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Biomedical subjects

A Tawara

Publications and source records attributed to A Tawara.

At least 37 records · Page 2Linked to original sources
PubMed1998

[Effects of brovincamine fumarate on choroidal blood volume in rabbits].

We examined the effects of brovincamine fumarate, a Ca(2+)-channel blocker, on choroidal blood flow. We measured the choroidal blood volume continuously for 1 hour using laser Doppler flowmetry, as well as systemic blood pressure, heart rate, and intraocular pressure in six urethane-anesthetized rabbits after intravenous administration of 0.1 mg/kg or 0.5 mg/kg brovincamine. As a control, ten rabbits receiving no medication were used. All the data were recorded and analyzed using MacLab on a computer. In both the 0.1 mg/kg and 0.5 mg/kg brovincamine-injected groups, the choroidal blood volume decreased significantly after administration, but showed no significant difference from controls. Vascular resistance in the choroid showed a significant increase over the value before administration and over the control group. The heart rate decreased significantly compared to the value before injection and to the control group. The mean blood pressure in both dose groups and the intraocular pressure in the 0.5 mg/kg injected group were significantly higher than the controls. These results indicate that intravenous administration of 0.1 mg/kg or 0.5 mg/kg brovincamine does not cause an increase in the choroidal blood volume in urethane-anesthetized rabbits.

Animals↗
PubMed1996

Ultrastructural age-related changes on the posterior iris surface. A possible relationship to the pathogenesis of exfoliation.

OBJECTIVES: To verify the presence of age-related changes in the human iris and to determine whether such changes could be related to the pathogenesis of the exfoliation syndrome. DESIGN: Ultrastructural examination of the posterior surface of the normal iris in 9 enucleated eyes. PATIENTS OR OTHER PARTICIPANTS: Eyes of persons aged 1 day, 3 months, and 3, 9, 27, 52, 59, 59, and 65 years. MAIN OUTCOME MEASURE: The presence of aging changes in the iris. RESULTS: Aging changes included duplication of the basal lamina of posterior iris pigment epithelial cells, formation of atrophic invaginations in the posterior cell membranes containing interlacing basal lamina, formation (or deposition) of microfibrils 11 to 13 nm in diameter, with a banding periodicity of 12 to 16 nm, deposition of electron-dense material in relation to the basal lamina and/or microfibrils, and the presence of some fine granular material overlying the basal lamina. CONCLUSION: These changes have been consistently described before in association with exfoliation material, which suggests the possibility that exfoliation is an eventual aging process.

Adult↗
PubMed1996

Ciliary body band width as an indicator of goniodysgenesis.

PURPOSE: To evaluate the gonioscopic signs indicative of underdevelopment of the iridocorneal angle and thereby obtain a correct diagnosis of goniodysgenetic glaucoma. METHODS: We examined morphologically the iridocorneal angle of 28 enucleated human eyes, including those from premature infants as well as from older subjects. The ratio of the ciliary body band width to the width of the posterior limbus (the distance between the termination of Descemet's membrane and the iris root), termed the theoretic C/L ratio, was calculated by drawing on light micrographs. Data were compared for three age groups: premature infants, children, and subjects older than 9 years. We also examined clinically the appearance of the ciliary body band on gonioscopy in 135 eyes of 69 younger patients having primary glaucoma with open iridocorneal angles and in 94 eyes of 47 age-matched control subjects. RESULTS: The theoretic C/L ratio +/-SD was 1.4% +/- 2.7% in premature infants, 24.0% +/- 5.4% in children, and 36.7% +/- 8.0% in the older subjects. There was a statistically significant difference between each of the three groups (between premature infants and children, P < .001; between children and older subjects, P < .005; between premature infants and older subjects, P < .001). On gonioscopy, 105 of 135 glaucomatous eyes (77.8%) and 13 of 94 control eyes (13.8%) showed either an invisible or very narrow ciliary body band (P < .0001). CONCLUSION: The ciliary body band seen on gonioscopy provides an indicator of the development of the iridocorneal angle. An invisible or very narrow ciliary body band represents an underdevelopment of the angle.

Adolescent↗
PubMed1996

Ultrasound biomicroscopic analysis of transient shallow anterior chamber in Vogt-Koyanagi-Harada syndrome.

