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Biomedical subjects

T Hosoya

Publications and source records attributed to T Hosoya.

At least 289 records · Page 16Linked to original sources
PubMed1983

[Glucagon-producing carcinoid of the rectum--report of a case].

A 22-year-old male who had been receiving insulin therapy to treat uncontrollable hyperglycemia, was diagnosed to have a carcinoid in the lower rectum. The excised tumor was 1.5 cm in diameter, and showed a yellowish-white cut surface. It did not invade into the proper muscle. Numerous glucagon immunoreactive cells were found. The tumor cells contained many rounded neurosecretory granules. After tumor excision, the patient's hyperglycemia did not return in the absence of insulin administration. We suggest that the tumor may have secreted glucagon which may have acted as an antagonist against insulin in the circulation.

Adult↗
PubMed1982

Partial purification of estrogen-dependent peroxidase of rat uterus and comparison of the properties with those of other animal peroxidases.

An attempt was made to solubilize a peroxidase from the uterine tissue of estrogen-primed rats using various detergents, and the best result was obtained by incubation with 4% cetyltrimethylammonium bromide at 37 degrees C for 60 min. The solubilized material was then dialyzed and subjected to gel filtration on Sephacryl S-200 followed by CM-cellulose chromatography, resulting in a 50-250-fold increase in specific activity over the detergent extract. Some properties of the partially purified uterine tissue peroxidase were studied in comparison with those of other animal peroxidases. The absorption spectra, molecular weight, and isoelectric point are very similar to those of lactoperoxidase. However, the oxidation rates of various hydrogen donor substrates by the uterine peroxidase were not parallel to those of lactoperoxidase and other animal peroxidases and the affinities for cyanide and azide of these enzymes were somewhat different from each other. The uterine peroxidase was inhibited by histidine and excess hydrogen peroxide competitively with respect to guaiacol, suggesting an important role of an amino acid residue in the protein moiety.

Animals↗
PubMed1981

The repair process in experimentally induced avascular necrosis of the femoral head in dogs.

Total necrosis of the femoral head was experimentally produced in dogs by freezing. The healing process was observed in a time sequence. There was a dense fibrous layer at the boundary between the necrotic bone mass and living bone tissue, in each dog which survived for 18 months after the surgery. The layers were similar to that commonly found in avascular necrosis of the femoral head in humans. Histological observation revealed that the establishment of the dense fibrous layer was the final result of three time dependent changes in biological potencies of granulation tissue, i.e., decreasing proliferating and differentiating potencies and increasing osteoclastic potency of mesenchymal cells within the granulation tissue.

Animals↗
PubMed1981

Comparative studies on estrogen-dependent peroxidases contained in uterine microsomes and fluid of rats and pigs.

1. The uterine peroxidase activity of rats was determined quantitatively at each stage of the estrous cycle, and it was found that the protein-based and DNA-based specific activities in proestrus and estrus are 4-5 times higher than those in diestrus. Ovariectomy caused a marked decrease in the activity in the uterus, and the administration of estrogen, but not other steroids, restored the activity. Of many organs in normal rats, the uterus had the greatest peroxidase activity. The peroxidase activity of pig uterus varied from animal to animal and the mean specific activity was about one-hundredth of that of rats. 2. The peroxidase activity of uterine tissue was mainly associated with subcellular particulates, especially microsomal fractions. The membrane-bound peroxidase showed a cyanide-difference spectrum which was very similar to those of lactoperoxidase and thyroid peroxidase. 3. Rat uterine fluid peroxidase was also found to be estrogen-dependent and to exhibit a similar cyanide-difference spectrum. 4. On the basis of spectroscopic, kinetic, and other properties, the relationship between the uterine tissue peroxidase, uterine fluid peroxidase and eosinophil peroxidase is discussed.

Animals↗
PubMed1981

Spectroscopic and kinetic properties of the estrogen-induced peroxidase in rat uterine fluid.

Uterine fluid was collected from estrogen-primed rats which had each previously been subjected to an operation to close the cervical junction of the uterus. Starting from the uterine fluid, uterine fluid peroxidase was purified by carboxymethyl cellulose column chromatography followed by gel filtration on Sephacryl S-200. The purity of the enzyme preparation, as estimated by microelectrophoresis on polyacrylamide gel, was found to be 70-95%. Absorption spectra of the peroxidase and its derivatives resembled those of lactoperoxidase. The pyridine hemochromogen spectrum of the enzyme was also very similar to that of lactoperoxidase. The apparent molecular weight of the enzyme was estimated to be 90,000, being similar to that of lactoperoxidase (78,000). Uterine fluid peroxidase has, however, distinctly different properties from lactoperoxidase, for example, in substrate specificity, pH optimum, inhibition by excess hydrogen peroxide, and isoelectric point.

