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Biomedical subjects

J Bertrand

Publications and source records attributed to J Bertrand.

At least 73 records · Page 4Linked to original sources
PubMed1990

[Incomplete androgen insensitivity syndrome. Difficulties of diagnosis and management].

A familial form of incomplete androgen insensitivity syndrome (AIS) is reported. The index case was first seen at 9 months of age for ambiguous genitalia. Diagnosis of AIS, suspected but first discarded on the basis of an androgen sensitivity test, was finally made at puberty on the discordance between poor virilization and elevated levels of both testosterone and LH, a florid gynecomastia, and the exclusion of any enzymatic defect in testosterone biosynthesis of 5 alpha-reductase deficiency. Androgen receptors in public skin were within the limits of normal for total number, with normal affinity. Familial occurrence included 2 first cousins born 7 and 10 years later, a maternal grand-uncle with similar ambiguous genitalia, and a maternal uncle with the gynecomastia-preserved fertility syndrome. This case report illustrates the heterogeneity of AIS in a given family and the difficulty of and early positive diagnosis in a newborn presenting with sexual ambiguity.

Body Height↗
PubMed1989

Evidence for an interaction of lipoprotein lipase with artery wall proteoglycans.

1. Artery wall proteoglycans-lipoprotein lipase binding characteristics were studied using bovine milk 125I-labelled lipoprotein lipase (LPL) and chondroitin sulphate-dermatan sulphate proteoglycans (PGs) purified from pig aorta. 2. The binding process was studied either by a soluble assay (gel filtration) or by an immobilized proteoglycan assay (ELISA). 3. The binding process was reversible, saturable and occurred at a stoichiometry 1:1. 4. The binding process involved ionic interactions between the positively charged groups of LPL and the negatively charged groups of PG carbohydrate chains. 5. The complex PG-LPL may lead to the production of remnant lipoproteins and, thereby, contribute to cholesteryl ester accumulation in the arterial wall.

Animals↗
PubMed1989

Rearrangements and point mutations of P450c21 genes are distinguished by five restriction endonuclease haplotypes identified by a new probing strategy in 57 families with congenital adrenal hyperplasia.

Congenital adrenal hyperplasia (CAH) is caused by disorders of the P450c21B gene, which, with the P450c21A pseudogene, lies in the HLA locus on chromosome 6. The near identity of nucleotide sequences and endonuclease cleavage sites in these A and B loci makes genetic analysis of this disease difficult. We used a genomic DNA probe that detects the P450c21 genes (A pseudogene, 3.2 kb; B gene, 3.7 kb in Taq I digests) and the 3' flanking DNA not detected with cDNA probes (A pseudogene, 2.4 kb; B gene, 2.5 kb) to examine Southern blots of genomic DNA from 68 patients and 165 unaffected family members in 57 families with CAH. Of 116 CAH-bearing chromosomes, 114 could be sorted into five easily distinguished haplotypes based on blots of DNA digested with Taq I and Bgl II. Haplotype I (76 of 116, 65.6%) was indistinguishable from normal and therefore bore very small lesions, presumably point mutations. Haplotype II (4 of 116, 3.4%) and haplotype III (8 of 116, 6.9%) had deletions and duplications of the P450c21A pseudogene but had structurally intact P450c21B genes presumably bearing point mutations; point mutation thus was the genetic defect in 88 of 116 chromosomes (75.9%). Haplotypes IV and V lack the 3.7-kb Taq I band normally associated with the P450c21B gene. Haplotype IV (13 of 116, 11.2%) retains all other bands, indicating that the P450c21B gene has undergone a gene conversion event, so that it is now also associated with a 3.2-kb band. Haplotype V (13 of 116, 11.2%) lacks the 2.4-kb Taq I fragment and the 12-kb Bgl II fragments normally associated with the P450c21A pseudogene, as well as lacking the 3.7-kb Taq I fragment, indicating deletion of approximately 30 kb of DNA, resulting in a single hybrid P450c21A/B gene. Most (114 of 116, 98%) CAH alleles thus can easily be classified with this new probing strategy, eliminating many ambiguities resulting from probing with cDNA.

Adrenal Hyperplasia, Congenital↗
PubMed1989

Gene conversions and rearrangements cause discordance between inheritance of forms of 21-hydroxylase deficiency and HLA types.

