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Biomedical subjects

M Unno

Publications and source records attributed to M Unno.

At least 37 records · Page 2Linked to original sources
PubMed1999

Hepatic phosphatidylcholine hydroperoxide content in noncirrhotic, cirrhotic, and antioxidant-treated rats with endotoxemia.

Hepatic phosphatidylcholine hydroperoxide (PCOOH) was studied intensively to delineate its role in the altered pathophysiology of liver failure associated with endotoxemic shock. Endotoxemia was induced by cecal ligation and puncture (CLP) in three models using rats. Model 1 consisted of normal healthy rats; model 2, cirrhotic rats; and model 3, rats treated with catalase and superoxide dismutase (SOD). Samples were taken before CLP, then 12 h and 24 h following CLP. A progressive and significant increase in serum endotoxin was seen in all models; however, a significantly low energy charge (EC) and high PCOOH were seen in models 1 and 2, whereas no change was observed in model 3. The regional blood flow remained unchanged throughout the experiment in models 1 and 3, but not in model 2. An initial increase in alpha-tocopherol was seen in model 1. The survival rate was markedly better in model 3 than in models 1 or 2. The fall in EC corresponded to the increase in serum endotoxin as well as to the increase in tissue PCOOH in models 1 and 2. It was more likely that the elevated lipid peroxidation in model 1 resulted from endotoxemia rather than from tissue hypoperfusion. The early increase in alpha-tocopherol that occurred in models 1 and 2, but not in model 3, indicated the antiradical defense response to oxidative injury. Thus, antioxidant therapy significantly improved the survival rate and tissue adenine nucleotide level in spite of the increased serum endotoxin level.

Adenosine Triphosphate↗
PubMed1999

Molecular characterization and functional regulation of a novel rat liver-specific organic anion transporter rlst-1.

BACKGROUND & AIMS: Recently, we isolated a new complementary DNA (cDNA) encoding human liver-specific organic anion transporter (LST-1), representing the multispecificity of human liver. The aim of this study was to isolate a rat counterpart of human LST-1 and examine the expression regulation of its messenger RNA (mRNA) to clarify the molecular basis of cholestasis. METHODS: A rat liver cDNA library was screened with human LST-1 cDNA as a probe. Xenopus oocyte expression system was used for functional analysis. Northern blot analyses were performed using the isolated cDNA (termed rlst-1). The bile duct ligation model and the cecum ligation and puncture model were used for expression analyses. RESULTS: rlst-1 encodes 652 amino acids, predicting at least 11 transmembrane regions. The overall homology with human LST-1 was 60.2%, which is the highest among all known organic anion transporters. rlst-1 also belongs to the same new gene family as human LST-1, located between the organic anion transporter family and the prostaglandin transporter. rlst-1 preferably transports taurocholate (K(m), 9.45 micromol/L) in an Na(+)-independent manner. The rlst-1 mRNA is exclusively expressed in the liver. In both the bile duct ligation model and the cecum ligation and puncture model, mRNA expression levels of rlst-1 were down-regulated. CONCLUSIONS: rlst-1 is a counterpart of human LST-1 and is one of the important transporters in rat liver for the clearance of bile acid. The expression of rlst-1 may be under feedback regulation of cholestasis by biliary obstruction and/or sepsis.

Amino Acid Sequence↗
PubMed1999

The degree of hepatic regeneration after partial hepatectomy in rats with peritonitis and the role of lipid peroxidation.

Bile accumulation in the peritoneal cavity after partial hepatectomy reduces hepatic regeneration. In 70% of hepatectomized rats with bile peritonitis, hepatic DNA synthesis showed a delayed initiation and diminished peak level. Because intraperitoneal bile significantly accelerated lipid peroxidation and decreased energy metabolism in the liver remnant, all hepatectomized rats with bile peritonitis died within 7 days. Subcutaneous administration of exogenous combined antioxidants SOD and catalase dramatically reduced lipid peroxidation and improved the survival rate. Although the slightly elevated serum endotoxin level in rats with peritonitis may play a role in the inhibition of hepatic regeneration, the result suggest that intraperitoneal accumulation of bile components may also directly accelerate lipid peroxidation in the liver remnant, inhibiting the hepatic regeneration.

