Biomedical subjects

S Sawaguchi

Publications and source records attributed to S Sawaguchi.

At least 37 records · Page 2Linked to original sources

PubMed1997

Up-regulation of glial fibrillary acidic protein in the retina of primate eyes with experimental glaucoma.

OBJECTIVE: To identify molecular mechanisms of retinal responses to intraocular pressure elevation in primate experimental glaucoma. METHODS: An experimental glaucoma model was created by repeated laser trabeculophotocoagulation. After the preparation of complementary DNAs from extracted total RNAs in the retinas, polymerase chain reaction (PCR) experiments were performed for the following screening target genes: beta-tubulin beta 2 and beta 5 and glial fibrillary acidic protein (GFAP). To investigate the amplified sequences derived from the PCR experiments, sequencing, subcloning, and Southern blot analysis of PCR products were performed. In addition, an immunohistochemical analysis was performed in an attempt to show the distribution of the target gene products in the retinas. RESULTS: A series of PCR experiments suggested up-regulation of gene expression for GFAP but not for beta-tubulins. Sequencing of the PCR products and results of the Southern blot analysis showed that the amplified sequences were derived mainly from the target gene, GFAP, and that increased expression of GFAP was found despite the severity of glaucoma. Immunohistochemical studies also demonstrated increased expression of GFAP proteins in Müller cells and astrocytes in the retinas of primate eyes with experimental glaucoma. CONCLUSIONS: Our study showed up-regulation of GFAP at gene and protein levels, which suggests that glial components in the retina may contribute to the pathologic processes induced by elevated intraocular pressure.

Animals↗

PubMed1997

Effects of mitomycin C on the expression of proliferating cell nuclear antigen after filtering surgery in rabbits.

BACKGROUND: The aim of the study was to evaluate the effects of mitomycin C on the cell replication activity in wound healing following experimental filtration surgery. METHODS: Trabeculectomy with or without application of mitomycin C was performed on albino rabbit eyes. At 1, 4, 7, 14, and 28 days after surgery, the expression of proliferating cell nuclear antigen, a marker of cell proliferation, in the filtering site was examined immunohistochemically using a streptavidin-biotin complex method. RESULTS: In control eyes that underwent trabeculectomy but did not receive mitomycin C, the number of immunoreactive cells increased 4-7 days after operation and decreased markedly at around 14 days. The filtering site was obstructed histologically at 4-7 days after operation. In the mitomycin C-treated eyes, immunoreactive cells appeared 4 days after surgery but disappeared by 7 days at the surgical site. The number of immunoreactive cells in the treated eyes was much lower than that in control eyes. CONCLUSION: The cell replication activity was markedly inhibited by administration of mitomycin C. The filtering site remained open for 28 days after surgery, whereas it was completely obstructed within 7 days in control eyes. Immunocytochemistry for proliferating cell nuclear antigen, as used in this study, is a simple and reliable method for detection of cell replication activity.

Animals↗

PubMed1997

Measurement of thickness of retinal nerve fiber layer by scanning laser polarimetry and high-pass resolution perimetry in patients with primary open-angle or normal-tension glaucoma.

PURPOSE: To evaluate the correlation between neural capacity, determined by high-pass resolution perimetry, and thickness of the retinal nerve fiber layer, evaluated by scanning laser polarimetry, in patients with primary open-angle glaucoma or normal-tension glaucoma. METHODS: Thickness of the peripapillary retinal nerve fiber layer was measured by scanning laser polarimetry in 19 eyes of 19 patients with primary open-angle glaucoma and in 23 eyes of 23 patients with normal-tension glaucoma. There were no significant differences between the two groups in mean age, sex ratio, or mean neural capacity. RESULTS: Neural capacity was significantly correlated with thickness of the retinal nerve fiber layer in all 42 eyes (r = 0.31, P = 0.0429). Neural capacity was significantly correlated with thickness of the retinal nerve fiber layer in the eyes of patients with primary open-angle glaucoma (r = 0.60, P = 0.0061), but not in the eyes of patients with normal-tension glaucoma (r = 0.04; P = 0.8522). CONCLUSION: The degree of correlation between neural capacity determined by high-pass resolution perimetry and thickness of the retinal nerve fiber layer measured by scanning laser polarimetry appeared to differ in patients with primary open-angle glaucoma vs those with normal-tension glaucoma.

