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Biomedical subjects

S Maeda

Publications and source records attributed to S Maeda.

At least 145 records · Page 8Linked to original sources
PubMed2000

Helicobacter pylori CagA protein can be tyrosine phosphorylated in gastric epithelial cells.

Attachment of Helicobacter pylori to gastric epithelial cells induces various cellular responses, including the tyrosine phosphorylation of an unknown 145-kD protein and interleukin 8 production. Here we show that this 145-kD protein is the cagA product of H. pylori, an immunodominant, cytotoxin-associated antigen. Epithelial cells infected with various H. pylori clinical isolates resulted in generation of tyrosine-phosphorylated proteins ranging from 130 to 145 kD in size that were also induced in vitro by mixing host cell lysate with bacterial lysate. When epithelial cells were infected with [(35)S]methionine-labeled H. pylori, a radioactive 145-kD protein was detected in the immunoprecipitates with antiphosphotyrosine antibody or anti-CagA (cytotoxin-associated gene A) antibody. Consistently, the 145-kD protein recognized by the anti-CagA and antiphosphotyrosine antibodies was induced in epithelial cells after infection of wild-type H. pylori but not the cagA::Km mutant. Furthermore, the amino acid sequence of the phosphorylated 145-kD protein induced by H. pylori infection was identical to the H. pylori CagA sequence. These results reveal that the tyrosine-phosphorylated 145-kD protein is H. pylori CagA protein, which may be delivered from attached bacteria into the host cytoplasm. The identification of the tyrosine-phosphorylated protein will thus provide further insights into understanding the precise roles of CagA protein in H. pylori pathogenesis.

Amino Acid Sequence↗
PubMed2000

Evolutionary conservation of apoptosis mechanisms: lepidopteran and baculoviral inhibitor of apoptosis proteins are inhibitors of mammalian caspase-9.

We cloned a new inhibitor of apoptosis protein (IAP) homolog, SfIAP, from Spodoptera frugiperda Sf-21 cells, a host of insect baculoviruses. SfIAP contains two baculovirus IAP repeat domains followed by a RING domain. SfIAP has striking amino acid sequence similarity with baculoviral IAPs, CpIAP and OpIAP, suggesting that baculoviral IAPs may be host-derived genes. SfIAP and baculoviral CpIAP inhibit Bax but not Fas-induced apoptosis in human cells. Their apoptosis-suppressing activity in mammalian cells requires both baculovirus IAP repeat and RING domains. Further biochemical data suggest that SfIAP and CpIAP are specific inhibitors of mammalian caspase-9, the pinnacle caspase in the mitochondria/cytochrome c pathway for apoptosis, but are not inhibitors of downstream caspase-3 and caspase-7. Thus the mechanisms by which insect and baculoviral IAPs suppress apoptosis may involve inhibition of an insect caspase-9 homologue. Peptides representing the IAP-binding domain of the Drosophila cell death protein Grim abrogated human caspase suppression by SfIAP and CpIAP, implying evolutionary conservation of the functions of IAPs and their inhibitors.

Amino Acid Sequence↗
PubMed2000

Changes with age in proteoglycan synthesis in cells cultured in vitro from the inner and outer rabbit annulus fibrosus. Responses to interleukin-1 and interleukin-1 receptor antagonist protein.

STUDY DESIGN: Proteoglycan synthesis was examined in cells isolated from the inner and outer annulus fibrosus of young and old rabbits. Their responses to interleukin-1 alpha and interleukin-1 receptor antagonist protein were investigated. OBJECTIVES: To evaluate the age-related changes and the anatomically related differences in the function of intervertebral disc cells. SUMMARY OF BACKGROUND DATA: Proteoglycan content in the human intervertebral disc decreases with age. Age-related changes in intervertebral disc cell function, however, have not been fully investigated. METHODS: Japanese white rabbits aged 2 months (young group) and 3 years (old group) were used. The inner and outer layer of the annulus fibrosus were separated. The proteoglycan synthesis and release were measured in cells cultured with or without human recombinant interleukin-1 alpha and interleukin-1 receptor antagonist protein. RESULTS: The proteoglycan synthesis significantly decreased and the release rate significantly increased in the old rabbits, compared with the young ones. In the inner annulus, the inhibition of proteoglycan synthesis due to interleukin-1 alpha was greater in the old rabbits than in the young ones. In the old rabbits, interleukin-1-induced inhibition was more pronounced in the inner annulus than in the outer annulus. Interleukin-1 receptor antagonist protein suppressed inhibition of proteoglycan synthesis by interleukin-1 alpha in the two layers in both age groups. CONCLUSIONS: Both the decline in proteoglycan synthesis and the increased cell sensitivity to interleukin-1 alpha with age may contribute to the degradation of discs. The increase in cell response to interleukin-1 alpha in the inner annulus of rabbits may explain why the inner annulus and nucleus pulposus degrade earlier than the outer annulus in human discs. Interleukin-1 receptor antagonist protein could be useful in inhibiting the degradation of the disc.

