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Biomedical subjects

Akiko Saito

Publications and source records attributed to Akiko Saito.

At least 19 recordsLinked to original sources

All-trans retinoic acid induces in vitro angiogenesis via retinoic acid receptor: possible involvement of paracrine effects of endogenous vascular endothelial growth factor signaling.

A natural retinoid all-trans retinoic acid (ATRA) regulates a variety of important cellular functions via retinoic acid receptor (RAR). ATRA has therapeutically been used against various malignancies including acute promyelocytic leukemia. Recently ATRA has also been recognized to be beneficial against atherosclerotic vascular disorders. However, its effects on angiogenesis remain controversial. We therefore examined ATRA effects on in vitro angiogenesis in terms of capillary-like tube formation using human umbilical vein endothelial cells (HUVECs)/normal human dermal fibroblast (NHDF) coculture. ATRA as well as RAR agonist Am80 significantly induced capillary-like tube formation. The ATRA-induced tube formation was inhibited by coincubation with RAR antagonist LE540/LE135. HUVEC proliferation, but not its migration, was also induced by ATRA. The ATRA-induced tube formation was completely abolished by coincubation with vascular endothelial growth factor (VEGF) neutralizing antibody or with VEGF receptor (VEGFR)-2 (KDR) neutralizing antibody, but not VEGFR-1 (Flt-1) neutralizing antibody. ATRA and Am80 induced VEGF secretion in the coculture as well as VEGF secretion/mRNA expression in NHDFs. Transcription activity of human VEGF gene promoter in NHDFs was stimulated by ATRA, which was augmented by RAR overexpression. ATRA also induced VDGFR-2/KDR mRNA expression in HUVECs. Moreover, ATRA-induced secretion of hepatocyte growth factor as well as angiopoietin-2 in the coculture. Taken together, ATRA may have induced angiogenesis via RAR mainly by stimulation of HUVEC proliferation and enhancement of endogenous VEGF signaling and in part by induction of hepatocyte growth factor and angiopoietin-2 production. Retinoids may therefore be potential candidates for therapeutic angiogenesis against ischemic vascular disorders.

Angiopoietin-2↗

Hepatocellular carcinoma with a central scar and a scalloped tumor margin resembling focal nodular hyperplasia in macroscopic appearance.

BACKGROUND: We sometimes encounter hepatocellular carcinoma (HCC) with a central scar and a scalloped tumor margin resembling focal nodular hyperplasia (FNH) in macroscopic appearance. The fibrolamellar variant sometimes shows this appearance; however, this type of HCC can be clearly differentiated from fibrolamellar variants on the basis of clinical and histopathological findings. The clinical features of patients with this type of HCC need to be clarified. METHODS: From 1988 to 1999, 1,043 patients with HCC underwent hepatectomy at our institution. Histopathological examinations show that fibrolamellar HCC was not included in the series. We selected HCC with a central scar and a scalloped tumor margin resembling FNH in macroscopic appearance. We refer to such tumors as scalloped HCC. We compared the clinical findings and surgical outcomes between patients with scalloped HCC and patients with simple nodular HCC. RESULTS: Of the 1,043 cases of HCC, 31 (3%) and 571 (55%) were scalloped HCC and simple nodular HCC, respectively. The mean age of the patients with scalloped HCC was 60.7 years, and that of the patients with simple nodular HCC was 62.6 years, without significant difference. The rates of hepatitis C virus infection and liver cirrhosis and serum alpha-fetoprotein levels were significantly lower, and Child-Pugh class and surgical outcomes were significantly better in patients with scalloped HCC than in those with simple nodular HCC. In multivariate analysis, Child-Pugh class (P < 0.001), tumor size (P = 0.046), and gross appearance (P = 0.009) were independent significant prognostic factors. CONCLUSION: HCC with a central scar and a scalloped tumor margin resembling FNH occurs in non-cirrhotic patients in their 60s and is associated with a good surgical outcome.

Aged↗

An animal model of intrauterine growth retardation induced by synthetic thromboxane a(2).

