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Biomedical subjects

H Yamazaki

Publications and source records attributed to H Yamazaki.

At least 163 records · Page 9Linked to original sources
PubMed2000

A significant role of human cytochrome P450 2C8 in amiodarone N-deethylation: an approach to predict the contribution with relative activity factor.

Human cytochrome P450 (CYP) isoforms involved in amiodarone N-deethylation were identified, and the relative contributions of these CYP isoforms were evaluated in different human liver microsomes. The mean K(M) and V(max) values of amiodarone N-deethylation in microsomes from six human livers were 31.6 +/- 7.5 microM and 1.2 +/- 0.7 pmol/min/pmol of CYP, respectively. Ketoconazole and anti-CYP3A antibodies strongly inhibited amiodarone N-deethylase activity in human liver microsomes at a substrate concentration of 50 microM. Of 15 recombinant human CYP enzymes (19 preparations), CYP1A1, CYP3A4, CYP1A2, CYP2D6, CYP2C8, and CYP2C19 catalyzed amiodarone N-deethylation. The amiodarone N-deethylase activity at a substrate concentration of 5 microM was significantly correlated with the paclitaxel 6alpha-hydroxylase activity (r = 0.84, P <.05) in the human liver microsomes, whereas the amiodarone N-deethylase activity at 100 microM was significantly correlated with the testosterone 6beta-hydroxylase activity (r = 0.94, P <.005). According to the concept of relative activity factor, it was clarified that CYP2C8 as well as CYP3A4 were significantly involved in amiodarone N-deethylation in human livers at clinically significant concentrations and that the contributions of CYP1A2, CYP2C19, and CYP2D6 were relatively minor. However, there was a large interindividual variability in the contribution of each CYP isoform to amiodarone N-deethylase activity in human liver; the relevance of these enzymes would be dependent on the content of the respective isoforms and on the amiodarone concentration in the liver.

Alkylation↗
PubMed2000

Formation of a dihydroxy metabolite of phenytoin in human liver microsomes/cytosol: roles of cytochromes P450 2C9, 2C19, and 3A4.

Formation of four oxidative metabolites from the anticonvulsant drug phenytoin (DPH) catalyzed by human liver microsomal cytochrome P450 (P450) enzymes was determined simultaneously. Under the conditions in which linearity for formation of 4'-hydroxylated DPH (4'-HPPH; main metabolite) was observed, human liver cytosol increased microsome-mediated DPH oxidation. 3',4'-Dihydroxylated product (3', 4'-diHPPH) formation was 10 to 40% of total DPH oxidation in the presence of liver cytosol. 3'-Hydroxy DPH formation was catalyzed by only one of the human liver microsomal samples examined and 3', 4'-dihydrodiol formation could not be detected in all samples. In the presence of liver cytosol, 3',4'-diHPPH formation activity from 100 microM 4'-HPPH was correlated with testosterone 6beta-hydroxylation activity and CYP3A4 content. However, 3', 4'-diHPPH formation using 1 or 10 microM 4'-HPPH as a substrate was not correlated with contents of any P450s or marker activities. Of 10 cDNA-expressed human P450 enzymes examined, CYP2C19, CYP2C9, and CYP3A4 catalyzed 3',4'-diHPPH formation from the primary hydroxylated metabolites (3'-hydroxy-DPH and 4'-HPPH). Fluvoxamine and anti-CYP2C antibody inhibited 3',4'-diHPPH formation from 10 microM 4'-HPPH in a human liver sample that contained relatively high levels of CYP2C, whereas ketoconazole and anti-CYP3A antibody showed inhibitory effects on the activities in liver microsomal samples in which CYP3A4 levels were relatively high. These results suggest that CYP2C9, CYP2C19, and CYP3A4 all have catalytic activities in 3',4'-diHPPH formation from primary hydroxylated metabolites in human liver and that the hepatic contents of these three P450 forms determine which P450 enzymes play major roles of DPH oxidation in individual humans.

Catalysis↗
PubMed2000

[A study of liver metastasis from colorectal cancer in which hepatic resection was performed after hepatic arterial infusion chemotherapy].

