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Biomedical subjects

C J Baker

Publications and source records attributed to C J Baker.

At least 235 records · Page 13Linked to original sources
PubMed1979

Heterogenity of serotypes of Neisseria meningitidis that cause endemic disease.

Three collections of strains of Neisseria meningitidis that caused meningococcal disease during nonepidemic periods were serotyped to determine whether serotypes that cause endemic disease are more heterogeneous than those responsible for epidemic disease. Thirty-four strains isolated from pediatric patients in Houston, Texas, from February 1977 to March 1978 were of three separate serogroups and 11 serotypes; 27 contemporary (1977-1978) strains from predominantly military populations, obtained nationwide, were of six serogroups and six serotypes, while 11 strains isolated at military posts in the southwest United States from 1970 through 1976 were of four serogroups and five serotypes. Between 9% and 20% of the strains were nontypable, while type II strains which were responsible for the epidemics in the Northern and Western Hemispheres earlier in the 1970's, accounted for only 20%-44% of the strains. In contast to epidemics, which appear to be caused by a single serotype, endemic meningococcal disease appears to be caused by a broad, heterogeneous distribution of serotypes. Thus, development of a serotype-specific vaccine may have limited application to the prevention of endemic meningococcal disease.

Adult↗
PubMed1979

Opsonic specificity of human antibody to the type III polysaccharide of group B Streptococcus.

The functional significance of vaccine-induced or naturally acquired antibody to the capsular polysaccharide of type III group B Streptococcus was determined in human sera by means of an opsonophagocytic assay. Sera containing a sufficient concentration of type-specific antibody and endogenous serum complement caused a significant reduction (greater than 1 log10) in colony-forming units for each of 22 type III clinical isolates after incubation for 40 min. In contrast, serum with a very low concentration of antibody (0.4 micrograms/ml) killed only one isolate. Absorption of serum containing vaccine-induced antibody with purified native type III polysaccharide decreased opsonophagocytosis by a mean of 1.2 log10 for 11 selected type III strains. These results indicate a lack of major antigenic differences among a wide spectrum of type III strains, since bactericidal activity of human serum is uniformly observed in the presence of complement and sufficient concentrations of antibody to the type III polysaccharide.

Absorption↗
PubMed1979

Modification of the colorimetric assay for chloramphenicol in the presence of bilirubin.

We recently found that bilirubin interferes with the colorimetric chloramphenicol assay of Kakemi et al. (K. T. Kakemi, T. Arita, and S. Ohashi, Yakugaku Zasshi 82:342-345, 1962). Levels of serum bilirubin alone (4 to 6 mg/dl) resulted in apparent concentrations of chloramphenicol which appear to be in the therapeutic range. Concentrations of serum bilirubin greater than 8 mg/dl resulted in levels of apparent chloramphenicol associated with toxicity (>50 mug/ml). Small amounts of activated charcoal added to the isoamyl acetate extraction step of the assay eliminated this interference by bilirubin.

Bilirubin↗
PubMed1979

Transmission and scanning electron microscopy of cell monolayers grown on polymethylpentene coverslips.

Plastic coverslips made of polymethylpentene serve as excellent substrates for growth of bovine endothelial cells, and are easily processed for both transmission (TEM) and scanning (SEM) electron microscopy. Portions of the same coverslip (monolayer) are used for both SEM and TEM examination and are fixed, postfixed, and dehydrated as a single entity. The portion of the coverslip for SEM is then excised, critical point dried, and mounted for sputter coating prior to viewing. The remaining piece of coverslip used for TEM is Epon-Araldite embedded, polymerized, separated from the coverslip by liquid nitrogen immersion, and sectioned either "en face" or in cross section for viewing. Coated glass coverslips are not required and organic solvents such as propylene oxide, acetone, and amyl acetate can be used for dehydration and infiltration. Furthermore, specimens do not require re-embedding or blocks to be glued onto blank capsules before sectioning. The number of cells needed to achieve a monolayer is significantly reduced compared to the usual culture flasks, but are abundant enough to assess ultrastructural changes accurately. Support films may be required to prevent folding of the ultrathin section which can obstruct viewing of cells located on the edge of the section.

