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Biomedical subjects

K Nakayasu

Publications and source records attributed to K Nakayasu.

At least 55 records · Page 3Linked to original sources
PubMed1997

Effect of topical tranilast and corticosteroids on subepithelial haze after photorefractive keratectomy in rabbits.

BACKGROUND: Tranilast (trade name Rizaben), an anti-allergic drug with anti-inflammatory effects, is thought to inhibit synthesis of extracellular matrix of fibroblasts through the suppression of TGF-beta. We evaluated the effect of topical tranilast on the subepithelial haze that developed after excimer laser keratectomy and its effect was compared with that of betamethasone eye drops METHODS: Excimer laser keratectomy (phototherapeutic keratectomy mode) was performed with the Nidek EC-5000 excimer laser on 16 rabbit corneas (eight rabbits). From the second postoperative day, topical 2% tranilast was instilled in the right eye and the control solution in the left eye, four times daily. Until the fourth week after the operation, we measured the densitometric values of scattered light intensity of the subepithelial haze with an anterior ocular analyzer, EAS-1000 (Nidek). At the fifth postoperative week, light and electron microscopy and immunohistochemistry with an antibody to TGF-beta were also performed. RESULTS: Densitometric values of the subepithelial haze in the corneas treated with 2% tranilast were slightly less than those of the subepithelial haze in the control corneas. However, the values of the subepithelial haze in the betamethasone-treated corneas were significantly less than those in control corneas. Histochemical examinations revealed that topical tranilast had a small effect on the subepithelial haze after excimer laser keratectomy in rabbits. CONCLUSION: Topical 0.1% betamethasone can limit the amount of subepithelial haze and tranilast may inhibit development of subepithelial haze by the suppression of TGF-beta.

Administration, Topical↗
PubMed1997

[The ultrastructure of lens capsule abnormalities in Alport's syndrome].

The ultrastructure of lens capsule abnormalities in Alport's syndrome is reported. An anterior lens capsule from a 29-year-old patient with lenticonus who was affected by Alport's syndrome was obtained at phacoemulsification. The histopathological findings showed decreased thickness of the anterior lens capsule and there were many vertical capsular dehiscences localized at the inner part of the lens capsule. Almost every dehiscence was limited to the inner two-thirds of the capsule. One should be cautious in attempting intraocular lens implantation into the lens capsule, since the lens capsule may be fragile in this disease.

Adult↗
PubMed1996

[Six cases of secondary keratoconus with Fleischer's ring pattern corneal epithelial iron ring].

We observed 6 cases of secondary keratoconus with Fleischer's ring pattern corneal epithelial iron ring. These 6 cases were 2 males and 4 females. The causes of secondary keratoconus were 2 cases of trachoma, 2 cases of trauma, 1 case of keratitis, and 1 case of unknown origin. All showed thinning of the cornea and Fleischer's ring pattern corneal epithelial iron ring. After penetrating keratoplasty of 1 case, the button of the recipient showed the deposition of hemosiderin in the corneal epithelium stained blue by Prussian blue. At the same time we confirmed the existence of iron in the corneal epithelium by the X-ray ultimate analysis. Fleischer's ring is considered to be characteristic of keratoconus, but we have found that Fleischer's ring is also seen in secondary keratoconus in which the cornea becomes thinner secondarily for some reason.

Adult↗
PubMed1996

[Glycosaminoglycans in subepithelial opacity after excimer laser keratectomy].

We evaluated histochemically the characteristics of glycosaminoglycans and proteoglycans in the corneal subepithelial opacity after excimer laser keratectomy on rabbit corneas. We also performed the same evaluations on the cornea after mechanical keratectomy. Twenty days after the operations, the area immediately subjacent to the epithelium showed strong staining with toluidine blue, alcian blue, and colloidal iron. However, after treatment with chondroitinase ABC or chondroitinase AC, alcian blue staining in this area decreased dramatically. Antilarge proteoglycan antibody also reacted strongly in this area. Histochemical and immunohistochemical examination of the cornea where mechanical keratectomy was done showed basically similar findings with the cornea of excimer laser keratectomy. These results suggest that large-molecula proteoglycans with chondroitine sulfate side chains become localized in the subepithelial area after two different kinds of keratectomies. We presume from histochemical and immunohistochemical observations that the subepithelial opacity observed after excimer laser keratectomy is not a special reaction to excimer laser but simply a corneal scar formed after stromal resection.

