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J Nicoli

Publications and source records attributed to J Nicoli.

At least 19 recordsLinked to original sources
PubMed2001

A genome-wide scan for linkage to human exceptional longevity identifies a locus on chromosome 4.

Substantial evidence supports the familial aggregation of exceptional longevity. The existence of rare families demonstrating clustering for this phenotype suggests that a genetic etiology may be an important component. Previous attempts at localizing loci predisposing for exceptional longevity have been limited to association studies of candidate gene polymorphisms. In this study, a genome-wide scan for such predisposing loci was conducted by using 308 individuals belonging to 137 sibships demonstrating exceptional longevity. By using nonparametric analysis, significant evidence for linkage was noted for chromosome 4 at D4S1564 with a MLS of 3.65 (P = 0.044). The analysis was corroborated by a parametric analysis (P = 0.052). These linkage results indicate the likelihood that there exists a gene, or genes, that exerts a substantial influence on the ability to achieve exceptional old age. Identification of the genes in humans that allow certain individuals to live to extreme old age should lead to insights on cellular pathways that are important to the aging process.

Aged↗
PubMed1997

Homogeneity of yellow fever virus strains isolated during an epidemic and a post-epidemic period in West Africa.

Three strains of yellow fever virus (YFV) were isolated in 1982 in The Ivory Coast, one from a human case and two from Aedes luteocephalus, during and subsequent to an epidemic. The complete genomic sequence of the human strain was determined and compared to that of the 1927 Asibi strain of YFV. The divergence observed was on average of 8.3%, ranging from 5.5 to 11.7% in the coding region. The transitions to transversions ratio was 5.9. Most mutations (84.3%) occurred on the third position of the codons, with synonymous mutations representing 92.5%. However, when partial sequences representing 60% of each genome were compared, homology between the three Ivory Coast strains was greater than 99%. These results demonstrate the homogeneity of the virus strains circulating in different hosts and vectors in a limited geographical region and validate the concept of topotype in viral quasi-species.

Aedes↗
PubMed1993

A study of GABAergic system in Scrapie-infected hamsters after striatal microinoculation of the agent.

Experimental Scrapie in hamster is a simple, reproducible model of prion diseases that occur in humans and animals. Stereotaxic microinoculation (0.5 microliter) of the agent (263 K) into a specific cerebral structure (striatum) in hamster, previously developed in our group, gives the opportunity to further investigate the pathogenesis of these degenerative diseases and to more precisely define the brain areas and the groups of cells more vulnerable to the effects of the agent. In this model, early significant changes of glutamic acid decarboxylase (GAD) activity in striatum suggested a preferential alteration of the GABA system. The present study was focused on the effects of Scrapie agent directly injected into striatum on GABA neurons at the presynaptic level (GABA uptake) and at the postsynaptic level (GABAA receptors). The high-affinity [3H]GABA uptake is not changed in the Scrapie-injected striatum neither in the controlateral site and the kinetics (Km, Vmax) values are not statistically different for control and Scrapie-inoculated animals. The binding of [3H]GABA (Scatchard analysis) to cerebral membranes does not seem to be altered either at the local site of agent inoculation (striatum) neither at distance in the cerebellum: the affinity constant (Kd) to the ligand and the maximal number of receptor sites were of the same magnitude in control and Scrapie animals, but we do not have a statistical analysis. These effects are completely different of those of a neurotoxin. The present data suggest that the effects of prion agent may be very limited and very specific to some cellular mechanisms, without altering the whole cellular machinery, as recently shown in an in vitro model.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Trypsin-dependent production of an antibacterial substance by a human Peptostreptococcus strain in gnotobiotic rats and in vitro.

