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Biomedical subjects

T Okano

Publications and source records attributed to T Okano.

At least 469 records · Page 26Linked to original sources
PubMed1981

Effect of hydrophilic and hydrophobic microdomains on mode of interaction between block polymer and blood platelets.

ABA-type block copolymers composed of 2-hydroxyethyl methacrylate (HEMA), a hydrophilic monomer, and styrene (St), a hydrophobic monomer, were synthesized by the coupling reaction of telechelic oligomers used as prepolymers. These block copolymers may be represented as microphase-separated structures. It is therefore possible to change the balance between hydrophilicity and hydrophobicity in the level of an assembled order of macromolecules. In response to the relative composition of the copolymers, three typical morphological patterns were observed in electron microscopic photographs: dispersed domains of continuous St chains in the region of HEMA chains, alternate HEMA and St lamellae and finally, dispersed phases of continuous HEMA chains in the region of St chains. The effect of the hydrophilic and hydrophobic microdomains of the copolymers on the mode of interaction between polymers and platelets was studied by the microsphere column method. In the case of homopolymers and random copolymers, a significant degree of platelet adhesion and aggregation was observed. However, the degree of platelet adhesion and deformation was suppressed on the surfaces of the block copolymers containing 0.608 and 0.347 mole fractions of HEMA whose microdomains were hydrophilic-hydrophobic lamellae and isolated hydrophilic islands in hydrophobic areas, respectively. These results show that the microphase-separated structures were antithrombogenic and prevented platelet adhesion and deformation. On the basis of the results obtained, the interaction between platelets and polymer surfaces was described in terms of the effect of hydrophilic and hydrophobic microdomains.

Acrylates↗
PubMed1981

Production of thyroxine (T4) and triiodothyronine (T3) in nontoxic thyroid tumors. An immunohistochemical study.

Thyroid tissue specimens from 27 patients with thyroid tumors were examined for thyroxine (T4) and triiodothyronine (T3) by the peroxidase-labeled antibody method. The result revealed localization of T4 in 12 of the 14 follicular adenomas, in all the 8 papillary carcinomas and in 1 of the 3 follicular carcinomas studied, and of T3 in 13 of the 14 follicular adenomas, in all the 8 papillary carcinomas and in all the 3 follicular carcinomas. In the tumor tissue, the thyroid hormones were demonstrated in the colloid substance, on the luminal surface of tumor cells and in their cytoplasm. Compared with nontumorous thyroid tissue, the tumor tissue showed localization of the hormones predominantly in the cytoplasm and to a lesser extent in the colloid substance, with conspicuous variations in tissue distribution of positive areas and intensity of staining. This tendency was more marked in thyroid carcinomas. The demonstration of T4 and T3 in routine histological paraffin sections of formalin-fixed thyroid tissues in this investigation indicates potential usefulness of thyroid hormone detection by the peroxidase-labeled antibody technique. It is an effective diagnostic tool for evaluating the functional activity of the thyroid tumors as well as for determining whether a malignant growth under examination originates from the thyroid.

Adenocarcinoma↗
PubMed1981

Detection of HBsAg in the pancreas.

Hepatitis B surface antigen (HBsAg) has been reported to be present in other organs than the liver. 3,9 So far as our knowledge is concerned, however, any report of cases dealing with pancreatic diseased induced by hepatitis B virus (HBV) has not been described in the English and Japanese literature. We report an autopsy case with a pancreatic lesion characterized by damage of both exocrine and endocrine epithelial cells with inflammatory responses, which were immunohistochemically found to be positive for HBsAg, and electron-microscopically to possess core-like particles in the nucleus and cytoplasm.

Chronic Disease↗
PubMed1981

A method for simultaneous determination of 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3 in human plasma by using two steps of high-performance liquid chromatography.

