Biomedical subjects

Takahiro Seno

Publications and source records attributed to Takahiro Seno.

7 recordsLinked to original sources

PubMed2006

Experimental study on stability of a high-porosity expanded polytetrafluoroethylene graft in dogs.

PURPOSE: The purpose of the present study was to evaluate the stability of a high-porosity expanded polytetrafluoroethylene (ePTFE) graft, which has been shown to possess excellent biocompatibility and tissue integration. METHODS: The graft used in the present study was a high-porosity ePTFE graft , which had an average internodal distance of approximately 60 microm and a random node architecture with tortuous path channels extending from the outer to the inner surface. Eleven beagle dogs (each group n = 3 or 4) weighing 10-12 kg were used. The graft, with a 6 mm inside diameter and a 30-40 mm length, was implanted into the canine abdominal aorta and retrieved after 2-80 weeks. The deformation of the graft was evaluated by conventional computed tomography (CT). The radial tensile strength, longitudinal tensile strength, and suture retention strength of the graft were measured after 2-80 weeks. RESULTS: CT studies showed no anastomotic aneurysm or deformation of the graft. Physical tests demonstrated no significant deterioration in suture retention strength, radial tensile strength or longitudinal tensile strength for periods ranging from 2-80 weeks compared to pre-implantation grafts. CONCLUSION: The graft possesses adequate stability that ensures safe and effective clinical use.

Animals↗

PubMed2005

Anesthetic and cardiovascular effects of balanced anesthesia using constant rate infusion of midazolam-ketamine-medetomidine with inhalation of oxygen-sevoflurane (MKM-OS anesthesia) in horses.

The anesthetic sparring and cardiovascular effects produced by midazolam 0.8 mg/ml-ketamine 40 mg/ml-medetomidine 0.05 mg/ml (0.025 ml/kg/hr) drug infusion during sevoflurane in oxygen (MKM-OS) anesthesia was determined in healthy horses. The anesthetic sparring effects of MKM-OS were assessed in 6 healthy thoroughbred horses in which the right carotid artery was surgically relocated to a subcutaneous position. All horses were intubated and ventilated with oxygen using intermittent positive pressure ventilation (IPPV). The end-tidal concentration of sevoflurane (ET(SEV)) required to maintain surgical anesthesia was approximately 1.7%. Heart rate and mean arterial blood pressure averaged 23-41 beats/min and 70-112 mmHg, respectively. All horses stood between 23-44 min after the cessation of all anesthetic drugs. The cardiovascular effects of MKM-OS anesthesia were evaluated in 5 healthy thoroughbred horses ventilated using IPPV. Anesthesia was maintained for 4 hr at an ET(SEV) of 1.7%. Each horse was studied during left lateral (LR) and dorsal recumbency (DR) with a minimum interval between evaluations of 1 month. Cardiac output and cardiac index were maintained between 70-80% of baseline values during LR and 65-70% of baseline values during DR. Stroke volume was maintained between 75-85% of baseline values during LR and 60-70% of baseline values during DR. Systemic vascular resistance was not different from baseline values regardless of position. MKM-OS anesthesia may be useful for prolonged equine surgery because of its minimal cardiovascular depression in both of lateral and dorsal recumbency.

Anesthesia, Inhalation↗

PubMed2005

Axial correction of pes varus by transverse-opening wedge osteotomy and T-plate fixation with beta-tricalcium phosphate (beta-TCP) transplantation in dachshunds.

Axial correction was performed surgically in two miniature dachshunds presenting with lateral patellar dislocation and limping caused by pes varus. Pes varus had resulted from asymmetric closure of the physis of the distal tibia. Prior to surgery, osteotomy was simulated by measuring X-ray films to determine the distance required for the wedge opening. Transverse-opening wedge osteotomy was performed on the medial side of the distal tibia, and beta-tricalcium phosphate (beta-TCP) was inserted in a wedge shape into the area created by the cuneiform osteotomy. Finally, the tibia was fixed by a veterinary 1.5/2.0-mm T-plate. Both dogs were able to walk a few days after surgery, and the lateral dislocation of the patella normalized almost completely in about one month. At two months, X-ray films showed that the implant had remained in position without any dislocation, and the beta-TCP had fused with the surrounding bone.

Animals↗

PubMed2005

Electroretinography using contact lens electrode with built-in light source in dogs.

