Showing papers by "University of Madras published in 2010"

Emergence of a new antibiotic resistance mechanism in India, Pakistan, and the UK: a molecular, biological, and epidemiological study

Abstract: Summary Background Gram-negative Enterobacteriaceae with resistance to carbapenem conferred by New Delhi metallo-β-lactamase 1 (NDM-1) are potentially a major global health problem. We investigated the prevalence of NDM-1, in multidrug-resistant Enterobacteriaceae in India, Pakistan, and the UK. Methods Enterobacteriaceae isolates were studied from two major centres in India—Chennai (south India), Haryana (north India)—and those referred to the UK's national reference laboratory. Antibiotic susceptibilities were assessed, and the presence of the carbapenem resistance gene bla NDM-1 was established by PCR. Isolates were typed by pulsed-field gel electrophoresis of XbaI-restricted genomic DNA. Plasmids were analysed by S1 nuclease digestion and PCR typing. Case data for UK patients were reviewed for evidence of travel and recent admission to hospitals in India or Pakistan. Findings We identified 44 isolates with NDM-1 in Chennai, 26 in Haryana, 37 in the UK, and 73 in other sites in India and Pakistan. NDM-1 was mostly found among Escherichia coli (36) and Klebsiella pneumoniae (111), which were highly resistant to all antibiotics except to tigecycline and colistin. K pneumoniae isolates from Haryana were clonal but NDM-1 producers from the UK and Chennai were clonally diverse. Most isolates carried the NDM-1 gene on plasmids: those from UK and Chennai were readily transferable whereas those from Haryana were not conjugative. Many of the UK NDM-1 positive patients had travelled to India or Pakistan within the past year, or had links with these countries. Interpretation The potential of NDM-1 to be a worldwide public health problem is great, and co-ordinated international surveillance is needed. Funding European Union, Wellcome Trust, and Wyeth.

Coexistence of blaOXA-23 with blaNDM-1 and armA in clinical isolates of Acinetobacter baumannii from India.

Abstract: Sir, The production of carbapenemases is the most common mechanism responsible for carbapenem resistance in Acinetobacter baumannii. They include metallo-b-lactamases (VIM, IMP and SIM types), which have been sporadically reported in some parts of the world, and acquired OXA-type carbapenemases which have been more frequently identified worldwide and are clustered in three major subfamilies (blaOXA-23, blaOXA-24 and blaOXA-58). 1 High levels of resistance to aminoglycosides due to the production of plasmid-encoded 16S rRNA methylase in Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter spp. have been documented since 2003. The present study was undertaken to determine the mechanism responsible for the carbapenem resistance. Three carbapenem-non-susceptible A. baumannii were isolated from patients in the intensive care unit of a tertiary care hospital in Chennai, India in April 2010. Species identification and antibiotic testing were carried out using an automated machine (VITEK-2). The MICs of carbapenems and aminoglycosides were determined using the CLSI agar dilution method, while tigecycline MICs were determined using the EUCAST broth microdilution method. All the isolates were resistant to all the b-lactams, aminoglycosides and quinolones, and were only susceptible to tigecycline and colistin. Double disc synergy test (DDST) and modified Hodge test (MHT) were used for detection of metallo-b-lactamases and other carbapenemases, respectively. PCR screening was performed for OXA-type carbapenemases (blaOXA-23, -24, -51 and -58-like) and the known metallo-b-lactamase genes. 3 – 5 All three isolates showed positivity for both DDST and MHT, and PCR yielded the products with expected sizes for blaOXA-51, 23-like and blaNDM-1 (Table 1). Sequencing of both blaOXA-23 and blaNDM-1 genes showed 100% identities with previously reported genes. In all three isolates, the blaOXA-23 gene was adjacent to insertion element ISAba1, which provides the promoter required for expression of linked resistance genes; blaOXA-51-like genes were also found in all of the isolates, but were not activated by ISAba1. Conjugation experiments using Escherichia coli J53 as the recipient were unsuccessful. Plasmids of Enterobacteriaceae were not detected among A. baumannii by PCR-based replicon typing. Susceptibility testing showed increased MICs of carbapenems and an unusual phenotype of broad-spectrum high-level resistance to aminoglycosides, including amikacin, gentamicin, netilmicin and tobramycin (MICs.256 mg/L), with susceptibility to tigecycline (MIC1⁄40.5–1 mg/L). PCR screening was performed for 16S rRNA methylase-encoding genes (armA, rmtA, rmtB, rmtC, rmtD and npmA). – 9 All three isolates showed positivity for the armA gene (Table 1). NDM-1 metallo-b-lactamase-mediated resistance to carbapenems in Enterobacteriaceae has been found in many parts of India. However, to our knowledge, this is the first

