PubMed Health⌕ Search

Biomedical subjects

J Shiloach

Publications and source records attributed to J Shiloach.

At least 73 records · Page 4Linked to original sources
PubMed1991

Preparation, characterization, and immunogenicity of conjugates composed of the O-specific polysaccharide of Shigella dysenteriae type 1 (Shiga's bacillus) bound to tetanus toxoid.

The background for developing conjugate vaccines for shigellosis composed of the O-specific polysaccharide (O-SP) bound to a protein is described elsewhere (C. Y. Chu, R. Schneerson, and J. B. Robbins, submitted for publication). Briefly, there is direct evidence for type (lipopolysaccharide [LPS])-specific protection after infection with the wild type or with attenuated strains of shigellae. Prospective studies of Israeli armed forces recruits show a correlation between preexisting serum immunoglobulin G (IgG) LPS antibodies and resistance to shigellosis (D. Cohen, M. S. Green, C. Block, R. Slephon, and I. Ofek, J. Clin. Microbiol. 29:386-389, 1991). In order to elicit IgG LPS-specific antibodies to Shigella dysenteriae type 1, the O-SP of this pathogen was purified and bound to tetanus toxoid (TT) by three schemes. The most immunogenic used a modification of a published method (C. Y. Chu, R. Schneerson, J. B. Robbins, and S. C. Rastogi, Infect. Immun. 40:245-256, 1983). The resultant O-SP-TT conjugates were stable and elicited high levels of IgG O-SP antibodies and booster responses in young mice when injected subcutaneously in saline at 1/10 the proposed human dose. Adsorption onto alum or concurrent administration with monophosphoryl lipid A enhanced both the IgG and IgM antibody responses to the O-SP of the conjugate; both the nonadsorbed and adsorbed conjugates elicited higher rises of IgG than of IgM antibodies. Clinical evaluations of S. dysenteriae type 1 O-SP-TT conjugates are planned.

Animals↗
PubMed1991

Identity between polysaccharide antigens of Moraxella nonliquefaciens, group B Neisseria meningitidis, and Escherichia coli K1 (non-O acetylated).

A surface polysaccharide antigen of Moraxella nonliquefaciens, reported to be cross-reactive with the capsular polysaccharides of group B Neisseria meningitidis and Escherichia coli K1 (K. Błvre, K. Bryn, O. Closs, N. Hagen, and L. O. Froholm, NIPH Ann. 6:65-73, 1983), was isolated, purified, and characterized chemically, immunologically, and by nuclear magnetic resonance. This polysaccharide was shown to be a linear homopolymer of alpha (2----8)-linked N-acetylneuraminic acid, identical to the capsular polysaccharide of group B N. meningitidis and O-acetyl-negative variants of E. coli K1.

Animals↗
PubMed1990

Production of cholera toxin subunit B by a mutant strain of Vibrio cholerae.

The B subunit (CTB) of cholera toxin (CT) can be used as a carrier protein for conjugate vaccines designed to elicit antipolysaccharide antibodies. A defined medium, AGM4, was designed to grow a high-producing mutant of Vibrio cholerae expressing only the B subunit of CT: V. cholerae 0395-NI. AGM4 contains four amino acids, asparagine, glutamic acid, arginine and serine, salts and a trace element solution. The carbon source is glucose. The fermentations performed in AGM4 indicated that CTB production paralleled the growth of the organism but that there was a maximal release of CTB during the stationary phase. There was a clear optimum of productivity at pH 8.0 and 30 degrees C. The pH had an influence on CTB production and not only on its release. Analysis of the amino acids present in the medium showed a correlation between their consumption rates and CTB productivity.

Amino Acids↗
PubMed1990

Synthesis and immunological properties of conjugates composed of group B streptococcus type III capsular polysaccharide covalently bound to tetanus toxoid.

