Biomedical subjects

Y Takeuchi

Publications and source records attributed to Y Takeuchi.

At least 721 records · Page 40Linked to original sources

PubMed1991

[Early diagnosis of intracranial hemorrhage in the newborn].

A routine ultrasonographic (US) examination is essential for monitoring intraventricular hemorrhage (IVH) in very low-birth-weight newborn infants. The incidence of IVH was decreased by risk factor analysis using US. Subarachnoidal hemorrhage (SAH), subdural hemorrhage (SDH) and intraparenchymal hemorrhage (IPH) occurred more in mature infants who had difficult deliveries. Final diagnosis was established by cranial computed tomography (CT) or careful US examinations. Symptoms and signs of intracranial hemorrhage (ICH) were more non-specific than neurological. The possibility of ICH should always be considered and excluded by CT or US in the infants with nonspecific clinical manifestations.

Cerebral Hemorrhage↗

PubMed1991

Quantitative study of the development of the optic nerve in rats reared in the dark during early postnatal life.

Male rats were placed in complete darkness from birth until 30 days of age, followed in some cases by a 35 days period of rehabilitation in control lighting conditions. Groups of control and experimental animals were killed at 30 and 65 days of age by perfusion with buffered 2.5% glutaraldehyde. The right optic nerve was dissected out from each animal and processed for embedding in Epon. Quantitative stereological procedures were used to estimate the total number of both myelinated and non-myelinated optic nerve fibres and their mean minimum diameters. There were no significant differences in the total number of optic nerve fibres between dark- and light-reared rats. However dark-reared rats had myelinated and non-myelinated fibres with significantly larger fibre diameters than those in age-matched light-reared rats. The proportion of optic nerve fibres which were myelinated increased with age in both groups of animals. However by 65 days of age the degree of myelination was slightly but significantly greater in the previously dark-reared rats than in the light-reared controls. These results indicate that rats reared in complete darkness for the first 30 days of postnatal life show morphological changes in the optic nerves. The possible significance of these changes is discussed.

Animals↗

PubMed1990

Thymic stromal cell clone with nursing activity supports the growth and differentiation of murine CD4+8+ thymocytes in vitro.

Thymic stromal cell clone, TNC-R3.1 cell, was established from spontaneous AKR/J mouse thymoma. TNC-R3.1 cell, which has the similar properties to thymic nurse cells, formed a unique complex with normal thymocyte subpopulations. Flow cytometry analysis demonstrated that CD4+8+ and CD4-8- immature thymocytes preferentially interacted with TNC-R3.1 stromal cell clone. CD4+8+ thymocytes, which interacted with TNC-R3.1 stromal cell clone, contained a higher proportion of large size and cycling T cells than did noninteracting CD4+8+ thymocytes. As is generally accepted, CD4+8+ thymocytes did not respond to any stimulation such as IL-2, anti-CD3 mAb (2C11), or IL-2 plus 2C11. However, culture of isolated CD4+8+ thymocytes on TNC-R3.1 stromal cell monolayer in the presence of suboptimal dose of IL-2 induced a significant cell growth. Moreover, the addition of 2C11 and IL-2 into this coculture system resulted in a dramatic increase of the proliferative response of thymocytes. Flow cytometry analysis showed the proliferating cells on TNC-R3.1, which originated from CD4+8+ thymocytes, were mostly TCR-alpha beta+ CD3+CD4-8+ T cells. These results provide in vitro evidence that CD4+8+ thymocytes are at an intermediate stage of T cell maturation and TNC-R3.1 stromal cell clone induces the growth and differentiation of CD4+8+ thymocytes into CD4-8+ T cells.

Animals↗

PubMed1990

Studies of the immunohistochemical and biochemical localization of the cytochrome P-450scc-linked monooxygenase system in the adult rat brain.

