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Biomedical subjects

T Kojima

Publications and source records attributed to T Kojima.

At least 109 records · Page 6Linked to original sources
PubMed2001

Occludin regulates actin cytoskeleton in endothelial cells.

Occludin is a major membrane component of tight junctions of endothelial cells, though the role of this molecule is not fully understood. RLE cells, derived from rat lung endothelial cells, express a negligible level of occludin with clear expression of E-cadherin and ZO-1 at cell junctions. Introduction of occludin by transfection induced clear junctional expression of occludin with few or no changes of expression of E-cadherin and ZO-1. The paracellular barrier function, as determined by transelectrical resistance and flux of non-ionic small molecules, was not detectably upregulated. When cells expressing occludin were cocultured with RLE cells null for occludin, clear junctional expression of occludin was observed irrespective of the expression of occludin on the apposing cells. Cortical actin was developed at the site of these occludin positive cell junctions. Treatment of cells with an actin depolymerizing agent, mycalolide B, abolished junctional expression of occludin together with E-cadherin and circumferential actin. ZO-1 showed relative resistance to this actin depolymerizing treatment and was maintained at the cell junctions, though fragmentation of immunoreactivity was detectable. Collectively, junctional expression of occludin was not associated with paracellular barrier function in this cell line. There was, however, a close correlation of occludin with the actin cytoskeleton, indicating a role of occludin as an important molecule in the regulation of the actin cytoskeleton in endothelial cells.

Actins↗
PubMed2001

Studies on the constituents of the leaves of Morus alba L.

Two novel prenylflavanes (1, 2) and a glycoside (3) of 1 were isolated along with six known compounds, isoquercitrin (4), astragalin (5), scopolin (6), skimmin (7), roseoside II (8) and benzyl D-glucopyranoside (9), from the leaves of Morus alba. The inhibitory activities of compounds 1, 2 and 3 on the oxidation of human low density lipoprotein (LDL) were investigated.

Antioxidants↗
PubMed2001

Frequency-dependent electrophysiological effects of flecainide, nifekalant and d,l-sotalol on the human atrium.

To compare the effects of class Ic and III antiarrhythmic agents on the termination and prevention of atrial fibrillation, the present study investigated the use-dependent electrophysiological effects of flecainide, nifekalant and d,l-sotalol on the human atrium. Flecainide significantly prolonged effective refractory period (ERP), intra-atrial conduction time (IACT) and monophasic action potential duration (MAPD), and its effects on ERP and IACT were use-dependent. Nifekalalant significantly prolonged ERP and MAPD, and these effects were reverse use-dependent; however, there was no significant change in IACT. d,l-Sotalol significantly prolonged MAPD and the effect was reverse use-dependent. It significantly prolonged ERP, but the effect was not reverse use-dependent. d,l-Sotalol increased IACT in a use-dependent manner. Thus, for atrial fibrillation, class Ic antiarrhythmic agents might be more effective in termination and class III antiarrhythmic agents might be more effective in prevention.

Action Potentials↗
PubMed2001

Growth-suppressive function of human connexin32 in a conditional immortalized mouse hepatocyte cell line.

Mouse hepatocytes immortalized with a temperature-sensitive allele of the SV40 large T-antigen (CHST8 cells) were found to lack the high expression of the gap junction proteins Cx26 and Cx32 that characterizes normal mouse hepatocytes, expressing instead Cx43 and Cx45 at minimal levels. In order to examine the growth suppressive function of Cx32 on hepatocytes, we transfected these CHST8 cells with human Cx32 complementary deoxyribonucleic acid and measured the growth rates at 33, 37, and 39 degrees C. Expression of human Cx32 and its messenger ribonucleic acid in the stable cell lines was confirmed by immunocytochemistry and by Western and Northern blots analyses. Dye transfer following lucifer yellow injection into the transfectants was extensive; Cx32 channels displayed unitary conductances of about 70 pS and were moderately voltage sensitive. When cultured at 33 and 39 degrees C, growth rates of both parental cells and transfectants were of the same level. When examined at 37 degrees C, growth rate of the transfectant, which highly expressed Cx32 at the membranes, was significantly decreased compared to the parental cells. However, no changes in the expression of Cx32 protein in the transfectants were observed between 33 and 37 degrees C. These results suggest that Cx32 expression could inhibit hepatocyte growth in vitro using the conditional immortalized cells. Cx32 transfectants using a conditional immortalized mouse hepatocyte may be useful for examining the mechanisms of growth and differentiation in hepatocytes by gap junction expression.

