Biomedical subjects

S Saika

Publications and source records attributed to S Saika.

At least 73 records · Page 4Linked to original sources

PubMed1995

Type IV collagen in the basement membrane of the corneal epithelium after alkali burns in guinea pigs.

To investigate the changes in the corneal epithelial basement membrane following an alkali burn, we examined the immunolocalization of type IV collagen and laminin in the eye of the guinea pig burned with alkali. The burn damaged the corneal, limbal and conjunctival epithelium. After regeneration, basement membrane was interrupted, as indicated by laminin immunoreactivity. Type IV collagen immunoreactivity was transiently expressed in the early healing phase in the epithelial derived from both the cornea and conjunctiva, but was not seen in the normal corneal epithelial basement membrane. Later in the healing process, following transdifferentiation of the conjunctival epithelium into a cornea-like epithelium, its type IV collagen immunoreactivity was weaker than that in the basement membrane of the nontransdifferentiated epithelium. Conjunctival transdifferentiation during healing may have led to transient development of type IV collagen immunoreactivity.

Animals↗

PubMed1995

Effect of a prolyl hydroxylase inhibitor on rabbit ocular fibroblasts.

We examined the effect of a prolyl hydroxylase inhibitor, ethyl-3,4-dihydroxybenzoate (E-DHB), on collagen production, proliferation, and spreading by cultured rabbit keratocytes and subconjunctival fibroblasts. Proliferating cells were incubated with or without E-DHB, and were examined by phase-contrast microscopy and proliferation assays. In addition, wounds were made in confluent cultures and were allowed to heal with or without exposure to E-DHB. Confluent cells were also observed by transmission electron microscopy after exposure to E-DHB (0.2-0.4 mM). Finally, confluent cells were incubated in the presence or absence of E-DHB, after which the concentration of soluble collagen in the culture medium was determined. E-DHB (0.2-0.4 mM) inhibited the growth of rabbit keratocytes and subconjunctival fibroblasts and decreased collagen production without inducing cytotoxicity.. Wounds in the control culture were initially healed by individual migrating cells and later by spreading monolayer sheets and proliferating cells, while E-DHB inhibited cell migration into the wound. Electron microscopy revealed large irregular cisternae of endoplasmic reticulum in E-DHB-treated cells, possibly due to protein accumulation. These findings suggest that collagen production may be closely related to various cellular activities.

Animals↗

PubMed1994

Prolyl hydroxylase inhibitor and lysyl hydroxylase inhibitor inhibit spreading of corneal epithelium.

BACKGROUND: The spreading of epithelium is critical in the healing of corneal wounds. Such epithelial spreading requires the continuous production of protein and glycoprotein. To determine whether collagen production is required for the spreading of corneal epithelium, we studied the effects of inhibitors for collagen production on spreading of corneal epithelium in vitro. METHODS: We examined the effect of two proline analogs, L-azetidine 2-carboxylic acid and cis-hydroxyproline, a prolyl hydroxylase inhibitor, ethyl-3,4-dihydroxybenzoate, and a lysyl hydroxylase inhibitor, minoxidil, on the spreading of epithelium of organ-cultured rabbit cornea. RESULTS: Both analogs and inhibitors inhibited epithelial spreading in a dose-dependent manner. CONCLUSION: These observations indicate that collagen production may be involved in the spreading of corneal epithelium.

Animals↗

PubMed1993

Ascorbic acid phosphate ester and wound healing in rabbit corneal alkali burns: epithelial basement membrane and stroma.

We examined the effect of L-ascorbic acid 2-phosphate (P-Asc) on the healing of alkali-burned corneas in rabbits. Round filter paper containing 1 N NaOH was applied to the central cornea for 60 or 120 s to produce the alkali burn. Animals were treated with topical saline, 10% ascorbate, or 6.5% P-Asc applied on the cornea. The corneas were then examined histologically. Burned stroma showed no toluidine blue staining, indicating a loss of glycosaminoglycan. In the 60-s burn group, P-Asc reduced the size of the unstained area as compared with the control. Transmission electron microscopy showed basal lamina under new epithelia in the corneas treated with ascorbate or P-Asc, but not in controls. These observations support the theory that P-Asc may have a therapeutic role in the repair of corneal alkali burns.

