Concurrent use of two dual-combination drenches containing monepantel/abamectin and oxfendazole/levamisole in sheep: effect on marker residues 21 and 28 days after administration.

AIMS: To determine the concentration, in comparison with the maximum residue limit (MRL), of anthelmintic marker residues in the target tissues (liver and fat) of sheep treated concurrently with two oral drenches, one containing monepantel and abamectin and the other oxfendazole and levamisole. METHODS: On day 0 of the study, 12 sheep (six male and six female; 8-9-months old) were dosed according to individual body weight determined the day prior. Zolvix Plus (dual-active oral drench containing 25 g/L monepantel and 2 g/L abamectin) was administered to all animals prior to administration of Scanda (dual-active oral drench containing 80 g/L levamisole hydrochloride and 45.3 g/L oxfendazole). Six sheep (three male and three female) were slaughtered 21 and 28 days after treatment and renal fat and liver samples were collected.Using validated methods, analyses for monepantel sulfone, abamectin, levamisole and oxfendazole (expressed as total fenbendazole sulfone following conversion of the combined concentrations of oxfendazole, fenbendazole and fenbendazole sulfone) were performed on liver samples while renal fat specimens were analysed for monepantel sulfone and abamectin residues only. Detected concentrations were compared to the established MRL in sheep for each analyte determined by the Ministry for Primary Industries. RESULTS: All residues detected in samples of liver and fat collected 21 and 28 days after treatment were below the MRL for each analyte. All liver samples collected on day 21 had detectable monepantel sulfone (mean 232 (min 110, max 388) µg/kg) and oxfendazole (mean 98.7 (min 51.3, max 165) µg/kg) residues below the MRL (5,000 and 500 µg/kg, respectively). Monepantel sulfone (mean 644 (min 242, max 1,119) µg/kg; MRL 7,000 µg/kg) residues were detected in 6/6 renal fat samples. Levamisole residues were detected in 3/6 livers (mean 40.0 (min 14.3, max 78.3) µg/kg; MRL 100 µg/kg), and abamectin residues in 1/6 livers (0.795 µg/kg; MRL 25 µg/kg) and 2/6 fat samples, (mean 0.987 (min 0.514, max 1.46) µg/kg; MRL 50 µg/kg) 21 days after treatment. CONCLUSION AND CLINICAL RELEVANCE: These results suggest that concurrent administration of Zolvix Plus and Scanda to sheep is unlikely to result in an extended residue profile for any of the active ingredients, with all analytes measured being under the approved New Zealand MRL 21 days after treatment. This work was not completed in line with guidance for establishing official residue profiles, nor is it sufficient to propose a new withholding period.

Lipocalin-2 protects the brain during inflammatory conditions.

Sepsis is a prevalent health issue that can lead to central nervous system (CNS) inflammation with long-term behavioral and cognitive alterations. Using unbiased proteomic profiling of over 100 different cytokines, we found that Lipocalin-2 (LCN2) was the most substantially elevated protein in the CNS after peripheral administration of lipopolysaccharide (LPS). To determine whether the high level of LCN2 in the CNS is protective or deleterious, we challenged Lcn2-/- mice with peripheral LPS and determined effects on behavior and neuroinflammation. At a time corresponding to peak LCN2 induction in wild-type (WT) mice injected with LPS, Lcn2-/- mice challenged with LPS had exacerbated levels of pro-inflammatory cytokines and exhibited significantly worsened behavioral phenotypes. To determine the extent of global inflammatory changes dependent upon LCN2, we performed an RNAseq transcriptomic analysis. Compared with WT mice injected with LPS, Lcn2-/- mice injected with LPS had unique transcriptional profiles and significantly elevated levels of multiple pro-inflammatory molecules. Several LCN2-dependent pathways were revealed with this analysis including, cytokine and chemokine signaling, nucleotide-binding oligomerization domain-like receptor signaling and Janus kinase-signal transducer and activator of transcription signaling. These findings demonstrate that LCN2 serves as a potent protective factor in the CNS in response to systemic inflammation and may be a potential candidate for limiting sepsis-related CNS sequelae.

