Search PubMed⌕ Search

Biomedical subjects

A Hara

Publications and source records attributed to A Hara.

At least 55 records · Page 3Linked to original sources
PubMed2001

Mechanism of retarded liver regeneration in plasminogen activator-deficient mice: impaired activation of hepatocyte growth factor after Fas-mediated massive hepatic apoptosis.

Urokinase-type plasminogen activator (uPA) is implicated in the regulation of hepatic regeneration by activating hepatocyte growth factor (HGF). Here, we investigated its role in the hepatic regeneration after Fas-mediated massive hepatocyte death employing mice deficient in either uPA or its inhibitor, plasminogen activator inhibitor-1 (PAI-1). We measured kinetics of hepatic levels of proliferating cell nuclear antigen (PCNA)-labeling index, plasmin activity, mature HGF, and its phosphorylated receptor, c-Met. In the genetically targeted and wild-type mice, hepatocytes fell into the same extent of apoptosis 6 to 12 hours after an intraperitoneal injection with anti-Fas antibody, as judged from histologic analysis and a histon-DNA enzyme-linked immunosorbent assay (ELISA). In the wild-type mice, mature HGF emerged in the liver 6 hours following anti-Fas injection, and hepatic PCNA-labeling index started to increase following 24 hours and peaked at 48 hours. In the uPA(-/-) mice, emergence of mature HGF was delayed 12 hours and hepatic regeneration peaked at 96 hours. Supplementation with the uPA gene to the uPA(-/-) mice by in vivo lipofection restored hepatic plasmin levels, and improved a delay in the expression of both mature HGF and phosphorylated c-Met, accompanying a normal rate of liver regeneration. In contrast, PAI-1(-/-) mice showed accelerated liver regeneration; mature HGF emerged as early as 3 hours, and PCNA-labeling index increased at 24 hours. This accelerated regeneration was abolished by administration with anti-HGF antibody. These results strongly suggest a physiologic role of uPA in the proteolytic maturation of HGF, and thereby in hepatic regeneration after Fas-mediated massive hepatocyte death.

Animals↗
PubMed2001

Relationship between circulating high density lipoprotein concentrations and interleukin-6 release during abdominal operations.

OBJECTIVE: To investigate whether circulating high density lipoprotein (HDL) concentrations influence inflammatory cytokine release during abdominal operations. SETTING: University Hospital, Japan. PATIENTS: 30 patients who underwent curative operations for gastric cancer. MAIN OUTCOME MEASURES: Serum HDL and cytokine concentrations were measured preoperatively, and portal and systemic blood samples were taken for the analysis of cytokine and endotoxin concentrations during operations. RESULTS: Portal blood interleukin-6 (IL-6) values of patients with low serum HDL concentrations (n = 6) (< 0.9 mmol/L) were significantly (p < 0.01) higher than those in patients with normal or high HDL concentrations (n = 24) (> or = 0.9 mmol/L) (80.63 (74.62) pg/ml (mean (SD)) compared with 10.25 (9.61) pg/ml.). Moreover, an inverse correlation (r = -0.43, p < 0.05) was found between portal blood IL-6 concentrations and circulating HDL concentrations. CONCLUSIONS: We suggest that serum HDL concentrations influence IL-6 release in response to abdominal operations. Circulating HDL particles may reduce endotoxin-induced IL-6 release in humans.

Aged↗
PubMed2001

Suppression of occurrence and advancement of beta-catenin-accumulated crypts, possible premalignant lesions of colon cancer, by selective cyclooxygenase-2 inhibitor, celecoxib.

Suppression of occurrence and advancement of premalignant lesions is important for cancer prevention. Our previous studies clarified that beta-catenin-accumulated crypts, independent of aberrant crypt foci (ACF), are probably direct precursors of colon cancers in rats. Here we investigated the effects of a selective cyclooxygenase-2 inhibitor, celecoxib, on the development of beta-catenin-accumulated crypts in comparison with those on ACF. Male F344 rats were divided into 4 groups. Groups 1 - 3 were administered azoxymethane (AOM) s.c. at a dose of 15 mg / kg body weight, once weekly for 3 weeks to induce beta-catenin-accumulated crypts. Groups 2 and 3 also received experimental diet containing celecoxib (500 and 1500 ppm, respectively) for 8 weeks, starting a week before the first dosing of AOM. At termination, the frequency and crypt multiplicity (number of crypts / lesion) of beta-catenin-accumulated crypts of groups 2 and 3 were significantly less than that of group 1. Furthermore, numbers of silver-stained nucleolar organizer regions (AgNORs) / nucleus in beta-catenin-accumulated crypts were also decreased by exposure to celecoxib. In this study, celecoxib had greater effects on the frequency and growth of beta-catenin-accumulated crypts than on those of ACF. These findings represent additional evidence that beta-catenin-accumulated crypts are premalignant lesions of colon cancer. The results also suggest that beta-catenin-accumulated crypts could be a novel target for evaluation of possible chemopreventive agents against colon carcino-genesis, and indicate that possible chemopreventive effects of celecoxib on the initial stage of colon carcinogenesis may be related to modulation of cell proliferation activity in such early lesions.

