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Biomedical subjects

C Katakami

Publications and source records attributed to C Katakami.

At least 37 records · Page 2Linked to original sources
PubMed1995

[The effect of epidermal growth factor on corneal endothelial wound healing in rabbits].

We investigated the effect of epidermal growth factor (EGF) on rabbit corneal endothelial wound healing in vivo. After a 6 mm-diameter metallic cryoprobe was applied to rabbit corneas, 0.1 ml of recombinant human EGF (100 micrograms/ml) or saline was injected into the anterior chamber. Corneas were excised on 1, 2, and 7 days postoperatively, labeled with 3H-thymidine and subjected to autoradiography. Some corneas were examined by scanning electron microscopy. Autoradiography showed that the number of endothelial cells incorporating 3H-thymidine in corneas treated with EGF was significantly greater than that in the control. Scanning electron microscopy demonstrated the effect of EGF on accelerating endothelial healing. These findings indicate that EGF has a stimulatory effect on the proliferation of wounded rabbit corneal endothelial cells in vivo. Under the conditions tested in the present study, there were no side effects of EGF such as neovascularization or cellular proliferation in the angle. The results suggest that EGF might be clinically applicable for corneal endothelial disorders.

Animals↗
PubMed1995

[The effect of epidermal growth factor on keratocytes during healing of corneal penetrating incision].

We investigated the effect of epidermal growth factor (EGF) on keratocytes during corneal wound healing focusing on cell proliferation. A penetrating linear incision was made in the center of rabbit corneas. The corneas were then treated with eye drops of recombinant human EGF (10 micrograms/ml) or physiological saline (control) four times a day. After 1, 2, 3, and 7 days, the corneas were excised, labeled with 3H-thymidine (10 microCi/ml) at 37 degrees C for 4 hours and subjected to autoradiography. The results demonstrated increased number of keratocytes incorporating 3H-thymidine on the 1st, 2nd, 3rd and 7th days of healing and accelerated stromal wound healing in corneas treated with EGF compared with the controls. Thus, EGF stimulates of proliferation keratocyte and promotes corneal stromal wound healing.

Animals↗
PubMed1994

[Corneoscleral wound healing after self-sealing cataract surgery--1. Histological findings in the early postoperative period].

We investigated histologically wound adaptation and healing after self-sealing cataract surgery in rabbits in the early postoperative period. A scleral pocket (4 mm wide, 2 mm long) and an internal corneal flap (2 mm long) were made in one eye in a series of rabbits. After phacoemulsification, a balanced salt solution was injected to self-seal the wound (self-sealing group). After the same procedures were performed in the contralateral eye, a horizontal 9-0 nylon suture was placed in the wound (suture group). On the first day after operation, the adaptation of the wound was better in the suture group than in the self-sealing group. On the fourth day, the scleral wound space was filled with fibroblastic cells and fibrin-like substance, and activated keratocytes had accumulated along the corneal wound. Although inflammatory cells collected around the suture in the suture group, there was no remarkable difference between the two groups on the seventh day. These results indicated that the adaptation of the wound in the early period was different between the self-sealing group and the suture group, and that the difference might result in different peripheral corneal curvature. This might be one of the causes of the postoperative astigmatism in the early stage.

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PubMed1993

The effect of hyaluronic acid on corneal epithelial cell proliferation.

PURPOSE: The authors investigated the mechanisms by which hyaluronic acid (HA) promotes corneal epithelial wound healing. The effect of HA on epithelial cell proliferation was examined in comparison with that of epidermal growth factor (EGF) and fibronectin (FN). METHODS: A penetrating linear incision (6-mm long) was made in the center of rabbit corneas. Immediately after wounding, the corneas were excised and cultured in TCM199 medium alone or medium containing HA (molecular weight, 860,000 Daltons; 100, 400, or 1000 micrograms/ml), EGF (25, 100, or 250 ng/ml), or FN (100 or 250 micrograms/ml) for 15 hr at 37 degrees C. The corneas were then labeled with tritiated thymidine (10 microCi/ml) and subjected to autoradiography. RESULTS: In the corneas cultured with HA at concentrations of 400 and 1000 micrograms/ml, the number of epithelial cells incorporating tritiated thymidine was significantly higher than that in the control corneas. In the corneas cultured with EGF at all concentrations, it was also higher than that of the control. FN did not affect cell proliferation. CONCLUSIONS: HA stimulates corneal epithelial cell proliferation. This stimulating effect of HA on epithelial cell proliferation might partly explain its effect in promoting corneal epithelial wound healing.