Immunohistochemical and biochemical studies were performed on the brains of adult female and male rats using a specific antibody against bovine adrenocortical cytochrome P-450scc. The results showed that in both male and female rats, the myelinated regions of the white matter are selectively immunostained throughout the brain and that even in rats pretreated with colchicine, there is never positive staining of neuronal cell bodies and their dendrites in any brain region. Western immunoblotting with the P-450scc antibody and enzymatic assays revealed that P-450scc and cholesterol side-chain cleavage activity were present in a homogenate derived from the cortical white matter, but not detectable in that from the cerebral cortex. Furthermore, quantitation of the P-450scc protein in the immunoblots indicated that the concentration of P-450scc in the cortical white matter of both female and male rat brains is approx. 3-4 pmol per mg tissue protein. Thus it could be concluded that in the adult rat brain, P-450scc and cholesterol side-chain cleavage activity are selectively localized only in the myelinated region of the white matter.

Adrenal Cortex↗

PubMed1990

Extracellular calcium regulates distribution and transport of heparan sulfate proteoglycans in a rat parathyroid cell line.

The regulation of the cellular distribution of proteoglycans in a clonal rat parathyroid cell line by extracellular Ca2+ concentrations ([Ca2+]e) was studied. Proteoglycans synthesized by the cells metabolically labeled with [35S]sulfate have been shown to be almost exclusively heparan sulfate (HS) proteoglycans (Yanagishita, M., Brandi, M.L., and Sakaguchi, K. (1989) J. Biol. Chem. 264, 15714-15720), which are generally associated with the plasma membrane. The proportion of HS proteoglycans on the cell surface was approximately 20% in 2.1 mM (high) [Ca2+]e, whereas it increased to 50-60% in 0.05 mM (low) [Ca2+]e. Cell-associated HS proteoglycans redistribute in response to changing [Ca2+]e with a t 1/2 less than 4 min; HS proteoglycans appear on the cell surface as [Ca2+]e decreases and disappear from the cell surface as [Ca2+]e increases. Further, HS proteoglycans on the cell surface recycle to and from an intracellular compartment approximately 10 times before their degradation in low [Ca2+]e but do not recycle in high [Ca2+]e. The distribution of newly synthesized HS proteoglycans is regulated by [Ca2+]e but is independent of [Ca2+]e during biosynthesis. In low [Ca2+]e, at least 50% of the HS proteoglycans pulse-labeled for 10 min are transported from the Golgi complex to the cell surface or to the recycling compartment with a t 1/2 of approximately 20 min. Another approximately 10% appear on the cell surface in either low or high [Ca2+]e in a compartment with a long half-life. Addition of Mg2+ or Ba2+ to the low [Ca2+]e cultures had little effect on the distribution of HS proteoglycans. These observations suggest that [Ca2+]e specifically regulates the distribution and recycling of cell-associated HS proteoglycans in the parathyroid cells.

Animals↗

PubMed1990

A 49-kilodalton phosphoprotein in the Drosophila photoreceptor is an arrestin homolog.

The gene encoding the 49-kilodalton protein that undergoes light-induced phosphorylation in the Drosophila photoreceptor has been isolated and characterized. The encoded protein has 401 amino acid residues and a molecular mass of 44,972 daltons, and it shares approximately 42 percent amino acid sequence identity with arrestin (S-antigen), which has been proposed to quench the light-induced cascade of guanosine 3',5'-monophosphate hydrolysis in vertebrate photoreceptors. Unlike the 49-kilodalton protein, however, arrestin, which appears to bind to phosphorylated rhodopsin, has not itself been reported to undergo phosphorylation. In vitro, Ca2+ was the only agent found that would stimulate the phosphorylation of the 49-kilodalton protein. The phosphorylation of this arrestin-like protein in vivo may therefore be triggered by a Ca2+ signal that is likely to be regulated by light-activated phosphoinositide-specific phospholipase C.

Amino Acid Sequence↗

PubMed1990

Effects of subacute toluene exposure on neuronal and glial marker proteins in rat brain.

