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K Nakayasu

Publications and source records attributed to K Nakayasu.

At least 37 records · Page 2Linked to original sources
PubMed1999

Analysis of glycosaminoglycans in rabbit cornea after excimer laser keratectomy.

BACKGROUND/AIMS: The biochemical basis for the development of subepithelial opacity of the cornea after excimer laser keratectomy has yet to be fully defined. The aim of this study was to evaluate the alterations of glycosaminoglycans (GAGs) after excimer laser keratectomy. METHODS: Rabbit corneas were harvested on days 5, 10, 20, and 30 after excimer laser photoablation. The amount of main disaccharide units was determined by high performance liquid chromatography (HPLC). In addition, immunohistochemical studies were performed on corneal sections 20 days after the ablation. RESULTS: The concentrations of DeltaDi-0S at 5 and 10 days were significantly lower than before the ablation. DeltaDi-6S showed a significant increase 5 days after the ablation but DeltaDi-4S did not show any significant change. There was a significant increase in DeltaDi-HA at 20 and 30 days after ablation. In immunohistochemistry, the positive staining for DeltaDi-6S and hyaluronic acid was observed in the subepithelial region. These immunohistochemical results were well correlated with the HPLC findings. CONCLUSIONS: The increase in chondroitin-6 sulphate and hyaluronic acid may be related to corneal subepithelial opacity after excimer laser keratectomy.

Animals↗
PubMed1999

[Long-term healing of excimer laser ablated rabbit corneas].

PURPOSE: To evaluate histologically and immunohistochemically long-term changes in rabbit cornea following excimer laser ablation. MATERIALS AND METHODS: Excimer laser keratectomy was performed on 12 eyes of 6 rabbits. The corneas were subjected to histological and immunohistochemical studies 2 and 3 years after treatment. FINDINGS: In all specimens, epithelial basement membrane of the ablated central cornea showed undulating and spike-pattern invasion into the epithelial side. The collagen lamellae showed irregularities in the subepithelial stroma. Immunohistochemically, the subepithelial stroma showed positive reaction to anti-type III collagen antibody. Staining for anti-IV collagen antibody showed a linear pattern in the epithelial basement membrane and was positive in the subepithelial stroma of the ablated central cornea. These positive reactions to anti-type III and type IV collagen antibodies in the stroma showed the localized presence of scar tissue in the ablated stroma. Antibody to type VII collagen showed weak reaction in the basement membrane, suggesting incomplete regeneration of anchoring fibrils. CONCLUSION: The healing process was still incomplete 3 years after excimer laser keratotomy in rabbits.

Animals↗
PubMed1999

[A confocal microscopic and histological study on rabbit corneas after photorefractive keratectomy for hyperopia].

PURPOSE: To evaluate changes in corneas after PRK (photorefractive keratectomy) for hyperopia. MATERIALS AND METHODS: Six rabbits were given PRK treatments for + 6.0 D of hyperopia. We observed these corneas by confocal microscopy at 3 days, 1 week, 2 weeks, 1 month, and 3 months after PRK, and examined them histologically. RESULTS: In the ablated area, proliferative changes in the subepithelial layer had already appeared three days after the operation. These changes progressed for one month, but had decreased at three months after operation. In confocal microscopy, the proliferative change in the subepithelial layer was observed as bright, highly refractive tissue interspersed with small spaces void of cells, and was especially evident at the wound edges of the peripheral side. The center of the cornea was slightly damaged by the excimer laser but proliferative changes were not observed there. CONCLUSION: The results of this study revealed that the damage to the center of the cornea caused by PRK for hyperopia was not very severe. But it is important to evaluate further the efficacy and safety of PRK for hyperopia.

Animals↗
PubMed1999

[The effect of neurotransmitters on rabbit cornea].

PURPOSE: To ascertain the effect of neurotransmitters added to the culture medium of rabbit corneal epithelium and stromal cells. METHOD: The corneal epithelium and stromal cells were cultured in RCGM medium. Three neurotransmitters were added to the medium : substance P, acetylcholine, and vasoactive-intestinal peptide (VIP). RESULTS: Proliferation of epithelial cells significantly increased after incubation for 24 hours with substance P (p < 0.05). There was no change in proliferation after addition of acetylcholine or VIP. The extension of epithelial cell layer increased after addition of substance P but not after addition of acetylcholine or VIP. No change was induced in proliferation of stromal cells or extension of the stromal cell layer after addition of any one of the three substances. CONCLUSION: Substance P stimulates the proliferation of corneal epithelial cells when added to the culture medium.

Acetylcholine↗
PubMed1999

[Corneal wound healing and immunohistological features of extracellular matrix following penetrating keratoplasty in rabbits].

