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Biomedical subjects

K Tashiro

Publications and source records attributed to K Tashiro.

At least 55 records · Page 3Linked to original sources
PubMed2001

The relationship between the aggregational state of the amyloid-beta peptides and free radical generation by the peptides.

In the present study, we investigated whether or not the amyloid-beta protein (Abeta) peptide itself spontaneously generates free radicals using electron spin resonance (ESR) spectroscopy while also monitoring the aggregational state of Abeta and Abeta-induced cytotoxicity. The present results demonstrated a four-line spectrum in the presence of both Abeta40 and Abeta42 with Ntert-butyl-alpha-phenylnitrone (PBN), but not in the presence of PBN alone in phosphate-buffered saline (PBS). The fact that the four-line spectrum obtained for the Abeta/PBN in PBS was completely abolished in the presence of the iron-chelating agent Desferal demonstrated the observed four-line spectrum to be iron-dependent. The present study also revealed that either Abeta40 or Abeta42 with PBN in phosphate buffer (PB) did not produce any definite four-line spectrum. Both a thioflavine-T (Th-T) fluorometric assay and circular dichroism (CD) spectroscopy showed the amyloid fibril formation of Abeta in PBS to be much higher than that of Abeta in PB. Moreover, Abeta-induced cytotoxicity assays showed Abeta incubated in PBS to be more cytotoxic than that incubated in PB. These results thus suggest that Abeta-associated free radical generation is strongly influenced by the aggregational state of the peptides.

Alzheimer Disease↗
PubMed2001

Aerosolized surfactant therapy for endotoxin-induced experimental acute respiratory distress syndrome in rats.

We have compared the effects of inhalation of aerosolized surfactant on experimental acute respiratory distress syndrome. Escherichia coli endotoxin (55 (SD 20) mg kg(-1)) was injected into the tracheas of 36 adult rats anaesthetized and mechanically ventilated with pure oxygen. When the Pa(O(2)) decreased to 11.3 (3.3) kPa, the animals were randomly subjected to inhalation of aerosolized modified natural surfactant (MNS) for 0 min (control group), 30, 60, and 120 min. In the control group, Pa(O(2)) remained below 12 kPa for 180 min. In the groups receiving inhalation of surfactant for 30 and 60 min, Pa(O(2)) increased but decreased soon after termination of the inhalation. In contrast, Pa(O(2)) of the group receiving inhalation of surfactant for 120 min continued to increase, reaching 52.1 (12.5) kPa at 180 min (P<0.05 vs control). Thus, we conclude that improvement in gas exchange as a result of inhalation of MNS depends on the duration of inhalation.

Aerosols↗
PubMed2001

Glutathione-S-transferase-pi expression regulates sensitivity to glutathione-doxorubicin conjugate.

We have reported that glutathione-doxorubicin conjugate (GSH-DXR) exhibited potent cytotoxicity against tumor cells and inhibited glutathione-S-transferase (GST) enzyme activity. In order to determine whether or not the expression of GST-pi lowered the cytotoxicity of GSH-DXR, cytocidal activity of the conjugate was examined using tumor cells in which the level of GST-pi expression was regulated by transfecting GST-pi cDNA in the correct or reverse direction and comparing with that of DXR. Enhancement of GST-pi expression by transfecting GST-pi sense cDNA into human hepatoblastoma HepG2 cells in which GST-pi expression was extremely low caused an increase in GST activity from 0.26 to 55.0 nmol/mg/min and a marked reduction in transfectant sensitivity to GSH-DXR to 1/120 (0.15-18 nM IC50) although the sensitivity to DXR was slightly decreased to 1/2.6 (380-990 nM IC50). By contrast, a high GST-pi-expressing human colon cancer cell line, HT29, showed a decrease in GST enzyme activity from 72.0 to 45.9 nmol/mg/min after transfecting GST-pi antisense cDNA and a marked improvement in transfectant sensitivity to GSH-DXR was observed (28-2.9 nM IC50) compared with the transfectant sensitivity to DXR (1020-320 nM IC50). Additionally, the expression of GST-pi in HepG2 cells caused a decrease in GSH-DXR-induced activation of caspase-3, which was an apoptotic marker, whereas the suppression of GST-pi in HT29 cells showed an increase in caspase-3 activation. These results suggested that the cytocidal efficacy of GSH-DXR, but not that of DXR, was controlled by the level of GST-pi expression in the cells.

