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Biomedical subjects

K Takemoto

Publications and source records attributed to K Takemoto.

At least 91 records · Page 5Linked to original sources
PubMed1988

[Magnetic resonance imaging (MRI) of intracranial chordomas].

MR images of 5 patients with intracranial chordoma were evaluated and compared with those of other clival lesions (1 clival osteomyelitis, 1 metastatic clival tumor, 3 clival meningiomas). The MR examination was performed using a 0.5 T superconductive magnet, with approximately 10 mm section thickness, one average and a 256 x 256 matrix. T1 weighted images were obtained by inversion recovery (IR) with TR 2100-2500 msec, TI 600 msec and TE 40 msec. T2 weighted images were obtained by spin echo pulse sequence with TR 1800-2500 msec and TE 120 msec (long SE). In several cases, the spin echo pulse sequences with TR 1000 msec and TE 40 msec (short SE) were also done. Multiplaned images were obtained. Four of 5 intracranial chordomas were low in intensity compared to cerebral gray matter on T1 weighted images, and all of 5 chordomas were as high in intensity as cerebrospinal fluid or higher than that of cerebrospinal fluid on T2 weighted images. Clival fatty marrow is high intensity on T1 weighted images. Clival involvement by a tumor was a clearly demonstrated as disappearance of this high intensity in all cases. In two cases, the tumor extended to the retropharyngeal space and this was detected clearly on short SE image. Although clival fatty marrow was disappeared, osteomyelitis and metastatic tumor in clivus were iso-intense to cerebral gray matter on both T1 and T2 weighted images.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

[Occupational lung cancer. A comparison between humans and experimental animals].

Many epidemiological and experimental studies have suggested that the respiratory tract is one of the most sensitive organs to environmental carcinogens. Nevertheless there is little evidence to determine the relationship between a specific environmental carcinogen and a cell type of lung cancer, because the cell types of lung cancer and their relative frequencies are highly complex compared with those of other organs and tissues. In the present paper, occupational lung-cancer characteristics, which are the clearest in the relation between cause and effect in human lung cancers, were reviewed in comparison with the results of animal experiments concerned with occupational lung carcinogens. Through accumulation of histopathological examinations of the lung cancer cases, the following relationships between cause and cell type were conjectured: chromium and squamous cell carcinoma; asbestos and adenocarcinoma; nickel and squamous cell carcinoma; beryllium and small cell carcinoma; bis (chloromethyl) ether and small cell carcinoma; mustard gas and squamous cell or small cell carcinoma; vinyl chloride and large cell or adenocarcinoma; radionuclides and small cell carcinoma. The relation pertaining to arsenic, benzotrichloride and tar could not be conjectured because of insufficient cases and information in the histological diagnosis. On the other hand, the carcinogenicity of these substances in occupational exposure has been confirmed by animal experiments administered intratracheally or by inhalation studies under relatively higher concentration. As a result of recent refinements of inhalation study, all-day and life-span exposure to extremely low concentrations, such as microgram/m3 orders, of certain substances has been possible. The characteristics of lung tumors occurring in these animals are rather different from those of human. For example, in mouse, almost all of the malignant lung tumors developed by carcinogens are adenocarcinomas and it is rare to find the squamous cell carcinoma. Moreover, small cell carcinoma and large cell carcinoma have not known to occur in the lungs of rats and mice. Therefore, future research should focus elucidating the specific relationship between cause and cell type of human lung cancer by means of animal experiments on lung cancer that give attention to the specificities of each experimental animal and the origin of the resultant lung tumor.

Adenocarcinoma↗
PubMed1987

[Magnetic resonance imaging (MRI) of pituitary adenomas].

MRI of 20 patients, 17-82 years old, with pituitary adenomas confirmed histopathologically, and 30 normal patients without pituitary dysfunction were reviewed. The studies were performed with a 0.5 Tesla MR scanner with a slice thickness of 10 mm. Inversion recovery sequences were employed as T 1-weighted examination, with repetition time (TR) of 2100-2500 msec, an inversion time (TI) of 600 msec and an echo time (TE) of 40 msec. The T 2-weighted examination had a TR of 1800-2500 msec and a TE of 120 msec. T 1-weighted images were obtained in all cases and T 2-weighted images in 14 cases. Spin echo images with a TR of 600-1000 msec and a TE of 40 msec (SE 40/600-1000) were also obtained in 14 cases. On T 1-weighted images, 20 adenomas were classified into six groups, according to their signal intensities; marked low intensity (1), low intensity (1), isointensity (11), high intensity (3), marked high intensity (1) and mixed intensity (3). On T 2-weighted images, 14 adenomas were classified into five groups; low intensity (1), isointensity (2), high intensity (4), marked high intensity (6) and mixed intensity (1). On SE 40/600-1000 images, 14 adenomas were also classified into four groups; low intensity (8), high intensity (2) and mixed intensity (3). Two adenomas with recent intratumoral hemorrhage had marked high intensity on both T1 and T2-weighted images. SE 40/600-1000 images were useful in evaluating the size and the extent of the visual pathway was best appreciated on IR images. Comparison between normal and involved cavernous sinus by adenomas was made.

