Phytotoxic phenols from the needles of Cedrus deodara

During the course of screening for anti-seed germination phytochemicals, the methanol fraction of the Cedrus deodara fresh needles showed potent activity. Bioactivity-guided fractionation led to the isolation of thirty-eight phenolic compounds. Four ones were identified as previously undescribed including (7S,8S)-3-methoxy-9'-acetoxy-3',7-epoxy-8,4'-oxyneoligna-4,9-diol (7), (7S,8R)-dihydro-3'-hydroxy-8-acetoxymethyl-7-(4-hydroxy-3-methoxy-phenyl)-1'-benzofuranpropanol (10), (8S)-4,9,9'-trihydroxy-3,3'-dimethoxy-8,4'-oxyneolignan (11) and (7S,8S)-4,7,9'-trihydroxy-3,3'-dimethoxy-9-acetoxy-8,4'-oxyneolignan (16), respectively. The potential phytotoxic effects of these compounds on the seed germination and root elongation of Arabidopsis thaliana were evaluated by the filter paper assay developed in our laboratory. Bioassay results indicated that caffeic acid (36) displayed most significant inhibitory activities against the seed germination and root elongation of A. thaliana, stronger than those of the commercial herbicides acetochlor and glyphosate at the same concentration of 200 μg/mL. Ditetrahydrofuran lignan (1), dihydrochalcone (25), and eight simple phenols (28, 29, 31, 33-35, 37 and 38) completely inhibited the seed germination of A. thaliana at the concentration of 400 μg/mL, which were as active as acetochlor. Dihydroflavone (21) and the simple phenols 32-34 displayed stronger inhibitory effects on the root elongation of A. thaliana than that of glyphosate. The inhibitory effects of these active compounds on the seed germination and root elongation of Amaranthus tricolor and Lactuca sativa were evaluated as well. The phytotoxic activity of 11, 16, 22, 25, 31, 34, 37 and 38 were detected for the first time. In addition, the structure-activity relationships of the same class of these phytochemicals were discussed.

Contrasting roles of cytochrome P450s in amitraz and chlorfenapyr resistance in the crop pest Tetranychus urticae

The molecular mechanisms of amitraz and chlorfenapyr resistance remain only poorly understood for major agricultural pests and vectors of human diseases. This study focusses on a multi-resistant field strain of the crop pest Tetranychus urticae, which could be readily selected in the laboratory to high levels of amitraz and chlorfenapyr resistance. Toxicity experiments using tralopyril, the active toxophore of chlorfenapyr, suggested decreased activation as a likely mechanism underlying resistance. Starting from the same parental strain, transcriptome profiling revealed that a cluster of detoxifying genes was upregulated after amitraz selection, but unexpectedly downregulated after chlorfenapyr selection. Further functional validation associated the upregulation of CYP392A16 with amitraz metabolism and the downregulation of CYP392D8 with reduced activation of chlorfenapyr to tralopyril. Genetic mapping (QTL analysis by BSA) was conducted in an attempt to unravel the genetic mechanisms of expression variation and resistance. This revealed that chlorfenapyr resistance was associated with a single QTL, while 3 QTLs were uncovered for amitraz resistance. Together with the observed contrasting gene expression patterns, we argue that transcriptional regulators most likely underly the distinct expression profiles associated with resistance, but these await further functional validation.

Teriflunomide shifts the astrocytic bioenergetic profile from oxidative metabolism to glycolysis and attenuates TNFα-induced inflammatory responses

Astrocytes utilize both glycolytic and mitochondrial pathways to power cellular processes that are vital to maintaining normal CNS functions. These cells also mount inflammatory and acute phase reactive programs in response to diverse stimuli. While the metabolic functions of astrocytes under homeostatic conditions are well-studied, the role of cellular bioenergetics in astrocyte reactivity is poorly understood. Teriflunomide exerts immunomodulatory effects in diseases such as multiple sclerosis by metabolically reprogramming lymphocytes and myeloid cells. We hypothesized that teriflunomide would constrain astrocytic inflammatory responses. Purified murine astrocytes were grown under serum-free conditions to prevent acquisition of a spontaneous reactive state. Stimulation with TNFα activated NFκB and increased secretion of Lcn2. TNFα stimulation increased basal respiration, maximal respiration, and ATP production in astrocytes, as assessed by oxygen consumption rate. TNFα also increased glycolytic reserve and glycolytic capacity of astrocytes but did not change the basal glycolytic rate, as assessed by measuring the extracellular acidification rate. TNFα specifically increased mitochondrial ATP production and secretion of Lcn2 required ATP generated by oxidative phosphorylation. Inhibition of dihydroorotate dehydrogenase via teriflunomide transiently increased both oxidative phosphorylation and glycolysis in quiescent astrocytes, but only the increased glycolytic ATP production was sustained over time, resulting in a bias away from mitochondrial ATP production even at doses down to 1 μM. Preconditioning with teriflunomide prevented the TNFα-induced skew toward oxidative phosphorylation, reduced mitochondrial ATP production, and reduced astrocytic inflammatory responses, suggesting that this drug may limit neuroinflammation by acting as a metabolomodulator.

Teriflunomide Preserves Neuronal Activity and Protects Mitochondria in Brain Slices Exposed to Oxidative Stress

Teriflunomide (TFN) limits relapses in relapsing–remitting multiple sclerosis (RRMS) by reducing lymphocytic proliferation through the inhibition of the mitochondrial enzyme dihydroorotate dehydrogenase (DHODH) and the subsequent modulation of de novo pyrimidine synthesis. Alterations of mitochondrial function as a consequence of oxidative stress have been reported during neuroinflammation. Previously, we showed that TFN prevents alterations of mitochondrial motility caused by oxidative stress in peripheral axons. Here, we aimed to validate TFN effects on mitochondria and neuronal activity in hippocampal brain slices, in which cellular distribution and synaptic circuits are largely preserved. TFN effects on metabolism and neuronal activity were investigated by assessing oxygen partial pressure and local field potential in acute slices. Additionally, we imaged mitochondria in brain slices from the transgenic Thy1-CFP/COX8A)S2Lich/J (mitoCFP) mice using two-photon microscopy. Although TFN could not prevent oxidative stress-related depletion of ATP, it preserved oxygen consumption and neuronal activity in CNS tissue during oxidative stress. Furthermore, TFN prevented mitochondrial shortening and fragmentation of puncta-shaped and network mitochondria during oxidative stress. Regarding motility, TFN accentuated the decrease in mitochondrial displacement and increase in speed observed during oxidative stress. Importantly, these effects were not associated with neuronal viability and did not lead to axonal damage. In conclusion, during conditions of oxidative stress, TFN preserves the functionality of neurons and prevents morphological and motility alterations of mitochondria.

Teriflunomide Inhibits JCPyV Infection and Spread in Glial Cells and Choroid Plexus Epithelial Cells

Several classes of immunomodulators are used for treating relapsing-remitting multiple sclerosis (RRMS). Most of these disease-modifying therapies, except teriflunomide, carry the risk of progressive multifocal leukoencephalopathy (PML), a severely debilitating, often fatal virus-induced demyelinating disease. Because teriflunomide has been shown to have antiviral activity against DNA viruses, we investigated whether treatment of cells with teriflunomide inhibits infection and spread of JC polyomavirus (JCPyV), the causative agent of PML. Treatment of choroid plexus epithelial cells and astrocytes with teriflunomide reduced JCPyV infection and spread. We also used droplet digital PCR to quantify JCPyV DNA associated with extracellular vesicles isolated from RRMS patients. We detected JCPyV DNA in all patients with confirmed PML diagnosis (n = 2), and in six natalizumab-treated (n = 12), two teriflunomide-treated (n = 7), and two nonimmunomodulated (n = 2) patients. Of the 21 patients, 12 (57%) had detectable JCPyV in either plasma or serum. CSF was uniformly negative for JCPyV. Isolation of extracellular vesicles did not increase the level of detection of JCPyV DNA versus bulk unprocessed biofluid. Overall, our study demonstrated an effect of teriflunomide inhibiting JCPyV infection and spread in glial and choroid plexus epithelial cells. Larger studies using patient samples are needed to correlate these in vitro findings with patient data.