Female↗

PubMed1997

Atomic force microscopic studies of isolated collagen fibrils of the bovine cornea and sclera.

Isolated collagen fibrils from the bovine cornea and sclera were investigated by atomic force microscopy (AFM) in a non-contact mode. AFM imaging visualized the surface topography of both corneal and scleral collagen fibrils with quantitative information on their height and width. The corneal collagen fibrils had a height of 15.6 +/- 1.5 nm and a D-periodicity of 63.9 +/- 0.5 nm. On the other hand, the height and D-periodicity of scleral collagen fibrils were 74.2 +/- 55.7 nm and 65.4 +/- 0.7 nm, respectively. A periodic banding pattern of grooves and ridges was found in individual fibrils, although the groove depth was 2.81 +/- 0.29 nm in the cornea and 5.47 +/- 0.66 nm in the sclera. When collagen fibrils were treated with acetic acid, they swelled and untwisted into subfibrils. The AFM is useful to analyze surface morphology of collagen fibrils and their subfibrils at high resolution with quantitative information.

Acetic Acid↗

PubMed1997

[Distribution of cell adhesion glycoproteins in the human retrobulbar optic nerve].

We examined the immunohistochemical distribution of six types of cell adhesion glycoproteins in the human retrobulbar optic nerve. The pial septa had laminin and entactin on the surface at the border with the optic nerve fibers, and fibronectin and vitronectin were distributed in the stroma of the septa. Some tenastin was also detectable both on the surface and in the stroma of the septa. Thrombospondin was associated with capillaries within the stroma. The surface of the arachnoid membrane, the pia mater, and the dura mater was covered by laminin and entactin. Diffuse staining with antifibronectin antibody was seen in all these meningeal tissues, but vitronectin showed a fine fibrillar appearance in these tissues. No significant staining could be found for tenastin. Thrombospondin showed only faint staining on the capillaries of the pia mater and the dura mater. These findings can provide clues for the discussion of how the extracellular matrix works and what roles it plays in disorders involving the retrobulbar optic nerve, such as optic neuritis and glaucoma.

Cell Adhesion↗

PubMed1997

[Expression of proteinase inhibitors in the human trabecular meshwork].

We examined the distribution and expression of three proteinase inhibitors, alpha 1-proteinase inhibitor (alpha 1-PI), alpha 1-antichymotrypsin (alpha 1-ACT), and alpha 2-macroglobulin (alpha 2-M) in the human trabecular meshwork. Immunohistochemistry, in situ hybridization, and reverse transcription-polymerase chain reaction (RT-PCR) were used. By immunostaining, all three inhibitors were identified in the human trabecular meshwork with enhanced staining in the uveal meshwork. In situ hybridization showed mild but positive accumulation of the silver grains on the trabecular meshwork cells, which indicates mRNA expression. Specific distribution or cell selectivity were not detectable probably due to weak expression of these inhibitors in this tissue. Instead mRNAs for alpha 1-PI, alpha 1-ACT, and alpha 2-M as well as antithrombin III, plasminogen activator inhibitor-1 could be identified by RT-PCR using trabecular meshwork culture cells. In this study, we concluded that some proteinase inhibitors were distributed in the human trabecular meshwork as well as in the cornea and the ciliary body. At least part of these were probably produced by the trabecular meshwork cells. The balance between proteinases and proteinase inhibitors might play an important role even in the human trabecular meshwork to maintain the outflow route. The alterations in the primary or secondary glaucomatous eyes are curious.

Adolescent↗

PubMed1997

[Posterior iris bowing after accommodation--elucidation of the etiology of pigment dispersion syndrome].

