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T Obara

Publications and source records attributed to T Obara.

At least 235 records · Page 13Linked to original sources
PubMed1986

[Circadian rhythm of air-borne bacteria and dust particles in a mouse breeding room].

The circadian rhythm of air-borne bacteria and dust particles in a mice breeding room was studied at 1-hour intervals on the first, third and fifth day after accommodation of the animals. The numbers of air-borne bacteria in the room increased day by day after accommodation, and showed a circadian rhythm which went down at about noon and rose with three peaks at about 20:00, 1:00 and 8:00. The numbers of dust particles tended to decrease from day to day, and they showed almost the same circadian rhythm as the air-borne bacteria. Correlations between air-borne bacteria and dust particles were not significant for each particle level on the first day, but were significant for all the particle levels of 0.3, 1, 2, and 5 microns at the third day, and were also significant at particles levels of 0.5 micron or more on the fifth day.

Air Microbiology↗
PubMed1986

Effects of phenobarbital and secondary bile acids on liver, gallbladder, and pancreas carcinogenesis initiated by N-nitrosobis (2-hydroxypropyl)amine in hamsters.

The effects of dietary administration of phenobarbital [(PB) CAS: 50-06-6] or the secondary bile acids, deoxycholic acid [(DCA) CAS: 83-44-3] and lithocholic acid [(LCA) CAS: 434-13-9], on tumorigenesis in the liver, gallbladder, and pancreas were investigated in male Syrian golden hamsters after carcinogenic initiation by N-nitrosobis(2-hydroxypropyl)amine [(BHP) CAS: 53609-64-6]. BHP [500 mg/kg (body wt)] was injected sc once weekly for 5 weeks. The animals were then maintained on a basal diet or a diet containing either 0.05% PB, 0.1% DCA, 0.5% DCA, or 0.5% LCA for 30 weeks. DCA enhanced the development of cholangiocarcinomas without influencing that of hepatocellular lesions. PB promoted the induction of hepatocellular carcinomas but not that of cholangiocarcinomas. LCA was without effect on the induction of either hepatocellular carcinomas or cholangiocarcinomas. DCA at a dose of 0.5% enhanced the induction of polyps in the gallbladder. Both DCA, at a dose of 0.1%, and LCA significantly enhanced the induction of pancreas carcinomas. PB had no effect on the induction of polyps in the gallbladder or of pancreas carcinomas. These data document that different tumors may be differentially promoted following initiation with a common carcinogen.

Adenoma, Bile Duct↗
PubMed1986

Justification of conservative surgical treatment of childhood thyroid cancer: report of eleven cases and analysis of Japanese literature.

Eleven thyroid carcinoma patients of 15 years old and under are reported. They represent only 1.3% of our personal series of 861 thyroid carcinoma cases. One case died from undifferentiated carcinoma of the thyroid. However, the other 10 cases of papillary or follicular carcinoma are all alive, in spite of the apparently advanced stage of the disease at the time of operation in most of the cases. From our experience and analysis of 127 cases of childhood thyroid cancer reported in the Japanese literature, it is suggested that childhood thyroid cancer constitutes an extreme case of thyroid cancer occurring in the adolescent and young adult periods, and that rather conservative surgical treatment, avoiding total laryngectomy, and preserving the recurrent laryngeal nerve and the parathyroid glands as far as possible, usually suffices for treatment. In these Japanese cases, radiation did not appear to have been an important causative factor of childhood thyroid cancer.

Adenocarcinoma↗
PubMed1986

Rapid detection of xenotransplanted human tissues using in situ hybridization.

A rapid and sensitive method for the identification of human tissues xenotransplanted in nude mice was developed. An in situ hybridization technique made it possible to distinguish between cells of human origin and cells of murine origin in formalin-fixed paraffin sections. High-molecular-weight DNAs extracted from human or mouse tissues were sonicated, nick-translated with 32P-dCTP, and used as hybridization probes. Dot blot hybridization of 32P-labeled probes revealed clear species-specific signals. Formalin-fixed paraffin-embedded tissue samples from repopulated tracheal transplants, containing either human tracheal epithelial cells or human renal tubular cells, were used. Cells of human and murine origin were distinguishable by in situ hybridization with sonicated DNA probes. This method has several advantages; simple preparation of probes, high sensitivity, and applicability to formalin-fixed paraffin-embedded tissue sections. In situ hybridization with sonicated DNA probes should provide a powerful tool for verifying the human origin of xenotransplanted tissues in nude mice.

Animals↗
PubMed1986

Aggressive surgical approach for locally invasive papillary carcinoma of the thyroid in patients over forty-five years of age.

