Browsing by Author "Sanjeev K Singh"

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Design of novel bioadhesive chitosan film loaded with bimetallic gold-silver nanoparticles for antibiofilm and wound healing activity
(Institute of Physics, 2023) Chandrashekhar Singh; Abhishesh Kumar Mehata; Vikas; Punit Tiwari; Aseem Setia; Ankit Kumar Malik; Sanjeev K Singh; Ragini Tilak; Madaswamy S Muthu
Microbial infections and antibiotic resistance are among the leading causes of morbidity and mortality worldwide. The bimetallic chitosan (CS)-capped gold-silver nanoparticles (CS-AuAg-NPs) were prepared by the seeded growth synthesis technique. The nanoparticles were optimized for particle size (PS), zeta potential (ZP) and antibacterial activity by Box-Behnken design at three levels and three factors. The developed CS-AuAg-NPs were polydispersed with mean hydrodynamic PS in the range of 55 - 289 nm and ZP ranges from +8.53 mV to +38.6 mV. The optimized CS-AuAg-NPs found to have a minimum inhibitory concentration and minimal bactericidal concentration of 1.625 ± 0.68 and 3.25 ± 0.74 µg ml−1 towards multidrug resistant (MDR) Staphylococcus aureus ATCC 25923 (MDR AT) and 3.25 ± 0.93 and 3.25 ± 0.86 µg ml−1 towards MDR S. aureus clinical isolate MDR1695 (MDR CI) strain, respectively. The CS-AuAg-NPs were much more effective against MDR AT and MDR CI compared to clindamycin standard. The live/dead assay of clinical isolates strain demonstrated significant reduction of bacterial cells ∼67.52 folds compared to control group in 12 h. The hemolysis study suggested that CS-AuAg-NPs were non-hemolytic and safer for application in the wound. Furthermore, CS-AuAg-NPs were distributed in the CS film, which showed 87% wound recovery after 7 d in mice model. Hence, we concluded that CS-AuAg-NPs was safer and more effective against MDR bacteria and capable of skin regeneration in the infected wound. © 2023 IOP Publishing Ltd
Effect of agonist and antagonist on the in vitro contractility of inflamed vermiform appendix
(Journal of Clinical and Diagnostic Research, 2017) Phani Bhushan Singh; Pushpakant Tiwary; Sanjeev K Singh; Ratna Pandey; Atanu Roy; Amrita Ghosh Kar; Somprakas Basu; Anil Kumar Tiwari
Introduction: Appendicitis poses a great health problem worldwide. Previous studies demonstrated structural damage to neuronal network and interstitial cell of Cajal in appendicitis. Above observations suggest for the alterations in appendicular motility/contractility in appendicitis. But the mechanisms involved in mediating the contractility in inflamed vermiform appendix is not known till date. Aim: The present in vitro study was performed to find out the mechanisms responsible for contractility in the inflamed human vermiform appendix. Materials and Methods: Contractions of the longitudinal muscle strips of inflamed appendix were recorded in vitro at 37±0.5°C. Control contractions were recorded for 30 min after an initial tension of 0.5 gram. Initially dose-response experiments of agonists (acetylcholine, serotonin and histamine) were performed separately and the dose that produced maximum contraction was determined with each agonist. This maximal dose of agonist was used to elicit contractions in next series of experiments before and after pre-treatment with appropriate antagonists like atropine, ondansetron (5-HT3 antagonist) and chlorpheniramine maleate respectively. Results: Acetylcholine (ACh) and serotonin (5-HT) elicited maximum amplitude of contraction at 10 µM and 1 µM concentration respectively. These contractions were significantly blocked by prior exposure of muscle strips with atropine (100 µM) and ondansetron (10 µM). Histamine produced very low amplitude of contractions in comparison to ACh or 5-HT and did not exhibit dose-response relations. The histamine induced contractions were blocked by H1 antagonist chlorpheniramine maleate (100 µM). Conclusion: The observations suggested that the contractility of longitudinal muscle strips of inflamed vermiform appendix in human beings was predominantly mediated by muscarinic and serotonergic (5-HT3) mechanisms, whereas, histaminergic mechanisms played a minor role in mediating the contractility. © 2017, Journal of Clinical and Diagnostic Research. All rights reserved.
Vasosensory responses elicited by Indian red scorpion venom last longer than capsaicin-induced responses
(2008) Sanjeev K Singh; Shripad B Deshpande
The present study was conducted to compare the time-related cardiorespiratory changes occurring after the injection of Mesobuthus tamulus (BT; 1 mg/kg) venom and capsaicin (1.2 ng/kg) in the peripheral end of femoral artery in urethane anaesthetised rats. Blood pressure (BP), electrocardiogram (for heart rate; HR) and respiratory movements were recorded for 60 min after venom/capsaicin intra-arterially. Minute ventilation (MV) was computed by using appropriate calibrations. After intraarterial injection of BT venom, there was immediate (within 2 sec) increase in respiratory rate (RR) and MV which reached to 40% within 30 sec, followed by a 40% decrease in RR without any change in MV. Further, there was sustained increase in RR (50%) and MV (65%) up to 60 min. The BP began to increase at 40 sec, peaking at 5 min (50%) and remained above the initial level up to 60 min. The bradycardiac response began after 5 min which peaked (50% of the initial) at 25 min and remained at that level up to 60 min. In capsai in treated group, there was immediate hyperventilatory (increase in RR and MV) changes within 2 sec which returned to the initial level within 2 min and remained at that level up to 60 min. The capsaicin-induced hypotensive response began within 5 sec which returned to the initial level by 5 min and remained at that level throughout. Capsaicin did not produce any change in HR. These observations suggest that intraarterialinjection of BT venom produces prolonged cardiorespiratory alterations as compared to the capsaicin-induced responses.