Cell cycle effects of antifolate antimetabolites: implications for cytotoxicity and cytostasis

 Purpose: Cell cycle-related events in CCRF-CEM lymphocytic leukemia cells were examined subsequent to inhibition of thymidylate synthase (TS) or GAR formyltransferase (GARFT) and prior to cell death or stasis. Methods: Cell populations were treated with the GARFT inhibitors 6R-5,10-dideazatetrahydrofolate (lometrexol) or LY309887, the TS inhibitor ZD1694, or the multitargeted antifolate LY231514. DNA content, nucleoside precursor incorporation and proliferating cell nuclear antigen (PCNA) expression as functions of drug treatment were assessed by multiparameter flow cytometry. Cellular respiration was measured by MTT analysis and apoptosis was detected by extraction of DNA fragments. Results: Cell populations treated for up to 96 h with lometrexol or LY309887 did not replicate and maintained a cell cycle distribution with distinct G₁, S and G₂/M regions. The number of S phase cells in treated populations was slightly elevated relative to control as measured by DNA content and PCNA. However, these cells were unable to incorporate 5-bromodeoxyuridine (BrdU). Throughout treatment, cells incubated with GARFT inhibitors maintained intact membranes and respired at a level comparable to untreated cells. In contrast, ZD1694 as well as LY231514, induced synchronization of the treatment population at the G₁/S interface within 12 h of drug addition. This was followed by synchronous entry of the population into S phase. After 24 h of treatment, more than 90% of the cells were capable of incorporating BrdU and stained positive for PCNA. DNA fragmentation occurred in cells treated with ZD1694 or LY231514 but not in those treated with GARFT inhibitors. In addition, the viable cells remaining after 24–48 h of treatment with ZD1694 or LY231514 were respiring at twice the level of untreated cells. Conclusion: These results demonstrate that the distinct endpoints of GARFT and TS inhibition are preceded by distinct cell cycle and metabolic alterations. Received: 1 April 1996 / Accepted: 5 September 1996     

Assay Formats: Recommendation for Best Practices and Harmonization from the Global Bioanalysis Consortium Harmonization Team

As part of the GBC (Global Bioanalysis Consortium), the L3 assay format team has focused on reviewing common platforms used to support ligand binding assays in the detection of biotherapeutics. The following review is an overview of discussions and presentations from around the globe with a group of experts from different companies to allow an international harmonization of common practices and suggestions for different platforms. Some of the major platforms include Gyrolab, Erenna, RIA, AlphaLISA, Delfia, Immuno-PCR, Luminex, BIAcore, and ELISAs. The review is meant to support bioanalysts in taking decisions between different platforms depending on the needs of the analyte with a number of recommendations to help integration of platforms into a GLP environment.     

Patient Blood Management: Use of Topical Hemostatic and Sealant Agents

Patient blood management is the scientific use of safe, effective medical and surgical techniques designed to conserve blood, prevent anemia, decrease bleeding, and optimize coagulation in an effort to improve patient outcomes. Perioperative and primary care nurses play a vital role in promoting and making the best use of patient blood management and can play a key role in implementing effective strategies that decrease or eliminate patient exposure to allogeneic blood. The fast and effective minimization of intraoperative bleeding is integral in an effective blood management program. Topical hemostatic and sealant agents can be used to improve blood conservation, reduce overall procedure time, and contribute to faster patient recovery based on specific clinical situations. The proper selection of hemostatic agents can greatly influence the patient’s clinical outcomes.     

Housing Dependence and Intimate Relationships in the Lives of Low-Income Puerto Rican Mothers

Using longitudinal ethnographic data from the Three-City Study, we examined the relationship between sixteen low-income Puerto Rican mothers' housing dependencies and their intimate partner relations. We traced mothers' dependent housing arrangements and entrée to marital or cohabiting relationships from their teens through their procurement of independent housing while entering and maintaining intimate partner unions as adults. Findings indicated that various trigger factors led women out of their natal homes and into expedited cohabitation with romantic partners which frequently resulted in unstable unions in which mothers had little power and autonomy. As mothers became eligible for housing subsidies they obtained housing independent from their male partners, potentially increasing the propensity for greater relationship power. Housing independence, however, was not without problems. Spillover effects, such as shadowing partners, threatened housing stability and mothers' independence. The relevance of these findings for future research is discussed.     

Acceptability of a Dapivirine/Placebo Gel Administered Rectally to HIV-1 Seronegative Adults (MTN-026)

AIDS and Behavior - This study describes the acceptability of a rectal microbicide gel formulation using dapivirine (DPV) among men and women from two countries (United States and Thailand)...