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Biomedical subjects

T Osada

Publications and source records attributed to T Osada.

At least 163 records · Page 9Linked to original sources
PubMed1992

[A case of ascending aortic dissection after aortic valve replacement in congenital bicuspid aortic valve].

Congenital bicuspid aortic valve is a risk factor of aortic dissection, but the case is rare in Japan. Several reports described ascending aortic aneurysm after aortic valve replacement. In these reports, most of aneurysms were false aneurysm, but the cases of ascending aortic dissection were rare. In this case, dissecting aneurysm of the ascending aorta occurred 4 years after aortic valve replacement, which was performed with mechanical prosthesis because of infective endocarditis, and it was repaired successfully by the modified Cabrol's method. This case was congenital bicuspid aortic valve, and had already been complicated with moderate aortic dilatation in the ascending aorta. In patients of congenital bicuspid aortic valve with aortic dilatation, consideration of complete replacement of the ascending aorta with aortic valve replacement is important.

Adult↗
PubMed1992

Effects of warfarin at beginning doses on patients with valve replacement.

Warfarin administered to patients with valve replacement at a dose of 0.1 mg/kg for 2 days after surgery, and blood levels of warfarin, TT, PT, HPT, total vitamin K and vitamin K1-epoxide were determined at various time intervals after the administration of the drug. The measurements were obtained from 15 patients: 8 patients with AVR, 6 patients with MVR, and 1 patient with DVR. The blood levels of warfarin reached a peak of 462 +/- 160 ng/ml 6 hours after the administration, TT, PT and HPT were 40% of the initial values 24 hours after the administration, and vitamin K1-epoxide was 1.28 +/- 0.30 ng/ml 24 hours after the administration. It is clear from the results that warfarin exhibits sufficient anticoagulant effects at a beginning dose of 0.1 mg/kg after surgery to prevent a sudden decrease in blood coagulation.

Blood Coagulation Factors↗
PubMed1992

[A successful case of thoracic aortic aneurysm with mixed cryoglobulinemia].

Cold-reactive proteins, such as cold agglutinins, cryoglobulins, and cryofibrinogens, are reversibly precipitates, or gel, upon exposure to cold temperatures. Cryoglobulins are usually not of importance, but under special conditions, such as surgical hypothermia, hyperviscosity and damage in microcirculation may occur in patients with high plasma concentration of cryoglobulins. Several groups have reported their efforts to reduce further the risks of surgical hypothermia in patients with cold agglutinins, but rarely in patients with cryoglobulins. A 57-year-old woman with thoracic aneurysm, requiring replacement of the ascending aorta and the aortic arch, had mixed cryoglobulinemia (cryocrit 29%) associated with rheumatoid arthritis. Steroids therapy and preoperative plasmapheresis were performed, and cryocrit levels were decreased until 0% before operation. Systemic hypothermia (25 degrees C), hemodilution techniques during cardiopulmonary bypass, and cold crystalloid cardioplegia were successfully employed, and no clinical evidence of microcirculation damage was posed after operation.

Aorta, Thoracic↗
PubMed1991

Reaction of proteinases with alpha 2-macroglobulin from the American horseshoe crab, Limulus.

