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Biomedical subjects

J C Nicolas

Publications and source records attributed to J C Nicolas.

At least 127 records · Page 7Linked to original sources
PubMed1986

Aromatase activity in human skin fibroblasts: characterization by an enzymatic method.

Human skin fibroblasts were incubated for 24 h with 10(-6) M androstenedione and the estrone + estradiol released in the culture medium were measured by an enzymatic assay. Aromatase activity was expressed as pmol (estrone + estradiol) formed in the medium per mg cell protein per day. Using this method we were able to investigate the kinetic properties of aromatase in different cell strains and its stimulation by dexamethasone. Values of 92 nM and 9.1 pmol/mg protein/day were obtained respectively for Km and Vmax in cultured fibroblasts derived from genital skin of normal prepubertal subjects. In patients with complete androgen insensitivity syndrome CAIS, the Km was 156 nM and the Vmax 42 pmol/mg protein/day. Aromatase activity varied from 7.9 +/- 1.2 pmol/mg protein/day (mean +/- SD; n = 19) in normal prepubertal boys to 24.5 +/- 4.7 pmol/mg protein/day (mean +/- SD; n = 11) in those from normal postpubertal boys. The values were even higher in fibroblasts cultured from genital skin of prepubertal patients with CAIS. Cell concentrations did not modify the pattern of estrogen formation and aromatase activity did not vary with serial subcultures. The stimulatory effect of dexamethasone on aromatase activity in cultured fibroblasts was measured after preincubation of the cells for 48 h with dexamethasone, by determining estrogen formation after 24 h incubation of the cells with androstenedione 10(-6) M using this enzymatic method. This data suggest that aromatase activity measured in cultured fibroblasts could be a useful tool for studying extraglandular estrogen formation in physiological and pathological conditions.

Adipose Tissue↗
PubMed1986

Effects of estradiol and indomethacin on the contractile activity of the isolated rat uterus.

The effects of estradiol (E2) on uterine contractility have been studied by continuous monitoring of the contraction of the whole horn and simultaneous determination of the production of prostaglandins (PG). In 70-minute experiments, uterine horns of ovariectomized rats released more prostaglandin E (PGE2) into the bath medium at the beginning (35 pg/min/mg) than at the end of incubation (4 pg/min/mg). However, the decrease in the contraction frequency (CF) was not as large (15%). Estradiol treatment decreased the uterine production of PGE2 and, at low Ca concentrations in the bath medium, it completely abolished spontaneous contractions. Prostaglandin synthesis in the whole organ of ovariectomized rat was inhibited by indomethacin. Spontaneous contractions decreased only at indomethacin concentrations 10 fold higher than those needed to obtain 90% inhibition of prostaglandin synthesis. The effect of high concentrations of indomethacin (10(-5)M) on the CF was calcium-dependent and not related to the inhibition of PG synthesis. The decrease in the CF during hormonal treatment does not seem to be correlated with the decrease in PGE2 production.

Animals↗
PubMed1986

Simplified enzyme-linked immunosorbent assay for specific antibodies to respiratory syncytial virus.

A simplified and reliable enzyme-linked immunosorbent assay (ELISA) was applied to the detection of serum antibodies against respiratory syncytial virus (RSV). RSV-infected cells were fixed and dried on 96-well microtiter plates and kept at 4 degrees C. The titers of reference sera were determined by endpoint dilution. A linear relation was found between the titers and the logarithm of absorbance values of sera diluted to 1:1,000 (r = 0.93, P less than 0.001). Measurement of RSV antibodies was done by using a single serum dilution (1:1,000) in conjunction with a standard curve. A strong correlation was found between complement fixation and ELISA results (r = 0.89, P less than 0.001). In addition, the ELISA method exhibited higher titers and a greater sensitivity than did complement fixation, although the applicability of the assay is limited with positive serum samples of low titer.

Animals↗
PubMed1986

Serological characterization of human reassortant rotaviruses.

We analyzed the serological properties of two human wild-type cell culture-adapted rotaviruses (strains 308 and 46) and of 308 X 46 reassortants which were previously obtained and genetically characterized. Strain 308, exhibiting a so-called long RNA pattern, was found to belong to human rotavirus subgroup II, serotype 1, whereas strain 46, exhibiting a so-called short RNA pattern, represented subgroup I, serotype 2. Among the 308 X 46 reassortants we analyzed, two belonged to subgroup II, serotype 1, and exhibited short RNA patterns. This showed that the correlation observed between human subgroups I and II rotaviruses and the short and long electrophoretic patterns is not supported by any molecular basis (i.e., gene segment 10 or 11 was not involved in the subgroup specificity).

