Receptor Complementation and Mutagenesis Reveal SR-BI as an Essential HCV Entry Factor and Functionally Imply Its Intra- and Extra-Cellular Domains

HCV entry into cells is a multi-step and slow process. It is believed that the initial capture of HCV particles by glycosaminoglycans and/or lipoprotein receptors is followed by coordinated interactions with the scavenger receptor class B type I (SR-BI), a major receptor of high-density lipoprotein (HDL), the CD81 tetraspanin, and the tight junction protein Claudin-1, ultimately leading to uptake and cellular penetration of HCV via low-pH endosomes. Several reports have indicated that HDL promotes HCV entry through interaction with SR-BI. This pathway remains largely elusive, although it was shown that HDL neither associates with HCV particles nor modulates HCV binding to SR-BI. In contrast to CD81 and Claudin-1, the importance of SR-BI has only been addressed indirectly because of lack of cells in which functional complementation assays with mutant receptors could be performed. Here we identified for the first time two cell types that supported HCVpp and HCVcc entry upon ectopic SR-BI expression. Remarkably, the undetectable expression of SR-BI in rat hepatoma cells allowed unambiguous investigation of human SR-BI functions during HCV entry. By expressing different SR-BI mutants in either cell line, our results revealed features of SR-BI intracellular domains that influence HCV infectivity without affecting receptor binding and stimulation of HCV entry induced by HDL/SR-BI interaction. Conversely, we identified positions of SR-BI ectodomain that, by altering HCV binding, inhibit entry. Finally, we characterized alternative ectodomain determinants that, by reducing SR-BI cholesterol uptake and efflux functions, abolish HDL-mediated infection-enhancement. Altogether, we demonstrate that SR-BI is an essential HCV entry factor. Moreover, our results highlight specific SR-BI determinants required during HCV entry and physiological lipid transfer functions hijacked by HCV to favor infection

Neuropatia vegetativa em pacientes com tolerância diminuída à glicose Autonomic neuropathy in patients with impaired glucose tolerance test

Com o objetivo de determinar se tolerância diminuída à glicose (TDG) está associada a neuropatia vegetativa realizamos estudo transversal de que participaram 44 pacientes com intolerância a glicose (Grupo 1) os quais foram comparados com 43 indivíduos controles apresentando teste de tolerância à glicose normal (Grupo 2). Os pacientes de ambos os grupos, após aceitarem participar da pesquisa, eram submetidos a anamnese, exames clínico e laboratoriais e estudo da função vegetativa (intervalo QT, prova da arritmia sinusal, manobra de Valsalva e teste postural). Os pacientes com TDG apresentaram mais hipertensão arterial sistêmica, obesidade centrípeta, hiperglicemas de jejum e pós-prandiais e dislipidemias que os controles. O teste de arritmia sinusal estava alterado em 54,5% dos grupo 1 e em 32,5% do grupo 2. A manobra de Valsalva foi anormal em 34,1% no grupo 1 e em 7% dos controles (p=0,004). A prova postural não foi diferente nos dois grupos. O comprometimento do sistema neurovegetativo foi mais freqüente nos pacientes com TDG que nos controles. A maior freqüência de fatores de risco para doença aterosclerótica cardiovascular e o concomitante comprometimento do sistema nervoso vegetativo nos pacientes com TDG podem ser os responsáveis pelas elevadas taxas de letalidade devida a vasculopatias observadas nessa população.<br>Impaired glucose tolerance (1GT) is a clinical situation characterized by mild hyperglicemia, which is estimated to afflict 7.8% of the Brazilian population. Diabetic neuropathy is the most common: complication in diabetes mellitus and it is related to morbidity and lethality in this disease. The associatior between IGT and peripheral neuropathy is still a matter of great concern. PURPOSE AND METHOD: In order to determine if IGT is associated with autonomic neuropathy a cross-sectional study in 44 patients with impaired glucose tolerance test (Group 1) was performed. The patients were compared to 43 control individuals (Group 2). Every patient in each group underwent anamnesis and standardized autonomic tests which consisted of hear) frequency test, Valsalva maneuver, postural test and sinus arrythmia. Routine hematologic exams as well as GTT were also made. RESULTS: Patients in group 1 had more systemic arterial hypertension, centripetal obesity, fasting and post-feeding hyperglicemia and dyslipidemia when compared with group 2. When we analysed the autonomic tests, the sinus arrythmia test was abnormal in 54.5% of the patients in group 1 and in 32.5% in group 2 (p=0.0039) and the Valsalva maneuver was abnormal in 34.1% of group 1 and in 7% of group 2 (p=0.004). The postural test was not different in both groups (p=0.334). CONCLUSION: Our results show that the involvement of the autonomic nervous system was more frequent in patients with IGT when compared to controls. These findings can explair the increased lethality due to vasculopathies observed in this group of patients and also alert physicians to care for patients with impaired glucose tolerance test

