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Biomedical subjects

T Okano

Publications and source records attributed to T Okano.

At least 253 records · Page 14Linked to original sources
PubMed1994

The enzymatic formation of 1 alpha,25-dihydroxyvitamin D3 from 25-hydroxyvitamin D3 in the liver of fetal rats.

We have confirmed the existence of 25-hydroxyvitamin D3 (25-OH-D3)-1 alpha-hydroxylase in the liver of fetal rats, in addition to that in the kidney, by in vitro experiments. The findings are similar to those in the fish liver as reported previously (Takeuchi et al., Life Sci. 32, 275-282, 1991). When [3H]-25-OH-D3 was incubated with liver homogenates of vitamin D-deficient fetal rats, a peak corresponding to [3H]-1 alpha,25-dihydroxyvitamin D3 (1,25-(OH)2D3) was observed in the profile of high-performance liquid chromatography (HPLC). The formation of the metabolite was confirmed by thermal isomerization into the pre-isomer, binding affinity to the receptor and mass fragmentography. Lineweaver-Burk plot analysis of mitochondrial 25-OH-D3-1 alpha-hydroxylase in the liver gave an apparent Km value of approximately 2 microM of 25-OH-D3 and a Vmax value of 0.2 pmol of 1,25(OH)2D3/30 min/mg protein. These findings suggest that the enzyme in the liver disappeared with the growth of the fetus and became predominant in the kidney of mature rats.

Aging↗
PubMed1994

The binding properties, with blood proteins, and tissue distribution of 22-oxa-1 alpha,25-dihydroxyvitamin D3, a noncalcemic analogue of 1 alpha, 25-dihydroxyvitamin D3, in rats.

The binding properties, with blood proteins, and tissue distribution of 22-oxa-1 alpha,25-dihydroxyvitamin (22-oxacalcitriol; OCT), a noncalcemic analogue of 1 alpha,25-dihydroxyvitamin D3 [1,25(OH)2D3], in rats were investigated. The binding affinity of OCT to plasma vitamin D binding protein (DBP) is extremely low and OCT mainly circulates in the blood as an intact form nonspecifically bound to lipoproteins especially to chylomicrons and low density lipoprotein (LDL). OCT intravenously injected into normal rats rats rapidly disappeared from the blood, and rapidly appeared in the bile as glucuronides of intact OCT and 1 alpha, 3 beta,20(S)-trihydroxy-9,10-secopregna-5,7,10(19)-triene (23,24,25,26, 27-pentanorOCT; pentanorOCT) as an OCT metabolite. When OCT or 1,25(OH)2D3 was injected into normal rats, significant amounts of OCT and 1,25(OH)2D3 were quickly detected in the thyroid and parathyroid glands, thymus, adrenals, liver, plasma, small intestine, kidneys, and calvaria. The detected amounts of OCT in the parathyroid glands, thymus, adrenals, liver, small intestine, and kidneys were significantly higher than the respective values for 1,25(OH)2D3 2 and/or 10 min after injection, while those of OCT in the plasma and calvaria were significantly lower than those of 1,25(OH)2D3. The in vivo rapid turn-over, nonspecific transportation, and incorporation of detectable amounts into the tissues are typical characteristics of OCT which may account for its specific activities.

Animals↗
PubMed1994

Temperature modulated solubility-activity alterations for poly(N-isopropylacrylamide)-lipase conjugates.

Chemical modification of proteins by use of functional polymers is expected to endow them with new properties without destroying their native functions, thus providing useful materials for application in different fields. We have synthesized poly(N-isopropylacrylamide) [poly(IPAAm)] co-oligomer with N,N-dimethylacrylamide (DMAAm) and reactive end groups by telomerization of IPAAm. This co-oligomer exhibits a lower critical solution temperature (LCST) at 37 degrees C. Using this temperature-responsive semitelechelic co-oligomer, we prepared polymer-enzyme conjugates of lipase by covalent coupling via carboxyl end-groups. This bioconjugate exhibits a LCST at 37 degrees C, having rapid, reversible hydration-dehydration changes due to highly mobile free polymer end groups. The conjugate retained its native enzymatic activity below this critical temperature, above which it precipitated and its catalytic function was shut off. This conjugate can be readily separated from reaction mixtures as a precipitate by simple temperature changes after reaction and reused in cycles without denaturation. Such a modulated system is attractive for application as a novel bioreactor system.

