Biomedical subjects

J T Handa

Publications and source records attributed to J T Handa.

17 recordsLinked to original sources

PubMed1999

Increase in the advanced glycation end product pentosidine in Bruch's membrane with age.

PURPOSE: To determine whether there is an age-related increase of pentosidine in human Bruch's membranes and to localize pentosidine and carboxymethyllysine (CML), two well-characterized, advanced glycation end products (AGEs) in aged human Bruch's membranes and choroid in vivo. METHODS: Human Bruch's membrane samples were isolated from the retinal pigment epithelium (RPE) and choroid and subjected to reversed-phase high-performance liquid chromatography to determine pentosidine content. A polyclonal anti-pentosidine antibody and a monoclonal antibody specific for carboxymethyllysine were used to localize AGEs in 20-month-old nondiabetic, 82-year-old nondiabetic, and 82-year-old diabetic globes. RESULTS: Human Bruch's membranes (n = 20) showed a linear age-dependent increase in pentosidine that reached approximately 0.17 millimoles pentosidine per mole hydroxyproline in late life (r = 0.896; P < 0.001). Immunohistochemical evaluation showed evidence of pentosidine in Bruch's membrane, choroidal extracellular matrix, and vessel walls in the 82-year-old nondiabetic and diabetic globes. A similar staining pattern was found with the anti-CML antibody. Basal laminar deposits and drusen stained with both antibodies in the elderly nondiabetic eye. In contrast, neither antibody stained the 20-month-old tissue. CONCLUSIONS: We provide biochemical and immunohistochemical evidence for the formation of pentosidine and CML structures in human Bruch's membrane and choroid with age. These changes could promote aging of the RPE-Bruch's membrane-choroid complex.

Adult↗

PubMed1999

Beta-galactosidase histochemistry and telomere loss in senescent retinal pigment epithelial cells.

PURPOSE: To investigate the relation of senescence-related beta-galactosidase activity and telomere shortening to replicative senescence in cultured human retinal pigment epithelial (RPE) cells. METHODS: A human RPE cell line was serially passaged until 80% of cells were nondividing in a 72-hour 5-bromo-2'-deoxyuridine (BrdU) labeling study. Early- and late-passage cells were double-stained for BrdU and senescence-related beta-galactosidase activity (pH 6). The average chromosomal telomere length at several population doublings was estimated by Southern blot analysis after double digestion of DNA with RsaI and HinfI and using a telomere-specific probe. RESULTS: BrdU-beta-galactosidase double-staining revealed an inverse correlation between the number of BrdU-labeled nuclei and beta-galactosidase-labeled cells as a function of population doubling level (PDL). At PDL 58, only 20% of all cells labeled for BrdU, whereas 57% stained for beta-galactosidase. The mean terminal restriction fragment length (TRF) was reduced from 10 kb in early (PDL 12) cultures to 4 kb in late (PDL 57) cultures. CONCLUSIONS: Senescence-related beta-galactosidase activity and mean TRF length may prove useful in studying the senescence of RPE cells in vitro. These techniques may be valuable in determining senescence of the retinal pigment epithelium in vivo, where senescent RPE cells could be involved in the development of age-related maculopathy and age-related macular degeneration.

Blotting, Southern↗

PubMed1998

The advanced glycation endproduct pentosidine induces the expression of PDGF-B in human retinal pigment epithelial cells.

Advanced glycation endproducts have been implicated in a number of diabetic and aging changes. Some of these effects occur in part through induction of cytokines such as platelet-derived growth factor (PDGF), which is expressed by the retinal pigment epithelium (RPE). In this study, cultures of RPE were evaluated for PDGF expression after treatment with pentosidine, a well characterized advanced glycation endproduct. Northern analysis provided evidence for the increased expression of a 3.7 kb PDGF-B transcript over unstimulated controls in the established ARPE-19 cell line. Western analysis demonstrated increased PDGF-BB protein in conditioned medium compared to controls of ARPE-19 cells. In addition, two different early passage cultures of RPE showed increased PDGF-BB protein after pentosidine treatment compared to unstimulated controls. The enhanced production of PDGF-BB could play a role in the maintenance of the RPE-Bruch's membrane complex and influence changes associated with diabetes and aging.

