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Biomedical subjects

A Nakashima

Publications and source records attributed to A Nakashima.

At least 55 records · Page 3Linked to original sources
PubMed1999

[Antioxidative effects of fluvastatin, and its major metabolites].

Fluvastatin (FV) is a highly potent inhibitor of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase. Recently, its antioxidant effect caused by inhibiting the formation of low density lipoproteins (LDL) in vitro has been reported. In this study, we reported the antioxidant effects of FV and its major metabolites in human (M-2, M-3, M-4, M-5, and M-7) on lipid peroxidation using rat liver microsomes. The extent of NADPH-induced microsomal (Ms) lipid peroxidation was determined by the thiobarbituric acid (TBA) assay. The antioxidant effect of each compound was shown as the percentage of inhibition on the formation of TBA reactive substances (TBARS) against the vehicle control. Probucol (PR), a potent antioxidant drug, was used as a reference control. The concentration of each compound in this experiment was set at 0.1 mM (final conc.). FV inhibited the formation of TBARS by 30 to 60% without depending on the used Ms concentrations (0.025-0.2 mg protein/ml). The antioxidant effects of M-2, M-3, and M-5 were comparable to that of FV at low Ms concentrations. At the highest Ms concentration, however, the antioxidant effects of these metabolites were considerably higher than that of FV. Inhibition of the formation of TBARS by M-4 or M-7 was approximately 30% of the control and independent of the used Ms concentrations. The antioxidant effect of PR was comparable to those of M-2, M-3, and M-5 in this study. Pravastatin (PV), a potent inhibitor of HMG-CoA reductase, reduced the formation of TBARS around 20% at 0.25 or 0.5 mg protein/ml of Ms concentrations. But the value of percentage of inhibition was around 5% at 0.1 or 0.2 mg protein/ml of Ms concentrations. In conclusion, the antioxidant effects of FV, M-2, M-3, and M-5 were found to be comparable to that of PR.

Animals↗
PubMed1998

Characterization of fetal serum 5'-nucleotide phosphodiesterase: a novel function as a platelet aggregation inhibitor in fetal circulation.

The study was performed to indicate the ADPase activity of 5'-nucleotide phosphodiesterase (PDEase) from human umbilical cord blood serum and demonstrates the effect of this enzyme on ADP-induced platelet aggregation. The PDEase was purified by using p-nitrophenyl-5'-TMP as a substrate. The PDEase had a molecular weight of 128,000 daltons, and activity of 103 nmol/min/mg protein. The PDEase activity was inhibited by 5'-AMP, ADP, ATP. But 2'-AMP, 3'-AMP, 3':5' cAMP, and adenosine had no inhibiting effects. Kinetic analysis indicated that ADP was a competitive inhibitor with a Ki value of 4.05x10(-5) M. The enzyme was markedly inhibited by 1 mM EDTA. The ADPase activity of the PDEase was 7.79 nmol/min/mg protein. The hydrolized products of ADP by the PDE ase were AMP and phosphoric acid. The platelet aggregation by ADP was inhibited by the addition of the PDEase in the platelet-rich plasma.

Adenosine Diphosphate↗
PubMed1998

Metabolism and ribonucleotide reductase inhibition of (E)-2'-deoxy-2'-(fluoromethylene)cytidine, MDL 101,731, in human cervical carcinoma HeLa S3 cells.

