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Biomedical subjects

K Sueyoshi

Publications and source records attributed to K Sueyoshi.

At least 37 records · Page 2Linked to original sources
PubMed1998

Favorable strategy for the ostial lesion of the left anterior descending coronary artery: influence on narrowing of circumflex coronary artery.

We examined the effectiveness of Palmaz-Schatz (P-S) stent and directional coronary atherectomy (DCA) in ostial lesions of left anterior descending arteries (LAD). The P-S stent was implanted in 11 cases at LAD ostial lesions, and DCA was performed in 13 cases. Percent stenosis and vessel diameter at the target site and the ostium of the circumflex coronary artery (LCX) were measured before and after the procedure. The initial success rate was 100% in both groups. No major complication occurred. LAD ostial lesions were improved from 81.3+/-3.4% to -8.1+/-5.7% by P-S stent and from 82.8+/-2.6% to -2.7+/-3.9% by DCA. LCX ostial vessel diameter was not changed by DCA (from 3.0+/-0.2 mm to 3.1+/-0.3 mm); however, it was significantly decreased by P-S stent (from 2.9+/-0.2 mm to 2.6+/-0.2 mm, P < 0.01). When the angle of LAD and LCX was < or = 80 degrees from the view of RAO 30 degrees and Caudal 30 degrees, the LCX ostium was significantly narrowed by stenting at LAD ostium (P < 0.01). These findings indicate that both the P-S stent and DCA are effective and safe therapies for LAD ostial lesions in cases with LAD-LCX angle > 80 degrees. In cases with LAD-LCX angle < or = 80 degrees, however, DCA is a favored therapy rather than P-S stenting to avoid narrowing of the LCX ostium.

Atherectomy, Coronary↗
PubMed1998

Successful predilation of a resistant, heavily calcified lesion with cutting balloon for coronary stenting: a case report.

A 65-year-old man with a restenotic lesion of the mid LAD was scheduled for Wiktor stent placement. The IVUS revealed circumferential severe calcification. Two conventional, non-compliant angioplasty balloons inflated to high pressures failed to achieved sufficient dilatation and both ruptured. At this point, we selected high pressure inflation of the Cutting Balloon. The Cutting Balloon achieved adequate dilation for stenting and proved to be useful in predilating a circumferential, heavily calcified lesion.

Aged↗
PubMed1998

Glucose and methionine uptake by rat brain tumor treated with prodrug-activated gene therapy.

The effect of acyclovir (ACV) on the metabolism of rat 9L-gliosarcoma cells expressing the herpes simplex virus-thymidine kinase gene was studied using 2-deoxy-2-[18F]fluoro-D-glucose (FDG) and L-[methyl-11C]methionine. Though the average weight of the tumors treated with ACV was significantly lower than that of the saline-injected control group, FDG and methionine uptake per weight of tumor tissue was not different between the two groups. This result exhibits a striking contrast to the metabolic pattern observed after radiation therapy, suggesting the different pathways regarding tumor cell death between the therapies.

Acyclovir↗
PubMed1998

Postrepolarization refractoriness as a potential anti-atrial fibrillation mechanism of pilsicainide, a pure sodium channel blocker with slow recovery kinetics.

The antifibrillatory effect of pilsicainide, a sodium channel blocker with slow recovery kinetics, was investigated in a canine model of atrial fibrillation. Prolonging the atrial effective refractory period is an important mechanism for pharmacological termination of atrial fibrillation. However, the effectiveness of potassium channel blockers has been questioned because of their reverse-use-dependent property. In eight open-chest dogs, the duration of the atrial endocardial monophasic action potential and the atrial effective refractory period were determined using a Franz catheter. Conduction velocity was obtained from a 96-channel mapping electrode at multiple cycle lengths. Inducibility of sustained atrial fibrillation (> 30 minutes) was confirmed by atrial burst pacing during bilateral vagal stimulation, and local fibrillation cycle lengths were measured. Five minutes after restarting fibrillation, pilsicainide (0.6 mg/kg + 0.04 mg/kg/min) was administered. After fibrillation was terminated, measurements were repeated. Pilsicainide successfully terminated atrial fibrillation in 7 of 8 dogs after the median time of 5.1 minutes. The conduction velocity decreased significantly. Although pilsicainide did not affect monophasic action potential duration, it caused use-dependent prolongation of the atrial effective refractory period (P < 0.05), creating postrepolarization refractoriness. Accordingly, pilsicainide prolonged the atrial fibrillation cycle length from 80.6 to 113.8 ms (P < 0.05) before termination of fibrillation. Sodium channel blockers with slow recovery kinetics can prolong the atrial effective refractory period without affecting monophasic action potential duration. Unlike potassium channel blockers, these sodium channel blockers maintain postrepolarization refractoriness, even at rapid stimulation rates, thus exerting a salutary antifibrillatory effect.