A method for simultaneous determination of 25-hydroxyvitamin D2 (25-OH-D2) and 25-hydroxyvitamin D3 (25-OH-D3) in human plasma has been developed by using two steps of high-performance liquid chromatography (HPLC). Lipids extracted from 0.51 ml of human plasma were first subjected to the preparative HPLC using a Nucleosil 5C18 column (reversed-phase type) and a 25-OH-D fraction containing 25-OH-D2 and 25-OH-D3 was separated. The separated fraction was subsequently subjected to the analytical HPLC using a Zorbax SIL column (straight-phase type). Since the peaks corresponding to 25-OH-D2 and 25-OH-D3 were clearly separated from one another on the chromatogram of the analytical HPLC, the metabolites could be simultaneously determined by estimating the respective peak heights. When the fractions corresponding to the respective peaks were separately collected by repeatedly applying rather large quantities of human plasma and were subjected to gas chromatography-mass spectrometry (GC-MS), they were identified as containing 25-OH-D2 and 25-OH-D3, respectively. The proposed method was applied to plasma samples of human adults taking 400 I.U./day of vitamin D2 for 8 weeks and the values were 22.5 +/- 8.1 ng/ml for 25-OH-D3 and 11.5 +/- 1.8 ng/ml for 25-OH-D2 (mean +/- S.D.), respectively.

25-Hydroxyvitamin D 2↗
PubMed1981

Simplified assay of vitamin D2 in fortified dried milk by using two steps of high-performance liquid chromatography.

A simplified method for the determination of vitamin D2 in fortified dried milk was established by using two steps of high-performance liquid chromatography (HPLC). About 1 g of fortified dried milk was accurately weighed and directly saponified. The extracted unsaponifiable matter was first subjected to preparative HPLC using a Nucleosil 5C18 column (reversed-phase type) with acetonitrile-methanol (1:1) as a mobile phase and a fraction containing vitamin D2 was separated. The separated fraction was subsequently subjected to analytical HPLC using a Zorbax SIL column (straight-phase type) with 0.4% isopropanol in n-hexane as a mobile phase. Since the peak corresponding to vitamin D2 was clearly observed with separation from other concomitants on the chromatogram of the analytical HPLC, the vitamin was assayed by estimating the peak height. The overall recovery of vitamin D2 by the proposed method was 94.3 +/- 2.3% (mean +/- SD). Naturally occurring vitamin D3 derived from cow's milk was negligible in commercial fortified dried milk sold in Japan. When the proposed method was applied to 5 kinds of commercial fortified dried milk, satisfactory results were obtained.

Animals↗
PubMed1981

Plasma levels of 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3 in maternal, cord and neonatal blood.

A high-performance liquid chromatographic method for simultaneous assay of 25-hydroxyvitamin D2 (25-OH-D2) and 25-hydroxyvitamin D3 (25-OH-D3) proposed in a previous paper (1) was applied to determine the plasma levels of the metabolites in perinatal and postnatal periods. The plasma samples of maternal, cord and neonatal blood were collected in summer and winter seasons. 25-Hydroxyvitamin D3 was detected in all the samples. The plasma levels of the metabolite in mothers, cords and newborn infants (at life within 24 hr) in summer were 33.9 +/- 12.5, 18.9 +/- 8.4 and 16.6 +/- 6.4 (mean +/- S.D.) ng/ml, respectively, while those in winter were 15.8 +/- 6.6, 8.8 +/- 3.4 and 7.7 +/- 3.2 ng/ml, respectively. The data in summer were significantly higher than the respective data in winter and there were high significant correlations between the mothers and cords and between mothers and newborns. In both seasons, the plasma levels of mothers were about two times higher than the respective data of cords and newborns which were nearly identical with one another. The similar tendency was always observed in the individual data of mothers-cords-newborns pair samples. In this study, many plasma samples from mothers, cords and newborns were examined, but 25-OH-D2 was detected in only few samples (6/41 for mothers, 3/36 for cords and 2/34 for newborns). However, the metabolite began to appear in all the samples during nursing with vitamin D2-fortified dry milk to show 4.6 +/- 1.3 and 4.8 +/- 1.2 ng/ml in the summer and winter samples of neonates at life of 5-6 days, respectively. When the variation of plasma 25-OH-D2 and 25-OH-D3 levels was examined in postnatal periods until one month, the levels of exogenous 25-OH-D2 was increased while those of endogenous 25-OH-D3 was decreased. The sum of vitamin D2 intake from fortified dry milk was highly significantly correlated with the plasma levels of 25-OH-D2, which indicates that daily uptake of exogenous vitamin D2 is very important in nutrition during postnatal periods of bottle-fed infants.