UNLABELLED: (E)-2'-Deoxy-2'-(fluoromethylene)cytidine, MDL 101,731, has shown potent antitumor activity against various human xenograft models. PURPOSE: The purpose of this study was to elucidate the mechanism of the antitumor activity of MDL 101,731 against human carcinoma cells through investigating metabolism and the target enzyme of MDL 101,731. METHODS: In respect of the intracellular metabolism of MDL 101,731, the effect on enzymes in the pyrimidine salvage pathway and the intracellular metabolites of MDL 101,731 were investigated. In respect of the target enzyme, the effect on intracellular deoxyribonucleoside triphosphate (dNTP) pools and the inhibition of the enzyme activity were investigated. RESULTS: MDL 101,731 which shows antiproliferative activity against human cervical carcinoma HeLa S3 cells at nanomolar concentrations (IC50, 30-50 nM), was hardly metabolized to (E)-2'-deoxy-2'-(fluoromethylene)uridine (FMdU) which had no antiproliferative activity below 100 microM because of resistance to human cytidine deaminase. MDL 101,731 showed low activity against murine lymphocytic leukemia P388R cells (Ara-C-resistant cells) which contained lower deoxycytidine kinase activity than parental P388 cells. In addition, the antiproliferative activity of MDL 101,731 against HeLa S3 cells was reversed by deoxycytidine. Studies of the intracellular metabolism of 3H-MDL 101,731 demonstrated that it was rapidly metabolized to the diphosphate and the triphosphate forms without the other metabolites in HeLa S3 cells. A 3-h treatment with 0.1-10 microM MDL 101,731 decreased intracellular dNTP pools. The recovery of dNTP pools decreased by treatment with 2 microM MDL 101,731 was much slower than the recovery following treatment with 10 mM hydroxyurea, a reversible ribonucleotide reductase inhibitor. At a dose of 250 mg/kg, MDL 101,731 continuously inhibited ribonucleotide reductase activity up to 72 h in a HeLa S3 xenograft model. CONCLUSIONS: This study suggests that the prolonged ribonucleotide reductase inhibition by rapidly activated metabolites of MDL 101,731 in part contributes to the potent antitumor activity of this drug against various xenografts.

Antineoplastic Agents↗
PubMed1998

Enzymes related to catecholamine biosynthesis in Tetrahymena pyriformis. Presence of GTP cyclohydrolase I.

We first identified GTP cyclohydrolase I activity (EC 3.5.4.16) in the ciliated protozoa, Tetrahymena pyriformis. The Vmax value of the enzyme in the cellular extract of T. pyriformis was 255 pmol mg-1 protein h-1. Michaelis-Menten kinetics indicated a positive cooperative binding of GTP to the enzyme. The GTP concentration producing half-maximal velocity was 0.8 mM. By high-performance liquid chromatography (HPLC) with fluorescence detection, a major peak corresponding to D-monapterin (2-amino-4-hydroxy-6-[(1'R,2'R)-1',2',3'-trihydroxypropyl]pteridin e, D-threo-neopterin) and minor peaks of D-erythro-neopterin and L-erythro-biopterin were found to be present in the cellular extract of Tetrahymena. Thus, it is strongly suggested that Tetrahymena converts GTP into unconjugated pteridine derivatives. In this study, dopamine was detected as the major catecholamine, while neither epinephrine nor norepinephrine was identified. Indeed, this protozoa was shown to possess the activity of a dopamine synthesizing enzyme, aromatic L-amino acid decarboxylase. On the other hand, activities of tyrosine hydroxylase or tyrosinase which converts tyrosine into dopa, the substrate of aromatic L-amino acid decarboxylase, could not be detected in this protozoa. Furthermore, neither dopamine beta-hydroxylase activity nor phenylethanolamine N-methyltransferase activity could be identified by the HPLC methods.

Amino Acid Sequence↗
PubMed1998

DNA-binding properties of the overexpressed recombinant estrogen receptor alpha.

Estrogen receptor alpha was overexpressed in COS-7 cells by transformation of an expression vector with the full length open reading frame of the receptor alpha. The nuclear estradiol-receptor complex and the soluble receptor from the COS-7 cells were cross-linked with an estrogen response element (ERE), which was substituted with 5-bromo-2'-deoxyuridine (BrdUVRE), as the receptor dimers by UV irradiation. In gel retardation analysis, the specific bindings of both nuclear and soluble receptors to ERE were decreased with increasing of KCl concentration compared with 0.1 M KCl. The ionic interactions of both receptors with ERE are thought to be similar.

