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Akira Yamaguchi

Publications and source records attributed to Akira Yamaguchi.

71 records · Page 4Linked to original sources
PubMed2003

T-cell receptor variable gamma chain gene expression in the interaction between rat gammadelta-type T cells and heat-shock protein 70-like molecule.

We previously reported that rat T-cell receptor (TCR) Vdelta6 of T-cell hybridomas was preferentially involved in recognition of the cell surface-expressed 70 kDa rat heat-shock cognate (hsc70, a constitutively expressed member of the hsp 70 family) protein-like molecule (#067 molecule). In the present study, we analyzed usage of the TCR Vgamma family of #067-restricted T-cell hybridomas. Our data indicated that most of these hybridomas expressed transcripts of TCR Vgamma1 and/or Vgamma2. However, some of the Vgamma2 transcripts were out-of-frame, suggesting that the TCR Vgamma1 family may be important for the recognition of #067-defined molecules. TCR Vgamma1 transcripts were detected in not only #067-restricted T-cell hybridomas, but #067-non restricted ones as well. However, V-J nucleotide sequences of #067-restricted and #067-non restricted T-cell hybridomas suggested that #067-restricted T-cell hybridomas showed limited insertion of nucleotide stretch as compared with #067-non restricted ones. In terms of amino acids, only one amino acid was added in #067-restricted T-cell hybridomas, whereas two or three amino acids were added in #067-non restricted ones. These data suggest that the heterodimer of the TCR relatively short stretch form of Vgamma1 molecule and TCR Vdelta6 may participate in recognition of the #067 molecule.

Animals↗
PubMed2003

P300/CBP acts as a coactivator to cartilage homeoprotein-1 (Cart1), paired-like homeoprotein, through acetylation of the conserved lysine residue adjacent to the homeodomain.

UNLABELLED: The paired-like homeoprotein, Cart1, is involved in skeletal development. We describe here that the general coactivator p300/CBP controls the transcription activity of Cart1 through acetylation of a lysine residue that is highly conserved in other homeoproteins. Acetylation of this residue increases the interaction between p300/CBP and Cart1 and enhances its transcriptional activation. INTRODUCTION: Cart1 encodes a paired-like homeoprotein expressed selectively in chondrocyte lineage during embryonic development. Although its target gene remains unknown, gene disruption studies have revealed that Cart1 plays an important role for craniofacial bone formation as well as limb development by cooperating with another homeoprotein, Alx4. In this report, we study the functional involvement of p300/CBP, coactivators with intrinsic histone acetyltransferase (HAT) activity, in the transcriptional control of Cart1. METHODS: To study the transcription activity of Cart1, a reporter construct containing a putative Cart1 binding site was transiently transfected with the expression vectors of each protein. The interaction between p300/CBP and Cart1 was investigated by glutathione S-transferase (GST) pull-down, yeast two-hybrid, and immunoprecipitation assays. In vitro acetylation assay was performed with the recombinant p300-HAT domain and Cart1 in the presence of acetyl-CoA. RESULTS AND CONCLUSIONS: p300 and CBP stimulate Cart1-dependent transcription activity, and this transactivation is inhibited by E1A and Tax, oncoproteins that suppress the activity of p300/CBP. Cart1 binds to p300 in vivo and in vitro, and this requires the homeodomain of Cart 1 and N-terminal 139 amino acids of p300. Confocal microscopy analysis shows that Cart1 recruits overexpressed and endogenous p300 to a Cart1-specific subnuclear compartment. Cart1 is acetylated in vivo and sodium butyrate and trichostatin A, histone deacetylase inhibitors, markedly enhance the transcription activity of Cart1. Deletion and mutagenesis analysis identifies the 131st lysine that locates immediately adjacent to the homeodomain as a target of p300-HAT, and a point mutation to this residue attenuates the binding affinity to p300 as well as p300-dependent transcription activity. Together, these results indicate that p300/CBP acts as a cotransactivator to Cart1 through a direct interaction and specific lysine acetylation. In addition, because 131st lysine is highly conserved in other types of homeoprotein, this lysine may be a common target for HAT of p300/CBP for these proteins.