PURPOSE: To analyze corneal wound healing after penetrating keratoplasty (PKP). MATERIALS AND METHODS: We performed PKP on 20 white rabbit eyes, and applied immunohistochemical techniques. The distribution of type I, III and IV collagens, large proteoglycan, chondroitin 6-sulfate, chondroitin 4-sulfate, and vimentin was determined at postoperative intervals of 3 days, 1 week, 2 weeks, 1 month and 3 months. RESULTS: By day 3, staining for type IV collagen was observed along the host-graft junction. By day 7, staining for type III collagen, large proteoglycan and chondroitin 6-sulfate had increased in the repair region, and then diminished with increasing postoperative time. Epithelial wound healing required more than one month, whereas the remodeling of Descemet's membrane did not terminate at 3 months after PKP. CONCLUSION: The data from this study suggest that type III collagen, large proteoglycan and chondroitin 6-sulfate play a crucial role in the corneal wound healing after PKP.

Animals↗
PubMed1999

[Effect of vitamin A palmitate on the synthesis of mucins in cultured conjunctiva].

PURPOSE: To evaluate the effect of vitamin A palmitate on the synthesis of mucins from goblet cells in cultured rabbit conjunctiva. METHODS: Palpebral conjunctiva was obtained from 12 white rabbits and was cultured in serum-free RCGM 2 which was developed for culture of rabbit corneal epithelial cells. This method eliminated retinol in the serum. High-performance liquid chromatography was used in quantitating N-acetylneuraminic acid contained in the sugar chain as an indicator of mucin content. RESULTS: Addition of vitamin A palmitate to the cultured medium resulted in significant increase in the amount of N-acetylneuraminic acid in the medium. CONCLUSIONS: The increase in N-acetylneuraminic acid in the cultured medium suggests that the increase of goblet cells in cultured conjunctiva is related to the synthesis of mucins due to vitamin A. RCGM 2 as a culture medium promises to be useful in evaluating the pharmacological activity of vitamin A. High-performance liquid chromatography facilitated quantitation of mucins in the culture medium.

Animals↗
PubMed1999

[Effect of vitamin A palmitate on vitamin A-deficient rabbits].

PURPOSE: We examined the effects of vitamin A palmitate (VA pal) eyedrops on the symptoms caused by vitamin A-deficiency in rabbits. METHODS: Three-week-old rabbits were raised on a vitamin A-deficient diet, and were examined for the quantity of retinol in the serum and the condition of the anterior segment of the eye. The vitamin A-deficient animals were treated with VA pal eyedrops. RESULTS: The retinol in the serum began to decrease seven months after the animals were placed on the vitamin A-deficient diet. After ten months, superficial punctate keratitis and the loss of conjunctival goblet cells were observed. Treatment of the disease in the anterior segment of the eyes with VA pal eyedrops resulted in restoration of normal condition within 3 weeks. The treatment increased the goblet cells in the ocular conjunctiva and the retinol in the serum. CONCLUSIONS: These results show the efficacy of topical VA pal treatment for vitamin A-deficient rabbits.

Animals↗
PubMed1999

[A pathological study on rabbit corneas after laser in situ keratomileusis].

PURPOSE: To investigate pathological changes in rabbit corneas after laser in situ keratomileusis (LASIK). MATERIALS AND METHODS: We performed LASIK on rabbit corneas to theoretically correct 10.0 diopters of myopia. The corneas were studied pathologically at day 0, and 3 days, 1 week, 3 weeks, 4 months, and 9 months after LASIK. RESULTS: At 3 days after LASIK, keratocytes in the ablated area changed morphologically into fibroblastic cells. And the structure of collagen fibers in the stroma was broken. These changes had disappeared almost entirely at 4 months after LASIK. There were no proliferative changes in the stroma of the ablated cornea 9 months after LASIK. No significant changes were observed in the endothelium. CONCLUSIONS: The damage to rabbit corneas induced by LASIK was mild to moderate under the present experimental conditions.

Animals↗
PubMed1998

Familial subepithelial corneal amyloidosis (gelatinous drop-like corneal dystrophy): exclusion of linkage to lactoferrin gene.

