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Aditya K Kar,1,2 Amrita Singh,1,2 Nitesh Dhiman,1,2 Mahaveer P Purohit,1,2 Pankaj Jagdale,3 Mohan Kamthan,4 Dhirendra Singh,3 Mahadeo Kumar,3 Debabrata Ghosh,2,5 Satyakam Patnaik1,2 1Water Analysis Laboratory, Nanomaterial Toxicology Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Lucknow 226001, Uttar Pradesh, India; 2Academy of Scientific and Innovative Research (AcSIR), CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Lucknow 226001, Uttar Pradesh, India; 3Regulatory Toxicology, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Lucknow 226001, Uttar Pradesh, India; 4CITAR, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Lucknow 226001, Uttar Pradesh, India; 5Immunotoxicology Laboratory, Food Drug and Chemical Toxicology Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Lucknow 226001, Uttar Pradesh, IndiaCorrespondence: Satyakam PatnaikWater Analysis Laboratory, Nanomaterial Toxicology Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Vishvigyan Bhawan, 31, Mahatma Gandhi Marg, Lucknow 226001, Uttar Pradesh, IndiaTel +91 5222627586, Ext. 205Fax +91 5222628227Email satyakampatnaik@yahoo.comIntroduction: An ideal wound dressing material needs to be predisposed with desirable attributes like anti-infective effect, skin hydration balance, adequate porosity and elasticity, high mechanical strength, low wound surface adherence, and enhanced tissue regeneration capability. In this work, we have synthesized hydrogel-based wound patches having antibacterial silver nanoparticles and antioxidant epigallocatechin gallate (EGCG) and showed fast wound closure through their synergistic interaction without any inherent toxicity.Methods and results: Wound patches were synthesized from modified guar gum polymer and assessed to determine accelerated wound healing. The modified polymer beget chemical-free in-situ synthesis of monodispersed silver NPs (∼12 nm), an antimicrobial agent, besides lending ionic surface charges. EGCG impregnated during ionotropic gelation process amplified the efficacy of wound patches that possess apt tensile strength, porosity, and swellability for absorbing wound exudates. Further, in vitro studies endorsed them as non-cytotoxic and the post agent effect following exposure to the patch showed an unbiased response to E coli K12 and B. subtilis. In vivo study using sub-cutaneous wounds in Wistar rats validated its accelerated healing properties when compared to a commercially available wound dressing material (skin graft; Neuskin-F®) through better wound contraction, promoted collagen deposition and enhanced vascularization of wound region by modulating growth factors and inflammatory cytokines.Conclusion: Synthesized wound patches showed all the desired attributes of a clinically effective dressing material and the results were validated in various in vitro and in vivo assays.Keywords: aminated guar gum, hydrogels, silver nanoparticles, epigallocatechin gallate, wound healing

Three imipenem-resistant mutants were obtained from a clinical isolate (C152) of Shigella dysenteriae by selection with increasing concentrations of imipenem. Resistance to imipenem was associated with resistance to several other beta-lactam antibiotics. The penicillin-binding protein (PBP) patterns of the resistant and the wild-type strains were comparable. The permeability of the outer membrane proteins (OMPs) of the most resistant mutant, IM16, was lower than that of the parent strain C152 when imipenem and arabinose were used as test solutes. This mutant had lower levels of both the major OMPs of M(r) 43,000 and 38,000. There were also differences in the patterns of lipopolysaccharide (LPS) of the mutants and the wild-type strain. The mutant IM16 had less short-chain LPS than the parent C152. Increasing imipenem resistance was also associated with a concomitant decrease in the level of 2-keto-3-deoxyoctonate, a component of the core region of LPS. [ABSTRACT FROM AUTHOR]