Animals↗
PubMed1992

Localization of collagen (I) and collagenase mRNA by in situ hybridization during corneal wound healing after epikeratophakia or alkali-burn.

The expression and localization of type I collagen and collagenase gene were studied by in situ hybridization using rabbit cornea during wound healing following epikeratophakia or alkali-burn. In corneas 24 days after epikeratophakia, alpha 1(I) collagen mRNA was detected in keratocytes which had migrated from the host cornea into the keratolens. In contrast, collagenase mRNA was detected in cells which seemed to be inflammatory cells around the suture between the host stroma and the keratolens. The increase of alpha 1(I) collagen mRNA in keratocytes was observed in corneas 94 days after epikeratophakia and in alkali-burned corneas 1-2 months after the burn. These results provide evidence that keratocytes synthesize collagen and that this synthesizing activity lasts for a long period during corneal wound healing.

Alkalies↗
PubMed1991

Collagen metabolism during healing of lacerated rabbit corneas.

We previously demonstrated that there are two waves of increased collagen synthesis following corneal laceration in rabbits. In the present study, we have examined whether increases in collagen synthesis and degradation result from increased amounts of mRNAs for collagen and collagenase, respectively. Rabbits were anesthetized by combined administration of ketamine (intramuscular) and pentobarbital (intravenous). A penetrating 8-mm incision was made at the center of each cornea. The lacerated corneas were allowed to heal for 0-49 days. The rabbits were then killed and the corneas excised. The total RNA was extracted from the tissue and subjected to slot-blot hybridization using 32P-labeled alpha 1(I) cDNA. The results indicate that there is a two-phase increase in the amount of alpha 1(I) mRNA in injured corneas and that the collagenase mRNA is elevated at most times throughout the healing period. However, the increase is collagenase mRNA may not fully account for the accelerated collagen degradation during corneal wound-healing. Thus, we propose that cells in the wound area may be directly involved in collagen degradation by phagocytosis. To examine our hypothesis, we cultured injured rabbit corneas in the presence or absence of leupeptin, a proteinase inhibitor. The tissues were then examined by electron microscopy. In the presence of leupeptin, lysosomes within fibroblasts or fibroblast-like cells in the wound area of the lacerated corneas healed for 2 and 3 weeks, contain collagen fibrils. In the absence of leupeptin no identifiable collagen was seen in the lysosomes.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1991

Keratocyte activity in wound healing after epikeratophakia in rabbits.

Epikeratophakia is a refractive surgical procedure for the correction of aphakia, high myopia, or keratoconus. To solve clinical problems associated with epikeratophakia, a basic knowledge of its postoperative healing process is needed. The authors investigated keratocyte activities, particularly cell proliferation and collagen synthesis, during wound healing after epikeratophakia in rabbits. Epikeratophakia was done on rabbit corneas with a homologous cryolathed keratolens. Ten, 16, 28, 45, 63, 90, 254, and 360 days after the operation, the corneas were excised, labeled with either 3H-thymidine (10 microCi/ml) or 3H-proline (10 microCi/ml) for 4 hr and examined histologically and by autoradiography. Keratocytes in keratolenses were killed during the freezing process. On postoperative day 10, a few keratocytes migrated to the edge of the keratolens from the host stroma. On days 16 and 28, keratocytes in the keratolens and host stroma near the junction between the host and the keratolens incorporated 3H-thymidine, suggesting active proliferation. The proliferating activity was no longer seen after day 45. The repopulation of keratocytes was almost complete on day 90 and gradually returned to normal through day 360. Keratocytes in the keratolens and host stroma beneath the keratolens showed a higher 3H-proline incorporation than the control from days 16-254 with the highest activity at around 4-9 weeks after surgery. These results suggest that remodeling of collagen fibers continues for a long postoperative period after epikeratophakia.

