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Biomedical subjects

S Parikh

Publications and source records attributed to S Parikh.

At least 55 records · Page 3Linked to original sources
PubMed1998

Isolated posterior capsule rupture in blunt trauma: pathogenesis and management.

Although blunt ocular trauma frequently-damages the crystalline lens, isolated rupture of the posterior capsule is an infrequently reported occurrence. The authors describe three patients with this unusual presentation. All patients underwent cataract extraction and intraocular lens (IOL) implantation using a limbal approach. There were no intraoperative complications. All patients achieved good postoperative visual acuity with well-positioned posterior chamber IOLs (in-the-bag in two eyes, sulcus fixated in one eye). Isolated rupture of the posterior capsule in young patients can be safely managed using the limbal approach and implantation of posterior chamber IOLs, is possible.

Adolescent↗
PubMed1997

Parabulbar anesthesia for primary vitreoretinal surgery.

PURPOSE: The efficacy and safety of parabulbar anesthesia was investigated prospectively in 100 patients undergoing primary vitreoretinal surgery. METHODS: The technique involved three steps: (1) orbicularis oculi injection, (2) subconjunctival injection, and (3) sub-Tenon irrigation. The effect of anesthesia was graded 0 to 5 depending on inadequate anesthesia-akinesia with or without local supplementation. Ninety-three patients underwent vitrectomy without buckling and 4 with an encircling band; 3 had scleral buckling. Mean duration of surgery was 89.38 minutes. RESULTS: In 69% of patients (grades 4 and 5), no supplementation was required and in 31% (grades 1-3), local supplementation was needed for inadequate anesthesia or akinesia or both. No ocular or systemic complication occurred. Early onset of anesthesia correlated with adequate anesthesia throughout the procedure (P < 0.04). CONCLUSIONS: Parabulbar anesthesia is a safe and effective technique of local anesthesia in patients undergoing primary vitreoretinal surgery.

Adult↗
PubMed1997

High intracellular calcium concentrations in transformed lymphoblasts from subjects with bipolar I disorder.

OBJECTIVE: Higher basal concentrations of intracellular calcium Ca2+ in platelets and lymphocytes from subjects with bipolar affective disorder than in unipolar depressed and healthy subjects implicate abnormal intracellular Ca2+ signaling in bipolar disorder. The purpose of this study was to clarify whether these intracellular Ca2+ abnormalities are trait related. METHOD: Basal Ca2+ concentration was measured by using ratiometric fluorescence assay with fura-2 for T lymphocytes and Epstein-Barr-virus-immortalized B lymphoblasts from physically healthy subjects with DSM-IV diagnoses of bipolar mood disorder (bipolar I, N = 28; bipolar II, N = 11) or major depressive disorder (N = 14), mixed psychiatric patients with non-mood disorders (N = 14), and health subjects (N = 20). Phytohemagglutinin-stimulated (10 micrograms/ml) intracellular Ca2+ levels were also determined in T lymphocytes. RESULTS: The basal Ca2+ concentration was significantly higher in the B lymphoblasts from patients with bipolar I disorder, but not bipolar II disorder or major depression, than in healthy subjects or psychiatric patients with nonmood disorders. There was a significant interaction between gender and diagnosis in the effect on basal Ca2+ levels in T lymphocytes. Contrasts of diagnoses within gender revealed significantly higher basal Ca2+ concentrations in T lymphocytes in male bipolar I patients, but not mean with bipolar II disorder or major depression, than in healthy male comparison subjects. Phytohemagglutinin-stimulated Ca2+ concentrations did not differ among groups, but the percent differences from basal Ca2+ levels were lower in bipolar I and depressed patients than in healthy subjects. CONCLUSIONS: These findings support the occurrence of abnormal calcium homeostasis in bipolar disorder and suggest that trait-dependent factors account, at least partly, for the higher basal lymphocyte Ca2+ concentration in bipolar I subjects.

Adult↗
PubMed1997

A case-control study of suprachoroidal hemorrhage during pars plana vitrectomy.

BACKGROUND AND OBJECTIVE: To investigate the risk factors associated with suprachoroidal hemorrhage (SCH) during vitrectomy. PATIENTS AND METHODS: Of 6971 pars plana vitrectomies performed between May 1988 and December 1994, SCH occurred intraoperatively in 12 (0.17%) cases. Forty-two age- and sex-matched control subjects were selected by computer-generated random numbers. Preoperative and intraoperative variables were subjected to univariate and conditional logistic regression analysis. RESULTS: Statistically significant risk factors for SCH after univariate analysis included myopia (P = .048), aphakia or pseudophakia (P = .024), rhegmatogenous retinal detachment (P = .044), scleral buckling and/or encirclage at vitrectomy (P = .029), and longer duration of surgery (P = .044). Multivariate analysis revealed independent risks associated with the absence of a lens and longer duration of the surgery. CONCLUSION: A knowledge of the risk factors involved with SCH helps the physician to identify patients who are at a greater risk for this complication.

