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Biomedical subjects

H Karch

Publications and source records attributed to H Karch.

192 records · Page 11Linked to original sources
PubMed1983

Alteration of the immunoglobulin G subclass responses in mice to lipopolysaccharide: effects of nonbacterial proteins and bacterial membrane phospholipids or outer membrane proteins of Proteus mirabilis.

The immunoglobulin M (IgM) and the IgG1, IgG2ab, and IgG3 subclasses of plaque-forming cells (PFC) specific for lipopolysaccharide (LPS) were measured after immunization of mice with LPS alone and compared with the responses to LPS in combination with nonbacterial proteins and with bacterial membrane phospholipid vesicles or two major outer membrane proteins from Proteus mirabilis. The relative numbers of IgG PFC belonging to the IgG1, IgG2, or IgG3 subclasses induced by immunization with LPS alone depended upon the type of LPS administered. Phospholipids and the proteins effected characteristic alterations in not only the strength but also the subclass of the IgG responses to LPS. The results suggest that the hydrophobic-hydrophilic nature or state of aggregation of the preparations plays a role in the induction of IgG1 and IgG2 subclasses of PFC specific for LPS. Complex formation with LPS and adjuvant was apparently necessary to obtain these effects.

Adjuvants, Immunologic↗
PubMed1983

Modulation of the IgG subclass responses to lipopolysaccharide by bacterial membrane components: differential adjuvant effects produced by primary and secondary stimulation.

The characteristic modulating effects of bacterial membrane adjuvants on the IgG subclass responses to lipopolysaccharide (LPS) were further investigated. Previous studies indicated that more hydrophobic adjuvants preferentially augmented the number of LPS-specific IgG1 plaque-forming cells (PFC) whereas more hydrophilic adjuvants induced predominantly IgG2 PFC, and that complex formation between LPS and adjuvants was necessary for this modulation. In the present report, no carrier effect of adjuvants in the classic immunologic sense could be detected. Undiminished secondary IgG responses to LPS were obtained regardless of which adjuvant was used for the secondary injection. When IgG subclass responses were examined, however, differential effects of adjuvants produced by primary and secondary injections were observed. The adjuvant used in combination with LPS for the primary stimulus determined the number and subclass of LPS-specific IgG memory cells induced: The same or a different adjuvant used with LPS for the secondary stimulus effected the induction of these memory cells to antibody-producing cells. The pattern set by the primary stimulus was not altered by the secondary stimulus, regardless of the potential modulating effect of the second adjuvant.

Adjuvants, Immunologic↗
PubMed1981

Antibody-producing cell responses to an isolated outer membrane protein and to complexes of this antigen with lipopolysaccharide or with vesicles of phospholipids from Proteus mirabilis.

Antibody-producing cell responses of mice to a protein isolated from the outer membrane of Proteus mirabilis were typical of the responses to a thymus-dependent antigen. The immunoglobulin G antibody-producing cell responses to the protein were increased after administration of the antigen complexed with either lipopolysaccharide or with vesicles of phospholipids extracted from P. mirabilis. The protein in turn significantly increased the immune response to lipopolysaccharide and also converted this response from predominantly immunoglobulin M to predominantly immunoglobulin G.

Animals↗
PubMedDate not supplied

A standard immunoglobulin preparation produced from bovine colostra shows antibody reactivity and neutralization activity against Shiga-like toxins and EHEC-hemolysin of Escherichia coli O157:H7.

Enterohemorrhagic Escherichia coli (EHEC) causes a variety of clinical conditions, the most important being hemorrhagic colitis and hemolytic uremic syndrome. A curative therapy of EHEC diseases is not yet feasible. This study investigates the antibody reactivity of Lactobin, a standardized immunoglobulin (Ig) preparation, obtained from the colostra of non-immunized cows. Three different batches of Lactobin exhibited equally high titers of specific antibodies against Shiga-like toxins (SLTs, verocytotoxins) and EHEC hemolysin (EHEC-Hly) produced by E. coli O157. In addition, Lactobin blocked the cytotoxic effect of SLT-I and SLT-II on Vero cell monolayers and inhibited the cytolytic effects of EHEC-Hly on human erythrocytes. Since Lactobin contains high levels of antibodies and neutralizing activity against important virulence factors of EHEC O157, this drug has potential use in the treatment of diarrhea and the prevention of EHEC-associated hemolytic uremic syndrome.

Acyltransferases↗
PubMedDate not supplied

Enterohemorrhagic Escherichia coli (EHEC) in pediatric hemolytic-uremic syndrome: a prospective study in Germany and Austria.

Studies from Europe indicate that infections with enterohemorrhagic Escherichia coli (EHEC) non-O157:H7 strains are increasing in frequency as a cause of hemolytic-uremic syndrome (HUS). In 1997 a prospective study was performed in Germany and Austria to assess the distribution of EHEC serotypes, to characterize the clinical course and to examine environmental aspects. 95 children with a diagnosis of HUS were evaluated in Germany and Austria. Diarrhea, which was bloody in 67%, was reported in 97% of patients. Oligo-/anuria occurred in 76% of patients, of which 63% required dialysis. Two patients showed neurological sequelae at the 2-month follow-up, both of them were infected with non-O157:H7 serotypes. Case fatality in the acute stage was 3/95, in two of these patients EHEC was isolated. Stool and serum specimens were analyzed for the presence of EHEC and antibodies against O157 lipopolysaccharide (LPS). Serotype O157:H7 was identified in 36/58 (62%) isolates, 22 strains (38%) belonged to non-O157:H7. Combining stool culture with serology, EHEC infection was documented in 88% of patients, including three patients without diarrhea. Non-O157:H7 serotypes occurred in 77% of children up to 36 months of age and were the most prevalent serotype in children up to 12 months of age.

Antibodies, Bacterial↗
PubMedDate not supplied

Prevalence of enteropathogenic bacteria in surgically treated chronic inflammatory bowel disease.

BACKGROUND/AIMS: In order to assess the potential impact of bacterial eradication on recurrence rates, the prevalence of various enteropathogenic bacteria and toxins in chronic inflammatory bowel diseases (CIBD) was prospectively examined. METHODOLOGY: Stool, sera and gut tissue samples from a total of 59 patients (33 males, 26 females; mean age: 42 years +/- 14; 21 Crohn's disease, 14 ulcerative colitis, 24 controls) were examined for the presence of enteropathogenic bacteria by culture, immunoblotting and PCR. RESULTS: Conventional cultures failed to detect obligate pathogenic bacteria. By PCR, mycobacteria were found in 85% of all groups, with mycobacterium paratuberculosis not detected. Yersinia species were observed in 63% of patients with Crohn's disease, in 46% of patients with ulcerative colitis, and in 36% of the control patients. Pathogenic E. coli were identified in stool samples of three patients with ulcerative colitis (21%) by amplifying the EAE-gene, one of whom exhibited shiga-like-toxin as well. CONCLUSIONS: We concluded that mycobacteria do not play a causative role in CIBD. Yersinia species seem to persist in intestinal tissue in CIBD patients without adequate immune response and might, thus, contribute to tissue destruction. E. coli infections contribute to the disease process in a small group of patients with ulcerative colitis and their eradication might eliminate the need for immediate surgical intervention.

Adult↗