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Biomedical subjects

T Obara

Publications and source records attributed to T Obara.

At least 217 records · Page 12Linked to original sources
PubMed1987

Pancreatic tumor antigen in transplantable adenocarcinomas induced by N-bis(2-hydroxypropyl)nitrosamine in hamsters.

An attempt was made to detect a pancreatic tumor antigen (PTA) in transplantable pancreatic adenocarcinomas induced by N-bis(2-hydroxypropyl)nitrosamine (DHPN) in hamsters. Antibody against antigenic protein was raised by immunizing rabbits with whole homogenate of the tumors transplanted into the back of hamsters. PTA was purified by affinity chromatography and shown to have the physicochemical properties of a glycoprotein with a molecular weight of 800,000, migrating in the beta regions upon agarose gel electrophoresis. Loss of immunological properties was observed after heating at 65 degrees C for 30 min. Enzyme immunoassay revealed that the levels of PTA in the serum and tissue showed a positive correlation with the induction of the presence of tumor, and size of the tumor. It is tentatively suggested that PTA values above 150 ng/ml serum are indicators of tumors, because in normal hamsters the PTA range is from 25 to 130 ng/ml serum. Immunohistochemically, PTA was demonstrated to be localized within the cytoplasm of epithelial tumor cells of well-differentiated tubular adenocarcinomas.

Adenocarcinoma↗
PubMed1987

Follicle structure-dependency of thyroglobulin and thyroxin staining in the thyroid glands of Graves' disease.

H.E. morphology of the thyroid glands from 170 patients with Graves' disease was studied, and the thyroid follicles were classified into two main groups: (1) F pattern, in which the follicles show circle/ellipse on cut sections; (2) P pattern, in which the follicular epithelium protrudes into the lumen or a follicle, is accompanied by proliferation of tubular or microfollicular structures. Studies on three serial sections of 88 thyroid glands stained with hematoxylin and eosin, thyroglobulin (TG), and thyroxin (T4), respectively, revealed the followings: (i) TG/T4 staining is dependent on the follicle structure (i.e., F or P); while the epithelium and colloid including scalloped vesicles in F follicles generally exhibited a direct relationship between TG and T4 staining, those in P follicles often showed an intense TG, but negative T4 staining. (ii) The results of morphological and immunohistochemical studies of P follicles among the cases are consistent with the view that P follicles are in the process of proliferation of immature daughter follicles from a main follicle and of their maturation. (iii) P follicles of Graves' thyroid glands were evaluated as possible non-neoplastic counterparts of well-differentiated follicular and papillary tumors.

Adult↗
PubMed1987

Acute suppurative thyroiditis in appearance of unusual neck mass.

We report on three adult cases of acute suppurative thyroiditis due to infection through a piriform sinus fistula. In these cases, the lesion did not exhibit the clinical symptoms characteristic of acute suppuration, but appeared as an unusual neck mass. Repeated barium meal roentgenograms, however, demonstrated the internal fistula in two of the three cases. Acute suppurative thyroiditis may not be so rare even in adults. When acute suppurative thyroiditis occurs in adults with scanty symptoms of acute suppuration, the piriform sinus fistula could easily go undetected. Recognition of acute suppurative thyroiditis in adults per se seems to be important for correct diagnosis.

Acute Disease↗
PubMed1987

Eleven cases of nonfunctioning parathyroid cyst--significance of needle aspiration in diagnosis and management.

Eleven cases of nonfunctioning parathyroid cyst are reported. Ultrasonography revealed the cystic nature of the asymptomatic lump in the neck. Clear watery fluid obtained by needle aspiration and the increased parathyroid hormone concentration in the fluid established the diagnosis. Five patients, in four of whom the cysts reappeared after one (3 cases) or seven (1 case) needle aspirations, underwent surgical resection of the cysts. Six other patients were followed conservatively after the aspiration maneuver. In four patients with enough follow-up time for evaluation, the cyst fluid has not reaccumulated 5, 2 and 2 years after only one aspiration, and 1 year after two aspirations. In one patient, the cyst reappeared 9 months after the initial aspiration. Simple percutaneous aspiration may be curative in some cases of nonfunctioning parathyroid cysts.

Adult↗
PubMed1987

Transient thyrotoxicosis associated with infarction of a large thyroid adenoma.

We report a 46-year-old male patient with a transient thyrotoxicosis that seems to have been caused by hemorrhagic infarction of a cold thyroid nodule. The serum level of triiodothyronine was markedly but transiently elevated, while the serum thyroxine level remained within the normal range. The resected nodule, measuring 8 x 7 x 5 cm, showed extensive degeneration and necrosis with viable follicles left only at the margin of the nodule. A transient thyrotoxicosis due to acute hemorrhagic infarction of autonomously functioning thyroid nodules has already been reported. This case showed that the phenomenon could occur even in cold thyroid nodules. Its implications were discussed in relation to the high incidence of impaired TSH response to TRH in patients with nodular goiter.

