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Boda A, Sahu P, Singha Deb A, Ali S. DFT, MD simulations and experimental analysis of adsorptive complexation and isotope separation of gadolinium ion with macrocyclic crown ether embedded polymeric resin. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.120709] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Sahu P, Balakrishnan A, Di Martino R, Luini A, Russo D. Role of the Mosaic Cisternal Maturation Machinery in Glycan Synthesis and Oncogenesis. Front Cell Dev Biol 2022; 10:842448. [PMID: 35465326 PMCID: PMC9019784 DOI: 10.3389/fcell.2022.842448] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 03/24/2022] [Indexed: 12/20/2022] Open
Abstract
Tumorigenesis is associated with the deregulation of multiple processes, among which the glycosylation of lipids and proteins is one of the most extensively affected. However, in most cases, it remains unclear whether aberrant glycosylation is a cause, a link in the pathogenetic chain, or a mere consequence of tumorigenesis. In other cases, instead, studies have shown that aberrant glycans can promote oncogenesis. To comprehend how aberrant glycans are generated it is necessary to clarify the underlying mechanisms of glycan synthesis at the Golgi apparatus, which are still poorly understood. Important factors that determine the glycosylation potential of the Golgi apparatus are the levels and intra-Golgi localization of the glycosylation enzymes. These factors are regulated by the process of cisternal maturation which transports the cargoes through the Golgi apparatus while retaining the glycosylation enzymes in the organelle. This mechanism has till now been considered a single, house-keeping and constitutive function. Instead, we here propose that it is a mosaic of pathways, each controlling specific set of functionally related glycosylation enzymes. This changes the conception of cisternal maturation from a constitutive to a highly regulated function. In this new light, we discuss potential new groups oncogenes among the cisternal maturation machinery that can contribute to aberrant glycosylation observed in cancer cells. Further, we also discuss the prospects of novel anticancer treatments targeting the intra-Golgi trafficking process, particularly the cisternal maturation mechanism, to control/inhibit the production of pro-tumorigenic glycans.
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Affiliation(s)
| | | | | | - A. Luini
- *Correspondence: A. Luini, ; D. Russo,
| | - D. Russo
- *Correspondence: A. Luini, ; D. Russo,
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Rizzo R, Russo D, Kurokawa K, Sahu P, Lombardi B, Supino D, Zhukovsky MA, Vocat A, Pothukuchi P, Kunnathully V, Capolupo L, Boncompain G, Vitagliano C, Zito Marino F, Aquino G, Montariello D, Henklein P, Mandrich L, Botti G, Clausen H, Mandel U, Yamaji T, Hanada K, Budillon A, Perez F, Parashuraman S, Hannun YA, Nakano A, Corda D, D'Angelo G, Luini A. Golgi maturation-dependent glycoenzyme recycling controls glycosphingolipid biosynthesis and cell growth via GOLPH3. EMBO J 2021; 40:e107238. [PMID: 33749896 DOI: 10.15252/embj.2020107238] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 01/24/2021] [Accepted: 02/10/2021] [Indexed: 01/08/2023] Open
Abstract
Glycosphingolipids are important components of the plasma membrane where they modulate the activities of membrane proteins including signalling receptors. Glycosphingolipid synthesis relies on competing reactions catalysed by Golgi-resident enzymes during the passage of substrates through the Golgi cisternae. The glycosphingolipid metabolic output is determined by the position and levels of the enzymes within the Golgi stack, but the mechanisms that coordinate the intra-Golgi localisation of the enzymes are poorly understood. Here, we show that a group of sequentially-acting enzymes operating at the branchpoint among glycosphingolipid synthetic pathways binds the Golgi-localised oncoprotein GOLPH3. GOLPH3 sorts these enzymes into vesicles for intra-Golgi retro-transport, acting as a component of the cisternal maturation mechanism. Through these effects, GOLPH3 controls the sub-Golgi localisation and the lysosomal degradation rate of specific enzymes. Increased GOLPH3 levels, as those observed in tumours, alter glycosphingolipid synthesis and plasma membrane composition thereby promoting mitogenic signalling and cell proliferation. These data have medical implications as they outline a novel oncogenic mechanism of action for GOLPH3 based on glycosphingolipid metabolism.