Anticoagulants↗

PubMed1998

Histologic localization of indocyanine green dye in aging primate and human ocular tissues with clinical angiographic correlation.

OBJECTIVE: This study aimed to histologically localize indocyanine green (ICG) dye in the geriatric primate and human eye and to correlate these findings with clinical ICG angiography. DESIGN: The study design was a clinicopathologic correlation. PARTICIPANTS: Six eyes of three geriatric monkeys (Maccaca mulatta) with macular drusen, 19 to 29 years of age, housed at the California Primate Research Center and an enucleated human eye from a 66-year-old patient with choroidal melanoma were examined. INTERVENTION: All six monkey eyes and the human eye underwent clinical ICG angiography. Five monkey eyes were enucleated at varying intervals after intravenous ICG dye injection for histologic examination. One monkey eye was removed without prior ICG injection as an age-matched control. The human eye was enucleated after intravenous injection of ICG dye. MAIN OUTCOME MEASURES: Infrared fluorescence microscopy of freeze-dried tissue sections was performed to detect ICG fluorescence. Histologic sections were stimulated with an 810-nm diode laser, and the fluorescence emitted was detected with a Hamamatsu infrared camera. The images were digitally recorded. The distribution of fluorescence on histologic examination was correlated with the fluorescence of the clinical ICG angiogram. RESULTS: Infrared fluorescence microscopy of monkey sections localized fluorescence within retinal and choroidal vessels early after injection of ICG dye. The ICG fluorescence was seen in the extravascular choroidal stroma within 10 minutes after injection. The stromal fluorescence persisted in sections obtained 50 minutes after injection of ICG. The retinal pigment epithelium (RPE)-Bruch's membrane complex was brightly fluorescent in the middle- and late-stage histologic sections. Drusen deposits were brightly fluorescent at all timepoints examined. Similar findings were observed in freeze-dried tissue sections of the human eye. The fluorescence detected on histologic sections correlated closely with the fluorescence of the clinical ICG angiograms for the same interval. CONCLUSIONS: The ICG dye does not remain solely within the choroidal intravascular space but extravasates into the choroidal stroma and accumulates within the RPE. Extravascular ICG binds to drusen material. These findings will enhance the interpretation of clinical ICG angiography.

Aged↗

PubMed1996

Transferrin-ricin A chain toxin limits the development of experimental proliferative vitreoretinopathy.

This study was designed to determine the safety and efficacy of transferrin-ricin A chain toxin (Tfr-rRA) at preventing retinal detachment in a rabbit model of proliferative vitreoretinopathy (PVR). The toxicity of intravitreal Tfr-rRA (1000-5000 ng) was determined by indirect ophthalmoscopy and electroretinography on days 1, 5, 8, 16, 26 and 48 post-injection, and by light and transmission electron microscopy conducted on eyes enucleated 48 days after drug exposure. PVR was created by injecting 25,000 homologous fibroblasts into the vitreous cavity of eyes which had previously undergone a gas compression vitrectomy. Eyes then received intravitreal Tfr-rRA (2000 ng) or vehicle. Animals were examined on days 1, 4, 7, 10, 14, 21 and 28 post-injection. Intravitreal injection of 1000 and 2000 ng Tfr-rRA did not show ophthalmoscopic or electroretinographic toxicity. Injection of 5000 ng Tfr-rRA showed mild retinal whitening, retinal arteriolar narrowing, and electroretinographic toxicity, but no morphologic damage, such as photoreceptor loss, nuclear layer vacuolation, or inflammatory cell infiltration, to the retina. Tfr-rRA (2000 ng) injected intravitreally 3 days after fibroblast injection prevented traction retinal detachment in 90% of eyes compared to 22% of sham treated eyes (P < 0.001). The data from this study suggest that transferrin-ricin A chain toxin (2000 ng) safely and effectively limits retinal detachment in experimental PVR.

