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Biomedical subjects

Y Takeda

Publications and source records attributed to Y Takeda.

At least 109 records · Page 6Linked to original sources
PubMed2001

A long-term follow-up analysis of serial core promoter and precore sequences in Japanese patients chronically infected by hepatitis B virus.

To investigate the association of hepatitis B virus (HBV) with core promoter mutation (T1762A1764) or precore mutation (A1896) with the clinical course of illness, we analyzed serial core promoter and precore sequences in 22 patients with HBV-associated chronic liver disease who were followed for 12+/-4 years (mean +/- SD). Sixteen of 22 patients were positive for HBeAg at baseline, and 15 of the 16 patients seroconverted to anti-HBe during the observation period. T1762A1764 mutation was detected in 16 of 22 patients, including 11 patients positive for HBeAg, at baseline. During the follow-up period, A1896 mutation emerged in 7 of 16 patients who had the wild-type HBV or only the T1762A1764 mutation at baseline. Sustained remission of hepatitis correlated with the low level of viremia, but did not with type of mutations. These results indicate that HBV with T1762A1764 mutation tends to precede A1896 mutation during the course of infection in Japanese patients with chronic liver disease.

Adult↗
PubMed2001

Functional analysis for peripheral myelin protein PASII/PMP22: is it a member of claudin superfamily?

Two major glycoproteins, P0 and PASII/PMP22, are specifically expressed in peripheral myelin. Point mutations of these proteins and over or under expression of PASII/PMP22 cause various hereditary peripheral neuropathies. P0 is well characterized as a major adhesion molecule in PNS myelin, but the function of PASII/PMP22 is still unknown. Recently, an oligodendrocyte-specific protein (OSP) was identified as a member of the claudin family and as a component of tight junctions of central myelins. Since PASII/PMP22 shows similarity in structure to OSP, which is a tetraspan membrane protein, we speculated if PASII/PMP22 could be a member of claudin superfamily. The primary structure of PASII/PMP22 showed a significant homology of 48% and a 21% identity with the OSP sequence. Exogenous expression of PASII/PMP22 in C6 cells significantly inhibited BrdU incorporation to the cells. The C6 cells stably transfected with PASII/PMP22 cDNA showed no homophilic cell adhesive activity. When dorsal root ganglion (DRG) neurons were cocultured on PASII/PMP22 expressing cells, both neurite extension and branching of DRG neurons were significantly inhibited. These results indicate that PASII/PMP22 may play a role in a turning point of Schwann cell development from proliferation to differentiation. On the other hand, the cells expressing claudin family proteins are reported to show strong cell adhesive activity and an ability to form tight junctions with neighboring cells. For this reason, we currently do not have any functional data supporting that PASII/PMP22 is the member of claudin superfamily.

Animals↗
PubMed2001

Capsid protein gene variation among feline calicivirus isolates.

We amplified the capsid protein gene fragments of 30 Japanese isolates of feline calicivirus (FCV), including the C, D, and E regions, by reverse transcription-polymerase chain reaction (RT-PCR), followed by direct sequencing. Alignment of the predicted amino acid sequences, together with other published sequences from the isolates obtained in other countries, demonstrated a marked heterogeneity among the isolates, confirming the current definition of hypervariable regions within the capsid protein: these regions give rise to the antigenic variations seen in FCV isolates. Phylogenetic analysis of the nucleotide sequences could not identify significant geographically or temporally separated clusters of FCV isolates, supporting the theory of a single genotype.

Amino Acid Sequence↗
PubMed2001

Genetic analysis of the cytochrome P-450c17alpha (CYP17) and aldosterone synthase (CYP11B2) in Japanese patients with 17alpha-hydroxylase deficiency.

