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Biomedical subjects

R Kodama

Publications and source records attributed to R Kodama.

At least 91 records · Page 5Linked to original sources
PubMed1988

The expression of melanosomal matrix protein in the transdifferentiation of pigmented epithelial cells into lens cells.

A monoclonal antibody (MC/1) was constructed against melanosomes purified from the chicken pigmented epithelial cells (PECs) in order to characterize the differentiative phenotypes of PEC in the process of transdifferentiation into lens cells. Immunofluorescent studies revealed that MC/1 antibody specifically stains both retinal PECs in the eye and melanocytes in the skin, of chicken embryos. Immunoelectron microscopy showed that the antigen molecules are located on the peripheral region of the melanosomal matrix. A single protein band with an apparent molecular weight of 115,000 was labelled by MC/1 in Western blotting. The 115 kDa polypeptide identified by MC/1 is considered to be a member of the melanosomal matrix proteins. The maintenance of specificity of pigment cell nature is followed in the system of transdifferentiation of PEC into lens in vitro, utilizing 115 kDa protein as a marker. In the dedifferentiated PECs, this protein was undetectable.

Animals↗
PubMed1987

Density dependent growth of corneal endothelial cells cultured in vitro.

Using the cornea of macaque monkey, we demonstrated the relationship between cell density and growth of endothelial cells in vitro. Corneal endothelial cells in a cell sheet grow most actively in regions with cell density of 1000 to 1800 cells/mm2, in explant cultures and cell sheets and in concentrated inocula dissociated cells. Cell morphology was well sustained in these cultures. Cells cultured at a higher cell density retained their potential to proliferate actively, showing clear contrast to cells cultured at a density lower than 200 cells/mm2. When dissociated cells were cultured at a low density and maintained for more than 4 weeks, they gradually lost their growth potential, altered into polymorphonuclear giant cells and eventually dedifferentiated. In addition, cells with no contact with each other did not express growth potential. Density dependent growth was confirmed by measuring the mitotic index against the cell density per square mm from the center to the peripheral regions in cultured explants. It is concluded that the growth pattern of corneal endothelial cells is closely related to cell density, and that growth of these cells might be regulated through intercellular communications.

Animals↗
PubMed1986

In vitro system of corneal endothelium.

A method for preparation of highly ordered monolayer cultures of the corneal endothelium was described. The technique of agar and palladium double-coating of culture plates was utilized for demarcation of the haptotactic area. The culture plate was prepared by precoating with agar and subsequent coating with palladium to define areas where growth of corneal endothelial cells was allowed. A micro-mass culture of corneal endothelial cells on the area defined by the palladium coating demonstrated their active growth and their reconstitution of the typical cellular pattern of the corneal endothelium.

Animals↗
PubMed1984

Cell behaviour in a polygonal cell sheet.

Cell monolayers on culture dishes were divided into two groups: tensile monolayers and non-tensile ones. In the development of an epithelium, a non-tensile cell monolayer turns into a tightly bound tensile one. Detection of these states was carried out by using the boundary shortening procedure, a computer-based geometrical method to show how much the polygonal cell boundary contracts. Non-tensile monolayers were divided further into two groups according to their motility: a fluctuating monolayer in which cells move laterally, and a stable monolayer in which cells are immobilized. Quantitative determination of cell motility was performed by analysing time-lapse cellular patterns. These computer-based geometrical analyses enabled us to divide monolayers into three groups: tensile stable monolayers, non-tensile stable monolayers and fluctuating monolayers, and this study therefore gives an insight into the way in which changing conformations of cells may be assayed.

Animals↗
PubMed1982

Microenvironments controlling the transdifferentiation of vertebrate pigmented epithelial cells in in vitro culture.

The transdifferentiation of pigmented epithelial cells in vitro is briefly introduced. Several environmental conditions regulating the process have been demonstrated experimentally. On the basis of these data we have suggested regulatory factors in relation to the mechanisms for the initiation of the transdifferentiation of pigmented epithelial cells, focussing particularly on cell surface functions. Finally, we have presented data which contributes to the establishment of a useful and powerful cell culture system which makes it possible for us to analyse the molecular basis of transdifferentiation.

Animals↗
PubMed1981

Demonstration of contractility of circumferential actin bundles and its morphogenetic significance in pigmented epithelium in vitro and in vivo.

