126
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Chadha R, Bagga D, Malhotra CJ, Mohta A, Dhar A, Kumar A. The embryology and management of congenital pouch colon associated with anorectal agenesis. J Pediatr Surg 1994; 29:439-46. [PMID: 8201516 DOI: 10.1016/0022-3468(94)90588-6] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Forty-one infants with a pouch colon malformation accompanied by a high anorectal anomaly were treated between January 1986 and December 1990. The 41 cases constituted 9% of all anorectal malformations and 15.2% of high defects managed during this period. There were 32 boys and nine girls; three of the girls had an associated cloaca. Many of the babies presented in poor condition, with gross abdominal distension caused by the distended colonic pouch. The typical radiological feature was an enormously distended colonic shadow occupying more than 50% of the width of the abdomen. At the time of surgery, the patients were classified into 4 subgroups based on the length of the normal colon. All but three infants had a high wide fistula, with the genitourinary tract consisting of a colovesical fistula in males and a colovaginal or colocloacal fistula in females. Frequent associated malformations included duplication of the appendix and vesicoureteric reflux. The operations performed initially were a window colostomy of the pouch with or without division-ligation of the fistula, end-colostomy after fistula ligation, or subtotal pouch excision with tubularization of the remaining colon and end-colostomy. Thirteen of the 41 patients have undergone a definitive pull-through operation using the posterior sagittal approach, including two children in whom one-stage reconstruction of a cloaca was performed. Standardized management of this complex anomaly is proposed for the initial operation and for definitive reconstruction.
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127
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Dhar A, Shukla S. Electrotransjection of pp60v-src monoclonal antibody inhibits activation of phospholipase C in platelets. A new mechanism for platelet-activating factor responses. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)37085-0] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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128
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Abstract
The authors report on a newborn with an accessory malformed leg attached to the back. The limb was associated with a teratomatous mass adjacent to its attachment site. The embryology and nomenclature of this malformation is discussed briefly.
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129
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Dhar A, Goenka MK. Endomysial antibody and celiac disease. Indian J Gastroenterol 1993; 12:157-8. [PMID: 8270300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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130
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Abstract
Incomplete parasitic twinning with the parasite attached at the host's epigastrium is extremely rare. We report a case of epigastric parasitic twinning where the parasite with a well-developed pelvis and lower limbs had accessory pelvic organs and was attached to the host above an omphalocele. The parasite was excised and the omphalocele managed conservatively by mercurochrome application. A review of the four previously reported cases is presented along with a discussion of the possible etiopathogenesis and nomenclature of this condition.
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Abstract
An unusual case of caudal duplication is presented in which the infant had an extra lower limb with 14 digits attached to an accessory parasitic pelvis situated in the midline subpubic area. Duplication of the external genitalia was also present. Successful excision of the accessory limb and reconstruction of the genitalia was performed in the neonatal period.
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133
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Abstract
Oxidative cleavage of the C17-C20 bond in progesterone by Pseudomonas sp. is reported. Transformation occurred under in vivo conditions. The bioconverted products were characterized as 1,4-androstadien-3,17-dione and 17 beta-hydroxy-1,4-androstadien-3-one. The steroid nucleus was not further degraded although the test organism had the capacity to induce dehydrogenation at C1 of this alpha, beta-conjugated steroid.
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134
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Ciancio MJ, Vitiritti L, Dhar A, Chang EB. Endotoxin-induced alterations in rat colonic water and electrolyte transport. Gastroenterology 1992; 103:1437-43. [PMID: 1358740 DOI: 10.1016/0016-5085(92)91162-w] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
This study examines the effects of endotoxin on intestinal water and electrolyte transport in adult male rats. Endotoxin (1.55 mg/kg, intravenously) reduced in vivo colonic saline absorption 61% in 1 hour. In vitro unidirectional and net 22Na and 36Cl fluxes showed that endotoxin significantly decreased net colonic 22Na absorption compared with control colons (0.3 +/- 1.7 vs. 4.8 +/- 1.1 microEq/h x cm2). Although endotoxin had no significant effect on basal short circuit current (Isc) and conductance, 3H-inulin flux studies suggested an increase in colonic permeability. Isc responses to the 5'-cyclic adenosine monophosphate (cAMP)-dependent secretagogues prostaglandin E2 (1 mumol/L) and vasoactive intestinal peptide (0.1 mumol/L) were diminished by 80% and 50%, respectively. However, cytosolic cAMP-dependent protein kinase activity under basal and stimulated (6 mumol/L 8-bromo-cAMP) conditions was not altered by endotoxin treatment. The Isc responses to 10 mumol/L bethanechol, a Ca(2+)-dependent agonist, were not effected by endotoxin treatment. It was concluded that endotoxin significantly affects colonic transport function and may contribute to the development of diarrhea in inflammatory bowel diseases.