OBJECTIVE: To determine the clinical and molecular genetic characterization of two Japanese patients with 17alpha-hydroxylase deficiency, we analysed the 17alpha-hydroxylase/17,20-lyase gene (CYP17). Next, to clarify the mechanism of hypoaldosteronism in 17alpha-hydroxylase deficiency, we analysed the expression of aldosterone synthase (CYP11B2) messenger RNA and sequenced CYP11B2 in these patients. PATIENTS: Patient 1 (46 XY), phenotypically female, sought medical attention for hypertension, amenorrhea and infantile genitalia. Patient 2 (46 XX), phenotypically female, presented for hypertension and amenorrhea. Hormonal data in both patients showed decreased levels of sex steroids, cortisol, aldosterone and plasma renin activity and extreme elevation of deoxycortisol. DESIGN: Direct sequencing of CYP17 and CYP11B2 was performed using genomic DNA from the patients. An expression studies of mutated forms of CYP17 was performed using COS-1 cells. The expression of CYP11B2 messenger RNA in mononuclear leucocytes (MNLs) of these patients and normal subjects was measured using the competitive polymerase chain reaction METHOD: The effect of renin secretion stimulation on the levels of CYP11B2 messenger RNA in MNLs of normal subjects was also studied. RESULTS: We detected two novel genetic defects in 17alpha-hydroxylase. Sequence analysis revealed one base pair deletion (T) at codon 243 in exon 4 in patient 1. CYP17 in patient 2 contained a point mutation (C to T) at position 415 in exon 8. Transfected cells of mutant from patient 1 had no 17alpha-hydroxylase or 17,20-lyase activity. The R415C mutant protein showed very weak activity of 17alpha-hydroxylase or 17,20-lyase activity. In the renin secretion stimulating test, the increase in CYP11B2 messenger RNA levels in MNLs was parallel with that of plasma aldosterone concentration. The expression of CYP11B2 mRNA in NMLs of these patients was lower compared to controls. No mutations in CYP11B2, including the 5' flanking region, were found. CONCLUSIONS: These results indicate that the novel mutations of the CYP17 gene found in these patients inactivate cytochrome P450c17 function, and that hypoaldosteronism in these patients may be partly explained by a decreased activity of aldosterone synthase, which is regulated at the transcriptional level.

Adrenal Hyperplasia, Congenital↗
PubMed2001

Acute psychosis during intracranial EEG monitoring: close relationship between psychotic symptoms and discharges in amygdala.

PURPOSE: This report examined the underlying mechanism of psychosis associated with epilepsy. METHODS: An adult patient with epilepsy manifesting acute psychosis during long-term EEG monitoring is presented, together with a literature review on this subject. RESULTS: A 25-year-old woman with intractable temporal lobe epilepsy developed acute psychosis while she underwent long-term intracranial EEG monitoring. After a clustering of seizures, she manifested psychotic symptoms including hallucination, stupor, and repeated fear. The transition of psychotic symptoms corresponded to the changes in frequency and morphology of seizure discharges restricted to the left amygdala. Improvement of psychosis coincided with disappearance of seizure discharges. CONCLUSIONS: This case confirmed a close relationship between psychotic symptoms and seizure discharges in the left amygdala. It is suggested that paroxysmal bombardment of the medial temporal lobe structure may be a pathogenetic factor of acute psychosis associated with epilepsy.

Acute Disease↗
PubMed2001

Docetaxel alone or orally combined with 5-fluorouracil and its derivatives: effects on mouse mammary tumor cell line MM2 in vitro and in vivo.

Although docetaxel (Taxotere; TXT), a taxoid anticancer drug, is clinically and experimentally very effective against breast cancer, its antitumor effect is of very short duration. We addressed whether 5-fluorouracil (5-FU) and its derivatives can act synergistically with TXT against mammary tumors, with placing particular stress on their use by oral route. Mouse mammary tumor cell line, MM2, was propagated in culture and as ascites in mice. Carmofur (HCFU) and doxifluridine (5'-DFUR) were used as 5-FU derivatives. In vitro, the cytotoxic effects of antitumor drugs on MM2 cells were examined by MTS assay. In vivo, mice inoculated i.p. with MM2 cells were treated with i.p. injection of TXT and/or oral administration of 5-FU or its derivatives, and observed for curing tumor. In vitro, the synergistic effects were observed in the combination of TXT and 5-FU or HCFU, but not in that of TXT and 5'-DFUR. In vivo, all of these combinations cured tumors far more effectively than TXT alone. The discrepant result of the combination of TXT and 5'-DFUR between in vitro and in vivo was ascribed to up-regulation of pyrimidine phosphorylase in tumor cells in vivo by TXT. Thus, 5-FU, its masked compounds like HCFU and its prodrugs like 5'-DFUR can act synergistically with TXT in the therapy of cancer even when administered by the oral route.

Administration, Oral↗
PubMed2001

Effects of high sodium intake on cardiovascular aldosterone synthesis in stroke-prone spontaneously hypertensive rats.