Animals↗
PubMed1998

Telomere length, telomerase activity and telomerase RNA expression during mouse mammary tumor progression.

To investigate the roles of telomere length (mean length of the terminal restriction fragments; TRFs), telomerase activity (TA) and telomerase RNA (mTR) expression in relation to mouse mammary tumor progression, we examined a pregnancy-dependent mouse mammary tumor line (TPDMT-4) and its four autonomous sublines (T4-OI320: non-metastatic; and T4-OI165, -OI96, and -OI145: artificial metastatic) of DDD/1 mouse origin, and an autonomous growing mammary tumor (JYG-MC) showing spontaneous lung metastasis developed in BALB/c mice infected with a Chinese feral mice (Sub-Jyg)-derived mouse mammary tumor virus (JYG-MTV). Compared with normal (pregnant) mammary tissue, the TA was elevated in the TPDMT-4 tumor and in the non-metastatic subline tumor (T4-OI320) (x10 fold, respectively), and was further increased (x13-15 fold) in parallel with the acquisition of metastatic potential (T4-OI165, -OI96, and -OI145). The mTR level was upregulated (x2.7-2.8 fold) in all autonomous growing tumors compared to the normal counter-part, but not in TPDMT-4. The TRF was shorter in accord with tumor progression (normal mammary tissue, 48 kb; TPDMT-4, 45 kb; T4-OI320, 37 kb; T4-OI165, -OI96 and -OI145, mean 37.7 kb; and JYG-MC, 21 kb). These results suggest that the activation of TA occurs as an early event at the stage of hormone-dependent tumorigenesis, followed by the up-regulation of mTR expression in accordance with the acquisition of autonomous growth, and then further activation of TA occurs when the tumor acquires metastatic potential. The TRF shortening was in parallel with the tumor progression.

Animals↗
PubMed1998

Clinicopathologic study of multiple primary superficial carcinoma of the esophagus.

Endoscopic examination with iodine staining has led to the easy detection of multiple superficial esophageal carcinoma (MSEC). The purpose of this study was to better understand the characteristics of MSEC. Of 49 patients with multiple esophageal carcinomas, 19 had superficial carcinoma. Multiple esophageal carcinomas were more often found in superficial carcinomas (31.1%) than in advanced carcinomas (14.4%). Comparing the depth of invasion of multiple esophageal carcinomas, the secondary lesions represented relatively early stages. Ki-67-positive cells were seen significantly more frequently in the main lesion of MSEC than in the secondary lesions, but proliferating cell nuclear antigen positivity and p53 expression did not differ significantly. Since multiple carcinoma occurs more frequently, care should be taken to look for small secondary lesions when treating superficial esophageal carcinoma. Ki-67 immunohistochemistry suggested that tumor cells proliferate more slowly in secondary lesions than in main lesions of MSEC.

Antibodies, Monoclonal↗
PubMed1998

[A case of refractory pulmonary fistula, managed with bronchoscopic therapy using occluding spiral embolus].

We report a successful case of bronchoscopic therapy using occluding spiral embolus and fibrin glue for refractory pulmonary fistula. A 22-year-old female underwent left lower lobectomy for giant bulla of the lung. Air leakage began 6 days after lobectomy. Closing alveolar fistula was performed 12 days after first operation. Relapsing air leakage began 4 days after second operation. Bronchography revealed a fistula from left B1+2c. The insertion of embolus through bronchofiberscope, following administration of fibrin glue, was performed to close the fistula. This method is effective for refractory pulmonary fistula.

Adult↗
PubMed1998

[Enhanced MR imaging with a nonionic contrast gadolinium complex, Gadoteridol, for lumbar disc herniation].

