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Biomedical subjects

E C Gotschlich

Publications and source records attributed to E C Gotschlich.

At least 73 records · Page 4Linked to original sources
PubMed1983

Bacterial meningitis in Egypt: analysis of CSF isolates from hospital patients in Cairo, 1977-78.

Bacterial meningitis remains a major cause of mortality and morbidity in many countries of the world despite effective antimicrobial therapy. Studies of the etiology and some laboratory characteristics of bacterial meningitis in Egypt were conducted during 1977-1978. All patients suspected of having bacterial meningitis were studied at the time of admission to the two fever hospitals of Cairo. Direct culture, serological identification of the capsular type, and countercurrent-immunoelectrophoresis of 1627 CSF specimens were done. Of these, 276 had bacteria identified either by culture or Gram stain. Pneumococci were the most common and the serotype distribution was similar to that reported from other parts of Africa; second were meningococci with groups C and B predominating; in third place was Haemophilus influenzae type b which caused the highest mortality and had an unusually young age distribution. There were 77 bacterial isolates (22%), including 11 species, designated as "other" because there was no predominant species. There were many "clear" CSF specimens that were found to contain pneumococci, meningococci or H. influenzae type b, confirming the need for more comprehensive laboratory facilities for accurate diagnosis of the etiology of bacterial meningitis.

Adolescent↗
PubMed1982

Binding of C-reactive protein to C-carbohydrate and PC-substituted protein.

Human CRP and the CRPs of other species bind Ca2+ ion. After binding of the divalent cation, CRP binds all phosphate monoesters with a stochiometry of one mole per mole of CRP subunit. Replacement of the phosphate monoester group by other acidic groups or by conversion to a phosphodiester markedly diminishes or abolishes the ability to bind. Phosphorylcholine is bound by CRP with much higher affinity than other phosphate monoesters speaking for a second binding site with specificity for the positively charged trimethylammonium group. The distance separating the phosphate from the positively charged group may be relevant. Protein that has been coupled with phosphorylcholine or phosphorylethanolamine is able to precipitate with CRP. Several natural substances including pneumococcal-C polysaccharide which react with CRP have been found to contain phosphorylcholine. In addition CRP has another binding site accounting for its ability to react with depyruvylated type 4 pneumococcal polysaccharide which does not contain phosphate or choline.

Animals↗
PubMed1982

Purification and partial characterization of the major outer membrane protein of Neisseria gonorrhoeae.

A procedure is described to isolate the major outer membrane protein (protein I) from Neisseria gonorrhoeae in large quantities. The method involves precipitation of protein I by hexadecyltrimethylammonium bromide (CTB) at low ionic strength. CTB is lethal for the gonococci and solubilizes most other proteins. Protein I is brought into solution by raising the ionic strength, and the nucleic acids are subsequently removed by 20% ethanol precipitation. The CTB is removed by precipitating protein I with ethanol and replaced by N-tetradecyl-N,N-dimethyl-3-ammonia-1-propanesulfonate, a dipolar ionic detergent. Further purification is accomplished by ion-exchange and molecular sieve chromatography. Two species of protein I (34,000 daltons [34K] and 32K) were purified by these methods. The purified proteins reacted with antisera prepared against the homologous organisms. The 34K proteins I generated proteolytic fragments upon treatment with trypsin and chymotrypsin similar to those generated by 34K protein in intact gonococci. The amino acid compositions of the three proteins were much like those of other major proteins of gram-negative organisms.

Amino Acid Sequence↗
PubMed1982

The capsule of cryptococcus neoformans passively inhibits phagocytosis of the yeast by macrophages.

