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Virk, Antar Puneet,Sharma, Prince,Capalash, Neena The Korean Society for Microbiology and Biotechnol 2011 Journal of microbiology and biotechnology Vol.21 No.7
The gene for esterase (rEst1) was isolated from a new species of genus Rheinheimera by functional screening of E. coli cells transformed with the pSMART/HaeIII genomic library. E. coli cells harboring the esterase gene insert could grow and produce clear halo zones on tributyrin agar. The rEst1 ORF consisted of 1,029 bp, corresponding to 342 amino acid residues with a molecular mass of 37 kDa. The signal P program 3.0 revealed the presence of a signal peptide of 25 amino acids. Esterase activity, however, was associated with a homotrimeric form of molecular mass 95 kDa and not with the monomeric form. The deduced amino acid sequence showed only 54% sequence identity with the closest lipase from Cellvibrio japonicus strain Ueda 107. Conserved domain search and multiple sequence alignment revealed the presence of an esterase/ lipase conserved domain consisting of a GXSXG motif, HGGG motif (oxyanion hole) and HGF motif, typical of the class IV hormone sensitive lipase family. On the basis of the sequence comparison with known esterases/ lipases, REst1 represents a new esterase belonging to the class IV family. The purified enzyme worked optimally at $50^{\circ}C$ and pH 8, utilized pNP esters of short chain lengths, and showed best catalytic activity with p-nitrophenyl butyrate ($C_4$), indicating that it was an esterase. The enzyme was completely inhibited by PMSF and DEPC and showed moderate organotolerance.
Complete Heart Block in Association with Dengue Hemorrhagic Fever
Hafeez Ul Hassan Virk,Faisal Inayat,Zia Ur Rahman 대한심장학회 2016 Korean Circulation Journal Vol.46 No.6
Dengue virus infection affects the heart structurally and functionally. Clinical manifestations of cardiac complications secondary to dengue virus infection vary from self-limiting arrhythmias to severe myocardial infarction, leading to hypotension, pulmonary edema, and cardiogenic shock. However, we report a case of dengue hemorrhagic fever (DHF) complicated by a complete heart block. A female with DHF due to dengue virus serotype 2, presented to the emergency department with fever, headache, rash, and fatigue followed by an episode of syncope. She was found to have a third-degree atrioventricular block, with pulseless polymorphic ventricular tachycardia. Patient was resuscitated and a temporary trans-venous pacemaker was placed. She reverted back to normal sinus rhythm after 4 days of syncope and was subsequently discharged from the hospital after complete resolution of symptoms, without the need for a permanent pacemaker. Physicians are warranted to have high index of suspicion for dengue virus infection as an etiology in patients with acute cardiovascular compromise, especially in tropical areas.
Somatic Embryogenesis in Withania somnifera (L.) Dunal
Rani, Gita,Virk, Gurdip Singh,Nagpal, Avinash The Korean Society of Plant Biotechnology 2004 Plant molecular biology and biotechnology research Vol.6 No.2
Somatic embryos were formed from calli obtained from axillary shoots (raised from nodal segments of glasshouse-grown plants under aseptic conditions), internodal segments (from in vitro-raised plants), and root and coty-ledonary leaf segments (from in vitro-raised seedlings) after 8 weeks of initial culture. Embryo formation was the highest (97.33%) from cotyledonary leaf callus on Mura-shige and Skoog's (MS) medium containing kinetin (KN) (3 mg/L). Somatic embryo induction was lesser with different combinations of auxins while it increased to 100% in internodal segment and cotyledonary leaf calli with 6-benzyladenine (BA) (2mg/L) along with 2,3,5-triiodobenzoic acid (TIBA) (2mg/L). The shoots were induced from somatic embryos raised from root, coty-ledonary leaf and internodal segment calli grown on MS medium containing BA in combination with indole-3-acetic acid (IAA). Maximum of 66.67% cultures formed shoots on MS medium containing BA (1mg/L) in combination with IAA (2mg/L). The shoots raised from somatic embryos were rooted on MS medium supplemented with indole-3-butyric acid (IBA) (2mg/L). The plantlets transferred to the field showed 70% survival rate after one year.
