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M Kamata

Publications and source records attributed to M Kamata.

At least 37 records · Page 2Linked to original sources
PubMed2000

Effect of single intracerebroventricular injection of alpha-interferon on monoamine concentrations in the rat brain.

The effect of a single intracerebroventricular (i.c.v.) injection of alpha-IFN on levels of central monoamines and their metabolites in six brain regions (frontal cortex, striatum, hypothalamus, hippocampus, mid brain and medulla) of the rat was investigated. Wistar rats (n=10) were decapitated 2 h after i.c.v. injection of alpha-IFN. The brain tissues were homogenized, and monoamine concentrations were measured by high-performance liquid chromatography with an electrochemical detector. The levels of 5-hydroxytryptamine (5-HT) were significantly reduced in the frontal cortex in a dose-dependent manner, and the levels of both 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) were reduced in the mid brain and the striatum. The levels of noradrenaline (NA) were also significantly reduced in a dose-dependent manner in the frontal cortex. Some neurophysiological changes that affect activity of the noradrenergic or/and the serotonergic neuron system may occur during IFN therapy.

3,4-Dihydroxyphenylacetic Acid↗
PubMed2000

A carboxy-terminally truncated form of the human immunodeficiency virus type 1 Vpr protein induces apoptosis via G(1) cell cycle arrest.

Viral protein R (Vpr) of human immunodeficiency virus type 1 inhibits cell proliferation by arresting the cell cycle at the G(2) phase and inducing to apoptosis after G(2) arrest. We have reported previously that C81, a carboxy-terminally truncated form of Vpr, interferes with cell proliferation via a novel pathway that is distinct from G(2) arrest. However, the mechanism of this effect of C81 is unknown. We demonstrate here that C81 can induce apoptosis via G(1) arrest of the cell cycle. Immunostaining for various markers of stages of the cell cycle and flow cytometry analysis of DNA content showed that most HeLa cells that had been transiently transfected with a C81 expression vector were arrested at the G(1) phase and not at the G(2) or S phase of the cell cycle. Staining for annexin V, which binds phosphatidylserine on the plasma membrane, as an early indicator of apoptosis and measurement of the activity of caspase-3, a signaling molecule in apoptotic pathways, indicated that C81 is a strong inducer of apoptosis. Expression of C81 induced the condensation, fragmentation, and clumping of chromatin that are typical of apoptosis. Furthermore, the kinetics of the C81-induced G(1) arrest were closely correlated with changes in the number of annexin V-positive cells and the activity of caspase-3. Replacement of Ile or Leu residues by Pro at positions 60, 67, 74, and 81 within the leucine zipper-like domain of C81 revealed that Ile60, Leu67, and Ile74 play important roles both in the C81-induced G(1) arrest and in apoptosis. Thus, it appears that C81 induces apoptosis through pathways that are identical to those utilized for G(1) arrest of the cell cycle. It has been reported that Ile60, Leu67, and Ile74 also play an important role in the C81-induced suppression of growth. These results suggest that the suppression of growth induced by C81 result in apoptosis that is independent of G(2) arrest of the cell cycle.

Apoptosis↗
PubMed2000

Two putative alpha-helical domains of human immunodeficiency virus type 1 Vpr mediate nuclear localization by at least two mechanisms.

To identify the domains of Vpr that are involved nuclear localization, we transfected HeLa cells with a panel of expression vectors that encode mutant Vpr protein with deletions or substitutions within putative domains. Immunofluorescence staining of transfected cells revealed that wild-type Vpr was localized predominantly in the nucleus and the nuclear envelope and certainly in the cytoplasm. Introduction of substitutions or deletions within alphaH1 or alphaH2 resulted, by contrast, in diffuse expression over the entire cell. In addition, double mutations within both of these alpha-helical domains led to the complete absence of Vpr from nuclei. Next, we prepared HeLa cells that express chimeric proteins which consist of the alphaH1 and alphaH2 domains fused individually with green fluorescent protein (GFP) and a Flag tag and extracted them with digitonin and Triton X-100 prior to fixation. Flag-alphaH1-GFP was detected in the nucleus but not in the cytoplasm, while Flag-alphaH2-GFP was retained predominantly in the nucleus and in a small amount in the cytoplasm. The immunostaining patterns were almost eliminated by substitutions in each chimeric protein. Thus, it appeared that the two alpha-helical domains might be involved in nuclear import by binding to certain cellular factors. Taken together, our data suggest that the two putative alpha-helical domains mediate the nuclear localization of Vpr by at least two mechanisms.