A synthetic scheme for covalently binding group B streptococcus type III to tetanus toxoid (TT), using adipic acid dihydrazide as a spacer, is described. Type III alone or as a conjugate with TT was injected subcutaneously into laboratory mice, and the type-specific and TT antibody responses elicited by these immunogens were assayed. Type III-TT elicited significantly higher levels of type-specific antibodies after each immunization than did the type III alone. These levels were related to the dosage of the conjugate, enhanced by Freund adjuvant, and exhibited booster responses. Type III alone elicited only immunoglobulin M (IgM) antibodies in Swiss albino mice and mostly IgM and low levels of IgG antibodies of the IgG3 subclass in BALB/c mice. Type III-TT conjugates, in contrast, elicited mostly IgG antibodies in both strains of mice. IgA type III antibodies were not detected. The first two immunizations with the conjugates elicited type III antibodies in the IgG1 and in the IgG3 subclasses. Low levels of IgG2a type III antibodies were detected after a third injection of type III-TT. Conjugate-induced antibodies facilitated opsonization of group B streptococcus type III organisms and did not react with the structurally related pneumococcus type 14. TT alone or as a component of type III-TT induced mostly antibodies of the IgG class: IgG1 levels were the highest of the four subclasses. No IgA TT antibodies were detected. The conjugation procedure, therefore, enhanced the immunogenicity of and conferred T-cell dependent properties to the type III while preserving the immunogenicity of the TT component. The T-cell dependent properties of the conjugates were responsible for stimulating IgG type III antibodies which could be boosted. Evaluation of type III-TT conjugates in antibody-negative women of child-bearing age is planned.

Animals↗
PubMed1990

Synthesis and immunologic properties in mice of vaccines composed of Staphylococcus aureus type 5 and type 8 capsular polysaccharides conjugated to Pseudomonas aeruginosa exotoxin A.

Epidemiological, serological and in vitro phagocytosis experiments provide evidence that the newly discovered type 5 and type 8 capsular polysaccharides (CPs) are both virulence factors and protective antigens for bacteremia caused by Staphylococcus aureus. Neither type 5 nor type 8 CP elicited serum antibodies when injected into mice. These two CPs were bound to Pseudomonas aeruginosa exotoxin A (ETA) to form conjugates by using the synthetic scheme devised for the CP (Vi) of Salmonella typhi and of pneumococcus type 12F (A. Fattom, W. F. Vann, S. C. Szu, A. Sutton, X. Li, D. Bryla, G. Schiffman, J. B. Robbins, and R. Schneerson, Infect. Immun. 56:2292-2298, 1988; S. C. Szu, A. L. Stone, J. D. Robbins, R. Schneerson, and J. B. Robbins, J. Exp. Med. 166:1510-1524, 1987). Both S. aureus CP-ETA conjugates elicited a rise in CP antibodies. As components of conjugates, both S. aureus CPs acquired T-cell-dependent properties, as shown by their ability to respond to carrier priming and to stimulate booster responses. The conjugate-induced antibodies facilitated type-specific opsonization of S. aureus by human polymorphonuclear leukocytes. The conjugates also induced ETA antibodies which neutralized the native toxin in vitro. Clinical studies of these two conjugates for active or passive immunization of patients at risk for S. aureus bacteremia are planned.

ADP Ribose Transferases↗
PubMed1989

Use of a novel air separation system in a fed-batch fermentative culture of Escherichia coli.

A novel air separation system based on permeable membrane gas separation technology was used to cultivate Escherichia coli. The system fulfilled the dissolved oxygen requirements of a culture of E. coli grown on a glucose synthetic medium at a high and constant growth rate of 0.55 h-1. A biomass yield of 45 g (dry weight) per liter was achieved, and no by-product inhibition by acetate or CO2 was observed.

Culture Media↗
PubMed1988

Bordetella pertussis adenylate cyclase. Identification of multiple forms of the enzyme by antibodies.

Two forms of Bordetella pertussis adenylate cyclase of 200 and 47 kDa have been purified from dialyzed urea extract of the bacteria to specific activities of 466 and 1685 mumol.min-1.mg-1, respectively. Both forms are activated 50-200-fold by calmodulin. The half-maximum concentration required for the activation of the 200-kDa catalyst is 5.4.10(-9) M, whereas the one required for activation of the 47-kDa catalyst is 1.8.10(-10) M. Polyclonal antibodies raised against the 47-kDa catalyst specifically recognize both forms of the enzyme in purified state as well as in bacterial extracts on immunoblots. The antibody inhibits at similar titer adenylate cyclase activity of the purified forms as well as the activity present in dialyzed urea extract of the bacteria. It also prevents the penetration of the invasive B. pertussis adenylate cyclase into human lymphocytes. The inhibition induced by the antisera is specific to B. pertussis enzyme, since both calmodulin-dependent brain and sperm adenylate cyclase are not affected by the antibody.

Adenylyl Cyclases↗
PubMed1988

Gi affects the agonist-binding properties of beta-adrenoceptors in the presence of Gs.

