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Agarwal M, Sharma R, Panda A, Gupta A. Laryngeal web associated with Simpson-Golabi-Behmel syndrome in a child. Anaesth Intensive Care 2009; 37:671-672. [PMID: 19681434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
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Sharma R, Kumar A, Panda A. Lumbar canal stenosis: retrospective diagnosis after a high spinal block. Anaesth Intensive Care 2009; 37:141-142. [PMID: 19157369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
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Sharma R, Kumar A, Panda A. Cricothyroidotomy assisted airway access with provision for connection to standard anaesthesia connectors. Anaesth Intensive Care 2009; 37:138. [PMID: 19157366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
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Sharma R, Goel N, Kumar A, Panda A. Central nervous system toxicity with a 1 ml lidocaine injection in the aberrant carotid artery overlying the trachea. Acta Anaesthesiol Scand 2008; 52:1436. [PMID: 19025545 DOI: 10.1111/j.1399-6576.2008.01776.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Kumar S, Panda A, Badhu BP, Das H. Safety of primary intraocular lens insertion in unilateral childhood traumatic cataract. JNMA J Nepal Med Assoc 2008; 47:179-185. [PMID: 19079390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023] Open
Abstract
This study analyzes the results of cataract surgery with primary intraocular lens implantation in unilateral childhood traumatic cataract following penetrating trauma and its long term follow up. It is a hospital based study of 114 children (age 3-10 years) with unilateral traumatic cataract who underwent extracapsular cataract extraction/ lens aspiration with implantation of posterior chamber intraocular lens (IOL). Primary posterior capsulotomy (PPC) was performed in 57 eyes and the rest 57 were without PPC (NPPC). The patients were followed up at regular intervals for a period of 3 years. Postoperative inflammation and pupillary capture were two frequent complications seen during postoperative period. Development of posterior capsular opacification (PCO) was 1/57, 4/57 at 8th week and 7/30 and 14/39 at 6 months, in PPC and NPPC group, respectively. Best corrected visual acuity (BCVA)>or=6/18 was achieved in 50% of eyes at 8th week post operatively and the same at 3 years with/without membranectomy/capsulotomy was evident in 73.3% of eyes. Meticulous case selection with insertion of "in the bag IOL" and subjecting the traumatized cataractous eyes to primary posterior capsulotomy are factors responsible for optimal outcome in unilateral traumatic cataract in children.
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Kumar S, Panda A, Bandu BP, Das H. Safety of Primary Intraocular Lens Insertion in Unilateral Childhood Traumatic Cataract. JNMA J Nepal Med Assoc 2008. [DOI: 10.31729/jnma.153] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
This study analyzes the results of cataract surgery with primary intraocular lens implantation inunilateral childhood traumatic cataract following penetrating trauma and its long term follow up.It is a hospital based study of 114 children (age 3-10 years) with unilateral traumatic cataract whounderwent extracapsular cataract extraction/ lens aspiration with implantation of posterior chamberintraocular lens (IOL). Primary posterior capsulotomy (PPC) was performed in 57 eyes and the rest57 were without PPC (NPPC). The patients were followed up at regular intervals for a period of 3years.Postoperative inflammation and pupillary capture were two frequent complications seen duringpostoperative period. Development of posterior capsular opacification (PCO) was 1/57, 4/57 at 8thweek and 7/30 and 14/39 at 6 months, in PPC and NPPC group, respectively. Best corrected visualacuity (BCVA) ≥ 6/18 was achieved in 50% of eyes at 8th week post operatively and the same at 3years with/without membranectomy/capsulotomy was evident in 73.3% of eyes.Meticulous case selection with insersion of “in the bag IOL” and subjecting the traumatizedcataractous eyes to primary posterior capsulotomy are factors responsible for optimal outcome inunilateral traumatic cataract in children.Key words: childhood, intraocular lens, Nepal, traumatic cataract
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Kai S, Vanathi M, Vengayil S, Panda A. Viscoexpression of large free floating Cysticercus cyst from the anterior chamber of the eye by double incision technique. Indian J Med Microbiol 2008; 26:277-9. [PMID: 18695335 DOI: 10.4103/0255-0857.42054] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
We describe a case of 16-year-old girl who reported with diminution of vision in left eye for past seven months with appearance of white reflex. Slit lamp biomicroscopy revealed the presence of a live grayish white cyst in the anterior chamber. The ultrabiomicroscopic evaluation revealed a large live Cysticercus cellulosae cyst in anterior chamber. The CT-scan of the brain revealed multiple non-contrast enhanced lesions with calcification in brain parenchyma. The patient was started on oral prednisolone and oral albendazole. The cyst was removed in toto from the eye by double incision technique. The patient achieved visual acuity of 6/12 post-operatively.
