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Biomedical subjects

J T Thompson

Publications and source records attributed to J T Thompson.

At least 55 records · Page 3Linked to original sources
PubMed1993

Retreatment of full-thickness macular holes persisting after prior vitrectomy. A pilot study.

PURPOSE: Vitrectomy with fluid-gas exchange has been shown to close more than one half of full-thickness macular holes, with improvement in visual acuity. By adding the appropriate dose of transforming growth factor-beta 2, a higher success rate has been reported. However, there still remain cases of macular holes that fail to close after vitreous surgery. The current pilot study is designed to determine whether reoperation may have a role in the management of cases that fail after vitreous surgery. METHODS: Twelve eyes with persistent full-thickness macular holes that failed to close after an initial vitrectomy underwent reoperation using 1330 ng transforming growth factor-beta 2. RESULTS: After the second operation, closure occurred in 12 (100%) of 12 eyes. Follow-up ranged from 8 to 16 months. Visual acuity also improved by two or more lines in 5 (42%) of 12 patients. Increased nuclear sclerosis occurred in nine (90%) of the ten phakic eyes. Of the five eyes showing visual improvement, four required cataract extraction and intraocular lens implantation. CONCLUSION: Retreatment of persistent full-thickness macular holes with transforming growth factor-beta 2 appears to have a beneficial effect on both neurosensory retinal flattening and visual outcome.

Adult↗
PubMed1993

Assessment of vision in idiopathic macular holes with macular microperimetry using the scanning laser ophthalmoscope.

BACKGROUND: Visual loss in eyes with full-thickness macular holes has been thought to be due to the absence of retinal function in the area of neurosensory defect as well as loss or reduction of retinal function in the surrounding area of neurosensory retinal detachment. With the advent of surgical techniques to treat macular holes, it is increasingly important to better characterize this visual dysfunction. METHODS: Thirty eyes of 30 patients with full-thickness idiopathic macular holes were evaluated with microperimetry using the scanning laser ophthalmoscope to detect and quantitate absolute and relative scotomata within the central 40 degrees of visual field. A log 2 scale of test stimulus intensities was established. Results of microperimetry were compared with best-corrected visual acuities as measured on the logarithmic Early Treatment of Diabetic Retinopathy Study chart as well as duration of symptoms. RESULTS: All 30 eyes showed an absolute scotoma in the area of neurosensory defect as well as surrounding relative scotomata in the area of neurosensory detachment. Best-corrected visual acuity was correlated with the size of the absolute and relative scotomata (P < 0.002). The sizes of the scotomata were correlated with the duration of symptoms of the macular holes (P < 0.05). CONCLUSION: Microperimetry using the scanning laser ophthalmoscope demonstrates that the visual loss associated with macular holes is related to the reduction of retinal function in the area of the surrounding neurosensory detachment as well as the absence of retinal function in the area of neurosensory defect. The size of the scotomata, determined by microperimetry, is correlated with the patient's visual acuity as well as the duration of symptoms of the macular hole.

Adult↗
PubMed1993

Infectious endophthalmitis after penetrating injuries with retained intraocular foreign bodies. National Eye Trauma System.

PURPOSE: To determine the risk factors and prognostic indicators of infectious endophthalmitis in eyes with penetrating injury and retained intraocular foreign body. METHODS: From the National Eye Trauma System (NETS) Registry, 492 eyes with intraocular foreign bodies were reviewed for signs of infectious endophthalmitis. RESULTS: Thirty-four eyes (6.9%) with intraocular foreign bodies had evidence of infectious endophthalmitis, and 31 (91.2%) of those eyes had signs of infection at the time of removal of the intraocular foreign body. The majority of eyes with an intraocular foreign body with or without endophthalmitis were in patients between 10 and 39 years of age, but the risk of endophthalmitis developing increased with age, especially in patients 50 years of age or older with delayed primary repair (P = 0.005). Endophthalmitis was more likely to develop in eyes with home or occupational injuries (33/358, 9.2%) than in those with injuries from other settings (1/128, 0.8%; P = 0.001). Infectious endophthalmitis was much less likely to develop in eyes with primary repair within 24 hours of the injury (10/287 = 3.5%) than in eyes with primary repair more than 24 hours after the injury (22/164, 13.4%; P < 0.0001). Bacilli or staphylococci were isolated in 21 (95%) of 22 eyes with positive cultures. Visual prognosis was reasonably good with 15 (58%) of 26 eyes attaining a visual acuity of 20/200 or better. CONCLUSIONS: Removal of a retained intraocular foreign body within 24 hours of injury markedly reduces the risk of infectious endophthalmitis developing. Older persons are at high risk for endophthalmitis developing after retaining an intraocular foreign body when there is delayed surgical repair.