Adenoma↗
PubMed1987

Biphasic effects of dexamethasone on growth hormone release in vitro.

The effect of dexamethasone (Dex) on growth hormone (GH) release was examined in vitro in monolayer culture of normal rat pituitary cells and human somatotropinoma cells from patients with acromegaly. In either cell strain, Dex, at a concentration of 50 nM initially inhibited, but later (48 less than or equal to h) potentiated, the release of GH into the medium, with or without growth hormone releasing hormone (GHRH). The intracellular GH was significantly increased by 4-hour incubation with Dex in rat cell cultures. These results indicate a biphasic effect of glucocorticoids on GH release, irrespective of the origin of somatotrophs, and that the initial inhibitory effect is probably caused by inhibition of the release.

Acromegaly↗
PubMed1987

Papillary carcinoma of the thyroid arising from dyshormonogenetic goiter.

A case of thyroid papillary carcinoma associated with dyshormonogenetic goiter is reported. The patient, a 35-year-old male, has been on thyroid hormone therapy since the age of three because of familial dyshormonogenetic goiter. He developed a distinct tumor in the right lobe, which was suggestive of carcinoma upon physical as well as ultrasonographic examination. Total thyroidectomy was performed, since a frozen section disclosed a focus of papillary carcinoma and the possibility of future development of further malignancy in any remaining thyroid tissue was considered. The patient is currently well with complete thyroid hormone supplementation one and a half years after the operation.

Adult↗
PubMed1987

Dichotomic action of glucocorticoids on growth hormone secretion.

The mechanism of apparently discrepant actions of glucocorticoids (GC) on GH secretion, in vivo suppression and in vitro potentiation, was studied in rats. Dexamethasone (Dex), at the concentration of 50 nmol/l, potentiated basal and GHRH-stimulated GH release from monolayer culture of normal rat pituitary cells in 48 h. On the other hand, in vivo administration of Dex, 165 micrograms daily for 3 days, consistently suppressed serum GH levels in female rats. In these rats, the hypothalamic content of immunoreactive (IR) SRIH was significantly increased, whereas that of IR-GHRH was significantly decreased in comparison with the untreated rats. Bioassayable GH-releasing activity was also lower in Dex-treated rats. These findings indicate that the suppressing effect of GC on GH release in vivo is, at least partially, due to the increase in hypothalamic SRIH release and probably also to the decrease in GHRH release, and these effects surpass the potentiating effect of GC on GH release at the pituitary level, resulting in a net inhibitory effect in vivo.

Animals↗
PubMed1987

A case of acute diffuse lymphocytic meningoencephalitis.

"Acute diffuse lymphocytic meningoencephalitis" is characterized neuropathologically by swelling of the brain and an unproportionally slight degree of inflammatory findings. Although many cases of this encephalitis have been reported in Japan, it was scarcely reported in other countries. The present case is a girl who had been well until fifteen years of age. She became psychotic on the 7th day after she seemed to have caught a cold. She fell into coma on the 15th day, then neurologic symptoms, such as nuchal rigidity and athetoid movement became prominent. She developed the status epilepticus with a high temperature of 41 degrees C, and died on the 23rd day. Although there was an increase of mononuclear cells in the cerebrospinal fluid (32/microliters), various antiviral titers were normal both in serum and cerebrospinal fluid. Neuropathologic changes were edema, perivascular lymphocytic infiltration in leptomeninges and parenchyma, and proliferation of rod-shaped microglia particularly prominent in the cerebral cortex and hippocampus. It is peculiar that thickening of leptomeninges formed by collagen fibers and inflammatory cells was observed. On the systemic study, centrolobular fatty change of the liver was found. This case had to be differentiated from several other neuro-psychiatric illnesses. The problems were discussed clinically and neuropathologically.

Acute Disease↗
PubMed1986

Vascular changes associated with growth of primary and transplantable pancreatic adenocarcinomas induced in Syrian golden hamsters by N-nitrosobis(2-oxopropyl)amine (BOP) and N-nitrosobis(2-hydroxypropyl)amine (BHP).

