Effects of short-course zidovudine on the selection of nevirapine-resistant HIV-1 in women taking single-dose nevirapine

Single-dose nevirapine (sdNVP) given to prevent mother-to-child-transmission of HIV-1 selects NVP-resistance. Short-course zidovudine (ZDV) was hypothesized to lower rates of NVP-resistance. HIV-1 infected pregnant women administered sdNVP with or without short-course ZDV were assessed for HIV-1 mutations (K103N, Y181C, G190A, and V106M) prior to delivery and postpartum. Postpartum NVP-resistance was lower among 31 taking ZDV+sdNVP compared to 33 taking only sdNVP (35.5% vs. 72.7%; χ2 P = .003). NVP mutants decayed to <2% in 24/35 (68.6%) at a median 6 months postpartum, with no differences based on ZDV use (logrank P = .99). Short-course ZDV was associated with reduced NVP-resistance mutations among women taking sdNVP.     

Benznidazole-resistance in Trypanosoma cruzi is a readily acquired trait that can arise independently in a single population

Benznidazole is the frontline drug used against Trypanosoma cruzi, the causative agent of Chagas disease. However, treatment failures are often reported. Here, we demonstrate that independently acquired mutations in the gene encoding a mitochondrial nitroreductase (TcNTR) can give rise to distinct drug-resistant clones within a single population. Following selection of benznidazole-resistant parasites, all clones examined had lost one of the chromosomes containing the TcNTR gene. Sequence analysis of the remaining TcNTR allele revealed 3 distinct mutant genes in different resistant clones. Expression studies showed that these mutant proteins were unable to activate benznidazole. This correlated with loss of flavin mononucleotide binding. The drug-resistant phenotype could be reversed by transfection with wild-type TcNTR. These results identify TcNTR as a central player in acquired resistance to benznidazole. They also demonstrate that T. cruzi has a propensity to undergo genetic changes that can lead to drug resistance, a finding that has implications for future therapeutic strategies.     

Comparison of High Ribavirin Induction Versus Standard Ribavirin Dosing, Plus Peginterferon-α for the Treatment of Chronic Hepatitis C in HIV-Infected Patients: The PERICO Trial

Background.?Ribavirin (RBV) exposure seems to be critical to maximize treatment response in human immunodeficiency virus (HIV)-positive patients with chronic hepatitis C virus (HCV) infection. Methods.?HIV/HCV-coinfected individuals naive to interferon were prospectively randomized to receive peginterferon-α-2a (180?μg/d) plus either RBV standard dosing (1000 or 1200?mg/d if <75 or ≥75?kg, respectively) or RBV induction (2000?mg/d) along with subcutaneous erythropoietin β (450?IU/kg/wk), both during the first 4 weeks, followed by standard RBV dosing until completion of therapy. Early stopping rules at weeks 12 and 24 were applied in patients with suboptimal virological response. Results.?A total of 357 patients received ≥1 dose of the study medication. No differences in main baseline characteristics were found when comparing treatment arms. Sustained virological response (SVR) was attained by 160 (45%) patients, with no significant differences between RBV induction and standard treatment arms (SVR in 72 of 169 patients [43%] vs 88 of 188 [47%], respectively). At week 4, undetectable HCV RNA (29% vs 25%) and mean RBV trough concentration (2.48 vs 2.14?μg/mL) were comparable in both arms, whereas mean hemoglobin decay was less pronounced in the RBV induction plus erythropoietin arm than in the RBV standard dosing arm (-1.7 vs -2.3?mg/dL; P?相似文献   

The removal from plasma of chylomicrons and remnants is reduced in heterozygous familial hypercholesterolemia subjects with identified LDL receptor mutations: study with artificial emulsions

Chylomicron remnants bind to both their specific receptors (LRP) and to the LDL receptor (LDLR) in the liver. There is controversy whether disturbances of chylomicron metabolism occur in subjects with familial hypercholesterolemia (FH). The aim of this study was to evaluate whether there are defects on the removal from plasma of chylomicrons and their remnants in heterozygous FH patients with determined LDLR mutations. We studied 20 heterozygous FH patients (43.2±12 years old, 60% males) and 50 normolipidemic subjects matched for age and gender. FH subjects were not in use of LDL-lowering drugs for at least 6 weeks. The removal from plasma of chylomicrons and their remnants was measured by isotopic decay after venous injection of a chylomicron-like emulsion radiolabeled with (14)C-cholesteryl ester ((14)C-CE) and (3)H-triolein ((3)H-TO). These track respectively removal from plasma of chylomicrons and remnants and lipolysis. There was a significant reduction in the fractional catabolic rates (FCR in h(-1)) of (14)C-CE in FH in comparison with normolipidemics: 0.048 (1.46.10(-7); 0.57) vs. 0.71(0.049; 1.62), [median (25th-75th percentile)], p=0.003. No differences were found in FCR of (3)H-TO between FH and controls, respectively 1.62 (1.02; 2.331) and 1.914 (1.34; 2.878), p=0.405. In conclusion heterozygous FH subjects had a significant decrease on the removal from plasma of chylomicrons and their remnants compared with normolipidemics.     

Sex differences in the effect of high-fat diet feeding on rat white adipose tissue mitochondrial function and insulin sensitivity

Obesity-induced mitochondrial dysfunction in white adipose tissue (WAT) leads to a dysregulation of adipokine secretion, which is involved in insulin resistance development. Taking into account the sex differences previously found both in mitochondrial function and for the insulin sensitivity profile in different tissues, the aim of this study was to investigate whether a sex-dependent effect of a long-term high-fat diet (HFD) feeding exists on WAT mitochondrial function. Indeed, HFD effects on the levels of the key components of the insulin and adiponectin signaling pathways, and the consequences of these effects on the systemic profile of insulin sensitivity were also studied. Wistar rats of both sexes were fed a standard diet or an HFD. Serum markers of insulin sensitivity, protein, and mRNA levels of the main elements of the insulin and adiponectin signaling pathways, and the markers of mitochondrial function and biogenesis, were measured. Our results indicate that different physiological strategies are adopted by male and female rats in response to HFD. In this regard, HFD induced mitochondrial proliferation in males and mitochondrial differentiation in females, as well as a greater retroperitoneal WAT expandability capacity, which allows them to preserve a better insulin sensitivity profile than male rats for both control and HFD groups. Moreover, female WAT showed a decrease in adiponectin and insulin signaling pathway element levels. This sexual dimorphism suggests that there are different strategies for retroperitoneal WAT to maintain the energetic and metabolic homeostasis in response to HFD feeding.