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Affiliation(s)
- Riccardo Rizzo
- Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy.,Institute of Nanotechnology, National Research Council (CNR-NANOTEC), Lecce, Italy
| | - Domenico Russo
- Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
| | - Kazuo Kurokawa
- Live Cell Super-Resolution Imaging Research Team, RIKEN Center for Advanced Photonics, Saitama, Japan
| | - Pranoy Sahu
- Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
| | - Bernadette Lombardi
- Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
| | - Domenico Supino
- Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
| | - Mikhail A Zhukovsky
- Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
| | - Anthony Vocat
- École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Prathyush Pothukuchi
- Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
| | - Vidya Kunnathully
- Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
| | - Laura Capolupo
- École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | | | - Carlo Vitagliano
- Istituto Nazionale Tumori Fondazione G. Pascale-IRCCS, Naples, Italy
| | | | - Gabriella Aquino
- Istituto Nazionale Tumori Fondazione G. Pascale-IRCCS, Naples, Italy
| | - Daniela Montariello
- Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
| | - Petra Henklein
- Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Biochemistry, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Berlin, Germany
| | - Luigi Mandrich
- Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
| | - Gerardo Botti
- Istituto Nazionale Tumori Fondazione G. Pascale-IRCCS, Naples, Italy
| | - Henrik Clausen
- Faculty of Health Sciences, Centre for Glycomics, Department of Cellular and Molecular Medicine Nørre Alle 20, University of Copenhagen, Copenhagen N, Denmark
| | - Ulla Mandel
- Faculty of Health Sciences, Centre for Glycomics, Department of Cellular and Molecular Medicine Nørre Alle 20, University of Copenhagen, Copenhagen N, Denmark
| | - Toshiyuki Yamaji
- Department of Biochemistry & Cell Biology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Kentaro Hanada
- Department of Biochemistry & Cell Biology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Alfredo Budillon
- Istituto Nazionale Tumori Fondazione G. Pascale-IRCCS, Naples, Italy
| | - Franck Perez
- Institute Curie - CNRS UMR1 44, Research Center, Paris, France
| | | | - Yusuf A Hannun
- Stony Brook University Medical Center, New York, NY, USA
| | - Akihiko Nakano
- Live Cell Super-Resolution Imaging Research Team, RIKEN Center for Advanced Photonics, Saitama, Japan
| | - Daniela Corda
- Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
| | - Giovanni D'Angelo
- Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy.,École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Alberto Luini
- Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
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Singha Deb AK, Sahu P, Boda A, Ali SM, Shenoy KT, Upadhyay D. DFT and MD simulation supplemented experiments for isotopic fractionation of zinc compounds using a macrocyclic crown ether appended polymeric resin. Phys Chem Chem Phys 2020; 22:14682-14693. [PMID: 32573611 DOI: 10.1039/d0cp01660h] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Isotope effect is a quantum mechanical phenomenon and thus poses a challenge for the separation of isotopes of an element of interest, especially for heavy elements. Isotopic fractionation of zinc is also quite difficult and challenging but is necessitated due to various applications of its isotopes ranging from nuclear medicine to nuclear power reactors. Here, we developed the dibenzo-18-crown-6 (DB18C6) ether-functionalized poly(methacrylic acid) (PMA) resin by exploiting the ion and isotope recognition ability of the crown ether using DFT/MD simulations followed by experiments for isotopic fractionation of zinc. The PMADB18C6 adsorbent was prepared and suitably characterized. Both computational and experimental findings demonstrate that the adsorption and isotope separation of zinc with PMADB18C6 are due to the molecular recognition effect of the "O" dipole of the crown ether. Furthermore, both MD simulations and experiments suggest Langmuir type adsorption isotherms. The adsorption of Zn2+ ions on the PMA resin is predicted to be endothermic, whereas it is exothermic on the PMADB18C6 resin, as revealed from the experimentally observed enthalpy change. A small scale fixed bed column study was demonstrated to test the scale-up application. The values of the experimental separation factors: 1.0013 for 66/64 and 1.0027 for 68/64 confirm the computationally predicted results of 1.00088 and 1.0010, respectively, thus establishing the combined strength of the theory and experiments for the identification of efficient fractionating agents for a complex quantum isotope effect which eventually helps in planning further experiments in view of medicinal and technological applications of zinc isotopes.
