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Biomedical subjects

S Masuda

Publications and source records attributed to S Masuda.

At least 37 records · Page 2Linked to original sources
PubMed2001

Human REG I gene is up-regulated in intrahepatic cholangiocarcinoma and its precursor lesions.

The Reg I gene (regenerating gene) and its product (Reg protein) are a regenerating and/or proliferating factor(s) of pancreatic islet cells. The ectopic expression of REG Ialpha was shown in colorectal carcinomas, suggesting that REG Ialpha is related to their carcinogenesis. In this study, we examined the expression of REG I in intrahepatic cholangiocarcinoma (ICC) and its precursor lesion (biliary dysplasia). By polymerase chain reaction and in situ hybridization (ISH) studies using a total of 16 fresh liver specimens, REG Ialpha mRNA was demonstrated in 6 of 11 (55%) ICC cases, but in 0 of 5 (0%) normal livers. Immunohistochemistry for REG I protein was performed in 100 formalin-fixed, paraffin-embedded sections obtained from the 18 cases of ICC alone, 45 hepatolithiasis with ICC (n = 19) or biliary dysplasia (n = 26), 21 hepatolithiasis alone (all with hyperplasia), and 16 normal livers. In ICC, the expression of REG I protein was significantly dependent on the histologic differentiation; 12 of 13 (92%) cases in papillary and well-differentiated, 6 of 16 (38%) cases in moderately differentiated, and 0 of 8 (0%) cases in poorly differentiated types. Moreover, in the lesions of hyperplasia, low-grade dysplasia, and high-grade dysplasia in hepatolithiasis, REG I protein was expressed in 4 of 21 (19%), 7 of 12 (58%), and 13 of 14 (93%) cases, respectively. In normal liver, intrahepatic bile ducts were constantly negative for REG I protein. These findings suggest that neoexpression of REG I is a good marker for biliary mucosa at risk for development of ICC, and also that REG I plays a role in the early stages of biliary carcinogenesis, probably via a cell-proliferative effect.

Bile Duct Neoplasms↗
PubMed2001

Study of retrieved acetabular sockets made from high-dose, cross-linked polyethylene.

Although ultra-high molecular weight polyethylene (UHMWPE) has stable chemical properties, chemical degradation, such as oxidation reaction, progresses with long-term clinical use. The purpose of this study was to investigate the change in properties of polyethylene (PE) in vivo by examining retrieved UHMWPE sockets and high-dose, cross-linked PE (100 Mrad PE) sockets. Twenty retrieved sockets (including 2 100 Mrad PE sockets), which were implanted from 1970 to 1996, were used for analysis. The oxidation index of 100 Mrad PE sockets was approximately the same as that of the normal UHMWPE sockets in worn areas. These long-term clinical results indicate that 100 Mrad PE is sufficiently stable for clinical use and that free radicals would not affect progression of oxidation significantly.

Acetabulum↗
PubMed2001

Pharmacokinetic and prognostic significance of intestinal MDR1 expression in recipients of living-donor liver transplantation.

BACKGROUND: Living-donor liver transplantation (LDLT) and subsequent immunosuppressive therapy with tacrolimus have been cornerstones in the recovery of patients from end-stage liver failure, but there has been no critical dosage regimen for tacrolimus therapy, especially the initial dosage. In this study, we examined whether the absorptive barriers, multidrug resistance protein (MDR1), or cytochrome P450 IIIA4 (CYP3A4) are important pharmacokinetic factors for tacrolimus and are prognostic indicators for LDLT outcome. METHODS: We used competitive polymerase chain reaction to evaluate the messenger ribonucleic acid (mRNA) expression levels of MDRL And Cyp3A4 in mucosal cells of the upper jejunum from a part of the Rroux-en- Y limb for biliary reconstruction during LDLT of recipients (n = 48). The tacrolimus dosage was started at an oral dose of 0.075 mg/kg every 12 hours and adjusted on the basis of its whole-blood trough level by use of a semiautomated microparticle enzyme immunoassay. RESULTS: The mRNA expression level of MDR1 (r = -0.776), but not CYP3A4 (r = -0.094), was inversely related to the concentration/dose ratio of tacrolimus. High levels of MDR1, but not CYP3A4, were strongly associated with reductions in survival rates after LDLT with the Kaplan-Meier method and log-rank statistics (P =.020 and P =.135, respectively). With use of a Cox regression procedure, high levels of MDR1 (relative risk, 12.99; 95% confidence interval, 1.64-103.23), but not CYP3A4 (relative risk, 0.93; 95% confidence interval, 0.87-1.00) appeared to be a significant prognostic indicator for poor survival. CONCLUSIONS: Intestinal MDR1 is not only a good probe with which to predict the interindividual variation in tacrolimus pharmacokinetics after LDLT but also a powerful prognostic indicator for the outcome of LDLT.

