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Biomedical subjects

T Otori

Publications and source records attributed to T Otori.

71 records · Page 4Linked to original sources
PubMed1970

Direct measurements of membrane unstirred layers.

1. The unstirred layer of fluid bounding the posterior surface of the rabbit cornea and contact lens has been directly measured using an optical apparatus.2. Small polystyrene latex spheres (< 0.25 mu diameter) were used as an indicator because of the excellent light-reflective properties; other indicators were used (e.g. carmine particles) and had a similar behaviour.3. With the bulk solution unstirred the layer was 350 mu thick on the cornea and 150 mu thick on the contact lens. Following vigorous stirring the layer was reduced to 65 mu on the cornea and < 20 mu on the contact lens.4. The present direct measurements of the unstirred layers thickness confirm previous indirect measurements.

Animals↗
PubMedDate not supplied

Detection of interleukin-1 beta in the tear fluid of patients with corneal disease with or without conjunctival involvement.

To investigate the role of Interleukin-1 (IL-1) in the pathobiology of the cornea, we measured IL-1 beta concentration in tear fluid samples from patients with corneal disease. Twenty patients with unilateral corneal disease were included in the study. Tear fluid samples were collected during the active stages of the disease and following resolution. The fellow (unaffected) eyes served as controls. The concentration of IL-1 beta in the tear fluid samples was measured using a sandwich ELISA method. IL-1 beta was detected in tear fluid from five eyes (three eyes with chemical burns, one with a Pseudomonas aeruginosa corneal ulcer, and one with a peripheral corneal ulcer) at concentrations between 29 and 218 pg/mL. IL-1 beta was not detected in tear fluid from the remaining 15 affected eyes, nor from the control eyes. The detection of IL-1 beta in tear fluid correlated with limbal conjunctival involvement, but did not correlate with the type of disease, size of epithelial defect, or degree of stromal involvement. IL-1 beta in the tear fluid may be one of the factors modifying the complex inflammatory process of the anterior ocular surface.

Adolescent↗
PubMedDate not supplied

Collagenolytic activity of keratocytes cultured in a collagen matrix.

To study the mechanism of collagen degradation by keratocytes, we developed the new in vitro model in which keratocytes were cultured three-dimensionally in a collagen matrix. Subcultured rabbit keratocytes were embedded in a type I collagen matrix and cultured in serum-free medium. Collagenolytic activity of the cells was determined by measuring the amount of hydroxyproline released into the medium from degraded collagen. Activities of collagenase in the medium were also measured, using collagen labeled with fluorescein isothiocyanate as a substrate. The presence of plasminogen was required for collagen degradation by keratocytes. In the presence of plasminogen, the amount of collagen degradation depended on both the cultivation period and the number of cells. The addition of interleukin-1 (IL-1) stimulated the collagen degradation in a dose-dependent manner. This stimulatory effect of IL-1 was completely inhibited by the addition of IL-1 receptor antagonist (IL-1ra). Collagenase activity in the medium was stimulated by the addition of IL-1, and IL-1ra antagonized this stimulatory effect. These findings indicate that our present model may be useful for investigating the mechanism of collagen degradation by keratocytes.

Animals↗
PubMedDate not supplied

The effect of corneal epithelial cells on the collagen gel contraction by keratocytes.

To understand the mechanism of the contraction of cicatricial tissues after corneal stromal wounding, we investigated the effect of corneal epithelial cells on the collagen gel contraction by keratocytes. Subcultured rabbit keratocytes were embedded in type I collagen gel and cultured. Rabbit corneal epithelial cells were cultured separately and the culture medium was collected and used as an epithelial cell-conditioned medium (ECCM). The collagen gel contraction by keratocytes was determined by measuring the diameters of the collagen disks once a day for 5 days. In the presence of fetal calf serum, the diameter of the collagen gel decreased in linear proportion to the number of keratocytes, but in inverse proportion to the concentration of collagen. The addition of the ECCM enhanced the collagen gel contraction by keratocytes in a dose-dependent manner. This stimulatory activity was found in the ECCM obtained from 3- to 7-day cultures of epithelial cells. These findings suggest that corneal epithelial cells secrete factor(s) that stimulate the collagen gel contraction by keratocytes.

Animals↗
PubMedDate not supplied

Delayed administration of JTP-2942, a novel thyrotropin-releasing hormone analogue, improves cerebral blood flow and metabolism in rat postischaemic brain.

1. The aim of the present study was to examine the central nervous system action of JTP-2942, a novel thyrotropin-releasing hormone (TRH) analogue, from the point of view of cerebral blood flow (CBF) and metabolism in the postischaemic brain. 2. Left middle cerebral artery ischaemia was induced for 90 min followed by reperfusion. 3. Animals were separated into four groups: (i) low-dose (0.003 mg/kg) JTP-2942; (ii) high-dose (0.03 mg/kg) JTP-2942; (iii) cystidine diphosphate choline (500 mg/kg); and (iv) saline. The test drug or saline was administered intravenously 1 week after ischaemia. 4. Local CBF and local cerebral glucose utilization were measured autoradiographically, adjacent sections were stained with haematoxylin-eosin and infarction size was measured. 5. JTP-2942 ameliorated the reduction of local CBF and glucose utilization except in the ischaemic core. In particular, the higher dose (0.03 mg/kg) of JTP-2942 significantly increased local CBF and glucose utilization not only in peri-infarcted areas, but also in distal and contralateral areas. 6. These results suggest that JTP-2942 treatment may be beneficial for improving cerebral circulation and metabolism in the postischaemic brain.

Animals↗
PubMedDate not supplied

Sodium and chloride transport across the isolated rabbit ciliary body.

Unidirectional Na+ and Cl- fluxes were determined in the isolated rabbit ciliary body under short-circuited conditions. A statistically significant net Cl- flux towards aqueous was detected in the standard bathing solution (HCO3- = 115 mM), but no net Na+ flux was demonstrated in this solution. The net Cl- flux exceeded the short-circuit current, suggesting the existence of a net flux of other ion(s). In a bathing solution containing 5 mM HCO3-, the net Cl- flux was abolished, suggesting that HCO3- in the bathing solution enhances the net Cl- flux.

Action Potentials↗