Adult↗
PubMed1996

Endogenous cell seeding. Remnant endothelium after stenting enhances vascular repair.

BACKGROUND: Endothelial integrity is essential for maintaining vascular homeostasis, and endothelial denudation results in neointimal thickening. Balloon-expandable endovascular stents provide a luminal scaffolding within atherosclerotic arteries with minimal direct contact between balloon and endothelium. We wondered whether stents cause diminished endothelial ablation, and if so, whether the degree of endothelial damage might determine later proliferative sequelae. METHODS AND RESULTS: Stainless steel stents were expanded in normal or previously denuded iliac arteries of New Zealand White rabbits. Stented arteries were harvested 15 minutes, 1 hour, 3 days, or 14 days later. En face staining of the luminal surfaces of stented arteries demonstrated that endothelial cell loss began immediately after stent expansion and was restricted to interstices between stent struts. Remnant endothelium adjacent to struts provided the foundation for complete endothelial regeneration of the stented segment within 3 days. Both early monocyte adhesion and later intimal macrophage accumulation were reduced > 80% in nonballooned but stented arteries, in concert with a twofold reduction in intimal thickening after 14 days, compared with arteries completely denuded with a balloon before stent expansion. CONCLUSIONS: It is accepted that deep injury caused by balloon-expanded endovascular stents is a critical contributor to experimental stent-induced neointimal hyperplasia. Our data indicate that the degree of endothelial injury may also be an important component of vascular repair after stenting and an important consideration in stent and balloon design and use. The use of stents for primary endovascular intervention may allow partial retention of endothelium within treated arteries, thereby modulating vascular repair with less need for adjunctive pharmacological therapy.

Angioplasty, Balloon↗
PubMed1996

Management of peripheral vascular disease: innovative approaches using radiation therapy.

Despite the early successes at vascular recanalization with percutaneous transluminal angioplasty, vascular restenosis has emerged as a clinical problem of near epidemic proportions. Numerous pharmacologic and mechanical adjuncts have been tried with little success. Over the last few years, there have major advances in our understanding of the biology of the restenotic process. The process is now recognized as a proliferation disorder, and therapies akin to those used in the treatment of malignant diseases are being explored. Endovascular brachytherapy has shown strong potential in controlling this pathologic proliferative process in the laboratory and in early clinical studies. In this review we discuss some of the basic issues involved in vascular restenosis and the current status of endovascular brachytherapy.

Arteriosclerosis↗
PubMed1996

Changing the transition state for protein (Un) folding.

(Un)folding transition states of Saccharomyces cerevisiae iso-1-ferri- and ferrocytochromes c were studied using equilibrium and kinetic denaturation experiments. The wild-type protein and the global suppressor variant, N52I (isoleucine replaces asparagine 52), were examined. Denaturation was induced by guanidinium chloride (GdmCI) and monitored by circular dichroism (CD) spectropolarimetry without stopped-flow devices. Soret CD spectra indicate that thermal and GdmCl denatured states are different, and heat is the more effective denaturant. Equilibrium data show that the high stability of ferrocytochrome c can be rationalized as a requirement to bury the oxidation-induced positive charge and remain folded under physiological conditions. Kinetic data are monoexponential and permit characterization of the rate-limiting transition state for unfolding as a function of [GdmCl]. For the oxidized wild-type protein, the transition state solvent accessibility is nearly the same as that of the denatured state. Three perturbations, reducing the wild-type protein, reducing the N52I variant, and substituting position 52 in the oxidized protein, change the free energy and solvent accessibility of the transition state. In contrast, substituting position 52 in the reduced protein apparently does not change the transition state solvent accessibility, allowing more detailed characterization. In the reduced proteins' transition states at 4.3 M GdmCl, the position 52 side chain is in a denatured environment, even though transition state solvent accessibility is only one-third that of the denatured state (relative to the native state).

Asparagine↗
PubMed1996

Removal of silicone oil and epimacular proliferation from eyes following vitrectomy.

BACKGROUND AND OBJECTIVES: Epimacular proliferation (EMP) represents a localized form of reproliferation at the macula. The significance of EMP in eyes that have undergone vitrectomy is still not clear. This study investigated the redetachment rate following silicone oil removal when combined with removal of EMP. PATIENTS AND METHODS: Twenty-two consecutive eyes underwent removal of silicone oil and EMP These eyes had attached retinas following silicone oil injection used as an adjunct to complex vitreoretinal surgery. RESULTS: The retina remained attached in 19 (86.4%) of the eyes, with functional improvement it vision in 81.8% of the eyes. Visual acuity of 6/60 (20/200) or better was obtained in 12 (54.5%*) of the eyes. The mean follow-up time was 6.3 months. CONCLUSION: These results suggest that removal of EMP and silicone oil does not increase the risk of redetachment.