OBJECTIVE: Intrauterine growth retardation (IUGR) is an important cause of prenatal and neonatal morbidity, and neurologic abnormalities. Although several animal models of IUGR have been developed for scientific investigation, few models approximate the pathophysiology in human fetal growth failure resulting from pregnancy-induced hypertension and preeclampsia. We developed an animal model of IUGR in which fetal growth restriction was induced by administering a synthetic thromboxane A(2) analogue (STA(2)) to the mother. METHODS: Timed pregnant Sprague-Dawley rats were used in this study. STA(2) was delivered into the peritoneal cavity of the pregnant female at a rate of 20 ng/h from day 13 of pregnancy. The effectiveness of this model was evaluated by monitoring the overall growth of the fetuses and neonates and measuring the weight and biochemical composition of individual organs. RESULTS: Fetuses and neonates from the STA(2) group showed a highly significant weight reduction throughout the observation period from day 19 of gestation to postnatal day 7. Weight reduction near and at term exceeded 10% and became more pronounced during the first week after birth. Fetuses on the 20th gestational day exhibited a pattern of growth retardation characteristic of asymmetrical IUGR in which the weight reduction was prominent in the liver with relative sparing of the brain. However, the decrease in brain weight was more than 10%. The protein, DNA, and RNA contents of the liver were lower in the STA(2) group. The protein content of the forebrain and brainstem also decreased significantly in the STA(2) group compared with the control; however, the DNA content of the forebrain was higher in the STA(2) group. CONCLUSIONS: This animal model may mimic human IUGR more closely than previous models because the growth restriction is induced in a truly chronic manner.

Animals↗

Molecular cloning and characterization of mouse aquaporin 6.

In the rat kidney, aquaporin (AQP) 6 is localized in the intracellular vesicle membranes of type-A intercalated cells of the collecting duct; mouse AQP6 (mAQP6) has not been characterized. Although mAQP6 was originally cloned from cDNA in a mouse cerebellum library (GenBank NM 175087), we have independently cloned a cDNA encoding mAQP6 from an adult kidney cDNA library (C57BL/6J strain). We identified two different spliced variants of mAQP6: mAQP6a and mAQP6b. The mAQP6a isoform is almost identical to that of rat AQP6, whereas mAQP6b is identical to that reported in the mouse cerebellum library mentioned above. We found that the mRNA expression of these two spliced variants is regulated in a tissue-specific and age-dependent manner. Functional analyses of water and ion permeation revealed that mAQP6a functions like rat AQP6 and that mAQP6b does not function as either a water channel or an ion channel under our experimental conditions.

Amino Acid Sequence↗

Abnormal expression of proteoglycans in Ullrich's disease with collagen VI deficiency.

Patients with Ullrich's disease have generalized muscle weakness, multiple contractures of the proximal joints, and hyperextensibility of the distal joints. Recently we found a marked reduction of fibronectin receptors in the skin and cultured fibroblasts of two patients with Ullrich's disease with collagen VI deficiency, and speculated that an abnormality of cell adhesion may be involved in the pathogenesis of the disease. In this study, we investigated the expression of proteoglycans and adhesion molecules in Ullrich's disease and other muscle diseases. We found a reduction of NG2 proteoglycan in the membrane of skeletal muscle but not in the skin in Ullrich's disease. By contrast, we found the upregulation of tenascin C in the extracellular matrix of skeletal muscle in Ullrich's disease. Our findings suggest that abnormal expression of proteoglycans and adhesion molecules may be involved in the pathogenesis of the dystrophic muscle changes in Ullrich's disease.

Adult↗

Catechin conjugated with fatty acid inhibits DNA polymerase and angiogenesis.

Catechins in green tea have anticancer and antiangiogenesis activities, with epigallocatechin-3-gallate (EGCG) being the most potent antiangiogenic tea catechin. This study examined whether chemical modification of catechin enhanced anticancer and antiangiogenic effects. Catechin, conjugated with fatty acid (acyl-catechin), strongly inhibited DNA polymerase, HL-60 cancer cell growth, and angiogenesis. Catechin conjugated with stearic acid [(2R,3S)-3',4',5,7-tetrahydroxyflavan-3-yl octadecanoate; catechin-C18] was the strongest inhibitor in DNA polymerase alpha and beta and angiogenesis assays. Catechin-C18 also suppressed human endothelial cell (HUVEC) tube formation on the reconstituted basement membrane, suggesting that it affected not only DNA polymerases but also signal transduction pathways in HUVECs. These data indicate that acyl-catechins target both DNA polymerases and angiogenesis as anticancer agents. These results suggest that acylation of catechin is an effective chemical modification to improve the anticancer activity of catechin.