Animals↗
PubMed2001

Loss of DCC expression in astrocytomas: relation to p53 abnormalities, cell kinetics, and survival.

AIMS: Although frequent reduction or loss of DCC (deleted in colorectal carcinomas) has been demonstrated in gliomas, the association with cell kinetics and survival is still unclear. METHODS: A total of 119 astrocytomas, comprising 39 grade IV, 36 grade III, and 44 low grade tumours, were immunohistochemically investigated, along with 26 normal adult brain samples and two fetal brains. The results were compared with p53 abnormalities, Ki-67 labelling index (LI), mitotic index (MI), apoptotic index (AI), and survival. RESULTS: In normal adult and fetal brain tissues, DCC expression was detected in mature and terminally differentiated neuronal cells but not glial elements. In astrocytomas, whereas DCC expression was still clearly shown with low grade malignancy, DCC scores were significantly decreased in high histological grade malignancy, along with an increase in cell kinetics determined by AI, MI, and Ki-67 LI values. In addition, p53 LI values were significantly increased, although a direct link between DCC scores and p53 LI values was not evident. Univariate analysis revealed that high DCC scores and low p53 LI values were closely related to a favourable outcome for astrocytoma, although only the AI was an independent prognostic factor. CONCLUSIONS: The loss of DCC expression may be closely related to changes in cell kinetics and tumour phenotype in astrocytomas, independent of p53 abnormalities.

Adolescent↗
PubMed2001

Poly(adenosine diphosphate-ribose) synthetase inhibitor 3-aminobenzamide alleviates cochlear dysfunction induced by transient ischemia.

The present study was undertaken to determine the possible deleterious role played by poly(adenosine diphosphate-ribose) synthetase (PARS) in cochlear ischemia-reperfusion injury. Transient ischemia of the cochlea was induced in albino guinea pigs for 15, 30, or 60 minutes by pressing the labyrinthine artery at the porus acusticus internus. The animals were given intravenous 3-aminobenzamide (a PARS inhibitor) or physiological saline solution I minute before the onset of reperfusion. The compound action potential thresholds were measured before the onset of ischemia and 4 hours after the onset of reperfusion. A statistically significant reduction in the postischemic compound action potential threshold shift was observed in the animals treated with 3-aminobenzamide after 15 or 30 minutes of ischemia, whereas no statistical difference was found after 60 minutes of ischemia. These results suggest that excessive activation of PARS exerts deleterious effects on the cochlear injury induced by transient ischemia.

Action Potentials↗
PubMed2001

Intralobar bronchopulmonary sequestration: evidence of air trapping shown by dynamic xenon-133 SPECT.

Dynamic single photon emission computed tomography with xenon-133 gas in a 29-year-old male patient showed xenon-133 retention within an intralobar bronchopulmonary sequestration (BPS) with a focal hyperlucent lung area on CT. Left lower lobectomy showed no fistulous connection between the anomalous and normal bronchial trees, but non-contiguous, incompletely developed visceral pleura between the sequestration and the adjacent normally ventilated lung. These features strongly support the role of intralobar collateral air drift and air trapping in producing secondary changes of a focal hyperlucent lung area in BPS.

Adult↗
PubMed2001

Purification and properties of extracellular chitinases from the parasitic fungus Isaria japonica.

