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Biomedical subjects

K Tsuji

Publications and source records attributed to K Tsuji.

At least 145 records · Page 8Linked to original sources
PubMed1999

Soluble interleukin-6 (IL-6) receptor with IL-6 stimulates megakaryopoiesis from human CD34(+) cells through glycoprotein (gp)130 signaling.

We have recently shown that stimulation of glycoprotein (gp) 130, the membrane-anchored signal transducing receptor component of IL-6, by a complex of human soluble interleukin-6 receptor (sIL-6R) and IL-6 (sIL-6R/IL-6), potently stimulates the ex vivo expansion as well as erythropoiesis of human stem/progenitor cells in the presence of stem cell factor (SCF). Here we show that sIL-6R dose-dependently enhanced the generation of megakaryocytes (Mks) (IIbIIIa-positive cells) from human CD34(+) cells in serum-free suspension culture supplemented with IL-6 and SCF. The sIL-6R/IL-6 complex also synergistically acted with IL-3 and thrombopoietin (TPO) on the generation of Mks from CD34(+) cells, whereas the synergy of IL-6 alone with TPO was barely detectable. Accordingly, the addition of sIL-6R to the combination of SCF + IL-6 also supported a substantial number of Mk colonies from CD34(+) cells in serum-free methylcellulose culture, whereas SCF + IL-6 in the absence of sIL-6R rarely induced Mk colonies. The addition of monoclonal antibodies against gp130 to the suspension and clonal cultures completely abrogated the megakaryopoiesis induced by sIL-6R/IL-6 in the presence of SCF, whereas an anti-TPO antibody did not, indicating that the observed megakaryopoiesis by sIL-6R/IL-6 is a response to gp130 signaling and independent of TPO. Furthermore, human CD34(+) cells were subfractionated into two populations of IL-6R-negative (CD34(+) IL-6R-) and IL-6R-positive (CD34(+) IL-6R+) cells by fluorescence-activated cell sorting. The CD34(+) IL-6R- cells produced a number of Mks as well as Mk colonies in cultures supplemented with sIL-6R/IL-6 or TPO in the presence of SCF. In contrast, CD34(+) IL-6R+ cells generated much less Mks and lacked Mk colony forming activity under the same conditions. Collectively, the present results indicate that most of the human Mk progenitors do not express IL-6R, and that sIL-6R confers the responsiveness of human Mk progenitors to IL-6. Together with the presence of functional sIL-6R in human serum and relative unresponsiveness of human Mk progenitors to IL-6 in vitro, current results suggest that the role of IL-6 may be mainly mediated by sIL-6R, and that the gp130 signaling initiated by the sIL-6R/ IL-6 complex is involved in human megakaryopoiesis in vivo.

Antigens, CD↗
PubMed1999

Regulation of worker reproduction by direct physical contact in the ant Diacamma sp. from Japan.

We investigated the function and transmission of signals that regulate worker reproduction in the ponerine ant Diacamma sp. from Japan, in which the morphological queen caste is absent and a mated worker (gamergate) reproduces as a functional queen in each colony instead. An inhibitory effect of a gamergate pheromone has been inferred in this species, because virgin workers frequently lay eggs in colonies without a gamergate, but rarely do so in the presence of one. We restricted the movements of gamergates and workers in experimental nests: one group of workers always had a gamergate present; another group had no gamergate; and a third group could choose between having contact with a gamergate and avoiding contact. Only workers that had no contact with a gamergate were aggressive and developed ovaries with fully mature oocytes. The gamergate signal was thus nonvolatile and passed on only by direct physical contact with workers. Theoretically, there should be a gamergate-worker conflict over male production; however, workers apparently responded to the gamergate's presence by refraining from egg laying. The gamergate signal may inform workers of the presence of a gamergate who can police their reproduction. Even when given the opportunity to avoid direct contact with the gamergate and thereby escape its policing, the workers did not do so and never oviposited. This behaviour may be a kin-selected trait, which mediates workers' sterility and in turn enhances colony efficiency. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1999

Familial primary biliary cirrhosis in Hiroshima.

