1
|
Saraswat V, Pal SK, Mehta N, Kumar A, Imran MMA. Thermal analysis of novel third-generation phase-change materials with zinc as a chemical modifier. RSC Adv 2023; 13:3602-3611. [PMID: 36756576 PMCID: PMC9890671 DOI: 10.1039/d2ra07041c] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Accepted: 01/07/2023] [Indexed: 01/27/2023] Open
Abstract
The thermal analysis in the present work is done to analyze the glass/crystal phase transformation in a newly synthesized glassy system (i.e., glassy SeTeSnZn alloys) consisting of chalcogenides Se and Te as major elements, Sn as a third element of the parent alloy and Zn as a chemical modifier. The role of increasing the Zn concentration at the cost of Se has been understood by correlating the kinematics of structural relaxation during the glass transition phenomenon and devitrification during the crystallization phenomenon in the chalcogenide glasses (ChGs) of the quaternary STSZ [i.e., Se78-x Zn x Te20Sn2 (0 ≤ x ≤ 6)] system and their different physicochemical properties. A noticeable rise in the crystallization rate is observed after the addition of Zn in the parent SeTeSn glass. With the rise in the zinc content, the values of average heat of atomization and overall mean bond energy are found to be decreased with the decrease in cohesive energy of samples. An inverse correlation is observed between the thermal stability parameter and the enthalpy released during the glass/crystalline phase transformation.
Collapse
Affiliation(s)
- Vishnu Saraswat
- Physics Department, Banaras Hindu University Varanasi-221005 India
| | - Shiv Kumar Pal
- Physics Department, Banaras Hindu University Varanasi-221005 India
| | - N. Mehta
- Physics Department, Banaras Hindu UniversityVaranasi-221005India
| | - Arun Kumar
- Physics Department, IIT RoorkeeRoorkee-247667India
| | - M. M. A. Imran
- Physics Department, Al-Balqa Applied UniversityAl-Salt-19117Jordan
| |
Collapse
|
2
|
Gane E, Kershenobich D, Seguin-Devaux C, Kristian P, Aho I, Dalgard O, Shestakova I, Nymadawa P, Blach S, Acharya S, Anand AC, Andersson MI, Arendt V, Arkkila P, Baatarkhuu O, Barclay K, Ben-Ari Z, Bergin C, Bessone F, Blokhina N, Brunton CR, Choudhuri G, Chulanov V, Cisneros L, Croes EA, Dahgwahdorj YA, Daruich JR, Dashdorj NR, Davaadorj D, de Knegt RJ, de Vree M, Gadano AC, Gower E, Halota W, Hatzakis A, Henderson C, Hoffmann P, Hornell J, Houlihan D, Hrusovsky S, Jarčuška P, Kostrzewska K, Leshno M, Lurie Y, Mahomed A, Mamonova N, Mendez-Sanchez N, Mossong J, Norris S, Nurmukhametova E, Oltman M, Oyunbileg J, Oyunsuren T, Papatheodoridis G, Pimenov N, Prins M, Puri P, Radke S, Rakhmanova A, Razavi H, Razavi-Shearer K, Reesink HW, Ridruejo E, Safadi R, Sagalova O, Sanchez Avila JF, Sanduijav R, Saraswat V, Schréter I, Shah SR, Shevaldin A, Shibolet O, Silva MO, Sokolov S, Sonderup M, Souliotis K, Spearman CW, Staub T, Stedman C, Strebkova EA, Struck D, Sypsa V, Tomasiewicz K, Undram L, van der Meer AJ, van Santen D, Veldhuijzen I, Villamil FG, Willemse S, Zuckerman E, Zuure FR, Prabdial-Sing N, Flisiak R, Estes C. Strategies to manage hepatitis C virus (HCV) infection disease burden - volume 2. J Viral Hepat 2015; 22 Suppl 1:46-73. [PMID: 25560841 DOI: 10.1111/jvh.12352] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [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] [Indexed: 02/06/2023]
Abstract
The hepatitis C virus (HCV) epidemic was forecasted through 2030 for 15 countries, and the relative impact of two scenarios was considered: (i) increased treatment efficacy while holding the treated population constant and (ii) increased treatment efficacy and increased annual treated population. Increasing levels of diagnosis and treatment, in combination with improved treatment efficacy, were critical for achieving substantial reductions in disease burden. In most countries, the annual treated population had to increase several fold to achieve the largest reductions in HCV-related morbidity and mortality. This suggests that increased capacity for screening and treatment will be critical in many countries. Birth cohort screening is a helpful tool for maximizing resources. In most of the studied countries, the majority of patients were born between 1945 and 1985.
