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Biomedical subjects

M Okuda

Publications and source records attributed to M Okuda.

At least 19 recordsLinked to original sources
PubMed1992

Expression of haptoglobin receptors in human hepatoma cells.

The uptake of radio-labeled hemoglobin-haptoglobin complex (Hb-Hp) by human hepatoma PLC/PRF/5 and HepG2 cells was investigated in an attempt to characterize the uptake process and intracellular transport. Human hepatoma cells took up Hb-Hp in a receptor-mediated manner. Scatchard analysis of binding revealed that PLC/PRF/5 and HepG2 cells exhibited about 21,000 and 63,000 haptoglobin receptors/cell, with a dissociation constant (Kd) of 8.0 and 17 nM, respectively. Human hepatocytes in primary culture also expressed about 84,000 receptors/cells, with a Kd of 7.4 nM. The hemoglobin-haptoglobin complex was internalized and subsequently the internalized Hb-Hp was slowly degraded in the cells. Preincubation of the cells with Hb-Hp resulted in a decrease in binding of the radioactive Hb-Hp to the cell surface, and was accompanied with an accumulation of intracellular receptors. The uptake of Hb-Hp by the cells was not inhibited by 100 microM chloroquine or by 10 mM methylamine, but was inhibited by 50 microM monodansylcadaverine. Hemoglobin-heme taken up by the cells induced microsomal heme oxygenase. Thus, human hepatoma PLC/PRF/5 and HepG2 cells can take up Hb-Hp by haptoglobin receptor-mediated endocytosis and Hb-Hp probably causes translocation of the haptoglobin receptors from the cell surface to the cell interior where they can be degraded. The internalized heme-moiety of hemoglobin can regulate the expression of heme oxygenase.

Biological Transport↗
PubMed1992

Effects of secretin on bile production in two kinds of cholestatic models by choledocho-caval fistula and bile duct ligation in rats.

Secretin is known to stimulate bile flow from the bile duct epithelium. To investigate the effects of secretin in cholestasis, we studied the response of the bile flow and the excretion of biliary components to secretin using two cholestatic models with or without damage to the bile duct epithelium. The model without bile duct epithelial damage was a choledocho-caval (CC) fistula over a 24-hour period, and the model with bile duct damage was a bile duct ligation over a 48-hour period. Secretin was administered by intravenous infusion for 30 minutes and bile was collected for 120 minutes. Controls were given saline similarly. The bile flow and biliary bicarbonate excretion rate were significantly increased after secretin infusion in the CC fistula rats when compared with the control rats, but no stimulation by secretin was observed in the ligated rats. These data indicate that secretin-induced bile production was enhanced under cholestatic conditions with no bile duct epithelial disturbance.

Animals↗
PubMed1992

Glutathione and ischemia-reperfusion injury in the perfused rat liver.

Using the isolated perfused rat liver, we investigated the relationship of glutathione (GSH) with reactive oxygen species (ROS) generation and liver cell damage during ischemia/reperfusion in normal and GSH-depleted conditions. Lucigenin-enhanced chemiluminescence was used as a sensitive index of tissue ROS generation. After 30 minutes of equilibration, livers were subjected to global ischemia for various times (60 or 90 minutes) and then reperfused for another 120 minutes. Intracellular ROS levels increased sharply at the onset of reperfusion and then declined slowly. After 30 to 60 minutes of reperfusion, ROS levels started to increase progressively in a linear fashion. However, sinusoidal glutathione disulfide release did not increase during reperfusion in the same livers, suggesting that intracellular ROS generation is too low to cause a significant increase in GSH oxidation. Pretreatment with phorone (300 mg/kg intrapentoneally [ip]), which reduced hepatic GSH by 90%, did not cause any difference in intracellular ROS generation compared with the control livers. There were also no significant differences in lactate dehydrogenase and thiobarbituric acid reactive substances (TBARS) release between the control and phorone-treated livers during reperfusion after various times of ischemia. These data indicate that ROS generation in the normal isolated perfused liver during ischemia/reperfusion is extremely low and intracellular GSH does not serve as a major intracellular defense system against such a low oxidative stress.

Acridines↗
PubMed1992

Allergic contact dermatitis releases soluble factors that stimulate melanogenesis through activation of protein kinase C-related signal-transduction pathway.

