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Biomedical subjects

C Beaumont

Publications and source records attributed to C Beaumont.

At least 109 records · Page 6Linked to original sources
PubMed1984

Assignment of the human gene for delta aminolevulinate dehydrase to chromosome 9 by somatic cell hybridization and specific enzyme immunoassay.

A non-competitive enzyme immunoassay specific for delta aminolevulinate dehydrase has been devised and applied to rodent-human hybrid cell lines. Two different conditions have been used, one specific for the human enzyme and the other indicative of both rodent and human enzymes. The ratio of the values obtained under the two conditions was used to discriminate between positive and negative clones. By this method the gene for ALA dehydrase has been assigned to chromosome 9.

Animals↗
PubMed1984

Enzymatic and immunological studies of uroporphyrinogen decarboxylase in familial porphyria cutanea tarda and hepatoerythropoietic porphyria.

Uroporphyrinogen decarboxylase activity was measured in hemoglobin-free lysates from two patients with hepatoerythropoietic porphyria (HEP) and from 12 unrelated patients with familial porphyria cutanea tarda (PCT). In HEP patients, enzyme activities were 5% of normal, and familial studies clearly confirmed that patients with HEP are cases of homozygous PCT. Immunoreactive uroporphyrinogen decarboxylase was measured by developing a direct and noncompetitive enzyme immunoassay (EIA). For the 12 familial PCT patients, we found an immunoreactive protein decreased (51%) to the same extent as the catalytic activity (48%) [cross-reactive immunological material ( CRIM ) negative]. The children from the HEP family were also CRIM negative, contrasting with another HEP family previously described as CRIM positive; our data support the hypothesis of a heterogeneity in familial uroporphyrinogen decarboxylase deficiency.

Carboxy-Lyases↗
PubMed1983

Maintenance and reversibility of active albumin secretion by adult rat hepatocytes co-cultured with another liver epithelial cell type.

When adult rat hepatocytes were co-cultured with another liver epithelial cell type in a medium supplemented or not with fetal calf serum (FCS), it was found that 1. They survived for more than 2 months 2. Albumin secretion levels remained high over the whole culture period 3. Decreased secretion might be reversed 4. This protein secretion activity appeared to be dependent upon both the presence of cell-cell contacts and the production of an extracellular material. The results demonstrate for the first time long-term stabilization and reversibility of a specific function (albumin secretion) at high levels by adult hepatocytes cultured in serum-free medium and suggest that both the presence of other liver cell type(s) and the production of an extracellular matrix are needed for the maintenance of specific functions in cultured hepatocytes.

Albumins↗
PubMed1983

Albumin secretion and protein synthesis by cultured diploid and tetraploid rat hepatocytes separated by elutriation.

Diploid and tetraploid rat hepatocyte subpopulations were isolated by elutriation and cultured for 24 h. Albumin secretion and protein synthesis rates were two-fold lower in 2n than in 4n hepatocytes. [35S]methionine-labelled proteins analysed by acrylamide gel electrophoresis showed a strikingly similar pattern in the two cell subpopulations. No differences in cellular proteins or in the intensity of labelling were observed. These results show (1) that viable diploid and tetraploid hepatocyte subpopulations can be separated by elutriation under sterile conditions and then cultured; and (2) strongly suggest that the same genes are transcribed and further translated at the same rate in both hepatocyte subpopulations.

Albumins↗
PubMed1983

Myocardial infarction and sexual activity of the female patient.

Although successful rehabilitation of cardiac patients should include consideration of their sexuality, there is a paucity of data regarding the sexual activity of female patients who have had myocardial infarctions. We report on interviews with 130 such patients. Sexual concerns soon developed in 30% of those sexually active before the myocardial infarction. Fear of resumption of sexual activity was expressed by 51% of the patients and 44% of the husbands. Sexual activity was not resumed by 27%, was unchanged by 27%, and was decreased by 44%. Only 45% of the total group received sexual instructions before discharge, and in only 18% of cases did the physician raise the topic. Symptoms during intercourse were reported by 57% of the patients. Myocardial infarction has a negative impact on the sexuality of the female patient, and although many patients who have had myocardial infarction desire sexual counseling, their demands are still not being met. Accurate and complete sexual instructions of both partners with specific attention to the woman's concerns and needs should be part of cardiac rehabilitation.

