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Biomedical subjects

R Varma

Publications and source records attributed to R Varma.

At least 37 records · Page 2Linked to original sources
PubMed2000

Tuberculosis of the sternum and clavicle: imaging findings in 15 patients.

OBJECTIVE: To describe the imaging findings in sterno-clavicular tubercular involvement. DESIGN AND PATIENTS: Fifteen patients with pathologically proven tuberculosis of the sternum and clavicle were retrospectively evaluated. Routine radiography, computed tomography (CT) and magnetic resonance imaging (MRI) were used in some or all of the patients. Clinical information and imaging features were evaluated in each case. RESULTS: Eight patients had sternoclavicular joint (SCJ) involvement, five had isolated sternal involvement and two had isolated clavicular involvement. Seven patients were evaluated with only CT, six with only MRI and two with both. There were eight male and seven female patients, varying in age between 16 and 78 years. Fever, swelling and pain were common presenting symptoms. Two patients were HIV positive. Radiographs were positive in only eight patients. Destruction and signal intensity (SI) changes of the sternum and clavicle, destruction of the cartilage, soft tissue changes representing granulation tissue/abscess, displacement of the adjacent structures (vessels, trachea, etc.) and inflammatory changes in the adjacent structures in the form of cellulitis and myositis were common imaging features. CONCLUSIONS: All imaging methods can provide complementary information regarding sterno-clavicular tubercular involvement that is helpful for determination of the therapy. MRI is useful in determining the extent of the lesion, particularly marrow involvement and soft tissue extent.

Adolescent↗
PubMed2000

Two-staged Baerveldt glaucoma implant for childhood glaucoma associated with Sturge-Weber syndrome.

PURPOSE: To report the outcome and complications of 10 eyes of 9 children with Sturge-Weber syndrome (SWS) who underwent two-stage insertion of a Baerveldt glaucoma implant (BGI) for glaucoma. DESIGN: Retrospective noncomparative case series. PARTICIPANTS: The authors reviewed the medical records of children under the age of 14 years with SWS who underwent two-stage BGI for glaucoma at two tertiary care referral centers. MAIN OUTCOME MEASURES: Intraoperative and postoperative complications, intraocular pressure (IOP), number of glaucoma medications, visual acuity, and further surgical intervention. RESULTS: Ten eyes of nine patients were included in the study. Ages of the nine patients at time of first stage BGI ranged between 6 weeks and 13 years. With average follow-up of 35 months (range, 10-50), all eyes had adequate IOP control (< or = 21 mmHg) without the need for additional glaucoma surgery. Intraocular pressure was reduced from a mean (+/- standard deviation) of 24.8 +/- 6.2 mmHg preoperatively to 16.9 +/- 2.3 mmHg at last follow-up visit (P = 0.001). The number of medications used for control of glaucoma was reduced from a mean (+/- standard deviation) of 1.8 +/- 1.0 preoperatively to 1.1 +/- 1.4 at last follow-up visit (P = 0.2). One eye had serous choroidal effusions with overlying serous retinal detachment that resolved spontaneously after 7 days with no permanent visual loss, and one eye had low choroidal effusion that lasted 4 days. There were no intraoperative or postoperative suprachoroidal hemorrhages. At last follow-up, visual acuity had improved by one or more lines in all patients in whom vision was measurable. CONCLUSIONS: Two-stage BGI surgery appears to be a safe and effective treatment for refractory glaucoma in children with SWS.

Adolescent↗
PubMed2000

Intramedullary tuberculomas. MR findings in seven patients.