Recent advancements in imaging the anterior segment structures using the ultrasound biomicro scope (UBM) have proven the involvement of posterior iris bowing due to reverse pupillary block as the cause of pigment dispersion syndrome. In this report, we examined whether the posterior iris bowing occurs even in normal eyes following accommodation, and whether the degree of iris concavity tends to be greater in myopic eyes than in emmetropic eyes. The subjects were normal eyes with sufficient accommodation power, i.e. 5 myopic eyes with less than-5 diopter reflection, 5 emmetropic eyes within +/- 1 dioptor reflection, respectively. We obtained UBM images of the iris at 4 portions before and after accommodation, and measured the degree of posterior iris bowing. We found that almost all data shift posteriorly after accommodation, and that the iris concavity is more distinct in myopic eyes than in emmetropic eyes both before and after accommodation (before: p = 0.0004, after: p < 0.0001). From these results, we confirmed that iris concavity after accommodation occurs in normal eyes but not enough for iridozonular contact, and that pigment dispersion syndrome results from augmented iris concavity owing to pre-existing factors such as iris flexibility, myopia, and sufficient accommodation power.

Accommodation, Ocular↗

PubMed1997

[Plateau iris configuration as a risk factor for malignant glaucoma].

To provide evidence for diagnosing malignant glaucoma, as well as to elucidate the pathogenetic mechanism of the disease, ultrasound biomicroscopy (UBM) is a useful tool. We examined the anterior segments of three patients with post-operative malignant glaucoma with UBM regarding the state before operation, the state of the opposite eye, and the state after the release of the cilio-lenticular block. Case 1 was a 76-year-old female who was diagnosed as having chronic angle-closure glaucoma (CACG) and was treated by trabeculectomy, phacoemulsification, aspiration (PEA), and simultaneous intraocular lens (IOL) implantation. Case 2 was a 22-year-old male diagnosed as having CACG secondary to plateau iris syndrome and was treated by trabeculectomy. Case 3 was a 73-year-old female diagnosed as having normal-tension glaucoma with narrow angle and was treated by PEA and IOL implantation. Slit-like anterior chamber angle and anteriorly positioned ciliary body were observed in all 3 cases, which were identical to those Pavlin reported in 8 cases with plateau iris syndrome. UBM seems to be an important pre-operative examination to evaluate the risk of malignant glaucoma and to consider which surgical procedure and post-operative management is proper. The pre-operative configuration of the ciliary body may be associated with the onset of malignant glaucoma in some patients with CACG or narrow angle.

Adult↗

PubMed1996

[Slow axonal transport in primate experimental glaucoma].

Axonal transport abnormality has been reported to be deeply related to glaucomatous optic nerve injury. These reports mainly investigate the axonal transport blockage using the model of acute elevation of intraocular pressure in normal primates. We studied such axonal transport abnormality especially of slow flow in laser-induced glaucomatous monkey eyes by tissue autoradiography. Abnormal silver grain accumulation suggesting axonal transport damage was seen in the areas of distorted lamina cribrosa in glaucomatous eyes. Accumulation of grains was also seen in the retro-laminar optic nerve in some areas. Normal control eyes showed almost homogenous grain distribution in the pre-lamina, lamina and post-lamina areas. Areas of slightly elevated, accumulation of grains were seen around the lamina cribrosa and disc margin suggesting physiological blockage of axonal transport.

Animals↗

PubMed1996

[Proteoglycan molecules in scleral tissue of enlarged eyeball].

We studied scleral specimens from experimentally induced enlarged eyeball with axial elongation by the transmission electron microscopy following cationic dye (cuplonic blue) staining. The animal model was prepared by the injection of alpha-chymotrypsin into the posterior chamber of young albino rabbits. Cuprolinic blue staining was applied to scleral specimens obtained from equatorial lesion and portions of the scleral tissues were subjected to enzyme digestion by chondroitinase ABC, AC and B before cuprolinic blue staining. In control eyes, dermatan and chondroitin type sulfated proteoglycan filaments were identified. Large, electron dense, and abnormal by shaped proteoglycan filaments were seen in the transmission electron microscopy. Such abnormal proteoglycan filaments were susceptible to enzyme chondroitinase ABC and AC digestion but resistant to chondroitinase B, suggesting that they are chondroitin sulfate dominant proteoglycans. Our morphological data corroborated a previous biochemical report of abnormally induced proteoglycan molecules in sclera with enlarged, axially elongated eyes.

Animals↗

PubMed1995

[Matrix metalloproteinase in the cynomolugus monkey optic nerve heads].