Differential Inhibitory Effects of the Polyphenol Ellagic Acid on Inflammatory Mediators NF-κB, iNOS, COX-2, TNF-α, and IL-6 in 1,2-Dimethylhydrazine-Induced Rat Colon Carcinogenesis

Abstract: Dietary polyphenols have been found to possess preventive and therapeutic potential against several types of cancers. We investigated the effect of ellagic acid on colon cancer induced by 1,2-dimethylhydrazine in rats. Male Wistar albino rats were divided into four groups. Group 1 served as control, group 2 rats received ellagic acid 60 mg/kg bodyweight/every day p.o. throughout the experiment. Rats from groups 3 and 4 were given subcutaneous (s.c.) injections of 1,2-dimethylhydrazine (20 mg/kg body weight) once a week for the first 15 weeks; rats in group 4 received ellagic acid as in group 2 after the last injection of 1,2-dimethylhydrazine and continued till the end of the experimental period of 30 weeks. 1,2-dimethylhydrazine-induced rats exhibited alterations in cancer tumour markers [5'-nucleotidase (5'-ND), gamma glutamyl transpeptidase (gamma-GT), carcinoembryonic antigen (CEA), alphafetoprotein (AFP) and cathepsin-D (CD)]; pathophysiological markers [alkaline phosphatase (ALP) and lactate dehydrogenase (LDH)] and oral administration of ellagic acid restored the levels of these marker enzymes. Nuclear factor-kappa B (NF-kappaB) actively involved in the regulation of both pro-inflammatory proteins [inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2)] and pro-inflammatory cytokines [tumour necrosis factor (TNF)-alpha and interleukin (IL)-6] and in our study 1,2-dimethylhydrazine-induced group exhibited elevated expressions of all these inflammatory proteins. Ellagic acid administration reduced the expressions of NF-kappaB, COX-2, iNOS, TNF-alpha and IL-6 as confirmed by immunohistochemical, immunoblot and immunofluorescence analysis during 1,2-dimethylhydrazine-induced colon carcinogenesis. In conclusion, ellagic acid demonstrates anti-inflammatory property by iNOS, COX-2, TNF-alpha and IL-6 down-regulation due to inhibition of NF-kappaB and exerts its chemopreventive effect on colon carcinogenesis.

Ameliorative potential of resveratrol on proinflammatory cytokines, hyperglycemia mediated oxidative stress, and pancreatic β-cell dysfunction in streptozotocin- nicotinamide-induced diabetic rats.

Abstract: Chronic exposure of pancreatic beta-cells to supraphysiologic glucose causes adverse beta-cell dysfunction. Thus, the present study was aimed to investigate the hypothesis that oral administration of resveratrol attenuates hyperglycemia, proinflammatory cytokines and antioxidant competence and protects beta-cell ultrastructure in streptozotocin-nicotinamide-induced diabetic rats. Oral administration of resveratrol (5 mg/kg body weight) to diabetic rats for 30 days showed a significant decline in the levels of blood glucose, glycosylated hemoglobin (HbA1c), TNF-alpha, IL-1beta, IL-6, NF-kappaB p65 unit and nitric oxide (NO) with concomitant elevation in plasma insulin. Further, resveratrol treated diabetic rats elicited a notable attenuation in the levels of lipid peroxides, hydroperoxides and protein carbonyls in both plasma and pancreatic tissues. The diminished activities of pancreatic superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx) and glutathione-S-transferase (GST) as well as the decreased levels of plasma ceruloplasmin, vitamin C, vitamin E and reduced glutathione (GSH) in diabetic rats were reverted to near normalcy by resveratrol administration. Based on histological and ultrastructural observations, it is first-time reported that the oral administration of resveratrol may effectively rescue beta-cells from oxidative damage without affecting their function and structural integrity. The results of the present investigation demonstrated that resveratrol exhibits significant antidiabetic potential by attenuating hyperglycemia, enhancing insulin secretion and antioxidant competence in pancreatic beta-cells of diabetic rats.

