Insecticide susceptibility status in two medically important mosquito vectors,Anopheles gambiae,and Culex quinquefasciatus to three insecticides commonly used in Niger State,Nigeria

High resistance ability on insecticides among major mosquito vectors of diseases in Nigeria is of growing concern for severe control strategies. The objective of this study was to assess the susceptibility status of females Anopheles gambiae and Culex quinquefasciatus complexes mosquitoes to permethrin (21.5 μg/bottle-pyrethroids), propoxur(12.5 μg/bottle-carbamate) and malathion (50 μg/bottle organophosphate), in Niger State, North-Central, Nigeria. Anopheline and Culecine larvae were collected from the larval habitats of the studied sites (Bosso, Katcha, Lapai, and Shiroro) larvae and pupae were identified guided by standard keys and reared to adults in troughs. Insecticide susceptibility bioassays were performed according to the CDC bottle bioassay standard operating procedures on 3 days old, sugar-fed female Anopheles and Culex mosquitoes. Post-exposure mortality after 24hr and knockdown values for KDT₅₀ were calculated. Knock-down at 1-hour insecticide exposure ranged (84–96 %) permethrin, (94–100 %) propoxur and (100 %) malathion for An. gambiae and (86–97 %) permethrin, (92–100 %) propoxur and (96–100 %) malathion for Cx. quinquefasciatus. Mortality, after 24hr post-exposure was 100 % in malathion, indicating the high effect of the insecticide. Tested samples were found potentially resistant to permethrin recorded against mosquitoes collected from all study sites, in two locations of the study sites to propoxur and one location site to malathion. All the tested mosquitoes were found to be potentially resistant to permethrin, however, mosquitoes tested in Katcha and Shiroro resist potentially to propoxur. Except, Culex quinqufasciatus from Lapai that partially resist malathion, all the tested mosquitoes were found to be susceptible to malathion, across the study sites.     

Organic anion transporter 1 (OAT1/SLC22A6) enhances bioluminescence based on d-luciferin–luciferase reaction in living cells by facilitating the intracellular accumulation of d-luciferin

Bioluminescence (BL) imaging based on d-luciferin (d-luc)–luciferase reaction allows noninvasive and real-time monitoring of luciferase-expressing cells. Because BL intensity depends on photons generated through the d-luc–luciferase reaction, an approach to increase intracellular levels of d-luc could improve the detection sensitivity. In the present study, we showed that organic anion transporter 1 (OAT1) is useful, as a d-luc transporter, in boosting the BL intensity in luciferase-expressing cells. Functional screening of several transporters showed that the expression of OAT1 in HEK293?cells stably expressing Pyrearinus termitilluminans luciferase (HEK293/eLuc) markedly enhanced BL intensity in the presence of d-luc. When OAT1 was transiently expressed in HEK293?cells, intracellular accumulation of d-luc was higher than that in control cells, and the specific d-luc uptake mediated by OAT1 was saturable with a Michaelis constant (K_m) of 0.23?μM. The interaction between OAT1 and d-luc was verified using 6-carboxyfluorescein, a typical substrate of OAT1, which showed that d-luc inhibited the uptake of 6-carboxyfluorescein mediated by OAT1. BL intensity was concentration-dependent at steady states in HEK293/eLuc cells stably expressing OAT1, and followed Michaelis–Menten kinetics with an apparent K_m of 0.36?μM. In addition, the enhanced BL was significantly inhibited by OAT1-specific inhibitors. Thus, OAT1-mediated transport of d-luc could be a rate-limiting step in the d-luc–luciferase reaction. Furthermore, we found that expressing OAT1 in HEK293/eLuc cells implanted subcutaneously in mice also significantly increased the BL after intraperitoneal injection of d-luc. Our findings suggest that because OAT1 is capable of transporting d-luc, it can also be used to improve visualization and monitoring of luciferase-expressing cells.     