Alanine Transaminase↗
PubMed1999

Digest

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Journal Article↗
PubMed1999

Induction of epithelial Na+ channel in rat ileum after proctocolectomy.

In patients with colectomy, epithelial transport function in the remnant small intestine can be regulated in response to the increased fecal electrolyte and fluid loss. Using a rat colectomy model, we investigated the Na+ and K+ transport mechanisms underlying the intestinal response. Proctocolectomy with ileoanal anastomosis was performed on rats. The small intestinal mucosa was mounted in Ussing chambers; then short-circuit currents and 22Na+ fluxes were measured. mRNA expression of the epithelial Na+ channel (ENaC) was determined by Northern blotting. Amiloride-sensitive, electrogenic Na+ absorption appeared in the ileum after proctocolectomy. This functional change was accompanied by the chronological induction of mRNAs for alpha-, beta-, and gamma-subunits of the ENaC in the ileum. Tetraethylammonium-sensitive short-circuit current was also activated. We conclude that electrogenic Na+ absorption and probably K+ secretion are induced in the ileum after proctocolectomy. This induction of electrogenic Na+ absorption is probably mediated by the increase in the mRNA levels for all three types of subunits of the ENaC and may contribute to the recovery from the increased fecal Na+ loss.

Aldosterone↗
PubMed1998

Simplified hepatic resection utilizing absorbable polyglycolic acid-based tape and other ligature apparatus.

Hepatic resection has been increasing in frequency in the management of metastatic or primary neoplasms of the liver. Although mortality for this procedure has steadily decreased, the associated morbidity remains high. Morbidity is mainly associated with operative time and blood loss, especially in jaundiced and cirrhotic patients. During hepatic resection, control of bleeding from various sources is the most important problem faced by surgeons. During conventional lobectomy, despite prior control of hepatic artery and portal vein to that lobe, bleeding still occurs from the opposite lobe or back flow from hepatic veins. We usually apply Pringle's maneuver for hemostasis, but consequently there is postoperative hepatic dysfunction. We have previously investigated methods for vascular occlusion at the site of liver resection. We developed a new absorbable polyglycolic acid-based tape (breadth, 3 mm; length, 70 cm) for use in hepatic mass ligation, as well as two types of ligature apparatus. Hemostasis was achieved with these devices, and all lobar, segmental, and non-anatomic resections were performed without prior control of the portal venous system, hepatic arterial inflow, and hepatic venous outflow before parenchymal resection. This significantly shortened the operative time, as well as decreasing the blood loss during hepatic resection, with consequent reduction of postoperative morbidity. The use of this absorbable tape may reduce the incidence of local infection, abscess formation, and septicemia.

Absorbable Implants↗
PubMed1998

Myoglobin mutants giving the largest geminate yield in CO rebinding in the nanosecond time domain.

We have measured the rebinding of carbon monoxide (CO) to some distal mutants of myoglobin (Mb) in the time range from 10(-8) to 10(-1) s by flash photolysis, in which the photodissociated CO rebinds to the heme iron without escaping to the solvent water from the protein matrix. We have found that the double mutants [His64-->Val/Val68-->Thr (H64V/V68T) and His64-->Val/Val68-->Ser (H64V/V68S)] have an extremely large geminate yield (70-80%) in water at 5 degreesC, in contrast to the 7% of the geminate yield of wild-type Mb. The CO geminate yields for these two mutants are the largest in those of Mb mutants reported so far, showing that the two mutants have a unique heme environment that favors CO geminate rebinding. Comparing the crystal structures and 1H-NMR and vibrational spectral data of H64V/V68T and H64V/V68S with those of other mutants, we discuss factors that may control the nanosecond geminate CO rebinding and CO migration in the protein matrix.

Carbon Monoxide↗
PubMed1998

[Advantages and disadvantages of SMANCS-Lipiodol intrahepatic arterial infusion chemotherapy for unresectable hepatocellular carcinoma].

Though SMANCS-Lipiodol suspension has advantages over tumor regression, its disadvantages should also be considered: (1) Anaphylactic reaction due to its high molecular weight. (2) Since it readily destroys the tissue, a smaller dose and repeated administration are required. (3) Due to its low viscosity, it easily enters the arterioles and causes damage even to the extrahepatic organs. When this drug is infused into the left hepatic artery in subsegmental fashion, it enters the neighboring gastric tissues through the communication of the left hepatic and left gastric arteries, and this ultimately causes intractable gastric ulcers. Considering the above facts, this drug should be used carefully.