Animals↗
PubMed1991

[Keratocyte activity during wound healing of alkali-burned cornea].

The proliferation and collagen synthesis of keratocytes during corneal wound healing after alkali-burn were investigated using 3H-thymidine or 3H-proline autoradiography. The effect of epidermal growth factor (EGF) on keratocytes was also examined. On day 1 after burn, the wounded stroma lacked keratocytes, and keratocytes at the periphery of the wound started to proliferate from the endothelial side. On day 7 and day 14, the population of keratocytes returned to normal. Collagen synthesis activity of the keratocytes was observed from day 7 through day 56, with the highest activity on around day 21. After day 14, keratocytes at the site of epithelial reopening or ulceration started to proliferate again. In the early stage of wound healing more keratocytes incorporated H-thymidine in eyes treated with EGF than those treated without EGF, suggesting that EGF may stimulate the proliferation of keratocytes in the early stage of wound healing.

Alkalies↗
PubMed1990

[The ultrastructural changes in the corneal lens stroma of wound healing process following epikeratophakia in rabbits].

We investigated the ultrastructural change of corneal lens+ stroma histologically following epikeratophakia in rabbits. Epikeratophakia was performed on rabbit corneas using cryolathed corneal lens+. At days 10, 16, 45, 63 and 90 after the operation, pachymetry was performed, and corneas were excised and analyzed histologically using an electron microscope. At days 16 to 63, collagen fibril density (CFD) in corneal lens+ stroma decreased 57 to 63% of that in the control cornea, but returned to 78% at day 90. The results of pachymetry revealed that postoperative increase of corneal thickness was greater than the expected value at days 10 and 16. However, after that the corneal thickness decreased gradually and became thinner than the expected value after 45 days postoperatively. At days 45 to 90, many activated keratocytes with dilated and well developed rough endoplasmic reticulum, suggestive of active collagen production, were observed in corneal lens+ stroma. Furthermore, at day 90, keratocytes with extended pseudopoidia that suggested phagocytic activity were also observed, especially in the subepithelial zone. These findings indicated that collagen fibrils in the corneal lens+ stroma were damaged under the influence of the cryolathing process and partially exfoliated postoperatively, however, collagen-producing activity increased gradually and the reconstruction of corneal lens+ stroma continued through day 90 after the operation.

Animals↗
PubMed1990

Study on vitreous fibrosis induced by blood cells.

In order to examine the individual role of each blood cell type in causing vitreous fibrosis, monocytes and/or lymphocytes, or erythrocytes were separated from rabbit blood and injected into rabbit vitreous bodies. Vitreous fibrosis was induced by intravitreal injections of the mixture of monocytes and lymphocytes, monocytes alone, lymphocytes alone, and erythrocytes. Cell density-dependent vitreous fibrosis was observed in eyes injected with monocytes and/or lymphocytes. Lymphocytes were more potent than monocytes in inducing fibrosis. Glycosaminoglycans (GAGs) synthesized by fibrotic vitreous bodies induced by the mixture of monocytes and lymphocytes, and erythrocytes were characterized. The results indicated that 91% of total GAGs synthesized by normal vitreous was hyaluronic acid (HA). In contrast, in fibrotic vitreous, the synthesis of HA was decreased to about 30% whereas that of chondroitin sulfate (CS) was increased to 47-59% of total newly synthesized GAGs. The ratio of CS against total newly synthesized GAGs in fibrotic vitreous corresponded to the grade of fibrosis. Control vitreous bodies injected with freeze-thawed monocytes and lymphocytes synthesized 70% of HA and 12% of CS although no vitreous fibrosis was observed. These results suggest that intravitreal injection of monocytes and/or lymphocytes or erythrocytes may cause the infiltration of fibroblasts or fibroblast-like cells or the transformation of hyalocytes into fibroblasts, and that these fibroblasts may be responsible for the synthesis of CS.

Animals↗
PubMed1989

[Keratocyte activity in wound healing process following epikeratophakia in rabbits].

