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C Ropars

Publications and source records attributed to C Ropars.

At least 19 recordsLinked to original sources
PubMed1992

Erythrocytes as carriers of new anti-opioid prodrugs: in vitro studies.

In using a reversed hypoosmotic lysis and resealing process, internalization of Naloxone or Naltrexone prodrugs as new opioid antagonists into red blood cells (RBC) can be obtained. We describe the entrapment method and haematological parameters of such RBC carriers. Percentages of internalization range between 35% and 70%, depending on the prodrug. The stability of the different prodrugs within RBC, after in vitro internalization have been compared at 4 degrees C and 37 degrees C. These studies were performed in order to screen and choose the most interesting prodrugs for in vivo studies. Some prodrugs tested appeared to be stable after 24 hours of incubation, but others were not. The intracellular ATP and 2,3 BPG concentrations of RBC carriers were similar to the control.

Drug Carriers↗
PubMed1992

Acetaldehyde, ethanol and acetone concentrations in blood of alcohol-treated mice receiving aldehyde dehydrogenase-loaded erythrocytes.

Blood levels of acetaldehyde (ACh), ethanol and acetone were investigated in mice treated with ethanol for 6 months and receiving compatible erythrocytes (RBCs) overloaded with aldehyde dehydrogenase (AlDH). Following an acute dose of ethanol, ACh levels were significantly lower in these animals than in alcohol-treated mice receiving AlDH-unloaded RBCs, and were similar to the ACh levels of normal mice. The peak ethanol concentration was higher in normal mice than in both groups of alcohol-treated animals, while acetone concentrations were not significantly different in the three groups of animals.

Acetaldehyde↗
PubMed1992

Enhanced O2 transportation during cardiopulmonary bypass in piglets by the use of inositol hexaphosphate loaded red blood cells.

A continuous lysing and resealing of erythrocytes permitted internalization of inositol hexaphosphate (IHP), a strong allosteric effector of Hb, leading to significant rightward shifts of the HbO2 dissociation curve. Twelve piglets were put on cardiopulmonary bypass (CPB) with the heart beating, cooled to 25 degrees C then rewarmed to 37 degrees C before weaning off CPB. AoP, LV pressure, PAP, and cardiac output (CO) were monitored. Blood samples were taken before CPB, at 25 degrees C, at 30 degrees C, at 37 degrees C and after CPB for assessment of blood gases, arterio-venous difference in O2 content, lactates, P50 (partial pressure of O2 at 50% Hb saturation), and ionogram. Control group I included five pigs where the CPB circuit was primed with Ringer's lactate solution and porcine blood. In group II (n = 5), priming was done with Ringer's lactate solution and IHP loaded erythrocytes. P50 was significantly higher during CPB than before surgery in group II (20%), but not in group I (1%). There was a significant increase in VO2 in group II (6.02 ml/min) compared to group I (4.03 ml/min) (p less than 0.05) after CPB. Hemodynamics improved after CPB in group II (mean AoP 42 mmHg and syst LVP 70 mmHg) compared to group I (AoP 25 mmHg and syst LVP 22.5 mmHg). These preliminary results show that O2 transportation at the end of CPB is enhanced and myocardial function is improved in piglets with the use of IHP erythrocytes.

Animals↗
PubMed1979

Human IgE response to the administration of blood components. II. Repeated gammaglobulin injections.

43 adults from a renal dialysis unit staff have received regularly spaced gamma-globulin administrations for hepatitis B prophylaxis. Several blood samples were collected over a prolonged period of time (160 days). Following gamma-globulin administration, anti-immunoglobulin antibodies of the IgE class were detected in 80% of this population, a fortnight after the first injection using serum absorptions on polymerized gamma-globulins or a specific inverse RAST method. The reactivity pattern of these IgE anti-immunoglobulin antibodies was similar to that observed for the anti-immunoglobulin antibodies with "limited specificity" detected by passive hemagglutination, in that they reacted with only one of the immunoglobulins of the panel used for their detection. A decrease of the overall IgE levels was observed in 62% of the subjects for a prolonged period of time following gamma-globulin administration. This suggests a feedback regulation mechanism for the reagin production in man, as it has already been observed in animals. A high incidence of anti-immunoglobulin antibodies of various classes was observed in this study. However, only a small number (4/43) of adverse reactions appeared following gamma-globulin administration. For some of these subjects, the presence of specific IgE anti-immunoglobulin, detected by the inverse-RAST technique, suggests a possible role of such antibodies in some intolerance reactions to gamma-globulin administration.

Absorption↗
PubMed1978

alpha-N-acetyl-D-galactosaminyl- and alpha-D-galactosyltransferase activities in sera of cis AB blood group individuals.

