Effect of rotational use of insecticides on pyrethroids resistance in Helicoverpa armigera (Lep.: Noctuidae)

Abstract:  To investigate fluctuation in susceptibility to insecticides in the field, natural populations of Helicoverpa armigera were collected from the same field in the region of Multan, Pakistan in 2002 and 2003. The populations were examined against pyrethroids (viz. cypermethrin, esfenvalerate and fenpropathrin) and new insecticides (viz. spinosad, abamectin and indoxacarb). In 2002, the resistance ratio (RR) of cypermethrin and esfenvalerate was significantly higher than fenpropahrin compared with susceptible population. The susceptibility to cypermethrin, esfenvalerate and fenpropathrin increased significantly in 2003; however, the RR for cypermethrin was about half the RR (38) of esfenvalerate (101) and fenpropathrin (89). The toxicity of spinosad, abamectin and indoxacarb was identical in both years. In the field experiments, abamectin was more effective than other compounds tested whereas fenpropathrin, cypermethrin and esfenvalerate had similar toxicity. These results might have important implications in resistance management and suggest that the rotational use of spinosad, abamectin and indoxacarb could help to avoid the development of multiple resistant in H. armigera .     

Effect of Cinnamon Oil on Quorum Sensing-Controlled Virulence Factors and Biofilm Formation in Pseudomonas aeruginosa

Quorum sensing (QS) is a system of stimuli and responses in bacterial cells governed by their population density, through which they regulate genes that control virulence factors and biofilm formation. Despite considerable research on QS and the discovery of new antibiotics, QS-controlled biofilm formation by microorganisms in clinical settings has remained a problem because of nascent drug resistance, which requires screening of diverse compounds for anti-QS activities. Cinnamon is a dietary phytochemical that is traditionally used to remedy digestive problems and assorted contagions, which suggests that cinnamon might contain chemicals that can hinder the QS process. To test this hypothesis, the anti-QS activity of cinnamon oil against P. aeruginosa was tested, measured by the inhibition of biofilm formation and other QS-associated phenomena, including virulence factors such as pyocyanin, rhamnolipid, protease, alginate production, and swarming activity. To this end, multiple microscopy analyses, including light, scanning electron and confocal microscopy, revealed the ability of cinnamon oil to inhibit P. aeruginosa PAO1 biofilms and their accompanying extracellular polymeric substances. This work is the first to demonstrate that cinnamon oil can influence various QS-based phenomena in P. aeruginosa PAO1, including biofilm formation.     

Analysis of sugar composition and pesticides using HPLC and GC–MS techniques in honey samples collected from Saudi Arabian markets

Honey is a complex foodstuff found in nature which is used without any processing. Honey has been in use in medicine as well as raw food since ancient times. Essentially, it is a blend of sugars especially fructose and glucose. The objectives of the study were to determine major sugar composition as well as pesticides contamination in honey samples. Further, Hydroxy-methyl-furfuraldehyde (HMF) level was also determined to ascertain the freshness of honey samples. A total of 14 samples were collected from local market and tested for fructose, glucose, sucrose, HMF and organochlorine pesticides using HPLC and GC–MS techniques respectively. The total sugars in the 14 honey samples were found ranging between 50.26 and 74.74 g/100 g of honey. The chromatographic results showed the presence of the sugars like fructose and glucose in all honey samples. The honey sample SH–11 was found to contain the highest amount of fructose (40.63%). On the other hand, the lowest amount of fructose with 29.08% was observed in SH–7. The HPLC analysis also revealed the presence of sucrose in two samples but under the permissible limit. The average ratio of fructose to glucose in these honey samples was 1.3. None of the sample has ratio below 1.0 indicating lesser chances for honey to crystallize on storage. Out of 14 honey samples, 13 samples were found negative for the presence of any of the 63 pesticides tested. Only sample No. 13, was found to contain 15.95 ppb hexachlorobenzene per kilogram of honey. The HMF was not detected in four samples but in remaining samples it was well below the maximum permissible limit. No pesticide and sugar adulteration was observed in any of the honey samples. The honeys collected from Saudi Arabian markets were found to confirm the standards set by the regional and international standardization organization, the GSO and Codex Alimentarius Commission respectively.     