Aggressive radical resection was performed on 18 of 21 elderly patients with locally invasive-papillary carcinoma of the thyroid. Diagnostic studies, including computed tomographic and endoscopic examinations, were useful in allowing accurate determination of tumor extent. Radical resection usually consisted of total or subtotal thyroidectomy and neck dissection combined with excision of the affected organs, which in one case included a laryngotracheoesophagectomy (reconstruction of the digestive tract with a forearm free flap), a sleeve, or a window resection of the trachea in nine cases (immediate end-to-end anastomosis in all but one), a partial esophagectomy in two cases, and resection of the outer layer of the trachea or esophagus in six cases. After these operations, one patient died of rupture of the carotid artery, one died of cancer in 4 years, and one other died of unrelated disease. The other 15 patients are alive and well 1 to 5 years postoperatively, although additional exploration for nodal metastases was required in three patients. Aggressive resection therefore appears to be justified for control of locally advanced, differentiated carcinoma of the thyroid.

Aged↗
PubMed1985

Establishment and characterization of human myelomonocytic (TYS) and histiocytic (TYH) cell lines.

Two human hematopoietic cell lines (TYS and TYH) with monocytic characteristics were derived from the peripheral blood of a patient with acute myelomonocytic leukemia and of another with a follicular large-cell type of malignant lymphoma. The TYS cells, derived from the leukemia patient, revealed a monocytic appearance with microvilli at one side and had many granules and vacuoles. They showed strongly positive reactions with alpha-NBE, NASDAE, and AcP, and were reactive with monoclonal antibodies such as OKlal, 12 and Bl. The TYS cells, which phagocytized carbon particles and antibody-coated SRBC but not latex particles, released lysosomal enzymes and tumoricidal factor into the supernatant. The TYH cells, derived from the malignant lymphoma patient, had abundant cytoplasm and pseudopods detectable by electron microscopy with a monocytoid appearance and virus-like particles in the cytoplasm. They showed strongly positive reactions with alpha-NBE, NASDAE and beta-Gase, but no reactivity with monoclonal antibodies or with surface markers except Fc gamma-R. TYH cells phagocytized latex particles very well. Two different human monocyte-histiocyte lineages were thus established. During culture, the TYS and TYH cells maintained their characteristics over 28 and 16 months of passage, respectively.

Animals↗
PubMed1985

A case of gastric carcinoma associated with excessive granulocytosis. Production of a colony-stimulating factor by the tumor.

A patient with gastric carcinoma exhibited an excessive granulocytosis (58,000/microliter) preoperatively, in the absence of overt infection. After resection of the primary tumor, the peripheral leukocyte count decreased promptly to the normal value. In a search for a colony-stimulating factor (CSF), the tumor was transplanted into nude mice. A marked neutrophilia was observed in the tumor-bearing mice, suggesting the production of CSF by the tumor. Media conditioned by the primary culture of the tumor cells revealed the presence of CSF activity as well. CSF-producing carcinomas have been detected in various organs; nevertheless, no cases of gastric carcinoma have hitherto been described. It is of particular interest that in this patient hypercalcemia was not observed, although it often accompanied CSF-producing tumors reported previously. Therefore, it is suggested that this tumor secreted pure CSF and that the CSF produced by the tumor did not necessarily induce hypercalcemia.

Aged↗
PubMed1985

Atrial natriuretic peptides stimulate renal gluconeogenesis.

Atrial natriuretic peptide (5-28AA; ANP) and atrial extract (ANS) stimulated rat renal gluconeogenesis in cortical tubule suspension in a dose dependent fashion only from substrates that enter gluconeogenesis via phosphoenol-pyruvate carboxylase. The effects of ANP and ANS were significantly potentiated by cAMP and cGMP, whereas methoxamine showed no effect. Extracellular calcium revealed a key role for ANP and ANS response to gluconeogenesis: a concentration of calcium higher than 1 mM was essential. Isolated cells from cortex which lost cell membrane polarity by warming but responded solely to cAMP and cGMP showed no effect by ANP nor ANS. These data suggest that ANP or ANS may act mainly from the basolateral site in the proximal tubule cell and promote gluconeogenesis through cAMP and/or cGMP system.

Animals↗
PubMed1985

Parathyroid carcinoma of the oxyphil cell type. A report of two cases, light and electron microscopic study.

Parathyroid adenomas are subdivided into chief cell and oxyphil cell variants. However, the parathyroid carcinomas described thus far have been only of the chief cell type. Two cases of oxyphil cell carcinoma of the parathyroid gland are reported, with light and electron microscopic study. The patients presented apparent clinical hyperparathyroidism with x-ray finding of generalized fibrous osteitis and palpable parathyroid tumors. Initially, a pathologic diagnosis of parathyroid adenoma was made in both of them. However, in due course, pulmonary metastases developed in one patient and a local recurrence occurred in the other, 5 and 8 years after the primary operation, respectively. Review of the microscopic slides showed that both primary tumors met the criteria of parathyroid carcinoma. A matter of interest in both cases is that the neoplasms were composed principally of oxyphil cells. Electron microscopic study confirmed the existence of typical oxyphil cells packed with numerous mitochondria.

Adenoma↗
PubMed1985

Mutagenic activation of carcinogenic N-nitrosopropylamines by rat liver: evidence for a cytochrome P-450 dependent reaction.