PURPOSE: To describe the MR findings in intramedullary tuberculomas and to discuss the usefulness of MR in the management of this pathology. MATERIAL AND METHODS: A retrospective study of 7 patients from 21 to 60 years of age with clinical and radiological evidence of intramedullary tuberculomas was undertaken. Both T1- and T2-weighted images (WI) were obtained along with postcontrast T1WI. Signal intensities (SIs) of the granulomas were compared with SIs of the normal spinal cord. RESULTS: Six patients showed focus of tuberculosis elsewhere in the body. Six out of 7 showed fusiform swelling of the cord. Ill-defined iso-intensity (in 4 patients) to hyperintensity (in 3 patients) was seen at the site of granuloma on T1WI. On T2WI, 2 patients revealed a hypointense area (with disc enhancement). An iso-hypointense rim was seen surrounding a hyperintense centre in 5 patients (with rim enhancement). Adjacent oedema was seen in all patients. In 2 patients meningeal enhancement was also seen. In 2 patients the histopathology following surgical biopsy confirmed the diagnosis. In the remaining 5 patients, another known focus of tuberculosis elsewhere in the body and a marked response to antitubercular treatment was considered confirmatory for tuberculomas. CONCLUSION: Hypo- or iso-intensity on T2WI within the spinal cord with surrounding hyperintense oedema is suggestive of intramedullary tuberculomas. Central hyperintensities are also detected at times due to a variable amount of caseous necrosis with liquefaction. On T1WI, fusiform swelling of the cord is seen along with iso- to hyperintense foci, surrounded by hypointense oedema of the cord. Such findings should prompt a contrast-enhanced study, which may show single or conglomerate disc- or ring-enhancing lesions. MR thus plays an important role not only in detection and diagnosis, but also in deciding the treatment options and in the follow-up of those patients.

Adult↗
PubMed2000

Screening performance of functional and structural measurements of neural damage in open-angle glaucoma: a case-control study from the Baltimore Eye Survey.

PURPOSE: To compare the sensitivity and specificity of four approaches to glaucoma screening. METHODS: Case patients were persons with possible, probable, or definite glaucomatous optic nerve damage, as judged by a glaucoma specialist using Humphrey 24-2 threshold findings and clinical assessment of disc and nerve fiber layer, identified in the population-based Baltimore Eye Survey Follow-up Study. Control patients were participants in the same study, frequency-matched for age, without evidence of glaucomatous optic nerve damage. Participants underwent optic disc photography (Topcon ImageNet), disc imaging (GlaucomaScope), scanning laser polarimetry (Nerve Fiber Analyzer), and suprathreshold field testing (Dicon). RESULTS: A total of 100 case patients with open-angle glaucoma and 149 control patients were included. Objective imaging had the best screening performance. For the GlaucomaScope, a criterion of cup-to-disc ratio of -0.68 had a sensitivity of 72% and specificity of 82% for detecting eyes with definite or probable glaucomatous optic nerve damage. For the nerve fiber layer, a criterion of The Number as > or = 20 had a sensitivity of 69% and specificity of 77% for detecting eyes with definite or probable glaucomatous optic nerve damage. Usable data could be obtained in 93% of participants with the Dicon and the Nerve Fiber Analyzer and in 82% and 87% of participants with the GlaucomaScope and Topcon instruments, respectively. CONCLUSIONS: Vertical cup-to-disc ratio, as measured by the GlaucomaScope or Topcon instruments, and the Nerve Fiber Layer neural network Number had the best combination of sensitivity and specificity among the instruments tested. The Nerve Fiber Analyzer had the highest percentage of participants with usable data.

Aged↗
PubMed1999

Randomized clinical trial of the 350-mm2 versus the 500-mm2 Baerveldt implant: longer term results: is bigger better?

OBJECTIVE: To report the longer term results of a randomized, clinical trial comparing the 350-mm2 and the 500-mm2 Baerveldt glaucoma implants. DESIGN: Extended follow-up on a randomized, controlled trial. PARTICIPANTS: Between March 1991 and April 1993, 107 patients with uncontrolled intraocular pressure (IOP) due to non-neovascular glaucoma associated with aphakia, pseudophakia, or failed filters were randomly assigned for surgical placement of either the 350-mm or the 500-mm2 Baerveldt implant at the Doheny Eye Institute. METHODS: A random-numbers table was used to assign each patient to one of the two groups. Preoperative IOPs and visual acuities were recorded. Clinical records were reviewed to ascertain postoperative IOPs, visual acuities, number of medications used, and implant-related complications that occurred throughout the follow-up period. MAIN OUTCOME MEASURES: Success was defined as IOP of 6 mmHg or greater and of 21 mmHg or less in two or more consecutive follow-up visits without further glaucoma surgery or loss of light perception attributable to glaucoma. RESULTS: The overall success rates were 87% for the 350-mm2 group and 70% for the 500-mm2 group (P = 0.05). Average follow-up was 37 months (range, 1-76 months) for the 350-mm2 group and 34 months (range, 5-77 months) for the 500-mm2 group. The life-table success rates declined over time for both implant groups, from a high of 98% for the 350-mm2 group and 92% for the 500-mm2 group at 1 year to a cumulative success rate of 79% for the 350-mm2 group and 66% for the 500-mm2 group at 5 years. Visual acuities were better or remained the same in 50% of the patients in the 350-mm2 group and 46% of those in the 500-mm2 group. Complications during the 5-year follow-up were also statistically similar. CONCLUSIONS: The longer term results show that the 350-mm2 Baerveldt implant is more successful than the 500-mm2 implant for overall IOP control. Interval comparisons indicate a higher rate of success for the 350-mm2 implant in the first, second, third, fourth, and fifth years of implantation. Visual acuities, implant-related complications, and average IOPs were statistically indistinguishable between the two groups.

