PubMed Health⌕ Search

Biomedical subjects

B Mercier

Publications and source records attributed to B Mercier.

At least 91 records · Page 5Linked to original sources
PubMed1995

[Evolution of breathing pattern and ventilation at maximal exercise during growth. Definition of reference values].

The aim of the study was to define the changes of parameters of breathing pattern and ventilation (VE) as a function of age during maximal exercise in children. A multi-longitudinal survey was conducted in forty four untrained schoolboys, divided in three groups with initial age of 11.2 years for group I, 12.9 years for group II, and 14.9 for group III. These children were subsequently followed three years ago at the same period. The range age was thus 11.2 to 16.9 years. This study showed that, during growth, ventilation (VE max), tidal volume (VT max) and mean inspiratory flow (VT/TI max) increased significantly with age, that inspiratory frequency (f max) decreased, that inspiratory, expiratory and total time of the respiratory cycle (TI max, TE max, TTOT max) increased slightly and that the inspiration fraction (TI/TTOT max) was identical at 11 and 17 years. Furthermore we observed that the peak height velocity and peak tidal volume velocity took place at the same age, i.e., 14 years and that those of weight and VT/TI at the same age of 15 years. In conclusion, this study allowed us to define reference values for breathing pattern at maximal exercise in sedentary boys and to specify the relation between growth and parameters of breathing pattern in these children.

Adolescent↗
PubMed1994

Visual pontocerebellar projections in the macaque.

The cerebellum plays an important role in the visual guidance of movement. In order to understand the anatomical basis of visuomotor control, we studied the projection of pontine visual cells onto the cerebellar cortex of monkeys. Wheat germ agglutinin horseradish peroxidase was injected into the dorsolateral pons two monkeys. Retrogradely labelled cells were mapped in the cerebral cortex and superior colliculus, and orthogradely labelled fibers in the cerebellar cortex. The largest number of retrogradely labelled cells in the cerebral cortex was in a group of medial extrastriate visual areas. The major cerebellar target of these dorsolateral pontine cells is the dorsal paraflocculus. There is a weaker projection to the uvula, paramedian lobe, and Crus II, and a sparse but definite projection to the ventral paraflocculus. There are virtually no projections to the flocculus. There are sparse ipsilateral pontocerebellar projections to these same regions of cerebellar cortex. In nine monkeys, we made small injections of the tracer into the cerebellar cortex and studied the location of retrogradely filled cells in the pontine nuclei and inferior olive. Injections into the dorsal paraflocculus or rostral folia of the uvula retrogradely labelled large numbers of cells in the dorsolateral region of the contralateral pontine nuclei. Labelled cells were found ipsilaterally, but in reduced numbers. Injections outside of these areas in ventral paraflocculus or paramedian lobule labelled far fewer cells in this region of the pons. We conclude that the principal source of cerebral cortical visual information arises from a medial group of extrastriate visual areas and is relayed through cells in the dorsolateral pontine nuclei. The principal target of pontine visual cells is the dorsal paraflocculus.

Animals↗
PubMed1994

Isosteric phosphonate analogs of ET-16-OMe. Synthesis and biological evaluation of the enantiomers of 2'-(trimethylammonio)ethyl 4-(hexadecyloxy)-3-methoxybutanephosphonate and 2'-(trimethylammonio)ethyl 4-(hexadecylthio)-3-methoxybutanephosphonate.

The enantiomers of two isosteric phosphonate analogs of the ether-linked antitumor agent 1-O-octadecyl-2-O-methyl-sn-glycero-3-phosphocholine (ET-18-OMe) were synthesized and evaluated for their cytotoxicity against various mouse leukemic cell lines in vitro and in vivo. The key step in the synthesis of the alkyloxy and alkylthio analogs (1 and 2, respectively) is the opening of an epoxide [hexadecyl 2-oxiranylmethyl ether (4) or hexadecyl 2-oxiranylmethyl thioether (8)] by LiCH2P(O)(OMe)2 using BF3.Et2O in tetrahydrofuran at low temperature. The cytotoxic activities of the hexadecyloxy and hexadecylthio phosphonate analogs of ET-18-OMe (1 and 2) against the murine leukemias WEHI-3B,L1210, and P388 were similar, indicating that substitution of a sulfur atom for oxygen in the long-chain ether does not result in a significant difference in cytotoxicity. The IC50 values of 1 and 2 were in the range of 1-5 microM. Alkyloxy phosphonate 1 was highly effective in inhibiting the growth of WEHI-3B and P388 tumors implanted in BALB/C mice. The alkyloxy and alkylthio phosphonates 1 and 2 prolonged the survival of CD1 mice bearing L1210 tumors. The antitumor activities of the phosphonate analogs of ET-18-OMe in these in vitro and in vivo studies were independent of chirality, consistent with previous studies with the enantiomers of 1-O-hexadecyl-2-O-methyl-sn-glycero-3-phosphocholine.