Acrylic Resins↗
PubMed1994

Postadsorptive behavior of plasma proteins on poly(propylene oxide)-segmented nylon-610 surfaces and its implication in preventing contact-induced activation of platelets on these surfaces.

The influence of adsorbed plasma proteins on preventing contact-induced activation of platelets on poly(propylene oxide) (PPO)-segmented nylon-610 surfaces was investigated by monitoring changes in cytoplasmic free Ca2+ concentrations in platelets and adsorption/desorption of albumin and fibrinogen on these copolymer surfaces. Direct measurement of cytoplasmic free Ca2+ concentration in platelets in contact with copolymer surfaces was achieved by monitoring spectral changes of a fluorescent indicator dye, Fura 2. These copolymers were characterized by a surface microstructure composed of coexisting crystalline and amorphous phases. An increase in cytoplasmic free Ca2+ concentration in platelets interacting with polymer surfaces was observed, and this increase was found to be strongly reduced both by the adsorption of plasma proteins into the polymer surface and by modifying the surface microstructure of the polymer itself. Transient changes in cytoplasmic free Ca2+ concentration were observed in platelets in contact with the surface of copolymer 61P3-25, which exhibited excellent nonthrombogenicity in our previous studies, depending on the residence time of plasma and plasma concentration. Additionally, adsorption/desorption of albumin and fibrinogen on copolymer surfaces was estimated using 125I-labeled proteins. Exchange of the adsorbed albumin with fibrinogen and minimum fibrinogen adsorption were observed particularly on the 61P3-25 surface. Exchange of adsorbed fibrinogen with plasma proteins and/or increased fibrinogen adsorption were also observed on all other polymer surfaces examined. Finally, we conclude that controlled formation of a defined protein adsorption layer on the 61P3-25 surface via the transient exchange of adsorbed albumin with fibrinogen from plasma, can be a dominant factor in preventing platelet adhesion and activation on this surface.

Adsorption↗
PubMed1994

Modulating the phase transition temperature and thermosensitivity in N-isopropylacrylamide copolymer gels.

Temperature-responsive copolymer (or ternary copolymer) gels of N-isopropylacrylamide (IPAAm) were synthesized with hydrophobic alkyl methacrylate (RMA), hydrophilic acrylamide (AAm), N,N'-dimethylacrylamide (DMAAm), and N-acryloylpyrrolidine (APy) as comonomers. The effects of these comonomers on the phase transition temperature (LCST) and the thermosensitivity have been discussed. The LCST of poly(IPAAm) gel in phosphate buffered saline (PBS) was lowered by the introduction of hydrophobic RMA, and the change in equilibrium swelling ratio with temperature change became smaller with an increase in RMA content. However, a stable skin layer to achieve complete 'on-off' regulation of drug release was formed at a higher temperature by RMA due to hydrophobic interaction of alkyl chains. The LCST of poly(IPAAm-co-AAm) gel increased with an increase in AAm content. However, the thermosensitivity of the gel became smaller. It was suggested that hydrophilic AAm prevented the formation of a dense skin layer at a higher temperature. It was difficult to obtain a complete 'off' state due to an insufficiently dense skin layer in order to stop the drug release. The LCST was raised and great thermosensitivity was possible by the introduction of DMAAm or APy. Poly(IPAAm-co-DMAAm) enabled 'on-off' drug release in response to smaller temperature changes around the body temperature. The molecular design to control transition temperature and thermosensitivity of gel was established.

Acrylamides↗
PubMed1994

Factors determining the diagnostic accuracy of digitized conventional intraoral radiographs.

A number of factors may determine the diagnostic accuracy of digitized intraoral radiographs. Conventional film radiographs were digitized with three different digitizers, a laser-scanner, a drum-scanner and a TV camera. Digital images, varying in pixel size, grey level and image processing, were displayed on three different video-monitors and assessed by 10 dentists. The detectability of incipient proximal surface caries was used as an index of the diagnostic accuracy and the effect of the different factors compared by means of receiver operating characteristic (ROC) analysis. Images digitized by the drum-scanner were found to have the best diagnostic accuracy. Sufficient diagnostic accuracy could be attained on the low-cost video monitor of a personal computer. Digital images with a pixel size of 100 microns and 32 grey levels were found to be acceptable for intraoral radiographs for diagnostic purposes. These results provide a practical guide for establishing a digital image acquiring system for any intraoral radiographs, reducing demands on data storage to a minimum.

Analysis of Variance↗
PubMed1994

[Three dimensional image analysis on retroperitoneal lymph node metastasis of testicular cancer].