Animals↗
PubMed1978

An etiologic shift in infantile osteomyelitis: the emergence of the group B streptococcus.

Twenty-one infants from six to 52 days of age (mean 23.3 days) with osteomyelitis were studied between 1965 and 1977. The etiologic agents were group B streptococcus (8), staphylococcus aureus (6), gramnegative bacilli (4), Streptococcus pneumoniae (1), and unknown (2). Patients with group B streptococcal osteomyelitis were characterized by an uncomplicated neonatal course, single bone involvement with a predilection for involvement of the proximal humerus, and lack of inflammatory signs. In contrast, patients with osteomyelitis due to other organisms frequently had had manipulative procedures predisposing to infection and were more likely to have multiple bone involvement, fever, and leukocytosis at the time of diagnosis. Functional impairment was detected in only one of 17 patients evaluated a mean of 36 months after diagnosis.

Female↗
PubMed1978

Association of elevated levels of extracellular neuraminidase with clinical isolates of type III group B streptococci.

The level of total extracellular neuraminidase produced by 74 clinical isolates of group B streptococci isolated from diseased or asymptomatically colonized infants was assayed. Extracellular neuraminidase was obtained from concentrated filtrates of exponentially growing cultures of group B streptococci grown in a chemically defined medium (FMC) containing supplemental protein. The total activity of extracellular enzyme produced by these clinical isolates ranged from less than 10 to 360 nmol of sialic acid released per min per mg of cell dry weight. Strains were arbitrarily classified as either nonproducers (less than 10 nmol/min per mg of cell dry weight), low producers (greater than 10 to less than or equal 140 nmol/min per mg of cell dry weight), or high producers (greater than 140 to 360 nmol/min per mg of cell dry weight). Type III isolates from diseased infants were significantly more often classified as high producers than strains of group B streptococci of other serotypes from diseased infants (P less than 0.001). Furthermore, the serotype III strains isolated from neonatal infections were more often high producers than those of the same serotype from asymptomatically colonized infants (P less than 0.025). These results suggest that the ability to produce elevated levels of neuraminidase may be related to the frequent association of type III strains with disease among neonates.

Culture Media↗
PubMed1978

Mycobacterium terrae synovitis and osteomyelitis.

An immunocompromised patient with Mycobacterium terrae synovitis and osteomyelitis is presented. Therapeutic recommendations are made based upon existing knowledge of the pathogenesis, course, and outcome of similar infections with nontuberculous mycobacteria.

Adult↗
PubMed1978

Immunogenicity of polysaccharides from type III, group B Streptococcus.

The immunogenicity and safety of two polysaccharides isolated from type III, group B Streptococcus, were tested in adults selected for existing low concentrations of natural antibody to the capsular polysaccharide of this organism. Both vaccine preparations (trichloroacetic acid and EDTA) were found to lack pyrogenicity and toxicity for experimental animals. A single 50-microgram subcutaneous injection of either polysaccharide in human subjects elicited significant increase in antibody concentration in immunized compared with control individuals receiving phosphate-buffered saline. Antibody responses were maximal by 2 wk and remained at 21 wk after immunization. Vaccine-induced antibody was primarily of the IgG class. Of the two vaccines, the larger molecular size polysaccharide was significantly more immunogenic. Although no systemic reactions were recorded, mild transient local reactions occurred in 45% of vaccinees.

Animals↗
PubMed1978

Pelvic osteomyelitis in children.

