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Biomedical subjects

C J Baker

Publications and source records attributed to C J Baker.

At least 181 records · Page 10Linked to original sources
PubMed1984

Two unlinked genetic loci interact to control the human immune response to type III group B streptococcal antigen.

Serum samples were collected from 30 healthy adult Caucasian volunteers before and after immunization with native type III polysaccharide of group B streptococcus. Serum antibody to this polysaccharide was measured and sera were typed for several Gm and Km(1) allotypes. A significant interactive effect of Gm(23) and Km(1) was found on immune responsiveness to native type III group B streptococcus polysaccharide antigen.

Antigens, Bacterial↗
PubMed1984

Chemical Characterization of the Lipopolysaccharide of Pseudomonas solanacearum.

The carbohydrates present in lipopolysaccharide (LPS) from Pseudomonas solanacearum are rhamnose, xylose, 2-amino-2-deoxyglucose, glucose, heptose, and 2-keto-3-deoxyoctonate. LPS extracted from cultures grown on either glycerol or glucose (as the major source of carbon) and extracted after various incubation periods had similar compositions. The LPS from several strains of the bacterium contained the same component sugars, but the amounts of each sugar varied considerably. It was observed, however, that xylose and 2-amino-2-deoxyglucose increased proportionately with rhamnose, the major component. Phenol-water-extracted LPS contained measurable amounts of nucleic acid, protein, and arabinan, but none of these polymers were detected in LPS extracted with phenol-chloroform-petroleum ether. Polysaccharides liberated from LPS by mild acid hydrolysis were purified by gel filtration. Carbohydrate analysis of the LPS from a virulent, fluidal strain (K60) showed that the O-specific antigen consisted of rhamnose, xylose, and 2-amino-2-deoxyglucose in the proportions 4:1:1. The LPS of an avirulent, afluidal strain (B1) lacked the O-specific antigen; the R-core region consisted of rhamnose, glucose, heptose, and 2-keto-3-deoxyoctonate. Methylation analysis indicated that the K60 O-specific antigen was composed of a hexasaccharide repeating unit containing 3-, 2-, and 3,4-substituted rhamnopyranosyl residues, 3-substituted 2-amino-2-deoxyglucose, and terminal xylopyranose in the molar ratios 2:1:1:1:1.

Journal Article↗
PubMed1984

Class specificity of naturally acquired and vaccine-induced antibody to type III group B streptococcal capsular polysaccharide: determination with a radioimmunoprecipitin assay.

A radioimmunoprecipitin test was developed to determine the immunoglobulin class distribution of naturally acquired and vaccine-induced antibody to the native capsular polysaccharide of type III group B streptococci (III-GBS). In sera from adults and pregnant women with naturally acquired antibody, the mean percentage of antigen bound by immunoglobulin G (IgG) was 74.9 and 78.6, respectively, whereas antigen bound by IgM comprised less than 10% of the total. In contrast, early-convalescent-phase sera (mean, 16.3 days) from neonates responding to III-GBS infection with an increase in specific antibody had significantly more IgM (mean, 36%; P less than 0.001, unpaired t test). However, in late convalescence, the immunoglobulin class distribution in sera from these neonates was similar to that of naturally immune adults. Four weeks after immunization with III-GBS polysaccharide vaccine, sera from adults with low (less than 2 micrograms/ml) preimmunization antibody levels in their sera and from those with moderate (mean, 5.5 micrograms/ml) preimmunization levels contained specific antibody predominantly of the IgG class. Although the percentage of IgG-specific antibody was greater in sera from naturally immune adults than in that from vaccinees with a presumed primary immune response, the major portion of antigen bound by sera at 4 weeks postimmunization (62.5%) was associated with IgG. These observations support the opinion that immunization of pregnant women with III-GBS capsular polysaccharide could be efficacious for the prevention of invasive neonatal III-GBS disease.

