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S K Arya

Publications and source records attributed to S K Arya.

13 recordsLinked to original sources
PubMed1979

Effect of bromodeoxyuridine and interferon on cellular and viral functions in human prostatic cells.

Some of the human prostatic cells in culture apparently produce oncornavirus-like particles. Bromodeoxyuridine does not enhance the production of these particles. On the contrary, this drug depresses such production. This depression is likely to be due to the cytotoxic effects of bromodeoxyuridine for these cells. These results can be interpreted to suggest that the human prostatic cells used in this study do not contain endogenous oncornavirus genetic information that is inducible. Purified human interferon inhibits the production of oncornavirus-like particles by these prostatic cells. It is also inhibits the rate of cellular DNA synthesis in these cells. These results are consistent with the notion that the inhibitory effects of interferon are mediated through its effect on cellular biosynthetic machinery.

Adenocarcinoma↗
PubMed1979

Oncornavirus-like particles released by human prostatic explant cultures.

Explant cultures from several human prostatic tissues have been examined for oncornavirus production. Some of these explants, epithelial in morphology, appear to release oncornavirus-like particles. The extracellular particulate material, obtained from the culture medium of these explants display the following characteristics: (1) It contains particles that band at a density of 1.1-1.2 g/cm3 in a sucrose density gradient. (2) The particles contain RNA-directed DNA polymerase. This polymerase utilizes poly(Cm) as a template and shows preference for poly(A) over poly(dA) and manganese over magnesium. (3) Apparently, the particles also contain RNA that directs the synthesis of DNA in vitro. The DNA thus synthesized is associated with RNA, some of it with high molecular weight RNA. Such particles are not observed in the culture medium from monolayers of monkey kidney CV-1 cells. We have found that explant cultures from 5 out of 15 tissue specimens with prostatic hyperplasia and 3 out of 4 with prostatic adenocarcinoma release particles that band at a density of 1.1-1.2 g/cm3 and contain RNA-directed DNA polymerase. Explant cultures of two normal prostates examined did not release such particles.

Adenocarcinoma↗
PubMed1978

Reverse transcriptase activity in extracts of human prostatic tissues.

The extracts of human prostatic tissue specimens contain oncornavirus-like reverse transcriptase activity. This activity was isolated by banding the tissue extract in an equilibrium sucrose density gradient followed by phosphocellulose chromatography of the lysate of the material banding at a density of 1.14--1.20 g/cc. It was characterised by its utilisation of poly (Cm) as a template and its inhibition by selective inhibitors of viral reverse transcriptase. Human prostatic tissues of three histo-pathologic types--normal, hyperplastic and adenocarcinoma--were examined. One out of four normal, five out of six hyperplastic, and two out of two adenocarcinoma specimens displayed virus-like reverse transcriptase activity.

Adenocarcinoma↗
PubMed1977

A status report: human prostatic carcinoma, with emphasis on potential for viral etiology.

Several parameters of the biology of cancer of the prostate have been reviewed with a continuing assessment of the possible etiologic role of virus. These aspects include epidemiology, clinical studies, morphology, pathology, enzymology, immunology, endocrinology, model animal studies, in vitro systems, and viral investigations. From available literature it is concluded that, to date, the association with several urogenital tissues of herpes-type viruses has been best documented. It is suggested that a fundamental barrier to more sophisticated virologic and biologic studies is the lack of long term cell cultures of normal and pathologic prostate epithelium from males of all ages.

Acid Phosphatase↗
PubMed1976

RNA tumor virus-like activities in human solid tissues: endogenous RNA:DNA polymerase activities in the prostate.