Antineoplastic Agents↗
PubMed2001

Reversible brain dysfunction in MELAS: MEG, and (1)H MRS analysis.

This case report describes a follow up investigation of a patient with impaired word discrimination due to mitochondrial encephalopathy with lactic acidosis and stroke-like syndrome (MELAS) using proton magnetic resonance spectroscopy ((1)H MRS) and auditory evoked magnetic fields (AEFs). The initial (1)H MRS showed no N-acetyl aspartate (NAA) and marked accumulation of lactate (Lac) in the stroke-like lesion of MELAS, which was silent in neural activity according to AEFs. The follow up investigations, however, demonstrated that NAA reappeared, that the formerly increased Lac signal was significantly reduced, and that the magnitude of AEFs of the lesion was markedly increased. Metabolic and functional changes in (1)H MRS and AEFs reflected the neurological recovery very well. The stroke-like lesion was shown, using AEFs and (1)H MRS, to be able to function properly, although brain tissue of the lesion initially had severe damage due to mitochondrial dysfunction.

Adult↗
PubMed2001

Pancreatic islet blood flow in conscious rats during hyperglycemia and hypoglycemia.

Anesthesia affects general hemodynamics and regulation of organ perfusion. We used colored microspheres to measure pancreatic islet blood flow in conscious rats at two time points, during either hyperglycemia or hypoglycemia. This method, using black and green microspheres, was validated by comparison with previous microsphere experiments and by lack of effect of a nonmetabolizable glucose analog, 3-O-methylglucose, on islet perfusion. Basal and glucose-stimulated islet blood flow levels were similar in pentobarbital sodium-anesthetized and conscious rats. However, the basal distribution of pancreatic blood flow was altered by anesthesia (fractional islet blood flow 5.8 +/- 0.4% in conscious rats, 7.9 +/- 0.8% in pentobarbital-anesthetized rats, P < 0.05). Insulin-induced hypoglycemia significantly increased whole pancreatic blood flow in conscious rats, whereas islet blood flow remained unchanged and fractional islet blood flow was decreased (5.8 +/- 0.5% in the basal state, 4.2 +/- 0.4% during hypoglycemia, P < 0.001). Methylatropine pretreatment significantly increased islet blood flow during hypoglycemia by 181%. This result suggests that prevention of hypoglycemia-induced increase in islet perfusion may be mediated, at least in part, by a cholinergic, vagal muscarinic mechanism.

3-O-Methylglucose↗
PubMed2001

Experimental models of acute respiratory distress syndrome: clinical relevance and response to surfactant therapy.

Surfactant therapy for acute respiratory distress syndrome (ARDS) has shown encouraging results in animal studies, but not always in clinical trials. Efficacy of this therapy may be limited to ARDS caused by indirect injury, but mistiming of its application in clinical trials may be responsible for the discouraging results. In addition, the therapy may not last long enough to be effective. In rats with acidified milk aspiration, the effects of aerosolized surfactant therapy followed by inhalation of aerosolized dextran (molecular weight, 40,000) last significantly longer than those of aerosolized surfactant therapy alone. This mode of surfactant therapy could lead to better results since it can be started and repeated at any time.

Aerosols↗
PubMed2001

Influence of interleukin-10 on the interleukin-1 receptor antagonist/interleukin-1 beta ratio in the colonic mucosa of ulcerative colitis.