Adolescent↗
PubMed1993

The effect of pars plana vitrectomy and transforming growth factor-beta 2 without epiretinal membrane peeling on full-thickness macular holes.

PURPOSE: Surgical techniques for the treatment of macular holes generally include removal of the overlying cortical vitreous and/or epiretinal membranes. The authors demonstrate that by using vitrectomy, posterior hyaloid removal, fluid-gas exchange, and transforming growth factor-beta 2 (TGF-beta 2), a growth factor that modulates the wound healing process, epiretinal membrane peeling can be avoided and the surgical procedure thereby simplified without compromising results. METHODS: A total of 24 eyes of 24 patients with stage 2, 3, or 4 full-thickness macular holes were treated. Of 24 patients, 1 was lost to follow-up after suffering a stroke; the remaining 23 (17 females and 6 males) (age range, 11-81 years; mean, 64 years) were followed for 5 to 16 months (mean, 12 months). Preoperative best-corrected visual acuity ranged from 20/50 to 20/400 (mean, 20/125). A standardized vitrectomy was performed with posterior hyaloid removal and, after a near-complete fluid-air exchange, 0.1 ml of a solution containing 1330 ng of TGF-beta 2 was instilled over the macular hole. No attempts were made to peel epiretinal membranes or drain fluid from the macular hole. RESULTS: Of 23 eyes, 22 (96%) had resolution of the surrounding subretinal fluid and flattening of the macular hole (1 patient required a second procedure, in which visual improvement of 20/30 was achieved); 11 (48%) had visual acuities of 20/40 or better, 19 (85%) had visual acuities of 20/60 or better, and 19 (85%) showed an improvement in visual acuity of at least two lines (mean, 3.8 lines). The authors saw no retinal pigment epithelial mottling. CONCLUSION: The authors' results demonstrate that treatment of macular holes using vitrectomy, fluid-gas exchange, and the instillation of a solution containing TGF-beta 2, without epiretinal membrane peeling, maintains efficacy while simplifying surgery.

Adolescent↗
PubMed1993

RET-PE10: a 61 kD polypeptide epitope expressed late during vertebrate RPE maturation.

PURPOSE: This study sought To learn more about the mechanisms that determine and maintain the differentiated state of the retinal pigment epithelium (RPE). METHODS: Monoclonal antibodies were raised against human RPE and used in conjunction with other antibodies. Immunocytochemical and biochemical analyses were performed on tissue sections and cells in culture. RESULTS: An RPE-specific epitope, RET-PE10, has been detected as a 61 kD cytoplasmic polypeptide in a variety of mammalian, amphibian, and avian species. In the rat, RPE-PE10 was expressed late in eye development, with a faint initial labelling of the RPE in central regions at postnatal day 9 (PN9) that increased to adult levels and extent of staining by PN14. RET-PE10 expression initially was present in overnight cultures of dissociated rat RPE cells but was lost rapidly from these cultures during the first week. Comparison of the staining patterns of RET-PE10 with those of various cytoskeletal elements suggests that RET-PE10 may be associated with part of the intermediate filament network. Culture of whole eyecups also resulted in a loss of RET-PE10 expression. RET-PE10 expression was normal in eyes of adult rd/rd mutant mice. CONCLUSIONS: RET-PE10 is a late-appearing marker of RPE differentiation. The results also suggest that the maintained expression of RET-PE10 depends upon extrinsic factors but that these do not include maintained contact with Bruch's membrane or light-induced retinal activity.