Chronic unpredictable stress exacerbates 7,12-dimethylbenz (a) anthracene induced hepatotoxicity and nephrotoxicity in Swiss albino mice

Oxidative stress, a pervasive condition induced by stress has been implicated and recognized to be a prominent feature of various pathological states including cancer and their progression. The present study sought to validate the effectiveness of chronic unpredictable stress (CUS) on hepatic and renal toxicity in terms of alterations of various in vivo biochemical parameters, oxidative stress markers and the extent of DNA damage in Swiss albino mice. Animals were randomized into different groups based on their exposure to CUS alone, 7,12-dimethylbenz (a) anthracene (DMBA) alone (topical), DMBA-12-O-tetradecanoylphorbol-13-acetate (TPA) (topical), and exposure to CUS prior to DMBA or DMBA-TPA treatment, and sacrificed after 16 weeks of treatment. Prior exposure to CUS increased the pro-oxidant effect of carcinogen as depicted by significantly compromised levels of antioxidants; superoxide dismutase, catalase, glutathione-S-transferase, glutathione reductase, reduced glutathione in hepatic and renal tissues accompanied by a significant elevation of thiobarbituric acid reactive species (TBARS) as compared to DMBA alone or DMBA-TPA treatments. Loss of structural integrity at the cellular level due to stress-induced oxidative damage was demonstrated by significant increases in the hepatic levels of intracellular marker enzymes such as glutamate oxaloacetate transaminase, glutamate pyruvate transaminase and alkaline phosphatase, and significantly reduced levels of uric acid in kidney tissues. The results of DNA damage studies further positively correlated with all the above biochemical measurements. Thus, exposure to physical or psychological stress may significantly enhance the hepatotoxic and nephrotoxic potential of carcinogens through enhanced oxidative stress even if the treatment is topical.     

Expression and characterization of alpha-(1,4)-glucan branching enzyme Rv1326c of Mycobacterium tuberculosis H37Rv

Glycogen branching enzyme (GlgB, EC 2.4.1.18) catalyzes the third step of glycogen biosynthesis by the cleavage of an alpha-(1,4)-glucosidic linkage and subsequent transfer of cleaved oligosaccharide to form a new alpha-(1,6)-branch. A single glgB gene Rv1326c is present in Mycobacterium tuberculosis. The predicted amino acid sequence of GlgB of M. tuberculosis has all the conserved regions of alpha-amylase family proteins. The overall amino acid identity to other GlgBs ranges from 48.5 to 99%. The glgB gene of M. tuberculosis was cloned and expressed in Escherichia coli. The recombinant protein was purified to homogeneity using metal affinity and ion exchange chromatography. The recombinant protein is a monomer as evidenced by gel filtration chromatography, is active as an enzyme, and uses amylose as the substrate. Enzyme activity was optimal at pH 7.0, 30 degrees C and divalent cations such as Zn2+ and Cu2+ inhibited activity. CD spectroscopy, proteolytic cleavage and mass spectroscopy analyses revealed that cysteine residues of GlgB form structural disulfide bond(s), which allow the protein to exist in two different redox-dependent conformational states. These conformations have different surface hydrophobicities as evidenced by ANS-fluorescence of oxidized and reduced GlgB. Although the conformational change did not affect the branching enzyme activity, the change in surface hydrophobicity could influence the interaction or dissociation of different cellular proteins with GlgB in response to different physiological states.     

Activation of Toll-Like Receptor 2 Prevents Suppression of T-Cell Interferon γ Production by Modulating p38/Extracellular Signal-Regulated Kinase Pathways following Alcohol and Burn Injury

Recent studies indicate that toll-like receptors (TLRs) are expressed on T cells and that these receptors directly or indirectly activate the adaptive immune system. We have shown previously that acute alcohol/ethanol (EtOH) intoxication combined with burn injury suppresses mesenteric lymph node (MLN) T-cell interleukin-2 (IL-2) and interferon γ (IFN-γ) production. We examined whether direct stimulation of T cells with TLR2, 4, 5 and 7 agonists modulates CD3-mediated T-cell IL-2/IFN-γ release following EtOH and burn injury. Male mice were gavaged with EtOH (2.9 gm/kg) 4 h prior to receiving an ~12.5% total body surface area sham or full-thickness burn injury. Animals were killed on d 1 after injury and T cells were purified from MLN and spleens. T cells were cultured with plate-bound anti-CD3 in the presence or absence of various TLR ligands. Although TLR2, 4 and 5 agonists potentiate anti-CD3-dependent IFN-γ by T cells, the TLR2 agonist alone induced IFN-γ production independent of CD3 stimulation. Furthermore, T cells were treated with inhibitors of myeloid differentiation primary response protein 88 (MyD88), TIR domain-containing adaptor protein (TIRAP), p38 and/or extracellular signal-regulated kinase (ERK) to determine the mechanism by which TLR2 mediates IL-2/IFN-γ production. IL-2 was not influenced by TLR agonists. MyD88 and TIRAP inhibitory peptides dose-dependently diminished the ability of T cells to release IFN-γ. p38 and ERK inhibitors also abolished TLR2-mediated T-cell IFN-γ. Together, our findings suggest that TLR2 directly modulates T-cell IFN-γ production following EtOH and burn injury, independent of antigen-presenting cells. Furthermore, we demonstrated that MyD88/TIRAP-dependent p38/ERK activation is critical to TLR2-mediated T-cell IFN-γ release following EtOH and burn injury.     