PURPOSE: To evaluate the mechanism of formation of the transient shallow anterior chamber in Vogt-Koyanagi-Harada syndrome. METHODS: Two patients with Vogt-Koyanagi-Harada syndrome with shallow anterior chambers were examined with an ultrasound biomicroscope. RESULTS: A ciliochoroidal detachment, which was not obvious on ophthalmoscopic examination, was clearly demonstrated in both patients by ultra-sound biomicroscopy. The detachment disappeared after systemic corticosteroid therapy. CONCLUSION: The shallowing of the anterior chamber in two patients with Vogt-Koyanagi-Harada syndrome was caused by suprachoroidal effusion secondary to inflammation of the uvea.

Anterior Chamber↗
PubMed1996

Neovascular tissue in the intertrabecular spaces in eyes with neovascular glaucoma.

AIMS/BACKGROUND: To investigate histological changes in the trabecular meshwork in eyes with neovascular glaucoma. METHODS: Light and electron microscopic studies were carried out on the trabecular meshwork of three enucleated eyes with neovascular glaucoma. The presence and distribution of factor VIII in the trabecular meshwork was assessed using the ABC method. RESULTS: Peripheral anterior synechiae covering the trabecular meshwork were detected in two eyes, which would explain the rise in intraocular pressure. In the third the angle was not completely closed by peripheral anterior synechiae. The spaces between the trabecular beams were lined by a single layer of vascular endothelium, and were filled with red blood cells in this patient. Factor VIII was positively stained in the endothelial cells, lining both these spaces and Schlemm's canal. A basal lamina and microfibrils were detected just beneath the newly formed vascular endothelial cells. CONCLUSION: The neovascular tissue found in the trabecular spaces might be one of the factors responsible for intraocular pressure elevation in eyes with neovascular glaucoma.

Adult↗
PubMed1996

Distribution and characterization of proteoglycans associated with exfoliation material.

PURPOSE: To examine the distribution of proteoglycans in the exfoliation materials in order to investigate the nature of the materials. METHODS: The anterior parts of two eyes with exfoliation syndrome were examined by electron microscopy after staining with cupromeronic blue (cmb). Some specimens were treated with enzymes and/or nitrous acid prior to staining. The effects of the enzymes were evaluated statistically by counting the density of the cmb-positive filaments in the exfoliation materials, using a computer. One eye with exfoliation syndrome stained with alcian blue was observed with light microscopy. RESULTS: Exfoliation materials were observed along the epithelial cells of the iris and ciliary body, and in the trabecular meshwork and zonules. In tissue specimens treated with cmb, electron-dense filaments were seen associated with the exfoliation materials. Microfibrils in the trabecular meshwork and iris, and zonular fibrils themselves were free of any filament staining, while the exfoliation materials located closely to the fibrils contained the electron-dense filaments. In the tissue specimens treated with chondroitinase AC, chondroitinase B, chondroitinase ABC or nitrous acid before cmb staining, the amount of the filament associated with exfoliation materials decreased in comparison to the controls. Digestion with keratinase did not demonstrate any significant changes in staining. A combination treatment with chondroitinase ABC and nitrous acid eliminated almost all filaments associated with the exfoliation materials. In the eye stained with alcian blue, the zonules that did not stain for the dye demonstrated an accumulation of exfoliation materials that stained strongly for alcian blue. CONCLUSIONS: Exfoliation materials contain chondroitin sulfate, dermatan sulfate, heparan sulfate proteoglycans. Depositions of proteoglycans on the microfibrils may be closely associated with the formation of exfoliation materials.

Aged↗
PubMed1996

Distribution of proteoglycans in the trabecular tissue of eyes with neovascular glaucoma.

We investigated histo-chemically the composition and distribution of proteoglycans in the trabecular tissue of eyes with neovascular glaucoma. Cupromeronic blue in combination with a series of enzyme digestions and nitrous acid treatment were used. The spaces between the trabecular beams were lined by a single layer of vascular endothelium and were filled with red blood cells. A basal lamina and microfibrils were detected just beneath the newly formed vascular endothelial cells. Chondroitin-sulfate- and dermatan-sulfate-type proteoglycans were present in association with collagen fibrils in the extracellular matrix. Heparan-sulfate-type proteoglycans were present in association with the basal lamina of both the vascular endothelial cells and the trabecular cells. It is unlikely that these abnormalities in the type or distribution of proteoglycans in the trabecular meshwork have a major role in the pathogenesis of glaucoma.