Amino Acid Sequence↗
PubMed2000

[Alternating chemoradiotherapy for oropharyngeal cancer].

To evaluate the usefulness of chemoradiotherapy for oropharyngeal cancer, we retrospectively analyzed disease-free survival (DFS) and acute toxicities of the patients treated with this therapy. Between 1990 and 1998, 15 patients were treated with alternating chemoradiotherapy (CRT). Chemotherapy (CT) mainly consisted of 5-fluorouracil 700 mg/m2 (i.v.) on days 1-5 and nedaplatin 100-140 mg/m2 (i.v.) on day 6. Chemotherapy was administered before the beginning of radiotherapy. One cycle of this treatment consisted of CT and a subsequent 27 to 36 Gy of radiotherapy, as a general rule, two cycles were performed. Radiotherapy was delivered in single daily fractions of 1.8 to 2 Gy, to a total dose of 54 to 75 Gy for local lesions and 45 to 86.3 Gy for nodal metastases in the neck. As a historical control, 52 patients treated with curative radiotherapy between 1971 and 1990 were analyzed and compared with the CRT group in terms of DFS. The complete response rate with CRT was 100%. The three-year DFS were 87% and 38% with CRT and RT, respectively. There was a significant difference between the two groups (p = 0.0081). The most frequent and severe acute toxicity was mucositis, with grade 3-4 occurring in 47%. Acute hematologic toxicities were mild. Therefore, this CRT is considered to be an effective and tolerable treatment, and is expected to improve survival for oropharyngeal cancer patients.

Adult↗
PubMed1999

A carboxy-terminally truncated form of the Vpr protein of human immunodeficiency virus type 1 retards cell proliferation independently of G(2) arrest of the cell cycle.

Vpr, one of the accessory gene products of HIV-1, is a 96-residue protein with several functions. It is involved in import of the HIV-1 preintegration complex into the nucleus of nondividing cells, in cellular differentiation, inducing cell cycle arrest at the G(2)/M phase, in immune suppression, and in enhancement of replication of the virus. We found recently that Vpr interferes with the proliferation of mouse NIH3T3 fibroblasts but fails to arrest these cells in the G(2) phase. Thus, it seems possible that Vpr might retard cell proliferation via a novel pathway that is distinct from G(2) arrest. To elucidate the mechanism by which Vpr induces the retardation of cell growth, we developed a panel of expression vectors that encoded Vpr molecules with deletions of specific putative domains, namely, the first alpha-helical domain, the second alpha-helical domain, a leucine zipper-like domain, and an arginine-rich carboxy-terminal domain. These vectors were introduced into HeLa cells since expression of Vpr can induce G(2) arrest in such cells. A carboxy-terminally truncated form of Vpr, C81, which failed to induce G(2) arrest, led to the G(1) arrest and retained the ability to prevent cell proliferation. All the other mutant proteins had completely lost the capacity to induce G(2) arrest and to suppress growth. Substitutions of Ile/Leu for Pro at positions 60, 67, 74, and 81 within the leucine zipper-like domain of Vpr or of C81 revealed that Ile60, Leu67, and Ile74 play an important role in the C81-induced suppression of growth, while Ile74 and Ile81 were found to be indispensable for Vpr-induced G(2) arrest. Collectively, our results strongly suggest that Vpr can retard cell proliferation independently of G(2) arrest of the cell cycle.

Amino Acid Sequence↗
PubMed1999

The effects of benzodiazepine (triazolam), cyclopyrrolone (zopiclone) and imidazopyridine (zolpidem) hypnotics on the frequency of hippocampal theta activity and sleep structure in rats.

In order to investigate the relative efficacy and safety of zopiclone and zolpidem, we compared the effects of higher doses of zopiclone and zolpidem on the frequency of hippocampal theta activity and sleep structure with that of triazolam. Rats were divided into triazolam treatment group (1 mg/kg, 5 mg/kg), zopiclone treatment group (20 mg/kg, 100 mg/kg) and zolpidem treatment group (20 mg/kg, 100 mg/kg). Rats were injected intraperitoneally with these drugs or their vehicle. Polygraphic sleep recording and visual frequency analysis of the hippocampal EEG activity in REM sleep were carried out for 6 h after each injection. Zolpidem, unlike triazolam and zopiclone, had a much milder reducing-effect on the frequency of hippocampal theta activity and suppressing-effect on REM sleep. These results suggest that zolpidem may prove to be a safer hypnotic drug which has fewer or milder side effects than are benzodiazepine and cyclopyrrolone hypnotics.