Two chitinases (P-1 and P-2) induced with colloidal chitin were purified from the culture supernatant of Isaria japonica by chromatography on DEAE Bio-Gel, chromatofocusing and gel filtration with Superdex 75 pg. The enzymes were electrophoretically homogeneous and estimated to have a molecular mass of 43,273 (+/-5) for P-1 and 31,134 (+/-6) for P-2 by MALDI-MS. The optimum pH and temperature was 3.5-4.0 and 50 degrees C for P-1 and 4.0-4.5 and 40 degrees C for P-2. P-1 acted against chitosan 7B (degree of deacetylation, 65-74%) = glycol chitin > colloidal chitin = chitosan 10B (degree of deacetylation, above 99%) and P-2 against chitosan 7B > glycol chitin = chitosan 10B > colloidal chitin in order of activity. The products of hydrolysis of chitin and chitosan hexamer were analyzed by MALDI-MS. The products from the chitin hexamer obtained with P-1 were almost all dimers with only a small amount of trimer whereas those obtained with P-2 were mainly trimers with some dimer and tetramer. No hydrolysis of chitosan hexamer was observed. High homology in the amino-terminal sequence for chitinase P-1 was exhibited by chitinases from Trichoderma harzianum, Candida albicans and Saccharomyces cerevisiae in the range of 48-39%. The highest homology for Chitinase P-2 was shown by an endochitinase from Metarhizium anisopliae of 66%, while 44% homology was exhibited by chitinases of Leguminosae plants.

Journal Article↗
PubMed2001

Removal of polyA tails from full-length cDNA libraries for high-efficiency sequencing.

We have developed a method to overcome sequencing problems caused by the presence of homopolymer stretches, such as polyA/T, in cDNA libraries. PolyA tails are shortened by cleaving before cDNA cloning with type IIS restriction enzymes, such as GsuI, placed next to the oligo-dT used to prime the polyA tails of mRNAs. We constructed four rice Cap-Trapper-selected, full-length normalized cDNA libraries, of which the average residual polyA tail was 4 bases or shorter in most of the clones analyzed Because of the removal of homopolymeric stretches, libraries prepared with this method can be used for direct sequencing and transcriptional sequencing without the slippage observed for libraries prepared with currently available methods, thus improving sequencing accuracy, operations, and throughput.

Animals↗
PubMed2001

[A case of breast cancer 5 cm in diameter treated with a breast preserving approach after preoperative intra-arterial chemotherapy].

The patient was a 59-year-old female with a mass in the right breast (area C). At the initial examination, the mass was 5.0 x 4.5 cm on palpation, aspiration cytology was Class V, and a diagnosis of T2aN1aM0, Stage II breast cancer was made. Since the patient strongly desired a breast preserving treatment, a reduction in the size of the mass was attempted by local intra-arterial chemotherapy. Docetaxel (TXT) was administered at 60 mg into the internal thoracic artery and lateral thoracic artery at a rate of once a month for a total of 5 times. After the fifth treatment, the mass was reduced in size to 2.8 x 2.5 cm on palpation, and breast-preserving resection was then carried out. On histopathological examination, cancer was observed in an area of 3.0 x 2.2 cm. Careful follow-up is still needed, but preoperative intra-arterial chemotherapy is considered to be significant as a step before breast preserving surgery for breast cancer with a diameter of 3-5 cm.

Antineoplastic Agents, Phytogenic↗
PubMed2001

Confirmation of minor components of less polar neutral and acidic glycolipids in monkey brain tissue.

Crude glycolipids, prepared without alkali treatment in advance, were separated into neutral and acidic glycolipids by DEAE-Sephadex A-25 (acetate form) column chromatography. Each glycolipid was further fractionated by a Silica gel 60-column chromatography. By matrix-assisted laser desorption/ionization time-of-flight mass spectrometry with delayed ion extraction (DE MALDI-TOF MS) of the intact glycolipid fractions, the less polar neutral glycolipids were found to contain alkali-labile ester cerebrosides and Galb-1-Diradylglycerols, whereas the less polar acidic glycolipids were found to contain alkali-labile ester sulfatide, HSO(3)-3Gal-1-Diradylglycerols, and novel alkali-stable plasmalo-sulfatides and ester or plasmalo HSO(3)-3Galb-1-Diradylglycerols as minor components of glycolipids in monkey brain tissue. In conclusion, minor components of less polar neutral and acidic glycolipids in monkey brain tissue were confirmed as ester cerebrosides, Galb-1-Diradylglycerols, ester sulfatides, HSO(3)-3Galb-1-Diradylglycerols, and novel plasmalo-sulfatides and ester or plasmalo HSO(3)-3Galb-1-Diradylglycerols by DE MALDI-TOF MS.

