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Biomedical subjects

J K Davis

Publications and source records attributed to J K Davis.

At least 55 records · Page 3Linked to original sources
PubMed1988

Clearance of different strains of Mycoplasma pulmonis from the respiratory tract of C3H/HeN mice.

Pathogen-free C3H/HeN mice were exposed by aerosol to Mycoplasma pulmonis PG34(ASH), UAB 5782C, M1, UAB T, or UAB CT, and clearance of mycoplasmas from the nasal passages, trachea, and lungs was determined during the first 72 h postinoculation (PI). There were differences among strains of mycoplasmas in physical removal of organisms and in killing by nonspecific factors in the nasal passages and trachea. The avirulent strain, PG34(ASH), was quickly removed from the nasal passages and trachea. Physical removal of the other mycoplasmal strains occurred slowly, with 60 to 89% of the radioactive label remaining in the nasal passages and trachea even after 72 h. There were significant differences in killing among mycoplasmal strains by nonspecific host mechanisms in the nasal passages, trachea, and lungs. Strain UAB T was quickly killed at all levels of the respiratory tract. Strains UAB 5782C and M1 were killed at all three sites by 2 to 4 h PI. The most virulent strain, UAB CT, was killed much more slowly than the other strains. However, there was no statistical difference in the relative numbers of mycoplasmas present in the lungs at 72 h PI among strains UAB CT, UAB 5782C, and M1. These studies showed that the different mycoplasmal strains were cleared from the respiratory tract by different mechanisms and suggest that the differences in virulence among the mycoplasma strains can be explained, in part, by the differences in elimination of the organisms from the respiratory tract by nonspecific host defense mechanisms.

Aerosols↗
PubMed1988

Natural mycoplasmal infections in isolator-maintained LEW/Tru rats.

For 4 years a colony of cesarean-derived, isolator-maintained LEW/Tru rats was evaluated for mycoplasmal infection by serology, culture and histopathology. Anti-mycoplasmal antibodies were detected by enzyme-linked immunosorbent assay (ELISA), and the colony eventually was found to have inapparent infections of Mycoplasma pulmonis and Mycoplasma arthritidis. Rats, naturally infected with M. pulmonis, remained consistently positive in the M. pulmonis ELISA after their initial seroconversion, and eventually developed clinical signs and lesions of respiratory and genital mycoplasmosis. M. pulmonis was apparently eliminated by serological testing and removal of infected rats. Rats naturally infected with M. arthritidis did not develop clinical or histologic evidence of mycoplasmal disease and their sera gave inconsistent results in the M. pulmonis ELISA, but eventually developed positive M. arthritidis ELISA responses. M. arthritidis was isolated from the genital tract, the intestinal tract, and Harderian gland. In contrast to M. pulmonis, removal of serologically positive animals was not sufficient for elimination of M. arthritidis from the colony.

Animals↗
PubMed1987

Pathogenesis and significance of urogenital mycoplasmal infections.

U. urealyticum and M. hominis can no longer be considered as harmless commensals of the lower genitourinary tract. Both can produce disease in humans. Diagnosis and management of infections due to these organisms must be based upon isolation of the organisms from the affected site and preferably the number of organisms present. Due to the frequent resistance of both organisms to tetracycline, treatment must be based upon appropriate antibiotic sensitivities. For a more detailed description of the basic biology of these organisms and isolation and identification and treatment, the reader is referred to several recent reviews.

Female↗
PubMed1987

Measurement of antibody to Mycoplasma hominis by an enzyme-linked immunoassay and detection of class-specific antibody responses in women with postpartum fever.

The standard conditions for detection of human IgG, IgM, and IgA antibodies to Mycoplasma hominis by an enzyme-linked immunosorbent assay (ELISA) were established with the use of a cell lysate antigen and alkaline phosphatase conjugates. Antigen was used at a concentration of 10 micrograms of protein per milliliter, sera were diluted 1:200, and conjugates were diluted 1:500. Agreement between cultured isolation of M. hominis from the lower genital tract and presence of antibody in 207 women was 71%, 82%, and 86% for IgG, IgM, and IgA, respectively. When the ELISA was compared with the mycoplasmacidal assay, an overall agreement of 81% occurred, with the majority of the discrepancies occurring in the ELISA-positive and mycoplasmacidal-negative category. A linear relationship between end point titer and the A400 value (ELISA or absorbance value at 400 nm) at a standard serum dilution was demonstrated for the IgG, IgM, and IgA classes. Although the ELISA was relatively independent of antigen heterogeneity, no single strain detected more than 87% of positive sera, thus suggesting that optimum detection of antibody to M. hominis by the ELISA will require use of antigen pools derived from multiple strains of M. hominis.

Antibodies, Bacterial↗
PubMed1987

Pulmonary clearance of Mycoplasma pulmonis in C57BL/6N and C3H/HeN mice.