Adult↗
PubMed1995

Detection of proteoglycans in human posterior capsule opacification.

Using cuprolinic blue staining, we histochemically examined the ultrastructural localization of proteoglycans in the fibrous-type human posterior capsule opacification. This capsule opacification contained proteoglycans that showed positive staining with cuprolinic blue. Many cuprolinic-blue-positive filaments were present within the bundles of collagen fibrils, basal lamina-like material and basal lamina of proliferated lens epithelial cells. Pretreatment with enzymes and nitrous acid revealed that the collagen fibrils contained chondroitin sulfate and dermatan sulfate, whereas the basal lamina-like material and basal lamina of epithelial cells contained heparan sulfate. These results suggest that proteoglycans are one of the components in posterior capsule opacification.

Aged↗
PubMed1995

[Histopathological studies on the rds mouse retina--relationship between photoreceptor and pigment epithelial cells].

We used light and electron microscopy to examine detailed ultrastructural changes in the course of the development and degeneration of the rds mouse (rds/rds) retina with particular reference to the relationship between the photoreceptor and retinal pigment epithelial cells. During the first 6 postpartum days, the mutant retina showed the same developmental pattern as in normal mice. After that, however, rds mouse retinas failed to develop the photoreceptor outer segments. After 14 days, the photoreceptor inner segments and the cilia were all arranged parallel in the same direction in which the pigment epithelial cells extend their long microvilli. The inner segments and the cilia were very long and surrounded by the microvilli of the retinal pigment epithelial cells in the mutant retinas 21 days postpartum or latter. Some inner segments and cilia showed cytoplasmic degeneration in the part surrounded by the microvilli, while the other part appeared normal. There were pigment epithelial cells that contained fragments of the inner segments. The photoreceptor nucleus and inner segment were reduced in number after 21 days. These findings indicate that the pigment epithelial cells play a role in photoreceptor degeneration in rds mice.

Animals↗
PubMed1994

Distribution and characterization of sulfated proteoglycans in the trabecular tissue of goniodysgenetic glaucoma.

We evaluated histochemically the distribution of proteoglycans in the trabecular tissue of goniodysgenetic (developmental) glaucoma. Nine trabecular tissue specimens obtained at trabeculectomy from seven patients with goniodysgenetic glaucoma were stained with either cuprolinic blue or cupromeronic blue in combination with a series of enzyme and nitrous acid treatments. Within the extracellular matrix of the trabecular meshwork, many cupromeronic blue- or cuprolinic blue-positive filaments were observed in association with collagen fibrils, basal lamina, and basal lamina-like material. The extracellular matrices of elastin-like fibers, fine fibrillar materials, and fine granular materials were free from any reaction products. The enzyme and nitrous acid treatments disclosed that the reaction products associated with collagen fibrils represented both chondroitin sulfate and dermatan sulfate types, while those with basal lamina and basal lamina-like material represented heparan sulfate-type proteoglycans. Extensive accumulations of basal lamina-like material contained a great deal of heparan sulfate-type proteoglycans in the thick subcanalicular tissue of goniodysgenetic glaucoma. These results indicate that the class and distribution of proteoglycans in the goniodsygenetic trabecular tissues are virtually the same as that in the normal tissues. However, the large accumulation of basal lamina-like material with heparan sulfate-type proteoglycans can be one of the causes of the intraocular pressure increase in goniodysgenetic glaucoma.

Adolescent↗
PubMed1994

Anterior chamber angle vascularization in Sturge-Weber syndrome. Report of a case.

The case of a 20-year-old woman with a left-sided facial hemangioma and a homolateral glaucoma is reported, complete with the histology of a trabeculectomy specimen. Her left eye had an episcleral hemangioma and goniodysgenetic features in the anterior chamber angle, while the intraocular pressure was measured to be 45 mmHg. The left optic disc showed a large cupping and the left visual field was constricted. The right eye had no glaucomatous changes. Histological examination of the trabeculectomy specimen by both light and electron microscopy showed multiple congenital anomalies. There was a cluster of blood vessels in the trabecular meshwork. Abnormal accumulations of fine granular extracellular matrixes were observed in both the juxtacanalicular connective tissue and around the vascular structures. The lumen of Schlemm's canal was subdivided into three or four parts with few giant vacuole structures. The endothelial cells lining the inner wall of Schlemm's canal contained a well-formed basal lamina with many villi projecting into the lumen. These findings suggest that the multiple anomalies observed in the trabecular tissue may contribute to the manifestation of glaucoma in Sturge-Weber syndrome.

