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Biomedical subjects

K Toyoda

Publications and source records attributed to K Toyoda.

At least 109 records · Page 6Linked to original sources
PubMed1994

Pontine infarction extending to the basal surface.

BACKGROUND AND PURPOSE: Etiology and symptomatology in pontine infarction extending to the basal surface are supposed to be different from those in deep pontine infarction of the lacunar type. The aim of this study was to compare the infarct size and location, vascular lesions, risk factors, and neurological deficits in three different types of acute pontine infarction. METHODS: We studied isolated pontine infarction extending to the basal surface on brain imaging (group 1, n = 30), deep pontine infarction without extension to the basal surface (group 2, n = 23), and pontine infarction with simultaneous extrapontine infarct in the posterior circulatory system (group 3, n = 20). Clinical features, angiographic findings, and risk factors such as emboligenic heart disease, hypertension, and hypercholesterolemia were compared among the groups. RESULTS: The infarct area was 2.5 times greater in group 1 than in group 2. On angiogram, atherosclerotic stenosis of the basilar trunk was observed in 50% of the patients studied in group 1, in 0% in group 2, and in 78% in group 3. Emboligenic heart diseases were observed in 23%, 0%, and 30% in groups 1, 2, and 3, respectively. However, hypertension (60% to 65%), diabetes mellitus (35% to 45%), and hypercholesterolemia (13% to 17%) were equally distributed among the three groups. Classic lacunar syndromes were seen in 14 patients (47%) in group 1, in 20 patients (87%) in group 2, but in none of the patients in group 3. Patients belonging to group 1 showed a higher incidence of hemiparesis involving the face (37%), sensorimotor stroke (20%), and hemiparesis with confusion (17%) than those in group 2 (22%, 0%, and 4%, respectively) or in group 3 (0%, 5%, and 0%, respectively). CONCLUSIONS: Pontine infarction in group 1 may have several different causes, such as cardioembolism, artery-to-artery embolism, or atherosclerosis of the basilar artery affecting pontine branches. Severe neurological symptoms often result that differ from those seen in the deep pontine lacunar infarction in group 2.

Adult↗
PubMed1994

Brain hemorrhage in mixed connective tissue disease. A case report.

Mixed connective tissue disease (MCTD) uncommonly develops stroke, although collagen disease is an important condition for stroke. A nonhypertensive woman with MCTD developed massive putaminal hemorrhage. No obvious predisposing factors were revealed by clinical and pathologic examination. MCTD may contribute to the development of brain hemorrhage by some mechanism other than hypertension.

Cerebral Arterial Diseases↗
PubMed1994

[Effect of efonidipine hydrochloride (NZ-105), a new dihydropyridine calcium antagonist, on the experimental atherosclerosis in cholesterol-fed rabbits].

We studied the effect of efonidipine hydrochloride [NZ-105:(+-)-2-[benzyl(phenyl)amino]ethyl 1,4-dihydro-2,6-dimethyl-5- (5,5-dimethyl-2-oxo-1,3,2-dioxaphosphorinan-2-yl)-4-(3-nitrophenyl )-3-pyridine-carboxylate hydrochloride ethanol], a newly synthesized dihydropyridine calcium antagonist, on atherosclerosis in 1% cholesterol-fed rabbits. NZ-105 (10, 30 and 100 mg/kg) was orally administered to the animals twice a day for 10 weeks. NZ-105 did not cause any significant change in the plasma lipid levels. The area of atherosclerotic lesion was reduced by 37% (P < 0.05) in the aortic arch and by 54% (P > 0.05) in the thoracic aorta of rabbits administrated 100 mg/kg of NZ-105. The content of cholesterol ester in the aorta was also reduced by 64% (P < 0.05) in the aortic arch and by 73% (P > 0.05) in the thoracic aorta. These results suggest that NZ-105 may suppress the development of atherosclerosis without affecting the plasma lipids.

Animals↗
PubMed1994

The relationship between spontaneous calcium oscillations and cell proliferation in cultured smooth muscle cells.

The relationship between spontaneous Ca2+ oscillations and cell proliferation was investigated in cultured longitudinal muscle cells from guinea pig ileum. BAPTA, caffeine, thapsigargine and La3+ suppressed the spontaneous Ca2+ oscillations and the DNA synthesis at 5.0 mM, 10.0 mM, 15.62 nM and 0.5 mM, respectively, whereas verapamil, nicardipine and ryanodine did not suppress either. However, BAPTA and La3+ did not inhibit the DNA synthesis at 1.25 mM and 0.13 mM, but did suppress the Ca2+ oscillations even at 1.0 mM and 0.1 mM, respectively. These results show that the spontaneous Ca2+ oscillations are not prerequisite for the cell proliferation.

Animals↗
PubMed1994

Purulent meningitis after endoscopic injection sclerotherapy for esophageal varices.

A 57-year-old man with liver cirrhosis developed alpha-hemolytic streptococcal meningitis following endoscopic injection sclerotherapy for esophageal varices. Central nervous system infection is uncommon as a complication of sclerotherapy, however, when such an infection does develop, it is usually intractable. We therefore emphasize the importance of immediate antibiotic therapy right after the onset of inflammatory symptoms in order to prevent the development of undesired infectious complications following sclerotherapy.

