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Biomedical subjects

G Avenard

Publications and source records attributed to G Avenard.

16 recordsLinked to original sources
PubMed1998

Acute and chronic haemodynamic effects of naftazone in portal hypertensive rats.

It has been demonstrated that hyperproduction of nitric oxide (NO) plays a major role in the vasodilatation of cirrhosis; thus, the vasodilatation might be reversed by an inhibition of NO production. Experimental studies in isolated aortic rings showed that naftazone inhibits the effects of NO production. The aim of this study was to evaluate the haemodynamic effects of acute and chronic administration of naftazone in rats with portal hypertension. Haemodynamic values were measured either before and 10 min after intravenous administration of 432 microg/kg of naftazone or after 4 days of oral administration of 10 mg/kg per day. Acute administration of naftazone significantly reduced portal pressure in portal vein-stenosed and cirrhotic rats. This reduction was related to a decrease in the resistance of the liver and collateral circulation and it was associated with an increased cardiac output. Oral administration of naftazone significantly decreased portal pressure in rats with portal vein stenosis; this decrease depended on a significant reduction of portal blood flow. In both groups, arterial pressure did not change significantly. These haemodynamic effects differed from those observed following prazosin or propranolol administration. However, these effects were similar but less marked than those observed following N-nitro-L-arginine administration in systemic and splanchnic arterial territories. In conclusion, acute and oral administration of naftazone significantly reduces portal pressure by two different mechanisms in portal hypertensive rats. The exact mechanism has, however, to be elucidated.

Animals↗
PubMed1998

Engineered erythrocytes: influence of P50 rightward shift and oxemia on oxygen transport to tissues.

The red blood cell (RBC) membrane may be reversibly opened using a lysis-resealing continuous flow method. The technology was adapted to the internalisation of an allosteric effector of haemoglobin, Inositol-Hexaphosphate (IHP). This molecule, occupying the allosteric site of 2,3 Bis-Phosphoglycerate with a very large affinity, induces a rightward shift of the oxyhaemoglobin dissociation curve (ODC). From ODC parameters in human volunteers, the potential effect of P50 (oxygen pressure at 50% haemoglobin saturation) on oxygen exchangeable fraction (OEF%), for various oxygen partial pressures (oxemia) was evaluated. For hyperoxic or normoxic arterial oxygen pressure (paO2), rightward shift greatly improved OEF%. In optimised conditions, engineered erythrocytes were potentially able to deliver two to three times more oxygen than normal cells. For patients with decreased paO2, as observed in chronic obstructive pulmonary deficiency (COPD), the reduction in arterial oxygen saturation (saO2%) reduces the benefit of the treatment for paO2 values between 60 and 80 mmHg. Below 60 mmHg, the saO2% reduction cannot be compensated by a corresponding reduction in svO2%, particularly for organs with physiologically low svO2%. In these organs, deleterious effects could be observed for a very large rightward shift of the ODC. Such engineered cells have unique properties for oxygen transport improvement and may be used for the treatment of patients suffering from diseases associated with hypoxia and ischemia.

Erythrocytes↗
PubMed1985

[In vitro evaluation and study of the survival of erythrocytes preserved in a saline-adenine-glucose-mannitol medium for 35 days].

The saline-adenine-glucose-mannitol (SAGM) solution for resuspension of red cells was evaluated on 30 blood units tested over 42 days and compared to 5 red cell concentrates collected on the conventional CPD medium. Total and extra-cellular hemoglobin, potassium, pH, ATP and DPG concentrations, osmotic fragility, schizocyte formation, and red cell antigenicity were studied through the storage period. Chromium survival studies of autologous donated red cells were performed in 10 donors. Red cell concentrates resuspended in SAGM solution showed at the 35th day of conservation at 4 degrees C, a mean storage hemolysis of only 0.66%, an ATP concentration of 67% of the initial value, a schizocyte proportion of less than 1.5%, a mean 24 hour posttransfusion viability of 88.33% and a mean red cell T 1/2 survival of 25 days 10 hours. No alteration of common blood group antigens could be found after storage of red cells for 42 days.

Adenine↗
PubMed1985

[Comparison of two skin antiseptics in blood transfusion. Comparison with the results of the bacteriologic control of labile blood products].