Adult↗
PubMed1993

Anterior capsule opacification in monkey eyes with posterior chamber intraocular lenses.

OBJECTIVE: To examine the morphologic features of anterior capsule opacifications in pseudophakic monkey eyes. METHODS: Extracapsular lens extraction with implantation of posterior chamber intraocular lenses in six monkey eyes. Eyes were enucleated 2, 4, and 12 months after implantation and then studied with light and electron microscopy. Distribution of proteoglycans was also examined with cuprolinic blue staining. RESULTS: Anterior capsule opacifications were composed of proliferated cellular and extracellular matrix components situated between the anterior capsule and the optics of the intraocular lens. The morphologic features of the proliferated cells were consistent with epithelial cells, and these cells probably represented lens epithelial cells. The extracellular matrix, which consisted of collagen fibrils, basal lamina-like material, and microfibrils, was most prominent in the specimens obtained 12 months after lens implantation. The extracellular matrix contained proteoglycans that showed positive staining with cuprolinic blue. CONCLUSIONS: Anterior capsule opacifications consisted of proliferated lens epithelial cells and aberrant extracellular matrix.

Animals↗
PubMed1992

Proteoglycans in the mouse interphotoreceptor matrix. V. Distribution at the apical surface of the pigment epithelium before and after retinal separation.

The distribution of chondroitin sulfate proteoglycans in the mouse interphotoreceptor matrix (IPM) proximal to the retinal pigment epithelium (RPE) was evaluated with EM histochemical techniques using Cupromeronic Blue (CmB) before and after retinal separation. Densely packed, sheet-like processes surrounding vesicle-like compartments containing CmB staining were normal constituents of the IPM at the apical surface of the RPE. Most of the vesicle-like compartments, which appeared to be isolated from the IPM in single section profiles, were found to be continuous with the IPM when three-dimensional reconstructions of serial thin sections were evaluated. Analyses of stereo image pairs of semithin sections visualized by electron spectroscopic imaging (ESI) also demonstrated that the CmB stained proteoglycans in the lumen of these pseudovesicles were in continuity with the CmB stained components present in the IPM. Moreover, ESI demonstrated that the CmB stained profiles formed an elaborate interconnecting network extending from the apical border of the RPE to the level of the outer limiting membrane of the retina. After removal of the retina, rinsing of the RPE with Ringer's solution prior to fixation eliminated proteoglycan staining near the base of the apical processes, whereas staining near the tips of these processes remained. The CmB stained filaments remaining after rinsing were thicker and shorter, and made fewer interconnections than those in the non-separated preparations. These results suggest that two types of chondroitin sulfate proteoglycans are present in the IPM which differ in distribution and in the degree of aqueous solubility. Additionally, a closely associated retina appears to be required for maintenance of the normal structure of proteoglycans associated with the RPE surface. The elaborate topography at the RPE apical surface may play a role in the delivery and/or recovery of components of the IPM.

Animals↗
PubMed1992

Goniodysgenesis of the eye with arthrogryposis multiplex congenita.

We report an autopsy case of 4-day-old male infant with arthrogryposis multiplex congenita studied by histological methods in respect to the ocular tissues. The eye examined was normal in size, and the retina, optic nerve, choroid, sclera and extracocular muscle showed no remarkable histological changes. However, the cornea was thickened, and the iris, trabecular tissue and ciliary body showed maldevelopmental changes, which were all compatible with goniodysgenesis. The clinical data of this case did not demonstrate any signs of congenital glaucoma, but the present study indicates that an infant with arthrogryposis multiplex congenita has a potential for infantile glaucoma with goniodysgenesis.

Abnormalities, Multiple↗
PubMed1991

Proteoglycans in the mouse interphotoreceptor matrix. IV. Retinal synthesis of chondroitin sulfate proteoglycan.

