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Biomedical subjects

B Crenshaw

Publications and source records attributed to B Crenshaw.

4 recordsLinked to original sources
PubMed2001

Physical activity and exercise training prescriptions for patients.

The dominant outcome from exercise prescription is an increase in various markers of exercise capacity. A very large group of studies have demonstrated that the VO2max is increased in response to exercise performed according to well-accepted principles of exercise prescription. Other markers of exercise capacity, such as the VT, also improve substantially following exercise training. Finally, improvement in exercise capacity is generally related to improved quality of life, particularly in patients with exercise capacity limited by various disease processes. Beyond the specific physiologic gains from training, exercise contributes to a better overall clinical outcome. Although there are few data conclusively demonstrating that exercise independently causes favorable changes in other risk factors, it should be recognized that exercise can contribute indirectly to modulation of other risk factors. Exercise represents positive health advice. Since most of our other recommendations to patients are in the nature of negative advice (e.g., don't smoke, don't eat high-fat foods), and since people are infamous for ignoring negative advice, the value of using a positive recommendation that may indirectly lead the patient to discontinue bad behaviors can hardly be overstated.

Cardiac Rehabilitation↗
PubMed2001

Genital mycoplasmosis in rats: a model for intrauterine infection.

PROBLEM: Microbial infections of the chorioamnion and amniotic fluid have devastating effects on pregnancy outcome and neonatal morbidity and mortality. The mechanisms by which bacterial pathogens cause adverse effects are best addressed by an animal model of the disease with a naturally-occurring pathogen. METHOD OF STUDY: Intrauterine infection in humans as well as genital mycoplasmosis in humans and rodents is reviewed. We describe a genital infection in rats, which provides a model for the role of infection in pregnancy, pregnancy wastage, low birth weight, and fetal infection. RESULTS: Infection of Sprague-Dawley rats with Mycoplasma pulmonis either vaginally or intravenously resulted in decreased litter size, increased adverse pregnancy outcome, and in utero transmission of the microorganism to the fetus. CONCLUSION: Mycoplasma pulmonis is an ideal model to study maternal genital infection during pregnancy, the impact of infections on pregnancy outcome, fetal infection, and maternal-fetal immune interactions.

Animals↗
PubMed2000

Mycoplasma pulmonis genital disease: effect of rat strain on pregnancy outcome.

BACKGROUND AND PURPOSE: Mycoplasma pulmonis is a natural pathogen of the respiratory and genital tracts of rats. Differential susceptibility and severity of the respiratory form of the disease, known as murine respiratory mycoplasmosis (MRM), exist between rat strains. We now report that specific rat strains vary in susceptibility to genital tract infection and pregnancy outcome. METHODS: Specific-pathogen-free (SPF) female F344, LEW, Wistar (WIS) and Sprague Dawley (SD) rats were intravaginally inoculated with 3 x 10(7) colony-forming units (CFU) of M. pulmonis strain X1048 or sterile diluent, and allowed to breed at 10 days after inoculation. Pregnant dams and pups were necropsied within 24 hours of parturition. At necropsy, culture for M. pulmonis was performed on dam and pups, and adverse effects on pregnancy outcome were assessed by determination of the incidence of infertility, fetal resorption, stillbirths, changes in litter size, and pup birth weight. Blood from dams was collected prior to inoculation and at time of necropsy for measurement of IgM and IgG antibodies to M. pulmonis. RESULTS: At time of necropsy, WIS (50%) and SD (60%) dams had a higher frequency of M. pulmonis culture positivity in the genital tract than did LEW (22.2%) and F344 (17.6%) dams. Dams that were still infected with M. pulmonis at time of necropsy had various complications. The SD rats had the greatest degree of adverse effects on pregnancy outcome, which were: infertility, decreased litter size (P < or = 0.01), decreased pup birth weight (P < or = 0.01), increased frequency of resorptions, stillbirths (P < or = 0.05), and the highest rate of pup pulmonary infection (23.1%) (P < or = 0.001). Despite a 50% colonization rate, WIS dams were the least adversely affected. The WIS pups born from M. pulmonis. infected dams had slight decrease in birth weight, and only 6% had pulmonary infections. The LEW infected dams developed infertility and lower numbers of liveborn pups without evidence of vertical transmission. The F344 infected dams had lower numbers of liveborn pups that were smaller than their control counterparts, and none had pulmonary infections. None of the animals had detectable IgM and IgG antibodies to M. pulmonis before inoculation. At time of necropsy, all animals inoculated with M. pulmonis developed significantly (P < or = 0.001) higher amounts of M. pulmonis IgG and IgM antibodies, with SD rats developing the highest amounts (P < or = 0.005). CONCLUSIONS: Both F344 and LEW rats are more resistant to vaginal inoculation with M. pulmonis than are WIS and SD rats. However, only SD dams suffered severe adverse effects on pregnancy outcome. The SD dams also had the greatest IgM and IgG antibody response to M. pulmonis. Our studies clearly indicate differences among rat strains in their susceptibility to vaginal inoculation with M. pulmonis and in secondary complications associated with infection. This system may be a useful model for determining host-specific factors that influence the outcome of natural mycoplasmal infections of the genital tract.

Animals↗