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Biomedical subjects

S Narang

Publications and source records attributed to S Narang.

At least 19 recordsLinked to original sources
PubMed2001

Fungal endophthalmitis following cataract surgery: clinical presentation, microbiological spectrum, and outcome.

PURPOSE: To determine the clinical presentation, microbiological spectrum, and outcome in cases of fungal endophthalmitis following cataract surgery. DESIGN: Observational case series. METHODS SETTING: Tertiary referral hospital. PATIENTS: Retrospective analysis of 27 cases of smear- and culture-proven fungal endophthalmitis. INTERVENTION: Pars plana vitrectomy in 18 eyes, where the corneal condition did not preclude the same. All eyes received intravitreal amphotericin B and dexamethasone along with systemic antifungal agents. MAIN OUTCOME MEASURES: Functional success: Final visual acuity of 3/60 or better with attached retina. Anatomical success: Final visual acuity of better than light perception with preserved anatomy of globe. RESULTS: The majority of the eyes (22 of the 27) had early onset and diffuse presentation (that is, anterior segment as well as posterior vitreous exudates). Substantial corneal involvement was seen in 14 eyes (51.85%). Aspergillus sp. was the most common isolate. Multivariate analysis using forward stepwise logistic regression showed corneal involvement as the single most important risk factor in determining final visual outcome (P =.0429). CONCLUSIONS: Early onset and diffuse presentation, which mimics bacterial endophthalmitis, stresses the importance of both bacterial and fungal cultures from intraocular fluids to reach a diagnosis apart from the clinical judgment. Corneal involvement was the most important predictor of outcome in cases of fungal endophthalmitis.

Adult↗
PubMed2001

Phakonit: phacoemulsification through a 0.9 mm corneal incision.

Advances in technique and equipment have led to a significant increase in the popularity of phacoemulsification and have increased its safety and efficiency. We describe a technique, phakonit, in which the lens is emulsified through a 0.9 mm clear corneal temporal incision. A cortical wash with bimanual irrigation/aspiration is followed by enlarging the incision to 2.0 mm and inserting a Staar sub-2.0 mm foldable intraocular lens. Phakonit is a safe, precise method of phacoemulsification with minimal intraoperative or postoperative complications.

Aged↗
PubMed2001

Anesthesia for patients with a mediastinal mass.

Anesthesia for patients with mediastinal masses carries a significant risk for fatal or near-fatal cardiorespiratory events. Careful history taking and thorough preoperative investigation, including CT, identify most susceptible patients. Preoperative fiberoptic bronchoscopy performed by or involving the anesthesiologist is invaluable for determining the plan for intubation and ventilation. A coordinated approach involving anesthesiologists and surgeons is essential.

Anesthesia↗
PubMed2001

Thermostable alpha-amylase production by an extreme thermophile Bacillus thermooleovorans.

AIMS: alpha-Amylase production by a newly isolated thermophile, Bacillus thermooleovorans, was studied under different cultivation conditions. METHODS AND RESULTS: The influence of various carbon and nitrogen sources on alpha-amylase production was quantified in batch fermentation in shake flasks. Starch and tryptone were observed to be the ideal carbon and nitrogen sources, respectively. Cultivation of the organism in a chemically defined medium consisting of glucose, riboflavin, cysteine, MgSO4, K2HPO4 and NaCl led to a near twofold increase in the production of alpha-amylase in comparison with that in the complex medium. The increase in enzyme production was achieved using vitamins and amino acids. When the organism was grown in a laboratory fermenter in the optimized complex medium, the noticeable effects were the near abolition of the lag phase, a 2.2-fold increase in enzyme production and a reduction in optimal production time from 12 to 4-5 h. CONCLUSION: Enhancement of amylase production was achieved under various cultivation conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: Bacillus thermooleovorans produces a calcium-independent and thermostable amylase which can find use in starch saccharification.

Bacillus↗
PubMed2001

Optimization of xylanase production by Melanocarpus albomyces IIS68 in solid state fermentation using response surface methodology.

Xylanase production by the thermophilic fungus, Melanocarpus albomyces IIS68, during solid state fermentation of wheat straw was studied and the effects of various variables were observed. Using the response surface methodology and the multivariant statistical approach, the optimum levels of the variables affecting xylanase production were determined. The optimum levels of the variables were 600-850 microm particle size, 43 h inoculum age, 1.37% Tween 80, 86% initial moisture content, 5.1% urea, 0.74% yeast extract and a harvest time of 96 h. Under these optimized conditions, xylanase activity of 7760 U/g initial dry substrate was obtained which was in very good agreement with the value predicted by the quadratic model (7890 U/g initial dry substrate).