Collapse
Affiliation(s)
- E Gane
- Auckland Hospital Clinical Studies Unit, Auckland, New Zealand
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
3
|
Hatzakis A, Chulanov V, Gadano AC, Bergin C, Ben-Ari Z, Mossong J, Schréter I, Baatarkhuu O, Acharya S, Aho I, Anand AC, Andersson MI, Arendt V, Arkkila P, Barclay K, Bessone F, Blach S, Blokhina N, Brunton CR, Choudhuri G, Cisneros L, Croes EA, Dahgwahdorj YA, Dalgard O, Daruich JR, Dashdorj NR, Davaadorj D, de Knegt RJ, de Vree M, Estes C, Flisiak R, Gane E, Gower E, Halota W, Henderson C, Hoffmann P, Hornell J, Houlihan D, Hrusovsky S, Jarčuška P, Kershenobich D, Kostrzewska K, Kristian P, Leshno M, Lurie Y, Mahomed A, Mamonova N, Mendez-Sanchez N, Norris S, Nurmukhametova E, Nymadawa P, Oltman M, Oyunbileg J, Oyunsuren T, Papatheodoridis G, Pimenov N, Prabdial-Sing N, Prins M, Radke S, Rakhmanova A, Razavi-Shearer K, Reesink HW, Ridruejo E, Safadi R, Sagalova O, Sanchez Avila JF, Sanduijav R, Saraswat V, Seguin-Devaux C, Shah SR, Shestakova I, Shevaldin A, Shibolet O, Silva MO, Sokolov S, Sonderup M, Souliotis K, Spearman CW, Staub T, Stedman C, Strebkova EA, Struck D, Sypsa V, Tomasiewicz K, Undram L, van der Meer AJ, van Santen D, Veldhuijzen I, Villamil FG, Willemse S, Zuckerman E, Zuure FR, Puri P, Razavi H. The present and future disease burden of hepatitis C virus (HCV) infections with today's treatment paradigm - volume 2. J Viral Hepat 2015; 22 Suppl 1:26-45. [PMID: 25560840 DOI: 10.1111/jvh.12351] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [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] [Indexed: 12/12/2022]
Abstract
Morbidity and mortality attributable to chronic hepatitis C virus (HCV) infection are increasing in many countries as the infected population ages. Models were developed for 15 countries to quantify and characterize the viremic population, as well as estimate the number of new infections and HCV related deaths from 2013 to 2030. Expert consensus was used to determine current treatment levels and outcomes in each country. In most countries, viremic prevalence has already peaked. In every country studied, prevalence begins to decline before 2030, when current treatment levels were held constant. In contrast, cases of advanced liver disease and liver related deaths will continue to increase through 2030 in most countries. The current treatment paradigm is inadequate if large reductions in HCV related morbidity and mortality are to be achieved.