Animals↗
PubMed1981

Thyrotropin-dependence of the distribution of peroxidase in rat thyroid gland.

After male rats were injected daily with propylthiouracil, whale thyrotropin, or thyroxine for several days, the thyroid glands were examined for their ultrastructural localization of peroxidase. The propylthiouracil treatment caused a marked increase in the number of round, peroxidase-positive vesicles in the apical and middle regions of cytoplasm, and brought about a formation of granular reaction products in the colloid lumen adjacent to the elongated microvilli. Such changes became evident after 2 days of the drug treatment and increased with the time of the effect, until the whole colloid lumen was filled with the reaction products and very elongated microvilli. The effect of exogenous thyrotropin was essentially similar, to a lesser degree, to the drug effect mentioned above. The thyroxine treatment diminished the population of the small vesicles, as usually seen in the case of normal rat thyroids. When the thyroids of thyrotropin-stimulated and unstimulated rats were homogenized and fractionated into particulates fractions and a soluble fraction, almost all the peroxidase activity was contained in the former in both cases. Based on these results, the dynamics and the physiological role of the intracellular peroxidase are discussed.

Animals↗
PubMed1980

A comparative study of histology in Perthes' disease and idiopathic avascular necrosis of the femoral head in adults (IANF).

Thirty-seven femoral heads in idiopathic avascular necrosis of adults and fifty-seven biopsy specimens of the capital nucleus of Perthes' disease were studied histologically. Although the early pathological changes in these two diseases are very similar, in the intermediate and late (advanced) stages they gradually take differing courses. Although the initiating causes in both diseases are still obscure both are probably produced by repeated episodes of infarction of the femoral head.

Biopsy↗
PubMed1979

Process of iodination of thyroglobulin and its maturation. I. Properties and distribution of thyroglobulin labeled with radioiodine in pig thyroid slices.

Pig thyroid slices were incubated with Na131I and the 17--19S 131I-labeled thyroglobulin isolated was subjected to dissociation with 0.3 mM sodium dodecyl sulphate SDS) on sucrose density gradient centrifugation and to iodoamino acid analysis. During the incubation, initially dissociable thyroglobulin was gradually altered to 0.3 mM SDS-resistant species with increasing incorporation of iodine. Microsome-bound, poorly iodinated thyroglobulin and preformed thyroglobulin were chemically iodinated and then subjected to analysis of dissociability and iodoamino acid contents with newly incorporated iodine. The results indicated that the behavior of the former thyroglobulin resembled that of 131I-thyroglobulin obtained from the slices. Then, thyroid slices were incubated for 3 min with Na131I and 3H-leucine with or without 10-min chase incubation. The sucrose density gradient centrifugation patterns of 131I and 3H-radioactivity of cytoplasmic extracts indicated that 131I-thyroglobulin is contained in particulates, especially in vesicles with low density(d=1.12) and that some of them are released into the soluble fraction within 10 min. The vesicles contained peroxidase and NADH-cytochrome c reductase, and are probably exocytotic vesicles in the apical area of cytoplasm of follicular cells. No positive evidence was obtained that plasma membranes participate in the iodination of thyroglobulin under the present experimental conditions. These results suggest that, in the incubation of thyroid slices, iodine atoms are preferentially incorporated into newly synthesized, less iodinated thyroglobulin, rather than preformed thyroglobulin, and that the iodination occurs, at least to a certain degree, in apical vesicles before the thyroglobulin is secreted into the colloid lumen.

Animals↗
PubMed1979

Process of iodination of thyroglobulin and its maturation. II. Properties and distribution of thyroglobulin labeled in vitro or in vivo with radioiodine, 3H-tyrosine, or 3H-galactose in rat thyroid glands.