Age Factors↗
PubMed2000

Flat-elevated and depressed, subtypes of flat early colorectal cancers, should be distinguished by their pathological features.

Flat-type colorectal tumors have are being detected with increasing frequency. It has become clear that these flat lesions contain two subtypes; flat-elevated and depressed lesions. However, their clinicopathological features and roles in colorectal carcinogenesis remain obscure. We classified colorectal adenomas and submucosal invasive cancers into three types: polypoid, flat-elevated, and depressed types. A clinicopathological study of 2505 colorectal tumors (2407 adenomas, 98 submucosal invasive cancers) was then performed. Furthermore, 64 tumors (25 adenomas with high-grade dysplasia, 39 submucosal invasive cancers) from which DNA was extracted were examined for K-ras gene mutation. The percentages of each configuration in the resected materials were 62.0%, 36.4%, and 1.6% of the polypoid, flat-elevated, and depressed types, respectively. The rate of submucosal invasive cancer in the depressed type was always high regardless of size. In the polypoid and flat-elevated types, lesions of larger size showed higher rates of invasion. Analysis of submucosal invasive cancers revealed no adenomatous components in any of the depressed-type lesions; in the polypoid and flat-elevated types the frequencies of cancer with adenomatous components were 83.6% and 77.8%, respectively. The flat-elevated type was more frequently located (77.8%) in the proximal colon than the other types (polypoid type 16.4%, depressed type 25.0%). The incidence of K-ras gene mutation was 47.2%, 18.2%, and 0% in the polypoid, flat-elevated, and depressed types, respectively. These findings suggest that the flat-elevated and depressed types are similar in that they are both morphologically flat and have infrequent incidences of K-ras gene mutation, but these two lesions differ in their pathological features. Especially, depressed type lesions have a tendency to invade the submucosal layer even when they are small. Therefore one should always be aware of this type of lesion during colonoscopic examination.

Adenoma↗
PubMed2000

Monosynaptic inputs from the nucleus tractus solitarii to the laryngeal motoneurons in the nucleus ambiguus of the rat.

The cricothyroid (CT) and the posterior cricoarytenoid (PCA) muscles in the larynx are activated by the laryngeal motoneurons located within the nucleus ambiguus; these motoneurons receive the laryngeal sensory information from the nucleus tractus solitarii (NTS) during respiration and swallowing. We investigated whether the neurons in the NTS projected directly to the laryngeal motoneurons, and what is the synaptic organization of their nerve terminals on the laryngeal motoneurons using the electron microscope. When wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) was injected into the NTS after cholera toxin subunit B-conjugated HRP (CT-HRP) was injected into the CT muscle or the PCA muscle, the anterogradely WGA-HRP-labeled terminals from the NTS were found to directly contact the retrogradely CT-HRP-labeled dendrites and soma of both the CT and the PCA motoneurons. The labeled NTS terminals comprised about 4% of the axosomatic terminals in a section through the CT motoneurons, and about 9% on both the small (PCA-A) and the large (PCA-B) PCA motoneurons. The number of labeled axosomatic terminals containing round vesicles and making asymmetric synaptic contacts (Gray's type I) was almost equal to that of the labeled terminals containing pleomorphic vesicles and making symmetric synaptic contacts (Gray's type II) on the CT motoneurons. The labeled axosomatic terminals were mostly Gray's type II on the PCA-A motoneurons, while the majority of them were Gray's type I on the PCA-B motoneurons. These results indicate that the laryngeal CT and PCA motoneurons receive a few direct excitatory and inhibitory inputs from the neurons in the NTS.

Animals↗
PubMed2000

Viral serostatus and coexisting inflammatory activity affect metachronous carcinogenesis after hepatectomy for hepatocellular carcinoma. A further report.