The products generated by the reaction of Limulus alpha 2-macroglobulin with trypsin were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions. Unreacted Limulus alpha 2-macroglobulin had a subunit molecular mass of 185 kDa. Trypsin-reacted samples contained two prominent peptides smaller (85 and 100 kDa) and three peptides larger (200, 250, and 300-350 kDa) than the unreacted subunit. Reaction of methylamine-treated Limulus alpha 2-macroglobulin with trypsin resulted in the same two prominent reaction products smaller than 185 kDa, but all of the reaction products larger than 185 kDa were absent. The covalent binding of biotinylated trypsin with Limulus alpha 2-macroglobulin was detected by probing Western blots with horseradish peroxidase-avidin. Surprisingly, the only reaction products that contained trypsin were bands at 100 and 120 kDa. The staining of these bands with horseradish peroxidase-avidin was weak: most of the biotinylated trypsin that remained associated with alpha 2-macroglobulin during gel filtration chromatography was located at the dye front following reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The reaction products larger than 185 kDa did not contain trypsin. Methylamine-reacted Limulus alpha 2-macroglobulin failed to bind any biotinylated trypsin. In contrast to the reaction of trypsin with Limulus alpha 2-macroglobulin, all high molecular mass bands generated by the reaction of human alpha 2-macroglobulin with biotinylated trypsin stained intensely with horseradish peroxidase-avidin. Thus, Limulus alpha 2-macroglobulin forms thiol ester-dependent, high molecular mass products involving isopeptide bonding between trypsin-generated fragments, without the incorporation of trypsin into the complexes. Most of the alpha 2-macroglobulin-associated trypsin is non-covalently trapped rather than covalently cross-linked.

Animals↗
PubMed1991

A fact database for toxicological data at the National Institute of Hygienic Sciences, Japan.

The computerized fact database for the toxicity data of chemicals was constructed at the National Institute of Hygienic Sciences, Tokyo, Japan (biological database, BL-DB). The BL-DB stores data on mutagenicity, teratogenicity, carcinogenicity, and other toxicological tests of chemicals that appeared in the scientific literature. The BL-DB includes information about chemical identification, test system, results of the assays, and a bibliography. The system consists of five modules: data collection, data maintenance, data search, data downloading, and backup. ADABAS is used as a core database management system. Many kinds of test data are stored with the same formats; therefore, users can retrieve data of different toxicological data by the same manner. A user of the BL-DB can use about 50 kinds of commands to interact with the system, and the majority of fields are defined as search fields, thereby facilitating retrieval of target data through many ways. Currently, there are mainly data for the mutagenicity, especially on the Salmonella/microsome assay and the rodent micronucleus assay. These data can be retrieved and used for structure-activity relationship studies.

Abnormalities, Drug-Induced↗
PubMed1991

The expert system for toxicity prediction of chemicals based on structure-activity relationship.

The prediction systems of chemical toxicity has been developed by means of structure-activity relationship based on the computerized fact database (BL-DB). Numbers and ratio of elements, side chains, bonding, position, and microenvironment of side chains were used as structural factors of the chemical for the prediction. Such information was obtained from the BL-DB database by Wiswesser line-formula chemical notation. In the present study, the Salmonella/microsome assay was chosen as indicative of the target toxicity of chemicals. A set of chemicals specified with mutagenicity data was retrieved, and necessary information was extracted and transferred to the working file. Rules of the relations between characteristics of chemical structure and the assay result are extracted as parameters for rules by experts on the rearranged data set. These were analyzed statistically by the discriminant analysis and the prediction with the rules were evaluated by the elimination method. Eight kinds of rules to predict Salmonella/microsome assay were constructed, and currently results of the assay on aliphatic and heterocyclic compounds can be predicted as accurately as +90%.

Algorithms↗
PubMed1991

Sex differences in the basal firing rate and the responsiveness to opioid peptides of rat hippocampal neurons.

The basal firing rate and the responsiveness to dynorphin and leu-enkephalin of the neurons in the pyramidal cell layer of the hippocampus were studied in intact male, castrated male, castrated female, and castrated female rats injected s.c. with 20 micrograms estradiol benzoate (EB) for 3 days. Most of the neurons studied had low spontaneous firing rate (less than 5 Hz) and burst-like activity in all the groups. The basal firing rates in castrated males and females were not different from those in intact males and castrated females treated with EB, respectively. However, neurons in intact and castrated males had significantly higher firing rates than those in castrated females with and without EB treatment, respectively. When effective, both iontophoretically applied dynorphin and leu-enkephalin evoked predominantly excitatory responses. Either castration of males or EB treatment to castrated females did not affect the neuronal responsiveness to these peptides. On the other hand, the responsiveness of neurons to leu-enkephalin, but not to dynorphin, was significantly different between castrated male and female rats. These results suggest that sex steroids do not affect the basal firing rate as well as the responsiveness to opioid peptides of the pyramidal cells in the hippocampus in adult animals. However, sex differences in the basal firing rate and in the responsiveness to leu-enkephalin might account for the differences in hippocampal functions between male and female rats.