Calcifediol↗
PubMed1979

A rapid and precise method for the determination of vitamin D3 in rat skin by high-performance liquid chromatography.

In order to develop the investigations into photobiogenesis of vitamin D3, a rapid and precise method for the determination of the vitamin in rat skin was established by using high-performance liquid chromatography (HPLC). The proposed method included saponification of small pieces of rat skin, extraction of the unsaponifiable matter and application to HPLC using "Zorbax SIL" (straight-phase) as an adsorbent and 0.5% isopropanol in n-hexane as a mobile phase. The applicable lower limit of the method was 2ng of vitamin D3/cm2 of subcutaneous tissue-removed skin and it was possible to assay a concentration higher than 2 ng/cm2. The proposed method was applied to determine the content of vitamin D3 in rat skin obtained from in vivo and in vitro irradiation experiments. In the in vitro experiment, the yield of vitamin D3 increased in proportion to the irradiation time. On the other hand, the yield in the in vivo experiment showed a proportional increase similar to the in vitro experiment until 60 min irradiation, while a nearly constant value was obtained by irradiation for longer than 60 min. When the rat skin obtained from the in vitro experiment was irradiated with monochromatic UV rays in the range s60-350 nm, the most effective wavelength for the formation of vitamin D3 was confirmed to be 303 nm, which differs from the result obtained from the experiment in a test tube (295 nm). Moreover, the yield of vitamin D3 by irradiation with UV rays below 288 nm was extremely low, which again differed from the results of a test tube experiment. These differences were thought to be due to the filter effect of the malpighian layer in the epidermis of rat skin.

Animals↗
PubMed1979

Assay of 25-hydroxyvitamin D3 in human plasma by high-performance liquid chromatography.

A method using preparative and analytical high-performance liquid chromatography (HPLC) is proposed for the assay of 25-hydroxyvitamin D3 (25-OH-D3) in human plasma. A constant volume (0.2--2.0 ml) of a plasma sample was saponified. The unsaponifiable matter was first applied to preparative HPLC using a column of the straight-phase type (Zorbax SIL) in order to separate a 25-OH-D3 fraction from lipophilic concomitants giving ultraviolet-absorbing noise. Then, the separated 25-OH-D3 fraction was applied to analytical HPLC using a column of the reversed-phase type (Zorbax ODS) in order to measure the content of 25-OH-D3 from the peak height. This is a revised method from Jones (1978): Clin. Chem., 24, 287--298). The results showed that the clean-up procedure by the first preparative HPLC was successfully performed because the peak corresponding to 25-OH-D3 on the chromatogram of the second analytical HPLC was not disturbed by any other interfering peaks. Moreover, recovery through the whole procedure was satisfacotry (about 100%) and the procedures of saponification and isolation of the unsaponifiable matter diminished the overload to the columns. These are the revised points of Jones' method. When two determinations were performed on 12 samples of plasma taken from normal adults in October, the values were 22.6 +/- 4.8 and 21.0 +/- 3.6 (mean +/- SD) ng/ml, respectively.

Adult↗
PubMed1979

Isolation and purification of in vivo-generated 25-hydroxyvitamin D2 by preparative high-performance liquid chromatography.