Efficacy and safety of dihydroorotate dehydrogenase (DHODH) inhibitors "leflunomide" and "teriflunomide" in Covid-19: A narrative review

Dihydroorotate dehydrogenase (DHODH) is rate-limiting enzyme in biosynthesis of pyrimidone which catalyzes the oxidation of dihydro-orotate to orotate. Orotate is utilized in the biosynthesis of uridine-monophosphate. DHODH inhibitors have shown promise as antiviral agent against Cytomegalovirus, Ebola, Influenza, Epstein Barr and Picornavirus. Anti-SARS-CoV-2 action of DHODH inhibitors are also coming up. In this review, we have reviewed the safety and efficacy of approved DHODH inhibitors (leflunomide and teriflunomide) against COVID-19. In target-centered in silico studies, leflunomide showed favorable binding to active site of MPro and spike: ACE2 interface. In artificial-intelligence/machine-learning based studies, leflunomide was among the top 50 ligands targeting spike: ACE2 interaction. Leflunomide is also found to interact with differentially regulated pathways [identified by KEGG (Kyoto Encyclopedia of Genes and Genomes) and reactome pathway analysis of host transcriptome data] in cogena based drug-repurposing studies. Based on GSEA (gene set enrichment analysis), leflunomide was found to target pathways enriched in COVID-19. In vitro, both leflunomide (EC50 41.49 ± 8.8 μmol/L) and teriflunomide (EC50 26 μmol/L) showed SARS-CoV-2 inhibition. In clinical studies, leflunomide showed significant benefit in terms of decreasing the duration of viral shredding, duration of hospital stay and severity of infection. However, no advantage was seen while combining leflunomide and IFN alpha-2a among patients with prolonged post symptomatic viral shredding. Common adverse effects of leflunomide were hyperlipidemia, leucopenia, neutropenia and liver-function alteration. Leflunomide/teriflunomide may serve as an agent of importance to achieve faster virological clearance in COVID-19, however, findings needs to be validated in bigger sized placebo controlled studies.

Tick treatment practices in the field: Access to, knowledge about, and on-farm use of acaricides in Laikipia, Kenya

The prevention of tick-borne diseases is a major challenge for livestock production globally. Tick control strategies include the use of acaricides, but the prescribed strategies do not achieve the desired results in several countries, including Kenya. To better understand how tick treatment practices, contribute to reported tick treatment failures, we assessed livestock owners' acaricide procurement, level of knowledge about acaricides and tick resistance, and how they apply acaricides. We also assessed the quality of the commonly available acaricides. We focused on three livestock systems in Laikipia County, Kenya: two private ranches; one community ranch whose members communally graze their cattle and acquire and apply acaricides; and individual livestock owners in two pastoral communities who individually graze their cattle and acquire and apply acaricides. Through interviews and focus group discussions we assessed; access to acaricides, livestock owners' knowledge, and acaricide use practices; interview data were triangulated with participant observations (n = 107). We analysed nine commonly used acaricides to determine the active ingredient concentration and we determined the concentration of active ingredients in acaricide dilutions collected on farms. All livestock owners had access to and used chemical acaricides for tick control, predominantly amitraz-based. Private ranchers bought one amitraz-based acaricide in bulk directly from the manufacturer, while all other livestock owners bought from agrovet shops. The livestock owners acquired knowledge about acaricides from their own experiences and through experience-based recommendations from peers, but not from the technical information provided by the manufacturers and agrovet shops. All pastoral livestock frequently changed acaricide brand and active ingredient class. A large majority of pastoralists (86%) mixed acaricide brands within and across active ingredient classes; a smaller majority (56%) mixed acaricides with crop pesticides and insecticides. Our lab tests confirmed the content description on the labels bought from agrovet shops. However, on-farm acaricide dilutions from all three livestock systems deviated from the level recommended for effective treatment. If too diluted, the acaricide does not kill ticks, promoting resistance development. If too concentrated, this increases environmental contamination and raises public health concerns. Livestock owners lack a technical understanding of the functioning of acaricides, compromising their use and effectiveness. The widely adopted mixing of acaricides with insecticides and pesticides raises serious health concerns.

Ponesimod Compared With Teriflunomide in Patients With Relapsing Multiple Sclerosis in the Active-Comparator Phase 3 OPTIMUM Study: A Randomized Clinical Trial

Importance

To our knowledge, the Oral Ponesimod Versus Teriflunomide In Relapsing Multiple Sclerosis (OPTIMUM) trial is the first phase 3 study comparing 2 oral disease-modifying therapies for relapsing multiple sclerosis (RMS).

Objective

To compare the efficacy of ponesimod, a selective sphingosine-1-phosphate receptor 1 (S1P1) modulator with teriflunomide, a pyrimidine synthesis inhibitor, approved for the treatment of patients with RMS.

Design, Setting, and Participants

This multicenter, double-blind, active-comparator, superiority randomized clinical trial enrolled patients from April 27, 2015, to May 16, 2019, who were aged 18 to 55 years and had been diagnosed with multiple sclerosis per 2010 McDonald criteria, with a relapsing course from the onset, Expanded Disability Status Scale (EDSS) scores of 0 to 5.5, and recent clinical or magnetic resonance imaging disease activity.

Interventions

Patients were randomized (1:1) to 20 mg of ponesimod or 14 mg of teriflunomide once daily and the placebo for 108 weeks, with a 14-day gradual up-titration of ponesimod starting at 2 mg to mitigate first-dose cardiac effects of S1P1 modulators and a follow-up period of 30 days.

Main Outcomes and Measures

The primary end point was the annualized relapse rate. The secondary end points were the changes in symptom domain of Fatigue Symptom and Impact Questionnaire-Relapsing Multiple Sclerosis (FSIQ-RMS) at week 108, the number of combined unique active lesions per year on magnetic resonance imaging, and time to 12-week and 24-week confirmed disability accumulation. Safety and tolerability were assessed. Exploratory end points included the percentage change in brain volume and no evidence of disease activity (NEDA-3 and NEDA-4) status.

Results

For 1133 patients (567 receiving ponesimod and 566 receiving teriflunomide; median [range], 37.0 [18-55] years; 735 women [64.9%]), the relative rate reduction for ponesimod vs teriflunomide in the annualized relapse rate was 30.5% (0.202 vs 0.290; P < .001); the mean difference in FSIQ-RMS, -3.57 (-0.01 vs 3.56; P < .001); the relative risk reduction in combined unique active lesions per year, 56% (1.405 vs 3.164; P < .001); and the reduction in time to 12-week and 24-week confirmed disability accumulation risk estimates, 17% (10.1% vs 12.4%; P = .29) and 16% (8.1% vs 9.9; P = .37), respectively. Brain volume loss at week 108 was lower by 0.34% (-0.91% vs -1.25%; P < .001); the odds ratio for NEDA-3 achievement was 1.70 (25.0% vs 16.4%; P < .001). Incidence of treatment-emergent adverse events (502 of 565 [88.8%] vs 499 of 566 [88.2%]) and serious treatment-emergent adverse events (49 [8.7%] vs 46 [8.1%]) was similar for both groups. Treatment discontinuations because of adverse events was more common in the ponesimod group (49 of 565 [8.7%] vs 34 of 566 [6.0%]).

Conclusions and Relevance

In this study, ponesimod was superior to teriflunomide on annualized relapse rate reduction, fatigue, magnetic resonance imaging activity, brain volume loss, and no evidence of disease activity status, but not confirmed disability accumulation. The safety profile was in line with the previous safety observations with ponesimod and the known profile of other S1P receptor modulators.

Trial Registration

ClinicalTrials.gov Identifier: NCT02425644.

Characterization and functional analysis of a β-adrenergic-like octopamine receptor from the oriental armyworm (Mythimna separata Walker)

The β-adrenergic-like octopamine receptor (OA2B2), which binds the biogenic amine octopamine, belongs to the class of G-protein coupled receptors and significantly regulates many physiological and behavioral processes in insects. In this study, the putative open reading frame sequence of the MsOA2B2 gene in Mythimna separata was cloned, the full-length complementary DNA was 1191 bp and it encoded a 396-amino acid protein (GenBank accession number MN822800). Orthologous sequence alignment, phylogenetic tree analysis, and protein sequence analysis all showed that the cloned receptor belongs to the OA2B2 protein family. Real-time quantitative polymerase chain reaction of spatial and temporal expression analysis revealed that the MsOAB2 gene was expressed in all developmental stages of M. separata and was most abundant in egg stages and second and fourth instars compared with other developmental stages, while the expression level during the pupal stage was much lower than that at the other stages. Further analysis with sixth instar M. separata larvae showed that the MsOA2B2 gene was expressed 1.81 times higher in the head than in integument and gut tissues. Dietary ingestion of dsMsOA2B2 significantly reduced the messenger RNA level of MsOA2B2 and decreased mortality following amitraz treatment. This study provides both a pharmacological characterization and the gene expression patterns of OA2B2 in M. separata, facilitating further research for insecticides using MsOA2B2 as a target.