Animals↗
PubMed1999

Panic attacks in patients with chronic schizophrenia: a complication of long-term neuroleptic treatment.

Panic attacks meeting the diagnostic criteria for panic disorder (DSM-III-R) were found in nine (20%) of 45 patients suffering chronic schizophrenia for more than 5 years. The scores of the Hamilton Depression Rating Scale and the Simpson Angus Scale were significantly higher in the group of patients with panic attacks. They also tended to be taking neuroleptics in larger doses than in the other group. The present report suggests that long-term treatment with neuroleptics is closely related to the manifestation of panic attacks in chronic schizophrenia. It also suggests that when panic attacks are seen frequently in patients taking high doses of neuroleptics, dose reduction of neuroleptics should be considered.

Adult↗
PubMed1999

Postoperative radiation therapy for completely resected invasive thymoma: prognostic value of pleural invasion for intrathoracic control.

BACKGROUND: Optimal management of postoperative radiation therapy for completely resected invasive thymoma remains controversial. This study was conducted to assess the efficacy of postoperative mediastinal irradiation in patients with completely resected invasive thymoma. METHODS: Between 1981 and 1996, 21 patients with completely resected invasive thymoma were referred for postoperative mediastinal irradiation. The distribution of Masaoka stages was stage II in 14 patients and stage III in seven patients. Nine patients had pleural invasion by the tumor. Thirteen patients were treated with a localized field and eight were treated with the whole mediastinal field with boost. The total dose to the primary tumor was 40-61 Gy (median: 52 Gy). The median follow-up time of the 16 living patients was 67 months (range: 29-202 months). RESULTS: The 5- and 10-year actuarial overall survival rates in all patients were both 77%. Relapses were observed in five patients, in all of whom the sites of the first relapse involved pleural dissemination. There were no relapses within the irradiated field in any of the 21 cases. Five of nine (56%) patients with pleural invasion had relapse of pleural dissemination, while 0 of 12 (0%) patients without pleural invasion had relapse. In univariate analysis, pleural invasion had a statistically significant impact on intrathoracic control (P = 0.01). CONCLUSIONS: The results indicated that pleural invasion might be predictive of pleural-based relapse for completely resected invasive thymoma. In patients with pleural invasion, mediastinal irradiation alone might be insufficient to avoid pleural-based relapse even after complete resection.

Adult↗
PubMed1999

Palliative radiation therapy for brain metastases from endometrial carcinoma: report of two cases.

Although endometrial carcinoma is a common invasive neoplasm of the female genital tract, brain metastases are extremely rare and few reports exist of their treatment with radiation therapy. We report two patients with manifest clinical signs of brain metastases from endometrial carcinoma on computed tomography (CT) or magnetic resonance imaging (MRI). These two patients had multiple brain metastases, with widespread dissemination late in the course of the disease and received palliative whole-brain radiation therapy to a total dose of 50 Gy in 25 fractions (case 1) and 30 Gy in 10 fractions (case 2). After radiation therapy, improvement of neurological function (NF) was observed in both patients. The duration of improvement of NF was 9 weeks in case 1 and 12 weeks in case 2. The patients died 5 months and 3 months after the diagnosis of brain metastases, respectively. In these two cases, palliative radiation therapy was effective in improving the quality of the remaining lifetime and appears to be the best treatment for brain metastases from endometrial carcinoma as well as those frequently seen from other primaries.

Adenocarcinoma↗
PubMed1999

Hyperfractionated radiotherapy followed by adjuvant chemotherapy for nasopharyngeal cancer: report of seven cases.