Administration, Topical↗

PubMed1993

Cellular fibronectin on intraocular lenses explanted from patients.

We investigated the origin of fibronectin (FN) on five posterior and four anterior chamber explanted intraocular lenses (IOLs) using immunohistochemical methods. Cellular deposits (assumed to be macrophages) and fibrous or membrane-like proteinaceous deposits on the IOLs showed immunoreactivity to an antibody against cellular FN. These proteinaceous deposits were believed to be products of the cells that adhered to the IOLs.

Aged↗

PubMed1993

Ascorbic acid and proliferation of cultured rabbit keratocytes.

The effect of ascorbate and L-ascorbic acid 2-phosphate (P-Asc), a stable derivative of ascorbate, on the growth of cultured rabbit keratocytes was examined. In a 12-day culture, P-Asc (0.05-0.1 mM) and ascorbate (0.05 mM) enhanced the growth of the cells, whereas 0.1-1.0 mM ascorbate was cytotoxic to the cells. An increase in the concentration of P-Asc up to 1.0 mM resulted in no further change in the cell growth. The effect of 0.1 mM P-Asc was observed after the confluency had been achieved in the culture. The lower toxicity of P-Asc may be due to its stability. The presence of both 0.1 mM P-Asc and mouse epidermal growth factor in the medium stimulated cell growth to a higher degree than each factor alone. The results suggested that these two factors enhance the growth of keratocytes in a different manner.

Animals↗

PubMed1993

Epithelial basement membrane in alkali-burned corneas in rats. Immunohistochemical study.

We investigated the altered immunolocalization of the components of epithelial basement membrane (BM) in rats with alkali burns of the cornea. Type IV collagen, laminin, and fibronectin were immunohistochemically stained in the alkali-burned corneas after various intervals. Linear laminin immunoreactivity, which represented the localization of the BM, was interrupted, probably by epithelial enzymes, under the regenerating epithelium after 24 h. A normal configuration was restored on day 7, when the central corneal BM showed a type IV collagen immunoreactivity that was not detected in BM of normal cornea. The exact cause of the development of type IV collagen immunoreactivity in the healing BM was not determined. Laminin, type IV collagen, and fibronectin, which were not detected in normal stroma, were all detected in the healing corneal stroma with repopulated keratocytes. Moreover, the BM zone under the regenerating epithelium showed fibronectin immunoreactivity on days 5-14. Distribution of these components of BM seemed to be normal 2 months postburn. The alteration of BM components is thought to be an important marker of the healing process in corneas burned with alkali.

Animals↗

PubMed1993

Cis-hydroxyproline inhibits adhesion, migration and proliferation of cultured rabbit keratocytes.

Recruitment of keratocytes into injured corneal stroma, and secretion of proteins including collagen in the cells are essential for wound healing of the corneal stroma. We examined the effect of a proline analog, cis-hydroxyproline, on the adhesion, migration and growth of rabbit keratocytes in vitro. This agent decreased the plating efficiency, migration and growth of the keratocytes in a dose-dependent manner. Reduction in these cellular activities may reflect altered functions of pericellular proteins such as collagen. Further studies are needed to determine which specific protein is involved.

Animals↗

PubMed1992

Clinical trial of a lyophilized inactivated hepatitis A candidate vaccine in healthy adult volunteers.

