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Zagariya A, Bhat R, Uhal B, Navale S, Freidine M, Vidyasagar D. Cell death and lung cell histology in meconium aspirated newborn rabbit lung. Eur J Pediatr 2000; 159:819-26. [PMID: 11079194 DOI: 10.1007/s004310000581] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
UNLABELLED Meconium aspiration syndrome (MAS) is a major cause of newborn mortality and morbidity. In this study we investigated the inflammatory responses and morphological changes in the newborn lung to debris-free meconium instillation. We developed a model for studies of MAS using 2-week-old rabbit pups. Cell death was assessed by DNA staining and detection of DNA fragmentation by in situ end labeling. Cell death was seen in association with an increase of inflammatory cytokines levels, studied by ELISA. Necrotic cells were detected by staining of lavage cells with ethidium bromide and 4',6'-diamino-2'-phenylidon. Meconium instillation resulted selectively in loss of airway and alveolar epithelial cells followed by cell death, which increased with time. Necrotic cells looked smaller and damaged with maximal counts at 24 h after instillation. CONCLUSION Meconium instillation into lungs caused massive cell death, possibly by apoptosis, and necrosis that may have been activated by the inflammatory cytokine production.
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Tiwari A, Kumar DP, Bhat R. An efficient and cost-effective procedure for preparing samples for differential scanning calorimetry experiments. Anal Biochem 2000; 284:406-8. [PMID: 10964427 DOI: 10.1006/abio.2000.4703] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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78
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Gordon EJ, Bhat R, Liu Q, Wang YF, Tackney C, Prince AM. Immune responses to hepatitis C virus structural and nonstructural proteins induced by plasmid DNA immunizations. J Infect Dis 2000; 181:42-50. [PMID: 10608749 DOI: 10.1086/315162] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
DNA-based immunizations have been used to elicit cellular immunity to hepatitis C virus (HCV) proteins in mice. Mice were immunized by intramuscular or intradermal injections of plasmid DNA derived from a near-full-length HCV genotype 1b genomic clone (pRC/B2) or individual genomic clones. These immunizations induced cytotoxic T lymphocytes (CTLs), as revealed in standard chromium-release assays that used syngeneic peptide-pulsed or transfected target cells. These assays identified four CTL epitopes within the capsid, E1, and E2 regions of the polyprotein sequence of HCV genotype 1a that were cross-reactive with HCV genotype 1b. Additionally, CTLs derived from mice immunized with either NS3 or NS5 specifically lysed target cells sensitized to either the genotype 1a or 1b gene products. Nucleic acid immunizations also generated humoral immunity to HCV proteins, as detected by anti-HCV reactivity to NS3 and capsid in ELISAs and immunoblot assays.
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79
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Bhat R. Characteristics of private medical practice in India: a provider perspective. Health Policy Plan 1999; 14:26-37. [PMID: 10351467 DOI: 10.1093/heapol/14.1.26] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Supply factors, depicted by input market conditions and government regulations, and demand factors, depicted by financing mechanisms and utilization patterns, are likely to determine the shape and character of private medical practice. The interaction of this complex set of factors will have considerable implications for the cost access and quality of services offered by this sector. Understanding these characteristics from a provider perspective is imperative to influence the behaviour of providers in this sector. This paper describes some of the important characteristics of private medical practice using a case study of an urban district in India, Ahmedabad, and analyzes their implications. Using survey data of 130 private doctors in the allopathic system, the paper describes broad characteristics of private medical practice using parameters such as growth of private practice, patient load and referrals within the sector, payment methods and determinants, patient concerns, and risks associated with private practice. The paper presents views on the prevalence of various undesirable practices in the private medical sector. It also discusses the awareness of providers about selected important regulations. The findings suggest that growing capital intensity due to cost of location, medical equipment and technology, and financial sources of capital investments are some unfavourable environmental factors experienced by private providers. The findings also indicate a high prevalence of various undesirable practices and low awareness of the objectives of important legislation among practicing doctors. Lack of awareness of important and relevant legislation raises serious questions about the implementation of these laws. The paper identifies the strong need for instituting and implementing an effective continuing medical education programme for practicing doctors, and linking it with their registration and continuation of their license to practice. The paper also suggests that cost of health care, access and quality problems will worsen with the growth of the private sector. The public policy response to check some of the undesirable consequences of this growth is critical and should focus on strengthening the existing institutional mechanisms to protect patients, developing and implementing an appropriate regulatory framework and strengthening the public health care delivery system. The study also discusses various other policy implications arising.