Survey on ISO Standards for Industrial and Service Robots
Seungbin Moon,Gurvinder S. Virk 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
In this paper, the current international ISO activities on robots are introduced; ISO TC 184/SC 2, which has been active in developing standards for industrial robots and has widened its scope recently to include service robots as well as industrial robots. The aim of this paper is to introduce the existing standards and the new standards to be developed in SC 2, so that anyone who has interest in these emerging robotic areas could have information on the progress and the future planned developments.
Nano oxalates of Fe, Co, Ni: Burning rate modifiers for composite solid propellants
Supriya Singh,Gurdip Singh Virk,Pratibha Srivastava 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.27 No.-
We highlight here current research focused on the catalytic activity of nano oxalates of Fe, Co and Nisynthesized by colloidal precipitation method. The catalytic activity of these nano oxalates wasexamined for the thermal decomposition of ammonium perchlorate (AP) and composite solidpropellants (CSPs) using thermogravimetry (TG), TG coupled with differential scanning calorimetry (TG–DSC) and ignition delay measurements. All the nano oxalates showed very high activity as burning ratecatalysts for composite solid propellants (CSPs) containing hydroxyl terminated polybutadiene (HTPB)as binder and AP as oxidizer. CoC2O4 2H2O was found to be the best catalyst in terms of loweringdecomposition temperature of both AP and CSPs
Effect of Oxidative Stress on Male Reproduction
Ashok Agarwal,Gurpriya Virk,Chloe Ong,Stefan S du Plessis 대한남성과학회 2014 The World Journal of Men's Health Vol.32 No.1
Infertility affects approximately 15% of couples trying to conceive, and a male factor contributes to roughly half of these cases. Oxidative stress (OS) has been identified as one of the many mediators of male infertility by causing sperm dysfunction. OS is a state related to increased cellular damage triggered by oxygen and oxygen-derived free radicals known as reactive oxygen species (ROS). During this process, augmented production of ROS overwhelms the body’s antioxidant defenses. While small amounts of ROS are required for normal sperm functioning, disproportionate levels can negatively impact the quality of spermatozoa and impair their overall fertilizing capacity. OS has been identified as an area of great attention because ROS and their metabolites can attack DNA, lipids, and proteins; alter enzymatic systems; produce irreparable alterations; cause cell death; and ultimately, lead to a decline in the semen parameters associated with male infertility. This review highlights the mechanisms of ROS production, the physiological and pathophysiological roles of ROS in relation to the male reproductive system, and recent advances in diagnostic methods; it also explores the benefits of using antioxidants in a clinical setting.
Rafique, Rafia,Zahra, Zahra,Virk, Nasar,Shahid, Muhammad,Pinelli, Eric,Park, Tae Jung,Kallerhoff, Jean,Arshad, Muhammad Elsevier 2018 Agriculture, ecosystems & environment Vol.255 No.-
<P>Titanium dioxide nanoparticles (TiO2 NPs) are used widely in commercial products. These high production levels have led to their increased release into natural ecosystems, where they may interact with plants and affect their physiological functions. The aim of this study was to assess the physiological responses of wheat (Triticum aestivum L.) to increasing concentrations of TiO2 NPs. TiO2 NPs with a particle size less than 20 nm were administered as soil spiked with 0, 20, 40, 60, 80, and 100 mg TiO2 NPs kg(-1), and their physiological parameters, including root and shoot lengths, biomass, phytoavailability of phosphorus (P), chlorophyll content, H2O2 production, and micronuclei (MN) formation in the plants grown from seeds in NPs-spiked soils, were subsequently recorded. All experiments were repeated twice with four replicates per treatment. After 60 days exposure to the NPs, root and shoot lengths, and P uptake by plants was significantly (p < 0.05) higher between 20 and 60 mg kg(-1) compared to the control (0 mg kg(-1) TiO2 NPs), but was then lower at 80 and 100 mg kg(-1) compared to 60 mg kg(-1) TiO2 NPs. The application of TiO2 NPs led to chlorophyll content being higher by 32.3% at 60 mg kg(-1) than in the control, but 11.1% lower content was observed at 100 mg kg(-1). The results suggested that wheat could not tolerate concentrations of TiO2 NPs higher than 60 mg kg(-1) owing to over-production of H2O2 (84.4%) and MN formation (53.6%).</P>