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Biomedical subjects

E Tamura

Publications and source records attributed to E Tamura.

At least 19 recordsLinked to original sources
PubMed2001

A 2.3 to 25 keV XAS beamline at LNLS.

The LNLS XAS beamline has been operating for external users since July 1997. Many facilities and improvements have been progressively added to it, extending the range of applications. Here, a technical description of the main beamline components is given, and results concerning important points, such as available flux at low and high energies, harmonic contamination, energy resolution and stability, are presented. Some key results are given to demonstrate the beamline performance and limitations. It is shown that the beamline can cover a large energy range, starting from the rather low energy of 2.3 keV up to 25 keV.

Journal Article↗
PubMed2001

A multiwire proportional counter for XAS fluorescence experiments.

A multiwire proportional counter was used in fluorescence X ray absorption measurements and a comparison to a Si(Li) and NaI(Tl) detectors was done. The main features of the multiwire proportional counter are its high counting rate capability (10(7)) counts x s(-1)) and large active area (6 x 6 cm2). It was shown that the MWPC is suitable for fluorescence absorption. Although the maximum capability was not reached in the present experiments, it was found that as the counting rate increase the MWPC performance became better than Si(Li) detectors and shows a similar response to the scintillator counter at medium counting rates (up to 10(5) counts x s(-1)).

Journal Article↗
PubMed2001

Clinical assessment of intralaryngeal ultrasonography.

OBJECTIVES: To assess the clinical use of intralaryngeal ultrasonography. STUDY DESIGN: A retrospective study was conducted of 16 patients with laryngeal lesions treated by laryngomicrosurgery. METHODS: An intraluminal ultrasonic tomography apparatus was connected to a radial scanning 30-MHz miniaturized probe. Under general anesthesia, ultrasonic images were obtained using the filling method. RESULTS: In cases of benign disease, such as vocal cord nodules or polyps, the layers of the mucosa could be identified. Characteristic internal echoes were noted in cases of hemorrhagic polyps, vocal cord cysts, and vocal cord cancer. In case of hemorrhagic polyps, hyperechoic regions were noted within the lesions. In cases of vocal cord cysts, internal echoes were absent, and posterior echoes were mildly enhanced. In cases of vocal cord cancer, infiltration beyond the mucosa could be visualized. CONCLUSIONS: Laryngeal lesions can be diagnosed by intralaryngeal ultrasonography using the filling method. Although it does not replace the combination of conventional endoscopy and a critical evaluation of the clinical symptoms of the individual disease, it can profitably complement them. Intralaryngeal ultrasonography can help in determining the extent of tumor involvement during microscopic laser surgery performed under general anesthesia. Confirmation of the results of this pilot study with a larger series of patients is desirable.

Adult↗
PubMed2000

Blood-brain barrier is involved in the efflux transport of a neuroactive steroid, dehydroepiandrosterone sulfate, via organic anion transporting polypeptide 2.

We have investigated the transport characteristics of dehydroepiandrosterone sulfate (DHEAS), a neuroactive steroid, at the blood-brain barrier (BBB) in a series of functional in vivo and in vitro studies. The apparent BBB efflux rate constant of [(3)H]DHEAS evaluated by the brain efflux index method was 2.68 x 10(-2) min(-1). DHEAS efflux transport was a saturable process with a Michaelis constant (K:(m)) of 32.6 microM: Significant amounts of [(3)H]DHEAS were determined in the jugular venous plasma by HPLC, providing direct evidence that most of the DHEAS is transported in intact form from brain to the circulating blood across the BBB. This efflux transport of [(3)H]DHEAS was significantly inhibited by common rat organic anion-transporting polypeptide (oatp) substrates such as taurocholate, cholate, sulfobromophthalein, and estrone-3-sulfate. Moreover, the apparent efflux clearance of [(3)H]DHEAS across the BBB (118 microl/min-g of brain) was 10.4-fold greater than its influx clearance estimated by the in situ brain perfusion technique (11.4 microl/min-g of brain), suggesting that DHEAS is predominantly transported from the brain to blood across the BBB. In cellular uptake studies using a conditionally immortalized mouse brain capillary endothelial cell line (TM-BBB4), [(3)H]DHEAS uptake by TM-BBB4 cells exhibited a concentration dependence with a K:(m) of 34.4 microM: and was significantly inhibited by the oatp2-specific substrate digoxin. Conversely, [(3)H]digoxin uptake by TM-BBB4 cells was significantly inhibited by DHEAS. Moreover, the net uptake of [(3)H]DHEAS at 30 min was significantly increased under ATP-depleted conditions, suggesting that an energy-dependent efflux process may also be involved in TM-BBB4. RT-PCR and sequence analysis suggest that an oatp2 is expressed in TM-BBB4 cells. In conclusion, DHEAS efflux transport takes place across the BBB, and studies involving in vitro DHEAS uptake and RT-PCR suggest that there is oatp2-mediated DHEAS transport at the BBB.