Collapse
Affiliation(s)
- A Hatzakis
- Department of Hygiene, Epidemiology and Medical Statistics, Athens University Medical School, Athens, Greece
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
4
|
Saraswat V, Norris S, de Knegt RJ, Sanchez Avila JF, Sonderup M, Zuckerman E, Arkkila P, Stedman C, Acharya S, Aho I, Anand AC, Andersson MI, Arendt V, Baatarkhuu O, Barclay K, Ben-Ari Z, Bergin C, Bessone F, Blach S, Blokhina N, Brunton CR, Choudhuri G, Chulanov V, Cisneros L, Croes EA, Dahgwahdorj YA, Dalgard O, Daruich JR, Dashdorj NR, Davaadorj D, de Vree M, Estes C, Flisiak R, Gadano AC, Gane E, Halota W, Hatzakis A, Henderson C, Hoffmann P, Hornell J, Houlihan D, Hrusovsky S, Jarčuška P, Kershenobich D, Kostrzewska K, Kristian P, Leshno M, Lurie Y, Mahomed A, Mamonova N, Mendez-Sanchez N, Mossong J, Nurmukhametova E, Nymadawa P, Oltman M, Oyunbileg J, Oyunsuren T, Papatheodoridis G, Pimenov N, Prabdial-Sing N, Prins M, Puri P, Radke S, Rakhmanova A, Razavi H, Razavi-Shearer K, Reesink HW, Ridruejo E, Safadi R, Sagalova O, Sanduijav R, Schréter I, Seguin-Devaux C, Shah SR, Shestakova I, Shevaldin A, Shibolet O, Sokolov S, Souliotis K, Spearman CW, Staub T, Strebkova EA, Struck D, Tomasiewicz K, Undram L, van der Meer AJ, van Santen D, Veldhuijzen I, Villamil FG, Willemse S, Zuure FR, Silva MO, Sypsa V, Gower E. Historical epidemiology of hepatitis C virus (HCV) in select countries - volume 2. J Viral Hepat 2015; 22 Suppl 1:6-25. [PMID: 25560839 DOI: 10.1111/jvh.12350] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [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] [Indexed: 12/23/2022]
Abstract
Chronic hepatitis C virus (HCV) infection is a leading cause of liver related morbidity and mortality. In many countries, there is a lack of comprehensive epidemiological data that are crucial in implementing disease control measures as new treatment options become available. Published literature, unpublished data and expert consensus were used to determine key parameters, including prevalence, viremia, genotype and the number of patients diagnosed and treated. In this study of 15 countries, viremic prevalence ranged from 0.13% in the Netherlands to 2.91% in Russia. The largest viremic populations were in India (8 666 000 cases) and Russia (4 162 000 cases). In most countries, males had a higher rate of infections, likely due to higher rates of injection drug use (IDU). Estimates characterizing the infected population are critical to focus screening and treatment efforts as new therapeutic options become available.
Collapse
Affiliation(s)
- V Saraswat
- Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, India
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
5
|
|
6
|
Saraswat V. Injury patterns in low intensity conflict. Indian J Anaesth 2009; 53:672-7. [PMID: 20640095 PMCID: PMC2900077] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/30/2009] [Indexed: 11/07/2022] Open
Abstract
SUMMARY Injury patterns and their outcome has been the subject of interest in all kinds of military conflicts. This retrospective study was conducted in a tertiary care hospital (Level I trauma centre) to find out the trends in injuries in low intensity conflict, adequacy of pre hospital treatment, mortality patterns and adequacy of treatment after reaching tertiary care hospital. 418 patients were treated over a period of two years. All were male and 76% younger than 30 years of age. 61% patients reported directly from the site of incident and 39% were transferred from other trauma centre. Two-third of patients (73.9%) reported with at least one limb injury and 44.9% with extremity injury alone. Multiple injuries were most common injury (29%). Head and neck injuries were seen in 20% patients and Thoracic and abdominal injuries were seen in 2.6% and 3.4% patients only. Most common mode of injury was Gunshot wound (41.4%), followed by splinter injuries (39.2%) and Road traffic accident(RTA) (19.4%). Overall mortality was 3.8% and inpatient mortality of 1.4%. Head and neck injuries were leading cause of death followed by thoracic injuries.
Collapse
Affiliation(s)
- V Saraswat
- Correspondence to: V Saraswat, Dy PMO (A), HQ, Western Air Command, Subroto Park, New Delhi – 110010, Email – ,
| |
Collapse
|
7
|
Gupta AK, Jain A, Jain A, Agrawal K, Saraswat V, Revathi S, Soni LK, Kaskhedikar SG. QSAR Analysis of Indazole Estrogens as Selective β-Estrogen Receptor Ligands: Rationalization of Physicochemical Properties. Med Chem 2007; 3:347-53. [PMID: 17627571 DOI: 10.2174/157340607781024384] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [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: 11/22/2022]
Abstract
Quantification of structure activity relationships was performed on a series of indazole estrogen analogs, for their relative beta estrogenic receptor agonist activity, in order to understand the essential structural requirements for selectivity of indazole estrogen analogs for beta-estrogenic receptor over alpha-estrogenic receptor. The de novo and Hansch approach suggested that the 3(rd) position of indazole nucleus (R(1)) is decisive for the selectivity of molecules towards beta-estrogenic receptor over alpha-estrogenic receptor. The study also depicted that the substitution of polar group at R(1) position might prove helpful in the beta-estrogenic receptor selectivity (ER(beta/alpha )).