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135
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Kaplan MH, Dhar A, Brown TR, Sundick RS. Marek's disease virus-transformed chicken T-cell lines respond to lymphokines. Vet Immunol Immunopathol 1992; 34:63-79. [PMID: 1332253 DOI: 10.1016/0165-2427(92)90152-g] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Current assays for chicken interleukin-2 (IL-2) utilize mitogen-activated lymphocytes. However, very high inter-assay variability and sporadic high background proliferation limit their usefulness. In view of the above, several Marek's disease virus (MDV)-transformed T-cell lines (which grow well in a serum-supplemented medium) were tested for a response to chicken IL-2 when grown in serum-free media. Five of six lines examined showed a dose-dependent proliferative response to chicken T-cell conditioned media. One line, MDCC-CU14, was chosen for further studies. In addition to the tumor cells' dose-dependent responses to semi-purified chicken IL-2, they expressed T-cell activation antigens on the cell surface. Furthermore, the level of surface expression was enhanced on cells provided IL-2. Co-incubation of the tumor cells with monoclonal antibody INN-CH-16 (specific for an antigen on the surface of activated T-cells) and IL-2 resulted in a modulation of lymphokine-induced proliferation. Together, these data suggest that signalling mechanisms in MDV T-cell tumors are intact and that these lines can be used as an assay for chicken T-cell lymphokines. Furthermore, they provide an interesting model for the study of avian and mammalian T-cell transformation. Implications for the study of Marek's disease are also discussed.
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136
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Chadha R, Bagga D, Mohta A, Malhotra CJ, Dhar A. Congenital fusion of the gums. ORAL SURGERY, ORAL MEDICINE, AND ORAL PATHOLOGY 1992; 74:30-2. [PMID: 1508506 DOI: 10.1016/0030-4220(92)90211-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Congenital fusion of the gums is a rare abnormality. This is a report of a successfully treated newborn infant who had unilateral fusion of the gums. A brief review of the previously reported cases is also presented.
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137
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Mohta A, Chadha R, Bagga D, Dhar A. Congenital agenesis of the penis. JOURNAL OF THE INDIAN MEDICAL ASSOCIATION 1992; 90:106. [PMID: 1645021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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138
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Bedi NK, Chadha R, Bagga D, Dhar A, Malhotra CJ, Mohta A. Non-surgical pneumoperitoneum in the newborn infant. Indian J Pediatr 1991; 58:867-73. [PMID: 1818884 DOI: 10.1007/bf02825454] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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139
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Dhar A, Shukla SD. Involvement of pp60c-src in platelet-activating factor-stimulated platelets. Evidence for translocation from cytosol to membrane. J Biol Chem 1991; 266:18797-801. [PMID: 1717453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
We have investigated the characteristics of platelet-activating factor (PAF)-stimulated protein tyrosine phosphorylation in rabbit platelets and its relationship to pp60c-src. 32P-Labeled platelets were challenged with PAF (10(-7) M) for 15 s, the reaction was killed by lysis at 4 degrees C, and samples were loaded onto a phosphotyrosine monoclonal antibody (Tyr(P)-mAb)-agarose column. The column was eluted with 10 mM phenyl phosphate, and the fractions were collected. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis, followed by autoradiography of the column fractions, showed that PAF increased the radioactivity of about a dozen protein bands with predominant ones of approximate molecular masses of 50, 60, 71, 82, and 300 kDa. When Tyr(P)-mAb-agarose column fractions were subjected to immunoblotting with pp60v-src mAb, it was observed that PAF treatment increased the reactivity of 50- and 60-kDa protein species. Immunoprecipitation with pp60v-src mAb further confirmed that PAF treatment increased phosphorylation of the 60- and 50-kDa proteins. Polyclonal antibody to G-protein (alpha-subunit) did not exhibit any reactivity to the column fractions and thus ruled out this protein as substrate for the tyrosine kinase. We next attempted to localize the pp60c-src. Platelet membrane particulate and cytosol fractions were separated from control and PAF-treated platelets, and it was observed that the immunoreactivity to pp60v-src mAb dramatically increased in the particulate membrane fraction from PAF-treated platelets. A concomitant decrease in the immunoreactivity in the cytosol fraction of PAF-treated platelets was also noted. It is concluded that PAF stimulates phosphorylation of pp60c-src tyrosine kinase and causes its rapid translocation from cytosol to membranes in rabbit platelets.