Toward cell therapy using placenta-derived cells: disease mechanisms, cell biology, preclinical studies, and regulatory aspects at the round table.

Abstract: Among the many cell types that may prove useful to regenerative medicine, mounting evidence suggests that human term placenta-derived cells will join the list of significant contributors. In making new cell therapy-based strategies a clinical reality, it is fundamental that no a priori claims are made regarding which cell source is preferable for a particular therapeutic application. Rather, ongoing comparisons of the potentiality and characteristics of cells from different sources should be made to promote constant improvement in cell therapies, and such comparisons will likely show that individually tailored cells can address disease-specific clinical needs. The principle underlying such an approach is resistance to the notion that comprehensive characterization of any cell type has been achieved, neither in terms of phenotype nor risks-to-benefits ratio. Tailoring cell therapy approaches to specific conditions also requires an understanding of basic disease mechanisms and close collaboration between translational researchers and clinicians, to identify current needs and shortcomings in existing treatments. To this end, the international workshop entitled "Placenta-derived stem cells for treatment of inflammatory diseases: moving toward clinical application" was held in Brescia, Italy, in March 2009, and aimed to harness an understanding of basic inflammatory mechanisms inherent in human diseases with updated findings regarding biological and therapeutic properties of human placenta-derived cells, with particular emphasis on their potential for treating inflammatory diseases. Finally, steps required to allow their future clinical application according to regulatory aspects including good manufacturing practice (GMP) were also considered. In September 2009, the International Placenta Stem Cell Society (IPLASS) was founded to help strengthen the research network in this field.

An Update on Nanomaterials-Based Textiles for Protection and Decontamination

Abstract: Protective clothing currently used against chemical and biological warfare (CBW) agents use activated charcoal impregnated with metal ions, which serve to physically adsorb nerve and blister agents thereby creating disposal hazards after its usage. Nanotechnology is booming in an unprecedented way in creating its impact in various applications such as in catalysis. Metal oxide nanoparticles (MONPs) such as TiO2 and MgO are currently used as potential catalysts for the decontamination of CBW agents. Various synthetic routes adopted for the preparation of MONPs are highlighted in this review. When compared with conventionally-prepared samples, aerogel-prepared samples are more reactive toward toxic chemicals and their ability to degrade CBW is presented here. TiO2 photocatalysts in the presence of UV light and mixed metal oxides are found to be efficient catalysts when compared with individual oxides. The recent trend of exploiting nanoparticles and the high aspect ratio ceramic oxide nanofibers for use in protective clothing, wipe materials, and textiles has been presented. Some of the issues concerning integration of metal oxides into fabrics for sensors are also reviewed in this article.

Modulatory effects of Aloe vera leaf gel extract on oxidative stress in rats treated with streptozotocin.

Abstract: Oxidative stress is currently suggested as a mechanism underlying diabetes and diabetic-related complications. Oxidative stress results from an imbalance between radical-generating and radical-scavenging systems. Many secondary plant metabolites have been reported to possess antioxidant activity. This study was designed to evaluate the potential antioxidative activity of the ethanolic extract from Aloe vera leaf gel in the plasma and pancreas of streptozotocin (STZ)-induced diabetic rats. Glibenclamide was used as a standard reference drug. Oral administration of ethanolic extract at a concentration of 300 mg kg(-1) body weight for 21 days resulted in a significant reduction in fasting blood glucose, thiobarbituric acid reactive substances, hydroperoxides and alpha-tocopherol and significant improvement in ascorbic acid, reduced glutathione and insulin in the plasma of diabetic rats. Similarly, the treatment also resulted in a significant reduction in thiobarbituric acid reactive substances, hydroperoxides, superoxide dismutase, catalase and glutathione peroxidase and significant improvement in reduced glutathione in the pancreas of STZ-induced diabetic rats when compared with untreated diabetic rats. The ethanolic extract appeared to be more effective than glibenclamide in controlling oxidative stress. Thus, this study confirms the ethnopharmacological use of Aloe vera in ameliorating the oxidative stress found in diabetes.