Microangiographic and histological methods were used to characterize vascular structure of primary and transplantable pancreatic adenocarcinomas induced by propylnitrosamines in Syrian golden hamsters. Originally of well-differentiated tubular morphology, serial transplantation subcutaneously to the back region was not associated with change in histopathological pattern or increase in invasive or metastatic potential. In contrast, pancreatic subserosal grafts displayed prominent invasion of surrounding tissues. Whereas primary tumors induced by N-nitrosobis(2-oxopropyl)amine (BOP) and those transplanted subserosally were characterized by hypovascularity, subcutaneous transplantation resulted in hypervascular tumors. Encasement, which is defined as invasion of normal arteries by the tumor, showing uneven caliber, irregular outline, appeared on earlier microangiographic findings rather than luminal irregularity, which is change of tumor vessels in neovascularization and occurs in tumor blood vessels subsequent to transplantation. The vascular component of subcutaneously transplanted tumors had a total vessel length ranging from 9.2 +/- 0.7 mm to 18.1 +/- 1.1 mm, a total vessel surface from 2.5 +/- 0.4 mm2 to 9.3 +/- 0.6 mm2 and a total vessel volume from 0.07 +/- 0.02 mm3 to 0.49 +/- 0.04 mm3, indicating that the vessels were of relatively large diameter and short length.

Adenocarcinoma↗
PubMed1986

Comparative histochemical investigation of the glutathione S-transferase placental form and gamma-glutamyltranspeptidase during N-nitrosobis(2-hydroxypropyl)amine-induced pancreatic carcinogenesis in hamsters.

Immunohistochemical staining using anti-rat glutathione S-transferase placental form (GST-P) rabbit antibody and enzyme histochemical staining for gamma-glutamyltranspeptidase (gamma-GT) were investigated in putative preneoplastic lesions and adenocarcinomas in the pancreas of Syrian golden hamsters treated with N-nitrosobis(2-hydroxypropyl)amine (BHP). Areas with ductular proliferation, ductal hyperplasia, and intraductal carcinoma were strongly positive for GST-P binding and negative for gamma-GT. Cystic adenoma, microcarcinoma, and carcinomas were constantly positively stained by GST-P and partially positive for gamma-GT. GST-P appears to be useful as a positive marker for putative preneoplastic lesions in pancreatic carcinogenesis. Since normal acinar cells are strongly positive for gamma-GT, the findings might suggest that acinar cells contribute to the development of cystic adenoma, microcarcinoma, and carcinomas.

Animals↗
PubMed1986

Epidermoid metaplasias of xenotransplanted human tracheobronchial epithelium.

Repopulation of rat tracheas of human tracheobronchial epithelial cells obtained from intermediate autopsies was achieved by introducing into de-epithelialized rat tracheas either pieces of donor tissue containing respiratory mucosa or epithelial cells produced by an in vitro amplification of these cells. After tracheas were sealed, and transplanted into the subcutaneous tissues of nude mice, a newly formed epithelium migrated over the denuded luminal surface. During this process, regenerative epidermoid metaplasias, consisting of the growth of thin stratified epithelium with keratinization but without atypia was observed. Four weeks after xenotransplantation, most of the luminal surface was covered by columnar epithelium with occasional patches of epidermoid metaplasia. When this epithelium was exposed to 7,12-dimethylbenzo[a]anthracene (DMBA) a thick epidermoid metaplasia with mild to moderate atypia was observed. This type of epithelium is seen one to three months after insertion of the DMBA-containing pellets into the tracheal lumen. Immunohistochemical staining with antikeratin monoclonal antibodies AE1 and AE3 revealed increased immunostaining in both regenerative and DMBA-induced metaplasias compared with that of untreated normal mucociliary epithelium. Although no differences between the two types of metaplasias were detected with AE1 and AE3, the use of involucrin immunostain showed important differences. Normal respiratory epithelium did not contain involucrin, but this protein was seen in the surface layer of regenerative epidermoid metaplasias. In DMBA-induced metaplasias, involucrin was found not only in the superficial cells but was also present in numerous suprabasal cells. The hyperplastic nature of these carcinogen-induced lesions, together with the presence of cellular atypia and an altered involucrin distribution pattern, suggest a preneoplastic state.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1986

Regulation of taurine transport in rat skeletal muscle.

Taurine concentration of soleus muscle (SL, slow-twitch) was initially about twofold higher than that of extensor digitorum longus muscle (EDL, fast-twitch). Taurine concentration in gastrocnemius muscle (GC) was intermediate between that of EDL and SL. Four days after sciatic nerve section, taurine concentration in the EDL but not in the SL was increased by 2.5-fold. The increase was not due to the muscle atrophy and was observed 28 days after denervation. Tenotomy did not increase the total taurine content of the EDL. The increase in taurine concentration of the denervated EDL was prevented by simultaneous ingestion of guanidinoethane sulfonate, a competitive inhibitor of taurine transport. The initial and the maximal rates of [3H]taurine uptake were significantly higher in SL than in EDL. Denervation dramatically accelerated the initial and the maximal rates of the transport in EDL, whereas it significantly reduced those in SL. In contrast, the electrical stimulation of sciatic nerve accelerated the uptake of taurine by EDL and SL of the control but not of the curare-treated rats. These results suggest that transport of taurine into rat skeletal muscles is regulated differently by neural information and by muscular activity, and that the regulation is dependent on the muscle phenotype.