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140
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Pande CS, Bassi D, Jain N, Dhar A, Glass JD. Diketopinic acid — A novel reagent for the modification of arginine. J Biosci 1991. [DOI: 10.1007/bf02703365] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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141
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Brown TR, Sundick RS, Dhar A, Sheth D, Bagchi N. Uptake and metabolism of iodine is crucial for the development of thyroiditis in obese strain chickens. J Clin Invest 1991; 88:106-11. [PMID: 1647412 PMCID: PMC296009 DOI: 10.1172/jci115265] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
To assess the importance of the role of thyroidal iodine in the pathogenesis of thyroiditis in the obese strain (OS) chicken, a model of spontaneous and severe disease, we studied the effect of antithyroid drugs that reduce thyroidal iodine or prevent its metabolism. Reduction of thyroidal iodine was achieved with KClO4, an inhibitor of iodine transport and mononitrotyrosine (MNT), a drug that promotes loss of thyroidal iodine as iodotyrosines. A regimen consisting of KClO4 and MNT administration beginning in ovo and continuing after hatching reduced thyroidal infiltration to 2% of control values and decreased thyroglobulin antibody (TgAb) production for as long as 9 wk. Untreated birds had severe disease by 5 wk of age. The suppression of disease was independent of TSH, not mediated by generalized immunosuppression and reversed by excess dietary iodine. Two drugs that inhibit the metabolism of iodine, propylthiouracil (PTU) and aminotriazole, reduced thyroidal infiltration and TgAb levels, although to a lesser extent. When splenocytes from OS chickens with thyroiditis were transferred to Cornell strain (CS) chickens, a related strain that develops late onset mild disease, only the recipients that were iodine supplemented developed thyroiditis. In conclusion, autoimmune thyroiditis in an animal model can be prevented by reducing thyroidal iodine or its metabolism and optimal effects require intervention at the embryonic stage.
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142
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Madan A, Dhar A, Kulshrestha PP, Laghate VD, Dhar P. Preliminary observation on drug resistant cases of typhoid fever. THE JOURNAL OF THE ASSOCIATION OF PHYSICIANS OF INDIA 1991; 39:449-51. [PMID: 1938845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We report here a sudden and marked increase in the occurrence, in a captive population, of typhoid fever cases showing multiple drug resistance. Fifty one cases of typhoid fever were seen from January '90 to June '90 of which 49% showed multiple drug resistance. Comparative figures for resistance in the previous three years were 0% (1987), 5% (1988), 14% (1989). Shared resistance to chloramphenicol, ampicillin, amoxycillin and sensitivity to gentamicin, kanamycin, sisomycin, cephazolin, norfloxacin and ciprofloxacin in most of our cases suggest infection by a common strain with R-factor, mediated resistance. The illness was prolonged and associated with serious complications. Therapy with combination of quinolone derivatives and aminoglycoside antibiotics seemed justified on the basis of the in-vitro tests and clinical response. Efforts to identify the strain and stern public health measures to prevent further development of drug resistant S typhi are urgently indicated.
