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Biomedical subjects

D Samuel

Publications and source records attributed to D Samuel.

At least 235 records · Page 13Linked to original sources
PubMed1988

[Cirrhosis and biliary lithiasis in France: a postmortem study].

The prevalence of cholelithiasis was estimated in 434 cirrhotic patients and 1582 non cirrhotic patients necropsied at Hôpital Beaujon from 1976 to 1984. The overall prevalence of cholelithiasis was significantly higher in cirrhotic than in non cirrhotic patients, 26.3 p. 100 and 20.3 p. 100, respectively. The prevalence of cholelithiasis was higher in cirrhotic than in non cirrhotic patients, whether male or female and at any age, except in women over 60 years and in men over 80 years; in these groups, the prevalence of cholelithiasis in non cirrhotic patients was especially high and therefore did not significantly differ from that in cirrhotic patients. The cause of cirrhosis did not significantly influence the prevalence of cholelithiasis; however, although the number of studied patients was small, the prevalence of cholelithiasis seemed to be particularly high in primary biliary cirrhosis. The prevalence of cholecystectomy was lower in cirrhotic than in non cirrhotic patients, which suggests that cholelithiasis might be less often symptomatic and/or less often complicated in the former than in the latter.

Adult↗
PubMed1987

The occurrence of 2'-5' oligoadenylates in Escherichia coli.

The use of a highly specific radioimmunoassay and of HPLC permitted us to confirm the occurrence of 2'-5' oligoadenylates [p chi (A2'p5')nA] in several strains of Escherichia coli. Cellular concentrations of 2'-5' oligoadenylates ranged from 50 nM to 300 nM. The mixture of 2'-5' oligoadenylates consisted primarily of pppA2'p5'A, pA2'p5'A,A2'p5'Ap and A2'p5'A under normal conditions of growth. None of them activated RNase L. Infection of the bacteria with the single-stranded DNA phage M13 or induction of a heat-inducible, non-lytic mutant of phage lambda led to a significant increase in the total pool of 2'-5' oligoadenylates, paralleling the progressive inhibition of growth. Likewise, the inhibition of protein synthesis with chloramphenicol stimulated the accumulation of 2'-5' oligoadenylates. Furthermore, the inhibition of bacterial growth by either phage or by chloramphenicol brought about a change in the composition of the 2'-5' oligoadenylate pool; 5'-phosphorylated 2'-5' oligoadenylates accumulated and became the major components. The findings indicate a parallelism between the effects of viral infection on the synthesis of 2'-5' oligoadenylates in eukaryotes and similar effects subsequent to phage growth in the bacterium E. coli.

Adenine Nucleotides↗
PubMed1987

AL721, a novel membrane fluidizer.

AL721, which is a novel lipid mixture extracted from egg yolks, is believed to be a therapeutic pharmacologic agent. AL721 interacts with membranes of various types of cells with a common mode of action. AL721 modifies cellular membrane composition and fluidity through passive extraction and/or exchange of cholesterol. Physiologically diminished cell function due to rigidification of its membrane is reversible both in vitro and in vivo by AL721. Fluidization of aged membranes with AL721 has been shown to restore brain serotonin receptor function both in vitro and in vivo. AL721 can also successfully restore deficient immune responsiveness of lymphocytes to mitogen stimulation in aged subjects. Drug tolerance to morphine and ethanol develops upon elevation of the viscosity of neuronal cell membranes in order to counteract the fluidization effect of the drug. Treatment of rigidified cellular membranes with AL721 in vivo can markedly reduce withdrawal symptoms. The virucidal effect of AL721 on the human immunodeficiency virus is believed to operate by lowering of viral membrane cholesterol thus interfering with the binding of the viral antigen to the host cell. Non-toxicity of AL721 is clearly demonstrated in animal and human safety studies.

Aged↗
PubMed1987

Emergency liver transplantation for fulminant hepatitis.

Orthotopic liver transplantation was done in 17 patients with fulminant hepatitis. The cause of the liver disease was infection with hepatitis B virus, or co-infection with hepatitis B virus and hepatitis D virus, or infection with hepatitis A virus in 6 patients; drug hepatotoxicity in 5; and indeterminate in 6. Grafts from incompatible blood groups, steatotic grafts, or reduced-size grafts were used in 5, 4, and 4 patients, respectively. Of the 17 patients, 5 died: 2 of early liver failure due to the poor quality of the graft, 1 presumably of accidentally transmitted acute infection with the human immunodeficiency virus, and 2 of decerebration occurring during or immediately after surgery. The 12 other patients were alive 2 to 15 months after transplantation.

Acute Disease↗
PubMed1987

[Immunologic surveillance of liver transplant patients using monoclonal antibodies against lymphocyte subpopulations].

A precise immunological surveillance of liver graft recipients can allow the adaptation to each patient of an adequate immuno-suppressive treatment. In 11 liver-transplanted patients (7 primitive biliary cirrhoses, 2 post-hepatic cirrhoses, one bile duct atresia with one antitrypsin deficit) different lymphocyte subpopulations were tested before transplantation and at days 3, 5, 7, 15, 30, 60 and 120 after grafting using OKT3, OKT4, OKT8 (Orthoclone, France). In 6 patients presenting one or more rejections, the (T4+):(T8+) lymphocyte ratio was significantly increased during the days preceding rejection. In all cases, the (T4+):(T8+) ratio increase was linked to a (T4+) helper lymphocyte augmentation. In the 6 patients who did not present any rejection, the (T4+):(T8+) ratio did not increase at long term. A decrease of the (T4+):(T8+) ratio, along with an augmentation of (T8+) lymphocytes, was noticed at long term in patients free of chronic rejection. The evolution of T lymphocyte populations, followed using monoclonal antibodies and mainly the (T4+):(T8+) ratio, can provide a test for rejection predictability of for the prognosis of tolerance to liver allografts.