Action Potentials↗
PubMed1991

[Surgery of atrial septal defect in patients aged over 40 years: comparative study of direct suture and patch closure].

Thirty patients over 40 years of age with atrial septal defects were operated on between 1981 and 1989. They were divided into two groups according to operative technique, group A of patients with direct suture of defect (17 cases) and group B patch closure (13 cases), in order to investigate the incidence of postoperative complications. Patient age and size of defect in group B were both greater than in group A. One group A patient had pulmonary stenosis, two group B patients had mitral valvular disease and six group B patients had pulmonary hypertension. The incidence of postoperative heart failure was 29% in group A and 61% in group B and that of arrhythmia was 47% and 69% respectively, however there were no intraoperative and postoperative deaths. We concluded that, although a high incidence of postoperative complications was observed in group B, patch closure was recommended for older patients with atrial septal defect because direct suture was more likely to distort the atrial septum.

Adult↗
PubMed1990

Role of leukotrienes in hydrochloric acid-induced gastric lesions in rats.

This study was designed to clarify the role of leukotrienes (LTs) in 0.6 N hydrochloric acid (HCl)-induced gastric lesions. In rats given 1 ml of 0.6 N HCl intragastrically, severe hemorrhagic lesions were observed in the gastric corpus mucosa 15 min, and 1, 3, and 5 hr after HCl administration. In the control rats treated with physiological saline, LTs in gastric mucosa were not observed throughout the experiments. Peptide LT contents (sum of LTC4 and LTD4) after 1 or 3 hr were increased to 13.2 +/- 2.9 ng/g tissue and 6.3 +/- 1.9, respectively, although peptide-LTs were not observed 15 min and 5 hr after HCl administration. Premedication with AA-861, a lipoxygenase inhibitor, decreased dose-dependently peptide LT contents 1 hr after HCl administration. Furthermore, gastric lesions caused by 0.6 N HCl were significantly prevented by 300 mg/kg of AA-861 3 hr after HCl administration, although the dose of AA-861 did not significantly prevent gastric lesions 1 hr after HCl administration. Administration of YM-638, a peptide LT antagonist, showed similar protective effects to AA-861 except inhibition of increase in LT levels after HCl administration. These results suggest that peptide LTs contribute to persistence of gastric lesions, although they might not participate in the onset of 0.6 N HCl-induced gastric lesions.

Animals↗
PubMed1990

[Metastatic penile tumor from lower pharynx: a case report].

Metastatic tumor of the penis is uncommon and only 95 cases have been reported in Japan. A 70-year-old man, who had squamous cell carcinoma of the lower pharynx, complained of urethral induration. Biopsy was performed and pathological diagnosis was metastatic tumor of penis originating from the lower pharynx. Although partial response in tumor size was noted by irradiation therapy, the patient died of multiple metastases in the 4th month after the diagnosis. This case is the first report of metastatic penile tumor originating from the lower pharynx.

Aged↗
PubMed1990

[A new method for closure of median sternotomy: applications of a stapler system].