Steroidogenic alterations and adrenal androgen excess in PCOS

BACKGROUND: This cross-sectional study was undertaken to improve our understanding of the steroidogenic alterations leading to adrenal hyperandrogenism in polycystic ovarian syndrome (PCOS). METHODS: Two-hundred and thirty-four women with clinical and biochemical features suggestive of PCOS underwent metabolic and hormonal evaluation. We used the androstenedione/DHEAS ratio as a surrogate for the level of ovarian 3betaHSD activity. We then selected the 90th percentile for the ratio in those with elevated DHEAS (>9 micromol/l) as the cut-off level beyond which excess DHEAS production will be minimized by excess ovarian 3betaHSD activity. This cut-off level was at a ratio of 1.5 and all PCOS women were then divided into two groups, the higher (>1.5) being the group with excess ovarian 3betaHSD activity. We hypothesized that women with a high ratio would be unlikely to have DHEAS excess due to the rapid conversion of DHEA to androstenedione. Those with a low ratio (concordant ovarian and adrenal steroidogenesis) could then either have high DHEAS or normal DHEAS, depending on whether CYP17 activity was higher or lower respectively. RESULTS: Insulin resistance was found to be associated with decreased CYP17 activity while irregular cycles and neuroendocrine dysfunction were determined to be associated with higher ovarian 3betaHSD activity. CONCLUSION: Adrenal androgen excess in PCOS seems to be related to insulin sensitivity as well as decreased activity of 3betaHSD, the latter being preferentially present in those women with regular cycles or without neuroendocrine dysfunction.     

Species Spectrum of Nontuberculous Mycobacteria Isolated from Clinical Specimens in Kuwait

Specific identification of mycobacteria is of clinical relevance since treatment varies according to the Mycobacterium species causing infection. All mycobacterial isolates are currently identified as M. tuberculosis (MTB) or nontuberculous mycobacteria (NTM) based on p-nitro-α-acetylamino-β-hydroxypropiophenone (NAP) test, and the species spectrum of NTM-causing infections in Kuwait remains unknown. This study identified all NTM strains isolated in Kuwait from 1 October 2003 to 31 March 2004 to the species level. The mycobacteria were cultured from various clinical specimens using the BACTEC 460 TB system and NAP test was performed to differentiate MTB from NTM strains. The INNO-LiPA MYCOBACTERIA v2 assay (LiPA) was used for species-specific identification of NTM strains and some randomly selected MTB strains. The LiPA results for selected isolates were confirmed by DNA sequencing of the 16S-23S internal transcribed spacer region. A total of 325 isolates of Mycobacterium species originating from 305 individual patients were recovered during the study period, with 307 and 18 isolates identified as MTB and NTM, respectively. The LiPA correctly identified all 18 MTB isolates analyzed. Seven different NTM species were identified among 18 NTM isolates originating from 14 patients, with M. fortuitum causing the majority of NTM infections in Kuwait. One patient was infected with two NTM species. Rapid species-specific identification of NTM may help with appropriate treatment regimens for proper patient management. The DNA sequencing data reported in this study are deposited in EMBL under accession numbers AM709724 to AM709731.     

Investigating molecular evolutionary forces and phylogenetic relationships among melatonin precursor-encoding genes of different plant species

Molecular Biology Reports - A total of 53 plant species accessions from different geographic regions, including four melatonin precursor-coding genes obtained from Arachis hypogaea (ASMT1, 2, 3 and...