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Biomedical subjects

N Sharma

Publications and source records attributed to N Sharma.

At least 163 records · Page 9Linked to original sources
PubMed1998

Modified phacoemulsification in situ.

We describe a phacoemulsification technique for cataracts in eyes with anticipated weak zonular apparatus. After central sculpting, a crater 90% deep is made. A horizontal fracture is created with the phaco probe and chopper. The nucleus is chopped, dividing the inferior hemisection into 2 pie-shaped pieces, which are then emulsified. Without rotating the nucleus, a groove is made at the superior hemisection and a vertical fracture created with the chopper. The bevel of the phaco probe is then turned down to emulsify each quadrant separately. This technique is especially useful in eyes with weakened zonular apparatus such as those with hypermature cataract, uveitis, long-standing glaucoma, trauma, retinitis pigmentosa, and operated retinal detachments.

Cataract↗
PubMed1998

Conversion from phacoemulsification to extracapsular cataract extraction: incidence, risk factors, and visual outcome.

PURPOSE: To evaluate the incidence, risk factors, and visual outcome in cases converted from phacoemulsification to routine extracapsular cataract extraction (ECCE). SETTING: Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India. METHODS: A retrospective study was performed in 540 eyes that had clear corneal phacoemulsification performed by an experienced phacoemulsification surgeon. The cases in which phacoemulsification was initiated and then converted to ECCE were studied. The main parameters evaluated were the factors responsible for the conversion, corneal endothelial cell loss, and visual outcome. RESULTS: Twenty eyes (3.7%) required conversion to ECCE during phacoemulsification. Pupillary miosis (6 cases), posterior capsule rupture (5 cases), prolonged phaco time (4 cases), posterior extension of the capsulorhexis (2 cases), corneal thermal burn (1 case), subluxation of the lens (1 case), and malfunctioning of the ultrasonic handpiece (1 case) were the reasons for the conversion. The mean percentage of endothelial cell loss was 11.06% +/- 2.3 (SD); 18 cases (90.0%) achieved a visual acuity of 20/40 or better at 6 weeks. CONCLUSIONS: Intraoperative pupillary miosis, posterior capsule rupture, and very hard nuclear cataract causing prolonged phacoemulsification were the major risk factors for conversion to ECCE. Optimal preoperative preparation and prompt recognition of complications during phacoemulsification can lead to timely conversion to ECCE to achieve a good visual outcome.

Cell Count↗
PubMed1998

Topical pefloxacin in bacterial keratitis.

PROBLEM: To evaluate the clinical efficacy and safety of topical pefloxacin 0.3% drops as the sole antibiotic used to treat culture positive bacterial corneal ulcers. METHODS: Forty two consecutive Gram's smear-positive cases of bacterial corneal ulcers were enrolled for this prospective open labelled clinical trial. All patients underwent a complete clinical and microbiological work up and were put on topical 0.3% pefloxacin drops with supportive cycloplegic, vitamins and antiglaucoma therapy. Of 42 cases, 4 cases of mycotic keratitis and 6 culture negative cases were excluded from the study. RESULTS: Positive microbiologic cultures were obtained in 84.2% (32 of 38) cases. Staphylococcus aureus (14/32; 43.7%) and coagulase negative Staphylococci (12/32; 37.5%) were the two most common organisms isolated. Resolution of the corneal ulcer was achieved in 31 out of 32 cases (96.9%) with a mean duration of 9.3+/-5.3 days (range 3-21 days). Best corrected visual acuity of 20/200 or better was achieved in 65.6% of cases at 4 weeks post resolution. Corneal deposits were observed in one case which disappeared 8 days following discontinuation of therapy. CONCLUSIONS: Topical pefloxacin is effective as a single antibiotic agent for the treatment of bacterial keratitis.

Adolescent↗
PubMed1998

Sympathetic ophthalmia associated with antecedent adherent leucoma--a rare association.