We experienced 5 cases of liver metastases from colorectal cancer, in which hepatic resection was carried out after down sizing by hepatic arterial infusion chemotherapy. In addition, a histological study about the effect of chemotherapy on the liver tumor was performed. Primary lesions were located at the sigmoid colon (2), cecum (1), descending colon (1) and rectum (1). We carried out hepatic arterial infusion chemotherapy using mainly 5-FU. The total amount of 5-FU was 10-81 g. Tumor volumes were reduced by 12.5-24%, and they were judged PR. However, surgery was indicated due to obstruction of the proper hepatic artery or other side effects. Postoperative courses were uneventful and the hospital stays were from 17-61 days, and all patients were still alive in tumor-free condition at writing. By the histological study of the excised specimen, we recognized not only remarkable fibrous changes or calcifications but also overt viable cancerous cells. We conclude that the option of hepatic resection after controlling the development of the cancer by hepatic arterial infusion chemotherapy is a rational strategy of treatment for liver metastasis from colorectal cancer.

Aged↗
PubMed2000

Roles of cytochromes P450 1A2, 2A6, and 2C8 in 5-fluorouracil formation from tegafur, an anticancer prodrug, in human liver microsomes.

Tegafur, an anticancer prodrug, is bioactivated to 5-fluorouracil (5-FU) mainly by cytochrome P450 (P450) enzymes. The conversion from tegafur into 5-FU catalyzed by human liver microsomal P450 enzymes was investigated. In fourteen cDNA-expressed human P450 enzymes having measurable activities, CYP1A2, CYP2A6, CYP2E1, and CYP3A5 were highly active in catalyzing 5-FU formation at a tegafur concentration of 100 microM. Kinetic analysis revealed that CYP1A2 had the highest V(max)/K(m) value and that the V(max) value of CYP2A6 was high in 5-FU formation. In human liver microsomes, the activities of 5-FU formation from 10 microM, 100 microM, and 1 mM tegafur were significantly correlated with both coumarin 7-hydroxylation (r = 0.83, 0.86, and 0.74) and paclitaxel 6 alpha-hydroxylation (r = 0.77, 0.62, and 0.85) activities, respectively. Coumarin efficiently inhibited the 5-FU formation activities from 100 microM and 1 mM tegafur catalyzed by human liver microsomes that had high coumarin 7-hydroxylation activity. On the other hand, furafylline, fluvoxamine, and quercetin, as well as coumarin, showed inhibitory effects in liver microsomes that had high catalytic activities of 5-FU formation. The other P450 inhibitors examined showed weak or no inhibition in human liver microsomes. Polyclonal anti-CYP1A2 antibody, monoclonal anti-CYP2A6, and anti-CYP2C8 antibodies inhibited 5-FU formation activities to different extents in those two microsomal samples. These results suggest that CYP1A2, CYP2A6, and CYP2C8 have important roles in human liver microsomal 5-FU formation and that the involvement of these three P450 forms differs among individual humans.

Antimetabolites, Antineoplastic↗
PubMed2000

Perforation of rotator cuff increases interleukin 1beta production in the synovium of glenohumeral joint in rotator cuff diseases.

OBJECTIVE: To study the hypothesis that perforation of the rotator cuff increases the degree of inflammation in the synovium of the glenohumeral joint in rotator cuff diseases. METHODS: Thirty-five synovial specimens in the glenohumeral joint of patients with rotator cuff diseases were examined. They were obtained during surgery and divided into 2 groups on the basis of the presence or absence of rotator cuff perforation, i.e., perforating and nonperforating tears. The expression levels of inflammatory cytokine mRNA of interleukin 1beta (IL-1beta) and 2 forms (secreted type and intracellular type) of IL-1 receptor antagonist (IL-1ra) were measured by reverse transcriptase polymerase chain reaction (RT-PCR). The protein level of IL-1beta was determined by Western blot analysis. IL-1beta producing cells were also identified by in situ RT-PCR and immunohistochemistry. RESULTS: In perforating tears cytokine mRNA in the glenohumeral synovium was more significantly expressed than in nonperforating tears. Also, higher levels of IL-1beta protein were detected in perforating tears. CONCLUSION: Perforation of the rotator cuff increases IL-1beta production in the glenohumeral joint, enhancing inflammatory intensity at the site. These findings suggest the possibility that glenohumeral synovitis in rotator cuff diseases may be a factor for the development of glenohumeral arthropathy.

