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Biomedical subjects

S Yamada

Publications and source records attributed to S Yamada.

At least 721 records · Page 40Linked to original sources
PubMed1996

Release and uptake of vitamin B12 by asakusanori (Porphyra tenera) seaweed.

When asakusanori was incubated in artificial seawater, it released a significant amount of vitamin B12. The rate of release was very high at the beginning of incubation and steeply decreased. Four-fifths of the released B12 was a macromolecule-bound form and the rest was free form, of which some were taken up by the asakusanori tissue. Asakusanori took up the free form B12 from the incubation medium by concentration- and temperature-dependent processes. The amount of uptake increased with the time of incubation and did not attain a plateau after 4 h. The capacity was retained even after storage in frozen state for 11 months.

Diffusion↗
PubMed1996

[Enhancement of cytotoxic effect of anticancer agents of renal cell carcinoma].

BACKGROUND: Human renal adenocarcinomas do not adequately respond to cancer chemotherapy. Their multidrug resistance is mainly conferred by the P-glycoprotein (P-gp). In this study, we analyzed effects of P-gp modulators on enhancement of anticancer activities against human renal cell carcinomas. METHODS: ACHN/ADM human renal adenocarcinoma cells with a high level expression of P-gp and 28 surgical specimens of renal cell adenocarcinomas were recruited. Adriamycin (ADM) and vinblastin (VLB) were used as anticancer drugs, and verapamil (Ver) and cyclosporin A (CsA) were as P-gp modulators. The chemosensitivity was determined by the ATP-assay. RESULTS: Ver and CsA exhibited 1.5-fold and 6-fold increase, respectively, in the anticancer activities of ADM against ACHN/ADM cells. The anticancer activities of VLB were also enhanced by the modulators; 7-fold for Ver and 11-fold for CsA. In the chemosensitivity test of clinical specimens, the cancer for which the viability of the cells assessed by the ATP-assay was 50% or less than 50% after exposure to the anticancer drug with or without a P-gp modulator was defined as sensitive to the drug. Of the 14 clinical specimens exposed to anticancer drugs without Ver, only 3 tumors and 1 tumor were sensitive to ADM and VLB, respectively, whereas with Ver, 6 tumors and 4 tumors were sensitive to ADM and VLB, respectively. Of the other 14 clinical specimens exposed to anticancer drugs without CsA, only 3 tumors and no tumor were sensitive to ADM and VLB, respectively, whereas, with CsA, 9 tumors and 6 tumors were sensitive to ADM and VLB, respectively. CONCLUSION: This study indicate that Ver and CsA have effects on enhancement of the anticancer activities of ADM and VLB against human renal adenocarcinomas. The addition of Ver or CsA to chemotherapy will be a potential circumvention of P-gp-mediated multidrug resistance of renal cell adenocarcinomas.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1996

[Retroperitoneal laparoscopic nephrectomy: initial 2 cases].

Two patients with nonfunctioning kidney were treated with retroperitoneal laparoscopic nephrectomy. The working space in the retroperitoneum was created by balloon dissector consisted of surgical glove and rigid nephroscope. The balloon dissector inserted to retroperitoneal space was inflated with 500-600 ml normal saline. After removal of the balloon dissector, 4 trocars were inserted to the retroperitoneal space. In these two cases, the kidney were removed successfully without any complication. The operating time was 165 min and 219 min, respectively.

Aged↗
PubMed1996

Alterations in calcium antagonist receptors and calcium content in senescent brain and attenuation by nimodipine and nicardipine.

