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Biomedical subjects

R Stephens

Publications and source records attributed to R Stephens.

At least 163 records · Page 9Linked to original sources
PubMed1977

Mutagenesis by 4-nitrobenzofurazans and furoxans.

15 nitrobenzofurazans and 10 nitrobenzofuroxans synthesized primarily for testing as potential anti-rheumatic drugs were also tested for mutagenicity in Salmonella typhimurium strains TA98 and TA100. The method used involved placing each compound in a "well" cut out of a plate of selective medium previously seeded with the appropriate tester strain, and then adding a rat liver microsome/cofactor mixture to one of the two wells on each plate. This method is considerably cheaper and more convenient than the conventional agar overlay technique, but in the present series of experiments failed to detect 4 compounds which could be detected by the overlay technique. Using a combination of the two techniques, 21 of the 25 compounds tested were found to be mutagenic. All 10 benzofuroxans and 9 of the 15 benzofurazans were detected as direct-acting mutagens with at least one of the two tester strains. Two of the benzofurazans gave positive results only in the presence of rat liver microsomes, and hence are pro-mutagens. One of the 4 benzofurazans which gave negative results for mutagenicity in these tests was found to be an efficient inhibitor of a neutral protease activity found in rheumatic synovial fluid, and may therefore have some potential as an anti-rheumatic drug.

Animals↗
PubMed1976

Hydroxyldaunomycin (Adriamycin) combination chemotherapy in malignant lymphoma.

Combination chemotherapy with CHOP (cyclophosphamide, Adriamycin, vincristine, and prednisone) and HOP (Adrimycin, vincristine, and prednisone, was used as treatment for patients with pathologically staged, advanced non-Hodgkin's lymphoma. Among 204 evaluable patients treated on CHOP there were 71% complete remissions with 92% overall responses. Among the 216 evaluable patients on HOP there were 61% complete remissions and 88% responses. Complete remission rates among patients with histiocytic lymphoma were comparable to those of patients with lymphocytic disease. Patients with nodular lymphoma had higher rates of complete remission than their counterparts with diffuse lymphoma. This was noted with both CHOP (78% vs. 67%) and HOP (67% vs. 60%) induction therapy. Rapid responses were common, as more than 14% of complete remissions and 66% of overall responses were achieved with the first course of treatment. Patients in complete remission have been maintained with either cyclophosphamide, vincristine, and prednisone (COP) or arabinosyl cytosine, vincristine, and prednisone (OAP). After 1 year, 86% of patients on COP and 80% on OAP are projected to be free of disease.

Cyclophosphamide↗
PubMed1976

An assessment of the carcinogenicity of isoniazid in patients with pulmonary tuberculosis.

In an assessment of the carcinogenicity of isoniazid, 3,842 adult tuberculous patients admitted to 2 sanatoria in the period 1950 to 1957 (that is, in the years immediately before and after the introduction of isoniazid) have been followed up for a mean period of over 19 years. Their mortality has been compared with that expected during the same calendar period in a general population group in England and Wales with the same age and sex distribution. The relative risk of death (the observed divided by the expected number of deaths) from all malignant neoplasms in patients first starting chemotherapy in 1950 to 1952, before the general introduction of isoniazid, was 0.8 for those who received isoniazid at some time, compared with 0.5 for those who never received it; for those first starting chemotherapy in 1953 to 1957, after the general introduction of the drug, the respective risks were 1.4 and 1.8. The relative risk of death from malignant neoplasms was 2.1 in the first 4 years after starting the treatment with isoniazid; this high relative risk is unlikely to be attributable to isoniazid and largely disappears subsequently, for in successive 4-year periods it was 1.3, 0.9, 1.2 and 1.4. The relative risks of death from all malignant neoplasms for patients receiving a total dosage of less than 50, 50-99, 100-199 and 200 g or more were 1.5, 1.5, 1.0 and 1.3, respectively. For patients receiving a maximum daily dose of less than 250 g the relative risk was 1.3, and for those receiving 250 g or more it was 1.2. There was a curious and unexplained difference in the mortality from malignant neoplasms in patients first starting chemotherapy in 1950 to 1952 (relative risk 0.6) and those first starting in 1953 to 1957 (relative risk 1.5). This is being studied further. This study has provided no evidence of a carcinogenic effect of isoniazid in a period of follow-up averaging nearly 20 years. The follow-up is being continued.

Adolescent↗
PubMed1976

Prenatal diagnosis of Wolman's disease.

Amniocentesis was performed in the 15th week of a pregnancy at risk for Wolman's disease. The cultured amniotic fluid cells were found to have a severe deficiency of acid esterase activity consistent with homozygosity of the fetus. The pregnancy was terminated in the 19th week and the prenatal diagnosis confirmed by enzymic and chemical evaluation of the fetal tissues.

Amniocentesis↗
PubMed1976

An investigation of the chest radiographs in a controlled trial of busulphan, cyclophosphamide, and a placebo after resection for carcinoma of the lung.

A standard series of radiographs of 588 patients allocated at random to treatment with busulphan (B patients), cyclophosphamide (C patients), or a placebo (P patients) for two years after surgery for bronchial carcinoma were viewed in three stages (following procedures which avoided bias) by an independent assessor, unaware of the allocated treatment of any patient, with a view to identifying pulmonary changes due to busulphan. Radiographic appearances consistent with busulphan lung were not reported in any of the 195 B patients (receiving a mean dosage of 464 mg of busulphan over 301 days) or of the 192 C patients but were present in one of the 201 patients receiving placebo.

Bronchial Neoplasms↗
PubMed1975

Improved recognition and quantitation technique for oncornaviruses.

A technique to recognize and quantitate oncornaviruses using perforated pointed BEEM capsules has been developed in our laboratory. Virus samples that presented problems in counting, or those which could not be evaluated at all by negative staining, could be clearly defined and counted using the thin-sectioning BEEM capsule technique. Perforation of the BEEM capsule allowed rapid infiltration of reagents into the tip of the virus pellet and made further manipulation and orientation unnecessary. The sensitivity of this technique, determined by making serial dilutions of viral concentrates, allows observation of as few as 5 times 10(5) virus particles per ml. Precision in counting by this technique varied only +/- 0.3 log in repeat aliquots of identical concentrated virus samples quantitated, making this a highly useful and reliable system.

Evaluation Studies as Topic↗
PubMed1975

New method for the removal of extraneous proteins from purified oncornaviruses.

Conventional methods (i.e. gradient centrifugation) for the purification of oncornaviruses are usually not effective in complete removal of nonviral proteins. Such contaminants often prove to be a nuisance in subsequent immunological or biochemical studies. Hyperimmune sera prepared from these viruses must be absorbed to assure specificity; cell-derived proteins can be shown to interfere with studies of virus structural proteins, nucleic acids, or viral enzymes. Herein is described a method for removal of most of these contaminants. Viruses are diluted in a high concentration of NaCl to achieve a final concentration of 15%, incubated for 30 min, sedimented, and resuspended in buffer. This procedure results in reductions of up to 48% of the protein without affecting particle count. Immunological, biochemical, and biological properties are not adversely affected. Of the proteins removed, fetal calf serum components and a ribonuclease (presumably cell-derived) were identified. This technique differs significantly from other high-salt methods in that the virus is not precipitated from suspension. It is believed that absorbed proteins are desorbed and left in solution (or suspension) as the virus is sedimented by centrifugation.

Cell Line↗