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Biomedical subjects

A Shirota

Publications and source records attributed to A Shirota.

At least 19 recordsLinked to original sources
PubMed2000

Spontaneous and ethyl-nitrosourea-induced medullomyoblastomas in cerebellar vermis defect (CVD) mutant rats.

A 26-week-old female cerebellar vermis defect (CVD) rat, a mutant with cerebellar vermis defect and cerebellar dysplasia, developed a brain tumor about 10 mm in diameter. Histopathologically, the tumor consisted of diffuse proliferation of small round to ovoid cells with hyperchromatic nuclei, occasionally containing round to strap-shaped myoblastic cells. Immunohistochemically, the small round cells expressed neuron-specific enolase and synaptophysin, indicating neuronal differentiation; myoblastic components reacted to desmin, myoglobin, and vimentin. Based on these findings, the case was diagnosed as a medullomyoblastoma (MMB). Furthermore, two cerebella tumors in CVD rats, which were induced by transplacental application of ethyl-nitrosourea, showed histopathology similar to the aforementioned case. MMB is a very rare tumor in humans and animals; thus, it is noteworthy that MMBs developed in CVD rats, involving the dysplastic cerebellum with abnormal migration of external granule cells.

Animals↗
PubMed2000

Effects of daytime activity on nocturnal sleep in the elderly.

This study investigates the relationship between the level of daytime activities and nocturnal sleep in the elderly using the wrist actigraph and ambulatory polysomnograph system. Five male and five female subjects (mean age = 73.8+/-3.05 years; range 69-77 years) participated in this study. The level of daytime activity was positively correlated with the sleep efficiency of the subsequent night only for male subjects, who were shown to be less active during the daytime. The results imply that increments in the time spent on physical activities may improve the quality of nocturnal sleep in elderly male subjects.

Aged↗
PubMed2000

Restorative effects of a short afternoon nap (<30 min) in the elderly on subjective mood, performance and eeg activity.

This study investigated the effects of a short afternoon nap (<30 min) in the elderly on subjective mood, performance and electroencephalograms (EEG). Ten healthy elderly persons who habitually napped in the afternoon three or more times a week participated in the present study. They participated in two experimental conditions with an interval of more than five days. In the nap condition, the participants went to bed at 13:00 hours and slept for 30 min, whereas they just had a rest while watching television in the no-nap condition. In both conditions, subjective sleepiness, fatigue, performance and EEG activities with eyes opened and closed were repeatedly measured before and after the nap or rest. The nap significantly reduced subjective sleepiness and fatigue in the afternoon. It also improved performance levels and EEG theta, alpha 1 or alpha 2 band activities with eyes opened and closed. These findings suggest that a short afternoon nap is useful for the elderly in maintaining their daytime psychological, behavioral and physiological arousal at an adequate level.

Affect↗
PubMed1999

Effects of volitional lifestyle on rest-activity cycle in the aged.

The present study investigated the relationship among volitional lifestyle, activity and sleep in the aged. We selected 28 subjects over 65 years of age to survey volition to lifestyle. High-volitional group (14 Ss, mean age: 74.1 years, seven males and seven females) and low-volitional group (14 Ss, mean age: 73.0 years, seven males and seven females) were identified by the scale of self-confidence and the Philadelphia Geriatric Center morale scale. Wrist activities were monitored by Actigraph for 10 or 14 consecutive days. The subjects recorded sleep logs by themselves for those days. It was found that high volitional aged individuals had a relatively well structured sleep in comparison with low volitional aged individuals, and that most of them took a clock dependent habitual nap around 14.00 h. On the other hand, low volitional aged individuals had a relatively poor structured sleep, and took a nap time-dependently after 8 h from the morning rising time. These results suggest that high volitional aged individuals build a short nap into their well organized sleep-life habits.

Aged↗
PubMed1999

Effects of a daytime nap in the aged.

This study evaluated the effects of the daytime nap on performance, mood and physiological measures in aged individuals Participants were six healthy aged persons (M=72.2 years old) who habitually napped in the afternoon three or more times a week. They participated under two conditions with an interval of 1 week. In the nap condition, the subjects went to bed at 13:00 h and slept for 30 min. In the rest condition, they just watched television. In both conditions, electroencephalogram (EEG), blood pressure, mood and performance were measured before and after a nap or rest. The daytime nap improved performance, decreased subjective sleepiness and fatigue, and attenuated EEG alpha band activity. Moreover, following a nap diastolic blood pressure significantly decreased. These findings suggest that a habitual daytime nap helps aged individuals to maintain their daytime physiological, psychological and behavioral arousal at an adequate level.

