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J T Thompson

Publications and source records attributed to J T Thompson.

At least 73 records · Page 4Linked to original sources
PubMed1990

Assessment of the dynamics of allograft rejection utilizing Tc-99m labeled lymphocytes.

The feasibility of utilizing technetium 99m (Tc-99m) lymphocytes labeled by a modified stannous chloride technique for the assessment of cardiac allograft rejection was examined. Syngeneic lymphocytes were labeled with Tc-99m at 125 microCi per 10(7) cells. Mean labeling efficiency was 67 +/- 17%, n = 44. Two groups of rats allogeneic (ALLO) (ACI/Lewis) and syngeneic (SYN) (Lewis/Lewis) were injected with labeled cells at two, four, five, and seven days post cardiac graft. At 20 hr post-injection, transplant and native hearts were harvested for radioanalysis and histology. Ratio of percent dose per gram transplant heart to native heart (T/N) revealed a significant difference between ALLO (T/N = 2.7 +/- 0.23, n = 5) and SYN (T/N = 1.73 +/- 0.12, n = 5) at two days P[F] = 0.0045. Maximum difference occurred at five days with ALLO mean T/N of 6.40 +/- 0.54, n = 5 (P[F] = 0.0001). There was no significant difference at seven days post graft with ALLO 2.85 +/- 0.30, n = 5 and SYN 2.02 +/- 0.05, n = 5 (P[F] = 0.0166). SYN rat T/Ns did not change significantly (mean 1.83 +/- 0.10, n = 18) at the various time periods.

Animals↗
PubMed1990

RPE-mediated collagen gel contraction. Inhibition by colchicine and stimulation by TGF-beta.

Retinal detachment secondary to proliferative vitreoretinopathy (PVR) is often precipitated by traction on the retina from preretinal membranes and traction on the vitreous base. Contraction and proliferation of retinal pigment epithelial (RPE) cells appear to play an important role in the pathogenesis of PVR. Contraction of collagen gels by human RPE cells was evaluated as a model of tractional forces on the vitreous gel. The area of collagen gels with admixed RPE cells in 15-mm wells was measured daily. The collagen gels contracted to less than 50% of original area in 89% of wells. Colchicine (0.01-1 microM) inhibited RPE-induced collagen gel contraction, whereas 1 ng/ml of transforming growth factor-beta enhanced it. Potential stimulators or inhibitors of RPE-mediated gel contraction can be tested using this model.

Aged↗
PubMed1989

The effects of intracranial administration of the dopamine agonist apomorphine on penile reflexes and seminal emission in the rat.

Previous studies employing systemic administration of the dopamine agonist apomorphine have shown that the dose response curves for apomorphine's effects on penile reflexes and seminal emission differ, suggesting that experimentally separable populations of dopamine receptors regulate these two responses. The present experiments examined the locations of central nervous system DA receptors mediating genital responses in the restrained, supine rate by injecting apomorphine into the medial preoptic area and the paraventricular nucleus through chronic, indwelling cannulae. Medial preoptic area injections facilitated penile reflexes, but not seminal emission, while paraventricular injections facilitated seminal emission. These results suggest that systemically administered apomorphine may facilitate penile reflexes by acting on the medial preoptic area and may enhance seminal emission by acting on the paraventricular nucleus.

Animals↗
PubMed1989

Kinetics of intraocular gases. Disappearance of air, sulfur hexafluoride, and perfluoropropane after pars plana vitrectomy.

Intraocular gas bubbles are an important source of internal tamponade for the treatment of retinal breaks in eyes requiring vitrectomy. The kinetics of disappearance of air, 20% sulfur hexafluoride, and 10% perfluoropropane were prospectively evaluated in 76 eyes undergoing pars plana vitrectomy. The absorption of each gas approximated a first-order kinetic equation with respect to bubble volume. The half-life of air was 1.6 days in phakic and 0.9 days in aphakic eyes. The half-life of 20% sulfur hexafluoride was 2.8 days in phakic and 2.4 days in aphakic eyes. The half-life of 10% perfluoropropane was 5.7 days in phakic, 4.5 days in aphakic, and 4.3 days in pseudophakic eyes. The difference in half-life among the three gases was significant. Intraocular gases had a shorter half-life in aphakic than in phakic eyes.

Absorption↗
PubMed1989

The effects of intrathecal administration of the dopamine agonist apomorphine on penile reflexes and copulation in the male rat.

Relatively high doses of systemically administered apomorphine inhibit penile reflexes. It is possible that these inhibitory effects are due, at least in part, to actions of apomorphine on the lumbosacral spinal cord. The present experiments examined this possibility by injecting apomorphine (10 and 50 micrograms/5.0 microliters vehicle) into the lumbosacral subarachnoid space through chronic, indwelling cannulae. Such injections impaired ex copula penile reflexes, slowed the rate of copulation, and decreased the number of intromissions preceding ejaculation. These results suggest that lumbosacral cord dopamine receptors may normally regulate male sexual performance.

Animals↗
PubMed1989

Quinelorane (LY163502), a D2 dopamine receptor agonist, facilitates seminal emission, but inhibits penile erection in the rat.