Effective control of a suspected cyromazine-resistant strain of Lucilia cuprina using commercial spray-on formulations of cyromazine or dicyclanil.

OBJECTIVE: To demonstrate the protection of Merino sheep from flystrike by Lucilia cuprina with cyromazine or dicyclanil in an implant study and in the field. METHODS: In the implant study, sheep were treated with cyromazine or dicyclanil and implanted with 1st-stage larvae from a newly isolated field strain of L. cuprina (CYR-LS) or a reference strain (DZR50), then assessed over 3 days and compared with the implants on untreated control sheep. In the field study, weaner lambs were treated with cyromazine or dicyclanil and monitored weekly for flystrike over 18 weeks of grazing on the same farm from which the L. cuprina were isolated. RESULTS: Implant study: cyromazine (6%) provided effective protection against CYR-LS and DZR50 L. cuprina for a minimum of 13 and 10 weeks, respectively. Dicyclanil (5%) provided at least 18 weeks' protection against both strains. Field study: only 1 of 386 lambs in the cyromazine-treated group was struck in the first 14 weeks of the trial. No strikes occurred in the 198 sheep treated with dicyclanil (5%). Rainfall, temperature and flytrap data indicated consistent fly pressure during the study. CONCLUSIONS: Based on the results of these studies, there was no evidence of reduced susceptibility to cyromazine or dicyclanil and the periods of protection of sheep against L. cuprina were unaffected and consistent with the registered label claims.

Efficacy of monepantel and anthelmintic combinations against multiple-resistant Haemonchus contortus in sheep, including characterisation of the nematode isolate.

Three experiments defined the resistance profile of a population of Haemonchus contortus, which was shown to express multiple resistances to the benzimidazole, levamisole, macrocyclic lactone and salicylanilide anthelmintic classes when given as a registered combination. Study 1 was a faecal egg count reduction (FECR) test and the efficacies for the anthelmintics were monepantel, 100%; abamectin+levamisole+oxfendazole, 40.0%; and abamectin+levamisole+oxfendazole+naphthalophos, 100%. No larvae were recovered from the post-treatment cultures for monepantel or the 4-way treatment, and for the 3-way treatment the culture was 100% Haemonchus spp. Efficacies in Study 2 were calculated from mean post-mortem nematode burdens of H. contortus and were levamisole+oxfendazole, 3.1%; abamectin+levamisole+oxfendazole, 5.0%; ivermectin, 0.4%; moxidectin, 28.4% and closantel, 70.2%. Study 3 was also a FECR test that resulted in efficacies of 100% for monepantel and 83.0% for a formulated 4-way combination of abamectin+levamisole+albendazole+closantel. Larvae recovered from the post-treatment culture for the combination-treated sheep were all Haemonchus spp. Multi-resistant parasites such as examined in these studies are a continuing challenge to be managed by farmers and their advisors. Control programs must be planned and well-managed, and should include on-farm testing for anthelmintic resistance, monitoring of nematode burdens (by FEC and larval culture) to determine appropriate treatment times and the management of pastures to reduce the overall parasite challenge. This should be in balance with the generation, use and maintenance of drug-susceptible nematode populations in refugia.

Nupafant, a PAF-antagonist prototype for suppression of ventricular fibrillation without liability for QT prolongation?