OBJECTIVES: Aldosterone is synthesized in extra-adrenal tissues such as the vasculature, heart and brain. The mechanisms underlying the effect of high salt intake on the development and acceleration of vascular injury and cardiac hypertrophy in the stroke-prone spontaneously hypertensive rats (SHRSP) are still not clear. The goal of this study was to determine whether high salt intake increases cardiovascular aldosterone synthesis in SHRSP. METHODS: Four-week-old SHRSP were given tap water or 0.9% NaCl solution for hydration for 4 weeks in addition to a normal salt diet. Isolated rat mesenteric arteries and hearts were perfused for 2 h, and the perfusate was analysed by high-performance liquid chromatography. The concentrations of aldosterone synthase gene (CYP11B2) mRNA and angiotensin II receptor (AT1R) mRNA were determined by competitive polymerase chain reaction. RESULTS: Salt-loaded SHRSP had higher blood pressures than SHRSP with normal salt intake. Plasma aldosterone concentrations and plasma renin activity were decreased by high salt intake. Aldosterone production, the expression of CYP11B2 mRNA and AT1R mRNA in mesenteric arteries and hearts were significantly increased by high salt intake. CONCLUSIONS: These results suggest that high salt intake increases aldosterone production and expression of the AT1R mRNA in the cardiovascular tissue in SHRSP, which may contribute to the development of malignant hypertension in salt-loaded SHRSP.

Aldosterone↗
PubMed2001

Temporal profiles of the levels of endogenous antioxidants after four-vessel occlusion in rats.

Although it is known that development of lipid peroxidation after ischemia occurs predominantly in vulnerable regions, temporal profiles of antioxidants after ischemia have not been regionally elucidated. After reperfusion periods of 0, 3, 24, and 72 hours following 20 minutes of four-vessel occlusion (n = 6 in each group), the concentration of total glutathione (GSH) and the activities of superoxide dismutase (SOD), catalase, and glutathione peroxidase (GSH-Px) were assayed in the hippocampus, parietal cortex, striatum, thalamus, and brain stem. The levels of all antioxidants were unchanged in all regions without reperfusion; however, the concentration of total GSH significantly decreased in the hippocampus at 3 hours after the onset of reperfusion, and showed a maximum decrease in the hippocampus (68% of the sham-control level), parietal cortex (78% of the sham-control level), and striatum (76% of the sham-control level) after 24 hours of reperfusion. After 72 hours of reperfusion, these regions and the thalamus showed restoration and an increase in the total GSH concentration, respectively. The activities of SOD, GSH-Px, and catalase were stable during the reperfusion period, but the hippocampus showed significant increases in these enzyme activities and the parietal cortex and striatum showed significant increases in SOD activities at 72 hours after the onset of reperfusion. These results indicate that endogenous antioxidants take 72 hours for restoration in vulnerable regions after 20 minutes of four-vessel occlusion in rats.

Animals↗
PubMed2001

Comparison of antibiogram, virulence genes, ribotypes and DNA fingerprints of Vibrio cholerae of matching serogroups isolated from hospitalised diarrhoea cases and from the environment during 1997-1998 in Calcutta, India.

This study identified 17 matching serogroups of Vibrio cholerae belonging to serogroups other than O1 and O139 isolated from human cases and from the environment during a concurrent clinical and environmental study conducted in Calcutta, a cholera endemic area. Isolates within these matching serogroups were compared by various phenotypic and genotypic traits to determine if the environment was the source of the organisms associated with the disease. Clinical strains of V. cholerae were resistant to a greater number of drugs and exhibited multi-drug resistance compared with their environmental counterparts. Except for the presence of the genes for the El Tor haemolysin and the regulatory element ToxR in most of the strains of V. cholerae examined, non-O1, non-O139 V. cholerae strains lacked most of the other known virulence traits associated with toxigenic V. cholerae O1 or O139. Restriction fragment-length polymorphism of virulence-associated genes, ribotypes and DNA fingerprints of strains of matched serogroups showed considerable diversity, although some gene polymorphisms and ribotypes of a few strains of different serogroups were similar. It is concluded that despite sharing the same serogroup, environmental and clinical isolates were genetically heterogeneous and were of different lineages.

Blotting, Southern↗
PubMed2001

The first large-scale nucleic acid amplification testing (NAT) of donated blood using multiplex reagent for simultaneous detection of HBV, HCV, and HIV-1 and significance of NAT for HBV.