The behavior of marker proteins of neurons (gamma-enolase) and glial cells (alpha-enolase, beta-S100 protein and creatine kinase-B) was investigated quantitatively by using enzyme immunoassay systems in toluene-exposed rat brains. Three groups of animals were exposed to toluene vapor at 300 ppm, 1000 ppm, and 3000 ppm, respectively, 8 h/day, 6 days/week, for 2 weeks. After subacute repeated solvent exposure, both neuron-specific gamma-enolase and glial marker proteins displayed an overall concentration-dependent increase tendency in separate brain regions. In cerebrum, only the 3000 ppm group showed a significant increase in alpha-enolase by 27% and creatine kinase-B (CK-B) by 26%. alpha-Enolase and gamma-enolase exhibited a pronounced elevation in cerebellum relative to other brain regions, while beta-S100 protein appeared to be the most markedly altered marker in brainstem. The development of gliosis, which is a frequent phenomenon following CNS damage, is presumed to be responsible for the elevation of glial marker content. Energy metabolism disruption in brain tissues may also bring about the compensatory oversynthesis of glycolytic enzymes such as gamma-enolase, alpha-enolase and CK-B. The dose-dependent alteration patterns following toluene exposure suggest the feasibility of using these brain specific markers to evaluate solvent-induced CNS effects.

Animals↗

PubMed1990

Synthesis and secretion of human chorionic gonadotropin and its subunits in choriocarcinoma cells: a comparative study with normal placental cells.

The human choriocarcinoma cell line, BeWo, synthesizes the glycoprotein hormone, human chorionic gonadotropin (hCG). We have undertaken this study to compare the synthesized and secreted forms of hCG and their alpha- and beta-subunits in cell cultures of BeWo cells to those forms of normal placental cells by immunobinding techniques. BeWo cells appeared to synthesize and secrete one species of the respective hCG subunit. The immature alpha- and beta-subunits, synthesized in BeWo cells as well as those of placental cells, were digested by endoglycosidase H indicating N-linked sugar chain(s) to be the high-mannose type. The mature alpha- and beta-subunits, secreted by BeWo cells as well as subunits of urinary hCG which are usually used as a standard hCG secreted by normal placental cells, were sensitive to neuraminidase treatment indicating that these subunits have terminal sialic acid(s). Contrary to placental cells, mature subunits of BeWo hCG could not be found in any subcellular fraction indicating a rapid secretion rate or supporting the hypothesis that BeWo cells secrete hCG subunits without the formation of secretory granules. The alpha-subunit synthesized in BeWo cells had a slightly lower molecular weight than that of placental cells; however, the alpha-subunit secreted by BeWo cells had a slightly higher molecular weight than the alpha-subunit of urinary hCG. The beta-subunits synthesized and secreted by BeWo cells had slightly higher molecular weights than beta-subunits of both placental cells and urinary hCG. Even after digestion by N-glycanase as well as endoglycosidase H, molecular weights were still different between the respective subunits of BeWo and placental cells indicating that the apoprotein structures of BeWo hCG subunits may differ from those of placental cells. Moreover, urinary beta-subunit was sensitive to endo-alpha-N-acetylgalactosaminidase treatment but the beta-subunit secreted by BeWo cells was not, indicating that the structure of O-linked sugar chain(s), if present, may be unusual. Analysis of assembled and free forms of subunits of BeWo cell cultures by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under nonreducing conditions followed by immunobinding methods revealed that subunits are associated intracellularly and then secreted to the media as hCG. Moreover, only free beta-subunits, but not alpha-subunits, of BeWo hCG were found intra- and extracellularly.

Acetylglucosaminidase↗

PubMed1990

Isolation and characterization of proteoglycans synthesized by mouse osteoblastic cells in culture during the mineralization process.