Primary biliary cirrhosis (PBC) is an autoimmune liver disease characterized by the presence of anti-mitochondrial antibodies and chronic inflammatory destruction of septal and intrahepatic bile ducts. Although there are no obvious associations of PBC with MHC class I or class II genes, there appears to be a significant increased risk of developing disease within families. Clearly, a combination of genetic and environmental factors play a role in disease pathogenesis, although the relative contributions of each are unclear. In this study, we have taken advantage of the well-defined health-care system in Hiroshima prefecture, where PBC is a reportable disease. In the period 1988-1997, 156 new patients with PBC in a total population of 2,873,000 were diagnosed. These patients included 18 subjects that were derived from eight different families in which more than one family member had a history of PBC; this reflects a frequency of 5.1% and further shows that the prevalence of PBC is greatly increased in family members. Of interest, the median age of onset of PBC in second generation patients was much younger (33.4+/-10.8 years) compared to median disease onset in general patients with PBC in Hiroshima (55.6+/-12 years). In fact, it was striking that the onset of disease in family members often occurred within a few years of each other. We also noted that sera of affected members had similar AMA reactive profiles against recombinant PDC-E2, BCKD-E2 and OGDC-E2; the major autoantigens of PBC. Similar HLA types were found within affected members of a pedigree but the data is limited because of absence of similar typing of unaffected members. The increased family history of PBC, and the earlier onset of disease in second generation members, suggests that environmental agents are an important risk factor for the development of disease. We suggest that genomic analysis in familial PBC will be important to identify the mechanisms of genetic susceptibility.

Adult↗
PubMed1999

Neurochemical characteristics and behavioral responses to psychological stress in ovariectomized rats.

The present study was designed to clarify the time-dependent changes in brain monoamine turnover in the frontal cortex, hypothalamus, hippocampus, septum and amygdala after ovariectomy, and the difference in behavioral responses to psychological stress between sham-operated and ovariectomized (OVX) rats. At 2 and 4 weeks after ovariectomy, the turnover rates of dopamine and norepinephrine in all of the brain regions examined did not differ significantly between the sham-operated and OVX rats. However, 5-hydroxytryptamine (5-HT) turnover in all of the brain regions at 2 weeks after OVX was significantly lower than that in sham-operated rats. This difference was greater in the hypothalamus than in other brain regions. At 4 weeks after ovariectomy, 5-HT turnover in all of the brain regions examined was not significantly different between sham-operated and OVX rats. At 2 and 4 weeks after ovariectomy, exploratory behaviour (e.g., locomotor activity, head- dipping, crossing and rearing behaviours) in a non-stressed ovariectomy group did not differ from that in a non-stressed sham-operation group. Locomotor activity and the number of head-dips and crossings significantly (P<0.05) increased after repeated exposure to psychological stress for 5 days in sham-operated rats, but not in those at 2 weeks after OVX. At 4 weeks after ovariectomy, locomotor activity and the number of crossings and rearings in sham-operated and OVX rats were not significantly different in the psychological stress and non-stress groups. However, the number of head-dips significantly (P<0.05) increased with psychological stress in the sham-operated rats, but not in OVX rats. These results suggest that female gonadal hormones may play an important role in the regulation of brain 5-HTergic systems. These interactions between gonadal hormones and 5-HT metabolism may be related to 5-HT-related neuropsychiatric disorders.

Amygdala↗
PubMed1999

Immunohistochemical distribution of bombesin-positive pulmonary neuroendocrine cells in a congenital diaphragmatic hernia.

Morphometrical analyses of the immunohistochemical expression of bombesin, which is one of the peptides produced by pulmonary neuroendocrine (PNE) cells, were carried out on the bronchioles of human congenital diaphragmatic hernia (CDH) neonates, and the findings were then compared with those in a gestational and postnatal age-matched control group. As a result, no difference was found in the number of bombesin-positive cells between the lungs of the control group and the unaffected side lungs in the CDH group except for the ratio of the bombesin-positive cells per unit of the bronchiolar surface area (P < 0.05). However, compared with the lungs in the control group, the affected side of the lungs in the CDH group showed a significant increase in the expression of bombesin, namely, the ratio of the bombesin-positive cells per bronchiole (P < 0.05), the ratio of the bombesin-positive cells per unit perimeter of the bronchioles (P < 0.05), and the ratio of the bombesin-positive cells per unit of the bronchiolar surface area (P < 0.01). These results thus suggest that hyperplasia of the PNE-cell system in the lungs of the CDH cases, especially on the affected side, exists in human fetuses. We also further speculate that PNE cells may thus play a role in the problems associated with CDH during intrauterine life in human beings.

Biometry↗
PubMed1999

Photoperiod-sensitive cytoplasmic male sterility in wheat: nuclear-mitochondrial incompatibility results in differential processing of the mitochondrial orf25 gene.

An alloplasmic wheat line with the cytoplasm of Aegilops crassa expresses photoperiod-sensitive cytoplasmic male sterility (PCMS). Southern- and Northern-hybridization analyses showed that this line contains alterations in both the gene structure and transcription patterns of the mitochondrial gene orf25. In this study, the nucleotide sequence around the orf25 gene of Ae. crassa (CR-orf25) and common wheat (AE-orf25) was determined, and we found that the upstream region of CR-orf25 had been replaced by that of rps7 of common wheat (AE-rps7) through recombination. A novel open reading frame (orf48) is present upstream of CR-orf25. In these three genes, transcription was initiated from the consensus promoter motif of plant mitochondrial genes located in the upstream regions. Processing enzymes in Ae. crassa and common wheat cleave the respective precursor mRNAs, namely CR-orf25 and AE-rps7, at sites similar to that of the premature mitochondrial 26S rRNA. In contrast, the precursor mRNA is not effectively processed at the target sequence of CR-orf25 in the alloplasmic wheat line. Because major transcripts of the euplasmic CR-orf25 and AE-rps7 genes would result in a truncated orf48 product, one possibility is that the orf48 protein might disturb mitochondrial function at a specific stage and hence affect the expression of the PCMS trait.

