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Biomedical subjects

Y Yamaguchi

Publications and source records attributed to Y Yamaguchi.

At least 217 records · Page 12Linked to original sources
PubMed2000

Glomerular and extraglomerular immune complex deposits in a bone marrow transplant recipient.

A 44-year-old man developed nephrotic syndrome 9 months after HLA-identical sibling bone marrow transplantation. Membranous changes consisted mainly of alterations of glomeruli, which were interpreted as chronic graft-versus-host disease (GVHD) caused by lodging of the circulating immune complex. In the tubules, a lumpy deposition of IgG and complement breakdown products was distributed along the tubular basement membrane, which coincided with the peculiar deposits ascertained by electron microscopy. These findings suggest that an extraglomerular reaction should be considered in evaluating renal involvement of GVHD.

Adult↗
PubMed2000

Deficits of masticatory movements caused by lesions in the orofacial somatosensory cortex of the awake cat.

The purpose of this study was to determine the role of somatosensory cortex (SI) in the control of orofacial movements during eating. We identified perioral and tongue projection regions of the cat SI and destroyed cells in one region by injecting kainic acid. The effects on orofacial behavior were then studied over a period of 4-6 weeks. Cats with unilateral lesions in the perioral region (PL-cats) dropped food from the contralateral side of the mouth in the early phase. Failure in erection of the contralateral whisker hairs during masticatory movements and delay of the masticatory start were observed throughout the experimental period. Furthermore, in the late phase, PL-cats showed prolongations of the masticatory and food intake periods, which were accompanied by the increase in the number of swallows and chewing cycles. Cats with unilateral lesions in the tongue region (TL-cats) showed the prolongation of the masticatory period in the early phase, which was accompanied by the increase in the number of swallows and chewing cycles. TL-cats did not show the prolongation of the food intake period and failure in erection of the contralateral whisker hairs. In both PL- and TL-cats, masticatory and swallowing rhythms were normal.

Animals↗
PubMed2000

The genetic structure of the Raleigh natural population of Drosophila melanogaster revisited.

The Raleigh natural population of Drosophila melanogaster was reanalyzed with special attention to possible dysgenic effects during the extraction of chromosomes. About 600 second chromosomes were extracted from the Raleigh natural population, half in the cytoplasm of wild-caught females (native genetic background) and half in the cytoplasm of the laboratory line, C160(In(2LR)SM1, Cy/In(2LR)bw(V1)) (foreign genetic background). We could not find significant differences between the two extraction schemes in the frequency of lethal second chromosomes (Q = 0.252 for the lines with the negative genetic background vs. 0.231 for the lines with the foreign genetic background) or in the homozygous detrimental (D) and lethal (L) loads (D = 0.210 vs. 0.251; L = 0.287 vs. 0.264). The effective size of the population was estimated to be approximately 19,000, based on the allelism rate of lethal-bearing chromosomes. The homozygous load markedly decreased in the 15 years since a previous study of the same population.

Animals↗
PubMed2000

A sequence motif involved in the donor substrate binding by alpha1,6-fucosyltransferase: the role of the conserved arginine residues.

Alpha1,6-fucosyltransferase catalyzes the transfer of fucose to the innermost GlcNAc residue of an N-linked oligosaccharide. In order to identify the amino acid residue(s) which are associated with the enzyme activity and to investigate their function, we prepared a series of mutant human alpha1,6-fucosyltransferases in which the conserved residues in the region homologous to alpha1,2-fucosyltransferase had been replaced. These proteins were then characterized by kinetic analyses. The wild-type and mutant alpha1,6-fucosyltransferases were expressed using a baculovirus-insect cell system. The activity assay showed that replacement of Arg-365 by Ala or Lys led to a complete loss of activity while substitution of Ala or Lys for the neighboring Arg-366 decreased the activity to about 3% that of the wild type. Kinetic analyses revealed that the replacements of Arg-366 lead to an increase in the apparent K (m) value for both GDP-fucose and the acceptor oligosaccharide but did not markedly affect the apparent V (max). When these mutants were inhibited by GDP in a competitive manner with respect to the donor substrate, the K (i) values were found to be 50-100 times higher than the value in the wild type. On the other hand, in the inhibition by GMP, the K (i) values for the mutants were very similar to that of the wild type. These findings suggest that Arg-366 contributes to the binding of GDP-fucose via an interaction with the beta-phosphoryl group of the GDP moiety of the donor, and that Arg-365 may also play an essential role in substrate binding. The results suggest that the motif common to alpha1,2- and alpha1,6-fucosyltransferases is critical for binding of the donor substrate, GDP-fucose.