Animals↗

PubMed1996

Hypoxia precedes the development of experimental preretinal neovascularization.

BACKGROUND: Although the mechanism of preretinal neovascular growth in the cell-injected rabbit eye model is not known, it has been proposed that the initial vasodilation and eventual development of neovascularization may be attributable to inflammatory mediators. However, an alternative explanation involving hypoxia has not been considered. The purpose of this study was to measure preretinal oxygen tension prior to the development of preretinal neovascularization in the cell-injected rabbit eye. METHODS: In the rabbit, intravitreous injections of 250,000 homologous dermal fibroblasts were performed on one eye; the fellow (control) eye was injected with vehicle. Preretinal oxygen tension over the myelin wing was measured using 19F-NMR spectroscopy of a 30-microliters droplet of perfluorocarbon previously injected into the preretinal vitreous. RESULTS: Compared to control eyes, fibroblast-injected eyes showed a 1.7-fold decrease in preretinal oxygen tension from the first time studied (1 day after cell injection) through the development of visible neovascularization. Hypoxia occurred without coexisting ophthalmoscopic evidence of vascular occlusion or, on days 1 and 3 after cell injection, retinal detachment. CONCLUSION: This result demonstrates for the first time that preretinal hypoxia precedes the development of preretinal neovascularization in the fibroblast-injected rabbit eye.

Animals↗

PubMed1996

Clearance of antitransferrin receptor immunotoxin from the rabbit eye.

PURPOSE: Antitransferrin receptor immunotoxin has potent antiproliferative effects on proliferating human ocular cells in vitro, and shows promise in the treatment of ocular proliferative diseases, such as proliferative vitreoretinopathy, bleb scarring after trabeculectomy, or corneal epithelial downgrowth syndrome. Before treating patients, the pharmacokinetics of immunotoxin must be known. The purpose of this study was to determine the clearance of antitransferrin receptor immunotoxin from the rabbit eye after ocular injection. METHODS: Immunotoxin (1,000 ng/0.1 ml PBS) was injected into the vitreous cavity of gas vitrectomized rabbit eyes. Immunotoxin in aqueous, vitreous, and plasma was measured by ELISA at various times after injection. Similar measurements were obtained after immunotoxin was injected into the anterior chamber or subconjunctival space of eyes which had not received vitrectomy. Cultured human retinal pigment epithelial cells were exposed to vitreous fluid obtained after intravitreal injection, and counted after four days, to determine the bioactivity of immunotoxin recovered from vitreous samples. RESULTS: Immunotoxin was cleared rapidly from the vitreous cavity over the first 24 hr (t1/2 = 8.0 hr), and thereafter was slow. Drug recovered from the vitreous cavity retained significant antiproliferative activity at 96 hr. Immunotoxin was cleared within 6 hr from the aqueous after anterior chamber injection, and was not present inside the eye after subconjunctival injection. The plasma did not contain immunotoxin after any of these injections. CONCLUSIONS: The favorable pharmacokinetics of antitransferrin receptor immunotoxin in the rabbit eye suggests that it could be useful in the treatment of ocular proliferative disorders.

Animals↗

PubMed1995

The role of vitrectomy in rhegmatogenous retinal detachment.

Several conditions, such as detachment from posterior breaks or detachment with significant media opacities, may warrant vitrectomy as the primary procedure. In cases in which the preoperative retinal view is clear and a posterior break is definitively excluded, vitrectomy does not appear to offer significant advantage over scleral buckling other than a theoretically improved ability to examine the retina microscopically with scleral depression. Performing a vitrectomy for an uncomplicated retinal detachment from a small peripheral break in which scleral buckling would be the usual procedure of choice remains controversial. Although it may avoid the complications of scleral buckling, vitrectomy does have its own potential complications. The status of the lens, cornea, and configuration of the retinal tears and detachment should carefully be considered before vitrectomy. Proper patient selection and appropriate education are important factors in a successful outcome. Finally, from an economic viewpoint, the likelihood of success with vitrectomy in one procedure compared with other less expensive procedures should be considered.