Adolescent↗
PubMed1995

Specific motifs in the external loops of connexin proteins can determine gap junction formation between chick heart myocytes.

1. Gap junction formation was compared in the absence and presence of small peptides containing extracellular loop sequences of gap junction (connexin) proteins by measuring the time taken for pairs of spontaneously beating embryonic chick heart myoballs to synchronize beat rates. Test peptides were derived from connexin 32. Non-homologous peptides were used as controls. Control pairs took 42 +/- 0.5 min (mean +/- S.E.M.; n = 1088) to synchronize. 2. Connexins 32 and 43, but not 26, were detected in gap junction plaques. The density and distribution of connexin immunolabelling varied between myoballs. 3. Peptides containing conserved motifs from extracellular loops 1 and 2 delayed gap junction formation. The steep portion of the dose-response relation lay between 30 and 300 microM peptide. 4. In loop 1, the conserved motifs QPG and SHVR were identified as being involved in junction formation. In loop 2, the conserved SRPTEK motif was important. The ability of peptides containing the SRPTEK motif to interfere with the formation of gap junctions was enhanced by amino acids from the putative membrane-spanning region. 5. Peptides from loop 1 and loop 2 were equivalently effective; there was no synergism between them. 6. The inclusion of conserved cysteines in test peptides did not make them more effective in the competition assay.

Amino Acid Sequence↗
PubMed1995

Recurrent intracranial epidermoid cyst treated with radiotherapy.

We report the case of a 58 year old woman with an epidermoid cyst of the right cerebello-pontine angle that was subtotally excised. She recurred 2 years later and received radiotherapy with resolution of symptoms and shrinkage of the cyst. The natural history of epidermoid cysts and the role of radiotherapy in their management is discussed.

Brain Diseases↗
PubMed1995

Prevention of tolerance to hemodynamic effects of nitrates with concomitant use of hydralazine in patients with chronic heart failure.

OBJECTIVES: This study was designed to determine the effect of oral hydralazine on the development of nitrate tolerance in patients with chronic congestive heart failure. BACKGROUND: Early development of nitrate tolerance with either continuous administration of intravenous or topical nitrate preparations or frequent dosing of oral nitrates leads to significant attenuation of nitrate-mediated hemodynamic and anti-ischemic effects. In recent animal experiments, prevention of nitroglycerin-induced hemodynamic tolerance with a concomitant use of hydralazine was demonstrated. This finding may have important clinical relevance. METHODS: Twenty-eight patients with chronic heart failure due to left ventricular systolic dysfunction were randomized to receive either a continuous infusion (24 h) of nitroglycerin alone (group I, 14 patients) or concomitantly with oral hydralazine (75 mg four times a day [group II, 14 patients]). The effect of nitroglycerin in each group was evaluated by analysis of variance for repeated measures. The power of the analysis to detect a 5.4-mm Hg (20%) change in mean pulmonary artery wedge pressure was 90%. RESULTS: Baseline hemodynamic variables as well as the initial hemodynamic response to nitroglycerin were comparable in both groups. Compared with the initial response to nitroglycerin, a significant attenuation of effect was found in group I at 24 h in mean (+/- SE) pulmonary artery pressure (27 +/- 4% vs. 10 +/- 3%, p < 0.05) and mean pulmonary artery wedge pressure (40 +/- 4% vs. 16 +/- 4%, p < 0.05). In group II, conversely, oral hydralazine prevented nitroglycerin-induced hemodynamic tolerance and resulted in a persistent effect on mean pulmonary artery and wedge pressures throughout the study period (31 +/- 3% vs. 27 +/- 4%, p = 0.13 and 37 +/- 4% vs. 34 +/- 6%, p = 0.40, respectively). In addition, the initial effect on blood pressure was attenuated at 24 h in group I (5 +/- 2% vs. 12 +/- 3%, p < 0.05) but not in group II (15 +/- 3% vs. 17 +/- 2%, p = 0.46). CONCLUSIONS: In patients with chronic heart failure due to left ventricular systolic dysfunction, the concomitant use of oral hydralazine prevents early development of nitrate tolerance and results in a persistent nitrate-mediated hemodynamic effect on systemic and pulmonary artery and left ventricular filling pressures. These data may support the concurrent use of hydralazine in patients with heart failure treated with organic nitrates.