In C57BL/6N and C3H/HeN mice known to be free of all murine pathogens and matched for age, sex, and environmental factors, pulmonary clearance was measured over a 72-h time period after exposure to infectious aerosols of 35S-labeled Mycoplasma pulmonis. Reduced clearance of M. pulmonis in C3H/HeN mice relative to C57BL/6N mice was primarily due to impaired mycoplasmacidal activity in the lungs of the C3H/HeN mice. The C3H/HeN mice also had a slightly slower rate of mechanical transport of radiolabel from the lungs in the first 4 h after infection relative to the C57BL/6N mice but not at any later times. By 72 h after infection (relative to 0 h, C3H/HeN mice had an over 4,000% (1.75 X 10(7) versus 4.30 X 10(5] increase in neutrophils and an over 18,000% (more than 2 orders of magnitude) increase in numbers of M. pulmonis recovered from mechanically disaggregated lungs. In contrast, C57BL/6N mice reduced the number of M. pulmonis present by over 83% (nearly 2 orders of magnitude) before any increase in inflammatory cells, which was only a slight increase in lymphocytes and macrophages at 24 h after infection. These results directly link decreased mycoplasmal pulmonary clearance in C3H/HeN mice with the increased susceptibility to, and severity of, murine respiratory mycoplasmosis observed in this strain. The resistance of C57BL/6N mice appears to be related to nonspecific host defense mechanisms responsible for limiting the extent of infection.

Aerosols↗
PubMed1987

Protein variability among strains of Mycoplasma pulmonis.

The proteins of Mycoplasma pulmonis were examined by two-dimensional polyacrylamide gel electrophoresis and immunoblotting. Comparison of profiles from silver-stained two-dimensional polyacrylamide gel electrophoresis of 18 strains of M. pulmonis allowed identification of five proteins that were strain variable. These variable proteins were not dependent on the medium used to grow the organisms and were shown by reaction with serum samples from naturally infected rats and mice to be produced in vivo and not to be medium components. Identification of strain-variable proteins may lead to an explanation of the differences in properties found among M. pulmonis strains.

Bacterial Proteins↗
PubMed1987

Isolation of Mycoplasma pulmonis membranes and identification of surface antigens.

Labeling of Mycoplasma pulmonis cells by iodination with the Bolton-Hunter reagent was shown to efficiently label membrane-associated proteins without significant loss of viability. Labeled proteins proven to be surface exposed by differential proteolytic digestion were analyzed by autoradiography of two-dimensional polyacrylamide gel electrophoresis (PAGE), and seven labeled major polypeptides were identified. To identify all the membrane-associated antigens, pure membranes were isolated by using the surface-labeled proteins as markers. Analysis of the isolated membranes by autoradiography of both sodium dodecyl sulfate-PAGE and the two-dimensional PAGE indicated that the labeled surface proteins were retained in the pure membranes; by immunoblotting with sera from naturally infected animals, these surface proteins were shown to be the predominant antigens recognized by the host during natural infection.

Antigens, Bacterial↗
PubMed1987

Requirements and selection of an animal model.

There are two broad classes of models: those based on analogy (similar structures imply similar functions), and those based on homology (structures derived from the same evolutionary precursor have the same or similar functions). There are four main categories of animal models: 1) induced or experimental models, that attempt to reproduce conditions found in the original species, 2) spontaneous or natural models, that are recognized as being similar to some condition in the original species, 3) negative or nonreactive models, that are the normal counterparts of a disease model, and 4) orphan models, that are animal diseases for which no human or animal counterpart is known. The selection of any model, but particularly animal models, for research should be based on the following considerations: 1) appropriateness as an analog, 2) transferability of information, 3) genetic uniformity of organisms, where applicable, 4) background knowledge of biological properties, 5) cost and availability, 6) generalizability of the results, 7) ease of and adaptability to experimental manipulation, 8) ecological consequences, and 9) ethical implications. The criteria for selection or rejection of particular animal models also include customary practice within a particular discipline, the existence of diseases or conditions that might complicate results, the existing body of knowledge on the problem under consideration, and special features of the animal, such as unique responses or microflora, that may make a particular species useful.

Animals↗
PubMed1987

Specific vs. nonspecific immune responses in murine respiratory mycoplasmosis.

Murine respiratory mycoplasmosis (MRM), due to Mycoplasma pulmonis, is a chronic respiratory disease in laboratory rats. LEW and F344 rats differ in the severity and progression of disease. LEW rats develop more severe disease than do F344 rats. Also, F344 rats are able to resolve lung and middle ear lesions, but the severity of these lesions in LEW rats continues to increase. LEW lymphocytes produce higher responses in vitro to various mitogens, including M. pulmonis mitogen, than do F344 lymphocytes; this difference is apparently due to higher levels of T-helper cells in LEW rats. The level of infiltration or expansion of mononuclear cells in the submucosa probably depends upon the host's ability to respond to nonspecific stimuli. In contrast to nonspecific responses, F344 rats produce a much higher specific antibody and cellular response to M. pulmonis antigens after immunization, suggesting that F344 rats, in contrast to LEW rats, are able to resolve lesions because they are able to mount an effective immune response to M. pulmonis.

Animals↗
PubMed1987

The role of Klebsiella oxytoca in utero-ovarian infection of B6C3F1 mice.

