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Biomedical subjects

M Taura

Publications and source records attributed to M Taura.

15 recordsLinked to original sources
PubMed1986

Kinetic study of immunoreactive human thyroglobulin.

Thyroglobulin (Tg) can be detected in the circulation of normal subjects. Serum Tg is increased in patients with various thyroidal disorders including Graves' disease; however, little is known about Tg metabolism. Therefore, a kinetic study of human Tg was carried out in 13 normal men, 19-28 yr old, and 6 untreated hyperthyroid patients with Graves' disease, 3 men (22 to 25 yr old), and 3 women (21 to 63 yr old). Ten milligrams of Tg were injected as a bolus dose. Blood samples were collected before and 10 min, and 2, 4, 6, 8, 12 h and every 12 h up to 72 h after injection. Concentrations of serum Tg were measured by an RIA method developed in our laboratory. Anti-Tg antibody was not detected in any subject. Various indices of this kinetic study were calculated using single compartmental analysis. In 13 normal subjects, the mean serum concentrations of Tg were 17 +/- 12.6 (SD) ng/ml; mean half-life was 29.6 +/- 2.8 h; distribution volume was 11,210 +/- 3,076 ml/60 kg body weight; fractional decay was 2.40 +/- 0.22%/h; MCR was 268.9 +/- 87.8 ml/h X 60 kg; and release rate was 100.3 +/- 50.2 micrograms/day X 60 kg. Serum concentrations of Tg were increased in four of the six untreated hyperthyroid patients with Graves' disease. Their Tg half-lives and MCR were within the normal range. In the two patients who had normal serum concentrations of Tg, the Tg half-lives were shorter and MCR were greater than in normal subjects. The release rates of Tg were increased in all six of these patients. In summary, in hyperthyroid patients, Tg release is significantly greater than normal, whereas Tg metabolism is similar to that in normal subjects.

Adult↗
PubMed1986

Release of thyroid hormone from circulating thyroglobulin in the rat.

Under normal conditions, a small amount of thyroglobulin (Tg) exists in peripheral blood. However, the fate of circulating Tg is unclear. In the present study, in vivo labelled rat Tg was injected iv into rats whose thyroids had been blocked with KI to determine whether circulating Tg released thyroid hormone by hydrolysis in extrathyroidal tissues. Radiolabelled Tg was obtained from thyroid of rats injected with 125I 24h before sacrifice, and subsequently purified by ammonium sulphate precipitation. The plasma samples were obtained from tail veins or by cardiac punctures at various times following injection of [125I]rat Tg. The radioactive samples were separated into iodoprotein, iodoaminoacid and iodide fractions using columns of anion and cation exchange resins. The per cent radioactivity of the iodoprotein, iodoaminoacid an iodide fractions, respectively, was 91.2, 3.8 and 5.2 at 15 min and 66.9, 17.4 and 15.4 at 20 h after injection. In the iodoaminoacid fractions, the presence of T4, T3, MIT and DIT was defined by further fractionation using a Sephadex G-25 column. At 20 h after injection, more than 75% of the radioactivity of the iodoaminoacid fraction was found to be incorporated in T4 and T3. It is concluded that circulating Tg is hydrolyzed in extrathyroidal tissues and that thyroid hormone is released into the circulation, but the amounts of T4 and T3 released are not physiologically significant.

Amino Acids↗
PubMed1985

Degradation of circulating thyroglobulin.

Reported half lives of rat Tg were different according to various investigators. In order to elucidate whether the derivatives of rat Tg in the peripheral circulation affect the results of kinetic studies of Tg, the present study was performed to investigate kinetics of rat Tg after separation of 19S Tg from its derivatives using gel-filtration. Radiolabeled Tg was obtained from thyroids of rats injected with 125I 24 hours before death, and subsequently purified by ammonium sulfate precipitation. The plasma samples obtained at varying time intervals after intravenous injection of 125I-rat Tg were fractionated on a Sephacryl S-300 column. As determined by sucrose density gradient, 99% of in vivo radiolabeled Tg was 19S. On gel-filtration, the injected labeled Tg and plasma samples obtained within two hours after injection showed a single peak in an identical area. A second peak in an area corresponding to a molecular weight of 60,000 to 70,000 appeared within six hours, and became as high as the first within 24 hours. In the second peak, 22.8 +/- 3.8% (mean +/- SE) of radioactivity was precipitated by anti-rat Tg antibody, and 14.4 +/- 1.7% (mean +/- SE) of radioactivity of its TCA precipitate was not extracted by n-butanol. Thus, the second peak could affect the results of Tg kinetic studies which utilize TCA precipitation, n-butanol extraction or RIA procedures. The half life of rat Tg in the present study was calculated from the disappearance curves of radioactivity of 19S Tg separated from other radioactive substances.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1979

Morphological alteration of aortic wall and mitotic cells after complete endothelial loss induced by repeated balloon denudation of swine aorta.

The aortic endothelium in weanling swine was rubbed ten times with an inflated balloon catheter in a repeated balloon denudation. This procedure produced more drastic, extensive and uniform changes in the aortic wall than the commonly used balloon denudation. Sequential alternations of regenerating endothelium, intimal thickening and medial reaction, and the incidence of mitotic cells were studied by scanning and transmission electron microscopy. Complete endothelial loss was confirmed from the descending thoracic aorta to the right femoral artery within 24 hr. By the third day, regenerated endothelium began to cover over the endothelial defect area from the uninjured areas such as the aortic arch and the orifices of branching arteries. Thrombus formation and fibromuscular intimal thickening were observed in the endothelial defect areas by the fifth and seventh days. Three types of mitotic cells, such as endothelial, intimal and medial cells were noted in the aortic wall. Mitotic endothelial and mitotic medial cells were most frequent at Day 3; the latter were closely associated with dead medial cells. Mitotic intimal cells initially appeared at Day 3 and were most frequent at Day 7. Mitotic intimal and mitotic medial cells were frequently present in the aortic wall subjacent to the endothelial defect areas containing interstitial blood components. The large numbers of mitotic aortic cells indicated that endothelial cells give rise to new endothelial cells, intimal cells to new intimal cells, and medial cells to new medial cells.

