Cross-resistance, fitness costs, and biochemical mechanism of laboratory-selected resistance to tenvermectin A in Plutella xylostella.

BACKGROUND: Tenvermectin A is a new avermectin derivative that has good insecticidal and acaricidal effects. In order to study the resistance of Plutella xylostella to tenvermectin A, a sensitive strain (SS) and a laboratory-selected tenvermectin A-resistant strain (RS, 33.57-fold) were used to evaluate cross-resistance and fitness costs as well as to determine the resistance mechanism. RESULTS: There was no cross-resistance with common pesticides except for moderate cross-resistance with cypermethrin (resistance ratio = 10.26-fold) observed in RS. The activities of metabolic enzymes were measured, and the results showed that mixed function oxidase (MFO) and carboxylate esterase (CarE) in RS increased significantly by 2.92- and 2.86-fold, respectively, compared with SS. In addition, there was no obvious difference in glutathione-S-transferase (GST), which indicated that enhanced MFO and CarE activities may be the main mechanisms of detoxification. In the four typical resistance-related genes, expression of GluCl (4.86-fold), ABCC2 (3.85-fold), and CYP6 (2.94-fold) in RS were significantly promoted, but expression of GST was not. The clone and sequence of the PxGluClα subunit displayed six mutations that could lead to changes in the amino acid residues. CONCLUSION: High suitability related to tenvermectin A resistance was observed in RS, and it was found that the developmental stages of RS were significantly shortened and the survival rate of females was reduced. In addition, the mechanism of resistance to tenvermectin A may be regulated by the glutamate-gated chloride channel, ATP-binding cassette transporter, and MFO. In general, the study of resistance and biochemical mechanisms can provide beneficial and rational information for the management of resistance in P. xylostella. © 2021 Society of Chemical Industry.

Effects of long-term indiscriminate use of macrocyclic lactones in cattle: Parasite resistance, clinical helminthosis, and production losses.

Our aims were to describe a case of clinical helminthosis caused by parasite resistance to macrocyclic lactones (MLs) after the long-term frequent use of these drugs in a cattle herd, and to evaluate the production losses prevented by the use of an effective anthelmintic treatment to control these resistant gastrointestinal nematodes (GINs). A case of clinical helminthosis culminating in the death of steers was investigated, the history of the antiparasitic treatments used during an 11-year period in the herd was assessed, and an efficacy test involving seven different drugs was performed. Thereafter, two groups of heifers naturally infected by ML-resistant GINs were formed and strategically treated with either a highly effective (levamisole) or less effective drug (doramectin) over a 9-month period. The heifers were evaluated monthly based on eggs per gram of feces (EPG) counts and liveweights. An evaluation of the history of parasite control in the farm revealed that MLs were used in 96.5% of the treatments aimed at controlling GINs, ticks, and myiasis in the herd. The efficacy test showed the presence of GINs resistance to all the MLs tested. However, levamisole and albendazole sulphoxide were highly effective against these parasites. Heifers treated with levamisole gained 12.1 kg more liveweight on average, compared to those treated with doramectin. Thus, we conclude that indiscriminate and long-term use of MLs in the studied herd led to the failure of GINs control, a critical situation resulting in significant production losses, and a surge of clinical helminthosis in young cattle. In addition, we showed increase in liveweight gain due to using a highly effective drug, in comparison to an ML, during a 9-month period, in heifers naturally infected by ML-resistant GINs.

Sampling and refinement protocols for template-based macrocycle docking: 2018 D3R Grand Challenge 4.

We describe a new template-based method for docking flexible ligands such as macrocycles to proteins. It combines Monte-Carlo energy minimization on the manifold, a fast manifold search method, with BRIKARD for complex flexible ligand searching, and with the MELD accelerator of Replica-Exchange Molecular Dynamics simulations for atomistic degrees of freedom. Here we test the method in the Drug Design Data Resource blind Grand Challenge competition. This method was among the best performers in the competition, giving sub-angstrom prediction quality for the majority of the targets.

