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Biomedical subjects

B Robert

Publications and source records attributed to B Robert.

198 records · Page 11Linked to original sources
PubMed1967

Studies on the proteolytic activity of gamma-globulin preparations.

1. The proteolytic activities of several gamma-globulin preparations were tested. These included sulphate-precipitated human and bovine preparations and human and bovine Cohn fraction II preparations as well as purified gamma-globulin preparations. Up to 14mg. of diffusible peptides and glycopeptides/g. of gamma-globulin was liberated after dialysis and up to 10mg. of peptides/g. after incubation and trichloroacetic acid precipitation, as products of the degradation process in incubated gamma-globulin. 2. in-Aminohexanoic acid and p-chloromercuribenzoic acid, as well as heating at 60 degrees for 40min., were shown to inhibit strongly these proteolytic activities. Streptokinase was shown to activate strongly the proteolytic activity of all the human preparations (sulphate-precipitated, Cohn fraction II, and purified gamma-globulin). 3. Two distinct pH optima were shown for human and bovine gamma-globulin preparations: one at pH8, the other at pH3.8 (the latter activity could be demonstrated only in the presence of cysteine). 4. Both (131)I-labelled human Cohn fraction II and bovine fibrinogen were attacked by a sulphate-precipitated preparation of gamma-globulin. Of the synthetic substrates tested toluene-p-sulphonyl-l-arginine methyl ester was hydrolysed by both the sulphate-precipitated and Cohn fraction II preparations, as was benzoyl-l-arginine amide at pH5, but only in the presence of cysteine. 5. These data are interpreted to indicate that at least two enzymes are present in gamma-globulin preparations, one being similar to the plasmin system, the other similar to cathepsin B.

Acids↗
PubMedDate not supplied

Role of Gd-DOTA in the evaluation and imaging of experimental blood-brain barrier disruption in brain edemas and their improvement after anti-inflammatory drugs treatment.

This study was carried out to evaluate the effect of new anti-inflammatory drugs in the treatment of brain edema in new models. Experimental brain edema was induced in rats by stereotaxic injection of phospholipase A2 into one hemisphere. Concentrations of intravenously injected gadolinium-DOTA in the lesioned hemisphere were three times as high as in normal rat hemisphere. Edema was reduced by treatment with anti-inflammatory drugs such as dexamethasone (P < 0.01) or an experimental benzamide drug (P < 0.02). Magnetic resonance imaging (MRI) was then used to evaluate edema reduction after administration of contrast medium. We observed weighted scans for control lesioned rats, a reduction of signal intensity after dexamethasone and no significant regression after the benzamide drug. For purposes of experimental brain edema research in rats, the MRI technique facilitates detection and evaluation of the anti-inflammatory activity of molecules crossing the blood-brain barrier.

Animals↗
PubMedDate not supplied

Does high polyunsaturated free fatty acid level at the feto-maternal interface alter steroid hormone message during pregnancy?

Polyunsaturated fatty acids (PUFA) are important in pregnancy, fetal development and parturition. We measured free fatty acids (FFA), albumin and alpha-fetoprotein (AFP) in the maternal and fetal circulations of women undergoing elective Caesarean section at term. We also studied the impact of PUFAs on estrogen (ER) and progesterone receptors (PR) binding properties in vitro in the myometria of pregnant women and ex vivo in human myometrial cells in culture. FFA in intervillous blood (I) (feto-maternal interface) and maternal peripheral blood (M) were similar, while those in the umbilical vein (V) and arteries (A) were 2-4 fold lower (P<0.001). PUFA levels were low in M and 3 fold higher in I, A and V (P< 0.001); consequently C20:4 and C22:6 were most abundant in intervillous space. Albumin was uniformly distributed throughout the maternal-fetal unit, but there was a transplacental gradient in AFP. The AFP in the intervillous space had a special conformation (less immuno-reactive, more anionic), suggesting loading with PUFA. Physiological concentrations of C20:4 stimulated estradiol binding, but inhibited progestin binding. C20:4 inhibited progesterone binding by decreasing the number of binding sites, with no change in apparent affinity, in vitro in myometrial tissue and ex vivo in myometrial cells. Thus PUFA may modulate the steroid hormone message, so that the high C20:4 concentration at the maternal-fetal interface at term may help amplify the estrogen signal and inhibit the progesterone signal.

Carrier Proteins↗
PubMedDate not supplied

Investigation of genetic linkage between myosin and actin genes using an interspecific mouse back-cross.

The introduction of cloned probes to follow the segregation of DNA restriction fragment length polymorphisms (RFLPs) has led to a revival of mendelian genetics in attempts to map the human genome. In the mouse, however, it has often proved difficult to detect an RFLP with a DNA probe between different inbred strains of the laboratory mouse. To circumvent this problem, we have used two species, Mus musculus domesticus and Mus spretus which interact as sympatric species but can be interbred under laboratory conditions. Because of the relative evolutionary distance between these species, they exhibit polymorphism at many more loci than do different strains of the usual M. m. domesticus laboratory mouse. This is also observed at the DNA level when the sizes of restriction fragments encoding a specific gene are compared. We have used these RFLPs between M. m. domesticus and M. spretus to follow the segregation of genes encoding different isoforms of myosin alkali light chains in the backcross progeny between these species and to compare this with that of other contractile protein genes. No linkage between these genes was observed.

Actins↗
PubMedDate not supplied

Alpha-fetoprotein gene expression in early and full-term human trophoblast.

Alpha-fetoprotein (AFP) is a major serum glycoprotein synthesized during fetal life mainly by the yolk sac and the fetal liver. At term, it reaches high concentrations in the maternal intervillous blood, which is in direct contact with the placental trophoblastic microvillous membrane, and this suggests the placental origin of the AFP at the fetal-maternal interface. We used several experimental approaches to investigate the expression of AFP gene and fetal protein production in early gestation and term placentas. RT-PCR and immunological studies clearly identified AFP messenger RNA and AFP protein in the placental villi from first trimester of pregnancy. The AFP gene was also expressed in highly purified cytotrophoblasts from early placentas, and enzymo-immunoassay showed that AFP protein was synthesized and secreted by early cytotrophoblasts. AFP was also detected in the cytoplasm of these cells by immuno-cytochemistry. However, none of these methods detected any expression of the AFP gene in full-term placental villi or in cultured trophoblasts. These findings demonstrate that both AFP mRNA and protein are present in trophoblastic cells early in pregnancy. The absence of AFP gene expression in term placental villi also suggests, that the AFP at the fetal-maternal interface is attributable to a notable transplacental passage of AFP from fetal blood in late pregnancy.

Adult↗