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Biomedical subjects

J C Nicolas

Publications and source records attributed to J C Nicolas.

At least 163 records · Page 9Linked to original sources
PubMed1981

Mutant carrying deletions in the two simian virus 40 early genes.

We isolated a simian virus 40 mutant, dl2194, which carried deletions in both early genes. One deletion removed 234 base pairs in the 54/59 region within the small-t-antigen coding sequence and the large-T-antigen gene intron. The second deletion removed 57 base pairs at the C terminus of the large-T-antigen coding sequence (0.20 map unit). dl2194 was a viable mutant, it carried a normal helper function for adenovirus growth on monkey cells, and it displayed the transformation properties of a small-t-antigen-negative single mutant. Therefore, none of the known large-T-antigen functions seemed to be altered by the C-terminal deletion.

Adenoviruses, Human↗
PubMed1980

Coupling of delta 5,3-ketosteroid isomerase to human placental lactogen with intermolecular disulfide bond formation. Use of this conjugate for a sensitive enzyme immunoassay.

An immunoassay for human placental lactogen (HPL) has been developed with the use of hormone labelled with delta 5,3-ketosteroid isomerase. The enzyme is coupled to the antigen via an intermolecular disulfide interchange reaction. HPL-enzyme conjugates are prepared in high yield and purified by affinity chromatography. An enzyme immunoassay using these hormone-enzyme derivatives is compared with radioimmunoassay for determination of HPL in serum.

Animals↗
PubMed1980

Affinity chromatography: a tool for enzyme immunoassay.

Affinity chromatography has been widely used for enzyme purification and for the preparation of antigen-enzyme conjugates. Most enzyme immunoassay use immunoadsorbent (specific or double insolubilized antibodies) which makes automation difficult as centrifugation and washing steps are necessary. We propose affinity chromatography for rapid separation of antigen-enzyme bound to antibodies from free conjugate and its application in enzyme immunoassay. We describe enzyme immunoassays for human placental lactogen and progesterone which use delta 5,3-ketosteroid isomerase as marker and depend upon retention by specific absorbent of enzyme conjugate not bound to antibodies.

Adsorption↗
PubMed1979

Alkylation of estradiol 17 beta-dehydrogenase from human placenta with 3-chloroacetylpyridine--adenine dinucleotide phosphate.

3-Chloroacetylpyridine--adenine dinucleotide phosphate is both active as a hydride acceptor and inactivates estradiol 17 beta-dehydrogenase. This coenzyme analogue behaves like an affinity label. The inactivation kinetics are discussed in relation to those observed with 3-chloroacetylpyridine--adenine dinucleotide. The pH dependence of the rate of inactivation, in combination with determination of the number of reactive cysteine residues, pointed to the alkylation of one cysteine residue/subunit. The stoichiometry was one molecule of dinucleotide per subunit and no cooperativity was detected. When 14C-labeled dinucleotide was used, the 14C label was found mainly in one peptide, accounting for 90% of the incorporated radioactivity, whereas in previous work it had been shown that 3-chloroacetylpyridine--adenine dinucleotide is an affinity reagent which labels three peptides.

17-Hydroxysteroid Dehydrogenases↗
PubMed1979

Enzymatic determination of estradiol and estrone in plasma and urine.

Plasma and urine estradiol and estrone can be determined using the transhydrogenase function of the estradiol dehydrogenase of human placenta: in the conditions described the transhydrogenase activity which is directly related to the estrogen concentration is measured by spectrophotometry. Estrone and estradiol can be determined together or separately if estrone is previously reacted with hydrazine with a limit of sensitivity of 10 picograms in the sample. On urine samples the assay is performed directly without extraction, a simplification which makes the method highly suitable for numerous routine determinations.

Estradiol↗
PubMed1978

[Response to an antiestrogen as a criterion for hormonal sensitivity of endometrial cancer].

A test is described for the evaluation of hormone sensitivity of endometrial cancer in vivo. The concentrations of progesterone and estradiol receptors, and the activities of ornithine-decarboxylase and 17 beta-hydroxysteroid oxido-reductase enzymes have been measured in the tumor, before and after administration of the anti-estrogen tamoxifen. The responses observed, in particular the increase of progesterone receptor, could allow a more rational approach to hormonal therapy of endometrial cancer.

17-Hydroxysteroid Dehydrogenases↗
PubMed1978

Renal transplantation and viral infections. III. Clinical and virological correlations.

Studies of the serological development after 26 renal transplants confirm the high frequency of antibody rises not only against the herpes virus group, but also against other virus groups such as measles, Coxsackie B viruses. These antibody rises correlate with febrile episodes and hepatic dysfunction in which CMV is the most often involved. However, the frequency of antibody rises against various viral antigens without any clinical event to suggest viral etiology; the lack of concomitant virus isolation (except the herpes group), as well as the ocurrence of simultaneous antibody rises against several viruses, all suggest that some of these various antibody rises observed may be related to immunological dysfunction rather than to virus infection.

Antibodies, Viral↗
PubMed1978

Renal transplantation and viral infections. IV. A survey of herpes simplex virus excretion in relation to cellular specific immunity and humoral immunity among renal transplant recipients.

Fourteen renal transplant recipients were screened systematically for HVH virus infection, cellular and humoral HVH immunity and general cellular immunity evaluated by PHA response. This study demonstrates significant correlation between humoral and cellular responses to HVH before graft and virus isolation after graft. This virus excretion occurred simultaneously with a PHA response peak. Neither significant drops in cellular general or specific HVH immune response nor correlation between acute rejection episode and any studied parameters were observed.

Adult↗
PubMed1978

Antiviral activity in sera of patients with influenza infection.

An interferon like activity was investigated in the sera of patients, very early during an Influenza A or B infection. A such substance was significantly more frequent among the patients who shed a Myxovirus Influenza than among the patients without virus isolation in the nasopharynx. The following relations are discussed : either is the interferon production merely associated without effect on the virus level? Or, on the other hand, in some cases is the rate or virus multiplication strictly directed by this interferon production? This study don't allowed to choose one of these hypothesis.

Animals↗