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80
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Kaushik JK, Bhat R. A mechanistic analysis of the increase in the thermal stability of proteins in aqueous carboxylic acid salt solutions. Protein Sci 1999; 8:222-33. [PMID: 10210200 PMCID: PMC2144102 DOI: 10.1110/ps.8.1.222] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The stability of proteins is known to be affected significantly in the presence of high concentration of salts and is highly pH dependent. Extensive studies have been carried out on the stability of proteins in the presence of simple electrolytes and evaluated in terms of preferential interactions and increase in the surface tension of the medium. We have carried out an in-depth study of the effects of a series of carboxylic acid salts: ethylene diamine tetra acetate, butane tetra carboxylate, propane tricarballylate, citrate, succinate, tartarate, malonate, and gluconate on the thermal stability of five different proteins that vary in their physico-chemical properties: RNase A, cytochrome c, trypsin inhibitor, myoglobin, and lysozyme. Surface tension measurements of aqueous solutions of the salts indicate an increase in the surface tension of the medium that is very strongly correlated with the increase in the thermal stability of proteins. There is also a linear correlation of the increase in thermal stability with the number of carboxylic groups in the salt. Thermal stability has been found to increase by as much as 22 C at 1 M concentration of salt. Such a high thermal stability at identical concentrations has not been reported before. The differences in the heat capacities of denaturation, deltaCp for RNase A, deduced from the transition curves obtained in the presence of varying concentrations of GdmCl and that of carboxylic acid salts as a function of pH, indicate that the nature of the solvent medium and its interactions with the two end states of the protein control the thermodynamics of protein denaturation. Among the physico-chemical properties of proteins, there seems to be an interplay of the hydrophobic and electrostatic interactions that lead to an overall stabilizing effect. Increase in surface free energy of the solvent medium upon addition of the carboxylic acid salts appears to be the dominant factor in governing the thermal stability of proteins.
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81
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Bhat R, Chandra B, Biswas K. Classification and Semantics of Objects and Relations of Object-Relation-Object Construct. JOURNAL OF INTELLIGENT SYSTEMS 1998. [DOI: 10.1515/jisys.1998.8.3-4.383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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82
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Bhat R, Chari G, Meller J, Ramarao S, Vidyasagar D. Bile flow and composition in preterm, term and infant baboons. BIOLOGY OF THE NEONATE 1997; 72:235-42. [PMID: 9339295 DOI: 10.1159/000244489] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
UNLABELLED We studied the maturational changes in bile composition, bile flow and choleretic effects of sodium taurocholate and secretin in preterm (160 +/- 2 days, n = 4, group I), term (184 +/- 2 days, n = 4, group II), 7-day postnatal age (n = 5, group III) and 60-day-old (n = 5, group IV) baboons. The canalicular bile flow was determined by 14C-erythritol clearance. RESULTS Gall bladder volume increased from group I to group III (0.08 +/- 0.06 to 1.06 +/- 0.93 ml). Bile flow increased significantly from group I to IV (0.13 +/- 0.05 to 0.34 +/- 0.07 microliter/min/g liver weight, p < 0.05). This was associated with significant increases in total bile acid excretion (16 +/- 3.6 to 31 +/- 2.5 mEq/l, p < 0.05). The composition of bile also showed maturational changes with increasing postnatal age. Sodium taurocholate and secretin increased the bile flow significantly in all groups. CONCLUSION Data from these studies clearly demonstrate that the bile flow and bile acid excretion is immature in preterm and term baboons when compared to 7- and 60-day-old baboons. The present studies also suggest that baboons can be used as a model to study the postnatal maturation of hepatic excretory function.