Animals↗
PubMed2001

Dynamic changes in plasma concentrations of gonadotropins, inhibin, estradiol-17beta and progesterone in cows with ultrasound-guided follicular aspiration.

To elucidate the effects of ultrasound-guided transvaginal follicular aspiration, plasma concentrations of FSH, LH, inhibin, estradiol-17beta and progesterone, and folliculogenesis were examined in Holstein cows. Four clinically healthy cows with regular estrous cycles were scanned by ultrasound per rectum once a week for 9 weeks before the commencement of follicular aspiration. All visible follicles were divided into 3 categories based on their sizes (2 < or = small < 5 mm; 5 < or = medium < 10 mm, large > or = 10 mm). The follicular aspiration was started at random during the estrous cycle and conducted under epidural anesthesia induced with 5 ml of 2% lidocaine once a week for 6 weeks. The average number of total visible follicles > or = 2 mm in diameter at 7 days after aspiration (21.7 +/- 7.4, n = 24) was similar to that before starting aspiration (26.7 +/- 10.5, n = 36). Plasma inhibin and estradiol-17beta declined and fell to a trough on 1.5 days and returned to pre-aspiration values by 5 days after aspiration. Plasma concentrations of FSH increased and reached peak levels between 1 and 1.5 days after aspirations. Plasma concentrations of LH also increased and reached peak levels between 0.5 and 1.5 days after aspirations. Both plasma FSH and LH had returned to pre-aspiration levels by 5 days after aspirations. Plasma concentrations of progesterone did not change with the follicular aspiration. These results demonstrate that follicular aspiration decreases plasma concentrations of inhibin and estradiol-17beta, which in turn leads to a rise in plasma concentrations of FSH and LH. It is suggested that marked increases in plasma concentrations of FSH and LH after the aspiration stimulate the development and maturation of a new cohort of follicles within one week in cows.

Animals↗
PubMed2001

Reappraisal of the historic 1959 cat experiment in Minamata by the Chisso Factory.

Autopsy specimens from the historic cat experiment were recently discovered in a storage area at the Kumamoto University School of Medicine. The specimens were from an experiment prompted by physicians in the Chisso Minamata Plant following the announcement made by the Study Group for Minamata disease. On July 14, 1959 the Group announced that the disease was most likely caused by a kind of organic mercury. In order to prove or disprove that industrial waste from the Chisso Factory was the culprit in Minamata disease, a total of ten cats were fed food mixed with industrial waste produced in the acetaldehyde-producing plant. One of the ten cats, No. 717, was subsequently autopsied but the autopsy findings have never been published or recorded in the literature despite their historic significance. The rediscovered specimens were studied pathologically and biochemically, and were analyzed chemically with currently available techniques. Characteristic lesions of methylmercury poisoning were observed in the central nervous system, and the mercury levels in the cerebrum, cerebellum, liver and kidney were found to be markedly elevated in this animal.

Animals↗
PubMed2001

Os odontoideum associated with hypertrophic ossiculum terminale. Case report.

The authors report on the case of a 20-year-old man who presented with a transient tetraparesis. Neuroimaging studies demonstrated atlantoaxial dislocation and ventral compression of the rostral spinal cord caused by a quite rare association of os odontoideum and hypertrophic ossiculum terminale. The patient underwent removal of two free ossicula via a transoral approach and posterior fusion in which an autogenous bone graft was placed. The majority of cases of os odontoideum are believed to be an acquired form; however, controversy with regard to the congenital causes of os odontoideum remains. One hypothesis is that os odontoideum results from the failure of fusion and the hypertrophy of the proatlas, although considerable confusion surrounds this hypothesis because definitive classification of os odontoideum-to differentiate between similar anomalies-has not been established. This rare coincidence in the current case supports the belief that os odontoideum has a different embryological origin from ossiculum terminale, which is thought to be a proatlantal remnant.