Amino Acid Motifs↗
PubMed2000

Genomic structure and promoter analysis of the human alpha1, 6-fucosyltransferase gene (FUT8).

GDP-L-Fuc:N-acetyl-beta-D-glucosaminide alpha1,6-fucosyltransferase (alpha1,6FucT) catalyzes the transfer of a fucosyl moiety from GDP-fucose to the asparagine-linked GlcNAc residue of complex N-glycans via alpha1,6-linkage. We have cloned the genomic DNA which encodes the human alpha1,6FucT gene ( FUT8 ) and analyzed its structure. It was found that the gene consists of at least nine exons spanning more than a 50 kbp genomic region, and the coding sequence is divided into eight exons. The translation initiation codon was located at exon 2, and thus exon 1 encodes only 5'-untranslated sequences. Transcription initiation site of FUT8 was determined by 5'-rapid amplification of the cDNA end and a primer-extension analysis using the total RNA isolated from SK-OV-3 cells, which have a high level of alpha1,6FucT activity. We then characterized the FUT8 promoter region by a reporter gene assay. The luciferase reporter assay indicated that the 5'-flanking region of exon 1, which covered about 1 kbp, conferred the promoter activity in SK-OV-3 cells. This region contains potential binding sites for some transcription factors, such as bHLH, cMyb, GATA-1, as well as a TATA-box, but not a CCAAT motif. 5'-Untranslated sequences found in ESTs and the cDNA for the FUT8 suggest the presence of an additional exon(s) at the upstream of the first exon identified in this study, and therefore, the transcription of the gene would be regulated by multiple promoters.

Base Sequence↗
PubMed2000

Kinetic basis for the donor nucleotide-sugar specificity of beta1, 4-N-acetylglucosaminyltransferase III.

The kinetic basis of the donor substrate specificity of beta1, 4-N-acetylglucosaminyltransferase III (GnT-III) was investigated using a purified recombinant enzyme. The enzyme also transfers GalNAc and Glc moieties from their respective UDP-sugars to an acceptor at rates of 0.1-0.2% of that for GlcNAc, but Gal is not transferred at a detectable rate. Kinetic analyses revealed that these inefficient transfers, which are associated with the specificity of the enzyme, are due to the much lower V(max) values, whereas the K(m) values for UDP-GalNAc and UDP-Glc differ only slightly from that for UDP-GlcNAc. It was also found that various other nucleotide-Glc derivatives bind to the enzyme with comparable affinities to those of UDP-GlcNAc and UDP-Glc, although the derivatives do not serve as glycosyl donors. Thus, GnT-III does not appear to distinguish UDP-GlcNAc from other structurally similar nucleotide-sugars by specific binding in the ground state. These findings suggest that the specificity of GnT-III toward the nucleotide-sugar is determined during the catalytic process. This type of specificity may be efficient in preventing a possible mistransfer when other nucleotide-sugars are present in excess over the true donor.

Acetylgalactosamine↗
PubMed2000

A half-type ABC transporter TAPL is highly conserved between rodent and man, and the human gene is not responsive to interferon-gamma in contrast to TAP1 and TAP2.

TAPL is a half-type ABC transporter with sequence similarity to TAP1 and TAP2 that is transcribed in various rat tissues [Yamaguchi, Y., Kasano, M., Terada, T., Sato, R., and Maeda, M. (1999) FEBS Lett. 457, 231-236]. Primary structures of the human and mouse orthologous counterparts were deduced from cDNAs cloned by means of polymerase chain reaction, and they were compared with that of the rat. The mammalian TAPLs (rat, mouse, and human) are highly conserved, since about 95% of the amino acid residues are identical between rodents and man. Phylogenetic analysis demonstrated that the evolutional rate of TAPL is much slower than those of TAP1 and TAP2, although TAPL could have diverged from an ancestor of TAP1 or that of TAP1 and TAP2. The TAPL-GFP fusion protein transiently expressed in Cos-1 cells was co-localized with PDI, suggesting that TAPL is inserted into endoplasmic reticulum membrane. The conservation of the peptide-binding motifs of TAP proteins in TAPL raises the possibility that the TAPL might be a peptide transporter. The gene for human TAPL is assigned to chromosome 12q24.31-q24.32, while those for TAP1 and TAP2 are located at the MHC locus of chromosome 6p21.!3. Furthermore, the transcription of TAPL gene is not responsive to interferon-gamma, in contrast to TAP1 and TAP2. These results indicate that the gene regulation of TAPL is different from those of TAP1 and TAP2.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2000

Three Arabidopsis genes encoding proteins with differential activities for cysteine synthase and beta-cyanoalanine synthase.

