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Biomedical subjects

M Sawa

Publications and source records attributed to M Sawa.

At least 19 recordsLinked to original sources
PubMed1992

Cortical area related to lens accommodation in cat.

Lens accommodation was evoked by microstimulation in the lateral suprasylvian (LS) area in cats. The accommodative response was monitored continuously with an infrared optometer. The low threshold areas related to lens accommodation were located in the lower parts of the medial banks of the middle suprasylvian sulcus from A1 to A4, and also in the fundus of the sulcus at A8 in the stereotaxic coordinates. The latency of the onset of the accommodative responses evoked by stimulating the caudal area (A1-A4) was shorter than that evoked by stimulating the rostral area (around A8). Electrical stimulation was also attempted at the subcortical area in order to study the output pathway from the LS area. It was determined that the low threshold sites in the LS cortex of A1-A4 extend rostrally along the lateral ventricle in the brainstem, then ventrally into the midbrain. These findings suggest that there are two cortical areas related to lens accommodation: caudal and rostral, and the caudal accommodation area may provide the output signal for the subcortical system.

Accommodation, Ocular↗
PubMed1992

Keratoepithelioplasty in rat: development of a model and histological study.

A model for keratoepithelioplasty (KEP) was developed using the Lewis rat, and histological studies were performed using this model. The entire corneal epithelium was removed mechanically and a 1.5-mm width of the conjunctiva including the limbus was excised. An oval corneal lamellar graft (3 x 1.5 mm) with an intact epithelium taken from another Lewis rat was transplanted on the denuded limbus. Biomicroscopic observations showed much less vascular invasion in the part of the cornea adjacent to the lenticule than in other parts of the cornea, and the cornea remained clear adjacent to the lenticule. Histologically, a few vessels were observed in the corneal stroma under the lenticule. Epithelial cells on the lenticule specimens showed histological characteristics of the corneal epithelium. These findings indicate that one of the functions of KEP is to block neovascularization in the newly developing corneal epithelium by transplanting the lenticule between the corneal epithelium and conjunctival vessels. The present study also confirmed that this model is useful in the research of the pathophysiological mechanism of KEP.

Animals↗
PubMed1992

[Histological study of a model of keratoepithelioplasty in the rat].

A model for keratoepithelioplasty (KEP) was developed using the Lewis rat, and histological studies were performed using the model. The entire corneal epithelium was removed using a spatula and a 1.5-mm-width of the conjunctiva including the limbus was excised. An oval corneal lamellar graft (3 x 1.5 mm) with an intact epithelium taken from another Lewis rat was transplanted on the denuded limbus. Biomicroscopic observation showed significantly less vascular invasion in the part of the cornea adjacent to the lenticule than in other part of cornea, and clear cornea was maintained in the cornea adjacent to the lenticule. Histologically only few vessels were recognized in the lenticule, and the epithelial cells on the lenticule showed histological characteristics of corneal epithelium. These results indicate that surgical function of KEP can be obtained because the lenticules keep distance between corneal epithelium and conjunctival vessels. And it is also confirmed that this model is useful in research on the pathophysiological mechanism of KEP.

Animals↗
PubMed1992

[A case of peripheral corneal ulcer accompanied by progressive systemic sclerosis].

A 61-year-old woman with progressive systemic sclerosis developed bilateral peripheral corneal ulcer. The corneal lesions were resistant to daily systemic treatment with 15 mg steroid and 50 mg cyclophosphamide. Corneal perforation occurred in her right eye 11 months after the onset of Raynaud's phenomenon and 3 months after the scleritis. Lamellar keratoplasty accompanied with Brown's operation was performed on both eyes. Graft melt and cicatricial corneal opacity developed postoperatively. Removed conjunctival tissue was examined immunohistochemically. HLA-DR protein positive monocytes infiltrated subepithelial tissue, demonstrating that the inflammation of the lesions was in the active stage. Not only perforin but also suppressor/cytotoxic T cell positive reactions were observed, which revealed an involvement of the T cell immune system in the present case.

Corneal Ulcer↗
PubMed1992

[Aqueous protein concentration in diabetics. Report 5. Relationship between aqueous protein concentration and pathological findings of iridial vessels].

The relationship between aqueous protein concentration (APC) and pathological changes in the iridial blood vessels was investigated in 49 eyes of 45 diabetic patients who underwent cataract surgery. APC was measured with a laser flare-cell meter before surgery. The quantification analysis method (type I, multivariate analysis) revealed that the most relevant factor to APC was the existence of nephropathy followed by, in descending order, the degree of retinopathy and changes in iridial vessels as demonstrated by electron microscopy. When data were reanalyzed after exclusion of the iridial vessels were found to be strongly relevant to APC. These results suggest that breakdown of the blood-retinal barrier contributes to the APC increase in eyes with advanced diabetic retinopathy, and that changes in iridial vessels may mainly influence APC in non- and milder-retinopathy groups.

