Insights into the structural biology of G-protein coupled receptors impacts drug design for central nervous system neurodegenerative processes**

In the last few years, there have been important new insights into the structural biology of G-protein coupled receptors. It is now known that allosteric binding sites are involved in the affinity and selectivity of ligands for G-protein coupled receptors, and that signaling by these receptors involves both G-protein dependent and independent pathways. The present review outlines the physiological and pharmacological implications of this perspective for the design of new drugs to treat disorders of the central nervous system. Specifically, new possibilities are explored in relation to allosteric and orthosteric binding sites on dopamine receptors for the treatment of Parkinson’s disease, and on muscarinic receptors for Alzheimer’s disease. Future research can seek to identify ligands that can bind to more than one site on the same receptor, or simultaneously bind to two receptors and form a dimer. For example, the design of bivalent drugs that can reach homo/hetero-dimers of D2 dopamine receptor holds promise as a relevant therapeutic strategy for Parkinson’s disease. Regarding the treatment of Alzheimer’s disease, the design of dualsteric ligands for mono-oligomeric muscarinic receptors could increase therapeutic effectiveness by generating potent compounds that could activate more than one signaling pathway.     

Functional analysis of HIV type 1 Nef gene variants from adolescent and adult survivors of perinatal infection

Throughout the world, infants and children with HIV-1 infection are increasingly surviving into adolescence and adulthood. As HIV Nef is an important determinant of the pathogenic potential of the virus, we examined nef alleles in a cohort of extreme long-term survivors of HIV infection (average age of 16.6 years) to determine if Nef defects might have contributed to patient survival. HIV nef gene sequences were amplified for phylogenetic analysis from 15 adolescents and adults infected by mother-to-child transmission (n=10) or by blood transfusion (n=5). Functional analysis was performed by inserting patient-derived nef sequences into an HIV-derived vector that permits simultaneous evaluation of the impact of the Nef protein on MHC-I and CD4 cell surface expression. We found evidence of extensive nef gene diversity, including changes in known functional domains involved in the downregulation of cell surface MHC-I and CD4. Only 3 of 15 individuals (20%) had nef alleles with a loss of the ability to downregulate either CD4 or MHC-I. Survival into adulthood with HIV infection acquired in infancy is not uniformly linked to loss of function in nef. The Nef protein remains a potential target for immunization or pharmacologic intervention.     

A comprehensive, longitudinal description of the in-hospital and post-discharge clinical, laboratory, and neurohormonal course of patients with heart failure who die or are re-hospitalized within 90?days: analysis from the EVEREST trial

Hospitalization for worsening chronic heart failure results in high post-discharge mortality, morbidity, and cost. However, thorough characterization, soon after discharge of patients with early post-discharge events has not been previously performed. The objectives of this study were to describe the baseline, in-hospital, and post-discharge clinical, laboratory, and neurohormonal profiles of patients hospitalized for worsening heart failure with reduced ejection fraction (EF) who die or are re-admitted for cardiovascular (CV) causes within 90 days of initial hospitalization. Retrospective analysis of 4,133 patients hospitalized for worsening heart failure with EF ≤40% in the Efficacy of Vasopressin Antagonism in Heart Failure: Outcome Study with Tolvaptan (EVEREST) trial, which randomized patients to tolvaptan or placebo, both in addition to standard therapy. Clinical and laboratory parameters were obtained within 48?h of admission, during hospitalization, and post-discharge weeks 1, 4, 8, and every 8?weeks thereafter for a median of 9.9?months. Patients with events within 90?days were compared with those with later/no events. All-cause mortality (ACM) and CV re-hospitalization were independently adjudicated. Within 90?days of admission, 395 patients (9.6%) died and 801 patients (19.4%) were re-hospitalized for CV causes. Significant baseline and longitudinal differences were seen between groups with early versus later (>90?days) or no events at 12?months post-randomization. Post-discharge outcomes were similar in the tolvaptan and placebo groups. Patients with early post-discharge events experienced clinically significant worsening in signs and symptoms, laboratory values, and neurohormonal parameters soon after discharge. Identifying these abnormalities may facilitate efforts to reduce post-discharge mortality and re-hospitalization.