The safety and immunogenicity of a lyophilized inactivated hepatitis A vaccine was tested in healthy adult male volunteers. Thirty-six volunteers, all of whom were negative for antibody to HAV (anti-HAV), were divided into three dosage groups, 1.0, 0.5 and 0.25 micrograms of viral protein, respectively. Each group received a total course of three intramuscular injections at months 0, 1 and 6. Slight side effects were noted after 16 of 99 injections and the occurrence and degree were almost identical to those of other commercial vaccines. On the other hand, all subjects had measurable titres of serum anti-HAV neutralizing antibodies as early as 2 months after the first injection. The mean values of serum anti-HAV neutralizing antibodies at 7 months in the 1.0, 0.5 and 0.25 micrograms dose groups were 64-, 12-, and 9-fold higher, respectively, than those observed at 5 days in five recipients given 7.5 mg kg-1 body weight of immune serum globulin (ISG).

Adolescent↗

PubMed1992

Collagenous deposits on explanted intraocular lenses.

An immunohistochemical study of type I collagen in deposits on the surface of two intraocular lenses (IOLs) explanted from human eyes was conducted. Type I collagen-immunoreactive proteinaceous deposits with cells were found around the haptics of an iris-supported IOL. A few such deposits and what appeared to be macrophages were observed on the optic. A few cells (presumably macrophages and giant cells) were observed on a posterior chamber IOL, whereas proteinaceous deposits that reacted positively to the antibody were not identified. Type I collagen-immunoreactive deposits on the iris-supported IOL were thought to be the products of fibroblastic cells, originating from iris tissue, that attached directly to the haptics and helped stabilize the implant.

Aged↗

PubMed1992

Ultrastructural effect of L-ascorbic acid 2-phosphate on cultured keratocytes.

I studied the effect of L-ascorbic acid 2-phosphate (P-Asc), a long-acting derivative of L-ascorbic acid, on the fine structures of cultured rabbit keratocytes. The results showed that cells cultured with 0.1 mM P-Asc for 30 days were more markedly multilayered than those grown without P-Asc. Dilation of the cisternae of the endoplasmic reticulum in the control cells indicated an accumulation of protein (probably procollagen). In addition, many lysosome-like structures, which may degrade underhydroxylated procollagen, were observed in the cytoplasm of the control cells. A slight increment of free ribosomes was also found within the control cells. P-Asc enhanced the multilayerization of cultured keratocytes. We conclude that the changes seen in the cytoplasm are due to the effect of P-Asc acting as vitamin C.

Animals↗

PubMed1992

L-ascorbic acid 2-phosphate enhances the production of type I and type III collagen peptides in cultured rabbit keratocytes.

We studied the effect of L-ascorbic acid 2-phosphate (P-Asc), a long-acting phosphate derivative of L-ascorbic acid, on the production and secretion of type I and type III collagen peptides in cultured rabbit keratocytes using immunohistochemistry and enzyme immunoassay. P-Asc enhanced production and secretion of these collagen peptides. Our observations support a therapeutic role for P-Asc in the repair of corneal stromal damage such as caused by corneal chemical burn.

Animals↗

PubMed1992

A case of frosted-branch retinal angiitis in a child.

We report the case of a patient with frosted-branch angiitis of the retina in a 3-year-old girl. She had acute visual disturbances OU, and we observed iritis, retinal edema, and retinal angiitis. Retinal angiitis showed the same condition as previously described, the so-called acute frosted retinal periphlebitis accompanied with vascular sheathing. Her eyes improved rapidly after administration of an oral corticosteroid, and during the ensuing four months, she had no recurrences.

Child, Preschool↗

PubMed1992

Phagocytosis and fibronectin of cells observed on intraocular lenses.

The phagocytic activity and distribution of fibronectin in the cells adhering to implanted intraocular lenses (IOLs) were studied in rabbits. IOLs were explanted from the posterior chamber 7 days after implantation. Phagocytosis by the cells from the IOLs was studied by electron microscopy after incubation with polystyrene beads. The distribution of fibronectin was examined immunohistochemically using an anti-fibronectin antibody. Many presumed macrophages and giant cells which were thought to be of macrophagic origin were observed on the IOLs. Adherence of the beads to the surface of the cells, phagocytosis of these beads, and fibronectin immunoreactivity were prominent in these presumed macrophages, whereas giant cells displayed a reduction in these activities. These findings suggest that the adherence activities of the presumed macrophages are less after giant cells are formed, reflecting a reduced production of fibronectin.