A decrease in the ratio of IL-1ra/IL-1 beta produced regionally by the colonic mucosa of patients with ulcerative colitis (UC) is believed to play a role in the pathogenesis of UC. To investigate factors influencing intramucosal IL-1ra/IL-1 beta ratios, we evaluated polymorphism of the IL-1ra gene and the production of mucosal cytokines in Japanese patients with UC. Colonic biopsy specimens of mucosal tissue were placed in organ cultures for 24 h. Then, the supernatant concentrations of IL-1 beta, IL-1ra, IL-8, IL-4, IL-10, and TGF-beta were assayed by ELISA. Genomic DNA was extracted from patient peripheral blood samples, then IL-1ra gene polymorphism was determined using PCR amplification. The mucosa from patients with active stage UC showed a tendency toward a decreased IL-1ra/IL-1 beta ratio. In the resolving stage, IL-1ra/IL-1 beta ratios increased with increasing IL-10 and TGF-beta concentrations. The addition of human recombinant IL-10 to the culture supernatants produced concentration-dependent inhibition of IL-1 beta. In Japanese patients with UC, the IL-1ra allele gene 2 phenotype had no effect on the IL-1ra/IL-1 beta ratio. Our findings suggest that a relative deficiency of IL-10 in patients with UC may contribute to persistent inflammatory changes.

Adult↗
PubMed2001

[A case of successful management of nonresectable pancreas cancer with liver metastasis by intra-arterial infusion chemotherapy with angiotensin-II and administration of tegafur/uracil].

Nontypical chemotherapy regimens exist for advanced pancreatic cancer. We herein report a 62-year-old man whose nonresectable pancreatic cancer was treated effectively with a new method of intra-arterial regional chemotherapy with angiotensin-II (AT-II). The patient was admitted to our hospital with obstructive jaundice and anorexia. He was diagnosed as having inoperable advanced pancreatic cancer with liver metastasis. Enteric-coated tegafur/uracil (400 mg) was administered for 3 weeks. Simultaneously, intraarterial infusion with 5-fluorouracil (500 mg) and infusion of methotrexate (100 mg) with 50 micrograms of AT-II was given every week. A catheter connected to a subcutaneously implanted port system was placed into the common hepatic artery. As a result of this treatment, the maximum diameter of the pancreatic tumor decreased from 3 cm to 2 cm on the CT-scan. Serum carbohydrate antigen 19-9 (CA19-9) decreased from 24,000 U/ml to 186 U/ml. Moreover, the performance status of patient also improved, and he was discharged from our hospital despite his terminal cancer. This regimen could well be effective in cases of advanced pancreatic cancer.

Angiotensin II↗
PubMed2001

[Study of functional rating scale for amyotrophic lateral sclerosis: revised ALSFRS(ALSFRS-R) Japanese version].

Amyotrophic lateral sclerosis(ALS) is progressive, degenerative, fatal disease of the motor neuron. No efficacious therapy is available to slow the progressive loss of function, but several new approaches including neurotrophic factors, antioxidants and glutamate antagonists, are currently being evaluated as potential therapies. Mortality, and/or time to tracheostomy, muscle strength and pulmonary function are used as primary endpoints in clinical trials for treatment of ALS. The effect of new therapies on the quality of patients' lives are also important, so we sought to develop a rating scale to measure it. The revised ALS Functional Rating Scale(ALSFRS-R), which has addition of items to ALSFRS to enhance the ability to assess respiratory symptoms, is an assessment determining the degree of impairment in ALS patients' abilities to function independently in activities of daily living. It consists of 12 items to evaluate bulbar function, motor function and respiratory function and each item is scored from 0(unable) to 4(normal). We translated the English score into Japanese one with minor modification considering the inter cultural difference. And we examined reliability of the translated scale. As a measure of reliability, the intraclass correlation coefficient(ICC) was evaluated for total score and the Kappa coefficient proposed by Cohen and Kraemer was calculated for each item. Moreover, we examined sensitivity to clinical change over time and carried out the factor analysis to analyze the factorial structure. The subjects were 27 ALS patients and each was scored twice for reliability or three times for sensitivity by 2 to 5 neurologists and if possible, nurses. The ICC for total score was 0.97(95% C. I.; 0.94-0.98). Extension of the Kappa coefficients were 0.48 to 1.00 for inter-rater reliability and the averaged Kappa coefficients were 0.63 to 1.00 for intra rater reliability, respectively. Concerning the factorial structure, the contribution of the first factor(the first principal component) were 53.5% principal factor solution. The factor loadings of items were 0.52-0.91 except "salivation" and this factor almost equal to the simple sum of all items was interpreted as the general degree of deterioration. The promax votation revealed the riginally supposed factor structure with 3 factors(groups of items): neuromuscuclar function, respiratory function and bulbar function. The rating scale correlated with Global clinical impression of change(GCIC) scored by neurologists and declined with time, indicating its sensitivity to change. On the bases of these results, ALSFRS-R(Japanese version) is considered to be highly reliable enough for clinical use.