To determine whether the mouse retina contributes chondroitin sulfate proteoglycan (CS-PG) to the interphotoreceptor matrix (IPM), 35SO4(2-) was used as a tracer for newly synthesized proteoglycan by retinas maintained in vitro in the absence of pigment epithelium. Following incubation with the tracer for 3 hr, the 35S-labeled proteoglycans present in the incubation medium and associated with isolated photoreceptor outer segments were analyzed separately. Proteoglycan was extracted with 4 M guanidine, and then separated on a G-25 column followed by DEAE ion exchange chromatography in the presence of 8 M urea. The proteoglycan fraction was eluted with a linear NaCl gradient of 0.15-1.0 M. Eluted 35S-labeled macromolecules were susceptible to chondroitinase AC and ABC degradation, indicating that virtually all the 35S-labeled proteoglycan synthesized by the mouse retina and secreted into the incubation media is of the chondroitin sulfate type. In parallel autoradiographic analysis of retinas following 35SO4(2-) incubation, silver grains were present over all retinal compartments, with 41-48% associated with the photoreceptor layer. Quantitative autoradiography of retinas following chondroitinase AC digestion of fixed retinas revealed significant (P less than 0.025) reduction in silver grains associated with the photoreceptor outer segment layer as compared to controls. These combined biochemical and autoradiographic studies indicate that the retina, possibly the photoreceptors, synthesize at least a portion of the CS-PG present in the IPM of the mouse.

Animals↗
PubMed1990

Proteoglycans in the mouse interphotoreceptor matrix. III. Changes during photoreceptor development and degeneration in the rds mutant.

The distribution of sulfated proteoglycans in the interphotoreceptor matrix (IPM) was examined during development and degeneration of photoreceptors in the rds mouse with electron microscopy after staining with the cationic dye Cupromeronic Blue (CmB). Three distinct CmB-positive filaments types were observed: type A (45-55 nm long and around 5 nm in diameter), type B (up to 0.5 micron long and 5-10 nm in diameter), and type C filaments (up to 1 micron long and 15-25 nm in diameter. During early postnatal development, before degenerative changes occur in photoreceptors, CmB-positive filaments were virtually identical in morphology and pattern of development as those recently reported for the normal mouse IPM (Tawara, Varner and Hollyfield, 1989, Exp. Eye Res. 48, 815-39). From 10 days to 1 year of age, during the period of progressive degeneration and loss of photoreceptor cells, numerous type B and type C filaments were present in the IPM. Type B filaments were distributed throughout the IPM, whereas type C were predominantly located around the apical termination of photoreceptor inner segments and between the pigment epithelial microvilli. Type A filaments were located principally in the apical cytoplasm of the pigment epithelial cells and in the proximal IPM. In the 20-month-old rds mouse, a time when virtually no photoreceptor cells remain, only minimal CmB staining was evident at the interface between the pigment epithelium and retina. Pretreatment with chondroitinase AC eliminated most CmB-positive filaments from the 18-day-old and 20-month-old mouse IPM. These findings suggest that there are no major differences in structural type or early postnatal development of chondroitin sulfate-type proteoglycans in the IPM between rds and normal mice. Any differences in distribution of chondroitin sulfate-type proteoglycans between rds and normal mice can be accounted for by the absence of photoreceptor outer segments and progressive loss of photoreceptor cells in this mutant. The disappearance of these IPM proteoglycans following photoreceptor degeneration suggests that photoreceptors may be critically involved in the maintenance of these matrix components.

Animals↗
PubMed1990

[A case of Rubinstein-Taybi syndrome suspected with goniodysgenetic glaucoma].

We reported a case of Rubinstein-Taybi syndrome suspected in association with goniodysgenetic glaucoma, and studied using light and electron microscopy the anterior chamber angle tissues obtained surgically by trabeculectomy. The patient was 31-year old male, who had a systemic appearance of Rubinstein-Taybi syndrome with dwarfism, mental retardation, antimongoloid slant, flat-broad based thumbs, low set ears, high arched plate except for whorl of dermatographism. In addition to these malformations, goniodysgenetic glaucoma was also present which is characterized by underdevelopment of the angle recess and invisible ciliary body band in gonioscopic examination. The histopathological studies of the specimens revealed the presence of a compact tissue filled with a large amount of collagen fibers with few cells in the juxta-canalicular tissue of Schlemm's canal. There were 3 to 4 layers of trabecular sheets of corneoscleral meshwork at the anterior chamber side of the compact tissue. We conclude that the presence of the compact tissue under Schlemm's canal represents goniodysgenesis, underdevelopment of the trabecular meshwork, which is the primary cause of the glaucoma in this case.

Adult↗