Collapse
Affiliation(s)
- A K Gupta
- Department of Pharmaceutical Chemistry, B.R.Nahata College of Pharmacy, Mandsaur, India
| | | | | | | | | | | | | | | |
Collapse
|
8
|
Gupta D, Agarwal A, Nath SS, Goswami D, Saraswat V, Singh PK. Inflation with air via a facepiece for facilitating insertion of a nasogastric tube: a prospective, randomised, double-blind study. Anaesthesia 2007; 62:127-30. [PMID: 17223803 DOI: 10.1111/j.1365-2044.2006.04910.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [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: 11/30/2022]
Abstract
Insertion of a nasogastric tube is a routine procedure but during anaesthesia it is often difficult and time consuming. One hundred and sixty adults undergoing elective surgery under general anaesthesia were randomly divided into two groups. After induction of anaesthesia, neuromuscular blockade and tracheal intubation, a nasogastric tube was inserted through the nose with the head of the patient in the neutral position, either with or without prior inflation with air via a facepiece attached to a self-inflating bag applied firmly with the face. Insertion of the nasogastric tube was successful in 75/78 (96%) following inflation compared with 54/80 (68%) without inflation (p<0.001). In four patients receiving inflation, a fibreoptic endoscope was passed as far as the upper oesophageal sphincter; this revealed opening of the upper oesophageal sphincter during inflation.
Collapse
Affiliation(s)
- D Gupta
- Department of Anaesthesiology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow 226 014, India
| | | | | | | | | | | |
Collapse
|
9
|
Mildvan AS, Xia Z, Azurmendi HF, Saraswat V, Legler PM, Massiah MA, Gabelli SB, Bianchet MA, Kang LW, Amzel LM. Structures and mechanisms of Nudix hydrolases. Arch Biochem Biophys 2005; 433:129-43. [PMID: 15581572 DOI: 10.1016/j.abb.2004.08.017] [Citation(s) in RCA: 240] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2004] [Revised: 08/16/2004] [Indexed: 12/12/2022]
Abstract
Nudix hydrolases catalyze the hydrolysis of nucleoside diphosphates linked to other moieties, X, and contain the sequence motif or Nudix box, GX(5)EX(7)REUXEEXGU. The mechanisms of Nudix hydrolases are highly diverse in the position on the substrate at which nucleophilic substitution occurs, and in the number of required divalent cations. While most proceed by associative nucleophilic substitutions by water at specific internal phosphorus atoms of a diphosphate or polyphosphate chain, members of the GDP-mannose hydrolase sub-family catalyze dissociative nucleophilic substitutions, by water, at carbon. The site of substitution is likely determined by the positions of the general base and the entering water. The rate accelerations or catalytic powers of Nudix hydrolases range from 10(9)- to 10(12)-fold. The reactions are accelerated 10(3)-10(5)-fold by general base catalysis by a glutamate residue within, or beyond the Nudix box, or by a histidine beyond the Nudix box. Lewis acid catalysis, which contributes 10(3)-10(5)-fold to the rate acceleration, is provided by one, two, or three divalent cations. One divalent cation is coordinated by two or three conserved residues of the Nudix box, the initial glycine and one or two glutamate residues, together with a remote glutamate or glutamine ligand from beyond the Nudix box. Some Nudix enzymes require one (MutT) or two additional divalent cations (Ap(4)AP), to neutralize the charge of the polyphosphate chain, to help orient the attacking hydroxide or oxide nucleophile, and/or to facilitate the departure of the anionic leaving group. Additional catalysis (10-10(3)-fold) is provided by the cationic side chains of lysine and arginine residues and by H-bond donation by tyrosine residues, to orient the general base, or to promote the departure of the leaving group. The overall rate accelerations can be explained by both independent and cooperative effects of these catalytic components.
