Alterations in levels of 5'-adenyl dinucleotides following DNA damage in normal human fibroblasts and fibroblasts derived from patients with xeroderma pigmentosum

Levels of 5'-adenyl dinucleotides, measured as diadenosine-5',5'-P1,P4-tetraphosphate (Ap4A), were found to accumulate in cultured human fibroblasts following treatment with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), the radiomimetic drug bleomycin, and nitroquinoline-1-oxide (NQO) or UV-irradiation in the presence of cytosine arabinofuranoside (araC). In contrast, cells derived from patients with xeroderma pigmentosum complementation group A (XP-A) did not demonstrate an increase in DNA-strand breaks following UV irradiation or NQO in the presence of araC nor an increase in Ap4A levels. Ap4A accumulation did occur in XP-A cells following treatment with MNNG. Cells derived from patients characterized as XP variants, which are incision repair-proficient, accumulated 5'-dinucleotides following bleomycin, MNNG and UV or NQO in the presence of araC. Taken together, these data suggest that Ap4A accumulates as a response to DNA-strand breaks.     

High colony-forming efficiency of primary human tumor cells cultured in the adhesive-tumor-cell culture system: improvements with medium and serum alterations

The colony-forming efficiency (CFE) of primary human tumor cells cultured in the adhesive-tumor-cell culture system (ATCCS) using Ham's F12 (F12) or Eagle's minimum essential medium, alpha modification (alphaMEM) and culture medium supplemented with either swine, equine or bovine sera were compared. AlphaMEM supplemented with equine serum provided the highest CFE of the combinations. The CFE increase due to the change from F12 to alphaMEM was approximately 5-fold, and the increase due to the change in serum from swine to equine was approximately 2-fold. Cytokeratin staining showed that this increase was not due to fibroblast growth. The high-average CFE with alphaMEM, approximately 3%, means that an inoculum of only 2 X 10(3) cells is needed to achieve formation of approximately 65 colonies in control cultures, thereby increasing the performance of this system when used in a chemosensitivity assay.     

Cyclic adenosine 3'5' monophosphate stimulates prostaglandin E production by human adherent synovial cells

Production of prostaglandin E (PGE) by rheumatoid synovium appears important to regulation of the pathologic process in rheumatoid arthritis. Cells derived from human synovium by proteolytic digestion produce large amounts of PGE which in turn can elevate synovial cell cAMP levels and inhibit cell proliferation. Data presented here indicate that cAMP can further increase production of PGE from adherent synovial cells (ASC). PGE production occurs over 12-72 hr and is not due to the ability of cAMP to inhibit cell proliferation. Exposure of cells to cAMP results in increased release of 3H arachidonic acid from precursors but not in activation of the cyclooxygenase enzyme. This phenomenon suggests the presence in adherent synovial cells of a mechanism for amplifying PGE production.     

Effects of oxygen and chloramphenicol on Frankia nitrogenase activity

The kinetics of asymbiotic nitrogenase activity in three strains of the actinomycete Frankia were studied. Decay rates for enzyme activity were determined by adding chloramphenicol to active acetylene-reducing cells and measuring the time required for all activity to cease. Synthesis rates were measured by bubbling oxygen through actively-reducing cells (which totally destroyed all activity) and then measuring the time required for activity to return to normal. Decay rates (t _1/2) for these three strains were approximately 30 to 40 min. Synthesis rates were slower and initial nitrogenase activities were recorded about 110 min (DDB 011610) or 210 min (DDB 020210 and WgCc1.17) after return to air-equilibrated cultures. Frankia strain WgCc1.17 showed a greater sensitivity to oxygen and nitrogenase activity was totally lost when cells were bubbled only with atmospheric concentrations of oxygen. The results presented here indicate that nitrogenase activity turnover time is relatively rapid, on the order of minutes rather than hours or days. However, regulation of nitrogenase activity will differ from one strain to another and asmmbiotic characterization will be useful for understanding nitrogenase regulation in the bacterial-plant symbiosis.Contribution no. 879 from the Battelle-Kettering Laboratory     

Longevity of Salmonella typhimurium in Tilapia aurea and water from pools fertilized with swine waste.

Salmonella typhimurium declined rapidly when inoculated into Tilapia aurea culture pools fertilized with fresh swine waste. Within the water column, a 95% decline of viable cells occurred during the first 6 h. Isolation of viable salmonellae was possible at 16 days post-inoculation, but not at 32 days. Similarly, salmonellae could be detected in the viscera and epithelium of T. aurea at 16 days, although not at 32 days. Salmonellae were not isolated from the fish flesh, nor was there evidence of septicemic infection.     

Grey seals, Halichoerus grypus, of the Dee Estuary and observations on a characteristic skin lesion in British seals

Grey seals on the West Hoyle Bank feed on a variety of fish and have a high incidence of dermal lesions, often associated with emaciation and nematode parasite infection. Corynebacterium phocae has been isolated from an active lesion. The significance of large numbers of seals in the Dee Estuary bearing lesions is discussed and the occurrence of seals with lesions elsewhere in British waters is reviewed. No evidence was found to associate the dermal lesions with any environmental factor and it is probable that lesions develop as a result of infection of minor wounds.     

The use of computers to study rates of lipid metabolism

Many complex problems of lipid metabolism are especially suited for multicompartmental analysis with computers. Examples are presented. The use of a model as a means of communicating one's working hypothesis and the model as it relates to experimental design are discussed. A number of principles relating to experimental design and to the interpretation and presentation of data are illustrated by 12 studies selected from the literature. These include evaluations of turnover and transport rates of liver and plasma triglycerides, triglyceride synthesis, phospholipid synthesis, and lipid oxidation to CO2. A discussion of computer-oriented vs. noncomputer-oriented techniques is included. Some of the practical problems involved in computer analysis are also considered. Among these are the choice of computer, computer applications, stepwise vs. multicompartmental analysis, validity of single-injection type experiments, avoidance of multicompartmental analysis, nonsteady state systems, and nomenclature.