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Biomedical subjects

F Lambert

Publications and source records attributed to F Lambert.

At least 73 records · Page 4Linked to original sources
PubMed1983

The stimulatory effect of corticotropin on cortisol biosynthetic pathway in guinea-pig adrenocortical cells.

The mechanism of the prolonged stimulatory effect of corticotropin (ACTH) on adrenocortical synthesis of cortisol was studied in guinea-pig adrenocortical cells harvested from control animals and from guinea-pigs submitted 24 h before the sacrifice to a prolonged ether anesthesia in an attempt to induce a release of endogenous ACTH. As a result of this in vivo exposure to endogenous ACTH, the maximal capacity to produce glucocorticoids (by 1 X 10(5) cells incubated during 2 h) in response to ACTH increased from 579 +/- 111 ng (control group) to 915 +/- 143 ng for cells from treated animals, whereas the apparent affinity of the steroidogenic response to ACTH remained unchanged. This hyper-reactivity of cells from anesthetized animals was also evident in the presence of dibutyryl cyclic AMP. Moreover, there was increased conversion of exogenous pregnenolone into cortisol by cells from previously anesthetized animals. It was therefore concluded that ACTH increases in a lasting way the activity of steroidogenic pathway leading to cortisol synthesis by adrenocortical cells at sites distal to cyclic AMP generation. Besides an obvious increase of formation of pregnenolone in response to ACTH, it seems that this ACTH-induced enhancement in the capacity of the steroidogenic response to ACTH also implies a prolonged stimulatory influence of the peptide on the post-pregnenolone steroidogenic pathway leading to cortisol synthesis.

Adrenal Cortex↗
PubMed1983

Competition between ABO and Le gene specified enzymes. I. A Lewis related difference in the amount of A antigen in saliva of A1 and A2 secretors.

Radioimmunoassays were prepared using two anti-A and one anti-B reagents. The specificity of the procedures was assessed with 13 artificial antigens. The amounts of A and B natural antigens in saliva of ABH secretors of known Lewis phenotype were measured with these assays. The results confirmed that the average amount of A antigen is lower in Lewis-positive (Leb) than in Lewis-negative (Led) donors and in A2 than in A1 donors. However, the differences among the four combined A and Lewis phenotypes were only supported by significantly lower amounts of A antigenic determinants in A2Leb as compared to the other three phenotypes (A1Leb, A1Led and A2Led) that had similar amounts of A antigenic determinants. No Lewis-related difference could be detected in the amounts of B antigens between BLeb and BLed donors. The results are discussed in terms of competition between A, B and Lewis-gene-specified enzymes for their common acceptors. The difference in the efficiency of the A2 enzyme as compared to that of the A1 enzyme is proposed as a possible explanation for the A1-A2 phenotypic difference.

ABO Blood-Group System↗
PubMed1983

Competition between ABO and Le gene specified enzymes. II. Quantitative analysis of A and B antigens in saliva of ABH nonsecretors.

One B- and two A-specific radioimmunoassays detected A and B antigenic determinants in saliva of ABH nonsecretors. The A or B antigens found in saliva of nonsecretors had lower efficiency and higher heterogeneity, in the inhibition of the A or B assays, as compared to A or B antigens in saliva of ABH secretors. In the 3 assays, samples of nonsecretor Lewis positive donors (Lea) had less A or B antigens than samples of nonsecretor Lewis negative donors (Lec), suggesting that there is a competition between A or B and Le gene-specified products.

ABO Blood-Group System↗
PubMed1983

H-deficient blood groups of Reunion island. II. Differences between Indians (Bombay Phenotype) and whites (Reunion phenotype).

