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Biomedical subjects

S K Pandey

Publications and source records attributed to S K Pandey.

At least 73 records · Page 4Linked to original sources
PubMed2000

Surgical prevention of posterior capsule opacification. Part 3: Intraocular lens optic barrier effect as a second line of defense.

PURPOSE: To emphasize an important aspect of preventing posterior capsule opacification (PCO), the barrier effect established by the optic of a posterior chamber intraocular lens (PC IOL), and present a new classification regarding capsular bag status after extra-capsular cataract extraction, including phacoemulsification. SETTING: Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. METHODS: This analysis included 150 consecutive eyes obtained postmortem with United States-manufactured PC IOLs including (1) poly(methyl methacrylate), (2) silicone, and (3) hydrophobic acrylic designs that were accessioned in the Center from September 1995 to January 1, 1998. Gross photographs from behind (Miyake-Apple views) were taken and serial histologic sections prepared. RESULTS: Microscopic analysis of the 150 eyes showed that the morphologic appearance of the capsular bag could be grouped into 2 categories: (1) those with little or no evidence of retained cortical material and cells, and (2) those with retained cortical material and cells in which a Soemmering's ring formed. With the latter, when a distinct barricade to cellular migration created by the IOL optic was noted, 2 discrete configurations occurred, depending on the different geometries of the optic components. With a classic biconvex optic with a curved and tapered edge, in many instances some ingrowth of cells proceeded posteriorly around the edge of the IOL optic in the direction of the central axis. With a lens optic that had a squared, truncated, and relatively thick edge, there was often abrupt termination of cells at the peripheral edge of the optic. The posterior capsule subtending the entire optic zone was therefore relatively or totally cell free. CONCLUSIONS: The barrier effect of the IOL optic appears to be of critical importance in retarding ingrowth of cells, functioning as a second line of defense when cortical cleanup is incomplete. Analysis of PC IOLs obtained postmortem showed that a square, truncated optic edge seemed to provide the maximum impediment to cell growth behind the IOL optic.

Acrylic Resins↗
PubMed2000

Surgical prevention of posterior capsule opacification. Part 1: Progress in eliminating this complication of cataract surgery.

PURPOSE: To evaluate over almost 2 decades the success of a component of cataract surgery that represents a critical step in reducing the incidence of posterior capsule opacification (PCO); namely, the efficacy of cortical cleanup. SETTING: Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Department of Ophthalmology, Medical University of South Carolina, Charleston, South Carolina, USA. METHODS: Accessioned from the early 1980s to 1997, 3320 eyes obtained postmortem with posterior chamber intraocular lenses were analyzed with respect to formation of a postoperative Soemmering's ring. This anatomic lesion, the precursor of clinical PCO, represents an important and measurable indication of the quality of cortical cleanup. Its formation was documented using Miyake-Apple posterior photographic analysis. RESULTS: The quality and thoroughness of cortical cleanup and overall effectiveness in eliminating retained and/or regenerating cortical cells, as measured by scoring of Soemmering's rings, showed virtually no net change since the early 1980s. The intensity of Soemmering's ring was higher in the most recent specimens than in those in the early 1980s. CONCLUSION: The results indicate that renewed attention to cortical cleanup in cataract surgery is warranted for significant reduction in incidence or the elimination of PCO. More attention to the hydrodissection (cortical cleaving hydrodissection) step of the procedure is likely a practical, immediately implementable, and inexpensive remedy.

Cadaver↗
PubMed2000

Surgical prevention of posterior capsule opacification. Part 2: Enhancement of cortical cleanup by focusing on hydrodissection.