Abnormalities, Multiple↗
PubMed2001

[Origin of sennosides in health teas including Malva leaves].

The aim of this study is to clarify whether sennosides are contained in the leaf of Malva verticillata L., and then to clarify the source of sennosides in health teas including malva leaves. The identification and determination of sennosides were performed with thin layer chromatography and high performance liquid chromatography. The leaf of Malva verticillata L. did not contain sennosides A or B and could be easily distinguished from senna leaf. Our previous report showed that sennosides are contained in weight-reducing herbal teas including malva leaves, and that senna leaf is a herbal component in some teas. Furthermore, in 10 samples of health tea including malva leaves that were bought last year, the smallest amount of sennosides was 6.1 mg/bag, and all health teas including malva leaves contained the leaf and midrib of senna. We suggest that sennosides A and B are not contained in the leaf of Malva verticillata L., and that the sennosides in health teas including malva leaves are not derived from malva leaf but from senna leaf.

Anthraquinones↗
PubMed2001

Evidence for involvement of central 5-HT(4) receptors in cholinergic function associated with cognitive processes: behavioral, electrophysiological, and neurochemical studies.

The possible involvement of 5-HT(4) receptors in cognitive function was investigated with a view toward modulating the cholinergic neuronal system. For this purpose, behavioral, electrophysiological, and neurochemical studies were performed in rats. The behavioral study, using a passive avoidance test, demonstrated that the 5-HT(4) receptor agonist SC 53116 (10 microg/rat i.c.v.) had an ameliorative effect on the muscarinic receptor antagonist scopolamine-induced (1 mg/kg i.p.) impairment of learning. The electrophysiological study showed that SC 53116 (1 and 10 microg/rat i.c.v.) enhanced the population spike amplitude in the hippocampal CA1 field evoked by Schaffer collateral stimulation. SC 53116 (10 microg/rat i.c.v.) also augmented the tetanus-induced long-term potentiation (LTP). This augmented LTP was blocked not only by the selective 5-HT(4) receptor antagonist GR 113808 (20 microg/rat i.c.v.) but also by scopolamine (1 mg/kg i.p.). These findings suggest that the functional interaction between the serotonergic system mediated via 5-HT(4) receptors and the cholinergic system associated with cognitive processes exists in vivo. This possibility was further strengthened by neurochemical study using in vivo microdialysis; local administration of SC 53116 (10 and 100 microM) concentration-dependently enhanced the extracellular levels of acetylcholine (ACh) in the hippocampus. SC 53116-induced (10 microM) facilitation of ACh release was prevented by coperfusion of GR 113808 (10 microM). Taken together, the present findings obtained by these different approaches indicate the possibility that the 5-HT(4) receptors are involved in cognitive impairment induced by the cholinergic neuronal system.

Acetylcholine↗
PubMed2001

Plasma levels of syndecan-4 (ryudocan) are elevated in patients with acute myocardial infarction.

Syndecan-4 (ryudocan) is a cell-surface heparan sulfate proteoglycan, which plays an important role in a variety of biological functions including regulation of blood coagulation. cell adhesion, and cell growth. In this study, we measured plasma levels of syndecan-4 in patients with acute myocardial infarction using an enzyme-immunoassay, and found that they were extremely high, with a peak of average (10.5 +/- 5.6 ng/ml, 2 weeks after onset), as compared with those in normal subjects (0.078 +/- 0.030 ng/ml) (p < 0.001). We also observed a distinct expression of syndecan-4 in the repair region of the damaged cardiac tissues with infarction, but not in intact region, by immunohistochemical analysis. To clarify the mechanism of syndecan-4 induction, we investigated the hypoxia effect on its expression, and found that hypoxia treatment up-regulated the gene expression of syndecan-4 in various types of cells. Taken together, it is suggested that syndecan-4 is induced by hypoxia stimuli in ischemic heart tissues, and may function as a tissue-repair molecule via biological mediators such as heparin-binding growth factors.

