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Biomedical subjects

T Nagatsu

Publications and source records attributed to T Nagatsu.

At least 127 records · Page 7Linked to original sources
PubMed1996

Interleukin (IL)-1 beta, IL-2, IL-4, IL-6 and transforming growth factor-alpha levels are elevated in ventricular cerebrospinal fluid in juvenile parkinsonism and Parkinson's disease.

Interleukin (IL)-1 beta , IL-2, IL-4, IL-6, epidermal growth factor (EGF), and transforming growth factor (TGF)-alpha were measured for the first time in ventricular cerebrospinal fluid (VCSF) from control non-parkinsonian patients, patients with juvenile parkinsonism (JP) and patients with Parkinson's disease (PD) by highly sensitive sandwich enzyme immunoassays. All cytokines were detectable in VCSF from control and parkinsonian patients, and the concentrations were much higher than those in lumbar CFS. The concentrations of IL-1 beta, IL-2, IL-4 and TGF-alpha in VCSF were higher in JP than those in controls (P < 0.05). In contrast, the concentrations of IL-2 and IL-6 in VCSF from patients with PD were higher than those from control patients (P < 0.05). These results agree with our previous reports, in which the cytokine levels were elevated in the striatal dopaminergic region of the brain from patients with PD. Since VCSF is produced in the ventricles, the alteration of cytokines in VCSF may reflect the changes of cytokines in the brain. Because cytokines play an important role as mitogens and neurotrophic factors in the brain, the increases in cytokines as a compensatory response may occur in the brain of patients of JP or PD during the progress of neurodegeneration. Increase in cytokines may contribute not only as a compensatory response but as a primary initiating trigger for the neurodegeneration.

Adolescent↗
PubMed1996

Regulation of N-terminus-deleted human tyrosine hydroxylase type 1 by end products of catecholamine biosynthetic pathway.

The N-terminal 52-, 70-, and 157-amino acids-deleted mutants and wild-type tyrosine hydroxylases were expressed in Escherichia coli and utilized to investigate the roles of the N-terminus in the catecholamine inhibition on enzyme activity. Their lysate's supernatants were used as enzyme samples. Three catecholamines, namely dopamine, norepinephrine, and epinephrine, affected both wild-type and mutant enzymes after preincubation in the mode of mixed inhibition, and the most marked alteration among the kinetic parameters produced by the deletion was the increase in the inhibition constants. The deletions also abolished the catecholamine-induced shift of the pH profile of the enzyme activity toward a more acidic pH optimum. All three mutants responded to catecholamines almost in the same way. These results suggest that the three catecholamine end products exert their inhibition on tyrosine hydroxylase to the same extent and that the N-terminal 52 amino acid residues contain the key sequence in mediating the inhibitory action.

Catalysis↗
PubMed1996

Interleukin-2 but not basic fibroblast growth factor is elevated in parkinsonian brain. Short communication.

The contents of interleukin (IL)-2 and basic fibroblast growth factor (bFGF) were measured in the brain (caudate nucleus, putamen, and cerebral cortex) from control and parkinsonian patients by highly sensitive enzyme-linked immunosorbent assay (ELISA). The concentrations of IL-2 in the brain were in the order of pg/mg protein, and the values were significantly higher in the caudate and putamen from parkinsonian patients than those from control patients. However, the levels of IL-2 in the cerebral cortex showed no significant difference between parkinsonian and control patients. In contrast to IL-2, the bFGF levels in the brain were high and in the order of ng/mg protein, and there was no significant difference in the caudate and putamen between parkinsonian and control patients. Although both IL-2 and bFGF may play important roles in dopaminergic neurons as neurotrophic factors, IL-2 but not bFGF may relate to the compensatory response in the nigrostriatal dopaminergic regions in parkinsonian brain during progress of neurodegeneration.

Aged↗
PubMed1996

Analysis of an alternative promoter that regulates tissue-specific expression of the human aromatic L-amino acid decarboxylase gene in cultured cell lines.