Antibodies, Monoclonal↗
PubMed1985

Epidemiology of human rotaviruses in a maternity unit as studied by electrophoresis of genomic RNA.

An epidemiological survey of Rotavirus infections in a maternity unit was carried out between May 1983 and August 1984. Rotaviruses have been detected throughout the survey in 184 of 528 fecal samples obtained from 3 and 6 day-old newborns. Rotavirus excretion could be detected neither from the mothers nor from the medical attendants. Rotavirus RNA was analyzed by polyacrylamide gel electrophoresis. All the strains isolated exhibited the same electropherotype. This result contrasts with the genomic variability amongst Rotavirus strains usually observed in pediatric wards, and is in agreement with some other studies conducted in maternity wards; in these locations Rotavirus infection seems to have a special epidemic status as compared with other communities.

Adult↗
PubMed1985

Ultrasonographic anatomy and diagnosis of fetal uropathies affecting the upper urinary tract. I. Obstructive uropathies.

The authors describe the ultrasonographic anatomy and semiology of allowing detection of the main types of fetal uropathies. The results of the author's personal experience in this domain are compared to data from the literature. Differential features of the uropathies are given and the limitations and practical significance of prenatal and postnatal ultrasonography are discussed.

Diagnosis, Differential↗
PubMed1985

Enzymatic androgen assay: some properties of human placental microsomal aromatase.

The androgen content of biological fluids can be determined after their conversion into estrogens using human placental microsomal aromatase (HPMA). The purpose of this paper is to report some physico-chemical properties of HPMA. Using an accurate, specific and sensitive assay for HPMA, Km values for dehydroepiandrosterone (DHEA), androstenedione and testosterone were found to increase with increasing amount of the detergent (Triton X-100) added. Analysis at substrate concentrations 5-10 times above and below the Km values did not indicate any anomalous kinetic behaviour. Triton X-100, used for enzyme solubilization, significantly decreased the rate of aromatization of the three substrates by increasing their Km values. This effect was more important for testosterone than for androstenedione or DHEA. Using a new protocol for the determination of aromatase activity, kinetic properties of aromatase before and after solubilization are described.

3-Hydroxysteroid Dehydrogenases↗
PubMed1985

Monoclonal antibodies against respiratory syncytial virus and their use for rapid detection of virus in nasopharyngeal secretions.

We developed five monoclonal antibodies against respiratory syncytial virus. Three of these (23A3, 12A4, and 18B2) were used in an indirect fluorescent antibody test, and the results were compared with those of a similar indirect fluorescent test with commercial anti-respiratory syncytial virus serum. The results obtained with antibody 18B2 and commercial anti-respiratory syncytial virus serum were identical, whereas with antibodies 23A3 and 12A4 the incidence of positive identifications was around 50%.

Antibodies, Monoclonal↗
PubMed1985

[Various protocols for determining estrogens by the enzymatic method using estradiol dehydrogenase. Respective procedures and advantages].

Up to now, more than 40.000 determinations of urinary estrogens (E1 + E2) have been carried out in routine clinical analysis by the enzymatic method using estradiol dehydrogenase. This method makes use of the transhydrogenating activity of the placental enzyme: this enzyme transfers hydrogen from NADP to NAD with recycling of the specific substrate (E1 + E2). For several years the necessary reagents have been commercially available in the form of a kit. Nonetheless, various improvements have been made to the measurement of reduced NAD, which accumulates in the reaction medium and is directly proportional to the concentration of the two estrogens. Three protocols are available at present: Spectrophotometric measurement at 340 nm (initial technique); Colorimetric measurement at 492 nm. The pink colour measured arises from the reduction of a tetrazolium salt (INT) by reduced NAD in a coupled system using diaphorase; Measurement by bioluminescence of the light energy liberated on the reduction of flavin derivatives by NADH. The reaction is mediated by various enzymes isolated from marine bacteria (FMN oxidoreductase and luciferase) in the presence of an aliphatic aldehyde (decanal). The procedure for each of these protocols is described as well as the means for controlling the linearity of the reaction. The choice of protocol is determined by the biological fluid available, the speed of response desired and the cost of the analysis.

17-Hydroxysteroid Dehydrogenases↗
PubMed1985

[Chemiluminescence and bioluminescence in clinical analysis. Perspectives of development].