Electroretinography (ERG) is an effective method for the diagnosis of retinal disease. In the dog, dependable ERG recording is difficult without the use of an expensive device like a Ganzfeld full-field stimulator. The International Society for Clinical Electrophysiology of Vision has defined the standard flash stimulus condition (SF) and evaluation of the retina using the b/a ratio in humans. In dogs, evaluation using the b/a ratio has not been reported, whereas the intensity of SF has been defined. In this study, we performed a convenient ERG recording method using a contact lens electrode with a built-in light source (LED-electrode), and confirmed SF as reported previously. ERG recordings were performed on 15 healthy beagle dogs under sedation. We performed bilateral ERG at 12 different intensities after 30 min dark adaptation. After 10 min light adaptation, we recorded single flash cone and flicker cone response using the SF determined in this study. In this study, SF of 3.0 cd/m(2)/sec (6,000 cd/m(2), 0.5 msec) resulted in b/a=2. The intensity for rod response that recorded only the b-wave was 0.0096 cd/m(2)/sec (80 cd/m(2), 0.12 msec). We could achieve ERG for each response easily and smoothly under sedation, and without general anesthesia. Using an LED-electrode, we could perform more quantitative and reproducible ERG examinations than with traditional methods. We propose that the b/a ratio is the most useful parameter in ERG reporting for evaluating retinal function.

Animals↗

PubMed2004

Fixation to the canine bone of artificial implant with new surface structure.

Screw and laser (SL) column by making screw threads and forming small holes using laser irradiation on the base metal and conventional beads coating (BC) columns were embedded into the shaft of canine femurs, and compared the implant fixation to the host bone. The interfacial strength in SL columns was almost equivalent as BC columns, and bone-column contact rate was higher than BC columns significantly at twelve weeks after implantation. The newly devised SL surface had almost equivalent bone fixation strength comparable to the conventional BC surface. Also, this surface should provide a useful porous surface for use in artificial joints since there is no risk of surface structure detachment.

Animals↗

PubMed2003

The interfacial strength in sputtering-hydroxyapatite-coating implants with arc-deposited surface.

Titanium columns (Ti-6A1-4V) were treated with arc-deposition to roughen the surface enough to anchor the bone, and then coated with hydroxyapatite (HA) at a thickness of 5 micro m by the sputtering technique. Columns were implanted into dog femurs, and fixation of columns to bone due to bone-ingrowth was assessed histologically and with the push-out test. The HA-coated columns were inserted in the shafts of the right femurs of 2 dogs. As a control, columns that were only arc-deposited (non-coated columns) were inserted into the left femurs. The interfacial strength was higher for the HA-coated columns than for the non-coated columns. Coating a rough surface with an HA layer using a sputtering technique reinforces interfacial strength between bone and implants.

Animals↗

PubMedDate not supplied

Detection of cone dysfunction induced by digoxin in dogs by multicolor electroretinography.

It is difficult to detect discrete cone function with the present conventional electroretinography (ERG) examination. In this study, we developed contact electrodes with a built-in color (red (644 nm), green (525 nm), or blue (470 nm)) light source (color LED-electrode), and evaluated an experimental model of digoxin in the dog. First, 17 normal Beagle dogs were used to determine which electrode works well for color ERG measurement on dogs. Then, color ERG was performed on seven normal Beagle dogs at various points during a 14-day period of digoxin administration. A single daily dose of 0.0125 mg/kg/day, which is within the recommended oral maintenance dosage range for dogs, was administered orally for 2 weeks. Ophthalmic examination, measurement of plasma concentration of digoxin, and color ERG examination were performed. On first examination, amplitudes of all responses were significantly (P < 0.01) lower with the red, than with the blue and green electrodes during ERG recording. In ERG using the red electrode, the standard deviation was large. According to these preliminary results, the red electrode was not used in the experimental dog model with digoxin. In the digoxin administrated animals, no significant change was observed in the ophthalmic examination findings. The digoxin level increased steadily throughout the dosing period but was always within the therapeutic range for dogs. In rod ERG, no abnormalities were detected with any electrode. In standard combined ERG, decreased amplitude of the a-wave was detected with every electrode. In single flash cone ERG, prolongation of implicit time was detected by color ERG with the blue and green electrodes. In 30-Hz flicker ERG, decreased amplitude was detected only by color ERG with the blue electrode. The decreased amplitude and prolonged implicit time recovered after termination of digoxin administration. Cone dysfunction induced by digoxin in the dog was revealed by multicolor ERG using blue and green LED-electrodes. Multi-color ERG was useful for detecting cone type-specific dysfunction in the dog.

Administration, Oral↗