Adolescent↗
PubMed2001

Upregulation of H(+)-peptide cotransporter PEPT2 in rat remnant kidney.

The progression of renal damage resulting from reduced nephron mass has been extensively studied in the 5/6 nephrectomized rat. However, reabsorption of small peptides and D-glucose across the renal proximal tubule in this model remains poorly understood. In this study, we examined the alterations of H(+)-peptide cotransporters (PEPT1 and PEPT2) and Na(+)-D-glucose cotransporters (SGLT1 and SGLT2) in chronic renal failure. Two weeks after surgery, H(+)-dependent [(14)C]glycylsarcosine uptake by the renal brush-border membrane vesicles isolated from 5/6 nephrectomized rats was significantly increased compared with that from sham-operated controls. Kinetic analysis revealed that the maximum velocity value for [(14)C]glycylsarcosine uptake by the high-affinity-type of peptide transporter was increased threefold by 5/6 nephrectomy, without significant changes in the apparent Michaelis-Menten constant value. Competitive PCR analyses indicated that the expression of PEPT2 mRNA was markedly increased in the remnant kidney, but PEPT1, SGLT1, and SGLT2 mRNA levels showed no significant changes. These findings indicated that the high-affinity-type H(+)-peptide cotransport activity is upregulated by 5/6 nephrectomy, accompanied by the increased expression of PEPT2. The upregulation of PEPT2 expression would result in an increase in reabsorption of small peptides and peptide-like drugs across the brush-border membranes in chronic renal failure.

Animals↗
PubMed2001

Pleiotropic functions and tissue-specific expression of erythropoietin.

Erythropoietin (EPO) is produced in the brain, uterus, and oviduct. Brain EPO plays a neuroprotective role, and uterine EPO is likely involved in estrogen-dependent angiogenesis. Hypoxic induction of brain EPO markedly differs from that in the kidney. EPO in the uterus and oviduct is estrogen inducible.

Animals↗
PubMed2001

Chitinase in cucumber xylem sap.

A chitinase activity was detected in fractions of xylem sap collected from the cut surface of cucumber stems. A 28-kDa acidic protein was purified from the active fractions and its N-terminal amino acid sequence was found to be identical to that of a chitinase gene. Cucumber roots produce and secrete an acidic chitinase, one of the PR proteins, into xylem sap and deliver it to aboveground organs.

Amino Acid Sequence↗
PubMed2001

In vivo gene electroporation in skeletal muscle with special reference to the duration of gene expression.

To determine the limits of the duration of in vivo transferred foreign gene expression, we conducted electroporation (EP), a powerful non-viral means of gene transfer for living animals, into skeletal muscle of rats and mice with a luciferase, GFP or erythropoietin (EPO)-encoding reporter plasmid. The luciferase reporter plasmid was used for optimization of EP conditions, while GFP and EPO plasmids were used for monitoring the duration of gene expression. In the rat, increased hematocrit levels were maintained for at least 9 weeks with approximately a 3-fold increase in plasma EPO protein concentration at 4 weeks post-transfection. In the mouse, the GFP plasmid transfer confirmed that the reporter gene expression lasted as long as 3 months post-transfection. By introducing the EPO gene in vivo in the mouse, increased hematocrit levels revealed that duration of reporter gene expression was at least 14.5 months after in vivo gene EP into skeletal muscle. These results implicate an excellent potential of in vivo gene EP, applicable to both experimental and therapeutic purposes.

Animals↗
PubMed2001

[Significance of pyrimidine nucleoside phosphorylase (PyNPase) and dihydropyrimidine dehydrogenase (DPD) in advanced gastric cancers].