Three cDNA clones encoding putative cysteine synthases (O-acetylserine (thiol) lyase, EC 4.2.99.8) were isolated from Arabidopsis thaliana and designated AtcysC1, AtcysD1 and AtcysD2, respectively. Southern blot analyses suggested that the corresponding genes were present as a single copy, or at most two copies, in the A. thaliana genome. Escherichia coli complementation analyses confirmed that the cDNAs encode cysteine synthase and the corresponding proteins produced in E. coli clearly showed cysteine synthase activity. In addition, AtcysC1 protein showed beta-cyanoalanine synthase (EC 4.4.1.9) activity, but the other two did not. Kinetic analysis suggests that AtcysC1 actually functions as beta-cyanoalanine synthase rather than cysteine synthase in vivo. The mRNA accumulation of AtcysC1, AtcysD1 and AtcysD2 differed in various organs, but did not change markedly when A. thaliana seedlings were subjected to various stresses, including nutrient deprivation. In vivo targeting experiments indicated that AtcysD1 and AtcysD2 are cytoplasmic isozymes, and AtcysC1 is a mitochondrial isozyme.

Amino Acid Sequence↗
PubMed2000

GB virus C/hepatitis G viremia and antibody response to the E2 protein of hepatitis G virus in hemodialysis patients.

The aim of this study was to assess the relationship between the prevalence of GB virus C/hepatitis G virus (GBV-C/HGV) RNA and that of antibody to the putative E2 protein (anti-E2) in hemodialysis patients. GBV-C/HGV RNA in serum was detected by a reverse transcription polymerase chain reaction (RT-PCR) assay, and anti-E2 was measured in 244 hemodialysis patients by enzyme-linked immunosorbent assay using recombinant E2 protein. The GBV-C/HGV RNA level was determined by competitive RT-PCR with an interval of 1 year. GBV-C/HGV RNA, anti-E2. and both together were detected in 11 (4.5%), in 19 (7.8%), and in 3 patients (1.2%), respectively. Comparison of clinical characteristics between GBV-C/HGV RNA-positive patients and negative patients revealed the longer duration of hemodialysis (9.8 years vs. 6.0 years; p < 0.05), and the greater frequency of anti-hepatitis C virus (HCV) (63.6% vs. 20.3%; p < 0.05) and HCV RNA (36.4% vs. 12.9%; p < 0.05) in GBV-C/HGV RNA-positive patients. The GBV-C/HGV RNA levels of patients who were positive for anti-E2 remained under detection limit (< 10(2) copies/mL), whereas only one of eight patients who were negative for anti-E2 showed a GBV-C/HGV RNA level under detection limit (p < 0.05). The presence of anti-E2 in serum was associated with loss of detectable GBV-C/HGV RNA or with a very small amount of HCV RNA in hemodialysis patients.

Antibodies, Viral↗
PubMed2000

Relationship between plasma cytokine concentration and multiple organ failure in patients with acute pancreatitis.

The dynamic aspects of circulating cytokines and cytokine modulators and their relationship with development of multiple organ failure (MOF) in patients with acute pancreatitis were analyzed. All cytokine and C-reactive protein levels in the circulation were higher than those in the MOF group. In particular, plasma concentrations of soluble tumor necrosis factor receptors (sTNF-RI and sTNF-RII) were significantly higher in patients with MOF than in those without even at admission. Furthermore, plasma concentrations of sTNF-Rs and interleukin-1 (IL-1) receptor antagonist (IL-1ra) were much higher than those of their counterparts, TNFalpha and IL-beta, respectively. These results suggest that the plasma concentrations of sTNF-Rs are useful predictors for the development of MOF, and actions of TNF-alpha and IL-1beta could be regulated by their modulators (soluble receptor and receptor antagonist, respectively) in the pathologic condition of severe acute pancreatitis.