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83
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Bhat R, Bresnick E. Glycine N-methyltransferase is an example of functional diversity. Role as a polycyclic aromatic hydrocarbon-binding receptor. J Biol Chem 1997; 272:21221-6. [PMID: 9261130 DOI: 10.1074/jbc.272.34.21221] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The cytochrome P-4501A1 (CYP1A1) gene is regulated by several trans-acting factors including the 4 S polycyclic aromatic hydrocarbon (PAH)-binding protein, which has recently been identified as glycine N-methyltransferase (GNMT) (Raha, A., Wagner, C., Macdonald, R. G., and Bresnick, E. (1994) J. Biol. Chem. 269, 5750-5756). The role of GNMT as a 4 S PAH-binding protein in mediating the induction of cytochrome P-4501A1 has been investigated further. GNMT cDNA, which was cloned into a pMAMneo vector containing the Rous sarcoma virus promoter and the neomycin resistance gene, was stably transfected into D422 Chinese hamster ovary (CHO) cells. Several positive clones were selected by reverse transcription-polymerase chain reaction and assayed for the expression of recombinant protein. Western blot analysis indicated the expression of significant levels of the 4 S protein in the stably transfected CHO cells (CHO-GNMT). Cytosolic preparations from the CHO-GNMT showed high benzo[a]pyrene (B[a]P) binding but no 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) binding activity when compared with clones transfected with the pMAMneo vector alone (CHO-neo) or the parental CHO cells. Challanging the CHO-GNMT cells with 4 microM B[a]P resulted in elevated levels of CYP1A1 mRNA. Equally effective in inducing CYP1A1 mRNA were benzo[e]pyrene and 3-methylcholanthrene. On the other hand, TCDD did not induce CYP1A1 gene expression in these cells. B[a]P-treated CHO-GNMT, expressing the 4 S protein, also showed CYP1A1 protein by Western blotting and exhibited ethoxyresorufin-O-deethylase activity; neither the CHO-neo or parental CHO cells were positive for any of these measures. No Ah receptor message or protein was detectable in the parental CHO, CHO-neo, or CHO-GNMT cells. Furthermore, no XRE binding activity was observed in TCDD-treated cytosolic preparations or nuclear extracts from CHO-GNMT cells that were treated with TCDD. These studies unequivocally establish that GNMT is a PAH-binding protein that can mediate the induction of CYP1A1 by PAHs such as B[a]P through an Ah receptor-independent pathway.
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84
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Bhat R, Wagner C, Bresnick E. The homodimeric form of glycine N-methyltransferase acts as a polycyclic aromatic hydrocarbon-binding receptor. Biochemistry 1997; 36:9906-10. [PMID: 9245423 DOI: 10.1021/bi970159x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In the rat, cytochrome P4501A1 gene expression is thought to be regulated by several trans-acting factors including the 4S polycyclic aromatic hydrocarbon (PAH)-binding protein, which was recently identified as glycine N-methyltransferase [Raha, A., Wagner, C., MacDonald, R. G., and Bresnick, E. (1994) J. Biol. Chem. 268, 5750-5756]. Glycine N-methyltransferase (GNMT) is one of those unique proteins which exhibit diversity in function. Different subunit configurations are involved in its enzymatic role as a methyltransferase and as PAH-binding receptor. Here we report a systematic study of the oligomeric state of GNMT in the presence of benzo[a]pyrene (B[a]P) in vivo and in vitro. We have used chemical cross-linking and denaturing polyacrylamide gel electrophoresis to show that the B[a]P-binding unit of GNMT is a homodimer. We recently reported that phosphorylation is involved in the interaction of B[a]P with the 4S PAH-binding protein [Bhat, R., Weaver, J. A., Wagner, C., Bodwell, J. E., and Bresnick, E. (1996) J. Biol. Chem. 271, 32551-32556]. In the present study, this observation has been amplified by using bacterially expressed GNMT, which was post-translationally modified by a reticulocyte lysate and ATP-generating system. This modification was also accompanied by the formation of homodimers in the presence of B[a]P. These results indicate that post-translational modification is involved in determining the final configuration, i.e., dimeric form, of GNMT which then acts as a PAH-binding receptor.