Adult↗
PubMed2000

Simultaneous treatment of multiple primary cancers of the oral cavity and other sites.

Multiple primary cancers are not uncommon in the head and neck region. Since the time for treatment will be prolonged if each lesion is treated separately, simultaneous treatment of the cancers is preferred to ensure complete remission of lesions and increased survival of patients. In this paper, the efficacy of combined treatment was evaluated in 9 patients with oral cancers and concurrent cancers in other sites. The mean age of the patients was 54 years (range 44 to 66). The tongue (8) and mandible (1) were the sites of involvement. Concurrent cancers were found most often in the esophagus, followed by stomach and lung. Histologically, 7 lesions were diagnosed as squamous cell carcinomas. All oral cancers were treated by surgery. Neck dissection and simultaneous reconstruction were performed in 5 patients. In addition, concurrent cancers were treated simultaneously by endoscopic mucosal resection in 2 patients and radical resection followed by immediate reconstruction in 6 other patients. However, simultaneous surgical treatment of all lesions could not be performed in an individual with 3 cancers. The time of surgery ranged from 23 minutes to 17 hours and 30 minutes. With the exception of 2 patients who died of postoperative complications and had needed treatment for dysphasia, all patients were discharged after 1 to 2 months. Four of the patients are still alive 2 years and 6 months after surgery. These results indicate that simultaneous treatment is effective in selected cases of multiple cancers.

Adenocarcinoma↗
PubMed1999

Transforming growth factor-beta activated during exercise in brain depresses spontaneous motor activity of animals. Relevance To central fatigue.

Intracerebroventricular administration into sedentary mice of the high molecular mass fraction of cerebrospinal fluid (CSF) from exercise-exhausted rats produced a decrease in spontaneous motor activity [K. Inoue, H. Yamazaki, Y. Manabe, C. Fukuda, T. Fushiki, Release of a substance that suppresses spontaneous motor activity in the brain by physical exercise, Physiol. Behav. 64 (1998) 185-190]. CSF from sedentary rats had no such effect. This suggests the presence of a substance regulating the urge for motion as a response to fatigue. A bioassay system using hydra, a freshwater coelenterate, showed an activity indistinguishable from transforming growth factor-beta (TGF-beta) in the CSF from exercise-fatigued rats, while not in that from sedentary rats. The increase in the concentration of active TGF-beta in the CSF from exercise-fatigued rat was also ascertained by another bioassay system using mink lung epithelial cells (Mv1Lu). Injection of TGF-beta into the brains of sedentary mice elicited a similar decrease in spontaneous motor activity in a dose-dependent manner. Increasing the exercise load on rats raised both the levels of active TGF-beta and the activity of depression on spontaneous motor activity of mice in the CSF of rats. Taken together, these results suggest that exercise increases active TGF-beta in the brain and it creates the feeling of fatigue and thus suppresses spontaneous motor activity.

Animals↗
PubMed1999

Molecular analysis of the GCF gene identifies revisions to the cDNA and amino acid sequences(1).

GC factor (GCF) was reported as a transcriptional regulator that binds to a specific GC-rich sequence in the epidermal growth factor receptor (EGFR) gene promoter and represses its expression. In this paper, we present the data on three revisions of the cDNA sequence that lead to significant changes of the amino acid sequences of the published GCF. Firstly, 5'-rapid amplification of cDNA end (5'-RACE) analysis revealed that the 308 nucleotides of 5'-end of the previously published GCF cDNA does not exist at the 5'-end of the RACE product. Simultaneously, the correct 5'-end cDNA sequence of 31 nucleotides was identified. Secondly, the 'T' at the position 787 of the published GCF cDNA was not observed. Finally, a new sequence of 114 nucleotides was identified between the positions 851 and 852 of the published cDNA sequence. The revisions result in a GCF cDNA of 2661 nucleotides that encodes a protein of 781 amino acids, replacing the highly basic region of the amino-terminus of the published GCF with a new sequence of 147 amino acids. In this era of massive gene cloning and sequencing, this study is a warning to the biological research of recent years.

Alternative Splicing↗
PubMed1999

Enkephalinergic neurons express 5-HT3 receptors in the spinal cord dorsal horn: single cell RT-PCR analysis.