Phenylazo-naphthol (PAN) allergy induces visibly well-defined and late-appearing hyperpigmentation of brownish yellow guinea pig skin in clear contrast to dinitrochlorobenzene (DNCB) allergy, which has very low incidence of hyperpigmentation. Skin extract from PAN allergy at 20-29 d post-challenge exhibited marked melanogenic stimulatory effects (3H2O release and 14C-thiouracil incorporation) when added to cultured guinea pig melanocytes. The time course in the appearance of melanogenic factor was definitely consistent with the induction pattern of visible pigmentation. By contrast, the addition of DNCB-challenged skin extract demonstrated no significant stimulating effect on melanogenesis in either assay system on any of the post-challenge days tested. Assay of intracellular inositol 1,4,5-trisphosphate formed through incubation with the melanocytes demonstrated that the PAN-allergy skin extract at day 28, which contains definite melanogenic factors, stimulated the formation of inositol 1,4,5-trisphosphate that occurs around 50 seconds in contrast to no or little increase with extracts obtained at days 0 and 1 post-challenge. Gel chromatographic analysis revealed that the PAN-allergy skin extract at day 28 contained a newly generated melanogenic fraction with a molecular weight of approximately 9000 Da which was also capable of stimulating DNA synthesis and activating the signal-transduction process (inositol trisphosphate formation) when added to guinea pig melanocytes. Both stimulations of melanogenesis and DNA synthesis by the 9000 Da fraction were completely abolished by the prior and simultaneous addition of protein kinase C (PKC) inhibitor (H-7) or its down-regulatory agent, phorbol 12,13-dibutyrate (PdBu). Taken together, these results suggest that PAN allergy provides a new mechanism of hypermelanization in which endogenous factors synthesized within skin induce the activation of signal-transduction pathways such as phosphoinositide turnover through ligands-receptor binding, resulting in the stimulation of melanocytes possibly through the activation of PKC.

Animals↗
PubMed1992

Flow cytometric analysis of intraepithelial lymphocytes in the human nasal mucosa.

Recently, much research has been carried out on phenotypes and the function of intraepithelial lymphocytes of the intestines. However, only few studies have been made of nasal intraepithelial lymphocytes (nIEL), and the results have been controversial. We examined the population of different subsets of the human nIEL by means of 2-color flow cytometry after culturing lymphocytes isolated from the inferior turbinates of hypertrophic rhinitis in incubation media with monoclonal antibody against CD3. As a result, CD8+ cells (suppressor/cytotoxic T cells) and double negative T cells (CD8- CD4- T cells) were the most predominant. The CD4+ cells (helper/inducer T cells) to CD8+ cells ratio was 0.6. Cytotoxic T cells predominated over suppressor T cells in CD8+ cells and helper T cells predominated over inducer T cells in CD4+ cells. Double positive T cells (CD8+CD4+ T cells) were nil and natural killer cells and CD8+ killer cells few. CD8+ cells and CD4+ cells were activated during cell culture. alpha beta receptor bearing T cells predominated over gamma delta receptor bearing T cells in CD8+ cells and CD4+ cells but gamma delta receptor bearing T cells predominated over alpha beta receptor bearing T cells in double negative T cells. To investigate the effect of cell culture on the population of each phenotype of nIEL we also examined peripheral blood lymphocytes by flow cytometry before and after culture, and found that activated T cells markedly increased and suppressor T cells, gamma delta bearing T cells and natural killer cells slightly decreased.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Analysis of lymphoid follicles in liver of patients with chronic hepatitis C.

Using immunohistological methods, we studied the lymphoid follicles in liver biopsy specimens obtained from patients with chronic hepatitis C(CH-C) to determine whether they represented an autoimmune manifestation. In 84 specimens obtained by liver biopsy from 76 patients positive for C-100 antibody, we assessed the presence or absence of lymphoid follicles within the portal areas, and then compared the clinical and immunohistological profiles of the two groups defined on this basis. There were no significant differences in the serological and clinical profiles of the two groups, but the T4:T8 cell ratio within the portal areas differed significantly. A T4:T8 cell ratio > 1.0 was more common in the specimens containing lymphoid follicles. This finding resembled the distribution of T cell subpopulations in the portal areas of patients with autoimmune hepatitis, and suggested that lymphoid follicles may be worth investigating to elucidate the relationship between chronic hepatitis C and autoimmune hepatitis.

Autoimmune Diseases↗
PubMed1992

Comparison of the effect of a mitochondrial uncoupler, 2,4-dinitrophenol and adrenaline on oxygen radical production in the isolated perfused rat liver.