Adult↗
PubMed1997

Spectroscopic effects of polarity and hydration in the distal heme pocket of deoxymyoglobin.

Distal pocket mutations at the E7 position (His64) of sperm whale deoxymyoglobin (deoxyMb) are used as a probe of distal pocket polarity and hydration. Changes of two key spectroscopic markers, the Fe-His(F8) stretch in the resonance Raman spectrum and the position of band III in the absorption spectrum, are monitored as the His64Tyr, His64Phe, His64Leu, and His64Gly mutations alter the distal heme pocket environment. The Fe-His vibration for the Phe, Leu, and Gly mutants is shifted to a lower frequency by 1-2 cm-1 relative to the Tyr mutant, wild type (WT), and native deoxyMb. Band III shifts to the red by approximately 4 nm ( approximately 70 cm-1) relative to WT and native deoxyMb for all the His64 mutants examined in this work. We correlate the small shift in the Fe-His frequency to the local electrostatic environment directly above the heme iron, affected by the presence of a localized water molecule in the heme pocket that is hydrogen-bonded to the E7 residue. The position of band III is roughly correlated to the displacement of the iron from the heme plane; however, the relatively large scatter in this correlation, as well as its dependence on distal pocket mutations, suggests that the heme pocket environment, particularly the E7 residue, also affects the energy of this transition.

Animals↗
PubMed1997

Structure, chromosomal localization and expression of mouse genes encoding type III Reg, RegIII alpha, RegIII beta, RegIII gamma.

Reg (regenerating gene), first isolated from a rat regenerating islet cDNA library, is expressed in regenerating islet beta-cells. Recently, it has been revealed that Reg and Reg-related genes constitute a multigene family, Reg family, which consists of three subtypes (type I, II, III) based on the primary structures of the encoded proteins of the genes. In mouse, type I and type II Reg genes (i.e. RegI and RegII gene) have so far been isolated. In the present study, the complete nucleotide (nt) sequences of the cDNAs and genes encoding murine type III Reg (regenerating gene product), RegIII alpha, RegIII beta and RegIII gamma were determined. RegIII alpha, RegIII beta and RegIII gamma encode 175-, 175- and 174-amino acid (aa) proteins, respectively, with 60-70% homology. All three genes are composed of six exons and five introns spanning approx. 3 kb, and exhibit distinctive structural features unique for members of the Reg gene family. All the mouse Reg genes, RegIII alpha, RegIII beta, RegIII gamma, RegI and RegII, are assigned to the adjacent site of chromosome 6C by fluorescence in situ hybridization (FISH). RegIII alpha, RegIII beta and RegIII gamma were expressed weakly in pancreas, strongly in intestinal tract, but not in hyperplastic islets, whereas both RegI and RegII were expressed in hyperplastic islets. These results suggest that genes of the mouse Reg family are derived from a common ancestor gene by several gene duplications, and have obtained divergency in expression and function in the process of genetic evolution.

Amino Acid Sequence↗
PubMed1997

Effects of the intramolecular disulfide bond on ligand binding dynamics in myoglobin.

In order to investigate the effects of an intramolecular disulfide bond on protein structure and ligand binding dynamics in myoglobin, we prepared a mutant myoglobin having a disulfide bond at the EF corner by introducing two cysteine at the position of Ile 75 and Glu 85. On the basis of the spectral features of the mutant, the formation of the disulfide bond only affected minor structural deviations of the heme environmental structure in the carbonmonoxy form, whereas more substantial structural alterations were induced in the deoxygenated form. Laser photolysis experiments for carbon monoxide rebinding clearly showed that the artificial S-S bond accelerates the bimolecular rebinding rate from 1.0 to 1.8 microM-1 s-1 and increases the geminate yield from 0.072 to 0.092. The ligand migration rate from the solvent to the heme pocket and the bond formation rate from the heme pocket to the heme iron also increased. The free energy diagram for the mutants indicates that the energy barrier for the bond formation was raised as well as that for the ligand migration by introduction of the disulfide bond. However, the effects of the disulfide linkage at the EF corner on the kinetic parameter is much smaller than those of the amino acid substitutions located in the heme cavity. We can conclude that the perturbation of the protein fluctuations by formation of the disulfide bond would be localized at the mutation site or the contributions from other regions and motions might be more important for the ligand binding dynamics.