Congenital adrenal hyperplasia (CAH) can be caused by a variety of defects in the functional gene encoding 21-hydroxylase (P450c21), which lies in the midst of the human leukocyte antigen (HLA) locus on chromosome 6. As a result, Mendelian genetics permit clinically distinct forms of CAH to be traced genetically by HLA and complement typing of family members. The recent cloning of probes for P450c21 now permits tracing of the affected gene directly. A consanguineous family had three members affected with three clinically distinct forms of CAH. Two of these individuals had identical extended haplotypes, including nine HLA and complement loci. Despite this extensive identity, the patterns of genomic DNA fragments digested with endonuclease EcoRI and detected by a P450c21 cDNA probe differed greatly in these two individuals. Thus, the DNA diagnosis of allelic variation was much more sensitive than the HLA diagnosis. Genomic DNA digested with endonuclease TaqI and probed with P450c21 cDNA revealed the 3.2-kilobase (kb) band, which is generally associated with the nonfunctional P450c21 A pseudogene, in all family members, and also revealed the 3.7-kb band associated with the functional P450c21 B gene in all family members except the severely affected index case. Probing of the same blots with a genomic probe also permitted examination of the adjacent downstream TaqI fragments, showing retention of both the 2.4-kb (A pseudogene) and 2.5-kb (B gene) fragments. Similarly, BglII-digested genomic DNA from all individuals contained both the 12-kb (A pseudogene) and 11-kb (B gene) bands. These data indicate that the basis of 21-hydroxylase deficiency in the index case was due to a homozygous gene conversion event and not to gene deletion. These results show that the DNA in and around the 21-hydroxylase gene is genetically very active, so that the usual generalization concerning linkage and inheritance may yield incorrect conclusions and diagnoses.

Adolescent↗
PubMed1988

Effect of protein kinase C activation and depletion on insulin stimulation of glycogen synthesis in cultured hepatoma cells.

Insulin stimulation of glycogen synthesis was nearly abolished in hepatoma cells shortly treated with 4 beta-phorbol 12 beta-myristate, 13 alpha-acetate (protein kinase C activation) but remained unmodified in cells chronically treated with the phorbol ester (protein kinase C depletion). Thus, although exogenous activation of protein kinase C results in an inhibition of insulin action, protein kinase C depletion has no influence on this process. The results suggest that, in hepatoma cells, no endogenous activation of protein kinase C may occur in response to the signal triggered by insulin.

Animals↗
PubMed1988

Influence of flow and diffusion on protein separation in a continuous flow electrophoresis cell: computation procedure.

Continuous flow zone electrophoresis is an efficient method for the non-destructive separation of biological materials in a flowing film of buffer solution in which the constituents of a sample are separated according to their electrophoretic mobilities, under the influence of an electric field. This paper deals with modeling of flow structure of the buffer solution taking into account the effect of electroosmosis, Joule heating and thermal free convection and the forced convection of axial flow. Modeling of diffusion is examined in a second part. The modeling equations and the corresponding boundary conditions are solved by finite difference methods. The various parameters affecting the quality of the fractionation are analyzed.

Diffusion↗
PubMed1988

Inversely related evolution of growth hormone and prolactin secretions in long-term tissue cultures of human pituitary adenomas from acromegalic patients.

Pituitary tumoral tissue from 20 acromegalic patients was cultured for up to 120 d in a medium containing 5 nM cortisol. In all cultures, growth hormone (GH) release decreased. At the beginning of the culture, prolactin (PRL) was detected in 18 adenomas, varying from 0.5 to 1000 ng per flask per day. Thereafter, in 10 cases PRL secretion increased from 3 to 50 times the basal level, most frequently after a lapse of 9 to 30 d. PRL secretion remained low in three cases, undetectable in one case only. When added at 350 nM, cortisol increased GH secretion up to 20-fold and simultaneously decreased PRL secretion by as much as 10% of the basal level. Withdrawing cortisol reversed the situation. Immunocytochemical studies of the tumor at surgery showed, besides GH immunoreactive (IR) cells, PRL-IR cells (from rare cells to 10% of total cells) in 15 adenomas, correlating with the first days of culture PRL levels. In cultured explants, mitoses were never found. In 5 nM cortisol medium, the number of GH-IR cells decreased and PRL-IR cells increased or appeared. With 350 nM cortisol, the number of GH-IR cells increased, and PRL-IR cells were scarce or absent. Immunoreactivities for GH and PRL were found in different cells. Care was taken to exclude cultures containing normal pituitary tissue, and because no mitoses were found, these results suggest that most somatotropic adenomas can reversibly shift their secretion from GH to PRL in culture. This capacity to secrete PRL, hidden or low in vivo, is revealed by the favorable low cortisol conditions present in vitro.