Characteristics of L- and N-type calcium (Ca++) channel antagonist receptors in brains of senescence-accelerated prone mouse (SAMP8) showing age-related deterioration of learning and memory were examined by using (+)-[3H]PN 200-110 and [125I]omega-conotoxin GVIA as radioligands. There was a tendency toward consistent decrease in Bmax for both radioligands in seven brain regions of SAMP8 compared with the control mouse. The reduction in (+)-[3H]Pn 200-110 binding sites was statistically significant in the hippocampus, midbrain and pons/medulla oblongata, and that in [125I]omega-conotoxin binding sites was significant in the cerebral cortex, corpus striatum and pons/medulla oblongata. On the other hand, there was a marked elevation in Ca++ content in the brain of SAMP8. Chronic p.o. administration (0.3, 1 and 3 mg/kg/day for 3 weeks) of nimodipine and nicardipine to SAMP8 caused a significant increase in the Bmax values of (+)-[3H]PN 200-110 binding in the cerebral cortex and hippocampus. This may reflect up-regulation of brain Ca++ channel antagonist receptors as a result of the prolonged blockade by nimodipine and nicardipine. On the other hand, similar administration of amlodipine and nilvadipine failed to produce an enhancement of Bmax values of (+)-[3H]PN 200-110 binding, whereas both drugs at high doses evoked a significant increase in the apparent dissociation constant. Furthermore, the brain Ca++ content in SAMP8 was markedly reduced by chronic p.o. administration of Ca++ channel antagonists, and the decrease was equivalently observed for all of four 1,4-dihydropyridine antagonists in spite of the difference in the effect on brain receptors. In conclusion, the present study suggests that there is an altered Ca++ homeostasis in the SAMP8 brain that is effectively attenuated by chronic administration of nimodipine and nicardipine. Hence SAMP8 may be a suitable animal model for evaluating the therapeutic effects of Ca++ channel antagonists on neurological disorders associated with the aging brain.

Aging↗
PubMed1996

Evaluation of tissue plasminogen activator and plasminogen activator inhibitor-I levels in acute myocardial infarction.

Fluctuations in tissue plasminogen activator (t-PA) activity, t-PA antigen, and plasminogen activator inhibitor-I (PAI-1) antigen levels were evaluated in blood samples obtained from 84 patients with initial uneventful acute myocardial infarction (AMI) and 35 patients with reinfarction and fatal infarction (patients with bad prognoses). Patients with initial AMI had significantly higher levels of t-PA activity than those of 14 patients with angina pectoris. Tissue plasminogen activator activity peaked between day 7 and 19 after the initial attack of AMI. Plasminogen activator inhibitor-I antigen level decreased significantly between day 2 and 19, then returned to the baseline levels of patients with angina pectoris nearly 4 weeks later. The t-PA activity levels of patients with reinfarction were significantly lower than those in patients without events between day 0 and 3 and between day 7 and 19. The percentage stenosis in the coronary arteries measured by coronary angiography was negatively correlated with t-PA activity. This information may help in selecting aggressive treatments such as thrombolysis by recombinant t-PA and predicting the prognosis for patients with AMI.

Aged↗
PubMed1996

Feasibility of fluorine-18-fluorophenylalanine for tumor imaging compared with carbon-11-L-methionine.

UNLABELLED: L-[methyl-11C]methionine (11C-Met) is a useful tracer for tumor imaging with PET. The drawbacks include a short half-life and high physiological accumulation in abdominal organs. To overcome these shortfalls, the feasible use of [18F]fluorophenylalanine (18F-Phe), which shares the same amino acid transport system with Met, for tumor imaging was examined. METHODS: The time course of tissue distribution of 18F-Phe and the tumor uptake response to radiotherapy were compared with 14C-Met and [3H] thymidine (3H-Thd) in the rat AH109A tumor model. Intratumoral distribution of 18F-Phe was compared with 14C-Met and 14C-Thd using double-tracer macroautoradiography (ARG). We also evaluated whole-body ARG. RESULTS: Tumor uptake of 18F-Phe peaked at 60 min postinjection and was higher than that of the liver, intestine and kidney but lower than the pancreas. Tumor uptake of 18F-Phe was similar to that of 14C-Met. Tumor-to-blood and tumor-to-muscle ratios were higher in 14C-Met compared with that of 18F-Phe because of the rapid blood clearance of 14C-Met. With whole-body ARG, the tumor was clearly visualized with high contrast. Radiotherapeutic response of tumor uptake of 18F-Phe was as rapid as that with 14C-Met and with 3H-Thd. Intratumoral distribution of 18F-Phe and 14C-Met were identical, and 18F-Phe and 14C-Thd were similar. CONCLUSION: Fluorine-18-Phe seems to be a potentially useful amino acid tracer for tumor imaging with a longer half-life than 11C, with higher tumor contrast in the abdomen than Met and a similar sensitive response to radiotherapy.