Ampicillin↗
PubMed1994

[Legionnaires' disease].

Among community-acquired pneumonias or hospital-acquired pneumonias, the genus Legionella, an intracellular bacteria, is one of the most important pathogens causing death. The bacteria from clinical specimens could not be cultured by ordinary methods and the polymerase chain reaction, a new method for rapid detection, has been developed; however, Legionella pneumonias are still difficult to diagnose. Antibiotics, such as macrolides, new quinolones and rifampicin, are very active against Legionella spp. These antibacterial agents should be administered when acute pneumonia tends to exacerbate with previous beta-lactams or aminoglycosides therapy. Legionella pneumonias are more likely to occur in elderly males or in the compromised-hosts with underlying diseases, such as malignancy, diabetes mellitus, AIDS, etc.

Anti-Bacterial Agents↗
PubMed1994

[Subchronic toxicity study of liquid paraffin in F344 rats].

A 13-week oral toxicity study of liquid paraffin was carried out in F344 rats at the dose levels of 5, 2.5, 1, 0.5, 0.2 and 0% in the powdered diet to select a suitable dose range for a 2-year carcinogenicity study. Each group consisted of 10 males and 10 females. No animals showed decrease in body weights and food intakes in any group, and all animals were surviving at the end of the experiment. Changes indicating obvious toxicity of liquid paraffin were not observed in the hematological-, serum biochemical- and histopathological-examinations. Based on these data, a concentration of 5% or more in the diet was considered as the maximum tolerable dose of liquid paraffin for both sexes in F344 rats.

Administration, Oral↗
PubMed1993

Induction of peroxisomal beta-oxidation by a microbial catabolite of cholic acid in rat liver and cultured rat hepatocytes.

The capability of (4R)-4-(2,3,4,6,6a beta,7,8,9,9a alpha,9b beta-decahydro-6a beta-methyl-3-oxo-1H-cyclopental[f]quinolin-7 beta-yl)valeric acid (DCQVA), a catabolite of cholic acid produced by enterobacteria, to induce peroxisome proliferation in vivo and in vitro was studied. Rats given 0.3% DCQVA in the diet for 2 weeks showed marked increases in peroxisomal beta-oxidation, mitochondrial 2,4-dienoyl-CoA reductase and microsomal laurate omega-oxidation activities in the liver compared with control rats given the diet without DCQVA. Cultured rat hepatocytes treated with DCQVA for 72 h also exhibited greatly enhanced beta-oxidation activity. The increased activity was concentration-dependent and the effective concentrations were comparable with those of clofibric acid that produced the same degree of induction in the assay. The results demonstrate that DCQVA is a potent peroxisome proliferator that occurs naturally in rat intestine.

Animals↗
PubMed1993

Comparative studies of the toxicity of standard reference materials in various cytotoxicity tests and in vivo implantation tests.

Polyurethane films that contained various amounts of zinc diethyldithiocarbamate (ZDEC) and zinc dibutyldithiocarbamate (ZDBC) were prepared as standard reference materials (SRM). Using three cell lines of V79, L929, and Balb/3T3 cells, the cytotoxicity of the dithiocarbamates and the SRM films were compared by agar diffusion assay, filter diffusion assay, neutral red assay, cell growth assay, and colony assay. Among these in vitro cytotoxicity tests, colony assay was found to be the most sensitive method for detecting the cytotoxicity. The cytotoxic potentials of extracts from SRM films correlated well with the concentrations of ZDEC or ZDBC involved in SRM. When various rubber materials including SRM and surgical rubber latex materials were tested, cytotoxic potentials of these extracts were also correlated with the inflammatory tissue capsule thickness in short-term implantation tests. On the basis of these results, the SRM is judged to be useful for validating test sensitivity, and comparing the correlation between in vitro and in vivo responses.

3T3 Cells↗
PubMed1993

Rabbit eye irritation caused by wearing toxic contact lenses and their cytotoxicities: in vivo/in vitro correlation study using standard reference materials.

To clarify the relationship between eye irritancy and cytotoxic potential induced by irritant materials, we made lenses coated with standard reference materials (SRMs) prepared from various amounts of zinc diethyldithiocarbamate (ZDEC) and polyurethane (PU). Zinc diethyldithiocarbamate was classified as a mild irritant by the Draize eye irritation test. When ZDEC-SRM coated contact lenses were applied to rabbit eyes, Draize scores increased in proportion to both the ZDEC and PU concentrations used for coating. Furthermore, correlation with the cytotoxic potential (gamma = -0.93) was better than with lactate dehydrogenase (LDH) activities of tears from rabbit eyes wearing these coated lenses (gamma = 0.78). In conclusion, in vivo eye irritancy induced by wearing lenses could be estimated quantitatively with the cytotoxic potentials using a colony assay. Furthermore, we could compare different sensitivities caused by the same set of SRMs among three different sites of tissue. As a result, the order of sensitivity was eye > muscle >> skin.