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85
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Bhat R, Weaver JA, Wagner C, Bodwell JE, Bresnick E. ATP depletion affects the phosphorylation state, ligand binding, and nuclear transport of the 4 S polycyclic aromatic hydrocarbon-binding protein in rat hepatoma cells. J Biol Chem 1996; 271:32551-6. [PMID: 8955080 DOI: 10.1074/jbc.271.51.32551] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
In the rat, cytochrome P4501A1 gene expression is thought to be regulated by several trans-acting factors including the 4 S polycyclic aromatic hydrocarbon (PAH)-binding protein. Phosphorylation and dephosphorylation have been suggested to influence the function of many cytosolic receptors and transcription factors. The ATP level within H4IIE rat hepatoma cells could be depleted by treatment with sodium azide or 2,4-dinitrophenol; restoration of the original ATP levels occurred with addition of glucose to the cell culture. ATP depletion reduced the phosphate content of the 4 S protein by approximately 25-30%, which lowered the binding of benzo[a]pyrene (B[a]P) to the 4 S protein by >60%. This effect could not be reversed by the addition of ATP to the binding reaction mixtures. Alkaline phosphatase treatment of the purified 4 S protein in a cell-free system also reduced the B[a]P binding to the protein. Cells treated with a protein phosphatase inhibitor, okadaic acid, and a protein kinase inhibitor, staurosporin, affected the B[a]P binding of the 4 S protein positively and negatively, respectively. These data suggested that phosphorylation is involved in the interaction of the 4 S protein with the PAH. The nuclear translocation of the predominantly cytosolic binding protein has been investigated after ligand binding. Western blots with the immunopurified 4 S PAH-binding protein from cytosolic and nuclear lysates showed significant differences in the distribution of the 4 S receptor between cytosolic and nuclear compartments in control and ATP-depleted cells. Ligand binding stimulated the movement of the receptor into the nucleus, which was completely blocked by reducing the intracellular ATP concentration. These findings provide new information on the role of ATP and phosphorylation on the interaction of B[a]P with 4 S PAH-binding protein and its nuclear translocation.
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86
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Huang LQ, Paiva A, Bhat R, Wong M. Characterization of large, heterogeneous proteins by electrospray ionization-mass spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 1996; 7:1219-1226. [PMID: 24203154 DOI: 10.1016/s1044-0305(96)00102-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/1995] [Revised: 07/02/1996] [Accepted: 07/02/1996] [Indexed: 06/02/2023]
Abstract
Characterization of heterogeneous proteins as large as 150,000 u was performed by a quadrupole mass spectrometer by using electrospray ionization (ESI). We were able to determine not only the molecular weight, but the detailed heterogeneity for the large glycoproteins as well. The successful application was facilitated by the optimization of the instrument in the high mass-to-charge range up to m/z 4000, where the multiply charged envelopes of the 150,000-u glycoproteins were found. For the analysis of clinically important monoclonal antibodies mass spectral data acquired by this method were consistent with the carbohydrate analysis and were useful in resolving the monosaccharide data into glycoform variations. In the case of the characterization of other large, heterogeneous proteins such as elongation factor 3 and bovine serum albumin, the quadrupole ESI mass spectrometer provided adequate mass resolution and high mass measurement accuracy to discern the modification and degradation of the proteins.
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87
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Radha C, Salotra P, Bhat R, Bhatnagar R. Thermostabilization of protective antigen--the binding component of anthrax lethal toxin. J Biotechnol 1996; 50:235-42. [PMID: 8987626 DOI: 10.1016/0168-1656(96)01569-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Protective antigen (PA) is the binding component of anthrax lethal toxin produced by Bacillus anthracis, and constitutes a major ingredient of the vaccine against anthrax. PA and lethal factor when added together are cytolytic to mouse macrophages and J774G8 macrophage cell line. This in vitro lethal toxicity assay is very useful in understanding the molecular mechanism of action of lethal toxin. Effective utilization of PA is, however, hampered due to its thermolability. On prolonged storage at 37 degrees C, PA was found to lose its activity almost completely. The effect of solvent additives like trehalose, sorbitol, xylitol, sodium citrate and magnesium sulphate on the thermal stabilization of PA was examined. The results indicated an increase in the stability of PA when the incubation at 37 degrees C was carried out in the presence of solvent additives used in the 1-3 M range. Magnesium sulphate helped retain the activity up to 82.7% against the control in which no additive was used, as judged by cytolytic assay using J774G8 macrophage cell line. Trehalose or sodium citrate also showed an appreciable protection of PA activity, while sorbitol or xylitol were not very effective. Competitive binding assay using radiolabeled PA showed that PA had lost capacity of binding to macrophage cells on prolonged incubation at 37 degrees C. Circular dichroism results at 4, 18, and 37 degrees C indicated an increase in secondary structure at 37 degrees C relative to that at 4 or 18 degrees C, supporting the activity data.
