Biomedical subjects

Atsuo Yamada

Publications and source records attributed to Atsuo Yamada.

3 recordsLinked to original sources

PubMed2006

A randomized controlled trial evaluating the usefulness of a transparent hood attached to the tip of the colonoscope.

OBJECTIVES: Considering the increasing demand for colonoscopy, auxiliary devices that could facilitate the examination would be useful. A hood attached to the tip of the colonoscope has been reported to be helpful in detecting and removing colorectal polyps. However, its usefulness in aiding scope intubation has not been fully evaluated. METHODS: Patients for colonoscopy between July 2004 and May 2005 in Tokyo University Hospital were enrolled to this randomized controlled trial, and assigned to colonoscopy with a transparent hood, a short hood, or no hood. Colonoscopies were conducted by trainees without sedation. The evaluated outcomes were cecal intubation rate, trainee intubation rate (cecal intubation within 15 min), cecal intubation time, and polyp detection rate. RESULTS: Enrolled 684 patients were randomly assigned to transparent hood (N = 221), short hood (N = 228), and no hood (N = 235) groups. The overall cecal intubation rate was 95.3% (652/684) and did not differ among the groups. The overall trainee intubation rate was 55.1% (377/684) and significantly higher in the transparent hood group than in the no hood group for female patients (60.7%vs 37.4%, P = 0.003). Cecal intubation time was 11.5, 13.5, and 14.0 min in the transparent, short, and no hood groups, respectively, and significantly shorter in the transparent hood group than in the no hood group among overall (P = 0.008), female (P = 0.001), and old (P = 0.04) patients. Polyp detection rate was higher in the transparent hood group than in the no hood group (49.3%vs 39.1%, P = 0.04). CONCLUSIONS: The transparent hood was useful in shortening the cecal intubation time especially in difficult cases.

Clinical Competence↗

PubMed2006

Room-temperature miscibility gap in LixFePO4.

The rechargeable lithium-ion cell is an advanced energy-storage system. However, high cost, safety hazards, and chemical instability prohibit its use in large-scale applications. An alternative cathode material, LiFePO(4), solves these problems, but has a kinetic problem involving strong electron/hole localization. One reason for this is believed to be the limited carrier density in the fixed monovalent Fe(3+)PO(4)/LiFe(2+)PO(4) two-phase electrode reaction in LixFePO4. Here, we provide experimental evidence that LixFePO4, at room temperature, can be described as a mixture of the Fe(3+)/Fe(2+) mixed-valent intermediate LialphaFePO4 and Li1-betaFePO4 phases. Using powder neutron diffraction, the site occupancy numbers for lithium in each phase were refined to be alpha=0.05 and 1-beta=0.89. The corresponding solid solution ranges outside the miscibility gap (0<x<alpha,1-beta<x<1) were detected by the anomaly in the configurational entropy, and also by the deviation of the open-circuit voltage from the constant equilibrium potential. These findings encourage further improvement of this important class of compounds at ambient temperatures.

Journal Article↗

PubMed2005

[Syndrome of inappropriate secretion of antidiuretic hormone (SIADH) associated with relapsing multiple sclerosis].

We report a 47-year-old man with multiple sclerosis (MS) with previous history of recurrent sensorimotor disturbance and visual deficit. The patient developed bilateral motor weakness in the upper limbs, and systemic malaise. An administration of 20 mg/day of prednisolone was ineffective for his symptoms and he complained dyspnea a week later. On admission, his clinical findings included brainstem dysfunction with optic nerve atrophy, motor disturbance in the bilateral upper limbs, hyperreflexia, and superficial sensory disturbance. Biochemical examination revealed marked reduction in serum Na (117 mEq/l) and C1 (85 mEq/l) with increased urinary Na excretion. Although his plasma osmotic pressure decreased to 233 mOsm/kg, urinary osmotic pressure increased to 409 mOsm/kg. Serum antidiuretic hormone (ADH) concentration was 26.1 pg/ml and plasma renin activity was 0.1 ng/ml/ hour. Renal function and adrenal function were normal. Cerebrospinal fluid contained increased protein concentration, IgG, and myelin basic protein. Syndrome of inappropriate secretion of antidiuretic hormone (SIADH) associated with MS was diagnosed. Intravenous Na infusion with restricted supplemental fluid and serial administration of methylprednisolone (1,000 mg/day for three days) improved his neurological abnormalities and normalized his serum serum Na level and plasma osmotic pressure. This suggests that demyelinating lesions in the hypothalamus due to MS may cause the transient increased ADH secretion.

Brain↗