In order to obtain a standard compound of 25-hydroxyvitamin D2 (25-OH-D2), a method for isolating in vivo-generated 25-OH-D2 from the blood of rats or rabbits was established by using several steps of preparative high-performance liquid chromatography (HPLC). When the unsaponifiable matter of the plasma obtained from rats or rabbits receiving a large dose of vitamin D2 was applied to the preparative HPLC using a Zorbax SIL column, a peak denoted as peak X was observed on the chromatogram. Since the peak X was thought to be due to 25-OH-D2 from the experiments of time course and dose-response, it was purified by subjecting it to successive preparative HPLC using several kinds of columns. From the results of ultraviolet (UV) absorption spectrum, gas chromatography-mass spectrometry (GC-MS) and mass chromatography, the purified peak X compound was confirmed to be 25-OH-D2. The proposed method for isolating in vivo-generated 25-OH-D2 is very convenient, because the time to perform each HPLC is very short though several steps of HPLC are used.

Animals↗
PubMed1979

Relationship of carcinogenicity, mutagenicity, and K-region reactivity in benz[c]acridines.

Benz[c]acridine and its 10 methyl-substituted derivatives were examined for chemical reactivity with osmium tetroxide and mutagenic activity on Salmonella typhimurium, and the results were contrasted with the electronic charge in the K region and the carcinogenic activity of benz[c]acridines. The addition of osmium tetroxide took place at the K region of benz[c]acridines. A linear relationship was established between the charge in the K region and the rate constant of the second-order reaction between osmium tetroxide and benz[c]acridines except the 5,7-dimethyl derivative whose substituent in the 5-position sterically hindered the reaction. Benz[c]acridines showed mutagenic activity in the presence of S-9 Mix, but not in the absence of S-9 Mix. There was a corresponding relationship among the K-region reactivity, mutagenic activity, and carcinogenic activity in benz[c]acridines. The only exception for this was the 7,11-dimethyl derivative in which the 11-methyl group had a steric effect on the ring-nitrogen atom. It was suggested that a common mechanism with regard to the reactivity of the K region is working in both carcinogenesis and mutagenesis. It was concluded that benz[c]acridines are activated, before they display a carcinogenic or mutagenic activity, to a proximate form such as 5,6-epoxides, through a metabolic process in which the nucleophilic property of the K region to react with electrophilic reagents plays an important role.

Acridines↗
PubMed1978

In vivo and in vitro conversion of 7-dehydrocholesterol into vitamin D3 in rat skin by ultraviolet ray's irradiation.

In order to confirm the photochemical conversion of 7-dehydrocholesterol (7-DHC) into vitamin D3 in rat skin, the following in vitro and in vivo experiments were carried out. In the first (in vitro) experiment, the skin stripped off from a sacrificed normal rat was irradiated with an ultraviolet (UV) lamp for a constant period. In the second (in vivo) experiment, the normal rat, irradiated under the same condition mentioned above, was sacrificed and then the skin was stripped off. Lipids were individually extracted with chloroform-methanol (1:1) from the skin obtained in the two experiments and the solvent was evaporated. The resulting residue was saponified and the unsaponifiable matter extracted with benzene was purified by application to hydroxyalkoxy-propyl (HAP) Sephadex column chromatography. The resulting purified vitamin D3 fraction was applied to high-performance liquid chromatography (HPLC) in order to estimate vitamin D3. No peak, aside from that of alpha-naphthol as an internal standard, was observed in the HPLC chromatogram on the skin obtained from the non-irradiated rat, whereas the peak corresponding to vitamin D3 was observed in each HPLC chromatogram on both the irradiated skin (in vitro experiment) and the skin obtained from the irradiated rat (in vivo experiment). The peaks, confirmed to be due to vitamin D3 by the results of co-chromatography, were increased according to the increase of irradiation energy and there were little differences between the corresponding estimated values of vitamin D3 in the two experiments. These results prompted the conclusion that 7-DHC in rat skin was photochemically converted into vitamin D3 by UV irradiation and that the in vivo conversion mechanism might be the same as the in vitro one.

Animals↗