Two variants of recessive, H-deficient nonsecretor individuals (h/h, se/se) were identified on Reunion Island: (1) H-negative individuals corresponding to the classical Bombay phenotypes (OhO, OhA, OhB, OhAB) who lack completely the H antigen on their red cells; all of them were Indian and had strong anti-H antibodies reacting with normal O and Oh red cells from whites; and (2) H-weak individuals (Oh, Ah, Bh, ABh). This phenotype represented the majority (85%) of the H-deficient phenotypes on Reunion Island, and all of them were white. They had only a weak expression of the H antigen and showed small but detectable amounts of ABH antigens on their red cells. Their anti-H antibodies reacted with normal O erythrocytes, but failed to react with Oh red cells, regardless of the ethnic origin of the donor. They were all from the same geographical area on the Island (Cilaos) and showed homogeneous titers of anti-H antibodies in sera. We propose to call this particular variant of weak H phenotype, belonging to the so-called para-Bombay series, Reunion.

ABO Blood-Group System↗
PubMed1982

Distribution of H type 1 and H type 2 antigenic determinants in human sera and saliva.

A radioimmunoassay specific for the H type 1 antigenic determinant demonstrated that the H type 1 antigen is under the strict control of the Se gene in both serum and saliva. Similar amounts of H type 1 antigenic determinants were found in saliva from Se/-, le/le donors and in saliva from Se/-, Le/- donors. However, sera from Se/-, le/le donors were about 100 times more efficient in inhibiting the H type 1 assay than were sera from Se/-, Le/- donors. A radioimmunoassay, based on the binding of Ulex europaeus with the H type 2 antigenic determinant, showed that all the H type 2 antigen in saliva is under the control of the Se gene, while only one-third of the H type 2 antigen present in serum is under the control of this gene. The remaining two-thirds of H type 2 antigen in sera is independent of the ABH secretor status of the donor. The amount of H type 2 antigen in both serum and saliva is independent of the Le gene. These results are compatible with the existence of two alpha (1 leads to 2) fucosyl-transferases but suggest that the enzyme of epithelial origin, coded by the Se gene, should be able to transform both type 1 and type 2 natural substrates, while the enzyme of mesodermic origin, coded by the H gene, would work preferentially on the natural type 2 substrates.

ABO Blood-Group System↗
PubMed1980

Non-specific inhibitory processes of immunological and mitogenic cellular responses.

The suppressive effects of four agents on several types of in vitro immune response and on in vitro responses to T and B mitogens were studied comparatively in spleen cells from C57B1/6 mice, previously injected with each of these agents. It was found that the in vitro PFC response to sheep erythrocytes was the most constantly and extensively inhibited: from 56% after treatment with Con A to 85% after treatment with HSA; LPS and C. parvum also provoked a strong inhibition (74-78%). Inhibition of MLC was constant but less effective, ranging from 36% (LPS) to 57% (C. parvum); HSA and Con A depressed it by about 50%. The CML reaction was substantially inhibited by C. parvum (50%), moderately by Con A and LPS (respectively, 23 and 28%) and slightly by HSA (15%). The inhibition of mitogenic response to PHA and LPS varied widely with the agent used: the PHA response was strongly inhibited by Con A (84%) to a lesser extent by C. parvum (54%) and even less by LPS (27%), whereas HSA did not affect it. LPS reactivity was well inhibited by C. parvum (57%), moderately by Con A (25%), slightly by HSA and not at all by LPS. Most of these agents produced a slight but significant prolongation of skin graft survival time. In vitro experiments using mixtures of spleen cells from treated and normal animals showed that these inhibitory effects were mediated by suppressive cells that developed as a result of the treatment used. The degree of inhibition observed in the mixed cultures satisfactorily paralleled the direct inhibition observed in cells from treated animals. The more consistently suppressive agents seemed to be C. parvum and Con A, the effects of the other two (HSA and LPS) on the cellular responses studied were less regular.

Animals↗
PubMed1978

The capacity of histocompatibility antigens solubilized in hypertonic salt solution to induce allograft tolerance in rats.

