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Biomedical subjects

K Toyoda

Publications and source records attributed to K Toyoda.

At least 145 records · Page 8Linked to original sources
PubMed1992

A case of panic disorder induced by oral contraceptive.

A 27-year-old woman experienced feelings of unreality and fear after taking an oral contraceptive in the form of birth control pills. She subsequently experienced a panic attack just after she had stopped taking the pills. This was characterized by palpitation, general fatigue, trembling of the whole body, and dyspnea. The panic disorder experienced by the patient could have been due to the drug's potentiating of the sympathoadrenal response to simple physiological stimuli, or possibly to a disorder in psychological functioning caused by an anxiotropic effect of rapid endocrinological change.

Adult↗
PubMed1992

[Twenty-eight-day repeated dose toxicity test of pentaerythritol in F344 rats].

A twenty-eight-day repeated dose toxicity test of pentaerythritol at dose levels of 1000 or 0 mg/kg/day was carried out in male and female F344 rats. Thirteen animals of each sex were divided into 2 groups with 7 rats receiving pentaerythritol treatment and 6 rats served saline as control. All groups received an i.g. administration daily for 28 days. As to serum biochemical and hematological examinations, there were no serious differences between the pentaerythritol-treated rats and the control rats. On histopathological examination, no specific changes were observed in the pentaerythritol-treated rats. Based on these results, the no-observed-effect level of pentaerythritol can be concluded to be more than 1000 mg/kg/day.

Administration, Oral↗
PubMed1991

Evaluation of biocompatibility, based on quantitative determination of the vascular response induced by material implantation.

The biocompatibility of nine different materials, including positive and negative references, 4 polyurethane based and 3 latex based materials was investigated by (1) cytotoxic assay using V79 chinese hamster cells, (2) the thickness of inflammatory layer at 3 and 7 days after intramuscular implantation test, and (3) the course of the blood flow in tissue reaction around subcutaneously implanted materials using Laser Doppler Flowmetry (LDF) over 14 days following implantation. In addition, for some materials, different modes of sterilization were compared. Although the three methods explore different reactive systems, the material ranking obtained was highly similar for the three methods, suggesting a relative accuracy between them. For one latex however, an absence of cytotoxic effect in culture and a highly intense response by LDF investigation of the same order of magnitude as for the positive reference implant suggest that bioincompatibility may result from the material itself and cannot be exclusively investigated by the leaching of toxic components.

Anesthesia↗
PubMed1991

Localization of the sensory neurons in the canine nodose ganglion sending fibers into the internal branch of the superior laryngeal nerve.

The distinct localization of the sensory neurons in the canine nodose ganglion that send fibers into the internal branch of the superior laryngeal nerve (the main sensory pathway from the larynx) was studied using horseradish peroxidase technique. The labeled cells were located mainly in the rostral one-third of the lateral side of the nodose ganglion. We conclude that the localization of these labeled cells does not reflect a difference in cellular role or function but is due to the course of the nerve's fibers.

Animals↗
PubMed1991

Enhanced lipid peroxidation in rat gastric mucosa caused by NaCl.

The effects of NaCl on lipid peroxidation levels in gastric mucosa and urine were investigated in male Wistar rats. The animals were fed NaCl-supplemented diet at concentrations of 4.0, 2.0, 1.0, 0.5, 0.25 and 0% (control) for 5 weeks. Further groups were maintained on the 4.0 or 0% NaCl diets and simultaneously administered 20 p.p.m. indomethacin dissolved in the drinking water. When the rats were killed, a dose-related increase of malondialdehyde (MDA) was found in both gastric mucosa and urine, the urinary MDA levels clearly correlating with those for stomach tissue. Cell proliferation of fundic mucosa was also significantly increased in rats fed 4.0 or 2.0% NaCl-supplemented diet. Indomethacin suppressed the 4% NaCl-associated MDA increase in both gastric mucosa and urine as well as the elevation in cell proliferation. The results clearly show that administration of NaCl, a gastric tumor promoter, is associated with enhanced lipid peroxidation in the gastric mucosa.

Animals↗
PubMed1991

[Localization of sensory neurons in the canine nodose ganglion sending fibers to the laryngeal nerves].