Cases of hyperfractionated radiotherapy and adjuvant chemotherapy for nasopharyngeal cancer are reported. Seven patients received hyperfractionated radiotherapy (76.8-81.6 Gy/64-68 fractions to primary tumor) and two cycles of cisplatin (80 mg/m2 i.v. on day 1) plus 5-FU (800 mg/m2 continuous infusion on days 2-6). Mucositis was the most frequent side effect in hyperfractionated radiotherapy. Moderate leukopenia was the major side effect of adjuvant chemotherapy. With a mean follow-up time of 34 months (range 25-48 months), five of the seven patients were locoregionally controlled. Two developed distant metastases. Two patients suffered late complications (posterior nasopharyngeal wall necrosis and brain necrosis). These results suggested that our regimen was almost well tolerated and might be of use in locoregional control of nasopharyngeal cancer. However, it carries some risk of late complications and might be inadequate for preventing distant metastases. A three-dimensional conformal boost irradiation technique and adequate dose intensity chemotherapy might be encouraged.

Adult↗
PubMed1998

Single and repeated electroconvulsive shocks activate dopaminergic and 5-hydroxytryptaminergic neurotransmission in the frontal cortex of rats.

1. The effect of electroconvulsive shock (ECS) on the extracellular concentration of dopamine (DA), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) was examined in the frontal cortex of rats with the use of in vivo microdialysis. 2. The extracellular concentration of DOPAC, HVA and 5-HIAA was largely increased after the first ECS treatment. The increase after the eighth ECS treatment tended to be attenuated or was significantly attenuated as compared to that after the first ECS treatment. The baseline concentration of DOPAC and 5-HIAA was significantly increased after repeated ECS, though that of DA and HVA did not show any significant change after repeated ECS. 3. These results suggest that the activating effect of repeated ECT on 5-hydroxytryptaminergic (5-HT) and DA neurotransmission, (especially on 5-HT neurotransmission), is significant in improving depression both in patients with Parkinson's disease (PD) and in those who do not suffer from PD.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1998

Intestinal absorption of fluorescence-derivatized cationic peptide 001-C8-NBD via adsorptive-mediated transcytosis.

The intestinal absorption of an intact oligopeptide was investigated in rats using a synthetic cationic peptide, 001-C8 (H-MeTyr-Arg-MeArg-D-Leu-NH(CH2)8NH2). The peptide was coupled with 4-nitrobenzo-2-oxa-1,3-diazole (NBD) to prepare a fluorescence-labeled derivative 001-C8-NBD (H-MeTyr-Arg-MeArg-D-Leu-NH(CH2)8NH-NBD) for the purpose of quantification. The degradation half-life of 001-C8-NBD in jejunal homogenate (1 mg/mL) was 99.5 min, which was significantly longer than that of natural leucine enkephalin (1.14 min). The absorption of 001-C8-NBD was evaluated by the vascular-perfusion method. Intact 001-C8-NBD appeared in the blood time-dependently and the absorption volume at 30 min (2.75 +/- 0.14 microL/cm intestine) was significantly larger than that of [3H]PEG 900 (0.88 +/- 0.13 microL/cm intestine), of which membrane permeability is very low. The absorption of 001-C8-NBD was greatly reduced by an adsorptive-mediated endocytosis inhibitor, protamine (10 mM). No inhibition of the absorption of [3H]PEG 900 by protamine was observed. The intestinal absorption was also measured by an in vivo loop method. The absorption clearance of 001-C8-NBD measured by this method (0.083 +/- 0.008 microL/min/cm intestine) was comparable to that obtained by the vascular perfusion method (0.092 +/- 0.005 microL/min/cm intestine). All of these data suggested that 001-C8-NBD was absorbed as the intact oligopeptide in the intestine in vivo. Adsorptive-mediated transcytosis is suggested to have enormous potential as an oral delivery system for peptide and/or protein drugs.

Animals↗
PubMed1997

Human immunodeficiency virus type 1 Vpr gene product prevents cell proliferation on mouse NIH3T3 cells without the G2 arrest of the cell cycle.

Human immunodeficiency virus type 1 Vpr is a 96-amino-acid virion-associated protein that arrests cells in the G2 phase of the cell cycle in peripheral blood lymphocytes, HeLa, 293, 293T, A549, Jurkat, CEM, SupT1, CV-1 and COS1 cells. When we transfected Vpr expression vector into mouse NIH3T3 and then cultured it in the presence of G418, NIH3T3 cells were the drug resistant cells yielded. The surviving colonies, however, exhibited a degenerating morphology up to 8 approximately 20-fold smaller than the control vector colonies. In addition, the growth of NIH3T3 cells transiently transfected with Vpr expression vector declined dramatically compared with that of transfectants with control vector, suggesting that Vpr significantly interferes with cell proliferation of NIH3T3 cells. Cell cycle characterization by flow cytometry indicated that expression of Vpr did not induce G2 cessation in NIH3T3. These findings strongly suggest that Vpr has a novel pathway to retard cell growth independently and arrests the G2 phase of the cell cycle.