Adult↗
PubMed2001

Expression of protein S in the murine heart and cultured mouse cardiomyocytes is down-regulated by cytokines.

Protein S (PS), a co-factor of activated protein C, is a vitamin K-dependent anticoagulant protein and is known to be produced extrahepatically. In the present study, the concentration of PS mRNA was determined tissue by tissue in the mouse, and it was high in lung, adrenal and heart as well as in liver. We further investigated the effects of lipopolysaccharide (LPS), tumor necrosis factor-alpha (TNF-alpha), and interleukin-1 (IL-1) on the PS mRNA expression in murine tissues in vivo. Although LPS and TNF-alpha significantly decreased the expression level of PS mRNA in all tissues examined (e. g., lung, liver, heart, and kidney) and the PS antigen level in plasma, the suppressive effect of IL-1 on PS gene expression was limited to heart. More specifically, considerable amounts of PS mRNA and antigen were expressed in a cultured mouse cardiomyocyte cell line, and again, treatment with IL-1 decreased the PS expression in these cells. These observations raise a possibility that the expression of cardiac PS may contribute to the regional anticoagulant potential in heart, and suggest that the decreased PS expression by cytokines may result in an increase in the systemic and/or regional prothrombotic potential under inflammatory conditions.

Adrenal Glands↗
PubMed2001

Late detection of supraclinoid carotid artery aneurysm after traumatic subarachnoid hemorrhage and occlusion of the ipsilateral cervical internal carotid artery.

BACKGROUND AND PURPOSE: We report the first case of traumatic aneurysm of the supraclinoid internal carotid artery (ICA), which we speculate may have developed or grown after traumatic occlusion of the ipsilateral cervical ICA. CASE DESCRIPTION: A 26-year-old man presented with severe traumatic subarachnoid hemorrhage (SAH) and occlusion of the right cervical ICA after a motor vehicle accident. Three-dimensional CT angiography on admission showed no aneurysm. However, cerebral angiography 3 weeks after the injury showed a large aneurysm of the right supraclinoid ICA. The aneurysm was trapped, and pathological examination showed that it was a traumatic aneurysm. CONCLUSIONS: In this case we cannot be sure that the aneurysm was not present on admission. In view of the significant SAH, a lesson of this case may be to suspect such an aneurysm early on and perform early diagnostic cerebral angiography.

Accidents, Traffic↗
PubMed2001

Large-scale selection of lines with deletions in chromosome 1 B in wheat and applications for fine deletion mapping.

Terminal deletions of chromosome 1B in common wheat were selected on a large scale. The gametocidal gene of Aegilops cylindrica was used as the inducer of chromosome breakage. First, genes for endosperm storage proteins located on both arms of chromosome 1B were used as the selection markers. However, it was found that the chromosome breakage occurred during female gametogenesis, causing genotypic inconsistency between the embryo and endosperm. Thus, we isolated plants with terminal deletions in chromosome 1B by C-banding. Of 1327 plants examined, 128 showed aberrations in chromosome 1B: 47 in the short arm, 76 in the long arm, and 5 in both arms. The present deletions tended to have the breakpoint at more proximal regions than those produced previously by T.R. Endo and B.S. Gill. Using 33 deletion lines produced in this study and 34 lines previously produced, we mapped 39 RFLP loci and a nucleolar organizer region (NOR) on a specific region of chromosome 1B. The NOR was found to consist of two subregions with different repetitive units, which were termed NOR-Bld and NOR-Blp. Based on this fine deletion map and genotypic inconsistency between embryo and endosperm, the features of the gametocidal gene are discussed.

Chromosome Aberrations↗
PubMed2001

[A case of pulmonary dirofilariasis].