In Vitro Assessment of the Efficacy of a Macrocyclic Chelator in Reversing Methylmercury Toxicity.

Methylmercury (MeHg) is a highly neurotoxic compound to which human populations are exposed via fish consumption. Once in cells, MeHg actively binds thiols and selenols, interfering with the activity of redox enzymes such as thioredoxin (Trx) and the selenoenzyme thioredoxin reductase (TrxR) which integrate the thioredoxin system. In fact, it has been shown that inhibition of this system by MeHg is a critical step in the unfolding of cell death. Current clinical approaches to mitigate the toxicity of MeHg rely on the use of chelators, such as meso-2,3-dimercaptosuccinic acid (DMSA) which largely replaced British anti-Lewisite or 2,3-dimercapto-1-propanol (BAL) as the prime choice. However, therapeutic efficacy is limited and therefore new therapeutic options are necessary. In this work, we evaluated the efficacy of a macrocyclic chelator, 1-thia-4,7,10,13-tetraazacyclopentadecane ([15]aneN4S), in preventing MeHg toxicity, namely by looking at the effects over relevant molecular targets, i.e., the thioredoxin system, using both purified enzyme solutions and cell experiments with human neuroblastoma cells (SH-SY5Y). Results showed that [15]aneN4S had a similar efficacy to DMSA and BAL in reversing the inhibition of MeHg over purified TrxR and Trx by looking at both the 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) reduction assay and insulin reduction capability. In experiments with cells, none of the chelating agents could reverse the inhibition of TrxR by MeHg, which corroborates the high affinity of MeHg to the selenol in TrxR active site. [15]aneN4S and BAL, unlike DMSA, could prevent inhibition of Trx, which allows the maintenance of downstream functions, although BAL showed higher toxicity to cells. Overall these findings highlight the potential of using [15]aneN4S in the treatment of MeHg poisoning and encourage further studies, namely in vivo.

Paritaprevir, ritonavir, ombitasvir, and dasabuvir treatment in renal transplant patients with hepatitis C virus infection.

BACKGROUND/AIMS: The Social Security System of our country reimburses only paritaprevir, ritonavir, ombitasvir, and dasabuvir (PrOD) regime in treatment-naive patients with hepatitis C regardless of kidney disease. Most of our renal transplant (RT) recipients were treated with PrOD. The aim of the present study was to investigate the efficacy and safety of PrOD in RT patients with hepatitis C virus (HCV) infection in a single center real-life experience. MATERIALS AND METHODS: RT recipients with a post-transplant follow-up of at least 1 year were included in the study. The patients were treated and monitored according to the guidelines. Blood levels of immunosuppressive patients were closely followed up and adjusted. RESULTS: A total of 21 (12 male and nine female) patients were assessed. The age of the patients was 50.8±8.5 years. Ten patients were infected with G1a, 10 patients with G1b, and one patient with G4 HCV. Two patients had compensated cirrhosis. Eighteen patients were treatment-naive, and three were peginterferon+ribavirin-experienced. Sustained virologic response (SVR12) was achieved in all patients. None of the patients discontinued the treatment. Cyclosporine (Csa) and tacrolimus (Tac) doses were reduced to once a day to once a week to maintain the blood level within normal range. The most common adverse effect was anemia in patients receiving ribavirin. Renal functions did not change during the treatment period. CONCLUSION: In this real-life experience, all of the 21 PrOD-treated RT recipients reached SVR12. Tac or Csa serum levels were maintained within the normal range with close monitoring. PrOD regime can be successfully and safely used in RT recipients with HCV infection with close follow-up.

A Cost-Effectiveness Analysis of Shortened Direct-Acting Antiviral Treatment in Genotype 1 Noncirrhotic Treatment-Naive Patients With Chronic Hepatitis C Virus.