A point mutation in the β-adrenergic-like octopamine receptor: possible association with amitraz resistance

BACKGROUND

Amitraz is a unique formamidine-class acaricide/insecticide that effectively controls ticks, mites, and insect pests. However, the recent emergence of amitraz-resistant cattle ticks is a serious problem that requires an urgent solution. A nonsynonymous single nucleotide polymorphism (A181T) leading to an amino acid substitution (I61F) in the β-adrenergic-like (β-AL) octopamine receptor (OAR) of amitraz-resistant southern cattle ticks (Rhipicephalus microplus) (RmβAOR) was proposed to be a cause of the amitraz resistance. However, it remains unclear whether this substitution exerts any functional effect on the action of amitraz. To make this clear, the functional role of this mutation was examined using an orthologous OAR (BmOAR2) from the silkworm (Bombyx mori).

RESULTS

Both amitraz and its metabolite N² -(2,4-dimethylphenyl)-N¹ -methyformamidine (DPMF) elevated intracellular cyclic AMP levels as orthosteric OAR agonists in HEK-293 cells stably expressing BmOAR2. The I45F mutant of BmOAR2 (equivalent to I61F in RmβAOR) was generated and tested for its sensitivity to amitraz and DPMF. The assay result showed that the I45F mutation reduces the potency of DPMF to a level similar to that of the endogenous agonist (R)-OA in wild-type BmOAR2.

CONCLUSION

The amino acid substitution found in the first transmembrane segment of RmβAOR most likely causes target-site insensitivity to DPMF, which might contribute to the resistance of R. microplus to amitraz. This needs to be further confirmed using RmβAOR. © 2020 Society of Chemical Industry.

Long non-coding RNAs as targets for immunosuppressive drug teriflunomide in anti-cancer potential for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common form of liver cancer. Because of the relatively chemotherapy-refractory nature of HCC and significant potential poor hepatic reserve, chemotherapy has not been used consistently in the treatment of HCC. Effective new drugs for HCC are urgently needed. Teriflunomide, which was approved for the treatment of relapsing forms of multiple sclerosis (MS), has been identified as a potential antineoplastic drug. Long noncoding RNAs (lncRNAs) are a novel class of RNA molecules defined as transcripts longer than 200 nucleotides that lack protein coding potential. In this study, we investigated the ability of teriflunomide to act as an antineoplastic drug by examining the effects of teriflunomide treatment on HCC cells. Teriflunomide strongly inhibited the proliferation of HCC cells, induced cell apoptosis and induced cell accumulation in S phases of the cell cycle. LncRNA and mRNA expression profiles of HCC cells treated with teriflunomide compared with controls were performed by using microarray analysis. For comparison, the differentially expressed mRNAs were annotated by using gene ontology (GO) and pathway analyses. The microarray revealed that 2085 lncRNAs and 1561 mRNAs differed in the cells treated with teriflunomide compared with controls. Several GO terms including protein folding, mitochondrial outer membrane, transmembrane receptor protein phosphatase activity, negative regulation of cellular biosynthetic process, DNA packaging complex, and receptor signaling protein activity were enriched in gene lists, suggesting a potential correlation with the action mechanism of teriflunomide. Pathway analysis then demonstrated that JAK-STAT signaling pathway may play important roles in the cell apoptosis induced by teriflunomide. Co-expression network analysis indicated that a number of lncRNAs and mRNAs were included in the co-expression network, and p34710_v4 is the lncRNA with highest degree. Then the mRNAs associated with those differentially expressed lncRNAs were also annotated by using gene ontology (GO) and pathway analyses. The pathway analyses shows that teriflunomide significantly inhibited cell proliferation and promoted cell apoptosis partly by participating in Wnt signaling pathways. These findings suggest that teriflunomide could be a potential drug for chemotherapy and molecularly targeted therapies of HCC.

Novel and potent inhibitors targeting DHODH are broad-spectrum antivirals against RNA viruses including newly-emerged coronavirus SARS-CoV-2

Emerging and re-emerging RNA viruses occasionally cause epidemics and pandemics worldwide, such as the on-going outbreak of the novel coronavirus SARS-CoV-2. Herein, we identified two potent inhibitors of human DHODH, S312 and S416, with favorable drug-likeness and pharmacokinetic profiles, which all showed broad-spectrum antiviral effects against various RNA viruses, including influenza A virus, Zika virus, Ebola virus, and particularly against SARS-CoV-2. Notably, S416 is reported to be the most potent inhibitor so far with an EC₅₀ of 17 nmol/L and an SI value of 10,505.88 in infected cells. Our results are the first to validate that DHODH is an attractive host target through high antiviral efficacy in vivo and low virus replication in DHODH knock-out cells. This work demonstrates that both S312/S416 and old drugs (Leflunomide/Teriflunomide) with dual actions of antiviral and immuno-regulation may have clinical potentials to cure SARS-CoV-2 or other RNA viruses circulating worldwide, no matter such viruses are mutated or not.

Novel and potent inhibitors targeting DHODH are broad-spectrum antivirals against RNA viruses including newly-emerged coronavirus SARS-CoV-2

Emerging and re-emerging RNA viruses occasionally cause epidemics and pandemics worldwide, such as the on-going outbreak of the novel coronavirus SARS-CoV-2. Herein, we identified two potent inhibitors of human DHODH, S312 and S416, with favorable drug-likeness and pharmacokinetic profiles, which all showed broad-spectrum antiviral effects against various RNA viruses, including influenza A virus, Zika virus, Ebola virus, and particularly against SARS-CoV-2. Notably, S416 is reported to be the most potent inhibitor so far with an EC₅₀ of 17 nmol/L and an SI value of 10,505.88 in infected cells. Our results are the first to validate that DHODH is an attractive host target through high antiviral efficacy in vivo and low virus replication in DHODH knock-out cells. This work demonstrates that both S312/S416 and old drugs (Leflunomide/Teriflunomide) with dual actions of antiviral and immuno-regulation may have clinical potentials to cure SARS-CoV-2 or other RNA viruses circulating worldwide, no matter such viruses are mutated or not.

The cost of teriflunomide in the treatment of relapsing-remitting multiple sclerosis

AIMS

Teriflunomide, used globally to treat multiple sclerosis (MS) and widely subsidised for this indication including in Australia and New Zealand, is the main metabolite of leflunomide, an older immune-modulating drug. Leflunomide therefore represents a potential alternative therapy for MS. Teriflunomide is about 50-500 times more expensive than leflunomide, depending on prices in each jurisdiction. I wished to study how this situation arose.

METHODS

Web search to obtain the publicly available minutes of eight international regulatory bodies that have approved teriflunomide for the governments of the US, Canada, Europe, England, Scotland, Australia (TGA and PBS) and New Zealand, and examination of the processes and minuted discussions concerning the metabolic, efficacy, toxicity and cost relationship between teriflunomide and leflunomide.

RESULTS

The relationship between the two drugs and their relative efficacy or toxicity in MS was considered by three of eight agencies (Food and Drug Administration (FDA), European Medicines Agency (EMA) and the Canadian Agency for Drugs and Technology in Health (CADTH)). The remaining agencies accepted teriflunomide applications at face value, assessed cost-effectiveness against contemporaneous drugs used for treating MS, and did not discuss the potential role of leflunomide as a therapy for MS. No agency minuted the implications of the cost difference.

CONCLUSIONS

Efficacy for leflunomide in MS is likely but unproven. The sponsor presented a case for teriflunomide that was within the established procedures for drug agencies in establishing cost-effectiveness, and agencies did not stray from their normal procedures. As a result, an opportunity to decrease the cost of treating MS has been missed. Though off-label use of leflunomide is possible, this is unlikely without a publicly-funded trial to demonstrate non-inferiority with regard to efficacy and safety.

Teriflunomide promotes oligodendroglial differentiation and myelination

BACKGROUND

Multiple sclerosis (MS) is a neuroinflammatory autoimmune disease of the central nervous system (CNS) which in most cases initially presents with episodes of transient functional deficits (relapsing-remitting MS; RRMS) and eventually develops into a secondary progressive form (SPMS). Aside from neuroimmunological activities, MS is also characterized by neurodegenerative and regenerative processes. The latter involve the restoration of myelin sheaths-electrically insulating structures which are the primary targets of autoimmune attacks. Spontaneous endogenous remyelination takes place even in the adult CNS and is primarily mediated by activation, recruitment, and differentiation of resident oligodendroglial precursor cells (OPCs). However, the overall efficiency of remyelination is limited and further declines with disease duration and progression. From a therapeutic standpoint, it is therefore key to understand how oligodendroglial maturation can be modulated pharmacologically. Teriflunomide has been approved as a first-line treatment for RRMS in the USA and the European Union. As the active metabolite of leflunomide, an established disease-modifying anti-rheumatic drug, it mainly acts via an inhibition of de novo pyrimidine synthesis exerting a cytostatic effect on proliferating B and T cells.