Six children (7 to 16 years of age) with pelvic osteomyelitis are described. Sites of involvement included the pubis in three patients, the ilium in two patients, and the ischium in one patient. All were right-sided. Each patient presented with a history of fever and an abnormal gait. In four, the point tenderness indicated the site of bony involvement. All patients had pain on abduction but free passive range of motion of the hip. Soft tissue swelling was present on admission pelvic roentgenograms in five patients. Intravenous pyelogram revealed deviation of the bladder toward the midline in each of four patients studied. Roentgenographic changes typical of osteomyelitis developed in four patients ten days to ten weeks after onset of symptoms. In four patients in whom an organism was identified, Staphylococcus aureus was isolated from blood and/or bone. All isolates were methicillin-sensitive and two were penicillin-sensitive. Purulent material was drained from three of the five patients who underwent surgical exploration of the pelvis. All patients received parenteral antistaphylococcal therapy for 3 to 5 1/2 weeks (mean, 4 weeks). Oral antibiotics were given to five patients for an additional 3 to 14 weeks. All patients recovered completely.

Adolescent↗
PubMed1977

Vaginal colonization with group B streptococcus: a study in college women.

Vaginal specimens for culture of group B Streptococcus and anonymous questionnaires were obtained from 499 college women. Group B Streptococcus was isolated from 90 (18.0%) of the participants. A selective broth medium was more sensitive for detection of vaginal isolates (85 of 493; 17.2%) than was direct inoculation of blood agar plates (44 of 466; 9.4%). The most prevalent serotypes among the isolates were type III (37.9%) and type II (25.3%). Logit analysis identified four factors associated with a higher prevalence of vaginal colonization with group B Streptococcus. These organisms were isolated significantly more often from (1) women who had an intrauterine device (50% vs. 18.6%; P less than 0.001), (2) sexually experienced women (20% vs. 7.1%; P less than 0.02), (3) women studied during the first half of the menstrual cycle (26.5% vs. 14.5%; P less than 0.01), and (4) women 20 years of age or younger (21.4% vs. 14.8%; P less than 0.05). The prevalence of colonization with group B Streptococcus was not related to sexual practices, history of venereal disease, use of oral contraceptives, presence of gynecologic symptoms, use of antibiotics, race, educational level, marital status, or history of pregnancy.

Adult↗
PubMed1977

Immunological investigation of infants with septicemia or meningitis due to group B Streptococcus.

Purified polysaccharide from type III group B Streptococcus contains both a type III-specific determinant and another determinant that is common to strains of serotypes other than type III. The polysaccharide contains sialic acid, galactose, heptose, glucose, glucosamine, and mannose. Serum antibody to this antigen was measured by means of a radioactive antigen-binding assay. Sera from 36 (67.9%) of 53 women with healthy newoborns contained antibody, a prevalence significantly different from that in sera from 15 women (13.3%) whose neonates developed septicemia or meningitis due to type III group B Streptococcus. Complete concordance for presence or absence of anticapsular antibody in sera from 14 women at delivery and in their neonates' cord sera was demonstrated; this concordance indicates transplacental transfer of antibody. Sera from each of four adults with invasive infection who were studied during convalescence contained antibody to the capsular polysaccharide of type III group B Streptococcus. In contrast, antibody was absent from 10 infants who had recovered from bacteremia, septicemia, and/or meningitis due to type III group B Streptococcus.

Antibodies, Bacterial↗
PubMed1977

Quantitative determination of antibody to capsular polysaccharide in infection with type III strains of group B Streptococcus.

The development of antibody in response to invasive infection with type III strains of group B Streptococcus was studied in sera from 31 infants and 4 adults by means of a quantitative radioactive antigen-binding assay. Low concentrations of antibody were consistently found in the acute sera of patients who developed clinical illness. Although adults with puerperal sepsis and infants with bone or joint infection uniformly demonstrated significant rises in serum antibody concentration after recovery, much lower levels of antibody were detected in convalescent sera from infants recovering from meningitis or sepsis. The median antibody concentration in sera from 43 parturients with type III strains of group B Streptococcus isolated from vaginal cultures whose neonates failed to develop symptomatic disease was significantly greater than that in sera from 29 mothers of infants with invasive, type III, group B streptococcal infection. Study of paired maternal and cord sera demonstrated a significant correlation between the antibody concentration in a mother's serum and that in her neonate.