Mutagenic potential of carcinogenic N-nitrosopropylamines was examined by the Ames's liquid incubation assay, using rat liver 9000 g supernatant (S9) fraction for metabolic activation. N-Nitrosobis(2-hydroxypropyl)amine, N-nitroso(2-hydroxypropyl)-(2-oxopropyl)amine (HPOP), N-nitrosobis(2-oxopropyl)amine (BOP), N-nitrosobis(2-acetoxypropyl)amine, N-nitroso-2,6-dimethylmorpholine, N-nitrosomethyl-(2-hydroxypropyl)amine and N-nitrosomethyl(2-oxopropyl)amine all showed positive mutagenicity in strain TA100 in the presence of liver S9 while being negative in strain TA98. With the exception of HPOP and BOP, which were also mutagenic in TA100 without S9 metabolic activation, these N-nitrosopropylamines required the presence of microsomes as a source of enzymes as well as NADP+ as a cofactor for mutagenic activation. Treatment of rats with polychlorinated biphenyls or phenobarbital (PB) resulted in a marked increase in the ability of S9 to activate the seven N-nitrosamines tested whereas 3-methylcholanthrene (3-MC) induction was not effective. All the mutagenic activities were considerably decreased by preincubation in an atmosphere of either carbon monoxide or nitrogen gas or by adding cytochrome c to the S9 mixture. Metyrapone, a specific inhibitor of PB-inducible major cytochrome P-450, considerably inhibited mutagenicity, whereas 7,8-benzoflavone, a specific inhibitor of 3-MC-inducible major cytochrome P-448, was totally lacking this effect. These results demonstrate a correlation between rat liver S9 dependent mutagenicity of six N-nitrosopropylamines and their known carcinogenicity in rat in vivo experiments, and that the PB-inducible major cytochrome P-450 is involved in the mutagenic activation. BOP was also shown to be activated by extrahepatic (lung, kidney, pancreas) tissue S9, blood S9 and bovine serum albumin (BSA) to the extent of 50% of that activity obtained with liver S9. A possible mechanism of BSA-mediated activation of BOP is discussed.

Animals↗
PubMed1985

Molecular cloning of the cls gene responsible for cardiolipin synthesis in Escherichia coli and phenotypic consequences of its amplification.

The cls gene responsible for cardiolipin synthesis in Escherichia coli K-12 was cloned in a 5-kilobase-pair DNA fragment inserted in a mini-F vector, pML31, and then subcloned into a 2.0-kilobase-pair fragment inserted in pBR322. The initial selection of the gene was accomplished in a cls pss-1 double mutant that had lesions in both cardiolipin and phosphatidylserine synthases and required either the cls or the pss gene product for normal growth at 42 degrees C in a broth medium, NBY, supplemented with 200 mM sucrose. The cloned gene was identified as the cls gene by the recovery and amplification of both cardiolipin and cardiolipin synthase in a cls mutant as well as by the integration of a pBR322 derivative into its genetic locus at 27 min on the chromosome of a polA1 mutant. The maxicell analysis indicated that a protein of molecular weight 46,000 is the gene product. The cls gene is thus most likely the structural gene coding for cardiolipin synthase. Hybrid plasmids of high copy numbers containing the cls gene were growth inhibitory to pss-I mutants under the above selective conditions, whereas they inhibited neither the growth of pss-I mutants at 30 degrees C nor that of pss+ strains at any temperature. Amplification of cardiolipin synthase activity was observed, but was not proportional to the probable gene dosage (the enzyme activity was at most 10 times that in wild-type cells), and cardiolipin synthesis in vivo was at the maximum 1.5 times that in wild-type strains, implying the presence in E. coli cells of a mechanism that avoids cardiolipin overproduction, which is possibly disadvantageous to proper membrane functions.

Cardiolipins↗
PubMed1985

Effect of dexamethasone on the release of pituitary hormones in monolayer cultures of rat pituitary cells.

The effect of dexamethasone on the release of ACTH, GH, PRL, LH and TSH was studied in monolayer cultures of rat pituitary cells in 4-hour incubation. With or without the addition of rat hypothalamic extract, the release of GH was significantly inhibited by dexamethasone at concentrations higher than 10(-9) M, although less remarkably than that of ACTH. Intracellular ACTH and GH were unchanged. PRL, LH and TSH were not affected. These results indicate that dexamethasone, when exerted for 4 hours, suppressed the release of GH as well as ACTH, at least in part, at the pituitary level.

Adrenocorticotropic Hormone↗
PubMed1985

Responses of pituitary and adrenal medulla to insulin-induced hypoglycemia in patients with anorexia nervosa.

The responses of pituitary and adrenomedullary hormones to insulin-induced hypoglycemia were studied in 10 patients with anorexia nervosa and 7 control females of comparable age. The increases in plasma GH and PRL were significantly smaller in the patients, while the responses of GH to arginine and of PRL to TRH were indistinguishable. Plasma cortisol attained similar peak levels in both groups with higher basal levels and smaller increments in the patients. The response of plasma epinephrine was markedly lower in the patients, although urinary epinephrine showed similar increase in both groups. These results suggest the possibility that the process by which hypoglycemic stimulus causes pituitary and adrenomedullary hormone secretion is deranged in patients with anorexia nervosa.

Adolescent↗