The comparison of two skin antiseptics (70 degrees alcohol and 0,5% alcoholic chlorhexidine solution) was carried out by the method of in vivo impressions. The study used 45 healthy volonteers from whom a bacteriological sample was taken from both bends of the elbow, without use of an antiseptic, and after the application of one according to usual sample taking methods. The subjects were divided into two sets according to the antiseptic being tested. The results of the cultures after 24 and 48 hours are expressed in the number of germs per cm2, which thus permits us to calculate a reduction in percentage or log 10 form, and to appreciate the efficiency of the antiseptic studied. Routine bacteriological inspection of labile blood products was carried out on products picked at random every week during 18 months of exclusive use of 70 degrees alcohol by the sample taking services. The results show a comparable in vivo effectiveness of the two antiseptics on the superficial aerobic flora of the bend of the elbow, and the ease of use of 70 degrees alcohol has led to its choice. This choice is confronted with the results of the inspection of blood products: out of 1 293 inspections, only one slight contamination (cocci gram+) was found on a unit of whole blood. These data as a whole can be compared with the work of various authors.

Anti-Infective Agents, Local↗
PubMed1982

Large scale detection of IgA deficient blood donors.

An automated technique using passive haemagglutination inhibition was developed on Groupamatic equipment for the screening of IgA deficient blood donors. Positive controls were also assayed by a manual haemagglutination inhibition test and solid-phase radioimmunoassay. Fourty-two blood donors totally deficient in IgA were detected in the systematic screening of 108,000 blood samples. Thirty-three were partially deficient and 2 other blood donors had an associated anti-IgA class-specific antibody. These donors now belong to a national panel of IgA deficient blood donors and their blood is used for the preparation of various IgA deficient blood components.

Antibodies, Anti-Idiotypic↗
PubMed1980

[Anti-varicella-zona immunoglobulins. Discovery of antibodies and method of formation].

The screening of zoster's antibodies has been performed in blood donors population and persons convalescing from herpes zoster. The results show that 25% of blood donors and 83,5% of convalescents have respectively a titer of CF antibody of 8. Plasma units were pooled and the pool had a final titer of CF antibody of 16. Varicella zoster immunoglobulin prepared by alcohol fractionation had a fluorescent antibody titer of 1 024 and a CF antibody of 512. These results are discussed and compared with those of literature.

Adult↗
PubMed1979

[The prevention of chickenpox in high risk children. Comparison of the effectiveness of specific immunoglobulins and of defibrinated convalescent plasma. 414 cases (author's transl)].

Comparison between 157 children treated with defibrinated convalescent plasma and 257 children treated with specific immunoglobulins revealed the improved effectiveness of the latter treatment in the prevention of chickenpox. Specific Herpes Zoster-Chickenpox immunoglobulins are prepared by caprylic acid fractionation of convalescent plasma. The prevention obtained in more than 90% of cases would appear to be clinically and biologically total as shown by serological surveillance of certain children with particularly severe immune depression.

Chickenpox↗
PubMed1978

[Detection of antitetanic antibodies. Technics (electrosyneresis, Laurell, latex) applied to a high-antibody population].

The human serum of about twenty years old men, recently vaccinated has been tested by Laurell's method (Mesnier and Piquet variant). Purified antitetanic equine serum from Pasteur Institute (P.I.) has been taken as reference. With 5 Lf tetanic toxoid from P.I. concentration we can trust in the results until 50 antitetanics I.U. For richer serum, a 10 Lf toxoid concentration must be used. Correspondance between Pasteur Institute serum and gamma TS (human specific immunoglobulins) is indicated. Technics of Laurell, latex and electroimmunodiffusion are compared. The way to obtain plasma pool with higher antitetanic titre than 8 I.U. from poor and rich plasma is mentionned. The highest rate of titre antibody after the first typhoid diphteria tetanic vaccinal injection is observed between the 11th and 21th day.

Adult↗
PubMedDate not supplied

Preparation of varicella-herpes zoster immunoglobulin.

The efficacy of zoster immunoglobulin in prophylaxis of varicella and herpes zoster is reported by many authors. The screening for zoster's antibodies is performed in the blood donor population and in persons convalescing from herpes zoster. The results show that 25 per cent of blood donors and 83.5 per cent of convalescents, respectively, have CF antibody titer of l6. Varicella zoster immunoglobulin prepared by alcohol fractionation has a fluorescent antibody titer of 1,024 and a CF antibody titer of 512. These results are discussed and compared with those of the literature.

Adult↗