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V Dumas

Publications and source records attributed to V Dumas.

At least 19 recordsLinked to original sources
PubMed2004

Diversification within grapevine cultivars goes through chimeric states.

Vitis vinifera 'Pinot' clones were analysed at 50 microsatellite loci to assess intravarietal genetic diversity. When analysing leaf tissue DNAs, polymorphism mainly resulted from the appearance of a third allele when two were expected for heterozygous loci in a diploid species. The sequencing of the three microsatellite alleles at two loci has confirmed their simultaneous presence in the leaf tissues. A hypothesis explaining the triallelic profiles at a locus is the presence of a periclinal chimera meristem structure, in which genetically different cell layers coexist. The periclinal chimeric state of two Vitis vinifera 'Pinot gris' clones was confirmed by splitting and analysing the genotypes resulting from L1 and L2 cell layers in progeny derived from self-fertilization, in root tissues, and in plants regenerated from somatic embryogenesis. Prevalence of chimerism in polymorphic clones observed in a collection of 145 accessions belonging to 'Pinot gris', 'Pinot noir', Pinot blanc', 'Pinot meunier', and 'Pinot moure' cultivars was demonstrated. The accumulation of somatic mutations and cell layer rearrangements allowed us to deduce the relationships between the various genotypes and to open a way for understanding the diversification process and the phylogeny in the 'Pinot' group.

Chimera↗
PubMed2001

New molecular marker for Trypanosoma (Duttonella) vivax identification.

Trypanosoma vivax is a widespread hemoparasite in tropical areas and is pathogenic to ruminant domestic livestock as well as wild ruminants. The accurate identification of parasites in both hosts and vectors is crucial for epidemiological studies and disease control programs. We describe here the development of molecular markers specific for T. vivax identification. These markers were used to identify mouthpart infections in field-collected tsetse flies from Cameroon. The markers target the genomic sequence of a species-specific antigen from the bloodstream stages. No cross amplification with other trypanosome species was observed, which makes the markers a reliable tool to detect T. vivax infections, both in hosts and vectors. The PCR-amplified sequence contains a (CA)(n) microsatellite repeat for which 11 different alleles were identified. This microsatellite, which showed high polymorphism, provides a suitable marker for population genetic studies.

Animals↗
PubMed2001

Specific inhibition by hGRB10zeta of insulin-induced glycogen synthase activation: evidence for a novel signaling pathway.

Grb10 is a member of a family of adapter proteins that binds to tyrosine-phosphorylated receptors including the insulin receptor kinase (IRK). In this study recombinant adenovirus was used to over-express hGrb10zeta, a new Grb10 isoform, in primary rat hepatocytes and the consequences for insulin signaling were evaluated. Over-expression of hGrb10zeta resulted in 50% inhibition of insulin-stimulated IRK autophosphorylation and activation. Analysis of downstream events showed that hGrb10zeta over-expression specifically inhibits insulin-stimulated glycogen synthase (GS) activity and glycogen synthesis without affecting insulin-induced IRS1/2 phosphorylation, PI3-kinase activation, insulin like growth factor binding protein-1 (IGFBP-1) mRNA expression, and ERK1/2 MAP kinase activity. The classical pathway from PI3-kinase through Akt-PKB/GSK-3 leading to GS activation by insulin was also not affected by hGrb10zeta over-expression. These results indicate that hGrb10zeta inhibits a novel and presently unidentified insulin signaling pathway leading to GS activation in liver.

Animals↗
PubMed2001

Malignant peripheral nerve sheath tumors associated with neurofibromatosis type 1: a clinicopathologic and molecular study of 17 patients.

OBJECTIVE: To identify potential prognostic factors and criteria for early detection of malignant peripheral nerve sheath tumors associated with neurofibromatosis type 1 (NF1). DESIGN: Retrospective study of malignant peripheral nerve sheath tumors in a cohort of 395 patients with NF1 followed up between October 1, 1988, and January 1, 1999; review of the clinical and histological characteristics of treatment and course; and analysis of p53 mutations and overexpression in tumors. SETTING: Teaching hospital referral neurofibromatosis center for adults. PATIENTS: Seventeen patients with NF1 (9 males and 8 females). Mean +/- SD patient age at diagnosis was 32 +/- 14 years. MAIN OUTCOME MEASURES: (1) Clinical symptoms, (2) comparison of p53 mutations and overexpression in benign vs malignant tumors; and (3) median survival. RESULTS: Twelve patients had high-grade tumors. All tumors except 1 developed on preexisting nodular or plexiform neurofibromas. Pain and enlarging mass were the first and predominant signs. None of the benign tumors displayed significant p53 staining or p53 mutations. Six of 12 malignant tumors significantly overexpressed p53, and 4 of 6 harbored p53 missense mutations. Median survival was 18 months overall, 53 months in peripheral locations, and 21 months in axial locations. CONCLUSIONS: Malignant peripheral nerve sheath tumors are highly aggressive in NF1. They mostly arise from plexiform or nodular neurofibromas. Investigations and deep biopsy of painful and enlarging nodular or plexiform neurofibromas should be considered in patients with NF1. Late appearance of p53 mutations and overexpression precludes their use as predictive markers of malignant transformation.

