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Biomedical subjects

T Tanishima

Publications and source records attributed to T Tanishima.

At least 37 records · Page 2Linked to original sources
PubMed1984

Endothelial wound-healing of monkey cornea: fluorophotometric and specular microscopic studies.

The process of wound-healing in the corneal endothelium after transcorneal freezing was studied in the monkey, using the techniques of fluorophotometry, pachymetry and specular microscopy. After intramuscular injection of fluorescein, the dye exchange between the cornea and aqueous humor was studied by fluorophotometry and the results were analyzed on the basis of a two-compartment model: the transfer coefficient (kac) and the distribution ratio of the dye between the aqueous humor and the cornea (rac) were calculated, and the endothelial permeability coefficient (Kac) was computed using the thickness of the corneal stroma. The corneal thickness was measured at its center (CT) with a modified pachymeter. The endothelial cell morphometry was carried out at the central cornea using a wide-field contact-type specular microscope and a computerized image analyzer: the mean cell size (CS) was calculated. The values of Kac, kac, rac, CT and CS in 16 normal uninjured corneas were 3.35 +/- 0.91 X 10(-4) cm min-1, 0.56 +/- 0.15 hour-1, 0.60 +/- 0.17, 0.40 +/- 0.02 mm and 290 +/- 35 micron2, respectively (mean +/- SD). The values of Kac, CT and CS increased markedly after freezing and decreased gradually with passage of time. The Kac and CT recovered to normal level by the 6th and 4th week after freezing, respectively. The positive significant correlation was found between the values of Kac and CT (r = 0.84, P less than 0.001), and between those of kac and CT (r = 0.58, P less than 0.001). On the contrary, no significant correlation was found between Kac and CS. The CS did not recover completely and remained about 32% larger than the values of the normal eyes even 30 weeks after freezing. Transmission and scanning electron microscopy of the endothelium revealed that the junctional complexes were reformed soon after the endothelial cells had made contact with each other, and the complexes became almost normal about 4 weeks after freezing. Normalization of the junctional complexes appeared to coincide with recovery of the Kac and CT.

Animals↗
PubMed1983

[Cerebral vasospasm: comparison of contractile responses in isolated human and canine basilar arteries].

Differences between human and canine basilar arteries in contractile responses to various agents were studied in vitro. Human basilar arteries were obtained at postmortem. Serotonin or prostaglandin F2 alpha contracted greatly both human and canine basilar arteries. There was no difference between the two vessels in serotonin- or prostaglandin F2 alpha-induced contractions. In contrast, great differences were found between the two arteries in response to norepinephrine or hemoglobin. Human basilar arteries contracted markedly to norepinephrine while canine basilar arteries did not contract to norepinephrine. This data suggests that sympathetics might play a more important role in the genesis of vasospasm after subarachnoid hemorrhage than has been previously thought. Hemoglobin did not elicit a contraction in human basilar arteries whereas it produced marked contractions in canine basilar arteries. This result indicates that possible participation of hemoglobin as a causative agent in vasospasm could be ruled out. In view of these differences between human and canine cerebral arteries, the canine seems unsuitable for an experimental model of cerebral vasospasm.

Animals↗
PubMed1983

A fluorophotometric study of the barrier functions in the anterior segment of the eye after intracapsular cataract extraction.

The transfer coefficient of fluorescein across the corneal endothelium, kc.ac, was determined by a method of oral dye administration in 54 normal eyes. The kc.ac averaged 0.46 +/- 0.13 (SD) hour-1, and the fluorescein distribution ratio between the anterior chamber and the cornea, rac, was 0.57 +/- 0.20. There were no significant differences in these values between young subjects and those older than 50 years. A total of 56 eyes which underwent intracapsular cataract extraction were divided into three groups, 1) those operated on with routine medications, 2) with topical indomethacin and 3) with alpha-chymotrypsin of 7,500 times dilution. The value of rac was fixed at 0.57 and kc.ac was calculated taking the fraction, X, of unbound fluorescein in the aqueous into account. In addition, the apparent transfer coefficients of the dye between the blood and anterior chamber, k'in and k'out, were also calculated from the apparent fluorescein concentrations in the whole plasma and aqueous. The kc.ac was significantly greater in patients than in normal eyes, showing damage of the corneal endothelium by the surgery. The value of X was less than unity, indicating an increase in aqueous protein in the patients, but it was closer to unity in the indomethacin group than in other groups. The value of k'in was significantly less in the indomethacin group than in other groups. Between the groups with routine medication and with chymotrypsin, no significant difference was found in X or in k'in. It was concluded that topical indomethacin suppressed disruption of the blood-aqueous barrier and also that chymotrypsin at the present dilution did not cause serious disruption of the barrier.

Adult↗
PubMed1983

Wound-healing of corneal endothelium in monkey: an autoradiographic study.