PURPOSE: To report a rare association of sympathetic ophthalmia with an antecedent adherent leucoma. METHOD: A 40-year-old patient with an adherent leucoma developed sympathetic ophthalmia in the fellow eye, 15 years after the occurrence of a perforated corneal ulcer. RESULTS: Intravenous pulse dexamethasone therapy followed by tapering oral prednisolone led to complete resolution of the disease process in the sympathising eye. CONCLUSION: Patients with an adherent leucoma subsequent to a perforated corneal ulcer may remain at an increased risk of developing sympathetic ophthalmia during their lifetime.

Administration, Oral↗
PubMed1998

Prone position ultrasonography in silicone filled eyes.

PURPOSE: To evaluate the efficacy of a new technique of prone position ultrasonography in cases with silicone filled eyes. METHODS: Forty patients with prior pars plana vitrectomy and silicone oil instillation referred to a tertiary eye care centre were the subjects of this study. A prospective clinical trial was undertaken to evaluate the efficacy of prone position ultrasonography in addition to routinely performed supine position ultrasonography in these patients. The technique was undertaken by 2 independent observers and compared with the findings by indirect ophthalmoscopy or surgical results. Interobserver variability was also calculated. RESULTS: Two spikes were observed in supine position corresponding to the intravitreal silicone oil surface and the sclera, whereas a single spike corresponding to the sclera was observed in prone position. Supine position ultrasonography yielded a diagnostic accuracy of 61.8%, which increased to 96.7% when the procedure was supplemented with prone position ultrasonography. Specificity increased from 75 to 100% by the addition of this adjuvant procedure, however, with no significant difference in the interobserver variability ('K'=0.67 Vs 'K'= 0.62). CONCLUSION: Prone position ultrasonography is a useful adjunct to the routinely performed supine position ultrasonography in silicone filled eyes and increases the diagnostic yield.

Diagnostic Techniques, Ophthalmological↗
PubMed1998

Corneal superinfection in acute hemorrhagic conjunctivitis.

PURPOSE: This study aimed to evaluate the clinical profile, microbial spectrum, management modalities, and visual outcome in cases of corneal superinfection that occurred after an epidemic of acute hemorrhagic conjunctivitis. METHOD: A retrospective analysis of 14 eyes of 13 patients who were referred to a tertiary eye-care center with corneal ulceration after an episode of acute hemorrhagic conjunctivitis was undertaken. The parameters analyzed were age, sex, prior use of topical medications, predisposing factors, ulcer characteristics, organisms isolated, success of medical therapy and surgery, and visual outcome. RESULTS: A definite history of topical corticosteroid use to treat acute hemorrhagic conjunctivitis was elicited in 12 (86%) eyes. Cultures were positive in 86% (12/14) eyes. Organisms isolated were Pseudomonas aeruginosa (three eyes, 25%), Fusarium species (three eyes, 25%), Aspergillus species (two eyes, 16%), and Staphylococcus aureus (two eyes, 16%). Mixed infection occurred in two patients. After discontinuation of topical corticosteroids, all patients received antimicrobial therapy. The keratitis resolved in seven eyes. Therapeutic penetrating keratoplasty was required in five eyes. Two patients were lost to follow-up. CONCLUSIONS: Corneal superinfection may occur after acute hemorrhagic conjunctivitis. Use of topical corticosteroids to treat acute hemorrhagic conjunctivitis may predispose an already compromised cornea to develop microbial keratitis and such a practice should be discouraged.

Adolescent↗
PubMed1998

Combined astigmatic keratotomy with corneal valvular incision in the treatment of high surgical astigmatism.

BACKGROUND: Astigmatic keratotomy is used conventionally to correct moderate surgical astigmatism. However, cases with very high surgical astigmatism due to wound compression can show a dramatic response to relaxing keratotomies made in the steeper meridian. The effect obtained cannot be predicted pre-operatively by using standard nomograms. METHODS: Coupled arcuate keratotomies combined with corneal valvular incisions were performed in a case of high astigmatism post-cataract surgery. RESULTS/CONCLUSION: Coupled arcuate keratotomies were combined with a corneal valvular incision enabled a surgical correction of nearly 9 D of astigmatism.

Astigmatism↗
PubMed1998

Post-penetrating keratoplasty glaucoma: risk factors, management and visual outcome.