Thirteen cis AB persons from five families were examined for serum glycosyltransferase activities associated with the biosynthesis of A and B blood group characters. Their transferases were generally homogeneous within one family, except for A2/cis AB genotypes, whose A enzyme level was similar to the A2 normal sera, but they varied from one family to another. These activities differed quantitatively and qualitatively from A, B and AB normal sera. Studies of A transferase showed variations in the pH-dependent curve, the effect of cofactors and the capacity of conversion of O red cells into A-active cells. Moreover, A and B transferases behaved differently with respect to their relative levels than did AB heterozygous normal sera. The results were discussed and it was suggested that a mutation of a single enzyme transferring both galactose and N-acetyl-galactosamine could explain these properties.

ABO Blood-Group System↗
PubMed1978

Effects of proteolytic enzymes and neuraminidase on the I and i erythrocyte antigen sites. Quantitative and thermodynamic studies.

The effects of neuraminidase and proteolytic enzymes on I and i reactivities was studied with I and i adult red cells, using radioimmunological methods. An enhanced reactivity after enzyme treatment is not exclusively due to a membrane charge reduction. The increase in site numbers and association constants bring about the gain of the cold agglutinin fixation. The release of N-acetylneuraminic acid residues gradually increases the I antigen site density of I red cells and the i site density of i red cells. Similar behaviour was observed after proteolytic enzyme treatment with papain, bromelin or ficin. The proteolytic treatment of I erythrocyte reveals underlying i receptors on these cells. Following membrane glycoprotein chain removal, anti-i antibodies are specifically fixed on I erythrocytes. The accessibility to antibodies of the determinants responsible for I and i erythrocyte activities was influenced significantly by steric hindrance factors. While N-acetylneuraminic acid release increased antibody affinities for the antigenic receptor, the removal of glycopeptide chains greatly diminished steric hindrance and brought about higher affinity constants. After enzyme treatment, the antigenic structures become more homogeneous in their reaction with antibodies. The heterogeneity of binding constants observed with antigenic determinants of non-treated erythrocytes is probably due to the wide range of spatial distribution of these receptors within the membrane.

Adult↗
PubMed1976

[Acquired B antigen].

Many cases of acquired B antigens, always observed in group A subjects have been so far reported. Most of them were found in patients with digestive tract disease, essentially colonic cancer. An investigation on 200 patients in a gastroenterology department showed that this B-like antigen was quite frequent (10,6%); it occurred only in A1 individuals and was related to infectious syndrome. Immunological and serological studies of many cases had shown that this B-like antigen differs from that of normal B cells. Groupe A1 cells transfused to patients acquired B activity; on the contrary group A2 and O cells remained unchanged. Likewise, only A1 cell became active when incubated in vitro with C. Tertium A., known to contain a deacetylase. In 1970, we postulated that a deacetylase enzyme could be responsible for this B-like antigen: this enzyme could transform the N-acetylgalactosamine (A specific sugar) into galactosamine, which could cross react with anti-B sera. The relationship between the acquired B antigen and a deacetylase was recently confirmed: A1 acquired B cells, chemically acetylated lost their B reactivity and enhanced their A1 activity. A polyagglutinability, different from that associated with T, Tn, Cad, Hempas has been always found in acquired B cells; nervertheless, because of its weakness, it could sometimes be unnoticed. Besides, it disappeared prior to B reactivity in case of recovery. Like acquired B activity, it decreased in low pH medium of after acetylation of the cells. Nevertheless, this polyagglutinability appears, contrarly to acquired B antigen, in vitro, on all the cells, irrespective of their ABO phenotypes. A deacetylation of N-acetyl-neruaminic acid could explain such a phenomenon.

ABO Blood-Group System↗
PubMed1976

[The biochemical aspects of blood group antigens].

The biochemical aspects of the immunodominant structures of blood groups antigens are mainly restricted to the following: ABH and Lewis in secretory fluids or on the red blood cells; P system (P1, P, Pk antigens); MN antigens and related; Tn and Tn antigens; Some hypothesis may be put forward for the I, i antigens. Many other antigens seem to be on the dependence of interactions between proteins and lipids of the red cell membrane; such immunodominant structures are not yet known. Except for the ABH and Lewis groups, the biosynthesis pathways are at present unclear.

ABO Blood-Group System↗
PubMed1976

Groups of alpha-D- galactosyltransferase activity in sera of individuals with normal B phenotype. II. Relationship between transferase activity and red cell agglutinability.

In the Paris population of blood donors with normal B phenotype, two groups can be formed owing to their respective serum alpha-D-galactosyltransferase activity and red cell agglutinability with an anti-B antibody. Both parameters are closely correlated. The agglutinability groups partially overlap. In an African population from various ethnical origins, this correlation was observed only in some individuals. 11 among 20 subjects belonged to a third group defined by a high transferase activity. The third group with the strongest agglutinability previously described by GIBBS et al. [6] were not encountered. On the other hand, serum transferase activity varied inversely as agglutination scores with anti-H (Ulex). Both parameters are closely correlated but not in the same way in Caucasian as in African individuals. In the latter, this relation does not depend on the agglutinability group. The H antigen strength variability, according to ethnical origins, may explain these results.

ABO Blood-Group System↗