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143
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Sundick RS, Herdegen D, Brown TR, Dhar A, Bagchi N. Thyroidal iodine metabolism in obese-strain chickens before immune-mediated damage. J Endocrinol 1991; 128:239-44. [PMID: 2005414 DOI: 10.1677/joe.0.1280239] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Several studies have shown that iodine plays a role in spontaneous autoimmune thyroiditis in man and other animals. In addition, abnormalities of iodine metabolism have been found in patients with Hashimoto's thyroiditis and in chickens of the obese strain (OS), an animal model of spontaneous autoimmune thyroiditis. We have examined several parameters of iodine metabolism before immune damage in this model and in the related Cornell strain (CS), a strain which develops a late-onset mild thyroiditis, to discover a possible causal relationship between altered iodine metabolism and the initiation of autoimmunity. Thyroglobulin was purified from individual chicken thyroid glands and analysed for iodine by the ceric sulphate method. Analogous to the thyroglobulin of Hashimoto's patients, the iodine content of OS thyroglobulin (27 atoms/molecule) was lower than that of normal-strain thyroglobulin (46 atoms/molecule) when the chickens were provided with a normal diet. Also, under conditions of TSH suppression, the iodine content of OS thyroglobulin (18 atoms/molecule) was lower than that of CS thyroglobulin (36 atoms/molecule) and of normal-strain thyroglobulin (32 atoms/molecule). In contrast with Hashimoto's patients, however, the OS and CS chickens had practically no inorganic iodide in their thyroid glands; electrophoretic analysis of thyroid homogenates revealed that essentially all (greater than 99.62%) 125I was organified by 16 h in all strains of birds tested. Despite the relatively poor iodination of thyroglobulin exhibited by OS chickens, they did not iodinate additional 'unique' proteins, when examined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of thyroid proteins labelled with 125I in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)
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144
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Dhar A, Shukla SD. Release of a membrane surface glycoprotein from human platelets by phosphatidylinositol specific phospholipase(s) C. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1091:15-21. [PMID: 1847299 DOI: 10.1016/0167-4889(91)90215-j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Phosphatidylinositol (PI) specific phospholipase C (PIase C) treatment of human platelets caused release of a surface glycoprotein in the medium. Human blood platelets were isolated by low speed centrifugation and surface glycoproteins were labelled with periodate/[3H]borohydride procedure. Intact surface-labelled platelets were treated with PIase C purified from culture filtrates of Staphylococcus aureus (SA) or Bacillus thuringiensis (BT). After PIase C treatments platelets were spun at low speed, pellet and supernatant were separated. The supernatant was further centrifuged at high speed (140,000 x g) for 30 min. The resulting supernatant and the pellet from low speed were subjected to SDS-PAGE analysis. Protein patterns were obtained by fluorography. Release of a specific glycoprotein of approx. 150 kDa in the medium was observed due to the PIase C treatment. Prolonged incubation of platelets in 0.25 M sucrose and depletion of NaCl concentrations also affected the release of this glycoprotein. BT-PIase C released more approx. 150 kDa protein than SA-PIase C. Western blot experiment with a monoclonal antibody (mAB), epitope SZ2, reactive to human platelet surface glycoprotein Ib (GPIb) complex, confirmed that released 150 kDa glycoprotein reacted with mAB of GPIb. The release of this protein by PIase C was not inhibited by proteinase inhibitors (EDTA, PMSF and leupeptin). Treatment of human platelet membranes with PIase C also caused release of this glycoprotein as evidenced by reactivity to GPIb-mAB. These studies demonstrate that PIase C treatment causes release of 150 kDa glycoprotein from human platelet membrane surface. It is suggested that 150 kDa glycoprotein is anchored to PI in human platelets and that this glycoprotein represents the GPIb complex.
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145
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Kochhar R, Patel F, Dhar A, Sharma SC, Ayyagari S, Aggarwal R, Goenka MK, Gupta BD, Mehta SK. Radiation-induced proctosigmoiditis. Prospective, randomized, double-blind controlled trial of oral sulfasalazine plus rectal steroids versus rectal sucralfate. Dig Dis Sci 1991; 36:103-7. [PMID: 1670631 DOI: 10.1007/bf01300096] [Citation(s) in RCA: 163] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In a prospective study, 37 consecutive patients with radiation-induced proctosigmoiditis were randomized to receive a four-week course of either 3.0 g oral sulfasalazine plus 20 mg twice daily rectal prednisolone enemas (group I, N = 18) or 2.0 g twice daily rectal sucralfate enemas plus oral placebo (group II, N = 19). The two groups were comparable with respect to demographic features, duration of symptoms, and clinical and endoscopic staging of the disease. Fifteen patients in group I and 17 in group II completed the trial. At four weeks, both groups showed significant clinical improvement (P less than 0.01 for group I and P less than 0.001 for group II) and endoscopic healing (P less than 0.01 for group I and P less than 0.001 for group II). When the two groups were compared, sucralfate enemas showed a significantly better response as assessed clinically (P less than 0.05), although endoscopically the response was not statistically different (P greater than 0.05). We conclude that both treatment regimens are effective in the management of radiation proctitis. Sucralfate enemas give a better clinical response, are tolerated better, and because of the lower cost should be the preferred mode of short-term treatment.