Aged↗
PubMed1992

[Corneal endothelial cell damage in penetrating keratoplasty].

Fifty-eight corneal grafts were investigated by specular microscopy to determine the corneal endothelial damage in penetrating keratoplasty. The center of the donor corneal endothelium was examined before and after 2 weeks, 1, 3, 6 and 12 months after surgery. The cell density decreased periodically during the observation period, and the endothelial cell loss in all the cases averaged 10. 4% at 2 weeks after the operation, 16.0% at 1 month, 33.0% at 3 months, 39.4% at 6 months, and 48. 2% at 12 months. However, the cell loss in the keratoconus subgroup averaged -1.9%, 1.2%, 9.9%, 30. 6%, and 33.4% corresponding to the above period. The least cell loss among the diagnostic subgroups was in the keratoconus, followed by corneal leukoma. The cell loss in bullous keratopathy was higher than in keratoconus and corneal leukoma case. It was concluded that the cell loss in penetrating keratoplasty during the first postoperative year depends on the primary disease.

Adolescent↗
PubMed1991

Severe corneal edema after prolonged use of psychotropic agents.

A 23-year-old woman with schizophrenia who had been treated with a high dose of psychotropic agents for 6 years had bilateral corneal edema and suffered from severe visual disturbance. No signs of inflammation, infection, congenital abnormality, or corneal endotheliitis were observed. The symptoms did not respond to either topical or systemic treatments. Reduction in the dosage of psychotropic agents resulted in quick and complete disappearance of the corneal edema within 2 weeks. Specular microscopic examination after recovery revealed a marked enlargement of corneal endothelial cells, but there was no evidence of any corneal dystrophy. Blood-aqueous barrier function was not deteriorated, as demonstrated by aqueous protein concentration measured with a laser flare-cell meter. In conclusion, we suggest that corneal edema may be caused by prolonged use of psychotropic agents, particularly a major tranquilizer.

Adult↗
PubMed1991

Corneal endothelial cell damage in penetrating keratoplasty.

Fifty-eight corneal grafts were examined by specular microscopy to determine the corneal endothelial cell damage following penetrating keratoplasty. The average postoperative follow-up period was 10.1 months. The cell density decreased continuously during the observation period, and the endothelial cell loss of the central area of the cornea in all the cases averaged 10.4% at two weeks after the surgery, 16.0% at one month, 33.0% at three months, 39.4% at six months, and 48.2% at one year. However, the cell loss in the keratoconus group averaged -1.9, 1.2, 9.9, 30.6 and 33.4% for the corresponding postoperative periods. The cell loss in the bullous keratopathy eyes showed higher values compared to those in the keratoconus and the corneal leukoma eyes. It was concluded that cell loss in penetrating keratoplasty during the first postoperative year depends on the host diseases.

Adolescent↗
PubMed1991

[The present status and the future of artificial liver support].

Orthotopic liver transplantation, started by Dr. Starzl in 1963, has already become an well established therapeutic method for the treatment of fulminant hepatic failure especially since the introduction of Cyclosporin A. On the other hand, hemoadsorption using charcoal, PAN membrane hemodialysis and plasma exchange were actively applied for clinical cases with fulminant hepatic failure between 1960 and 1970, but the survival rates were not so improved as expected due to the lack of metabolic functions. Hybrid artificial liver has been therefore investigated experimentally to support metabolic functions by using biomaterials such as isolated hepatocytes. Today many efforts are being made to keep hepatocytes highly viable for a long period of time by calcium alginate entrapment, spheroid formation, or by using biomatrix, some polymers, and microcarriers, etc. In the future, xeno-hepatocytes or so-called super cell will be realized and applied for artificial liver support with the development of gene operation techniques.

Artificial Organs↗
PubMed1990

New wound-healing model using cultured corneal endothelial cells. 1. Quantitative study of healing process.