Animals↗
PubMed1986

Low density lipoprotein receptor activity in the guinea pig adrenal cortex. I. Zonal characterization and response to adrenocorticotropin.

The binding of [125I]iodo-low density lipoprotein ([125I]iodo-LDL) to isolated membranes was determined for the outer (glomerulosa/fasciculata) and inner (reticularis) zones of the guinea pig adrenal cortex. Binding of [125I]iodo-LDL to membranes from both zones was found to be highly specific and dependent on the presence of divalent cations, such as calcium. Saturation analysis revealed that the maximum high affinity binding capacity was similar for both zones under control conditions (approximately 400 ng/mg protein). When ACTH was administered, however, the maximum high affinity binding capacity increased in the outer zone by at least 3-fold, while there was no significant change for the inner zone. It was also noted that dexamethasone administration decreased [125I]iodo-LDL high affinity binding activity to less than half the control level in the outer zone without altering the binding activity in the inner zone. The cholesterol content in the outer zone was 2-3 times greater than that in the inner zone. When ACTH was administered, the concentration of cholesterol decreased significantly in both zones. Thus, ACTH appeared to influence cholesterol metabolism in the outer and inner adrenocortical zones, but was able to modulate LDL receptor activity only in the outer zone.

Adrenal Cortex↗
PubMed1986

Further data supporting episodic degenerative discharge of thyroid hormone from nodular goiters.

To elucidate the features of thyroid hormone secretion under conditions of impaired circulation, blood samples were withdrawn at operation from thyroid and peripheral veins of 23 patients with thyroidal and non-thyroidal diseases. They were taken from the respective veins simultaneously, when the arterial supply to the thyroid tissue was partially occluded by surgical manipulation. It was found that triiodothyronine was preferentially, as compared with thyroxine, secreted from the thyroid, irrespective of the disease. Serum levels of thyroglobulin were also markedly elevated in the thyroid vein. These results suggest that episodic degenerative discharge of thyroid hormone from nodular goiters may be a cause of impaired or blunted TSH response to TRH, frequently observed in patients with common nontoxic nodular goiters.

Goiter, Nodular↗
PubMed1986

[The effects of fur on the thermal regulation of mice (Mus musculus)].

In order to ascertain the thermal insulation function of fur in mice, food and water intakes and rectal and skin temperatures were observed in Jcl: ICR mice and a group of the same species with their fur clipped, as well as BALB/C nu/+ and nu/nu mice. Food and water intakes increased as the ambient temperature dropped. The rectal temperature remained almost unchanged at ambient temperatures of from 18 to 30 degrees C. Skin temperatures were highest at side of the abdomen, lower at the neck, and lowest at the head. There was a tendency for skin temperatures to increase as the ambient temperature rose. The skin temperatures of mice with fur were higher than those of mice without fur. The thermal insulation of fur was 0.25, 0.14 and -0.06 clo at 18, 22, 26 and 30 degrees C in ICR mice, and 0.36, 0.01, 0.01 and -0.03 clo at 18, 22, 26 and 30 degrees C in BALB/C mice, respectively. These results confirm that heat loss from the skin at low temperatures could be prevented by the presence of fur. It also appeared that the hairless mice mutant had a lower metabolic rate than the animals with their fur clipped.

Animals↗
PubMed1986

[Filter efficiency of commercial face masks in capturing particles and airborne bacteria].

The filter efficiency of seven kinds of commercial face mask for particles and airborne bacteria was tested in the wash room of a laboratory animal facility. The filter efficiency of the masks was 19 to 50%, as measured by the weight of particles with diameters below 10 micron, 22 to 71% for particles of the 0.3 micron level, 47 to 90% for the 1 micron level, and 90 to 99.6% for the 5 micron level. The filter efficiency for airborne bacteria was 35 to 81%. Among these even masks tested, glasswool surgery masks, three-sheet synthetic fiber masks with and without charcoal, and 28-sheet gauze masks with glass filter showed generally high efficiency, and single-sheet synthetic fiber masks, 18-sheet of gauze masks and gas masks showed low efficiency.

Animal Husbandry↗