Biomedical subjects

I Endo

Publications and source records attributed to I Endo.

At least 37 records · Page 2Linked to original sources

PubMed2001

Successful left trisegmentectomy for polycystic liver disease accompanied by jaundice.

BACKGROUND: We report a case of severe polycystic liver disease (PLD) with jaundice in a 57-year-old woman who underwent successful left trisegmentectomy. METHOD: She was admitted for the first time in February 1992 to our hospital with a 7-year history of PLD, and became jaundiced in June 1995. Because normal liver parenchyma was confirmed mainly to the posterior segment, left trisegmentectomy was performed. RESULTS: No postoperative complication occurred. The serum bilirubin level decreased promptly after the operation, but postoperative endoscopic retrograde cholangiography showed that the root of the posterior hepatic duct remained thin. Thus, the elimination of jaundice was presumed to have been caused by a decrease of intra-abdominal and peripheral biliary pressure, since a large volume of tissue had been removed from the peritoneal cavity. She has since remained well without any symptoms. CONCLUSION: This procedure is useful for severe PLD, because it can be performed safely and the symptoms disappear dramatically. However, further follow-up is needed to determine the long-term effects of this procedure, because the remaining liver has shown some increase in size.

Cholangiopancreatography, Endoscopic Retrograde↗

PubMed2001

Corticospinal tract involvement in a variant of Guillain-Barré syndrome.

To determine the involvement of the corticospinal tract in Guillain-Barré syndrome (GBS), we examined central motor conduction in patients with GBS-like symptoms and hyperreflexia using a magnetic stimulation technique. The subjects were 3 patients who exhibited ascending muscle weakness 2-4 weeks after preceding infections. Deep tendon reflexes were exaggerated in all four limbs of the 3 patients. The results of cerebrospinal fluid examinations revealed protein elevation without pleocytosis. The serum anti-GM(1) antibody titer was elevated in 2 patients. The results of nerve conduction study revealed axonal motor neuropathy and normal F-wave conduction. Central motor conduction time (CMCT) in patients with hyperreflexia was significantly delayed compared to that in patients with GBS and areflexia (p < 0.001), and the delayed CMCTs were significantly improved in the recovery periods (p < 0.001). Although hyperreflexia is a controversial symptom in patients with GBS, these findings indicate that there is functional corticospinal tract involvement in patients with a GBS variant.

Adolescent↗

PubMed2001

[Ultra-slow infusion dynamic MRI using an infusion pump: a new method for the evaluation of drug distribution in arterial infusion chemotherapy].

Ultra slow infusion dynamic MR imaging using an infusion pump(IP-MRI) was performed in six patients with metastatic liver tumor or unresectable gastric cancer to evaluate ant-cancer drug distribution. We used un implanted port for the infusion of Gd-DTPA by infusion pump. On IP-MRI, the speed of Gd-DTPA infusion was very slow (0.01 ml/sec) , the same as drug infusion at chemotherapy. The contrast enhancement of tumors was extremely clear. Therefore, IP-MRI was considered feasible for the evaluation of drug distribution.

Adult↗

PubMed2001

[Indications for combined resection and reconstruction of the hepatic artery in biliary tract carcinoma].

More than 10 years have passed since hepatic artery resection was first performed for the treatment of biliary tract cancer. The safety of this procedure has been established with the introduction of the microsurgery technique. However, the benefits of and indications for this treatment have not yet been clarified. Twenty-three patients underwent vascular resection (portal vein in 7, portal vein + hepatic artery in 9, hepatic artery in 7) among 114 resected patients with biliary tract cancer in our institution. The right hepatic artery was reconstructed by end-to-end anastomosis in most cases. The curative resection rate was 88.9% in hilar bile duct cancer. However, it was less than 50% in other carcinomas. Cumulative 5-year survival rates of vascular resection patients with hilar bile duct cancer, lower bile duct cancer, gallbladder cancer, and cholangiocarcinoma were 14.8%, 25%, 0%, and 0%, respectively. On the other hand, the rates were 38.9%, 0%, 0%, and 0%, in the stage III + IV patients who did not undergo vascular resection. The longest survival period among patients with hilar bile duct cancer and lower bile duct cancer was 85 months and 65 months, respectively, whereas it was 15 months in gallbladder cancer and 20 months in cholangiocarcinoma patients. No hilar bile duct cancer patient who survived for more than 3 years had lymph node metastasis. The longest surviving cholangiocarcinoma patient has received adjuvant chemotherapy consisting of 5-fluorouracil and cisplatin. It is concluded that patients with hilar bile duct cancer are good candidates for vascular resection. Adjuvant chemotherapy should be administered to gallbladder cancer and cholangiocarcinoma patients, because vascular resection alone does not result in prolongation of life in these patients.