Collapse
Affiliation(s)
- A S Mildvan
- Department of Biological Chemistry, The Johns Hopkins School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205-2185, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Massiah M, Saraswat V, Azurmendi H, Mildvan A. Solution structure, mutagenesis, and NH exchange studies of the MutT enzyme–Mg2+-8-oxo-dGMP complex. J Mol Struct 2004. [DOI: 10.1016/j.molstruc.2003.12.060] [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: 11/17/2022]
|
11
|
Yogeeswari P, Sriram D, Saraswat V, Ragavendran JV, Kumar MM, Murugesan S, Thirumurugan R, Stables JP. Synthesis and anticonvulsant and neurotoxicity evaluation of N4-phthalimido phenyl (thio) semicarbazides. Eur J Pharm Sci 2003; 20:341-6. [PMID: 14592700 DOI: 10.1016/j.ejps.2003.08.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [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: 10/27/2022]
Abstract
The phenyl (thio) semicarbazide derivatives of phthalimido pharmacophore were synthesized and evaluated for their anticonvulsant and neurotoxic properties. Initial anticonvulsant screening was performed using intraperitoneal (i.p.), maximal electroshock-induced seizure (MES), subcutaneous pentylenetetrazole (scPTZ) and subcutaneous strychnine (sc STY)-induced seizure threshold tests in mice. Compound 2c afforded protection in all the three screens. Compounds except 1d, 2a and 2d showed no neurotoxicity up to 300 mg/kg. Compounds 1a, 1b, 2c, 2d, 2g and 2i were found to show oral MES activity. The compounds exhibited CNS depression and behavioral despair side effects, lesser than the conventional antiepileptic drugs.
Collapse
Affiliation(s)
- P Yogeeswari
- Medicinal Chemistry Research Laboratory, Pharmacy Group, Birla Institute of Technology and Science, Pilani 333031, India.
| | | | | | | | | | | | | | | |
Collapse
|
12
|
Satyanarayana S, Pathak SD, Saraswat V, Sarma YS, Bharadwaj R, Goorha YK. Tracheal lymphoepithelioma-like carcinoma: a case report. Indian J Cancer 2002; 39:112-5. [PMID: 12928566] [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: 03/04/2023]
Abstract
Lymphoepithelioma like carcinoma is rare in locations other than nasopharynx. We report the second case of this tumour in trachea, in a young female patient, who was managed with concomitent surgery, radiotherapy and chemotherapy. The patient is disease free in the one-year follow up. The tumour presented difficulties during intubation for general anaesthesia and during surgery. Association with Epstein-Barr virus was not found in our case.
Collapse
Affiliation(s)
- S Satyanarayana
- Department of Pathology, Armed Forces Medical College, Pune, Maharashatra, India
| | | | | | | | | | | |
Collapse
|
13
|
Lee J, Saraswat V, Koh I, Song KB, Park YH, Rhee SK. Secretory production of Arthrobacter levan fructotransferase from recombinant Escherichia coli. FEMS Microbiol Lett 2001; 195:127-32. [PMID: 11179640 DOI: 10.1111/j.1574-6968.2001.tb10509.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [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: 11/28/2022] Open
Abstract
Levan fructotransferase (LFTase) from Arthrobacter ureafaciens K2032 was expressed with N-terminal fusion of a LacZ-derived secretion motif (TMITNSSSVP) using the lac promoter system in recombinant Escherichia coli JM109 [pUDF-A81]. In flask cultures, recombinant enzyme activity was detected in culture media, and sequence analysis of N-terminal residues showed that about 40% of the extracellular recombinant LFTase had an authentic N-terminus. In a fed-batch bioreactor containing recombinant E. coli at high cell concentrations (OD(600)>200), the extracellular LFTase accumulated to 46000 U ml(-1) (approximately 2.0 g l(-1)) which was almost 40% of total (intra- and extracellular) recombinant LFTase. The synthesized recombinant enzyme was secreted soon after gene expression was induced by IPTG. Prolonged high secretion caused cell lysis and growth inhibition during the production phase in fed-batch cultures. When lactose was added by continuous feed mode, the secretion of recombinant LFTase and hence the cell lysis were significantly delayed in spite of the increased synthesis level. Therefore the induced cell culture of recombinant E. coli could grow up to a much higher cell concentration with continuing recombinant enzyme synthesis. In the case of the controlled feed of lactose, the maximum activities (U ml(-1)) of total and extracellular LFTase were nearly 100% and 70% higher, respectively.