An antibacterial substance appeared within 1 day in feces of gnotobiotic rats harboring a human intestinal Peptostreptococcus strain. It disappeared when the rat bile-pancreatic duct was ligatured or when the rats ingested a trypsin inhibitor. Anaerobic cultures of the Peptostreptococcus strain in a medium supplemented with trypsin also exhibited an antibacterial activity, which was also inhibited by the trypsin inhibitor. In vitro the antibacterial substance from both feces and culture medium was active against several gram-positive bacteria, including other Peptostreptococcus spp., potentially pathogenic Clostridium spp. such as C. perfringens, C. difficile, C. butyricum, C. septicum, and C. sordellii, Eubacterium spp., Bifidobacterium spp., and Bacillus spp. Whatever the order of inoculation of the strains, a sensitive strain of C. perfringens was eliminated within 1 day from the intestine of rats monoassociated with the Peptostreptococcus strain. These findings demonstrate for the first time that very potent antibacterial substances can be produced through a mechanism involving intestinal bacteria and exocrine pancreatic secretions.

Animals↗
PubMed1991

Presence of PAF-acether in stool of patients with pouch ileoanal anastomosis and pouchitis.

Platelet-activating factor is an endogenous phospholipid produced by a wide variety of inflammatory cells. Platelet-activating factor induces severe pathological changes in various organs and, among numerous potent effects, causes bowel necrosis. Pouchitis is a poorly understood complication of ileoanal pouch anastomosis which occurs in patients who undergo surgery for ulcerative colitis. The aim of this study was to measure ileal or fecal platelet-activating factor and lyso platelet-activating factor contents in normal volunteers (n = 12), in patients with terminal ileostomy (n = 7), and in patients with ileoanal anastomosis (n = 15) (8 patients have pouchitis defined by the presence of ulcerations on the reservoir). Fecal samples were processed and assessed for platelet-activating factor by platelet aggregation assay. The aggregating material was further characterized as platelet-activating factor by the following: inhibition of the platelet aggregation it induced by specific platelet-activating factor receptor antagonist (BN 52021; IHB, Le Plessis Robinson, France); abolition of platelet aggregation after incubation with phospholipase A2 but not with lipase A1; and retention time on high-performance liquid chromatography. Stool platelet-activating factor content (in nanograms per gram of stool, mean +/- 1SD) was significantly increased in patients with pouchitis (22.2 +/- 16 ng/g) compared with patients with normal reservoir (1.59 +/- 0.63 ng/g, P less than 0.01), terminal ileostomy (0.59 +/- 0.43 ng/g, P less than 0.01), and healthy controls (0 +/- 0 ng/g of stool, P less than 0.001). Lyso platelet-activating factor (nanograms per gram of stool) was increased in patients with pouchitis (10,704 +/- 5499 ng/g) compared with patients with normal reservoir (4721 +/- 4549 ng/g of stool, P less than 0.05), terminal ileostomy (3042 +/- 4019 ng/g, P less than 0.02), and healthy volunteers (128 +/- 107 ng/g, P less than 0.001). In patients with ileoanal anastomosis and pouchitis, increased platelet-activating factor production could be implicated in the inflammation and ulcerations observed in the reservoir.

Adult↗
PubMed1979

[Cellular differentiation and malignant transformation (author's transl)].

The mechanisms and determination of differentiation of normal and cancer cells were compared by distinguishing them from the phenomena of regulation, retrodifferentiation and maturation. Reference is made to the laws of order in time and space which are superimposed on the common genetic code during the various types of differentiation. In conclusion, the particular mechanisms of malignant differentiation are discussed by taking melanoma and tumor formation by papova-viruses as examples.

Animals↗
PubMed1977

Toxicity of radiolytic products from 60 Co-treated starch on microorganisms.

The radiolytic products of a 60Co-irradiated starch are sensitive to the action of catalase, peroxidase and ferrous ions: extracts of irradiated starch so treated loss their toxicity for Escherichia coli. After eliminating the reductones, the toxic activity is attributed to the peroxides and more especially to hydrogen peroxide. Artificial reconstitution of an irradiated starch extract confirms this conclusion and reveals a secondary toxic action of formaldehyde.

Catalase↗
PubMed1975

[The length of polyadenylic acid tracts of Sindbis virus RNA: the possible existence of two synthetic mechanisms].

The poly (A) tracts of RNA's from viral particles and from replicative complex belong to two classes of 180 and of 60 nucleotides in length. Those of the mRNA are homogenous and around 280 nucleotides in length. The results presented here strongly suggest the possibility of a copying mechanism in the first case and of a posttranscriptional addition in the latter.

Cell Line↗