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Kai S, Vanathi M, Vengayil S, Panda A. VISCOEXPRESSION OF LARGE FREE FLOATING CYSTICERCUS CYST FROM THE ANTERIOR CHAMBER OF THE EYE BY DOUBLE INCISION TECHNIQUE. Indian J Med Microbiol 2008. [DOI: 10.1016/s0255-0857(21)01883-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Sah RP, Badhu BP, Pokharel PK, Thakur SKD, Das H, Panda A. Prevalence of glaucoma in Sunsari district of eastern Nepal. Kathmandu Univ Med J (KUMJ) 2007; 5:343-348. [PMID: 18604052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
AIMS To determine prevalence of glaucoma and glaucoma suspect in subjects 40 years and above in Sunsari district of eastern Nepal. METHODS A community based cross sectional study examining 1600 selected subjects was carried out. In all subjects best corrected visual acuity was determined. Oblique torch light test was used for anterior chamber depth evaluation. Intraocular pressure (IOP) measurements with Perkins tonometer and fundus examination were carried out in the community. Subjects diagnosed as glaucoma suspect were further evaluated in the hospital using slit lamp examination, gonioscopy and Goldmann perimetry. Glaucoma was defined by characteristic disc and visual field changes irrespective of the level of IOP. RESULTS Of 1600 subjects examined, the prevalence of glaucoma was found to be 0.938%. The prevalences of primary open angle glaucoma, primary angle closure glaucoma, secondary glaucoma and ocular hypertension were 0.562%, 0.125%, 0.250% and 0.500% respectively. Lens induced glaucoma accounted for all the cases of secondary glaucoma. CONCLUSION The prevalence of glaucoma in the Sunsari District of Nepal is 0.938%, which is lower than that reported in the neighboring regions. Lens induced glaucoma is highly prevalent as a cause of secondary glaucoma.
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Panda A, Kumar S, Das H, Badhu BP. Striving for the perfect surgery in traumatic cataract following penetrating trauma in a tertiary care hospital at eastern Nepal. JNMA J Nepal Med Assoc 2007; 46:119-125. [PMID: 18274567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023] Open
Abstract
This study analyzes the result of traumatic cataract surgery in a tertiary care hospital at eastern Nepal. It is a hospital-based study of 112 patients (age 15-62), who underwent cataract extraction for unilateral traumatic cataracts. The study was carried out to evaluate the surgical outcome of tramatic cataract. Thirty-eight eyes had associated posterior capsular defect. No serious postoperative complications were encountered. Posterior capsular opacification at the end of sixth week was evident only in two eyes. Best corrected visual acuity nof 6/18 or more at the eighth week was achieved in 61 (54%) eyes. Astigmatism of less than 3D was achieved in 82 (73%) eyes. Rational surgical approach in traumatic cataract provides encouraging results. To comment on actual outcome long term follow up is mandatory.
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Roy D, Panda A, Calaf GM, Mitra A. Differential gene expression of sulindac-treated human breast epithelial cells. Int J Oncol 2005; 27:1727-36. [PMID: 16273229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023] Open
Abstract
Breast cancer is the most common malignancy and the second major cause of cancer-related deaths among women in the United States. Recent advances in the molecular genetics of breast cancer have identified various genes associated with tumorigenesis. There is evidence that non-steroidal anti-inflammatory drugs, e.g. sulindac, have some anti-proliferative effects on various tumors involving altered p53 function. Most of these studies have been performed with various human colon carcinoma cell lines and few of them focus on non-malignant proliferative human mammary epithelial cell lines. Therefore, the present study was undertaken to analyze the differentially expressed genes of the p53 signaling pathway by means of a gene array for the immortalized human breast epithelial cell line, MCF-10F, treated with sulindac. Out of the total 96 genes, only 17 were altered by the drug treatment. Among these 17 genes, 6 showed significant alteration (Q > 2.0), whereas 11 genes showed moderate alterations. Altered genes included BRCA1 associated protein-1 [ubiquitin carboxy-terminal hydrolase (bap1)]; cell division cycle 2, G1 to S and G2 to M [cdk1(cdc2)]; and DNA-damage-inducible transcript 1 (gadd45), which were down-regulated. However, N-myc gene 1 (rtp), promyelocytic leukemia (pml), and nuclear factor of kappa-light polypeptide gene enhancer in B-cell 3 and p65 [avian (rel A)] were up-regulated. Northern blot analysis confirmed some of these alterations. The alteration of p53 signaling pathway gene markers by sulindac treatment can give us valuable information about the response to drug treatments in a proliferative cell population.