METHODS

We investigated teriflunomide-dependent effects on primary rat oligodendroglial homeostasis, proliferation, and differentiation related to cellular processes important for myelin repair hence CNS regeneration in vitro. To this end, several cellular parameters, including specific oligodendroglial maturation markers, in vitro myelination, and p53 family member signaling, were examined by means of gene/protein expression analyses. The rate of myelination was determined using neuron-oligodendrocyte co-cultures.

RESULTS

Low teriflunomide concentrations resulted in cell cycle exit while higher doses led to decreased cell survival. Short-term teriflunomide pulses can efficiently promote oligodendroglial cell differentiation suggesting that young, immature cells could benefit from such stimulation. In vitro myelination can be boosted by means of an early stimulation window with teriflunomide. p73 signaling is functionally involved in promoting OPC differentiation and myelination.

CONCLUSION

Our findings indicate a critical window of opportunity during which regenerative oligodendroglial activities including myelination of CNS axons can be stimulated by teriflunomide.

Inhibition of the Mitochondrial Pyruvate Carrier by Tolylfluanid

Several recent studies have suggested that compounds known as endocrine-disrupting chemicals (EDCs) can promote obesity by serving as ligands for nuclear receptors, including the peroxisome proliferator-activated receptor γ (PPARγ) and the glucocorticoid receptor (GR). Thiazolidinedione insulin sensitizers, which act as ligands for PPARγ, also interact with and regulate the activity of the mitochondrial pyruvate carrier (MPC). We evaluated whether several EDCs might also affect MPC activity. Most of the EDCs evaluated did not acutely affect pyruvate metabolism. However, the putative endocrine disruptors tributyltin (TBT) and tolylfluanid (TF) acutely and markedly suppressed pyruvate metabolism in isolated mitochondria. Using mitochondria isolated from brown adipose tissue in mice with adipocyte-specific deletion of the MPC2 protein, we determined that the effect of TF on pyruvate metabolism required MPC2, whereas TBT did not. We attempted to determine whether the obesogenic effects of TF might involve MPC2 in adipose tissue. However, we were unable to replicate the published effects of TF on weight gain and adipose tissue gene expression in wild-type or fat-specific MPC2 knockout mice. Treatment with TF modestly enhanced adipogenic gene expression in vitro but had no effect on GR activation or phosphorylation in cultured cells. These data suggest that TF may affect mitochondrial pyruvate metabolism via the MPC complex but also call into question whether this compound affects GR activity and is obesogenic in mice.

Amitraz changes NE, DA and 5-HT biosynthesis and metabolism mediated by alterations in estradiol content in CNS of male rats

Amitraz is a formamidine insecticide/acaricide that alters different neurotransmitters levels, among other neurotoxic effects. Oral amitraz exposure (20, 50 and 80 mg/kg bw, 5 days) has been reported to increase serotonin (5-HT), norepinephrine (NE) and dopamine (DA) content and to decrease their metabolites and turnover rates in the male rat brain, particularly in the striatum, prefrontal cortex, and hippocampus. However, the mechanisms by which these alterations are produced are not completely understood. One possibility is that amitraz monoamine oxidase (MAO) inhibition could mediate these effects. Alternatively, it alters serum concentrations of sex steroids that regulate the enzymes responsible for these neurotransmitters synthesis and metabolism. Thus, alterations in sex steroids in the brain could also mediate the observed effects. To test these hypothesis regarding possible mechanisms, we treated male rats with 20, 50 and 80 mg/kg bw for 5 days and then isolated tissue from striatum, prefrontal cortex, and hippocampus. We then measured tissue levels of expression and/or activity of MAO, catechol-O-metyltransferase (COMT), dopamine-β-hydroxylase (DBH), tyrosine hydroxylase (TH) and tryptophan hydroxylase (TRH) as well as estradiol levels in these regions. Our results show that amitraz did not inhibit MAO activity at these doses, but altered MAO, COMT, DBH, TH and TRH gene expression, as well as TH and TRH activity and estradiol levels. The alteration of these enzymes was partially mediated by dysregulation of estradiol levels. Our present results provide new understanding of the mechanisms contributing to the harmful effects of amitraz.

Amitraz and its metabolite differentially activate α- and β-adrenergic-like octopamine receptors

BACKGROUND

Amitraz is a formamidine acaricide and insecticide used to control ticks, mites and fleas. N² -(2,4-Dimethylphenyl)-N¹ -methyformamidine (DPMF), a metabolite of amitraz, is thought to be an active agent that exerts acaricidal and insecticidal effects by acting as an agonist on octopamine receptors. The emergence of cattle ticks resistant to amitraz is a serious problem that requires urgent attention. The objective of this research was to determine which type of octopamine receptor is the primary target of amitraz and thereby understand the molecular mechanisms of action and resistance to amitraz.

RESULTS

Amitraz and DPMF potently activated Bombyx mori α- and β-adrenergic-like octopamine receptors (α- and β-AL OARs) that were stably expressed in HEK-293 cells. Notably, DPMF elevated intracellular cAMP levels, with an EC₅₀ of 79.6 pm in β-AL OARs, the transcripts of which were prevalently and widely localised in B. mori body parts. Furthermore, DPMF elevated the intracellular Ca²⁺ levels, with an EC₅₀ of 1.17 nm in α-AL OARs.

CONCLUSION

Although both amitraz and DPMF acted as OAR agonists, the metabolite DPMF was more potent than amitraz and differentially activated α- and β-AL OARs. The present findings provide a basis for studies to examine the mechanism of amitraz resistance and to develop novel acaricides and insecticides. © 2016 Society of Chemical Industry.

The current status of resistance to alpha-cypermethrin, ivermectin, and amitraz of the cattle tick (Rhipicephalus microplus) in Ecuador

Rhipicephalus microplus is widely distributed in tropical and subtropical areas of the world where livestock is a principal activity with great veterinary and economic importance. In Ecuador, this hematophagous ectoparasite has been observed between 0 and 2600 masl. One of the main tick control measures is the use of acaricides, which have been indiscriminately used worldwide and in Ecuador. In this country, no studies on acaricide resistance in Rhipicephalus microplus have been published. The current study aims to characterise the level of resistance of R. microplus against three main acaricides commonly used in Ecuador i.e. amitraz, alpha-cypermethrin and ivermectin to determine the level and pattern of dose-responses for R. microplus in 12 field populations (farms). The level of acaricide resistance was evaluated using three different bioassays: adult immersion test (AIT), larval package test (LPT) and larval immersion test (LIT), as recommended by the FAO. The predictive dose-responses were analysed by binomial logistics regression of the larval survival rate (resistance). In general, we found resistance of 67% for amitraz; 50% for alpha-cypermethrin and from 25 to 42% for ivermectin in the twelve field populations analysed. Resistance levels were studied in larval and adult bioassays, respectively, which were slightly modified for this study. For larval bioassays based on corrected mortality i.e. high (above 51%), medium (21–50%) and low (11–20%) resistance, percentages less than 10% were considered as susceptible. For the adult test, two resistance levels were used i.e. high (more than 76%) and medium (51 to 75%) resistance. Percentages lower than 50% were considered as susceptible. In this context, for larval bioassays, amitraz showed 21%, 38% and 8% for high, medium and low resistance, respectively. Alpha-cypermethrin presented 8%, 4 and 38% for high, medium and low resistance, respectively. Ivermectin presented 8%, 25% and 8% for high, medium and low resistance, respectively. For adult tests with amitraz 50% and 17% of the field populations showed average and high resistance, with evidences of average resistance to alpha-cypermethrin in 50% of the samples and average resistance against ivermectin in 25% of the farms. No statistical difference amongst the three bioassays was found and acaricide resistance was confirmed by logistic regression analysis; hence resistance (dose-responses) in each field populations differed, depending on the choice of the acaricide, frequent usage, frequency of treatment and farm management. The effective estimated dose needed to eliminate 99% of ticks is higher than dose recommended by the manufacturer. In conclusion, amitraz showed the highest resistance followed by ivermectin and alpha-cypermethrin and reveals differences on resistance in each individual field population. This information is important in order to establish the monitoring of resistance on each farm individually, contributing to the rational use of acaricides included in an integrated control program for R. microplus.