BACKGROUND AND PURPOSE: PAF antagonists inhibit ischaemia-induced ventricular fibrillation (VF) in animals. However, unfavourable ancillary actions (on QT interval and coronary flow) have been reported with the PAF antagonist, BN-50739. If these are class actions, they would preclude development of PAF antagonists as novel anti-VF drugs. Our purpose was to examine this proposition using the hitherto untested PAF antagonist, nupafant. EXPERIMENTAL APPROACH: Two rat heart preparations (Langendorff and 'dual coronary' perfusion) were used to assay nupafant's effects on ischaemia-induced VF, coronary flow and QT interval, and to test for the site-selectivity necessary if any effects on VF are caused by PAF antagonism. KEY RESULTS: Global (whole-heart) delivery of 10 microM nupafant, reduced the incidence of ischaemia-induced VF and widened QT interval without affecting coronary flow. Importantly, lower concentrations (0.1 and 1 microM) had no effect on VF, yet widened QT almost identically to 10 microM nupafant. When nupafant was delivered selectively to (and entrapped within) the involved region it partially protected against VF (P<0.05). This occurred without change in QT interval. Selective nupafant delivery to the uninvolved region was without effect. CONCLUSIONS AND IMPLICATIONS: Nupafant protects against ischaemia-induced VF primarily by site-selective actions in the ischaemic region but, unlike BN-50739, the effect is unrelated to its QT widening action, and is not compromised by any effect on coronary flow. This establishes proof of concept that VF suppression by PAF antagonism need not invariably be associated with QT prolongation or vasodilatation, justifying further development of this drug class.

Will a physician assistant improve your dermatology practice?

A physician assistant (PA) is a licensed health care professional and dependent practitioner. The profession began in the 1960s and accredited programs now number 110 nationwide. PAs practice in every specialty, including dermatology, and their clinical duties vary tremendously. Research has shown enhanced productivity and increased patient satisfaction in practices using PAs. Most third-party payers cover services provided by PAs, making them ideally suited in this era of increasing managed care.

Information systems disaster planning in the patient care environment.

This article focuses on preparedness planning for the nurse manager in the event of a network failure of a hospital clinical information system. The evolution of health care information systems is discussed. A 4-step preparation model is discussed to aid the nurse manager in preparing for network failure.

Protection against ventricular fibrillation by the PAF antagonist, BN-50739, involves an ischaemia-selective mechanism.

The platelet-activating factor (PAF) antagonist BN-50739 can suppress certain cardiac arrhythmias. PAF is released from ischaemic myocardium and may contribute to initiation of ischaemia-induced ventricular fibrillation (VF). In this study we characterised the action of BN-50739 on left regional ischaemia-induced VF and examined whether effects are mediated within the ischaemic territory, or are nonspecific. In rat isolated Langendorff perfused hearts (n = 12/group), 10 microM BN-50739 reduced the incidence of ischaemia-induced VF from 75 to 17% (p<0.05). This was accompanied by QT widening and an increase in coronary flow. Heart rate and PR interval were not affected by the drug. In separate studies, isolated rat hearts were perfused by using a dual-lumen tube that allows independent delivery of solution to the left and right coronary beds. Successful regional localisation of drug delivery was confirmed by observing, before ischaemia, a regionally selective increase in coronary flow (p<0.05), measured by using two in-line flow meters. Protection against ischaemia-induced VF (p<0.05) was achieved by pretreatment with BN-50739, delivered selectively and entrapped within the involved region, but not when the drug was delivered to the uninvolved region. In conclusion, BN-50739 protects against ischaemia-induced VF by eliciting a pharmacologic action in the involved (ischaemic) myocardium. This supports the hypothesis that BN-50739 suppresses an arrhythmogenic effect of endogenous PAF released within the ischaemic tissue.

Utilization of orotate as a pyrimidine source by Salmonella typhimurium and Escherichia coli requires the dicarboxylate transport protein encoded by dctA.

Mutants deficient in orotate utilization (initially termed out mutants) were isolated by selection for resistance to 5-fluoroorotate (FOA), and the mutations of 12 independently obtained isolates were found to map at 79 to 80 min on the Salmonella typhimurium chromosome. A gene complementing the mutations was cloned and sequenced and found to possess extensive sequence identity to characterized genes for C4-dicarboxylate transport (dctA) in Rhizobium species and to the sequence inferred to be the dctA gene of Escherichia coli. The mutants were unable to utilize succinate, malate, or fumarate as sole carbon source, an expected phenotype of dctA mutants, and introduction of the cloned DNA resulted in restoration of both C4-dicarboxylate and orotate utilization. Further, succinate was found to compete with orotate for entry into the cell. The S. typhimurium dctA gene encodes a highly hydrophobic polypeptide of 45.4 kDa, and the polypeptide was found to be enriched in the membrane fraction of minicells harboring a dctA+ plasmid. The DNA immediately upstream of the deduced -35 region contains a putative cyclic AMP-cyclic AMP receptor protein complex binding site, thus affording an explanation for the more effective utilization of orotate with glycerol than with glucose as carbon source. The E. coli dctA gene was cloned from a lambda vector and shown to complement C4-dicarboxylate and orotate utilization in FOA-resistant mutants of both E. coli and S. typhimurium. The accumulated results demonstrate that the dctA gene product, in addition to transporting C4-dicarboxylates, mediates the transport of orotate, a cyclic monocarboxylate.