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Das H, Das BP, Panda A. Pattern of intraocular pressure changes following manual small incision cataract surgery. Kathmandu Univ Med J (KUMJ) 2005; 3:340-4. [PMID: 16449832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
OBJECTIVES To find out the pattern of changes in intraocular pressure after manual small incision cataract surgery. METHODS Consecutive patients (291 eyes of 291 patients) undergoing manual small incision cataract surgery were prospectively evaluated for change in IOP. Patients were further divided into two groups based on whether or not sutures were used to close the scleral tunnel. IOP was serially measured at day 1, 1st, 2nd, 4th, 6th, 8th and 12th week. RESULTS The mean post operative IOP in eyes where sutures were not applied (12.59+/- 3.02 mmHg, 12.59+/-2.34mmHg, 12.54+/-2.19mmHg and 12.40+/-2.99 mm Hg at day1, 2week and 4weeks respectively) was lower than that where sutures were used to close the wound (15.57+/- 3.86mmHg, 14.05+/-2.52mmHg, 14.43+/-3.39mmHg at day1, 2weeks and 4 weeks respectively). There was a drop of IOP from the preoperative IOP in both suture (1.15+/-3.29mm Hg) and non suture (3.29+/-3.07mm Hg) group at 3 months of follow up. CONCLUSION There is a small drop of IOP following sutureless MSICS during long term follow up. Eyes where sutures are applied are more likely to have higher IOP than those without sutures at the initial post operative period.
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Abstract
AIM To present seven eyes of suspected donor to host transmitted Pseudomonas sp corneal graft infection after corneal and scleral graft leading to corneal melting within 24 hours, in a span of 10 months. METHODS Case series. Seven eyes, operated for either penetrating or lamellar keratoplasty or scleral patch graft for different indications and which developed massive corneal/corneoscleral infection within 24 hours, were studied prospectively. RESULTS Pseudomonas aeruginosa, resistant to almost all antibiotics except polymyxin B in all and vancomycin in two, was identified as the causative organism from all the specimens obtained from the infected graft. CONCLUSION Post-keratoplasty infection is a disaster. The source of early infection is invariably iatrogenic. Use of empirical antibiotics in the media is not always sufficient to prevent such infection. Thus, measures must be taken in the form of strict maintenance of asepsis and revision of antibiotics added to the storage medium. Further, early recognition and energetic therapy for such infection could reduce the ophthalmic morbidity.
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Khanal B, Deb M, Panda A, Sethi HS. Laboratory diagnosis in ulcerative keratitis. Ophthalmic Res 2005; 37:123-7. [PMID: 15746569 DOI: 10.1159/000084273] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2004] [Accepted: 08/19/2004] [Indexed: 11/19/2022]
Abstract
AIMS To identify the common bacterial and fungal isolates from corneal ulcers and to determine the antimicrobial susceptibility patterns of bacterial isolates to commonly used antibiotics at B.P. Koirala Institute of Health Sciences (BPKIHS), eastern Nepal. Culture and direct microscopic correlation and reliability were also compared. METHODS All patients with suspected corneal ulceration presenting to the Ophthalmology Department of BPKIHS from 1st August 1998 to 31st July 2001 were evaluated. Corneal scraping was performed and processed for direct microscopy and culture for bacterial and fungal isolates. Bacterial isolates were subjected to antimicrobial susceptibility testing. RESULTS Of 447 specimens examined direct microscopy was positive in 216 (48%) specimens. Culture positivity could be correlated with direct microscopy in 179 (83%) of specimens. Growth of etiologic agents was found in 303 (67.8%) samples. Of these 145 (47.8%) had pure fungal growth, 103 (34%) had pure bacterial growth and 55 (18.2%) had mixed fungal and bacterial infection. The commonest fungal pathogen was Aspergillus spp.in 78 (38.4%) followed by Fusarium spp. in 45 (22%). Aureobasidium sp. was isolated in 25 (12.3%) samples. Staphylococcus aureus (93, 56.7%) dominated the scene as the commonest bacterial agent. Streptococcus pneumoniae (33, 20%) was second in the list. Most of the bacterial isolates were sensitive to commonly used antibiotics. CONCLUSION This study emphasizes the importance and need of the continued surveillance of the agents and their antimicrobial susceptibility for the prevention and management of corneal ulcers and their complications.