Administration, Oral↗
PubMed1995

Neurologic characteristics of childhood lupus erythematosus.

Records of 108 patients with lupus erythematosus beginning in childhood (1953-1990) were reviewed; 25 had recorded neurologic findings. This is the largest group of childhood lupus erythematosus patients with neurologic disease that has been reported. The average age of children at the time of diagnosis of lupus was 154 months. There were 22 girls and 3 boys in the group. All patients met at least four of the 1982 American Rheumatism Association criteria for the classification of systemic lupus erythematosus. Average age at onset of neurologic difficulties was 168 months. In 4 patients, the neurologic symptoms preceded the diagnosis: 1 month (spastic diplegia), 1 month (bilateral weakness and spasticity), 24 months (chorea), and 26 months (chorea), respectively. Four patients had neurologic symptoms coincident with the diagnosis of lupus erythematosus. In those patients whose symptoms followed the diagnosis of lupus erythematosus, the average elapsed time until symptoms appeared was 33 months; the single lowest and highest outliers were discounted. Most frequent findings were headache (16/25) and behavioral aberrations (10/25). All behavioral manifestations were depression except in 1 patient. Other prevalent findings included hemichorea or chorea (7/25), cerebrovascular accident with hemiplegia or diplegia (7/25), seizures (5/25), visual loss (3/25), and cranial neuropathy (2/25). Vertigo and myelopathy occurred in 1 patient each. All patients were treated primarily with corticosteroids and azathioprine; in the presence of active disease, the drug dosages were increased with significant improvement in neurologic symptoms. Resolution usually occurred from days to months; most improved in a few days to a few weeks; 3-4 months was the longest period until symptoms subsided.

Adolescent↗
PubMed1995

The airflow resistance profile of healthy nasal cavities.

Distribution of resistance to respiratory airflow in the nasal cavities was determined by digitized pressure/flow measurements of consecutive 2-cm airway segments between nostril and nasopharynx. Healthy adult subjects seated in a head-out body plethysmograph breathed exclusively through a single nasal cavity while transnasal pressure and flow signals were transduced, digitized and processed by a programmed desk-top computer to provide resistance values. Mean total resistances of untreated and decongested single nasal cavities were 0.44 (n = 30; SD +/- 0.25) and 0.26 (n = 15; SD +/- 0.06) Pa/cm3/s, respectively. The proportion of total airway resistance of successive 2-cm segments from nostril to nasopharynx was 56%, 22%, 16%, and 6% in the untreated nose, and 88%, 5%, 2%, and 5% following decongestion. The findings from 45 nasal cavities are consistent with previous pressure/flow measurements from six nasal cavities and support recent acoustic reflection assessments of nasal cross-sectional areas of both untreated and decongested noses.

Adolescent↗
PubMed1995

Retinal detachment secondary to ocular perforation during retrobulbar anaesthesia.

The clinical characteristics and the retinal breaks associated with rhegmatogenous retinal detachments secondary to accidental globe perforation during local infiltration anaesthesia in five highly myopic eyes are presented. Retinal detachment was total with variable proliferative vitreoretinopathy. The pattern of retinal breaks was rather typical and predictable. Management involved vitreous surgery with internal tamponade by silicone oil in four eyes and perfluoropropane gas in one eye. At the last follow-up, all eyes had attached retina. One eye did not recover useful vision due to possible concurrent optic nerve damage.

Anesthesia, Local↗
PubMed1995

Endophthalmitis caused by anaerobic bacteria.

A retrospective analysis of 22 patients who underwent pars plana vitrectomy for endophthalmitis and had culture-proven anaerobic bacteria, was done. Elimination of infection with attached retina and recovery of ambulatory vision > or = 2/60 were considered as anatomic success and functional success, respectively. Mean follow-up period was 12.7 months (range, 2 to 48 months). Anatomic success was attained in 14 (63.6%) eyes and functional success in 12 (54.6%) eyes. A poor preoperative visual acuity was found to be associated with poor functional outcome (p < 0.046). In endophthalmitis, a routine anaerobic culture of intraocular specimen is recommended.

Adolescent↗
PubMed1993

Giant cell tumour of bone. A surgical approach to grade III tumours.

Thirty-one patients with giant cell tumours of bone (BGCT) were treated at our hospital by a conservative approach between 1975 and 1988. 94% of the tumours were grade III (Campanacci) and the follow up was from 2 to 13 years. In the 20 patients who had a modified intralesional excision (curettage) with bone grafting and cement, 5 recurrences occurred. There was one soft tissue recurrence in the 11 patients who had marginal or wide excisions. All recurrences were in grade III lesions. We conclude that grade III BGCT can be treated by modified intralesional excision provided the articular surfaces and part of the metaphysis are intact.

Adolescent↗