Adolescent↗
PubMed1977

Colonization with group B streptococci in girls under 16 years of age.

Cultures from the vagina, pharynx, and anal canal of 100 healthy girls, 2 months through 15 years of age, were examined for the presence of group B streptococci. Of the 100 participants, 20% were colonized at one or more of these three sites. Pharyngeal colonization was detected in 15% of the girls under 11 years of age and in 5% of those over 11 years of age. Colonization at anogenital sites were observed in 19% of participants under 3 years of age, in 25% of those 11 years of age and older, and in only 4% of those between the ages of 3 and 10 years (P less than .025). The concentration of serum antibody directed against the polysaccharide capsular antigen isolated from type III, group B Streptococcus appeared, in part, to be related to increasing age.

Adolescent↗
PubMed1977

Antigenic specificity of opsonophagocytic antibodies in rabbit anti-sera to group B streptococci.

An opsonophagocytic assay has been developed which requires human polymorphonuclear leukocytes, immune serum, and complement for optimal killing of Group B streptococci. Only with all three of these components was killing of greater than 1.0 log10 of the initial inoculum achieved, using rabbit antisera directed to homologous strains of each of the five known serotypes of Group B streptococci. Titers of specific antisera which opsonized the strains and resulted in greater than 1 log 10 reduction of colony-forming units, ranged from 1:100 (serotype Ib) to 1:3200 (serotype Ia). Cross-reactions between serotype-specific sera and heterologous strains were seen in certain instances. Type Ic strain and serotype Ic antiserum demonstrated cross-reactions with types Ia and Ib which were explainable by known shared antigens among these types. The only other cross-reaction which resulted in greater than 1 log 10 reduction in colony-forming units was when unabsorbed antiserum to strain Ia was used to opsonize a strain of serotype III. Opsonization of 10 serotype III strains was demonstrated with a single type III antiserum. Killing of nine of these strains required polymorphonuclear leukocytes, complement, and antiserum, but one strain, D136C, the reference strain, could be killed (greater than 1 log 10 reduction in colony-forming units) without either complement or specific antiserum. Inhibition studies were performed utilizing large m.w. polysaccharide antigens extracted from each serotype. These antigens inhibited opsonization of homologous strains by homologous antisera with 50% inhibition points ranging between 0.5 and 4 mug.

Animals↗
PubMed1976

Correlation of maternal antibody deficiency with susceptibility to neonatal group B streptococcal infection.

We investigated the role of maternal antibody in neonatal Group B streptococcal infection with a radioactive antigen-binding assay employing a purified polysaccharide antigen with both Type III and Group B determinants. Serums from seven women who gave birth to infants who had invasive Group B streptococcal infection with Type III strains were all deficient in antibody. In contrast, serums from 22 of 29 pregnant Type III vaginal carriers whose infants were healthy contained antibody with a prevalence significantly different from that in women delivering infants with Type III disease (P less than 0.01). Three healthy neonates born to women with antibody in serums had demonstrable antibody in umbilical-cord serum. These data suggest that transplacental transfer of maternal antibody protects infants from invasive Group B streptococcal infection with Type III strains.

Animals↗
PubMed1976

Immunochemical characterization of the "native" type III polysaccharide of group B Streptococcus.

The type III polysaccharide of -roup B Streptococcus has been isolated and purified by a method that employs washing of intact cells at neutral pH. That the polysaccharide prepared by this procedure is the "native" type III antigen is suggested by its molecular size in excess of 10(6) daltons, its degradation by acid and heat treatment to a fragment with immunologic characteristics of the classical HCl antigen, and its type-specific serologic activity. The type III polysaccharide in native form contains sialic acid, galactose, glucose, glucosamine, heptose, and mannose. It is acidic in nature, is resistant to neuramindiase degradation, contains no O-acetyl groups, and does not share antigenic determinants with capsular type K1 antigen of Escherichia coli or Group B polysaccharide antigen of Neiserria meningitidis.

Epitopes↗