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Nanda R, Mishra PK, Das UK, Rout SB, Mohapatra PC, Panda A. Evaluating role of oxidative stress in determining the pathogenesis of falciparum malaria induced acute renal failure. Indian J Clin Biochem 2004; 19:93-6. [PMID: 23105436 PMCID: PMC3453903 DOI: 10.1007/bf02872399] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Serum malondialdehyde was measured in sixty-one falciparum malaria cases, which include thirty uncomplicated, and thirty-one complicated with acute renal failure. Twenty-six healthy individuals were also studied as controls. Serum malondialdehyde level was found to be significantly elevated in falciparum malaria induced acute renal failure cases when compared with uncomplicated falciparum malaria (p<0.001) and healthy controls (p<0.001). A positive correlation with the raised urea, creatinine and bilirubin levels were significant (r=0.62, p<0.025; r=0.65, p<0.05 and r=0.72, p<0.001 respectively) indicating the severity of complication with rise of lipid peroxides in falciparum malaria induced acute renal failure cases.
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Huang Z, Elankumaran S, Panda A, Samal SK. Recombinant Newcastle disease virus as a vaccine vector. Poult Sci 2003; 82:899-906. [PMID: 12817444 DOI: 10.1093/ps/82.6.899] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Veterinary vaccines remained conventional for more than fifty years. Recent advances in the recombinant genetic engineering techniques brought forward a leap in designing vaccines for veterinary use. A novel approach of delivering protective immunogens of many different pathogens in a single virus vector was made possible with the introduction of a "reverse genetics" system for nonsegmented negative-sense RNA viruses. Newcastle disease virus (NDV), a nonsegmented negative-sense virus, is one of the major viruses of economic importance in the poultry industry throughout the world. Despite the availability of live virus vaccines of good potency, the intrinsic ability of attenuated strains to revert in virulence makes control of this disease by vaccination difficult. Armed with the knowledge of virulence factors of this virus, it is now possible to produce genetically stable vaccines and to engineer mutations that enhance immunogenicity. The modular nature of the genome of this virus facilitates engineering additional genes from several different pathogens or tumor-specific antigens to design contemporary vaccines for animals and humans. This review will summarize the developments in using NDV as a vaccine vector and the potential of this approach in designing next generation vaccines for veterinary use.
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Rauniyar RK, Thakur SKD, Panda A. CT in the diagnosis of isolated cysticercal infestation of extraocular muscle. Clin Radiol 2003; 58:154-6. [PMID: 12623046 DOI: 10.1053/crad.2002.1101] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
AIM To evaluate the use of computed tomography (CT) and ultrasound (US) to diagnose orbital cysticercosis, and present the diagnostic features. METHOD US and CT were used to evaluate patients with proptosis. Four patients were diagnosed as having orbital myocysticercosis and treated with oral albendazole and corticosteroid. Follow-up was undertaken with US and CT. RESULT US features were confirmatory of myocysticercosis in two eyes where as CT was effective in diagnosing the condition in all four eyes. In two patients the medial rectus was involved, in one the superior rectus and, in the other, the inferior rectus muscles. Serial US and CT revealed complete resolution of the lesions in 3 months. CONCLUSION CT is useful method in diagnosing isolated orbital myocysticercosis. Our report demonstrated that ophthalmic signs and symptoms in the presence of proptosis, especially in an endemic region, should alert the clinician to the possibility of myocysticercosis. Though CT is superior, US can be used as a economical follow-up investigation.