Power driven staples were used in 20 patients for median sternotomy closure, and the staples were evaluated for clinical fixation. In each case four to six staples and two wires were used to secure closure. Clinically, in one patient prolonged sternal flail was observed, but this disappeared after six weeks. In the remaining 19 patients, good sternal fixation was secured. No cases required surgical procedures such as refixation of the sternum or removal of the staples. As a means of assessing the status of "backing out", which is a major cause of poor fixation, the backing out part of the staple leg was measured from lateral sternal radiographies. The ratio of the backing out portion to the staple leg, the backing out ratio (BOR), was calculated. The average BOR was found to be 32.7 +/- 21.4% (n = 102). The BOR was 70% or less in 91.2% of all staples, and 70% or more in 8.8%. The fragility of the sternum, poor sternal connection and inadequate technique to drive were suspected as factors accountable for backing out. In conclusion, the stapler system seems to be useful for sternal fixation and will become even more after improvement of the staple size and technical modifications to assure better connection at the driven site.

Adult↗
PubMed1989

[Clinical study of the anti-calculus effect of a dentifrice containing sodium polyphosphate].

A double-blind clinical study was conducted to evaluate the effect of a tartar-control dentifrice containing 1% sodium polyphosphate as tartar control agent compared with dentifrice A containing 5% sodium pyrophosphate and a placebo dentifrice. One hundred forty-eights who continued to have a degree of calculus formation after using a regular dentifrice containing no tartar control agent for 1 month in the pretest, were stratified randomly on the basis of pretest, calculus score, age and sex into 3 homogeneous groups. All subjects who received initial prophylaxis were provided the assigned dentifrice and toothbrush. No instructions regarding frequency or method of toothbrushing were allowed. Assessment of supragingival calculus was made at 4 and 12 weeks using the calculus scoring procedure proposed by Volpe et al. Side effects such as oral irritation, ablation of oral mucosa and discoloration of teeth caused by dentifrices were also diagnosed after 12 weeks of use. The following results were obtained in this study. 1. The test dentifrice had reduced (P less than 0.01) supra-gingival calculus significantly more than dentifrice A and the placebo at 12 weeks. 2. A significant reduction (P less than 0.01) was observed when dentifrice A was compared with the placebo dentifrice. 30.1% reduction was obtained using the test dentifrice and 9.0% reduction using dentifrice A when assessed in subjects who had a pretest VMI score of more than 6.0. 3. No side effects caused by the dentifrice which contained sodium polyphosphate were observed.

Dental Calculus↗
PubMed1989

Fluctuation of the mucosal hydroxyproline content in compound 48/80-induced gastric lesions in rats.

Extensive gastric mucosal lesions were observed after i.p. administration of compound 48/80 (0.75 mg/kg) for 3 days to rats. The mucosal hydroxyproline content was significantly increased at 4 h after the last injection of compound 48/80 and subsequently decreased as the lesions were healed. Treatment with cimetidine (50 mg/kg, i.p.) did not prevent compound 48/80-induced gastric lesions. The increase in the mucosal hydroxyproline content was significantly reduced by treatment with cimetidine. This fact suggested that cimetidine might have an inhibitory effect on the regeneration of connective tissue.

Animals↗
PubMed1989

The role of prostaglandin D2 in the genesis of indomethacin-induced gastric lesions in rats.

Four kinds of prostaglandins (PGs), 6-keto-PGF1 alpha, PGF2 alpha, PGE2 and PGD2, in rat gastric mucosa were decreased at 1 or 6 h after oral administration of indomethacin (2 or 12 mg/kg). With 2 mg/kg of indomethacin, the PG levels had slightly recovered 6 h later. Gastric lesions were observed 6 h after administration of indomethacin (12 mg/kg), but not with 2 mg/kg. Omeprazole (20 mg/kg, i.p.) prevented ulcer formation caused by indomethacin, without improvement of the reduced gastric mucosal PG levels. PGD2 (0.5 mg/kg, p.o.) reduced indomethacin-induced gastric lesions and considerable amounts of PGD2 existed in the gastric mucosa. We conclude that H+ is a determining factor in the genesis of indomethacin-induced gastric lesions and persistent decreases in tissue PG levels also participate in ulcer formation.

Animals↗