Proteoglycans in mineralized (0.5 M-EDTA/4 M-guanidinium chloride-extractable) and non-mineralized (4 M-guanidinium chloride-extractable) matrices synthesized by a mouse osteoblastic-cell line MC3T3-E1 were characterized at different phases of mineralization in vitro. Cell cultures were labelled with [35S]sulphate and either [3H]glucosamine or 3H-labelled amino acids. At the mineralization phase a large majority of proteoglycans were extracted with 4 M-guanidinium chloride (G extract), and at least five species of labelled proteoglycans were identified; dermatan sulphate proteoglycans (DSPG), apparent Mr approx. 120,000 and 70,000), heparan sulphate proteoglycans (HSPG, apparent Mr approx. 200,000 and 120,000) and DS chains with very little core protein. DSPGs weakly bound to an octyl-Sepharose CL-4B column and HSPGs bound more tightly, whereas DS chains did not bind to the column. Amounts of labelled proteoglycans extracted with 0.5 M-EDTA/4 M-guanidinium chloride (EDTA extract) were much less than those in G extract. Although the predominant species in the EDTA extract were comparable with the DS or DSPGs in the G extract, none of them bound to octyl-Sepharose CL-4B, indicating their lack of hydrophobicity. At the nonmineralizing phase a large chondroitin sulphate proteoglycan (Mr greater than 600,000) was found in the matrix in addition to the five proteoglycan species similar to those at the mineralization phase. Although DS chains at the early phase were similar in size to those at the mineralization phase, the ratio of 2-acetamido-2-deoxy-3-O-(beta-D-gluco-4-enepyranosyluronic acid)-4-O-sulpho-D-galactose to 2-acetamido-2-deoxy-3-O-(beta-D-gluculo-4-enepyranosyluronic acid)-6-O-sulpho-D-galactose was less than that at the mineralization phase. These results agree with those of previous studies performed in vivo and suggest that alteration in the synthesis of proteoglycans is involved in the mineralization process. They also suggest that at the osteoblastic mineralization front proteoglycans undergo partial degradation and lose their hydrophobicity.

Animals↗

PubMed1990

Changes in urinary n-hexane metabolites by co-exposure to various concentrations of methyl ethyl ketone and fixed n-hexane levels.

To make clear how the n-hexane metabolism is modified by co-exposure with MEK, rats were exposed to various concentrations of MEK mixed with a fixed concentration of n-hexane. Twenty-four male Wistar rats were divided into four equal groups. Each group was exposed for 8 h to 2000 ppm n-hexane, 2000 ppm n-hexane plus 200 ppm MEK, 2000 ppm n-hexane plus 630 ppm MEK and 2000 ppm n-hexane plus 2000 ppm MEK, respectively. Free metabolites and the sum of free and conjugated metabolites of n-hexane were analyzed by gas chromatography. The main metabolite was 2-hexanol during the exposure and 2,5-hexanedione (2,5-HD) after the exposure in any group. The main metabolites, 2-hexanol and 2,5 HD, decreased in inverse proportion to the co-exposed MEK concentrations. The results suggest that augmentation of n-hexane neurotoxicity by MEK co-exposure could not be explained only by 2,5-HD. In addition, 2,5-HD is recommended as an index for biological monitoring of n-hexane exposure. However, one should be careful to evaluate the exposed n-hexane concentration by urinary 2,5-HD, because n-hexane metabolism could be largely modified by co-exposure with MEK.

Administration, Inhalation↗

PubMed1990

Effects of MEK on kinetics of n-hexane metabolites in serum.

The neurotoxicity of n-hexane is thought to be caused ultimately by 2,5-hexanedione (2,5-HD), one of the n-hexane metabolites. The potentiation of n-hexane neurotoxicity by co-exposure with MEK, therefore, is suspected to be related to kinetics of 2,5-HD in blood. To clarify the kinetics of n-hexane metabolites in the mixed exposure of n-hexane and MEK, rats were exposed to 2000 ppm n-hexane or a mixture of 2000 ppm n-hexane and 2000 ppm MEK, and the time courses of serum n-hexane metabolites were determined. 2,5-HD in serum increased until 2 h after the end of exposure, when serum 2,5-HD concentration reached a peak of 16.35 micrograms/ml in the n-hexane-alone group. In contrast, 2,5-HD in the mixed exposure group increased much more slowly during and after exposure than in the n-hexane-alone group. It reached a peak of 2.12 micrograms/ml at 8 h after the end of exposure. Serum MBK, a precursor of 2,5-HD in the co-exposure group, was about half in the n-hexane-alone group during exposure. However, MBK decreased more slowly in the co-exposure group than in the n-hexane-alone group after the end of the exposure. The results suggest that co-exposed MEK might inhibit oxidation of n-hexane and decrease clearance of n-hexane metabolites. Co-exposed MEK did not increase serum 2,5-HD, which was considered a main neurotoxic metabolite. Therefore the enhancement of neurotoxicity could not be attributed to increased serum 2,5-HD in the co-exposed group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Coronary revascularization in a child with Kawasaki disease: use of right gastroepiploic artery.