The aim of this study was to evaluate the usefulness for lumbar disc herniation of enhanced imaging with a nonionic contrast gadolinium complex (Gadoteridol). Among 130 discs in 26 patients, 27 herniated discs were shown on MR sagittal imaging. They were classified into 4 types according to the enhancement pattern of the disc on MR sagittal imaging (Type Ia: nonenhancement, Type Ib: globular enhancement, Type II: strong enhancement, Type III: ring enhancement). The results were as follows: Type Ia: 3, Type Ib: 15, Type II: 7, Type III: 2. A total of herniated discs were enhanced with Gadoteridol. Surgery was performed in 5 patients (Type Ib: 1, Type II: 4). The herniated disc of Type Ib extruded but did not rupture the posterior ligament, whereas the herniated discs of Type II extruded and ruptured the posterior ligament. Thus, the herniated discs were enhanced with the nonionic contrast agent Gadoteridol. If the disc herniates over the posterior ligament, it might be strongly enhanced. Therefore, enhanced MR imaging is thought to be useful to establish the diagnosis of lumbar disc herniation.

Adult↗
PubMed1997

Effect of lipopolysaccharide on the gene expression of the enzymes involved in tetrahydrobiopterin de novo biosynthesis in murine neuroblastoma cell line N1E-115.

The amounts of messenger RNA for three enzymes, namely guanosine triphosphate (GTP) cyclohydrolase 1,6-pyruvoyltetrahydropterin synthase, and sepiapterin reductase, all of which are involved in the de novo biosynthesis of (6R)-L-erythrodihydroxypropyl-2-amino-4-hydroxy-5,6,7,8-tetrahydro pteridine (BH4) from GTP, were measured quantitatively in murine neuroblastoma cell line N1E-115 by the competitive polymerase chain reaction (PCR) technique after reverse transcription using a heterologous DNA fragment as an internal standard. Twenty-four hour activation of this cell line with 1 microg/ml lipopolysaccharide resulted in statistically significant increases in the amounts of the messages of all three enzymes. Our data suggest that lipopolysaccharide can activate the intrinsic pathway resulting in the enhanced gene expression of these three enzymes in neuron-derived cells such as N1E-115.

Alcohol Oxidoreductases↗
PubMed1997

Suppression of the Saccharomyces cerevisiae hac1/ire15 mutation by yeast genes and human cDNAs.

We previously reported that the Saccharomyces cerevisiae ire15 mutation results in an inositol-auxotrophic phenotype, and that human cDNAs can suppress the ire15 mutation (Nikawa, J., 1994. A cDNA encoding the human transforming growth factor beta receptor suppresses the growth defect of a yeast mutant. Gene 149, 367 372; Nikawa, J., Nakano, H., Ohi, N., 1996b. Structural and functional conservation of human and yeast HAC1 genes which can suppress the growth defect of the Saccharomyces cerevisiae ire15 mutant. Gene 171, 107-111). Herein, we present evidence that the gene responsible for the ire15 mutation is HAC1, which encodes a transcription factor for KAR2, obtained by isolating a yeast single-copy supressor gene and by performing complementation analysis. Sequencing analysis revealed that the mutant HAC1 gene obtained from the ire15 mutant contained an AAA codon at position 50 instead of the AGA codon observed in the wild-type gene, resulting in the alteration of the aa from Arg to Lys. All human cDNAs and yeast multicopy suppressors, which had been isolated as suppressors for the ire15 mutation, were able to suppress the inositol-auxotrophic phenotype but not the defect in KAR2 induction of the hac1-disrupted strain.

14-3-3 Proteins↗
PubMed1997

Effects of dopamine on N-terminus-deleted human tyrosine hydroxylase type 1 expressed in Escherichia coli.

N-Terminus-deleted mutants and wild-type human tyrosine hydroxylase type 1 were expressed in Escherichia coli (E. coli) and utilized to investigate the dopamine-induced decrease in the enzyme catalytic activity and also to identify the specific portion in the N-terminus that affects the efficiency of the inhibitory action of dopamine. Supernatants of bacterial lysates were used as enzyme samples. The pH profiles of the enzyme catalytic activity were affected according to the degree of the deletion. The deletion up to 39 amino acid residues was enough to abolish the inhibitory effect of dopamine in the basic pH range. These results suggest that the inhibition by dopamine of tyrosine hydroxylase activity is closely related to the amino acid sequence in the N-terminus of the enzyme.