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Panda A, Pangtey MS, Sony P. Assessment of endothelium from donor corneas. Br J Ophthalmol 2003; 87:123. [PMID: 12488281 PMCID: PMC1771446 DOI: 10.1136/bjo.87.1.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Panda A, Bajaj MS, Sethi HS, Pushker N, Kumar H, Dada VK. Squamous cell carcinoma of the conjunctiva. Br J Ophthalmol 2002; 86:1462. [PMID: 12446412 PMCID: PMC1771400 DOI: 10.1136/bjo.86.12.1462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Panda A, Nainiwal SK, Sudan R. Failure of amniotic membrane transplantation in the treatment of acute ocular burns. Br J Ophthalmol 2002; 86:831. [PMID: 12084765 PMCID: PMC1771176 DOI: 10.1136/bjo.86.7.831] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Biswas NR, Das H, Satpathy G, Mohanty S, Panda A. Role of aprotinin in the management of experimental fungal keratitis. Ophthalmic Res 2001; 33:147-50. [PMID: 11340405 DOI: 10.1159/000055661] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In an experimentally induced Aspergillus fumigatus fungal keratitis in 20 rabbits, aprotinin, an antiplasmin agent, was studied to find out its role as an adjuvant when given along with other established antifungal agents like natamycin and fluconazole. The 20 rabbits included in this study were randomly divided into four equal treatment groups. Once the ulcer was produced after intrastromal injection of 0.03 ml of A. fumigatus (5.5 x 10(4) spores/ml), different drugs/agents in combination were used in a randomized manner. These were natamycin (5%) + placebo, natamycin + aprotinin (40 IU/ml), fluconazole (0.3%) + placebo and fluconazole + aprotinin. The rabbits were followed up every day to note the signs of healing which included subsidence of corneal infiltration, disappearance of stromal abscess and subsidence of corneal oedema till complete healing. Results showed that the average healing time was 28.2, 28.4, 49.8 and 49.0 days for natamycin + placebo, natamycin + aprotinin, fluconazole + placebo and fluconazole + aprotinin, respectively. It suggests that aprotinin as an adjuvant has no definite role in the management of fungal keratitis. The plasminogen activator-plasmin system which is inhibited by aprotinin may not be the pathway through which filamentous fungi like A. fumigatus cause tissue destruction.
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Mugesh G, Panda A, Singh HB, Punekar NS, Butcher RJ. Glutathione peroxidase-like antioxidant activity of diaryl diselenides: a mechanistic study. J Am Chem Soc 2001; 123:839-50. [PMID: 11456617 DOI: 10.1021/ja994467p] [Citation(s) in RCA: 261] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The synthesis, structure, and thiol peroxidase-like antioxidant activities of several diaryl diselenides having intramolecularly coordinating amino groups are described. The diselenides derived from enantiomerically pure R-(+)- and S-(-)-N,N-dimethyl(1-ferrocenylethyl)amine show excellent peroxidase activity. To investigate the mechanistic role of various organoselenium intermediates, a detailed in situ characterization of the intermediates has been carried out by (77)Se NMR spectroscopy. While most of the diselenides exert their peroxidase activity via selenol, selenenic acid, and selenenyl sulfide intermediates, the differences in the relative activities of the diselenides are due to the varying degree of intramolecular Se.N interaction. The diselenides having strong Se.N interactions are found to be inactive due to the ability of their selenenyl sulfide derivatives to enhance the reverse GPx cycle (RSeSR + H(2)O(2) = RSeOH). In these cases, the nucleophilic attack of thiol takes place preferentially at selenium rather than sulfur and this reduces the formation of selenol by terminating the forward reaction. On the other hand, the diselenides having weak Se.N interactions are found to be more active due to the fast reaction of the selenenyl sulfide derivatives with thiol to produce diphenyl disulfide and the expected selenol (RSeSR + PhSH = PhSSPh + RSeH). The unsubstituted diaryl diselenides are found to be less active due to the slow reactions of these diselenides with thiol and hydrogen peroxide and also due to the instability of the intermediates. The catalytic cycles of 18 and 19 strongly resemble the mechanism by which the natural enzyme, glutathione peroxidase, catalyzes the reduction of hydroperoxides.
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