Animals↗
PubMed2000

[Concurrent chemoradiotherapy for locally unresectable head and neck cancer].

In patients with locally unresectable head and neck cancer with large nodal involvement, the expected five-year survival is as low as 1-2%. To improve the prognosis of these patients, we studied the usefulness of concurrent chemoradiotherapy in a phase II trial. Between September 1996 and May 1999, thirty-five patients with locally unresectable head and neck cancer were administered concurrent chemoradiotherapy consisting of low-dose and long-term treatment with cisplatin (CDDP) plus 5-fluorouracil (5FU), or (L-CF); the L-CF regimen consisted of CDDP, 3 mg/m2 on 5 days of the week and 5FU, 150 mg/m2 as a 24-hour infusion on 5 days of the week. Concurrently, conventional radiotherapy was given up to total dose of around 60 Gy. In the 33 patients evaluable for response, 17 complete and 9 partial responses were noted, with an overall response rate of 79%. Oral mucostis and myelosuppression were the major side effects and mucositis was a dose limiting toxicity. This study demonstrates increase in survival among the responders (complete + partial) in the concurrent chemoradiotherapy setting. However 8 local relapses were eventually noted in the 17 complete responders. We concluded that this treatment strategy was beneficial in patients with locally unresectable head and neck cancer.

Adult↗
PubMed2000

The role of low dose cisplatin plus 5-fluorouracil for treatment of recurrent and/or advanced squamous cell carcinoma of the head and neck.

To improve survival rate in advanced head and neck cancer, we scheduled 90 patients to receive low dose cisplatin plus 5-fluorouracil regimen as neoadjuvant(NAC), concurrent(CC), adjuvant(AC), and second line chemotherapy (SC) setting. Our regimen consisted of cisplatin (CDDP 5 mg/m2/1 hr infusion on days 1-5, 8-12, 15-19, 22-26) and 5-fluorouracil (5-FU 200 mg/m2/24 hr infusion or oral administration of tegaful-uracil (UFT-E) 400 mg/body on days 1-28). The concurrent chemoradiotherapy consisted of conventional irradiation with 1.6-2.0 Gy/day on five days per week up to a total dose around 60Gy, and CDDP 3 mg/m2 by intravenous infusion over 1 hour plus 5-FU 150 mg/m2 by intravenous infusion over 24 hours per day on five days per week. For SC, 24 patients evaluable for response, 4 CR and 6 PR with RR of 42% were achieved. For NAC, 14 patients were evaluated for response, 2 CR and 7 PR were achieved. CC was indicated for locally unresectable cases. Of the 33 patients evaluable for response were 17 CR and 9 PR with RR of 79%. Dose limiting toxicities for chemotherapy were anemia and leukopenia and chemoradiotherapy was mucositis. Our treatment modality showed marginal toxicity and good response. Moreover, our regimen could be given in an outpatient setting safely so quality of life for patients was identical. We concluded that for advanced head and neck cancer, these treatment options were effective for second line and adjuvant setting. Chemoradiotherapy with this regimen also gave a impact for improving local control and survival period for locally unresectable cases.

Adult↗
PubMed1999

A skin blister method to study epidermal nerves in peripheral nerve disease.

Skin is a reservoir of sensory and autonomic nerve fibers that are potential indicators of peripheral nerve disease. Biopsies of skin have shown that sensory nerves in the most superficial layer of skin, the epidermal nerve fibers (ENFs), are reduced in patients with polyneuropathy. This report describes a minimally invasive skin blister method to isolate, image, and obtain quantitative analysis of ENFs. Blisters are made by applying a suction capsule to skin. The epidermal roof of the blister is excised, immunostained, whole mounted, and analyzed for ENF number and distribution. A reduction in number and abnormal distribution of ENFs are early indicators of peripheral nerve disease. Illustrations of skin blister and skin biopsy specimens from patients with different types of peripheral nerve disorders are included. These patients were chosen because their findings demonstrate the complementary information obtained by the blister and biopsy methods and the potential of the blister procedure to evaluate single nerve lesions and polyneuropathy and to follow the progress of ENF degeneration and regeneration.