Acromegaly↗
PubMed1988

Variations of liver prolactin receptors during the estrous cycle in normal rats and in the genetically hypoprolactinemic IPL nude rat.

Ovine prolactin (oPRL) binding to liver membranes was studied during the estrous cycle in normal and in genetically hypoprolactinemic rats. Serum levels of hormones were measured by radioimmunoassay and prolactin (PRL) binding was determined using 125I-ovine PRL in the 100,000 X g pellet. Scatchard plots obtained were curvilinear throughout the estrous cycle in the normal rat. They were analyzed in reference to the co-operativity model and to the Hill model which give the factor delta and Hill's coefficient (nH), respectively. During the estrous cycle, delta values varied from 3.77 +/- 0.66 on the day of estrous to 13.48 +/- 1.34 on the day of proestrus at 16.00 h. At the same time, nH were 0.97 +/- 0.033 on the day of estrus and 0.72 +/- 0.025 on the day of proestrus at 16.00 h. On the other hand, the number of PRL receptors did not change significantly throughout the estrous cycle. Moreover, the dissociation of 125I-oPRL from its receptor was accelerated by the presence of native ovine oPRL. These results suggest the presence of a negative co-operativity which reached a maximum on the day of proestrus in the normal rat. This co-operativity during the estrous cycle was not found in liver from genetically hypoprolactinemic (IPL nude) rats, which present a total absence of lactation. The delta values did not vary significantly and were 6.52 +/- 1.30 on the day of estrus and 4.41 +/- 0.52 on the day of proestrus at 16.00 h. The difference between the two rat strains was statistically significant on the day of proestrus at 16.00 h for both delta and nH values.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Variations of liver prolactin receptors during pregnancy in normal rats and in the genetically hypoprolactinemic IPL nude rat.

Ovine prolactin (oPRL) binding to liver membranes was studied during pregnancy in normal and in genetically hypoprolactinemic rats. Prolactin (PRL) binding was determined using 125I-oPRL in the 100,000 x g pellet. Scatchard plots obtained changed throughout the pregnancy in the normal rat, being almost linear from days 2 to 10, becoming curvilinear (convex) on day 16, and linear again at the end of pregnancy. They were analyzed with reference to the co-operativity and Hill models, which give delta and nH, respectively. During pregnancy, delta values varied and were respectively 2.48 +/- 0.66, 1.84 +/- 0.64, 0.52 +/- 0.06 and 1.69 +/- 0.25 on days 3, 10, 16 and 22, and the delta value on day 16 was significantly different from other days; the nH value estimated on day 16 was 1.10 +/- 0.031. These results suggest the presence of a positive co-operativity on day 16 of pregnancy. Over the same period, a huge increase in the capacity occurred on day 10 and reached a maximum on day 14. It remained elevated until the day before parturition. In the IPL nude rat, the delta value (0.92 +/- 0.45) on day 16 was significantly different from that of normal rats and indicated an absence of positive co-operativity on this day in the IPL nude rat liver. This finding was confirmed by an nH value (0.99 +/- 0.39) close to 1. The PRL-binding capacity was similar to that of normal rats, except on day 14, where it was significantly decreased. These results are discussed in relation to hormonal variations during pregnancy, particularly with regard to serum PRL and placental lactogen values.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Relationship between bioassay and radioimmunoassay measurement of prolactin in the IPL rat, a hypoprolactinemic rat strain.

