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Biomedical subjects

K Arai

Publications and source records attributed to K Arai.

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

Arginine as an exacerbating factor for glomerulonephritis in rats fed a methionine-threonine-supplemented low casein diet.

We previously demonstrated that a methionine-threonine-supplemented low (8.5%) casein diet (8.5CMT) reduced symptoms such as proteinuria in nephritic rats without severe protein malnutrition. In this study, we examined whether or not L-arginine supplementation to 8.5CMT would exacerbate proteinuria and other symptoms in nephritic rats. Male Wistar rats with glomerulonephritis induced by a single intravenous injection of nephrotoxic serum were fed either a 20% casein diet (control), 8.5% casein diet, 8.5CMT, or L-arginine-supplemented 8.5CMT (8.5CMTA) for 16 days. The 8.5CMTA, as compared with the 8.5CMT, aggravated proteinuria and glomerulonephritis. Administration of L-N(G)-nitroarginine methyl ester, an inhibitor of nitric oxide synthase, to 8.5CMTA-fed nephritic rats by drinking water for 14 days canceled the adverse effect of L-arginine on proteinuria and histopathological damage in glomeruli. These results suggest that the supplementation of L-arginine makes exacerbation via nitric oxide production in glomerulonephritis.

Animals↗
PubMed2001

Characterization of isotype-specific regions of five classes of canine beta-tubulin and their expression in several tissues and cell culture.

The structure of isotype-specific regions of classes 1, II, III, IVa and IVb of canine beta-tubulin was characterized by 3'-RACE and the expression of these isotypes in canine tissues was examined by ribonuclease protection assay (RPA). Furthermore, a malignant mammary tumor-derived osteosarcoma-like cell line was established and the altered expression of beta-tubulin isotypes in taxol-resistant sublines was analyzed. The deduced amino acid sequences in isotype-specific regions corresponding to classes I, II and IVb were identical to those of humans and mice, but those in classes III and IVa showed slight differences among species. RPA revealed that classes I and IVb were widely distributed, but classes II, III and IVa were restricted to the brain. Because RPA could clearly distinguish the expression of class IVa from that of class IVb, it was thought to be more useful than northern blot for analysis of beta-tubulin isotype expression. In vitro, taxol-resistant sublines displayed a significant increase in class IVa as compared with taxol-sensitive cells, suggesting that altered expression of class IVa was associated with taxol resistance in these cell lines.

Amino Acid Sequence↗
PubMed2001

Estimation of the antioxidant activities of flavonoids from their oxidation potentials.

A simple electrochemical method for estimating the antioxidant activity (AA) of flavonoids has been developed. The proposed method is based on a measurement of the half-wave potential (E1/2) of the first oxidation wave of flavonoids by using flow-through column electrolysis. At the same time, the lipid peroxidation (LPO) inhibiting effects of these flavonoids were determined. A quantitative structure-activity relationship was obtained to describe the AA of flavonoids: IC50(microM) = 30.36 + 151.50 E1/2 (V) -12.63 log P (r = 0.852), where IC50 represents the concentration for 50% inhibition of LPO, and P represents the octanol/water partition coefficient. This method is expected to be useful for the quick screening of flavonoid antioxidants, and evaluating the AA of flavonoid-containing foods and medicinal plants.

Animals↗
PubMed2001

Frequent allelic loss/imbalance on the short arm of chromosome 3 in tongue cancer.

Frequent allelic imbalances including loss of heterozygosity (LOH) and microsatellite instability (MSI) on the short arm of chromosome 3 (3p) have been found in several types of human cancer. This study was designed to identify the tumor suppressor locus (or loci) on 3p associated with tongue squamous cell carcinoma (SCC). Among 16 patients with tongue SCC tested, 7 (44%) of 16 informative cases showed LOH at one or more loci. Deletion mapping of these 16 tumors revealed two discrete, commonly deleted regions on the chromosome arm. Our data support the notion that tumor suppressor gene(s) contributing to the progression of tongue squamous cell carcinoma reside on 3p24 and 3p25.

Carcinoma, Squamous Cell↗
PubMed2001

Analysis of a role for p16/CDKN2 expression and methylation patterns in human oral squamous cell carcinoma.