The analgesic effect of activation of 5-HT3 receptors at the spinal cord is attenuated by the opioid antagonist naloxone. Enkephalin-immunoreactive neurons in the spinal cord superficial dorsal horn are innervated by 5-HT-immunoreactive fibers. This prompted us to examine whether enkephalinergic dorsal horn neurons express 5-HT3 receptors. Using the technique of single-cell RT-PCR adapted for small neurons in the superficial dorsal horn, methionine-enkephalin sequence-specific PCR products were observed in about half of the neurons studied. Furthermore, 5-HT3 receptor mRNA was detected in approximately 25% of enkephalinergic neurons. These observations suggest that at least part of the antinociception elicited by activation of 5-HT3 receptors at the spinal cord may involve enkephalinergic dorsal horn neurons.

Animals↗
PubMed1999

Radiotherapy of early tongue cancer in patients less than 40 years old.

PURPOSE: To evaluate the results of treatment for early mobile tongue cancer in patients less than 40 years. METHODS AND MATERIALS: Between January 1967 and September 1992, 70 patients less than 40 years old (young age group) with early tongue cancer (T1-2N0M0) were treated with low-dose-rate (LDR) interstitial radiotherapy at the Osaka University Hospital (OUH). All patients had a minimum 2-year follow-up (median: 13 years). External radiotherapy (median: 30 Gy) was combined in 25 cases. The treatment results were compared with those for two older age groups (middle age: 40-64 years old; old age: 65 years old or more). RESULTS: The 5-year probability of cause-specific survival (CSS) rate for the young age group was 80%, which was not significantly different from the two older groups: 81% for middle age and 71% for old age. However, male patients of young age showed significantly worse rates than those of middle and old age (p = 0.02). The 5-year local control rate for the young age group was 78%. It was not significantly different from the two older groups: 81% for middle age and 70% for old age. The incidence of regional lymph node metastasis was 32% for T1, 48% for T2, 56% for males, and 24% for females. The regional failure rate of young males was significantly higher than those of the two older groups: 32% for middle and 22% for old age (p = 0.001). CONCLUSION: The overall treatment results for patients with early tongue cancer less than 40 years old were not worse than those of older age groups. However, male gender was a risk factor for lymph node metastasis and CSS.

Adult↗
PubMed1999

Tooth-specific expression conferred by the regulatory sequences of rat dentin sialoprotein gene in transgenic mice.

We have isolated a 3.8-kb DNA fragment containing the 5' flanking region, 1st exon, and 1st intron of the rat dentin sialoprotein (rDsp) gene and produced transgenic mice carrying a LacZ reporter gene under the control of this fragment. Expression of the transgene transcript and beta-galactosidase activity were restricted to dentin and odontoblasts with spatial and temporal patterns comparable to those of the endogenous mouse Dsp transcript, although beta-galactosidase activity could not be detected visually during embryonal stages. Other tissues tested, such as alveolar bones, ameloblasts and dental pulps, did not express the transgene. This indicates that the regulatory elements necessary for tooth-specific expression are present in the fragment, which contains a TATA box and several consensus sequences for binding sites of transcription factors related to tooth development, such as TCF-1/LEF-1, MSX-1 and Dlx-1. The regulatory sequences and the transgenic mice described here provide useful information for the study of tooth development.

Amino Acid Sequence↗
PubMed1999

Phospholipase D activity of cytochrome P450 in human liver endoplasmic reticulum.

Phospholipase D (PLD) activity in mammalian liver endoplasmic reticulum (ER) has not been characterized. Purified human liver microsomal cytochromes P450 (P450)-P450 1A2 and P450 2E1-were shown to have appreciable PLD activity, hydrolyzing phosphatidylcholine but not other phospholipids, generating PA and choline. The activity was confirmed using recombinant and mutated human P450s expressed in bacteria. In human liver microsomes, immunoinhibition of PLD activity was observed with anti-P450 1A2 > anti-P450 2C > anti-P450 2E1. Thus, P450 may act as a significant PLD in human liver ER and exert its biological effects by several mechanisms, including signaling functions and change of membrane properties.

Amino Acid Sequence↗
PubMed1999

Lack of repetition priming effect on visual event-related potentials in schizophrenia.