Amino Acid Sequence↗
PubMed1997

Lymphocytes bursting induced by heparin, dextran sulfate and other polyanions.

We found that high molecular polyanions (PAs) such as dextran sulfate and heparin burst some damaged or dead lymphocytes in lymphocyte suspension isolated from living bodies, and clarified morphologically the mechanism involved in this. PAs passed through damaged cell membranes and reached the chromatin in the nucleus. Electron micrographs suggested that they then extracted histones from the chromatin and formed complexes with them, and that freed DNA formed a gel binding with the complexes in the nucleus, and the nucleus became swollen and burst due to the gel swelling pressure. To support this conjecture, the nuclei of lymphocytes were stained with propidium iodide and exposed to light to stabilize them. The stabilized nuclei were not swollen after the addition of PAs and the lymphocytes did not burst. The lymphocyte bursting effect of PAs was attributed to their negative charges which could not destroy intact cells. At this point, PAs are different from sodium dodecyl sulfate which destroys intact cells completely.

Animals↗
PubMed1997

Cloning of a human cDNA for CTP-phosphoethanolamine cytidylyltransferase by complementation in vivo of a yeast mutant.

CTP-phosphoethanolamine cytidylyltransferase (ET) is the enzyme that catalyzes the formation of CDP-ethanolamine in the phosphatidylethanolamine biosynthetic pathway from ethanolamine. We constructed a Saccharomyces cerevisiae mutant of which the ECT1 gene, putatively encoding ET, was disrupted. This mutant showed a growth defect on ethanolamine-containing medium and a decrease of ET activity. A cDNA clone was isolated from a human glioblastoma cDNA expression library by complementation of the yeast mutant. Introduction of this cDNA into the yeast mutant clearly restored the formation of CDP-ethanolamine and phosphatidylethanolamine in cells. ET activity in transformants was higher than that in wild-type cells. The deduced protein sequence exhibited homology with the yeast, rat, and human CTP-phosphocholine cytidylyltransferases, as well as yeast ET. The cDNA gene product was expressed as a fusion with glutathione S-transferase in Escherichia coli and shown to have ET activity. These results clearly indicate that the cDNA obtained here encodes human ET.

Amino Acid Sequence↗
PubMed1997

Inhibition of intimal hyperplasia after balloon injury by antibodies to intercellular adhesion molecule-1 and lymphocyte function-associated antigen-1.

BACKGROUND: Although intercellular adhesion molecule-1 (ICAM-1) is known to be expressed in balloon-injured arteries, it remains unknown whether ICAM-1 plays a role in the progression of intimal hyperplasia (IH) induced by balloon injury. METHODS AND RESULTS: We examined the ICAM-1 expression in rat carotid arteries at 1, 2, 5, 7, 10, and 14 days after injury by immunohistochemistry. Medial smooth muscle cells (SMC) expressed ICAM-1 intensely at 1 to 2 days after injury. The regenerating endothelial cells expressed ICAM-1 more than did those of intact carotid arteries. To investigate the effects of monoclonal antibodies (MAbs) on IH, we examined the intima/ medial ratio of arteries at 2 weeks after injury in five treatment groups: nonimmune IgG, anti-membrane glycoprotein MAb, anti-lymphocyte function-associated antigen-1 (LFA-1) MAb, anti-ICAM-1 MAb, and anti-ICAM/LFA-1 MAb. Treatments were administered intravenously into rats for 6 consecutive days after injury. MAb against LFA-1 alone or membrane glycoprotein had no effect on IH. The intima/media ratios in anti-ICAM-1 MAb-treated and anti-ICAM-1/LFA-1 MAb-treated animals were significantly less than those in nonimmune IgG-treated and anti-membrane glycoprotein MAb-treated animals (P < .05). CONCLUSIONS: Balloon injury induced or upregulated the ICAM-1 expression on vascular SMC and on regenerating endothelial cells. MAb against ICAM-1 or ICAM-1/LFA-1 attenuated IH. These results suggest that ICAM-1 may play a role in the progression of IH after injury in rats.

