concentrations. Recently we proposed a prevalence criterion for impression cytology with transfer (ICT) at the level of 50% of ICT results being abnormal. We conducted a cross-sectional survey of the prevalence of vitamin A deficiency and also undernutrition during the dry season in a random sample of 1,259 children (n = 442 for the 2-6 years and n = 817 for the 7-14 years) from a rural area in Senegal. Prevalence was 0 times and 4.2 times the WHO criteria for xerophthalmia and deficient serum retinol levels, respectively in preschool children. Abnormal ICT results were more frequent in preschool than in school children (53.4% versus 21.0%). There was an association between abnormal ICT results and stunting. Vitamin A deficiency was a public health problem in preschool children as assessed by the biochemical criterion (20.9% of serum retinol values under 0.35 mumol/l) or the cytological cut-off (53.4% of abnormal ICT results) but was also found in school children (21.0% of abnormal ICT results).

Adolescent↗
PubMed1992

Annual assessment of the vitamin A and nutritional status of children during two cross-sectional surveys.

The changes in the vitamin A and nutritional status of children from a rural area in Senegal were determined by the same team during two cross-sectional surveys distant from exactly one year. At baseline (T = 0 year) 1,259 children were chosen at random. One year later (T = 1 year), 1,008 children were re-examined. Vitamin A and nutritional status were assessed by clinical and cytological methods, and by anthropometrical indicators for the 1,008 participants, respectively. No signs of xerophthalmia were recorded at T = 0 and T = 1 year. The proportions of children deficient in vitamin A as defined by abnormal cytology and suffering from stunting were similar at these two measuring points. Even though these percentages remained similar at T = 0 and T = 1 year, there existed little movement between the abnormal and normal eye cytology group and the stunted and non-stunted group. Since vitamin A is required for normal growth, we calculated the mean linear gain in height according to the eye cytological changes assessed between the two examinations. We found that mean linear growth increments were higher in the groups of children who remained abnormal or reverted to abnormal cytology than in those who remained normal or reverted to normal cytology.

Adolescent↗
PubMed1992

Assessment of vitamin A deficiency in the Republic of Djibouti.

In a countrywide survey, we assessed the prevalence of vitamin A deficiency by clinical examination and impression cytology with transfer method (ICT) in a randomized sample of 2445 subjects representative of the population of the Republic of Djibouti. A plasma retinol determination was made on a part of this sample. Results lead to believe that serious vitamin A deficiency may periodically occur in Republic of Djibouti when nutritional conditions become poor. Meanwhile a large number of children, mostly in the rural area, have a marginal vitamin A status and are exposed to a high level of risk.

Adolescent↗
PubMed1991

An integrative vector exploiting the transposition properties of Tn1545 for insertional mutagenesis and cloning of genes from gram-positive bacteria.

We have constructed and used an integrative vector, pAT112, that takes advantage of the transposition properties (integration and excision) of transposon Tn1545. This 4.9-kb plasmid is composed of: (i) the replication origin of pACYC184; (ii) the attachment site (att) of Tn1545; (iii) erythromycin-and kanamycin-resistance-encoding genes for selection in Gram- and Gram+ bacteria; and (iv) the transfer origin of IncP plasmid RK2, which allows mobilization of the vector from Escherichia coli to various Gram+ recipients. Integration of pAT112 requires the presence of the transposon-encoded integrase, Int-Tn, in the new host. This vector retains the insertion specificity of the parental element Tn1545 and utilises it to carry out insertional mutagenesis, as evaluated in Enterococcus faecalis. Since pAT112 contains the pACYC184 replicon and lacks most of the restriction sites that are commonly used for molecular cloning, a gene from a Gram+ bacterium disrupted with this vector can be recovered in E. coli by cleavage of genomic DNA, intramolecular ligation and transformation. Regeneration of the gene, by excision of pAT112, can be obtained in an E. coli strain expressing the excisionase and integrase of Tn1545. The functionality of this system was illustrated by characterization of an IS30-like structure in the chromosome of En. faecalis. Derivatives pAT113 and pAT114 contain ten unique cloning sites that allow screening of recombinants having DNA inserts by alpha-complementation in E. coli carrying the delta M15 deletion of lacZ alpha. These vectors are useful to clone and introduce foreign genes into the genomes of Gram+ bacteria.