BACKGROUND: Direct-acting antivirals are successful in curing hepatitis C virus infection in more than 95% of patients treated for 12 weeks, but they are expensive. Shortened treatment durations, which may have lower cure rates, have been proposed to reduce costs. OBJECTIVES: To evaluate the lifetime cost-effectiveness of different shortened treatment durations for genotype 1 noncirrhotic treatment-naive patients. METHODS: Assuming a UK National Health Service perspective, we used a probabilistic decision tree and Markov model to compare 3 unstratified shortened treatment durations (8, 6, and 4 weeks) against a standard 12-week treatment duration. Patients failing shortened first-line treatment were re-treated with a 12-week treatment regimen. Parameter inputs were taken from published studies. RESULTS: The 8-week treatment duration had an expected incremental net monetary benefit of £7737 (95% confidence interval £3242-£11 819) versus the standard 12-week treatment, per 1000 patients. The 6-week treatment had a positive incremental net monetary benefit, although some uncertainty was observed. The probability that the 8- and 6-week treatments were the most cost-effective was 56% and 25%, respectively, whereas that for the 4-week treatment was 17%. Results were generally robust to sensitivity analyses, including a threshold analysis that showed that the 8-week treatment was the most cost-effective at all drug prices lower than £40 000 per 12-week course. CONCLUSIONS: Shortening treatments licensed for 12 weeks to 8 weeks is cost-effective in genotype 1 noncirrhotic treatment-naive patients. There was considerable uncertainty in the estimates for 6- and 4-week treatments, with some indication that the 6-week treatment may be cost-effective.

Safety assessment in Child A cirrhotic patients treated with Ombitasvir/Paritaprevir/Ritonavir and Dasabuvir with Ribavirin.

BACKGROUND: In our country, the national program for hepatitis C virus treatment with ombitasvir/paritaprevir/ritonavir and dasabuvir was approved for patients with stage four of liver fibrosis and stage three associated with specific comorbidities. Our aim was to analyze the characteristics associated with the presence of adverse events in patients receiving this antiviral regimen, with ribavirin in cirrhotic patients. METHODS: We prospectively studied a cohort of adults with hepatitis C virus infection with Child A cirrhosis, treated for 12 weeks with ombitasvir/paritaprevir/ritonavir/dasabuvir and ribavirin, which have been followed in an infectious diseases tertiary-care hospital. RESULTS: We included 137 adult patients diagnosed with compensated cirrhosis, hepatitis C virus genotype 1b infected, 82 (60%) previously treated. We recorded 201 adverse events in 98 (71.5%) patients, with a median number of events per patient of one. The intensity of adverse events was classified as mild, moderate and severe in 50%, 36% and 14% of cases, respectively. Forty-five (22%) episodes required medical intervention. The most frequently reported adverse events were pruritus 34(35%), asthenia 22(22%) and insomnia 15(15%). The presence of severe adverse events was associated with the presence of comorbidities (p = 0.01, OR : 9.5, 95% CI : 1.2-74.3) and with the presence of associated medication (p = 0.02, OR : 3.9, 95% CI : 1.08-14.2). At the end of current treatment, 136 (99.2%) patients had undetectable viral load. CONCLUSION: We found a high number of adverse events, but most of them were mild or moderate and only one quarter of them required medical intervention. Only severe adverse events were associated with comorbidities and associated medication.

Rigid Peptide Macrocycles from On-Resin Glaser Stapling.

Peptide macrocycles are widely utilized in the development of high affinity ligands, including stapled α-helices. The linear rigidity of a 1,3-diynyl linkage provides an optimal distance (7 Å) between ß-carbons of the i,i+4 amino acid side chains, thus suggesting its utility in stabilizing α-helical structures. Here, we report the development of an on-resin strategy for an intramolecular Glaser reaction between two alkyne-terminated side chains by using copper chloride, an essential bpy-diol ligand, and diisopropylethylamine at room temperature. The efficiency of this ligation was illustrated by the synthesis of (i,i+4)-, (i,i+5)-, (i,i+6)-, and (i,i+7)-stapled BCL-9 α-helical peptides using the unnatural amino acid propargyl serine. Overall, this procedurally simple method relies on inexpensive and widely available reagents to generate low molecular weight 23-, 26-, 29-, and 32-membered peptide macrocycles.

