Biomedical subjects

T Amano

Publications and source records attributed to T Amano.

At least 145 records · Page 8Linked to original sources

PubMed1997

Millimeter-Wave Spectrum of the NO Dimer

The pure rotational spectrum of the NO dimer, (14N16O)2, has been studied in the 225-400 GHz millimeter-wave region by means of direct absorption in a supersonic jet expansion. Previously, only 4 rotational transitions of (NO)2 had been measured in the microwave region. To these, we have added 66 new millimeter-wave transitions with values of J ranging from 4 to 16 and of Ka from 2 to 7. Most transitions were observed as single lines, but a few showed partially resolved hyperfine structure. The analysis of these data, in combination with the previous microwave transitions and an extensive set of infrared (nu1 band) measurements, has resulted in a greatly improved set of parameters for the ground state of the NO dimer, including the first sextic distortion parameters. Copyright 1997 Academic Press. Copyright 1997Academic Press

Journal Article↗

PubMed1997

Existence of voltage-dependent Ca2+ channels in vestibular dark cells: cytochemical and whole-cell patch-clamp studies.

To determine whether functional Ca2+ channels are present in vestibular dark cells, changes in intracellular Ca2+ concentration ([Ca2+]i) due to K+ applications were measured using the Ca(2+)-sensitive dye (fura-2) and patchclamp whole-cell recordings were made in dark cells isolated from the ampullae of the semicircular canal of the guinea pig. Exchange of the external solution with a buffer medium containing a high K+ concentration (80 mM K+ or 150 mM K+) caused a concentration-dependent increase in [Ca2+]i in vestibular dark cells. Application of 1 microM nifedipine as a Ca2+ channel antagonist completely blocked the increase in [Ca2+]i. Further treatment with 10 microM BAY K 8644 as a Ca2+ channel agonist caused an increase in [Ca2+]i. In the patch-clamp whole-cell recordings a 1-s depolarizing pulse given into the dark cell in the presence of a high barium concentration (50 mM Ba2+) induced an inward current. In determining the current-voltage relationship, a current was detected at a potential that depolarized at-50 mV and was maximal at +10 mV. This inward current was completely blocked by 1 mM La3+ as a Ca2+ channel antagonist. These findings suggest the presence of voltage-dependent Ca2+ channels in dark cells, which have a presumed function in the regulation of [Ca2+]i in the vestibular endolymph.

Animals↗

PubMed1997

Bezoar (Capra aegagrus) is a matriarchal candidate for ancestor of domestic goat (Capra hircus): evidence from the mitochondrial DNA diversity.

The leading hypothesis on the ancestor of domestic goats (Capra hircus) is that it is the wild goat called the bezoar or pasang (Capra aegagrus). To verify this hypothesis, we sequenced and compared the cytochrome b gene of mitochondrial DNA from six domestic goats and bezoar. A further sequence for the markhor was taken from the database. In total we detected 51 nucleotide substitutions among the domestic goats, bezoar and markhor. However, only one specific nucleotide substitution was found between the domestic goats and the bezoar. On the other hand, 43 nucleotide substitutions were specific for the markhor. This result suggested a close relationship between the domestic goats and the bezoar. A neighbor-joining and parsimony phylogenetic tree constructed using the sequences showed that the domestic goats and the bezoar belong to the same cluster, while the markhor showed a distinct cluster separate from that of the domestic/bezoar cluster. This result was confirmed by trees based on the sequence of the mitochondrial displacement loop regions. These results suggest that the strongest candidate for a matriarchal ancestor of domestic goats is the bezoar.

Animals↗

PubMed1997

Increased expression of cathepsins E and D in neurons of the aged rat brain and their colocalization with lipofuscin and carboxy-terminal fragments of Alzheimer amyloid precursor protein.