Cdc42 and its BORG2 and BORG3 effectors control the subcellular localization of septins between actin stress fibers and microtubules

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Lipopolysaccharide induces inducible nitric oxide synthase-dependent podocyte dysfunction via a hypoxia-inducible factor 1α and cell division control protein 42 and Ras-related C3 botulinum toxin substrate 1 pathway

Urine protein loss in immune complex-mediated diseases such as lupus nephritis is associated with podocyte foot process effacement (podocytopathy) but is not always dependent on glomerular immune complex deposition. Several murine and human studies have associated lupus nephritis with inducible nitric oxide synthase (iNOS) expression in what appear to be podocytes. This study was conducted to determine mechanisms of immune-complex-independent and iNOS-dependent podocyte dysfunction. Conditionally immortalized podocytes were cultured with lipopolysaccharide (LPS) and nitric oxide (NO), superoxide (SO), or peroxynitrite donors in the presence or absence of inhibitors of iNOS, reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase or monocyte chemotactic protein 1 (MCP-1), or with sepiapterin to increase coupling of iNOS homodimers. Podocyte NO, SO, and MCP-1 production and nitrotyrosine modifications were determined. The podocytopathy phenotype was determined by measuring cell motility and membrane permeability to albumin. This study determined that NO produced by iNOS is sufficient and necessary to induce podocytopathy. NO probably induces this phenotype via hypoxia-inducible factor 1α and cell division control protein 42 and Ras-related C3 botulinum toxin substrate 1 pathways. With LPS stimulation, neither SO nor peroxynitrite produced by uncoupled iNOS or NADPH oxidase nor MCP-1 was sufficient to induce the full phenotype. This study supports the notion that iNOS may induce autocrine podocyte dysfunction. Thus, targeting iNOS or the pathways of its induction may have therapeutic benefit.     

The activities of mycotoxins derived from Fusarium and related substances in a short-term transformation assay using v-Ha-ras-transfected BALB/3T3 cells (Bhas 42 cells)

Cell transformation assays using BALB/3T3 cells can mimic the two-stage process of chemical carcinogenesis in experimental animals. A short-term transformation assay using v-Ha-ras-transfected BALB/3T3 cells (Bhas 42 cells), which was developed by Ohmori et al. and modified by Asada et al., has been reported to detect both tumor initiators and promoters as transformation initiators and promoters, respectively, with their differences based on their protocols. In this new short-term assay, we examined mycotoxins derived from Fusarium and related substances for the initiation and promotion activities of the transformation. The tested substances included deoxynivalenol, nivalenol, fusarenon-X, T-2 toxin, fumonisin B₁, fumonisin B₂, zearalenone, α-zearalanol, β-zearalanol, α-zearalenol and β-zearalenol. Fumonisin B₁ and T-2 toxin were positive for promoting activity in the assay. Especially, T-2 toxin was active at concentrations as low as 0.001–0.002 μg/mL in the culture medium. From a comparison between the results of this study and published carcinogenicity assay data, it was expected that the Bhas 42 cell transformation assay had a good correlation with the two-stage carcinogenicity tests using experimental animals for estimation of the tumor-promoting activity.     

A mechanistic link between oxidative stress and membrane mediated amyloidogenesis revealed by infrared spectroscopy

The fully developed lesion of Alzheimer's disease is a dense plaque composed of fibrillar amyloid β-proteins (Aβ) with a characteristic and well-ordered β-sheet secondary structure. Because the incipient lesion most likely develops when these proteins are first induced to form β-sheet structure, it is important to understand factors that induced Aβ to adopt this conformation. In this review, we describe the application of polarized attenuated total internal reflection infrared FT-IR spectroscopy for characterizing the conformation, orientation, and rate of accumulation of Aβ on lipid membranes. We also describe the application and yield of linked analysis, whereby multiple spectra are fit simultaneously with component bands that are constrained to share common fitting parameters. Results have shown that membranes promote β-sheet formation under a variety of circumstances that may be significant to the pathogenesis of Alzheimer's disease.     

Peptide histidine valine-42 stimulates gastric acid secretion in man

The effect of peptide histidine valine-42 (PHV-42) on gastric acid secretion was studied in man. PHV-42 was infused into 5 healthy volunteers at a dose of 10 pmol/kg/min. This dose caused a significant stimulation of basal gastric acid and potassium output. there were no significant changes in circulating gastrin throughout the infusion. In 2 subjects with a background of submaximal pentagastrin stimulation, PHV-42 infusion at the same dose did not alter acid secretion in either subject. The previous observation that PHV-42 is found particularly in the stomach and the new finding that it stimulates basal gastric secretion suggest the possibility that PHV-42 could have a role in local control of acid secretion.