Biomedical subjects

T Nagatsu

Publications and source records attributed to T Nagatsu.

At least 163 records · Page 9Linked to original sources

PubMed1994

Interleukin-1 beta, interleukin-6, epidermal growth factor and transforming growth factor-alpha are elevated in the brain from parkinsonian patients.

Interleukin (IL)-1 beta, IL-6, epidermal growth factor (EGF), and transforming growth factor-alpha (TGF-alpha) were measured for the first time in the brain (caudate nucleus, putamen and cerebral cortex) from control and parkinsonian patients by highly sensitive sandwich enzyme immunoassays. The concentrations of IL-1 beta, IL-6, EGF, and TGF-alpha in the dopaminergic, striatal regions were significantly higher in parkinsonian patients than those in controls, whereas those in the cerebral cortex did not show significant differences between parkinsonian and control subjects. Since these cytokines and growth factors may play important roles as neurotrophic factors in the brain, the present results suggest that they may be produced as compensatory responses in the nigrostriatal dopaminergic regions in Parkinson's disease, and may be related, at least in part, to the process of neurodegeneration in Parkinson's disease.

Aged↗

PubMed1994

Phenotypic changes of AADC-only immunopositive premammillary neurons in the brain of laboratory shrew Suncus murinus by systemic administration of monoamine precursors.

After 5-hydroxy-L-tryptophan (5-HTP) and L-3,4-dihydroxyphenylalanine (L-DOPA) were injected i.p. in the laboratory shrew Suncus murinus, immunocytochemical and immunofluorescence studies were conducted on continuous or same sections of the brain, using specific anti-tyrosine hydroxylase (TH), anti-aromatic L-amino acid decarboxylase (AADC), anti-dopamine (DA) and anti-serotonin (5-HT) antisera which were produced in our laboratory. The results of double-staining by the immunofluorescence method as well as immunoelectron microscopy strongly indicate that the cells of the premammillary nucleus of the laboratory shrew brain (AADC-only-positive neurons) are capable of synthesizing DA and 5-HT simultaneously upon simultaneous administration of L-dopa and 5-HTP.

Animals↗

PubMed1994

High-performance liquid chromatographic measurement of cerebrospinal fluid tetrahydrobiopterin, neopterin, homovanillic acid and 5-hydroxindoleacetic acid in neurological diseases.

Cerebrospinal fluid (CSF) samples from patients with a variety of neurological disorders were assayed to determine the concentrations of tetrahydrobiopterin (BH4), the active cofactor of hydroxylases. Dihydroneopterin (NH2) and neopterin (N), which are linked with BH4 synthesis and are inflammatory biochemical markers, were also measured simultaneously in a number of patients. 5-Hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA), the main products of serotonin and dopamine breakdown, were analyzed in parallel whenever possible. As BH4 and NH2 are difficult to analyze owing to their instability, CSF samples were collected under special conditions to preserve the reduced BH4 and NH2. Liquid chromatographic assays and detection of the various substances measured also required particular precautions. BH4 concentrations were elevated in patients with neurological disorders such as syphilis and lupus-like disease and especially in an AIDS patient with neurological complications with an increased N/BH4 ratio.

Acquired Immunodeficiency Syndrome↗

PubMed1994

Endogenous synthesis of N-methylnorsalsolinol in rat brain during in vivo microdialysis with epinine.

The in vivo metabolic pathway for the synthesis of N-methylnorsalsolinol, an analogue of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), was studied in the rat brain. N-Methyldopamine (epinine) was perfused at the striatum of the rat brain by in vivo microdialysis. N-Methylnorsalsolinol (NMNSAL) was identified in the brain dialysate after epinine perfusion using gas chromatography-selected-ion monitoring mass spectrometry (GC-SIM-MS). We demonstrated that NMNSAL could be synthesized from epinine with an aldehyde by the Piclet-Spengler condensation reaction in the rat brain.

Aldehydes↗

PubMed1994

Protein products of the bacterial reporter gene are found within axon terminals in the brain of transgenic mice.

The aim of this study is to examine whether protein products of the bacterial reporter gene are localized within axon terminals in transgenic mice. We have previously created transgenic mice carrying a chimeric gene composed of the human tyrosine hydroxylase gene promoter and the bacterial gene encoding chloramphenicol acetyltransferase (CAT). In the present study, we used an antiserum that detects specifically CAT, and examined immunocytochemically the brain of the transgenic mice. At a light microscopic level, CAT immunoreactivity was found in a dense plexus of fibers in the central nucleus of the amygdala, and in cell bodies of the ventral tegmental area. At an electron microscopic level, in the central nucleus of the amygdala, CAT immunoreactivity was observed in axon terminals. In the ventral tegmental area, the immunoreactivity was found in the perikaryal cytoplasm and on the microtubule of dendrites. The present findings suggest that protein products of the bacterial gene may be transported in axons up to their terminals, and also moved along the microtubules of dendrites.