Age-related changes in the expression and localization of two distinct intracellular aspartic proteinases, cathepsin E (CE) and cathepsin D (CD), were investigated in the rat cerebral cortex and the brainstem by immunocytochemical and quantitative methods using discriminative antibodies specific for each enzyme. Nonlysosomal CE was barely detectable in these two brain tissues in the embryonic stages, whereas relatively high expression of lysosomal CD was observed in embryonic tissues. After birth, CE was increasingly expressed in these tissues with aging to attain maximal levels at 30 months of age. Western blot analyses revealed that CE existed predominantly as the mature enzyme at 2 and 17 months of age, whereas it was present as not only the mature enzyme but also the proenzyme at 30 months of age. On the other hand, CD was mainly present in the mature form throughout development, although its level in these tissues was also significantly increased with aging. The CE-positive cortical and brainstem neurons of the aged rat corresponded well with cells emitting autofluorescence for lipopigments. By the double-staining technique, most of the CE-positive cortical and brainstem neurons of the aged rat were also positive for antibody to the carboxyl-terminal fragments of amyloid precursor protein (APP634-695), intracellular accumulation of which is thought to be associated with age-related changes in the endosome/lysosome system. It is important that electron microscopy revealed that CE in brainstem neurons of the aged rat colocalized with CD in the lipofuscin-containing lysosomes. These results indicate that aging results in the increased expression and lysosomal localization of CE in cortical and brainstem neurons and changes in the endosomal/lysosomal proteolytic system, which may be related to lipofuscinogenesis and altered intracellular APP metabolism.

Aging↗

PubMed1997

In vitro combination effect of 5-fluorouracil and cisplatin on the proliferation, morphology and expression of Ki-67 antigen in human gastric cancer cells.

The combination effect of 5-fluorouracil (5-FU) and cisplatin was examined in terms of the proliferation, morphology and expression of Ki-67 antigen, and propidium iodide (PI) staining using four cultured human gastric cancer cell lines, and we assessed how such activity was affected by the exposure time and the timing of treatment. MKN-1, MKN-28, MKN-45 and MKN-74 cells were exposed to various concentrations of 5-FU for 72 h and cisplatin for 8 or 72 h. At IC50, MKN-28 cells were more sensitive to 5-FU than other cell lines, whereas MKN-1 and MKN-45 cells were more sensitive to cisplatin than other cell lines. The cell growth-inhibitory activity of cisplatin was found to be 'area under the curve' dependent. When 5-FU and cisplatin were combined simultaneously, the combination effect was higher than that of 5-FU or cisplatin alone. On the other hand, when cisplatin was applied before 5-FU, there was no potentiation of the cell growth-inhibitory activity by combination treatment. In 5-FU-treated MKN-74 cells, the size, morphology and PI staining of nuclei were almost the same as those of the untreated cells, and the expression of Ki-67 antigen was less than that of the untreated cells. In cisplatin-treated MKN-74 cells, the size of cells and nuclei was larger than that of the untreated cells and fragmentation of nuclei was observed. The expression of Ki-67 antigen was less than the untreated cells but more than that of 5-FU-treated cells. In the cells treated with 5-FU and cisplatin in combination, the above changes were an intermediate of those of 5-FU-treated cells and cisplatin-treated cells. In conclusion, the cell growth-inhibitory activity of 5-FU and cisplatin against gastric cancer cells was potentiated by the combined treatment with 5-FU and cisplatin simultaneously, but not with cisplatin followed by 5-FU.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1997

Trends in clinical outcome of transitional cell carcinoma of the ureter: have the results improved?

We divided 53 consecutive patients with transitional cell carcinoma of the ureter into two groups. Group A consisted of patients treated in the 1970s and group B of patients treated in the 1980s. Clinical features and outcomes were compared between the groups. Group B patients saw an increased use of new diagnostic modalities, including antegrade pyelography, computed tomography, and bone scintigraphy. Regional lymphadenectomy was added to the operative routine in group B and combined chemotherapy, using methotrexate, vinblastine, adriamycin and cisplatinum, the most effective regimen at present, was used in 9 patients in group B and no patients in group A. In spite of new diagnostic modalities and treatments, the survival rate for ureteral cancer failed to improve from the 1970s to the 1980s.

