Long-term rescue of a familial hypertrophic cardiomyopathy caused by a mutation in the thin filament protein, tropomyosin, via modulation of a calcium cycling protein.

We have recently shown that a temporary increase in sarcoplasmic reticulum (SR) cycling via adenovirus-mediated overexpression of sarcoplasmic reticulum ATPase (SERCA2) transiently improves relaxation and delays hypertrophic remodeling in a familial hypertrophic cardiomyopathy (FHC) caused by a mutation in the thin filament protein, tropomyosin (i.e., α-TmE180G or Tm180). In this study, we sought to permanently alter calcium fluxes via phospholamban (PLN) gene deletion in Tm180 mice in order to sustain long-term improvements in cardiac function and adverse cardiac remodeling/hypertrophy. While similar work has been done in FHCs resulting from mutations in thick myofilament proteins, no one has studied these effects in an FHC resulting from a thin filament protein mutation. Tm180 transgenic (TG) mice were crossbred with PLN knockout (KO) mice and four groups were studied in parallel: 1) non-TG (NTG), 2) Tm180, 3) PLNKO/NTG and 4) PLNKO/Tm180. Tm180 mice exhibit increased heart weight/body weight and hypertrophic gene markers compared to NTG mice, but levels in PLNKO/Tm180 mice were similar to NTG. Tm180 mice also displayed altered function as assessed via in situ pressure-volume analysis and echocardiography at 3-6 months and one year; however, altered function in Tm180 mice was rescued back to NTG levels in PLNKO/Tm180 mice. Collagen deposition, as assessed by Picrosirius Red staining, was increased in Tm180 mice but was similar in NTG and in PLNKO/Tm180 mice. Extracellular signal-regulated kinase (ERK1/2) phosphorylation increased in Tm180 mice while levels in PLNKO/Tm180 mice were similar to NTGs. The present study shows that by modulating SR calcium cycling, we were able to rescue many of the deleterious aspects of FHC caused by a mutation in the thin filament protein, Tm.

Neonatal gene transfer of Serca2a delays onset of hypertrophic remodeling and improves function in familial hypertrophic cardiomyopathy.

Familial hypertrophic cardiomyopathy (FHC) is an autosomal dominant genetic disorder linked to numerous mutations in the sarcomeric proteins. The clinical presentation of FHC is highly variable, but it is a major cause of sudden cardiac death in young adults with no specific treatments. We tested the hypothesis that early intervention in Ca(2+) regulation may prevent pathological hypertrophy and improve cardiac function in a FHC displaying increased myofilament sensitivity to Ca(2+) and diastolic dysfunction. A transgenic (TG) mouse model of FHC with a mutation in tropomyosin at position 180 was employed. Adenoviral-Serca2a (Ad.Ser) was injected into the left ventricle of 1-day-old non-transgenic (NTG) and TG mice. Ad.LacZ was injected as a control. Serca2a protein expression was significantly increased in NTG and TG hearts injected with Ad.Ser for up to 6 weeks. Compared to TG-Ad.LacZ hearts, the TG-Ad.Ser hearts showed improved whole heart morphology. Moreover, there was a significant decline in ANF and ß-MHC expression. Developed force in isolated papillary muscle from 2- to 3-week-old TG-Ad.Ser hearts was higher and the response to isoproterenol (ISO) improved compared to TG-Ad.LacZ muscles. In situ hemodynamic measurements showed that by 3 months the TG-Ad.Ser hearts also had a significantly improved response to ISO compared to TG-Ad.LacZ hearts. The present study strongly suggests that Serca2a expression should be considered as a potential target for gene therapy in FHC. Moreover, our data imply that development of FHC can be successfully delayed if therapies are started shortly after birth.

Development and implementation of a piperacillin-tazobactam extended infusion guideline.

Administration of ß-lactam antibiotics by extended infusion optimizes the pharmacodynamic properties and bactericidal activity of these agents resulting in a potential improvement in patient outcomes and reduction in drug expenditure. Consequently, a pharmacist-led piperacillin-tazobactam extended 4-hour infusion guideline was implemented hospital-wide at a 500-bed academic medical center. Each piperacillin-tazobactam infusion was prospectively monitored for 5 weeks to ensure accurate administration and identify barriers to guideline adherence. Overall, a total of 103 patients received 1215 doses of piperacillin-tazobactam by extended infusions. In all, 98% of the doses were administered at the correct extended infusion rate and 94% of the doses were given at the scheduled time. There were a total of 20 missed doses and 53 delayed doses, accounting for 2% and 4% of the total administered doses, respectively. The primary barrier to adherence was the patient not being on the unit at the time of the scheduled dose followed by the piperacillin-tazobactam dose not being available on the floor. While insufficient power prevented meaningful evaluation of clinical outcomes, we anticipate a conservative annual estimated cost savings of $108,529. Key elements contributing to our success included consistent pharmacy leadership, multidisciplinary involvement, thorough inservicing to health care professionals, hospital-wide implementation, and extensive quality assurance monitoring.