A "Motif-Oriented" Total Synthesis of Nannocystin Ax. Preparation and Biological Assessment of Analogues.

The highly cytotoxic cyclodepsipeptides of the nannocystin family are known to bind to the eukaryotic translation elongation factor 1α (EF-1α). Analysis of the docking pose, as proposed by a previous in silico study, suggested that the trisubstituted alkene moiety and the neighboring methyl ether form a domain that might be closely correlated with biological activity. This hypothesis sponsored a synthetic campaign which was designed to be "motif-oriented": specifically, a sequence of ring closing alkyne metathesis (RCAM) followed by hydroxy-directed trans-hydrostannation of the resulting cycloalkyne was conceived, which allowed this potentially anchoring substructure to be systematically addressed at a late stage. This inherently flexible approach opened access to nannocystin Ax (1) itself as well as to 10 non-natural analogues. While the biological data confirmed the remarkable potency of this class of compounds and showed that the domain in question is indeed an innate part of the pharmacophore, the specific structure/activity relationships can only partly be reconciled with the original in silico docking study; therefore, we conclude that this model needs to be carefully revisited.

Benefit-risk assessment for sofosbuvir/velpatasvir/voxilaprevir based on patient population and hepatitis C virus genotype: U. S. Food and Drug Administration's evaluation.

On July 18, 2017, the U.S. Food and Drug Administration (FDA) approved sofosbuvir/velpatasvir/voxilaprevir (SOF/VEL/VOX) (Vosevi) fixed-dose combination (FDC), an interferon-free, complete regimen for adult patients with chronic hepatitis C virus (HCV) infection without cirrhosis or with compensated cirrhosis (Child-Pugh A) who have: • genotype 1, 2, 3, 4, 5, or 6 infection and have previously been treated with an HCV regimen containing a nonstructural protein 5A (NS5A) inhibitor; and • genotype 1a or 3 infection and have previously been treated with an HCV regimen containing sofosbuvir without an NS5A inhibitor. Approval was based on an acceptable safety profile and high sustained virological response rates 12 weeks after the end of treatment (SVR12) in two phase 3 clinical trials in subjects previously treated with a direct-acting antiviral (DAA) regimen. In POLARIS-1, 96% of SOF/VEL/VOX-treated subjects achieved SVR12. In POLARIS-4, 98% of SOF/VEL/VOX-treated subjects achieved SVR12. A key and challenging question in evaluating the data was determining the contribution of VOX to SOF/VEL and how this differed depending on the genotype and patient population. In this article, we provide our perspective on the issues considered in making these determinations, especially regarding the POLARIS-4 data in subjects who have previously been treated with a chronic HCV regimen containing sofosbuvir without an NS5A inhibitor. Conclusion: We seek to provide context as to why a broad indication was given for NS5A inhibitor-experienced patients (HCV genotypes 1-6) while the indication for NS5A inhibitor- naïve patients was limited to HCV genotypes 1a and 3 only. (Hepatology 2018;67:482-491).

HCV core antigen as an alternate test to HCV RNA for assessment of virologic responses to all-oral, interferon-free treatment in HCV genotype 1 infected patients.

In light of the advances in HCV therapy, simplification of diagnosis confirmation, pre- treatment diagnostic workup and treatment monitoring is required to ensure broad access to interferon-free therapies. HCV core antigen (HCV cAg) testing is rapid, giving results in approximately 60min, and less expensive than HCV RNA methods. While extensive data on the analytical performance of HCV cAg relative to RNA or comparisons in longitudinal studies of patients on interferon based (response guided) therapy there is very limited data on the relative performance of HCV cAg in diagnosis and monitoring patients receiving all-oral interferon free regimens. Furthermore, there is no data in the literature that describes the specificity of HCV cAg in patients with resolved HCV infection i.e. anti-HCV positive/HCV RNA negative. In this study a total of 1201 plasma samples from the 411 HCV genotype 1 subjects with a HCV RNA viral load >50,000IU/ml who enrolled in a clinical trial with ombitasvir, ritonavir-boosted paritaprevir and dasabuvir, with or without ribavirin were retrospectively tested in a blinded fashion with HCV cAg test and results were compared to HCV RNA levels. The specificity of the HCV cAg test was also evaluated in anti-HCV positive but HCV RNA negative samples. Overall concordance between HCV cAg and HCV RNA was 98.6% while concordance in pre-treatment samples was 99.5% (409/411; n=2 HCV RNA pos. with viral loads>3 Mill IU/ml but HCV cAg neg.) and 99.24% in post treatment week 12 samples (391/394; n=2 HCV RNA pos.<25IU/ml and n=1 HCV RNA pos. 2180IU/ml). Specificity in anti-HCV positive HCV RNA negative samples tested was 100%.