Animals↗
PubMed2000

Kinetic alteration of a human dihydrodiol/3alpha-hydroxysteroid dehydrogenase isoenzyme, AKR1C4, by replacement of histidine-216 with tyrosine or phenylalanine.

Human dihydrodiol dehydrogenase with 3alpha-hydroxysteroid dehydrogenase activity exists in four forms (AKR1C1-1C4) that belong to the aldo-keto reductase (AKR) family. Recent crystallographic studies on the other proteins in this family have indicated a role for a tyrosine residue (corresponding to position 216 in these isoenzymes) in stacking the nicotinamide ring of the coenzyme. This tyrosine residue is conserved in most AKR family members including AKR1C1-1C3, but is replaced with histidine in AKR1C4 and phenylalanine in some AKR members. In the present study we prepared mutant enzymes of AKR1C4 in which His-216 was replaced with tyrosine or phenylalanine. The two mutations decreased 3-fold the K(m) for NADP(+) and differently influenced the K(m) and k(cat) for substrates depending on their structures. The kinetic constants for bile acids with a 12alpha-hydroxy group were decreased 1.5-7-fold and those for the other substrates were increased 1.3-9-fold. The mutation also yielded different changes in sensitivity to competitive inhibitors such as hexoestrol analogues, 17beta-oestradiol, phenolphthalein and flufenamic acid and 3,5,3', 5'-tetraiodothyropropionic acid analogues. Furthermore, the mutation decreased the stimulatory effects of the enzyme activity by sulphobromophthalein, clofibric acid and thyroxine, which increased the K(m) for the coenzyme and substrate of the mutant enzymes more highly than those of the wild-type enzyme. These results indicate the importance of this histidine residue in creating the cavity of the substrate-binding site of AKR1C4 through the orientation of the nicotinamide ring of the coenzyme, as well as its involvement in the conformational change by binding non-essential activators.

3-Hydroxysteroid Dehydrogenases↗
PubMed2000

Roles of His-79 and Tyr-180 of D-xylose/dihydrodiol dehydrogenase in catalytic function.

Mammalian dimeric dihydrodiol dehydrogenase is identical with d-xylose dehydrogenase and belongs to a protein family with prokaryotic proteins including glucose-fructose oxidoreductase. Of the conserved residues in this family, either His-79 or Tyr-180 of d-xylose/dihydrodiol dehydrogenase has been proposed to be involved in the catalytic function. Site-directed mutagenesis was used to examine the roles of the two residues of the monkey enzyme. A mutant, Y180F, was almost inactive, but, similarly to the wild-type enzyme, exhibited high affinity for NADP(H) and fluorescence energy transfer upon binding of NADPH. The H79Q mutation had kinetically largest effects on K(d) (>7-fold increase) and K(m) (>25-fold increase) for NADP(H), and eliminated the fluorescence energy transfer. Interestingly, the dehydrogenase activity of this mutant was potently inhibited with a 190-fold increase in the K(m) for NADP(+) by high ionic strength, which activated the activity of the wild-type enzyme. These results suggest a critical role of Tyr-180 in the catalytic function of this class of enzymes, in addition to functions of His-79 in the coenzyme binding and chemical steps of the reaction.

Animals↗
PubMed2000

Nuclear factor-kappaB activates dual inhibition sites in the regulation of tumor necrosis factor-alpha-induced neutrophil apoptosis.

The objective of this study was to elucidate the role of the nuclear factor-kappaB (NF-kappaB) pathway in tumor necrosis factor-alpha (TNF-alpha)-induced neutrophil apoptosis. A single treatment with TNF-alpha produced significant caspase-3 activation in a time- and concentration-dependent manner, while no significant morphological change in neutrophils was observed. After pretreatment of neutrophils with cycloheximide or actinomycin D, TNF-alpha produced morphologically typical apoptosis in a time- and concentration-dependent manner. Similarly, following pretreatment of neutrophils with the specific NF-kappaB inhibitors, pyrrolidine dithiocarbamate or SN50, TNF-alpha also produced neutrophil apoptosis (assessed morphologically). Caspase-3 activation by TNF-alpha was significantly enhanced by pretreatment with both cycloheximide and pyrrolidine dithiocarbamate. TNF-alpha-induced a rapid phosphorylation and degradation of IkappaB-alpha in neutrophils. Furthermore, TNF-alpha increased NF-kappaB DNA binding, which was abolished by pretreatment with pyrrolidine dithiocarbamate. These results indicate that the NF-kappaB pathway is crucial for neutrophil survival against TNF-alpha cell toxicity. Furthermore, it is proposed that NF-kappaB-induced proteins act on dual inhibitory sites, both upstream and downstream of caspase-3, to protect against apoptosis.