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Affiliation(s)
- A K Singha Deb
- Chemical Engineering Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India.
| | - P Sahu
- Chemical Engineering Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India.
| | - A Boda
- Chemical Engineering Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India.
| | - Sk M Ali
- Chemical Engineering Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India.
| | - K T Shenoy
- Chemical Engineering Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India.
| | - D Upadhyay
- Homi Bhabha National Institute, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India and Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur, West Bengal 721302, India
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Gupta S, Rout G, Patel AH, Mahanta M, Kalra N, Sahu P, Sethia R, Agarwal A, Ranjan G, Kedia S, Acharya SK, Nayak B, Shalimar. Efficacy of generic oral directly acting agents in patients with hepatitis C virus infection. J Viral Hepat 2018; 25:771-778. [PMID: 29377464 DOI: 10.1111/jvh.12870] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 12/15/2017] [Indexed: 12/13/2022]
Abstract
Novel direct-acting antivirals (DAAs) are now the standard of care for the management of hepatitis C virus (HCV) infection. Branded DAAs are associated with high sustained virological response at 12 weeks post-completion of therapy (SVR12), but are costly. We aimed to assess the efficacy of generic oral DAAs in a real-life clinical scenario. Consecutive patients with known HCV infection who were treated with generic-oral DAA regimens (May 2015 to January 2017) were included. Demographic details, prior therapy and SVR12 were documented. Four hundred and ninety patients (mean age: 38.9 ± 12.7 years) were treated with generic DAAs in the study time period. Their clinical presentations included chronic hepatitis (CHC) in 339 (69.2%) of cases, compensated cirrhosis in 120 (24.48%) cases and decompensated cirrhosis in 31 (6.32%) cases. Genotype 3 was most common (n = 372, 75.9%) followed by genotype 1 (n = 97, 19.8%). Treatment naïve and treatment-experienced (defined as having previous treatment with peginterferon and ribavirin) were 432 (88.2%) and 58 (11.8%), respectively. Generic DAA treatment regimens included sofosbuvir in combination with ribavirin (n = 175), daclatasvir alone (n = 149), ribavirin and peginterferon (n = 80), ledipasvir alone (n = 43), daclatasvir and ribavirin (n = 37), and ledipasvir and ribavirin (n = 6). Overall SVR12 was 95.9% (470/490) for all treatment regimens. SVR12 for treatment naïve and experienced patients was 97.0% (419/432) and 87.9% (51/58), respectively, P = .005. High SVR12 was observed with various regimens, irrespective of genotype and underlying liver disease status. There were no differences in SVR12 with 12 or 24 weeks therapy. No major adverse event occurred requiring treatment stoppage. Generic oral DAAs are associated with high SVR rates in patients with HCV infection in a real-life clinical scenario.