The p16/CDKN2 (cyclin dependent kinase number 2) gene is known to be one of the negative regulators of the cell cycle. Aberrant 5'CpG island methylation is one of the most important mechanisms of p16/CDKN2 gene promoter region alteration. We studied 8 oral squamous cell carcinoma cell lines and 25 primary tumor tissues for the p16/CDKN2 gene and its expression by PCR-SSCP, MSP, RT-PCR, and immunohistochemical methods to determine the mechanism and the potential biological significance of p16/CDKN2 gene inactivation. In primary tumors, no p16/CDKN2 gene mutations were found by PCR-SSCP. However, hypermethylation of the CpG sites of p16/CDKN2 gene was observed in 48% (12/25) cases of primary tumors and in 50% (4/8) of cell lines. To verify the p16 mRNA expression, we employed RT-PCR and observed decreased or lacked p16 mRNA in 44% (11/25) of primary tumor tissues. In addition, hypermethylation was observed in 6 of the above 11 cases (55%). An immunohistochemistry assay was also performed with the primary tumor tissues, and a semi-quantitative method was used to evaluate the staining intensity of p16 protein. We observed 52% (13/25) negative nuclear staining. When we compared these results with clinicopathological stages, there was no statistical significance. These findings suggest that hypermethylation of p16/CDKN2 promoter region may be associated with p16/CDKN2 gene alteration.

Aged↗
PubMed2001

[Genetic abnormalities of regulatory mechanism of appetite].

Recently, leptin was cloned and characterized as a sateity factor which acts through the hypothalamus. alpha-melanocyte-stimulating hormone derived from pro-opiomelanocortin(POMC) and melanocortin receptor-4(MC4-R) have been reported to be involved in the downstream of the effect of leptin. In this paper, we summarized the clinical characteristics and the mechanisms of obesity caused by genetic abnormalities involved in the regulatory mechanism of appetite such as leptin, leptin receptor, POMC, MC4-R and prohormone convertase 1.

Animals↗
PubMed2001

[Two cases of alpha-fetoprotein producing gastric cancer, showing marked response to continuous hepatic arterial infusion (HAI) chemotherapy with adriamycin].

We report two cases of alpha-fetoprotein producing gastric cancer (AFPGC) with multiple liver metastases showing marked response to continuous HAI chemotherapy with adriamycin (ADM). In both cases, 5-FU 500 mg/body/day and Leucovorin (LV) 30 mg/body/day was infused continuously for 7 days and ADM 30 or 60 mg/body/day was infused continuously for 4 hours on day 7 as preoperative HAI chemotherapy. The primary gastric lesions were reduced and became resectable. After gastrectomy, they were treated with 4-hour continuous HAI of ADM 30 or 60 mg/body with or without 5-FU and LV once a week several times in our outpatient clinic. After these treatments, the multiple liver metastases were reduced remarkably, with a marked decrease of serum AFP levels. During these treatments, neither patient showed remarkable side effects, so they could work as before. This frequently low-dose ADM administration resulted in a high local response without severe side effects.

Antibiotics, Antineoplastic↗
PubMed2001

[Intubation with a double lumen tube in patients with difficult airway using endoscopy mask, and tracheal tube guide].

A 71-year-old-man with pneumothorax was scheduled for a video-assisted-thoracic-surgery. He had received subtotal resection of the mandible and was anticipated to have difficult airway. Anesthesia was induced by fentanyl, midazolam, and maintained by 0.4% isoflurane in pure oxygen. The patient was ventilated using Endoscopy Mask, having a port for fiberscopy. A fiberoptic bronchoscope and an endotracheal tube can be passed through the port without significant air leakage during positive pressure ventilation. First, a single lumen orotracheal tube was passed through the port, and Endoscopy Mask was removed. Then, a Tracheal Tube Guide was inserted through the single lumen tube. After the tube had been removed, a double lumen tube was advanced into the trachea guided by the Tracheal Tube Guide. During this procedure oxygen saturation was maintained at 100%.

Aged↗
PubMed2001

[Repeated intraperitoneal chemotherapy for peritoneal dissemination from gastric carcinoma].

Repeated intraperitoneal chemotherapy (RIC) via an i.p. port system was carried out in 16 patients with peritoneal dissemination (P1) and in 10 with positive washing cytology (P0.CY1) from gastric carcinoma. CDDP dissolved in 500-1,000 ml of physiological saline solution was periodically administered via the i.p. port system. The change of washing cytology (CY), which was obtained from i.p. port, was examined before each administration as a indicator of the response. The average number of administrations was 5.7 and the average total dose was 301.7 mg. As a result, a negative change of CY after RIC was found in 74% of patients, and also more than 80% of the response occurred within three administrations. The prognosis tended to be better in P0.CY1 patients than in P1 patients. In particular, the median survival time of the CY responders markedly improved as compared with non-responders (27.8 months versus 7.1 months). Although diarrhea and anorexia of grade 3 developed once in each patient, serious toxicities were not found. In conclusion, we consider RIC to be an effective therapy for P0.CY1 among cases with peritoneal dissemination from gastric carcinoma.