Acylation↗

Upregulation of nitric oxide production in vascular endothelial cells by all-trans retinoic acid through the phosphoinositide 3-kinase/Akt pathway.

BACKGROUND: A natural retinoid all-trans retinoic acid (ATRA) contains various beneficial effects on vasculature, including suppression of neointima formation after balloon injury. However, little is known about the effects of ATRA on vascular endothelial function. We therefore studied its role in nitric oxide (NO) production of vascular endothelial cells (ECs). METHODS AND RESULTS: Human dermal microvascular ECs, human umbilical vein ECs, and SV40-transformed rat lung vascular ECs were incubated with or without ATRA (1 micromol/L) for 48 hours. Their NO production was determined with the use of a fluorescent NO indicator, diaminofluorescein-2 diacetate. ATRA significantly increased their basal as well as acetylcholine-induced NO production. Treatment with Nomega-nitro-L-arginine methyl ester or carboxy-PTIO suppressed their fluorescence. Increase of NO production was also observed by incubation with retinoic acid receptor (RAR) agonist Am580. ATRA-induced NO increase was abolished by coincubation with RAR antagonist LE540. Moreover, the NO increase was completely inhibited by the phosphoinositide 3-kinase (PI3K) inhibitor wortmannin and LY294002. ATRA as well as Am580 enhanced endothelial NO synthase (eNOS) phosphorylation at Ser-1177 as well as Akt phosphorylation at Ser-473 without changing their protein expression. Overexpression of dominant-negative Akt inhibited the eNOS phosphorylation. Moreover, ATRA increased PI3K activity as well as PI3K catalytic subunit p110beta protein expression, which was completely inhibited by LE540 treatment. Real-time polymerase chain reaction analyses demonstrated that ATRA increased PI3K catalytic subunit p110beta mRNA expression without affecting its stability. Finally, ATRA-induced NO increase was observed in COS-1 cells transfected with wild-type eNOS and RARalpha, but not with mutated eNOS whose Ser-1177 was substituted. CONCLUSIONS: ATRA increases NO production by eNOS phosphorylation through RAR-mediated PI3K/Akt pathway activation in vascular ECs and possibly plays beneficial roles in vascular endothelium. Retinoids may therefore be candidates as novel therapeutic agents against vascular disorders with endothelial damage.

Cells, Cultured↗

Structural analysis of catechin derivatives as mammalian DNA polymerase inhibitors.

The inhibitory activities against DNA polymerases (pols) of catechin derivatives (i.e., flavan-3-ols) such as (+)-catechin, (-)-epicatechin, (-)-gallocatechin, (-)-epigallocatechin, (+)-catechin gallate, (-)-epicatechin gallate, (-)-gallocatechin gallate, and (-)-epigallocatechin gallate (EGCg) were investigated. Among the eight catechins, some catechins inhibited mammalian pols, with EGCg being the strongest inhibitor of pol alpha and lambda with IC(50) values of 5.1 and 3.8 microM, respectively. EGCg did not influence the activities of plant (cauliflower) pol alpha and beta or prokaryotic pols, and further had no effect on the activities of DNA metabolic enzymes such as calf terminal deoxynucleotidyl transferase, T7 RNA polymerase, and bovine deoxyribonuclease I. EGCg-induced inhibition of pol alpha and lambda was competitive with respect to the DNA template-primer and non-competitive with respect to the dNTP (2'-deoxyribonucleotide 5'-triphosphate) substrate. Tea catechins also suppressed TPA (12-O-tetradecanoylphorbol-13-acetate)-induced inflammation, and the tendency of the pol inhibitory activity was the same as that of anti-inflammation. EGCg at 250 microg was the strongest suppressor of inflammation (65.6% inhibition) among the compounds tested. The relationship between the structure of tea catechins and the inhibition of mammalian pols and inflammation was discussed.

Animals↗

Systematic synthesis of galloyl-substituted procyanidin B1 and B2, and their ability of DPPH radical scavenging activity and inhibitory activity of DNA polymerases.