Pertussis-toxin-catalyzed ADP-ribosylation of Gi in S49 membranes, but not in S49AC- membranes, which lack Gs, induces a threefold reduction of isoproterenol affinity to the beta-adrenoceptors. A similar treatment of turkey erythrocyte membranes, which are devoid of functional Gi, has no effect on beta-agonist affinity to their beta-adrenoceptors. Non-hydrolyzable analogs such as GTP[S] induce a larger decrease in beta-adrenoceptor affinity in S49 cells towards the agonist isoproterenol as compared to pertussis-toxin-catalyzed ADP-ribosylation of Gi. These results suggest that Gi affects beta-adrenoceptor affinity to its agonist and that this interaction requires the presence of Gs. It seems, therefore, that Gi physically interacts with Gs to exert its effects on the receptor and probably on adenylate cyclase as well. Our ability to detect (a) the effect of pertussis-toxin-catalyzed ADP-ribosylation in S49 cells on beta-agonist affinity and (b) the quantitative difference between the effect of pertussis toxin (approx. threefold) and GTP[S] (fivefold to sevenfold) depends on the use of a simple but rigorous method to study in detail the affinity of beta-agonists to their receptors. This method seems to be superior to the analysis of displacement curves as a means to examine receptor-ligand interactions.

Adenylate Cyclase Toxin↗
PubMed1988

Clinical, metabolic, and antibody responses of adult volunteers to an investigational vaccine composed of pertussis toxin inactivated by hydrogen peroxide.

A toxoid vaccine, composed of purified pertussis toxin inactivated with H2O2 (NICHD-Ptxd), was developed on the basis of evidence that serum neutralizing antibodies (antitoxin) would confer immunity to pertussis. In vivo and in vitro assays of NICHD-Ptxd showed only trace or nondetectable levels of pyrogenic, adenosine diphosphate-ribosyltransferase, binding and pharmacologic activities. Nevertheless, about 40% of the antigenicity of pertussis toxin was retained. Adult volunteers were injected, two times 6 weeks apart, with either 10 (n = 21), 50 (n = 25), or 75 (n = 30) micrograms/dose of one lot, Ptx-06, adsorbed onto AI(OH)3. Neither fever nor changes in the levels of leukocytes, lymphocytes, fasting blood glucose, or insulin were observed in the volunteers. The optimal immunizing dose, 50 micrograms, induced levels of antitoxin (geometric mean (GM) 302 U) comparable to those found in eight adults convalescent from pertussis (GM 269 U) and greater than those found in 18-month-old children after their fourth dose of diphtheria and tetanus toxoids and pertussis vaccine (GM 20.0 U, p less than 0.001). These data indicate that NICHD-Ptxd is safe and immunogenic in adults, and they justify its evaluation in infants and children.

Adolescent↗
PubMed1988

Large scale preparation of calmodulin.

A rapid large scale purification procedure based on three conventional purification steps, ammonium sulfate fractionation, DEAE cellulose and hydroxylapaptite chromotography yields gram amounts of calmodulin. The protein is more than 98% pure by SDS gel electrophoresis and amino acid composition. It is free of contaminating EGTA or EDTA and the omission of heat treatment or denaturing solvents during the preparation avoids possible denaturation of the protein and minimizes partial proteolysis.

Animals↗
PubMed1987

Development of a defined medium and two-step culturing method for improved exotoxin A yields from Pseudomonas aeruginosa.

A two-step method is described for the production of exotoxin A by Pseudomonas aeruginosa in which a defined growth medium is modified for the toxin production phase. As a result, specific exotoxin A yields comparable to those obtained with complex media were achieved. In the development of this two-step process, several divalent metallic cations (Ca2+, Cu2+, and Mn2+), in addition to iron, were found to inhibit the yield of exotoxin A while Ca2+ and glycerol were found to increase yields. Northern blot analysis of total RNA isolates suggests that these effects on exotoxin A yields are based on events at the transcription level.

ADP Ribose Transferases↗
PubMed1986

Extracts of protozoa contain materials that react specifically in the immunoassay for guinea pig insulin.

Extracts of protozoa contain materials that resemble guinea pig insulin, which is noted for its unusual structure and properties. The protozoan derived materials react in the radioimmunoassay for guinea pig insulin; some but not all of these immunoreactive materials migrate on gel filtration in the position of authentic guinea pig insulin. Experiments were done to exclude artifacts in the assay as well as inadvertent contamination by guinea pig insulin. By immunological methods, we segregated the guinea pig type immunoactivity from that which has rat/pork type immunoactivity. These findings extend our studies of extracts of guinea pig tissues which also have these two types of insulin immunoactivities.