BACKGROUND: The present study was designed to assess, using event-related potentials, whether aberrant semantic processing reported in schizophrenia results from primary semantic overactivation or contextual dysregulation. METHODS: The visual event-related brain potentials were compared between 9 schizophrenic subjects and 16 normal control subjects performing two kinds of semantic categorization tasks with different nontarget stimuli: 1) nontargets comprising words, pseudowords, and unpronounceable foreign letters and 2) nontargets comprising initial presenting words, immediate repetition words, and delayed repetition words. RESULTS: Schizophrenic subjects showed no evidence suggestive of a greater negative potential associated with words and pseudowords, but they did show a lack of amplitude change associated with immediately repeated words relative to that in control subjects. CONCLUSIONS: These results suggest that aberrant semantic activation in schizophrenia results mainly from a failure to utilize information from preceding words or context, and could explain the increased N400 to the congruent or related words recently reported in this disease.

Adult↗
PubMed1999

Molecular cloning of a novel human collectin from liver (CL-L1).

Collectins are a C-lectin family with collagen-like sequences and carbohydrate recognition domains. These proteins can bind to carbohydrate antigens of microorganisms and inhibit their infection by direct neutralization and agglutination, the activation of complement through the lectin pathway, and opsonization by collectin receptors. Here we report the cloning of a cDNA encoding human collectin from liver (CL-L1 (collectin liver 1)) that has typical collectin structural characteristics, consisting of an N-terminal cysteine-rich domain, a collagen-like domain, a neck domain, and a carbohydrate recognition domain. The cDNA has an insert of 831 base pairs coding for a protein of 277 amino acid residues. The deduced amino acid sequence shows that this collectin has a unique repeat of four lysine residues in its C-terminal area. Northern blot, Western blot, and reverse transcription-polymerase chain reaction analyses showed that CL-L1 is present mainly in liver as a cytosolic protein and at low levels in placenta. More sensitive analyses by reverse transcription-polymerase chain reactions showed that most tissues (except skeletal muscle) have CL-L1 mRNA. Zoo-blot analysis indicated that CL-L1 is limited to mammals and birds. A chromosomal localization study indicated that the CL-L1 gene localizes to chromosome 8q23-q24.1, different from chromosome 10 of other human collectin genes. Expression studies of fusion proteins lacking the collagen and N-terminal domains produced in Escherichia coli affirmed that CL-L1 binds mannose weakly. CL-L1 and recombinant CL-L1 fusion proteins do not bind to mannan columns. Analysis of the phylogenetic tree of CL-L1 and other collectins indicated that CL-L1 belongs to a fourth subfamily of collectins following the mannan-binding protein, surfactant protein A, and surfactant protein D subfamilies including bovine conglutinin and collectin-43 (CL-43). These findings indicate that CL-L1 may be involved in different biological functions.

Amino Acid Sequence↗
PubMed1999

Characterization of T-cell repertoire of the bone marrow in immune-mediated aplastic anemia: evidence for the involvement of antigen-driven T-cell response in cyclosporine-dependent aplastic anemia.

To determine whether the antigen-driven T-cell response is involved in the pathogenesis of aplastic anemia (AA), we examined the complementarity-determining region 3 (CDR3) size distribution of T-cell receptor (TCR) beta-chain (BV) subfamilies in the bone marrow (BM) of untreated AA patients. AA patients who did not respond to immunosuppressive therapy and those who obtained unmaintained remission early after cyclosporine (CyA) or antithymocyte globulin (ATG) therapy exhibited essentially a normal CDR3 size pattern. In contrast, five patients who needed continuous administration of CyA to maintain remission exhibited a skewed CDR3 size pattern in a number (>40%) of BV subfamilies suggestive of clonal predominance. The skewing of CDR3 size distribution became less pronounced in one of the CyA-dependent patients when the patient achieved unmaintained remission after a 4-year therapy with CyA, whereas it persisted longer than 7 years in the other patient requiring maintenance therapy. Sequencing of BV15 cDNA for which the CDR3 size pattern exhibited apparent clonal predominance in all CyA-dependent patients showed high homology of the amino acid sequence of the CDR3 between two different patients. These findings indicate that antigen-driven expansion of T cells is involved in the pathogenesis of AA characterized by CyA-dependent recovery of hematopoiesis.

Adolescent↗