To the Editor.— Recent data indicate that transformation of normal cells by tumor viruses appears to require altered DNA polymerase activity to transcribe new genetic information. Multiple workers have noted the promise for rational cancer chemotherapy of drugs depressing RNA-dependent DNA polymerase ("reverse transcriptase") activity from tumor viruses and human acute leukemia cells. The drugs include rifamycin antibiotics (J Natl Cancer Inst 49:761, 1972) and clinically promising sulfhydryl (SH)-inhibitors (Knock et al in Oncology, Nov, 1972). At concentrations as low as 10μg/ml, clinically useful SH-inhibitors depress "reverse transcriptase" activity of human leukemic lymphocytes to 12% to 16% of control, activity usually far exceeding that of available rifamycins.The SH-inhibitors were selected by performing three in vitro sensitivity tests on hundreds of human cancers: namely agar plate assay, the Kondo sensitivity test, and radioactive tracer studies monitoring the incorporation of labeled precursors to DNA, RNA, and protein of tumors. The three
Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature
Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal
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