Adenoma↗
PubMed1986

Pituitary dwarfism: CT evaluation of the pituitary gland.

The pituitary glands of 12 patients, aged 4-20 years, with pituitary dwarfism and of 15 age-matched control patients were evaluated with contrast-enhanced, high-resolution computed tomography (CT). In control patients, CT clearly demonstrated pituitary glands and stalks, 2.5-9.0 mm in height (average, 5.7 mm +/- 1.8). In the 12 patients with pituitary dwarfism, CT did not demonstrate the gland or stalk in four; CT faintly showed only the stalk in another four and showed a small gland (less than 2 mm in height) and a small to normal stalk in the remaining four. Eleven of the 12 patients had a birth history of breech presentation. Possible causes of pituitary dwarfism are discussed.

Adolescent↗
PubMed1986

[Effects of chromium compounds on the respiratory system. Part 4. Long-term inhalation of chromic acid mist in electroplating to ICR female mice].

In order to determine the effect on the respiratory system of long-term inhalation of chromic acid in electroplating, histopathological examination was performed on mice (ICR, female, n = 50) exposed to chromic acid mist for 12 months (30 min/d, 2 d/wk), by using the authors' miniaturized chromium electroplating system. After 12 months' exposure, the mice were kept for 6 months without exposure. In the upper respiratory tract, round perforations were found in the nasal septum in 6 mice that were sacrificed or died after 10 months' exposure. The perforations were located near the point of the septum, the thinnest part of the nasal septum, and were of pin-hole sige. On the epithelium of the trachea and bronchus, loss of cilia, proliferation of goblet cells or basal cells, and squamous metaplasia were observed in almost all of the exposed mice. These changes appeared to be more advanced in mice exposed for a longer period. In the lung, development of benign adenoma was observed in one mouse in the 6- to 9-months' exposure group, in three in the 10- to 14-months' exposure group and in one in the group examined after 15 to 18 months. Furthermore, adenocarcinomas were found in two mice, one of which died at 17 months and the other was sacrificed 18 months after initiation of exposure. In conclusion, the finding that adenomas and adenocarcinomas were observed in mice exposed to chromic acid mist suggests the need to give careful attention to the possibility of respiratory cancers in chromium electroplating workers.

Adenocarcinoma↗
PubMed1986

[Carcinogenicity in mice by inhalation of benzotrichloride and benzoyl chloride].

Benzotrichloride and benzoyl chloride are suspected to be causative agents of lung cancer and maxillary malignant lymphoma of workers employed in factories producing benzoyl chloride. The present study was undertaken to evaluate the carcinogenicity in mice of inhaling benzotrichloride and benzoyl chloride. Mice inhaled benzotrichloride and benzoyl chloride vapor for 30 min/d for 2 d/wk for 5 months, and each animal was followed for several month without subsequent exposure. Tumor developed in the lung, skin and lymphatic tissues at high incidences in mice inhaling benzotrichloride. By benzotrichloride vaporized at 50 degrees C, the incidence of pulmonary tumors was 53.1% (17/32, p less than 0.001), that of skin tumors was 25% (8/32, p less than 0.02), and that of malignant lymphoma was 25% (8/32, p less than 0.02) observed at the 10th month after exposure. These are significantly higher than that observed in control mice. In mice exposed to benzotrichloride vaporized at room temperature, the incidence of pulmonary tumors was 81.1% (30/37), that of skin tumors was 27.0% (10/37), and that of malignant lymphoma was 10.8% (4/37) observed at the 15th month after exposure. On the other hand, by benzoyl chloride vaporized at 50 degrees C, the incidence of pulmonary tumors was 10.7% (3/28) and that of skin tumors was 7.1% (2/28), but these incidences did not show any significant difference from the controls. These results suggest that the carcinogenicity of benzotrichloride is much higher than benzoyl chloride and that benzotrichloride is the primary cause of malignancies developing among workers engaged in manufacturing benzoyl chloride.

Adenocarcinoma↗