Antineoplastic Agents↗
PubMed2000

Pure autonomic failure in association with human alpha-synucleinopathy.

We studied an autopsy case with pure autonomic failure, using anti-alpha-synuclein antibody. Until now there has been no report about the immunohistochemical properties of alpha-synuclein in pure autonomic failure. In conventional stainings, both pre- and post-ganglionic lesions of the sympathetic and parasympathetic nervous systems were found. Lewy bodies and Lewy neurites were abundant especially in the sympathetic nervous system. These inclusions were immunoreactive to anti-alpha-synuclein antibody. The intensity of alpha-synuclein immunoreactivity was stronger in the halos than in the cores of the Lewy bodies. The edges of the swollen neurites had strong immunoreactivity. The substantia nigra was well preserved, and no cortical Lewy bodies were seen. These findings indicate that pure autonomic failure is one of the Lewy body type alpha-synucleinopathies, such as Parkinson's disease and dementia with Lewy bodies, targeting the peripheral autonomic nervous system.

Aged↗
PubMed2000

Human Cdc7-related kinase complex. In vitro phosphorylation of MCM by concerted actions of Cdks and Cdc7 and that of a criticial threonine residue of Cdc7 bY Cdks.

huCdc7 encodes a catalytic subunit for Saccharomyces cerevisae Cdc7-related kinase complex of human. ASK, whose expression is cell cycle-regulated, binds and activates huCdc7 kinase in a cell cycle-dependent manner (Kumagai, H., Sato, N., Yamada, M., Mahony, D. , Seghezzi, W., Lees, E., Arai, K., and Masai, H. (1999) Mol. Cell. Biol. 19, 5083-5095). We have expressed huCdc7 complexed with ASK regulatory subunit using the insect cell expression system. To facilitate purification of the kinase complex, glutathione S-transferase (GST) was fused to huCdc7 and GST-huCdc7-ASK complex was purified. GST-huCdc7 protein is inert as a kinase on its own, and phosphorylation absolutely depends on the presence of the ASK subunit. It autophosphorylates both subunits in vitro and phosphorylates a number of replication proteins to different extents. Among them, MCM2 protein, either in a free form or in a MCM2-4-6-7 complex, serves as an excellent substrate for huCdc7-ASK kinase complex in vitro. MCM4 and MCM6 are also phosphorylated by huCdc7 albeit to less extent. MCM2 and -4 in the MCM2-4-6-7 complex are phosphorylated by Cdks as well, and prior phosphorylation of the MCM2-4-6-7 complex by Cdks facilitates phosphorylation of MCM2 by huCdc7, suggesting collaboration between Cdks and Cdc7 in phosphorylation of MCM for initiation of S phase. huCdc7 and ASK proteins can also be phosphorylated by Cdks in vitro. Among four possible Cdk phosphorylation sites of huCdc7, replacement of Thr-376, corresponding to the activating threonine of Cdk, with alanine (T376A mutant) dramatically reduces kinase activity, indicative of kinase activation by phosphorylation of this residue. In vitro, Cdk2-Cyclin E, Cdk2-Cyclin A, and Cdc2-Cyclin B, but not Cdk4-Cyclin D1, phosphorylates the Thr-376 residue of huCdc7, suggesting possible regulation of huCdc7 by Cdks.

Antigens, Viral, Tumor↗
PubMed2000

Expression of invariant chain and pro-cathepsin L in Alzheimer's brain.

Inflammatory and immune systems are involved in the pathogenesis of Alzheimer's disease (AD), but those systems in the human brain have not been well identified. Cathepsin L might play a predominant role in the degradation of the invariant chain (Ii), which plays a critical role in antigen presentation to block the antigen-binding site of the major histocompatibility complex class II. We examined the expression of Ii and pro-cathepsin L (pCPL) in AD and normal brains by using immunohistochemistry. Ii expresses only in resting or mildly activated microglia, whereas pCPL strongly expresses in fully activated microglia but not in resting or mildly activated microglia in AD. Normal brain tissues have rarely been stained for Ii or pCPL. These results suggest that the activation of microglia leads to expression of a complex of Ii and human leukocyte antigen class II at first, and that further activation, which is followed by cluster formation and enlargement of microglia frequently seen in the AD brain, might cause pCPL expression to degrade Ii. Our study confirmed that microglia plays a central role in the immune system of the brain, and that an activation of microglia is involved in the pathogenesis of AD.