The human aromatic L-amino acid decarboxylase (AADC) gene is transcribed in a tissue-specific manner by an alternative promoter. In this study using human cultured cell lines, we analyzed the alternative promoter that regulates tissue-specific expression of AADC. Neither neuronal nor nonneuronal-type mRNA of AADC was detected in HeLa cells, nonneuronal-type mRNA of AADC was expressed in HepG2 cells, and the neuronal-type was expressed in the SK-N-SH cell line. We examined the promoter activities located in 5'- and 3'-flanking regions of exon N1 and exon L1 by transfection experiments. Plasmids containing 5'-flanking regions of exon L1, the shortest of which was 0.3 kb, could promote specifically high expression of the reporter gene HepG2 cells. On the other hand, plasmids containing 5'-flanking regions of exon N1 (3.6 kb to 0.5 kb) could promote the reporter gene expression not only in SK-N-SH cells but also in HeLa and HepG2. More enhanced expression were observed by transfection of plasmids containing parts of the first intron in these cell lines. Thus, these results suggest that the basal liver-specific promoter activity is located in the 5'-flanking region of exon L1 and that the first intron may also be needed for enhanced expression rather than determination of cell-specificity.

Aromatic-L-Amino-Acid Decarboxylases↗
PubMed1996

GTP cyclohydrolase I gene, tetrahydrobiopterin, and tyrosine hydroxylase gene: their relations to dystonia and parkinsonism.

Catecholamine biosynthesis is regulated by tyrosine hydroxylase (TH) requiring tetrahydrobiopterin (BH4) as the cofactor. We found four (human TH type 1-4) and two isoforms (TH type 1 and 2) in humans and monkeys, while non-primate animals have a single TH corresponding to human TH type 1. BH4 is synthesized from GTP, and GTP cyclohydrolase I (GCH) is the first and regulatory enzyme. Mutations in GCH gene were found to cause both GCH deficiency with autosomal recessive trait and hereditary progressive dystonia with marked diurnal fluctuation (HPD) (Segawa's disease)/or DOPA-responsive dystonia (DRD) with autosomal dominant trait. When GCH activity is decreased to less than 20% of the normal value, the activity of TH in the nigrostriatal dopaminergic neurons may be first decreased resulting in decreases in TH activity and dopamine level, and in the symptoms of HPD/DRD. In contrast to HPD/DRD, juvenile parkinsonism (JP) have normal GCH activity. In Parkinson's disease (PD), GCH, TH, and dopamine in the striatum may decrease in parallel, as the secondary effects caused by cell death.

Animals↗
PubMed1996

Effects of moclobemide on forced-swimming stress and brain monoamine levels in mice.

Moclobemide [Ro 11-1163, p-chloro-N-(2-morpholinoethyl)benzamide, AURORIX] is known as an antidepressant and a reversible inhibitor of type A monoamine oxidase. In the present study, a forced swimming test was applied to mice to evaluate behavioral and neurochemical effects of this drug. During forced swimming posture of immobility, a typical behavioral change, was observed, and biochemical analysis of the brain revealed significant changes in the monoamine levels. The norepinephrine concentration was reduced, while that of its product was increased, indicating increase in norepinephrine turnover. The stress increased the levels of dopamine, serotonin, and their metabolites. Moclobemide significantly improved the immobility elicited by the test, and it could prevent the changes in the turnover of norepinephrine, dopamine, and serotonin induced by the stress. These results suggest that moclobemide may improve the behavioral changes induced by the forced swimming through its effects on monoamine metabolism.

Animals↗
PubMed1996

Tetrahydrobiopterin biosynthesis enhanced by lipopolysaccharide stimulation in murine neuroblastoma cell line N1E-115.