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146
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Bagchi N, Brown TR, Herdegen DM, Dhar A, Sundick RS. Antioxidants delay the onset of thyroiditis in obese strain chickens. Endocrinology 1990; 127:1590-5. [PMID: 2401227 DOI: 10.1210/endo-127-4-1590] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Dietary iodine has been shown to be important in the induction of thyroiditis in susceptible chicken strains although the underlying mechanism remains unknown. Iodine may exert its effects through the formation of reactive oxidative radicals which would cause thyroidal injury and initiate infiltration. We have tested this hypothesis by examining the ability of butylated hydroxyanisole (BHA), ethoxyquin, and other antioxidants to prevent thyroiditis in Obese strain (OS) chickens, a strain that develops severe disease by 4 weeks of age. BHA, when administered from hatching until death at 5 weeks of age, reduced thyroidal infiltration and serum levels of antibodies binding thyroglobulin, T3, T4. Similar effects were observed with the antioxidant ethoxyquin. Weaker antioxidants such as vitamins C and E and beta-carotene had only slight or negligible effects on these parameters. BHA reduced thyroiditis in OS chicks killed at 3 and 5 weeks of age, but not at 8 weeks. When BHA treatment was initiated after the development of severe disease, it did not reduce thyroglobulin antibody levels. To determine the mechanism by which BHA reduces thyroiditis, studies were performed to assess the effect of BHA on thyroid function and on the immune responses to exogenous antigens. BHA had no effect on thyroid function in normal strain chickens since thyroidal radioiodine uptake and organification and serum T3 and T4 levels were unaffected. BHA did not alter immune responses to exogenous antigens such as sheep red blood cells or Brucella abortus in OS chickens. In summary, potent antioxidant drugs delayed the onset of thyroiditis when treatment was initiated before the onset of disease, suggesting that reactive oxygen intermediates are involved in the early stages of pathogenesis. However, the site of action remains unknown since they had no detectable effects on thyroid function or general immune responses.
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147
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Abstract
One hundred sixty seven children were operated at the Kalawati Saran Children Hospital for acute peritonitis during last 10 years (1978-88). Bowel perforation was seen in 123 cases. Nineteen cases had underlying tubercular enteritis. Preoperative diagnosis was usually difficult. The terminal ileum was affected in 12 and the jejunum in 5 cases. Multiple perforations were seen in 3 cases. Postoperative mortality was high (12/19) and usually attributable to their poor preoperative status.
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148
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Dhar A, Paul AK, Shukla SD. Platelet-activating factor stimulation of tyrosine kinase and its relationship to phospholipase C in rabbit platelets: studies with genistein and monoclonal antibody to phosphotyrosine. Mol Pharmacol 1990; 37:519-25. [PMID: 1691437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Platelet-activating factor (PAF) is a proinflammatory lipid that has platelet-stimulating property. PAF receptor-coupled activation of phosphoinositide-specific phospholipase C (PLC) and phosphorylation of several proteins has already been established in our laboratory. To investigate further the molecular mechanism and relationship between activation of PLC and protein phosphorylation, we have used Genistein (a putative inhibitor of tyrosine-specific protein kinases), phosphotyrosine antibody, and phosphoamino acid analysis to probe the involvement of tyrosine kinase in this process. Washed rabbit platelets were loaded with myo-[2-3H]inositol and challenged with PAF (100 nM) after pretreatment with Genistein. PLC-mediated production of radioactive inositol monophosphate, inositol diphosphate, and inositol triphosphate was monitored. PAF alone caused stimulation of PLC activity [( 3H]inositol triphosphate production), whereas pretreatment with Genistein (0.5 mM) diminished PAF-stimulated PLC activity to basal level. Genistein also blocked PAF-stimulated platelet aggregation at this dose. In contrast to Genistein, staurosporine which inhibits protein kinase C, potentiated PAF-stimulated [3H]inositol triphosphate production. Genistein substantially inhibited the combined effects of staurosporine and PAF