Adult↗
PubMed1984

Detection of group B streptococcal antigen in body fluids by a latex-coupled monoclonal antibody assay.

A commercially available latex agglutination reagent, Directigen (Hynson, Westcott & Dunning, Div. Becton Dickinson & Co., Baltimore, Md.), in which a murine monoclonal antibody to group B streptococcal (GBS) antigen is the active component, was evaluated by using body fluid specimens from 94 sick infants. Antigen was detected in one or more admission specimens from 18 of 19 (94.7%) infants with symptomatic GBS infection. In 15 patients with GBS meningitis, cerebrospinal fluid, serum, and 10-fold-concentrated urine specimens were positive in 87, 50, and 100%, respectively. GBS antigen was detected in 50% of unconcentrated urines, but in no sera from infants with nonmeningitic GBS sepsis. Among specimens from 27 infants with invasive infection due to organisms other than GBS and from 48 culture-negative sick infants, false-positive latex agglutination reactions occurred in only 4 (9.5%) urine specimens and in no cerebrospinal fluid or serum specimens. The 94.7% sensitivity and specificity of the Directigen GBS test indicate that it is a useful reagent for the rapid diagnosis of invasive GBS infection in young infants.

Antibodies, Monoclonal↗
PubMed1983

Antibody to type III group B Streptococcus in the rhesus monkey.

Susceptibility to infection due to intra-amniotic type III group B streptococcal infection was studied in 27 rhesus monkeys. Sera from mothers and their offspring were tested to determine the concentration of antibody to the native type III group B Streptococcus antigen. Among 17 controls there was a statistically significant association between the concentration of maternal antibody prior to infection and both the neonatal survival rate and survival time (P less than 0.05). Neonatal survival was decreased to less than or equal to 6 hours (P = 0.005) if the maternal antibody concentration was less than 0.5 micrograms/ml. Modified immune serum globulin was given intravenously to the mothers prior to intra-amniotic infection with (five animals) or without (five animals) neonatal modified immune serum globulin. Neither of the modified immune serum globulin groups demonstrated a significant reduction in the neonatal mortality rate; however, the addition of the modified immune serum globulin provided protection against rapid neonatal death among those animals born to mothers which had low or no detectable antibody. All maternal groups developed a significant increase in the concentration of antibody in postpartum sera. These results indicate that both naturally acquired and passive (modified immune serum globulin) antibodies to type III group B Streptococcus antigen are partially protective against intra-amniotic infection.

Animals↗
PubMed1983

Single oral dose metronidazole therapy for Gardnerella vaginalis vaginitis in adolescent females.

This study briefly reviews Gardnerella vaginalis as a primary vaginal pathogen and assesses the efficacy and safety of therapy with a single, 2-g oral dose of metronidazole. Over a period of 20 months, 882 symptomatic adolescent girls had positive cultures for G. vaginalis. All were post-menarcheal. No other vaginal pathogen was isolated in 609. The total group had a second culture 5-7 days after treatment. Cultures taken after treatment were negative in 95% of those treated with a single 2-g dose of metronidazole. Symptoms abated with therapy and culture negativity. Side effects were limited to infrequent, minor gastric distress. Our results suggest the utility of a simplified, one-dose regimen with high efficacy, insignificant side effects, and a lower cost per patient than the current dosage schedule of 500 mg b.i.d. for 7 days.

Adolescent↗
PubMed1983

Role of adherence in the pathogenesis of neonatal group B streptococcal infection.