Humans↗

PubMed1994

Inhibition of proliferating lens epithelium with antitransferrin receptor immunotoxin.

We investigated the effect of an antitransferrin receptor immunotoxin (454A12-rRA) on proliferating human and baboon lens epithelium in vitro. Human and baboon lens epithelial cells grown in modified TC-199 medium at 35 degrees Celsius in 7% CO2 were seeded in 24 well plates at a density of 17,500 cells/ml to 40,000 cells/ml. The cells were exposed to various concentrations of 454A12-rRA for seven days. The sensitivity of proliferating human lens epithelium to 454A12-rRA was dependent on the dose, with a 60% to 70% reduction in cell counts at immunotoxin concentrations of 100 ng/ml and above. The immunotoxin had no significant effect on baboon lens epithelium in vitro, which suggests that it is specific for human tissue. By preventing the proliferation of human lens epithelial cells, immunotoxin 454A12-rRA may be useful in the management of posterior capsule opacification after planned extracapsular cataract surgery.

Animals↗

PubMed1994

Lightning maculopathy. A case report.

BACKGROUND: Lightning can cause a number of ocular complications. A case involving a patient who developed a cataract and reversible maculopathy in both eyes after being struck by lightning is reported. METHODS: The patient was evaluated for cataract and macular edema by ophthalmoscopic examination, fluorescein angiography, and potential acuity meter. RESULTS: Maculopathy developed that was characterized initially by a retinal cyst with surrounding edema. Later, the lesions evolved to simulate a full-thickness hole. These lesions subsequently resolved, and the patient's visual acuity improved to 20/20 in each eye after cataract extraction. CONCLUSION: Because the visual prognosis for lightning-induced maculopathy is potentially different than that for full-thickness macular holes, careful retinal examination is essential in the preoperative workup.

Adult↗

PubMed1994

Inhibition of cultured human RPE cell proliferation and lysyl hydroxylase activity by hydroxy derivatives of minoxidil.

PURPOSE: To examine the antiproliferative and lysyl hydroxylase suppressing effects of 3'-hydroxyminoxidil and 4'-hydroxyminoxidil, derivatives of minoxidil devoid of the antihypertensive effect, on human retinal pigment epithelial (RPE) cells in culture. METHODS: Subconfluent and confluent cultures of RPE cells, exposed to 0.01 to 5 mM 3' or 4'-hydroxyminoxidil for 15 minutes to 7 days, were examined for proliferation, viability, and morphologic changes. Lysyl hydroxylase activity in confluent cultures exposed to 1 mM 3'- or 4'-hydroxyminoxidil was determined by measuring the amount of 3H2O released from L-(4,5-3H)lysine-labeled unhydroxylated procollagen substrate after vacuum distillation. RESULTS: Both compounds inhibited the proliferation of subconfluent cultures of RPE cells in a dose-dependent fashion. The 50% effect occurred at 0.25 mM for 3'-hydroxyminoxidil and 0.5 mM for 4'-hydroxyminoxidil. The antiproliferative effect was detectable within 24 hours, required a minimum 1-hour exposure, and persisted even after the drug was removed from the culture medium. Cell viability experiments provided no evidence for toxicity. In contrast, the number of cells at confluent density was not affected. Both 3'-hydroxyminoxidil and 4'-hydroxyminoxidil suppressed lysyl hydroxylase activity by 72%. CONCLUSIONS: The structure of minoxidil can be altered to reduce the antihypertensive activity while preserving the antiproliferative and lysyl hydroxylase suppressing effects. The hydroxy derivatives of minoxidil may be useful in the treatment of proliferative vitreoretinopathy, a disease with unwanted proliferation of RPE cells.