Several human prostatic tissues have been examined for possible particles and associated DNA polymerizing activity generally associated with the C-type RNA tumor virus family. Partially purified tissue extracts, when centrifuged to equilibrium in sucrose gradients, yield fractions which contain actinomycin D resistant, endogenous DNA polymerase activity; this activity bands at a density of 1.15-1.18 gm/cm3. Further analysis of the endogenous products by sucrose gradient sedimentation suggested the presence of high molecular weight RNA:DNA hybrids generally felt to be indicative of a faithful copy of a lengthy stretch of viral specific RNA. However, most of the DNA products synthesized in these endogenous reactions sedimented in much lower molecular weight regions of these sucrose gradients. Clearly, the relative distributions of "high" and "low" molecular weight products could critically depend on the nuclease content of the subcellular fraction under study, and the prostate may be relatively enriched in nucleases. Further, oligo (dT) stimulated the endogenous DNA polymerase activity contained in these extracts, and omission of one of the DNA precursor nucleotides depressed it. Thus, it seems unlikely that terminal transferase activity, rather than genuine DNA polymerization, was being measured primarily. Because of the spectrum of molecular weight classes formed by these DNA:RNA hybrids, as well as their apparent presence in normal prostatic tissue, we find it difficult to ascribe their presence with certainty either to the presence of typical C-type RNA viruses or to the exclusive behavior of the neoplastic prostatic tissue. Thus, our studies lend support to the growing evidence for functions similar to those of C-type RNA viruses being relatively widespread in human tissues without the apparent necessity for a possible etiologic role in neoplastic production (Strand and August, 1974; Sherr et al., 1974). At the same time, our current studies emphasize the need for caution in drawing conclusions from results utilizing probes generally felt quite useful in scoring for presence of virus in lower animals at least in the human prostate.

Centrifugation, Density Gradient↗
PubMed1975

Interaction of steroids with nucleic acids.

17beta-Estradiol and testosterone bind to both native and denatured DNA, and to RNA and poly(A)-poly(U). Binding affinity depends on the conformation of nucleic acid. Lowering the electrolyte concentration and raising the temperature increase the binding of 17beta-estradiol to native DNA and decrease that to denatured DNA. In 0.01 M NaCl and at 37 degrees, more 17beta-estradiol is bound to native DNA than to denatured DNA. Higher binding of steroid to denatured DNA relative to native DNA at low temperature and high ionic strength is related to larger fraction of binding sites per unit nucleotide in denatured DNA. In addition to 17beta-estradiol and testosterone, 17alpha-estradiol, 17beta-estradiol-3-methyl ether and 19-nortestosterone also stabilize the structure of nucleic acids and poly(A)-poly(U) against thermal denaturation. The 17beta-estradiol induced elevation of the T-m of DNA is diminished by methanol or high NaCl concentration. These results indicate the involvement of hydrogen bonding and hydrophobic interactions between steroids and nucleic acids. The results of binding isotherms and optical studies suggest a conformational dependence of the binding of steroids to nucleic acids.

Animals↗
PubMedDate not supplied

The search for "virogene" in human prostatic tissues: prostatic DNA polymerases.

The "virogene-oncogene" hypothesis of Huebner and Todaro and the "provirus" hypothesis of Temin implicate RNA tumor viruses in the neoplastic transformation of mammalian cells. These hypotheses have been substantiated in several animal systems including primates and, presumably, in man. Because the detection in a tissue of one or two activities allegedly related to RNA tumor virus may not be conclusive evidence for viral presence, we have developed a scheme of coordinated morphologic, biologic, and biochemical investigations of human prostatic tissues. We report here the more recent progress we have made in one of the segments of our scheme of investigations. Two, possibly three, DNA polymerase activities from human prostatic tissue have been isolated and partially purified by DEAE-cellulose and phosphocellulose chromatography. These activities have been partially characterized. Based on template preferences and non-inhibition by selective inhibitors of reverse transcriptase, neither of the major polymerase activities appears to be the reverse transcriptase-type activity.

Adenine↗
PubMedDate not supplied

RNA tumor virus-like activities in human prostate: possible novel pharmacologic approaches.

The cytoplasmic extracts of human prostatic tissues yield two classes of "particles" when centrifuged to equilibrium in a sucrose density gradient, one class banding at a density of 1.15-1.18 g/cm3 ("high density particles") and another at a density of 1.07-1.14 g/cm3 ("low density particles"). Both bands display endogenous DNA polymerase activity which is largely resistant to actinomycin D inhibition. The endogenous DNA products synthesized by high density particles give some indication of high molecular weight RNA:DNA complexes. The tissue extracts from normal, hyperplastic, and neoplastic prostate behave similarly in these assays. In addition, explant cultures of hyperplastic and neoplastic prostate either release, or can be induced to release, particles by treatment with bromodeoxyuridine. These particles band at a density of 1.15-1.18 g/cm3 in a sucrose density gradient and possess RNA and associated DNA polymerase activity which utilizes poly(A):oligo(dT). Our results suggest that human prostatic tissues may contain functions analogous in some ways to those of known RNA tumor viruses of other species.

Bromodeoxyuridine↗