We investigated for the first time the effect of lipopolysaccharide and the signal transduction pathway on the biosynthesis of tetrahydrobiopterin [(6R-L-erythro-1',2'-dihydroxypropyl) -2-amino-4-hydroxy-5,6,7,8-tetrahydropteridine], the cofactor for the enzymatic hydroxylation of the aromatic amino acids, in the murine neuroblastoma cell line N1E-115, which synthesizes tetrahydrobiopterin constitutively. Activation of N1E-115 cells with 1 microgram/ml lipopolysaccharide resulted in statistically significant increases in both intracellular tetrahydrobiopterin contents and the activity (Vmax) of GTP cyclohydrolase I, a rate-limiting enzyme in tetrahydrobiopterin de novo biosynthesis. Following simultaneous addition of the inhibitors of protein tyrosine kinases and GTP-binding proteins into serum-free culture media with lipopolysaccharide, we analyzed the transduction pathway of lipopolysaccharide signal toward the tetrahydrobiopterin biosynthetic system in N1E-115 cells. Our data indicate the following conclusions: (a) Protein tyrosine kinase systems are involved in mediating lipopoly-saccharide signal to tetrahydrobiopterin production, and (b) there may be a cross-talk between GTP-binding protein and the protein tyrosine kinase system in mediating lipopolysaccharide signal. These observations suggest that a neuronal cell such as N1E-115, which barely expresses CD14 on its cell surface, responds to lipopolysaccharide like macrophages and monocytes in the absence of soluble CD14.

Animals↗
PubMed1996

The role of L-aromatic amino acid decarboxylase in serotonin-stimulated aldosterone secretion in response to salt intake.

In this study we tested a new hypothesis namely that serotonin (5-hydroxytryptamine, 5-HT) could be synthesised within the zona glomerulosa of the rat adrenal gland from exogenous 5-hydroxytryptophan (5-HTP) by the enzyme L-aromatic amino acid decarboxylase (L-AAAD). A specific monoclonal antibody against L-AAAD showed that the enzyme was present predominantly in the adrenal medulla but also in the zona glomerulosa and zona fasciculata. Wistar rats, maintained on a normal (NS), low (LS) or high (HS) salt diet for one week, were sacrificed by decapitation, blood samples taken and the adrenal glands removed. Plasma aldosterone concentrations were significantly higher in the LS diet group (2.91 +/- 0.35 nM) and significantly lower in the HS diet group (0.261 +/- 0.55 nM) compared with the NS diet group (1.025 +/- 0.133 nM) (p < 0.001). Capsules from the LS diet group synthesised significantly higher maximal levels of 5-HT (2615.463 +/- 480.88 nM/mg protein) than capsules from the NS (1219.117 +/- 150.259 nM/mg protein) and the HS (968.477 +/- 214.485 nM/mg protein) salt diet groups (p < 0.05). Maximal aldosterone secretion in adrenal capsules obtained from rats on the LS diet (73.428 +/- 4.053 nM/mg protein) was significantly higher than in those obtained from rats on the NS diet (41.658 +/- 1.87 nM/mg protein) (p < 0.05). Maximal aldosterone secretion in adrenal capsules from the HS diet group (30.624 +/- 2.114 nM/mg protein) was significantly lower than in the capsules from both the LS and NS groups (p < 0.05). Carbidopa (10(-4) M), a specific inhibitor of L-AAAD, markedly attenuated the secretion of aldosterone when adrenal capsules from all three salt diet groups were incubated with 10(-4) M 5-HTP (p < 0.05), but had no significant effect on basal aldosterone secretion. These results clearly demonstrate that L-AAAD is not only present in the medulla, but also in the zona glomerulosa and zona fasciculata of the rat adrenal gland. In addition, 5-HT can be synthesised in the zona glomerulosa/capsular region of the rat adrenal gland and both its biosynthesis and its ability to stimulate aldosterone secretion is increased by sodium depletion and attenuated by sodium loading. This raises the interesting possibility that L-AAAD could play a role in the regulation of aldosterone secretion during sodium deficiency in the rat by converting circulating 5-HTP (which is present in blood at concentrations exceeding 1 micromolar) into 5-HT within the adrenal cortex.

5-Hydroxytryptophan↗
PubMed1996

[Amines and pteridines].