PURPOSE: Because corneal tissue with familial subepithelial corneal amyloidosis (FSCA; gelatinous drop-like dystrophy of the cornea) contains lactoferrin the possibility that the FSCA gene was the human lactoferrin (hLF) gene was investigated. Due to contradictory published information we also mapped the hLF gene. METHODS: We mapped the hLF gene using a genomic clone of the entire hLF gene as a probe by fluorescence in situ hybridization (FISH). Utilizing PCR primers that are specific to the hLF gene, we also mapped the hLF via radiation somatic cell hybrid analysis. Linkage of the FSCA gene to the hLF gene was evaluated by genetic linkage analysis using polymorphic markers within and in the vicinity of the hLF gene. RESULTS: The hLF gene mapped to the short arm of chromosome 3 at 3p21. Linkage analysis using polymorphic markers for hLF and haplotype analysis of the 3p21 loci indicates that the FSCA gene is not linked to the 3p21 locus. CONCLUSIONS: The gene for FSCA is not the hLF gene in these families.

Amyloidosis↗
PubMed1998

A new L527R mutation of the betaIGH3 gene in patients with lattice corneal dystrophy with deep stromal opacities.

Mutations in the betaIGH3 gene on chromosome 5q31 cause five distinct autosomal dominant corneal dystrophies: granular Groenouw type I, Reis-Bücklers', lattice type I and IIIA. and Avellino corneal dystrophies. We present here a new mutation of the betaIGH3 gene in patients with late-onset lattice corneal dystrophy manifest as a deep stromal opacity. To test the previously reported R124C, R124H, P501T, R555W, and R555Q mutations of the betaIGH3 gene, 30 patients and 11 normal relatives from 16 independently ascertained families with lattice corneal dystrophy, 49 patients and 12 normal relatives from 40 independently ascertained families with other corneal dystrophies, and 40 unrelated normal volunteers, were analyzed. A L527R (CTG/CGG) mutation of the betaIGH3 gene was found in 6 unrelated patients with lattice corneal dystrophy. A retrospective review of the patients' records showed that the opacities were deep in the stromal layer and of late onset. The mutation was a heterozygous single base-pair transversion from T to G of the second nucleotide position of codon 527. This caused the substitution of arginine for leucine. These six patients did not have mutations in codons 124, 501, or 555. The L527R mutation was not detected in the other corneal dystrophies or 40 normal volunteers. Although phenotypic variations in the size and shape of the deposits were found, all patients with the L527R mutation showed deposits deep in the stromal layer. We conclude that there are now at least six different mutations that have been detected in the betaIGH3 gene on chromosome 5q31 and that lead to corneal dystrophy.

Aged↗
PubMed1998

Surgery for abdominal aortic aneurysms associated with malignancy.

Of 148 patients treated for abdominal aortic aneurysms (AAA), 33 (22%) also had cancer. According to the classification of Szilagyi, there were 13 patients in group I, 19 in group II, and 1 in group IV. In group I, the mean interval between the cancer and AAA operations was 7 years (range 1-14 years). Aneurysmectomy was performed in 9 patients, wrapping in 2, and no operation in 2. In group II, a two-stage operation was performed in 8 patients, a single-stage operation in 4, only surgery for cancer in 4, and no operation in 3. Of 4 patients undergoing single-stage operations, 3 had colorectal cancer, and there were no postoperative complications such as graft infection or anastomotic breakdown. In group I, 6 of 13 patients died, but there were no cancer deaths. In group II, 9 of 19 patients died, 6 from progressive cancer. The group IV patient also died of cancer. These results suggest that if a patient can tolerate surgery for both diseases, a single-stage operation is preferable.

Abdominal Neoplasms↗
PubMed1998

Multihormone-producing islet cell tumor of the pancreas associated with somatostatin-immunoreactive amyloid: immunohistochemical and immunoelectron microscopic studies.

Pancreatic islet cell tumors, especially insulinomas, are often associated with amyloid deposition in the tumor tissue. Biochemical analysis has demonstrated that the amyloid protein from insulinoma is derived from islet amyloid polypeptide (or amylin) that is produced by tumor cells originating from beta cells of the islet of Langerhans. We examined a case of malignant pancreatic islet cell tumor with amyloid deposition in the tumor tissue using immunohistochemistry and double-labeling immunogold electron microscopy. The tumors were composed of cells producing multiple hormones, including somatostatin, gastrin, amylin, insulin, calcitonin gene-related polypeptide, and calcitonin. Amyloid deposits reacted with antisomatostatin antiserum but not with other antisera, including antiamylin. The present study demonstrated for the first time that amyloid associated with islet cell tumors is not always derived from amylin and can come from somatostatin.

Aged↗
PubMed1998

Does prolonged exercise alter diet-induced thermogenesis?