Aged↗

PubMed1997

Antiepileptic effects of 20-hydroxyecdysone on convulsive seizures in spontaneously epileptic rats.

We examined the effect of 20-hydroxyecdysone (20-HE), a neurosteroid found in insects that is involved in their developmental process, on both tonic convulsion and absence-like seizure in spontaneously epileptic rat (SER). When 20-HE was given orally to SER at 25-200 mg/kg, significant decreases of the tonic convulsion were observed with 100 and 200 mg/kg. Pretreatment of the animal with bicuculline (1 mg/kg, i.p.) antagonized the inhibitory effects of 20-HE. However, absence-like seizures were not affected by 20-HE. These findings indicate that 20-HE produces antiepileptic effects on tonic convulsion by acting on the modulatory site of GABA(A) receptors.

Administration, Oral↗

PubMed1997

Effects of perospirone, a novel antipsychotic agent, on the dopaminergic neurons in the rat ventral tegmental area.

An electrophysiological study was performed to investigate the effects of cis-N-[4-[4-(1,2-benz-isozole-3-yl)-1-piperazinyl]butyl]cyclohexan e-1,2-dicarboximide hydrochloride (perospirone), a novel antipsychotic agent with high affinities for D2/5-HT2-receptors, on the dopaminergic (DA) neurons in the ventral tegmental area (VTA) using chloral hydrate-anesthetized rats. DA neurons and non-DA neurons in VTA were identified according to the configurations of their action potentials and firing rates. Spontaneous firing of DA neurons was dose-dependently decreased by i.v. injection of methamphetamine (MAP). Most non-DA neurons were unaffected by MAP up to 2 mg/kg, but the firing was increased with MAP in 2 of 7 neurons. Perospirone injected intravenously reversed the MAP-induced decrease in spontaneous firing of DA neurons in a dose-dependent manner. In addition, i.v. injection of perospirone also inhibited the MAP-induced increase in firing of the 2 non-DA neurons. Similarly, inhibition of spontaneous firing in DA neurons by microiontophoretically applied DA was antagonized during iontophoretic application of perospirone. However, the firing of non-DA neurons, which were insensitive to DA, was not affected by iontophoretically applied perospirone. Since the DA neurons are inhibited by DA via D2-receptors, these findings suggest that perospirone acts on the D2-receptors to antagonize the dopaminergic inhibition of DA neurons in VTA.

Animals↗

PubMed1997

Scatter and attenuation correction in technetium-99m brain SPECT.

UNLABELLED: We propose a practical method for scatter and attenuation compensation in 99mTc-ECD brain SPECT using a simultaneous emission CT (ECT) and transmission CT (TCT) acquisition system that includes the following major components: (a) triple-headed SPECT gamma camera equipped with fanbeam collimators; (b) external line sources containing 99mTc placed at the focal lines of the collimators; and (c) scatter correction by the triple-energy-window (TEW) method. METHODS: Projection images were obtained over a 360 degrees rotation scan. After acquisition, scatter correction was performed using the TEW method, which corrected scattered photons pixel by pixel in the projection data. Scatter-corrected ECT images were compensated for attenuation using the TCT images with Chang's iterative method, and were converted to activity concentration (kBq/ml) images by obtaining a cross-calibration scan. After validating this method with phantom studies, it was applied to clinical brain imaging using a combination of 925 MBq 99mTc-ECD as a radiopharmaceutical and 222 MBq 99mTc as an external source. ECT and TCT data were acquired separately or simultaneously. RESULTS: SPECT quantification and image quality were improved by performing this correction. The activity concentration images obtained with the simultaneous acquisition were almost identical to those obtained with the separate acquisition. CONCLUSION: This method was clinically practical and cost-effective for reconstructing quantitative 99mTc brain SPECT images.

Brain↗

PubMed1997

[Clinical features of 5 cases of tuberculous meningitis--with special reference to brain CT and MRI findings].