A 76-year-old woman admitted to our hospital with abnormal shadow on chest X-ray. Computed tomography demonstrated the 2 x 2 cm of round, well defined tumor on right S6 segment which was suspected to be a malignant tumor. Partial resection was performed with video-assisted thoracotomy (VATS) and histological examination of quickly frozen specimen showed no malignancy. Then, histological examination of formalin fixed specimen showed dirofilariasis. It has been reported 97 cases of dirofilariasis in Japan so far. Although X-ray or biochemical and immunological examination of serum help to diagnose dirofilariasis, difinite diagnosis can be done only by histological evidence of resected specimen. Because of the difficulty for denial the malignant tumor, surgical treatment should be required.

Aged↗
PubMed2001

RAPD and ISSR fingerprints as useful genetic markers for analysis of genetic diversity, varietal identification, and phylogenetic relationships in peanut (Arachis hypogaea) cultivars and wild species.

Abstract: Twenty-one random and 29 SSR primers were used to assess genetic variation and interrelationships among subspecies and botanical varieties of cultivated peanut, Arachis hypogaea (2n = 4x = 40), and phylogenetic relationships among cultivated peanut and wild species of the genus Arachis. In contrast with the previous generalization that peanut accessions lack genetic variation, both random and SSR primers revealed 42.7 and 54.4% polymorphism, respectively, among 220 and 124 genetic loci amplified from 13 accessions. Moreover, the dendrograms based on RAPD, ISSR, and RAPD + ISSR data precisely organized the five botanical varieties of the two subspecies into five clusters. One SSR primer was identified that could distinguish all the accessions analysed within a variety. Although the polymorphic index content varied from 0.1 to 0.5 for both ISSR and RAPD markers, primer index values were substantially higher for RAPD primers (0.35-4.65) than for SSR primers (0.35-1.73). It was possible to identify accessions, particularly those of divergent origins, by RAPD and (or) ISSR fingerprints. Based on these results, marker-based genetic improvement in A. hypogaea appears possible. None of the 486 RAPD and 330 ISSR amplification products were found to be commonly shared among 13 species of section Arachis and one species each of sections Heteranthae, Rhizomatosae, and Procumbentes. Dendrograms constructed from RAPD, ISSR, and RAPD + ISSR data showed overall similar topologies. They could be resolved into four groups corresponding to the species grouped in four taxonomic sections. The present results strongly support the view that Arachis monticola (2n = 4x = 40) and A. hypogaea are very closely related, and indicate that A. villosa and A. ipaensis are the diploid wild progenitors of these tetraploid species.

Arachis↗
PubMed2000

A novel low-density lipoprotein receptor-related protein mediating cellular uptake of apolipoprotein E-enriched beta-VLDL in vitro.

We report here the identification of a novel member of the low-density lipoprotein receptor (the LDL receptor) family through signal sequence trap screening of a mouse lymphocyte cDNA library. The protein was termed LDL receptor-related protein 9 (LRP9). LRP9 is a type I membrane protein predicted to contain 696 amino acids with a calculated molecular mass of 74 764 Da. The NH(2)-terminal half of LRP9 contains two CUB domains separated by a single ligand-binding repeat. The second CUB domain is followed by a cluster of three additional ligand-binding repeats and a transmembrane domain. The COOH-terminal intracellular region contains a proline-rich region. LRP9 mRNA was expressed in the liver, kidney, lung, and heart at high levels, and in the spleen and brain at low levels. In situ hybridization analysis of mouse liver, kidney, and brain detected LRP9 transcripts in hepatocytes, sinusoidal lining cells, peritubular capillaries, choroid plexus, ependyma of the third ventricle, pia matter, and hippocampus. In particular, high levels of expression were observed in the vascular walls. Apolipoprotein E (apoE)-enriched beta-VLDL stimulated cellular cholesteryl ester formation in ldl-A7/LRP9. These results raise the possibility that this newly identified receptor, which is expressed in the liver, may play a physiological role in the uptake of apoE-containing lipoproteins.

Adult↗