Dopaminergic compounds have been shown to facilitate male sexual responses in various contexts. We investigated the effects of a specific D2 dopamine receptor agonist, quinelorane (LY163502), on sexual responses elicited in the restrained supine male rat (i.e., ex copula reflex tests). Penile erections, evoked by retraction of the penile sheath, were inhibited by systemic administration of 10 micrograms/kg quinelorane; however, the occurrence of seminal emission was dramatically increased. A smaller dose of 0.25 ng/kg was without effect. In a second experiment, intracranial microinjection of quinelorane was followed by ex copula reflex tests. The medial preoptic area (MPOA) has been previously implicated in the dopaminergic regulation of male copulatory behavior. The effects of an intra-MPOA injection of quinelorane on seminal emission and erectile responses were similar to those observed following systemic administration. These results are consistent with the hypothesis that DA receptors in the MPOA are important in the regulation of male sexual behavior and suggest that D2 receptors in the MPOA may decrease ejaculatory threshold while inhibiting erectile mechanisms.

Animals↗
PubMed1989

D2/D1 ratio in the medial preoptic area affects copulation of male rats.

The D1/D2 dopamine agonist apomorphine, microinjected into the medial preoptic area (MPOA), facilitates male rat sexual behavior and the D1/D2 antagonist cis-flupenthixol in the MPOA impairs it. The present study investigated the roles of D1 and D2 receptors in the regulation of copulation by microinjecting drugs selective for these receptors into the MPOA. The D2 agonist LY-163502 delayed the onset and slowed the rate of copulation and also reduced the number of vaginal intromissions required to trigger ejaculation (reduced ejaculatory threshold). The D1 agonist SKF-82526 had no effect, either alone or together with LY-163502. The D1 antagonist SCH-23390 delayed the onset of copulation and decreased ejaculatory threshold, as had the D2 agonist. A low dose of the D2 agonist alone and together with the D1 antagonist delayed the onset of copulation and reduced ejaculatory threshold; the combination of drugs was more effective than LY-163502 alone. Only the combination of drugs slowed the rate of copulation and delayed the resumption of copulation after an ejaculation. Thus, increasing the D2/D1 ratio in the MPOA, by selective stimulation of D2 and/or antagonism of D1 receptors, delays the onset of copulation and reduces ejaculatory threshold, possibly by altering autonomic control of penile reflexes.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1989

Rpe cell migration into intact vitreous body.

Retinal pigment epithelial (RPE) cells were obtained from human cadaver eyes and grown to confluence in 16 mm wells. A sterile intact rabbit vitreous body was isolated and placed on the RPE monolayer. RPE cells with fibrocyte-like morphology appeared over the RPE monolayer within 4 to 6 days. These rapidly proliferating cells were observed to extend cellular processes and migrate into the vitreous body. Migration of the RPE cells progressed over 20 to 40 days, at which time bipolar RPE cells were found in multiple layers of the vitreous body. The contractile properties of the migrating RPE cells were evident as 24% of vitreous bodies contracted into a dense cellular gel. This study provides a model of migration of RPE cells in the vitreous and allows study of the interaction of RPE with the intact vitreous gel.

Adolescent↗
PubMed1988

Nuclear sclerosis after vitrectomy for idiopathic epiretinal membranes.

We performed a retrospective analysis of lens changes occurring after vitrectomy for idiopathic epiretinal membranes causing macular pucker on 75 consecutive phakic eyes. Thirty-five eyes (47%) had appearance or progression of nuclear sclerosis. There were no changes in anterior subcapsular cataracts and three eyes (4%) had minimal changes in posterior subcapsular cataracts. Based on univariate analysis, presence of preoperative nuclear sclerosis, length of follow-up period, and surgeon were found to be associated with the occurrence or progression of nuclear sclerosis. Differences between surgeons were largely accounted for by the difference in proportions with preoperative nuclear sclerosis, and differing lengths of follow-up. Kaplan-Meier life table analysis performed on 53 eyes with examination of fellow eyes and longer follow-up showed significantly more nuclear sclerosis in the operated on eye when compared to the fellow eye (log-rank test, P less than .0001).

Actuarial Analysis↗
PubMed1988

Vitrectomy for macular pucker. Use after treatment of retinal tears or retinal detachment.

We review our experience and present an analysis of 119 consecutive cases of macular pucker treated by vitrectomy and removal of the epiretinal tissue following treatment for acute retinal tears (16 eyes) or rhegmatogenous retinal detachment (103 eyes). Vision improved postoperatively in 104 (87%) of the 119 eyes. Final visual acuity of 20/60 or better was achieved in 38 (75%) of 51 cases in which the macula had not been detached previously and in 12 (24%) of 52 cases with prior macular detachment. Two preoperative factors were associated with a final visual acuity of 20/100 or better: (1) macula not involved by the original retinal detachment, and (2) thin epiretinal membrane.

Adolescent↗
PubMed1988

Apomorphine and haloperidol, but not domperidone, affect penile reflexes in rats.