The mitotic activity of the corneal endothelium during wound-healing was studied in 8 eyes of 5 cynomolgus monkeys. By transcorneal freezing, the endothelium was damaged at the corneal center over an area with a diameter of 2.5 mm. At various intervals, 3H-thymidine was injected into the anterior chamber and its incorporation into the endothelial cells was studied by autoradiography. On flat preparations of the endothelium, the total number of cells labeled with 3H-thymidine was counted on all specimens. The labeling of the cells occurred exclusively within the zone of about 2 mm from the center of the wound. The maximum labeling occurred 2 days after freezing and it decreased abruptly after 4 days, when endothelial covering of the central denuded area had been completed. No labeled cells were encountered after 30 days. The percentage of labeled cells to all cells present in a given area was computed and its regional distribution studied. On the second day after freezing, the maximum percentage of 12-19% was found in the center of the wound in one cornea and about 2 mm from the center in another cornea. On the third day, the maximum percentage of only 3-7% was found in the center and it decreased toward the periphery. It was thought that the number of labeled cells was too small to cover the damaged area by cell multiplication. It is suggested that the endothelial defect in the monkey cornea is covered mainly by migration of the adjacent cells.

Animals↗
PubMed1983

Influence of argon laser treatment of glaucoma on corneal endothelium.

The morphometric study of the corneal endothelium was carried out by means of specular microscopy prior to and for one year following laser trabeculoplasty (LTP) or laser iridotomy. A significant increase in the endothelial cell size was demonstrated in 6 months after trabeculoplasty and in 3 months following iridotomy. The magnitude of increase in cell size following laser iridotomy was significantly correlated with the amount of laser energy delivered to the eye. However, such correlation was not demonstrated following LTP where the applied energy was kept fairly constant among the present treated cases. The increase in cell size failed to correlate with clinical factors including IOP before and after laser therapy, age and the presence or absence of endothelial burn. The treatment protocols using reduced energy are indicated to minimize endothelial damage induced by LTP or laser iridotomy.

Adult↗
PubMed1982

Transmission and scanning electron microscopic studies on endothelial cells in macular corneal dystrophy.

Macular corneal dystrophy of both eyes in a 50-year-old man was studied by light microscopy and transmission and scanning electron microscopies. The endothelial cells contained empty vacuoles and numerous granules stained with alcian blue and periodic acid fuchsin. The endothelial cells were thin, especially at the guttata excrescences of the Descemet's membrane. Transmission electron microscopy revealed two types of vacuoles in the endothelium. The first type, which has been reported before, contained fine fibrillar material. The second type, described for the first time in this paper, was larger in size than the first type, and contained mostly amorphous material which appeared at the same electron density as the empty space of the anterior chamber, while a small amount of fibro-membranous materials were occasionally seen in the vacuoles. The second type of vacuoles sometimes appeared to be flattened. Cytoplasmic organelles of the endothelial cells and endothelial junctions were normal. Endothelial cells at the guttata excrescences were thin and contained only fine filaments. Slight depressions were observed on the endothelial surface facing the anterior chamber. Scanning electron microscopy of the endothelium showed an irregular surface which was composed of craters, nodules and pits. The cytoplasmic membrane of the endothelial cells at the top of the craters were continuous with that at the bottom of the craters. Marginal folds of the endothelial cells were obscure. Vacuoles of the first type were identical to those seen in the keratocytes of this disease. The second type of vacuoles and the guttata excrescences of the Descemet's membrane were thought to represent the craters and nodules on the endothelial surface.

Adult↗
PubMed1982

Permeability of the corneal endothelium to fluorescein--a follow-up of keratoplasty cases.

The permeability of the corneal graft endothelium to fluorescein was determined, by the oral administration method, in 47 eyes with penetrating keratoplasty. The endothelial permeability was expressed as the transfer coefficient of the dye between the anterior chamber and the cornea. In the early postoperative period, an increase in the aqueous protein was noted and a correction was made for fluorescein binding to aqueous protein. The measurements of the graft thickness and morphometry of the endothelial cells by specular microscopy were also carried out concurrently. The transfer coefficient was high in the early postoperative period, and was reduced by time. Similarly the graft was thick in the early postoperative period but it thinned to a normal level over a period of several months. A significant correlation was found between the transfer coefficient and the corneal thickness. The mean cell size of the graft endothelium was significantly greater than that of the normal cornea. The mean cell size and the postoperative period were correlated using the present data and those reported by Sato previously. A significant positive correlation was found, indicating progressive enlargement of the graft endothelial cells over a long period of time. The mean cell size was not significantly correlated with the transfer coefficient nor with the graft thickness.

Administration, Oral↗
PubMed1982

The corneal endothelial cells in ocular hypertension.

In order to evaluate the effect of the intraocular pressure (IOP) on the corneal endothelial cells, we investigated the endothelial cells of 37 untreated ocular hypertensive patients (72 eyes) and 40 normotensive individuals (65 eyes) by means of the contact type specular microscope, both groups being in the similar age range. The IOP was measured with a Goldmann applanation tonometer and the corneal thickness was determined with a pachymeter of Haag-Streit modified by Mishima & Hedbys. Endothelial photographs were taken in the central area of the cornea and the individual cell area was computed using a computerized image analyzer. The correlation among the IOP, the corneal thickness and the corneal endothelial cell size was analyzed. The mean cell size of corneal endothelial cells failed to be significantly correlated with either the IOP or the corneal thickness and did not show a significant difference between the right and left eyes in ocular hypertensive patients. The mean cell size of central corneal endothelial cells in ocular hypertensives was noted to be larger than that of the normotensives in each age group. The difference was of statistical significance in the subjects younger than 49 years old, and the mean difference in the cell size was the greatest in the patient group younger than 30 years old.

Adolescent↗