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Biomedical subjects

R L Adams

Publications and source records attributed to R L Adams.

At least 127 records · Page 7Linked to original sources
PubMed1979

Prophylactic antibiotics in gynecologic surgery.

A 2-year prospective double-blind study of prophylactic antibiotics in 317 patients undergoing elective total abdominal or vaginal hysterectomy was conducted. Patients randomly received placebo, penicillin, or cefazolin 30 minutes prior to surgery and at 6-hour intervals thereafter for 48 hours. Rigid criteria for postoperative morbidity were established. Vaginal hysterectomy patients given either penicillin or cefazolin prophylaxis had fewer postoperative infections (P less than 0.01) compared to those given placebo. A similar trend was noted among women undergoing abdominal hysterectomy; however, this trend was not statistically significant (P greater than 0.05). Despite continuous surveillance, no change in nosocomial flora or antibiotic sensitivity of bacterial isolates was noted. Adverse drug effects and antibiotic-resistant secondary infections were encountered with similar frequency in all treatment groups.

Bacterial Infections↗
PubMed1978

Genome modification in two lines of baby hamster kidney fibroblasts (BHK-21).

Reasons for the different levels of 5-methyl cytosine encountered in the DNA of two baby hamsters kidney fibroblast lines, BHK-21/C13 and BHK-21/PyY have been investigated. From enzymic studies it does not seem that there are large numbers of potentially methylatable cytosine residues in the C13 line DNA which contains a lower level of 5-methyl cytosine. Rather it is possible that the difference may be due to the reiteration in the PyY strain of certain sequences containing 5-methyl cytosine which simply occur less frequently in the other line.

Cell Line↗
PubMed1978

Involvement of deoxyribonucleic acid polymerase beta in nuclear deoxyribonucleic acid synthesis.

The effects on DNA synthesis in vitro in mouse L929-cell nuclei of differential extraction of DNA polymerases alpha and beta were studied. Removal of all measurable DNA polymerase alpha and 20% of DNA polymerase beta leads to a 40% fall in the replicative DNA synthesis. Removal of 70% of DNA polymerase beta inhibits replicative synthesis by 80%. In all cases the nuclear DNA synthesis is sensitive to N-ethylmaleimide and aCTP (arabinosylcytosine triphosphate), though less so than DNA polymerase alpha. Addition of deoxyribonuclease I to the nuclear incubation leads to synthesis of high-molecular-weight DNA in a repair reaction. This occurs equally in nuclei from non-growing or S-phase cells. The former nuclei lack DNA polymerase alpha and the reaction reflects the sensitivity of DNA polymerase beta to inhibiton by N-ethylmaleimide and aCTP.

Animals↗
PubMed1978

Endometrial and vaginal cuff bacteria recovered at elective hysterectomy during a trial of antibiotic prophylaxis.

The utility of culturing the cut edge of the vaginal cuff and endometrium of the uterine specimens of patients undergoing elective hysterectomy and receiving antibiotic prophylaxis has been critically examined. Subjects for this study represent a randomized subpopulation of patients participating in a larger controlled, prospective, double-blind study of antibiotic prophylaxis which has been conducted at Yale-New Haven Hospital during the past five years. On the basis of the organisms recovered, speculation is raised concerning the existence of an endometrial flora and the mechanisms of postoperative vaginal cuff infection in patients treated and not treated with antibiotic prophylaxis at the time of hysterectomy.

Aerobiosis↗
PubMed1978

Anaerobic bacterial recovery from two transport systems in a study of gynecologic flora.

Several systems for transporting specimens to the laboratory to test for the presence of anaerobic bacteria are available to clinicians. To date, these have not been systematically compared, especially regarding cost-effectiveness. This study compares recovery of anaerobic organisms from genital cultures of gynecological patients under bacteriologic study for research purposes. Two transport systems for delivery of specimens to the laboratory were studied: 1) the commercially available Anaswab system, and 2) a modified Stuart medium (transport charcoal medium) with 0.2% added agar in addition to 0.2% added charcoal. Our data shows no significant difference in kinds of anaerobic organisms recovered using either system when specimens are transported to the laboratory within 24 hours. Although the sites of culturing compared in this study are not directly applicable to the problem of pelvic infection, nevertheless the potential for lowering cost by selecting alternative systems for anaerobic recovery should prompt further comparisons in clinical settings. Some practical suggestions are made for applying agar-modified transport charcoal medium, the less expensive alternative, to clinical situations.

Aerobiosis↗
PubMed1977

The sequence specificity of a mammalian DNA methylase.

The sequence specificity of an extensively purified DNA methylase preparation from Krebs II mouse ascites cells has been examined. The enzyme appears to be highly sequence dependent. Moreover the sequence distribution of cytosine residues that are methylated, bears a very close resemblance to the sequence distribution of 5'-methyl cytosine found in vivo in a wide range of vertebrate cells and is consistent with methylation of cytosines in the sequence R-Yn-C-R.

Animals↗
PubMed1977

Methylation of nucleosomal and nuclease sensitive DNA.

The proportion of cytosines methylated in the DNA of nucleosome oligomers and of core particles appears indistinguishable from that of total nuclear DNA from CHO cells. However the DNA in nucleoprotein which is initially released from nuclei by treatment with very low levels of micrococcal nuclease and the first 10% of material rendered acid soluble by treatment of nuclei with DNase I are enriched 2 fold in their content of 5 methylcytosine. (Cessation of hydrolysis by nuclease occurs concomitantly with precipitation of nucleosomal core particles).

Cell Line↗
PubMed1976

DNA methylase: purification from ascites cells and the effect of various DNA substrates on its activity.

DNA methylase has been purified 405-fold from Krebs II ascites cells. The purified enzyme is homogeneous on SDS-poly acrylamide gel electrophoresis (molecular weight about 80,000) and the only product of the reaction with DNA is 5-methyl cytosine. Both native and denatured DNA are methylated by the enzyme; with calf thymus DNA the double stranded form is the better substrate but the enzyme preferentially methylates single stranded E.coli DNA even in "native" preparations. Our results do not support a mechanism whereby the enzyme methylates DNA by binding irreversibly and "walking" along it. By measuring maximum levels of methylation of DNAs from different sources we have estimated the proportion of unmethylated sites present in them. Homologous ascites DNA can be methylated, but only to about 5% of the level of the best substrate, undermethylated mouse L929 cell DNA. DNA isolated from growing cells or tissues is a better substrate than DNA from normal liver or pancreas, or from stationary cells.

Animals↗