Adolescent↗
PubMed1999

Effects of some N-nitropyrazole derivatives on ocular blood flow and retinal function recovery after ischemic insult.

Ocular blood flow and retinal function were determined in this study with colored microspheres and b-wave amplitude of electroretinography, respectively. It was found that N-nitropyrazole analogs can facilitate the retinal function recovery efficiently after ischemic insult primarily through increase of choroidal blood flow specifically. Since age-related macular degeneration (AMD) is caused mainly by the choroidal vascular abnormality and/or insufficiency, these N-nitropyrazole analogs are of potential use in the treatment of AMD.

Animals↗
PubMed1999

The relationship between optic disc area and open-angle glaucoma: the Baltimore Eye Survey.

PURPOSE: To determine if eyes with larger optic disc area are more likely to have open-angle glaucoma or to have glaucoma at lower intraocular pressure (IOP). METHODS: Data were collected from a population-based sample of adults residing in East Baltimore, consisting of demographic information, ocular examinations, automated and static/kinetic visual field tests, IOP as measured by applanation tonometry, and image analysis of the optic disc. Optic disc area was calculated using refractive error to correct magnification. Open-angle glaucoma was defined by visual field and optic disc criteria. One eye from each of 75 patients with glaucoma was compared to those of 3,518 subjects without glaucoma. RESULTS: Although optic disc area was somewhat larger among patients with glaucoma than control subjects, in a regression model adjusting for age, gender, and race, the significance of this difference had a probability of 0.06. Among patients with glaucoma, disc area was not related to IOP level measured at study examination. CONCLUSION: Disc area is a weak risk factor for open-angle glaucoma. Disc area did not differ between patients with glaucoma who had lower IOP and those who had higher IOP among a group with glaucoma that were identified in a population survey.

Adult↗
PubMed1998

GPI-anchored proteins are organized in submicron domains at the cell surface.

Lateral heterogeneities in the classical fluid-mosaic model of cell membranes are now envisaged as domains or 'rafts' that are enriched in (glyco)sphingolipids, cholesterol, specific membrane proteins and glycosylphosphatidylinositol (GPI)-anchored proteins. These rafts dictate the sorting of associated proteins and/or provide sites for assembling cytoplasmic signalling molecules. However, there is no direct evidence that rafts exist in living cells. We have now measured the extent of energy transfer between isoforms of the folate receptor bound to a fluorescent analogue of folic acid, in terms of the dependence of fluorescence polarization on fluorophore densities in membranes. We find that the extent of energy transfer for the GPI-anchored folate-receptor isoform is density-independent, which is characteristic of organization in sub-pixel-sized domains at the surface of living cells; however, the extent of energy transfer for the transmembrane-anchored folate-receptor isoform was density-dependent, which is consistent with a random distribution. These domains are likely to be less than 70 nm in diameter and are disrupted by removal of cellular cholesterol. These results indicate that lipid-linked proteins are organized in cholesterol-dependent submicron-sized domains. Our methodology offers a new way of monitoring nanometre-scale association between molecules in living cells.

Animals↗
PubMed1998

Getting higher yields of monoclonal antibody in culture.