Animals↗
PubMed1993

Transforming growth factor-beta 2 significantly enhances the ability to flatten the rim of subretinal fluid surrounding macular holes. Preliminary anatomic results of a multicenter prospective randomized study.

Previous studies of treatment of full-thickness macular holes have effected resolution of the surrounding subretinal fluid cuff in 58%-71% of cases. An initial report has found 330 ng and 1,330 ng transforming growth factor-beta 2 to be successful in effecting resolution of the surrounding subretinal fluid cuff in 100% of cases. A randomized, masked, controlled, prospective, multicenter study of 90 patients with full-thickness macular holes was performed to assess the efficacy of the local application of TGF-beta 2 at the time of vitrectomy surgery. Eligibility criteria included: (1) best corrected visual acuity of 20/80 or worse; (2) duration of macular hole for less than 1 year; and (3) absence of other ocular disorders that might interfere with vision. Patients were evenly randomized to receive placebo, 660 ng transforming growth factor-beta 2, or 1,330 ng transforming growth factor-beta 2. The treatment assignment was unmasked at the examination 3 months after treatment only if the macular hole failed to close. If the initial treatment had been placebo, patients were offered crossover to 1,330 ng transforming growth factor-beta 2 during a reoperation. It can be deduced that resolution of the subretinal fluid cuff occurred in 16 of 30 placebo-treated eyes, 53 of 58 eyes treated with transforming growth factor-beta 2, and in 9 of 13 cases (69%) initially treated with placebo that subsequently underwent repeat surgery under the crossover option.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

The absorption of mixtures of air and perfluoropropane after pars plana vitrectomy.

The duration of mixtures of perfluoropropane and air (0% to 20% C3F8) were analyzed in 206 eyes following pars plana vitrectomy for a variety of vitreoretinal disorders using a noninvasive model for calculating the intraocular gas bubble volume. The accuracy of the noninvasive model was tested by comparing the estimated bubble volume with the actual volume withdrawn from 12 eyes with intraocular gas bubbles undergoing a subsequent vitrectomy. The method for estimating intraocular bubble volume had a mean difference between the actual and estimated bubble volume of 0.1 +/- 0.35 mL. The half-life of air (0% C3F8) was 1.3 +/- 0.1 days; 5% C3F8, 4.2 +/- 0.1 days; 10% C3F8, 6.5 +/- 0.2 days; 15% C3F8, 8.0 +/- 0.6 days; and 20% C3F8, 12.5 +/- 1.1 days. The difference between each half-life was statistically significant (P < .01). Linear regression analysis of the half-lives of C3F8 mixtures of up to 20% C3F8 showed a linear increase in half-lives with increasing concentrations of C3F8. The duration of intraocular gas tamponade can be controlled by selecting the appropriate concentration of air and C3F8.

Absorption↗
PubMed1992

Isolated lung transplantation for end-stage lung disease: a viable therapy.

Since January 1990, we have performed 29 isolated lung transplantations in 28 patients with end-stage lung disease (12 single, 16 bilateral). Recipient diagnoses were: cystic fibrosis (11), chronic obstructive pulmonary disease (6), pulmonary fibrosis (6), eosinophilic granulomatosis (1), postinfectious lung disease (1), adult respiratory distress syndrome (1), and primary pulmonary hypertension (2). There have been four deaths, two in patients with pulmonary fibrosis and two in patients with primary pulmonary hypertension. Four patients have undergone transplantation while on ventilatory support for respiratory failure (2 with cystic fibrosis, 1 having redo lung transplantation with cystic fibrosis, and 1 with adult respiratory distress syndrome); all of these have survived. Six patients required cardiopulmonary bypass, which was associated with increased transfusion requirement. All patients 2 months after discharge have returned to an active life-style, except for 2 patients who currently await retransplantation. Preoperative pulmonary rehabilitation has resulted in significant improvement in exercise performance in all patients. Immunosuppression consists of cyclosporine, azathioprine, and antilymphoblast globulin (University of Minnesota), withholding systemic steroids in the early postoperative period. We have employed bronchial omentopexy in all but four transplants; there has been one partial bronchial dehiscence, two instances of bronchomalacia requiring internal stenting, and one airway stenosis. Cytomegalovirus disease has been seen frequently (15 cases), but has responded well to treatment with ganciclovir. Other complication shave included one drug-related prolonged postoperative ventilation, thrombosis of a left lung after bilateral lung transplantation requiring retransplantation, five episodes of unilateral phrenic nerve palsy after bilateral lung transplantation (4 resolved), and the requirement of massive transfusion (greater than 10 units) in 5 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Lasers in dermatology and ophthalmology.