Six galloyl-substituted procyanidin B1 and B2, 3-O-gallate, 3''-O-gallate, and 3,3''-di-O-gallate, were systematically synthesized with the condensation method using TMSOTf as a catalyst. Their ability of DPPH radical scavenging activity and DNA polymerase inhibitory activity were also investigated. The results indicated that the galloyl group of these compounds is very important for both activities. 3,3''-Di-O-gallate dimers acted as strong inhibitor against DNA polymerase alpha and beta, whereas the desgalloyl and monogalloyl compounds did not exhibit any appreciable inhibitory activity against the DNA polymerase beta.

Animals↗

Clinicopathologic features of patients with primary malignant hepatic tumors seropositive for alpha-fetoprotein-L3 alone in comparison with other patients seropositive for alpha-fetoprotein-L3.

BACKGROUND: Patients with hepatocellular carcinoma (HCC) seropositive for lectin-reactive alpha-fetoprotein (AFP-L3) have a poor prognosis. However, there have been no studies of the clinicopathologic features of patients seronegative for both AFP and des-gamma-carboxy prothrombin (DCP), and seropositive for AFP-L3 alone in comparison with other patients seropositive for AFP-L3. METHODS: Patients with primary malignant hepatic tumors seropositive for AFP-L3 who underwent hepatectomy (n = 84) were divided into four groups, and their clinicopathologic features were compared: (i) group A, seronegative for AFP <100 ng/mL and DCP <40 mAU/mL; (ii) group B, seropositive for AFP > or =100 ng/mL and seronegative for DCP; (iii) group C, seronegative for AFP and seropositive for DCP > or =40 mAU/mL; and (iv) group D, seropositive for AFP and DCP. RESULTS: Among the 14 group A patients seropositive for AFP-L3 alone with low AFP concentrations, three had intrahepatic cholangiocarcinoma (ICC), one had a cholangiolocellular carcinoma, one had combined HCC and ICC, and one had undifferentiated hepatic sarcoma. Group A had a higher incidence of non-HCC tumors (P < 0.001) and tumors derived from cholangiocytes (P < 0.001) than the other three groups. They also had a high frequency of poorly differentiated tumors and sarcomatous changes, and showed a poor prognosis. CONCLUSIONS: Patients with primary malignant hepatic tumors seropositive for AFP-L3 alone with low AFP concentrations have unique clinicopathologic features. Thus, we should be aware of these patients and should measure AFP-L3 levels, at least once, even in those seronegative for both AFP and DCP.

Adenocarcinoma↗

Systematic synthesis of four epicatechin series procyanidin trimers and their inhibitory activity on the Maillard reaction and antioxidant activity.

A systematic synthesis of four natural epicatechin series procyanidin trimers [[4,8:4",8"]-2,3-cis-3,4-trans: 2",3"-cis-3",4"-trans: 2,3-trans-(-)-epi-catechin-(-)-epicatechin-(+)-catechin, [4,8:4",8"]-2,3-cis-3,4-trans: 2",3"-cis-3",4"-trans: 2,3-cis-tri-(-)-epicatechin: procyanidin C1, [4,8:4",8"]-2,3-cis-3,4-trans: 2",3"-trans-3",4"-trans: 2,3-trans-(-)-epicatechin-(+)-catechin-(+)-catechin: procyanidin C4, and [4,8:4",8"]-2,3-cis-3,4-trans: 2",3"-trans-3",4"-trans: 2,3-cis-(-)-epicatechin-(+)-catechin-(-)-epicatechin] is described. Condensation of (2R,3R,4S)-5,7,3'4'-tetra-O-benzyl-4-(2"-ethoxyethyloxy)flavan derived from (-)-epicatechin as an electrophile with the dimeric nucleophiles in the presence of TMSOTf followed by deprotection yielded trimers. Inhibitory activities on the Maillard reaction and antioxidant activity on lipid peroxide of the synthesized oligomers were also investigated.

Antioxidants↗

Favorable surgical outcomes in patients with early hepatocellular carcinoma.

