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Biomedical subjects

R Okamura

Publications and source records attributed to R Okamura.

At least 55 records · Page 3Linked to original sources
PubMed1989

Effect of cyclosporine on oxidative phosphorylation and adenylate energy charge of regenerating rat liver.

The effect of cyclosporin A (CyA) on regenerating liver was investigated in subtotal hepatectomized rats treated with CyA in terms of mitochondrial phosphorylative activity, hepatic energy charge, and serum bilirubin levels. In the CyA-treated hepatectomized group, the energy charge decreased from normal control value of 0.857 to 0.782 at 6 h after hepatectomy. The decreased energy charge, however, gradually increased and returned to 0.842 at 48 h after hepatectomy with no significant changes being observed between CyA-treated and untreated hepatectomized groups. Phosphorylation rate in the CyA-untreated group increased to 142% of the normal control at 24 h and then decreased to 114% at 48 h after hepatectomy. By contrast, phosphorylation rate in the CyA-treated group increased to 144% of the normal control at 24 h, but remained at the high value of 132% (P less than 0.01; compared to the CyA-untreated group) even at 48 h after hepatectomy. Serum total bilirubin levels in the CyA-treated group were significantly higher than those in the CyA-untreated group during all experimental periods. We conclude that CyA does not exert a direct detrimental effect on mitochondrial function and that, despite the marked hyperbilirubinemia induced by CyA, the mitochondrial phosphorylative activity increases adaptively to provide sufficient energy for enhanced ATP-utilizing reactions in an early process of liver regeneration.

Adenine Nucleotides↗
PubMed1989

Changes in blood ketone body ratio with reference to graft viability after liver transplantation in rats.

Arterial blood ketone body ratio (acetoacetate/3-hydroxybutyrate; KBR), which reflects hepatic mitochondrial redox potential, was measured during a 2-week period after orthotopic liver transplantation in three groups of rats: group 1, the isogenic combination of LEW (RT1l) graft to LEW recipient as control; group 2, the allogenic combination of ACI (RT1a) graft to LEW recipient without immunosuppressive treatment: and group 3, the allogenic combination of ACI to LEW with immunosuppressive treatment using cyclosoporin (CyA). Isogenic recipients survived indefinitely. Allogenic recipients in group 2 had severe rejection with a mean survival of 10.3 +/- 0.54 days, while 77.8% of the allogenic recipients in group 3 survived more than 30 days. KBR of rats surviving more than 2 weeks in groups 1 and 3 gradually increased post-transplantation and was maintained at a high level. By contrast, though KBR in group 2 was restored at 3 days, it gradually fell and remained at a significantly low level (P less than 0.001). It is suggested that KBR provides an accurate indicator for evaluating metabolic viability of the critically deteriorating liver graft accompanied by sever rejection.

Animals↗
PubMed1989

Immunological treatment with low dosage ciclosporin in rat liver allotransplantation.

Ciclosporin (CsA) was administered subcutaneously at a dose of 3 mg/kg body weight/day from the day of operation to 14 days of liver allotransplantation in ACI rat (RT1a) to LEW rat (RT1(l) strain combination. All LEW recipients of ACI liver transplants without immunosuppressive treatment had severe rejection and expired within 12 days. In contrast, 7 out of 9 recipients in the same strain combination with temporary CsA treatment survived indefinitely. Histologically, widespread cellular infiltration and massive hepatocyte necrosis were evident upon autopsy of the recipients without CsA treatment. In contrast, in the surviving rats of the CsA-treated group, mononuclear cell infiltration was restricted to the periportal field and hepatocytes appeared to be normal at 14 days posttransplant. CsA concentrations in whole blood were determined by high-performance liquid chromatography. The trough levels were 788 +/- 48, 621 +/- 76 and 546 +/- 52 ng/ml, at 5, 10 and 14 days posttransplant, respectively. We concluded that this relatively low-dose subcutaneous administration of CsA offered adequate immunosuppression in rat liver allotransplantation in this strain combination.

Animals↗
PubMed1989

Retrograde transneuronal labeling of premotor neurons of horizontal eye movement system in the cat using wheat germ agglutinin conjugated with horseradish peroxidase.

The retrograde transneuronal labeling of premotor neurons of the abducens nucleus was examined by wheat germ agglutinin conjugated with horseradish peroxidase (WGA-HRP) injections into the lateral rectus muscle in the cat. Native horseradish peroxidase injections into the lateral rectus muscle resulted in labeling of neurons in the ipsilateral abducens nucleus and accessory abducens nucleus only. By contrast, when WGA-HRP injections were made into the lateral rectus muscle, retrogradely labeled cells appeared in the mesencephalic central gray, the oculomotor complex, the pontine reticular nuclei, the medial and lateral vestibular nuclei, and the nucleus prepositus hypoglossi, in addition to strong labeling of cells in the ipsilateral abducens nucleus and the accessory abducens nucleus. These findings suggest that portions other than the abducens and the accessory abducens nuclei labeled by WGA-HRP injections into the lateral rectus muscle are transneuronally labeled. The same areas were also labeled by direct injection of a small amount of WGA-HRP into the abducens nucleus. The nonspecific retrograde transneuronal labeling is considered to be applicable to neuroanatomical analysis of origins of afferents to motor regions that innervate the extraocular muscles and consist of several small subdivisions or mixed motoneurons, where it is difficult for conventional tracer techniques to make successfully confined injections.

Abducens Nerve↗
PubMed1988

Quantitative study of characteristic aqueous humor transferrin, serum transferrin and desialized serum transferrin in aqueous humor.