Activities of Daily Living↗
PubMed2001

[Minimally invasive stereotactic functional surgery using an intravenous anesthetic propofol and applying Image Fusion and AtlasPlan].

Image-guided stereotactic surgery of the ventralis intermedius nucleus of the thalamus, globus pallidus, and subthalamic nucleus is a prevailing modality as a treatment of movement disorders. This technical note describes a method of minimally-invasive stereotactic functional surgery for patients with parkinsonian symptom or various tremors. Patients were administered propofol, an intravenous anesthetic, during placement of a burr hole and a stereotactic frame, but not the period when the patients were necessary to be awake. The intravenous anesthesia was very beneficial to relieve local pain and mental stress of the patients. Radionics ImageFusion and AtlasPlan were used for defining the target localization without an intraoperative ventriculography. ImageFusion efficiently fused high-resolution MR images on CT images. AtlasPlan accurately corrected the localization of the tentative target point after measurements from the midpoint of the anterior commissure-posterior commissure line on the modified MRI, and enabled us to reduce the degree of an intraoperative correction to fix a final target. Stereotactic functional surgery has been thought to be less-invasive, however further modifications of surgical procedure and intraoperative medication can make this type of surgery much more less-invasive.

Anesthesia, Intravenous↗
PubMed2001

[A case of nonresectable scirrhous type gastric cancer treated by hypertensive subselective chemotherapy with pharmacokinetic modulating chemotherapy].

There have been few effective chemotherapeutic regimens for scirrhous type gastric cancer. A 62-year-old male patient was admitted to our hospital because of anorexia and abdominal discomfort. Gastroendoscopy showed a type 4 advanced gastric cancer in the upper gastric body. Histologic study of biopsy specimens from the tumor revealed poorly differentiated adenocarcinoma. Examination by computed tomography and ultrasonography revealed swollen paraaortic lymph nodes and peritonitis carcinomatosa. The patient was diagnosed as having a nonresectable scirrhous type gastric cancer with peritonitis carcinomatosa and paraaortic lymph node metastasis. This patient was treated weekly with an intraarterial 5-FU (500 mg) and MTX (100 mg) including AT-II by a subcutaneously implanted port system placed into the thoracic aorta. Furthermore, he was administered tegafur/uracil (400 mg/day) 5 days weekly as a pharmacokinetic modulating chemotherapy (PMC). After eight courses of treatment of PMC, paraaortic lymph node swelling and ascites decreased. This chemotherapy produced a partial response in the peritonitis carcinomatosa and paraaortic lymph nodes. This chemotherapy was repeated preoperatively. We reconsidered this case to show indications for operation. The patient died suddenly of acute heart failure before the operation. This therapy was considered an effective treatment for nonresectable gastric cancer.

Adenocarcinoma, Scirrhous↗