Little data are available regarding the effects of hepatitis virus serostatus and the severity of coexisting chronic inflammation on intrahepatic recurrence after hepatectomy for hepatocellular carcinoma (HCC). We investigated the extent to which these factors modified the prognosis of hepatectomized patients. A total of 274 patients treated in the period January 1981 to December 1996 were divided into three groups: antihepatitis C-positive (HCV; n = 144), hepatitis B surface antigen-positive and HCV antibody (Ab)-negative (HBsAg; n = 106), and HBsAg-negative and HCV Ab-negative (NBNC; n = 20). Positivity for HBV-related antibody in the HCV group was 76%. Histologic grading of inflammatory activity from coexisting hepatitis was determined according to Knodel's histological activity index (HAI) scoring system. Post-hepatectomy crude survival rates and disease-free survival (DFS) rates were compared, according to tumor characteristics, between the three groups. In the patients overall and also in the patients with a single nodular HCC, the HCV group had significantly higher HAI scores and preoperative serum aspartate aminotransaminase (AST) levels than the other two groups. When the patients were limited to those with a single nodular HCC, the crude survival was similar in the three groups with comparable tumor characteristics; however, the DFS was different (NBNC > HBsAg > HCV). When the patients were further limited to those with a single nodular HCC without microscopic extracapsular spread, in whom removal of the tumor was expected to be microscopically complete, the difference in the DFS became more marked. Irrespective of the viral serostatus, better crude and disease-free survivals were observed in the patients with lower AST levels (< or =50 IU/ 1) than in those with higher AST levels (>50IU/l). In contrast, there were no differences in survivals and HAI scores according to the presence or absence of HBV-related antibody in the HCV group. From our univariate analysis, we can conclude that the severity of virally induced inflammation, which was well correlated with viral serostatus, may be a factor that affects intrahepatic recurrence, which is more likely to originate from metachronous carcinogenesis. Prior co-infection of HBV in HCV patients may not be an adverse risk factor for intrahepatic recurrence.

Carcinoma, Hepatocellular↗
PubMed2000

Evolution of and obstacles in surgical treatment for hepatocellular carcinoma over the last 25 years: differences over four treatment eras.

This study was designed to clarify what differences the last 25 years have made in surgical results for patients with hepatocellular carcinoma (HCC). We examined results for 716 hepatectomized patients in four treatment eras: first era (1973-1980; n = 58), second era (1981-1985; n = 155), third era (1986-1990; n = 243), and fourth era (1991-1997; n = 260). Patient background, tumor characteristics, type of hepatectomy, treatment for intrahepatic recurrences, and surgical results in the four eras were compared by univariate analysis to clarify the factors that have contributed to or impeded progress in the surgical treatment of HCC. Although there were no significant chronological differences in liver pathology and surgical resectability, operative mortality was reduced to 2% in the fourth era, from 29% in the first era. With an increasing proportion of early-stage HCCs (TNM, stages I and II), the cumulative survival rate at 5 years improved in the course of the eras in our overall population of patients (12%, 31%, 38%, and 51%, respectively, for the first, second, third, and fourth eras) and in a subset of the population divided according to tumor stage. Also, we found a chronological improvement in the survival rate at 3 years after intrahepatic recurrence (10%, 28%, 36%, and 44%, respectively in the first second, third, and fourth eras). This improvement was associated with the establishment of an early detection program for intrahepatic recurrences. However, the recurrence rate was similar in any subset of the population through the four eras. Although this univariate study could not determine independent factors that contributed to the chronological progress in results for HCC surgery in the four eras, it is conceivable that the establishment of indication criteria for hepatectomy, an early detection program for primary and recurrent lesions, and the introduction of multimodal treatment for recurrence were contributory factors in this improvement. A strategy for alleviating the frequent recurrences originating from posthepatectomy metachronous carcinogenesis remains to be established.

Analysis of Variance↗
PubMed2000

Baculovirus infection blocks the progression of fat body degradation during metamorphosis in Bombyx mori.

The effect of baculovirus infection into silkworm pupa particularly on programmed fat body degradation during metamorphosis was investigated. Pupal fat body degradation did not occur following infection with Bombyx mori nucleopolyhedrovirus (BmNPV). There were no histolytic differences between the fat body tissues of mock and BmNPV infected papae until 48 h postinfection (p.i.). Between 48 and 72 h p.i., significant differences were observed. In order to determine whether the histolysis of fat body was due to apoptosis, genomic DNAs were purified at various p.i. times and analyzed. Rapid genomic DNA fragmentation was observed at 24 and 48 h after pupation in both mock and BmNPV infected pupae. However, BmNPV infection clearly inhibited DNA fragmentation and ladder formation at 72 h and later times p.i. Furthermore, pulse-labeling analysis showed that BmNPV infection restored protein synthesis in fat body cells. These results suggested that fat body degradation during pupal-adult development was due to apoptosis, and that BmNPV was able to evoke a cellular response in these cells.

