A rapid survival assay to measure drug-induced cytotoxicity and cell cycle effects

We describe a rapid method to accurately measure the cytotoxicity of mammalian cells upon exposure to various drugs. Using this assay, we obtain survival data in a fraction of the time required to perform the traditional clonogenic survival assay, considered the gold standard. The dynamic range of the assay allows sensitivity measurements on a multi-log scale allowing better resolution of comparative sensitivities. Moreover, the results obtained contain additional information on cell cycle effects of the drug treatment. Cell survival is obtained from a quantitative comparison of proliferation between drug-treated and untreated cells. During the assay, cells are treated with a drug and, following a recovery period, allowed to proliferate in the presence of bromodeoxyuridine (BrdU). Cells that synthesize DNA in the presence of BrdU exhibit quenched Hoechst fluorescence, easily detected by flow cytometry; quenching is used to determine relative proliferation in treated vs. untreated cells. Finally, this assay can be used in high-throughput format to simultaneously screen multiple cell lines and drugs for accurate measurements of cell survival and cell cycle effects after drug treatment.National Institutes of Health (U.S.) (U54-CA112967)National Institutes of Health (U.S.) (R01-CA055042)National Institutes of Health (U.S.) (P30-ES002109)National Institutes of Health (U.S.) (P30-CA014051)Massachusetts Institute of Technology (Merck Fellowship

Ethical issues in the practice of medicine

This article does not have an abstract

Differential control of CXCR4 and CD4 downregulation by HIV-1 Gag

<p>Abstract</p> <p>Background</p> <p>The ESCRT (endosomal sorting complex required for transport) machinery functions to sort cellular receptors into the lumen of the multivesicular body (MVB) prior to lysosomal degradation. ESCRT components can also be recruited by enveloped viruses to sites of viral assembly where they have been proposed to mediate viral egress. For example, HIV-1 budding is dependent on Gag-mediated recruitment of the cellular ESCRTs-I, -III, AIP1/Alix and Vps4 proteins. Viral recruitment of ESCRT proteins could therefore impact on host cell processes such as receptor downregulation.</p> <p>Results</p> <p>Here we show that downregulation of the HIV-1 co-receptor, CXCR4, by its ligand SDF-1, is ESCRT-I dependent. Expression of HIV-1 Gag attenuated downregulation of CXCR4, resulting in accumulation of undegraded receptors within intracellular compartments. The effect of Gag was dependent on an ESCRT-I interacting motif within the C-terminal p6 region of Gag. In contrast, PMA-induced downregulation of the HIV-1 receptor CD4 was independent of ESCRT-I and Vps4; HIV-1 Gag had no effect on this process.</p> <p>Conclusion</p> <p>These results establish that the HIV-1 receptor, CD4, and co-receptor, CXCR4 are differentially regulated by ESCRT proteins. HIV-1 Gag selectively modulates protein sorting at the MVB, interfering with ESCRT-I dependent but not ESCRT-I independent processes.</p

TO DETERMINE THE EFFICACY OF 0.12%CHLORHEXIDINE MOUTHRINSES IN REDUCING VIABLE BACTERIAL COUNT IN DENTAL AEROSOLS WHEN USED AS A PREPROCEDURAL RINSE DURING THE PANDEMIC ERA -A PROSPECTIVE CLINICAL PILOT STUDY

Background: In dentistry , aerosols being the major concerns that brings about transmission of infectious agents and harmful to patients and dentists . Thus the vigilant use of barriers, appropriate immunisation procedures all could safeguard the dental fraternity from the ill effects of aerosols. Aim: To Determine The Efficacy of 0.12% chlorhexidine mouth rinse as preprocedural rinse in reduction of bacterial aerosol contamination generated during Ultrasonic scaling in a closed operatory and compared with1% Povidone iodine rinse and without preprocedural rinse. Materials and Methods: Thirty patients were selected from Department of Periodontics, Sree Balaji Dental College and Hospital, Chennai. The subjects were grouped into A -10 patients each receive 1% POVIDINE IODINE mouth rinse and Group B of 10 patients received 0.12% CHLORHEXIDINE mouth rinse respectively as a pre-procedural rinse. Group C 10 patients without preprocedural rinse. The aerosols produced by the ultrasonic unit were collected on blood agar plates placed at 8 standard positions around the dental chair. These plates were sent for microbiologic analysis for the assessment of bacterial Colony Forming Units (CFUs) was evaluated and statistically analysed. Results: The significance of the study was both the mouthrinses reduced the bacterial colony forming units (CFUs) in aerosol samples. 0.12%Chlorhexidine mouth rinses were found to be superior to 1%Povidone iodine in reducing aerosolized bacteria when used preprocedurally. Conclusion: The study highlights the efficacy of preprocedural mouth rinses , during any dental treatment which generates aerosols, reduces the risk of cross- contamination within the dental operatory

Pushing for answers: is myosin V directly involved in moving mitochondria?

In budding yeast, the actin-based class V myosin motors, Myo2 and Myo4, transport virtually all organelles from mother to bud during cell division. Until recently, it appeared that mitochondria may be an exception, with studies showing that the Arp2/3 complex is required for their movement. However, several recent studies have proposed that Myo2 has a direct involvement in mitochondria inheritance. In this issue, Altmann et al. (Altmann, K., M. Frank, D. Neumann, S. Jakobs, and B. Westermann. 2008. J. Cell Biol. 181:119–130) provide the strongest support yet that Myo2 and its associated light chain Mlc1 function directly and significantly in both mitochondria–actin interactions and in the movement of mitochondria from mother to bud. The conflicting functions of Arp 2/3 and Myo2 may be reconciled by the existence of multiple pathways involved in mitochondrial transport

Cardiac surgery - an offspring of experiment

Cardiac surgery is like a drama which is still unfolding. Old scenes of conflicting ideas, procedures and technologies give place to the new in quick succession leaving nothing unchanged on the stage

Heparin bonding: then and now

This article does not have an abstract

Blood compatibility of materials

This article does not have an abstract

Geography and the heart

Geography brings to mind the physical formations of the earth, mountains and rivers plants and deserts, oceans and bays. Presently climate, winds and currents enter the mental picture. In contrast, the heart ticks on within the inner sancctum of the body, unseen and unheard. The connection between the world without and the heart within is scarcely apparent. Does the heart sense geopraphical events? Does it leap up before the rainbow in the sky?

E-Glass Fiber Reinforced Composites in Dental Applications

Fiber reinforced composites (FRCs) are more and more widely applied in dentistry to substitute for metallic restorations: periodontal splints, fixed partial dentures, endodontic posts, orthodontic appliances, and some other indirect restorations. In general in FRCs, the fiber reinforcement provides the composite structure with better biomechanical performance due to their superior properties in tension and flexure. Nowadays, the E-glass fiber is most frequently used because of its chemical resistance and relatively low cost. Growing interest is being paid to enhance its clinical performance. Moreover, various techniques are utilized to reinforce the adhesion between the fiber and the matrix. Oral conditions set special requirements and challenges for the clinical applications of FRCs. The biomechanical properties of dental materials are of high importance in dentistry, and given this, there is on-going scientific interest to develop E-glass fiber reinforced composite systems. FRCs are generally biocompatible and their toxicity is not a concern. © 2011 The Author(s).published_or_final_versionSpringer Open Choice, 21 Feb 201