Each pigmented epithelial cell bears circumferential actin bundles at its apical level when the pigmented epithelium is established in eyes in situ or in culture in vitro. Well-differentiated pigmented epithelia in culture were treated with a 50% glycerol solution containing 0.1 M KCl, 5 mM EDTA, and 10 mM sodium phosphate buffer, pH 7.2, for 24 h or more at 4 degrees C. When the glycerinated epithelium was transferred to the ATP solution, each cell constituting the epithelium began to contract. The epithelium was cleaved into many cell groups as a result of contraction of each cell. The periphery of each cell group was lifted to form a cup or vesicle and eventually detached from the substratum. However, those cells that had not adhered tightly and not formed a monolayer epithelium with typical polygonal cellular pattern contracted independently as observed in the glycerinated fibroblasts. Contraction of the glycerinated pigmented epithelial cells was inhibited by N-ethylmaleimide but not by cytochalasin B. ITP and UTP also effected the contraction of the glycerinated cells, but GTP and ADP did not. Ca2+ was not required. This contractile model of pigmented epithelium provides a useful experimental system for analyzing the function of actin in cellular morphogenesis.

Actins↗
PubMed1976

Studies on the metabolism of d-limonene (p-mentha-1,8-diene). IV. Isolation and characterization of new metabolites and species differences in metabolism.

1. The main route of elimination of d-limonene administered orally was via the urine in animals and man, 75-95% of the administered radioactivity being excreted in the urine during 2-3 days. Faecal excretion accounted for less than 10% of the dose in animals during 2-3 days. 2. In addition to six metabolites, namely p-mentha-1,8-dien-10-ol (M-I), p-menth-1-ene-8,9-diol (M-II), perillic acid (M-III), perillic acid-8,9-diol (M-IV), p-mentha-1,8-dien-10-yl-beta-D-glucopyranosiduronic acid (M-V) and 8-hydroxy-p-meth-1-en-9-yl-beta-D-glucopyranosiduronic acid (M-VI) isolated from rabbit urine previously (Kodama et al., 1974), five new metabolites have been isolated from dog and rat urine, and which were characterized as 2-hydroxy-p-menth-8-en-7-oic acid (M-VII), perillylglycine (M-VIII), perillyl-beta-D-glucopyranosiduronic acid (M-IX), p-mentha-1,8-dien-6-ol (M-X) and probably p-menth-1-ene-6,8,9-triol (M-XI). 3. The major metabolite of d-limonene in the urine was M-IV in rat and rabbit, M-IX in hamster, M-II in dog and M-VI in guinea pig and man.

Animals↗
PubMed1975

Metabolism of 1-(3-trifluoromethylphenyl)-3-(2-hydroxyethyl) quinazoline-2,4(1H,3H)-dione (H-88). I. Species differences in metabolism.

1. Following oral administration of [14C] H-88 to rat, mouse, quinea-pig and hamster, 40-65% and 5-15% of radioactivity was excreted in urine and faeces respectively during 3 or 4 days. In rabbit, monkey and man, more than 80% of radioactivity was excreted in urine during 2 or 3 days, and faecal excretion was negligible. 2. Rabbit, rat or guinea-pig excreted non-labelled H-88 in urine as unchanged H-88 (M-I), 1-(3-trifluoromethylphenyl) quinazoline-2,4(1H,3H)-dione-3-acetic acid (M-II), H-88 glucuronide (M-III) and 1-(3-trifluoromethylphenyl)-3-(2-hydroxyethyl)-6-hydroxyguinazoline-2,4(1H,3H)-dione (M-IV). 3. The carboxylic acid (M-II) was the major metabolite of H-88 in rat, mouse, guinea-pig and hamster urine and faeces, while the major metabolite in urine of rabbit, monkey and man was H-88 glucuronide (M-III). The 6-hydroxy compound (M-IV) was a major metabolite only in guinea-pig.

Administration, Oral↗
PubMed1975

Metabolism of 1-(3-trifluoromethylphenyl)-3-(2-hydroxyethyl)quinazoline-2,4(1H,3H)-dione (H-88). II. Abosorption, distribution and excretion in rat, mouse, rabbit, monkey and man.

1. The maximum concentration radioactivity in blood occurred 2-4 h after oral administration of [14C]H-88 in mouse, rabbit and man. With rat, a maximum concentration was obtained 24 h after administration of the drug at a dose level of 60 mg/kg, but only 4 h at a dose of 6 mg/kg. Unchanged H-88 comprised about 50% of serum radioactivity in rat and mouse during the first few hours, but only a small proportion of the serum radioactivity in rabbit and man. 2. The distribution pattern of the radioactivity in rat given the drug at two dose levels was similar, and this differed slightly from mouse and considerably from rabbit. Autoradiograms in rat and rabbit confirmed the findings from the distribution studies, and the autoradiographic distribution pattern in monkey was similar to that in rabbit. 3. Of the administered radioactivity 25-30% was recovered from bile within 48 h in bile-duct-cannulated rats and rabbits. Excretion of radioactivity in respiratory CO2 was negligible in the rat.

Administration, Oral↗