In coronary insufficiency produced by Kawasaki disease, myocardial revascularization using saphenous vein, internal mammary arteries, and a combination of both grafts has been performed with considerable success. Recently, we successfully used a right gastroepiploic artery as another conduit in coronary revascularization of a 6-year-old boy with Kawasaki disease. Use of the gastroepiploic artery was feasible even in a small child, and this technique is expected to contribute to long-term graft patency as an arterial graft adjunct to internal mammary arteries.

Child↗

PubMed1990

Conflict between the need to forage and the need to avoid competition: persistence of two-species model.

We consider a model in which the need to forage and the need to avoid a competitor are in conflict. The model is composed of two Lotka-Volterra patches. The system has two competitors; one can diffuse between two patches, but the other is confined to one of the patches and cannot diffuse. It is proved that the system can be made persistent under appropriate diffusion conditions that ensure the instability of boundary equilibria, even if the competitive patch is not persistent without diffusion. Further it is shown that the system is globally stable for any diffusion rate if the competition between the two species is weak.

Animals↗

PubMed1990

Dose response of N-butyl-N-(4-hydroxybutyl)nitrosamine on urinary bladder carcinogenesis in mutant ODS rats lacking L-ascorbic acid synthesizing ability.

With a daily intake of 250 ppm total ascorbic acid, ODS and F344 male rats were given 0.0125%, 0.025% or 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in the drinking water for 12 weeks, and additional groups received 0.05% BBN for 2, 4 or 8 weeks. The experiment was terminated after a total of 36 weeks. A greater response to urinary bladder carcinogenesis was observed in both strains with increasing dose of BBN or longer treatment period. However, the magnitude of urinary bladder carcinogenesis in ODS rats given the higher BBN concentrations and/or long periods of BBN treatment was less than in comparably treated F344 rats, but not with lower concentrations of BBN and/or shorter periods of BBN treatment.

Animals↗

PubMed1990

Peptide displacement of [3H]5-hydroxytryptamine binding to bovine cortical membranes.

Chemical studies have demonstrated that peptides such as the encephalitogenic (EAE) peptide of myelin basic protein (MBP) and luteinizing hormone-releasing hormone (LHRH) can bind serotonin (5-hydroxytryptamine, 5-HT) in vitro. The present research was undertaken to determine whether such binding interferes with 5-HT binding to its 5-HT1 receptors on bovine cerebral cortical membranes. EAE peptide and LHRH displaced [3H]5-HT with IC50s of 4.0 x 10(-4) and 1.8 x 10(-3) M respectively. MBP itself also showed apparent displacing ability with an IC50 of 6.0 x 10(-5) M, though it also caused aggregation of cortical membranes that might have interfered with normal receptor binding. These results support previous suggestions that the tryptophan peptide region of MBP may act as a 5-HT receptor in the neural system. We also tested the effects of muramyl dipeptide (N-acetyl-muramyl-L-Ala-D-isoGln, MD), a bacterial cell-wall breakdown product that acts as a slow-wave sleep promoter, binds to LHRH and EAE peptide, and competes for 5-HT binding sites on macrophages. It showed no significant displacement of 5-HT binding to cortical membranes (IC50 greater than 10(-1) M), but its D-Ala analogue did (IC50 = 1.7 x 10(-3) M). Thus, it seems likely that the 5-HT-related effects of naturally occurring muramyl peptides are physiologically limited by receptor types.

Acetylmuramyl-Alanyl-Isoglutamine↗

PubMed1990

Afferent fibers in the hypoglossal nerve: a horseradish peroxidase study in the cat.

The existence of afferent fibers in the cat hypoglossal nerve was studied by transganglionic transport of horseradish peroxidase (HRP). Injections of wheat germ agglutinin-conjugated HRP (WGA-HRP) into the hypoglossal nerve resulted in some retrograde labeling of cell bodies within the superior ganglia of the ipsilateral glossopharyngeal and vagal nerves. A few labeled cell bodies were also present ipsilaterally within the inferior ganglion of the vagal nerve and the spinal ganglion of the C1 segment. Some of the labeled glossopharyngeal and vagal fibers reached the nucleus of the solitary tract by crossing the dorsal portion of the spinal trigeminal tract. Others distributed to the spinal trigeminal nucleus pars interpolaris and to the ventrolateral part of the medial cuneate nucleus by descending through the dorsal portion of the spinal trigeminal tract. In the spinal cord these descending fibers, intermingling with labeled dorsal root fibers, distributed to laminae I, IV-V and VII-VIII of the C1 and C2 segments. Additional HRP experiments revealed that the fibers in laminae VII-VIII originate mainly from dorsal root of the C1 segment.