Affect↗
PubMed1998

Analysis of aberrant neuronal migrations in the hereditary cerebellar vermis defect (CVD) rat using bromodeoxyuridine immunohistochemistry.

The hereditary cerebellar vermis defect rat (CVD) is a new neurological mutant characterized by cerebellar vermis defect and a dysplastic cerebellum, especially in the cerebello-pontine junctions. In this study, the cytokinetics of neuronal migrations in the CVD were analyzed using 5-bromo-2'-deoxyuridine (BrdU) as a labeling marker. From embryonic day 21, the CVD cerebellum was small in size with retarded foliation, but no significant differences were detected in the migration pattern of the BrdU-labeled cells between the unaffected controls and the CVD during the prenatal period. On postnatal day 0 (P0), heterotopic Purkinje cells, demonstrable by calbindin immunohistochemistry, were seen in the dorsal pons of the CVD. From P4, BrdU-positive external granule cells (EGCs), which were labeled by BrdU injection on P2, began to penetrate the pons. From P5, the EGCs aggregated around the blood vessels, leading to a disturbance of the cerebellar lamination both in the cerebello-pontine junctions and in the cerebellar hemispheres. Thereafter, the BrdU-labeled cells in the perivascularly aggregated EGCs migrated radially, and formed internal granular layers around the vessels, indicating an aberrant perivascular migration of the EGCs. These findings suggest that the EGC dislocation was preceded by an aberrant settlement of the Purkinje cells, and that the perivascularly aggregated EGCs resulted in cerebellar dysplasia in the CVD.

Aging↗
PubMed1998

Effects of volitional lifestyle on sleep-life habits in the aged.

This study investigates the relationship between a volitional lifestyle and sleep-life habits in the aged. High volitional group (HVG: n=45, 26 men and 19 women, mean age 73.0 years) and low-volitional group (LVG: n=45, 27 men and 18 women, mean age 72.2 years) were grouped using the scale of self-confidence. It was found that high volitional aged individuals had a relatively well structured sleep, and that most had become accustomed to taking an appetitive nap (an individual with a mean wake time shorter than the average) in the mid-afternoon without experiencing insomniac problems.

Aged↗
PubMed1998

C-cell adenoma containing variously sized thyroid follicles in a horse.

A thyroid gland tumor, showing unusual histology, was identified in a 13-year-old male Andalusian horse. Microscopically, the tumor consisted of neoplastic proliferation of C-cell (parafollicular cell) with cytoplasmic fine granules, containing diffusely distributed, variously sized colloid-containing follicles. Immunohistochemically, the neoplastic C-cell were positive for calcitonin and follicleforming epithelial cells showed a positive reaction for thyroglobulin. Ultrastructurally, membrane-bound secretory granules up to 250 nm in diameter were found in the cytoplasm of the parafollicular cells, whereas the follicular epithelial cells had microvilli, junctional complex, and well-developed endoplasmic reticulum.

Adenoma↗
PubMed1986

Estrogen and progesterone receptors in gastric cancer.

Cancerous tissue from 86 patients with primary gastric cancer were examined for the presence of receptors for estrogen (ER) and progesterone (PgR). ER and PgR were present in 8 (15.4%) and 5 (9.6%), respectively, of 52 male patients, 9 (26.6%) and 7 (20.6%), respectively, of 34 female patients, a total of 17 (19.8%) and 12 (14.0%), respectively. One male patient (1.9%) and 4 female patients (11.8%) had both ER and PgR, and 40 male (76.9%) and 22 female patients (64.7%) showed no ER or PgR. The binding activity ranged from 6 to 200 fmol/mg protein for estradiol and from 5 to 58 fmol/mg protein for progesterone. ER- and/or PgR-positive cases were characterized grossly as Borrmann type 4, and microscopically as diffuse type with scirrhous growth pattern. The presence of ER and/or PgR in some gastric cancers indicates the possibility that sex hormonal factors are involved in these tumors.

Adult↗
PubMed1986

Ultrastructural studies of experimental endotoxin shock in the liver and spleen: therapeutic effects of low-dose heparin on reticuloendothelial disturbances.

To determine the effects of low-dose heparin on the reticuloendothelial system in shock, rats were subjected to intraperitoneal administration of E coli endotoxin. Alterations such as degeneration and necrosis of the Kupffer cells and sinusoidal endothelial cells were observed in the livers of the non-heparin-treated animals 4 hours after the administration of the endotoxin. These changes progressed with time. Kupffer cells in the heparin-treated rats appeared undisturbed up to 8-12 hours post endotoxin challenge. Phagocytosis of cell remained slight in the heparin-treated rats. The mortality rate of the heparin-treated group was 10% with LD50 endotoxin (7.6 mg/kg). The mortality rate of the untreated control group 24 hours after administration was 50%. However, when endotoxin was administered in a dosage of 30 mg/kg (MLD), the mortality rate of the heparin-treated rats was 60%--10% greater than that of controls (P less than 0.05).