Aged↗

PubMed2000

Time delay effect in a living coupled oscillator system with the plasmodium of Physarum polycephalum.

A living coupled oscillator system was constructed by a cell patterning method with a plasmodial slime mold, in which parameters such as coupling strength and distance between the oscillators can be systematically controlled. Rich oscillation phenomena between the two-coupled oscillators, namely, desynchronizing and antiphase/in-phase synchronization were observed according to these parameters. Both experimental and theoretical approaches showed that these phenomena are closely related to the time delay effect in interactions between the oscillators.

Animals↗

PubMed2000

Arginine 56 mutation in the beta subunit of nitrile hydratase: importance of hydrogen bonding to the non-heme iron center.

Arginine 56 in the beta subunit (betaArg56) of the iron-containing nitrile hydratase (NHase), one of the strongly conserved residues within the NHase family, is known to form hydrogen bonds to the sulfinyl (-SO2H) and sulfenyl (-SOH) groups of the post-translationally modified cysteine residues in the catalytic center. BetaArg56 was substituted by tyrosine, glutamate or lysine, respectively, and the respective mutant enzymes generated by reconstitution were characterized. The betaR56K mutant complex exhibited about 1% of the enzymatic activity of native NHase, while the others were totally inactive. The kinetic analysis of the betaR56K mutant complex exhibited a drastic decrease in turnover number and decreases in kinetic constants for substrate and inhibitors as compared to the native NHase. Changes in UV-visible absorption and light-induced Fourier transform infrared difference spectra suggest that betaArg56 is involved in the positioning of the -SO2H and -SOH groups of the modified Cys residues in the catalytic center so as to fine tune the electronic state of the iron center suitable for catalysis. Thus, betaArg56 is essential for catalysis.

Arginine↗

PubMed2000

Cobalt-substituted Fe-type nitrile hydratase of Rhodococcus sp. N-771.

When the genes encoding alpha and beta subunits of Fe-type nitrile hydratase (NHase) from Rhodococcus sp. N-771 were expressed in Escherichia coli in Co-supplemented medium without co-expression of the NHase activator, the NHase specifically incorporated not Fe but Co ion into the catalytic center. The produced Co-substituted enzyme exhibited rather weak NHase activity, initially. However, the activity gradually increased by the incubation with an oxidizing agent, potassium hexacyanoferrate. The oxidizing agent is likely to activate the Co-substituent by oxidizing the Co atom to a low-spin Co(3+) state and/or modification of alphaCys-112 to a cysteine-sulfinic acid. It is suggested that the NHase activator not only supports the insertion of an Fe ion into the NHase protein but also activates the enzyme via the oxidation of its iron center.

Amino Acid Sequence↗

PubMed2000

Appraisal of surgical resection of gallbladder cancer with special reference to lymph node dissection.

BACKGROUND: Radical lymph node dissection in surgery for advanced gallbladder cancer is controversial. The purpose of this study is to evaluate the role of lymph node dissection based on the clinico-pathologic results. PATIENTS: Seventy-three patients who underwent radical surgery including systematic dissection of the N1+N2 region lymph node plus some of the para-aortic nodes were reviewed. RESULTS: pT1 patients had no lymph node metastasis, but pT2 and pT3/pT4 patients had lymph node metastasis at a rate of 50.0% (13/26) and 83.3% (25/30), respectively. As infiltration of the hepatoduodenal ligament (Binf) became severe, the rate and extent of lymph node metastasis increased. There were four 5-year survivors with lymph node involvement. The 5-year survival rates are 77.0% in pN0 cases and 27.3% in pN1 cases (P<0.01). There was no difference in survival between pN1 and pN2 patients. However, significant differences in survival were observed between pN0/1 and pN2/3 patients when these patients were limited to Binf0/1. Examination of the recurrence pattern showed that most patients with pN0/1/2 had no regional lymph node recurrence, but there was para-aortic lymph node recurrence in patients with pN3 outside the dissected region. Significant prognostic factors influencing survival after surgery by multivariate analysis were pN2/3, pT, and residual tumor. CONCLUSION: Systematic lymph node dissection of N1, N2, and part of the para-aortic region improves survival in advanced gallbladder cancer patients, especially in those without either para-aortic lymph node metastases or Binf2/3.