Dermatology and ophthalmology are two specialties that have made exceptional use of laser technology. In dermatology, port wine stains and hemangiomas, neoplastic lesions, and adnexal tumors are amenable to laser treatment. In ophthalmology, the use of lasers to effect photocoagulation, photoradiation, photovaporization, photodisruption, and photodecomposition has permitted the treatment of vascular retinal disease, macular edema, intraocular tumors, open angle glaucoma, and angle closure glaucoma. Although great strides in laser technology have been made, the future is even more promising as laser devices are further modified to treat specific disease processes.

Eye Diseases↗
PubMed1992

Retinal cartography. An analysis of two-dimensional and three-dimensional mapping of the retina.

The current two-dimensional (2D) retinal drawing chart is an azimuth equidistant representation of the retina. The distortion produced by this chart was analyzed and compared to other 2D projections, such as stereographic, equal area, and orthographic maps of the retina. Circumferential distortion was calculated for lesions at varying distances from the macula using the azimuth equidistant retinal map and was found to increase exponentially as a function of the distance from the macula. Circumferential distortion was 57.1% at the equator, 88.5% 3 mm anterior to the equator, and 137.8% 6 mm anterior to the equator. A three-dimensional (3D) model of the retinal surface was created using 3D computer assisted design (CAD) software. This 3D model was able to represent retinal lesions such that their true size, shape, location, and orientation were all conserved. Retinal lesions could be viewed from multiple angles and examined in cross section. The use of 3D CAD software coupled with ultrasound or magnetic resonance imaging data has the potential to represent retinal lesions more accurately than current methods.

Choroid Neoplasms↗
PubMed1991

Microinjection of the dopamine antagonist cis-flupenthixol into the MPOA impairs copulation, penile reflexes and sexual motivation in male rats.

Microinjection of the dopamine antagonist cis-flupenthixol into the medial preoptic area was previously shown to impair male rat copulatory behavior. The present experiments provide further evidence of cis-flupenthixol's inhibitory effects on male sexual behavior. Following microinjections of moderate to high doses of cis-flupenthixol, males exhibited slower copulatory rates and fewer ejaculations in copula, fewer ex copula erections and penile movements, and reduced sexual motivation in an X-maze. Locomotion in the X-maze was not significantly affected. Microinjections of the inactive isomer trans-flupenthixol produced no change in any behavioral measure, indicating that cis-flupenthixol's effects were receptor mediated. We suggest that dopamine receptors in the MPOA influence copulation primarily by regulating reflexive and motivational factors, but not locomotion.

Animals↗
PubMed1991

Dose dependent D2 effects on genital reflexes after MPOA injections of quinelorane and apomorphine.

This study investigated the effects on genital reflexes of unilateral MPOA injections of 0.1, 1, 3, and 10 micrograms of the D2 agonist quinelorane (LY-163502), and of 3 micrograms quinelorane administered together with 3 micrograms of the D1 antagonist SCH-23390. In addition, the effects of an MPOA injection of 10 micrograms apomorphine were tested. All but the lowest dose of quinelorane significantly decreased the latency to the first reflex. The 3 and 10 micrograms doses of quinelorane, and the combination of quinelorane and SCH-23390, decreased the total number of reflexes. In addition, 10 micrograms quinelorane increased the number of seminal emissions. 10 micrograms apomorphine, like 10 micrograms quinelorane, decreased the latency to the first reflex and increased the number of seminal emissions, but did not decrease the numbers of erections or penile movements. The ratio of D1/D2 activity may influence the number of erections displayed during ex copula testing.