Animals↗
PubMed1997

High-performance liquid chromatographic separation of kyotorphin, a basic Tyr-Arg dipeptide, in rat brain tissue and quantification using fluorimetric detection.

Two HPLC procedures based on sample derivatization at the N-terminal Tyr moiety with agents yielding fluorescent derivatives were applied to the selective and sensitive detection as well as quantification of the basic kyotorphin, Tyr-Arg dipeptide, in rat brain tissue. The first one is a post-column fluorescence derivatization method, whereby the peptides extracted from the brain tissue are separated on an octadecylsilyl-silica gel column, followed by on-line fluorescence derivatization for detection. The other one is a pre-column derivatization method, where the extracted peptides are first reacted with fluorogenic agents at the N-terminal Tyr moiety to their corresponding fluorescent derivatives, subsequently separated on an octadecyl-poly(vinyl alcohol) copolymer gel column, and signal responses are measured fluorimetrically. Both methods permitted the quantification of the synthetic kyotorphin added to the rat brain tissues. The concentration range of kyotorphin-like biogenic peptide was 60-100 pmol/g in the cortex, striatum and hypothalamus tissues.

Animals↗
PubMed1997

Synergistic immunosuppression caused by high-dose methylprednisolone and cardiopulmonary bypass.

BACKGROUND: Steroid use during cardiac operations may reduce the risk of postperfusion lung syndrome, but both cardiopulmonary bypass and steroids are immunosuppressive. The synergistic effects of the bypass and steroids on patients' immunologic activities, hemodynamics, and metabolisms during and after heart operations have not been clarified systematically. METHODS: Twenty-four patients undergoing valve replacement were studied in a randomized, double-blind trial. Twelve of these patients (S group) received bolus methylprednisolone, 20 mg/kg body weight, and the remaining 12 patients (C group) received a placebo intravenously before and after bypass. Blood cell count, C-reactive protein, lymphocyte surface markers (CD3, CD4, CD8, CD16, and CD20), phytohemagglutinin response, interleukin-2 production, and natural killer cell activity were examined on admission through day 7. Cardiac output, blood gas, electrolyte, lactate, and serum glucose levels were examined perioperatively. RESULTS: The peak white blood cell count in the S group was higher than that in the C group (analysis of variance: p [group] = 0.0436). The peak C-reactive protein level was higher in the C group than in the S group (p [group] < 0.0001). From the analysis of the surface markers, the steroid increased the natural killer cells before and soon after bypass (p [group] = 0.0117), and later tended to increase the CD4+ T and B cells during the postoperative recovery period. The phytohemagglutinin response in both groups decreased after bypass (p [time] < 0.0001), but the steroid caused exaggerated decreases before (p < 0.01 by Student's t test) and soon after (p < 0.001) bypass in the S group (analysis of variance: p [group] = 0.0127). The interleukin-2 production was suppressed by bypass alone after the bypass in the C group, but was further suppressed by the steroid before and after bypass in the S group (p [group] = 0.0446). The cardiac index, water balance, electrolytes, arterial oxygen tension, and timing of extubation were not different between the groups. In contrast, the glucose (p [group] = 0.0486) and lactate (p [group] = 0.0525) levels were higher in the S group than those in the C group. CONCLUSIONS: T-cell functions are synergistically suppressed by cardiopulmonary bypass and high-dose methylprednisolone in heart operations. The hemodynamic benefits of the steroid are negligible, whereas glucose tolerance is worsened by the steroid during bypass.

Antigens, Surface↗