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PA-824 Kills Nonreplicating Mycobacterium tuberculosis by Intracellular NO Release
Singh, R.,Manjunatha, U.,Boshoff, H. I. M.,Ha, Y. H.,Niyomrattanakit, P.,Ledwidge, R.,Dowd, C. S.,Lee, I. Y.,Kim, P.,Zhang, L.,Kang, S.,Keller, T. H.,Jiricek, J.,Barry, C. E. American Association for the Advancement of Scienc 2008 Science Vol.322 No.5906
<P>Bicyclic nitroimidazoles, including PA-824, are exciting candidates for the treatment of tuberculosis. These prodrugs require intracellular activation for their biological function. We found that Rv3547 is a deazaflavin-dependent nitroreductase (Ddn) that converts PA-824 into three primary metabolites; the major one is the corresponding des-nitroimidazole (des-nitro). When derivatives of PA-824 were used, the amount of des-nitro metabolite formed was highly correlated with anaerobic killing of Mycobacterium tuberculosis (Mtb). Des-nitro metabolite formation generated reactive nitrogen species, including nitric oxide (NO), which are the major effectors of the anaerobic activity of these compounds. Furthermore, NO scavengers protected the bacilli from the lethal effects of the drug. Thus, these compounds may act as intracellular NO donors and could augment a killing mechanism intrinsic to the innate immune system.</P>
A Study of Shielding Properties of X-ray and Gamma in Barium Compounds
Seenappa, L.,Manjunatha, H.C.,Chandrika, B.M.,Chikka, Hanumantharayappa The Korean Association for Radiation Protection 2017 방사선방어학회지 Vol.42 No.1
Background: Ionizing radiation is known to be harmful to human health. The shielding of ionizing radiation depends on the attenuation which can be achieved by three main rules, i.e. time, distance and absorbing material. Materials and Methods: The mass attenuation coefficient, linear attenuation coefficient, Half Value Layer (HVL) and Tenth Value Layer (TVL) of X-rays (32 keV, 74 keV) and gamma rays (662 keV) are measured in Barium compounds. Results and Discussion: The measured values agree well with the theory. The effective atomic numbers ($Z_{eff}$) and electron density (Ne) of Barium compounds have been computed in the wide energy region 1 keV to 100 GeV using an accurate database of photon-interaction cross sections and the WinXCom program. Conclusion: The mass attenuation coefficient and linear attenuation coefficient for $BaCO_3$ is higher than the $BaCl_2$, $Ba(No_3)_2$ and BaSO4. HVL, TVL and mean free path are lower for $BaCO_3$ than the $BaCl_2$, $Ba(No_3)_2$ and $BaSO_4$. Among the studied barium compounds, $BaCO_3$ is best material for x-ray and gamma shielding.
B. Chinnappa Reddy,H.C. Manjunatha,Y.S. Vidya,K.N. Sridhar,U. Mahaboob Pasha,L. Seenappa,B. Sadashivamurthy,N. Dhananjaya,K.V. Sathish,P.S. Damodara Gupta 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.3
In the present communication, pure and stable a-Bismuth Oxide (Bi2O3) nanoparticles (NPs) weresynthesized by low temperature solution combustion method using urea as a fuel and calcined at 500oC. The synthesized sample was characterized by using powder X-ray Diffraction (PXRD), Scanning ElectronMicroscopy (SEM), Energy dispersive X-ray analysis (EDAX), Transmission Electron Microscopy (TEM),Fourier Transform Infrared Spectroscopy (FTIR) and UVeVisible absorption spectroscopy. The PXRDpattern confirms the formation of mono-clinic, stable and low temperature phase a-Bi2O3. The directoptical energy band gap was estimated by usingWood and Tauc's relation which was found to be 2.81 eV. The characterized sample was studied for X-ray/gamma ray shielding properties in the energy range0.081e1.332 MeV using NaI (Tl) detector and multi channel analyzer (MCA). The measured shieldingparameters agrees well with the theory, whereas, slight deviation up to 20% is observed below 356 keV. This deviation is mainly due to the influence of atomic size of the target medium. Furthermore an accuratetheory is necessary to explain the interaction of X-ray/gamma ray with the NPs.The present workopens new window to use this facile, economical, efficient, low temperature method to synthesizenanomaterials for X-ray/gamma ray shielding purpose
Multifunctional properties of tin oxide nanoparticles synthesized by green and chemical approach
Uday Y.S.,Manjunatha H.C.,Vidya Y.S.,Manjunatha S.,Soundar R.,Sridhar K.N. 한국물리학회 2023 Current Applied Physics Vol.55 No.-
Herein, we report the synthesis of SnO2 nanoparticles by combustion method using two reducing agents. One with urea as a fuel (SnO2U) and another one with Azadirachta indica leaves extract as a reducing agent (SnO2N) and calcined at 500oC for 3 hrs. The synthesized samples are characterized using different techniques. The Bragg reflections confirms the formation of pure tetragonal SnO2 NPs. The surface morphological analysis clearly indicates the formation of irregular shaped agglomerated NPs. The agglomeration and particle size was found to be more in SnO2U NPs. The estimated direct energy bandgap using Tauc's relation was found to be 3.75 and 3.37 eV for SnO2U and SnO2N respectively. Further, Photoluminescence excitation, emission, CIE and CCT analysis was performed. Thus, the present sample might be used as a nanophosphor material in Cool and Warm blue light emitting diodes. The cytotoxic properties against HeLa and MCF7 cells and compared the percentage of viability and cell death with standard chemotherapy drug Cisplatin. Theoretically, X-ray/gamma ray absorption properties such as mass attenuation coefficient (MAC) SnO2U and SnO2N NPs were evaluated which might finds an application in nuclear radiation dosimetry.
Sathish K.V.,Sridhar K.N.,Seenappa L.,Manjunatha H.C.,Vidya Y.S.,Chinnappa Reddy B.,Manjunatha S.,Santhosh A.N.,Munirathnam R.,Raj Alfred Cecil,Damodara Gupta P.S.,Sankarshan B.M. 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.5
For the first time Aluminium-BariumeZinc oxide nanocomposite (ZABONC) was synthesized by solution combustion method where calcination was carried out at low temperatures (6000 C) to study the electromagnetic (EM) (X/g) radiation shielding properties. Further for characterization purpose standard techniques like PXRD, SEM, UV-VISIBLE, FTIR were used to find phase purity, functional groups, surface morphology, and to do structural analysis and energy band gap determination. The PXRD pattern shows (hkl) planes corresponding to spinel cubic phase of ZnAl2O4, cubic BaðNO3Þ2, a and g phase of Al2O3 which clearly confirms the formation of complex nano composite. From SEM histogram mean size of nano particles was calculated and is in the order of 17 nm. Wood and Tauc’s relation direct energy band gap calculation gives energy gap of 2.9 eV. In addition, EM (X/g) shielding properties were measured and compared with the theoretical ones using standard procedures (NaI (Tl) detector and multi channel analyzer MCA). For energy above 356 keV the measured shielding parameters agree well with the theory, while below this value slight deviation is observed, due to the influence of atomic/crystallite size of the ZABONC. Hence synthesized ZABONC can be used as a shielding material in EM (X/g) radiation shielding