Afferent fibers from the larynx traverse through the superior laryngeal nerve (SLN) and the inferior laryngeal nerve (ILN), and the parent cell bodies of these fibers are located in the nodose ganglion (NG). However, the exact location and form of these neurons in the NG have not been clarified. The aim of this study is to determine the exact location and form of the sensory neurons in the canine NG which send fibers to the laryngeal nerves, using the retrograde tracer technique with wheat germ agglutinin-horseradish peroxidase (WGA-HRP). The cell bodies sending sensory fibers to the internal and external branches of the SLN (SLNI & SLNE) were localized on the rostro-lateral side of the NG, but the cell bodies sending fibers to the ILN were widely distributed. These findings suggest that the location of cells does not reflect differences in the roles of the cells, but is due to the courses of nerve fibers. The cell bodies sending sensory fibers to the SLNI accounted for about 11% of all cells in the NG; about 0.1% of cells sending fibers to the SLNE; and about 0.2% in the ILN. The cell bodies sending sensory fibers to each laryngeal nerve varied in size, from 15 to 60 microns, suggesting differences in the roles of these cells.

Animals↗
PubMed1991

[Twenty-eight-day repeated dose toxicity test of p-phenetidine in F344 rats].

A twenty-eight-day repeated dose toxicity test of p-phenetidine was carried out in male and female F344 rats at dose levels of 160, 40, 10 or 0 mg/kg/day. Thirty animals of both sexes were divided into 6 groups of equal number. All groups were treated daily by i.g. administration for 28 days, two extra groups of animals at dose levels of 160 and 0 mg/kg being used for investigation of recovery over 14 days. Hematological and urinary examinations revealed decrease in erythrocytes and increased serum reticulocytes and urinary urobilinogen in the 160 and 40 mg/kg groups of both sexes, and methemoglobinemia occurred in the 160 mg/kg group. Increase in spleen weight was noted in the 160 and 40 mg/kg groups. On histopathological examination, hemosiderosis, increased extramedullary hemopoiesis, congestion of the spleen and myeloid hyperplasia of the bone marrow were observed in the 160 and 40 mg/kg groups of both sexes. Repair of these lesions occurred within 14 days after the cessation of administration. Based on these findings, a no-observed-effect level for p-phenetidine would be concluded 10 mg/kg/day.

Animals↗
PubMed1991

[Subchronic oral toxicity study of stevioside in F344 rats].

A 13-week subchronic oral toxicity study of stevioside was carried out in F344 rats at dose levels of 0, 0.31, 0.62, 1.25, 2.5 and 5% in diet, to determine appropriate dose levels for a 2-year carcinogenicity study. The rats were randomly allocated to 6 groups, each consisting of 10 males and 10 females. No animals died during the administration period. Between the control and treated groups, there were no differences in body weight gain during the administration period and in food consumption in the later period of the study. LDH on biochemical investigation and single cell necrosis in the liver revealed by histopathological examination were increased in all male treated groups. These were not considered specific changes, because of the lack of any clear dose response, the relatively low severity and the limitation to males. Other parameters that were found to demonstrate significant differences on hematological and biochemical investigations were of minor toxicological significance. From these results, a concentration of 5% in diet was concluded to be a suitable maximum tolerable dose of stevioside for a 2-year carcinogenicity study in rats.

Administration, Oral↗
PubMed1991

[Ultrastructural study of the blood-testis barrier in rat by the lanthanum method].

Ultrastructural changes of the testes in 35-week-old WBN/Kob rats were investigated using the lanthanum-tracer method. Tissues were cut and fixed with a solution containing 1% lanthanum and 2% glutaraldehyde in a 0.1 M sodium cacodylate buffer at pH 7.8 and with a solution of 2% osmium and 1% lanthanum in a 0.1 M sodium cacodylate buffer. Ultrathin sections of epoxy resin-embedded specimens were stained with uranyl acetate and lead citrate and observed into a JEM-100CXS JEOL transmission electron microscope. The remnants of each testis were fixed in Bouin's fixative, and observed light-microscopically, where almost all seminiferous tubules in all of the six testes were found to be severely atrophied. Electron microscopically, lanthanum pigments were limited in the Sertoli cell tight junctions of the seminiferous tubules even in the severely atrophied tubules. In conclusion, it is unlikely that the testicular atrophy in WBN/Kob rats is attributable to dysfunction of the blood-testis barrier.

Animals↗
PubMed1991

[Long-term changes in cerebral blood flow in patients with atherothrombotic and embolic brain infarction].