Amygdala↗

PubMed1994

Nicotine-induced regulation of tyrosine hydroxylase activity in adrenal gland of transgenic mouse carrying human tyrosine hydroxylase gene.

We investigated the effect of subcutaneous injection of nicotine on in vitro tyrosine hydroxylase (TH) activity in adrenal gland and brain of the transgenic mice carrying an 11-kb fragment containing the entire human TH gene. Injection of 5 mg nicotine/kg (as free base) for 3 days caused a statistically significant increase in vitro TH activity in the adrenal gland, whereas brain TH activity was not affected at all. The adrenal gland of non-transgenic C57BL/6J mice treated in the same way as for transgenic mice tended to enhance TH activity, although not to a significant level. This observation might indicate the possibility that the machinery used by nicotine in regulating the properties or expression of TH in the adrenal gland should be similar between transgenic and non-transgenic mice.

Adrenal Glands↗

PubMed1994

Tumor necrosis factor-alpha (TNF-alpha) increases both in the brain and in the cerebrospinal fluid from parkinsonian patients.

Tumor necrosis factor-alpha (TNF-alpha), a glial-cell-related factor, was measured for the first time in the brain (striatum) and cerebrospinal fluid (CSF) from control and parkinsonian patients by a sensitive sandwich enzyme immunoassay. The concentrations of TNF-alpha in the brain and CSF were significantly higher in parkinsonian patients than those in controls. Since TNF-alpha is an important signal transducer of the immune system with cytotoxic and stimulator properties, these results suggest that an immune response may occur in the nigrostriatal dopaminergic regions in Parkinson's disease and that TNF-alpha may be related, at least in part, to the neuronal degeneration.

Adult↗

PubMed1994

Novel toxins and Parkinson's disease: N-methylation and oxidation as metabolic bioactivation of neurotoxin.

In human brains, a series of monoamine-derived 1,2,3,4-tetrahydroisoquinolines and the 6,7-dihydroxy derivatives has been identified. A tetrahydroisoquinoline was found to cause parkinsonism in monkey, but its toxicity was not so potent as 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. Two metabolic steps were found to increase cytotoxicity of isoquinolines. N-Methylation by a non-specific N-methyltransferase was proved by in vivo and in vitro experiments. The N-methylated compound was oxidized into N-methylisoquinolinium ion by monoamine oxidase from human brain mitochondria. The oxidation was proved by microdialysis in the rat brain. The isoquinolinium ion was more cytotoxic than the two metabolic precursors. N-Methylation of dopamine-derived 1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinolines was detected by in vivo microdialysis in the rat striatum, and their presence in the human brain was confirmed by GC-MS. The metabolic bioactivation may be a general pathway to produce neurotoxins as the pathogenic agents of Parkinson's disease.

Adenosine Triphosphate↗

PubMed1994

Food-derived heterocyclic amines, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole and related amines, as inhibitors of monoamine metabolism.

The effects of heterocyclic amines, pyrolysis products of tryptophan, on monoamine metabolism were examined. Among these amines, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) and 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2) are potent inhibitors of the enzymes related to amine metabolism. They inhibited type A monoamine oxidase more markedly than type B. After culture of a dopamine cell model, clonal pheochromocytoma PC12h cells, with Trp-P-1 activity of tyrosine hydroxylase was decreased by reduction of its affinity to the biopterin cofactor. Trp-P-1 and Trp-P-2 inhibited tryptophan hydroxylase competitively with the substrate and non-competitively with biopterin. These results suggest that food-derived heterocyclic amines may perturb the monoamine levels in the brain through the inhibition of the biosynthesis and metabolism of biogenic amines.

Amines↗

PubMed1994

Expression of human tyrosine hydroxylase-chloramphenicol acetyltransferase (CAT) fusion gene in the brains of transgenic mice as examined by CAT immunocytochemistry.