Animals↗

PubMed1990

Heparan sulphate proteoglycans on rat parathyroid cells recycle in low Ca2+ medium.

A rat parathyroid cell line, with some differentiated properties of the parathyroid gland, synthesizes predominantly a heparan sulphate proteoglycan (HS-PG) typical of cell surface HS-PGs (core protein = approximately 70 kDa, three to four HS chains of approximately 30 kDa). A 10 min pulse-chase protocol was used to determine the metabolic fate of the HS-PGs for cells maintained in 2.1 mM-Ca2+ (high Ca) or in 0.05 mM-Ca2+ (low Ca). In low Ca, approximately 60% of the labelled HS-PGs reach the cell surface (t1/2 = approximately 15 min) as determined by trypsin accessibility. This population of HS-PGs recycles (t1/2 = approximately 9 min) between the cell surface and an intracellular (presumably endosome) compartment. After approximately 2 h, this population of HS-PGs is internalized and rapidly degraded in lysosomes. In high Ca, only approximately 10% of the HS-PGs reach the cell surface, where they do not recycle. Changing from high to low Ca any time between 30-120 min of chase, rapidly (t1/2 less than 4 min) redistributes the HS-PGs to the cell surface where they begin recycling; conversely, changing from low to high Ca leads to a rapid sequestration of the cell surface HS-PGs within the cells. Other divalent cations fail to mimic the response to Ca2+. The results suggest that most of the HS-PGs in this cell line are anchored in a membrane compartment involved in a transport process between endosomes and the cell surface which is regulated by the concentration of extracellular Ca2+.

Animals↗

PubMed1990

Molecular Cloning and Ethylene Induction of mRNA Encoding a Phytoalexin Elicitor-Releasing Factor, beta-1,3-Endoglucanase, in Soybean.

Soybean (Glycine max) beta-1,3-endoglucanase (EC 3.2. 1.39) is involved in one of the earliest plant-pathogen interactions that may lead to active disease resistance by releasing elicitor-active carbohydrates from the cell walls of fungal pathogens. Ethylene induced beta-1,3-endoglucanase activity to 2- to 3-fold higher levels in cotyledons of soybean seedlings. A specific polyclonal antiserum raised against purified soybean beta-1,3-endoglucanase was used to immunoprecipitate in vitro translation products, demonstrating that ethylene induction increased translatable beta-1,3-endoglucanase mRNA. Several cDNA clones for the endoglucanase gene were obtained by antibody screening of a lambda-gt11 expression library prepared from soybean cotyledons. Hybrid-select translation experiments indicated that the cloned cDNA encoded a 36-kilodalton precursor protein product that was specifically immunoprecipitated with beta-1,3-endoglucanase antiserum. Escherichia coli cells expressing the cloned cDNA also synthesized an immunologically positive protein. Nucleotide sequence of three independent clones revealed a single uninterrupted open reading frame of 1041 nucleotides, corresponding to a polypeptide of 347 residue long. The primary amino acid sequence of beta-1,3-endoglucanase as deduced from the nucleotide sequence was confirmed by direct amino acid sequencing of trypsin digests of the glucanase. The soybean beta-1,3-endoglucanase exhibited 53% amino acid homology to a beta-1,3-glucanase cloned from cultured tobacco cells and 48% homology to a beta-(1,3-1,4)-glucanase from barley. Utilizing the largest cloned cDNA (pEG488) as a hybridization probe, it was found that the increase in translatable beta-1,3-endoglucanase mRNA seen upon ethylene treatment of soybean seedlings was due to 50- to 100-fold increase in steady state mRNA levels, indicating that ethylene regulates gene expression of this enzyme important in disease resistance at the level of gene transcription.

Journal Article↗