Acute Disease↗
PubMed2000

An immunohistochemical analysis of p27 expression in human pancreatic carcinomas.

p27 is known as one of the candidate tumor suppressor genes. Although abnormalities including deletion and mutation in this gene are rarely detected, loss of p27 expression has been reported to be correlated with the high degree of malignancy in many human cancers. In the present study, we investigated the status of p27 expression in human pancreatic carcinoma (PC) and assessed the clinicopathologic significance of loss of p27 expression in the development and progression of this malignancy using immunohistochemistry. No nuclear staining for p27 protein existed in 65 (65.7%) of the 99 PC tumors examined. Furthermore, loss of p27 expression was correlated with tumor grade (G1 versus G2 or G3, p < 0.05) or clinical stage (I and II versus III and IV, p < 0.01). The above data suggest that loss of p27 expression is a very common event in PC, and moreover, this alteration might contribute to the progression of this malignant disease. Key Words: Pancreatic carcinoma-p27 protein expression-Immunohistochemistry.

Cell Cycle Proteins↗
PubMed2000

Ultrastructural and immunohistochemical findings in five patients with vitreomacular traction syndrome.

OBJECTIVE: To evaluate pathologic features of vitreomacular traction syndrome (VMT). METHODS: Preretinal membranes removed from five patients during vitreous surgery for VMT syndrome were evaluated by electron microscopy (n = 4) and immunohistochemistry (n = 1). RESULTS: Electron microscopic examination revealed large segments of internal limiting lamina (ILL) in three of the four cases. Other extracellular features included two types of abnormal collagen fibrils, determined to be type I and fibrous long-spacing collagen. The myofibrocyte was the predominant cell type in all cases. Collagen types I, II, and III, as well as glial fibrillary acidic protein and vimentin, were identified by immunohistochemistry. CONCLUSIONS: Epiretinal membranes in eyes with VMT syndrome adhered tightly to the ILL with abnormal collagen and contractile elements that included myofibrocytes.

Aged↗
PubMed2000

Genome structure of Sagiyama virus and its relatedness to other alphaviruses.

Sagiyama virus (SAG) is a member of the genus Alphavirus in the family Togaviridae, isolated in Japan from mosquitoes in 1956. We determined the complete nucleotide sequence of the SAG genomic RNA from the original stock virus which formed a mixture of plaques with different sizes, and that from a full-length cDNA clone, pSAG2, infectious RNA transcripts from which formed uniform large plaques on BHK-21 cells. The SAG genome was 11698 nt in length exclusive of the 3' poly(A) tail. Between the complete nucleotide sequences of the full-length cDNA clone, pSAG2, and the consensus sequence from the original stock virus, there were nine amino acid differences; two each in nsP1, nsP2 and E1, and three in E2, some of which may be responsible for plaque phenotypic variants in the original virus stock. SAG was most closely related to Ross River virus among other alphaviruses fully sequenced, with amino acid sequence identities of 86% in the nonstructural proteins and of 83% in the structural proteins. The 3' terminal 280 nt region of SAG was 82% identical to that of Barmah Forest virus, which was otherwise not closely related to SAG. Comparison of the nucleotide sequence of SAG with partial nucleotide sequences of Getah virus (GET), which was originally isolated in Malaysia in 1955 and is closely related to SAG in serology and in biology, showed near identity between the two viruses, suggesting that SAG is a strain of GET.

Aedes↗
PubMed2000

[Antibody levels for diphtheria, tetanus and pertussis in young adult females immunized with whole cell pertussis-diphtheria-tetanus toxoid vaccine in infancy].

Antibody levels for diphtheria, tetanus and pertussis in 84 young adult females were measured. They had been immunized with whole cell pertussis-diphtheria-tetanus toxoid (DTwP) vaccine as a routine immunization in their infancy. Their history of DTwP vaccination were confirmed in their Maternal and Child Health Handbook, which includes their immunization record. Among the 84 cases, 4 cases (4.7%) had been immunized with the first dose of DTwP, 5 cases (6.0%) with the second dose, 23 cases (27.4%) with the third dose and 52 cases (61.9%) with the fourth dose. Of the 84 cases, 89.3% had received DTwP vaccine more than the third dose. In the 15-19 years after the last DTwP vaccination, the antibody positive rate for diphtheria and tetanus (> or = 0.01 IU/ml) were 86.9% and 94.0%, respectively. On the other hand, antibody positive rate for anti-pertussis toxin (anti-PT) and anti-filamentous hemaggulutinin (anti-FHA) (> or = 10 EU/ml) were 35.7% and 55.9%, respectively. The positive rate for pertussis compared with those for diphtheria and tetanus were lower. These findings suggested that DTwP vaccination in infancy does not provide sufficient immunity for young adults against pertussis, but DTwP vaccination provides adequate immunity against diphtheria and tetanus.