Animals↗
PubMed1996

[Distribution of conjunctival goblet cells and observation of goblet cells after conjunctival autotransplantation in rabbits].

Conjunctival goblet cells are essential for maintaining a normal ocular surface and important for recovering a diseased ocular surface. However, how goblet cells in conjunctival epithelium evolve after transplantation are uncertain. We experimented with albino rabbits to study the distribution of goblet cells in normal conjunctiva. We performed autograftings of conjunctiva which contained many goblet cells on the sclera of albino rabbits, and made histological observations on how goblet cells evolved after transplantation. The results were as follows. 1. Goblet cells in the normal rabbits were most abundant at the lid margin of both upper and lower tarsal conjunctiva. 2. We made autograftings of conjunctiva on the sclera of albino rabbits. The goblet cells on the transplanted conjunction disappeared for a short time on the 3rd day after transplantation. On the 7th day and onwards they reappeared, and by the 14th day a large number of goblet cells were observed. 3. Between the 7th and 14th day after autografting, epithelial differentiation of the grafted conjunctiva occurred.

Animals↗
PubMed1996

Non-contact specular microscopic observation for early response of corneal endothelium after contact lens wear.

PURPOSE: Contact lenses induce short- and long-term corneal endothelial changes, including endothelial blebs. The endothelial bleb is a reversible, short-term response found on the corneal endothelium after lens wear. We used non-contact specular microscopy to observe endothelial blebs occurring with different types of contact lenses. METHODS: We observed the time course, frequency, and location of endothelial blebs in 11 eyes of 9 contact lens wearing patients. Eight types of contact lenses with various oxygen transmissibilities (Dk/L) were used in the study. RESULTS: Blebs were observed in the central cornea in patients with polymethylmethacrylate and rigid gas permeable contact lenses, while blebs in the central to mid-peripheral cornea were seen in patients wearing soft contact lenses. CONCLUSIONS: Although the number of blebs vary by individual patient, there appears to be an inverse correlation between the number of blebs and the Dk/L of the contact lens.

Adult↗
PubMed1996

[Immunohistochemical localization of acidic and basic fibroblast growth factor through corneal neovascularization in vivo and in vitro].

Neovascularization on the center of rabbit cornea was induced by 5N.NaOH alkali burns. We studied the change in localization of acidic fibroblast growth factor (a-FGF) and basic fibroblast growth factor (b-FGF) through corneal neovascularization with immunohistochemistry, using eyes which we enucleated on the 3rd, 7th, and 14th day. Moreover, by co-cultivation of rabbit corneal stromal cells and adrenal cortical vascular endothelium of bovine, a capillary-like code was induced, in which we also studied the localization of a-FGF and b-FGF on the 3rd, 7th, and 14th day. On the 14th day after the alkali burn we recognized intrastromal neovascularization and positive staining of a-FGF and b-FGF around it. Strong staining of a-FGF was observed in goblet cells through the experimental period. In control eyes we recognized positive reaction of a-FGF in corneal and conjunctival epithelium. In co-cultured cells, we recognized positive staining of both a-FGF and b-FGF around the capillary-like code which was induced among the corneal stromal cells.

Animals↗
PubMed1995

[Incidence of tumors and tumor-like lesions in the conjunctiva and the cornea].

Incidence of tumors and tumor-like lesions in conjunctiva and cornea seen at Juntendo University during the 13-year period from 1980 to 1992 was analysed histopathologically. There were 126 cases including 116 benign (92.1%) and 10 malignant lesions (7.9%). Pigmented nevi (32 cases) were most frequently found, accounting for 27.6% of the benign tumors and tumor-like lesions, half of which were compound nevi (16 cases). Nevi were closely followed by cysts (24 cases, 20.7%) and dermoids (15 cases, 12.9%). Carcinoma in situ (3 cases) was most frequently found, accounting for 30% of the malignant tumors (10 cases), closely followed by malignant lymphoma (2 cases), squamous cell carcinoma (2 cases), mucinous carcinoma (1 case), sebaceous gland carcinoma (1 case) and metastatic tumor (1 case). The ratio of males to females was 4:6. Age distribution of the patients was 47-92 years.

Adolescent↗
PubMed1995

[Clinical importance of inclusion cysts of nevi in bulbar conjunctiva].