Journal Article↗
PubMed2001

Lingual cysticercosis--a case report.

Cysticercosis is unlikely to be the first diagnosis for a swelling over the tongue. In this report we document an unusual case of lingual cysticercosis presenting as an isolated lesion.

Adolescent↗
PubMed2001

Frequency doubled Nd:YAG (532 nm) laser photocoagulation in corneal vascularisation: efficacy and time sequenced changes.

PURPOSE: To evaluate the efficacy of frequency-doubled Nd:YAG (532 nm) laser treatment in quiescent corneal vascularisation, and to record the sequential changes in lasered vessels and complications in eyes with one and two quadrant vascularisation. METHODS: Thirty eyes (30 patients)--15 eyes (15 patients) with one-quadrant and 15 eyes (15 patients) with two-quadrant corneal vascularisation were treated. Frequency-doubled Nd:YAG laser (532 nm) was used at laser setting of 120-480 mw power, 50-150 mm spot size and 0.05 sec pulse duration. The area of corneal vascularisation, status of treated corneal vessels, area of corneal opacity and visual acuity were recorded before treatment, at one week after treatment and thereafter at monthly intervals up to three months. RESULTS: The mean area of corneal vascularisation decreased from 20.09% to 8.31% of the total corneal area in group I (p<0.01) and from 44.34% to 20.67% of the total corneal area in group II (p<0.01) at 3 months' follow-up. The mean reduction in the area of corneal vascularisation was 58.64% in group I and 53.38% in group II (p>0.05). Of 148 corneal vessels treated, 60 (44.6%) were totally occluded, 44 (30%) partially occluded, 37 (28%) recanalized and there was one shunt vessel at one week following laser treatment. At three months' follow-up, 80 (54.15%) vessels were totally occluded, 14 (9%) partially occluded, 52 (35.14%) recanalised and two shunt vessels appeared. Thus, at three months' follow-up, the number of totally occluded vessels increased and partially occluded vessels decreased. Superficial corneal haemorrhage was observed in 4 (14%) patients. CONCLUSION: Frequency-doubled Nd:YAG (532 nm) laser photocoagulation appears a safe and effective means of reducing the area of corneal vascularisation in quiescent eyes with vascularised corneal opacities.

Adult↗
PubMed2001

Threshold retinopathy of prematurity: ocular changes and sequelae following cryotherapy.

PURPOSE: To determine ocular changes and sequelae following cryotherapy for threshold retinopathy of prematurity (ROP). METHODS: This is a retrospective study of 49 eyes of 26 premature babies with threshold ROP treated with cryotherapy between 1995 and 1998. All eyes included in the study had favourable structural outcome after cryotherapy. Follow-up examination of all babies was done 12 - 62 months (average 28 months) after cryotherapy. Visual axis, fixation pattern, anterior segment examination, cycloplegic refraction and dilated fundus examination with indirect ophthalmoscopy were undertaken in all eyes during follow-up. RESULTS: Posterior pole retinal residuae observed following cryotherapy were tortousity of blood vessels in 32 (65.3%), narrow temporal arcade in 22 (44.89%), temporal crescent in 17 (34.69%), disc drag in 13 (26.53%) and macular heterotopia in 7 (14.28%) eyes. Myopia was observed in 20 (40.82%) eyes and strabismus in 5 (19.23%) babies. The significant risk factor for ocular changes was ROP with more clock hours of involvement (p < 0.05). Higher period of gestation was associated with posterior pole changes (p< 0.05). CONCLUSIONS: All premature babies with threshold ROP treated with cryotherapy require frequent and long-term follow up to look for retinal residuae, refractive status, and ocular motility disorders.

Cryotherapy↗
PubMed2000

Results of pediatric laser in situ keratomileusis.