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Affiliation(s)
- S Gupta
- Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India
| | - G Rout
- Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India
| | - A H Patel
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
| | - M Mahanta
- Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India
| | - N Kalra
- Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India
| | - P Sahu
- Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India
| | - R Sethia
- Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India
| | - A Agarwal
- Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India
| | - G Ranjan
- Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India
| | - S Kedia
- Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India
| | - S K Acharya
- Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India
| | - B Nayak
- Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India
| | - Shalimar
- Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India
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Sahu P, Aggarwal P, Dayal S, Kumar Jain V. Biologic therapy: a boon for hidradenitis suppurativa-like lesions complicating naevus comedonicus in a prepubertal child. Clin Exp Dermatol 2018; 44:322-324. [PMID: 29888492 DOI: 10.1111/ced.13685] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/07/2018] [Indexed: 11/30/2022]
Affiliation(s)
- P Sahu
- Department of Dermatology, Venereology and Leprology, Pandit Bhagwat DayalSharma Post Graduate Institute of Medical Sciences, Rohtak, Haryana, India
| | | | - S Dayal
- Department of Dermatology, Venereology and Leprology, Pandit Bhagwat DayalSharma Post Graduate Institute of Medical Sciences, Rohtak, Haryana, India
| | - V Kumar Jain
- Dr V. K. Jain Skin Center, Rohtak, Haryana, India
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Sahu P, Khuntia HK, Mohapatra A, Kar SK. Occult Hepatitis B virus Infection (OBI) predominated by genotype D among chronic liver disease patients: The first report from Odisha, Eastern India. Trop Biomed 2018; 35:221-227. [PMID: 33601794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Detection of Occult hepatitis B infection (OBI) has higher significance for treatment and management. There is no information available about the OBI and its genotype associated with chronic hepatitis patients in Odisha, India. We aimed to determine the association of OBI and its genotype among the chronic hepatitis patients in Odisha. In a hospital based study, 175 serum samples of chronic hepatitis patients were screened for Hepatitis surface antigen (HBsAg). All the HBsAg - negative samples were tested for hepatitis B core antibodies (HBcAb). HBcAb-positive samples were tested further for Hepatitis surface antibodies (HBsAb), hepatitis B virus HBV-DNA and HBV genotyping. Of the 89 HBsAg negative samples, 79 (88.8%) were found positive for HBcAb and these patients were presumed to have OBI. Among the total HBcAb positive samples, 22 (27.8%) were positive and 57 (72.2%) were negative for HBsAb. Detection of HBV- DNA from 45 out of 79 HBcAb positive samples (57.0%) yielded positive results for OBI which was negative for HBsAb. Genotyping of all hepatitis B virus showed that all 45 (100%) were genotype-D. Detection of OBI among chronic hepatitis patients suggests testing for OBI for management and treatment.
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Affiliation(s)
- P Sahu
- National Institute for Malaria Research (ICMR), New Delhi, India
| | - H K Khuntia
- Regional Medical Research Centre (ICMR), Bhubaneswar-23, Odisha, IndiaRegional Medical Research Centre (ICMR), Bhubaneswar-23, Odisha, India
| | - A Mohapatra
- Regional Medical Research Centre (ICMR), Bhubaneswar-23, Odisha, India
| | - S K Kar
- Directorate of Medical Research, S'O'A University, Bhubaneswar, Odisha, India
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Singal R, Singh P, Sahu P, Mittat A, Naredi B, Gupta3 S. Metaplastic Carcinoma of the Breast with High Grade Spindle Cell Component with Osteoid Formation—a Rare Case Report. Acta Chir Belg 2016. [DOI: 10.1080/00015458.2011.11680747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- R. Singal
- Department of Surgery, M.M. Institute of Medical Sciences and Research, Mullana (Distt-Ambala), Haryana, India
| | - P. Singh
- Department of Pathology, M.M. Institute of Medical Sciences and Research, Mullana (Distt-Ambala), Haryana, India
| | - P. Sahu
- Department of Surgery, M.M. Institute of Medical Sciences and Research, Mullana (Distt-Ambala), Haryana, India
| | - A. Mittat
- Department of Radiology, M.M. Institute of Medical Sciences and Research, Mullana (Distt-Ambala), Haryana, India
| | - B. Naredi
- Department of Surgery, M.M. Institute of Medical Sciences and Research, Mullana (Distt-Ambala), Haryana, India
| | - S. Gupta3
- Department of Radiology, M.M. Institute of Medical Sciences and Research, Mullana (Distt-Ambala), Haryana, India
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Jena MS, Sahu P, Dash P, Mohanty JK. Beneficiation of limestone plant rejects for value addition. J Hazard Mater 2013; 262:218-227. [PMID: 24035797 DOI: 10.1016/j.jhazmat.2013.08.048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 08/16/2013] [Accepted: 08/17/2013] [Indexed: 06/02/2023]
Abstract
Investigations were carried out on lime stone rejects (-1mm) generated at a lime stone washing plant in southern India. These rejects contain 12.09% CaO, 2.95% MgO, 10.73% Al2O3, 4.99% Fe2O3, 43.05% SiO2 and 24.92% LOI. Mineralogical studies including SEM-EDAX, XRD, FTIR and TGA were conducted to confirm relative distribution of minerals in the flotation feed and products. These studies revealed that feed sample consists of quartz and calcite as the major minerals with minor amounts of montmorillonite and dolomite whereas flotation concentrate dominantly consists of calcite, and tailings mostly of quartz and montmorillonite. A commercial grade sodium silicate, oleic acid and MIBC were used as depressant, collector and frother respectively in flotation studies. The effects of different operating parameters were evaluated for both conventional and column flotation. Two stage conventional cell flotation results indicate that a cleaner concentrate of 42.50% lime (CaO) content could be obtained at a yield of 15.65%. The lime (CaO) content of the concentrate was further enhanced up to 44.23% at 20.73% yield using single stage column flotation. The column flotation is more efficient in comparison to the conventional cell for treating this sample. A process flowsheet was developed to treat these rejects based on the studies carried out. This process can minimize the waste generation and the concentrate generated during this process can be directly utilized in the Indian cement industries.