We examined the mechanism by which cryptococcal capsular polysaccharide inhibits phagocytosis of Cryptococcus neoformans by macrophages. O-Acetyl and carboxyl groups are major structural features of serotype D polysaccharide. Serotype D capsular polysaccharide or encapsulated whole cryptococci were de-O-acetylated by alkaline hydrolysis with 0.1 M NaOH. Carboxyl groups were reduced by treatment with 1-ethyl-3(3-dimethylaminopropyl)carbodiimide followed by reduction with sodium borohydride. De-O-acetylated or carboxyl-reduced polysaccharides had phagocytosis-inhibiting properties that did not differ appreciably from the untreated polysaccharide; thus, neither the O-acetyl nor the carboxyl groups were essential phagocytosis-inhibiting determinants. Antiserum specific for these noninhibitory groups was obtained by adsorption of cryptococcal antiserum with de-O-acetylated or carboxyl-reduced whole cells to produce antiserum enriched respectively with antibody specific for the O-acetyl and carboxyl groups. These adsorbed antisera showed opsonic activity for the untreated yeast that was similar to the unadsorbed antiserum when these antisera were compared at identical levels of precipitating antibody. We also examined the ability of Fab' fragments of opsonic IgG to reduce the amount of anticapsular IgG needed to opsonize the yeast. No synergy was noted between Fab' fragments and undigested IgG in opsonization. These results are consistent with a passive mechanism for inhibition of phagocytosis. The capsule does not directly modulate phagocytic function, but instead, presents a surface that is not recognized by the phagocyte. This absence of recognition is corrected by opsonizing antibody specific for any surface determinant on the capsule.

Animals↗
PubMed1981

Lipid on capsular polysaccharides of gram-negative bacteria.

Hydrolysis of the meningococcal group A, B, and C, and Escherichia coli K92 polysaccharides by 60% aqueous hydrofluoric acid liberated various 1,2-diacylglycerols. These were extracted with chloroform, trimethylsilylated, and analyzed by gas chromatography-mass spectrometry. Two 1,2-diacylglycerols were the major components isolated. In each polysaccharide, 80 to 90% dipalmitoyl glycerol and 10 to 20% distearoyl glycerol were identified. No monoacylglycerols or mixed diacylglycerols were noted. The presence of the hydrophobic end causes the polysaccharides to aggregate in a micellar form and may be the entity by which the polysaccharide remains attached to the outer membrane of the bacterium giving rise to the structure recognized as a capsule.

Diglycerides↗
PubMed1981

Effects of proteolytic enzymes on the outer membrane proteins of Neisseria gonorrhoeae.

Proteolytic enzymes inhibit the growth of some strains and opacity variants of Neisseria gonorrhoeae. To understand the inhibitory effects of these enzymes, we examined several strains to determine the actions of proteases on the three predominant proteins in gonococcal outer membranes. namely, the major outer membrane protein (protein I), the sometimes-expressed opaque protein (protein II), and protein III. In a comparison of the protein I species expressed by different strains, we observed a pattern based on subunit molecular weight and susceptibility to enzymatic degradation. Protein I species having molecular weights of 34,000 were more susceptible to proteolysis, whereas protein I species having molecular weights of 33,000 were less susceptible, and protein I species having molecular weights of 32,000 were resistant. This pattern was observed both in intact cells and in purified outer membranes. All of the enzymes degraded protein II, but this susceptibility appeared to be influenced in part by the species of protein I present. Protein III was resistant to all of the proteolytic enzymes tested. Based on the resulting fragments from each proteolytic cleavage of proteins I and II and their membrane associations, we suggest how these proteins may be arranged in intact membranes. Our data suggested the presence of an endogenous gonococcal enzyme. This enzyme appeared to degrade proteins I and II into fragments resembling the fragments resulting from the action of chymotrypsin.

Bacterial Proteins↗
PubMed1981

Group C Neisseria meningitidis variant polysaccharide vaccines in children.

The currently United States-licensed group C Neisseria meningitidis vaccine, composed of the O-acetyl-positive capsular polysaccharide, is poorly immunogenic and does not afford protection from disease to infants and young children. Group C N. meningitidis O-acetyl-negative polysaccharide vaccine induces higher titers in adults than does the O-acetyl-positive vaccine. We compared the immunogenicity of these vaccines in 2-year-old children. Reactions were minimal and did not differ between the two vaccines. The postvaccination geometric mean titer was twofold greater in the O-acetyl-negative group (1.58 versus 0.73 micrograms of antibody per ml). The rates of decline in titer were similar in both groups. Further study regarding immunogenicity of and the anamnestic response to the O-acetyl-negative vaccine is warranted in the age group (less than 18 months) at highest risk for invasive meningococcal disease.

Antibodies, Bacterial↗
PubMed1980

Intra-strain heterogeneity of gonococcal pili is related to opacity colony variance.