The first nationwide nucleic acid amplification testing (NAT) for hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus type 1 (HIV-1) of voluntarily donated blood after serological pre-screening and before release of cellular components and plasma for fractionation was implemented by the Japanese Red Cross Blood Transfusion Services. From February 1, 2000 to April 30, 2001, specimens from 6,805,010 units of serologically negative donation were screened in minipools of 50 samples within 24 hr after blood donation by NAT using multiplex HBV/HCV/HIV-1 reagent for blood transfusion including short shelf-life platelets. Among them, 112 HBV DNA-positives, 25 HCV RNA positives and 4 HIV-1 RNA positives were screened out and we could prevent transfusion of these NAT positive units. Subtypes/genotypes of HBV DNA, adr/C, adw/A, adw/B, adw/C, ayr/C and ayw/D were found and adr/C was predominant. A total of 61.6 % of them (69/112) were negative by overnight EIA. Sixth three of HBV NAT-positive samples carried virus loads less than 10(4) copies/mL and 92.1 % of them (58/63) were negative by overnight EIA. The virus growth curves of HBV in 6 cases obtained by retrospective and prospective follow-up study showed exponential straight lines in the early stage of serological window periods and the log times of HBV growth (10 fold increase) in serological window period were between 4.6 and 7.6 days. NAT screening with highly sensitive reagents in pool of specimens is useful to exclude blood units with low level of HBV and HBV mutants from blood transfusion.

Blood Donors↗
PubMed2001

A sandwich ELISA for detection of soluble GPI-80, a glycosylphosphatidyl-inositol (GPI)-anchored protein on human leukocytes involved in regulation of neutrophil adherence and migration--its release from activated neutrophils and presence in synovial fluid of rheumatoid arthritis patients.

GPI-80, mainly distributed on human neutrophils and monocytes, is a novel glycosylphosphatidylinositol (GPI)-anchored protein regulating neutrophil adherence and migration. We prepared a polyclonal antibody specific to GPI-80 by immunizing rabbits with the purified GPI-80 and established a sandwich ELISA for detecting soluble GPI-80. We found that soluble GPI-80 was released from fMLP activated neutrophils and was present at high concentrations in synovial fluids but not sera of rheumatoid arthritis patients, suggesting that GPI-80 may play a role in inflammatory diseases. The detection of soluble GPI-80 may help us to understand its physiological and pathological functions.

Amidohydrolases↗
PubMed2001

Preclinical in vivo antitumor efficacy of nedaplatin with gemcitabine against human lung cancer.

The antitumor efficacy of the combination of nedaplatin (NDP) with gemcitabine (GEM) was evaluated. We also compared the antitumor activity of NDP plus GEM with that of cisplatin (CDDP) plus GEM or carboplatin (CBDCA) plus GEM. Ma44, which is a human lung cancer sensitive to GEM, and NCI-H460, which is a human lung cancer refractory to GEM, were used in this study. GEM was injected i.v. once followed by i.v. injection of NDP at an interval of approximately 30 min into tumor-bearing athymic mice. GEM was administered again 3 or 4 days thereafter. Combined dosing of NDP with GEM resulted in synergistically enhanced inhibition of tumor growth in the Ma44 tumor model. NDP plus GEM was also effective against Ma44 cells when given late in the therapy, a model for advanced disease. Potent augmentation of growth inhibition by NDP with GEM was also found with the NCI-H460 tumor model. The combination effect of NDP plus GEM appeared to be superior to that of CDDP plus GEM or CBDCA plus GEM in both tumor models. Toxicity in terms of blood cell numbers was not enhanced by the combination of NDP with GEM. These results suggest the effectiveness of combination of NDP with GEM for clinical therapy.

Animals↗
PubMed2001

Geranylgeraniol, an intermediate product in mevalonate pathway, induces apoptotic cell death in human hepatoma cells: death receptor-independent activation of caspase-8 with down-regulation of Bcl-xL expression.