Purification, crystal structure and antimicrobial activity of phenazine-1-carboxamide produced by a growth-promoting biocontrol bacterium, Pseudomonas aeruginosa MML2212

Abstract: Aim: To purify and characterize an antimicrobial compound produced by a biocontrol bacterium, Pseudomonas aeruginosa MML2212, and evaluate its activity against rice pathogens, Rhizoctonia solani and Xanthomonas oryzae pv. oryzae. Methods and Results: Pseudomonas aeruginosa strain MML2212 isolated from the rice rhizosphere with wide-spectrum antimicrobial activity was cultured in Kings’B broth using a fermentor for 36 h. The extracellular metabolites were isolated from the fermented broth using ethyl acetate extraction and purified by two-step silica-gel column chromatography. Three fractions were separated, of which a major compound was obtained in pure state as yellow needles. It was crystallized after dissolving with chloroform followed by slow evaporation. It is odourless with a melting point of 220–222°C. It was soluble in most of the organic solvents and poorly soluble in water. The molecular mass of purified compound was estimated as 223·3 by mass spectral analysis. Further, it was characterized by IR, 1H and 13C NMR spectral analyses. The crystal structure of the compound was elucidated for the first time by X-ray diffraction study and deposited in the Cambridge Crystallographic Data Centre (http://www.ccde.com.ac.uk) with the accession no. CCDC 617344. Conclusion: The crystal compound was undoubtedly identified as phenazine-1-carboxamide (PCN) with the empirical formula of C13H9N3O. Significance and Impact of the Study: As this is the first report on the crystal structure of PCN, it provides additional information to the structural chemistry. Furthermore, the present study reports the antimicrobial activity of purified PCN on major rice pathogens, R. solani and X. oryzae pv. oryzae. Therefore, the PCN can be developed as an ideal agrochemical candidate for the control of both sheath blight and bacterial leaf blight diseases of rice.

Synthesis, characterization, and antimicrobial activities of nickel(II) and copper(II) Schiff-base complexes

Abstract: Ni(II) and Cu(II) metal complexes of simple unsymmetrical Schiff-base ligands derived from salicylaldehyde/5-methylsalicylaldehyde and ethylenediamine or diaminomaleonitrile (DMN) were synthesized. The ligands and their complexes were characterized by elemental analysis, 1H NMR, FT IR, and mass spectroscopy. The electronic spectra of the complexes show d–d transitions in the region at 450–600 nm. Electrochemical studies of the complexes reveal that all mononuclear complexes show a one-electron quasi-reversible reduction wave in the cathodic region. ESR spectra of the mononuclear copper(II) complexes show four lines, characteristic of square-planar geometry, with nuclear hyperfine spin 3/2. The copper(II) complexes show a normal room temperature magnetic moment value μ eff = 1.70–1.74 BM which is close to the spin only value of 1.73 BM. Kinetic studies on the oxidation of pyrocatechol to o-quinone using the copper(II) complexes as catalysts were also carried out. The in vitro antimicrobial activity of the ...

Designed synthesis of Au/Ag/Pd trimetallic nanoparticle-based catalysts for Sonogashira coupling reactions.

Abstract: Pdnp and Pd containing trimetallic nanoparticles (tnp) are synthesized by chemical method with cetyltrimethylammonium bromide as the capping agent. Compositionally, four different tnp are prepared and the particle sizes are characterized by UV-vis spectra, HR-TEM, and XRD measurements. The catalytic activities of Pdnp and tnp are tested using the Sonogashira C-C coupling reaction. The product yield and recyclability of the recovered catalysts are studied. tnp (1:1:1) exhibited better catalysis than Pdnp, which may be due to the concerted electronic effects of the Au-Ag core onto the Pd shell atoms.