First report of amitraz and cypermethrin resistance in Rhipicephalus sanguineus sensu lato infesting dogs in Mexico

Engorged female Rhipicephalus sanguineus sensu lato (Ixodida: Ixodidae) were collected from dogs in the state of Yucatán, Mexico. Fourteen tick populations were collected from dogs at seven veterinary clinics, four residential homes and three cattle farms. The larval immersion test was used in the progeny of collected adult females to test susceptibility to amitraz and cypermethrin. Dose-mortality regressions, 50% lethal concentrations (LC₅₀ ), confidence intervals and slope were estimated by probit analysis. For amitraz, 12 tick populations (85.7%) were classified as resistant and low inter-population variation in the phenotypic level of resistance was evident [resistance ratios (RRs) at LC₅₀ : 1.0-13.0]. For cypermethrin, 12 tick populations (85.7%) were classified as resistant and substantial inter-population variation in the phenotypic level of resistance was evident (RRs at LC₅₀ : 1.0-104.0). Thus, amitraz resistance in R. sanguineus s.l. is common, but generally occurs at low levels; however, alarmingly high levels of cypermethrin resistance are present in R. sanguineus s.l. populations in dogs in Yucatán, Mexico. The intensive use of both acaricides to control ectoparasites on dogs is likely to lead to more serious resistance problems that may cause high levels of control failure in the future.

Detection of amitraz and malathion resistance in field populations of Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) in Jammu region of India

Detection of resistance levels against amitraz and malathion in Rhipicephalus (Boophilus) microplus collected from four districts of Jammu region (India) was carried out using the adult immersion test. The regression graphs of probit mortality of ticks plotted against log values of concentration of drugs were utilised for the determination of slope of mortality, lethal concentration for 50% (LC₅₀), 95% (LC₉₅) and resistance factor (RF). On the basis of the data generated on variables (mortality, egg mass weight, reproductive index and percentage inhibition of oviposition) the resistance level was categorised as I, II, III and IV. Out of these four districts, resistance to amitraz was detected at level I in Udhampur (RF = 2.81), Jammu (RF = 2.53) and Samba isolates (RF = 2.24) whereas Rajouri isolate was found susceptible (RF = 1.0). Resistance to malathion was detected at level I in Udhampur (RF = 4.01) and Jammu isolates (RF = 1.76) whereas Rajouri (RF = 0.472) and Samba (RF = 0.199) isolates were found susceptible. The data generated on amitraz and malathion resistance status will help in formulating a tick control strategy in the region.

Field efficacy of acaricides against Varroa destructor

Field trials were conducted in Northeast Spain (Aragón) to evaluate the effectiveness of two acaricides against Varroa destructor. These experiments took into account the season of the year, apiary, colony, and developmental state and strength of the colony. The acaricides used were a synthetic (amitraz, Apivar®) and a natural (formulated from Api Life Var®, thymol oil and thymol alcohol) product. The treatments used in the present study reduce high infestations of V. destructor, although they do not eliminate the infestation. Similar efficacies between treatments were found. Nevertheless, the efficacy of a treatment depends on the apiary where applied. Moreover, the detected variability in the apiary and hive poses a challenge to the identification of the significant factors. Therefore, more field studies to assess efficacies in several apiaries are needed to obtain a better understanding of the effects of the applied treatments.

New Data on Vanillin-Based Isothiazolic Insecticide Synergists

By alkylation of vanillin with 4,5-dichloro-3-chloromethylisothiazole the corresponding ether was synthesized. The latter was then reacted with p-toluidine to afford the corresponding azomethine. During the bioassays of synthesized isothiazolic derivatives of vanillin in mixtures with insecticides (imidacloprid and a-cypermethrin) a strong synergetic effect was observed.

Scabies: A clinical update

BACKGROUND

Scabies is a common, yet neglected, skin disease. Scabies occurs across Australia, but most frequently in socioeconomically disadvantaged populations in tropical regions, including in remote Aboriginal and Torres Strait Islander communities. In temperate settings, the disease clusters in institutional care facilities.

OBJECTIVE

The objective of this article is to provide updates on the clinical diagnosis and treatment approaches for scabies in Australia.

DISCUSSION

Clinical examination remains the mainstay of diagnosis, although dermatoscopy is a useful adjunct. Scabies presents with severe itch and a papular rash, with a predilection for the hands, feet and genitalia. The distribution may be more widespread in infants and older people. Secondary bacterial infection is also common in patients with scabies. Crusted scabies is a rare but highly infectious variant. Topical permethrin is highly effective for individual treatment, but less practical for treatment of asymptomatic contacts and control of outbreaks. Oral ivermectin is a safe and effective alternative, and is now listed on the Pharmaceutical Benefits Scheme as a third-line treatment.

[Oral disease-modifying agents in relapsing-remitting multiple sclerosis]

In relapsing-remitting multiple sclerosis, only parenteral immunomodulatory treatments existed for 15 years, until 2010. In recent years, novel disease-modifying agents became available with new mechanisms of action and oral application, which expanded therapeutic options. Thus, when making therapeutic decisions, more and new aspects should be considered, and the daily practice of patient management has been changed due to the different profile of possible side-effects. The authors review the mechanism of action, pharmacokinetics, studies regarding efficacy, side-effects of first- and second line oral disease-modifying treatments and provide practical guide of their everyday usage.

Pharmacological characterization of a tyramine receptor from the southern cattle tick, Rhipicephalus (Boophilus) microplus

The southern cattle tick (Rhipicephalus (Boophilus) microplus) is a hematophagous external parasite that vectors the causative agents of bovine babesiosis or cattle tick fever, Babesia bovis and B. bigemina, and anaplasmosis, Anaplasma marginale. The southern cattle tick is a threat to the livestock industry in many locations throughout the world. Control methods include the use of chemical acaricides including amitraz, a formamidine insecticide, which is proposed to activate octopamine receptors. Previous studies have identified a putative octopamine receptor from the southern cattle tick in Australia and the Americas. Furthermore, this putative octopamine receptor could play a role in acaricide resistance to amitraz. Recently, sequence data indicated that this putative octopamine receptor is probably a type-1 tyramine receptor (TAR1). In this study, the putative TAR1 was heterologously expressed in Chinese hamster ovary (CHO-K1) cells, and the expressed receptor resulted in a 39-fold higher potency for tyramine compared to octopamine. Furthermore, the expressed receptor was strongly antagonized by yohimbine and cyproheptadine, and mildly antagonized by mianserin and phentolamine. Tolazoline and naphazoline had agonistic or modulatory activity against the expressed receptor, as did the amitraz metabolite, BTS-27271; however, this was only observed in the presence of tyramine. The southern cattle tick's tyramine receptor may serve as a target for the development of anti-parasitic compounds, in addition to being a likely target of formamidine insecticides.

Effects of Pesticide Mixtures on Host-Pathogen Dynamics of the Amphibian Chytrid Fungus

Anthropogenic and natural stressors often interact to affect organisms. Amphibian populations are undergoing unprecedented declines and extinctions with pesticides and emerging infectious diseases implicated as causal factors. Although these factors often co-occur, their effects on amphibians are usually examined in isolation. We hypothesized that exposure of larval and metamorphic amphibians to ecologically relevant concentrations of pesticide mixtures would increase their post-metamorphic susceptibility to the fungus Batrachochytrium dendrobatidis (Bd), a pathogen that has contributed to amphibian population declines worldwide. We exposed five anuran species (Pacific treefrog, Pseudacris regilla; spring peeper, Pseudacris crucifer; Cascades frog, Rana cascadae; northern leopard frog, Lithobates pipiens; and western toad, Anaxyrus boreas) from three families to mixtures of four common insecticides (chlorpyrifos, carbaryl, permethrin, and endosulfan) or herbicides (glyphosate, acetochlor, atrazine, and 2,4-D) or a control treatment, either as tadpoles or as newly metamorphic individuals (metamorphs). Subsequently, we exposed animals to Bd or a control inoculate after metamorphosis and compared survival and Bd load. Bd exposure significantly increased mortality in Pacific treefrogs, spring peepers, and western toads, but not in Cascades frogs or northern leopard frogs. However, the effects of pesticide exposure on mortality were negligible, regardless of the timing of exposure. Bd load varied considerably across species; Pacific treefrogs, spring peepers, and western toads had the highest loads, whereas Cascades frogs and northern leopard frogs had the lowest loads. The influence of pesticide exposure on Bd load depended on the amphibian species, timing of pesticide exposure, and the particular pesticide treatment. Our results suggest that exposure to realistic pesticide concentrations has minimal effects on Bd-induced mortality, but can alter Bd load. This result could have broad implications for risk assessment of amphibians; the outcome of exposure to multiple stressors may be unpredictable and can differ between species and life stages.