The effects of chemotherapy on the metastasis of retroperitoneal lymph nodes from testicular cancer have been generally evaluated with bi-dimensional imaging methods. Since the structure of these lymph nodes seems to be complicated, it is expected that three dimensional imaging methods could achieve more correct evaluation of the disease extension and the treatment effects when compared with bi-dimensional ones. The present study was undertaken to reconstruct the three dimensional imaging from CT films using personal computer system. Twenty one patients with bulky retroperitoneal nodal metastases were examined before and after chemotherapy. The evaluation of treatment effects based on three dimensional imaging method reflected the clinical course more adequately than the bi-dimensional one. When shrinkage rate of the tumor volume was less than 65%, viable tumor cells remained in all cases. Only one of six cases with more than 90% shrinkage revealed viable tumor cells. All patients in whom the metastases were estimated to be more than 100 cm3 in volume before chemotherapy and less than 50 cm3 after chemotherapy were shown to have completely necrotic tissues. In conclusion, three dimensional imaging was useful to estimate the post-treatment volume and shrinkage rate which correlated to the effects of treatment and prognosis.

Adolescent↗
PubMed1994

[Lymph node metastasis in bladder cancer].

Forty patients who had transitional cell carcinoma of the bladder with positive pelvic lymph node metastasis, treated at Chiba University Hospital between April 1975 and March 1991 were investigated to evaluate the significance of pelvic lymph node dissection. The frequency of the patients with positive lymph node was 9.1% in all patients with transitional cell carcinoma of the urinary bladder, 4.0% in the clinical T1, 3.4% in T2, 35.7% in T3a, 32.1% in T3b, 46.2% in T4, and none in Tis and Ta. Of the 40 patients, 16 underwent cystectomy pelvic lymph node dissection, 19 had biopsy of suspicious lymph nodes which turned out to be positive for metastasis, and 5 were defined by computed tomography. Pelvic lymph node dissection was performed at the common iliac, presacral, external iliac, internal iliac, and obturator nodes. In the 16 patients who underwent cystectomy with pelvic lymph node dissection, the frequency of metastasis in each nodal group was 38% in common iliac, 31% in external iliac and obturator, and 25% in presacral and internal iliac. Out of the 16 patients, eight had regional lymphatic metastasis, three had only extra regional lymph node metastasis, and five had both regional and extra regional metastasis. Three of nine patients who had single positive node had common iliac or presacral positive node without regional lymph node metastasis.

Adult↗
PubMed1994

[A new autoantibody anti-Na which reacts with a cell cycle-dependent nuclear antigen].

By immunofluorescent techniques many autoantibodies have been detected in sera from patients with connective tissue diseases. A distinct antinuclear antibody reacting with a cellular component which showed a characteristic expression pattern is reported. The new antibody, termed anti-Na, stained approximately 20-30% of the HEp-2 cell with a variegated speckled pattern. In synchronized cell analysis, anti-Na showed fine speckles in G2/M phase cells, discrete speckles in dividing chromosomes, and specific cytoplasmic staining in anaphase and telophase cells. Although the preliminary study showed that 3% of SLE patients had anti-Na, the frequency of the anti-Na antibody in rheumatic diseases and their clinical significance remain to be clarified. Screening of a lambda gt11 cDNA expression library with anti-Na antibody yielded only one cDNA encoding a portion of this autoantigen. Deduced amino acid sequences of this cDNA showed a partial homology with myosin heavy chain of C. elegans, suggesting that the Na antigen is involved in contractibility related to myosin.

Amino Acid Sequence↗
PubMed1994

A stable acentric marker chromosome: possible existence of an intercalary ancient centromere at distal 8p.

A centromere is considered to be an essential chromosomal component where microtubule-kinetochore interaction occurs to segregate sister chromatids faithfully and acentric chromosomes are unstable and lost through cell divisions. We report a novel marker chromosome that was acentric but stable through cell divisions. The patient was a 2-year-old girl with mental retardation, patent ductus arteriosus, and mild dysmorphic features. G-banded chromosome analysis revealed that an additional small marker chromosome was observed in all 100 cells examined. By the reverse-chromosome-painting method, the marker was found to originate from the distal region of 8p, and a subsequent two-color FISH analysis with cosmid probes around the region revealed that the marker was an inverted duplication interpreted as 8pter-->p23.1::p23.1-->8pter. No centromeric region was involved in the marker. By FISH, no alpha-satellite sequence was detected on the marker, while a telomere sequence was detected at each end. Anti-kinetochore immunostaining, using a serum from a patient with CREST (calcinosis, Raynaud syndrome, esophageal dismotility, sclerodactyly, and telangiectasia) syndrome, showed a pair of signals on the marker, which indicated that a functional kinetochore was present on the marker. The analysis of this patient might suggest the possibility that an ancient centromere sequence exists at distal 8p (8p23.1-pter) and was activated through the chromosome rearrangement in the patient.

