Biomedical subjects
Publications and source records attributed to S Kazama.
An aortic valve replacement was successfully performed employing the Nicks annulus enlargement procedure in a case of aortic valve stenosis with small annulus 12 years after mitral valve replacement. Previous mitral valve replacement does not preclude feasibility of the Nicks procedure.
A new reversed-direction scissors design was developed to facilitate the coronary artery incising procedure during bypass surgery. These scissors consist of a blade which is curved 180 degrees sideways in relation to the longitudinal axis of the handle. Also the blade portion is directed downward by about 20 degrees against the horizontal axis of the handle portion. It is important to note that when these scissors are used to make an incision in the coronary artery, the handles do not obstruct the surgeon's view of the blades and the coronary artery. It is also to be noted that the surgeon's arm holding these scissors can stay as low as when using regular straight scissors. Therefore, reversed-direction incisions of the coronary artery can be performed accurately and comfortably with these new scissors.
A new device comprising a set of graded aorta sizers is presented. Each sizer consists of a disc mounted on the top a straight holder. The length of each holder equals the circumference of its disc (the length of the holder equals the diameter of the disc times 3.14). The size of the discs are graded by 2 mm from 24 mm to 36 mm in diameter. In aneurysm operations, the proper-size vascular graft is selected by sizing the diameter of the transected aorta with the disc portion of a sizer. The proper length of the reinforcing felt strip is then determined by the length of the holder portion of the appropriate sizer.
Nitric oxide (NO) generation from a spin trap, N-tert-butyl-alpha-phenylnitrone (PBN) under various oxidative conditions was examined. The absorbance of PBN at 295 nm decreased with time of UV-irradiation, showing that PBN was decomposed by UV irradiation. The hydroxyl radical formed from a Fenton reagent also decomposed PBN, but there was little effect by a peroxyl radical and a superoxide. Nitrite, an oxidative product of NO, in PBN solution was determined using a NOx analyzer based on Griess reaction. UV-irradiation and the hydroxyl radical also formed nitrite. Direct detection of NO from the sample on reaction with hydroxyl radical was successful using a GC/MS/SIM on the UV-irradiated sample. NO generated in PBN solutions activated guanylate cyclase. From these results, PBN is viewed as a new kind of medicine which acts as an antioxidant and as an NO donor in vivo.
OBJECTIVE: To examine whether Mycoplasma hyorhinis inoculated into the tympanic cavity can cause otitis media in pigs. ANIMALS: 17- or 22-day-old specific-pathogen-free pigs. PROCEDURE: Histologic and bacteriologic examinations were performed on specimens from the tympanic cavity and auditory tube at 0, 7, 14, and 25 days after intratympanic inoculation of M hyorhinis (auditory tube cloning strain 14). RESULTS: In M hyorhinis-inoculated pigs, mild to moderate inflammation of the auditory tube and tympanic cavity first appeared at postinoculation day (PID) 7. In pigs euthanatized at PID 14, the degree of inflammation was aggravated. Immunohistochemical analysis revealed M hyorhinis antigens on the luminal surface of the auditory tube and tympanic cavity. By PID 25, lesions had lessened. By use of transmission and scanning electron microscopic examinations, mycoplasmal organisms were identified among the cilia in the auditory tubes at PID 14 but not at PID 25. Results of bacteriologic examination indicated that 10(4) to 10(6) color-changing units of M hyorhinis were isolated from the tympanic cavity at PID 0. Variable numbers of M hyorhinis were isolated at PID 7 and 14, and numbers were decreased at PID 25. CONCLUSIONS: M hyorhinis inoculated into the tympanic cavity can cause a self-limiting otitis media in SPF pigs.
With changes in heart rate and mean aortic pressure, an intraaortic balloon (IAB) works with incomplete inflation. The effects of initial peak positive pressure and plateau holding positive pressure on IAB volume were investigated and minimum pressures necessary to inflate an IAB to a desired volume were established with a standard IAB catheter (Datascope type, 9.5 Fr, 40 ml). Initial peak pressure greater than 200 mm Hg was adequate to attain the desired volume of the IAB. Plateau positive pressure should be altered in accordance with hemodynamic changes.