3T3 Cells↗
PubMed1997

Lipid and fatty acid compositions of a novel docosahexaenoic acid-producing marine bacterium.

An unidentified bacterial strain, SCRC-21406, isolated from the intestine of a marine fish, Glossanodon semifasciatus, produced docosahexaenoic acid at 23% (mol/mol) [= 28% (w/w)] of total fatty acids in a medium containing 0.5% (wt/vol) peptone and 0.1% (wt/vol) yeast extract at 12 degrees C under atmospheric pressure. The cell yield was 0.43 g/L. The major lipids of the strain were phosphatidylethanolamine and phophatidylglycerol. Docosahexaenoic acid was localized at the sn-2 positions of both phospholipids. The amounts of polyunsaturated fatty acids other than docosahexaenoic acid were extremely small [< 3% (mol/mol)]. Monounsaturated fatty acids of the cis-7, cis-9 and cis-11 types were detected.

Animals↗
PubMed1997

Dopamine releasing response in rat striatum to single and repeated electroconvulsive shock treatment.

1. The effect of electroconvulsive shock (ECS) on extracellular concentration of dopamine (DA), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) was examined with the use of in vivo microdialysis in rat striatum. 2. Extracellular concentration of DA was markedly increased up to 183% after single ECS, and that of DOPAC, HVA and 5-HIAA was also significantly increased. The increase after the eighth ECS was attenuated compared to their increase soon after the first ECS. After repeated ECS, baseline concentration of DOPAC, HVA and 5-HIAA was significantly increased, and baseline DA concentration tended to increase. 3. These results suggested that single and repeated ECS activated metabolism of DA and 5-hydroxytryptamine in rat striatum. Activated metabolism of DA may be responsible for the clinical effect of electroconvulsive therapy for parkinsonism.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1997

Structure-internalization relationship for adsorptive-mediated endocytosis of basic peptides at the blood-brain barrier.

For the purpose of the brain delivery of peptides, the structural specificity of adsorptive-mediated endocytosis at the blood-brain barrier was studied by measuring transport of a newly synthesized basic peptide 001-C8, H-MeTyr-Arg-MeArg-D-Leu-NH(CH2)aNH2, using primary cultured bovine brain capillary endothelial cells. The apparent uptake of [125I]001-C8 increased time-dependently and reached a steady-state at 60 min. The steady-state uptake of [125I]001-C8 was temperature and concentration dependent and was significantly decreased in the presence of dansylcadaverine, protamine or poly-L-lysine. Uptakes of peptides modified by 1,8-octanediamine, 1,5-pentanediamine, 1,2-ethanediamine or ethylamide and peptides with a free carboxyl terminal were significantly higher than, and similar to, that of [3H]PEG900, respectively. The half-saturation constants and the maximal uptake capacities of these peptides were in the ranges of 0.2 to 134 microM and 1.1 to 408 pmol/mg protein, respectively. These values were correlated with the basicity of the molecules. In conclusion, not the number of constituent amino acids of peptides, but rather the C-terminal structure and the basicity of the molecules are the most important determinants for the uptake by the adsorptive-mediated endocytosis system at the blood brain barrier.

Adsorption↗
PubMed1997

[Redo operation after surgery for aortic aneurysm and dissection].

Thirteen patients who underwent redo operation after surgical treatment of aortic aneurysm and dissection were presented. In 8 patients, redo operations were performed for aortic dissection following aortic valve replacement. A-C bypass, the Koster-Collins operation and replacement of thoracic aorta. In the other 5 patients, the reasons for redo operation were aortic root enlargement after replacement of ascending aorta and aortic valve replacement, pseudoaneurysm and aneurysmal dilatation around coronary button for the Bentall operation and recurrent aneurysm after patch aortoplasty and thoracoabdominal replacement using the Crawford's maneuver. To prevent these redo operation, adequate selection of surgical procedures and meticulous operative techniques should be required in primary operation.

Aortic Dissection↗