Animals↗

PubMed1991

L-ascorbic acid 2-phosphate, a phosphate derivative of L-ascorbic acid, enhances the growth of cultured rabbit keratocytes.

We examined the effect of L-ascorbic acid 2-phosphate (P-Asc) on the proliferation of cultured rabbit keratocytes. P-Asc is a phosphate derivative of L-ascorbic acid and has more prolonged vitamin C activity in solution than does L-ascorbic acid. The proliferation of cultured keratocytes was promoted by the presence of P-Asc in culture medium. Transmission electron microscopic observations revealed that cells were more multi-layered after culture in the presence of P-Asc (0.1 mM) for 30 days than were those cultured in the absence of P-Asc. The effect of P-Asc was abrogated by L-azetidine 2-carboxylic acid, which is an analogue of proline that inhibits the production and secretion of collagen. Our observations support a therapeutic role for P-Asc in the repair of corneal stromal damage such as that caused by a corneal chemical burn.

Animals↗

PubMed1991

[Effect of L-ascorbic acid 2-phosphate on cultured rabbit keratocytes (the third report). The effect on production and secretion of type I collagen].

We examined the effect of L-ascorbic acid 2-phosphate (P-Asc), a long-acting phosphate derivative of L-ascorbic acid, on intracellular distribution and production of type I collagen in cultured rabbit keratocytes by an immunohistochemistry and enzyme immunoassay. Exposure of 0.1 mM P-Asc for 10 hours decreased a type I collagen immunoreactivity of the cytoplasm as stained in fine granular materials. 0.1 mM P-Asc induced increase of type I collagen level in the medium. The results suggested that 0.1 mM P-Asc might increase the biosynthesis and secretion of type I collagen in keratocytes and have a therapeutic effect on corneal stromal damage.

Animals↗

PubMed1991

Immunohistochemical study of deposits on intraocular lenses explanted from human eyes.

Immunohistochemical studies of deposits were carried out on two intraocular lenses (IOLs) explanted from human eyes. One anterior chamber intraocular lens (AC-IOL) was studied using a monoclonal anti-human type I collagen-peptide antibody (C-Ab). One posterior chamber intraocular lens (PC-IOL) was studied using a monoclonal anti-human vimentin antibody (V-Ab). Most of the cells on the AC-IOL contained many melanin granules in the cytoplasm and were thought to be macrophages. They did not show any immunoreactivity to C-Ab. Some spindle-shaped cells and fibrous deposits at the margin of the lens optics showed immunoreactivity to the antibody. These cells were thought to be fibroblasts migrating from the tissue around the IOL, such as the iris. On the PC-IOL, many mononuclear cells and multinucleated giant cells were observed. These cells showed immunoreactivity to vimentin and contained immunostained fibers which were intermediate filaments. They were thought to be either of mesodermal origin or derived from the lens epithelium.

Aged↗

PubMed1991

[Effect of L-ascorbic acid 2-phosphate on cultured rabbit keratocytes (the second report)].

We examined the effect of L-ascorbic acid 2-phosphate (P-Asc) on the proliferation of cultured rabbit keratocytes. P-Asc is a derivative of L-ascorbic acid and it yields more prolonged effects of vitamin C in solution than L-ascorbic acid. The proliferation of cultured rabbit keratocytes was promoted by the presence of P-Asc in culture medium for 10, 20, and 30 days. Transmission electron microscopic observations revealed that the cells were more multilayered in the presence of P-Asc (0.1mM) for thirty days than those in the absence of P-Asc. Moreover, this effect of P-Asc was attenuated by azetidine 2-carboxylic acid which is an inhibitor of collagen synthesis. Hence, it is suggested that the promotive effect of P-Asc on the growth of cultured keratocytes is related to the synthesis of collagen. Based on our observations, P-Asc may have a therapeutic effect on corneal stromal damages such as a corneal chemical burn and surgical trauma.

Animals↗