BACKGROUND: Early hepatocellular carcinoma (HCC) is defined as well-differentiated HCC with an obscure tumor margin in the classification of the Liver Cancer Study Group of Japan. However, the surgical outcomes in patients with early HCC have not yet been clarified. METHODS: From 1985 to 1994, 186 patients with HCC 2 cm or less in greatest dimension underwent curative hepatectomy. Of the 186 cases, 37 were early HCC and 149 were small advanced HCC. The relationship between clinicopathological findings and surgical outcomes was examined. RESULTS: The rate of hepatitis C antibody or number of tumors was significantly higher in patients with early HCC than in patients with small advanced HCC. Liver function test showed no differences between patients with early HCC and patients with small advanced HCC. The 5-and 10-year survival rates were 85% and 61%, respectively, in patients with early HCC, which was significantly better than in patients with small advanced HCC (P = 0.0137). Univariate and multivariate analysis showed Child-Pugh class, intrahepatic metastasis, and early HCC to be significant prognostic factors. CONCLUSIONS: Patients with early HCC had a different clinical background and good surgical outcomes; therefore, it should be recognized that early HCC is a distinct clinicopathological entity.

Carcinoma, Hepatocellular↗

Comparative analysis of clinical outcomes after allogeneic bone marrow transplantation versus peripheral blood stem cell transplantation from a related donor in Japanese patients.

A reduced incidence of graft versus host disease (GvHD) has been documented among Japanese allogeneic bone marrow transplantation (BMT) patients, as the Japanese are genetically more homogeneous than western populations. To clarify whether this ethnic difference affects the results of allogeneic peripheral blood stem cell transplantation (PBSCT), we conducted a nationwide survey to compare clinical outcomes of allogeneic PBSCT (n = 214) and BMT (n = 295) from a human leucocyte antigen-identical-related donor in Japanese patients. The cumulative incidence of grades II-IV acute GvHD was 37.4% for PBSCT and 32.0% for BMT. The cumulative incidence of extensive chronic GvHD at 1 year was significantly higher after PBSCT than BMT (42% vs. 27%; P < 0.01). The organ involvement patterns of GvHD were different between the two groups. By multivariate analyses, the incidence of chronic GvHD was significantly increased in PBSCT, whereas the stem cell source did not affect the incidence of acute GvHD, transplant-related mortality, relapse or survival. We concluded that Japanese PBSCT patients have an increased risk of chronic GvHD compared with BMT patients, but the incidence of acute GvHD was still lower than in western populations. Thus, the choice of haematopoietic stem cell source should be considered based on data for individual ethnic populations.

Acute Disease↗

Protective effects of quercetin and its metabolites on H2O2-induced chromosomal damage to WIL2-NS cells.

We investigated chromosomal damage caused by a typical flavonoid, quercetin, and its two conjugates, quercetin-3-O-sulfate and isorhamnetin, and their protective effects against chromosomal damage induced by H2O2. The chromosomal damage was detected by the cytokinesis-block micronucleus (CBMN) assay using a lymphoblastoid cell line, WIL2-NS. We found that quercetin itself induced chromosomal damage at 10 microM, but quercetin-3-O-sulfate and isorhamnetin did not induce damage up to 30 microM. In the medium used for the CBMN assay, quercetin (at 100 microM) generated a high concentration of H2O2, but the two conjugates did not at the same concentration. On the other hand, pretreatment with quercetin (at 1 microM), quercetin-3-O-sulfate (at 10 microM), and isorhamnetin (at 5 microM) prevented H2O2-induced chromosomal damage to WIL2-NS cells. These findings suggest that the induction and prevention of H2O2-induced chromosomal damage are different between quercetin and its metabolites.

Antioxidants↗

Histopathologically-diagnosed splenic metastasis in a hepatocellular carcinoma case with adrenal metastasis.

We encountered a patient with hepatocellular carcinoma (HCC), with adrenal gland metastasis, in whom splenic metastasis was diagnosed histopathologically. A 59-year-old man visited our hospital in May 2001 with chief complaints of abdominal distension and pretibial pitting edema. Multiple HCCs associated with HCV-positive liver cirrhosis were detected. Transarterial embolization (TAE) was performed a total of 4 times for HCCs. A left adrenal gland metastatic lesion was detected and it was found to increase in diameter from 3 cm to 6 cm over a four-month period; left adrenalectomy was performed in June 2002. Because of marked splenomegaly and findings of hypersplenism, the spleen was also resected. Although no metastatic lesions were evident on macroscopic examination of the spleen, a small metastatic lesion from moderately differentiated HCC, approximately 0.5 mm in diameter, was detected histopathologically. Splenic metastasis from HCC is rare, usually occurring with metastases involving other organs. Our patient also had adrenal gland metastasis. Therefore, hematogenous metastasis to the congested spleen via the systemic circulation was suspected.