Cell Division↗

PubMed1993

Monensin enhances the cytotoxic effect of antitransferrin receptor immunotoxin on cultured RPE cells.

The effect of monensin on the cytotoxic effect of antitransferrin receptor immunotoxin (IT) was determined on cultured, human retinal pigment epithelial (hRPE) cells. Human RPE cells were treated with 0.1-10,000 ng/ml IT with and without 0.01-0.1 microM monensin, a lysosomotropic reagent that can influence IT activity. Monensin (0.01 microM) shortened the onset of cell kill with IT (10,000 ng/ml) from 48 to 24 hours (p = 0.0016). Although 0.01 microM monensin alone was not cytotoxic to hRPE cells, a single 7-day treatment with monensin caused up to a 4.1-fold increase in antiproliferative potency of IT on proliferating hRPE cells (p < or = 0.0001). Enhancement was obtained with only a 1-hour exposure to 0.1 microM monensin (p = 0.0001). In contrast, IT (0.1-10,000 ng/ml) combined with monensin (0.01 microM) had minimal effect on density-arrested cells. IT with or without monensin did not inhibit proliferation of Rhesus monkey RPE cells. Our results indicate that monensin enhances the selective cytotoxic effect of IT on proliferating hRPE cells in culture.

Animals↗

PubMed1993

The antiproliferative effect of a transferrin-toxin on human retinal pigment epithelial cells and rabbit fibroblasts.

PURPOSE: To determine the effect of a rabbit transferrin conjugated to recombinant ricin A chain (Tfr-rRA) and the carboxylic ionophore monensin on proliferating and density-arrested human retinal pigment epithelial cells and rabbit dermal fibroblasts. METHODS: Cells were seeded on 24-well plates at 20,000 cells/cm2 and exposed to Tfr-rRA (0.1-10,000 ng/ml) with or without monensin (0.01 microM), and with or without human transferrin (65.7 mg/l) for 5 minutes to 7 days. Cells were studied morphologically and counted at 1, 2, 4, and 7 days. RESULTS: Tfr-rRA (10-10,000 ng/ml) killed proliferating human retinal pigment epithelial cells and rabbit dermal fibroblasts in a dose-dependent manner (p < or = 0.01) up to a maximum of 86% and 93%, respectively. In contrast, Tfr-rRA had minimal effect on density-arrested human retinal pigment epithelial cells and rabbit dermal fibroblasts. The cytotoxicity of Tfr-rRA was inhibited by the addition of human transferrin (65.7 mg/l), an effect that was partially overcome by longer treatment with Tfr-rRA. Monensin (0.01 microM) increased the cytotoxicity of Tfr-rRA by 4.8-fold over Tfr-rRA alone, shortened the onset of cell kill with Tfr-rRA from 48 to 24 hours (P = 0.04), and partially reversed the neutralizing effect of human transferrin. CONCLUSIONS: The results indicate that Tfr-rRA effectively inhibited the proliferation of human retinal pigment epithelial cells and rabbit dermal fibroblasts in vitro. The inhibitory effect could be modified by the addition of human transferrin or monensin. Thus, this ricin A chain conjugate may interrupt the proliferation of cells necessary in the pathogenesis of proliferative vitreoretinopathy.

Animals↗

PubMed1993

Minoxidil inhibits ocular cell proliferation and lysyl hydroxylase activity.