Animals↗
PubMed1994

Identification of three novel mutations (457 TAT-->G, D192G, Q685X) in the Slovenian CF patients.

Chromosomes from a cohort of 60 Slovenian families, corresponding to the 121 cystic fibrosis (CF) chromosomes available, were fully scanned for mutations in the coding sequence of the cystic fibrosis transmembrane conductance regulator (CFTR) gene (The 60 families yielded 121 CF alleles because the mother of one patient was also affected). This corresponds to the 27 exons and intron/exon boundaries that have been studied in chromosomes carrying unidentified alleles. As a result of this survey 84% of the alleles are now clearly identified and we describe in this paper three novel mutations (457 TAT-->G, D192G, and Q685X).

Alleles↗
PubMed1994

Retrospective study of the cystic fibrosis transmembrane conductance regulator (CFTR) gene mutations in Guthrie cards from a large cohort of neonatal screening for cystic fibrosis.

The cystic fibrosis transmembrane conductance regulator (CFTR) gene encodes a cAMP-activated chloride channel, and in individuals with both alleles of the gene mutated, symptoms of CF disease are manifest. With more than 300 mutations so far described in the gene the profile of mutant alleles in a population is specific to its ethnic origin. For an analysis with an unbiased recruitment of the CF alleles in neonates of similar origin (Normandy, France), we have retrospectively analyzed the Guthrie cards of affected newborns, diagnosed by the immunoreactive trypsinogen (IRT) assay. Analysis of the 27 exons of the CFTR gene using a GC clamp denaturing gradient gel electrophoresis (DGGE) assay has enabled us to identify over 96% of the mutated alleles. Two of these were novel mutations. We would like to propose this strategy as an efficient method of retrospective molecular genetic diagnosis that can be performed wherever Guthrie cards can be obtained. Knowledge of rare alleles could be a prerequisite for CF therapy in the future.

Base Sequence↗
PubMed1994

Complete detection of mutations in cystic fibrosis patients of Native American origin.

An increased incidence of cystic fibrosis (CF) has been reported in some populations of Native Americans of the Southwest such as the Pueblo, which is a genetic isolate. As the most common mutation found in Caucasians (delta F508) was absent and only one chromosome carried the G542X mutation, we decided to analyze the entire coding sequence of the CFTR gene in eight Pueblo CF patients. We have identified four different mutations: G542X, R1162X, 3849+10kbC-->T, and D648V that account for these 16 haplotypes. The R1162X was found on 11 chromosomes. Using intragenic microsatellites, we have compared the haplotypes of those chromosomes to those of Italian origin where the R1162X mutation was initially reported. These haplotypes turned out to be identical, suggesting a common origin and an admixture with Italian or Spanish settlers, followed by typical founder effect. In contrast the 3849+10kbC-->T mutation, which was found on three chromosomes, is associated with different haplotypes than those on chromosomes carrying the same mutation in Caucasians. A novel mutation, D648V, observed on one chromosome has not been found outside the Pueblo population.

Base Sequence↗
PubMed1994

Effects of 2-chloropropionate on venous plasma lactate concentration and anaerobic power during periods of incremental intensive exercise in humans.

We investigated the effects of a stimulation of pyruvate dehydrogenase (PDH) activity induced by 2-chloropropionate (2-CP) on venous plasma lactate concentration and peak anaerobic power (W an, peak) during periods (6 s) of incremental intense exercise, i.e. a force-velocity (F-v) test known to induce a marked accumulation of lactate in the blood. The F-v test was performed twice by six subjects according to a double-blind randomized crossover protocol: once with placebo and once with 2-CP (43 mg.kg-1 body mass). Blood samples were taken at ingestion of the drug, at 10, 20, and 40 min into the pretest period, at the end of each period of intense exercise, at the end of each 5-min recovery period, and after completion of the F-v test at 5, 10, 15, and 30 min. During the F-v test, venous plasma lactate concentrations with both placebo and 2-CP increased significantly when measured at the end of each period of intense exercise (F = 33.5, P < 0.001), and each 5-min recovery period (F = 24.6, P < 0.001). Venous plasma lactate concentrations were significantly lower with 2-CP at the end of each recovery period (P < 0.01), especially for high braking forces, i.e. 8 kg (P < 0.05), 9 kg (P < 0.02), and maximal braking force (P < 0.05). After completion of the F-v test, venous plasma lactate concentrations were also significantly lower with 2-CP (P < 0.001). The percentage of lactate decrease between 5- and 30-min recovery was significantly higher with 2-CP than with the placebo [59 (SEM 4)% vs 44.6 (SEM 5.5)%, P < 0.05]. Furthermore, W an, peak was significantly higher with 2-CP than with the placebo [1016 (SEM 60) W vs 957 (SEM 55) W, P < 0.05]. In conclusion, PDH activation by 2-CP attenuated the increase in venous plasma lactate concentration during the F-v test. Ingestion of 2-CP led to an increased W an, peak.