Epikeratophakia is a refractive surgery for the correction of aphakia, high myopia and keratoconus. Although many clinical studies of epikeratophakia have been performed, its wound healing process is not well understood. In the present study, we investigated keratocyte activities, particularly cell proliferation and collagen synthesis activity, during wound healing following epikeratophakia in rabbit corneas. Ten, 16, 28, 45, 63 and 90 days after the operation, corneas were excised, labeled with either 3H-thymidine (10 microCi/ml) or 3H-proline (10 microCi/ml) in DME for 4 hours and examined histologically, and by autoradiography. Ten days after the operation, almost no cells were seen in the keratolens except for a few keratocytes which had migrated to the edge of the keratolens. At days 16 and 28, keratocytes in the keratolens and in the host stroma near the junction between the host and the keratolens incorporated 3H-thymidine, suggesting active proliferation. The proliferating activity was no longer seen at days 45, 63 and 90. At day 90, almost complete repopulation with keratocytes was observed. Keratocytes in the keratolens and in the host stroma beneath the keratolens showed higher activity of 3H-proline incorporation than those in the control from day 16 through day 90 with the highest activity at day 28.

Animals↗
PubMed1989

[Reepithelialization of keratolens in the wound healing process following epikeratophakia in rabbits].

Most of the complications of epikeratophakia are minor and can be treated successfully. However, approximately 5 to 10% of cases of epikeratophakia result in removal of keratolenses mainly because of the failure to reepithelialize or chronic epithelial defects. In this study, in order to solve this problem we investigated the process of reepithelialization of epikeratophakia in rabbits. Epikeratophakia was performed on rabbit corneas using cryolathed keratolens. Ten, 16, 45, 63 and 90 days after the operation, corneas were excised, labeled with 3H-thymidine and examined histologically using light and electron microscope and autoradiography. 10 to 16 days after the operation, keratolenses were reepithelialized with a very thin epithelium of one or two layers. Epithelium thickened gradually, but was still thinner than normal controls at day 90. At days 10 and 16, basal cells of the epithelium showed high activity of 3H-thymidine incorporation, suggesting active proliferation. After that the proliferating activity decreased gradually and was no longer seen at day 90. Electron microscopic examination revealed no desmosomes or interdigitation between epithelial cells and poorly developed hemidesmosomes between basal cells and basement membrane at day 10, immediately after reepithelialization. At day 90, the epithelium over the keratolens showed areas where the basement membrane was irregular and extensively interrupted. These results indicated that in epikeratophakia, reepithelialization, recovery of epithelial thickness, formation of differentiated desmosomes or hemidesmosomes and normalization of ultrastructural abnormalities took longer than reepithelialization of usual epithelial defects. These results may explain the reason for of clinical problems of chronic epithelial defects or failure of reepithelialization in epikeratophakia. It was suggested that one of the factors causing delayed reepithelialization in epikeratophakia might be the cryolathing process of the keratolenses.

Animals↗
PubMed1988

Cell density dependency of vitreous fibrosis induced by monocytes and lymphocytes.

The possible roles of monocytes and lymphocytes in vitreous fibrosis were examined by injecting various numbers of the peripheral cell types into the rabbit vitreous. Our results indicated that the degree of vitreous fibrosis and the presence of traction retinal detachment corresponded to the number of cells injected. It was suggested that these findings are probably similar to vitreous membrane formation and retinal detachment in various clinical ocular diseases or inflammations in humans.

Animals↗
PubMed1986

Change in the synthesis of glycosaminoglycans by fibrotic vitreous induced by erythrocytes.

Vitreous fibrosis was induced in rabbit eyes by intravitreal injection of erythrocytes. The fibrotic vitreous removed from experimental animals were then incubated with [3H]glucosamine at 37 degrees C for 24 h. The newly synthesized 3H-labeled glycosaminoglycans were isolated by 4 M guanidium hydrochloride extraction followed by pronase digestion. The 3H-labeled glycosaminoglycans were then characterized by gel filtration column chromatography and by specific enzymatic degradation, i.e., hyaluronidase, chondroitinase AC, and/or chondroitinase ABC. The disaccharides derived from chondroitinase ABC degradation were identified by thin-layer chromatography. We previously demonstrated that 91% of the total glycosaminoglycan synthesized by normal vitreous was hyaluronic acid. Our present results indicate that in the fibrotic vitreous, the synthesis of hyaluronic acid was decreased to 26%, whereas the synthesis of chondroitin sulfate increased to 59% of the total newly synthesized glycosaminoglycans. These results suggest that cells present in fibrotic vitreous resemble fibroblasts with respect to their activities in glycosaminoglycans synthesis.