We investigated 30 cases of nevi in bulbar conjunctiva histopathologically from 1980 to 1992. The patients' ages were between 5 and 85 years old (mean, 21 years). Investigated parameters of the tumors were the location, growth pattern, and the presence of inclusion cysts, melanin granules, goblet cells, and feeding vessels. Of 30 cases, 26 cases (87%) had inclusion cysts which were characteristic findings of conjunctival nevi. The mucous secretion from goblet cells may play an important role in the synthesis of inclusion cysts, but goblet cells were not found in 9 cases. This finding suggests that other secretory cells may be present. Four cases without inclusion cysts consisted of flat tumors. From this finding, the presence of inclusion cysts may be related to the growth of tumors. We conclude that the growth of the pigmented conjunctival tumors with inclusion cysts suggests a benign growth pattern. A periodical follow-up study or biopsy should be performed, if inclusion cysts are not found.

Adolescent↗
PubMed1995

Development of a new soft gas permeable contact lens with Dk 300.

The effects on the rabbit cornea of a new gas permeable nonhydrophilic soft contact lens made of newly designed polymer with a Dk value of 300 were studied physiologically, histologically, and histochemically during 5 days of daily wear followed by 14 days of extended wear. Corneal swelling was observed to be within 10% of corneal thickness during the wear period. No serious corneal surface changes were observed. Specular microscopy showed no endothelial changes in terms of cell density, coefficient of variation of cell area (CV), or hexagonality before and 2 weeks after lens wear. Histochemical study using periodic acid-Schiff staining and histological study with hematoxylin-eosin revealed no remarkable changes. Scanning electron microscopy revealed slight focal changes; there were no significant changes. The results show that the new soft gas permeable contact lens has no harmful effect on the rabbit cornea.

Animals↗
PubMed1994

Ringed grafting for an abdominal aortic aneurysm in a 92-year-old patient: report of a case.

We report herein the case of a 92-year-old man with an abdominal aortic aneurysm who underwent successful surgical resection using a ringed graft. His postoperative course was uneventful, and he was discharged after 42 days, following which he attended the outpatient department twice a month for regular check-ups. He finally died of pneumonia which developed from an upper respiratory tract infection 6 months after his operation. Thus, surgical treatment should always be considered when an aneurysm is detected, even in very aged patients for whom the activities of daily living are possible.

Aged↗
PubMed1993

Deletion of 19 base pairs in intron 13 of the gene for the pro alpha 2(I) chain of type-I procollagen (COL1A2) causes exon skipping in a proband with type-I osteogenesis imperfecta.

Skin fibroblasts from a proband with mild osteogenesis imperfecta (type I) synthesized normal pro alpha 2(I) chains and shortened pro alpha 2(I) chains of type-I procollagen. The type-I collagen that contained the shortened alpha 2(I) chains was thermally unstable in that it was cleaved at 30 degrees C by a mixture of trypsin and chymotrypsin. The mutation generating the shortened pro alpha 2(I) chains was shown to be a deletion of 19 base pairs from +4 to +22 of intron 13 of the COL1A2 gene by sequencing of genomic DNA and allele-specific oligonucleotide hybridization. The same mutation was found in the proband's affected father. Probe-protection experiments with S1 nuclease demonstrated that about 88% of the RNA transcripts from the mutated allele were spliced by exon skipping from exon 12 to exon 14 and that about 12% of the RNA transcripts were normally spliced. There was no evidence for use of cryptic splice sites, even though two cryptic splice sites had more favorable statistical scores and delta G degree 37 values than the new site that was created by the mutation and that was used for splicing of 12% of the transcripts into a normal mRNA. Comparison of the results with observations on 17 previously reported mutations that produced in-frame deletions of amino acids from the triple-helical domain of type-I collagen indicated that deletions in the N-terminal half of the alpha 2(I) chain tended to produce milder phenotypes than similar deletions elsewhere in the alpha 1(I) or alpha 2(I) chains.

Adolescent↗
PubMed1993

[The effect of hyaluronic acid on proliferation and differentiation of capillary endothelial cells].

The effects of hyaluronic acid (HA) on capillary endothelial cells were studied in cell culture. The capillary endothelial cells were obtained from the bovine adrenal cortex. The proliferation of endothelial cells was inhibited by the addition of HA to the culture medium. Significant inhibition was observed consistently at concentrations of 100 micrograms/ml or greater. Capillary-like networks were formed by the differentiated endothelial cells in co-culture with rabbit corneal keratocytes and in type I collagen gels. They were inhibited by the addition of HA at a concentration of 200 micrograms/ml. The cell proliferation and differentiation were not significantly affected by different HA molecular weights.