We evaluated the clinical features of 5 cases of tuberculous meningitis who had been admitted to our department from 1987 to 1994. Three patients were male and two were female. Their age ranged from 17 to 74 years old. All cases were examined by both CT and MRI before and during antituberculous treatment. Before the treatment, CT scan revealed abnormal findings such as nodular lesion suggesting tuberculoma, subarachnoid contrast enhancement or cerebral infarction in 2 cases, while MRI revealed abnormal findings such as inflammatory lesions with Gd-enhancement in 4 out of 5 patients. During the treatment, all abnormal findings except cerebral infarction disappeared. No abnormal findings were detected by CT. MRI and SPECT in one case who showed right hemiparesis and motor aphasia. In summary, CT scan could demonstrate abnormal findings in only a small portion of patients with tuberculous meningitis. One the other hand, MRI revealed various abnormal findings in most patients, and could reveal some lesions which could be responsible for the symptoms of patients. In a few patients, however, MRI could not show any lesion in spite of obvious focal neurological signs. MRI is considered to be useful for detecting the lesions in most patients with tuberculous meningitis, although its findings are not always specific for the disease.

Adolescent↗

PubMed1997

D2 receptor activation in distinct striatal neurons in comparison with D3 receptors.

The role of D2/D3 receptors in striatum was electrophysiologically examined in vitro in chloralose-anesthetized rats. In addition, in vitro patch clamp method with rat brain slices was followed. Stimulations of the substantia nigra pars compacta (SN) in vivo elicited spike generation which was inhibited by microiontophoretically applied domperidone, a D2 antagonist. These domperidone-sensitive neurons were activated by microiontophoretic application of D2 agonists such as talipexole, quinpirole and bromocriptine as well as the D2 agonist, 7-OH-DPAT. They were also excited by either intravenous injection of bromocriptine or talipexole in a dose-dependent manner. Furthermore, the SN-induced increases in neuronal firing were blocked during microiontophoretic application of domperidone. In patch clamp whole-cell recording large-sized cells, identified visually under Ramanosky microscope, were depolarized with repetitive firing on bath application of talipexole and 7-OH-DPAT at a current clamp mode. Talipexole-induced depolarization in the large-sized cell was similarly observed in the presence of TTX and high Mg2+ in Ca(2+)-free physiological solution. In contrast, the medium-sized cells were hyperpolarized on bath application of talipexole without being affected by 7-OH-DPAT. These findings suggest that the large-sized cells, which were presumably cholinergic interneurons, are activated by dopamine derived from the SN via D2 and/or D3 receptors, while the medium-sized cells are inhibited by dopamine via D2 receptors.

Animals↗

PubMed1997

[A case of postbulbar duodenal ulcer due to adjuvant chemotherapy after gastrectomy for gastric cancer].

We encountered a rare case of postbulbar ulcer caused by adjuvant chemotherapy after gastrectomy. A 64 year-old woman, who received chemotherapy with CDDP-5-FU after gastrectomy, developed severe hematemesis. Endoscopic examination revealed a gigantic ulcer at the anal site of Vater's papilla. The ulcer was healed with PPI and soft diet.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1997

[A patient with psoriatic arthritis due to generalized pustular psoriasis (von Zumbusch type)].

Pustular psoriasis is a rare skin disease that is observed in about 1% of all patients with psoriasis. We encounted a patient with psoriatic arthritis (PsA) due to pustular psoriasis. The patient was a 31-year old male. He visited our hospital due to generalized eruption and pain in multiple joints. Treatment was initiated under a diagnosis of psoriasis vulgaris and associated PsA. However, eruption extended to the entire body and became pustular, and fever developed. Since PsA symptoms were simultaneously aggravated, and body movements become difficult, he was admitted. A diagnosis of generalized pustular psoriasis (von Zumbusch) and associated symmetrical polyarthritis was made. Local therapy was performed. As systemic treatment, oral administration of an corticosteroid and weekly low-dose pulse methotrexate therapy were performed. The skin symptoms and PsA symptoms rapidly improved. At present, about one year after the initiation of treatment, the eruption almost completely disappeared, and joint pain does not present any problem in daily life.