Polyamines (putrescine, spermidine and spermine) play important roles in cell proliferation and differentiation, and have been established as tumors markers. We and other workers have confirmed that N1-acetylspermidine in tumor tissues, spermidine and spermine in erythrocytes, and N1,N12-diacetylspermine in urine might be the most sensitive indicators for various forms of tumors. Neopterin is a marker of cell-mediated immunostimulation, and may be a helpful marker in monitoring cancer patients. HPLC and immunological assays of neopterin, biopterin, and N2-(3-aminopropyl)biopterin(oncopterin) in urine might be useful in the clinical study of pteridines, as cancer markers. Serum 5-S-cysteinyldopa level is a useful and specific biochemical marker for malignant melanoma.

Biomarkers, Tumor↗
PubMed1996

Inhibition of hepatocellular carcinoma development and erythrocyte polyamine levels in ODS rats fed on 3'-methyl-4-dimethylaminoazobenzene by hemicalcium ascorbate, 2-O-octadecylascorbic acid, and ascorbyl palmitate.

We examined the modifying effect of hemicalcium ascorbate (Ca-Asc), and its lipophilic derivatives, 2-O-octadecylascorbic acid (CV-3611) and ascorbyl palmitate (AscP), on hepatocarcinogenesis by 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB) in ODS rats (a mutant unable to synthesize ascorbic acid). Male 14-week-old ODS rats were given a modified AIN-A diet or the diet containing 0.06% 3'-Me-DAB, and drinking water containing 0.1% ascorbic acid. Rats were divided into the following eight groups: Group 1, no treatment (basal diet alone); Group 2, Ca-Asc; Group 3, CV-3611; Group 4, AscP;Group 5, 3'-Me-DAB; Group 6, 3'-Me-DAB + Ca-Asc; Group 7, 3'-Me-DAB + CV-3611; and Group 8, 3'-Me-DAB + AscP. Ca-Asc (2 g/kg), CV-3611 (0.2 g/kg), and AscP (0.6 g/kg) was administered once every day by gavage. 3'-Me-DAB was given in the basal diet. After 17 weeks, animals were killed by exsanguination, and the liver was weighed and processed for histological examination. Treatment by CV-3611 exerted a marked inhibitory effect on the development of 3'-Me-DAB-induced hepatocellular carcinomas (HCC) as measured by multiplicity. Although less effective than CV-3611, Ca-Asc and AscP also showed inhibitory effect. We have also studied the correlation of erythrocyte (RBC) polyamine levels and HCC development. RBC polyamine levels were inhibited by Ca-Asc and its derivatives, indicating it may be a marker of hepatocarcinogenesis.

Animals↗
PubMed1996

[Molecular genetics of hereditary progressive dystonia (HPD/Segawa's disease)].

Hereditary progressive dystonia with marked diurnal fluctuation (HPD, Segawa's disease), also known as DOPA-responsive dystonia (DRD), was found to be caused by mutation of GTP cyclohydrolase I (GCH) gene. GCH activity in mononuclear blood cells was decreased to less than 20% of the normal values. The decrease in GCH activity causes the decrease in tetrahydrobiopterin (BH4) levels, resulting in decreased tyrosine hydroxylase (TH) activity and finally in decreased dopamine levels in the nigrostriatal dopamine neurons. In contrast, GCH activity in mononuclear blood cells in juvenile parkinsonism was normal. Recessive dystonia was shown to have a point mutation in TH gene. Thus, HPD (Segawa's disease) is distinct from recessive dystonia and juvenile parkinsonism. Patients with Parkinson's disease had decreased GCH activity in parallel with the decreases in TH activity and dopamine in the striatum, probably as the results of cell death.

Cell Death↗
PubMed1995

Targeted disruption of the tyrosine hydroxylase locus results in severe catecholamine depletion and perinatal lethality in mice.