SNP Analysis Infers that Recombination Is Involved in the Evolution of Amitraz Resistance in Rhipicephalus microplus

Rhipicephalus microplus, better known as the Asiatic cattle tick, is a largely invasive ectoparasite of great economic importance due to the negative effect it has on agricultural livestock on a global scale, particularly cattle. Tick-borne diseases (babesiosis and anaplasmosis) transmitted by R. microplus are alarming as they decrease the quality of livestock health and production. In sub-Saharan Africa, cattle represent a major source of meat and milk, but this region of the world is severely affected by the Rhipicephalus microplus tick. The principal method for tick control is the use of chemical acaricides, notably amitraz, which was implemented in the 1990’s after resistance to other acaricides surfaced. However, the efficiency of chemical control is hindered by an increase in the frequency of mutant resistance alleles to amitraz in tick populations. Presently, the only way to assess amitraz resistance is by means of larval packet tests, but this technique is time-consuming and not particularly cost effective. The main aims of this study were three-fold. First, we attempted to correlate two known SNPs in the octopamine/tyramine (OCT/Tyr) receptor with amitraz resistance in South African field samples of R. microplus. Second, we calculated gametic disequilibrium for these SNPs to determine whether they are randomly associated. Lastly, we conducted a study to assess the evolutionary effects of recombination within the OCT/Tyr receptor. Our results confirmed that the two SNPs are associated with amitraz resistance in the South African tick strain, and that they are in gametic disequilibrium. Additionally, recombination was detected in the OCT/Tyr receptor generating two recombinant haplotypes. These results are of concern to farmers in sub-Saharan Africa, and the emergence of amitraz resistance should be closely monitored in future. Therefore, we present a quick and affordable RFLP based diagnostic technique to assess amitraz resistance in field samples of R. microplus.

Unique biochemical and molecular biological mechanism of synergistic actions of formamidine compounds on selected pyrethroid and neonicotinoid insecticides on the fourth instar larvae of Aedes aegypti (Diptera: Culicidae)

We recently reported that formamidine pesticides such as amitraz and chlordimeform effectively synergize toxic actions of certain pyrethroid and neonicotinoid insecticides in some insect species on the 4th instar larvae of Aedes aegypti. Here we studied the biochemical basis of the synergistic actions of the formamidines in amplifying the toxicity of neonicotinoids and pyrethroids such as dinotefuran and thiamethoxam, as well as deltamethrin-fenvalerate type of pyrethroids. We tested the hypothesis that their synergistic actions are mediated by the octopamine receptor, and that the major consequence of octopamine receptor activation is induction of trehalase to increase glucose levels in the hemolymph. The results show that formamidines cause a significant up-regulation of the octopamine receptor and trehalase mRNA expressions. Furthermore, formamidines significantly elevate levels of free glucose when co-treated with dinotefuran, deltamethrin and fenvalerate, but not with permethrin or fenitrothion, which showed no synergistic toxic effects with formamidines. These results support the conclusion that the main mode of synergism is based on the ability to activate the octopamine receptor, which is particularly effective with insecticides causing hyperexcitation-induced glucose release and consequently leading to quick energy exhaustion.

Synergistic action of octopamine receptor agonists on the activity of selected novel insecticides for control of dengue vector Aedes aegypti (Diptera: Culicidae) mosquito

Studying insecticide resistance in mosquitoes has attracted the attention of many scientists to elucidate the pathways of resistance development and to design novel strategies in order to prevent or minimize the spread and evolution of resistance. Here, we tested the synergistic action of piperonyl butoxide (PBO) and two octopamine receptor (OR) agonists, amitraz (AMZ) and chlordimeform (CDM) on selected novel insecticides to increase their lethal action on the fourth instar larvae of Aedes aegypti L. However, chlorfenapyr was the most toxic insecticide (LC50 = 193, 102, and 48 ng/ml, after 24, 48, and 72 h exposure, respectively) tested. Further, PBO synergized all insecticides and the most toxic combinatorial insecticide was nitenpyram even after 48 and 72 h exposure. In addition, OR agonists significantly synergized most of the selected insecticides especially after 48 and 72 h exposure. The results imply that the synergistic effects of amitraz are a promising approach in increasing the potency of certain insecticides in controlling the dengue vector Ae. aegypti mosquito.

[TERIFLUNOMIDE: A NEW ORAL IMMUNOMODULATING AGENT FOR MULTIPLE SCLEROSIS]

Multiple sclerosis (MS) is the autoimmune, demyelinating, neurodegenerative disorder of the central nervous system (CNS). There are nine drugs available in Hungary reimbursed by the National Health Insurance Fund of Hungary (OEP) to reduce the activity of the disease, from which seven can be used as first line therapies. We have approximately 20 years of experience with the interferon beta-1a/1b and glatiramer-acetate products. Though in case of approximately 30% of the patients using one of the first line drugs, the disease remains active, that we call break-through disease. The reasons for breakthrough disease could be the insufficient adherence and compliance, the appearance of neutralizing antibodies or the high activity of the disease. One of the oral immunomodulating drugs for MS, teriflunomide, was registered in Europe in 2013. Because of the anti-proliferative and anti-inflammatory effect of teriflunomide, it can be used for the reduction of the disease activity in the relapsing-remitting course of MS. The effect of teriflunomide was proved in one Phase II. and four Phase III. (TEMSO, TOWER, TENERE, TOPIC) studies. Teriflunomide 14 mg once daily was able to demonstrate in two consecutive placebo-controlled phase 3 clinical trials that significantly reduces the relapse rate (31.5% and 36.3%) and in both studies significantly reduces the sustained disability progression (29.8% and 31.5%) moreover delays the appearance of the clinically definitive MS in patients with clinically isolated syndrome (CIS). According to the TENERE study there were no significant differences observed between teriflunomide 14 mg and IFNβ-α a s.c. in time to failure and annualized relapse rate but the treatment satisfaction domains of global satisfaction, side-effects and convenience were significantly improved with teriflunomide compared with s.c. IFNβ-α.

Effect of benfluralin on Pinus pinea seedlings mycorrhized with Pisolithus tinctorius and Suillus bellinii--study of plant antioxidant response

In this study, Pinus pinea seedlings mycorrhized with selected ectomycorrhizal fungi (ECMF), Pisolithus tinctorius and Suillus bellinii, were exposed to the herbicide benfluralin. Non-mycorrhized P. pinea seedlings and seedlings mycorrhized with ECMF were transferred to benfluralin-spiked soils at levels of 0.165, 1.65 and 16.5 mg kg(-1). Plant growth and the fungal role on plant antioxidant response were assessed. In the presence of benfluralin, higher plant growth was observed in mycorrhized plants compared to non-mycorrhized plants, but ECMF colonisation and nutrient uptake were affected by the herbicide. Benfluralin showed no effect on lipid peroxidation in P. pinea seedlings. However, seedlings mycorrhized with S. bellinii showed higher levels of lipid peroxidation when compared to non-mycorrhized ones, both in the presence and absence of benfluralin. The increase of lipid peroxidation could be related to seedling growth induced by the fungus and not to benfluralin toxicity. A similar trend was observed in seedlings mycorrhized with P. tinctorius when exposed to higher benfluralin concentrations, suggesting that the antioxidant response to benfluralin is related not only to fungus species, but also to the level of stress applied in the soil. The higher amount of superoxide dismutase activity in P. pinea seedlings tissues exposed to benfluralin could indicate a plant adaptative response to benfluralin toxicity. Catalase activity showed no increase with benfluralin exposure. Pre-established P. tinctorius mycorrhization conferred root protection and enhanced plant growth in benfluralin spiked soil, inferring that P. tinctorius - P. pinea association could advantageous for plant growth in soils contaminated with pesticides.

Teriflunomide and its mechanism of action in multiple sclerosis

Treatment of multiple sclerosis (MS) is challenging: disease-modifying treatments (DMTs) must both limit unwanted immune responses associated with disease initiation and propagation (as T and B lymphocytes are critical cellular mediators in the pathophysiology of relapsing MS), and also have minimal adverse impact on normal protective immune responses. In this review, we summarize key preclinical and clinical data relating to the proposed mechanism of action of the recently approved DMT teriflunomide in MS. Teriflunomide selectively and reversibly inhibits dihydro-orotate dehydrogenase, a key mitochondrial enzyme in the de novo pyrimidine synthesis pathway, leading to a reduction in proliferation of activated T and B lymphocytes without causing cell death. Results from animal experiments modelling the immune activation implicated in MS demonstrate reductions in disease symptoms with teriflunomide treatment, accompanied by reduced central nervous system lymphocyte infiltration, reduced axonal loss, and preserved neurological functioning. In agreement with the results obtained in these model systems, phase 3 clinical trials of teriflunomide in patients with MS have consistently shown that teriflunomide provides a therapeutic benefit, and importantly, does not cause clinical immune suppression. Taken together, these data demonstrate how teriflunomide acts as a selective immune therapy for patients with MS.