Animals↗
PubMed1996

[Cerebral atrophy and ventricular enlargement in physiological ageing--a morphometrical study in 28 autopsy brain of normal old people].

It is generally agreed that the adult human brain shows atrophy with advance of ageing. Although this phenomenon has been confirmed, mainly by measurement on CT images, there were only a few studies on brains over the age of 70 years. We measured the cranial cavity volume brain volume and ventricular volume in 28 normal autopsy brains of from 63 to 96 years of age (mean 81.4 years). We found that the ratio between the brain volume and the cranial cavity volume (B/C ratio), and the ratio between the ventricular volume and the brain volume (V/B ratio), had no significant correlation to age (B/C ratio: r = 0.22, p = 0.28, V/B ratio; r = 0.13, p = 0.50). Although our results are compatible with the previous studies on very old people, they are different from those on middle aged and presenile people. We considered that the cerebral atrophy become far less marked after 70 years of age.

Aged↗
PubMed1996

[A case of hepatocellular carcinoma with reduction of primary tumor and disappearance of multiple lung metastasis].

A 62-year-old male patient was admitted for spontaneous rupture of hepatocellular carcinoma. He also had multiple lung metastases and liver dysfunction. So neither operation nor trans-arterial embolization could be performed. He had been administered UFT (400 mg/day) orally every day. After 5 months of daily administration, there was complete disappearance of multiple lung metastasis and reduction of the primary tumor. This case suggests that UFT is effective for some advanced hepatocellular carcinoma with extrahepatic metastasis.

Administration, Oral↗
PubMed1996

Prevalence of skin neoplasms among the atomic bomb survivors.

About 7,000 atomic bomb (A-bomb) survivors from Hiroshima and Nagasaki who participate in the Radiation Effects Research Foundation (RERF) Adult Health Study (AHS) were examined to define the relationship between skin neoplasms and exposure to ionizing radiation. Careful clinical inspection of the skin was undertaken to detect not only skin cancer but precancerous lesions such as senile keratosis. Five cases of basal cell carcinoma, five cases of senile keratosis and one case of Bowen's disease were confirmed histologically among 5955 A-bomb survivors for whom Dosimetry System 1986 (DS86) dose estimates are available. The relationship between the combined prevalence of skin cancer and precancerous lesions and DS86 dose was examined together with other factors that might affect skin neoplasms including occupational exposure to ultraviolet (UV) rays, age, sex and city. The prevalence of basal cell carcinoma and senile keratosis increased as the DS86 dose increased. The prevalence of skin cancer and senile keratosis among persons engaged in work involving frequent exposure to UV rays was higher than among those who were not engaged in such work. Sex and city were not significantly related to those skin diseases. Odds ratios of skin neoplasm for a 1-Gy dose, occupational exposure to UV rays and age at time of examination (in 10-year increments) are 1.7, 5.9 and 1.9, respectively.

Adult↗
PubMed1996

[Analysis of locally controlled esophageal carcinomas treated with radiotherapy].