Adolescent↗
PubMed2000

[Perianal streptococcal dermatitis].

BACKGROUND: Pediatric perianal streptococcal dermatitis (PSD) is a well-defined clinical entity. However, its highly uniform presentation remains surprisingly unrecognized by many practitioners 33 years after its first description. CASE REPORT: A seven-year-old girl had a three-week history of perianal and vulva redness with well-defined margins. Functional symptoms associated perirectal tenderness and pain during defecation, which was responsible for constipation. At onset she also presented with a sore throat, which resolved spontaneously, and she had been complaining for a few days about a perioral impetigo. She received mycostatin unsuccessfully for an alleged candidiasis. Positive cultures for group A beta-hemolytic streptococci from both perirectal and perioral swabs confirmed the diagnosis of PSD. Therapy with amoxicillin (50 mg/kg/d) was prescribed for ten days. Perianal lesions were cleared by day 2. CONCLUSION: Since PSD can masquerade as candidiasis, psoriasis, seborrheic dermatitis, inflammatory bowel disease or even sexual abuse, it remains an underdiagnosed entity. This situation leads to delayed diagnosis and treatment which in turn might increase the frequency of secondary complications related to streptococcal infections (i.e., post-streptococcal acute nephritis and rheumatism, guttate psoriasis, etc.).

Amoxicillin↗
PubMed1999

The treatment of mild pemphigus vulgaris and pemphigus foliaceus with a topical corticosteroid.

Seven patients with mild pemphigus vulgaris (n = 3) or pemphigus foliaceus (n = 4) were treated with a very potent topical corticosteroid alone. Clobetasol propionate 0.05% cream was applied to mucosal lesions and involved skin twice a day for at least 15 days, then progressively tapered. Pemphigus was considered to be controlled if healing of lesions was obtained, with a 75% decrease in the number of new lesions per week without addition of any systemic treatment. In all seven patients, the disease was controlled initially with healing of cutaneous lesions within 15 days, while healing of mucosal lesions took at least 1 month. In four patients, remission was maintained with topical corticosteroid alone for a mean 19-month follow-up. In three patients, relapse occurred after 2-11 months, requiring a systemic treatment.

Administration, Topical↗
PubMed1999

[Nasal involvement in atrophic polychondritis. A case report].

Relapsing polychondritis is a rare and little known inflammatory disease. The case of a 29-year-old woman who presented with a one-year history of saddle nose is discussed in this article. After waiting for one year, rhinoplasty was decided, with a good result at the 18th month. We prefer to use a calvarial bone graft for this disease and to only operate under stable and minor conditions.

Adult↗
PubMed1998

Microsatellite markers for genetic population studies in Glossina palpalis gambiensis (Diptera: Glossinidae).

Little is known about intraspecific variability in tsetse flies and its consequences for vectorial capacity. Microsatellite markers have been developed for Glossina palpalis gambiensis. Three loci have been identified and showed size polymorphisms for insectarium samples. G. palpalis gambiensis from Burkina Faso were also subjected to PCR to investigate then genetic variability. Amplifications were observed in different species belonging to the palpalis group. These molecular markers will be useful to estimate gene flow within G. palpalis gambiensis populations and analysis could be extended to related species.

Animals↗
PubMed1998

Polymorphic microsatellites in Simulium damnosum s.l. and their use for differentiating two savannah populations: implications for epidemiological studies.

In West Africa, Onchocerca volvulus, the cause of human onchocerciasis, is transmitted by sibling species of the Simulium damnosum complex. Little is known about blackfly intraspecific variability and its consequences on vectorial capacity. This study reports the use of microsatellite markers for differentiating populations of S. damnosum s.l. Five microsatellite loci were characterized and used to analyze individuals from two savannah populations in Mali, 120 km apart. Four loci were highly polymorphic, having 8-12 alleles per locus and gene diversities ranging from 77.9 to 88.2%. A significant heterozygote deficiency was observed in the two populations. This may arise from inbreeding, population structure (the Walhund effect), or the presence of null alleles. To test this last hypothesis, new primers were designed for two loci and used to analyze homozygous individuals. After correcting for null alleles, heterozygote deficit persisted. Population subdivision in the two foci remains the most likely explanation. Our results indicate that microsatellite markers could differentiate fly populations, making them valuable tools for the study of population genetic structure.

Alleles↗
PubMed1997

Microsatellite markers for genetic population studies in Glossina palpalis (Diptera: Glossinidae).

Little is known about tsetse intraspecific variability and its consequences on vectorial capacity. Since isoenzyme analyses revealed little polymorphism, microsatellite markers have been developed for Glossina palpalis gambiensis species. Three loci have been identified and showed size polymorphisms for insectarium samples. Moreover, amplifications were observed in different species belonging to palpalis group. These molecular markers will be useful to estimate gene flow within G. p. gambiensis populations and analyses could be extended to related species.