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88
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Bhat R. Regulating the private health care sector: the case of the Indian Consumer Protection Act. Health Policy Plan 1996; 11:265-79. [PMID: 10160372 DOI: 10.1093/heapol/11.3.265] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Private medical provision is an important constituent of health care delivery services in India. The quality of care provided by this sector is a critical issue. Professional organizations such as the Medical Council of India and local medical associations have remained ineffective in influencing the behaviour of private providers. The recent decision to bring private medical practice under the Consumer Protection Act (COPRA) 1986 is considered an important step towards regulating the private medical sector. This study surveyed the views of private providers on this legislation. They believe the COPRA will be effective in minimizing malpractice and negligent behaviour, but it does have adverse consequences such as an increase in fees charged by doctors, an increase in the prescription of medicines and diagnostics, an adverse impact on emergency care, etc. The medical associations have also argued that the introduction of COPRA is a step towards expensive, daunting and needless litigation. A number of other concerns have been raised by consumer forums which focus on the lack of standards for private practice, the uncertainty and risks of medicines, the effectiveness of the judiciary system, and the responsibility of proving negligence. How relevant are these concerns? Is the enactment of COPRA really appropriate to the medical sector? The paper argues that while this development is a welcome step, we need to comprehensively look into the various quality concerns. The effective implementation of COPRA presumes certain conditions, the most important being the availability of standards. Besides this, greater involvement of professional organizations is needed to ensure appropriate quality in private practice, since health and medical cases are very different from other goods and services. The paper discusses the results of a mailed survey and interview responses of 130 providers from the city of Ahmedabad, India. The questionnaire study was designed to assess the opinion of providers on various implications of the COPRA. We also analyze the data on cases filed with the Consumer Disputes and Redressal Commission in Gujarat since 1991. Four selected cases filed with the National Commission on Consumers Redressal are discussed in detail to illustrate various issues affecting the implementation of this Act.
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89
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Ali N, Ola S, Bhat R. Subunit structure of Ca++ dependent soluble goat hepatic lectin: evidence that it has antigenic structural relationship with soluble 14K lectin family. BIOCHEMISTRY AND MOLECULAR BIOLOGY INTERNATIONAL 1996; 39:961-73. [PMID: 8866013 DOI: 10.1080/15216549600201112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The subunit structure of soluble goat hepatic lectin was studied by determining molecular weight under nondenaturing conditions by gel filtration and denaturing conditions by SDS PAGE. Affinity purified lectin was subjected to HPLC on asahipack column equilibrated with 10 mM Tris-HCl pH 7.5, containing 1 mM CaCl2, 1mM 2-mercaptoethanol and 0.1M NaCl. The lectin was eluted under single peak at retention time of 12 min. corresponding to molecular weight of 38Kd. On SDS-PAGE in the presence and absence of 2-mercaptoethanol protein moved as single band with Rm 0.45, which corresponds to molecular weight of 20 Kd. The results suggest that soluble goat hepatic lectin is a dimmer of identical subunits which are linked together by noncovalent interactions. The interaction of monoclonal antibodies raised against soluble goat hepatic lectin (MGHL/20) with hemagglutinin from different species as sheep, human, rat, bovine and chicken was studied in PBS by solid phase binding assay. MGHL/20 showed 29.89% binding with these lectin. However no binding was found with Ca++ dependent membrane bound lectin. These results indicate that soluble goat hepatic lectin possesses antigenic structural relationship with soluble 14 K lectin family.
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Abstract
The expansion of the private sector in India has forced the passages of a number of regulations to promote quality of care and protect consumers. This has expanded the role of government in developing and enforcing regulations in three areas of the health sector: drugs, medical practice, and health facilities. These regulations have been promulgated by both national and state governments. Three particular Acts are examined: the Consumer Protection Act, Medical Councils, and the Nursing Home Act. These Acts have provided basic guidelines for regulation of certain aspects of the health sector, but have also created new challenges, as consumers have become more involved in monitoring health service delivery. The challenge for the future will be to ensure the quality and efficiency of health services in both the public and private sectors through these regulatory mechanisms while seeking to promote national health objectives.