Action Potentials↗
PubMed1998

Mutation of the p53 gene in human astrocytic tumours correlates with increased resistance to DNA-damaging agents but not to anti-microtubule anti-cancer agents.

Astrocytic tumours often become resistant to a variety of chemotherapeutic agents in advanced stages and frequently possess mutations in the p53 tumour-suppressor gene. Previous studies using established cell lines to investigate the relation between mutated p53 genes and altered resistance to anti-cancer agents brought inconsistent results. In this report, we examined the status of the p53 gene in 56 astrocytic tumour specimens by single-strand conformation polymorphism and their in vitro chemosensitivity to 30 different kinds of anti-cancer agents. The chemosensitivity was determined by drug-induced cell death using flow cytometry. We found that the mutated p53 gene correlated with increased resistance to DNA-damaging agents but the sensitivity to anti-microtubule agents was independent of the mutation, suggesting a clinical significance of the status of p53 gene in astrocytic tumours and a rational application of anti-microtubule agents to the patients with p53-mutated astrocytic tumours.

Antineoplastic Agents↗
PubMed1998

Discordant prolongation of the refractory period and repolarization time by a class III agent, E4031, in the healing phase of myocardial infarction.

Susceptibility to reentrant tachyarrhythmias and the antiarrhythmic efficacy of class III agents are related more to the duration of the refractory period (ERP) than to the repolarization time (RT). We measured both ERP and RT in a canine model of healing myocardial infarction, and evaluated the effect of a class III agent (E4031) on these parameters and on the inducibility of ventricular tachyarrhythmias. ERP and RT on the unipolar electrogram were measured at several cycle lengths in the normal (NZ) and infarct zones (IZ), respectively, in 10 canine myocardial infarction models and extrastimulation was used to induce ventricular arrhythmias. Measurements were repeated after E4031 administration. At baseline, both ERP and RT were significantly longer in IZ than in NZ with ERP/RT ratio also higher in IZ. This ratio tended to increase at longer cycle lengths. E4031 increased ERP and RT both in NZ and IZ at all cycle lengths, but increased the ERP/RT ratio predominantly in IZ. E4031 prevented induction of sustained VT or VF, which was inducible in 3 out of 10 dogs at baseline, although it facilitated induction of VF in 1 dog with no baseline arrhythmia. By increasing the ERP/RT ratio, class III drugs may shorten the relative refractory period in IZ at the expense of a greater ERP difference created between NZ and IZ.

Animals↗
PubMed1998

[Clinical usefulness of scatter and attenuation correction for brain single photon emission computed tomography (SPECT) in pediatrics].

This investigation was undertaken to study clinical usefulness of scatter and attenuation correction (SAC) of brain SPECT in infants to compare the standard reconstruction (STD). The brain SPECT was performed in 31 patients with 19 epilepsy, 5 cerebro-vascular disease, 2 brain tumor, 3 meningitis, 1 hydrocephalus and psychosis (mean age 5.0 +/- 4.9 years old). Many patients was necessary to be injected sedatives for restraining body motion after Technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) was injected at the convulsion or rest. Brain SPECT data were acquired with triple detector gamma camera (GCA-9300 Toshiba Japan). These data were reconstructed by filtered backprojection after the raw data were corrected by triple energy windows method of scatter correction and Chang filtered method of attenuation correction. The same data was reconstructed by filtered backprojection without these corrections. Both SAC and STD SPECT images were analyzed by the visual interpretation. The uptake ratio of cerebral basal nuclei was calculated by the counts of the thalamus or lenticular nuclei divided by the cortex. All images of SAC method were excellent than that of STD method. The thalamic uptake ratio in SAC method was higher than that of STD method (1.22 +/- 0.09 > 0.87 +/- 0.22 p < 0.01). The lenticular nuclear uptake ratio in SAC method was higher than that of STD method (1.26 +/- 0.15 > 1.02 +/- 0.16 p < 0.01). Transmission scan is the most suitable method of absorption correction. But the transmission scan is not adequate for examination of children, because this scan needs a lot of time and the infants are exposed by the line source radioisotope. It was concluded that these scatter and absorption corrections were most suitable method for brain SPECT in pediatrics.

Adolescent↗
PubMed1997

Evaluation of uptake and release of technetium-99m MIBI SPECT of pulmonary and mediastinal lesions.