Treatment of Fisher rats (AgB 1,26,28) with a soluble extract of histocompatibility antigens (SAE) prepared from the liver of donor August rats (AgB 5, 28, 31) associated with a few injections of anti-lymphocyte serum (ALS) provoked a specific prolongation of the median survival time of skin grafts from 27.6 +/- 11.4 days in ALS-treated controls to 55.1 +/- 8.8 days (p less than 0.01). The SAE was obtained from liver homogenates by hypertonic KCl (3M) extraction. Further purification by chromatography in DEAE-cellulose column resulted in the separation of fractions possessing a specific inhibitory activity on a Fisher anti-August cytotoxic serum that was almost 100 times higher than that of the initial SAE preparation. Analysis of the state of unresponsiveness induced by SAE and ALS showed that most of the unresponsive animals had in their serum blocking factors. On the other hand, in vitro study of proliferative and cytotoxic components of cell-mediated immunity by mixed lymphocyte reaction and cell-mediated lympholysis, respectively, showed that the proliferative reactivity remained unimpaired whereas the cytotoxic reactivity was clearly inhibited in the tested animals. These results suggest that a central tolerance to histocompatibility antigens (equivalent to those coded by the K and D end in the mouse) could have been induced in the experimental animals whereas reactivity to Ia region antigens was not affected.

Animals↗
PubMed1977

Genetic selection of mice for quantitative responsiveness of lymphocytes to phytohemagglutinin.

A two-way selection was performed in mice according to the quantitative in vitro response of lymph node lymphocytes to the mitogenic activity of phytohemagglutinin (PHA). The foundation population was composed of outbred mice produced by reciprocal mating of equal numbers of mice from four different colonies. The selective breeding was carried out by mating of mice at each generation giving the best or the lowest response, respectively. The progressive interline separation produced by 6 generations of selective breeding demonstrates that responsiveness to PHA is submitted to polygenic regulation. The heritability of the character investigated is 0.28 +/- 0.08. The interline separation is also found with another T mitogen, concanavalin A (Con A). In spleen cells PHA and Con A produce a similar interline difference. In contrast, the purified protein derivative of tuberculin (PPD) stimulated both lines equally, and E. coli lipopolysaccharide gave only a slightly higher response in high line. This finding implies that our selection based upon response to PHA did not influence B cell function.

Animals↗
PubMed1976

[Neuroleptanalgesia as the anesthesia in pediatric surgery].

In work carried out over a period of two years in the department of anesthetics and intensive care of the Saint-Etienne University Hospital, the authors report their experience of neuroleptanalgesia using droperidol-dextromoramide in children in 104 cases. The observations may be divided up into 2 groups: - 1 group of children below the age of 2 years; - 1 group of children from 2 to 10 years. This study showed the side-effects and complications common to both groups, in particular, the extrapyramidal syndrome. Furthermore, the authors present their technique of administration.

Anesthesia↗
PubMed1975

[Study of anti-macrophage serum and of its effect on antibody formation].

A specific anti-macrophage serum (AMS) has been obtained by immunizing rabbits with mouse peritoneal exudate cells and after repeated absorption with mouse erythrocytes, thymocytes and splenic lymphocytes. A comparative study of the cytotoxic activities of this serum on macrophages, thymocytes and lymph node cells, before and after absorption, showed that macrophage posses antigens which are common to both thymic and lymph node lymphocytes, and other antigens which are in common with lymph node lymphocytes but absent on thymocytes, as well as antigens being particular to macrophages. The absorbed sera had a definite cytotoxic effect on macrophages in vitro. This effect was observed when complement was added immediately or 4 hours after incubation with serum. It was lost after 24 hours. An inhibitory effects of AMS on phagocytosis in vivo has also been observed, which disappeared after one day. Antibody production in vivo was only moderately affected by a pretreatment with AMS. However, addition of AMS to spleen cell cultures stimulated with sheep red blood cells inhibited the appearance of hemolytic plaque forming cells.

Animals↗