PubMed Health⌕ Search

Biomedical subjects

W A Clyde

Publications and source records attributed to W A Clyde.

71 records · Page 4Linked to original sources
PubMed1969

Characteristics of virulent, attenuated, and avirulent Mycoplasma pneumoniae strains.

Homologous pairs of virulent and attenuated or avirulent Mycoplasma pneumoniae strains were derived and compared in an effort to elucidate the mechanisms of virulence. These related strains were found to vary in growth, glycolysis, protein electrophoretic patterns, peroxide formation, morphology, and cytadsorption. Variations in the last two characteristics closely correlated with avirulence. This enables understanding of one stage in the pathogenic sequence and provides a convenient marker for avirulence. The derivation of infectious avirulent strains may make possible their use as live vaccines against M. pneumoniae disease.

Animals↗
PubMed1966

Physical properties of human Mycoplasma species.

Kim, Kwang S. (University of North Carolina, Chapel Hill), Wallace A. Clyde, Jr., and Floyd W. Denny. Physical properties of human mycoplasma species. J. Bacteriol. 92:214-219. 1966.-Studies were made of the comparative morphology and stability of five Mycoplasma species of human origin (M. hominis type 1, M. salivarium, M. fermentans, M. pneumoniae, M. pharyngis). Broth-cultivated organisms were examined by electron microscopy to determine their relative appearance after uniform processing, including fixation-drying with formaldehyde vapor. M. pneumoniae was characterized by the occurrence of 250- to 300-mmu spheres in clusters, and M. pharyngis by the appearance of filaments 120 mmu by 1.5 to 8 mu; the remaining species revealed a variety of structures, including spheres, rings, and short filaments. To complement these findings, the effect of physical stresses on viability of the mycoplasmas was measured by exposing the organisms to heat (in saline), osmotic variations (in sucrose), and sonic oscillation and repetitive freeze-thawing (in culture medium). M. pneumoniae was most resistant to heat, vibration, and freeze-thawing; M. pharyngis was most sensitive to heart and vibration, but was least affected by osmotic changes. The remaining organisms assumed intermediate positions. The type-related variations in relative morphology and stability suggest differing physical attributes of the mycoplasmas studied, supporting taxonomic differentiation of the five species based on metabolic and immunological criteria.

Freezing↗
PubMedDate not supplied

Mycoplasma pneumoniae infections of man: integration of attachment mechanism, cellular responses and clinical manifestations.

Research advances of recent years are permitting new understanding of M. pneumoniae disease pathogenesis, although our knowledge remains incomplete. Colonization of the respiratory tract mucosa, mediated by an attachment protein, leads to specialized cell injury and altered muco-ciliary clearance. Pulmonary cellular infiltrates and airway exudates are a mixture of both non-specific and specific host immune responsiveness to the mycoplasma. It is now possible to begin integration of the organism's molecular biology and the clinical manifestations of infection.

Antibodies, Monoclonal↗
PubMedDate not supplied

The longitudinal approach to the pathogenesis of respiratory disease.

Longitudinal observations were made of a well-defined population of children at a day care center in an investigation of the pathogenesis of infections due to respiratory syncytial virus (RSV) and Mycoplasma pneumoniae. A single RSV infection induced a modest but significant degree of resistance to further RSV infection in these children. Age and immunity seemed to interact to decrease the intensity of the clinical expression of illness associated with RSV infection. Infants and young children had asymptomatic or mild infections with M. pneumoniae; some of these children also became reinfected. A rise in titer of antibody to M. pneumoniae was demonstrated frequently in children of all ages. However, stimulation of peripheral lymphocytes by M. pneumoniae antigen was demonstrated infrequently in children younger than four years of age but frequently in children older than four years of age. It is speculated that the clinical expression of disease due to M. pneumoniae is modulated by immune responses; this hypothesis would explain the greater severity of illness in older children and young adults than in younger children. It is also speculated that RSV vaccines will not prevent RSV infection but may be expected to lessen the severity of clinical disease that follows such infections. M. pneumoniae vaccines probably should not be used in children because these vaccines may enhance immunity and increase the sevrity of illness.

Child↗
PubMedDate not supplied

Ureaplasma colonization: definitions and epidemiologic implications.

Genital mucosal colonization with Ureaplasma species complicates interpretation of their role as pathogens. From an epidemiologic point of view, colonization should be considered a dynamic process in which knowledge about the habitat colonized is an integral part. The classical criteria of pathogenicity need to be broadened to include qualitative, quantitative, and temporal aspects as disease associations of ureaplasmas are explored.

Genitalia↗
PubMedDate not supplied

Location of attachment moiety on Mycoplasma pneumoniae.

Mycoplasma pneumoniae initiates infection in the human host by attachment to respiratory epithelium. The organism attaches by a specialized terminal structure. Monoclonal antibodies to an organism surface protein (P1) inhibited attachment to respiratory epithelium and were localized to the tip structure by a ferritin antibody label. The P1 protein was degraded by trypsin treatment to smaller polypeptides that possessed the same antigenic determinants as the larger P1 protein when reacted with the specific monoclonal antibody, and evidence has been provided for the existence of multiple antigenic determinants on the attachment protein.

Adhesins, Bacterial↗
PubMedDate not supplied

Mycoplasma pneumoniae respiratory disease symposium: summation and significance.

The symposium on M. pneumoniae respiratory disease has examined the clinical expression of infection in adults and children, the pathophysiologic disturbances which occur, and the laboratory diagnosis by isolation and serology. That these infections are very common has been well documented; however, a variable incidence over periods of several years tends to minimize importance of the disease for many clinicians. While good laboratory diagnostic methods exist, they provide retrospective insight predominantly and are not useful for early diagnosis or therapeutic decision making. Development of rapid diagnostic methods which are sensitive and specific is an important goal for future research. Success would facilitate our understanding and control of M. pneumoniae disease.

Adolescent↗