Adult↗
PubMed1994

Identification of six novel mutations in the CFTR gene of patients from Bulgaria by screening the twenty seven exons and exon/intron boundaries using DGGE and direct DNA sequencing.

The CFTR gene, in which more than 300 mutations have been described, displays a spectrum of mutations which varies according to ethnic and geographic origin of patients. In this paper we report an exhaustive study of the 27 exons and exon/intron boundaries of a sample of 35 CF patients from Bulgaria which is situated in the south east of Europe. We have used denaturing gradient gel electrophoresis assay followed by DNA sequencing and we report the identification of six previously undescribed CFTR alleles.

Amino Acid Sequence↗
PubMed1994

HLA-DRB and -DBQ typing by PCR amplification using sequence-specific primers (PCR-SSP): assessment after 1 year of routine use by three laboratories.

Using sequence-specific amplifications, a practical and fast technique for DRB and DQB typing has been developed. The primers are chosen in order to amplify groups of alleles corresponding to the same serological specificity. In a second step, precise allelic determination is obtained by studying the restriction fragment length polymorphism of the PCR products. The experience of three laboratories using this technique in the context of organ or bone marrow transplantation is reported.

Alleles↗
PubMed1994

Association of 1078 del T cystic fibrosis mutation with severe disease.

Apart from the high frequency of the delta F508 mutation (81.81%) in Breton cystic fibrosis chromosomes, one mutation, 1078 del T, is also observed frequently (4.96%) in this group, in comparison with the rest of the French where it occurs with a frequency of 0.57%. These two mutations account for more than 86.5% of the total CF mutations identified on Breton chromosomes. We have conducted an unblinded retrospective analysis of 25 patients with the 1078 del T mutation and compared their phenotypes with those of a group of 70 delta F508 homozygous patients. Both groups of patients had the same ethnic origin and were regularly attending the same CF centre in Brittany, which makes this sample highly homogeneous despite the small size. The 1078 del T mutation appeared to be associated with severe presentation of the disease with, however, a trend to reduced mortality and less Pseudomonas aeruginosa colonisation.

Adolescent↗
PubMed1994

A cluster of cystic fibrosis mutations in exon 17b of the CFTR gene: a site for rare mutations.

Intensive screening has improved our understanding of the profile of mutations in the CFTR gene in which more than 400 mutations have been detected to date. In collaboration with several European laboratories we are involved in such analysis. We have identified 14 new mutations in exon 17b of CFTR, having analysed 780 CF chromosomes, and have compared the frequency of mutations in this exon with that of other regions of the CFTR gene. The results obtained indicate an accumulation of mutations, not only in regions encoding the two nucleotide binding folds, but also in those encoding transmembrane domains of the CFTR gene, in particular exon 17b.

Cystic Fibrosis↗
PubMed1994

[Cystic fibrosis gene mutations in the West of France: clinical application].

The cystic fibrosis transmembrane conductance regulator (CFTR) gene, responsible for the cystic fibrosis phenotype when both alleles are mutated, was cloned and sequenced in 1989. Since then, more than 400 mutations have been reported in the gene, although most of these are rare. We have systematically analysed the entire coding sequence of the CFTR gene in a cohort of patients originating from the West of France (Caen, Brest and Nantes). More than 450 CF children, 914 chromosomes in all, have been exhaustively studied in the three centers. We have been able to characterize more than 90% of the mutations, respectively 93.5%, 99% and 95.8%. Despite the large diversity in the CFTR mutations occurring in CF patients from this area, these results can help to improve genetic counselling, prenatal diagnosis as well as our understanding of the molecular basis of the pathophysiology of cystic fibrosis.

Child↗
PubMed1993

TP53 gene mutation profile in esophageal squamous cell carcinomas.

Esophageal squamous cell carcinoma is a form of cancer occurring most commonly in males, particularly those living in some areas of Asia, Africa, and western Europe. In some of these tumors, a sequence alteration has been identified in the coding region of the TP53 gene which is known to inactivate the tumor suppressor function of its product. Using a GC clamp (i.e., a GC rich domain) denaturing gradient gel electrophoresis assay we have been able to identify sequence modifications in 27 of the 32 tumor samples analyzed (84%). Most of the mutations occur in exon 6, a region of the gene which has not previously been reported as being a hot spot for the mutations of other cancers. Twelve of the mutations reported here have not been described in other types of tumors and these consist mostly of frameshift or splice mutations. The distribution of mutations [transitions (45%), transversions (34%), and frameshift (21%)] suggests that the etiological contribution of genotoxic factors might be complex and might associate different exogenous and endogenous mutagen exposures.

Adult↗