Cerebral blood flow (CBF) was measured twice at years interval using xenon-133 inhalation technique in patients with atherothrombotic and embolic supratentorial brain infarction. The purpose of the study was to elucidate factors influencing long-term change in CBF in two subtypes of brain infarction of different mechanisms. Those patients were excluded from the study, who had bilateral hemispheric lesions, significant arterial lesion in the contralateral carotid axis and recurrent stroke before the second measurement of CBF. Of 46 patients studied, 23 (17 men and 6 women) were classified as atherothrombotic and 23 (15 men and 8 women) as embolic infarction based on the diagnostic criteria reported earlier. Their age at onset was 60.6 +/- 8.9 years old (mean +/- S.D.) for atherothrombotic patients, and 60.2 +/- 11.0 years old for embolic patients. The first measurement of CBF was performed between 31 and 87 days and the second measurement between 13 and 99 months after onset. In atherothrombotic group, mean hemispheric CBF (mCBF) of the affected side tended to be higher in patients examined at intervals shorter than 30 months, but tended to decrease in those at longer interval. The multivariate stepwise regression analysis indicated only "the interval between 2 measurements" to have a significant effect on reduction of mCBF, although in addition to the interval (p less than 0.05), infarct-size (p less than 0.01) and change in PaCO2 (p less than 0.05) were suggested to be possible factors by single regression analysis. In embolic group, an increase in hematocrit had a significant effect on reduction of mCBF, even when being evaluated with multivariate stepwise regression analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

[Isolated nuclear oculomotor nerve palsy due to mesencephalic infarction].

A patient with unilateral nuclear oculomotor palsy due to midbrain infarction is described. A 46-year-old man was admitted because of difficulty in opening right eye and double vision noticed when he awoke in that morning. On admission, neurological examination revealed total right oculomotor palsy with slight impairment of left upward gaze. There were no other neurologic abnormalities at all. Brain CT and cerebral angiograms were also normal. Magnetic resonance imaging (MRI) performed on the ninth day, however, demonstrated high signal intensity in the right tegmentum of the mesencephalon on T2-weighted images, which was shown more clearly after the administration of Gadolinium-DPTA. He was diagnosed as nuclear third nerve palsy caused by midbrain infarction. The majority of isolated oculomotor nerve palsy has been reported to be caused by extraaxial lesion. When the oculomotor palsy is caused by intraaxial ischemic lesion, it is usually accompanied by other brain stem signs, because abundant nuclei and fibers are present adjacent to the oculomotor nucleus and nerve in the mesencephalon. The present case clarified that such a small infarct disclosed only by MRI can cause isolated oculomotor nerve palsy. It is emphasized that the intraaxial ischemic lesion should be ruled out by using the sophisticated diagnostic aid before making diagnosis of peripheral lesion. This is the first report of the isolated third nerve palsy resulting from mesencephalic ischemic lesion in the Japanese.

Cerebral Infarction↗
PubMed1990

Effects of 2-phenyl-1,4-benzoquinone and 2,5-dihydroxybiphenyl on two-stage mouse skin carcinogenesis.

Two metabolites of sodium o-phenylphenate (OPP-Na), 2-phenyl-1,4-benzoquinone (PBQ) and 2,5-dihydroxybiphenyl (5-OH), were examined for initiating, promoting or complete carcinogenic activity for skin carcinogenesis in female CD-1 mice. While PBQ treatment (1 mg per mouse, twice a week for 34 weeks) did cause sustained hyperplasia like 12-O-tetradecanoylphorbol 13-acetate (TPA) treatment (2.5 micrograms, twice/week for 34 weeks), it showed weak, but not statistically significant, tumor promoting potential for skin tumor development initiated with 7,12-dimethylbenz[a]anthracene (DMBA, 10 micrograms x 10 in 5 weeks). On the other hand, 5-OH applied at a dose of 10 mg/mouse using a similar protocol did not exert any promoting influence, and neither of these chemicals administered continually for 40 weeks without prior DMBA initiation treatment induced any skin tumors. Furthermore, both chemicals applied 10 times in 5 weeks at higher doses (2 mg for PBQ and 20 mg for 5-OH) in association with subsequent TPA treatment did not initiate any skin tumor development. Thus, neither of the OPP-Na metabolites demonstrated any capacity to influence skin tumor development in any manner, despite the fact that OPP-Na itself was previously found to exert skin tumor promoting potential in the mouse.

9,10-Dimethyl-1,2-benzanthracene↗