Adult↗

PubMed1996

Unusual pKa of the carboxylate at the putative catalytic position of the thermophilic F1-ATPase beta subunit determined by 13C-NMR.

Glutamic acid-190 in the beta subunit of F1-ATPase from thermophilic Bacillus PS-3 (TF1) was reported to be essential for the ATPase activity. The mutant TF1beta subunit in which Glu-190 had been substituted by cysteine was carboxymethylated with 13C-labeled monoiodoacetic acid. The pKa value of the carboxymethylene group at the 190 position was determined as 5.6 +/- 0.4 by 13C-NMR. On the basis of this value, the pKa of the carboxylate of Glu-190 of the TF1beta subunit was estimated to be 6.8 +/- 0.5. The unusually high pKa could play a role in the catalytic mechanism of F1-ATPase.

Adenosine Diphosphate↗

PubMed1996

Detection of a new interstellar molecular ion, H2COH+ (protonated formaldehyde).

A new interstellar molecular ion, H2COH+ (protonated formaldehyde), has been detected toward Sgr B2, Orion KL, W51, and possibly in NGC 7538 and DR21(OH). Six transitions were detected in Sgr B2(M). The 1(1,0)-1(0,1) transition was detected in all sources listed above. Searches were also made toward the cold, dark clouds TMC-1 and L134N, Orion (3N, 1E), and a red giant, IRC + 10216, without success. The excitation temperatures of H2COH+ are calculated to be 60-110 K, and the column densities are on the order of 10(12)-10(14) cm-2 in Sgr B2, Orion KL, and W51. The fractional abundance of H2COH+ is on the order of 10(-11) to 10-(9), and the ratio of H2COH+ to H2CO is in the range 0.001-0.5 in these objects. The values in Orion KL seem to be consistent with the "early time" values of recent model calculations by Lee, Bettens, & Herbst, but they appear to be higher than the model values in Sgr B2 and W51 even if we take the large uncertainties of column densities of H2CO into account. We suggest production routes starting from CH3OH may play an important role in the formation of H2COH+.

Astronomical Phenomena↗

PubMed1996

Hypersensitivity of nucleus accumbens neurons to methamphetamine and dopamine following repeated administrations of methamphetamine.

Methamphetamine (MAP) abuse is known to induce reverse tolerance in humans. Electrophysiological studies were performed to elucidate time-related changes in dopamine (DA) receptor sensitivities to DA and MAP after withdrawal following repeated MAP administrations. MAP (5 mg/kg) or physiological saline (1 ml/kg) was injected i.p. to rats once daily for 5 days. Single neuronal activities of nucleus accumbens (Acc) of 5-day MAP-administrated rats were extracellularly recorded with a glass microelectrode attached along a seven-barreled micropipette under chloral hydrate anesthesia. Each barrel was respectively filled with DA, MAP, haloperidol, glutamate and NaCl. Drugs were microiontophoretically applied to the immediate vicinity of Acc neurons receiving inputs from the parafascicular nucleus (Pf) of thalamus. Spikes elicited by Pf stimulation- and glutamate-induced firing were inhibited by iontophoretic application of either DA or MAP at doses of 20-40 nA in the saline-treated rats: EC50 for DA and MAP were 23.8 and 23.2 nA, respectively. At 24-30 hr after the final MAP administration, however, the inhibitory effects of both DA and MAP on Pf stimulation- and glutamate-induced firing of Acc neurons were less pronounced than those in the saline-treated animals. Furthermore, spontaneous firing was enhanced during haloperidol application. On day 5 postadministration, the inhibition of Acc neurons by DA or MAP was significantly more marked than that of saline-treated animals. On day 10 postadministration, the inhibition of Acc neurons by DA or MAP was comparable to that in controls. These results indicate that repeated administrations with MAP induce hyposensitivity and hypersensitivity of Acc neurons to DA and MAP at 24-30 hr and on day 5 postadministration, respectively.