Geranylgeraniol (GGOH), an intermediate of mevalonate metabolism, is known to induce apoptosis in various lines of cancer cells. The present study was undertaken to clarify the signaling pathways of apoptosis induced by GGOH in human hepatoma cells. HuH-7 human hepatoma cells were incubated in the absence or presence of GGOH. Activation of caspase-8 /-9 /-3 in HuH-7 cells was found after 8 h treatment with GGOH, at which time DNA fragmentation and loss of mitochondrial transmembrane potential (Deltaphim) occurred. HuH-7 cells do not express Bcl-2; however, down-regulation of Bcl-xL expression preceded activation of the caspase cascade in GGOH-treated HuH-7 cells, while Bax expression was not changed by GGOH treatment. Addition of caspase inhibitors restored the decreased cell viability of HuH-7 cells by GGOH, including Deltaphim, to the baseline level, which indicated that caspase triggers mitochondria-dependent apoptotic pathways in GGOH-treated HuH-7 cells. Similarly, GGOH-mediated apoptosis of HuH-7 cells was clearly prevented by coadministration of ursodeoxycholic acid (UDCA), which led to restoration of the level of Bcl-xL expression. Activation of caspase-8 /-9 /-3, as well as Deltaphim, by GGOH treatment was suppressed by addition of UDCA. Our results indicate that activation of the caspase cascade initiating from caspase-8, which could be accelerated by down-regulation of Bcl-xL expression, plays a key role in an apoptotic process induced by GGOH in human hepatoma cells.

Apoptosis↗
PubMed2001

Protective effect of Lactobacillus casei strain Shirota on Shiga toxin-producing Escherichia coli O157:H7 infection in infant rabbits.

We examined colonization patterns of Shiga toxin-producing Escherichia coli (STEC), concentrations of Shiga toxins (Stxs) and specific immunoglobulin A (lgA) against Stxs and STEC bacterial cell surface antigen in various portions of the gastrointestinal tract in an infant rabbit infection model. After inoculation of 3-day-old infant rabbits with STEC strain 89020087 at low doses (approximately 10(3) CFU/body), numbers of colonizing STEC bacteria and concentrations of Stxs in the intestine increased dramatically and the animals developed diarrhea within a couple of days after infection. Daily administration of Lactobacillus casei from the day of birth dramatically decreased the severity of diarrhea and lowered STEC colonization levels in the gastrointestinal tract 100-fold day 7 after infection. Both Stx1 and Stx2 concentrations in the intestines and histological damage to the intestinal mucus induced by STEC infection were decreased by the administration of L. casei. Examination of the concentrations of volatile fatty acids and pH of the intestinal contents revealed that the protective effect of L. casei administration against STEC infection was not due to fermented products such as lactic acid in the gastrointestinal tract. Administration of L. casei increased levels of lgAs against Stx1, Stx2, and formalin-killed STEC cells in the colon approximately two-, four-, and threefold, respectively, compared with those of the untreated controls by day 7 after infection. These results suggest that administration of L. casei strain Shirota enhances the local immune responses to STEC cells and Stxs and leads to elimination of STEC and thus decreases Stx concentrations in the intestines.

Animals↗
PubMed2001

Characterization of VPI pathogenicity island and CTXphi prophage in environmental strains of Vibrio cholerae.

Environmental isolates of Vibrio cholerae of eight randomly amplified polymorphic DNA (RAPD) fingerprint types from Calcutta, India, that were unusual in containing toxin-coregulated pilus or cholera toxin genes but not O1 or O139 antigens of epidemic strains were studied by PCR and sequencing to gain insights into V. cholerae evolution. We found that each isolate contained a variant form of the VPI pathogenicity island. Distinguishing features included (i) four new alleles of tcpF (which encodes secreted virulence protein; its exact function is unknown), 20 to 70% divergent (at the protein level) from each other and canonical tcpF; (ii) a new allele of toxT (virulence regulatory gene), 36% divergent (at the protein level) in its 5' half and nearly identical in its 3' half to canonical toxT; (iii) a new tcpA (pilin) gene; and (iv) four variant forms of a regulatory sequence upstream of toxT. Also found were transpositions of an IS903-related element and function-unknown genes to sites in VPI. Cholera toxin (ctx) genes were found in isolates of two RAPD types, in each case embedded in CTXphi-like prophages. Fragments that are inferred to contain only putative repressor, replication, and integration genes were present in two other RAPD types. New possible prophage repressor and replication genes were also identified. Our results show marked genetic diversity in the virulence-associated gene clusters found in some nonepidemic V. cholerae strains, suggest that some of these genes contribute to fitness in nature, and emphasize the potential importance of interstrain gene exchange in the evolution of this species.

Amino Acid Sequence↗