Dual control by purines and pyrimidines of the expression of the pyrD gene of Salmonella typhimurium.

Expression of the Salmonella typhimurium pyrD gene was found to be repressed two-fold when cells were grown in the presence of hypoxanthine. Purine-mediated repression was evident for reporter plasmids containing pyrD-lacZ transcriptional or translational fusions, indicating that regulation was being exercised at the level of transcriptional initiation. In a strain harbouring a purR6::Tn10 mutation inactivating the purine regulon repressor (PurR), expression of pyrD was not repressed by hypoxanthine. Gel retardation experiments provided evidence that PurR binds to a PUR box centered 27 base pairs upstream of the -35 region of the pyrD promoter. Site-directed mutagenesis was used to decrease the similarity of the putative PUR box to the consensus sequence; each mutation eliminated binding of PurR to the mutated DNA in vitro and abolished repression by hypoxanthine in purR+ cells in vivo. Regulation by pyrimidines was unaffected by either of the two PUR box mutations, showing that purine and pyrimidine control of pyrD expression can operate independently.

Nucleotide pool-sensitive selection of the transcriptional start site in vivo at the Salmonella typhimurium pyrC and pyrD promoters.

Expression of the Salmonella typhimurium pyrC and pyrD genes is regulated in response to fluctuations in the intracellular CTP/GTP pool ratio. The repressive mechanism involves the formation of a stable secondary structure (hairpin) at the 5' ends of the transcripts that precludes translational initiation by sequestering sequences required for ribosomal binding. The potential for hairpin formation is controlled through CTP/GTP-modulated selection of the transcriptional start site. Substitution of nucleotides in the region of transcriptional initiation has revealed that selection of the transcriptional start point in vivo depends on the nucleotide context within the initiation region and the nucleoside triphosphate pool ratios. For maximal control in response to CTP/GTP pool ratios, the wild-type CCGG start site motif appears to be optimal. Changing the -35 region in the pyrC promoter to the consensus sequence, or replacement of the pyrC promoter with the lac promoter from Escherichia coli, has served to illustrate that the ability of the RNA polymerase to select the initiation site in response to the intracellular nucleoside triphosphate pools is not promoter specific but is determined by the kinetic properties of the initiating RNA polymerase during the formation of the first phosphodiester bond of the transcript.

Comparative morphological and histochemical aspects of selected arteries in the chicken and rat.

Morphologic and histochemical characteristics of selected portions of normal arteries from two species known to differ in susceptibility to vascular disease were examined. Arteries were classified as predominantly elastic, muscular or complex. Species differences in the structural organization of the abdominal aortic segment were observed. Arterial mucopoly-saccharides were stained more intensely in the tunica intima and media of chicken vessels than within those of the rat, and tended to be most concentrated in proximity of the internal elastic membrane. Histochemical procedures for the demonstration of enzymatic activity revealed inter-and intraspecies variations in vascular metabolism. Pronounced differences in reaction intensity for hydroxybutyrate dehydrogenase and malic enzyme, affecting chicken and rat coronary arteries, were noted. In contrast, theses vessels displayed only minimal activity for acid phosphatase. Marked endothelial deposition of alkaline phosphatase reaction products in the arteries of the chicken was demonstrated, while this enzyme's activity in the vessels of the rat was restricted to the tunica adventitia. The implications of these structural and histochemical factors with regard to vascular susceptibility to disease were discussed.