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91
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Bhat R, Weaver JA, Sterling KM, Bresnick E. Nuclear transcription factor Oct-1 binds to the 5'-upstream region of CYP1A1 and negatively regulates its expression. Int J Biochem Cell Biol 1996; 28:217-27. [PMID: 8729008 DOI: 10.1016/1357-2725(95)00122-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The cytochrome P450-dependent monooxygenases, which represent an extended superfamily, catalyze the biotransformation of many endogenous and exogenous substances. One of these hemoproteins, cytochrome P4501A1, is most closely associated with the bioactivation of polycyclic aromatic hydrocarbons such as benzo[a]pyrene, which may play a role in environmental carcinogenesis. A negative regulatory element (NRE) has been localized in the 5'-upstream region of the cytochrome P4501A1 gene (CYP1A1) at -843 to -746 base pairs from the site of transcription. The purpose of this research was to define any interactions of trans-acting proteins with this cis element. Rat liver nuclei were used as the source of trans-acting proteins and a biotinylated NRE-bearing fragment (-782 to -843 bp) from a plasmid which contained the CYP1A1 was prepared by the polymerase chain reaction technique. Gel mobility shift assays were used to demonstrate interactions between this NRE fragment and nuclear proteins. The specific binding to an octamer-containing motif in the 5'-upstream region of CYP1A1 was demonstrated; this was used as a step in the partial purification from rat liver of the transcription factor, Oct-1. Conventional chromatographic procedures and DNA recognition site affinity chromatography were also used. HepG2 human hepatoma cells were transfected with both pMCoLUC+ which contains the luciferase gene as a reporter gene driven by the CYP1A1 promoter (including the NRE), and an Oct-1 expression vector. Luciferase activity/mg protein in the doubly-transfected cells was significantly lower than in cells containing only pMCoLUC+. A nuclear transcription factor Oct-1 interacts with a portion of the NRE of the rat CYP1A1, suppressing the expression of this gene. These findings may help to explain the low level of basal expression of CYP1A1 in mammalian systems.
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Yeh CN, McNeil LE, Nahory RE, Bhat R. Measurement of the In0.52Al0.48As valence-band hydrostatic deformation potential and the hydrostatic-pressure dependence of the In0.52Al0.48As/InP valence-band offset. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:14682-14687. [PMID: 9980803 DOI: 10.1103/physrevb.52.14682] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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93
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Bhat R, John E, Chari G, Shankararao R, Fornell L, Gulati A, Vidyasagar D. Renal actions of endothelin-1 in newborn piglets: dose-effect relation and the effects of receptor antagonist (BQ-123) and cyclooxygenase inhibitor (indomethacin). THE JOURNAL OF LABORATORY AND CLINICAL MEDICINE 1995; 126:458-69. [PMID: 7595031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Although the effects of endothelin-1 (ET-1) on intact or perfused adult kidney are well understood, its effects in the fetus and the newborn have not been well studied. We examined the effects of infusions of 25, 50, and 100 ng/kg of ET-1 per minute on mean blood pressure (MBP), cardiac index (CI), renal blood flow (RBF), glomerular filtration rate (GFR), and urine volume (UV) in 7- to 10-day-old piglets (n = 24). In addition, the effects of pretreatment with a receptor antagonist (BQ-123) and with a cyclooxygenase inhibitor (indomethacin) were studied in 12 separate piglets. ET-1 produced a dose- and level-dependent decrease in CI (60%), RBF (50% to 75%), GFR (66% to 80%) and MBP 15% to 17%. These changes returned to 75% to 80% of baseline 60 minutes after discontinuation of ET-1. Low-dose infusion (25 ng/kg) did not result in any changes in systemic or renal hemodynamics. Plasma half-life of ET-1 in piglets was 2.1 +/- 0.4 minutes. Pretreatment with the specific ETA receptor antagonist BQ-123 completely blocked the ET-1-induced systemic and renal hemodynamic changes. Indomethacin blocked the ET-1-induced rise in MBP but failed to block any renal changes. In fact, indomethacin accentuated the changes induced by ET-1, especially the changes in RBF, RVR, and GFR. Studies of receptor binding in the renal cortex and medulla showed that, in the cortex, the Ki value for ET-1 was 6.32 +/- 1.57, and for ET-3 it was 20.05 +/- 4.38 (p < 0.05); in the medulla, the Ki values were similar for both ET-1 and ET-3. These results indicate that in piglets the renal vascular bed is highly sensitive to ET-1, and its effects are predominantly mediated through ETA receptors.