We evaluated the uptake and release of Tc-99m MIBI in 7 benign and 30 malignant pulmonary and mediastinal lesions. Of the 37 patients, 13 underwent surgery; malignant involvement was examined in 21 mediastinal lymph nodes. Tl-201 SPECT was also performed in 10 patients. Tc-99m MIBI SPECT studies were performed on transverse SPECT images acquired 30 minutes and 3 hours after intravenous injection of 600 MBq of Tc-99m MIBI with three gamma camera detectors (GCA-9300A). Regions of interest were set in the area of abnormal uptake of Tc-99m MIBI and in an area of normal tissue in the contralateral lung. The uptake ratio of the lesion in the contralateral normal lung was obtained on the early image (early ratio; ER) as well as the delayed image (delayed ratio; DR). The benign lesions showed significantly lower ER (1.6 +/- 0.3) and DR (1.4 +/- 0.4) than the malignant lesions (1.9 +/- 0.5 and 1.8 +/- 0.5, respectively; both p < 0.05). There was no significant difference in the retention index (RI), calculated as RI = (DR-ER)/ER x 100. The DR obtained with Tl-201 SPECT images was significantly higher than that obtained with Tc-99m MIBI SPECT (p < 0.05). For the detection of mediastinal lymph node metastases, the early images showed sensitivity, specificity, and accuracy of 85.7%, 100%, and 95.2%, respectively, for the delayed images these values were 85.7%, 92.9%, and 90.5%, respectively. These results suggest that the uptake ratio of Tc-99m MIBI is a useful index in assessing benign or malignant pulmonary and mediastinal lesions.

Aged↗
PubMed1997

MUC2 gene expression is found in noninvasive tumors but not in invasive tumors of the pancreas and liver: its close relationship with prognosis of the patients.

We have previously reported that MUC2 apomucin was highly expressed in noninvasive tumors of the pancreas (intraductal papillary tumor [IdPT]) and liver (bile duct cystadenocarcinoma [BdCC]), which show more favorable outcomes than invasive carcinomas. In contrast, MUC2 was rarely expressed in invasive carcinomas of the pancreas (invasive ductal carcinoma [IDC]) and the liver (invasive cholangiocarcinoma [ICC]). In the present study, we examined localization of MUC2 messenger RNA (MUC2 mRNA) by using a complementary DNA (cDNA) probe for the MUC2 tandem repeat for in situ hybridization (pHAM1). Localization of MUC2 apomucin was determined by using an antibody directed against MUC2 apomucin (anti-MRP) for immunohistochemistry study. Eleven IdPTs and 10 IDCs of the pancreas, and 8 BdCC and 8 ICCs of the liver were examined. Nine (82%) of 11 IdPTs showed positive expression of MUC2 mRNA in the neoplastic cells, whereas none (0%) of the IDCs showed expression of MUC2 mRNA. Six (75%) of the 8 BdCCs showed positive expression of MUC2 mRNA in the neoplastic cells, whereas none (0%) of the 8 ICCs showed expression of MUC2 mRNA. The localization of MUC2 mRNA and that of MUC2 apomucin usually coincided, although a few cases (1 IDC, 1 BdCC, and 1 ICC) showed focal expression of MUC2 apomucin despite the absence of detectable MUC2 mRNA. These results indicate that the expression of MUC2 apomucin in IdPTs and BdCCs correlates with expression of MUC2 mRNA. In both patient groups with pancreatic tumors and hepatic tumors, patients with positive MUC2 mRNA expression in the tumors showed significantly better survival than those with negative MUC2 mRNA expression in the tumors. The production of MUC2, an abundant extracellular mucin, by most IdPTs and BdCCs may be correlated with tumors that display lower levels of invasion and metastasis.

Aged↗
PubMed1997

Prediction of drug cytotoxicity in 9L rat brain tumor by using flow cytometry with a deoxyribonucleic acid-binding dye.

