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Biomedical subjects

T Okano

Publications and source records attributed to T Okano.

At least 451 records · Page 25Linked to original sources
PubMed1983

Immunohistochemical localization of thyroxine (T4) and triiodothyronine (T3) in the rat thyroid gland under various experimental conditions.

Detection of T4 and T3 in paraffin sections of the rat thyroid gland in various functional states was attempted by an immunoenzyme technique. Both hormones showed a similar localization, being detected mainly in the colloid in the follicular lumen, and sometimes in certain regions of the cytoplasm of the follicular epithelium. Following administration of TSH, their stainability was increased, and the localization within the cytoplasm became more remarkable. Decrease or disappearance of stainability was observed after hypophysectomy or administration of PTU. These findings support the view that the immunostainability of T4 and T3 is closely correlated with the functional state of the thyroid gland.

Animals↗
PubMed1983

Variation of 25-hydroxyvitamin D3 and 25-hydroxyvitamin D2 levels in human plasma obtained from 758 Japanese healthy subjects.

Plasma levels of 25-hydroxyvitamin D3 (25-OH-D3) and 25-hydroxyvitamin D2 (25-OH-D2) in 758 Japanese healthy subjects (most of them adults) were determined by a high-performance liquid chromatographic method previously reported (6) and the following results were obtained: The mean and standard deviation (M +/- SD) of the assayed values of 25-OH-D (sum of 25-OH-D3 and 25-OH-D2) was 23.8 +/- 10.1 ng/ml. 25-OH-D3 was detected in all the samples and the M +/- SD was 23.0 +/- 10.1 ng/ml. The plasma levels clearly showed the seasonal variation that the levels in summer were significantly higher than those in winter. Moreover, the plasma levels were significantly correlated with the amounts of UV light in solar radiation. These results strongly suggested that 25-OH-D3 in plasma mainly originated from endogenous vitamin D3 formed by photo-conversion of 7-dehydrocholesterol in skin. 25-OH-D2 was detected only in 18.3% of the plasma samples and the M +/- SD in the detected samples was 4.4 +/- 2.9 ng/ml which was much lower than those of 25-OH-D3. The results suggested that few healthy Japanese are taking daily exogenous vitamin D2 from multivitamin preparations or others. The M +/- SD values of 25-OH-D3 plasma levels in men and women were 26.2 +/- 10.4 and 19.3 +/- 8.0 ng/ml, respectively. The formers were significantly higher than the latters. The results were thought to be due to the reason that men might be outdoors for longer periods than women. When age variation of plasma 25-OH-D3 levels was examined, the levels in the twenties were significantly lower than the other generations. This was confirmed to be due to the low values observed in the female twenties group, but the detailed reason is unclear at the present time. When 4 healthy volunteers were orally administered 400 I.U./day of vitamin D2 every day for 8 weeks, maximum levels (average: 11.5 ng/ml) were observed at the 8 weeks and the levels gradually decreased after stopping the administration. The results suggested that the half life of 25-OH-D2 in plasma might be 4-5 weeks.

25-Hydroxyvitamin D 2↗
PubMed1983

Doxorubicin-induced skin ulcer in the piglet.

Skin ulceration produced by inadvertently extravasated doxorubicin is characterized by a prolonged course accompanied by severe morbidity, and it has proven to be notoriously difficult to treat. In attempts to identify possible antidotes, 11 different pharmacologic agents were tested using piglets, because their skin is anatomically similar to that of man. Among the agents studied, topical application of DMSO daily for 7 days tended to decrease the maximal diameter and accelerate healing of skin ulcers produced by intradermal doxorubicin. alpha-Tocopherol appeared to worsen the ulceration. None of the 11 agents studied prevented the development of ulcerations completely.

Animals↗
PubMed1982

Mechanisms of p-aminohippurate transport by brush-border and basolateral membrane vesicles isolated from rat kidney cortex.

The uptake of [3H]-labeled p-aminohippurate by brush-border and basolateral membrane vesicles isolated from rat renal cortex has been studied by a rapid filtration technique. Some characteristics of carrier-mediated transport for p-aminohippurate were demonstrated in basolateral membrane vesicles: the uptake was inhibited by probenecid or 4,4'-diisothiocyano-2,2'-disulfonic stilbene (DIDS), was saturable, was stimulated by the countertransport effect, and showed discontinuity in the Arrhenius plot. In contrast, brush-border membrane vesicles failed to display saturability of p-aminohippurate uptake and stimulation by the countertransport effect, although probenecid and DIDS reduced the uptake. Furthermore, p-aminohippurate uptake by brush-border membrane vesicles was influenced more sensitively by alteration in the membrane potential compared with that by basolateral membrane vesicles.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1982

The interaction of cephalosporin antibiotics with renal cortex of rats: accumulation to cortical slices and binding to purified plasma membranes.