Getting higher yields of monoclonal antibody (MAb) is a problem in Hybridoma Technology which has two major bottlenecks: a) poor yield of hybridized cells, b) low cellular productivity of MAb in culture. There are three ways of obtaining high MAb yield in vitro a) Large scale culture, b) high density culture and c) enhancing individual cellular productivity in culture. Currently, the focus is on the correct synergistic combination of fortified nutrient media, bioreactor design and mode of operation. Maximization of cell culture longevity, maintenance of high specific antibody secretion rates, nutrient supplementation, waste product minimization and control of environmental conditions are important parameters for improvement of large scale production of MAb. Though, MAb yields have improved rapidly over the decade, there is a growing concern for the decrease in quality of MAb secreted. Further research is therefore necessary to take full advantage of MAb as a potential diagnostic agent for in vivo therapy.

Animals↗
PubMed1996

Retinal nerve fiber layer thickness in normal human eyes.

PURPOSE: To measure the histologic thickness of the retinal nerve fiber layer (RNFL) in normal human eyes. METHODS: Human eyes were obtained at autopsy within 6 hours postmortem. The retina was dissected into four quadrants and serially sectioned in historesin. The RNFL thickness was measured histologically in all four quadrants at the disc margin and at regular intervals from the disc margin. Measurements of the RNFL thickness also were obtained at the fovea and in the retinal periphery. RESULTS: Ten eyes of ten white individuals were studied. Age (mean +/- standard deviation) was 53.1 +/- 19.6 years (range, 18-76 years). For the eyes studied, the disc area (mean +/- standard deviation) and cup:disc ratio (mean +/- standard deviation) were 1.92 +/- 0.1 mm2 and 0.3 +/- 0.08, respectively. Mean superior, inferior, nasal, and temporal RNFL thickness at the disc margin was 405, 376, 372, and 316 microns, respectively. In all four quadrants, the RNFL thickness decreased with increasing distance from the disc margin. The average superior and inferior RNFL thickness was inversely related to age (P = 0.033, P = 0.097, respectively). The average RNFL thickness was not related to disc area. The average RNFL thickness just superior, inferior, nasal, and temporal to the foveola was 27, 34, 26, and 12 microns, respectively. The average RNFL thickness just posterior to the ora serrata in the superior, inferior, nasal, and temporal retinal periphery was 8 to 11 microns. CONCLUSION: The peripapillary RNFL thickness in humans is thicker than that seen in nonhuman primates. The thinnest peripapillary RNFL is in the region of the papillomacular bundle. These data can be used to determine the accuracy of NFL analyzers in obtaining in vivo RNFL thickness measurements.

Adolescent↗
PubMed1996

Fascia lata patch graft in glaucoma tube surgery.

PURPOSE: To determine if using human cadaveric fascia lata grafts to cover glaucoma implant tubes is safe and effective. METHODS: All patients who underwent glaucoma implant surgery at the Doheny Eye Institute between July 1993 and September 1993 received a fascia lata patch graft to cover the subconjunctival portion of the tube. These patients were followed prospectively for clinical signs of conjunctival breakdown, graft melt, tube erosion, graft-related inflammation, infection, and graft-related complications. RESULTS: Twenty-two eyes of 21 patients were followed for a mean of 19 months. All eyes tolerated the fascia lata grafts well without clinical evidence of graft-related conjunctival, scleral, or intraocular inflammation. No tube erosion or melting of the graft was observed in the study group. CONCLUSION: Preserved donor fascia lata was well tolerated as a grafting material in glaucoma implant surgery. No clinical signs of graft rejection, foreign body reaction, tube erosion, or graft melt were observed in the study group during the follow-up period.

Adolescent↗
PubMed1996

Heart in hypothyroidism--an echocardiographic study.