Molecular Rearrangement of an Aza-Scorpiand Macrocycle Induced by pH: A Computational Study.

Rearrangements and their control are a hot topic in supramolecular chemistry due to the possibilities that these phenomena open in the design of synthetic receptors and molecular machines. Macrocycle aza-scorpiands constitute an interesting system that can reorganize their spatial structure depending on pH variations or the presence of metal cations. In this study, the relative stabilities of these conformations were predicted computationally by semi-empirical and density functional theory approximations, and the reorganization from closed to open conformations was simulated by using the Monte Carlo multiple minimum method.

Economic and Public Health Impacts of Policies Restricting Access to Hepatitis C Treatment for Medicaid Patients.

BACKGROUND: Interferon-free hepatitis C treatment regimens are effective but very costly. The cost-effectiveness, budget, and public health impacts of current Medicaid treatment policies restricting treatment to patients with advanced disease remain unknown. OBJECTIVES: To evaluate the cost-effectiveness of current Medicaid policies restricting hepatitis C treatment to patients with advanced disease compared with a strategy providing unrestricted access to hepatitis C treatment, assess the budget and public health impact of each strategy, and estimate the feasibility and long-term effects of increased access to treatment for patients with hepatitis C. METHODS: Using a Markov model, we compared two strategies for 45- to 55-year-old Medicaid beneficiaries: 1) Current Practice-only advanced disease is treated before Medicare eligibility and 2) Full Access-both early-stage and advanced disease are treated before Medicare eligibility. Patients could develop progressive fibrosis, cirrhosis, or hepatocellular carcinoma, undergo transplantation, or die each year. Morbidity was reduced after successful treatment. We calculated the incremental cost-effectiveness ratio and compared the costs and public health effects of each strategy from the perspective of Medicare alone as well as the Centers for Medicare & Medicaid Services perspective. We varied model inputs in one-way and probabilistic sensitivity analyses. RESULTS: Full Access was less costly and more effective than Current Practice for all cohorts and perspectives, with differences in cost ranging from $5,369 to $11,960 and in effectiveness from 0.82 to 3.01 quality-adjusted life-years. In a probabilistic sensitivity analysis, Full Access was cost saving in 93% of model iterations. Compared with Current Practice, Full Access averted 5,994 hepatocellular carcinoma cases and 121 liver transplants per 100,000 patients. CONCLUSIONS: Current Medicaid policies restricting hepatitis C treatment to patients with advanced disease are more costly and less effective than unrestricted, full-access strategies. Collaboration between state and federal payers may be needed to realize the full public health impact of recent innovations in hepatitis C treatment.

Cost-effectiveness of direct-acting antiviral regimen ombitasvir/paritaprevir/ritonavir in treatment-naïve and treatment-experienced patients infected with chronic hepatitis C virus genotype 1b in Japan.

