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Biomedical subjects

K Aizawa

Publications and source records attributed to K Aizawa.

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

Localization of experimental submucosal esophageal tumor in rabbits by using mono-L-aspartyl chlorin e6 and long-wavelength photodynamic excitation.

BACKGROUND AND OBJECTIVE: To increase the applicability of photodynamic diagnosis with regard to deep-seated tumor, we illuminated tumors with a long-wavelength laser beam after photosensitization with mono-L-aspartyl chlorin e6 (NPe6). STUDY DESIGN/MATERIALS AND METHODS: Rabbits with VX2 esophageal tumors were divided into four groups. The control group was not treated, and the other three groups were injected with 1, 2.5, and 5 mg/kg mono-L-aspartyl chlorin e6 (NPe6), respectively. After excitation with a 664-nm laser beam (10 mW, 10 seconds), the fluorescence image and the relative fluorescence intensity (tumor/normal tissue) were recorded every 2 hours up to 8 hours by a newly developed diode laser endoscopic fluorescence imaging system. The tissue concentration of NPe6 was examined by high performance liquid chromatography at 2, 4, and 6 hours after injection with 1 and 5 mg/kg NPe6. RESULTS: The diode laser endoscopic fluorescence imaging system was able to selectively detect fluorescence from submucosal tumor by comparison with the surrounding normal mucosa after NPe6 injection. The fluorescence intensity correlated with NPe6 dose, selectively accumulated in the tumor tissue and relative intensity peaked at 6 hours after injection. No fluorescent images were detected in controls. CONCLUSION: Given intravenously, NPe6 at a dose of 5 mg/kg and excited with a 664-nm wavelength laser beam 6 hours later can define experimentally induced deep-seated esophageal carcinoma in rabbits, by using an endoscopic fluorescence imaging system.

Animals↗
PubMed2000

Effects on Rb(+)(K+) uptake of HeLa cells in a high K(+) medium of exposure to a switched 1.7 Tesla magnetic field.

Effects of a switched, time-varying 1.7 T magnetic field on Rb(+)(K+) uptake by HeLa S3 cells incubated in an isosmotic high K(+) medium were examined. The magnetic flux density was varied intermittently from 0.07-1.7 T at an interval of 3 s. K(+) uptake was activated by replacement of normal medium by high K(+) medium. A membrane-permeable Ca(2+) chelating agent (BAPTA-AM) and Ca(2+)-dependent K(+) channel inhibitors (quinine, charibdotoxin, and iberiotoxin) were found to reduce the Rb(+)(K+) uptake by about 30-40%. Uptake of K(+) that is sensitive to these drugs is possibly mediated by Ca(2+)-dependent K(+) channels. The intermittent magnetic field partly suppress ed the drug-sensitive K(+) uptake by about 30-40% (P < 0.05). To test the mechanism of inhibition by the magnetic fields, intracellular Ca(2+) concentration ([Ca(2+)]c) was measured using Fura 2-AM. When cells were placed in the high K(&plus;) medium, [Ca(2+)]c increased to about 1.4 times the original level, but exposure to the magnetic fields completely suppressed the increase (P < 0.01). Addition of a Ca(2+) ionophore (ionomycin) to the high K(+) medium increased [Ca(2+)]c to the level of control cells, regardless of exposure to the magnetic field. But the inhibition of K(+) uptake by the magnetic fields was not restored by addition of ionomycin. Based on our previous results on magnetic field-induced changes in properties of the cell membrane, these results indicate that exposure to the magnetic fields partly suppresses K(+) influx, which may be mediated by Ca(2+)-dependent K(+) channels. The suppress ion of K(+) fluxes could relate to a change in electric properties of cell surface and an inhibition of Ca(2+) influx mediated by Ca(2+) channels of either the cell plasma membrane or the inner vesicular membrane of intracellular Ca(2+) stores.

Calcium↗
PubMed2000

RIKEN integrated sequence analysis (RISA) system--384-format sequencing pipeline with 384 multicapillary sequencer.