Animals↗
PubMed1991

D2 receptors in the paraventricular nucleus regulate genital responses and copulation in male rats.

The D2 dopamine receptor agonist quinelorane (LY-163502), microinjected into the paraventricular nucleus (PVN), affected genital response of restrained supine male rats in a biphasic dose-dependent fashion. A moderate dose (1 microgram) facilitated penile responses (intense erections and penile movements), and decreased the latency to the first response. A high dose of quinelorane (10 micrograms) facilitated seminal emission while inhibiting penile responses. The addition of the D1 antagonist SCH-23390 to the 1 microgram dose of quinelorane potentiated quinelorane's increase in seminal emission. We suggest that D1 receptors in the PVN may be antagonistic to D2 receptor-mediated seminal emission, and possibly also penile responses. In copulation tests 1 microgram quinelorane decreased mount latency, whereas 10 micrograms quinelorane increased mount and intromission latencies and slowed copulatory rate. Both 1 and 10 micrograms quinelorane, and also 1 and 10 micrograms of the mixed D1 and D2 agonist apomorphine, decreased the number of intromissions preceding ejaculation.

Animals↗
PubMed1990

Dopamine receptors in the ventral tegmental area modulate male sexual behavior in rats.

The mesocorticolimbic dopamine tract is considered to be a substrate for motivation and reward as well as for locomotor behavior. The present experiments assessed the role of dopamine cell bodies in the ventral tegmental area (VTA), the source of this tract, in the copulatory behavior of male rats. The dopamine agonist apomorphine or the dopamine antagonist cis-flupenthixol were microinjected into the VTA immediately before sexual behavior tests with a receptive female. Apomorphine delayed the onset of copulation and slowed its rate, presumably by stimulating somatodendritic autoreceptors and thereby decreasing the firing rate of VTA neurons. Control injections of apomorphine into the substantia nigra were without effect. cis-Flupenthixol, which would have blocked autoreceptors and thereby depolarized VTA neurons, shortened the latency to begin copulating in those animals that did copulate; however, fewer animals exhibited sexual behavior. One possible explanation for the apparently contradictory effects of cis-flupenthixol may be that VTA neurons increased their rate of firing in some animals, leading to a faster onset of copulation, but that in other animals depolarization block in a substantial number of neurons resulted in a lack of copulation. These results are consistent with a contribution of the mesocorticolimbic dopamine tract to motivational and/or motor aspects of male copulatory behavior.

Action Potentials↗
PubMed1990

Flow dynamics of extrusion needle vacuuming in a closed vitrectomy system.

The dynamics of pressure, flow, and ocular volume relationships were examined with respect to extrusion needle use in simulated vitrectomy. Glass-stoppered bottles used with infusion lines with drip chambers lowered the intraocular pressure 4 to 7 inches below the fluid level in the bottle, varying with the amount of fluid in the bottle. Compared with flow rates using the regular tip needle with the steel infusion cannula, the disposable infusion cannula lowered the flow rate by about 25% and the tapered tip extrusion needle decreased outflow by 40% to 50%. Tracer dilution rates were decreased by the use of the disposable infusion port or the aphakic model eye; however, 2 minutes of infusion at a 30-inch bottle height dilution was still sufficient to wash out the tracer to less than 5% of the original concentration.

Humans↗
PubMed1990

Assessment of visual-field changes before and after focal photocoagulation for clinically significant diabetic macular edema.

Visual fields were compared before and after focal photocoagulation for eyes with nonproliferative diabetic retinopathy and clinically significant diabetic macular edema. A total of 8 eyes was tested before treatment and 6-8 weeks after treatment using static automated visual fields (Octopus). The visual-field indices, mean defect (MD) and corrected loss variance, were employed as measures of retinal sensitivity. Our results show that focal photocoagulation (CLV) generally depressed sensitivity (increased MD) in the treated central 10 degrees field, whereas in the untreated control region (10-30 degrees) sensitivity generally remained stable. However, the whole-field indices indicated that overall the fields remained stable following focal photocoagulation treatment. These results suggest that although focal treatment produces local absolute visual-field defects, the effects are small relative to the global indices.

Adult↗