Adult↗

PubMed2000

Control of interaction strength in a network of the true slime mold by a microfabricated structure.

The plasmodium of the true slime mold, Physarum polycephalum, which shows various nonlinear oscillatory phenomena, for example, in its thickness, protoplasmic streaming and concentration of intracellular chemicals, can be regarded as a collective of nonlinear oscillators. The plasmodial oscillators are interconnected by microscale tubes whose dimensions can be closely related to the strength of interaction between the oscillators. Investigation of the collective behavior of the oscillators under the conditions in which the interaction strength can be systematically controlled gives significant information on the characteristics of the system. In this study, we proposed a living model system of a coupled oscillator system in the Physarum plasmodium. We patterned the geometry and dimensions of the microscale tube structure in the plasmodium by a microfabricated structure (microstructure). As the first step, we constructed a two-oscillator system for the plasmodium that has two wells (oscillator part) and a channel (coupling part). We investigated the oscillation behavior by monitoring the thickness oscillation of the plasmodium in the microstructure with various channel widths. It was found that the oscillation behavior of two oscillators dynamically changed depending on the channel width. Based on the results of measurements of the tube dimensions and the velocity of the protoplasmic streaming in the tube, we discuss how the channel width relates to the interaction strength of the coupled oscillator system.

Animals↗

PubMed2000

Post-translational modification is essential for catalytic activity of nitrile hydratase.

Nitrile hydratase from Rhodococcus sp. N-771 is an alphabeta heterodimer with a nonheme ferric iron in the catalytic center. In the catalytic center, alphaCys112 and alphaCys114 are modified to a cysteine sulfinic acid (Cys-SO2H) and a cysteine sulfenic acid (Cys-SOH), respectively. To understand the function and the biogenic mechanism of these modified residues, we reconstituted the nitrile hydratase from recombinant unmodified subunits. The alphabeta complex reconstituted under argon exhibited no activity. However, it gradually gained the enzymatic activity through aerobic incubation. ESI-LC/MS analysis showed that the anaerobically reconstituted alphabeta complex did not have the modification of alphaCys112-SO2H and aerobic incubation induced the modification. The activity of the reconstituted alphabeta complex correlated with the amount of alphaCys112-SO2H. Furthermore, ESI-LC/MS analyses of the tryptic digest of the reconstituted complex, removed of ferric iron at low pH and carboxamidomethylated without reduction, suggested that alphaCys114 is modified to Cys-SOH together with the sulfinic acid modification of alphaCys112. These results suggest that alphaCys112 and alphaCys114 are spontaneously oxidized to Cys-SO2H and Cys-SOH, respectively, and alphaCys112-SO2H is responsible for the catalytic activity solely or in combination with alphaCys114-SOH.

Amino Acid Sequence↗

PubMed2000

Two-step selective clamping of IVC for removal of hepatocellular carcinoma with intracaval extension.

Hepatocellular carcinoma (HCC) with retrohepatic intracaval extensions are difficult to treat. HCC may sometimes extend into the inferior vena cava (IVC) through two routes: via the right hepatic vein and via the inferior right hepatic vein. In such cases, in which tumor emboli are located both above and below the confluence of the hepatic vein with the IVC, we first remove the upper embolus during THVE, and then remove the lower one while the IVC is clamped obliquely in order to preserve the residual liver circulation.

Carcinoma, Hepatocellular↗

PubMed2000

[Multidisciplinary treatment of hilar cholangiocarcinoma].