Tyrosine 3-hydroxylase (TH, EC 1.14.16.2) catalyzes the first and rate-limiting step of the catecholamine biosynthetic pathway in the nervous and endocrine systems. The TH locus was disrupted in mouse embryonic stem cells by homologous recombination. Mice heterozygous for the TH mutation were apparently normal. In these mice, TH activity in the embryos and adult tissues was less than 50% of the wild-type values, but the catecholamine level was decreased only moderately in the developing animals and was maintained normally at adulthood, suggesting the presence of a regulatory mechanism for ensuring the proper catecholamine level during animal development. In contrast, the homozygous mutant mice died at a late stage of embryonic development or shortly after birth. Both TH mRNA and enzyme activity were lacking in the homozygous mutants, which thus explained the severe depletion of catecholamines. These changes, however, did not affect gross morphological development of the cells that normally express high catecholamine levels. Analysis of electrocardiograms of surviving newborn mutants showed bradycardia, suggesting an alteration of cardiac functions in the homozygous mice that may lead to the lethality of this mutation. In addition, transfer of a human TH transgene into the homozygous mice corrected the mutant phenotype, showing recovery of TH activity by expression of the human enzyme. These results indicate that TH is essential for survival of the animals during the late gestational development and after birth.

Animals↗
PubMed1995

Genomic structure and tissue distribution of the mouse dopamine D4 receptor.

The mouse dopamine D4 receptor gene was isolated from a genomic DNA library by plaque hybridization. The D4 receptor gene encoded an open reading frame consisting of 387 amino acids, interrupted by three introns. Distribution of the D4 receptor mRNA in brain regions and peripheral tissues of mice was examined by reverse transcription-polymerase chain reaction (RT-PCR). There was a remarkable expression of the receptor mRNA in various brain regions, showing the highest expression level in the cerebellum. Also, in the peripheral tissues a high level expression of the D4 mRNA was detected in the eye, adrenal gland and testes. We observed several differences in tissue distribution of the D4 mRNA in mice from that reported in other mammalian species.

Amino Acid Sequence↗
PubMed1995

Simultaneous determination of N2-(3-aminopropyl)biopterin (oncopterin), biopterin and neopterin by high-performance liquid chromatography with fluorescence detection.

A high-performance liquid chromatographic method is described for the simultaneous determination of N2-(3-aminopropyl)biopterin (oncopterin, a newly found natural pteridine in urine from cancer patients), biopterin, and neopterin in urine. For the detection and quantification of the compounds, fluorometry was used. Using Develosil ODS K-5 and Develosil ODS HG-5 reversed-phase columns and a Nucleosil 100-SSA strong cation-exchange column, oncopterin, biopterin, and neopterin in urine were completely separated and assayed simultaneously by fluorescence detection. Similar values of oncopterin were obtained using each of the three columns, and the Develosil ODS K-5 reversed-phase column gave the most satisfactory separation. The sensitivity was high enough to measure 1 pmol of each pteridine. The HPLC method was highly reproducible. Our preliminary results indicate that oncopterin could be a most sensitive marker for cancer.

Biomarkers, Tumor↗
PubMed1995

Deletion mutagenesis of human tyrosine hydroxylase type 1 regulatory domain.

A series of N-terminal deletion mutants of human tyrosine hydroxylase type 1 has been expressed in Escherichia coli to characterize the N-terminal regulatory domain. The mutants lacking the first 74 to 117 amino acids led to the precipitation into aggregates probably due to improper folding. All of the deletion mutants are active in the lysate supernatant and/or the pellet. The Michaelis constants of pterins are similar among all the mutants examined and the wild-type.

Amino Acid Sequence↗
PubMed1995

GTP cyclohydrolase I gene in hereditary progressive dystonia with marked diurnal fluctuation.

We previously reported four different mutations in the coding region of GTP cyclohydrolase I (GCH-I) gene in patients with hereditary progressive dystonia with marked diurnal fluctuation (HPD). We found two independent new mutations (leucine 79 proline and a deletion in exon 4) in patients with HPD. We also found four families of HPD without any mutations in the coding region of GCH-I gene.

Base Sequence↗