PURPOSE: To evaluate the incidence, associated risk factors, graft status and treatment modalities in patients with post-penetrating keratoplasty glaucoma. METHODS: A retrospective analysis of 747 consecutive penetrating keratoplasties was undertaken at a tertiary eye care centre. The frequency of post-penetrating keratoplasty glaucoma was determined and correlated with the pre-operative corneal diagnosis, lens status and associated surgeries performed during penetrating keratoplasty. The response to antiglaucoma therapy (i.e. medical, surgical or cyclo-destructive procedures) and graft outcome was also evaluated. RESULTS: The incidence of post-penetrating keratoplasty glaucoma was 10.6% (79/747). Pre-operative corneal diagnosis of adherent leucomas was significantly associated with the development of postoperative glaucoma. Post-penetrating keratoplasty glaucoma was significantly higher in aphakes (odds ratio (OR) 6.6; confidence interval (CI) 3.81-11.69) compared with phakic or pseudophakic eyes. Associated vitrectomy (OR 2.32; CI 1.16-4.73) and anterior segment reconstruction (OR 3.31; CI 1.43-7.72) were other high-risk factors. Most patients responded to medical therapy (41/79; 51.9%), whereas filtering surgery and cyclo-destructive procedures were performed in 29.1 (23/79) and 19% (15/79) of eyes, respectively. Despite clear grafts in 39 eyes (49.4%), visual acuity of 6/18 or better was achieved in 15 eyes (18.9%). CONCLUSIONS: A high incidence of post-penetrating keratoplasty glaucoma occurs in eyes with adherent leucomas. Anterior vitrectomy and associated surgeries further accentuate the risk Anti-glaucoma therapy may not achieve optimum visual outcome, despite a clear graft.

Antihypertensive Agents↗
PubMed1998

Association between anterior and posterior keratoconus.

BACKGROUND/METHODS: We studied a 53-year-old male patient, presenting with a history of reduced vision since childhood in the right eye and since birth in the left eye. RESULTS: Ocular examination revealed the presence of anterior keratoconus in the right eye and posterior keratoconus in the left eye. CONCLUSION: To our knowledge, co-occurrence of both varieties of keratoconus in the same patient has not been previously reported.

Anterior Chamber↗
PubMed1998

Imaging of the liver with helical CT: a survey of scanning techniques.

OBJECTIVE: We conducted a survey of the members of the Society of Computed Body Tomography/Magnetic Resonance to assess current techniques in liver imaging using helical CT. MATERIALS AND METHODS: The survey, which was designed to update earlier surveys from 1987 and 1993, included a questionnaire distributed to 77 members of the Society of Computed Body Tomography/Magnetic Resonance. RESULTS: Forty-nine members responded, representing 28 institutions. In 1993, 19% (5/26) of institutions used helical scanners, compared with 82% (23/28) in 1996. The group of institutions with helical CT served as the focus of this survey. In 1993, 58% of institutions used 1-cm collimation: in 1996, 78% (18/23) used thinner, 7- to 8-mm collimation. In 1987, 41% used power injectors compared with 85% in 1993 and 100% in 1996. In 1996, monophasic injections were used by 96% (22/23) of institutions. In 1993, most institutions used a contrast material injection rate of 1.5-2.0 ml/sec; in 1996, most used a 2.5-3.0 ml/sec injection rate. In 1993, 96% of institutions used 125-150 ml of contrast material; in 1996, 57% (13/23) of institutions used 125-150 ml and 30% of institutions used less than 125 ml of contrast material. A delay time of 21-45 see was used by 83% of institutions in 1993, whereas in 1996, 83% (19/23) of institutions used a longer delay time of 50-80 sec. In 1996, 13% of institutions used an individual scan delay technology and all institutions performed multiphasic scanning of hypervascular lesions. CONCLUSION: The availability of helical CT has changed radiologists' approach to liver imaging. The greatest effects of which are a more widespread use of power injectors, longer delay times, thinner collimation, increased contrast material injection rates, decreased contrast material volumes, and multiphasic scanning.

Contrast Media↗
PubMed1997

Sustained stress and fixed interval performance.