55 individuals, 44 of whom served as patients and 11 as controls were included in this study. Patient group was further divided into overt and subclinical hypothyroid group each having 22 patients. Patients were examined in a prospective manner and results compared with control group with an aim to evaluate the effect of hypothyroidism subclinical and overt on cardiac status by echocardiography. Variables of heart structure and function were assessed by cross sectional and Doppler echocardiography. IVS dimensions were significantly raised in moderate subclinical and in severe overt hypothyroidism (mean 0.911 +/- 0.038 and 0.973 +/- 0.217 cm). LVPW thickness was significantly increased only in overt hypothyroidism (mean 1.378 +/- 0.246). However RVW and LVID showed no definite pattern of change. Pericardial effusion and Diastolic dysfunction was seen in significant cases only in overt hypothyroidism. To conclude, hypothyroidism both subclinical and overt is associated with cardiovascular alteration both structural and functional. IVS and LVPW thickness are markedly affected, as well as there is impairment of left ventricular function more in diastole.

Diastole↗
PubMed1995

Neural rim area declines with increased intraocular pressure in urban Americans.

OBJECTIVE: To determine intraocular pressure (IOP)-related differences in the neural rim area among urban Americans without known optic nerve disease. DESIGN: Population-based prevalence study conducted in 16 cluster areas in East Baltimore, Md. PARTICIPANTS: A population-based sample of 1521 black and 1851 white individuals aged 40 years and older without evidence of optic nerve disease. MAIN OUTCOME MEASURE: Intraocular pressure-related differences in neural rim area, neural rim area-to-disc area ratio, and cup-to-disc ratio. RESULTS: We analyzed optic disc photographs using the Imagenet system (Topcon Instrument Corp of America, Paramus, NJ). After adjusting for age and disc area, white Americans had a 6% decrease in neural rim area for every 10-mm Hg increase in IOP (P = .0001). In black Americans, there was a quadratic relationship between neural rim area and IOP, with little decline with IOP up to approximately 17 mm Hg, after which neural rim area declined significantly with higher IOP (P = .001). Similarly, the neural rim area-to-disc area ratio decreased and the vertical cup-to-disc ratio increased with increasing IOP in both black and white Americans. CONCLUSIONS: The higher the level of IOP, the smaller was the amount of neural rim tissue in the optic disc for both black and white Americans. However, the relationship between IOP and neural rim area was different in whites and blacks.

Adult↗
PubMed1995

Pars plana Baerveldt tube insertion with vitrectomy in glaucomas associated with pseudophakia and aphakia.

PURPOSE: We reviewed the course of intraocular pressure, visual acuity, and complications in patients with shallow anterior chambers or vitreous prolapse who underwent insertion of glaucoma drainage tubes through the pars plana (after a complete posterior vitrectomy). METHODS: Thirteen patients (13 eyes) with uncontrolled glaucoma associated with shallow anterior chamber or vitreous prolapse and aphakia or pseudophakia underwent pars plana Baerveldt tube insertion after vitrectomy. RESULTS: In 11 eyes the intraocular pressure was less than or equal to 15 mm Hg at a minimum follow-up of one year; the other two eyes underwent additional glaucoma surgery. Two of the 11 eyes with controlled intraocular pressure had limitation of ocular motility postoperatively. No retinal complications had occurred in any of the 13 eyes. CONCLUSION: This technique of combined pars plana vitrectomy and pars plana insertion of a Baerveldt tube provides intraocular pressure control in eyes with shallow anterior chamber or vitreous prolapse and glaucoma associated with pseudophakia or aphakia.

Adolescent↗
PubMed1995

Comparison of clinician judgment with digitized image analysis in the detection of induced optic disk change in monkey eyes.