OBJECTIVE: Flow cytometry (FCM) with a deoxyribonucleic acid (DNA)-binding dye, propidium iodide, provides a rapid and quantitative method to detect apoptotic cell death. This technique was used to examine the sensitivity of tumor cells to anticancer agents, as a novel test of chemosensitivity in vitro. METHODS: The in vitro chemosensitivity of 9L gliosarcoma cells to a panel of anticancer agents (cisplatin, nimustine, adriamycin, cyclophosphamide, vincristine, 5-fluorouracil, and methotrexate) was investigated by both FCM, yielding DNA histograms, and a microtiter tetrazolium test, measuring cellular metabolism. Clinically achievable concentrations of the agents were used for the analysis of DNA histograms and proliferation of 9L cells in vitro. Rats intracranially inoculated with 9L cells were treated with the agents, and tumor masses were visually monitored by using magnetic resonance imaging with gadolinium-diethylenetriaminepentaacetic acid enhancement. RESULTS: The cytotoxic effect of anticancer agents examined by the microtiter tetrazolium test correlated with a decreased G0/G1 peak in the DNA histograms. Serial FCM analysis showed that the decrease in the G0/G1 peak was subsequently accompanied by increased hypodiploid areas, suggesting DNA fragmentation induced by the agents. The in vitro chemosensitivity test and cell proliferation examination showed that all agents except cisplatin were effective. Growth retardation of inoculated brain tumors and prolonged survival of inoculated rats were observed with treatment with the anticancer agents, except cisplatin. CONCLUSION: The present study shows that FCM analysis with a DNA-binding dye can detect DNA damage induced by anticancer agents, and it suggests that this technique is a novel method to test chemosensitivity in vitro.

Animals↗
PubMed1997

[Usefulness of 99mTc-tetrofosmin myocardial scintigraphy before and after coronary intervention].

Dipyridamole-loading 99mTc-tetrofosmin myocardial scintigraphy was performed for patients with coronary artery disease who underwent percutaneous transluminal coronary angioplasty (PTCA) in order to examine whether SPECT imaging prior to treatment is useful for the determination of prognosis after coronary intervention. Thirty-six patients including 9 with angina pectoris (AP), 22 with old myocardial infarction (OMI) and 5 OMI with AP were underwent dipyridamole-loading 99mTc-tetrofosmin myocardial SPECT before and after coronary intervention. The length of follow-up was 185 +/- 107 days after PTCA. Improvement of myocardial uptake was observed on myocardial SPECT in all cases with AP. Improvement of the myocardial uptake was observed 50% (4/8) of patients with OMI who had no myocardial viability. It was suggested that the improvement of myocardial uptake after PTCA was due to incomplete fill-in in cases with AP and that the presence of fill-in was important for level of fill-in in patients with AP. The improvement of myocardial uptake in the scar tissue in patients with OMI contributed to the hibernating myocardium. We concluded that correct detection of hibernating myocardium was difficult despite the superior imaging capability of 99mTc-tetrofosmin myocardial SPECT.

Aged↗
PubMed1997

[Quantitative measurement of cerebral blood flow by the microsphere model with super-early 123I-IMP brain SPECT].

Cerebral blood flow (CBF) was quantitatively measured in 6 healthy young volunteers based on "super-early" acquisition of N-isopropyl-p-[123I]iodoamphetamine (IMP) brain SPECT obtained 4-6 min after IMP injection with a three-head rotating gamma camera and the microsphere (MS) model. The ratio of radioactivity (count/pixel/min) in the conventional early SPECT image (taken 25-55 min after IMP injection) to that in the "super-early" image for each brain region negatively correlated with regional CBF value obtained with the "super-early" MS method. This indicates that wash-out of IMP from the regions with higher CBF is faster than that from the regions with lower CBF and that CBF values are underestimated with the conventional MS method in regions with higher CBF. Regional CBF was quantitatively measured with the "super-early" MS method and the ARG method, a recently developed method based on two-compartment model. The mean cortical CBF was 52.5 +/- 7.0 (ml/100 g/min, mean +/- SD) with the "super-early" MS method and 47.5 +/- 3.3 with the ARG method. The CBF values obtained with the "super-early" MS method agreed with those previously reported with positron emission tomography. Since the MS method is theoretically the simplest model, the "super-early" MS method can be applied various disorders of the central nervous system where the behavior of IMP is not fully understood.

Adult↗
PubMed1996

Evaluation of the bystander effect in experimental brain tumors bearing herpes simplex virus-thymidine kinase gene by serial magnetic resonance imaging.

Antitumor effects of herpes simplex virus-thymidine kinase (HSV-tk) gene transfer followed by ganciclovir (GCV) administration were studied by serial magnetic resonance imaging (MRI) with reference to the bystander effect. Mixed populations of 9L-gliosarcoma cells transduced with the HSV-tk gene (TK cells) and wild-type 9L cells were implanted into the brain of syngeneic Fisher rats at various ratios (total cell number, 10(5) cells; percentage of TK cells, 100%, 25%, 10%, or 0%). Rats were treated with GCV (30 mg/kg per day) or saline for 14 days and tumor masses were visually monitored using MRI. All of the saline-treated rats (regardless of TK cell percentage) and GCV-treated rats inoculated with 0% TK cells died between day 19 and day 31 (mean survival, 22.9 days) due to progressive tumor growth. The GCV-treated rats inoculated with more than 10% of TK cells lived significantly longer than the saline-treated rats (p < 0.01). The mean survivals of GCV-treated groups were 50.7, 70.0, and longer than 100 days for 10%, 25%, and 100% TK cells, respectively. MRI study revealed that reduction in tumor size and disappearance of tumor were observed in the GCV-treated rats inoculated with 10% or 25% TK cells. Complete regression of the tumor was, however, observed only in the rats implanted with 100% TK cells. The present results show that the bystander effect is clearly observed in vivo in a TK percentage-dependent manner, and a population of more than 25% of TK-positive cells is required for complete tumor elimination.