Amino Acid Sequence↗
PubMed1999

Specific binding and effects of dehydroepiandrosterone sulfate (DHEA-S) on skeletal muscle cells: possible implication for DHEA-S replacement therapy in patients with myotonic dystrophy.

Dehydroepiandrosterone (DHEA) and its sulfate (DHEA-S) are the most abundant steroidal products and major circulating steroids in humans. The serum concentrations of DHEA-S are lower in patients with myotonic dystrophy (DM) than normal controls, and possible improvement of myotonia and muscle weakness was recently reported following DHEA-S replacement therapy. However, the molecular mechanism of action of DHEA-S remains unknown. To understand the reported anti-DM action of DHEA-S, we investigated DHEA-S binding in skeletal muscle cells in vitro. We identified two populations of DHEA-S binding sites (Kd = 5-9 microM and 35-40 microM) in C2C12 myocytes. Similar binding sites were also identified in human skeletal muscles. The Kd value of the high-affinity site was within the range of serum concentrations of DHEA-S in adult humans. Our results suggest that DHEA-S might act directly on skeletal muscles under normal physiological conditions in humans.

Animals↗
PubMed1999

Delayed hyperacute xenograft rejection in porcine to canine fetal liver transplantation.

Fetal tissues are generally considered to express weaker antigenic cell-surface molecules than adult tissues. We have reported that transplantation of porcine fetal liver tissue (fragments) is useful for acute and chronic hepatic failure in rats. We further investigated, in the present study, whether transplantation of a porcine fetal liver has the advantage of delayed hyperacute xenograft rejection (HAR) in comparison with that of an adult liver. Porcine fetal liver heterotopically transplanted into dogs was compared. Haematoxylin-eosin (HE) and immunohistochemical studies using IgM, C3, IgG antibodies were performed in serial biopsies of the liver grafts. Lectin binding to target antigen epitopes on pig and dog tissues was studied by flow cytometry. Carbohydrate expression on the liver was also studied by immunohistochemistry. The macroscopic and HE section findings indicate that HAR started 15 min postgraft in fetal and adult liver grafts. Thereafter, vascular changes and parenchymal damage progressed more rapidly in the adult grafts. The final HAR time in adult liver transplantation was determined to be 60 min, while it was determined to be 180 min in fetal liver transplantation. IgM, C3 and IgG were deposited more strongly in the adult grafts than in the fetal grafts up until 60 min after xenografting. Phaseolus vulgaris erythroagglutinin lectin competitively blocked dog sera binding to porcine PBLs. The fetal liver expressed oligosaccharide at a significantly lower level than the adult liver. We conclude that porcine fetal liver xenografts had a significantly delayed HAR.

Acute Disease↗
PubMed1999

Effects of tea polyphenols on the invasion and matrix metalloproteinases activities of human fibrosarcoma HT1080 cells.

The effects of tea polyphenols on the invasion of highly metastatic human fibrosarcoma HT1080 cells through a monolayer of human umbilical vein endothelial cells (HUVECs) and the accompanying basal membrane were investigated. Among the tea polyphenols tested, epicatechin gallate (ECg), epigallocatechin gallate (EGCg), and theaflavin strongly suppressed the invasion of HT1080 cells into the monolayer of HUVECs/gelatin membrane, whereas epicatechin, epigallocatechin, tea flavonols, tea flavones, and gallate derivatives had no effect. Both theaflavin-digallate and theasinensin D showed a weak invasion inhibitory effect. ECg significantly inhibited the invasion without cytotoxicity against cancer cells and HUVECs. Ester-type catechins (ECg and EGCg) and theaflavin strongly suppressed the gelatin degradation mediated by matrix metalloproteinase (MMP) 2 and MMP-9, which were secreted into the conditioned medium of HT1080 cells. In conclusion, among the tea polyphenols tested, ECg was considered to be the agent with the most potential antimetastasis activity because it inhibited invasion in the absence of cytotoxicity.

Antioxidants↗
PubMed1999

Increased neutrophil chemotaxis in obstructive jaundice: an in vitro experiment in rats.