Until now, the methods of analysis by luminescence have not developed greatly in clinical biology because of the instability of the reagents and the absence of a single protocol applicable to a sufficiently wide range of assays. For this reason, the application has been limited to several assays using a specific bioluminescence reaction i.e., the ATP assay (for the measurement of bacterial contamination), and several assays which evaluate NADH production (bile acids, triglycerides, lactate). Research on assay methods that are very specific and very sensitive and do not use radioactive molecules has led to, among other things, the development of new techniques using luminescence reactions. These reactions are of two types: chemiluminescence reactions, which use molecules (luminol, dioxetane, derivatives of acridine and imidazol) that lead to an emission of light under the action of various chemical and enzymatic compounds; bioluminescence reactions produced by specific enzymatic systems (luciferases). Chemiluminescence reactions are used in several immunometric assays. The chemiluminescent marker fixed to the antigen or antibody has a low molecular weight: for this reason it does not lead to a significant modification of immunoreactivity and it is highly stable. Moreover, in certain cases it is possible to use particular properties of these markers (energy transfer, modification of the efficiency of the luminescent reaction) to carry out homogeneous immunometric assays requiring no separation step. Bioluminescence reactions have been less developed, because of the instability of enzymatic systems. However, these reactions are by far the most sensitive of all the detection techniques currently used.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1984

Characterization of monoclonal antibodies and polyclonal immune sera directed against human cytomegalovirus virion proteins.

Four classes of monoclonal antibody-producing cell lines have been obtained that detect human cytomegalovirus virion structural proteins. These antibodies react with (1) a major outer membrane virion glycoprotein(s) gp58-gp130, whose molecular weight varies between strains of cytomegalovirus, (2) a phosphoprotein, pp71, localized inside the virion membrane, (3) a phosphorylated nucleocapsid protein, pp155, and (4) a virion-associated phosphoprotein, pp29. Polyclonal immune human sera react with a large number of virion proteins including those detected by these monoclonal antibodies. These monoclonal antibodies were employed in a radioimmune assay to detect low levels (6 X 10(3) PFU/ml) of human cytomegalovirus in solution and human urine. These antibodies were also employed in a fluorescent antibody format to identify cytomegalovirus-infected cells obtained from human urine and nasopharyngeal aspirates. These reagents provide useful tools for studying the molecular biology of virus replication, for diagnosing cytomegalovirus infections, and for studying virus latency and activation.

Animals↗
PubMed1984

Study of genetic reassortment between two human rotaviruses.

Eight different human rotavirus strains were adapted to replicate in cell culture. In vitro, rotavirus genetic reassortment has been performed between two virus strains, one with a long pattern of segmented genomic RNAs and the other with a short pattern in the electrophoretic mobility of genomic RNAs. This genetic reassortment was detectable despite the lack of selective markers in the parental strains. Moreover, some of the reassorted virus exhibited mixed RNA patterns containing extra genomic RNAs resembling those found in clinical specimens. These viruses with mixed RNA band patterns could segregate their supplementary segments after successive passages in cell culture. Finally it has been shown that classification of genomic segments in long and short electropherotypes should not only be based on their relative size but also by their ability to reassort with the genetically equivalent segment.

Cell Line↗
PubMed1984

Identification of Epstein-Barr virus sequences that encode a nuclear antigen expressed in latently infected lymphocytes.

The Epstein-Barr virus (EBV) BamHI restriction endonuclease fragment K (B95-8 strain) was introduced into a polyoma virus expression vector and used to transfect murine NIH 3T3 cells. An EBV-associated nuclear antigen was detected in these cells in an indirect immunofluorescence test using anti-EBV nuclear antigen-positive human sera. These sera recognized a Mr 88,000 polypeptide in 3T3 cells transfected with the BamHI fragment K-containing polyoma virus plasmid by radioimmunoelectrophoresis. A Mr 88,000 polypeptide also was detected in a B-cell line latently infected with the B95-8 strain of EBV. Plasmids containing insertion and deletion mutations in BamHI fragment K directed the synthesis of truncated forms of the Mr 88,000 polypeptide in 3T3 cells. These data directly demonstrate that the polypeptide identified in EBV-infected lymphocyte lines by anti-EBV nuclear antigen-positive human sera is encoded by the viral genome.

Animals↗
PubMed1984

Survey of human rotavirus propagation as studied by electrophoresis of genomic RNA.

Rotavirus RNA isolated from three different environmental sources during the winter of 1981-1982 was analyzed by polyacrylamide gel electrophoresis. Our results demonstrate the presence of novel RNA patterns, the coexistence of multiple electrophoretic patterns in rotavirus isolated from samples from a given ward, and that spread of a given electropherotype is limited.

Child↗