We measured pyrimidine nucleoside phosphorylase (PyNPase), a known angiogenetic factor, and dihydropyrimidine dehydrogenase (DPD) in advanced gastric cancers. PyNPase was expressed in cytoplasm of the cancer cells and surrounding interstitial cells. The levels of PyNPase and DPD were significantly higher in cancer tissue. With respect to tumor factors, the level of PyNPase was significantly higher in cases positive for venous invasion. We divided patients into two groups, with high and low activities of IAP and MMP-9. The level of PyNPase was significantly higher in the high IAP activity group. A correlation was suggested between the level of PyNPase and the activity of IAP. 5'-Deoxy-5-fluorouridine (5'-DFUR) is transformed into 5-FU by PyNPase and manifests antitumor effects. DPD is a rate-limiting enzyme in the process of degradation of 5-FU. In the present study, the level of PyNPase/DPD was significantly higher in cancer tissue. PyNPase/DPD suggests not only the malignant potential of the tumor but also the efficiency of chemotherapy using 5-FU, especially 5'-DFUR.

Aged↗
PubMed2001

Multispecific substrate recognition of kidney-specific organic anion transporters OAT-K1 and OAT-K2.

We characterized the interactions of various compounds with OAT-K1 and OAT-K2, kidney-specific organic anion transporters. By using Madin-Darby canine kidney cells stably transfected with OAT-K1 or OAT-K2 cDNA, the antitumor drug methotrexate, the mycotoxin ochratoxin A, endogenous organic anions (thyroid hormones, taurocholic acid, and conjugated steroids), and the antiretroviral drug zidovudine were shown to be substrates for these transporters. Although the apparent Michaelis constant (Km) values of methotrexate for OAT-K1 and OAT-K2 were 2.1 and 1.8 microM, respectively, 2.5 mM methotrexate inhibited only 20% of the 125I-thyroid hormones uptake via these transporters. In addition, 100 microM methotrexate did not have any effect on [3H]zidovudine uptake via OAT-K1 or OAT-K2. Similarly, several substrates caused little or no mutual inhibition at concentrations much higher than their Km values for these transporters. Moreover, intracellular methotrexate trans-stimulated the OAT-K1- and OAT-K2-mediated uptake of [3H]folic acid, but not that of other compounds. Organic anion-transporting polypeptide 2 (oatp2), a liver-type homolog of OAT-K1 and OAT-K2, showed similar events. The inhibition constant values of triiodothyronine and taurocholic acid for [3H]digoxin uptake in oatp2-expressing oocytes resulted in 50.4 and 1.48 mM, respectively, which were about 9- and 40-fold higher than their Km values for oatp2, respectively. These findings suggested that several substrates interact with these transporters at different amino acid residue(s). Taken together, these observations suggested that OAT-K1 and OAT-K2 could serve as multispecific transporters, mediating transport of a wide variety of endogenous substances, xenobiotics, and their metabolites in the kidney, presumably via several interaction sites in their molecules.

Animals↗
PubMed2000

cDNA cloning and characterization of vascular apoptosis-inducing protein 1.

Hemorrhagic snake venom induces apoptosis in vascular endothelial cells (VEC). In previous reports, we described the purification from crude venom of Crotalus atrox of two vascular apoptosis-inducing proteins (VAP1 and VAP2) that specifically induce apoptosis in vascular endothelial cells. We report here the cDNA cloning and characterization of VAP1. VAP1 cDNA encoded a protein with 610 amino acid residues. The amino acid sequence predicted from the cDNA indicated that VAP1 belongs to the metalloprotease/disintegrin family and that it is a multidomain polypeptide with a proprotein domain, a metalloprotease domain, a disintegrin-like domain, and a cysteine-rich domain. In the disintegrin-like domain, the sequence DECD replaces the RGD sequence that has frequently been found in such domains. We demonstrated that VAP1 has Zn(2+)-dependent metalloprotease activity and degrades fibrinogen. After incubation in the presence of either EDTA or EGTA, VAP1 was hardly able to degrade fibrinogen and to induce apoptosis in VEC. Our results indicated that VAP1 is a new type of snake venom metalloprotease/disintegrin and suggest that the metalloprotease activity of VAP1 might be involved in the induction of apoptosis by VAP1 in VEC.

Amino Acid Sequence↗
PubMed2000

Endoscopic surgery for lateral cervical cysts. A report of three cases.