Total transferrin (Tf) concentration and relative percentages of its subfractions, ie, characteristic aqueous humor Tf (Tfah), serum Tf (Tfs) and desialized serum Tf (Tau), in the aqueous humor of 30 patients were determined. According to the total Tf concentration, these patients were divided into the group with intact or mildly damaged blood aqueous barrier (BAB), consisting of cataract, glaucoma and central retinal artery occlusion patients, and the severely damaged BAB group, consisting of uveitis patients. In the intact or mildly damaged group, Tfah, Tfs and Tau revealed constant ratios of 60%, 26% and 14%; while in the severely damaged group, a relatively high concentration of Tfs was observed. There is only Tfs in the serum, therefore, theoretically, damage of the BAB should lead to an immediate increase of the relative concentration of Tfs in the aqueous humor. Because it did not occur until the BAB had been severely damaged, the possibility of an intraocular interchange of the 3 Tf subfractions is suggested.

Adolescent↗
PubMed1988

Mercury accumulation in lens following single administration of methylmercury.

Mercury levels in the lens, aqueous humor, blood and plasma after a single administration of methylmercuric chloride (MMC, 10 mg/kg or 20 mg/kg) were studied in Wistar rats. The animals were sacrificed on the 1st, 3rd, 7th, 14th, 21st and 180th days following administration. Mercury levels in each tissue after MMC 20 mg/kg treatment were higher than after 10 mg/kg treatment. Mercury levels in the blood, plasma and aqueous humor on the 1st day following administration were significantly high. On the other hand, the highest mercury level in the lens was shown on the 7th day after administration. Total concentration of the lens mercury on the 180th day was almost equal to that on the 21st day. These results suggested active accumulation of mercury takes place in the lens and that retention is at a high concentration for over half a year even after only a single administration.

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↗
PubMed1987

Pathogenic capacity of proteases from Serratia marcescens and Pseudomonas aeruginosa and their suppression by chicken egg white ovomacroglobulin.

The pathogenicities of three proteases from Serratia marcescens, two proteases from Pseudomonas aeruginosa, and one thermolysin from Bacillus stearothermophilus were examined. All proteases tested caused acute liquefactive necrosis of the cornea and descemetocele formation in guinea pig eyes after intrastromal injection, with the exception of the 60-kilodalton protease from S. marcescens, which produced only an opaque lesion. When injected into guinea pig skin, the protease also enhanced vascular permeability, which was followed by edema formation. The permeability-enhancing activity of the proteases increased in parallel with the concentration of the enzymes. When tested in vitro for its effect on these bacterial proteases, chicken egg white ovomacroglobulin (ovoM) inhibited the enzymatic activity of all the proteases after a short incubation period at an enzyme/inhibitor ratio (molar) of 1:1 to 1:4 or at a lower concentration after a longer incubation period. Such treatment of the proteases with chicken egg white ovoM before injection intrastromally into the eyes or intradermally into the clipped flanks of guinea pigs protected the cornea from destruction or completely prevented the permeability reaction and edema formation. No inhibitory effects of plasma protease inhibitors against these bacterial proteases were noted. Since the proteases are critical in the pathogenic processes caused by the bacteria, these results suggest a beneficial effect of ovoM against bacterial infections.

Animals↗
PubMed1987

Comparative study of native proteins in aqueous humor and serum--detection of characteristic aqueous humor proteins.

Native proteins in the aqueous humor and serum from 4 patients with cataract and 2 patients with central artery occlusion were studied using micro two-dimensional isoelectric focusing-gradient gel electrophoresis combined with silver staining. A total of 51 protein spots were detected in the aqueous humor and the standard map of distribution pattern of the native proteins was established. Transferrin, albumin, alpha 2-macroglobulin, ceruloplasmin, haptoglobin, IgA and IgG were identified by an enzyme immunoassay. As a whole, the protein pattern of the aqueous humor is comparable with the pattern of the serum, except for marked quantitative differences. Most aqueous humor components have their corresponding spots found in the serum. However, there are some spots detected only in the aqueous humor but not in the serum. These spots were identified as transferrin. It is already known that the tau fraction (a desialized form of transferrin, absent in serum) is found in an extra band in the electrophoretic patterns of cerebrospinal fluid and vitreous humor. Therefore, the samples were treated with neuraminidase to determine whether or not the different aqueous transferrin spots were the tau fraction. Serum transferrin and certain aqueous transferrin spots (corresponding to serum transferrin in electrophoretic position) were transformed to tau fraction after treatment. However, some other aqueous transferrin spots (tau fraction and unreported transferrin) remained unchanged. This indicated that, in the aqueous humor, there are three kinds of transferrin molecules: ordinary serum transferrin, tau fraction and characteristic aqueous humor transferrin. Soluble proteins in the extracts of ciliary processes, iris, vitreous humor, sensory retina and lens were also studied. The characteristic transferrin pattern seen in the aqueous humor was observed only in the vitreous humor. The ciliary processes and iris revealed an identical transferrin pattern as in the serum. alpha 2-Macroglobulin, that has been thought to be too large to pass the blood-aqueous barrier, was detected in all of the aqueous humor samples. Certain larger serum proteins were observed to have their corresponding spots in the aqueous, whereas certain smaller ones were not found. These findings strongly suggested that the aqueous humor proteins are not a simple ultrafiltrate of the serum. Active transport and/or local synthesis of proteins may play important roles in determining the constitution of the proteins in the aqueous humor.

Adult↗
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↗