Collapse
Affiliation(s)
- J Lee
- Microbial and BioProcess Engineering Laboratory, Korea Research Institute of Bioscience and Biotechnology, P.O. Box 115, Yusong, Taejon 305-600, South Korea.
| | | | | | | | | | | |
Collapse
|
14
|
Kim DY, Lee J, Saraswat V, Park YH. Glucagon-induced self-association of recombinant proteins in Escherichia coli and affinity purification using a fragment of glucagon receptor. Biotechnol Bioeng 2000; 69:418-28. [PMID: 10862680 DOI: 10.1002/1097-0290(20000820)69:4<418::aid-bit8>3.0.co;2-c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [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: 11/11/2022]
Abstract
The specific molecular interactions of alpha-helical peptide, human glucagon (i.e., intermolecular self-association and specific receptor-binding affinity) provided a rationale for using the glucagon as the fusion expression partner to achieve high productivity of foreign proteins both in vivo (in bacterial fusion-expression system) and in vitro (in affinity column chromatography). The fusion of glucagon peptide(s) effectively promoted homogeneous aggregate formation of recombinant proteins while avoiding intermolecular crosslinking by disulfide bridges. High sensitivity of the self-aggregation to sequence effects resulted from two distinct nonpolar domains of glucagon, determining specificity of molecular interaction and aggregate size of recombinant proteins. An N-terminal domain of glucagon molecule (Phe6-Tyr10-Tyr13) could be a certain hydrophobic moiety involved in intermolecular self-association (probably, via helix-helix docking), while a C-terminal domain (Phe22-Trp25-Leu26) seems to critically affect the oligomer size in the off-pathway aggregation of synthesized fusion proteins. An N-terminal extracellular domain of human glucagon receptor was recombinantly expressed in Escherichia coli, immobilized to a chromatography column, and efficiently renatured to a conformation that attains high specificity in interaction with N-terminus glucagon molecules of recombinant fusion proteins. Through column chromatography employing the receptor fragment as affinity ligand, the recombinant proteins were efficiently purified from total intracellular proteins, and the long-term ligand stability was evidently proven through multiple cyclic-purification experiments. Major scaffolds for using protein ligands are large-scale production in a low-cost expression system and long-term stable operation with selective-binding affinity. From this point of view, the extracellular fragment of human glucagon receptor used in this study seems to be a new potent ligand for fusion protein-based affinity chromatography.
Collapse
Affiliation(s)
- D Y Kim
- Microbial and BioProcess Engineering Laboratory, Korea Research Institute of Bioscience and Biotechnology (KRIBB), P.O. Box 115, Yusong, Taejon 305-600, South Korea
| | | | | | | |
Collapse
|
15
|
Saraswat V, Bisaria VS. Purification, characterization and substrate specificities of xylanase isoenzymes from Melanocarpus albomyces IIS 68. Biosci Biotechnol Biochem 2000; 64:1173-80. [PMID: 10923787 DOI: 10.1271/bbb.64.1173] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [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: 11/08/2022]
Abstract
The ascomycetous fungus Melanocarpus albomyces when grown on wheat straw produced seven extracellular xylanase isoenzymes, designated as la, Ib, Ic, IIa, lib, llc, and lId. All seven xylanases were purified to homogeneity by gel filtration and ion-exchange chromatography. The molecular mass (kDa) of la, lb, Ic, Ila, lIb, lIc, and lId were estimated to be 22.9, 20.7, 18.6, 31.3, 25.4, 38.5, and 34.3, respectively by SDS-PAGE, and 23.7, 20.5, 17.1, 31.7, 25.1, 39.8, and 32.2, respectively by gel filtration. The isoelectric points of Ia, lb, Ic, Ila and IIb were found to be 6.2, 6.3, 6.4, 3.7, and 4.4, respectively. The activity of the isoenzymes was dependent on the type of the xylan substrates; Xylanases Ia, lb, and Ic showed highest specific activity toward larchwood xylan (an arabinoglucuronoxylan), IIa and Ilc toward birchwood xylan (a glucuronoxylan), and llb and IId toward beechwood xylan (a glucuronoxylan). Four isoenzymes la, lb, Ic, and Ila had an arabinose-releasing property on larchwood xylan. Application of specific isoenzymes as prebleaching agents in paper manufacture is proposed.