With advances in surgical techniques, the number of curative resection for hilar cholangiocarcinoma has increased. However, the recurrence rate after curative resection is significantly high. There is no established adjuvant therapy for these patients, although some groups have administered intraarterial infusion of 5-fluorouracil combined with cisplatin. In our institution, postoperative radiation is administered to control remnant tumors at the ductal and surgical margins. Extracorporeal radiation is directed at the surgical margins and intraluminal radiation at the ductal margins. This has improved the cumulative survival rate for cholangiocarcinoma patients who underwent both curative and noncurative resection. The 3-year survival rate of those who underwent curative resection with and without postoperative radiation is 100% and 28.5%, respectively. The longest survival duration among our patients who received intraluminal radiation for positive ductal margins were 55 months. Because the biological behaviour and radiation sensitivity of the tumors differ among individually, these should be determined through molecular biologic studies in the future. Such tailored therapy will require multidisciplinary treatment.

Bile Duct Neoplasms↗

PubMed1999

Tertiary and quaternary structures of photoreactive Fe-type nitrile hydratase from Rhodococcus sp. N-771: roles of hydration water molecules in stabilizing the structures and the structural origin of the substrate specificity of the enzyme.

The crystal structure analysis of the Fe-type nitrile hydratase from Rhodococcus sp. N-771 revealed the unique structure of the enzyme composed of the alpha- and beta-subunits and the unprecedented structure of the non-heme iron active center [Nagashima, S., et al. (1998) Nat. Struct. Biol. 5, 347-351]. A number of hydration water molecules were identified both in the interior and at the exterior of the enzyme. The study presented here investigated the roles of the hydration water molecules in stabilizing the tertiary and the quaternary structures of the enzyme, based on the crystal structure and the results from a laser light scattering experiment for the enzyme in solution. Seventy-six hydration water molecules between the two subunits significantly contribute to the alphabeta heterodimer formation by making up the surface shape, forming extensive networks of hydrogen bonds, and moderating the surface charge of the beta-subunit. In particular, 20 hydration water molecules form the extensive networks of hydrogen bonds stabilizing the unique structure of the active center. The amino acid residues hydrogen-bonded to those hydration water molecules are highly conserved among all known nitrile hydratases and even in the homologous enzyme, thiocyanate hydrolase, suggesting the structural conservation of the water molecules in the NHase family. The crystallographic asymmetric unit contained two heterodimers connected by 50 hydration water molecules. The heterotetramer formation in crystallization was clearly explained by the concentration-dependent aggregation state of NHase found in the light scattering measurement. The measurement proved that the dimer-tetramer equilibrium shifted toward the heterotetramer dominant state in the concentration range of 10(-2)-1.0 mg/mL. In the tetramer dominant state, 50 water molecules likely glue the two heterodimers together as observed in the crystal structure. Because NHase exhibits a high abundance in bacterial cells, the result suggests that the heterotetramer is physiologically relevant. In addition, it was revealed that the substrate specificity of this enzyme, recognizing small aliphatic substrates rather than aromatic ones, came from the narrowness of the entrance channel from the bulk solvent to the active center. This finding may give a clue for changing the substrate specificity of the enzyme. Under the crystallization condition described here, one 1,4-dioxane molecule plugged the channel. Through spectroscopic and crystallographic experiments, we found that the molecule prevented the dissociation of the endogenous NO molecule from the active center even when the crystal was exposed to light.

Amino Acid Sequence↗

PubMed1999

Liver transplantation for primary sclerosing cholangitis.

Although the development of interventional radiology and biliary surgical techniques has prolonged the survival time of patients with primary sclerosing cholangitis, liver transplantation remains the only effective treatment for patients with primary sclerosing cholangitis with liver cirrhosis. Several prognostic survival models have been establised for this disease, and the efficacy of actual liver transplantations has been reported in comparison with these survival models. One- and 5-year actuarial patient survivals after liver transplantation for primary sclerosing cholangitis were shown to be greater than and approximately equal to 90%, respectively. An association with cholangiocarcinoma is the most adverse factor affecting survival after liver transplantation for primary sclerosing cholangitis, while the association of inflammatory bowel disease or previous bili-ary surgery does not adversely affect the outcome of the liver transplantation. Recurrent sclerosing cholangitis is an important issue for posttransplant patients with primary sclerosing cholangitis, and occurs in 10%-20% of such patients. Although our understanding of recurrent sclerosing cholangitis is still in the early stages, its potential occurrence indicates the need for a longer follow-up period after liver transplantation.