Amino Acid Sequence↗
PubMed1991

Shuttle vectors containing a multiple cloning site and a lacZ alpha gene for conjugal transfer of DNA from Escherichia coli to gram-positive bacteria.

The mobilizable shuttle cloning vectors, pAT18 and pAT19, are composed of: (i) the replication origins of pUC and of the broad-host-range enterococcal plasmid pAM beta 1; (ii) an erythromycin-resistance-encoding gene expressed in Gram- and Gram+ bacteria; (iii) the transfer origin of the IncP plasmid RK2; and (iv) the multiple cloning site and the lacZ alpha reporter gene of pUC18 (pAT18) and pUC19 (pAT19). These 6.6-kb plasmids contain ten unique cloning sites that allow screening of derivatives containing DNA inserts by alpha-complementation in Escherichia coli carrying the lacZ delta M15 deletion, and can be efficiently mobilized by self-transferable IncP plasmids co-resident in the E. coli donors. Plasmids pAT18, pAT19 and recombinant derivatives have been successfully transferred by conjugation from E. coli to Bacillus subtilis, Bacillus thuringiensis, Listeria monocytogenes, Enterococcus faecalis, Lactococcus lactis, and Staphylococcus aureus at frequencies ranging from 10(-6) to 10(-9). The presence of a restriction system in the recipient dramatically affects (by three orders of magnitude) the efficiency of conjugal transfer of these vectors from E. coli to Gram+ bacteria.

Cloning, Molecular↗
PubMed1991

Prevalence of malnutrition and vitamin A deficiency in the Diourbel, Fatick, and Kaolack regions of Senegal: feasibility of the method of impression cytology with transfer.

The evaluation of the prevalence of ophthalmological diseases and vitamin A deficiency in Senegalese preschool-aged children enabled us to confirm the method of impression cytology with transfer (ICT) and to assess the impact of ophthalmological diseases on the cytological appearance of conjunctival cells. A simplification of the ICT method consisted of transferring cells present on a strip of paper to a glass slide by finger pressure. Harris-Schorr staining of the sample papers confirmed the results obtained by the transfer. Inflammatory trachoma influenced the results of the test. This simple method will prove very helpful for detection of vitamin A deficiency in children in underdeveloped areas.

Child↗
PubMed1991

Prevalence of malnutrition and vitamin A deficiency in the Diourbel, Fatick, and Kaolack regions of Senegal: epidemiological study.

The purpose of our study was to determine the prevalence of protein-calorie malnutrition (PCM), ocular diseases, and vitamin A deficiency in preschool children selected at random in a rural zone of the groundnut belt of Senegal. The prevalence of PCM was 37.1% (95% CI 33.8-40.2%) according to the Waterlow classification, with a majority of stunting, and prevalence of hypovitaminosis A was estimated to be 11.4% (95% CI 9.3-13.5%) by using impression cytology. Furthermore, 19.4% (95% CI 15.8-22.0%) of the children might be defined at risk of deficiency. The prevalence of Bitot's spots was equal to 0.2% (95% CI 0.03-0.9%). A problem of PCM associated with a health-endangering vitamin A deficiency existed.

Anthropometry↗
PubMed1991

Prevalence of malnutrition and vitamin A deficiency in the Diourbel, Fatick, and Kaolack regions of Senegal: a controlled study.

Two hundred and six Senegalese preschool children included in an epidemiological study were selected by their results from impression cytology with transfer (ICT) for assessment of their nutritional state by means of biological variables and for assessment of the diagnostic values of the ICT. A problem of protein-calorie malnutrition existed (transthyretin and retinol-binding protein concentrations were low) associated with vitamin A deficiency (retinol concentrations were low). The sensitivity and specificity of the ICT defined with respect to retinol (threshold fixed at 0.35 mumol/L) varied with the classification criteria of ICT and seemed to be fairly insensitive but specific.