Previous studies have shown that systemic administration of the dopamine agonist apomorphine produced a biphasic effect on erection in the freely moving rat, with lower doses facilitating, and high doses inhibiting, erection. However, those studies did not distinguish between erection per se and seminal emission. The present results demonstrate that apomorphine produces a similar biphasic effect on penile reflexes in the restrained, supine rat, while facilitating seminal emission in a monophasic fashion. Haloperidol, a centrally-acting dopamine antagonist, either blocked the effects produced by apomorphine administration, or had actions opposite to those of apomorphine. Domperidone, a dopamine antagonist that does not readily penetrate the blood-brain barrier, did not antagonize apomorphine's effects, and did not affect penile responses when administered alone. These results suggest that dopamine receptors in the central nervous system regulate genital responses, and that effects on penile reflexes and seminal emission can be experimentally dissociated.

Animals↗
PubMed1988

Prediction of the kinetics of disappearance of sulfur hexafluoride and perfluoropropane intraocular gas bubbles.

Intravitreal gases are useful in treating complicated retinal detachments by providing internal tamponade of retinal breaks. The geometry of the intraocular gas bubble and the kinetics of intraocular gas absorption determine the geometry and duration of internal tamponade of the retinal break. The authors derived a mathematical relationship based on a geometric model of the rabbit eye which allows calculation of the volume of an intraocular gas bubble from its observed meniscus height. When compared with actual measured bubble volumes, this technique was found to provide an accurate, noninvasive method for determining true intraocular gas volumes. Using this model, the absorption of nonexpansile concentrations of sulfur hexafluoride (SF6) and perfluoropropane (C3F8) were found to obey first-order kinetics. Both gases were found to have an intraocular half-life two to three times shorter in aphakic rabbit eyes after total vitrectomy than in phakic rabbit eyes with intact vitreous.

Animals↗
PubMed1988

Occult foreign body simulating a choroidal melanoma with extrascleral extension.

A 62-year-old man was noted on routine examination to have a dark lesion in the peripheral fundus of the right eye and a corresponding dark scleral mass. The lesion was initially suspected to be a choroidal melanoma with extrascleral extension. The patient denied having ocular trauma. Orbital x-rays and ultrasonography, however, demonstrated the lesion to be an occult transcleral metallic foreign body. An occult foreign body should be considered in the differential diagnosis of a small choroidal or ciliary body melanoma with extrascleral extension.

Choroid Neoplasms↗
PubMed1988

Vitrectomy for idiopathic epiretinal membranes causing macular pucker.

We used vitreous surgery to remove idiopathic epiretinal membranes from the macular area in 70 consecutive cases. The abnormal tissue was successfully removed in each case. Vision improved postoperatively in 61 eyes (87%), remained unchanged in six eyes (9%), and worsened in three eyes (4%). However, at the time of final examination vision was improved in only 47 eyes (67%), primarily because of the occurrence or progression of nuclear sclerosis, which occurred in 38 of 60 phakic eyes (63%). Four preoperative factors were associated with final visual acuity of 20/60 or better: (1) initial vision of 20/100 or better, (2) shorter preoperative duration of blurred vision, (3) thin epiretinal membrane, and (4) absence of traction retinal detachment.

Adult↗
PubMed1987

An analysis of the effect of intravitreal blood on visual acuity.

We investigated the effect of diffuse hemorrhage on Snellen visual acuity in a model of vitreous hemorrhage in phakic and aphakic eyes. Two cylindrical test chambers with optical paths of 17 mm and 23 mm were constructed to simulate the effect of vitreous hemorrhage in phakic and aphakic eyes. The visual acuity was measured in two subjects in a double-masked fashion for 17 dilutions of whole blood between 1/100 and 1/12,800. The visual acuity decreased approximately linearly between the 1/800 and 1/4,800 dilutions of blood. The visual acuity was 20/20 in all dilutions of blood higher than 1/4,800. The visual acuity was reduced to hand motions or worse with 12.5 microliter of blood in the 5-ml test chamber under all test conditions. The visual acuity was 20/20 in all tests with 1.04 microliter of blood in the test chamber. The visual acuity decreased from 20/20 to hand motions with only a twelve-fold change in concentration of blood in the test chamber.

Aphakia↗
PubMed1987

Results and prognostic factors in vitrectomy for diabetic vitreous hemorrhage.

The final visual acuities and prognostic factors predictive of these results were analyzed in 353 eyes that had pars plana vitrectomy for nonclearing diabetic vitreous hemorrhage. Eighty-one percent of the eyes had improved visual acuities on final examination. The percentage of eyes that achieved a visual acuity of 20/100 or better and the percentage that achieved 5/200 or better increased during the study period. Preoperative factors associated with a favorable visual prognosis included the following: preoperative visual acuity of 5/200 or better, absence of iris neovascularization, absence of neovascular glaucoma, clear lens or minimal cataract, and panretinal photocoagulation of at least one fourth of the fundus. Intraoperative factors associated with a favorable visual prognosis included retaining the crystalline lens and absence of an intraocular gas bubble.

Adolescent↗