Recently, endoscopic surgery has been applied to cervical exploration. We have developed new techniques for endoscopic neck surgery, and in this paper report our experience with three patients with lateral cervical cysts. A 5- or 10-mm midline trocar for the endoscope and two 5- or 10-mm lateral trocars were inserted from the anterior chest wall and/or both axillary fossae to avoid neck scars. There were no intraoperative complications. Slight subcutaneus emphysema was present postoperatively, but it was limited to the neck and disappeared in a few days. The incisions were completely covered by the patients' undergarments. This is the first report of endoscopic lateral cervical cystectomy.

Adolescent↗
PubMed2000

Type I muscle atrophy caused by microgravity-induced decrease of myocyte enhancer factor 2C (MEF2C) protein expression.

To investigate the molecular mechanisms of muscle atrophy under microgravity, the paraspinal muscles of rats after 14 days spaceflight and those of ground-based controls were examined. In the microgravitational environment, expressions of 42 genes changed, and the expressions of heat shock protein 70 and t complex polypeptide 1 increased. In Northern blotting, myocyte-specific enhancer binding factor 2C (MEF2C) and MEF2C-related genes including aldolase A and muscle ankyrin decreased. After 9 days ground recovery, expression of MEF2C increased and it was located mainly on the satellite cells in the muscle regeneration state. MEF2C could be a key transcriptional factor for skeletal muscle atrophy and regeneration under microgravity.

Animals↗
PubMed2000

A new biological strategy for high productivity of recombinant proteins in animal cells by the use of hypoxia-response enhancer.

Oxygen supply is one of the major problems in the production of useful proteins by cultured animal cells and therefore it is of importance to devise a system by which a high productivity of human therapeutic recombinant proteins can be maintained or enhanced under low oxygen concentrations. A number of hypoxia-inducible genes have been found in animal cells and the induction in most cases is due to hypoxic activation of the gene transcription. A consensus sequence (HRE = hypoxia-response enhancer) responsible for the hypoxic activation exists in these genes and the binding of a protein, which is widely distributed in animal cells, to this sequence responding to hypoxia activates the promoter activity. The promoter of lactate dehydrogenase A gene is active in Chinese hamster ovary (CHO) cells and the vicinal HRE stimulates the promoter activity efficiently in hypoxia. We have prepared a number of permanent CHO cell lines producing recombinant human erythropoietin (Epo) under control of this promoter/HRE. Epo production was highly hypoxia-inducible when the wild-type of HRE was used but uninducible when the mutant HRE was used. There was little difference in the in vitro and in vivo activities, and glycosylation between Epo produced by the cells cultured in 21% and 2% oxygen. Furthermore, forced expression of hypoxia-inducible factor-1alpha (HIF-1alpha) enhanced Epo production in all oxygen concentrations. These results indicate that a biological strategy based on the hypoxic induction of gene transcription provides a novel system which guarantees a high productivity even uner low oxygen concentrations.

Animals↗
PubMed2000

Redox regulation of glutathione S-transferase induction by benzyl isothiocyanate: correlation of enzyme induction with the formation of reactive oxygen intermediates.

Here we report the molecular mechanism underlying the induction of glutathione S-transferase (GST) in rat liver epithelial RL34 cells treated with a cancer chemopreventive isothiocyanate compound, benzylisothiocyanate (BITC). BITC was found to significantly induce GST activity in RL34 cells. Northern and Western blot analyses demonstrated that BITC specifically enhanced the production of the class pi GST isozyme (GSTP1). Our studies demonstrated for the first time that the addition of BITC to the cells resulted in an immediate increase in the reactive oxygen intermediates (ROIs) detected by a fluorescence probe, 2',7'-dichlorofluorescin diacetate. The level of the ROIs in the cells treated with BITC (10 microM) was approximately 50-fold higher than those in the control cells. Furthermore, glutathione depletion by diethyl maleate significantly enhanced BITC-induced ROI production and accelerated the BITC-induced elevation of the GST activity, whereas pretreatment of the cells with glutathione inhibited both the ROI production and GST induction. The structure-activity relationship of the isothiocyanates also indicated that the ROI-producing activities closely correlated with their GST-inducing potencies. Moreover, the GSTP1 enhancer I-containing region was found to be essential for induction of the GSTP1 gene by intracellular ROI inducers such as BITC and diethyl maleate. These data suggest the involvement of the redox regulation on the induction of GSTP1 by BITC.

Animals↗