IPL (Institut Pasteur, Lyon) nude, hypoprolactinemic rats exhibit delayed puberty and a complete lack of lactation. To characterize the secretion of circulating forms of prolactin (PRL) of these rats, PRL concentrations were measured in serum and pituitaries of males and females under various physiological conditions. Two assay methods, a radioimmunoassay (RIA) and a sensitive bioassay (NB2BA) were employed. Normal rats of the Sprague-Dawley strain were tested simultaneously, as controls. The pituitary content of PRL, estimated either by RIA or by NB2BA, in IPL nude males and females was similar to that of normal male and female rats. On the contrary, serum PRL levels of IPL male rats, measured by RIA or NB2BA, were significantly reduced when compared to normal rats. In both groups, there was a close correlation between the results obtained by the two methods, the NB2BA estimates being higher. However, the NB2BA/RIA ratio was significantly decreased in serum from IPL nude rats compared to controls, indicating that the circulating form of PRL was less bioactive in this group. Castrated male rats injected with estradiol showed sharply increased PRL values as estimated by RIA or NB2BA. The increase was greater (35-fold) in IPL nude rats then in normal rats (9-fold), but these increases resulted in serum PRL levels being similar in the two groups. However, the NB2BA/RIA ratio remained significantly reduced in IPL nude rats. In female rats, PRL was measured during different physiological states: estrus, diestrus, proestrus at 1000, 1200, and 1600 h and Days 1 and 21 of gestation and 2 days postpartum.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Undescended testis: comparison of two protocols of treatment with human chorionic gonadotropin. Effect on testicular descent and hormonal response.

A randomized study of two protocols of human chorionic gonadotropin (hCG) treatment was performed in 183 prepubertal boys between 7 months and 12 years of age: protocol I, in which the boys were given 7 injections of 1,500 IU every other day, and protocol II consisting of 4 injections of 100 IU/kg at 4- to 5-day intervals. In both protocols, by the end of the test, testosterone had risen significantly to values within the normal adult male range. However, the amplitude of the rise was slightly but significantly lower using protocol II (4.08 +/- 2.07 ng/ml) than protocol I (5.16 +/- 2.73 ng/ml). It would thus appear that repetition of the hCG injection at intervals of less than 4 days is unnecessary, and that a total stimulation period of 2-3 weeks is sufficient. Although not correlated with testosterone levels, the success rates for treatment were similar in both protocols and comparable to rates reported in the literature.

Adolescent↗
PubMed1988

Structure, function, and immunogenicity of human insulinoma cells.

Dissociated human insulinoma cells were plated onto plastic multiwell dishes. Cells were maintained for 1 mo on plastic with three passages. Cultures consisted of small colonies with some areas of stratification and few intercellular spaces. Ultrastructural studies indicated that cultured cells had epithelial features with desmosomes at cell-to-cell contacts and intermediate filaments in addition to secretory granules in the cytoplasm. Insulin and C-peptide were released in equimolar amounts in culture media. When challenged for 30 min with 16.7 mM glucose, 1 mM 3-isobutyl-1-methylxanthine, 4 mM tolbutamide, or 10(-6) M glucagon, insulinoma cells responded by a 1.5-, 1.5-, 2-, or 3-fold increase, respectively, in insulin release above baseline levels. A 15-min challenge with 10(-5) M isoproterenol increased insulin secretion by 1.85-fold. By indirect immunofluorescence, an anti-insulin antibody reacted positively with cell cytoplasm, whereas anti-somatostatin and anti-glucagon antibodies did not. Insulinoma cell surface expressed class I MHC molecules but not class II molecules. Immediately after isolation, crude insulinoma cells were contaminated by 2% of DR+ cells from nonislet components that disappeared after several weeks in culture. The ability of insulinoma cells to stimulate allogenic T-lymphocyte proliferation was assessed by [3H]thymidine incorporation in mixed culture combinations. Crude insulinoma cells elicited a strong lymphoproliferative response with a stimulation index ranging between 3.5 and 7, whereas no stimulation was found after 1 mo in culture. It is postulated that absence of class II-positive cells in the stimulatory cell preparation conditioned this immune tolerance across the major histocompatibility barrier.(ABSTRACT TRUNCATED AT 250 WORDS)

1-Methyl-3-isobutylxanthine↗
PubMed1987

Effect of dibutyryl cyclic AMP and theophylline on lipoprotein lipase secretion by human monocyte-derived macrophages.