Diagnosis of amitraz resistance in Brazilian populations of Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) with larval immersion test

Among the ectoparasites of cattle, Rhipicephalus (Boophilus) microplus (Canestrini) (Acari: Ixodidae) remains a major cause of economic losses to livestock. The chemical control with acaricides is still the most efficient method available to control ticks. The aims of this study were to diagnose resistance to amitraz in 16 tick populations from the States of São Paulo (14) and Paraná (2), using the larval immersion technique (LIT), and evaluate the effect of synergists [piperonyl butoxide (PBO), diethyl maleate (DEM), triphenyl phosphate (TPP)] on amitraz resistant and susceptible strains of cattle tick. Most of the evaluated populations (68.7 %) showed to be resistant to amitraz, with resistance ratios ranging from 2.14 to 132. The results suggest that the test procedure by LIT is sensitive and adequate for detection and monitoring of amitraz resistance in cattle tick. No synergistic effect was observed for the synergists PBO, DEM and TPP, on the amitraz resistant (Poa) strain of cattle tick, indicating that increased detoxification metabolism was not involved in this resistance.

In vitro and in vivo evaluation of cypermethrin, amitraz, and piperonyl butoxide mixtures for the control of resistant Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) in the Mexican tropics

A study was conducted to evaluate the efficacy of cypermethrin, amitraz, and piperonyl butoxide (PBO) mixtures, through in vitro laboratory bioassays and in vivo on-animal efficacy trials, for the control of resistant Rhipicephalus (Boophilus) microplus on cattle in the Mexican tropics. Also, to examine mechanisms of resistance to cypermethrin in this tick population, the frequency of a mutated sodium channel gene (F1550I) was determined using a PCR assay. Results of laboratory bioassays using modified larval packet tests revealed that cypermethrin toxicity was synergized by PBO (from 46.6-57.0% to 83.7-85.0% larval mortality; P<0.05). The cypermethrin and amitraz mixture showed an additive effect (from 46.6-57.0% to 56.0-74.3% larval mortality). Strong synergism was observed with the mixture of cypermethrin+amitraz+PBO and this mixture was the most effective killing resistant tick larvae in vitro (96.7-100% of larval mortality). Tick larvae surviving exposure to cypermethrin or mixtures either with amitraz and PBO in vitro showed 2.9-49.6 higher probability to present the mutated allele than those killed by acaricide treatment (P<0.05). In the in vivo trial, the mixtures containing cypermethrin+PBO (80.6-97.3%), and cypermethrin+amitraz (87.0-89.7%) were more efficacious than cypermethrin alone (76.3-80.5%). The highest level of efficacy was obtained with the mixture of cypermethrin+amitraz+PBO, which yielded >95% control that persisted for 28 days post-treatment against R. microplus infesting cattle when tested under field conditions in the Mexican tropics. Although this mixture is a potentially useful tool to combat pyrethroid resistance, a product based on an acaricide mixture like the one tested in this study has to be used rationally.

Synthesis and characterization of binary and ternary complexes of Co(II), Ni(II), Cu(II) and Zn(II) ions based on 4-aminotoluene-3-sulfonic acid

Salicylidene (4-aminotoluene-3-sulfonic acid) Schiff base ligand H(2)L, and its binary and ternary Co(II), Ni(II), Cu(II) and Zn(II) complexes using 8-hydroxyquinoline (8-HOqu) and 2-aminopyridine (2-Ampy) as secondary ligands have been synthesised and characterized via elemental analysis, spectral data (IR, (1)H NMR, mass and solid reflectance), molar conductance, magnetic moment, TG-DSC measurements and XRPD analysis. Correlation of all spectroscopic data suggest that H(2)L ligand acts as monoanionic terdentate ligand with ONO sites coordinating to the metal ions via deprotonated phenolic-O, azomethine-N and sulfonate-O while 2-Ampy behaves as a neutral monodentate ligand via amino group-N and 8-HOqu behaves as a monoanionic bidentate ligand through the ring-N and deprotonated phenolic-O. The thermal behavior of these complexes shows that the coordinated water molecules were eliminated from the complexes at relatively higher temperatures than the hydrated water and there are two routes in removal of coordinated water molecules. All complexes have mononuclear structure and the tetrahedral, square planar or an octahedral geometry have been proposed. The ligand and its complexes have been screened for their antimicrobial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Salmonella typhimurium, Candida albicans and Aspergillus fumigatus. Among the synthesised compounds, the binary and ternary Ni(II) complexes, (2, 8 and 10) and ternary Zn(II) complex, (12) were found to be very effective against Candida albicans and Bacillus subtilis than all other complexes with MICs of 2 and 8 μg/mL, respectively.

Acaricide, fungicide and drug interactions in honey bees (Apis mellifera)

Background

Chemical analysis shows that honey bees (Apis mellifera) and hive products contain many pesticides derived from various sources. The most abundant pesticides are acaricides applied by beekeepers to control Varroa destructor. Beekeepers also apply antimicrobial drugs to control bacterial and microsporidial diseases. Fungicides may enter the hive when applied to nearby flowering crops. Acaricides, antimicrobial drugs and fungicides are not highly toxic to bees alone, but in combination there is potential for heightened toxicity due to interactive effects.

Methodology/Principal Findings

Laboratory bioassays based on mortality rates in adult worker bees demonstrated interactive effects among acaricides, as well as between acaricides and antimicrobial drugs and between acaricides and fungicides. Toxicity of the acaricide tau-fluvalinate increased in combination with other acaricides and most other compounds tested (15 of 17) while amitraz toxicity was mostly unchanged (1 of 15). The sterol biosynthesis inhibiting (SBI) fungicide prochloraz elevated the toxicity of the acaricides tau-fluvalinate, coumaphos and fenpyroximate, likely through inhibition of detoxicative cytochrome P450 monooxygenase activity. Four other SBI fungicides increased the toxicity of tau-fluvalinate in a dose-dependent manner, although possible evidence of P450 induction was observed at the lowest fungicide doses. Non-transitive interactions between some acaricides were observed. Sublethal amitraz pre-treatment increased the toxicity of the three P450-detoxified acaricides, but amitraz toxicity was not changed by sublethal treatment with the same three acaricides. A two-fold change in the toxicity of tau-fluvalinate was observed between years, suggesting a possible change in the genetic composition of the bees tested.

Conclusions/Significance

Interactions with acaricides in honey bees are similar to drug interactions in other animals in that P450-mediated detoxication appears to play an important role. Evidence of non-transivity, year-to-year variation and induction of detoxication enzymes indicates that pesticide interactions in bees may be as complex as drug interactions in mammals.

Synergistic effect of pasireotide and teriflunomide in carcinoids in vitro

BACKGROUND/AIM

Somatostatin (SST) analogs are mainstay for controlling tumor proliferation and hormone secretion in carcinoid patients. Recent data suggest that extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation may potentiate the anti-tumor effects of SST analogs in carcinoids. Additionally, ERK1/2 phosphorylating agents have been shown to suppress biomarker expression in carcinoids. Thus, Raf-1/MEK/ERK1/2 pathway activating drugs may be synergistic with SST analogs such as pasireotide (SOM230), which may be more effective than others in its class given its elevated receptor affinity and broader binding spectrum. Here, we investigate the effects of SOM230 in combination with teriflunomide (TFN), a Raf-1 activator, in a human carcinoid cell line.

METHODS

Human pancreatic carcinoid cells (BON) were incubated in TFN, SOM230 or a combination. Cell proliferation was measured using a rapid colorimetric assay. Western analysis was performed to analyze expression levels of achaete-scute complex-like 1 (ASCL1), chromogranin A (CgA), phosphorylated and total ERK1/2, and markers for apoptosis.

RESULTS

Combination treatment with SOM230 and TFN reduced cell growth beyond the additive effect of either drug alone. Combination indices (CI) fell below 1, thus quantifiably verifying synergy between both drugs as per the Chou-Talalay CI scale. Combined treatment also reduced ASCL1 and CgA expression beyond the additive effect of either drug alone. Furthermore, it increased levels of phosphorylated ERK1/2, cleaved poly(ADP)-ribose polymerase and caspase-3, and reduced levels of anti-apoptotic biomarkers. Elevated phosphorylated ERK1/2 expression following combination therapy may underlie the synergistic interaction between the two drugs.