The RIKEN high-throughput 384-format sequencing pipeline (RISA system) including a 384-multicapillary sequencer (the so-called RISA sequencer) was developed for the RIKEN mouse encyclopedia project. The RISA system consists of colony picking, template preparation, sequencing reaction, and the sequencing process. A novel high-throughput 384-format capillary sequencer system (RISA sequencer system) was developed for the sequencing process. This system consists of a 384-multicapillary auto sequencer (RISA sequencer), a 384-multicapillary array assembler (CAS), and a 384-multicapillary casting device. The RISA sequencer can simultaneously analyze 384 independent sequencing products. The optical system is a scanning system chosen after careful comparison with an image detection system for the simultaneous detection of the 384-capillary array. This scanning system can be used with any fluorescent-labeled sequencing reaction (chain termination reaction), including transcriptional sequencing based on RNA polymerase, which was originally developed by us, and cycle sequencing based on thermostable DNA polymerase. For long-read sequencing, 380 out of 384 sequences (99.2%) were successfully analyzed and the average read length, with more than 99% accuracy, was 654.4 bp. A single RISA sequencer can analyze 216 kb with >99% accuracy in 2.7 h (90 kb/h). For short-read sequencing to cluster the 3' end and 5' end sequencing by reading 350 bp, 384 samples can be analyzed in 1.5 h. We have also developed a RISA inoculator, RISA filtrator and densitometer, RISA plasmid preparator which can handle throughput of 40,000 samples in 17.5 h, and a high-throughput RISA thermal cycler which has four 384-well sites. The combination of these technologies allowed us to construct the RISA system consisting of 16 RISA sequencers, which can process 50,000 DNA samples per day. One haploid genome shotgun sequence of a higher organism, such as human, mouse, rat, domestic animals, and plants, can be revealed by seven RISA systems within one month.

Animals↗
PubMed2000

Effects of photodynamic therapy using mono-L-aspartyl chlorin e6 on vessels and its contribution to the antitumor effect.

The effect of photodynamic therapy (PDT) on the vascular system has a significant role in tumor tissue destruction. We investigated the contribution of vascular damage to the antitumor effects of PDT and analyzed the quantitative vascular changes after PDT. Fibrosarcoma-bearing BALB / c male mice were injected with mono-L-aspartyl chlorin e6 (NPe6) at a dose of 0.25, 5 or 15 mg / kg, and photoradiation was performed with a diode laser 10 min, 2 h or 24 h after injection, respectively. Ten minutes after injection of 0. 25 mg / kg, NPe6 was found to be present only in plasma, while at 2 h after injection of 5 mg / kg it was present in both plasma and tumor, and 24 h after injection of 15 mg / kg it was present only in the tumor. The antitumor effects observed in the 5 mg / kg-2 h and 0. 25 mg / kg-10 min groups were virtually the same, whereas the effect in the 15 mg / kg-24 h group was weaker. The damage to the tumor vasculature and tumor cells in the 15 mg / kg-24 h group occurred later than under the other conditions, and vascular damage in the tumor-surrounding tissue was also less marked even 24 h after PDT. These results suggested that the plasma NPe6 concentration during laser irradiation contributed more than the tumor NPe6 concentration to the antitumor effect, and that the minimal damage to blood vessels around the tumor at the low plasma NPe6 concentration may be one reason for the failure to obtain a marked antitumor effect.

Animals↗
PubMed2000

Renal artery stenosis associated with epidermal nevus syndrome.

Epidermal nevus syndrome is an unusual neurocutaneous disorder in which epidermal nevi are associated with abnormalities of the skeleton and central nervous system, including the eyes and somtimes the cardiovascular system. We treated a patient in whom the latter included renal artery stenosis. An 18-year-old man with epidermal nevi was diagnosed as having the syndrome based on the additional presence of scoliosis, an arachnoid cyst in the middle cranial fossa, and microphthalmos. Hypertension was diagnosed when the patient was 15 years old. The plasma renin activity (9.7 ng/ml/h) was elevated. Right renal artery stenosis was demonstrated by angiography, and the abdominal aorta was narrowed distal to the ostium of the superior mesenteric artery. The plasma renin activity in the right renal vein (16 ng/ml/h) was higher than contralaterally (10 ng/ml/h). Several cardiovascular manifestations have been reported as a complication of epidermal nevus syndrome. Hypertension in an individual with epidermal nevi and congenital anomalies should prompt a search for a vascular anomaly.

Adolescent↗
PubMed2000

Structural features of an anti-diabetic polysaccharide (TAP) from Tremella aurantia.

The structure of an anti-diabetic polysaccharide (TAP) obtained from the fruiting bodies of Tremella aurantia was investigated by methylation analysis, Smith degradation, partial acid hydrolysis, 13C-NMR spectrometry, and enzymatic digestion. The results suggested that TAP was composed of (1-->3)-linked alpha-D-mannopyranosyl residues as a backbone, some of which were substituted at position 2 with (1-->3)-linked beta-D-xylopyranose side chains and with beta-D-glucopyransyluronic acid at position 4 linked to terminal alpha-D-mannopyranose.

Acetylation↗
PubMed2000

Renovascular hypertension observed in a patient with antiphospholipid-antibody syndrome.