PURPOSE: To experimentally analyze the role and efficacy of hydrodissection in achieving maximal cortical cleanup. SETTING: Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Department of Ophthalmology, Medical University of South Carolina, Charleston, South Carolina, USA. METHODS: Phacoemulsification and irrigation/aspiration were performed in 10 pairs of human eyes (20 eyes) obtained postmortem. Ten eyes had previous hydrodissection and 10 eyes, no hydrodissection. The time (seconds) required for complete lens substance removal in each procedure was measured. In addition, a qualitative evaluation of difficulty of surgery was noted. RESULTS: Phacoemulsification required 28.6% less time in eyes with previous hydrodissection than in those without. Irrigation/aspiration time was reduced by 50.9% when hydrodissection was performed. The total time of each procedure required for complete evacuation of the capsular bag was reduced by an average of 37.7% in eyes with hydrodissection. Furthermore, qualitatively the procedure was far easier, less stressful, and caused less posterior capsule stress or rupture when copious hydrodissection was performed. CONCLUSIONS: Hydrodissection enhances the general safety and efficiency of cortical cleanup, especially at 12 o'clock. Hydrodissection is the best available, practical, immediately implementable, and inexpensive means to help remove equatorial E-cells and thus alleviate the incidence of posterior capsule opacification.

Aged↗
PubMed2000

Creating cataracts of varying hardness to practice extracapsular cataract extraction and phacoemulsification(2).

We describe a method to harden the nucleus of crystalline lenses in postmortem human globes by intralenticular injection of a mixture of paraformaldehyde and glutaraldehyde (Karnovsky's solution). Evaluation of the nuclear manipulations, using the Miyake-Apple posterior video/photographic technique, shows that the method provides suitable specimens for practicing extracapsular cataract extraction and phacoemulsification.

Cataract↗
PubMed2000

Interlenticular opacification: clinicopathological correlation of a complication of posterior chamber piggyback intraocular lenses.

PURPOSE: To present a clinicopathological correlation of 2 pairs of piggyback posterior chamber intraocular lenses (PC IOLs) explanted because of opacification between the lens optics. SETTING: Gayton Health Center, Eyesight Associates of Middle Georgia, Warner Robins, Georgia, and Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. METHODS: Two pairs of piggyback AcrySof lenses were explanted from 2 patients with significant visual loss related to opacification between the optics. They were submitted for pathological analysis. Gross and histopathological examinations were performed, and photomicroscopy was used to document the results. RESULTS: Gross examination showed accumulation of a membrane-like white material between the lenses. Histopathological examination revealed that the tissue consisted of retained/proliferative lens epithelial cells (bladder cells or pearls) mixed with lens cortical material. CONCLUSION: Piggyback PC IOLs were explanted in 2 cases because of a newly described complication, interlenticular opacification. Three surgical means may help prevent this complication: meticulous cortical cleanup, especially in the equatorial region; creation of a relatively large continuous curvilinear capsulorhexis to sequester retained cells peripheral to the IOL optic within the equatorial fornix; insertion of the posterior IOL in the capsular bag and the anterior IOL in the ciliary sulcus to isolate retained cells from the interlenticular space.

Acrylic Resins↗
PubMed2000

An assessment of Maryland Medicaid's Rare and Expensive Case Management Program.

The Rare and Expensive Case Management Program provides intensive case management services to an especially vulnerable population comprised of primarily pediatric beneficiaries. This study examines the effect of the case management program on the pattern of costs. With its emphasis on obviating the need for acute care services and providing the necessary medical and assistive services in a timely manner, the case management program is expected to change the pattern of expenditures by category of service. Due to the low prevalence of conditions covered by the program, constituting a comparison group for the evaluation posed a major challenge. Employing an innovative methodological approach, a historical comparison group was modeled using statewide Medical Assistance claims files. The study design included a retrospective comparison of Medicaid beneficiaries enrolled in the program with a similar group before the case management program was implemented. The results bear out the anticipated pattern of shifts in cost of care from acute care to nonacute care services.

Case Management↗
PubMed1999

Phosphatidylinositol 3-kinase requirement in activation of the ras/C-raf-1/MEK/ERK and p70(s6k) signaling cascade by the insulinomimetic agent vanadyl sulfate.