A disease consisting of suppurative endometritis, salpingitis, perioophoritis and/or peritonitis has been an important problem in aging B6C3F1 mice on some chronic chemical carcinogenicity studies. Klebsiella oxytoca was identified as the most likely causative agent based on cultural isolations from lesions. A study was done to determine prevalence of K. oxytoca in the "normal" flora of mice from different breeding facilities. In a survey of 684 retired female breeder mice from 10 National Institutes of Environmental Health Sciences (NIEHS) and National Cancer Institute (NCI) production facilities, K. oxytoca was isolated from only 1% of nasopharynxes, vaginas and ceca in mice from 7 of 10 facilities. Epizootiology of the natural infection was investigated using the capsular and biochemical typing methods on 97 isolates of K. oxytoca from mice of 11 NIEHS and NCI production facilities and sentinel mice from three National Toxicology Program testing facilities. A few capsular types were associated with either lesions, nonlesion isolation sites, or certain facilities but the capsular typing method was not reproducible. No associations were found for any biotypes. A K. oxytoca isolate (capsular type 20, biotype A) from a typical case of perioophoritis was used in attempts to reproduce the natural disease in Klebsiella-free B6C3F1 female mice. Mice were inoculated at 6 months of age by the intravaginal, intrauterine or intraperitoneal route with one of four doses of K. oxytoca and killed at 4, 7 or 10 months post-infection. Some mice given high doses (10(6) or 10(8) colony forming units) of K. +oxytoca died of septicemia and a few developed mild inflammatory lesions in the uterus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Mycoplasma pulmonis proteins common to murine mycoplasmas.

The proteins of Mycoplasma pulmonis were examined by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and immunoblots using the following sera: antimedium, anti-M. arthritidis, anti-M. collis, anti-M. neurolyticum, and anti-M. muris. Fifteen proteins identified as genus-common were shared by M. pulmonis and at least one other mycoplasmal species. These proteins were shown not to be medium components, based on their reaction with antimedium serum.

Animals↗
PubMed1986

Teenage pregnancy in an urban hospital setting.

Recent research suggests that adverse consequences of teenage pregnancy are largely a function of social background factors and adequacy of prenatal care. This study examines the situation of young mothers with new babies in a low income, urban environment. The study explores the relationship between age and ethnicity and various life circumstance and life style differences which might effect long term developmental outcome. 475 Hispanic and black mothers were interviewed using a structured questionnaire. The majority are poorly educated, single parents. Educational attainment is higher for blacks than for Hispanics and for older mothers than for younger. Older mothers are more likely to be living with the father, to be married, and to have received adequate prenatal care. Hispanic parents are more likely than Blacks to be planning to live together. Hispanic mothers are more likely than blacks to be planning to be the primary caretaker for their babies. Adequacy of prenatal care is related to both prematurity and low birth weight. The implications of these findings are discussed in relation to pregnancy prevention and parenting education programs.

Adolescent↗
PubMed1986

Further studies on genital mycoplasmas in intra-amniotic infection: blood cultures and serologic response.

Mycoplasma hominis is recovered significantly more often in amniotic fluid of women with intra-amniotic infection than in matched control women, but Ureaplasma urealyticum is found in 50% of amniotic fluid samples of both groups. To gain further understanding, we performed blood cultures for genital mycoplasmas and measured serologic responses by a micro enzyme-linked immunosorbent assay method in women with intra-amniotic infection and in control subjects. In blood cultures of 81 women with intra-amniotic infection, M. hominis was isolated in two (2.5%) and U. urealyticum in 11 (13.6%). In 44 control blood cultures, M. hominis was not isolated, and U. urealyticum was recovered in eight (18.2%). These differences were not significant. Serologic response was determined in 86 patients. Rise in antibody to M. hominis was significantly more common in women with intra-amniotic infection and M. hominis in the amniotic fluid than in either women with intra-amniotic infection or control patients without M. hominis. For U. urealyticum antibody response was significantly more common in the intra-amniotic infection group than in control subjects, but there was no association between antibody response and isolation of this organism in amniotic fluid. When M. hominis was found in amniotic fluid or maternal blood, patients were nearly always symptomatic. The high likelihood of serologic response in these cases supports a pathogenic role of M. hominis in intra-amniotic infection. The role of U. urealyticum remains unclear.

Adult↗
PubMed1986

Interrater agreement and predictive validity of faculty ratings of pediatric residents.

In the study reported here attending faculty members completed a 14-item rating scale at the end of each clinical rotation in a general pediatrics residency training program. The rating scale items assessed medical knowledge, interpersonal and professional relationships, and attitudes toward education. Significant interrater agreement occurred primarily on those items concerning medical knowledge, and ratings on these items showed significant correlation with the external criterion of scores on the intraining examination of the American Board of Pediatrics. There was also significant interrater agreement for ratings on the item regarding relationship with coworkers. Intercorrelations of ratings on this item with those concerning medical knowledge were relatively low. There was no correlation between scores on the relationship item and subsequent intraining examination scores.

Clinical Competence↗