We have purified pili from isogenic opacity colony variants that were derived from 14 gonococcal strains. Pili purified from opaque colonies of one strain usually differed from pili purified from transparent colonies of the same strain. In 10 of the 14 strains examined, the apparent subunit molecular weight of pilin isolated from the opaque variants was larger than that seen with pilin obtained from transparent variants. In addition there were demonstrable intra-strain differences in the isoelectric point and buoyant density of pili derived from the opacity variants. Because gonococci express differing opacity phenotypes during the menstrual cycle, it is possible that the pili of these organisms may also alter in vivo.

Bacterial Proteins↗
PubMed1979

Association between immunoglobulin allotypes and immune responses to Haemophilus influenzae and Meningococcus polysaccharides.

Serum samples were collected from 20 healthy White and 33 Black infants before and after immunisation with three doses of diphtheria-pertussis-tetanus vaccine and with one dose of Haemophilus influenzae type b polyribose phosphate vaccine and meningococcal group A and group C polysaccharide vaccines. Antibodies to these immunogens were measured and sera were allotyped for several Gm, A2m, and Km antigens. A highly significant association was found between the Km(1) allotype and the immune responses (difference between post-immunisation and pre-immunisation antibody levels) to H. influenzae and meningococcus C polysaccharides in the White children.

Antibodies, Bacterial↗
PubMed1979

Isolation of type-specific polysaccharide antigen from group B type Ib streptococci.

Group B streptococcus type Ib (strain H36B) was subjected to digestion with extracellular muralytic enzymes prepared from Streptomyces albus. Type Ib-specific polysaccharide antigen was isolated from the lysate by alcohol precipitation and Sepharose 6B chromatography. The purified type Ib antigen has a Kd value of 0.31 on a Sepharose 4B column and contains four sugars, galactose, glucose, N-acetyl glucosamine, and sialic acid in a molar ratio of 2.05:0.86:1.00:0.90. Acid treatment (pH 2.0) of this polysaccharide results in partial degradation of the antigen (Kd = 0.41 on Sepharose 4B) with the loss of 93% of the sialic acid. The molar ratio of the remaining sugars in the polysaccharide remains identical to that in the native one. This suggests that the sialic acid is at the terminal position in the molecule. Both intact and acid-treated antigen cross-react with some type Ia and type Ic antisera as a result of the common Iabc determinant, but not with type II and type III antisera. Absorption studies indicate that Ib-specific determinant and Iabc determinant are on the same molecule and that sialic acid is not the cross-reactive determinant.

Antigens, Bacterial↗
PubMed1979

Comparative immunogenicity of vaccines prepared from capsular polysaccharides of group C Neisseria meningitidis O-acetyl-positive and O-acetyl-negative variants and Escherichia coli K92 in adult volunteers.

Three structurally and antigenically similar capsular polysaccharides, two derived from group C Neisseria meningitidis (O-acetyl-positive and O-acetyl-negative variants) and one from Escherichia coli K92, which cross-reacts with polysaccharide from group C N. meningitidis, were compared for their ability to induce anticapsular and bactericidal antibodies to group C N. meningitidis in adult volunteers. All three vaccines elicited group C-specific serum antibodies. The vaccine derived from the O-acetyl-negative variant was the most immunogenic of the three vaccines. With use of radiolabeled O-acetyl-positive group C N. meningitidis polysaccharide antigen, the geometric mean titers of antibody in serum were 41.7 microgram/ml to the O-acetyl-negative variant, 22.8 microgram/ml to the O-acetyl-positive variant, and 7.1 microgram/ml to E. coli K92. Antibodies induced by all three vaccines were bactericidal for both of the group C N. meningitidis polysaccharide variants. An inverse relation between the comparative immunogenicity of the O-acetyl-negative polysaccharide and the virulence of group C N. meningitidis was found.

Adult↗
PubMed1979

Protein K: a new major outer membrane protein found in encapsulated Escherichia coli.

The protein composition of purified outer membranes of 47 Escherichia coli strains was examined by sodium dodecyl sulfate-polyacrylamide gradient gel electrophoresis. Of 33 encapsulated strains, all contained an outer membrane protein distinguishable from previously reported proteins. The 14 non-encapsulated strains with one exception lacked this protein. Because of its apparent association with encapsulation (K antigen) we have named it K protein. The protein was purified nearly to homogeneity by chromatography in the presence of detergents, and its composition was determined. Its amino acid composition does not differ significantly from that reported for protein I, another E. coli major outer membrane protein. Furthermore, the N-terminal amino acid sequence of protein K indicates that it is related to protein I.

Amino Acid Sequence↗