3T3 Cells↗
PubMed1993

Distribution of the afferent neurons from the canine recurrent laryngeal nerve.

Localization of the afferent neurons from the canine recurrent laryngeal nerve in the nodose ganglia (NG) and jugular ganglia was studied using the horseradish peroxidase technique. Labeled cells were detected in the ipsilateral NG and presented no distinct pattern of distribution, but rather were scattered throughout the ganglion. No labeled cells were found in the contralateral NG or bilateral jugular ganglia. The size of labeled cells varied from 15 microns to 60 microns. Two to six labeled cells larger than 45 microns were detected in each dog. Most of the labeled cells (62%) had a diameter between 30 microns and 45 microns. The percentage of labeled cells with a diameter between 15 microns and 30 microns was 30% and between 45 microns and 60 microns was 8%. This difference in size of labeled cells in the NG may be related to functional differences among the receptors mediated.

Animals↗
PubMed1993

Effects of hickory smoke condensate on gastric carcinogenesis in Wistar rats after treatment with N-methyl-N'-nitro-N-nitrosoguanidine and sodium chloride.

Short-term assays in vivo have suggested that hickory smoke condensate (HSC), a food flavouring, might have tumour-initiating and/or promoting activities in the glandular stomach of the rat. In the present study, the modifying effects of HSC on glandular stomach carcinogenesis after initiation with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and sodium chloride (MNNG salt) were investigated in male Wistar rats. Animals were given MNNG solution (100 ppm) as drinking water and simultaneously fed the diet supplemented with 5% sodium chloride for 8 wk. Matched negative controls received neither MNNG nor sodium chloride. Rats were then fed a basal diet and given HSC solution (1 or 3%) or tap water for the following 32 wk. During the experimental period, treatment with MNNG salt and administration of HSC both brought about growth retardation although the final body weight of rats was comparable between groups. Only two rats treated with MNNG salt followed by 1% HSC developed adenocarcinoma of the stomach. HSC treatment appeared to increase the number of rats with preneoplastic hyperplasias and/or adenocarcinomas in both the fundic and pyloric mucosa, although not to a statistically significant extent. HSC administration significantly increased malondialdehyde levels in the urine and gastric mucosa, the former in a dose-dependent manner. The results suggest that HSC has little, if any, promoting effect on two-stage glandular stomach carcinogenesis in rats when given during the post-initiation phase. However, the tumour co-initiating effects of HSC require further clarification.

Adenocarcinoma↗
PubMed1993

Relationship between bisacodyl-induced urolithiasis and rat urinary bladder tumorigenesis.

Dietary supplementation with bisacodyl at concentrations ranging from 1 to 0.3% was found to induce both calculi and epithelial proliferative lesions, including a transitional-cell carcinoma, in the urinary bladder of F344/DuCrj rats. In order to clarify the relationship between the bisacodyl-associated urinary bladder calculi and the development of proliferative lesions in the urinary bladder, male and female rats were administered bisacodyl-diets at concentrations of 0.3, 0.1, and 0.03% for 32 wk. Both sexes of animals treated with bisacodyl suffered from diarrhea throughout the experimental period. Epithelial proliferative lesions and calculus formation were observed only in the urinary bladder of male rats given the 0.3% bisacodyl diet. Proliferative lesions and increases of bromouracil deoxyriboside (BUdR) labeling indices were found only in the urinary bladder epithelium of rats with calculi, the severity of the former correlating with the calculus weight and being most marked in the dome areas, which are susceptible to physical stimulation. These findings indicate a close relationship between the development of proliferative lesions and the existence of calculi in the urinary bladder, and suggest that bisacodyl-induced proliferative lesions are not caused directly by bisacodyl per se but are secondary to calculus formation.

Administration, Oral↗
PubMed1993

Enhancing effect of ethanol on esophageal tumor development in rats by initiation of diethylnitrosamine.

The effects of ethanol on initiation of esophageal tumorigenesis by diethylnitrosamine (DEN) were investigated in male F344 rats. Animals were administered 50 p.p.m. DEN plus 10% ethanol (Group 1), 33 p.p.m. DEN (Group 2), 50 p.p.m. DEN (Group 3) or 10% ethanol (Group 4) in the drinking water for the first 8 weeks, and were then maintained on basal diet and tap water for up to 104 weeks. The concentration of 33 p.p.m. DEN in Group 2 was an adjustment to the anticipated intake in Group 1. Consequent total intakes of DEN in Groups 2 and 3 were respectively 80% and 134% of that in Group 1. Histopathological examination of esophagus tissue after final sacrifice revealed incidences of papillomas and/or carcinomas in Groups 1, 2 and 3 to be 57.7, 3.8 and 10.7% respectively. No esophageal tumors occurred in Group 4. The incidence of hyperplasia was 100% in Group 1 in contrast to 46.2% in Group 2, 57.1% in Group 3 and 3.6% in Group 4. Thus, the incidences of esophageal proliferative lesions were significantly higher in Group 1 than in Groups 2 or 3. Our results clearly indicate that ethanol has an enhancing effect on the development of esophageal tumors induced by DEN in rats, when administered during the initiation phase.

Animals↗