Biomedical subjects

H Kikuchi

Publications and source records attributed to H Kikuchi.

At least 91 records · Page 5Linked to original sources

PubMed2000

Novel substrate specificity of a membrane-bound beta-glycosidase from the hyperthermophilic archaeon Pyrococcus horikoshii.

A beta-glycosidase gene homolog of Pyrococcus horikoshii (BGPh) was successfully expressed in Escherichia coli. The enzyme was localized in a membrane fraction and solubilized with 2.5% Triton X-100 at 85 degrees C for 15 min. The optimum pH was 6.0 and the optimum temperature was over 100 degrees C, respectively. BGPh stability was dependent on the presence of Triton X-100, the enzyme's half-life at 90 degrees C (pH 6.0) was 15 h. BGPh has a novel substrate specificity with k(cat)/K(m) values high enough for hydrolysis of beta-D-Glcp derivatives with long alkyl chain at the reducing end and low enough for the hydrolysis of beta-linked glucose dimer more hydrophilic than aryl- or alkyl-beta-D-Glcp.

Amino Acid Sequence↗

PubMed2000

A 38 kb segment containing the cdc2 gene from the left arm of fission yeast chromosome II: sequence analysis and characterization of the genomic DNA and cDNAs encoded on the segment.

A genomic 38 kbp segment on the c1750 cosmid clone containing the cdc2 gene, located in the left arm of chromosome II from Schizosaccharomyces pombe, was sequenced. The segment was found to have five previously known genes, pht1, cdc2, his3, act1 and mei4. Among 11 coding sequences (CDSs) predicted by the gene finding software INTRON.PLOT., four CDSs, pi007, pi010, pi014 and pi016, had considerable similarity to 40S ribosomal protein, glycosyltransferase, cdc2-related protein kinase and alpha-1, 2-mannosyltransferase, respectively. Another unusually huge open reading frame (ORF) (pi011), consisting of 2233 amino acids, existed, having significant homology to alpha-amylase, granule-bound glycogen synthase and the Sz. pombe YS 1110 clone product at the N-terminal, middle and C-terminal regions, respectively. All the predicted 11 CDSs were experimentally analysed by RACE PCR. The sequencing of the RACE products revealed that there were two small overlaps at the 3' untranslated regions (UTRs) between pi004 and pi005 (17 bp) and between pi007 and pi008 (2 bp). The distances between 5' end of the 5'UTR and the putative translation initiation codon varied from 10 to 302 nucleotides (nt) among the nine CDSs successfully analysed by 5'-RACE. The expression level of each CDS on this clone was determined. Among the 16 genes on this clone, the previously determined genes, pht1, cdc2, his3 and act1, were found to be most highly expressed. Finally, cDNAs of all the newly identified genes were detected by RACE, proving the actual expression of these genes. The nucleotide sequence has been submitted to the EMBL database under Accession No. AB004534.

Base Sequence↗

PubMed2000

Primary effusion lymphoma with B-cell phenotype.

We describe here a case of primary effusion lymphoma that occurred in a 78-year-old woman. She was successively treated with prednisolone but died 15 months after the diagnosis of primary effusion lymphoma. The immunohistochemistry revealed the neoplastic cells to be CD19(+), CD20(+), CD21(+), Sm-Ig(+), and HLA-DR(+). This patient exhibited clonal IgH and clonal kappa light chain gene rearrangement, indicating a B-cell origin. The present case was distinguished from the majority cases of HHV-8-positive primary effusion lymphoma. Here we present clinical details of response to therapy in this case.

Aged↗

PubMed2000

Ubiquitin-immunoreactive skein-like inclusions in the neostriatum are not restricted to amyotrophic lateral sclerosis, but are rather aging-related structures.