The antiphospholipid-antibody syndrome is associated with an increased incidence of arterial and venous thrombosis. Although renal infarction has been observed in these patients, stenotic lesions of the renal artery associated with the antiphospholipid-antibody syndrome have not been reported. A 47-year-old male with a history of hypertension for 7 years developed blurred vision secondary to thrombotic occlusion of the central retinal artery. Laboratory and radiologic examinations revealed renal dysfunction, a positive anticardiolipin antibody, and narrowing of the right renal artery. Successful percutaneous transluminal renal artery angioplasty resulted in normalization of the blood pressure and recovery of renal function.

Angioplasty, Balloon, Coronary↗
PubMed2000

Effect of a polysaccharide (TAP) from the fruiting bodies of Tremella aurantia on glucose metabolism in mouse liver.

An acidic polysaccharide (TAP) obtained from the fruiting bodies of Tremella aurantia significantly increased the activities of glucokinase, hexokinase, and glucose-6-phosphate dehydrogenase, and decreased the activity of glucose-6-phosphatase in normal and diabetic mouse liver after intraperitoneal administration, while the glycogen content in the liver was reduced. Furthermore, TAP lowered the plasma cholesterol level in normal and diabetic mice.

Animals↗
PubMed2000

[Photodynamic diagnosis and photodynamic therapy for experimental hepatoma with ME 2906].

We studied the effects of photodynamic diagnosis (PDD) and photodynamic therapy (PDT) in confirming the existence of hepatoma, using the new photosensitizer mono-L-aspartyl chlorine 6. Japanese white rabbits were selected for abdominal incision under intravenous anesthesia, and VX 2 tumor cells were transplanted into the left liver lobe to create a hepatoma model. In the experiment, hepatoma of 1 cm in diameter (at one week after transplantation) was radiated with a semiconducter laser (664 nm, 200 J/cm2) for treatment.

Animals↗
PubMed1999

Direct interaction between a quinoline derivative, MS-209, and multidrug resistance protein (MRP) in human gastric cancer cells.

MS-209 is a novel quinoline derivative reversing P-glycoprotein-mediated multidrug resistance (MDR). We investigated the interaction between MS-209 and multidrug resistance protein (MRP) in MRP-overexpressing human gastric cancer cells. We measured [3H]leukotriene C4 uptake into the membrane vesicles of the cells and intracellular calcein and [3H]vincristine accumulation with or without MS-209. In multi-drug-resistant MKN45R0.8 cells selected by doxorubicin, MS-209 dose dependently reduced MRP-mediated [3H]leukotriene C4 uptake and increased calcein accumulation. In both resistant and unselected cell lines expressing the MRP gene, MS-209 increased [3H]vincristine accumulation in proportion with the level of MRP mRNA expression and enhanced the cytotoxicity of etoposide, doxorubicin, and vincristine. The reversal effects correlated with the level of MRP mRNA expression in these cells. Our results indicate that MS-209 effectively reverses intrinsic and acquired MRP-mediated MDR of gastric cancer cells by interacting directly with MRP.

ATP-Binding Cassette Transporters↗
PubMed1999

Apoptosis and Bbcl-2 expression in gastric carcinomas: correlation withclinicopathological variables, p53 expression, cell proliferation and prognosis.

We investigated apoptosis and Bcl-2 expression in 221 advanced gastric carcinomas in correlation with clinicopathological variables, p53 expression, cell proliferation and prognosis, using the in situ DNA nick end labeling method and immunohistochemistry. Apoptosis was associated with high immunoreactivity of proliferating cell nuclear antigen. Bcl-2 expression correlated with a low apoptotic index and less malignant behavior of tumors. Prognostically, Bcl-2 expression was associated with a better prognosis, whereas p53 expression was the most important prognostic risk factor. Thus, apoptosis in gastric carcinomas is associated with cell proliferation, and Bcl-2 expression may have a prognostic importance as well as p53 expression.

Apoptosis↗
PubMed1998

Selective removal of cholesterol esters in an arteriosclerotic region of blood vessels with a free-electron laser.

BACKGROUND AND OBJECTIVE: In advanced atheromatous atherosclerosis, a large amount of lipids, particularly cholesterol esters, accumulates on the arterial wall. The selective removal of cholesterol esters accumulated in the intracellular or extracellular spaces has clinical significance. In the present work, the authors investigated the removal of cholesterol esters by using a free-electron laser (FEL) in an arteriosclerotic region. STUDY DESIGN/MATERIALS AND METHODS: Thin films of cholesteryl oleate and albumin and the cross section of a rabbit artery were placed on an inverted microscope stage, and the changes caused by the FEL irradiation of 5.75 microm and 6.1 microm, with 1.5-3 mW on average, were monitored continuously by using a CCD camera in real time. RESULTS AND CONCLUSION: FEL irradiation at a wavelength of 5.75 microm, which is a stretching vibrational mode of the ester, was able to ablate cholesterol esters without affecting albumin. It can also remove cholesterol esters from rabbit arteriosclerotic arterial walls.