Acetylation↗
PubMed2003

[Non-ischemic tumor enucleation for renal angiomyolipoma: a case report].

A case of renal angiomyolipoma, successfully treated with non-ischemic tumor enucleation, is reported. A 16-year-old Japanese female visited another hospital with a chief complaint of general fatigue. She was diagnosed with angiomyolipoma of the right kidney, 7 cm in the long axis, which developed exteriorly at the lower pole. A nephrectomy was recommended. The patient visited us for a second opinion. We judged that nephron-sparing surgery was applicable to this case. The patient underwent non-ischemic tumor enucleation using a microwave tissue coagulator via retroperitoneal approach. The patient was discharged from our hospital 9 days after the surgery. Since a preoperative diagnosis with renal angiomyolipoma can be obtained relatively easily, maximum efforts for nephron-sparing surgery should be made.

Adolescent↗
PubMed2002

Quantum tunneling of magnetization in a new [Mn18]2+ single-molecule magnet with s = 13.

The reaction between 2-(hydroxyethyl)pyridine (hepH) and a 2:1 molar mixture of [Mn3O(O2CMe)6(py)3](ClO4) and [Mn3O(O2CMe)6(py)3](py) in MeCN leads to isolation of [Mn18O14(O2CMe)18(hep)4(hepH)2(H2O)2](ClO4)2 (1) in 10% yield. The complex is 2MnII,16MnIII and consists of a Mn4O6 central unit to either side of which is attached a Mn7O9 unit. Magnetization data collected in the 2.0-4.0 K and 20-50 kG ranges were fit to yield S = 13, g = 1.86, and D = -0.13 cm-1 = -0.19 K, where D is the axial zero-field splitting parameter. AC susceptibility studies in the 0.04-4.0 K range at frequencies up to 996 Hz display out-of-phase (chiM' ') signals, indicative of a single-molecule magnet (SMM). Magnetization vs applied DC field scans exhibit hysteresis at <1.0 K, confirming 1 to be a SMM. DC magnetization decay data were collected on both a microcrystalline sample and a single crystal, and the combined data were used to construct an Arrhenius plot. Between 3.50 and 0.50 K, the relaxation rate is temperature-dependent with an effective barrier to relaxation (Ueff) of 14.8 cm-1 = 21.3 K. Below ca. 0.25 K, the relaxation rate is temperature-independent at 1.3 x 10-8 s-1, indicative of quantum tunneling of magnetization (QTM) between the lowest energy Ms = +/-13 levels of the S = 13 state. Complex 1 is both the largest spin and highest nuclearity SMM to exhibit QTM.

Journal Article↗
PubMed2002

A new source of basaltic meteorites inferred from Northwest Africa 011.

Eucrites are a class of basaltic meteorites that share common mineralogical, isotopic, and chemical properties and are thought to have been derived from the same parent body, possibly asteroid 4 Vesta. The texture, mineralogy, and noble gas data of the recently recovered meteorite, Northwest Africa (NWA) 011, are similar to those of basaltic eucrites. However, the oxygen isotopic composition of NWA011 is different from that of other eucrites, indicating that NWA011 may be derived from a different parent body. The presence of basaltic meteorites with variable oxygen isotopic composition suggests the occurrence of multiple basaltic meteorite parent bodies, perhaps similar to 4 Vesta, in the early solar system.

Africa↗
PubMed2002

Sonic hedgehog is involved in osteoblast differentiation by cooperating with BMP-2.

The roles of Sonic hedgehog (Shh) and Bone morphogenetic protein-2 (Bmp-2) in osteoblast differentiation were investigated using in vitro cell systems. Recombinant amino-terminal portion of SHH (rSHH-N) dose dependently stimulated ALP activity in C3H10T1/2 and MC3T3-E1 cells. rSHH-N induced expression of Osteocalcin mRNA in C3H10T1/2 cells. A soluble form of the receptor for type IA BMP receptor antagonized rSHH-N-induced ALP activity in C3H10T1/2 and MC3T3-E1 cells, indicating that BMPs are involved in SHH-induced osteoblast differentiation. Simultaneous supplement with rSHH-N and BMP-2 synergistically induced ALP activity and expression of Osteocalcin mRNA in C3H10T1/2 cells. Pretreatment with rSHH-N for 6 h enhanced the response to BMP-2 by increasing ALP activity in C3H10T1/2 and MC3T3-E1 cells. Stimulatory effects of rSHH-N and additive effects with rSHH-N and BMP-2 on ALP activity were also observed in mouse primary osteoblastic cells. Transplantation of BMP-2 (1 microg) into muscle of mice induced formation of ectopic bone, whereas transplantation of r-SHH-N (1-5 microg) failed to generate it. These results indicate that Shh plays important roles in osteoblast differentiation by cooperating with BMP.