Adult↗
PubMed2000

Gene cloning and molecular characterization of lysine decarboxylase from Selenomonas ruminantium delineate its evolutionary relationship to ornithine decarboxylases from eukaryotes.

Lysine decarboxylase (LDC; EC 4.1.1.18) from Selenomonas ruminantium comprises two identical monomeric subunits of 43 kDa and has decarboxylating activities toward both L-lysine and L-ornithine with similar K(m) and V(max) values (Y. Takatsuka, M. Onoda, T. Sugiyama, K. Muramoto, T. Tomita, and Y. Kamio, Biosci. Biotechnol. Biochem. 62:1063-1069, 1999). Here, the LDC-encoding gene (ldc) of this bacterium was cloned and characterized. DNA sequencing analysis revealed that the amino acid sequence of S. ruminantium LDC is 35% identical to those of eukaryotic ornithine decarboxylases (ODCs; EC 4.1.1.17), including the mouse, Saccharomyces cerevisiae, Neurospora crassa, Trypanosoma brucei, and Caenorhabditis elegans enzymes. In addition, 26 amino acid residues, K69, D88, E94, D134, R154, K169, H197, D233, G235, G236, G237, F238, E274, G276, R277, Y278, K294, Y323, Y331, D332, C360, D361, D364, G387, Y389, and F397 (mouse ODC numbering), all of which are implicated in the formation of the pyridoxal phosphate-binding domain and the substrate-binding domain and in dimer stabilization with the eukaryotic ODCs, were also conserved in S. ruminantium LDC. Computer analysis of the putative secondary structure of S. ruminantium LDC showed that it is approximately 70% identical to that of mouse ODC. We identified five amino acid residues, A44, G45, V46, P54, and S322, within the LDC catalytic domain that confer decarboxylase activities toward both L-lysine and L-ornithine with a substrate specificity ratio of 0.83 (defined as the k(cat)/K(m) ratio obtained with L-ornithine relative to that obtained with L-lysine). We have succeeded in converting S. ruminantium LDC to form with a substrate specificity ratio of 58 (70 times that of wild-type LDC) by constructing a mutant protein, A44V/G45T/V46P/P54D/S322A. In this study, we also showed that G350 is a crucial residue for stabilization of the dimer in S. ruminantium LDC.

Amino Acid Sequence↗
PubMed2000

Small GTPase RhoG is a key regulator for neurite outgrowth in PC12 cells.

The Rho family of small GTPases has been implicated in cytoskeletal reorganization and subsequent morphological changes in various cell types. Among them, Rac and Cdc42 have been shown to be involved in neurite outgrowth in neuronal cells. In this study, we examined the role of RhoG, another member of Rho family GTPases, in nerve growth factor (NGF)-induced neurite outgrowth in PC12 cells. Expression of wild-type RhoG in PC12 cells induced neurite outgrowth in the absence of NGF, and the morphology of wild-type RhoG-expressing cells was similar to that of NGF-differentiated cells. Constitutively active RhoG-transfected cells extended short neurites but developed large lamellipodial or filopodial structures at the tips of neurites. RhoG-induced neurite outgrowth was inhibited by coexpression with dominant-negative Rac1 or Cdc42. In addition, expression of constitutively active RhoG elevated endogenous Rac1 and Cdc42 activities. We also found that the NGF-induced neurite outgrowth was enhanced by expression of wild-type RhoG whereas expression of dominant-negative RhoG suppressed the neurite outgrowth. Furthermore, constitutively active Ras-induced neurite outgrowth was also suppressed by dominant-negative RhoG. Taken together, these results suggest that RhoG is a key regulator in NGF-induced neurite outgrowth, acting downstream of Ras and upstream of Rac1 and Cdc42 in PC12 cells.

Animals↗