PURPOSE: To evaluate the results of laser in situ keratomileusis (LASIK) for uniocular high myopia in pediatric eyes. SETTING: Dr. Agarwal's Eye Hospital, Chennai (Madras), India. METHODS: Sixteen eyes that were treated by LASIK for uniocular high myopia were retrospectively analyzed. The mean patient age was 8.4 years +/- 1.83 (SD) (range 5 to 11 years). Laser in situ keratomileusis was performed using the Technolas Keracor 217 excimer laser and the Automated Corneal Shaper microkeratome, which created a 160 microm corneal lamellar flap. Postoperatively, patients were reviewed at 1 day, 1 week, and 1, 6, and 12 months. The examination included uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), refraction, anterior segment evaluation, grading of haze based on a 5-point scale, intraocular pressure, corneal topography, and fundus evaluation. The Student t test was used for statistical analysis. RESULTS: The charts of all patients were analyzed at the 12 month visit. The mean preoperative spherical equivalent (SE) was -14.88 +/- 3.69 diopters (D) (range -9.00 to -23.00 D) and the mean postoperative SE, -1.44 +/- 1.14 D (range 0 to -2.50 D) (P < .05). The safety index was 1.01 (mean postoperative BCVA 0.54 and mean preoperative BCVA 0.53; P = .77). The efficacy index was 0.53 (mean postoperative UCVA 0.28 and mean preoperative BCVA 0.53). None of the eyes had an induced astigmatism of more than 0.5 D. Twelve eyes regained their BCVA, 2 lost 1 line of BCVA, and 2 gained 1 line. Three eyes had grade 2 haze. No retinal complications were observed. CONCLUSION: In this study, LASIK for uniocular high myopia in pediatric eyes provided encouraging results in the management of select cases of anisometropic amblyopia when other measures failed. A larger study with a longer follow-up is necessary to determine the long-term effects.

Child↗
PubMed2000

Characterization of high affinity monoclonal antibodies specific for chlamydial lipopolysaccharide.

Pathogens belonging to the genus Chlamydia contain lipopolysaccharide with a 3-deoxy-D- manno- oct-2-ulosonic acid (Kdo) trisaccharide of the sequence alpha-Kdo-(2-->8)-alpha-Kdo-(2-->4)-alpha-Kdo. This lipopolysaccharide is recognized in a genus-specific pattern by murine monoclonal antibodies (mAbs), S25-23 and S25-2 (both IgG1kappa), which bind as the minimal structures the trisaccharide and the terminal Kdo-disaccharide, respectively. The variable domains of these mAbs were reverse transcribed from mRNA which was isolated from hybridomas and cloned as single-chain variable fragments (scFvs) in E.coli TG1. The kinetics of binding of whole antibodies, Fab fragments and scFvs to natural and synthetically modified ligands were determined by surface plasmon resonance (SPR) using synthetic neoglycoconjugates. As examples of an antibody-carbohydrate interaction involving anionic carboxyl groups on the ligand, we report that the affinities of these antibodies are higher than usually observed in carbo-hydrate-protein interactions (K(D)of 10(-3)to 10(-5)M). SPR analy-ses of monovalent Fab and scFv binding to the natural trisaccharide epitope gave dissociation constants of 770 nM for S25-2 and 350 nM for S25-23, as determined by global fitting (simultaneous fitting of several measurements at different antibody concentrations) of sensorgram data to a one-to-one interaction model. Local fitting (separate fitting of individual sensorgram data at different antibody concentrations) and Scatchard analysis of the data gave kinetic and affinity constants that were in good agreement with those obtained by global fitting. The SPR data also showed that while S25-2 bound well to several Kdo disaccharides and carboxyl-reduced Kdo ligands, S25-23 did not. Identification of amino acids in the complementarity determining regions revealed the presence of a large number of positively charged amino acids which were located towards the center of the combining site, thus suggesting a different recognition mechanism than that observed for neutral ligands. The latter mainly involves aromatic amino acids for hydrophobic stacking inter-actions and hydrogen bonds.

Amino Acid Sequence↗
PubMed1997

Aortic atherosclerosis and perioperative stroke in patients undergoing coronary artery bypass: role of intra-operative transesophageal echocardiography.

Intra-operative transesophageal echocardiography was performed in 126 patients undergoing coronary artery bypass grafting. Significant protruding atheromas (grade IV and V; Katz et al., 1992) were present in 12 patients (9.5%). Protruding atheromas had significantly higher incidence in patients above 60 years in age. Preoperative assessment with chest roentgenography and angiography, as well as intra-operative assessment by surgical palpation proved to be insensitive in detecting aortic atheromas. Out of four patients with grade V atheromas, two (50%) developed right hemiplegia postoperatively. For the rest, patients with grade V atheromas and eight patients with grade IV atheromas, surgical technique was modified and that helped in preventing occurrence of perioperative stroke.

Adult↗