He initiation of ART. Given the global scaling-up of AZT use, additional studies from different settings and populations are needed to provide additional information on how the risk of AZTrelated anemia varies according to previous ART use and body weight [3]. More generally, it remains to be assessed whether, while keeping similar efficacy, lower AZT dosing would be associated with increased tolerance and a reduced incidence of other side-effects like early intolerance (headache and nausea) and long-term mitochondrial toxicity. Nevertheless, given the overall 
high rate of anemia associated with AZT, 22948146 even following initialTable 3. Risk factors associated with AZT-induced anemia requiring AZT discontinuation.Event/N ( )Univariate analysis HRMultivariate analysisp valueaHRp valueBody weight at AZT start 60 kg 50?9 kg 40?9 kg ,40 kg Hemoglobin at AZT start .12 g/dL 10?2 g/dL ,10 g/dL Age (per 10 year increase) Gender Male Female Time on D4T 1 year ,1 year 91/924 (9.9) 47/256 (18.4) 1 1.8 (1.3?.6) 0.001 1 1.4 (1.0?.1) 0.057 56/466 (12.0) 82/714 (11.5) 1 1.0 (0.7?.4) 0.877 1 0.7 (0.5?.1) 0.155 66/827 (8.0) 53/312 (17.0) 19/41 (46.4) 139/1180 (11.8) 1 2.2 (1.6?.2) 7.0 (4.0?1.1) 1.3 (1.1?.6) ,0.001 ,0.001 0.002 1 2.2 (1.5?.3) 6.5 (3.7?1.4) 1.2 (1.0?.4) ,0.001 ,0.001 0.042 23/225 (10.2) 51/457 (11.2) 51/427 (11.9) 13/71 (18.3) 1 1.1 (0.6?.7) 1.1 (0.7?.9) 1.7 (0.8?.3) 0.814 0.953 0.152 1 1.0 (0.6?.7) 1.0 (0.6?.8) 1.1 (0.5?.4) 0.982 0.916 0.HR: Hazard ratio, aHR: adjusted hazard ratio, AZT: zidovudine, D4T: 1662274 stavudine Additional co-variates included in univariate analysis but not retained in multivariate analysis are described in the Methods. doi:10.1371/journal.pone.0060206.tAnemia after AZT Substitution for D4TTable 4. Association of body weight with anemia according to prior duration of D4T use.AZT start.1 year after D4T initiation aHR CASIN custom synthesis Outcome: AZT discontinuation due to anemia Body weight .60 kg 50?0 kg 40?0 kg ,40 kg 1 0.8 (0.5?.5) 0.8 (0.4?.6) 0.7 (0.2?.9) 0.522 P-valueAZT start#1 year after D4T initiation aHR MedChemExpress Solvent Yellow 14 P-value1 1.8 (0.6?.4) 1.9 (0.6?.6) 2.6 (0.7?.9)0.Outcome: Anemia grade 2 or more (hemoglobin below 8 g/dL) Body weight .60 kg 50?0 kg 40?0 kg ,40 kg 1 0.4 (0.2?.9) 0.7 (0.3?.4) 0.5 (0.1?.0) 0.437 1 4.4 (0.6?5.0) 4.4 (0.5?5.1) 9.5 (1.1?0.7) 0.aHR: adjusted hazard ratio, AZT: zidovudine, D4T: stavudine doi:10.1371/journal.pone.0060206.ttreatment with D4T, our findings also argue for increased use of tenofovir in first line ART regimens.Medicine (ITM) for their support and for their contribution to the data collection for this study.AcknowledgmentsWe thank all patients, the hospital management team and staff at the Sihanouk Hospital Center of HOPE (SHCH) and Institute of TropicalAuthor ContributionsConceived and designed the experiments: TP JvG. Performed the experiments: TP JvG CV SS. Analyzed the data: TP JvG. Wrote the paper: TP CV SS ST LL JvG.