Gelationolytic and caseinolytic activity of matrix metalloproteinase in normal cynomolugus monkey optic nerve heads was investigated. Optic nerve heads of three eyes were incubated in the media for 20 hours. Each media was applied to the gelatin or casein containing gels, and zymography was performed. Major bands of 94 kDa and 62 kDa gelatinase activities were demonstrated in all three eyes. In one eye gelatinolytic activity of the 58 kDa band was also demonstrated. Caseinase activity was not detected in any of the three optic nerve heads.

Animals↗

PubMed1995

[Changes of expression in matrix metalloproteinase and its inhibitor level in the sclera from axially elongated eyes].

We studied the gelatinolytic activity, caseinolytic activity and the level of tissue inhibitor of metalloproteinase-1 (TIMP-1) in the sclera from experimentally induced axially elongated eyes. The animal models were made by the injection of 250U alpha-chymotrypsin into the posterior chamber of young albino rabbits. Animals were killed with overdoses of intravenous pentobarbital and eyes were enucleated gently. Sclera from the equatorial area was then subjected to organ culture. The enzyme activity in the media was investigated by zymography using gelatin- or casein-containing gels together with an image analyzer system. TIMP-1 levels in each medium were measured by enzyme immunoassay (EIA). All samples showed three major bands of gelatinolytic activity at molecular weights of 87, 61, and 57 kDa. Gelatinolytic activity of 87 kDa increased 1.1 to 2.9 times compared with control sclera. All of the caseinolytic activity (87, 82, 52, and 50 kDa) was also elevated 1.8 to 6.6 times in samples from experimental eyes. TIMP-1 levels were mildly increased (up to 1.41 times) in the experimental eyes. These data suggest that degradation processes might be accelerated in the sclera from experimentally induced elongated eyes.

Animals↗

PubMed1995

[Collagen synthetic activity following filtration surgery in rabbits].

We evaluated collagen synthetic activity, which plays an important role in wound healing, following experimental filtration surgery in rabbits. Collagen synthetic activity was measured by immunohistochemistry for prolyl 4-hydroxylase beta-subunit and type I procollagen. Trabeculectomy was performed on albino rabbit eyes, with the filtering site harvested on postoperative days 1, 4, 7, 14, and 28. Samples were fixed with 10% buffered formalin for 12 hours and prepared for paraffin section, and each antigen was detected in filtering site tissue using avidin-biotinylated peroxidase complex. Immunoreaction of prolyl 4-hydroxylase beta-subunit or type I procollagen increased from day 4 to 14 and markedly decreased at day 28. These findings show that prolyl 4-hydroxylase and type I procollagen are markedly produced almost simultaneously, and collagen synthetic activity following filtration surgery continues for over 14 days in the process of wound healing.

Animals↗

PubMed1995

[Ultrastructural changes in the lamina cribrosa in experimental monkey glaucoma].

We examined the ultrastructural changes in the lamina cribrosa in monkeys with experimental chronic glaucoma. In normal monkey eyes, the extracellular matrix consists of tightly packed collagen fibers, elastic fibers and less ground substance in the beams, and basement membranes associated with vascular cells and astrocytes in the lamina cribrosa. In the experimental glaucomatous eyes there was a marked destruction of collagenous bundles. The empty spaces were expanded and filled with fine fibrillar materials. There were normal by appearing parts and clearly destroyed parts mixed in the same region. Elastic fibers looked isolated from the collagenous bundles around them. Basement membranes were generally thick, multi-laminated, and bent. In addition, basement membrane-like materials, separated from the cells, were often seen in the laminar beams. The lamina cribrosa in experimental chronic glaucoma showed evidence of both destruction and healing or remodeling. These changes might have a influence to the worse for the tissue characterization of the lamina cribrosa, such as resistence to intraocular pressure changes. In conclusion, this may be a factor related with the progression of glaucomatous optic nerve damage.

Animals↗

PubMed1994

Sulfated proteoglycans in the lamina cribrosa of normal monkey eyes and monkey eyes with laser-induced glaucoma.