We have produced transgenic (Tg) mice carrying 5.0-kb fragment from the 5'-flanking region of the human tyrosine hydroxylase (hTH) gene fused to a reporter gene, chloramphenicol acetyltransferase (CAT) [Sasaoka et al. (1992) Mol Brain Res 16: 274-286]. In the brain of the Tg mice, CAT expression has been observed in catecholaminergic (CAnergic) neurons and also in non-CAnergic neurons. The aim of the present study is to examine in detail the cell-type specific expression of the hTH-CAT fusion gene in the brain of the Tg mice, by use of immunohistochemistry for CAT, TH, and aromatic L-amino acid decarboxylase (AADC). CAT-immunoreactive cells were found in CAnergic brain regions which contained TH-positive cells, and also in non-CAnergic brain regions which contained no TH-labeled cells. The non-CAnergic brain regions that represented CAT-stained cells were further divided into two groups: (i) regions containing AADC-labeled cells, for example, bed nucleus of the stria terminalis, nucleus suprachiasmaticus, mammillary body, nucleus raphe dorsalis, inferior colliculus, and nucleus parabrachialis, and (ii) regions containing no AADC-positive cells, for example, main olfactory bulb (except A16), accessory olfactory bulb, nucleus olfactorius anterior, caudoputamen, septum, nucleus accumbens, hippocampus, medial nucleus of the amygdala, entorhinal cortex, nucleus supraopticus, and parasubiculum. The results indicate that the 5.0-kb DNA fragment flanking the 5' end of the hTH gene may contain the element(s) specific for neuron-specific TH expression but which may be insufficient to attenuate ectopic expression.

Animals↗

PubMed1994

Effects of subacute administration of methamphetamine and nicotine on locomotor activity in transgenic mice expressing the human tyrosine hydroxylase gene.

We produced transgenic (Tg) mice carrying the human tyrosine hydroxylase (TH) gene. To investigate differences in the dopaminergic (DAergic) neuronal activity between the Tg and nTg mice, we examined changes in the locomotor activity induced by methamphetamine (MAP) and nicotine (NIC), which enhances DA release and induces TH enzyme activation, respectively. Surprisingly, however, the intensity of MAP (2.5 mg/kg, once a day for 14 days)-induced hyperlocomotion in the nTg mice was greater than that in the Tg mice, and, furthermore, the Tg mice were less sensitive to subacute administration of NIC (0.5 mg/kg, once a day for 14 days) than the nTg mice. These results suggest that DAergic neuronal function is suppressed in Tg mice to compensate for the overexpression of TH.

Animals↗

PubMed1994

Quantification of mRNA of tyrosine hydroxylase and aromatic L-amino acid decarboxylase in the substantia nigra in Parkinson's disease and schizophrenia.

Using the reverse transcription-polymerase chain reaction (RT-PCR), we developed a sensitive and quantitative method to detect all four types of human tyrosine hydroxylase (TH) mRNAs in the human brain (substantia nigra). All four types of TH mRNAs were found in the substantia nigra in the control brains examined, and the ratio of type-1, type-2, type-3, and type-4 mRNAs to the total amount of TH was 45, 52, 1.4, and 2.1%, respectively. The average amount of total TH mRNA in the normal brain (substantia nigra) was 5.5 amol of TH mRNA per microgram of total RNA. The ratios of four TH isoforms were not altered significantly in Parkinson's disease or schizophrenia. Further we measured the relative amount of aromatic L-amino acid decarboxylase (AADC) and beta-actin mRNAs in the brain samples. TH and AADC mRNAs were highly correlated in the control cases. We found that parkinsonian brains had very low levels of all four TH isoforms and AADC mRNAs in the substantia nigra compared with control brains, while no significant differences were found between schizophrenic brains and normal ones. Since the decrease in AADC mRNA was comparable to that in TH mRNA, the alteration of TH in Parkinson's disease would not be a primary event, but it would reflect the degeneration of dopaminergic neurons in the substantia nigra. This is the first reported measurement of mRNA contents of TH isoforms and AADC in Parkinson's disease and schizophrenia.

Actins↗

PubMed1994

Tyrosine hydroxylase indicates cell differentiation of catecholamine biosynthesis in neuroendocrine tumors.

The intracellular localization of tyrosine hydroxylase (TH), which is the rate limiting enzyme in catecholamine (CA) biosynthesis, and its activity in various adrenal and other neuroendocrine tumors was studied. TH was strongly localized in adrenal medulla, pheochromocytoma, and paraganglioma, but was scatteredly expressed in neuroblastoma. TH was not detected in adrenocortical tumors, ganglioneuroma, and other neuroendocrine tumors. Neuron specific enolase (NSE) was found in all neuroendocrine tumors, but Grimelius staining showed only the secreting granules of the tumor cells. TH activity was significantly high in pheochromocytoma and paraganglioma as compared with that in normal adrenal gland, whereas TH activity was low in a neuroblastoma and was undetectable in other tumors. These findings indicate that TH correlates well with the biosynthetic function of CA in the tumor cell and, thus, both the immunostaining of TH and the measurement of its activity in adreno-medullary and related tumors may provide some information about the process of cell differentiation in these tumors.