The ability of group B streptococci to attach to buccal epithelial cells from adult volunteers, healthy neonates, and infants with invasive group B streptococcal infection was assessed by using (3)H-labeled bacteria incubated at a bacteria-to-cells ratio of 1,000:1. Type III group B streptococcal clinical isolates adhered significantly better to the epithelial cells of healthy neonates than to those of adults (mean bacteria per cell of 31 versus 7, respectively; P < 0.005). In contrast, no statistically significant differences in adherence of type Ia or type II strains to cells of neonates and adults were noted. The adherence of strains isolated from 15 infants with invasive group B streptococcal infection was significantly greater to the cells of infected infants than to those of age-matched controls (mean bacteria per cell of 39 versus 18, respectively; P < 0.005). In contrast, no significant difference was noted in the adherence of a usually adherent type Ia strain and a nonadherent type III strain to the cells of infected infants compared with control infants. These results indicate that the serotype of group B streptococci with the greatest virulence for neonates (type III) adheres better to neonatal than to adult epithelial cells. Infants who develop invasive infection may have an increased number of epithelial cell surface receptor sites for attachment of group B streptococci, the bacteria may elaborate products which unmask receptor sites, or both.

Adhesiveness↗
PubMed1983

Species distribution of non-group D alpha-hemolytic streptococci in maternal genital and neonatal blood cultures.

At our hospital (Jefferson Davis Hospital, Houston, Tex.) since 1979, non-group D alpha-hemolytic streptococci have been isolated with increasing frequency from neonatal blood cultures with clinical findings of sepsis. A total of 47 such isolates were identified to the species level by the scheme of Facklam and were compared with 57 genital isolates from 167 maternity patients. Among the genital isolates, S. sanguis II and S. MG-intermedius accounted for 53 and 28%, respectively, and both were significantly less common in neonatal cultures (23 and 11%, respectively; P less than 0.05). Among neonatal isolates, S. mitis was the single most frequent species (35%), in contrast to its rare occurrence in maternal cultures (3.4%; P less than 0.001). The disparity between the prevalence of S. mitis in neonatal compared with maternal cultures suggests that this species of non-group D alpha-hemolytic streptococci may have increased virulence in neonatal hosts.

Female↗
PubMed1983

Immunochemical analysis and immunogenicity of the type II group B streptococcal capsular polysaccharide.

The relationship between group B streptococcal (GBS) type-specific antisera and the type II-specific polysaccharide is evaluated from a structural and immunologic viewpoint. Although all GBS type-specific polysaccharides are composed of the same monosaccharides, the type II antigen is more complex structurally and contains these sugars in a molar ratio different from the other antigens. Type II polysaccharide has two side chains. One contains only sialic acid and is less susceptible to acid cleavage than sialic acid residues found on types III, Ia, and Ib polysaccharides. The other side chain is composed of galactose as the only sugar. Immunochemical studies demonstrate that the type II polysaccharide has several immunodeterminants. One of these determinants is likely to be the side-chain galactose, while sialic acid appears to comprise part of another immunodeterminant, more complex than sialic acid alone. A series of cross-reactions is demonstrated between the type II native antigen and antisera to serotypes Ia, III, and Ib by a sensitive radioactive antigen-binding assay, which account for additional, complex immunodeterminants. The strongest of these cross-reactions is with type Ia antiserum and the weakest with Ib antiserum. Since Ia and Ib polysaccharides differ in only one linkage, these findings suggest that the trisaccharide beta D-N-acetyl-glucosamine-p(1 leads to 3) beta D-galactose-p(1 leads to 4) beta D-glucose-p [[beta D-GlcNAcp(1 leads to 3) beta D-Galp(1 leads to 4)beta D-Glcap]] is the likely common site responsible for the interaction of the type II native polysaccharide and type Ia antiserum. Another cross-reaction is observed between type III antiserum and type II native antigen. Inhibition studies indicate that the most likely cross-reactive determinant in this case is [beta D-Galp(1 leads to 4)beta D-GlcNAcp]. Type II polysaccharide has been utilized in a human vaccine trial to test safety and immunogenicity. The polysaccharide is highly immunogenic, inducing an antibody response in 95% of recipients, and nontoxic, with side-effects confined to minimal local reactions. Despite the cross-reactions observed between type-specific antigens and antibody prepared by immunization of rabbits with whole bacteria, which suggest shared immunodeterminants, similar cross-reactions were not detected in human sera after immunization with purified type II polysaccharide.