on inositol triphosphate production. Genistein also reduced PAF-induced phosphorylation of Mr 20,000 and 50,000 proteins. Phorbol 12-myristate 13-acetate-induced Mr 40,000 protein phosphorylation was also affected by Genistein. The above results suggested that Genistein inhibited tyrosine kinase at an early stage of signal transduction by inhibiting PLC. This, in turn, decreased the activation of protein kinase C and, therefore, caused a reduction in Mr 40,000 protein phosphorylation. The inhibition of PLC by Genistein raised the possibility of involvement of tyrosine kinase in PAF receptor-coupled PLC activation. Western blot analysis using monoclonal antibody to phosphotyrosine demonstrated that PAF stimulated the tyrosine phosphorylation of two major proteins of 50,000 and 60,000 molecular weight. When platelets were challenged with PAF after treatment with either Genistein or CV-6209 (a PAF receptor antagonist), the reactivity of these proteins to monoclonal antibody was inhibited. Phosphoamino acid analysis of Mr 50,000 and 60,000 proteins confirmed that PAF increased the phosphorylation of tyrosine residues in both Mr 50,000 and 60,000 proteins and that this was inhibited by Genistein. Thus, PAF caused a receptor-dependent phosphorylation of tyrosine residues on Mr 50,000 and 60,000 proteins. Based on these observations, it is concluded that tyrosine kinase is involved in the PAF receptor-coupled PLC activation and signal transduction mechanism.
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149
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Abstract
To assess the efficacy of sucralfate enemas in distal colonic ulcerative lesions, 22 patients with radiation proctitis (n = 8), idiopathic ulcerative proctitis (n = 5), and solitary rectal ulcer (n = 5) unresponsive to conventional medical therapy, and those with ulcerated and bleeding rectal polyps awaiting polypectomy (n = 4) were studied. Enemas of sucralfate suspension (2 gm in 20 ml water) were administered twice daily for a period of three weeks. Clinical and sigmoidoscopic improvements were observed in 19 and 18 of the 22 patients, respectively (86 and 82 percent, respectively). No side effects were seen. The authors conclude that sucralfate enemas are useful in the treatment of ulcerative lesions of the rectosigmoid.
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150
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Shukla SD, Morrison WJ, Dhar A. Desensitization of platelet-activating factor-stimulated protein phosphorylation in platelets. Mol Pharmacol 1989; 35:409-13. [PMID: 2539556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Treatment of 32P-labeled rabbit platelets with platelet-activating factor (PAF) caused a time- and dose-dependent phosphorylation of several proteins including five major phosphorylated proteins with apparent molecular weights of 20,000, 35,000, 40,000, 65,000, and 150,000. Both PAF and thrombin caused a rapid increase followed by a decrease in phosphorylation of proteins, indicating the occurrence of a phosphorylation-dephosphorylation process. Four separate PAF receptor antagonists, CV-3988, CV-6209, SRI-63-441, and SRI-63-675 drastically reduced the PAF-stimulated protein phosphorylation. The order of potency was SRI-63675 greater than SRI-63441 greater than or equal to CV-6209 greater than CV-3988. These antagonists had no effect on thrombin-stimulated protein phosphorylation. Pretreatment of platelets with PAF (0.1 nM) completely abolished any further protein phosphorylation by the same concentration of PAF. PAF pretreatment shifted the dose response of protein phosphorylation by about 2 log units, to the right. When platelets were treated with PAF (10 nM) for 10 min, this abolished phosphorylation of proteins by any concentration of PAF. These studies indicated a homologous desensitization of protein phosphorylation. Interestingly, PAF-pretreated platelets still exhibited phosphorylation of proteins by thrombin. On the other hand, a lack of protein phosphorylation by PAF or thrombin was observed in platelets preexposed to thrombin and this demonstrated a heterologous desensitization. It is concluded that phosphorylation of proteins by PAF is a PAF receptor-coupled event and that this process is desensitized in platelets preexposed to PAF. The fact that both the activation of phosphoinositide-specific phospholipase C and the phosphorylation of proteins are desensitized in PAF-pretreated platelets suggests that a close "regulatory" intercommunication between these processes exists.
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