The interaction of cephalosporin antibiotics with renal cortex of rats has been examined in vitro by means of cortical slice uptake and binding assay to plasma membranes and other subcellular fractions, including the comparative study with p-aminohippurate. The uptakes of cephalexin and cephaloridine by cortical slices were concentrative, and were strongly inhibited in the presence of 2,4-dinitrophenol, ouabain, nitrogen gas and probenecid. In the case of cefazolin, the degree of concentrative uptake and influence of inhibitors were low. Cephalexin, cephaloridine and p-aminohippurate specifically bound to the basolateral membranes, compared to brush border membranes and other subcellular fractions. Cefazolin binding to basolateral membranes was relatively small. These results suggest that the specificity of cephalexin and cephaloridine bindings to the basolateral membranes could be related to the interaction with the organic acid transport system at the antiluminal side. Thus, an examination of cephalosporin interaction with plasma membranes from renal cortex could offer an appropriate in vitro model system to study the renal transport of these antibiotics.

Animals↗
PubMed1982

Effect of quantum noise on the detection of incipient proximal caries.

The effect of quantum noise on the radiographyic detectability of proximal carious lesions was studied. Bitewing radiographs obtained from patients considered to be free of caries were digitized and stored in a computer using a sampling interval comparable to screen-film systems. Lesions limited in depth to one half the thickness of the enamel were induced by means of computer simulation. Various amounts of randomly generated quantum noise were added to each radiographic image. The results from observer-performance studies show that the lesions can be detected reliably in the presence of substantial amounts of quantum noise, suggesting that comparable diagnostic performance could be obtained with significantly faster imagining systems than those currently used in dentistry.

Analog-Digital Conversion↗
PubMed1982

Statistical contrast enhancement of subtraction images for radiographic caries diagnosis.

The effects of the nonlinear contrast-enhancement technique are examined in terms of diagnostic performance obtainable from subtracted dental radiographs for a variety of simulated exposures. Conventional bitewing radiographs of patients known to be free of caries were digitized by means of a computer interfaced with a conventional television camera. The resulting images were duplicated and stored in the computer. Radiolucencies similar in appearance to interproximal caries were simulated analytically in one set of the images. Reference images were superimposed spatially and subtracted from their counterparts containing the induced interproximal lesions after simulating the effects of quantum limited exposure on both sets. This was done for each separate image element independently by replacing original gray levels in each image with levels determined by a Poisson random deviate. The resulting difference images were contrast enhanced by a method which first smooths out local variations in gray level and then reassigns gray-level values in a way determined by the observed second-order spatial statistics. To aid in localization, these images were then again subtracted from the original noise-degraded pictures without lesions, rendering images similar to conventional radiographs but contrast enhanced. Observer performance by means of these enhanced images was compared with that produced from unenhanced-lesion-containing controls. The results suggest that enhancement increases the certainty with which diagnosis can be made and, further, that diagnostic accuracy can be improved in severely degraded images which simulate the effects of reduced levels of exposure.

Computers↗
PubMed1982

Effect of microphase separated structure of polystyrene/polyamine graft copolymer on adhering rat platelets in vitro.

Rat platelet adhesion on microphase separated surface of polystyrene/polyamine graft copolymers (SA copolymers) was investigated. Shapes of adhering platelet were very much changeable in response to the mode of microphase separation of SA copolymer surfaces. We assume that the microphase separated structure of SA copolyer may regulate the shape change of platelet through its effect on a redistribution of proteins and/or lipids present at the plasma membrane of platelets.

Animals↗
PubMed1982

Effects of contrast medium on radiation-induced chromosome aberrations.

The effects of contrast material (meglumine iothalamate) on radiation-induced chromosome aberrations were investigated in studies on the lymphocytes of patients who had undergone diagnostic radiography and in in vitro experiments with diagnostic x rays and 60Co gamma rays. Chromosome and chromatid aberrations were found to increase significantly with increasing concentrations of contrast material that were added at irradiation. However, the aberrations were not associated with elevation of the ratio of dicentric and ring chromosomes to the number of cells with unstable chromosome aberrations at the first mitosis. Lymphocytes irradiated in the absence of contrast material did not show an increase in chromosome-type aberrations when the agent was given in increasing concentrations during subsequent incubation, but there were greater numbers of chromatid gaps and breaks. When lymphocytes were exposed to 400 R (103.2 mC/kg) of 60Co gamma rays, the presence of contrast agent did not increase the yield of dicentric and ring chromosomes, but induced a marked delay in cell proliferation, especially in lymphocytes with more heavily damaged chromosomes. In additional examination, the contrast agent itself induced sister chromatid exchanges in lymphocytes.