Adult↗
PubMed1983

Impaired chemotaxigenesis by type III group B streptococci in neonatal sera: relationship to diminished concentration of specific anticapsular antibody and abnormalities of serum complement.

A chemotaxigenesis (CTG) assay employing adult or neonatal sera, type III group B streptococci (GBS) and polymorphonuclear leukocytes (PMNs) was designed to evaluate the role of PMN mobilization in the pathogenesis of type III GBS infection in neonates. Generation of C5a in healthy adult sera with moderate-high (3-40 micrograms/ml) or low (less than or equal to 2 micrograms/ml) levels of specific anticapsular antibody was confirmed by PMN aggregometry and by the neutralization of CTG by goat anti-human C5. CTG was significantly (P less than 0.001) greater in high as compared to low specific antibody-containing adult sera; stepwise increases in CTG occurred when specific IgG was added to untreated, but not heat-inactivated, hypogammaglobulinemic serum. Immunospecificity of CTG was shown by a failure of type III GBS to generate C5a in heterologous (type Ia) high antibody sera. Mean CTG values in three high and 16 low antibody-containing sera from healthy term neonates were 24% and 62% of high (P less than 0.001) and low (P less than 0.01) antibody adult sera, respectively. The addition of both complement and specific IgG to low antibody-containing neonatal sera was required to enhance their CTG activity to high antibody adult values. CTG by type III GBS in neonatal sera-neonatal PMN mixtures was only 25% (high antibody sera) and 14% (low antibody sera) of values for paired maternal sera mixtures reacted with adult PMNs (P less than 0.001). These studies demonstrate that CTG by type III GBS in neonatal sera is markedly diminished and that low concentrations of specific anticapsular antibody and abnormalities of complement function contribute to impaired PMN mobilization in human neonates.

Adult↗
PubMed1983

Influence of age on serogroup distribution of endemic meningococcal disease.

The age distribution of 126 infants and children with disseminated meningococcal disease hospitalized consecutively in Houston between January 1977 and June 1979, and between January 1981 and June 1981 was analyzed and compared with that in the United States as a whole and to that during outbreaks of group B disease in North America and epidemics of group C disease in South America. Eighty-one (64.3%) isolates from Houston cases were serogroup B and 37 (29.4%) were serogroup C Neisseria meningitidis. Children with serogroup C disease were significantly older than those with group B disease (P = .017). Of the children with serogroup B infections, 33% were less than 12 months of age and 8.6% were less than 3 months of age. Of those with serogroup C disease, only 2.7% were less than 3 months of age and the majority (73%) were more than 2 years of age. These age distributions are similar to those reported for the entire United States during endemic periods. In contrast, focal outbreaks of group B meningococcal infection occurred in populations that were significantly older (0.02 greater than P less than .05). Similarly, epidemic disease in South America due to serogroup C strains also occurred in older children when compared with the occurrence of endemic group C disease in the United States (P = .02).

Adolescent↗
PubMed1982

Group B streptococcal cellulitis-adenitis in infants.

Seven infants with group B streptococcal (GBS) cellulitis-adenitis were compared with nine previously described patients. The clinical features of infection included a mean age at onset of five weeks, a male predominance (75%), a history of poor feeding or irritability (94%), and a rapid resolution with appropriate antimicrobial therapy. Bacteremia occurred in 94% of the patients. Type III GBS were associated with 75% of these infections; no antibody response to the capsular antigen of these organisms was detected in convalescent sera. Two of our cases had previously unreported sites of involvement, inguinal lymph nodes and a thyroglossal duct cyst. Four infants (80%) with typical facial or submandibular GBS cellulitis had ipsilateral otitis media at the time of admission. Otitis media with subsequent lymphatic spread to facial or submandibular areas, rather than primary bacteremia, may explain the pathogenesis of these unusual infections.

Cellulitis↗