A spatiotemporal ESR-CT study, rapid three dimensional ESR imaging by which distribution and metabolism of radicals in a small region in a living body can be followed, was carried out by intravenously administering spin-labeled polysaccharides to mice. The in vivo lifetime of spin-labeled hydroxyethylstarch (TEMPO-HES) was shorter than that of spin-labeled dextran (TEMPO-DX), suggesting that the clearance of their spins depended on the stability of the polymer chains to the hydrolysis. Spatiotemporal image at the kidney domain of a mouse showed that low molecular weight TEMPO-DX was excreted into the kidney and then was transferred to the bladder. Time dependence of the ESR intensity of TEMPO-HES at certain points in the liver domain had a maximum showing that TEMPO-HES was taken into the liver and then was decomposed there by the metabolism, but the rate of decrease in the intensity was different in each part in the liver because of the difference in metabolic function. The rate of decrease of TEMPO-DX in the blood was slowed by the prior administration of dextran, meaning that the intake of TEMPO-DX into the liver from the blood was suppressed by the dextran.
New cardiovascular forceps have been conceived and a prototype of the new design has been fabricated. The new forceps feature a pair of gripping edges mounted on the tips of the handles at a 45-degree angle. Opening and closing the gripping ends are done in the same manner as conventional forceps. These new forceps are found to be quite effective when gripping tissues in narrow, deep operative fields.
The nitroxide group 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) was covalently bound to a dextran via an N-acetamido linkage to produce a novel spin probe, TEMPO-dextran (TEMPO-DX), which circulates for long time periods in an animal without metabolic degradation. TEMPO-DX was stable in mice, while small TEMPO analogs quickly disappeared after administration. Since dextran was reduced somewhat in size during synthesis, the resultant spin-labeled dextran could be excreted through the kidney. A strong L-band electron spin resonance signal was obtained shortly after intravenous administration of TEMPO-DX into the tail vein of a mouse, from which three-dimensional images of specific organs were calculated. The signal was found to persist for well over 1 h.
Temporary pacing wires are routinely placed at the end of cardiac surgery. These pacing wires are helpful in maintaining patients with postoperative bradycardias, and physiological pacing is also more desirable in critically ill patients. We herein report our simplified procedure for atrial pacing. This technique uses commercially available intravenous pacing catheters. The catheter is passed through the skin, and its tip is placed at the pericardial oblique sinus just between the right and left pulmonary veins. Atrial pacing is then initiated with a temporary pulse generator. This procedure is simple and effective for patients undergoing cardiac surgery. We also report two clinical cases that satisfactorily underwent atrial pacing using this procedure.
The effects of hemodynamic changes on intraaortic balloon (IAB) volumes were studied experimentally using a helium tachometer in a mock circulatory system. The IAB volume decreased with increases in the heart rate and mean aortic pressure, but the degree of reduction in the IAB volume was different among 4 commercially available IAB drivers. Improvements in IAB consoles are needed to compliment the progress made in percutaneous techniques for IAB insertion resulting in smaller balloons.
Nucleotide-sequence analysis showed that the gene for cytochrome oxidase subunit I (coxI) from tomato mitochondrial DNA has an ACG codon at a conserved position corresponding to an ATG initiation codon in other higher-plant coxI genes. cDNA-sequence analysis of the coxI transcripts showed that 15 positions in the genomic DNA were converted from C to U in the transcripts by RNA editing. One of the editing events is observed at the indicated ACG codon, producing an ATG initiation codon. The nucleotide sequences of 37 cDNA clones showed that the initiation codon was created in 32 out of the 37 clones, while nucleotide positions 254 and 11 were edited in 37 and 34 of the 37 clones examined, respectively, suggesting that creation of the initiation codon is a post-transcriptional event. The BamHI site at nucleotide position 757-762 within the coxI genomic DNA was altered in all 97 cDNA clones examined, demonstrating that RNA editing at this site in the transcripts is very common. RNA editing takes place to a lesser extent at the initiation codon, compared with editing at internal position 254. This indicates that editing is either a random process or that it involves a mechanism favoring less RNA editing in the initiation codon than in internal sites.
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A study of the pathology of the ear was performed on 479 pigs ranging in age from 1 day to 1 year. Histologically, 364 (76.0%) of 479 pigs were affected with otitis. Eustachitis was the most common and preceded an inflammation of other sites of the ear, and an acute eustachitis occurred from as early as 1 week of life. Immunohistochemical examination of frozen cryostat sections revealed Mycoplasma hyorhinis (Mhr) antigens on the luminal surface of the eustachian epithelia in 14 (50.0%) of 28 piglets examined. All the pigs positive for Mhr had an acute eustachitis. Ultrastructural examination on the auditory tubes with positive immunostaining disclosed many mycoplasmas among the cilia. Mhr was isolated from the auditory tubes and tympanic cavities of 19 (67.9%) and 16 (57.1%) of 28 piglets examined, respectively. Porcine otitis media may be caused primarily by Mhr infection in the auditory tube.