With the aim of obtaining information on the process of iodination of thyroglobulin, the properties and subcellular distribution of thyroglobulin labeled with radioiodine, 3H-tyrosine, or 3H-galactose were studied. The following results were obtained for 17-19S thyroglobulin isolated from rat thyroid lobes labeled in vitro. (a) The effect of sodium dodecyl sulfate (SDS) concentration (0.1-2.0 mM) on the dissociability of the proteins into 12S subunits showed that 3H-labeled, 131I-labeled, and preformed thyroglobulin behaved very differently; their dissociability decreased in that order. In addition, 0.3 mM SDS is most suitable for discriminating among these species. (b) The amount of 0.3 mM SDS-resistant 131I-thyroglobulin increased with the time of incubation of the lobes or with the amount of iodine atoms incorporated by chemical iodination. (c) Digestion of 3H-tyrosine-labeled thyroglobulin showed that 3H-monoiodotyrosine and 3H-diiodotyrosine were present after incubation of the lobes for 180 min. (d) The dissociability of 3H-galactose-labeled 17-19S thyroglobulin was higher than that of 131I-labeled protein, but its elution pattern on DEAE-cellulose chromatography resembled that of the latter. (e) 131I-Thyroglobulin was scarcely found in the incubation medium, although a considerable amount of 19S thyroglobulin was released into the medium during the incubation. As for the lobes, a significant amount of 131I-radioactivity as well as 3H-radioactivity was found in cytoplasmic particulates, especially in fractions containing apical vesicles and rough microsomes. On the other hand, the following results were obtained for 17-19S thyroglobulin isolated from rats injected with 125I. (a) Dissociability of the protein by 0.3 mM SDS and analysis of 125I-iodoamino acids of pronase digest showed that the iodination process was essentially similar to the case of in vitro incorporation, but was faster. (b) The effect of cyclohiximide treatment showed that the relative reduction of 0.3 mM SDS dissociable species was probably due to a shortage of newly synthesized proteins. All the results obtained in the present experiments are compatible with the view that iodine atoms are incorporated selectively into newly synthesized, less iodinated thyroglobulin, and that the iodination occurs intracellularly, at least to a certain degree, after carbohydrate attachment, probably in the apical vesicles. The possibility that iodination also occurs to some extent in the endoplasmic reticulum and in the colloid lumen of thyroglobulin-stimulated thyroids is discussed.

Animals↗
PubMed1978

In vivo effect of androgen and cycloheximide on the RNA synthesis in isolated nuclei of rat ventral prostates.

Castration results in a rapid decrease in the activity of RNA polymerase I (or A) of isolated nuclei of rat prostates. The decrease was mainly ascribed to the diminution in the number of in vivo initiated RNA chains. The "free form" activity of the enzyme, however, which was estimated by the use of exogenous template and actinomycin D, increased 24 h after castration, then dropped rapidly. The administration of testosterone to castrated rats caused an increase in the activities of both RNA polymerases I and II (or B), which started 2 h and reached the maximum 12 h after the administration. No initial rise in RNA polymerase II activity was observed during the first 2 h. The administration of cycloheximide to normal rats caused a very rapid decrease of the activity of template-bound RNA polymerase I of isolated prostatic nuclei (t1/2=1.7 h), while the "free form" activity of the enzyme did not appreciably change until 3 h. The androgen-stimulated increase in the "engaged form" of the RNA polymerase I of isolated nuclei was completely abolished by the administration of cyclohexmide 60 min before killing. Based on the results obtained, the role of protein(s) with a rapid turn-over which is/are androgen-dependent and presumably participating in the control of preibosomal RNA synthesis is discussed.

Animals↗
PubMed1978

Effects of temperature and urea concentration on the chemical modification and ionization behavior of tyrosyl and iodoamino acid residues of porcine thyroglobulin.

Acetylation of porcine thyroglobulin with N-acetyl imidazole was performed at various temperatures in the presence of urea. In the medium without urea, the number of O-acetylated iodoamino acid residues formed was constantly 15 above 10 degrees C (originating from all diiodotyrosyl and a few of monoiodotyrosyl residues), while the number of O-acetyl tyrosyl residues increased gradually from 15 at 0 degrees C to a maximum of 70 at 70 degrees C. All (about 25) iodoamino acid residues were acetylated at 20 degrees C in 2 M urea, while the presence of 8 M urea was necessary to acetylate all tyrosyl residues at 20 degrees C. Experiments on the nitration of thyroglobulin with tetranitromethane showed that diiodotyrosyl and thyroxyl residues were easily nitrated even at low temperatures and the low ratio of the reagent to the protein, while tyrosyl residues consisted of three groups: the first group (about 14%) which was very easily nitrated even at 0 degrees C and the low ratio of the reagent to the protein, the second group (about 45%) which was nitrated depending on temperature and the molar ratio of the reagent, the remaining which was definitely unreactive even under extreme conditions. In addition, the ionization of tyrosyl and iodoamino acid residues was studied by spectrophotometric titration at various temperatures in the presence and absence of 8 M urea. It was found that diiodotyrosyl and thyroxyl residues did not change very much with respect to ionization behaviour by the addition of urea, in contrast to clear dependence of tyrosyl residues on urea. Based on these observations, the location of these residues and the structural change of the protein with temperature are discussed.

Acetylation↗