Adrenal Gland Neoplasms↗

PubMed1994

Recombinant human tyrosine hydroxylase types 1-4 show regulatory kinetic properties for the natural (6R)-tetrahydrobiopterin cofactor.

Human tyrosine hydroxylase (hTH) exists in four isoforms. The four recombinant hTH isoenzymes types 1-4 (hTH1-4) produced in and purified from Escherichia coli showed regulatory kinetic properties for the natural (6R)-L-erythro-tetrahydrobiopterin (RBPH4) as a cofactor. In contrast, the unnatural cofactor (6S)-L-erythro-tetrahydrobiopterin (SBPH4) and a synthetic cofactor (6RS)-methyl-tetrahydropterin (6MPH4) showed usual kinetic characteristics with each of hTH1-4. Substrate inhibition by tyrosine was observed for each of hTH1-4 with natural RBPH4. Two different Km values for pterin cofactor were observed at a high concentration (200 microM) of L-tyrosine only with natural RBPH4, in contrast to a single Km value for unnatural SBPH4 or synthetic 6MPH4. The present results suggest that in the presence of relatively high concentrations (approximately 100 microM) of tyrosine in vivo, RBPH4 cofactor may have a regulatory role for the activity of all four human isoenzymes in vivo. We also found that recombinant hTH1 and 3 were more unstable than hTH2 and 4, suggesting that the 4-amino-acid insertion in hTH2 and 4 may be responsible for the relative stability of hTH2 and 4 isoenzymes.

Base Sequence↗

PubMed1994

Establishment of a human small cell lung cancer cell line producing a large amount of anti-diuretic hormone.

A new cancer cell line (Lu-165) producing a large amount of anti-diuretic hormone (ADH, 2.8 micrograms/g protein) was established from a 50-year-old small cell lung cancer patient presenting with a syndrome of inappropriate anti-diuretic hormone secretion. These cells grew well in serum-supplemented medium and during more than 100 passages they continued producing a large amount of this hormone. This cell line will be a useful tool for studies of the biochemistry and pathology of ADH-producing cancer.

Animals↗

PubMed1994

The effect of exercise on plasma biopterin levels.

The plasma total biopterin and tetrahydrobiopterin levels of 29 normal volunteers were measured before and after exercise by ergometer, and those of 10 were also measured until 24 h after exercise. An increase of plasma total biopterin and tetrahydrobiopterin was observed only after strong exercise, which exhausted the subjects, the ratio of tetrahydrobiopterin to total biopterin not differing before and after exercise. The increase of plasma biopterins disappeared 2 h after exercise. The mechanism of the increase of plasma biopterins was thought to be different from that of patients with affective disorders.

Adult↗

PubMed1994

Changes in plasma tetrahydrobiopterin levels of depressives in depressive and remission phases: reconfirmed by measurement with an internal standard.

Plasma total biopterin and tetrahydrobiopterin levels of 10 normal controls and 10 patients with monopolar depression were measured with and without internal standard. The levels did not differ between the two methods. A significant increase of total biopterin levels and the lower ratio of tetrahydrobiopterin to total biopterin in the depressive phase were observed in the plasma of patients with depression compared to normal controls, and these changes in plasma biopterin tended to normalize in the remission phase.

Adult↗

PubMed1993

Distribution of beta 1- and beta 2-adrenoceptor subtypes in various mouse tissues.

The distribution of beta 1- and beta 2-adrenoceptor subtypes in mice was determined in crude membranes prepared from the submandibular gland, lung, spleen, heart and kidney, all of which are major target tissues of sympathoadrenal neurons. Scatchard analysis using [125I]-(-)iodocyanopindolol gave linear plots and the order of the density of total beta-adrenoceptors was lung > submandibular gland > spleen > kidney > heart. Competition binding studies using beta 1-selective antagonist CGP20712A indicated that all tissues examined possessed both high and low affinity sites which approximately stand for beta 1- and beta 2-adrenoceptor subtypes respectively despite the notable difference in the ratios of high and low affinity sites depending on the tissues. The order of the occupancy of high affinity sites was submandibular gland (71%), heart (55%), spleen (18%), kidney (17%), lung (14%). These results will be helpful to elucidate the regulatory mechanism which underlies beta-adrenergic functions in mice.

Adrenergic beta-Antagonists↗