Animals↗
PubMed1992

Single moving dipole obtained from magnetic field of the heart in patients with left ventricular hypertrophy.

Magnetocardiograms (MCGs) were recorded by means of a second-derivative SQUID (superconducting quantum interference device) magnetometer in 20 normal subjects and 28 patients with left ventricular overload to analyze the activation sequence of the heart and amplitude of estimated current source. In the normal subjects, the dipole was directed to the left and gradually superiorly 40 ms after the beginning of the QRS wave mainly due to the activation of the left ventricle. In the patients with hypertension, the direction and location of the dipoles were similar to those of the normal subjects, but their dipole moments were increased. In the patients with mitral regurgitation, the dipoles of late QRS were directed more inferiorly than in the normal subjects and their amplitude was increased. In the patients with aortic valve disease, the amplitude of the dipoles was increased markedly and their location was deviated more to the left than the dipoles of the normal subjects. We established the criterion for diagnosis of LVO from the dipole moment of 50 ms of 3.13 x 10(-3) A or more. The sensitivity of this criterion is significantly higher in the diagnosis of left ventricular overload than the electrocardiogram (ECG). The present study shows that the moving dipole method is useful to determine the increased electromotive force in patients with left ventricular overload and that sensitivity in diagnosis of left ventricular overload is increased.

Aortic Valve Insufficiency↗
PubMed1992

Formation of capillary-like tubes by vascular endothelial cells cocultivated with keratocytes.

This report describes an in vitro system that could be useful for investigating corneal neovascularization. When isolated bovine capillary endothelial cells (CEC) were cocultivated with rabbit corneal keratocytes, capillary-like cords extended actively from the endothelial cells in the multilayers of the keratocytes. The developing cords continued to elongate, branch out, and anastomose with each other, forming a capillary-like network by the 12th day of coculturing. Electron microscopic observation revealed that the cords were tubular structures composed of three to seven endothelial cells in the multilayers of keratocytes, and that a basal lamina-like matrix was situated at the abluminal face of the endothelial cells. The growth of cellular cords from the cloned CEC also occurred when CEC were seeded onto a cell-free extracellular matrix that had been synthesized by keratocytes. Keratocyte-conditioned medium alone did not stimulate proliferation of CEC. These observations clearly indicate that the formation of capillary-like structures by CEC depended upon the presence of an extracellular matrix produced by keratocytes, rather than upon the keratocytes themselves or any other keratocyte byproduct. This simple in vitro experimental system is proposed as a useful tool for studying corneal neovascularization.

Adrenal Cortex↗
PubMed1992

[In vitro formation of endothelial cells into capillary-like cords is promoted by keratocytes].

When isolated bovine capillary endothelial cells were co-cultivated with rabbit corneal keratocytes, capillary-like cords extended actively from the capillary endothelial cells in multilayers of keratocytes. The developing cords continued to elongate, branch out and anastomose with each other, forming a capillary-like network by the 12th day of co-culturing. Electron microscopic observation revealed that the cords had tubular structures, which were composed of 3-8 endothelial cells in the multilayers of keratocytes, and that a basal-like matrix was situated on the outer surface of the endothelial cells. The roles of keratocytes in the cord formation by capillary endothelial cells were discussed. This simple in vitro experimental system is proposed as a useful tool in the study of corneal neovascularization.

Animals↗
PubMed1991

[Mitotic activity of rabbit corneal epithelium in vitro].

It is difficult to maintain corneal epithelial cells for several passages in culture. At a first step to establish a culture system for corneal epithelium, the authors evaluated factors which seemed to be involved in the growth kinetics and mitotic activity of rabbit corneal epithelium in vitro. First of all, to compare the growth kinetics of peripheral and central epithelium, we measured the areas and distances of the epithelium that outgrew from peripheral and central explants in culture. The peripheral corneal epithelium grew 1.2-to 1.6-fold better than the central corneal epithelium. However, there was no significant difference between them. Secondly, we evaluated the effects of epidermal growth factor (EGF), cholera toxin (CTX) and insulin, which were contained in supplemented hormonal epithelial medium (SHEM) developed by Jumblatt et al, on the mitotic activity of rabbit corneal epithelium. Among these drugs, only EGF had the ability to increase the epithelial cell number after 10 days of incubation. By contrast, CTX which elevated the level of cyclic AMP inhibited the proliferation of the epithelium.

Animals↗