Animals↗
PubMed1986

Collagen metabolism following corneal laceration in rabbits.

We investigated the synthesis and degradation of collagen in lacerated rabbit corneas. The rate of collagen synthesis was measured by the incorporation and hydroxylation of [14C]proline up to 5 weeks after a penetrating laceration. Our results indicate that protein and collagen synthesis is initially reduced during the 24 h period after laceration and then increases in two phases. A moderate increase in protein and collagen synthesis occurs up to day 5 after laceration. Synthesis then decreases to a low level through the 10th day after injury. A second wave of increase in protein and collagen synthesis takes place reaching a new peak of approximately twice the activity as found in control corneas after 5 weeks of healing. Afterwards, the rate of protein and collagen synthesis declines and reaches the basal level after 7 weeks of healing. In a separate set of experiments, rabbit corneas were lacerated and allowed to heal for one or three weeks at which point 100 microCi of [14C]proline was injected into each anterior chamber. The corneas were excised 1 to 17 days later and subjected to collagen analysis. Our data indicates that the degradation of collagen synthesized by the cornea 1 week after laceration followed biphasic kinetics. In the first phase, the half-life of newly-synthesized collagen is 20 days, whereas it is approximately 4 days in the second phase. It is of particular interest that the accelerated degradation of the newly-synthesized [14C]collagen is concomitant with the increased rate of collagen synthesis during the wound healing process. The degradation of collagen synthesized 3 weeks after injury was slower and followed monophasic kinetics having a half-life of 14 days. The degradation of non-collagenous 14C-proteins follow a monophasic kinetics having a half-life of 6-7 days. Polyacrylamide gel electrophoresis of newly-synthesized collagen indicated that the collagen(I) and collagen(V) were the main collagenous components synthesized by the lacerated corneas.

Animals↗
PubMed1985

Synthesis of chondroitin sulfate by fibrotic vitreous induced by monocytes and lymphocytes.

Vitreous fibrosis was induced in rabbit eyes by intravitreal injection of monocytes and lymphocytes. The fibrotic vitreous and normal vitreous removed from experimental animals were then incubated with [3H]-glucosamine at 37 degrees C for 24 hr. The newly synthesized 3H-labeled glycosaminoglycans (GAGs) were isolated by 4 M GuHCl extraction followed by pronase digestion. The 3H-labeled GAGs were then characterized by gel-filtration column chromatography and by specific enzymatic degradation, i.e. hyaluronidase, chondroitinase AC and/or chondroitinase ABC. The disaccahrides derived from chondroitinase ABC degradation were identified by thin-layer chromatography. Our results indicated that 91% of the total glycosaminoglycan synthesized by normal vitreous was hyaluronic acid. In contrast, in the fibrotic vitreous, the synthesis of hyaluronic acid was decreased to 30% whereas the synthesis of chondroitin sulfate increased to 47% of the total newly synthesized glycosaminoglycans. Control vitreous which was injected with freeze-thawed monocytes and lymphocytes synthesized 70% hyaluronic acid and 12% chondroitin sulfate although no fibrosis was observed.

Animals↗
PubMedDate not supplied

Cataract surgery in patients with advanced Mooren's ulcer.

BACKGROUND: We describe 2 patients with severe Mooren's ulcer who underwent phacoemulsification and intraocular lens implantation surgery. The clinical features of this disease are highlighted. CASE: A detailed study of the ocular and laboratory findings in these patients, together with a review of the literature, is presented. OBSERVATIONS: There was a visually rewarding outcome after phacoemulsification and intraocular lens implantation were performed, and Mooren's ulcer did not recur. CONCLUSION: We conclude that phacoemulsification-aspiration and intraocular lens implantation surgery with a small incision can be successfully performed in patients with Mooren's ulcer after complete control of inflammation with topical and oral steroid therapy, or with ocular reconstruction surgery when required.

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