C-Reactive Protein↗
PubMed1991

Nucleotide sequences specific for Tn1545-like conjugative transposons in pneumococci and staphylococci resistant to tetracycline.

The distributions of tet(M) and conjugative transposons related to Tn1545 were studied by hybridization in 47 clinical isolates of Streptococcus pneumoniae resistant to tetracycline. Resistance to tetracycline was always associated with resistance to minocycline and was due to the presence of the tet(M) gene. Association of tet(M) with int-Tn, the gene encoding the protein required for the movements of Tn1545-like transposons, was found in all but one strain of S. pneumoniae. In contrast, int-Tn was detected in only 2 of 37 strains of Staphylococcus spp. harboring tet(M).

Base Sequence↗
PubMed1990

Transferable plasmid-mediated antibiotic resistance in Listeria monocytogenes.

A strain of Listeria monocytogenes, isolated from a patient with meningoencephalitis, was resistant to chloramphenicol, erythromycin, streptomycin, and tetracycline. The genes conferring resistance to these antibiotics were carried by a 37-kb plasmid, pIP811, that was self-transferable to other L monocytogenes cells, to enterococci-streptococci, and to Staphylococcus aureus. The efficacy of transfer and the stability of pIP811 were higher in enterococci-streptococci than in the other gram-positive bacteria. As indicated by nucleic acid hybridisation, the genes in pIP811 conferring resistance to chloramphenicol, erythromycin, and streptomycin were closely related to plasmid-borne determinants that are common in enterococci-streptococci. Plasmid pIP811 shared extensive sequence homology with pAM beta 1, the prototype broad host range resistance plasmid in these two groups of gram-positive cocci. These results suggest that emergence of multiple antibiotic resistance in Listeria spp is due to acquisition of a replicon originating in enterococci-streptococci. The dissemination of resistance to other strains of L monocytogenes is likely.

Chloramphenicol Resistance↗
PubMed1990

The integration-excision system of the conjugative transposon Tn 1545 is structurally and functionally related to those of lambdoid phages.

Excision of Tn1545 and related conjugative transposons of Gram-positive bacteria occurs by reciprocal site-specific recombination between non-homologous regions of the transposon-target junctions. Excisive recombination requires two transposon-encoded proteins designated Xis-Tn and Int-Tn. We have shown that, following excision, Tn1545 is a circular structure with ends separated by either of the two hexanucleotides that were present at the transposon-target junctions. Using a trans-complementation assay, we have demonstrated that Int-Tn is able to catalyse in vivo integration of a circular intermediate of Tn1545 defective for integration and excision. comparison of integration sites suggests that limited sequence homology at the vicinity of the recombining sites is required for integration of the element. These data support the hypothesis that the integration/excision systems of conjugative transposons from Gram-positive cocci and of lambdoid phages from Gram-negative bacilli have evolved from a common ancestor.

Bacteriophage lambda↗
PubMed1990

Gene homogeneity for aminoglycoside-modifying enzymes in gram-positive cocci.

Aminoglycoside-resistant strains of Staphylococcus and Enterococcus, approximately 500 of each, were screened by dot blot hybridization for the presence of genes encoding aminoglycoside-modifying enzymes. The MICs of various aminoglycosides for the strains were determined, and the enzyme contents of the cells were inferred from the resistance phenotypes. The agreements (in percent) of the hybridization results with the deduced enzyme contents for Staphylococcus and Enterococcus species were, respectively, 80 and 87.6 for ANT(6) (aminoglycoside nucleotidyltransferase), 99.8 and 100 for both APH(3') (aminoglycoside phosphotransferase) and APH(2")-AAC(6') (aminoglycoside acetyltransferase), and 100 and 100 for ANT(4'). The weak correlation obtained with the probe for ANT(6) was due to the fact that gram-positive cocci can also be streptomycin resistant by synthesis of APH(3") or ANT(3")(9) and by ribosomal mutation. The remaining probes appeared to be specific: they hybridized with all the resistant clinical isolates but not with the susceptible strains. These results indicate that, except for streptomycin, nucleic acid hybridization is a valid approach for the detection and characterization of aminoglycoside resistance in gram-positive cocci.

Acetyltransferases↗