OBJECTIVE: This study compared the cost-effectiveness of chronic hepatitis C virus (HCV) genotype 1b (GT1b) therapy ombitasvir/paritaprevir/ritonavir (OBV/PTV/r) vs daclatasvir + asunaprevir (DCV/ASV) and no treatment in patients without cirrhosis. Cost-effectiveness analyses (CEAs) that compared OBV/PTV/r against DCV/ASV and sofosbuvir/ledipasvir (SOF/LDV) in Y93H mutation-negative, GT1b patients with and without cirrhosis were also included. METHODS: A health state transition model was developed to capture the natural history of HCV. A CEA over a lifetime horizon was performed from the perspective of the public healthcare payer in Japan. Costs, health utilities, and rates of disease progression were derived from published studies. Sustained virologic response (SVR) rates of OBV/PTV/r and DCV/ASV were extracted from Japanese clinical trials. Analyses were performed for treatment-naïve and -experienced patients. Alternative scenarios and input parameter uncertainty on the results were tested. RESULTS: OBV/PTV/r exhibited superior clinical outcomes vs comparators. For OBV/PTV/r, DCV/ASV, and no treatment, the lifetime risk of decompensated cirrhosis in treatment-naïve patients without cirrhosis was 0.4%, 1.4%, and 9.2%, and hepatocellular carcinoma was 6.5%, 11.4%, and 49.9%, respectively. Quality-adjusted life years (QALYs) were higher in treatment-naïve and -experienced patients without cirrhosis treated with OBV/PTV/r (16.41 and 16.22) vs DCV/ASV (15.83 and 15.66) or no treatment (11.34 and 11.23). In treatment-naïve and -experienced patients without cirrhosis, the incremental cost-effectiveness ratios (ICERs) of OBV/PTV/r vs DCV/ASV were JPY 1,684,751/QALY and JPY 1,836,596/QALY, respectively; OBV/PTV/r was dominant compared with no treatment. In scenario analysis, including GT1b patients with and without cirrhosis who were Y93H mutation-negative, the ICER of OBV/PTV/r vs DCV/ASV was below the Japanese willingness-to-pay threshold of JPY 5 million/QALY, while the ICER of SOF/LDV vs OBV/PTV/r was above this threshold; thus, OBV/PTV/r was cost-effective. CONCLUSION: OBV/PTV/r appears to be a cost-effective treatment for chronic HCV GT1b infection against DCV/ASV. OBV/PTV/r dominates no treatment in patients without cirrhosis.

Cost-Effectiveness of Genotype 1 Chronic Hepatitis C Virus Treatments in Patients Coinfected with Human Immunodeficiency Virus in the United States.

INTRODUCTION: New treatments for chronic hepatitis C virus (HCV) are highly effective in patients coinfected with human immunodeficiency virus (HIV). This study estimated the cost-effectiveness of treatments for genotype 1 (GT1) HCV in HIV-coinfected patients. METHODS: A Markov model based on HCV natural history was used. The base-case analysis included both treatment-naïve and -experienced patients. Alternatives were ombitasvir/paritaprevir/ritonavir, dasabuvir with or without ribavirin (3D ± R) for 12 or 24 weeks, sofosbuvir plus peginterferon and R (SOF + PR) for 12 weeks, SOF + R for 24 weeks, and no treatment (NT). A subgroup analysis restricted to treatment-naïve, non-cirrhotic patients compared 3D ± R for 12 weeks to SOF plus ledipasvir (LDV) for 12 weeks and NT. Transition probabilities, utilities, and costs were obtained from the published literature. Outcomes were measured over a lifetime horizon and included rates of compensated cirrhosis, decompensated cirrhosis, hepatocellular carcinoma and liver-related death, total costs, life-years, quality-adjusted life-years (QALYs), and the incremental cost-effectiveness ratio (ICER). RESULTS: In the base-case, SOF + R was dominated by both SOF + PR and 3D ± R. Compared to SOF + PR, 3D ± R had an ICER of $45,581. The lifetime rates of liver morbidity and mortality were lower among those treated with 3D ± R compared to SOF + PR, SOF + R, or NT. In the subgroup analysis, 3D ± R was cost-effective compared to NT at a threshold of $50,000 per QALY (ICER $27,496). SOF/LDV had an ICER of $104,489 per QALY gained compared to 3D ± R. CONCLUSION: In the GT1 HCV population coinfected with HIV, 3D ± R was cost-effective compared to NT, SOF + R, and SOF + PR. In the treatment-naïve sub-population, 3D ± R was cost-effective compared to NT and SOF/LDV.