Adult↗
PubMed1981

Hormonally stimulated adenylate cyclase and cAMP dependent protein kinase in membranes of rabbit erythroid cells separated according to density.

Plasma membranes were prepared after density gradient separation of erythroid cells obtained from bled animals. In a fraction enriched in young reticulocytes (lowest density), the basal and the prostaglandin stimulated adenylate cyclase were greatly augmented if compared with the membranes from unfractionated cells or from the layers of higher densities. Potentiation by GTP or soluble factor(s) of the prostaglandin stimulated adenylate cyclase was found solely in the fractions containing the youngest cells (lowest density). A very significant augmentation of both the basal and the effectors stimulated adenylate cyclase was obtained when the white blood cells and the platelets were removed by filtration through alpha-cellulose prior to density separation. A small population of probably very young reticulocytes was shown to contain a very active adenylate cyclase coupled to the hormonal receptor. Upon short time of maturation this coupling could no longer be detected. The cAMP generated in the fraction enriched in young reticulocytes increased the phosphorylation of some membrane proteins. The presence of a hormonally regulated adenylate cyclase and eventually the phosphorylation of some specific membrane proteins by the cAMP generated in situ permit to envisage possible functions of this system in young reticulocytes.

Adenylyl Cyclases↗
PubMed1981

Assessment of liver iron content in 271 patients: a reevaluation of direct and indirect methods.

Two direct methods for hepatic iron assessment (liver iron concentration and stainable liver iron--judged by a new histologic grading) and three indirect methods (serum iron and transferrin saturation, deferoxamine-chelation test, and ferritinemia) were reevaluated in 271 patients. These patients consisted of: 103 with idiopathic hemochromatosis, 39 with alcoholic cirrhosis, 54 with noncirrhotic alcoholic liver diseases, 13 with nonalcoholic liver diseases, and 62 with miscellaneous disorders. The results indicate that: (a) liver iron concentration, well correlated with mobilized excess iron (r = 0.88; p < 0.01), is the method of reference and validates the proposed histologic grading; (b) serum ferritin, which is in good correlation with liver iron concentration (r = 0.80; p < 0.01), is a valuable indirect method for hepatic iron evaluation; (c) regarding the other indirect methods a "boundary zone" may be delimited, thus corresponding to liver iron concentration values of 10.7 mumol/100 mg dry liver weight, beyond which values of serum iron less than 28.6 micrometer or transferrin saturation less than 45% or chelatable iron less than 45 mumol/24 h are rare; and (d) using the various indirect methods, there is a marked risk in idiopathic hemochromatosis to underestimate and in alcoholic liver diseases to overestimate hepatic iron content.

Deferoxamine↗
PubMed1980

Idiopathic hemochromatosis: a study of biochemical expression in 247 heterozygous members of 63 families: evidence for a single major HLA-linked gene.

The hypothesis has been advanced that the two genes on chromosome 6 determining idiopathic hemochromatosis are not identical alleles and therefore that the disease is not recessively inherited, but rather that two different genes are involved. A study of 63 families points to: (a) the rarity with which a single hemochromatosis gene finds biochemical expression (in only 1 of 5 cases), as revealed through determinations of serum iron, serum ferritin and the desferrioxamine test; (b) no difference in HLA-antigen marking between genes with and those without biochemical expression: (c) no difference other than that produced by chance in the biochemical expression of the two genes in families; and (d) the finding in one highly informative family of identical expression of the two genes. It is concluded that idiopathic hemochromatosis is determined by two homologous alleles in accordance with the classical mode of recessive inheritance.