PURPOSE: To compare the ability of clinicians to detect change in the photographic appearance of the optic disk with the performance of a system for digitized image analysis. METHODS: In 11 monkey eyes, a Topcon Imagenet System was used to acquire eight digitized image pairs and four stereoscopic photographs at an intraocular pressure of 10 mm Hg, and then, again, 45 minutes after intraocular pressure was increased to 45 mm Hg. We recently reported detection of global (ten of 11 eyes) and regional (11 of 11 eyes) change in the digitized images of these eyes by using two new statistical strategies for optic disk analysis. For the current study, we evaluated the ability of three clinicians (the authors) to detect a change within the stereoscopic photographs of these 11 optic disks. For each eye, the eight stereoscopic photographs (four at intraocular pressure of 10 mm Hg and four at intraocular pressure of 45 mm Hg) were developed as stereoscopic slides and arranged into four pairs (10/10, 45/45, 10/45, and 45/10 mm Hg). Thus, two pairs represented no change in intraocular pressure (10/10 and 45/45 mm Hg) and the other two pairs represented either an increase or a decrease in intraocular pressure (10/45 and 45/10 mm Hg). The 44 pairs of stereoscopic slides (four pairs for each of 11 eyes) were masked then randomly mixed. On two separate occasions, each clinician evaluated each pair of stereoscopic slides for the presence of absence of optic disk change. RESULTS: Reproducibility between the two readings of each clinician ranged from .50 to .64 (kappa statistic). Clinicians correctly detected change (as detected by image analysis) within 45% to 64% of the 10/45 and 45/10 pairs of stereoscopic slides. Clinicians correctly indentified no change within 86% to 100% of the 10/10- and 45/45-mm Hg pairs of stereoscopic slides. Clinicians correctly identified no change significantly more often than change (P < .01, chi 2 test). Change was not detected consistently by all three clinicians in any of the 11 eyes. CONCLUSION: In a controlled experimental setting, digitized image acquisition with extensive secondary statistical analysis more sensitively detected small short-term changes in the surface of the optic disks of monkeys than did three masked clinicians.

Animals↗
PubMed1995

Early changes in optic disc compliance and surface position in experimental glaucoma.

PURPOSE: To detect changes in the compliance and baseline position (position at the baseline time point of a compliance test) of the monkey optic disc after the onset of chronic experimental glaucoma. METHODS: Sixty-six compliance tests were performed on 26 eyes of 13 monkeys. Longitudinal Study. In seven normal monkeys, compliance tests were performed three times in one eye (study eye) and once in the contralateral eye. In the study eye of five of these monkeys, chronic experimental glaucoma was then induced and compliance tests were performed at some or all of the following postglaucoma testing intervals: 1 to 2 weeks, 3 to 4 weeks, 5 to 8 weeks, 9 to 12 weeks, 13 to 18 weeks, and more than 18 weeks after the onset of elevated intraocular pressure (IOP). In the study eye of the remaining two monkeys, the optic nerve was transected, and compliance was tested at 5, 9, and 13 weeks after transection. An analysis of variance (ANOVA) was performed to detect an increase (hypercompliance) or decrease (rigidity) in the compliance of the glaucomatous eyes at each testing interval. A second ANOVA was performed to detect the onset of chronic posterior deformation of the baseline position of each disc. Cross-Sectional Study. In six additional monkeys with pre-existing experimental glaucoma, the glaucomatous study eye was compliance tested at one of the postglaucoma testing intervals used in the longitudinal study. The contralateral normal eye was compliance tested once. These data were then added to the data from the five longitudinally studied monkeys at the appropriate preglaucoma and postglaucoma testing intervals. A third ANOVA was done to compare the compliance of the expanded group of glaucomatous eyes at each postintervention testing interval with the compliance of the 13 normal contralateral eyes. RESULTS: Compliance. In the longitudinally (Pr > F = 0.0005) and cross-sectionally (Pr > F = 0.0001) studied glaucomatous eyes, optic disc compliance increased significantly by 1 to 2 weeks and then returned to a level statistically indistinguishable from normal within 13 to 18 weeks after the onset of glaucoma. In the transection eyes, the optic discs were significantly less compliant (more rigid) at 5 and 9 weeks after transection compared with the discs in either the normal or the glaucomatous eyes (Pr > F < 0.05). Baseline Optic Disc Position. Chronic posterior deformation of the disc was detected in one of three eyes tested 1 to 2 weeks and three of four eyes tested 3 to 4 weeks after the onset of glaucoma (Pr > F < 0.05). Chronic posterior deformation was not detected in the discs of either of the transection eyes at any of the post-transection testing intervals. CONCLUSION: Changes in optic disc compliance and surface position were detected by digitized image analysis within 2 to 4 weeks of the onset of experimental glaucoma in the monkey eye. These findings are unlikely to be due to axon loss alone, because they did not occur in optic nerve transection eyes (which constitute a model of axon loss in which intraocular pressures remain normal). The results suggest that IOP-related damage to the load-bearing connective tissues of the optic nerve head may occur early in the course of experimental glaucoma.

Analysis of Variance↗