Apoptosis↗
PubMed2000

La autoantigen is cleaved in the COOH terminus and loses the nuclear localization signal during apoptosis.

La autoantigen is a 47-kDa nuclear protein that binds to nascent polymerase III transcripts and a number of viral RNAs. We show that La protein was cleaved to generate a 43-kDa fragment during apoptosis of human leukemic HL-60 cells treated with camptothecin or etoposide. Immunofluorescence microscopy showed that the La protein level was increased in the cytoplasm during apoptosis of HL-60 cells. In addition, UV irradiation of HeLa cells led to the cleavage and redistribution of La protein upon apoptosis. Several lines of evidence show that La protein is cleaved by caspase-3 or closely related proteases at Asp-374 in the COOH terminus. When the full-length (La) and COOH-terminally truncated (La delta C374) forms of La protein were expressed as fusion proteins with green fluorescence protein (GFP), GFP-La delta C374 was predominantly cytoplasmic, whereas GFP-La was localized in the nucleus. These results suggest that La protein loses the nuclear localization signal residing in the COOH terminus upon cleavage and is thus redistributed to the cytoplasm during apoptosis.

Animals↗
PubMed2000

Modifying effects of ferulic acid on azoxymethane-induced colon carcinogenesis in F344 rats.

The modifying effects of dietary administration of ferulic acid (FA) on azoxymethane (AOM)-induced colon carcinogenesis were examined in three experiments with male 344 rats. In the first experiment, the modifying effect of FA on AOM (15 mg/kg body weight, once a week, for 3 weeks)-induced formation of aberrant crypt foci (ACF) was examined in five groups. Numbers of ACF/colon of groups 2 (AOM+250 ppm FA) and 3 (AOM+500 ppm FA) at the termination (5 weeks after the start) were smaller than of group 1 (AOM alone). Those of ACF/cm(2) of group 3 were also smaller than of group 1 (P<0.05). In the second experiment, a long-term assay for the effects of FA was conducted with seven groups. At the termination (35 weeks), groups 2 and 3 which were given FA during the initiation phase at doses of 250 and 500 ppm, respectively, had lower incidences of colonic carcinomas (23 and 27%, respectively) than group 1 which was given AOM alone (59%; P<0.05). In the third experiment, to determine whether FA could modify the activities of phase II detoxifying enzymes, glutathione S-transferase (GST) and quinone reductase (QR) in liver and colon, 60 rats were gavaged with FA at four doses (0, 25, 50, 100 mg/kg body weight). Dosing of 100 mg/kg significantly elevated GST activity in liver (P<0.03), and QR activities in liver and colonic mucosa (P<0.01 and P<0.02, respectively), suggesting that detoxifying enzymes are related to the blocking effect of FA on AOM-induced colon carcinogenesis.

Animals↗
PubMed2000

Decreased expression of CD44, alpha-catenin, and deleted colon carcinoma and altered expression of beta-catenin in ulcerative colitis-associated dysplasia and carcinoma, as compared with sporadic colon neoplasms.

BACKGROUND: To clarify the cell adhesion status in ulcerative colitis (UC)-associated colon neoplasm, expression of cell adhesion molecules were investigated and compared with that of sporadic colon neoplasm. METHODS: A total of 14 low grade dysplasias, 16 high grade dysplasias, and 8 adenocarcinomas associated with UC and 17 sporadic adenomas with mild to moderate dysplasia, 22 adenomas with severe dysplasia, and 15 invasive adenocarcinomas were immunohistochemically examined using monoclonal antibodies against CD44, E-cadherin, alpha- and beta-catenin, and deleted colon carcinoma (DCC). RESULTS: CD44, especially its standard form, and DCC expression was stronger in the sporadic colon neoplasms than in the UC-associated lesions. Although E-cadherin did not show significant differences between the two cases, alpha-catenin was more expressed in sporadic colon adenomas with severe dysplasia and carcinomas than in their UC-associated counterparts. Membranous beta-catenin staining was stronger in UC-associated neoplasms, whereas sporadic lesions had greater cytoplasmic and nuclear expression. CONCLUSIONS: The differences in cell adhesion molecule expression suggests that UC-associated and sporadic colon neoplasms arise from different pathways of tumorigenesis.

Cadherins↗