Antibodies, Monoclonal↗
PubMed1986

The use of monoclonal and polyspecific antibodies in the IgE sandwich ELISA.

The use of antibody to link antigen to microtitre plates in the enzyme-linked immunosorbent assay (ELISA) has been extended to include mouse monoclonal antibodies and polyspecific rabbit antibodies. Small amounts of both reagents could be used. The capacity of the microtitre plate for the antibody was found to be critical and irradiated plates generally gave better results. Both rabbit anti-IgE conjugated to horseradish peroxidase, and monoclonal mouse anti-IgE with alkaline phosphatase-conjugated rabbit anti-mouse IgG could be used as detection reagents. Comparison with the radioallergosorbent (RAST) test showed a good agreement with the sandwich ELISA. The sandwich ELISA using polyspecific rabbit antibody was substantially more sensitive than conventional ELISA and also marginally more sensitive than RAST.

Allergens↗
PubMed1986

New evidence for taurine biosynthesis in man obtained from 18O2 inhalation studies.

The ability of adult humans to synthesize taurine was assessed by measurement of the 18O content of urinary taurine in eight subjects following 60 minutes inhalation of 18O2 (97% 18O). All subjects had at least one 3-hour urine collection in which the mole ratio of 18O-taurine to taurine was at least three times greater than the standard deviation of the stable isotope measurement. The peak mole ratios of 18O-taurine/16O-taurine ranged from 0.0075 to 0.015. These data indicated that adult human subjects have a significant ability to synthesize taurine.

Adult↗
PubMed1985

A new method of iodinating ovalbumin, a protein which lacks accessible tyrosine groups, by conjugation to a highly fluorescent coumarin active ester, CASE.

A simple and efficient method is described to overcome the difficulty in radiolabelling ovalbumin and is applicable to any protein. Coumarin-3-acetic acid-N-OH-succinimidyl ester (CASE) binds directly to ovalbumin in aqueous solution to form covalent bonds with free amino groups. The attached CASE residues can then be radiolabelled by the chloramine-T method. This offers an inexpensive alternative to the Bolton and Hunter reagent with the advantage that CASE is fluorescent. This property, apart from direct use as a fluorescent tag, allows one to monitor the conjugate before radiolabelling. Below a conjugation ratio of 9:1, CASE-ovalbumin retained full antigenic identity with ovalbumin.

Animals↗
PubMed1985

Use of the enzyme-linked immunosorbent assay for measurement of allergen-specific antibodies.

A sensitive and specific enzyme-linked immunosorbent assay (ELISA) for allergen-specific IgG antibodies is described. Various solid-phase supports (microtiter plates), coating procedures, binding kinetics, and presentation of allergen in the assay were investigated. Using optimal conditions the indirect ELISA, in which the allergen is coated onto the well, was capable of detecting 2.4 ng/ml specific IgG antibodies to bee venom phospholipase A2(PLA2). The sandwich ELISA, in which the allergen was immobilized via specific antibody precoated onto the well, detected 0.24 ng/ml IgG antibodies to PLA2.

Antibodies, Anti-Idiotypic↗
PubMed1985

Increased sensitivity and specificity of a sandwich ELISA for measurement of IgE antibodies.

We have developed a sandwich enzyme-linked immunosorbent assay (ELISA) for measurement of IgE antibodies to the bee venom allergens phospholipase A2 (PLA2) and hyaluronidase (HYAL). The assay is 10-20 times more sensitive than conventional indirect ELISA or radioallergosorbent test (RAST). Furthermore, by using affinity purified rabbit antibodies to these allergens, the specificity of the test was increased compared to RAST. The use of antibodies to link the antigen to the solid phase removes the dependence on the individual protein's ability to bind to the microtitre plate. The increased sensitivity of the sandwich assay seems to be due to better presentation and retention of antigen on the solid phase.

Antibody Specificity↗
PubMed1985

Altered characteristics of [3H]dopamine release from superfused slices of corpus striatum obtained from rats receiving ethanol in vivo.

Ethanol, 50 mM, in vitro inhibited the release of [3H]dopamine ([3H]DA) induced by depolarisation with 40 mM K+ from slices of corpus striatum of the rat. In contrast, the release of [3H]DA induced by the Ca2+ ionophore (A23187) was enhanced by the presence of ethanol in vitro. When similar preparations were obtained from brains of rats which had received ethanol in vivo chronically by inhalation for 5-7 days the characteristics of release of [3H]DA were altered. Thus, the inhibitory effect of ethanol in vitro on release induced by K+-depolarisation was lost, as was the enhancing effect of ethanol on the release induced by A23187. When release of [3H]DA was studied in the absence of added ethanol the fraction of stored 3H released either by K+-depolarisation or by A23187 was increased in the preparations from animals which had received ethanol in vivo. Similar changes in release induced by A23187, though of lesser magnitude, could be seen in rats which had received ethanol acutely (3 g kg-1 i.p.; 30 min). An even greater fraction of [3H]DA was released by A23187 in preparations from rats which had been made physically dependent on ethanol. These changes in the release characteristics of [3H]DA were still apparent in animals undergoing a physical syndrome of withdrawal from ethanol. The results are discussed in relation to the cellular basis for the development of tolerance to and dependence on ethanol.

Animals↗