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R D Fletcher

Publications and source records attributed to R D Fletcher.

143 records · Page 8Linked to original sources
PubMed1973

Inhibition of Mycoplasma pneumoniae by actinomycin D.

Growth of Mycoplasma pneumoniae was completely prevented by 0.06 mug of actinomycin D/ml, and 0.00375 mug/ml caused 90% inhibition. It thus appears that M. pneumoniae is more susceptible to actinomycin D than previously reported. Low concentrations (0.019 mug/ml) of the antibiotic primarily inhibited ribonucleic acid synthesis and high concentrations (20 mug/ml) inhibited both ribonucleic and deoxyribonucleic acid synthesis.

Cell Survival↗
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Smoking and obesity are associated with the progression of aortic stenosis.

OBJECTIVE: The purpose of the study was to identify clinical predictors of progression of aortic stenosis. BACKGROUND: The natural history of valvular aortic stenosis includes a latency period followed by an unpredictable progression. Recent investigations have shown an association between risk factors for atherosclerosis and the presence of aortic stenosis. The authors hypothesized that atherosclerosis risk factors are also associated with the progression of aortic stenosis. METHODS: In a retrospective study, patients with a diagnosis of aortic stenosis were identified by continuous wave Doppler and a follow-up study of at least 6 months. Clinical data at the time of the index echocardiogram were obtained from review of patients' medical records. Independent risk factors for the progression of aortic stenosis were identified by stepwise logistic regression analysis. RESULTS: One hundred twenty-three patients were identified, and complete data were obtained for 87 patients (mean age, 70.7 +/- 10 years; men, 81%; mean follow-up, 2.54 +/- 1.6 years). The initial gradient was mild in 61% of patients and moderate in 31%. The mean rate of progression was 6.3 +/- 13 mm Hg/year. Mild aortic stenosis in 36% of patients at the time of the index echocardiogram progressed to moderate or severe over an average of 2.9 +/- 2.0 years. Independent clinical factors associated with a progression of 5 mm Hg/year or greater included a history of smoking (relative risk [RR] = 3.06; 95% confidence interval [CI] = 1.09-8.61; p = 0.034) and body mass index (RR = 1.16; 95% CI = 1.03-1.30; p = 0.013). Hypertension, diabetes, cholesterol, age, gender, and coronary artery disease were not independently associated with progression. CONCLUSIONS: Body mass index and a history of smoking are independent predictors of significant progression of aortic stenosis, defined as > 5 mm Hg/year. The rate of progression of aortic stenosis is variable. However, a substantial number of patients have progression of even initially mild aortic stenosis within a relatively short period of time. The effect of controlling atherosclerosis risk factors on the rate of progression of aortic stenosis remains to be determined.

Aged↗
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Herpes simplex virus type 1 replication in a gingival cell line.

Propagation of herpes simplex virus type 1 (HSV-1) in gingival cells is advantageous since these cells are more definitive than HeLa cells in demonstrating viral-induced cytopathic effects and are easily and economically maintained in the laboratory. They also provide a potential medium for studying oral tissue reactions to HSV-1 infection. HSV-1-induced cytopathic effects are clearly characterized following inoculation with virus from standard laboratory cultures and human infections.

Cell Line↗