Action Potentials↗

PubMed1996

Inhibition by a putative antipsychotic quinolinone derivative (OPC-14597) of dopaminergic neurons in the ventral tegmental area.

The effects of the newly synthesized quinolinone derivative, OPC-14597 (7-{4-[4-(2,3-dichlorophenyl)-1-piperazinyl]butyloxy}-3, 4-dihydro-2(1 H)-quinolinone), on dopaminergic neuronal activity in the ventral tegmental area were examined using both in vivo microiontophoretic methods in chloral hydrate-anesthetized rats and the tight-seal whole-cell patch-clamp technique in thin-slice preparations of the rat brain. Neurons in the ventral tegmental area were classified as type I or type II according to their responses to antidromic stimulation of the nucleus accumbens, probably corresponding to dopaminergic and non-dopaminergic neurons, respectively. Antidromic spikes elicited by nucleus accumbens stimulation were inhibited by microiontophoretic application of dopamine and OPC-14597 in type I, but not in type II neurons. Although the OPC-14597-induced inhibition was antagonized by simultaneous application of domperidone (5-chloro-1-[1-[3-(2,3-dihydro-2-oxo-1 H-benzimidazo-1-yl)-propy]-4-piperidinyl]-1,3-dihydro-2H- benzimidazol-2-one; dopamine D2 receptor antagonist), SCH 23390 (R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4, 5-tetrahydro-1 H-3-benzazepine hydrochloride; dopamine D1 receptor antagonist) had no such effect. Spontaneous firing of type I neurons was also inhibited by iontophoretically applied OPC-14597 and dopamine, whereas that of type II neurons was unaffected. The inhibitory effect of OPC-14597 on the spontaneous firing of type I neurons was antagonized by domperidone, but not by SCH 23390. In a whole-cell patch-clamp study using a thin-slice preparation of the rat brain, bath application of OPC-14597 induced hyperpolarization accompanied by inhibition of spontaneously occurring action potentials in the large neurons (> 20 microns in diameter) in a concentration-dependent manner. These results suggest that OPC-14597 acts on dopaminergic neurons in the ventral tegmental area as a dopamine D2 receptor agonist to inhibit neuronal activities, probably by increasing membrane potassium conductance.

Animals↗

PubMed1996

Catalytic activities of alpha3beta3gamma complexes of F1-ATPase with 1, 2, or 3 incompetent catalytic sites.

In order to know how many functional catalytic sites are necessary for ATPase activity of F1-ATPase from a thermophilic Bacillus PS3, a new method of isolating homogeneous preparations of the alpha3beta3gamma complex with 1, 2, or 3 incompetent catalytic sites was developed. Ten glutamic acids (Glu.Tag) were linked to the C terminus of the catalytically incompetent beta(E190Q) subunit. The Glu.Tag itself did not affect ATPase activity of the complexes. Two kinds of alpha3beta3gamma complexes, one containing beta(wild-type) and the other Glu.Tag-linked beta(E190Q), were mixed, urea-denatured, and dialyzed, and alpha3beta3gamma complexes were reconstituted. Each of the complexes containing a different number of Glu.Tag-linked beta(E190Q) was separated by anion-exchange chromatography and analyzed. The results were as follows. 1) Normal steady-state ATPase activity requires three intact catalytic sites. 2) Chase-acceleration, a catalytic cooperativity, requires at least two intact catalytic sites. 3) Single-site catalysis can be mediated by a single intact catalytic site alone. Rescrambling of subunits between complexes could occur when the complex was aged under certain conditions, and this might be one of the reasons for previous contradictory results (Miwa, K., Ohtsubo, M., Denda, K., Hisabori, T., Date, T., and Yoshida, M.(1989) J. Biochem. (Tokyo) 106, 730-734).

Adenosine Diphosphate↗