Abnormalities, Multiple↗
PubMed1994

The natural course of myelopathy caused by ossification of the posterior longitudinal ligament in the cervical spine.

The natural course of ossification of the posterior longitudinal ligament, particularly the relationship between the onset of myelopathy and factors associated with its aggravation, was studied in 207 patients during an average period of 10 years 3 months. Myelopathic signs were already present in 37 (18%) patients at the time of the initial examination. Fourteen of these 37 patients showed aggravation of symptoms during the observation period. Myelopathy appeared during the observation period in 33 (16%) of the 207 patients. One hundred thirty-seven (66%) patients were free of myelopathy. Some patients had no myelopathic signs, despite severe spinal stenosis, because of the ossification. In these patients, the range of motion of the cervical spine was severely limited, indicating that dynamic factors are important in the development of myelopathy. In treating this disease, it is necessary to take into consideration the natural course of the disease and to identify the involvement not only of static factors, such as compression caused by ossification, but also of dynamic factors.

Adult↗
PubMed1994

Detection of human papillomavirus DNA and state of p53 gene in Japanese penile cancer.

The frequency of integration with human papillomavirus (HPV) and its genotypes in Japanese penile cancer was examined with relation to p53 gene mutations using polymerase chain reaction amplification. Tissues were obtained from 13 patients (eight from freshly frozen and five from paraffin-embedded samples). HPV DNA was detected in seven out of the 13 (54%), and their genotypes were type 16 in four, type 31 in one and type 33 in two cases. Neither HPV-detected nor -undetected tissues showed mutated alterations in exons 4-9 of p53 genes. The results suggest HPV to be, at least to some extent, involved in the oncogenesis of penile cancer, and that p53 gene mutations may not correlate with the development of penile cancer.

Aged↗
PubMed1993

Boronate-containing polymer as novel mitogen for lymphocytes.

A novel water-soluble polymer (poly(AAm-co-PBA)) was synthesized by radical copolymerization of 3-acrylamidophenylboronic acid with acrylamide and evaluated as synthetic mitogen of lymphocytes. Boronic acid was introduced in the polymer as recognition site of sugar residues existing on the plasma membrane surface of lymphocyte, since it makes a covalent bonding with polyol compounds including sugars. Obvious increase in [3H]thymidine incorporation of lymphocytes was observed when murine spleen lymphocytes were cultured with poly(AAm-co-PBA), while little proliferative response of lymphocytes was observed in the presence of the homopolymer of acrylamide, the polymer without boronic acid moiety. This suggests that proliferation of lymphocytes was induced through the binding of phenylboronic acid moiety in poly(AAm-co-PBA) with glycoproteins existing on the plasma membrane surface of lymphocytes. Further, poly(AAm-co-PBA) was found to induce even the proliferation of B cell-depleted population of lymphocytes, suggesting T cell stimulation by this boronate-containing polymer.

Acrylic Resins↗
PubMed1993

Transport of organic cation in renal brush-border membrane from rats with renal ischemic injury.

Transport of tetraethylammonium, an organic cation has been studied using renal brush-border membrane vesicles isolated from rats with ischemic and ischemia-reperfusion injury. H+ gradient-dependent uptake of tetraethylammonium slightly, but significantly, decreased in brush-border membrane vesicles from ischemic kidneys. When the kidney was reperfused after ischemia, the extent of the decrease of tetraethylammonium uptake was much greater than that after ischemia alone. The Vmax value of tetraethylammonium uptake by brush-border membrane vesicles from reperfused kidneys was decreased compared with control, without any change in the Km value. The tetraethylammonium uptake by the vesicles from reperfused kidneys was decreases both in the presence and absence of the outward H+ gradient (driving force). Uptake of D-glucose in renal brush-border membrane vesicles was also decreased by ischemia and again, reperfusion caused a further decrease of the uptake. Reperfusion also induced marked changes in the enrichment and recovery of marker enzymes in the isolated brush-border membrane fraction compared with ischemia. These findings suggest that renal ischemic injury altered the transport properties of tetraethylammonium as well as D-glucose, and that reperfusion after ischemia induced further damages on these functions in the brush-border membrane.