Structural, electrochemical, phosphate-hydrolysis, DNA binding and cleavage studies of new macrocyclic binuclear nickel(II) complexes

Abstract: New macrocyclic binuclear nickel(II) complexes have been synthesized by using the bicompartmental mononuclear complex [NiL] [3,30-((1E,7E)-3,6-dioxa-2,7-diazaocta-1,7-diene-1,8-diyl)bis(3-formyl-5-methyl-2-diolato)nickel(II)] with various diamines like 1,2-bis(aminooxy)ethane (L1), 1,2-diamino ethane (L2), 1,3-diamino propane (L3), 1,4-diamino butane (L4), 1,2-diamino benzene (L5), and 1,8-diamino naphthalene (L6). The complexes were characterized by elemental analysis and spectroscopic methods. The molecular structures of the symmetrical binuclear complex [Ni2L1(H2O)4](ClO4)2 (1) and unsymmetrical binuclear complex [Ni2L3(H2O)4](ClO4)2·(H2O)4 (3) were determined by single-crystal X-ray diffraction. The geometry around both the nickel(II) ions in each molecule is a slightly distorted octahedral. The distance between the Ni⋯Ni centers for complex 1 is 3.039 A and for complex 3 is 3.059 A. The influence of the coordination geometry and the ring size of the binucleating ligands on the electronic, redox, phosphate hydrolysis, DNA binding and cleavage properties have been studied. Electrochemical studies of the complexes show two quasi-reversible one electron reduction processes between −0.49 to −1.69 V. The reduction potential of the binuclear Ni(II) complexes shifts towards anodically upon increasing the macrocyclic ring size. The observed first order rate constant values for the hydrolysis of 4-nitrophenyl phosphate reaction are in the range from 8.69 × 10−3 to 1.85 × 10−2 s−1. The complexes show good binding propensity to calf thymus DNA giving binding constant values in the range from 1.4 × 104 to 17.5 × 104 M−1. The absorption, fluorescence and CD spectral data suggests that the complexes are strongly interacting with DNA. These complexes display hydrolytic cleavage of supercoiled pBR322DNA in the presence of H2O2 at pH 7.2 and 37 °C. The hydrolytic cleavage of DNA by the complexes is supported by the evidence from free radical quenching and T4 ligase ligation. The pseudo-Michaelis–Menten kinetic parameters kcat = 1.27 ± 0.4 h−1 and KM = 7.7 × 10−2 M for naphthalene diimine containing macrocyclic binuclear nickel(II) complex, (6) were obtained.

Synthesis and characterization of nanoscale-hydroxyapatite-copper for antimicrobial activity towards bone tissue engineering applications.

Abstract: The bacterial infection is one of the major problems associated with implant and reconstructive surgery of bone. Hence, the aim of this study was to develop biomaterials having antibacterial activity for bone tissue engineering. The hydroxyapatite nanoparticles (nHAp) improve the mechanical properties and incorporate nanotopographic features that mimic the nanostructure of natural bone. We report here for the first time the synthesis and characterization of nHAp and nHAp soaked with copper (nHAp-Cu) using SEM, AFM, FTIR and XRD. The antibacterial activity of nHAp and nHAp-Cu was determined using Gram-positive and Gram-negative bacterial strains. To have accelerated antibacterial activity, polyethylene glycol 400 (PEG 400), a synthetic biodegradable polymer was also added along with nHAp-Cu. The nHAp-Cu/PEG 400 had increased antibacterial activity towards Gram-positive than Gram-negative bacterial strains. The cytotoxicity of nHAp-Cu/PEG 400 was determined using MTT assay with rat primary osteoprogenitor cells and these biomaterials were found to be non-toxic. Hence, based on these results we suggest that the biomaterials containing nHAp-Cu/PEG 400 can be used as antibacterial materials in bone implant and bone regenerative medicine.

Wound healing properties of Indian propolis studied on excision wound-induced rats.

Abstract: Context: In traditional medicine propolis is widely used for the treatment of various ailments including ulcer and wound healing. The phytochemical screening of Indian propolis indicates the presen...