Animals↗
PubMed2000

Effects of taste stimulation on beta-endorphin levels in rat cerebrospinal fluid and plasma.

Opioids are suggested to be involved in generation of palatability and facilitation of consumption of food and fluid. We measured the level of an endogenous opioid, beta-endorphin, in the cerebrospinal fluid (CSF) and plasma after free drinking of water and taste solutions in Wistar rats. When the water-deprived animals were allowed to drink 10 mL of water, the level of beta-endorphin increased significantly 60 and 90 min after the start of drinking in both samples. beta-Endorphin in the CSF increased most after ingestion of 0.5 M sucrose and 0.005 M saccharin followed by 0.1 M NaCl, 0.1 mM quinine and water. An intragastric infusion of 7 mL of water did not change the beta-endorphin level. Essentially the same results were obtained for plasma samples except that NaCl and quinine solutions did not increase beta-endorphin levels. Sucrose became ineffective in releasing beta-endorphin in both samples after the establishment of conditioned taste aversions to this taste stimulus. These results suggest that the release of beta-endorphin is positively correlated with the palatability of taste stimuli, and that CSF beta-endorphin also reflects the reinforcement of fluid intake in thirsty animals.

Animals↗
PubMed2000

Involvement of mitogen-activated protein kinase in peroxynitrite-induced cell death of human neuroblastoma SH-SY5Y cells.

We have investigated the activation of mitogen-activated protein kinase (MAP kinase) in relation to cell death induced by peroxynitrite in human neuroblastoma SH-SY5Y cells. Exposure of the cells to peroxynitrite caused transient increase in MAP kinase activity, and resulted in cell death. PD98059, a selective inhibitor of MAP kinase kinase, reduced peroxynitrite-induced cell death. These results suggest that the activation of MAP kinase may be involved in cell death induced by peroxynitrite.

Cell Survival↗
PubMed2000

Potentiation of carbachol-induced Ca2+ release by peroxynitrite in human neuroblastoma SH-SY5Y cells.

We have investigated the effect of 3-morpholinosydnonimine (SIN-1), a peroxynitrite donor, on carbachol-induced increase in intracellular Ca2+ concentration ([Ca2+]i) in human neuroblastoma SH-SY5Y cells by means of single cell imaging of [Ca2+]i. SIN-1 potentiated carbachol-induced [Ca2+]i rise regardless of external Ca2+, and the potentiation was completely inhibited by superoxide dismutase, indicating that peroxynitrite may enhance Ca2+ release from intracellular stores. On the other hand, SIN-1 reduced carbachol-induced inositol 1,4,5-trisphosphate (IP3) formation. Genistein, a tyrosine kinase inhibitor, potentiated carbachol-induced rise of [Ca2+]i regardless of external Ca2+. These results suggest that peroxynitrite may potentiate the release of Ca2+ from intracellular stores through the perturbation of regulation in tyrosine phosphorylation-dephosphorylation system.

Calcium↗
PubMed2000

The Na+-Ca2+ exchange inhibitor KB-R7943 inhibits high K+-induced increases in intracellular Ca2+ concentration and [3H]noradrenaline release in the human neuroblastoma SH-SY5Y.

The effects of the Na+-Ca2+ exchange inhibitor 2-[2-[4-(4-nitrobenzyloxy)phenyl]ethyl]isothiourea methanesulfonate (KB-R7943) on depolarization-induced Ca2+ signal and [3H]noradrenaline release were examined in SH-SY5Y cells. KB-R7943 at 10 microM significantly inhibited high K+-induced increase in intracellular Ca2+ concentration. KB-R7943 also inhibited high K+-evoked release of [3H]noradrenaline from the cells. These findings suggest that the Na+-Ca2+ exchanger in the reverse mode is involved at least partly in depolarization-induced transmitter release.

Calcium↗
PubMed2000

Identification of novel residues involved in nuclear localization of a baculovirus polyhedrin protein.

A baculovirus polyhedrin protein has proven to possess a nuclear localization signal (NLS) sequence and a domain required for supramolecular assembly. Here we investigated five Bombyx mori nucleopolyhedrovirus (BmNPV) mutants that did not produce polyhedra. Two of five mutants were generated during routine baculoviral expression vector screening, and three were isolated by treatment with the mutagen 5-bromo-2'-deoxyuridine (BrdU). Marker rescue mapping and nucleotide sequence analysis showed that mutations in the polyhedrin gene caused the altered phenotype of these mutants. Biochemical fractionation indicated that cells infected with these mutants exhibited polyhedrin protein in both the nucleus and the cytoplasm. Electron microscopic observation revealed that polyhedrin produced by these mutants ocurred in both the nucleus and the cytoplasm, but did not form a crystalline lattice. Despite the incompleteness of polyhedrin nuclear localization, the NLSs of the five mutants were unchanged, although some of the mutations occurred within residues just outside of the domain reported to be required for polyhedron assembly (4). This result suggests that (a) the polyhedrin NLS directs polyhedrin to the nucleus, but the efficiency of this localization is regulated by regions other than the NLS (probably, polyhedrin conformation and its association with the nucleus are also involved), and (b) formation of a crystalline lattice may also be determined by several domains within polyhedrin.