Monoclonal autoantibodies specific for oxidized phospholipids or oxidized phospholipid–protein adducts inhibit macrophage uptake of oxidized low-density lipoproteins

We recently cloned monoclonal IgM autoantibodies which bind to epitopes of oxidized low-density lipoprotein (OxLDL) from apoE-deficient mice (EO(–) autoantibodies). We now demonstrate that those EO(–) autoantibodies that were originally selected for binding to copper-oxidized low-density lipoproteins (CuOx-LDL), also bound both to the oxidized protein and to the oxidized lipid moieties of CuOx-LDL. The same EO(–) autoantibodies showed specific binding to products of oxidized 1-palmitoyl-2-arachidonoyl-phosphatidylcholine (OxPAPC) and to the specific oxidized phospholipid, 1-palmitoyl-2-(5-oxovaleroyl)-phosphatidyl-choline (POVPC), whereas oxidation of fatty acids (linoleic or arachidonic acid) or cholesteryl esters (cholesteryl-oleate or cholesteryl-linoleate) did not yield any binding activity. Those EO(–) autoantibodies that bound to oxidized phospholipids (e.g., EO6) inhibited the binding and degradation of CuOx-LDL by mouse peritoneal macrophages up to 91%, whereas other IgM EO(–) autoantibodies, selected for binding to malondialdehyde (MDA)-LDL, had no influence on binding of either CuOx-LDL or MDA-LDL by macrophages. F(ab′)(2) fragments of EO6 were equally effective as the intact EO6 in preventing the binding of CuOx-LDL by macrophages. The molar ratios of IgM to LDL needed to maximally inhibit the binding varied from ∼8 to 25 with different CuOx-LDL preparations. Finally, a POVPC–bovine serum albumin (BSA) adduct also inhibited CuOx-LDL uptake by macrophages. These data suggest that oxidized phospholipid epitopes, present either as lipids or as lipid-protein adducts, represent one class of ligands involved in the recognition of OxLDL by macrophages, and that apoE-deficient mice have IgM autoantibodies that can bind to these neoepitopes and inhibit OxLDL uptake

Laboratories for global space-time: science-fictionality and the World’s Fairs, 1851-1939

This article examines the world’s fair movement between The Great Exhibition of 1851 and The New York World’s Fair of 1939, suggesting that these sites are science-fictional spaces that expose their mass audiences to forms of space-time compression that enable early figurations of globalization. Fair sites embody specific forms of economic transfer and exchange that anticipate dreams of the borderless flows of capital in some current versions of globalization theory. This “sfnal” condition of the world’s-fair site is not just in the futuristic displays of techno-scientific “progress,” which became an insistent form of spectacle in the world’s fair, but also in the spatialization of developmental histories, reading conceptions of modernity remorselessly through hierarchies of racial “progress” or spectacles of anachronistic “arrest” or degenerative “decline.” Long before the famous Futurama of 1939 New York, world’s fairs were one of the first spaces in which large populations experienced deliberate and sustained disadjustment in time within a bounded zone, an early sense of immersion in the “science-fictional.

Effects of once-weekly exenatide on cardiovascular outcomes in type 2 diabetes

BACKGROUND: The cardiovascular effects of adding once-weekly treatment with exenatide to usual care in patients with type 2 diabetes are unknown. METHODS: We randomly assigned patients with type 2 diabetes, with or without previous cardiovascular disease, to receive subcutaneous injections of extended-release exenatide at a dose of 2 mg or matching placebo once weekly. The primary composite outcome was the first occurrence of death from cardiovascular causes, nonfatal myocardial infarction, or nonfatal stroke. The coprimary hypotheses were that exenatide, administered once weekly, would be noninferior to placebo with respect to safety and superior to placebo with respect to efficacy. RESULTS: In all, 14,752 patients (of whom 10,782 [73.1%] had previous cardiovascular disease) were followed for a median of 3.2 years (interquartile range, 2.2 to 4.4). A primary composite outcome event occurred in 839 of 7356 patients (11.4%; 3.7 events per 100 person-years) in the exenatide group and in 905 of 7396 patients (12.2%; 4.0 events per 100 person-years) in the placebo group (hazard ratio, 0.91; 95% confidence interval [CI], 0.83 to 1.00), with the intention-to-treat analysis indicating that exenatide, administered once weekly, was noninferior to placebo with respect to safety (P<0.001 for noninferiority) but was not superior to placebo with respect to efficacy (P=0.06 for superiority). The rates of death from cardiovascular causes, fatal or nonfatal myocardial infarction, fatal or nonfatal stroke, hospitalization for heart failure, and hospitalization for acute coronary syndrome, and the incidence of acute pancreatitis, pancreatic cancer, medullary thyroid carcinoma, and serious adverse events did not differ significantly between the two groups. CONCLUSIONS: Among patients with type 2 diabetes with or without previous cardiovascular disease, the incidence of major adverse cardiovascular events did not differ significantly between patients who received exenatide and those who received placebo