Animals↗
PubMed1983

[Recent advances in research on the intestinal metaplasia of the stomach].

Intestinal metaplasia of the stomach is classified into two types, complete and incomplete, by enzymatical, mucin histochemical and histological differences. Complete type resembles the small intestine while incomplete type does not. But, even complete type differs from the small intestine from the point of cytological observations. Vascular structures of the metaplastic mucosa are different from those in the mucosae of stomach, small and large intestines. Focal intestinal metaplasia can be induced in rats by a gastric carcinogen, N-propyl-N'-nitro-N-nitrosoguanidine or regeneration after ulceration with 0.5 NaOH. There is no solid evidence that intestinal metaplasia is a precancerous change of the stomach. However, the patients with extensive intestinal metaplasia of the stomach belong to the high risk group for the gastric cancer. Therefore, careful follow-up studies are needed for these patients using endoscopy by dye-staining method.

Animals↗
PubMed1982

Effect of doxorubicin on liver regeneration and host survival after two-thirds hepatectomy in rats.

The effects of doxorubicin (Adriamycin) on regenerating liver were studied after two-thirds hepatectomy in rats. In Group I, standard two-thirds hepatectomy was performed. Doxorubicin in a dose of 2 mg/kg (Group II) and 6 mg/kg (Group III) was given intravenously immediately after the same hepatectomy. In Group IV, 6 mg/kg doxorubicin was given after sham operation. Animal survival, body weight restoration, wet weight and mitotic activity of remnant livers, and serum albumin concentrations were examined 1-14 days after operation. The survival rates were 95.5% in Group I, 76.8% in Group II, 10.3% in Group III, and 96.7% in Group IV. Although there were no differences in the residual liver weights among the hepatectomized groups, treatment with doxorubicin induced substantial, dose-dependent suppression and delay of liver cell division. Serum albumin levels dropped considerably in hepatectomized, doxorubicin-treated rats. Light microscopy showed degenerative changes with a single cell necrosis of hepatocytes in Group III. Death among rats hepatectomized and treated with doxorubicin was considered to be mainly due to the failure of residual livers since albumin synthesis was impaired and no marked changes were seen in vital organs other than the liver. For patients with hepatoma, the present results may indicate that the administration of adjuvant chemotherapy with doxorubicin, when necessary immediately after hepatectomy, should be performed with great care. In the absence of such necessity, doxorubicin should be withheld until life-sustaining liver regeneration has taken place.

Animals↗
PubMed1982

Sequential morphological studies of the esophageal carcinoma of rats induced by N-methyl-N-amylnitrosamine.

N-Methyl-N-amylnitrosamine was given to male Wistar rats in the drinking water at a concentration of 0.003% for 8 weeks. Three rats were autopsied weekly from the first to the 25th week. The stages of hyperplasia, dysplasia and squamous cell carcinoma in the esophagus were chronologically observed. Hyperplasia and dysplasia were found by the 6th week and continuously observed until the end of the experiment. Early squamous cell carcinomas were found in the 13th week. They showed endophytic or exophytic growths. Histologically, the endophytic growths were well-differentiated squamous cell carcinomas and the exophytic growths were poorly-differentiated. Advanced carcinomas were first found in the 15th week and were almost well-differentiated. Carcinomas were not found in papillomas. The incidence of carcinomas increased with time, being 9 out of 15 rats (60%) in the final 21st through 25th weeks. Lymph node metastasis was found in one rat, killed at the 24th week.

Animals↗
PubMed1981

Cytochemical localization of alkaline phosphatase in intestinal metaplasia of the human stomach.

Alkaline phosphatase in the brush border of areas of intestinal metaplasia of human stomach was studied cytochemically. All absorptive cells in the upper part of the villi of the duodenum had strong alkaline phosphatase activity but, in areas of intestinal metaplasia, the metaplastic glands consisted of alkaline phosphatase-positive and negative absorptive cells. Alkaline phosphatase activity was found in tall dense microvilli of absorptive cells in areas of intestinal metaplasia and in the duodenum. However, in some areas of metaplastic epithelium the activity was very weak in some tall dense microvilli of absorptive cells but strong in those of neighbouring absorptive cells. No alkaline phosphatase activity was found in short sparse microvilli of absorptive cells in areas of intestinal metaplasia. The difference in alkaline phosphatase activity in microvilli of different cells in areas of intestinal metaplasia, which is not seen in the duodenum, indicates abnormal morphological and enzymatic differentiation intestinal metaplasia.

Alkaline Phosphatase↗