Alkaline Phosphatase↗
PubMed2002

Effects of skeletal loading on bone mass and compensation mechanism in bone: a new insight into the "mechanostat" theory.

We have suggested that: (i) osteocalcin carboxylation is related to bone material properties (bone quality), and (ii) impairment of bone material properties could be compensated by bone mass increase. The aim of the present prospective study was to investigate whether the effects of skeletal loading on bone mass were associated with the compensation mechanism between bone mass and bone material properties. The subjects were 56 healthy female volunteers aged around 50 years. They were classified into pre- and postmenopausal groups, and each group was then subdivided into a no-exercise (control) and a vertical jumping exercise group. Bone mineral density (BMD) was measured at baseline and after the 6-month study period. Urinary gamma-carboxyglutamate (Gla), a possible parameter of osteocalcin carboxylation, was also measured at baseline. Among the premenopausal women, hip BMD in the exercise group increased significantly in comparison to the control value. Among the postmenopausal women, however, there was no significant difference in the BMD change between the control and the exercise group. In addition, the baseline urinary Gla level showed an inverse correlation with the change in whole body BMD in the premenopausal exercise group. These results suggest that: (i) estrogen plays a certain role in the high-impact exercise-induced bone gain, and (ii) the effects of skeletal loading on bone mass are involved in the compensation mechanism, i.e., bone gain due to high-impact exercise becomes greater in accordance with the degree of deterioration in bone material properties. Our concept of the compensation mechanism could provide a new insight into the understanding of the skeleton's adaptability to load-bearing.

1-Carboxyglutamic Acid↗
PubMed2002

Functional domains of paired-like homeoprotein Cart1 and the relationship between dimerization and transcription activity.

BACKGROUND: Cart1 encodes the paired-like homeodomain in the central portion of the gene, and plays a crucial role in the developmental lineage of bone and cartilage, especially in head formation. However, its transactivation mechanism is still poorly understood, including the target gene. Here, we report biochemical dissections of Cart1 functional domains and a relationship between dimerization and transcription activity. RESULTS: Deletion studies of GAL4-fused Cart1 indicated that the transactivation domain is located in the middle portion of the C-terminal domain, but the N-terminal is also required for a full activation of the consensus palindromic binding site (TAATNNNATTA). Analysis of the basic amino acid residues at both ends of the homeodomain revealed that both sides act as nuclear localization signals, and are necessary for the cooperative binding to the palindromic sequence. In this study, two additional Cart1 isoforms that behave as dominant negatives were identified from rat chondrosarcoma cells. These isoforms suppressed the transcription activity of the wild-type, despite loss of DNA binding ability, and could interact with the wild-type in yeast. Finally, we demonstrated that wild-type Cart1 forms a DNA-independent homodimer in in vivo conditions, and that the transactivation of wild-type Cart1 was suppressed by the N- or C-terminal domain which was expressed in the nucleus. CONCLUSION: These results revealed that homodimerization through direct interaction is necessary for the potent transcription activity of Cart1.

Amino Acid Motifs↗
PubMed2002

Mucoepidermoid carcinoma arising in Warthin's tumor of the parotid gland.