Animals↗
PubMed1979

Vitamin D-induced coronary atherosclerosis in normolipemic swine: comparison with human disease.

Coronary atherosclerosis developed in normolipemic swine fed a basal ration supplemented with 125,000 IU, 62,500 IU and 31,250 IU of vitamin D3/kg of diet for 3 months and subsequently only the basal ration for the following 3 months. Lesions consisted of intimal atheromata and calcified internal elastica and caused luminal narrowing. The incidence of atherosclerotic lesions was proportional to the vitamin D3 doses. The present experimentally induced lesions had many morphological features resembling those in coronary arteries from human subjects.

Adult↗
PubMed1978

Mitotic structure of aortic intimal cells induced by mechanical injury in swine.

Repair processes of the aortic wall have been studied electron microscopically after removal of the endothelium by an inflated balloon procedure in the thoracic aortae of swine. Initial responses after injury included a thrombotic reaction, the appearance of intimal cells over the denuded surface, and increased mitotic activity of medial cells adjacent to the dead cells by day 3. Cells which engaged in intimal thickening were classified as modified smooth muscle cells throughout the course of this investigation. Mitosis of intimal cells, which was initially observed at day 3, substantially increased at day 7 and decreased by day 14. Mitotic intimal cells contained the same cytoplasmic organelles as interphase modified smooth muscle cells. A detailed description of the paired cisternae as an ultrastructural feature of cell division of modified smooth muscle cells was provided. The paired cisternae were initially observed among the remnants of the nuclear envelope in late prophase; they remained at the periphery of the mitotic apparatus in meta- and anaphase, and finally attached themselves to the nuclear envelope of the daughter cells in late telophase.

Animals↗
PubMed1978

Ultrastructure of cardiovascular lesions induced by hypervitaminosis D and its withdrawal.

Aortic, coronary and cardiac lesions were induced in swine by a hypervitaminosis D3 diet Lipid-free intimal plaques overlying focally calcified medial or internal elastica occured in the thoracic aorta, pulmonary trunk and coronary artery of swine fed a basal ration supplemented with 250,000 IU of vitamin D3/kg of diet for an induction period of 4 months. Cartilage formation with minimal calcification was initiated in the aortic valve during this period. When such animals were subsequently fed only the basal ration free of excessive vitamin D3 for 3 months, intimal plaques regressed in the aorta and pulmonary trunk but progressed in the coronary artery. The calcific deposits in the medial elastica and internal elastica of all three arteries decreased in size. Atherosclerotic intimal thickening occurred in the main coronary arteries. The most severe lesion occupied 75 p.100 of the lumen area. Multiple intimal plaques were noted in the left atrium and aortic and mitral valves. The thickened intima at these coronary and cardiac sites contained calcified elastica and collagen fibers.

Animals↗
PubMed1977

Ultrastructure of botryoid sarcoma of the common bile duct.

A case of botryoid sarcoma of the common bile duct in a 4-year-old girl was reported. Electron microscopic examination disclosed that the neoplasm consisted of three types of cells: polygonal, elongated, and small cells. The former two contained moderate to large amounts of poorly developed myofibriles in the cytoplasm with occasional A, I and Z-bands. The small cells contained mitochondria and dilated rough endoplasmic reticulum but few myofilaments. Deposits of glycogen granules were constant components of the neoplastic cells. Mitosis was striking in the small cells. Abnormal multilaminar endoplasmic reticulum was observed in the small cells in the mitotic stage.

Bile Duct Neoplasms↗
PubMed1977

Duplication cyst of the duodenum in the adult.

A duodenal duplication cyst in a 45-year-old male is reported. A hypotonic duodenography showed a smooth spherical defect in the descending portion of the duodenum. A fiberoptic duodenoscopy disclosed a smooth well-defined tumor which was located orally from the ampulla of Vater. A retrograde pancreatocholangiography indicated the tumor was not in communication with the pancreatic duct or biliary tract. At operation, a cystic spherical mass, 3 cm in diameter, was located in the posterior wall of the duodenum corresponding to the above described diagnosis. The combination of a greater awareness of this condition as well as improved X-ray and endoscopic techniques has made preoperative diagnosis more accurate.

Cysts↗
PubMed1977

An ultrastructural study of the Brunner's cyst.

A Brunner's cyst, removed from a 54-year-old woman, was studied by light and electron microscopy. The cyst was spherical, measured 1.5 cm in diameter and was located in the duodenal bulb. Histologically, the cyst, confined in the submucosa, consisted of a single layer of epithelial cells and connective tissue. The epithelial cells were composed of an orderly array of tall columnar cells containing basal round nuclei and fine granular cytoplasm. Ultrastructurally, the epithelial cells contained many secretory granules in the cytoplasm. Each secretory granule was membrane-bound and appeared electron-lucid with a dense core. They were small and sparse around the Golgi apparatus but large and numerous in the apical region. Multinucleated cells were intermingled with cells of the epithelial lining.

Brunner Glands↗