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C Brossard

Publications and source records attributed to C Brossard.

26 records · Page 2Linked to original sources
PubMed1981

Characteristics of a lipid preparation (lipid A) from Haemophilus influenzae type a lipopolysaccharide.

Mild hydrolysis of Haemophilus influenzae type a lipopolysaccharide by ion exchangers yielded a lipid A extracted by chloroform. It contained phosphorus, glucosamine, and fatty acids. Myristic, palmitic, 3-hydroxymyristic, and oleic acids and two other unidentified long-chain fatty acids were found. The free lipid A was not toxic for mice at doses of up to 50 mg/kg and did not provoke a Shwartzman reaction. The Limulus test activity was positive up to 10(-12) g/ml, but the pyrogenicity in rabbits was lower than with the original lipopolysaccharide. However, the lipid A did induced a mitogenic response and polyclonal B-cell activation in mouse spleen cell cultures. Complexing lipid A with bovine serum albumin gave a nontoxic preparation which lost these immunological activities. Immunochemical studies showed that the major reactive determinants of this lipid-protein complex were altered after such a linkage. Consequently, the nontoxic and mitogenic lipid A isolated from H. influenzae type a did not exhibit all of the classical activities of lipid A preparations.

Animals↗
PubMed1980

Comparative study of biological activities and mitogenic effect of extracts from Haemophilus influenzae type a.

Two preparations designated as PWE and NCE were obtained from H, influenzae type a by treatment with either phenol water or hypertonic NaCl citrate respectively. The protein content of NCE was three fold higher than for PWE. Electroimmunodiffusion against H. influenzae antiserum disclosed an immunological relationship between NCE and PWE. The toxicity for mice was lower for both antigenic extracts (LD50 PWE: 47 +/- 7 mg/kg; LD50 NCE: 943 +/- 5 mg/kg) than for E. coli LPS. Limulus assay showed that both H. influenzae extracts had a weaker potency (100 to 1000 times less) than E. coli LPS. Sanarelli and Shwartzman reactions failed for PWE and NCE. The blast transformation of DBA/2 and nude mouse spleen cells were strikingly different for the three preparations: PWE, NCE, and E. coli LPS. Neither extract from H. influenzae cells showed the biological properties of a classical endotoxin. We suggest that they are endotoxin-like substances.

Animals↗
PubMed1980

Preparation of a nontoxic and immunogenic polysaccharide fraction from a Haemophilus influenzae phenol-water extract.

A phenol-water extract from Haemophilus influenzae type a was hydrolyzed to decrease the toxicity without affecting the antigenicity of the preparation. We used partial hydrolysis for 15 h with ion exchangers in the presence of chloroform. The lipid fraction was collected into the organic solvent. The preparation obtained from the aqueous solution was designated the polysaccharide fraction. Rhamnose, glucose, galactose, mannose, and glucosamine were the major components of the polysaccharide fraction, and their molar ratios were determined by gas-liquid chromatography; 2.5% myristic acid was also found in the polysaccharide fraction. The mild hydrolysis of the polysaccharide fraction for 15 h caused a marked reduction in toxicity (50% lethal dose, 183 +/- 9 microgram/kg) and pyrogenicity. The generalized Sanarelli reaction was negative. The local Shwartzman phenomenon was not observed if chloroform and Dowex were exchanged three times during hydrolysis. Most of the antigenic components remained active after the hydrolytic process. The polysaccharide fraction could also induce the formation of circulating antibodies in rabbits and also increase the phagocytic process against H. influenzae from month 2 to 6.

Animals↗
PubMed1980

[Studies on an extract from Haemophilus influenzae type a. I.--Antigenic and immunogenic studies (author's transl)].

Haemophilus influenzae is the bacteria most commonly found in chronical bronchitis not treated by antibiotic therapy. Experimental studies have suggested that the destruction of the ciliated respiratory epithelium is in conjunction with the toxic product of the cell-wall of this bacteria. Endotoxin is extracted by phenol-water procedure. Toxicity is reduced by mild hydrolysis. Antigenicity of the preparation is controlled by gel diffusion in a parallel sides-tank diffusion and electroimmunodiffusion. These methods show that common antigenicity is not affected by hydrolysis. After immunisation by that preparation, circulating antibodies are detected by passive hemagglutination and immuno-precipitation. The immunized rabbits have agglutinin titer of 1 : 256th. Antigenicity of this bacterial extract is preserved and the preparation is still immunogenic.

Animals↗
PubMed1980

[Studies on an extract from Haemophilus influenzae type a. II.--Phagocytic capacity of sera obtained from rabbits immunized by this bacterial extract (author's transl)].

Opsonins may protect against infections. In this study, the different parameters of opsonization assay are strictly standardized. Results are expressed as percentage of opsonization. 0% and 100% opsonization must be established. The experiment without immunserum is used as the 0% opsonization. To determine the 100% opsonization an excess of reducing capacity is required. This is provided by crushed leukocytes. Rabbits are immunised by bacterial extract from Haemophilus influenzae type a. The hemagglutinins are detected in sera earlier (D + 30) and longer than the opsonic activity. Phagocytosis increases from the second month following the immunization. Percentage of opsonization is maintained at about 50% up to the sixth month. Alternatively, the percentage of phagocytosis is decreasing when heterologous bacteria are used. The serum thermolabile factors are necessary for the response. The phagocytic capacity is not modified whether leukocytes are obtained from immunized rabbits or not.

Animals↗
PubMed1979

Chemical composition and biological activities of a phenol-water extract from Haemophilus influenzae type a.

Ribonucleic acid was removed from a phenol-water extract of Haemophilus influenzae type a by streptomycin sulfate. This preparation was called purified preparation or PP. It contained neutral sugars (glucose, galactose, mannose, pentose), glucosamine, amino acids, and fatty acids. Heptose and 2-keto-3-deoxyoctonic acid were not present. The biological properties and immunogenicity were compared with the activities of lipopolysaccharide of Escherichia coli or Salmonella typhimurium. Higher doses were necessary to obtain lethality in mice and Sanarelli and Shwartzman reactions with our preparations than were necessary with lipopolysaccharide. The Limulus test and pyrogen assay in rabbits gave the same results with purified preparation and lipopolysaccharide, but pyrogenicity of purified preparation was not destroyed by NaOH treatment. Purified preparation was not as immunogenic at low doeses for rabbits as lipopolysaccharide. The results were different from those obtained with lipopolysaccharide but similar to those known from peptidoglycan studies. The contamination of purified preparation with peptidoglycan was negligible and cannot explain the biological activities of purified preparation. We suggest that the phenol-water extract from H. influenzae is not a classical endotoxin, but rather an endotoxin-like substance.

Animals↗
PubMedDate not supplied

[Prolongation of theophylline derivative release with cellulose acetate based tablets].

Sustained-release tablets were prepared with three theophylline compounds of increasing solubility: theophylline, dyphylline and proxyphylline. Cellulose acetate was used as the matrix polymer. Two formulation parameters were studied: incorporated theophylline dose and percentage of polymer constituting the matrix. Drug release was enhanced as these parameter values rose. A mixed mineral and plastic matrix was formed by the two insoluble excipients, i.e. cellulose acetate and dibasic calcium phosphate for direct compression. Drug release could be optimized either by 2(2) factorial analysis or by multiple linear regression. Drug solubility was found to have an especially important influence on the release and did not allow sustained-release tablets to be obtained when it was too great. In the case of dyphylline and proxyphylline, only the additional application of a barrier-coating over the surface of the matrix tablets enabled prevention of their premature erosion and the massive release of drugs.

Cellulose↗