Adolescent↗
PubMed1982

In vivo and in vitro studies on steroid metabolism in a case of primary aldosteronism with multiple lesions of adenoma and nodular hyperplasia.

In order to systematically analyze the regulation and metabolism of steroid hormones in a case of primary aldosteronism with multiple lesions, including adenoma and nodular hyperplasia of the left adrenal gland, the amounts of 9 steroids (progesterone (P), 11-deoxycorticosterone (DOC), corticosterone (B), 18-hydroxycorticosterone (18-OH-B), aldosterone (Aldo), 17 alpha-hydroxyprogesterone (17-OH-P), 11-deoxycortisol (S), cortisol (F) and dehydroepiandrosterone sulfate (DHEAS)) contained in the plasma and in the adrenal tissues were measured. The patient (a 39-year-old female) was admitted to our hospital because of hypokalemia and hypertension. A diagnosis of primary aldosteronism was made on the basis of a complete evaluation, and an adenoma (1.8 x 1.2 cm), a nodular hyperplasia (0.5 x 0.5 cm), a microadenoma and a cortical nodule were found on the left adrenal gland. In vivo studies revealed that the plasma level of Aldo was high, but those of the other steroid hormones were within the normal range. After ACTH infusion, the plasma levels of the 9 steroid hormones increased by 2 to 17 times the base levels. In particular, the responses of DOC and B were markedly high. In vitro studies on P, DOC, B, Aldo and F content in the adenoma (A), the nodular hyperplasia (A'), the adjacent adrenal tissue (C) and the right normal adrenal tissue (D) revealed that, except for F, they were highest in A, followed by A', D and C in that order. In incubation studies with ACTH using A and C, it was found that the levels of 8 steroid hormones with the exception of DHEAS were high in A than in C. In particular, the response of B in A was markedly increased. These findings suggest that aldosteronoma produces 8 steroid hormones under conditions of excess ACTH, while at physiological levels of ACTH, it produces only Aldo in excess.

Adenoma↗
PubMed1982

Simultaneous detection of thyroglobulin (Tg), thyroxine (T4), and Triiodothyronine (T3) in nontoxic thyroid tumors by the immunoperoxidase method.

In 97 nontoxic thyroid tumors, detection of thyroxine(T4) and triiodothyronine(T3) was attempted by the immunoperoxidase method. T4 was demonstrated in 58 tumors (59.8%) and T3 in 76 (78.4%). The feasibility of biosynthesis of T4 and T3 by such tumors was thus established. In 65 of the tumors, we applied the immunostaining method to serial or semiserial sections to study the correlation among the localizations of thyroglobulin(Tg), T4, and T3. The localization of T4 agreed relatively well with that of Tg, and part of the Tg-positive structure frequently revealed simultaneous positive staining for T4. The localization of T3, however, did not always correspond with that of T4 or Tg. T4 and T3 with localizations identical to that of Tg may be considered to be bound to Tg, but the mode of existence of T3 without correspondence in localization to Tg remains unknown.

Adenocarcinoma↗
PubMed1982

Conformation change of DNA induced by 6-oxybenzo[a]pyrene radical.

The interaction of 6-oxybenzo[a]pyrene radical with DNA in 50% methanol solution was studied in order to determine whether the radical molecule influences DNA conformation. The mode of the interaction of 6-oxybenzo[a]pyrene radical with DNA differed from that of other benzo[a]pyrene derivatives such as 6-hydroxybenzo[a]pyrene, diol-epoxides, etc. The physical binding of the radical molecule to DNA seemed to be transient. This physical binding is most likely due to adsorption at the external surface of DNA, i.e., simply contact in character. It is likely that the local base-pairs are tilted by the contact due to hydrophobic interactions. Furthermore, it is concluded that the covalently bound radical molecule, which is mainly introduced on guanine base, induces a twist of the base plane with respect to other base planes.

Benzopyrenes↗
PubMed1981

A simple method for the isolation of basolateral plasma membrane vesicles from rat kidney cortex. Enzyme activities and some properties of glucose transport.

A procedure for preparing basolateral membrane vesicles from rat renal cortex was developed by differential centrifugation and Percoll density gradient centrifugation, and the uptake of D-[3H] glucose into these vesicles was studied by a rapid filtration technique. (Na+ + K+)-ATPase, the marker enzyme for basolateral membranes, was enriched 22-fold compared with that found in the homogenate. The rate of D-glucose uptake was almost unaffected by Na+ gradient (no overshoot).

Alkaline Phosphatase↗