Malignant transformation of Warthin's tumor is extremely rare, although it is the second most common benign tumor of the parotid gland. We describe our experience of mucoepidermoid carcinoma arising in Warthin's tumor of the parotid gland in a 64-year-old man. He had a swelling in the left parotid-masseteric region. The removed tumor was well encapsulated and histopathologically comprised Warthin's tumor and low-grade mucoepidermoid carcinoma. The mucoepidermoid carcinoma infiltrated lymphoid stroma of the Warthin's tumor, but capsular invasion is not found. Considering the clinical course and physical examination, the lesion was diagnosed as mucoepidermoid carcinoma arising in Warthin's tumor because its features filled the criteria of malignant transformation of Warthin's tumor. There has been no recurrence or distant metastasis for 19 months. Histological change from Warthin's tumor to mucoepidermoid carcinoma may be implicated in squamous or goblet cell metaplasia of epithelial cells. It is considered that the neoplastic cells of Warthin's tumor acquire malignant genotypes simultaneously with this dual differentiation.

Adenolymphoma↗
PubMed2002

Spontaneously ruptured multilocular cystic nephroma.

Multilocular cystic nephroma is a relatively rare benign tumor of the kidney. An adult case of spontaneously ruptured multilocular cystic nephroma was reported. A 33-year-old woman who presented with a right flank colic attack. The preoperative diagnosis was spontaneously ruptured renal tumor. A right nephrectomy was performed. A multilocular cystic lesion, 10 cm in diameter, was found in the removed specimen, which had a hematoma inside and direct tumor extension into the renal pelvis. On microscopic examination, the surface of loculi was covered by a layer of hobnail epithelium, and septa were composed of fibrous tissue with dilated vessels, lacking in normal renal components. There were no signs of malignancy. The lesion extending into the renal pelvis showed the same microscopic findings. The final diagnosis was multilocular cystic nephroma. Two respects, spontaneous rupture and tumor extension into the renal pelvis, were unique to the present case. There has been no report of spontaneously ruptured mutilocular cystic nephroma. The tumor extension into the renal pelvis, however, has been found in several reports. This growth pattern might be one of the characteristics of this benign renal tumor.

Adult↗
PubMed2002

Comparison of parameters to determine the cause of urinary disturbance in men with prostate volume less than 20 milliliters.

BACKGROUND: A pressure-flow study, although a slightly invasive procedure, can evaluate bladder outlet obstruction and detrusor contractility. This study was conducted in men with a non-enlarged prostate to determine the cause of urinary disturbance by less invasive examinations that might eventually replace pressure-flow study. METHODS: Thirty-six men with lower urinary tract symptoms were enrolled. Their prostate volume, estimated by transrectal ultrasonography, was less than 20 mL. All patients were examined using pressure-flow study, free-flowmetry, transrectal ultrasonography, prostate specific antigen and an interview using the International Prostate Symptom Score and Quality of Life Index. With determination of the cause for urinary disturbance, parameters that correlated with outflow obstruction or impaired detrusor contractility were sought. RESULTS: Twenty-one (60%) of the 36 men were judged as having outflow obstruction, and 16 of these 21 men had normal detrusor function. Impaired detrusor contractility was observed in 17 men. Only three of these 17 men had no outflow obstruction. Four patients had an unstable bladder. All these four had normal detrusor contractility, but had outflow obstruction. Among the parameters examined, only the maximum flow rate in a flow metrogram (Qmax) correlated significantly with the degree of outflow obstruction (P = 0.04). The positive predictive value of Qmax for outflow obstruction was 65% at a flow rate of less than 10 mL/s, and 100% at that of less than 5 mL/s. No parameter correlated with detrusor contractility. CONCLUSION: The only parameter that was a clear indicator of outflow obstruction was Qmax. Other indicators of detrusor contractility should be sought.

Aged↗
PubMed2002

Natural antigenic peptides from squamous cell carcinoma recognized by autologous HLA-DR8-restricted CD4+ T cells.