Animals↗
PubMed1993

Tau protein kinase II has a similar characteristic to cdc2 kinase for phosphorylating neurofilament proteins.

Tau protein kinase II purified from a bovine brain tau protein fraction (Ishiguro, K., Takamatsu, M., Tomizawa, K., Omori, A., Takahashi, M., Arioka, M., Uchida, T., and Imahori, K. (1992) J. Biol. Chem. 267, 10897-10901) was shown to have a similar substrate specificity to cdc2 kinase in that both phosphorylate neurofilament (NF) proteins. Tau protein kinase II recognized the dephosphorylated form of the heavy subunit of NF (NF-H) as a predominant substrate. The substrate was phosphorylated to the same extent with tau protein kinase II as with cdc2 kinase. Upon phosphorylation, the electrophoretic mobility of the NF-H on SDS-polyacrylamide gel electrophoresis changed to the position of the phosphorylated form. A synthetic peptide containing a KSPXK sequence was by far a better substrate for tau protein kinase II than that containing a KSPXX sequence, as was also observed with cdc2 kinase. NF-H lost its microtubule-associating ability upon phosphorylation with tau protein kinase II as well as with cdc2 kinase. Although anti-PSTAIR antibody (PSTAIR is an amino acid sequence commonly found in cdc2 and several cdc2-related kinases) failed to react with tau protein kinase II, tau protein kinase II bound to p13suc1-Sepharose beads (p13suc1 is a yeast protein known to bind to cdc2 kinase).

Amino Acid Sequence↗
PubMed1993

Neonatal glutamate can destroy the hippocampal CA1 structure and impair discrimination learning in rats.

Neonatal Wistar rats were subcutaneously injected with 0.1, 1, or 2 mg/g b.wt. of monosodium glutamate (MSG) at 1, 3, 5, 7, and 9 days after birth. The animals were observed for degeneration of pyramidal cells in the hippocampus. The histological change disappeared when the animals were concurrently injected with glutamate diethyl ester (GDEE), an antagonist of the glutamate receptor. When light-dark discrimination learning was carried out at 10 weeks old, the correct response in the acquisition period was impaired in the animals given 1 and 2 mg/g of neonatal MSG. Their retention scores were also impaired in comparison with the control animal. The behavioral impairment recovered with pre-treatment with GDEE. No significant changes were observed in the concentrations of transmitter substances, including amino acids and monoamines. These results suggest that neonatal MSG destroys the hippocampus and impairs acquisition and retention of discrimination learning through the mechanism of glutamate receptors.

Animals↗
PubMed1993

An immunohistochemical study of the c-erbB-2 oncogene product in intraductal mucin-hypersecreting neoplasms and in ductal cell carcinomas of the pancreas.

BACKGROUND: Intraductal mucin-hypersecreting neoplasm of the pancreas (IMHN) is a unique tumor that has a tendency to spread intraductally. The clinical outcome of IMHN generally is far better than that of pancreatic ductal cell carcinoma. Because of the presence of various cell atypia within the same tumor, it sometimes is difficult to make an accurate histopathologic diagnosis and, therefore, predict its biologic behavior. It has been shown that overexpression of c-erbB-2 protein in breast cancer with lymph node metastases is related to a poor prognosis. Overexpression of c-erbB-2 protein has been reported as an infrequent event in pancreatic ductal cell carcinoma, but little is known in the case of IMHN. METHODS: The expression of c-erbB-2 protein was immunohistochemically investigated in the formaldehyde-fixed, paraffin-embedded tissues of 17 cases of IMHN, and 14 cases of pancreatic ductal cell carcinoma (8 cases with lymph node metastasis), using polyclonal and monoclonal c-erbB-2(p185) antibodies by the avidin-biotin method. RESULTS: Both the polyclonal and monoclonal antibodies showed similar immunostaining for the c-erbB-2 product. Overexpression of the c-erbB-2 product was observed frequently in IMHN (13/17), especially in that with moderate- to high-grade cell atypia (12/12), whereas it was detected in only 1 of 14 cases of pancreatic ductal cell carcinoma (1/14). Among eight cases of pancreatic ductal cell carcinoma with lymph node metastases, overexpression of the c-erbB-2 product in metastatic lesions was detected in two, one of whose primary lesions also overexpressed the oncogene product. CONCLUSIONS: These observations suggest the genetic expression of c-erbB-2 is related to the pathogenesis of IMHN.

Adenocarcinoma, Mucinous↗