Animals↗
PubMed2000

Determination of the optimal cut-off value for the [13C]-urea breath test based on a Helicobacter pylori-specific polymerase chain reaction assay.

BACKGROUND: This study was conducted to determine the optimal cut-off value and breath sample collection time for the [13C]-urea breath test based on the assessment of Helicobacter pylori status with a gastric juice-based polymerase chain reaction (PCR) assay. METHODS AND RESULTS: A total of 104 patients took 100 mg [13C]-urea orally and breath samples were collected at 5, 10, 20, 30 and 60 min. The increment of 13CO2:12CO, ratio from the baseline (delta13C) was measured using a laser spectroanalyser. The PCR assay was positive in 63 and negative in 41 patients. The optimal cut-off value of delta13C was calculated for each sample collection time so that the distance from the geometric mean value among Helicobacter pylori-positive patients and that from the arithmetic mean value among negative patients were simultaneously maximized. The cut-off value of 2.7% at 20 min had the longest distance, being separated by 3.16 SD from the two mean values. Using this cut-off value, the urea breath test showed 100% specificity and 98% sensitivity for the diagnosis of Helicobacter pylori infection.

Breath Tests↗
PubMed2000

Clinicopathologic analysis of stage II-III hepatocellular carcinoma showing early massive recurrence after liver resection.

BACKGROUND AND AIMS: Prognosis after hepatectomy for hepatocellular carcinoma (HCC) has been improved by progress in the evaluation of hepatic functional reserve, surgical techniques and perioperative management. However, even when curative resection is performed at a relatively early stage, a considerable number of patients develop early intrahepatic and/or extrahepatic recurrence postoperatively. This study analyzed the clinicopathologic features of HCC with early recurrence. METHODS: We reviewed records of 513 consecutive patients who had undergone liver resection for HCC. There were 48 deaths within a year after surgery from recurrence, including 21 patients with stage II or III HCC (group I). Clinicopathologic parameters of group I patients were compared with those of 188 patients (group II) who developed recurrence following resection of stage II or III HCC and died more than 1 year after surgery. RESULTS: On univariate analysis, age, tumor diameter (phi), alpha-fetoprotein (AFP):phi and protein induced by vitamin K absence or antagonist II (PIVKA-II):phi were significantly greater in group I than in group II. Macroscopic portal vein invasion, microscopic vascular invasion, intrahepatic metastasis, poor differentiation, pleomorphism, sarcomatous change, vascular lake, and angiographic condensed pooling were more frequently observed in group I than group II. Five independent determinants were selected by multivariate analysis: AFP:phi, histologic pleomorphism, sarcomatous change, vascular lake and angiographic condensed pooling. CONCLUSIONS: Highly malignant HCC with extremely poor prognosis exhibits peculiar clinicopathologic characteristics, particularly histologic immaturity, and can be predicted by preoperative indicators such as markedly elevated tumor marker concentrations and condensed pooling on angiography.

Aged↗
PubMed2000

Activation of the TCL1 protein in B cell lymphomas.

The TCL1 gene, localized near the break point of chromosome 14q32.1 often involved in T cell leukemias, is also expressed in normal precursor T and B cells, and B cell lymphoma cell lines. We investigated the expression of the TCL1 protein in various types of B cell lymphomas according to the Revised European-American Classification of Lymphoid neoplasms. Paraffin-embedded tissue sections of lymphoma specimens were subjected to TCL1 immunohistochemistry, and positivity was scored on a three-tiered scale: - (< 25% cells), + (25-50% cells), and ++ (> 50% cells). The TCL1 protein was expressed in low-grade B cell lymphomas including mucosa-associated lymphoid tissue type in ocular adnexa (18/20, 90%). It was also expressed in follicular, lymphoplasmacytic, and mantle cell lymphoma, but not in high-grade diffuse large B cell lymphoma (2/11, 18%). These data suggest that the expression of the TCL1 gene characterizes low-grade B cell lymphomas, and may be involved in certain processes of lymphomatogenesis.

DNA-Binding Proteins↗