Neutron Reflectometry and Molecular Simulations Demonstrate HIV-1 Nef Homodimer Formation on Model Lipid Bilayers.

The HIV-1 Nef protein plays a critical role in viral infectivity, high-titer replication in vivo, and immune escape of HIV-infected cells. Nef lacks intrinsic biochemical activity, functioning instead through interactions with diverse host cell signaling proteins and intracellular trafficking pathways. Previous studies have established an essential role for Nef homodimer formation at the plasma membrane for most if not all its functions. Here we combined neutron reflectometry of full-length myristoylated Nef bound to model lipid bilayers with molecular simulations based on previous X-ray crystal structures of Nef homodimers. This integrated approach provides direct evidence that Nef associates with the membrane as a homodimer with its structured core region displaced from the membrane for partner protein engagement. Parallel studies of a dimerization-defective mutant, Nef-L112D, demonstrate that the helical dimerization interface present in previous crystal structures stabilizes the membrane-bound dimer. X-ray crystallography of the Nef-L112D mutant in complex with the SH3 domain of the Nef-associated host cell kinase Hck revealed a monomeric 1:1 complex instead of the 2:2 dimer complex formed with wild-type Nef. Importantly, the crystal structure of the Nef-L112D core and SH3 interface are virtually identical to the wild-type complex, indicating that this mutation does not affect the overall Nef fold. These findings support the intrinsic capacity of Nef to homodimerize at lipid bilayers using structural features present in X-ray crystal structures of dimeric complexes.

Antiretroviral Drug Discovery Targeting the HIV-1 Nef Virulence Factor.

While antiretroviral drugs have transformed the lives of HIV-infected individuals, chronic treatment is required to prevent rebound from viral reservoir cells. People living with HIV also are at higher risk for cardiovascular and neurocognitive complications, as well as cancer. Finding a cure for HIV-1 infection is therefore an essential goal of current AIDS research. This review is focused on the discovery of pharmacological inhibitors of the HIV-1 Nef accessory protein. Nef is well known to enhance HIV-1 infectivity and replication, and to promote immune escape of HIV-infected cells by preventing cell surface MHC-I display of HIV-1 antigens. Recent progress shows that Nef inhibitors not only suppress HIV-1 replication, but also restore sufficient MHC-I to the surface of infected cells to trigger a cytotoxic T lymphocyte response. Combining Nef inhibitors with latency reversal agents and therapeutic vaccines may provide a path to clearance of viral reservoirs.

Percutaneous Gastrostomy Device for the Treatment of Class II and Class III Obesity: Results of a Randomized Controlled Trial.

OBJECTIVES: The AspireAssist System (AspireAssist) is an endoscopic weight loss device that is comprised of an endoscopically placed percutaneous gastrostomy tube and an external device to facilitate drainage of about 30% of the calories consumed in a meal, in conjunction with lifestyle (diet and exercise) counseling. METHODS: In this 52-week clinical trial, 207 participants with a body-mass index (BMI) of 35.0-55.0 kg/m2 were randomly assigned in a 2:1 ratio to treatment with AspireAssist plus Lifestyle Counseling (n=137; mean BMI was 42.2±5.1 kg/m2) or Lifestyle Counseling alone (n=70; mean BMI was 40.9±3.9 kg/m2). The co-primary end points were mean percent excess weight loss and the proportion of participants who achieved at least a 25% excess weight loss. RESULTS: At 52 weeks, participants in the AspireAssist group, on a modified intent-to-treat basis, had lost a mean (±s.d.) of 31.5±26.7% of their excess body weight (12.1±9.6% total body weight), whereas those in the Lifestyle Counseling group had lost a mean of 9.8±15.5% of their excess body weight (3.5±6.0% total body weight) (P<0.001). A total of 58.6% of participants in the AspireAssist group and 15.3% of participants in the Lifestyle Counseling group lost at least 25% of their excess body weight (P<0.001). The most frequently reported adverse events were abdominal pain and discomfort in the perioperative period and peristomal granulation tissue and peristomal irritation in the postoperative period. Serious adverse events were reported in 3.6% of participants in the AspireAssist group. CONCLUSIONS: The AspireAssist System was associated with greater weight loss than Lifestyle Counseling alone.

Low adoption of weight loss medications: A comparison of prescribing patterns of antiobesity pharmacotherapies and SGLT2s.

OBJECTIVE: To characterize the adoption of antiobesity pharmacotherapies, as compared with that of the newest antidiabetes pharmacotherapy, subtype 2 sodium-glucose transport protein inhibitors (SGLT2s), among prescribers in the United States. METHODS: A retrospective analysis of 2012 to 2015 data extracted from the IMS Health National Prescription Audit™ and Xponent™ assessed adoption rates of antiobesity pharmacotherapies and SGLT2s. RESULTS: The number of dispensed antidiabetes prescriptions was 15 times the number of dispensed antiobesity prescriptions. The antiobesity market share was: 74.0% phentermine, 18.6% new antiobesity pharmacotherapies. The mean increase in prescriptions/month were: 25,259 for SGLT2s, 5,154 for new antiobesity pharmacotherapies, and 2,718 for phentermine. Medical specialties prescribing the majority of the analysis medications were Family Medicine/General Practice and Internal Medicine. Endocrinology had the highest prevalence of prescribers of any subspecialty. CONCLUSIONS: The adoption rate of SGLT2s was nearly exponential, while the adoption rate of new antiobesity pharmacotherapies was linear. Considering the relative prevalence of obesity to diabetes and that obesity is a major cause of diabetes, these results are paradoxical and suggest systematic barriers against the prescribing of antiobesity pharmacotherapies. The under-prescribing of antiobesity pharmacotherapies is widely acknowledged, but this is the first prescription data of these new medications to demonstrate its extent in the United States.