A large number of human tumor antigens recognized by CD8+ cytotoxic T lymphocytes (CTL) have been identified. Some of them have been employed in clinical trials and have achieved some objective responses. However, little is known about those that are recognized by CD4+ T cells, except for a very few that were identified from melanomas. Previously, we reported that an oral squamous cell carcinoma (SCC) cell line, OSC-20, was effectively lysed by HLA-DRB1*08032 (HLA-DR8)-restricted autologous CD4+ T cell line, TcOSC-20. In this study, we performed two steps of chromatographic purification of the tumor cell lysate in combination with mass spectrometry. We found one reverse-phase high-performance liquid chromatography (RP-HPLC) fraction that was effectively recognized by the T cells. We analyzed the fraction by nano-liquid chromatography/electrospray ionization ion trap mass spectrometry (LC/MS/MS) and found six representative ions. We could determine the primary amino acid sequence of each of the six ions. Three of them contained a potential HLA-DR8 binding motif, and TcOSC-20 showed a rather strong cytotoxic response to one of the synthetic peptides, namely, amino acid residues 321-336 of human alpha-enolase. Thus, several gene products of squamous cancer cells are endogenously processed and may be presented on HLA class II molecules, so that they could constitute target molecules for autologous CD4+ T cells.

Amino Acid Motifs↗
PubMed2002

Involvement of Fas/Fas ligand in the induction of apoptosis in chronic sialadenitis of minor salivary glands including Sjögren's syndrome.

The role of apoptosis and contribution of Fas/FasL systems in the pathogenesis of Sjogren's syndrome (SS) are still controversial. With serial sections, we explored apoptosis assessed by the dUTP nick end labeling (TUNEL) method and expression of Fas and FasL by immunohistochemistry, and compared their distribution in minor salivary gland (MSG) of SS and sialolithiasis (SIL) patient tissues. Fas and FasL were co-localized in ductular and acinar cells of SS and SIL TUNEL+ cells co-distributed with the Fas and FasL expressing cells in ductular and acinar cells of SS in the vicinity of lymphocytic infiltration, while not in those of SIL Moreover, to morphologically confirm apoptosis, we identified TUNEL-positive(+) cells in the MSGs of SS at the ultra structural level by applying an inversion method to paraffin-embedded sections stained by TUNEL method. Surprisingly, these cells did not show characteristic apoptotic figures although TUNEL products were deposited on the hyperchromatin of acinar and ductular cells. On the other hand, acinar and ductular cells of SIL included clusters of TUNEL+ apoptotic bodies as did those cells by phagocytosis or having fallen into the ductular lumen. These findings suggest that Fas and FasL expressed in ducts and acini of chronic sialadenitis in SS patients induce apoptosis, possibily in an autocrine and/or paracrine manner.

Apoptosis↗
PubMed2002

[Vascular calcification and bone-related factors].

Bone is consisted of bone matrix proteins produced by osteoblasts and minerals, Recently, it has been reported that bone-related factors are also involved in vascular calcification. Among bone matrix proteins, osteopontin and matrix Gla protein play important roles in vascular calcification. Regulatory factors for osteoblast differentiation (BMP) and osteoclast differentiation (osteoprotegerin) are also involved in vascular calcification.

English Abstract↗
PubMedDate not supplied

Effects of bisphosphonate on bone reaction after placement of titanium implants in tibiae of ovariectomized rats.

PURPOSE: This study was undertaken to investigate the action of bisphosphonate on bone reactions after the placement of titanium screw implants into the tibiae of ovariectomized rats. MATERIALS AND METHODS: Twelve-week-old female Wistar rats were divided into 4 groups of 18 animals each. The first group (Sham) was sham-operated, the second group (OVX) was ovariectomized only, the third group (Estrogen) was ovariectomized and received continuous estrogen with a 17beta-estradiol pellet, and the fourth group (YM-175) was ovariectomized and received bisphosphonate at a dose of 10 microg/kg of body weight. Titanium screw implants were placed in the proximal metaphyses of the tibiae 168 days after surgery. The animals were sacrificed 7, 14, and 56 days after implant placement. Undecalcified sections were prepared and evaluated by light microscopy. Histomorphometric measurements were obtained with a computer-based image analyzer to quantify the unit bone mass around the implant and the rate of implant-bone contact. RESULTS: Ovariectomies significantly reduced implant-bone contact and the bone volume around the implants. However, in the YM-175 group, only slight differences in both bone contact and bone volume were noted compared with the Sham and Estrogen group. The woven structure of new bone in the YM-175 group was also replaced by mature lamellar bone, as in the other groups. DISCUSSION AND CONCLUSION: These results suggested that bisphosphonate preserved the implant-bone contact and bone volume around the implants.

Animals↗