Using the isolated perfused rat liver, we examined the effect of stimulation of mitochondrial respiration by 2,4-dinitrophenol (2,4-DNP) and adrenaline on reactive oxygen species (ROS) production, liver damage and lipid peroxidation. ROS production was monitored by luminol- and lucigenin-enhanced chemiluminescence and oxygen uptake was measured simultaneously. Liver damage and lipid peroxidation were evaluated by measuring hepatic lactate dehydrogenase (LDH) and thiobarbituric acid reacting substances (TBARS) release. Tissue ROS level decreased and oxygen uptake increased soon after 2,4-DNP infusion. On termination of 2,4-DNP infusion, there was a sharp increase in lucigenin-enhanced chemiluminescence, which declined slowly, but luminol-enhanced chemiluminescence did not change prominently. Hepatic LDH and TBARS release increased gradually during 2,4-DNP infusion and were manifested by termination of the infusion. Allopurinol did not affect ROS production and TBARS release, but delayed increases in LDH release after termination of 2,4-DNP infusion. Adrenaline, which stimulates mitochondrial respiration without uncoupling caused similar but smaller ROS changes observed in 2,4-DNP. LDH and TBARS release were not affected significantly by adrenaline infusion. These results indicate that uncoupling of oxidative phosphorylation decreases ROS production and restoration of oxidative phosphorylation enhances ROS production and liver damage. Xanthine oxidase is unlikely to contribute to enhanced ROS production after termination of 2,4-DNP but has some protective effect during uncoupling.

2,4-Dinitrophenol↗
PubMed1992

Mechanism of nasal secretion mediated via nerve reflex in guinea pigs and evaluation of antiallergic drugs.

In order to confirm the mechanism of nasal secretion mediated via a nerve reflex in guinea pigs, the secretory response from the contralateral side was studied which was induced by local application of various stimulators. There was no difference in the nasal secretion between the contralateral and the stimulated sides when the secretion was induced by allergen, histamine, and capsaicin at lower doses. Methacholine caused a nasal secretion only on the stimulated side. Pretreatment with local anesthetic and ganglionic blockers blocked the secretory response bilaterally which was induced by allergen, histamine, and capsaicin. Antihistaminics also blocked the secretory response induced by allergen and histamine on both sides, but not the capsaicin-induced nasal secretion. Unilateral pretreatment with local anticholinergics prevented all secretory responses only on the stimulated side. Thus, exogenous and endogenous histamine released by the allergen-antibody reaction may stimulate histamine H1 receptors located in the sensory nerve endings as trigger, resulting in the secretory response mediated via a nerve reflex, while methacholine may act directly on nasal glands. Ketotifen and azelastine, which are chemical mediators releasing inhibitor with antihistaminergic activity, prevented the nasal secretion induced by histamine and allergen. On the other hand, disodium cromoglycate, amlexanox, and tranilast had only a slight effect on the allergen-induced nasal secretion. The secretory response on the contralateral side induced by various stimulators would be useful in the in vivo evaluation of anti-allergic drugs to demonstrate the difference in their modes of action.

Allergens↗
PubMed1992

Inhibition of apical membrane enzyme activities and protein synthesis by gentamicin in a kidney epithelial cell line LLC-PK1.

The mechanism of a gentamicin-induced decrease in apical membrane enzyme activities was investigated in LLC-PK1 cells. Increasing activities of apical membrane enzymes (alkaline phosphatase, aminopeptidase, and gamma-glutamyltransferase) were markedly suppressed by gentamicin during growth in culture. On the other hand, a lesser effect was observed when the activities of these enzymes were decreasing or relatively constant. Gentamicin treatment decreased the maximal enzyme activities of alkaline phosphatase and aminopeptidase, indicating that the number of active enzyme molecules in the apical membrane was decreased by gentamicin. [3H]Leucine incorporation in LLC-PK1 cells was inhibited by gentamicin in a dose-dependent manner, followed by a reduction of total protein. In addition, a well-known protein synthesis inhibitor, cycloheximide, also decreased the apical enzyme activities. These results suggest that the inhibition of protein synthesis by gentamicin is a possible cause of the decreased activities of apical membrane enzymes in LLC-PK1 cells. The inhibition of protein synthesis may be related to the nephrotoxicity induced by aminoglycoside antibiotics.

Animals↗
PubMed1992

The microvasculature of the human bone marrow correlated with the distribution of hematopoietic cells. A computer-assisted three-dimensional reconstruction study.