Adolescent↗
PubMed1980

Hepatic and serum ferritin concentrations in patients with idiopathic hemochromatosis.

Hepatic iron and ferritin concentrations have been measured in needle biopsy specimens from patients with idiopathic hemochromatosis and from patients with other liver diseases. There was an excellent correlation between liver iron and ferritin concentrations in patients with miscellaneous liver diseases, but this was not found for the patients with hemochromatosis either before or after treatment. The proportion of liver iron bound to ferritin was lower in treated and untreated hemochromatosis than in the other patients. This probably reflects the formation of increasing amounts of hemosiderin with increasing iron deposition. Three patients in the early stage of idiopathic hemochromatosis were studied. These patients had high concentrations of hepatic iron and ferritin, but had serum ferritin concentrations within, or just above, the normal stage. These results suggest that, in the early stage of hemochromatosis, there is no failure of ferritin synthesis in the liver and that normal levels of serum ferritin are present either because the total body iron content is within the normal range or because the liver parenchymal cells are not, in the absence of liver damage, an important source of plasma ferritin.

Adult↗
PubMed1979

Serum ferritin as a possible marker of the hemochromatosis allele.

To determine whether a correlation exists between the biochemical expression of hemochromatosis and the HLA genotype, we studied 174 family members of 32 persons with the disease. Persons who shared both HLA haplotypes with the proband (and presumably having two hemochromatosis alleles) differed significantly from those who shared only one haplotype (and presumably having one hemochromatosis allele) in terms of serum iron (P less than 0.001 for both sexes), unsaturated iron-binding capacity (P less than 0.01 for female and P less than 0.0001 for male subjects) and serum ferritin (P less than 0.0001 for female and P less than 0.00001 for male subjects). The only significant difference between relatives having one hemochromatosis allele and age and sex-matched controls was related to serum ferritin values in male subjects (P less than 0.05, despite considerable overlap). In our hands, serum ferritin was the best indicator of disordered iron metabolism and was elevated among most homozygous but among few heterozygous family members.

Adolescent↗
PubMed1979

[Demonstration by iron overloading study and HLA genotyping of recessive transmission of idiopathic haemochromatosis in two pseudodominant pedigrees (author's transl)].

We studied iron overloading and HLA genotype in two families with overt forms of idiopathic haemochromatosis in two successive generations. In each family the spouse of the patient with overt haemochromatosis in the first generation had clinical and laboratory signs of moderate iron overload and a HLA haplotype A3, B14 and A3, B7 respectively--which is frequently associated with the haemochromatosis gene. This specific HLA haplotype had been transmitted to the second generation patient with overt disease, which thus could be considered as having received a haemochromatosis gene from each parent. Although the finding of cases of overt disease in successive generation firstly suggests a dominant transmission the genetical analysis of these families lead to further strong argument in favour of recessive inheritance of idiopathic haemochromatosis.

Adolescent↗
PubMedDate not supplied

Genetic parameters of body weight and prolificacy in pigeons.

Genetic parameters of body weight at weaning and of prolificacy were estimated in three commercial lines of pigeons selected by BLUP (Best Linear Unbiased Prediction) on both traits. The model of analysis took into account the direct genetic effects for both traits and the effect of parental permanent environment for body weight. Depending on the line considered, body weight varied from 556.7 g to 647.6 g and prolificacy ranged from 12.5 to 16.8 pigeons weaned per couple of parents per year. Heritability of body weight was high, varying between 0.46 and 0.60, and permanent environment was responsible for 6% to 9% of the total variability. On the contrary, prolificacy was poorly heritable (0.04 to 0.12). They were highly and negatively correlated (-0.77 to -0.82). Body weight showed significant genetic trends in lines B and C. No significant genetic difference could be observed between males and females for both traits.

Journal Article↗