Diet-induced thermogenesis (DIT) is mainly an insulin-mediated response and the result of fat and glycogen synthesis. We investigated DIT at rest and after exercise to clarify the mechanism of exercise-induced changes in DIT in 6 healthy men (mean age 36 +/- 16 years). Subjects exercised for 1 h at 58% of maximal O2 consumption on a bicycle ergometer and then rested for 8 h sitting in a comfortable chair (exercise experiment). On a different day, subjects rested for 8 h without preceding exercising (non-exercise experiment). At 12.30 h, the subjects were given their second meal. DIT to individual meal did not differ significantly between the exercise and non-exercise days. Increased insulin sensitivity and increased free fatty acid oxidation by exercise may facilitate the conversion of glucose to glycogen in muscle. On the other hand, insulin secretion expressed as the ratio of plasma levels of insulin to glucose after the meal was significantly decreased in the exercise experiment (p < 0.05). Study of heart rate variability showed that sympathetic tone, a primary hormonal determinant of glucose metabolism during exercise, was increased and parasympathetic tone was decreased during the recovery period in the exercise experiment (p < 0.05). These findings suggest that changes in DIT are affected by many factors and may be related to the balance between these counteracting factors.

Adult↗
PubMed1998

[Inhibitory effects of matrix metalloproteinase inhibitor on corneal neovascularization].

We evaluated the inhibitory effects of matrix metalloproteinase inhibitor (MMPI) on corneal neovascularization in vivo. MMPI drops in the right eye and MMPI basic drops in the left eye were administrated six times per day after wearing a large polymethylmethacrylate-hard contact lens (PMMA-HCL) and intralamellar transplantation of a basic fibroblast growth factor (basic-FGF) containing polymer disk. We observed the status of corneal neovascularization with a slit lamp biomicroscopically after two weeks. Corneal buttons were also investigated histologically with light and electron microscopes. The findings of both investigations showed MMPI eye drops tended to inhibit the corneal neovascularization.

Animals↗
PubMed1998

Homozygotic patient with betaig-h3 gene mutation in granular dystrophy.

PURPOSE: This study investigated patients with granular dystrophy and identified a homozygotic patient and his family with a mutation in the betaig-h3 gene. METHODS: Genomic DNAs were extracted from leukocytes of the peripheral blood of the proband, his parents, and his grandmother. All had granular dystrophy. Genomic DNAs from 50 unrelated normal volunteers were used as controls. Exon 4 of betaig-h3 gene was amplified and analyzed by direct sequence. Clinical data were collected. RESULTS: A single-base-pair transition was detected. This was a substitution of G to A of the second nucleotide position of codon 124 in the betaig-h3 gene that led to a replacement of histidine for arginine (Arg124His, CGC-->CAC). This mutation was the precise one previously reported for Avellino dystrophy. Although the proband was homozygotic for the mutant alleles, his grandmother, and parents were heterozygotic for these alleles. No sequence modification in the codon 124 from 50 nonaffected control individuals was detected. Clinical findings of the proband were severe. Keratectomies were performed for both his eyes 5 times for a 24-year period. His grandmother and parents showed mild clinical symptoms, had a few annular granules in the subepithelial stroma, and maintained good visual acuities. CONCLUSION: Arg124His mutation of the betaig-h3 gene was found in a pedigree with granular dystrophy. This mutation was the precise one previously reported for Avellino dystrophy. This fact shows an existence of Avellino form in Japanese. Homozygotic patient for mutant gene showed severe symptoms and an early onset.

Adolescent↗
PubMed1998

[Trial of new intraocular lens power calculation following phototherapeutic keratectomy].

We reviewed the SRK-II method and introduce a new equation to calculate the intraocular lens (IOL) power for eyes which underwent laser phototherapeutic keratectomy (PTK). The Gullstrand series was used to determine the power and the radius of curvature of planoconvex IOLs which alter the focal point from the cornea to reach the conjugate point on the retina. The radius of anterior corneal curvature (R), axial length (AXL), predicted postoperative anterior chamber depth (ACD), and lens thickness (LT) were employed in the following formula to calculate the IOL refractive power: K = R/7.7, DC = 337. 5/R, VC = 1,000/DC*1.336 where VC is the posterior vertex focal length. A1 = -(VC-ACD), B1 = AXL-0.5* K-ACD-0. 103 LT, S = 1/A1 + 1/B1; this determined the diopter (D) of IOL in liquid to be (D) = 1,000/(1/S)* 1.336. In eyes which underwent PTK, the keratometric value prior to cataract surgery was not applied. Instead, R' defined as R-dT, where R is the radius of corneal curvature prior to PTK and dT the amount of corneal tissue removed, was introduced. Further, the corneal thickness before cataract surgery (CT') was defined as CT-dT where CT is the corneal thickness prior to PTK. Although it is important to select a lens that has an acurate predicted anterior chamber depth, the new equation appears to be more useful than the SRK-II formula.

Cataract Extraction↗