Surgical specimens of ordinary bone marrow from eight patients were submitted to computer-assisted three-dimensional reconstruction from resin-embedded, semi-thin serial sections. This was undertaken with the aim of contributing to a better understanding of hematopoietic microenvironment by establishing the basic architecture of the bone marrow, particularly the microvasculature and its relation to the hematopoietic cell series. The basic vascular structure was found to consist of mutually intertwining sinuses and hematopoietic cords (or compartments), the latter with an arteriole running along the axis. This allowed to define the unitary structure of the bone marrow as a hematopoietic cord with a central arteriole and surrounded by sinuses. Here granulopoietic cells were distributed mostly along the wall of the central arteriole. Erythropoietic cells, located mainly around the sinus wall, proved to be forming a continuous network of cord instead of separate "islands" as usually assumed, justifying a designation of "erythroblastic cords". Megakaryocytes were positioned in close vicinity to the sinus wall. These findings appear not only to be helpful in analyzing factors involved in the in vivo hematopoiesis of man, but also to visualize the importance of structural studies of bone marrow.

Adult↗
PubMed1992

Phorbol myristate acetate-induced lung injury: involvement of reactive oxygen species.

Using lucigenin-enhanced chemiluminescence, isolated rat lungs perfused with physiological salt-Ficoll solution were studied to test whether phorbol myristate acetate (PMA)-induced lung injury was mediated by reactive oxygen species (ROS). PMA (0.03 micrograms ml-1) caused small but significant increases in lung ROS levels and pulmonary arterial perfusion pressure (Ppa) but did not induce lung oedema. PMA (0.15 micrograms ml-1) induced lung oedema with large increases in ROS production and Ppa. Superoxide dismutase (SOD) inhibited the increases in ROS, Ppa, and lung oedema. Catalase and dimethylthiourea inhibited lung oedema but did not attenuate the increases in ROS and Ppa entirely. Indomethacin attenuated lung oedema partially but did not inhibit the increases in ROS and Ppa. These data indicate that PMA-induced lung injury is dependent on PMA concentration and ROS are responsible for such lung injury. Thromboxane plays a minor role for PMA-induced lung injury. The different effects of oxygen radical scavengers suggest that different radical species contribute to the increased pulmonary vascular response and lung injury.

Acridines↗
PubMed1992

[Detection of Epstein-Barr virus DNA in salivary gland tumors].

To evaluate the relations between salivary gland tumors and Epstein-Barr virus (EBV), the levels of EBV-related antibodies were examined, and detection of EBV nuclear antigen (EBNA) and EBVDNA in tumor tissue was attempted by the anti-complement immunofluorescence technique and polymerase chain reaction, respectively. The mean VCA-IgG antibody level was increased to 925 (80-2560) in Warthin's tumor, 496 (40-2560) in mucoepidermoid tumor, and 206 (40-640) in pleomorphic adenoma. The positive rate of EA-IgG was high in Warthin's and mucoepidermoid tumors. VCA-IgA antibody was positive in 2 of the 7 cases of Warthin's tumor. EA-IgA antibody was negative in all cases. EBVDNA was detected in 7 of the 7 cases of Warthin's tumor, 3 of the 5 cases of mucoepidermoid tumor, and 2 of the 26 cases of pleomorphic adenoma. A relationship between Warthin's tumor and EBV was suggested by the 100% detection rate of the viral DNA.

Adenolymphoma↗
PubMed1992

The effect of ruthenium red during Ca2+ depletion and repletion in the isolated perfused rat liver.

Perfusion of rat liver with Ca(2+)-depleted buffer induces oxidative stress and liver damage, which can be prevented by Ca2+ repletion (Okuda et al. J Lab Clin Med). In the present study, we investigated the action of ruthenium red on acute Ca2+ loading after Ca2+ depletion in the isolated perfused rat liver. The major findings of this study are that 1) Ca2+ depletion-induced liver damage was related to mitochondrial disfunction; 2) ruthenium red inhibited the oxidative stress and liver damage normally seen during Ca2+ depletion; 3) ruthenium red inhibited the Ca2+ depletion-induced mitochondrial disfunction. These observations suggest that mitochondrial Ca2+ cycling is responsible for Ca2+ depletion-induced oxidative stress and liver damage.

Animals↗
PubMed1992

Oxygen radical generation during ischemia-reperfusion in the isolated perfused rat liver monitored by enhanced chemiluminescence.