Animals↗
PubMed1986

Quantitative and qualitative analyses of serum antibodies elicited in adults by Haemophilus influenzae type b and pneumococcus type 6A capsular polysaccharide-tetanus toxoid conjugates.

Covalent binding to immunogenic proteins increases the immunogenicity of the capsular polysaccharides of Haemophilus influenzae type b (Hib) and pneumococcus type 6A (Pn6A). Conjugates composed of Hib, Pn6A, or the cross-reacting Escherichia coli K100 covalently bound to tetanus toxoid (TT) were injected into young adult volunteers. Local reactions were common and were probably due to Arthus reactivity mediated by the preexisting antibodies reacting with the TT component of the conjugates. Fever occurred in about 10% of the volunteers after the first injection; no volunteers had fever after the second injection. Similar levels of Hib or Pn6A antibodies were elicited by either 50- or 100-micrograms doses or by concurrent injection of two different conjugates (Hib-TT and Pn6A-TT or Hib-TT and K100-TT). The Hib-TT elicited about a 180-fold increase in Hib antibodies, and the Pn6A-TT conjugate elicited about an 8-fold increase in Pn6A antibodies after one injection. Booster reactions were not elicited in adults; similar levels of antibodies in the five experimental groups suggested that the responses elicited by the conjugates were maximal. A one-way cross-reaction was noted as Pn6A conjugates elicited rises of Hib antibodies in 13 of 20 volunteers; only 4 of 59 volunteers immunized with Hib-TT had increases in Pn6A antibodies. The preimmunization Hib antibodies were composed of immunoglobulin M (IgM), IgA, and IgG. The postimmunization sera showed an increase in all three isotypes; the elevation of the IgG was the highest of the three isotypes. Conjugate-induced antibodies to both the polysaccharide and TT exerted biological activities that have been correlated with immunity. Adsorption of the Hib-TT onto aluminium hydroxide resulted in higher levels and an earlier Hib antibody response in infant rhesus. These results encourage the evaluation of Hib and Pn6A conjugates in human children and infants.

Adjuvants, Immunologic↗
PubMed1985

Escherichia coli K51 and K93 capsular polysaccharides are crossreactive with the group A capsular polysaccharide of Neisseria meningitidis. Immunochemical, biological, and epidemiological studies.

Eleven Escherichia coli strains, crossreactive with the capsular polysaccharide (CPS) of Neisseria meningitidis group A (GrA), were detected among 645 stool isolates from healthy families in Cairo, Egypt. 10 of these strains were of the O107:K93:H27 or O107:K93:SP serotypes and may be considered descendents of a single bacterium or as a clone. The remaining crossreactive strain was of the O7:K51:H18 serotype. None of the 11 strains produced enterotoxins and none were enteroinvasive. The purified CPS of these E. coli strains, as well as a polysaccharide (PS) from B. pumilis, strain Sh17, precipitated with equine GrA (H49) antiserum. A partial identity between the E. coli K93, K51 and Sh17 PS on the one hand and the GrA CPS on the other was observed by double immunodiffusion when reacted against the H49 antiserum. Four K93 strains and one K51 strain were found among 320 E. coli strains from patients at the Clinical Center, National Institutes of Health, and three K93 strains were found in 105 stool samples from children in Copenhagen. The data from these three surveys suggest that these crossreactive E. coli are common organisms and could serve as a stimulus for "natural" GrA CPS antibodies. Quantitative precipitation analysis showed that K51, K93, and Sh17 PS precipitated 25, 46.8, and 50% of H49 antibodies, respectively. Absorption of H49 antiserum with the GrA CPS removed its precipitating activity with the E. coli K93, K51, and Sh17 PS. Absorption of H49 antiserum with either K51 CPS or Sh17 PS removed the homologous crossreactivity only, whereas K93 CPS absorbed both K93 and K51 reactivities. Antibodies, raised by intravenous injection of formalinized E. coli K93 or K51 cells into rabbits, precipitated with GrA CPS and were bactericidal against GrA meningococci. The crossreaction between the E. coli K93 and the GrA CPS was unexpected since these two CPS are compositionally so dissimilar.

Absorption↗