Aged↗
PubMed2000

Dbf4 motifs: conserved motifs in activation subunits for Cdc7 kinases essential for S-phase.

Dbf4 and its related molecules were originally identified as cyclin-like partners for Cdc7 kinases, essential for S-phase. Recent reports and database search indicate the presence of multiple Dbf4-related molecules with distinct functions. We have identified three stretches of amino acids which are conserved in various Dbf4-related molecules and possibly play distinct functions in binding to and activation of the catalytic subunits as well as in interactions with other proteins. Discovery of conserved motifs for this possible new protein family would serve as a useful framework for future identification of new members of this family as well as for probing their functions.

Amino Acid Motifs↗
PubMed2000

Determination of catechins in human urine subsequent to tea ingestion by high-performance liquid chromatography with electrochemical detection.

The title determination was conducted by HPLC with electrochemical detection using an ODS column and a mobile phase of acetonitrile: 0.1 M phosphate buffer (pH 2.5) (15:85, v/v). The eight catechins, gallocatechin (GC), epigallocatechin (EGC), catechin (C), epicatechin (EC), epigallocatechin gallate (EGCg), gallocatechin gallate (GCg), epicatechin gallate (ECg), and catechin gallate (Cg), were detected at 0.6 V vs Ag/AgCl. Good linear relationships between current and amount were noted for 0.5-250 pmol of each catechin, with a correlation coefficient of 0.999 in each case. The detection limit for any one was 0.5 pmol (signal to noise ratio, S/N = 3). After the ingestion of 340 ml canned green tea, GC, EGC, C, and EC, mostly in conjugated form, were determined in urine samples. Conjugated catechins were hydrolyzed by enzymes using sulfatase and beta-glucuronidase. The time courses of the above four catechins showed a maxima at 1-3 h after tea ingestion. (+), (-)-EC and (+), (-)-C were present in canned tea.

Acetonitriles↗
PubMed2000

Form of human p53 protein during nuclear transport in Xenopus laevis embryos.

The p53 protein binds DNA as a tetramer inside the nucleus, but a form of the p53 protein during nuclear transport has not been fully elucidated. To verify whether the human p53 protein passes through the nuclear pore as a monomer or oligomer, two different p53 mutants N1 and C1NLS- with or without a nuclear localization signal (NLS), respectively, were expressed in Xenopus laevis embryos. By the whole-mount immunostaining method, their intracellular distributions were observed to exist in an NLS-dependent manner. In a immunoprecipitation assay system, NLS-defective mutants formed oligomer in the cytoplasm. When coexpressed with NLS-containing N1, C1NLS- still stayed in the cytoplasm and did not inhibit N1 transport into the nucleus. Furthermore, when oligomerization-defective p53 mutant was expressed in Xenopus embryos, efficiency of its nuclear transport was demonstrated to be unchanged compared to that of the wild type. Assuming that NLS-defective p53 mutants have no dominant-negative effect on wild-type p53 in the nucleus of p53 heterozygous cells, we investigated the dominant-negative effect by CAT activity assay using human cell line Saos-2 and NLS-defective mutants. It was found that the NLS-defective p53 mutant did not have a dominant-negative effect on the function of wild-type p53 protein in the nucleus. Data indicate that each monomeric p53 protein independently passes through the nuclear pore; however, the possibility of homooligomeric p53 protein transport into the nucleus is not completely excluded.

Animals↗
PubMed2000

NFATz: a novel rel similarity domain containing protein.

Nuclear Factor of Activated T cell (NFAT) is a family of transcription factors that are important for the coordinate expression of various cytokines and immunoregulatory cell surface molecules in T cells and other types of cells in the immune system. In addition, analysis of gene disrupted mice revealed that some members of NFAT family are important for the development of myocardium, myocardial hypertrophy, and mesenchymal stem cells. NFAT family proteins have two conserved domains, the NFAT Homology Domain (NHD) and the Rel Similarity Domain (RSD). The RSD is DNA binding and AP-1 interacting domain which has structural similarity to the Rel Homology Region, the DNA binding domain of Rel family proteins. The NHD is a regulatory domain required for the Ca regulated translocation of NFAT. We report here the isolation and initial characterization of a novel RSD containing protein designated NFATz. NFATz has a RSD but no NHD. NFATz protein is localized in the nucleus without Ca signal. There is no detectable binding to a typical NFAT site even in the presence of AP-1, and it is not capable of activating transcription through the NFAT site. The chromosomal location determined by FISH revealed that NFATz and NFATx genes are in the same region.

Amino Acid Sequence↗