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Affiliation(s)
- M S Jena
- Department of Mineral Processing, CSIR-Institute of Minerals & Materials Technology, Bhubaneswar, Orissa, India.
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Singal R, Singh P, Sahu P, Mittal A, Naredi B, Gupta S. Metaplastic carcinoma of the breast with high grade spindle cell component with osteoid formation--a rare case report. Acta Chir Belg 2011; 111:243-245. [PMID: 21954743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Metaplastic carcinoma breast is rare entity with incidence of 0.02% of all breast malignancies. The ranges of age at diagnosis as well as clinical symptoms do not differ from that of conventional invasive ductal breast cancer. We are reporting a rare case diagnosed as metaplastic breast carcinoma on ultrasonography and confirmed histopathologically. The case merits presentation because of its rarity, low frequency of axillary metastasis and difficulty in interpreting the morphological features which correspond with prognosis.
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Affiliation(s)
- R Singal
- Department of Surgery, M.M. Institute of Medical Sciences and Research, Mullana (Distt - Ambala), Haryana, India.
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Bonasera A, Chen Z, Wada R, Hagel K, Natowitz J, Sahu P, Qin L, Kowalski S, Keutgen T, Materna T, Nakagawa T. Quantum nature of a nuclear phase transition. Phys Rev Lett 2008; 101:122702. [PMID: 18851368 DOI: 10.1103/physrevlett.101.122702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2008] [Indexed: 05/26/2023]
Abstract
At finite temperatures and low densities, nuclei may undergo a phase change similar to a classical liquid-gas phase transition. Temperature is the control parameter while density and pressure are the conjugate variables. In the nucleus the difference between the proton and neutron concentrations acts as an additional order parameter, for which the symmetry potential is the conjugate variable. We present experimental results which reveal the N/Z dependence of the phase transition and discuss possible implications of these observations in terms of the Landau free energy description of critical phenomena.
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Affiliation(s)
- A Bonasera
- Cyclotron Institute, Texas A&M, College Station, TX 77843, USA
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Sahu P, Hamada AS, Ghosh Chowdhury S, Karjalainen LP. Structure and microstructure evolution during martensitic transformation in wrought Fe–26Mn–0.14C austenitic steel: an effect of cooling rate. J Appl Crystallogr 2007. [DOI: 10.1107/s0021889807005882] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Structure and microstructure evolution under various cooling rates of a wrought austenitic steel, Fe–26Mn–0.14C (composition in mass %), were studied by the Rietveld method of X-ray diffraction pattern fitting, grain boundary characterization by electron back-scattered diffraction (EBSD) and optical microscopy. Cooling rate, density of stacking faults, and austenite grain size and grain boundaries influence the observed γfcc→ ∊hcptransformation and lead to significant anisotropic X-ray line broadening. Depending on the cooling conditions, the grain boundaries are misoriented at both lower and higher angles. In the ∊-martensites, the dominant planar fault is twins (∼10−3). The austenite grains were found to contain low to moderate density of stacking faults (∼10−4–10−3), which act as efficient nucleation sites of the ∊-martensites. Both X-ray and EBSD analyses estimated negligible twins in the austenite. Approximate average dislocation densities have been estimated and correlated with the grain structure.