Of 227 esophageal carcinomas treated with a radiation dose of 60 Gy or more, 100 patients had no tumor or ulceration (with or without stenosis) of the esophagus after irradiation. We analyzed local control factors of these 100 patients to determine the need for further treatment. The cumulative local control rate at five years was 40% in all cases, 37% in 21 cases without any stenosis of the esophagus and 40% in 79 cases with stenosis. The presence of stenosis of the esophagus after irradiation was not a critical factor in predicting final local control. Local recurrence of tumors with findings of Borrmann III or Borrmann IV by the pretreatment esophageal barium study, tumors controlled after a total dose of more than 80 Gy, tumors without low dose rate telecobalt therapy (LDRT; 1 Gy/hour, 5 to 7Gy/day, a total dose of 12 to 15 Gy) as boost therapy, and apparently controlled tumors with a stenotic ratio of 60% or more or with 5 cm or more length of stenosis of the esophagus after irradiation was significantly higher than that of the others (p < 0.05). Multivariate analysis revealed that findings of pretreatment barium study, total dose, with or without LDRT, and length of stenosis of the esophagus after irradiation were significantly important factors in local control. Members of the high risk group of apparently controlled tumors should undertake surgical treatment or further intensive chemotherapy.

Aged↗
PubMed1996

Long-term stone recurrence rate after extracorporeal shock wave lithotripsy.

PURPOSE: We followed patients who were stone-free after extracorporeal shock wave lithotripsy (ESWL) to investigate the factors that contributed to recurrent calculi. MATERIALS AND METHODS: For longer than 5 years 903 patients without residual fragments 3 months after ESWL were enrolled in this study. Plain abdominal films and/or excretory urograms were evaluated every 6 months for recurrent stones on the side of ESWL. Patients who presented with colic pain or other complaints and who were suspected of having recurrent stones were also examined. Stone recurrence rates were calculated with the Kaplan-Meier method. We assessed the influence of patient age; size, location, composition and configuration of the original stones, and pyuria after ESWL on stone recurrence. RESULTS: Mean followup was 25 months and stones recurred in 183 of 903 renal units (20.3%). Kaplan-Meier recurrence rates were 6.7, 28.0 and 41.8% after 1, 3 and 5 years, respectively. There was a significant correlation between stone recurrence and multiple stones on one hand, and pyuria after ESWL on the other hand. Stones recurred most frequently in the lower calix. Recurrent stones were passed without intervention in 33 cases, while ESWL was repeated in 53. CONCLUSIONS: These data demonstrate the importance of long-term followup and the search for an effective prophylactic therapy to prevent recurrence.

Adolescent↗
PubMed1996

[Clinical evaluation of hepatic arterial infusion chemotherapy in patients with liver metastases from colorectal cancer].

Seventy-four cases of hepatic metastasis of colorectal cancer experienced in our hospital from January 1988 to February 1996 were examined for hepatic arterial infusion chemotherapy induced macrobiotic effect. A group (21 cases of hepatectomy and hepatic arterial infusion chemotherapy), B group (31 cases of hepatic arterial infusion chemotherapy only) and C group (22 cases of iv and po systemic chemotherapy) were comparatively examined for survival rate using Kaplan-Meier method. Single administration of adriamycin, epirubicin, cisplatin (CDDP) and 5-FU, along with CDDP-5-FU combined therapy and 5-FU 1,000 mg/5 hr intermittent continuous infusion therapy, were used. Mean survival period was 719 +/- 369, 426 +/- 417, 158 +/- 125 days for groups A, B and C, respectively. One-year survival rate by degrees of H factor was comparatively examined because of different H factor rates for these 3 groups. As a result, it proved to be 83 and 40% for groups A and B, respectively, in H1,2 cases and 32 and 11% for groups B and C, respectively, in H3 cases, with their respective significant differences (p < 0.05). Positive treatment, including hepatectomy, hepatic arterial infusion chemotherapy and the like, was suggested to contribute to patient macrobiosis.

Aged↗
PubMed1996

Re-evaluation of myocardial FDG uptake in hyperglycemia.