Animals↗
PubMed1996

Association of p53 gene mutation with decreased chemosensitivity in human malignant gliomas.

Loss of p53 function is involved in tumorigenesis of various human cancers, but the relation between mutation of the p53 tumor-suppressor gene and the chemo- and radiosensitivity of tumors remains unclear. Mutated p53 gene in malignant glioma is often associated with progression and recurrence of malignancy, and these events are closely linked with increased resistance to both chemotherapy and radiation. We have examined the status of the p53 gene in malignant gliomas obtained from 34 patients (glioblastoma: 29 cases, anaplastic astrocytomas: 5 cases). The chemosensitivities of these specimens using 28 kinds of anti-cancer agents were determined using an in vitro assay system. Overall, 12 mutated cases of p53 gene were found in malignant glioma samples. The mean numbers of effective agents were 0.58 for the tumor samples with p53 mutations and 5.00 for tumors without mutations. Our data indicate that p53 gene mutation predisposes to decreased cell killing via chemotherapy in malignant gliomas.

Adolescent↗
PubMed1996

The effect of steroid on thallium-201 uptake by malignant gliomas.

In order to assess the effect of steroid on thallium-201 uptake by glioma, 201Tl single-photon emission tomography was performed before and after steroid administration in four patients with recurrent malignant glioma. After steroid administration the 201Tl index, expressed as the ratio of 201Tl uptake in the tumour to that in the contralateral cerebral hemisphere, was 0.77+/-0.11 of the value before steroid (mean+/-SD: P<0.05 by paired t test). The 201Tl index has been used as a possible indicator for the differentiation of malignant gliomas from relatively benign tumours or radiation necrosis. The present results indicate that the effect of steroid has to be taken into account when semi-quantitative analysis, e.g. by means of the 201Tl index, is used in patients with brain tumours.

Antineoplastic Agents, Hormonal↗
PubMed1996

Quantifying brain tumor blood flow by the microsphere model with N-isopropyl-p-[123I]iodoamphetamine super-early SPECT.

Regional cerebral blood flow was quantitatively measured in 6 patients with brain tumor by the microsphere model with N-isopropyl-p-[123I]iodoamphetamine (IMP) "super-early" single photon emission computed tomography (SPECT) images obtained 4-6 min after IMP injection with a three-head rotating gamma camera. The ratio of radioactivities (counts/pixel/min) in the "early" SPECT images (taken 25-55 min after IMP injection) to the "super-early" images of the brain tumors was 1.47 +/- 0.13 (mean +/- SD, n = 6), which was significantly lower than the ratio in the normal cerebral cortices (1.93 +/- 0.25) (p < 0.01). This indicates faster clearance of IMP from the tumor tissue than that from the normal brain tissue. Blood flow values for the brain tumors obtained by the microsphere model based on the "super-early" SPECT images were 39.3 +/- 12.4 ml/100 g/ min, which was similar to the blood flow values for normal gray matter and in agreement with previous studies with positron emission tomography.

Adult↗
PubMed1996

Emergence of proteases in germinating cucumber cotyledons and their roles in the two-step degradation of storage protein.

The degradation of storage protein in germinating cucumber seeds was shown to proceed via two distinct steps. First, several proteases with acidic isoelectric points (pIs) were involved in solubilization and partial degradation of 11S globulin. Treatment of seedlings with cycloheximide inhibited this step and the expression of these proteases. Thus, the first step appeared to be governed by these proteases, which were synthesized de novo after imbibition. The first step was observed in dark-grown cotyledons, but the complete degradation of 11S globulin did not occur in the absence of illumination. An additional protease, with a pI of 4.5, was induced by illumination, and it was involved in the further cleavage of the partially degraded products of 11S globulin. Thus, the complete degradation of the storage protein proceeded via a two-step process in illuminated germinating seedlings. Light is needed to induce the second step in the degradation of 11S globulin that supplies the nitrogen required for development of the photosynthetic apparatus in the greening cotyledon.

Amino Acid Sequence↗