Binding Sites↗
PubMed1997

[An anaphylactic shock case after hepatic arterial infusion of zinostatin stimalamer suspension improved by anti-histaminics].

A 47-year-old man with hepatocellular carcinoma (HCC) at anterior and medical segment in the liver was treated with hepatic arterial infusion of Zinostatin Stimalamer-lipiodol suspension (SMANCS). After the 2nd infusion of SMANCS, the accumulation of lipiodol in the tumor was not good (Grade II), so additional administration was undertaken at five-weeks intervals. His systolic blood pressure immediately decreased from 120 to 60 mmHg, and he had numbness of hands, shaking chills, sweating, chest pain and numerous urticaria-like red exanthema. In spite of treatment by anti-shock agents such as steroid and catecholamines, these symptoms did not disappear, but antihistaminics greatly improved them without any serious side effects. Because of the remarkable effects of the antihistaminics and possibility of antibody production (IgE) after repeated infusions of high molecular SMANCS, this patient may have suffered anaphylactic shock caused by massive histamine release from mast cells.

Anaphylaxis↗
PubMed1996

Role of Arg112 of cytochrome p450cam in the electron transfer from reduced putidaredoxin. Analyses with site-directed mutants.

The mechanism for the reduction of ferric cytochrome P450cam by reduced putidaredoxin, the physiological electron donor for the cytochrome, has been studied by using site-directed mutants of cytochrome P450cam, in which Arg112, an amino acid residue at the presumed binding site for putidaredoxin, was changed to several other amino acid residues. The affinity of reduced putidaredoxin for ferric cytochrome P450cam to form a diprotein complex was decreased greatly by changing Arg112 to a neutral amino acid such as Cys, Met, or Tyr. The rate of intracomplex electron transfer from putidaredoxin to cytochrome P450cam also diminished upon replacing the basic residue with neutral ones, being 42, 18, 4.0, 1.3, and 0. 16 s-1 for Arg (wild type), Lys, Cys, Met, and Tyr enzymes, respectively. Furthermore, the oxidation-reduction potential of cytochrome P450cam (Fe3+/Fe2+ couple) decreased in a similar way to the decrease in the rate of electron transfer upon amino acid substitution; the values were -138, -162, -182, -200, and -195 mV for Arg (wild type), Lys, Cys, Met, and Tyr enzymes, respectively. These results indicate that the amino acid substitution at position 112 affects the oxidation-reduction potential of the heme iron in cytochrome P450cam, thereby diminishing the rate of electron transfer between the two metal centers. The rate of electron transfer from putidaredoxin to oxyferrous cytochrome P450cam also diminished upon substitution of Arg112 with a neutral amino acid.

Arginine↗
PubMed1995

Nicotinamide inhibits IRF-1 mRNA induction and prevents IL-1 beta-induced nitric oxide synthase expression in pancreatic beta cells.

Nitric oxide produced by inducible nitric oxide synthase in islets exerts inhibitory and cytotoxic effects on pancreatic beta cells and is therefore thought to be a potent mediator in the pathogenesis of Type I diabetes mellitus. Here, using isolated rat pancreatic islets, we show that high-concentration nicotinamide (20 mM), but not low-concentration nicotinamide (5 mM), attenuates the interleukin-1 beta-evoked inhibition of glucose-induced insulin secretion by preventing the induction of interferon regulatory factor-1, a transcriptional factor which plays an essential role in inducible nitric oxide synthase gene expression, and the interleukin-1 beta-induced nitric oxide formation. High-concentration nicotinamide also restored an interleukin-1 beta-induced decrease in ATP content in pancreatic beta cells, suggesting that interleukin-1 beta-induced nitric oxide inhibits the mitochondrial function. The present results show the molecular basis of the preventive effect of high-dose nicotinamide on Type I diabetes mellitus.

Adenosine Triphosphate↗