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Sahu P. Bainite and stress-induced martensite in an AISI type 300 steel: an X-ray diffraction study of the microstructure by the Rietveld method. J Appl Crystallogr 2005. [DOI: 10.1107/s0021889804028717] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The present study concerns the X-ray characterization of the microstructure of an AISI type 300 stainless steel with composition Fe–17Cr–8Ni–1Mn–0.1C (wt%), undergoing stress-induced martensite and bainite transformations following γ(f.c.c.) → α(b.c.c.) transformation reactions. The methodology applied is a Rietveld whole X-ray profile fitting technique, adopting the recently developed softwareMAUD(Materials Analysis Using Diffraction) which incorporates the Popa model for crystallite size and microstrain [root mean square (r.m.s.) strain] and the preferred orientation of the crystallites. The analysis also considers the lattice-defect-related features of the evolved microstructures, namely stacking-fault probabilities and dislocation-density values. The study revealed a high degree of stress-induced martensitic transformation (∼94%) in the cold-worked (hand-filed powder) state of the material. However, no low-temperature martensitic transformation could be observed in this class of materials at temperatures below the martensite start temperature (Ms). On isothermal aging at 673 K for different periods of time (1, 3 and 6 h), the austenite transforms partially into bainite with continuously varying volume fractions (17, 42 and 44%) and the corresponding microhardness values are 218, 230 and 233 kg mm−2. The size–strain–shape analysis adopting the Popa model reveals anisotropic and almost isotropic values of the crystallite sizes and r.m.s. strains in the austenite and bainite microstructures, respectively. High values of the dislocation density (∼1016 m−2) were observed in the bainite due to the plastic deformation of the austenite induced by the shape change of the growing bainite. The values of all the above defect parameters have been evaluated and compared in order to elucidate the structure–property relationships.
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Choudhury SR, Sahu P, Singh D, Chadha R. Plastic pens as substitutes for metallic dilators. J Indian Assoc Pediatr Surg 2005. [DOI: 10.4103/0971-9261.16478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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Sahu P, De M, Kajiwara S. Microstructural characterization of stress-induced martensites evoluted at low temperature in deformed powders of Fe-Mn-C alloys by Rietveld method. Acta Crystallogr A 2002. [DOI: 10.1107/s0108767302099373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Affiliation(s)
- P Sahu
- Cardiovascular Research Group, Department of Clinical Pharmacology and Therapeutics, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
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Kane GR, Mathew R, Chakrapani BS, Waykole M, Sahu P. Thrombotic complications during coronary angiography associated with use of non-ionic contrast media. Indian Heart J 1998; 50:433-5. [PMID: 9835205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Affiliation(s)
- G R Kane
- Department of Cardiology, LTMM Medical College, Mumbai
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Beckett GJ, Russell A, Nicol F, Sahu P, Wolf CR, Arthur JR. Effect of selenium deficiency on hepatic type I 5-iodothyronine deiodinase activity and hepatic thyroid hormone levels in the rat. Biochem J 1992; 282 ( Pt 2):483-6. [PMID: 1546962 PMCID: PMC1130805 DOI: 10.1042/bj2820483] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Selenium deficiency in rats for a period of up to 6 weeks inhibited both the production of 3,3',5-tri-iodothyronine (T3) from thyroxine (T4) (5'-deiodination) and also the catabolism of T3 to 3,3'-di-iodothyronine (5-deiodination) in liver homogenates. The hepatic stores of T3 were decreased by only 8% in selenium deficiency, despite the T3 production rate from T4 being only 7% of the rate found in selenium-supplemented rats. Hepatic glutathione S-transferase (GST) activity was increased in both hypothyroidism and selenium deficiency, but apparently by different mechanisms, since mRNA expression for this family of enzymes was lowered by hypothyroidism and increased in selenium deficiency. It is concluded that, since both T3 production and catabolism are inhibited by selenium deficiency, there is little change in hepatic T3 stores, and therefore the changes in the activity of certain hepatic enzymes, such as GST, that are found in selenium deficiency are not the result of tissue hypothyroidism.
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Affiliation(s)
- G J Beckett
- University Department of Clinical Chemistry, Royal Infirmary, Edinburgh, U.K
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Rao PT, Patnaik SB, Mahapatr BM, Sahu P. Pycnodysostosis. J Indian Med Assoc 1976; 66:65-6. [PMID: 1270830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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