Using luminol- and lucigenin-enhanced chemiluminescence (Lm-CL and Lg-CL), we monitored oxygen radical generation during ischemia-reperfusion in the isolated perfused rat liver. Both enhanced chemiluminescence levels decreased during 30 min of ischemia and increased markedly at the onset of reperfusion. When the liver was subjected to another 30 min of ischemia, reperfusion caused a progressive increase in both types of enhanced chemiluminescence. Administration of superoxide dismutase (SOD) into the perfusate strongly attenuated Lm-CL, but had a limited effect on Lg-CL. Catalase (CAT) and allupurionol (ALP) failed to attenuate both types of enhanced chemiluminescence. Thus the predominant oxygen radicals in the liver during reperfusion is superoxide and the lack of effect of ALP on oxygen radical generation indicates that hypoxanthine-xanthine oxidase reaction is unlikely to be a primary source of oxygen radicals. The different response to SOD in Lm-CL and Lg-CL is considered to be based on the diffusion space of luminol and lucigenin in the tissue. The relationship between oxygen radical levels and tissue damage, and the site of oxygen radical detection are discussed.

Acridines↗
PubMed1992

Role of extracellular Ca2+ in ischemia-reperfusion injury in the isolated perfused rat liver.

The influx of extracellular Ca2+ has been postulated to be one of the mediators of ischemia-reperfusion injury. A possible link between Ca2+ influx and oxygen radical generation has also been suggested. In the present study, using the isolated perfused rat liver, we evaluated the role of extracellular Ca2+ on oxygen radical generation, liver damage, and lipid peroxidation during 30 min ischemia and 60 min of reperfusion. Oxygen radical generation in the liver was continuously monitored by lucigenin-enhanced chemiluminescence. Liver damage and lipid peroxidation were evaluated by measuring lactate dehydrogenase (LDH) and thiobarbituric acid reactive substances (TBARS) release into the effusate, respectively. In the absence of extracellular Ca2+ (much less than 30 microM) oxygen radical generation from the liver increased gradually over 2 hr and there were concomitant increases in LDH and TBARS release. When livers were made ischemic and then reperfused, oxygen radical generation increased at the onset of reperfusion and then decreased over 30 min of reperfusion. After 30 min of reperfusion, livers reperfused with low Ca2+ buffer showed a linear increase in oxygen radical generation as well as progressive increases in LDH and TBARS release. On the other hand, livers reperfused with Ca2+ containing (1.25 mM) buffer showed no further increase in oxygen radical generation and no evidence of progressive liver damage and lipid peroxidation. These results suggest that Ca2+ overload is not a primary cause of liver ischemia-reperfusion injury and that the presence of extracellular Ca2+ during reperfusion is necessary to maintain normal liver function.

Acridines↗
PubMed1992

[A case of monoblastic crisis of CML beginning with extramedullary tumor formation in a rib].

A patient with CML showed monoblastic crisis which started with extramedullary tumor formation in a rib before medullary involvement. She was diagnosed as having CML in 1984 at the age of 57. In February 1990, she was admitted to Furukawa City Hospital because of extramedullary blastic crisis beginning at the right 5th rib. At that time, the bone marrow revealed 4.6% blasts. On March 5, after one course of chemotherapy, she was transferred to our hospital for radiotherapy. Hematological findings were WBC 10,100/microliter with 10% blasts, Hb 10.9 g/dl, platelet 3.7 x 10(4)/microliters. Bone marrow aspiration was unsuccessful. The blasts in the peripheral blood were negative for peroxidase and chloroacetate esterase; but positive for naphtylbutyrate esterase. The leukemic cells were positive for CD13, CD33, and had phagocytic activity. Chromosomal analysis revealed 46XX with Ph1 chromosome and some additional anomalies. Southern blot analysis of tumor cells shows BCR rearrangement. These findings suggest that the blasts were immature monocytic cells, and we conclude that this is a rare case of extramedullary monoblastic crisis of CML.

Bone Neoplasms↗
PubMed1992

[Differentiating effect of oral administration of retinol palmitate (Chocola-A) for an aged AML (M3) with severe complications].

A 74 year-old woman, who had been diagnosed as AML (M3) in poor condition, was treated with Retinol Palmitate (Chocola-A, 150,000 unit/m2 per os, after informed consent. An increase of white blood cells (neutrophil) counts was observed after 7 days. After 4 weeks, WBC counts were increased to 20,700/microliters (neutrophil counts 6,400/microliters) Maturation tendency of leukemic cells was also proved in the bone marrow. In vitro studies showed that morphological differentiation was recognizable in cultured leukemic cells treated with 10(-6)M all-trans retinoic acid after 6 days, but not in controls. Responses in the NBT reduction test were slightly less than in the clinical study. The administration of Retinol Palmitate may be a new regimen to treat AML (M3) in aged patients in poor condition.

Administration, Oral↗