We examined the presence of ubiquitin-immunoreactive skein-like inclusions (SLI) in the neostriatum and spinal cord in normal individuals and patients with different neurodegenerative diseases. Ubiquitin-immunoreactive SLI in the neostriatum were observed both in the normal individuals and in the patients with a variety of neurodegenerative diseases. In particular, SLI were frequently seen in normal aged subjects and certain neurodegenerative diseases, such as progressive supranuclear palsy and myotonic dystrophy. In contrast, the occurrence rate of SLI in cases with Pick's disease and multiple system atrophy tended to decrease. On the other hand, SLI in the spinal anterior horn were detected in cases of amyotrophic lateral sclerosis, but not in any cases with other neurodegenerative diseases. SLI in the neostriatum were also identifiable using phosphotungstic acid-hematoxylin and Gomori trichrome staining. Ubiquitin immunoelectron microscopy demonstrated that the SLI in the neostriatum corresponded to bundles of filaments. These features of SLI in the neostriatum were quite similar to those of intracytoplasmic rod-like inclusions (RLI) in the large neurons of caudate nucleus, which were first described by Kojima and Ogawa in 1974. Our findings indicate that SLI in the neostriatum are ubiquitin-related structures whose occurrence increases by aging, and less frequently accompany several neurodegenerative diseases, and are identical to at least some RLI.

Aging↗

PubMed2000

Distal pancreatectomy with resection of the celiac axis and reconstruction of the hepatic artery for carcinoma of the body and tail of the pancreas.

Distal pancreatectomy with resection of the celiac axis can increase resectability of carcinoma of the body and tail of the pancreas. We performed reconstruction of the hepatic artery to avoid complications caused by a decrease in hepatic arterial flow. We carried out distal pancreatectomy with resection of the celiac axis for carcinoma of the body and tail of the pancreas in four patients. When pulsation in the proper hepatic artery was weak after occlusion of the celiac axis, we performed reconstruction of the hepatic artery, using the splenic artery, which had been taken beforehand from the resected specimen. In two patients, we performed reconstruction of the hepatic artery. These two patients underwent reconstruction of the portal vein combined with prolonged clamping of the portal vein. Levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were elevated just after the operation, but recovered to normal levels within 10 days. No complications related to hepatic ischemia were observed. These results suggested that reconstruction of the hepatic artery allowed us to safely perform distal pancreatectomy with resection of the celiac axis for carcinoma of the body and tail of the pancreas.

Aged↗

PubMed2000

Microwave coagulation therapy for hepatocellular carcinoma.

The efficacy and safety of microwave coagulation therapy (MCT) in patients with hepatocellular carcinoma (HCC) and impaired hepatic reserve were studied. Preoperative background factors, postoperative results, and prognostic factors were compared in 51 patients who underwent hepatic resection (HR group) and 38 patients who underwent microwave coagulation therapy (MCT group). Before surgery, measures of hepatic function, including level of albumin (P = 0.0072), prothrombin time (P<0.0001), hepaplastin test (P = 0.0088), and the radioactivity of technetium-99m galactosyl-human serum albumin 15 min in the liver after injection divided by that in both liver and heart (P <0.0001) were significantly lower in the MCT group than in the HR group. The indocyanine green dye retention rate at 15 min was significantly greater (P<0.0001) in the MCT group than in the HR group, and a significant difference was noted in Child-Pugh grade between the groups (P<0.0001). Operative time (P = 0.0014) and blood loss during surgery (P = 0.0005) were significantly lower in the MCT group than in the HR group. In contrast, no significant differences were recognized between the groups in the changes in postoperative liver function, or in the rates of morbidity, mortality, local recurrence, and survival. Moreover, the type of treatment (HR or MCT) was not a prognostic factor. The results indicate that MCT can be used safely as an alternative to hepatic resection in patients with poor liver function without reducing the efficacy of local control.

Aged↗

PubMed2000

Heparin reduces serum levels of endothelin-1 and hepatic ischemia reperfusion injury in rabbits.