A dextran-bonded nitroxide radical (TEMPO-DX) was synthesized to obtain a radical with long life in vivo for ESR imaging. TEMPO-DX was injected intravenously into a rat tail vein and the decrease in ESR intensity in the collected, circulating blood was followed. The result showed that the half life of TEMPO-DX in vivo was 30 min, the longest value reported so far and more than 30 times longer than the corresponding radicals of the six-membered piperidine ring, which means that the bonding of a radical to the polymer greatly prolonged life. The stabilities of TEMPO-DX against the reduction with L-ascorbic acid and the rat liver homogenate were also examined and compared with those of the 3-carbamoyl-2,2,5,5-tetramethylpyrolidin-1-yloxy (CPROXYL) known as a radical stable in vivo. TEMPO-DX was shown not to be as stable as CPROXYL, thus in vivo stability of TEMPO-DX arises from the fact that it is slowly absorbed into the tissues where the radicals are quenched. An ESR image of the mouse head domain was obtained only by an intravenous injection of TEMPO-DX solution into the tail vein.
Chitosan derivatives, sulfated N-acyl-chitosan (S-Cn-chitosan) possessing various lengths of alkyl chain, were prepared, and the properties of their aqueous solutions were examined. The 1H-NMR spectrum of D2O solutions of S-C12-chitosan showed broadening of the proton signals caused by aggregation of the alkyl chain. The solubility of a hydrophobic compounds, azobenzene, was small in the aqueous solutions of S-Cn-chitosan with shorter alkyl chains, but increased with increasing length of the chains above C10, showing that micelles had been formed. The ESR spectrum of a spin probe, TEMPO, in an S-C14-chitosan solution showed the existence of a hydrophobic region in the solution, but this region did not exist in the S-C2-chitosan solution. The rigidity of this region was examined by using a spin probe, 16-doxyl-stearic acid. From these results, it was revealed that S-Cn-chitosan with longer alkyl chains formed a novel type of micelle called a "polymer micelle," which was more stable than the ordinary micelles formed from low-molecular-weight surfactants.
Removal of cerebrospinal fluid (CSF) has been proposed as a means of protecting the spinal cord against ischemic injury during thoracoabdominal aneurysm operations. We investigated the effect of altering CSF pressure (CSFP) on lumbar spinal cord blood flow (SCBF) in an experiment using dogs. The SCBF was measured before and after withdrawal of CSF in settings with and without thoracic aortic clamping. Furthermore, SCBF was measured at the basal state and after elevation of CSFP to 20 mm Hg and to 40 mm Hg. The SCBF did not change significantly before and after removal of CSF in settings both with and without thoracic aortic clamping. Elevation of CSFP significantly reduced SCBF. Elevation of CSFP reduces SCBF, but lowering CSFP per se does not increase SCBF whether the thoracic aorta is occluded or not. This supports the notion that removal of CSF offers spinal cord protection only when CSFP is abnormally elevated.
Mycoplasmas were isolated from the middle ears and nasal cavities of clinically ill, young pigs that were slaughtered due to an unfavourable prognosis. The isolation rates of Mycoplasma hyorhinis were 27 of 43 (62.8 per cent) from the auditory tube, 22 of 43 (51.2 per cent) from the tympanic cavity, and 15 of 25 (60.0 per cent) from the nasal cavity. M arginini was also recovered at rates of 11 of 43 (25.6 per cent) from the auditory tube, 7 of 43 (16.3 per cent) from the tympanic cavity, and 9 of 25 (36.0 per cent) from the nasal cavity. Dual infections with M hyorhinis and M arginini occurred in these sites in some cases. M hyorhinis was isolated from 16 (80.0 per cent) of 20 pigs with otitis media diagnosed histologically, and from two (25.0 per cent) of eight pigs without this condition. The isolation rate was significantly different (P < 0.05) between the groups, suggesting either that the organism triggers development of the disease of the ear or that the agent(s) or factors responsible for otitis media in the pigs created favourable conditions at this site for colonisation by M hyorhinis.