Excitation-contraction (E-C) coupling in the adult mammalian heart is governed by the Ca2+-induced Ca2+ release (CICR) mechanism. The process involves entry of Ca2 through L-type Ca2+ channel that activates the ryanodine receptors (RyRs)mediated Ca2+ release from sarcoplasmic reticulum (SR) and resulting in intracellular Ca2+ transients [1]. Ca2+ sparks, a local and transient Ca2+ release originating from a single RyR or a cluster of RyRs, constitute the elementary events of cardiac E-C coupling [2]. Whole cell Ca2+ transients are believed to represent the recruitment and summation of many Ca2.He initiation of ART. Given the global scaling-up of AZT use, additional studies from different settings and populations are needed to provide additional information on how the risk of AZTrelated anemia varies according to previous ART use and body weight [3]. More generally, it remains to be assessed whether, while keeping similar efficacy, lower AZT dosing would be associated with increased tolerance and a reduced incidence of other side-effects like early intolerance (headache and nausea) and long-term mitochondrial toxicity. Nevertheless, given the overall high rate of anemia associated with AZT, 22948146 even following initialTable 3. Risk factors associated with AZT-induced anemia requiring AZT discontinuation.Event/N ( )Univariate analysis HRMultivariate analysisp valueaHRp valueBody weight at AZT start 60 kg 50?9 kg 40?9 kg ,40 kg Hemoglobin at AZT start .12 g/dL 10?2 g/dL ,10 g/dL Age (per 10 year increase) Gender Male Female Time on D4T 1 year ,1 year 91/924 (9.9) 47/256 (18.4) 1 1.8 (1.3?.6) 0.001 1 1.4 (1.0?.1) 0.057 56/466 (12.0) 82/714 (11.5) 1 1.0 (0.7?.4) 0.877 1 0.7 (0.5?.1) 0.155 66/827 (8.0) 53/312 (17.0) 19/41 (46.4) 139/1180 (11.8) 1 2.2 (1.6?.2) 7.0 (4.0?1.1) 1.3 (1.1?.6) ,0.001 ,0.001 0.002 1 2.2 (1.5?.3) 6.5 (3.7?1.4) 1.2 (1.0?.4) ,0.001 ,0.001 0.042 23/225 (10.2) 51/457 (11.2) 51/427 (11.9) 13/71 (18.3) 1 1.1 (0.6?.7) 1.1 (0.7?.9) 1.7 (0.8?.3) 0.814 0.953 0.152 1 1.0 (0.6?.7) 1.0 (0.6?.8) 1.1 (0.5?.4) 0.982 0.916 0.HR: Hazard ratio, aHR: adjusted hazard ratio, AZT: zidovudine, D4T: 1662274 stavudine Additional co-variates included in univariate analysis but not retained in multivariate analysis are described in the Methods. doi:10.1371/journal.pone.0060206.tAnemia after AZT Substitution for D4TTable 4. Association of body weight with anemia according to prior duration of D4T use.AZT start.1 year after D4T initiation aHR Outcome: AZT discontinuation due to anemia Body weight .60 kg 50?0 kg 40?0 kg ,40 kg 1 0.8 (0.5?.5) 0.8 (0.4?.6) 0.7 (0.2?.9) 0.522 P-valueAZT start#1 year after D4T initiation aHR P-value1 1.8 (0.6?.4) 1.9 (0.6?.6) 2.6 (0.7?.9)0.Outcome: Anemia grade 2 or more (hemoglobin below 8 g/dL) Body weight .60 kg 50?0 kg 40?0 kg ,40 kg 1 0.4 (0.2?.9) 0.7 (0.3?.4) 0.5 (0.1?.0) 0.437 1 4.4 (0.6?5.0) 4.4 (0.5?5.1) 9.5 (1.1?0.7) 0.aHR: adjusted hazard ratio, AZT: zidovudine, D4T: stavudine doi:10.1371/journal.pone.0060206.ttreatment with D4T, our findings also argue for increased use of tenofovir in first line ART regimens.Medicine (ITM) for their support and for their contribution to the data collection for this study.AcknowledgmentsWe thank all patients, the hospital management team and staff at the Sihanouk Hospital Center of HOPE (SHCH) and Institute of TropicalAuthor ContributionsConceived and designed the experiments: TP JvG. Performed the experiments: TP JvG CV SS. Analyzed the data: TP JvG. Wrote the paper: TP CV SS ST LL JvG.
Excitation-contraction (E-C) coupling in the adult mammalian heart is governed by the Ca2+-induced Ca2+ release (CICR) mechanism. The process involves entry of Ca2 through L-type Ca2+ channel that activates the ryanodine receptors (RyRs)mediated Ca2+ release from sarcoplasmic reticulum (SR) and resulting in intracellular Ca2+ transients [1]. Ca2+ sparks, a local 
and transient Ca2+ release originating from a single RyR or a cluster of RyRs, constitute the elementary events of cardiac E-C coupling [2]. Whole cell Ca2+ transients are believed to represent the recruitment and summation of many Ca2.