The effects of sustained stress on response rate and temporal patterning (quarter-life) of rats performing either a previously learned fixed-interval schedule (FI 60) or learning an FI 60 simultaneously with stress onset were determined. Rats lived 24 h/day in operant cages, where they earned all of their food via lever-pressing. During the stress portion of each experiment, one group of rats was able to avoid or escape signalled intermittent footshock (Avoidance/ Escape Group), a second group (Yoked) did not have control over shock termination, a third group never received shock (Control). Shock trials were presented around the clock at approximately 5-min intervals and the stress portion of each study lasted 1-2 weeks. We have previously reported that rats tolerate this paradigm well and avoid/escape 99% of the shock trials. In rats previously trained on the FI task, both rate of responding and quarter-life values were significantly decreased on the first day of stress for both the Avoidance/Escape and Yoked Groups. Food intakes and quarter-life values were not significantly different from the controls by stress Days 3 and 2, respectively. In the acquisition study, controls learned the F1 task by Day 4 as judged by quarter-life of responding. FI task acquisition was significantly impaired in stressed rats compared to controls, not reaching asymptotic performance until Day 9 of stress. There were no major differences between the 2 stress groups in either study. These data demonstrate that stress may impair both the rate and patterning of behavior, and suggest that this rodent paradigm may usefully model some aspects of the effects of stress in humans.

Animals↗
PubMed1997

Retroperitoneal laparoscopic management of urolithiasis.

Laparoscopic retroperitoneal pyelolithomy (Lap PL) and ureterolithotomy (Lap UL) were performed in 20 and 24 patients, respectively. The average operating time was 61.4 minutes for Lap UL and 80.2 minutes for Lap PL. The conversion rate for Lap PL was 4 (20%) patients, and none of the Lap ULs required conversion. There were no major postoperative complications, except prolonged tube drainage in 2 patients, and the average hospital stay was 3.6 days.

Adult↗
PubMed1997

A compartmental model of water radon contamination in the human body.

A multicompartmental model is developed to simulate the biokinetics in the human body following the ingestion of an inert gas. It was assumed that 100% of the radon ingested appears in the stomach, from which it is transported through the body to different organs via the blood stream. Each of these organs absorbs and releases radon differently, and, amongst all, the fat retains radon for the longest time. To test the model, the information on elimination rates of 222Rn in expired breath was obtained from other experiments done at the University of Maine. The data included male and female participants with a wide range of ages and physical activity levels. The radiation doses in the different organs and tissues were computed. As was expected, the stomach sustained the maximum dose. In this study, the highest stomach dose to any volunteer was evaluated as 115 mSv y(-1).

Adolescent↗
PubMed1997

Genetic mapping of genes regulating the thymus size in back-cross rats between the laboratory BUF/Mna strain and the MITE strain derived from the wild rat, Rattus norvegicus.

The thymoma prone BUF/Mna (B) rat is a useful model for studying the genes responsible for thymus enlargement during the stage of young growth. Among the strains of rats, B rats have the largest thymuses at all stages of life. A locus, Ten-1, which contributes to thymus enlargement in back-cross (BC) rats between the B and WKY/NCrj (W) strains, was mapped on chromosome 1. To determine the precise location of the locus, ¿B x(B x MITE)F1¿ BC rats were generated by crossing the B strain with the inbred MITE (M) strain, which was established from captured, Japanese wild rats, and were examined by linkage study using polymerase chain reaction with 67 microsatellite markers. Linkages with thymus enlargement were found in genotypes of seven markers, BSIS, LSN, MYL2, IGF2, PBPC2, D1Mgh11, and D1MIt6, by chi2-test and Student's t-test, which confirmed the presence of the genetic locus associated with thymus enlargement, Ten-1, in this region. Paradoxically, a suppressive locus, Tsu-1, to thymus enlargement was also found on chromosome 3, showing linkages of phenotype of the small thymus with genotypes of SCN2A, CAT, D3MIt16, and D3MIt13. By analyses of MAPMAKER/EXP and MAPMAKER/QTL, Ten-1 was mapped at 4.6 cM proximal from IGF2 locus on chromosome 1 and Tsu-1 at 4.0 cM proximal from CAT locus on chromosome 3, respectively.