A new in vitro model to evaluate the corneal endothelial wound-healing process was developed. Confluent monolayer cell sheets of either rabbit or bovine corneal endothelial cells were cultured on cover slips, the surface of which had been precoated with hydroxyethyl methacrylate (HEMA) except for the 8 mm-diameter area for cell culture. Wounds were made by scraping off cells in the center of the cell sheets using a rotating silicone tip. The areas of these wounds were measured by a method of computed planimetry. The average wound area was 3.00 +/- 0.21 mm2 in rabbit cell cultures and 3.18 +/- 0.28 mm2 in bovine. The healing process after the wounding was observed using an inverted phase contrast microscope and wound-healing rates (healed area per hour) were calculated. Wounded areas were recovered by 60 hours in rabbit experiments, and by 84 hours in bovine experiments. Wound-healing rates were different among the observation periods and showed differences between the two species. The healing rates in the rabbit were higher than those in the bovine in the early phase. This in vitro model can be used for quantitative evaluation of the wound-healing process of the corneal endothelium.

Animals↗
PubMed1990

New wound-healing model using cultured bovine corneal endothelial cells. 2. Role of migration and mitosis studied by immunohistochemistry.

The roles of migration and mitosis in the in vitro corneal endothelial wound-healing process were studied using an immunohistochemical method. The in vitro wound-healing model was a cultured cell sheet prepared using bovine corneal endothelium, and the wound was made at the center of the cell sheet using a rotating silicon tip. Following the wounding, specimens were incubated with bromodeoxyuridine (BrdU) for 12 hours. After the fixation with 10% phosphate-buffered formalin, the cells incorporating BrdU were stained by the avidin biotin peroxidase complex method. In 12 hours after the wounding, no stained cells were observed. In 24 hours, cell migration had started and a few cells were stained; the average number of stained cells was 14.6 +/- 4.0 cells/mm2. In 48 hours, the number of stained cells increased. The maximum number of stained cells was observed between 48 and 60 hours after the wounding. The number of stained cells decreased rapidly after 72 hours when the wound was almost closed. Stained cells were most numerous in the area within 0.8 mm of the wound edge throughout the wound-healing. The endothelial wound-healing process in this model could be divided into four phases, latent, migration, concurrence of migration and mitosis, and inhibition phases. This in vitro wound-healing model could simulate the wound-healing process in vivo and will be useful for a quantitative evaluation of drug effects on the corneal endothelial wound-healing.

Animals↗
PubMed1990

Clinical application of laser flare-cell meter.

Clinical application of the laser flare-cell meter was described. The instrument was developed for concurrent quantitative determinations of the flare and number of cells in the aqueous humor. Diurnal variations were demonstrated in the aqueous flare, and also an increase in the flare with increasing age. The effects of drugs on aqueous humor dynamics were also studied. Orally administered 500 mg of carbonic anhydrase inhibitor reduced the aqueous humor formation by one-third. Concurrent study with the laser flare-cell meter and slit-lamp microscopy in uveitis cases has revealed that the former instrument is superior to the latter in making a quantitative evaluation of inflammation in the anterior segment of the eye. A follow-up study of postoperative inflammation was performed in patients undergoing extracapsular cataract extraction with posterior chamber intraocular lens implantation. Cases with uneventful postoperative course showed intense flare on the first postoperative day followed by a rapid decrease. Cases with inflammation and fibrin had high aqueous flare which showed an increase even before detection of fibrin in the aqueous by slit-lamp microscopy. Topical 0.5% indomethacin treatment was shown to be effective in suppressing the postoperative increase in aqueous flare but had little effect on cell count. In cases undergoing Argon laser trabeculoplasty, the aqueous flare in the treated eyes was determined to be significantly higher than that in the fellow eyes for four weeks postoperatively (P less than 0.05). The laser flare-cell meter has made it possible to determine the flare and number of cells in the aqueous humor quantitatively. This capability differentiates the instrument from the slit-lamp microscope as well as the instruments previously developed for similar purposes. The laser flare-cell meter is a newly developed useful tool to investigate the pathophysiology of the eye.

Acetazolamide↗
PubMed1990

[Isotonic contraction of rabbit superior rectus muscle].

It is well known that the mammalian extraocular muscle has slow muscle fiber morphologically. But the contraction speed of slow muscle fiber has not been mentioned in previous reports. We studied the isotonic contraction of slow muscle fiber and compared it with fast muscle fiber. Each fiber bundle was isolated from the rabbit superior rectus muscle. Both light microscopic findings and the reaction to isotonic contraction in Ca2+ free Ringer's solution could identify each of the two muscle fiber types. Contraction speed depended on the frequency of stimuli (40-200 Hz) in both slow and fast muscle fiber. Maximum velocities of slow and fast fiber bundles were 4.3 +/- 1.53 mm/sec and 26.9 +/- 3.48mm/sec at 200Hz, respectively. It was suggested that the relaxation of slow muscle fiber did not interfere with the contraction of the fast muscle fiber. The relation between contraction velocity and afterload showed an approximately right angle hyperbolic curve.

Animals↗