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Iyer RS, Singh G, Rebello S, Roy S, Bhat R, Vidyasagar D, Gulati A. Changes in the concentration of endothelin-1 during development of hypertensive rats. Pharmacology 1995; 51:96-104. [PMID: 8584577 DOI: 10.1159/000139321] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The concentration of endothelin-1 (ET-1) in the brain regions, heart, and throacic aorta of 1-, 4-, 6- and 8-week-old spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats was determined using radioimmunoassay. ET-1-like immunoreactivity in the brain regions of 1-week-old WKY and SHR rats was lower compared to older (6 and 8 weeks) rats. ET-1 levels in the central nervous system gradually increased with age in both SHR and WKY rats. However, the concentration of ET-1 in 8-week-old rats was lower in the brain regions of SHR compared to WKY rats. The concentration of ET-1 in the thoracic aorta of SHR (224 +/- 43 pg/g tissue) rats was lower than that of WKY (452 +/- 11 pg/g tissue) rats at 1 week of age. However, ET-1 levels gradually increased with age in SHR rats. By 8 weeks of age, levels of ET-1 in SHR (623 +/- 33 pg/g tissue) rats were higher compared to WKY (439 +/- 62 pg/g tissue) rats. In the heart, ET-1 levels were similar in WKY and SHR rats at 4 weeks of age, but at 8 weeks of age ET-1 levels were higher in SHR rats (364 +/- 33 pg/g tissue) compared to WKY rats (260 +/- 31 pg/g tissue). It appears that at 8 weeks of age when hypertension is fully expressed in rats, ET-1 levels are lower in the central nervous system and are higher in the thoracic aorta and heart of SHR compared to WKY rats.
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95
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Muztar J, Chari G, Bhat R, Ramarao S, Vidyasagar D. A High-Performance Liquid Chromatographic Procedure for the Separation of Cocaine and Some of Its Metabolites from Acepromazine, Ketamine, and Atropine from Serum. ACTA ACUST UNITED AC 1995. [DOI: 10.1080/10826079508009314] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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96
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97
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Maslar JE, Dorsten JF, Bohn PW, Agarwala S, Adesida I, Caneau C, Bhat R. Electron-phonon interactions in n-type In0.53Ga0.47As and In0.52Al0.48As studied by inelastic light scattering. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 50:17143-17150. [PMID: 9976114 DOI: 10.1103/physrevb.50.17143] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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98
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Bhat R, Hadi SM. DNA breakage by tannic acid and Cu(II): generation of active oxygen species and biological activity of the reaction. Mutat Res 1994; 313:49-55. [PMID: 7519310 DOI: 10.1016/0165-1161(94)90032-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Tannic acid was shown to reduce oxygen to superoxide anion. In the presence of Cu(II), the hydroxyl radical and hydrogen peroxide were formed. Strand scission reaction was shown to account for the biological activity of tannic acid as assayed by bacteriophage inactivation. The inactivating activity occurs through the Fenton pathway for free radical production and subsequent DNA cleavage by these radicals.
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99
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Bhat R, Hadi SM. DNA breakage by tannic acid and Cu(II): sequence specificity of the reaction and involvement of active oxygen species. Mutat Res 1994; 313:39-48. [PMID: 7519309 DOI: 10.1016/0165-1161(94)90031-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Tannic acid has numerous chemical, food and pharmacological applications. In the presence of Cu(II) and molecular oxygen it was found to cause breakage of calf thymus DNA and supercoiled plasmid DNA. Treatment of lambda phage DNA with tannic acid protected cleavage with restriction endonucleases DraI and EcoRI* but not with SmaI and HaeIII. The results indicate that under the conditions used tannic acid preferably binds to AT base pairs. Restriction analysis of open circular form II plasmid DNA generated by tannic acid-Cu(II) treatment further showed that the strand breakage is caused at specific sites or sequences. In this reaction Cu(I) was shown to be an essential intermediate by using the Cu(I) sequestering reagents neocuproine and bathocuproine. By using job plots, we established that in the absence of DNA, six Cu(II) ions can be reduced by one tannic acid molecule. The involvement of active oxygen species in the reaction was established by the inhibition of DNA breakage by superoxide dismutase, thiourea, mannitol, formate and catalase.
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100
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Bhat R, Hadi SM. Photoinactivation of bacteriophage lambda by kojic acid and Fe(III): role of oxygen radical intermediates in the reaction. BIOCHEMISTRY AND MOLECULAR BIOLOGY INTERNATIONAL 1994; 32:731-735. [PMID: 8038723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Kojic acid, a bacterial metabolite, intensively used in food and pharmaceutical industry has been reported to induce strand breaks in double stranded DNA. This genotoxic action of kojic acid was tested directly by using bacteriophage inactivation. The inactivating activity is mediated through DNA strand scissions by oxygen free radical intermediates. This was tested by quenching of the inactivation reaction in presence of radical scavengers. These results indicate the usefulness of a simple system to test various risk factors in dietary components.
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