CONCLUSION

Since efficacy is achieved at lower doses, combination therapy may palliate symptoms at low toxicity levels. Because each drug has already been evaluated in clinical trials, combinatorial drug trials are warranted.

Developing biologically active compounds having efficient DNA binding and cleavage activity: spectroscopic investigation

A new series of novel o-acetoacetotoluidide derived Schiff base and its metal complexes have been synthesized and structurally characterized. Elemental analysis, magnetic and spectroscopic data suggest that the complexes have octahedral geometry. Binding of these complexes with CT-DNA has been analyzed by absorption spectra, viscosity, cyclicvoltammetry and molecular docking analysis. Detailed analysis reveals that the metal complexes intercalate into the DNA base stack as intercalators. All the metal complexes cleave the pBR322 DNA upon irradiation. Antibacterial and antifungal activities of the ligand and its metal complexes are also explored and it has been observed that the complexes exhibit excellent activity against all types of bacteria and fungi than the ligand.

In vitro toxicity of photodynamic antimicrobial chemotherapy on human keratinocytes proliferation

This in vitro experimental study has been designed to assess the effects of photodynamic antimicrobial chemotherapy (PACT) on human keratinocytes proliferation. Human keratinocytes (HaCaT) monolayers (∼0.5 cm(2)) have been irradiated with 635 nm red laser light with a fluence of 82.5 or 112.5 J/cm(2) in the absence or presence of toluidine (TB). Cell proliferation, monolayer area coverage, cytokeratin 5 (K5) and filaggrin (Fil) expression, and metalloproteinase (MMP)-2 and MMP-9 activity were measured after 72 h from laser irradiation. HaCaT proliferation was reduced by TB staining. Cell exposure to both low- and high-fluence laser irradiation in both presence and absence of TB staining reduced their proliferation and monolayer area extension. Moreover both laser treatments were able to reduce K5 and Fil expression and MMP-9 production in keratinocytes not treated with TB. These data indicate that PACT could exert toxic effects on normal proliferating keratinocytes present around parodontal pockets. The observed reduced cell proliferation along with a reduced production of enzymes involved in wound healing could alter the clinical outcome of the patients treated with PACT.

Pathophysiology of multiple sclerosis and the place of teriflunomide

Significant progress in multiple sclerosis (MS) treatment has been made over the last two decades, including the emergence of disease-modifying therapy (DMT). However, substantial unmet medical need persists and has stimulated the search for new therapeutics. Teriflunomide, one of the several oral DMTs under investigation, is a selective inhibitor of de novo pyrimidine synthesis which exerts a cytostatic effect on proliferating T- and B lymphocytes in the periphery and thus has both antiproliferative and anti-inflammatory properties. Anti-inflammatory effects have been demonstrated in rodent MS models, with reductions in macrophage and B- and T-cell infiltration in the central nervous system and preservation of myelin and oligodendrocytes. Delays in disease onset, reductions in disease relapses and improvements in clinical symptoms were also observed. A proof-of-concept clinical trial in patients with relapsing MS demonstrated that teriflunomide significantly reduced magnetic resonance imaging (MRI) activity and improved clinical endpoints, with both effects maintained with longer-term treatment. Additional studies have shown that teriflunomide can be safely added to beta interferon or glatiramer acetate therapy, with some evidence of additional improvements in MRI disease burden and clinical signs. Teriflunomide has an acceptable and manageable safety and tolerability profile. A large clinical programme is underway to further elucidate the role of teriflunomide in the treatment of MS.

Assessing the effects of acetochlor on soil fungal communities by DGGE and clone library analysis

We assessed the potential eco-toxicological risks of the herbicide acetochlor on fungal communities in the microcosm of black soil using 28S rRNA gene-PCR-DGGE and clone library analysis. The acetochlor was applied to black soil at four concentrations (0-control, 50, 150, and 250 mg/kg). The DGGE fingerprint patterns indicated that acetochlor stimulated fungal communities at day 7 after application, after which there was a suppression effect. The fungal communities in acetochlor-treated soil gradually became more like that of the control during the 60-day experimental period. Diversity indices in the 50 and 150 mg/kg acetochlor treatments changed more rapidly than in the 250 mg/kg acetochlor treatment. The cluster analysis indicated a significant change in fungal community structure after application of acetochlor. The impacts were markedly greater in the 150 and 250 mg/kg acetochlor treatments compared with the 50 mg/kg acetochlor treatment. Sequencing of clones showed that acetochlor application resulted in an increase in pathogenic and non-cultivatable fungal populations, which could increase the risk of plant disease outbreaks.

Dihydroorotate dehydrogenase is required for N-(4-hydroxyphenyl)retinamide-induced reactive oxygen species production and apoptosis

The synthetic retinoid N-(4-hydroxyphenyl)retinamide (4HPR) exhibits anticancer activity in vivo and triggers apoptosis in transformed cells in vitro. Thus, apoptosis induction is acknowledged as a mechanistic underpinning for 4HPR's cancer preventive and therapeutic effects. Apoptosis induction by 4HPR is routinely preceded by and dependent on the production of reactive oxygen species (ROS) in transformed cells. Very little evidence exists, outside the possible involvement of the mitochondrial electron transport chain or the plasma membrane NADPH oxidase complex, that would pinpoint the predominant site of 4HPR-induced ROS production in transformed cells. Here, we investigated the role of dihydroorotate dehydrogenase (DHODH; an enzyme associated with the mitochondrial electron transport chain and required for de novo pyrimidine synthesis) in 4HPR-induced ROS production and attendant apoptosis in transformed skin and prostate epithelial cells. In premalignant prostate epithelial cells and malignant cutaneous keratinocytes the suppression of DHODH activity by the chemical inhibitor teriflunomide or the reduction in DHODH protein expression by RNA interference markedly reduced 4HPR-induced ROS generation and apoptosis. Conversely, colon carcinoma cells that lacked DHODH expression were markedly resistant to the pro-oxidant and cytotoxic effects of 4HPR. Together, these results strongly implicate DHODH in 4HPR-induced ROS production and apoptosis.

Effect of the herbicide glyphosate on glyphosate-tolerant maize rhizobacterial communities: a comparison with pre-emergency applied herbicide consisting of a combination of acetochlor and terbuthylazine

A comparison was made of the effect of glyphosate (RoundupPlus), a post-emergency applied herbicide, and of HarnessGTZ, a pre-emergency applied herbicide, on the rhizobacterial communities of genetically modified NK603 glyphosate-tolerant maize. The potential effect was monitored by direct amplification, cloning and sequencing of soil DNA encoding 16S rRNA, rhizobacterial DNA hybridization to commercially available genome-wide microarrays from the soil bacterium Streptomyces coelicolor, and high-throughput DNA pyrosequencing of the bacterial DNA coding for 16S rRNA hypervariable V6 region. The results obtained strongly suggest that both herbicides do in fact affect the maize rhizobacterial communities, glyphosate being, to a great extent, the environmentally less aggressive herbicide.

C-fin: a cultured frog tadpole tail fin biopsy approach for detection of thyroid hormone-disrupting chemicals

There is a need for the development of a rapid method for identifying chemicals that disrupt thyroid hormone (TH) action while maintaining complex tissue structure and biological variation. Moreover, no assay to date allows a simultaneous screen of an individual's response to multiple chemicals. A cultured tail fin biopsy or C-fin assay was developed using Rana catesbeiana tadpoles. Multiple tail fin biopsies were taken per tadpole, cultured in serum-free medium, and then each biopsy was exposed to a different treatment condition. The effects of known disruptors of TH action were evaluated in the C-fin assay. Chemical exposure was performed +/- 10 nM 3,3',5-triiodothyronine and real-time quantitative polymerase chain reaction (QPCR) of two TH-responsive transcripts, TH receptor beta (TRbeta) and the Rana larval keratin type I (RLKI), was performed. Within 48 h of exposure to Triac (1-100 nM), roscovitine (0.6-60 microM), or genistein (1-100 microM), perturbations in TH signaling were detected. Tetrabromobisphenol A (TBBPA) (10-1,000 nM) showed no effect. Acetochlor (1-100 nM) elicited a modest effect on the TH-dependent induction of TRbeta transcript. These data reveal that a direct tissue effect may not be critical for TBBPA and acetochlor to disrupt TH action previously observed in intact tadpoles.