PubMed Health⌕ Search

Biomedical subjects

M I Goldberg

Publications and source records attributed to M I Goldberg.

9 recordsLinked to original sources
PubMed1978

Clear cell adenocarcinoma arising in endometriosis of the rectovaginal septum.

Malignant transformation in a focus of endometriosis is uncommon (less than 1%). The ovary is by far the most common site, followed in frequency by the rectovaginal septum. A case of clear cell adenocarcinoma arising in endometriosis of the rectovaginal septum is presented and its pathogenesis discussed.

Adenocarcinoma↗
PubMed1977

A protein cofactor that stimulates the activity of DNA-dependent RNA polymerase I on double-stranded DNA.

Partially purified rat liver RNA polymerase I chromatographed on ribosomal RNA-Sepharose loses most (96%) of its activity assayed on native calf-thymus DNA templates, but loses little (8%) of its activity assayed on poly(deoxycytidylic acid) template. Polymerase I is not stimulated by polymerase II protein factor, or by bovine serum albumin. However, it is stimulated by histones, polylysine, and spermine. Addition of a protein fraction eluted by high ionic strength from the rRNA-Sepharose also restores activity on native calf-thymus DNA. Further purification yields a fraction containing two proteins of 11 000 and 12 000 molecular weight. Both proteins are distinct from histones by electrophoresis in sodium dodecyl sulfate and in acid urea. Both proteins are basic, insensitive to heat, bind to DNA, and stimulate polymerase I activity. The degree of stimulation of polymerase I is dependent upon both the enzyme/DNA and the factor/DNA ratio. The protein factors also stimulate polymerase II activity about half as effectively as polymerase I.

Animals↗
PubMed1977

Purification of rat liver and mouse ascites DNA-dependent RNA polymerase I.

Three forms of RNA polymerase were assayed in nuclei and nucleoli isolated from rat liver and from Krebs II ascites cells. Assays of rat liver nuclei in the absence of exogenous DNA showed polymerase I accounted for 72% of the total activity, polymerase II for 17%, and polymerase III for 11%. The total activity in ascites nuclei was similar but the ratios of polymerase activities were different: polymerase I, 53%; polymerase II, 41%; and polymerase III, 6%. These values may reflect differences in the transcriptional activity of the nuclei. After isolation of nucleoli, both rat liver and ascites polymerase I accounted for 85% of enzyme activity. When exogenous calf-thymus DNA was added to nucleoli, there was a greater than 50% increase in activity suggesting that less than one-half of the polymerase I present was bound to endogenous template. Polymerase I was solubilized from either rat liver or ascites nucleoli by sonication at high ionic strength and subsequently purified by ion filtration, phosphocellulose, sucrose gradient centrifugation, and DNA-cellulose chromatography. The essentially homogenous ascites enzyme had a specific activity of 86 units/mg when assayed with native calf-thymus DNA and of 876 units/mg when assayed with poly(deoxycytidylic acid). Electrophoresis of the enzyme in sodium dodecyl sulfate indicated the presence of six subunits with molecular weights of 205 000, 125 000, 51 000, 44 000, 26 000 and 16 000. After the same purification procedure, the rat liver enzyme had a similar specific activity (98 units/mg) on native calf thymus and 362 units/mg on poly(deoxycytidylic acid).

Animals↗