Filling the Geriatric Gap: Is the Health System Prepared for an Aging Population?

This issue brief explores the field of geriatrics, the ways practitioners meet the health care needs of the elderly, training gaps, and the impact of Medicare payment policies on the delivery of health care to older Americans

Properties and inhibition of thymidylate synthetase in Drosophila melanogaster

A quantitative comparison of the incorporation of methyl-3H-thymidine and 6-3H-deoxyuridine into the DNA of Drosophila melanogaster in the presence and in the absence of 5-fluorouracil indicated that 5-fluorouracil inhibits the reaction converting dUMP to dTMP catalysed by thymidylate synthetase (methylenetetrahydrofolate:dUrd-5'-P C-methyltransferase, E.C. 2.1.1.b). The enzyme exhibits maximal activity at pH 7[middle dot]5 to 8[middle dot]0 and is protected from heat inactivation by deoxyuridine monophosphate. The addition of thiol compounds to the homogenization buffer results in the enhancement of synthetase activity. The Km values for deoxyuridine monophosphate and 5,10-methylenetetrahydrofolate are 6[middle dot]8 x 10-6 M and 8[middle dot]3 x 10-5 M, respectively. Fluorodeoxyuridine monophosphate, trifluoromethyldeoxyuridine monophosphate, and methotrexate are inhibitors of the enzyme. 5-Bromodeoxyuridine and 5-iododeoxyuridine have no inhibitory effect. The results support the contention that, under conditions which induce morphological lesions in Drosophila, fluorinated pyrimidines and methotrexate inhibit the de novo synthesis of thymidylate whereas thymidine analogues function in some other manner.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22328/1/0000773.pd

In Situ Activity of Enzymes on Polyacrylamide Gels of a Deoxyribonucleic Acid-Membrane Fraction Extracted from Pneumococci

A deoxyribonucleic acid (DNA)-membrane fraction extracted from Diplococcus pneumoniae was subjected to polyacrylamide gel electrophoresis after treatment with 0.16% sodium dodecyl sulfate. At least two DNA polymerase activities were detected by in situ assays with appropriate substrates, templates, and inhibitors, including a co-polymer of deoxyadenylic and thymidylic acid and N -ethylmaleimide. This activity coincided with a fraction in the gel containing 7.5, 9.4, and 24%, respectively of the DNA, phospholipid, and protein present in the DNA-membrane fraction before electrophoresis and sodium dodecyl sulfate treatment. Assays with minced gels showed that several nuclease activities, deoxyribonucleotide kinase activity, and DNA ligase activity also coincided with this fraction. However, ribonucleoside diphosphate reductase activity did not. These results demonstrate that a complex of enzymes involved in DNA replication is firmly bound to the DNA-membrane fraction in pneumococci. </jats:p