The mechanisms by which inorganic salts of the trace element vanadium mediate their insulinomimetic effects are not clearly understood and were investigated. We have shown previously that vanadium salts activate mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase activities (PI3-K) via a pathway that does not involve the insulin receptor (IR) tyrosine kinase function [Pandey, S. K., Anand-Srivastava, M. B., and Srivastava, A. K. (1998) Biochemistry 37, 7006-7014]. Herein, we have examined a possible role of PI3-K in the vanadyl sulfate (VS)-mediated increase in the level of ras-MAPK activation as well as the contribution of signaling components upstream to MAPK in this VS response. Treatment of IR-overexpressing cells with VS resulted in an increased level of tyrosine phosphorylation of p44(mapk) (ERK-1) and p42(mapk) (ERK-2) along with stimulation of MAPK, MAPK kinase (MEK), and C-raf-1 activities, and ras activation. Preincubation with wortmannin and LY294002, two structurally and mechanistically different inhibitors of PI3-K, blocked the VS-mediated increase in MAPK activity and phosphorylation of ERK-1 and ERK-2. Furthermore, wortmannin inhibited activation of ras, C-raf-1, and MEK in response to VS. The addition of a farnesyltransferase inhibitor, B581, to cells reduced the level of MAPK activation as well as ERK-1 and ERK-2 phosphorylation stimulated by VS. Finally, VS increased PI3-K activity in ras immunoprecipitates. A VS-mediated increase in p70(s6k) activity was also found to be inhibited by wortmannin. Taken together, these results demonstrate that the insulinomimetic effects of VS may be mediated, in part, by PI3-K-dependent stimulation of the ras-MAPK and p70(s6k) pathways.

Androstadienes↗
PubMed1999

Visual results and postoperative complications of capsular bag and ciliary sulcus fixation of posterior chamber intraocular lenses in children with traumatic cataracts.

PURPOSE: To evaluate the visual results and postoperative complications of capsular bag and ciliary sulcus fixation of posterior chamber intraocular lenses (IOLs) for traumatic cataracts in children. SETTING: Department of Ophthalmology, Postgraduate Institute of Medical Education and Research, Chandigarh, India. METHODS: Twenty children (20 eyes) with traumatic cataracts had extracapsular cataract extraction (ECCE) and posterior chamber IOL implantation. They were randomly divided into 2 groups. Capsular bag fixation was performed in 10 children (Group A) and ciliary sulcus fixation in the other 10 (Group B). Traumatic cataracts associated with large corneal lacerations (10.0 mm or more), hyphema, angle recession, or posterior segment involvement were excluded. The best corrected visual acuity (BCVA) as well as early and delayed postoperative complications were prospectively evaluated in both groups. RESULTS: The BCVA was 6/12 or better in 9 eyes (90%) in Group A and 8 eyes (80%) in Group B at the end of the mean follow-up (24.6 months +/- 10.6 [SD]). Amblyopia (1 eye in Group A) and corneal scar and commotio retinae (1 eye each in Group B) accounted for a visual acuity of worse than 6/12. The residual refractive error did not exceed 3.50 diopters in either group. The incidences of fibrinous anterior uveitis and pupillary capture were significantly higher in Group B (P < .05, Fisher exact test). CONCLUSION: Capsular bag fixation of posterior chamber IOLs provided visual results similar to those with ciliary sulcus fixation but was associated with fewer postoperative complications, particularly uveitis and pupillary capture. This represents another important reason to attempt in-the-bag fixation in cases of traumatic cataract.

Cataract↗
PubMed1999

Efficacy of supratarsal dexamethasone versus triamcinolone injection in recalcitrant vernal keratoconjunctivitis.