Adult↗
PubMed1999

[Clinicopathological evaluation of intralaryngeal ultrasonography].

We used a miniature ultrasonic probe to study its diagnostic application in the detection of laryngeal lesions. Using the immersion method and an extracted human larynx, we evaluated ultrasonic images, identified the layered structure of vocal folds, and examined clinical cases following the study of diagnostic application. By the immersion method, ultrasonic images revealed that the membranous vocal fold was separated into three layers. We identified the histological structures of these three layers by comparing the ultrasonic images with the corresponding histologies. The first layer (hyperechoic) was the epithelial and the superficial layer of the lamina propria; the second layer (hypoechoic) was the vocal ligament; and the third layer (hyperechoic) was the deep layer of the lamina propria. On the basis of this study, we then evaluated ultrasonographic images of clinical cases. Benign lesions such as vocal nodules or vocal polyps were noted on the layered structure of the mucosa, especially, polyps as hyperechoic images. Furthermore, glottic cancer lesions demonstrated hypoechoic images and sometimes revealed destruction of the layered structures. These results suggest that intralaryngeal ultrasonography can be useful as a clinical application for the detection of tumor involvement in the vocal folds.

Aged↗
PubMed1995

[Effects of transcutaneous silicon injection for aspiration caused by unilateral vocal cord paralysis].

The purpose of this study was to determine the effects of transcutaneous silicon injection on swallowing function in unilateral vocal cord paralysis with aspiration. The preoperative and postoperative swallowing function were evaluated by means of videofluoroscopy and pharyngeal manometry in eight patients who received injection of silicon into the laryngeal vestibule, ventricle and vocal cord. Data analysis compared 1) types of aspiration and pharyngeal clearance, 2) timing of laryngeal closure (complete closure between arytenoid and epiglottic base) that was correlated with the onset of cricopharyngeal (CP) opening as time zero, and 3) swallowing pressure in the pyriform sinus on the side of the paralyzed vocal cord. In seven of the 8 patients, a favorable clinical response was achieved and aspiration and/or penetration were not observed on the fluoroscopic images after the silicon injection. Timing of laryngeal closure could be quantified in six patients, and mean values of the times preceding the onset of CP opening were significantly earlier on the postoperative examinations than preoperative examinations. Pharyngeal clearance on the affected vocal cord side was improved in six of the 8 patients, and swallowing pressure in the pyriform sinus was significantly elevated in four patients following surgery. These results suggested that silicon injection therapy produced earlier laryngeal closure during the swallow and improvement of pharyngeal clearance on the affected side after the swallow, so that aspiration and/or penetration with vocal cord paralysis might be prevented.

Aged↗
PubMed1994

Severe radicular pathology in rats with longstanding diabetes.

There few pathological abnormalities in nerves from animals with diabetes. Reported changes consist of mild distal axonal atrophy, axoglial disjunction and minimal segmental demyelination and remyelination. These changes are seen in distal nerves but no studies of radicular pathology in diabetic animals have been reported. We therefore studied peripheral nerve and radicular pathology in rats with longstanding, severe, chemically-induced diabetes. We found marked interstitial edema and severe changes of myelin in the roots of diabetic rats, particularly in the dorsal root. The earliest changes consist of myelin splitting, occurring at the intraperiod line. This progresses to myelin ballooning, accompanied by both tubulovescicular myelin degeneration and macrophage stripping, all of which tend to predominate in large myelinated fibers. There is minimal axonal degeneration. Despite these severe changes in nerve roots, the distal peripheral nerves show no discernible edema and only minimal myelin splitting without demyelination or axonal degeneration. The radicular changes are almost identical to those seen in much older nondiabetic animals. This suggests that they may represent an acceleration of the normal aging process, perhaps related to increased glycation of myelin proteins induced by accumulation of glucose rich interstitial endoneurial edema.

Animals↗
PubMed1992

Endoneurial blood supply to peripheral nerves is not uniform.

Peripheral nerves are not uniformly susceptible to the effects of ischemia in human and experimental ischemic neuropathies. Since endoneurial blood flow is directly proportional to the number of endoneurial capillaries, we studied endoneurial capillary density at multiple levels of the peripheral nerves of normal rats. Capillary density was lowest in the sciatic and proximal tibial nerves and significantly higher in dorsal and ventral roots and distal tibial and plantar nerves. Endoneurial capillary density corresponds to the hierarchy of susceptibility to ischemic nerve damage in human and experimental ischemic neuropathies. These findings suggest that susceptibility of peripheral nerves to ischemia is determined, at least in part, by the density of endoneurial capillaries.

Animals↗