Effects of Direct Renin Inhibition on Myocardial Fibrosis and Cardiac Fibroblast Function

Myocardial fibrosis, a major pathophysiologic substrate of heart failure with preserved ejection fraction (HFPEF), is modulated by multiple pathways including the renin-angiotensin system. Direct renin inhibition is a promising anti-fibrotic therapy since it attenuates the pro-fibrotic effects of renin in addition to that of other effectors of the renin-angiotensin cascade. Here we show that the oral renin inhibitor aliskiren has direct effects on collagen metabolism in cardiac fibroblasts and prevented myocardial collagen deposition in a non-hypertrophic mouse model of myocardial fibrosis. Adult mice were fed hyperhomocysteinemia-inducing diet to induce myocardial fibrosis and treated concomitantly with either vehicle or aliskiren for 12 weeks. Blood pressure and plasma angiotensin II levels were normal in control and hyperhomocysteinemic mice and reduced to levels lower than observed in the control group in the groups treated with aliskiren. Homocysteine-induced myocardial matrix gene expression and fibrosis were also prevented by aliskiren. In vitro studies using adult rat cardiac fibroblasts also showed that aliskiren attenuated the pro-fibrotic pattern of matrix gene and protein expression induced by D,L, homocysteine. Both in vivo and in vitro studies demonstrated that the Akt pathway was activated by homocysteine, and that treatment with aliskiren attenuated Akt activation. In conclusion, aliskiren as mono-therapy has potent and direct effects on myocardial matrix turnover and beneficial effects on diastolic function

Simplifying complex information structures: The Application of archiving and mapping strategies in the design of prescription drug labeling

Information Design involves finding meaningful solutions to raw and complex data that is difficult to understand. Archiving and Mapping are approached as means of information design during the course of this thesis study. The process of Archiving involves collection, documentation and organization of data. Traditional Archiving methods are studied along with analyzing organization of large amounts of information in the form of web sites, publications, annual reports and reference books. The approach towards Mapping is not limited to just geographic contexts. Maps can be visualized in the form of an idea, metaphor or process. Graphic Design elements such as color, shape, line weight, typography, imagery, etc. are used as visual aids in the creation of maps. The study of these visual aids and their role in making raw data decipherable forms the crux of this study. This thesis focuses on identification of archiving and mapping strategies and applying them to the design of prescription labeling. Although the focus of this study is on the design of prescription labels, these strategies can be used in finding efficient design solutions to everyday life problems

Renin and cardiovascular disease: Worn-out path, or new direction

Inhibition of the renin angiotensin system has beneficial effects in cardiovascular prevention and treatment. The advent of orally active direct renin inhibitors adds a novel approach to antagonism of the renin-angiotensin system. Inhibition of the first and rate-limiting step of the renin angiotensin cascade offers theoretical advantages over downstream blockade. However, the recent discovery of the (pro)renin receptor which binds both renin and prorenin, and which can not only augment catalytic activity of both renin and prorenin in converting angiotensinogen to angiotensin I, but also signal intracellularly via various pathways to modulate gene expression, adds a significant level of complexity to the field. In this review, we will examine the basic and clinical data on renin and its inhibition in the context of cardiovascular pathophysiology

AN INVESTIGATION ON THE MOLECULAR BASIS FOR DIMER FORMATION OF A BACTERIOPHAGE ENDOLYSIN POSSESSING ANTIMICROBIAL ACTIVITY AGAINST STREPTOCOCCUS PNEUMONIAE

The global rise of antibiotic resistance casts a shadow on treating infectious disease. An alternative to the use of antibiotics is bacteriophage-derived peptidoglycan hydrolases called endolysins. Endolysins, produced at the end of a bacteriophage replication cycle, cause bacterial cell lysis and virion release. When applied exogenously as recombinant proteins, they are also capable of cleaving the Gram-positive bacterial peptidoglycan. Various studies conducted in vitro and in vivo showcase the therapeutic potential of endolysins as the next generation of antimicrobials. Streptococcus pneumoniae is the most common cause of a variety of infections ranging from otitis media to invasive bloodstream infection (bacteremia) and meningitis (brain infection). While pneumococcal vaccination programs have proven to be effective, the high rates of antibiotic resistance reported for S. pneumoniae has led to the CDC classifying it as a “serious” threat. One of the most studied endolysins targeting S. pneumoniae is Cpl-1. This thesis represents an investigation into the molecular basis for dimer formation of the Cpl-1 endolysin which displays antibacterial activity against S. pneumoniae. In addition to disproving a long-accepted mechanism of dimerization of Cpl-1 in the presence of choline, we have conclusively identified the residue involved in the formation of the Cpl-1 dimer. Our findings led to the discovery of a novel C-terminal consensus sequence shared by all pneumococcal endolysins that informs their propensity to form dimers in the presence of choline. Next, through a bioinformatics approach we identified a new endolysin containing this C-terminal consensus sequence, produced it, named it SP-CHAP, and showed that it forms a dimer in the presence of choline, indicative of the widespread dimerization phenomenon associated with pneumococcal endolysins. Of interest, SP-CHAP is the first endolysin with antimicrobial activity against S. pneumoniae that possesses a cysteine, histidine-dependent amidohydrolase/peptidase (CHAP) domain. SP-CHAP was subsequently characterized for its biochemical and antimicrobial properties and benchmarked against Cpl-1. SP-CHAP is active in all physiologically relevant conditions (pH, temperature) against various S. pneumoniae strains and displays no activity towards oral/nasal commensal organisms. This enzyme also displays pneumococcal biofilm eradication ability to a greater extent than Cpl-1, as visualized by confocal microscopy. To further translate the antimicrobial potential of this enzyme, the antimicrobial efficacy of SP-CHAP was validated in a S. pneumoniae mouse nasopharyngeal colonization model. Our results demonstrate the therapeutic potential of SP-CHAP as an attractive endolysin to treat S. pneumoniae infections and warrant further translational development of this enzyme