Since the role of heparin in hepatic ischemia/reperfusion (I/R) injury is still not fully understood, we investigated the effects of heparin on hepatic I/R injury in rabbits. Heparin was injected into rabbits after inducing partial hepatic ischemia for 1 h. Thereafter, the serum levels of endothelin-1 (ET-1) and liver transaminase, and tissue levels of oxidized and deoxidized hemoglobin (oxHb, deoxHb) in the reperfused liver were analyzed. Microscopic examinations were also performed. The increased serum levels of ET-1 and liver transaminase after reperfusion were significantly reduced by heparin (P > 0.01). Hepatic ischemia reduced oxHb and increased deoxHb. Reperfusion with heparin immediately reduced deoxHb and increased oxHb, and thereafter the balance between the two kinds of Hb also recovered. However, reperfusion without heparin did not demonstrate any similar recovery, but instead gradually exacerbated the dissociation. Microscopically, heparin appeared to normalize I/R-induced activation of hepatic stellate cells which are the target cells for ET-1. These results suggest that heparin improves the hepatic I/R injury caused by sinusoidal microscirculatory disturbances partly via an inhibition of the ET-1 increase.

Animals↗

PubMed2000

Glutamate dehydrogenase from the aerobic hyperthermophilic archaeon Aeropyrum pernix K1: enzymatic characterization, identification of the encoding gene, and phylogenetic implications.

NADP-dependent glutamate dehydrogenase (L-glutamate: NADP oxidoreductase, deaminating, EC 1.4.1.4) from the aerobic hyperthermophilic archaeon Aeropyrum pernix K1 (JCM 9820) was purified to homogeneity for characterization. The enzyme retained its full activity on heating at 95 degrees C for 30 min, and the maximum activity in L-glutamate deamination was obtained around 100 degrees C. The enzyme showed a strict specificity for L-glutamate and NADP on oxidative deamination and for 2-oxoglutarate and NADPH on reductive amination. The Km values for NADP, L-glutamate, NADPH, 2-oxoglutarate, and ammonia were 0.039, 3.3, 0.022, 1.7, and 83 mM, respectively. On the basis of the N-terminal amino acid sequence, the encoding gene was identified in the A. pernix K1 genome, cloned, and expressed in Escherichia coli. Analysis of the nucleotide sequence revealed an open reading frame of 1257 bp starting with a minor TTG codon and encoding a protein of 418 amino acids with a molecular weight of 46170. Phylogenetic analysis revealed that the glutamate dehydrogenase from A. pernix K1 clustered with those from aerobic Sulfolobus solfataricus, Sulfolobus shibatae, and anaerobic Pyrobaculum islandicum in Crenarchaeota, and it separated from another cluster of the enzyme from Thermococcales in Euryarchaeota. The branching pattern of the enzymes from A. pernix K1, S. solfataricus, S. shibatae, and Pb. islandicum in the phylogenetic tree coincided with that of 16S rDNAs obtained from the same organisms.

Amino Acid Sequence↗

PubMed2000

Significance of a two-domain structure in subunits of phycobiliproteins revealed by the normal mode analysis.

Phycobiliproteins are basic building blocks of phycobilisomes, a supra-molecular assembly for the light-capturing function of photosynthesis in cyanobacteria and red algae. One functional form of phycobiliproteins is a trimeric form consisting of three identical units having C(3) symmetry, with each unit composed of two kinds of subunits, the alpha-subunit and beta-subunit. These subunits have similar chain folds and can be divided into either globin-like or X-Y helices domains. We studied the significance of this two-domain structure for their assembled structures and biological function (light-absorption) using a normal mode analysis to investigate dynamic aspects of their three-dimensional structures. We used C-phycocyanin (C-PC) as an example, and focused on the interactions between the two domains. The normal mode analysis was carried out for the following two cases: 1) the whole subunit, including the two domains; and 2) the globin-like domain alone. By comparing the dynamic properties, such as correlative movements between residues and the fluctuations of individual residues, we found that the X-Y helices domain plays an important role not only in the C(3) symmetry assemblies of the subunits in phycobiliproteins, but also in stabilizing the light absorption property by suppressing the fluctuation of the specific Asp residues near the chromophore. Interestingly, the conformation of the X-Y helices domain corresponds to that of a module in pyruvate phosphate dikinase (PPDK). The module in PPDK is involved in the interactions of two domains, just as the X-Y helices domain is involved in the interactions of two subunits. Finally, we discuss the mechanical construction of the C-PC subunits based on the normal mode analysis.

Amino Acid Sequence↗

PubMed2000