Africa, Western↗
PubMed1997

Early signaling events triggered by peroxovanadium [bpV(phen)] are insulin receptor kinase (IRK)-dependent: specificity of inhibition of IRK-associated protein tyrosine phosphatase(s) by bpV(phen).

Peroxovanadiums (pVs) are potent protein tyrosine phosphatase (PTP) inhibitors with insulin-mimetic properties in vivo and in vitro. We have established the existence of an insulin receptor kinase (IRK)-associated PTP whose inhibition by pVs correlates closely with IRK tyrosine phosphorylation, activation, and downstream signaling. pVs have also been shown to activate various tyrosine kinases (TKs) that could participate in activation of the insulin-signaling pathway. In the present study we have sought to determine whether pV-induced IRK tyrosine phosphorylation requires the intrinsic kinase activity of the IRK, and whether IRK activation is necessary to realize the early steps in the insulin-signaling cascade. To address this we evaluated the effect of a pure pV compound, bis peroxovanadium 1,10-phenanthroline [bpV(phen)], in HTC rat hepatoma cells overexpressing normal (HTC-IR) or kinase-deficient (HTC-M1030) mutant IRKs. We showed that at a dose of 0.1 mM, but not 1 mM, bpV(phen) induced IRK-dependent events. Thus, 0.1 mM bpV(phen) increased tyrosine phosphorylation and IRK activity in HTC-IR but not HTC-M1030 cells. Tyrosine phosphorylation of insulin signal-transducing molecules was promoted in HTC-IR but not HTC-M1030 cells by bpV(phen). The association of p185 and p60 with the src homology-2 (SH2) domains of Syp and the p85-regulatory subunit of phosphatidylinositol 3'-kinase was induced by bpV(phen) in HTC-IR, but not in HTC-M1030 cells, as was insulin receptor substrate-1-associated phosphatidylinositol 3'-kinase activity. Thus autophosphorylation and activation of the IRK by bpV(phen) is effected by the IRK itself, and the early events in the insulin- signaling cascade follow from this activation event. This establishes a critical role for PTP(s) in the regulation of IRK activity. bpV(phen) could be distinguished from insulin only in its ability to activate ERK1 in HTC-M1030 cells, thus indicating that this event is IRK independent, consistent with our previous hypothesis that bpV(phen) inhibits a PTP involved in the negative regulation of mitogen-activated protein kinases.

Animals↗
PubMed1996

Improvement of blood and fly gut processing for PCR diagnosis of trypanosomosis.

We have adapted a simple and efficient technique to detect trypanosomes in human blood, without DNA purification, and increased the sensitivity threshold to 1 parasite in 1 ml. We have then applied it for detection of parasites in midguts of tsetse flies, negative by microscopy. This technique has been developed for field conditions and could greatly facilitate epidemiological studies.

Animals↗
PubMed1995

Induction of tolerance by administration of hapten-immunoglobulin conjugates is associated with decreased IL-2 and IL-4 production.

Intravenous administration of trinitrophenyl-modified isologous immunoglobulin-induced nonresponsiveness to subsequent epicutaneous painting of sensitizing doses of trinitrochlorobenzene. Isologous immunoglobulin with various degrees of trinitrophenyl substitution (11.2, 14.3, 27 and 47.3) prevented sensitization. The suppression of contact hypersensitivity was dependent on the dose of tolerogen and was hapten specific. Tolerance was inducible in mice of the strains CBA (H-2k), C57BL/6 (H-2b), and DBA/2 (H-2d) but not in Balb/C (H-2d) mice, suggesting that this trait maps outside the murine major histocompatibility complex. Tolerance induced by trinitrophenyl-modified immunoglobulin was associated with decreased hapten-induced proliferation of draining lymph-node cells. Unlike in other models of tolerance in which a decreased interleukin-2 to interleukin-4 ratio can be observed, administration of tolerizing trinitrophenylated immunoglobulin was associated with deficient hapten-induced release of both interleukin-2 and interleukin-4.

Animals↗
PubMedDate not supplied

The development of the RISK tool for fall prevention.

The authors tailored a 26-item risk assessment tool (RAT) for falls based on a literature review and an analysis of causative factors of falls that had occurred over a 3-month period at the Olin E. Teague VA Medical Center, an 1,100-bed acute medical-surgical, psychiatric, and extended care facility in Temple, TX. The RAT was completed by nursing staff on 10 patient units (four medical, four surgical, and two nursing home units) for all admissions during the period. A 25% sample of the completed RATs was randomly selected (n = 208). Pearson's correlation coefficient was used to identify factors that would most likely predict falls from the RATs of the randomly selected group and of the patients who fell (n = 78). Only 4 of the 26 items were statistically related to falls. Based on findings from this study, the RAT was shortened to the four items and called the RISK (Reassessment Is Safe "Kare") tool.

Accidental Falls↗