Albumins↗
PubMed1998

Esophageal intramural metastasis from an adenocarcinoma of the gastric cardia: report of a case.

We report herein the rare case of a 65-year-old man found to have esophageal intramural metastasis from cancer of the gastric cardia. Endoscopic examination initially revealed an infiltrating ulcerative tumor of the gastric cardia involving the esophagogastric junction, as well as a submucosal tumor of the lower esophagus. A total thoracic esophagogastrectomy with lower mediastinal lymphadenectomy was performed, and the resected specimen demonstrated that both the cardia and esophageal tumors were adenocarcinomas with the same cellular differentiation. As lymphatic invasion and metastases to the paracardial and mediastinal lymph nodes were observed, the esophageal submucosal tumor was considered to be an intramural metastasis from the carcinoma of the gastric cardia resulting from extensive lymphatic spread. The patient died of recurrent disease 9 months after the resection. This case report serves to demonstrate that intramural metastasis may be a local indicator of the systemic spread of disease in patients with gastric carcinoma, as it is in esophageal carcinoma.

Adenocarcinoma↗
PubMed1998

The effects of serum on cellular uptake and phototoxicity of mono-L-aspartyl chlorin e6 (NPe6) in vitro.

Previous reports showed that the photosensitizer mono-L-aspartyl chlorin e6 (NPe6) binds to serum proteins. However, the influence of this binding on the cellular uptake and photodynamic therapy (PDT) phototoxicity of NPe6 is still undefined. In this paper, we studied how serum in medium affected the P388 cellular uptake and PDT phototoxicity of NPe6 in vitro. This was assessed by (1) detection of the red shift (654 nm Q band peak of absorption) induced by protein binding NPe6; (2) detection of intracellular concentration of NPe6 by HPLC and (3) measurements of the cell survival ratio after PDT by MTT assay. The 654 nm Q band peak of NPe6 shifted to 665 nm after binding of NPe6 and serum proteins. The protein-bound NPe6 cannot be uptaken by cells, thus there was no PDT phototoxicity. Nevertheless, phototoxicity recovered when the concentration of NPe6 excessed the serum protein binding ability or there was free serum protein in the medium. These data suggested that the cellular uptake of NPe6 is inhibited by serum components in the medium, and that only free NPe6 is accumulated by P388 cells even during relatively long incubations. The cytotoxicity of PDT mainly depends on the free NPe6 level in the medium.

Animals↗
PubMed1998

Tumor recurrence in patients with early gastric cancer: a clinicopathologic evaluation.

We conducted a retrospective study on 711 patients with early gastric cancer. Twenty-two patients (4.0%) developed recurrent disease and 21 died of recurrence during this study. One hundred and sixty-three patients died of unrelated or unknown causes. The recurrence patterns of 22 patients were as follows: hematogeneous metastasis to the liver in 11 patients, peritoneal dissemination in 3, recurrence in the remnant stomach in 3, and in the distant lymphonodes in 1. The mean survival period of patients with recurrent disease was 50.4 months, and 7 of these patients (31.8%) died more than 5 years after surgery. A retrospective clinicopathologic evaluation of the 22 patients and 526 patients without recurrence revealed significant differences between the two groups with respect to mean age at the time of surgery (62.5 years in the recurrent group vs 57.3 years in the nonrecurrent group), tumor size (41.2 vs 30.6 mm), depth of invasion (submucosal cancer: 19 vs 256), lymphnode metastasis (11 vs 48), lymphatic (11 vs 89) and venous (7 vs 18) invasion, and operative curability (curability B: 8 vs 48). Three patients with intramucosal cancer who died of hematogenous and/or peritoneal recurrence within 7 years after surgery had neither lymphnode metastasis nor lymphatic or venous invasion, suggesting that new techniques are needed for prediction of recurrent disease in patient with early gastric cancer.

Adult↗
PubMed1998

[A basic study of photodynamic therapy of experimental hepatoma with ME 2906].

We have studied effects of photodynamic diagnosis (PDD) and photodynamic therapy (PDT) in hepatoma as confirmed by the existence of hepatoma when using a new photosensitizer mono-L-aspartyl chlorin e6. Japanese white rabbits were selected to perform abdominal incision under intravenous anesthesia and transplant VX2 tumor cells into the liver left lobe for the hepatoma model. Hepatoma of 1 cm in diameter (at one week after transplantation) was used experimentally to radiate a semiconductor laser (664 nm, 200 J/cm2) for treatment.

Animals↗