The effect of dibutyryl cyclic AMP and theophylline on lipoprotein lipase secretion was investigated after a 24 h pretreatment of human monocyte-derived macrophages. Both the effectors decreased in a dose-dependent manner the enzyme activity recovered in the culture medium. The decrease in lipoprotein lipase activity appeared to be related to reduced enzyme synthesis without apparent modification of its stability and half-life and was conversely associated with an increase of lysosomal acid hydrolase activities. This effect was reversible on removal of the nucleotide. The present findings suggest that cyclic AMP may play a role in lipoprotein lipase expression in human macrophages and therefore may participate in the regulation of lipoprotein uptake by these cells, which are strongly implicated in the atherogenic process.

Bucladesine↗
PubMed1987

Chronic splenomegaly in Nairobi, Kenya. II. Portal hypertension.

Eighty-five patients with chronic splenomegaly and proven oesophageal varices were studied at Kenyatta National Hospital, Nairobi. The major defined groups were hepatosplenic schistosomiasis (24%), cirrhosis (20%) and portal vein occlusion (11%). Hyper-reactive malarial splenomegaly (tropical splenomegaly syndrome) was considered as the cause of oesophageal varices in only one patient. In 26% of cases liver biopsy was non-diagnostic and the extrahepatic portal vein was demonstrated radiologically to be patent. Such patients were thought to be suffering from idiopathic portal hypertension, not previously described elsewhere in Africa. Hepatitis B surface antigen was detected in 12% of controls and in 58% of patients with cirrhosis (p less than 0.001). Some serological marker of previous hepatitis B virus infection was present in 92% of patients with cirrhosis and in 79% of controls. Kamba patients from Machakos and Kitui Districts were significantly more prevalent than expected among these 85 cases of portal hypertension.

Esophageal and Gastric Varices↗
PubMed1987

Thyroid-hypophyso-hypothalamic axis of the genetically hypoprolactinemic rats (IPL nude rats).

In order to evaluate thyrotropin function in the genetically hypoprolactinemic rat, (IPL nude), we measured by radioimmunoassay TRH hypothalamic content, pituitary TSH content and serum TSH, T3, T4, both in IPL nude and control rats at various times over the 24-hour period. Compared to normal rats, the hypothalamic TRH content in the IPL nude rat showed similar variations during the day, whereas a slight increase was observed during the night characterized by a significant difference at 20.00 h. Pituitary weight and TSH content were doubled in IPL nude rats; however, when expressed as micrograms TSH/micrograms protein or DNA, a significant increase was found only at 17.00 and 20.00 h. Serum TSH and total serum T3, T4 depicted similar variations although they were minute but nonetheless significant modifications, i.e. an increase of TSH at 17.00 and 23.00 h and a decrease of T4 at 11.00 h. However, only FT4 concentrations (and not-FT3) were slightly but significantly decreased in IPL rats over the experimental times. In conclusion, the slight increase in hypothalamic TRH and pituitary TSH contents and the absence of main associated variations of serum TSH, T3 and T4 do not lend support to the hypothesis that TRH could be the cause of the hypoprolactinemia of these rats. On the contrary, the observed thyrotropin axis variations might be rather interpreted as the consequence of it.

Animals↗
PubMed1987

Human islet cell autoantibodies specifically bind cloned rat islet cells.

Sera from newly diagnosed type I (insulin dependent) diabetic patients and control subjects were tested by indirect immunofluorescence on a particular subclone of RINm5F cells for the presence of cytoplasmic antibodies. Cell cultures after biochemical fixation and frozen sections of cell sheets obtained after incubating confluent monolayers with dispase were used alternatively as substrate. Eight out of ten ICA positive sera previously tested on frozen sections of human pancreas bind RIN cells when fixed with acetone-ethanol whereas no staining was obtained after treating the cells with paraformaldehyde or glutaraldehyde. Four normal sera did not bind RIN cells under these conditions. Alternatively, frozen sections of cell sheets appeared to be a more sensitive substrate as all ICA positive sera tested reacted with cell cytoplasm. In addition, an immunoradiometric assay was developed using microtitre plate wells coated with Nonidet P40 solubilized RIN antigens. Coated wells were incubated with ICA positive and ICA negative diabetic sera along with sera from normal individuals. Antigen antibody complexes were detected by the binding of 125I-Protein A. A good correlation was found between binding values and results obtained by indirect immunofluorescence on frozen sections of human pancreas. Although this study indicates that RIN cells express a specific cytoplasmic antigen to which ICA positive sera bind, more information is required concerning the exact nature of this antigen before such assay can be reliably used for the detection of ICA.

Animals↗