Bile Duct Neoplasms↗

PubMed1999

An enzyme controlled by light: the molecular mechanism of photoreactivity in nitrile hydratase.

Extensive studies have revealed the molecular mechanism of the photoreactivity of nitrile hydratase from Rhodococcus sp. N-771. In the inactive enzyme, nitric oxide is bound to the non-heme ferric iron at the catalytic center, stabilized by a claw-like structure formed by two post-translationally modified cysteines and a serine. The inactive nitrile hydratase is activated by the photoinduced release of the nitric oxide. This result might provide a means of designing novel photoreactive chemical compounds or proteins that would be applicable to biochips and light-controlled metabolic systems.

Crystallography, X-Ray↗

PubMed1999

Functional expression of nitrile hydratase in Escherichia coli: requirement of a nitrile hydratase activator and post-translational modification of a ligand cysteine.

The nitrile hydratase (NHase) from Rhodococcus sp. N-771 is a photoreactive enzyme that is inactivated on nitrosylation of the non-heme iron center and activated on photo-dissociation of nitric oxide (NO). The nitrile hydratase operon consists of six genes encoding NHase regulator 2, NHase regulator 1, amidase, NHase alpha subunit, NHase beta subunit and NHase activator. We overproduced the NHase in Escherichia coli using a T7 expression system. The NHase was functionally expressed in E. coli only when the NHase activator encoded downstream of the beta subunit gene was co-expressed and the transformant was grown at 30 degrees C or less. A ligand cysteine, alphaCys112, of the recombinant NHase was also post-translationally modified to a cysteine-sulfinic acid similar to for the native NHase. Although another modification of alphaCys114 could not be identified because of the instability under acidic conditions, the recombinant NHase could be reversibly inactivated by nitric oxide.

Amino Acid Sequence↗

PubMed1999

Occurrence of free D-amino acids and aspartate racemases in hyperthermophilic archaea.

The occurrence of free D-amino acids and aspartate racemases in several hyperthermophilic archaea was investigated. Aspartic acid in all the hyperthermophilic archaea was highly racemized. The ratio of D-aspartic acid to total aspartic acid was in the range of 43.0 to 49.1%. The crude extracts of the hyperthermophiles exhibited aspartate racemase activity at 70 degrees C, and aspartate racemase homologous genes in them were identified by PCR. D-Enantiomers of other amino acids (alanine, leucine, phenylalanine, and lysine) in Thermococcus strains were also detected. Some of them might be by-products of aspartate racemase. It is proven that D-amino acids are produced in some hyperthermophilic archaea, although their function is unknown.

Amino Acid Isomerases↗

PubMed1998

Characterization of homo-oligomeric complexes of alpha and beta chaperonin subunits from the acidothermophilic archaeon, Sulfolobus sp. strain 7.

The chaperonin from the acidothermophilic archaeon, Sulfolobus sp. Strain 7, is composed of two kinds of subunits designated as Scp alpha and Scp beta. In this study, we characterized the recombinant Scp alpha and Scp beta, which were separately expressed in Escherichia coli. Both of them were able to assemble to homo-oligomeric double-ring complexes, similar to subunits of group II chaperonins from Thermoplasma acidophilum and Thermococcus strain KS-1. Both complexes have no or at most trace ATPase activities. However, they could arrest spontaneous refolding of chemically denatured enzyme in the same way as the purified Sulfolobus chaperonin. We found that they dissociated in the presence of 15% ethanol to monomers, which spontaneously assembled to oligomers when concentrated in the absence of ethanol. Both the reconstituted homo-oligomers were unstable, and easily dissociated to monomers. Further structural and functional characterization is necessary to elucidate if these homo-oligomers exist and if so, their function in vivo.

3-Isopropylmalate Dehydrogenase↗