PURPOSE: To compare the efficacy of supratarsal injection of short acting dexamethasone sodium phosphate versus intermediate acting triamcinolone acetonide as a new therapeutic modality for treating eyes with recalcitrant vernal keratoconjunctivitis (VKC). METHODS: The study was a prospective, randomized, double blind, case controlled trial, including 38 eyes of 19 patients with recalcitrant VKC. Except for two initial patients who received supratarsal injection of triamcinolone acetonide in both the eyes, one eye of each patient was randomly assigned to receive either 2 mg of dexamethasone sodium phosphate or 20 mg of triamcinolone acetonide. RESULTS: Both the drugs were equally effective with no statistically significant difference in the mean time of resolution of cobblestone papillae, limbal edema, shield ulcer, SPK and relief of symptoms. The recurrence rate of disease was, however, lower following triamcinolone acetonide injection. CONCLUSIONS: Supratarsal injection of corticosteroid is a cheap, effective and safe modality of treatment for managing eyes with recalcitrant VKC. Both short acting dexamethasone and intermediate acting triamcinolone acetonide are equally effective.

Adolescent↗
PubMed1998

Vanadyl sulfate-stimulated glycogen synthesis is associated with activation of phosphatidylinositol 3-kinase and is independent of insulin receptor tyrosine phosphorylation.

Salts of the trace element vanadium, such as sodium orthovanadate and vanadyl sulfate (VS), exhibit a myriad of insulin-like effects, including stimulation of glycogen synthesis and improvement of glucose homeostasis in type I and type II animal models of diabetes mellitus. However, the cellular mechanism by which these effects are mediated remains poorly characterized. We have shown earlier that different vanadium salts stimulate the MAP kinase pathway and ribosomal-S-6-kinase (p70s6k) in chinese hamster ovary cells overexpressing human insulin receptor (CHO-HIR cells) [Pandey, S. K., Chiasson, J.-L., and Srivastava, A. K. (1995) Mol. Cell. Biochem. 153, 69-78]. In the present studies, we have investigated if similar to insulin, VS also activates phosphatidylinositol 3-kinase (PI3-k) activity, and whether VS-induced activation of the PI3-k, MAP kinase, and p70s6k pathways contributes to glycogen synthesis. Treatment of CHO-HIR cells with VS resulted in increased glycogen synthesis and PI3-k activity which were blocked by pretreatment of the cells with wortmannin and LY294002, two specific inhibitors of PI3-k. On the other hand, PD98059 and rapamycin, specific inhibitors of the MAP kinase pathway and p70s6k, respectively, were unable to inhibit VS-stimulated glycogen synthesis. Moreover, VS-stimulated glycogen synthesis and PI3-k were observed without any change in the tyrosine phosphorylation of insulin receptor (IR) beta-subunit but were associated with increased tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1). In addition, PI3-k activation was detected in IRS-1 immunoprecipitates from VS-stimulated cells, indicating that tyrosine-phosphorylated IRS-1 was able to interact and thereby activate PI3-k in response to VS. Taken together, these results provide evidence that tyrosine phosphorylation of IRS-1 and activation of PI3-k play a key role in mediating the insulinomimetic effect of VS on glycogen synthesis independent of IR-tyrosine phosphorylation.

Androstadienes↗
PubMed1998

Potential mechanism(s) involved in the regulation of glycogen synthesis by insulin.

Stimulation of glycogen synthesis is one of the major physiological responses modulated by insulin. Although, details of the precise mechanism by which insulin action on glycogen synthesis is mediated remains uncertain, significant advances have been made to understand several steps in this process. Most importantly, recent studies have focussed on the possible role of glycogen synthase kinase-3 (GSK-3) and glycogen bound protein phosphatase-1 (PP-1G) in the activation of glycogen synthase (GS) - a key enzyme of glycogen metabolism. Evidence is also accumulating to establish a link between insulin receptor induced signaling pathway(s) and glycogen synthesis. This article summarizes the potential contribution of various elements of insulin signaling pathway such as mitogen activated protein kinase (MAPK), protein kinase B (PKB), and phosphatidyl inositol 3-kinase (PI3-K) in the activation of GS and glycogen synthesis.

Animals↗
PubMed1996

Modulation of G-protein expression by the angiotensin converting enzyme inhibitor captopril in hearts from spontaneously hypertensive rats. Relationship with adenylyl cyclase.