UNLABELLED: Myocardial [18F] fluorodeoxyglucose (FDG) uptake depends on several metabolic variables in vivo. The effect of different levels of experimentally induced hyperglycemia on myocardial FDG uptake was examined. METHODS: FDG uptake was studied in young Donryu rats 1 hr after intravenous injection under various pretreatments that increased serum glucose levels. Serum samples were analyzed for glucose, insulin and free fatty acids. Myocardial distribution of FDG was examined with autoradiography. RESULTS: Administration of glucose (n = 42), triiodothyronine (n = 7), epinephrine (n = 7), dehydroascorbic acid (n = 5) and 4 mg streptozotocin (Szt, n = 10) increased glucose levels to 120-200 mg/dl. Dexamethasone (Dex, n = 34) and 6 mg Szt (n = 6) increased glucose levels to 200-450 mg/dl. Myocardial FDG uptake increased proportionately with increases in serum glucose level up to 200 mg/dl. In severe hyperglycemia (serum glucose: 200-450 mg/dl), however, the FDG uptake decreased and did not correlate with blood glucose level. A study of fractional FDG uptake calibrated by the arterial FDG curve confirmed the same results. Heterogeneous distribution of FDG was observed in the myocardium, both in fasting and in severe hyperglycemic conditions. The pattern of FDG uptake by skeletal muscles was similar to that of the myocardium, although the uptake was lower than that in the myocardium. Changes in insulin and free fatty acids levels could not explain the FDG uptake pattern in severe hyperglycemia. Blood FDG uptake level remained constant regardless of glucose level. CONCLUSION: Hyperglycemia induced a biphasic pattern of myocardial FDG uptake, common with skeletal muscles. The understanding of myocardial FDG uptake characteristics and their dependence on blood glucose is helpful in interpreting myocardial FDG-PET images.

Animals↗
PubMed1996

[Changes in plasma level of brain natriuretic peptide during exercise in recovery phase of myocardial infarction and the clinical significance].

Brain natriuretic peptide (BNP) plasma levels increase in patients with myocardial infarction and may reflect the degree of left ventricular dysfunction. The changes in plasma level of BNP during exercise in the recovery phase and the clinical significance were investigated in 60 patients (55 men and 5 women; mean age 62.3 +/- 9.8 years) with initial acute infarction. Cardiopulmonary exercise testing was performed with a treadmill using the ramp protocol in 60 patients in the first month and 46 in the third month after the onset of the disease. Blood samples for measuring BNP and atrial natriuretic peptide (ANP) were obtained in the resting control state and immediately after peak exercise. Plasma BNP in the first month had a significant negative correlation with anaerobic threshold (AT) and peak oxygen uptake (peak VO2), and the serial change in plasma BNP from the first to third month had a significant negative correlation with the serial change of AT (peak: r = -0.35, p < 0.05) and peak VO2 (rest: r = -0.35, p < 0.05; peak: r = -0.45, p < 0.01). The serial change of plasma ANP had no relationships with the serial change of AT or peak VO2. Because the serial change ratio of plasma BNP reflects the serial change of exercise tolerance in the recovery phase of myocardial infarction, we conclude that the serial measurement of plasma BNP level is a useful non-invasive parameter for predicting latent heart failure in patients with myocardial infarction.

Aged↗
PubMed1996

Decreased incidence of thymic lymphoma in AKR mice as a result of chronic, fractionated low-dose total-body X irradiation.

We have investigated whether low-dose total-body X irradiation could suppress the development of lymphoma in AKR mice. Male mice were irradiated with 5 cGy three times a week or 15 cGy two times a week from 11 weeks of age for 40 weeks. The incidences of lymphoma were 80.5% in sham-irradiated mice, 67.5% in mice irradiated with 5 cGy three times a week and 48.6% in mice irradiated with 15 cGy twice a week. Incidence of lymphoma was significantly reduced by irradiation with 15 cGy twice a week (P = 0.006). The mean survival time was significantly prolonged from 283 +/- 3 days in control mice to 316 +/- 10 days in mice irradiated with 15 cGy twice a week (P = 0.008) and to 309 +/- 14 days in mice irradiated with 5 cGy three times a week (P = 0.040). Because about 80% of male AKR mice die of lymphoma, it is likely that the prolonged life span observed in the irradiated mice is due to the reduced incidence of lymphoma.

Animals↗