The distribution of the sulfated proteoglycans in the lamina cribrosa of normal monkey eyes and monkey eyes with laser-induced glaucoma were analysed by electron microscopy after cuprolinic blue dye binding. Three types of cuprolinic blue-positive filaments, CB-1, CB-2 and CB-3, were identified in the laminar beams of normal monkey eyes. CB-1 and CB-2 were both small filaments representing chondroitin and dermatan sulfate proteoglycan copolymers. The former lined up perpendicularly to the long axis of collagen fibrils, whereas the latter ran axially parallel to collagen fibrils. The large CB-3 filaments, representing chondrotin sulfate proteoglycans, were located around collagen bundles or in loose spaces within the beams. In addition, small CB-4 filaments or punctate structures representing heparan sulfate proteoglycans were found aligned on the basal laminae of blood vessels and glial cells. In the glaucomatous eyes, accumulation and enlargement of collagen-associated proteoglycan filaments were seen, accompanied by the destruction of collagenous beams. Accumulation of chondroitin sulfate proteoglycans was most evident. Prominent filamentous heparan sulfate/heparin proteoglycans were also noted in thickened astrocytic and vascular basal laminae. These may be alterations secondary to the destruction of collagen bundles. They may also represent cellular responses related to intraocular pressure elevation.

Animals↗

PubMed1994

The collagen fibrillar network in the human pial septa.

The three-dimensional organization of the collagen fibrils in the human pial septa was studied by transmission electron microscopy and by scanning electron microscopy after cell maceration with sodium hydroxide. The collagen fibrils along the nerve fibers were loosely distributed thin filaments with a diameter ranging from 25 to 40 nm (mean, 32 +/- 6 nm). Most fibrils were oriented perpendicularly to the long axis of the nerve fiber. In the deeper stroma of the pial septa, collagen fibrils were well packed and the diameter was 40 +/- 6 nm (range, 35 to 50 nm). The scanning electron microscopic study demonstrated a smooth, fabric-like structure formed by wavy and loosely interwoven thin collagen fibrils. Under high magnification, multiple collagenous sheets were observed in the pial septa by scanning electron microscopy. In addition to the structure of loosely arranged thin fibrils on the surface layer adjacent to the nerve fibers, two distinct patterns of collagen fibril network were demonstrated in the deeper stroma. One exhibited fibrils with random distribution, and the other showed well-packed, undirectionally oriented collagen. Small openings corresponding to elastic tissues were also observed. This collagen architecture may contribute to the flexibility and tensile strength of the pial septa required in the intraorbital portion of the optic nerve.

Adult↗

PubMed1994

Alpha 2-macroglobulin levels in normal human and keratoconus corneas.

PURPOSE: To compare the levels of alpha 2-macroglobulin, one of the major proteinase inhibitors, in corneas with keratoconus to those in normal human corneas and corneas with other diseases. METHODS: An immunoperoxidase technique was used to visualize the presence of alpha 2-macroglobulin in the corneas. Western blot analysis was performed, and the levels of this inhibitor in extracts of keratoconus and normal human corneas were subsequently analyzed by a dot blot assay. RESULTS: alpha 2-Macroglobulin was demonstrated immunohistochemically in the epithelium, stroma, and endothelium of all corneal sections. Compared with normal human control specimens, the staining intensity in the epithelium of keratoconus corneas was markedly reduced. The majority of scarred and other diseased corneas exhibited normal staining intensity for alpha 2-macroglobulin. Dot blot assays showed that the alpha 2-macroglobulin levels in the epithelial and stromal extracts of keratoconus corneas were lower than those found in normal human control counterparts. CONCLUSION: Keratoconus corneas contained a reduced level of alpha 2-macroglobulin. This result lends further support to the hypothesis that degradation processes may be aberrant in keratoconus.

Adolescent↗

PubMed1994

[c-erbB-2 oncogene product expression in lacrimal gland tumors].

Using a polyclonal antibody to the c-erbB-2 oncogene product (ErbB-2 protein), an immunohistochemical study on the expression of ErbB-2 protein in lacrimal gland tumors was performed. The expression of ErbB-2 protein was observed in 4 (33.3%) of 12 cases of pleomorphic adenoma, but was not in two cases of adenoid cystic carcinoma and one case of normal lacrimal gland. The immunohistochemical reaction was localized in the cell membrane and cytoplasm, and was more intense in the former. There were strongly stained cells in the epithelium of ductal cell lineage and in the solid area, and some of the cells in the myxoid/chondroid areas were weakly stained. The relation ErbB-2 protein with the malignant lacrimal gland tumors in general is not clear, but pleomorphic adenomas of lacrimal gland could have some relation with this protein.

Adult↗