Biomedical subjects

Shinichi Yamamoto

Publications and source records attributed to Shinichi Yamamoto.

5 recordsLinked to original sources

PubMed2006

Brachial plexus injury: clinical manifestations, conventional imaging findings, and the latest imaging techniques.

Brachial plexus injury (BPI) is a severe neurologic injury that causes functional impairment of the affected upper limb. Imaging studies play an essential role in differentiating between preganglionic and postganglionic injuries, a distinction that is crucial for optimal treatment planning. Findings at standard myelography, computed tomographic (CT) myelography, and conventional magnetic resonance (MR) imaging help determine the location and severity of injuries. MR imaging sometimes demonstrates signal intensity changes in the spinal cord, and enhancement of nerve roots and paraspinal muscles at MR imaging indicates the presence of root avulsion injuries. New techniques including MR myelography, diffusion-weighted neurography, and Bezier surface reformation can also be useful in the evaluation and management of BPI. MR myelography with state-of-the-art technology yields remarkably high-quality images, although it cannot replace CT myelography entirely. Diffusion-weighted neurography is a cutting-edge technique for visualizing postganglionic nerve roots. Bezier surface reformation allows the depiction of entire intradural nerve roots on a single image. CT myelography appears to be the preferred initial imaging modality, with standard myelography and contrast material-enhanced MR imaging being recommended as additional studies. Work-up will vary depending on the equipment used, the management policy of peripheral nerve surgeons, and, most important, the individual patient.

Brachial Plexus↗

PubMed2004

Continuous spinal anesthesia and postoperative analgesia for elective cesarean section in a parturient with Eisenmenger's syndrome.

We describe the use of continuous spinal anesthesia (CSA) for an elective cesarean section in a 29-year-old parturient with Eisenmenger's syndrome at 30 weeks of gestation. It is essential in patients with Eisenmenger's syndrome to prevent significant increases in right-to-left shunt following the reduction in systemic vascular resistance. In this case, the patient hoped to be awake during the operation because of her fear of death. We therefore applied CSA to this patient because single-shot spinal anesthesia and epidural anesthesia might cause sudden cardiovascular depression. In fact, sudden cardiovascular changes were avoided by the titration of local anesthetics and the operation was uneventful, although prompt treatment of hypotension was essential and adjustment of the anesthetic levels was difficult. Postoperative patient-controlled spinal analgesia provided satisfactory pain relief with hemodynamic stability and no significant side effects. However, thorough experience with the requisite techniques is critical in CSA because of the technical difficulty of the procedure, and anesthesiologists must gain such experience in less-demanding cases before attempting to administer it in patients presenting extreme challenges as described in this case report.

Adult↗

PubMed2003

Enhancement of the endotoxin recognition pathway by ventilation with a large tidal volume in rabbits.

Ventilation with a small tidal volume (V(t)) is associated with better clinical outcomes than with a large V(t), particularly in critical settings, including acute lung injury. To determine whether V(t) influences the lipopolysaccaharide (LPS) recognition pathway, we studied CD14 expression in rabbit lungs and the release of TNF-alpha by cultured alveolar macrophages after 240 min of ventilation with a large (20 ml/kg) vs. a small (5 ml/kg) V(t). We also applied small or large V(t) to lungs instilled with 50 microg/kg of LPS. The alveolar macrophages collected after large V(t) ventilation revealed a 20-fold increase in LPS-induced TNF-alpha release compared with those collected after small V(t) ventilation, whereas TNF-alpha was undetectable without LPS stimulation. In animals ventilated with a large V(t), the expression of CD14 mRNA in whole lung homogenates and the expression of CD14 protein on alveolar macrophages, assessed by immunohistochemistry, were both significantly increased in the absence of LPS stimulation. A large V(t) applied to LPS-instilled lungs increased the pulmonary albumin permeability and TNF-alpha release into the plasma. These results suggest that mechanical stress caused by a large V(t) sensitizes the lungs to endotoxin, a phenomenon that may occur partially via the upregulation of CD14.

Albumins↗

PubMed2003

[The use of milrinone in a patient with mitral regurgitation and severe pulmonary hypertension: a case report].

A 65-year-old female with mitral regurgitation was scheduled for the mitral valve surgery. However, because of the severe pulmonary hypertension, the patient needed evaluation on the reversibility of pulmonary hypertension and the safety of the surgical procedure. Milrinone, a phosphodiesterase inhibitor with vasodilating and positive inotropic properties, known to lower pulmonary vascular resistance was administered to the patient. Milrinone showed a prompt decrease of pulmonary artery pressure and an increase of cardiac output, and the cardiac surgery was performed uneventfully. It is considered that milrinone is useful in lowering pulmonary vascular resistance and assessing the reversibility of pulmonary hypertension in patients with severe pulmonary hypertension undergoing cardiac surgery.

Aged↗

PubMed2002

A comprehensive rice transcript map containing 6591 expressed sequence tag sites.

To determine the chromosomal positions of expressed rice genes, we have performed an expressed sequence tag (EST) mapping project by polymerase chain reaction-based yeast artificial chromosome (YAC) screening. Specific primers designed from 6713 unique EST sequences derived from 19 cDNA libraries were screened on 4387 YAC clones and used for map construction in combination with genetic analysis. Here, we describe the establishment of a comprehensive YAC-based rice transcript map that contains 6591 EST sites and covers 80.8% of the rice genome. Chromosomes 1, 2, and 3 have relatively high EST densities, approximately twice those of chromosomes 11 and 12, and contain 41% of the total EST sites on the map. Most of the EST-dense regions are distributed on the distal regions of each chromosome arm. Genomic regions flanking the centromeres for most of the chromosomes have lower EST density. Recombination frequency in these regions is suppressed significantly. Our EST mapping also shows that 40% of the assigned ESTs occupy only approximately 21% of the entire genome. The rice transcript map has been a valuable resource for genetic study, gene isolation, and genome sequencing at the Rice Genome Research Program and should become an important tool for comparative analysis of chromosome structure and evolution among the cereals.

Chromosome Mapping↗