Collapse
Affiliation(s)
- V Saraswat
- Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology, Hauz Khas, New Delhi, India
| | | |
Collapse
|
16
|
Saraswat V, Kim DY, Lee J, Park Y. Effect of specific production rate of recombinant protein on multimerization of plasmid vector and gene expression level. FEMS Microbiol Lett 1999; 179:367-73. [PMID: 10518739 DOI: 10.1111/j.1574-6968.1999.tb08751.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [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: 11/29/2022] Open
Abstract
In fed-batch cultures of recombinant Escherichia coli BL21(DE3)[pT7-G3IL2] at high cell concentration, the post-induction specific growth rate was carefully regulated by controlled medium feed to maximize the synthesis level of recombinant fusion interleukin-2, G3.IL-2. A maximum concentration of G3.IL-2 (11.25 g l(-1)) was achieved in the induced recombinant culture growing at the rate of 0.056 h(-1). A steep decrease in the expression level of G3.IL-2 was observed at the post-induction specific growth rates higher than its optimal value (0.056 h(-1)). In the induced recombinant cultures, plasmid multimerization was observed and highly dependent on specific growth and production rate: a higher post-induction specific growth rate and an increased specific production rate tended to significantly promote it much further. Moreover, plasmid stability was found to decrease rapidly in a faster growing culture.
Collapse
Affiliation(s)
- V Saraswat
- Biochemical Process Engineering R.U., Korea Research Institute of Bioscience and Biotechnology (KRIBB), P.O. Box 115, Yusong, Taejon, South Korea
| | | | | | | |
Collapse
|
17
|
Mills CO, Milkiewicz P, Saraswat V, Elias E. Cholyllysyl fluroscein and related lysyl fluorescein conjugated bile acid analogues. Yale J Biol Med 1997; 70:447-57. [PMID: 9626765 PMCID: PMC2589346] [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] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
There have been attempts to couple bile acids to fluorescein to permit their visualization during studies of physiology and pathophysiology. Although conjugation has been achieved by many, the product differed in many respects from the parent bile acid congener. We describe lysylfluorescein conjugated bile acid analogues (LFCBAA) synthesized in our laboratory as model divalent "unipolar" molecules. We have determined LFCBAA properties including their water:octanol partition coefficient, HPLC retention time and critical micellar concentration and compared them with their parent bile acid congeners. Cholyl lysylfluorescein (CLF) and lithocholyl lysylfluoroscein (LLF) have properties similar to cholylglycine (CG) and glycolithocholate (GLC), respectively. In human and rat hepatocytes uptake of CLF follows Michaelis-Menten kinetics with K(m) and Vmax similar to CG. Biliary excretion rates of CLF and LLF closely resemble those of CG and GLC in both normal and mutant TR- rats which lack the multiorganic anion transporter (MOAT), strongly supporting the notion that CLF and LLF are substrates for the canalicular bile salt transporter (cBST). The close similarity of hepatocyte uptake and biliary secretion of these LFCBAA and their parent bile acid congeners makes them potentially useful probes for the intracellular visualization of bile salt movement and deposition in various models of bile formation and secretion.
Collapse
Affiliation(s)
- C O Mills
- Liver and Hepatobiliary Unit, Queen Elizabeth Hospital, Birmingham, United Kingdom
| | | | | | | |
Collapse
|
18
|
Bhargava DK, Dasarathy S, Chowdhry GC, Anand AC, Saraswat V. Upper gastrointestinal bleeding due to hookworms (Ancylostoma duodenale)--a case report. Endoscopy 1993; 25:548-9. [PMID: 8287823 DOI: 10.1055/s-2007-1010399] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
|
19
|
Srivastava DN, Chakravarti AL, Saxena R, Saraswat V, Kulshrestha A, Gujral RB, Phadke RV. Sonographic appraisal of endobiliary ascaris with calculi. Am J Gastroenterol 1991; 86:527-8. [PMID: 2012059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
|