Animals↗
PubMed1997

Evidence for alpha 2-adrenoceptor agonist activity of minoxidil.

The present investigation was undertaken to study the mechanism of action of minoxidil using various smooth muscle preparations. Minoxidil (4.7 x 10(-6) M to 4.7 x 10(-4) M) produced a concentration-dependent inhibition of field stimulation-evoked responses in rat anococcygeus muscle and vas deferens. The inhibition produced by minoxidil was antagonized by yohimbine (2.5 x 10(-7) M). Minoxidil (1.4 x 10(-5) M to 4.7 x 10(-4) M) also produced a concentration-dependent relaxation in oestrogen-primed potassium chloride-depolarized rat uterus. These responses were blocked not only by yohimbine but also by glibenclamide (2.02 x 10(-8) M). Our results suggest that minoxidil possesses alpha 2-adrenoceptor agonist activity in addition to potassium-channel-opening activity.

Adrenergic alpha-Agonists↗
PubMed1997

Mycotic keratitis in children: epidemiologic and microbiologic evaluation.

PURPOSE: To evaluate the demographic features, clinical profile, and laboratory diagnosis in cases of mycotic keratitis in children. METHODS: We retrospectively analyzed 211 cases of mycotic keratitis in children younger than 16 years over a 5-year period in a tertiary eye center. Culture-proven cases of fungal keratitis were reviewed. RESULTS: Trauma was the most common predisposing factor (55.3%), followed by associated systemic illness (11.2%), previous ocular surgery (9.8%), and others. Corneal injury contaminated with vegetable matter was responsible for 60.5% of traumatic cases. Aspergillus species were the most frequent isolates (39.5%). Others included Fusarium (10.7%), Alternaria (10.2%), Curvularia (7.4%), and Penicillium (7%). A seasonal variation in the incidence of mycotic keratitis revealed a peak incidence in the months of September and October. One hundred sixty-two children (76.7%) cooperated for examination and scraping under topical anesthesia with or without sedation. General anesthesia for scraping was required in 49 (23%) of 211 children for corneal scraping. Gram stains of corneal scraping were positive for hyphal elements in 54.5% of cases, and potassium hydroxide wet-mount preparation was positive in 90.2% of cases. CONCLUSIONS: This study highlights important risk factors and organisms responsible for mycotic keratitis in children.

Adolescent↗
PubMed1996

Bcl-2 prevents CD95 (Fas/APO-1)-induced degradation of lamin B and poly(ADP-ribose) polymerase and restores the NF-kappaB signaling pathway.

In the study presented here, we investigated the possible interactions between CD95 (Fas/APO-1) and Bcl-2 by studying the effects of Bcl-2 on the modulation of cellular pathways activated by CD95 using HeLa cells as a model system. We report that stable expression of Bcl-2 in HeLa cells is associated with multiple phenotypic changes. Treatment of HeLa cells with anti-CD95 monoclonal antibody (mAb) resulted in preferential degradation of lamin B compared with lamins A and C. Significant lamin B degradation was detected as early as 1 h after anti-CD95 mAb treatment. In contrast, lamins A and C as well as actin remained unchanged until 4 h after treatment with anti-CD95 mAb, a time point that correlated with the period of DNA fragmentation. These results indicate that selective degradation of lamin B is an early cellular event in response to activation of the CD95 pathway and that it precedes DNA fragmentation. Overexpression of Bcl-2 resulted in prevention of lamin B degradation and DNA fragmentation into oligonucleosome fragments in response to the apoptotic signal by anti-CD95 mAb. In addition, in Bcl-2-overexpressing cells that were protected against apoptosis, anti-CD95 mAb-induced cleavage of poly(ADP-ribose) polymerase was completely blocked. Overexpression of Bcl-2 also resulted in restoration of the CD95-mediated signaling pathway involving activation of the transcription factor NF-kappaB (p50/RelA). These findings suggest that Bcl-2 prevents apoptosis in part by preventing the degradation of major nuclear polypeptides such as lamin B and poly(ADP-ribose) polymerase. In addition, our results demonstrate that CD95-mediated signaling involves activation of NF-kappaB (p50/RelA).

Apoptosis↗