We have recently shown an enhanced expression of Gi alpha-2 and Gi alpha-3 at protein and mRNA levels and their relationship with adenylyl cyclase regulation in hearts and aorta from spontaneously hypertensive rats (SHR). The present studies were undertaken to examine if the antihypertensive action of captopril, an angiotensin I converting enzyme (ACE) inhibitor, is associated with the interaction and modulation of G-proteins and adenylyl cyclase activity. SHR and age-matched WKY were divided into two groups. One group of rats received captopril (10 mg/kg body weight) intravenously, whereas the other group received only vehicle (0.9% saline). The levels of Gi alpha-2 and Gi alpha-3 proteins were determined by immunoblotting technique using specific antisera against these proteins. The levels of Gi alpha-2 and Gi alpha-3 proteins were significantly enhanced in hearts from SHR as compared to WKY and captopril treatment restored the enhanced levels of Gi alpha-2 and Gi alpha-3 observed in SHR by about 70% to 80% towards WKY control rats. However, captopril slightly decreased the levels of Gi alpha 2 and Gi alpha 3 protein in normotensive WKY. In addition, the diminished stimulation of adenylyl cyclase by isoproterenol, glucagon and N-ethyl carboxamide adenosine and enhanced inhibition by inhibitory hormones such as C-type natriuretic peptide and angiotensin II observed in SHR was restored significantly by captopril treatment. These results suggest that one of the mechanisms by which captopril lowers the blood pressure may be due to its ability to modulate the levels of G-proteins and adenylyl cyclase activity.

Adenylyl Cyclases↗
PubMed1996

Paracetamol use, availability, and knowledge of toxicity among British and American adolescents.

Paracetamol is the commonest agent employed in self poisoning, however it is not clear whether adolescents possess insight into the serious complications associated with its misuse. Using a one page questionnaire, the availability, usage, and knowledge of toxicity of paracetamol among 1147 American and British adolescents was assessed. Although 90% of all students recognised that paracetamol could kill, the great majority of students overestimated the lethal dose. In addition, while knowledge regarding side effects of paracetamol was poor the drug was widely available to, and used by, the study population. It is proposed that gross overestimation of the number of tablets required to kill, poor understanding of paracetamol side effects, and wide availability of the drug contribute to its frequent use in adolescent suicidal behaviour. The inclusion of some over-the-counter medications in school drug education programs in addition to tighter control of the availability of paracetamol may help reduce the problem of adolescent self poisoning.

Acetaminophen↗
PubMed1991

Anatomical basis for the clinical application of the arterial supply of musculus pectoralis major.

The pattern of arterial supply to the various parts (clavicular, sternocostal and aponeurotic) of the pectoralis major muscle was studied in 7 cadaver dissections and 10 angiograms by injecting a radio-opaque substance. Three main arteries supplied the muscle, i.e. the pectoral branch of the thoracoacromial trunk (TAT-PB), the lateral thoracic artery and the perorating branch of the internal thoracic artery, supported by other branches of the TAT and the superior thoracic artery. It is observed that the TAT-PB, a chief vascular pedicle, anastomoses freely with other arteries and supplies most parts of the muscle. The present study is mainly focussed on the exclusion of the chief vascular pedicle of muscle to eliminate the confusion of previous studies and prevent the unnecessary hindrance and complications of the muscle flap.

Humans↗
PubMed1990

Study of squatting facet/extension of talus in both sexes.

Extensions of the trochlear surface and facets of the neck tali, i.e. the effects of squatting stress induced bone-remodelling, have been studied in samples from a North Indian population and examined for differences with those from other geographic sectors. Further, size and side of occurrence of the facets and extensions were analysed. Various squatting effects on the talus are found to be more common in this zone in general and in females in particular. The differences are appraised in the sociophysiologic context of life style in the studied population. The study reasonably emphasizes the need for elaboration of impact, that stress induced bone remodelling may have on physical and sports performance especially that of the females and possible preventive and corrective measures.

Anthropology, Cultural↗