Adrenal Gland Neoplasms↗

Covalent binding of oxidized cholesteryl esters to protein: implications for oxidative modification of low density lipoprotein and atherosclerosis.

It has been proposed that plasma low density lipoproteins (LDL) undergo oxidative modification before they can produce foam cells in atherosclerosis. The oxidation of LDL generates a variety of reactive aldehydic products, which covalently bind to the LDL apolipoprotein B-100 (apoB). In the present study, to investigate the mechanisms contributing to the modification of LDL, we analyzed oxidized cholesteryl esters generated during the autoxidation of LDL and characterized their covalent binding to the lysine residues of LDL apoB. In addition, we raised a monoclonal antibody specific to a lysine-bound oxidized cholesteryl ester and determined its production in human atherosclerotic lesions. The peroxidation of LDL with Cu2+ produced 9-oxononanoylcholesterol (9-ONC) and 5-oxovaleroylcholesterol as the major oxidized cholesteryl esters. We observed that the levels of 9-ONC and 5-oxovaleroylcholesterol peaked at 12 h and significantly decreased thereafter. The reduction of the core aldehyde levels was accompanied by (i) the formation of free 7-ketocholesterol and 7-ketocholesteryl ester core aldehydes and (ii) an increase in the amounts of apoB-bound cholesterol and 7-ketocholesterol, suggesting that the cholesteryl ester core aldehydes were further converted to their 7-ketocholesterol- and apoB-bound derivatives. To detect the protein-bound 9-ONC, we raised the monoclonal antibody 2A81, directed against 9-ONC-modified protein, and found that it extensively recognized protein-bound cholesteryl ester core aldehydes. Agarose gel electrophoresis followed by immunoblot analysis of the oxidized LDL clearly demonstrated the formation of antigenic structures. Furthermore, immunohistochemical analysis of the atherosclerotic lesions from the human aorta showed that immunoreactive materials with mAb 2A81 were indeed present in the lesions, in which the intense immunoreactivity was mainly located in the macrophage-derived foam cells and the thickening neointima of the arterial walls. The results of this study suggest that the binding of cholesteryl ester core aldehydes to LDL might represent the process common to the oxidative modification of lipoproteins.

Aldehydes↗

Low frequency of CD94/NKG2A+ T lymphocytes in patients with HTLV-1-associated myelopathy/tropical spastic paraparesis, but not in asymptomatic carriers.

Human natural killer (NK)-cell receptors are expressed by NK cells and some T cells, primarily TCR+CD8+ cytotoxic T lymphocytes (CTLs). Inhibitory NK cell receptors (iNKRs) can down-regulate antigen-mediated T-cell effector functions, including cytotoxic activity and cytokine release. In the present study we demonstrate that CD3+ T cells that bind tetramers of HLA-E and express its ligand, the NK-cell inhibitory receptor CD94/NKG2A, were significantly decreased in frequency in patients with human T-cell lymphotropic virus 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) but not in asymptomatic HTLV-1 carriers. These cells were either alphabeta or gammadelta T cells. T-cell receptor (TCR) Vbeta-specific reverse transcription-polymerase chain reaction and spectratyping analysis revealed that the TCR repertoire in directly isolated HLA-E tetramer-positive cells from peripheral blood mononuclear cells was skewed in both HTLV-1-infected and healthy individuals. However, oligoclonally or monoclonally expanded levels of TCR Vbetawere more frequently detected within HTLV-1-infected individuals than healthy controls. Importantly, HLA-E tetramer-positive or NKG2A+ T cells from HTLV-1 patients do not express Tax and display different TCR usage from the immunodominant Tax11-19-specific CD8+ T cells, suggesting that they do not encounter HTLV-1-infected cells. The expression of NK cell-associated receptors by clonally expanded CD8+ T cells during chronic viral infection suggests that these receptors play a role in regulating CD8+ T cell-mediated antiviral immune responses and that a decrease of this cell subset results in an increased risk of inflammatory diseases such as HAM/TSP.

Antigens, CD↗