PURPOSE: To examine the antiproliferative and lysyl hydroxylase-suppressing effects of minoxidil on cultured proliferating and density-arrested human retinal pigment epithelial cells (hRPE) and Tenon's capsule fibroblasts (hTCF). METHODS: Proliferating and density-arrested hRPE and hTCF, exposed to minoxidil (0.1-5 mM) for 15 min to 7 days, were examined by proliferation assays, [3H]thymidine incorporation, trypan-blue exclusion, and phase-contrast microscopy. The lysyl hydroxylase-suppressing effects were examined in confluent hRPE exposed to minoxidil (0.01-1 mM) using L-[4,5-3H]-lysine-labeled procollagen substrate and measuring the amount of tritium released as 3H2O after vacuum distillation. RESULTS: Minoxidil (0.1-5 mM) inhibited the proliferation of subconfluent cultures of hRPE and hTCF in a dose-dependent manner with a half-maximal effect at 1.5 and 2.5 mM, respectively. The antiproliferative effect, detectable within 24 hr, occurred with a limited exposure period and persisted even after removal of minoxidil from the culture medium. In contrast, 1-5 mM minoxidil had minimal effect on density-arrested hRPE and hTCF. However, at doses above 3 mM, although minoxidil had no effect on the number of density-arrested hRPE, morphologic and viability experiments indicated signs of cytotoxicity. Minoxidil (0.1-1 mM) caused a maximum of 71% reduction in the activity of lysyl hydroxylase, an enzyme needed for stable cross-links in collagen. CONCLUSIONS: Minoxidil may be a useful drug for the treatment of conditions such as proliferative vitreoretinopathy and bleb scarring after trabeculectomy, disorders with unwanted cell proliferation and collagen production.

Cell Count↗

PubMed1992

Treatment with intravitreal steroid reduces blood-retinal barrier breakdown due to retinal photocoagulation.

The effect of corticosteroid treatment on blood-retinal barrier breakdown caused by argon-laser panretinal photocoagulation was evaluated in the rabbit eye. One day before photocoagulation, eyes were given either a sub-Tenon (20-mg) or intravitreal (2-mg) injection of triamcinolone acetonide. The severity of blood-retinal barrier breakdown was measured after photocoagulation using rapid sequential magnetic resonance imaging following intravenous administration of gadolinium diethylenetriaminepentaacetic acid. Leakage of gadolinium diethylenetriaminepentaacetic acid into the vitreous space was significantly lower in eyes that received intravitreal triamcinolone acetonide than in control eyes (P = .007); however, sub-Tenon triamcinolone acetonide produced no significant reduction in leakage (P = .65) compared with controls. Fluorescein angiography supported the magnetic resonance imaging findings. We conclude that retinal photocoagulation in the rabbit eye produces blood-retinal barrier breakdown that is partially amenable to corticosteroid treatment.

Animals↗

PubMed1990

Hemihang-back recession: description of the technique and review of the literature.

We describe a modification of the hang-back and loop techniques that we call the hemihang-back recession, in which the muscle is reattached to the sclera posterior to the original insertion with a single, absorbable suture. We recommend it for difficult strabismus cases, specifically when recessions of 7 mm or more are required.

Adult↗

PubMedDate not supplied

Perfluorocarbon temperature measurements using 19F NMR.

Measuring the T1 of the fluorine resonances of perfluorocarbons (PFC) is a unique method for monitoring oxygen tension in vivo. However, because T1 is also temperature sensitive, error in the pO2 determination due to animal-to-animal temperature variation may arise. Pathophysiologic conditions, such as ischemia, where temperature is not known a priori may also introduce error. Thus, measuring the PFC temperature is clearly desirable in order to correct for tissue temperature variations during the pO2 determination. Because the fluorine chemical shift of various fluorinated compounds has a significant temperature dependence, we evaluated the effect of temperature on the chemical shift of the fluorine resonances of perfluorotributylamine (FTBA). A linear relationship was found between chemical shift and temperature in vitro. In addition, the relative FTBA chemical shifts were essentially independent of pO2. Chemical shift temperature measurements in vivo, obtained from a 10 microL FTBA bubble in the preretinal vitreous space of the rabbit eye, were in good agreement (+/- 0.5 degrees C) with thermocouple measurements from the same location. Good agreement between the NMR determined temperature and core body temperature was also found. The implication of such temperature measurements for the ultimate accuracy of the pO2 determination based on PFC T1 measurements is discussed. To the best of our knowledge, this report describes the first absolute temperature measurement in vivo by NMR.

Animals↗