BACKGROUND AND AIMS: Changes in neutrophil functions in obstructive jaundice have been poorly understood. An in vitro experimental study was performed to evaluate the effect of obstructive jaundice on the functions of macrophages (secretion of neutrophil chemoattractants) and neutrophils (chemotaxis and superoxide anion generation). METHODS: Obstructive jaundice was produced in rats by 7 day bile duct ligation. Peripheral neutrophils and peritoneal macrophages were harvested from either normal, sham-ligated or bile duct-ligated rats and supernatants of the monolayers of the respective macrophages were prepared after stimulation with lipopolysaccharide. Neutrophil chemotaxis was evaluated with a modified Boyden method. RESULTS: The supernatant of the bile duct-ligated rat macrophages showed a chemotactic effect on normal rat neutrophils with insignificant difference from the supernatant of the sham-ligated rat macrophages. Chemotaxis of the bile duct-ligated rat neutrophils towards the supernatant of the normal rat macrophages was significantly increased, compared with that of sham-ligated rat neutrophils. Similarly, neutrophils from bile duct-ligated rats showed significantly greater chemotaxis to formyl-methionyl-leucyl-phenylalanine than the sham-ligated rat neutrophils. Superoxide anion generation in response to formyl-methionyl-leucyl-phenylalanine or phorbol myristate acetate was significantly increased in the bile duct-ligated rats compared with the sham-ligated rats. CONCLUSIONS: The results suggest that the neutrophil is primed in terms of chemotaxis and superoxide anion generation in obstructive jaundice. How these activated neutrophils play a role in the inflammatory response to obstructive jaundice should be evaluated.

Animals↗
PubMed1999

Magnolol inhibits leukotriene synthesis in rat basophilic leukemia-2H3 cells.

We have observed an inhibitory action of magnolol on the production of leukotriene (LT) C4 and LTB4, important lipid mediators in allergy and inflammation. IgE- and A23187-stimulated production of LTC4 and LTB4 was measured by radio-immunoassay (RIA) in the absence or presence of various concentrations of magnolol in intact rat basophilic leukemia (RBL)-2H3 cells. Magnolol dose-dependently inhibited synthesis of LTC4 and LTB4. Magnolol inhibited the IgE-mediated increase of intracellular calcium ion concentration, resulting in the inhibition of cytosolic phospholipase A2 (cPLA2) and possibly 5-lipoxygenase (5-LO), both calcium ion-dependent enzymes. In cell-free studies magnolol inhibited LTC4 synthase activity. LTA4 hydrolase activity was only inhibited at the higher concentration (2.5 x 10(-5)M). These results indicate that magnolol inhibits production of LTs by inhibiting PLA2, 5-LO, LTC4 synthase and LTA4 hydrolase which are essential for LT-synthesis. Magnolol may have anti-allergic effect by blocking LT-synthesis.

Animals↗
PubMed1999

Recording of mechano-electrical transduction currents by a nystatin perforated-patch method.

Mechano-electrical transduction (MET) currents in isolated cochlear hair cells of chicks were recorded by use of a nystatin perforated-patch method. The membrane of a cell-attached patch was permeabilized by nystatin in the patch pipette, thus providing electrical continuity between the pipette and the cytoplasm of the cell without loss of cytoplasmic compounds. The current-voltage relationship was linear for the inward-going MET current at negative membrane potentials, but outward currents were reduced at positive membrane potentials, evidence of inward-going rectification. Elevation of the intracellular concentration of calcium at positive membrane potential, mediated via a voltage-dependent Ca2+ channel, may suppress the outward-going MET current by acting from within the cell.

Animals↗
PubMed1999

Characterization of a novel missense mutation in the pore of HERG in a patient with long QT syndrome.

INTRODUCTION: A new strategy to elucidate the molecular mechanisms underlying the long QT syndrome (LQTS) is now available with genetic mutational analyses and characterization of ion channel mutations. METHODS AND RESULTS: In a 26-year-old woman with LQTS, we identified a novel missense mutation in the pore of HERG by using polymerase chain reaction/single-strand conformation polymorphism (PCR/SSCP) and sequencing of her genomic DNA. The mutation resulted in an amino acid substitution of a positively charged lysine for a highly conserved uncharged asparagine at codon 629 (N629K). Whole cell, patch clamp studies were conducted in COS7 cells by transfecting with wild-type (WT) and/or the mutant N629K HERG. The WT HERG produced an I(Kr)-like, E-4031-sensitive conductance with an inward rectification. In contrast, the cells transfected with the N629K HERG did not display any time-dependent current. Cotransfection of WT and N629K HERG (at a ratio of 1:1) produced a significantly smaller conductance when compared with WT HERG (WT 59.9 +/- 7.3 pA/pF [n = 22] vs WT+N629K 5.5 +/- 2.3 pA/pF [n = 11]; P < 0.01), but did not alter K+ ion selectivity and tail current-voltage dependence. Because aprindine hydrochloride was effective in preventing ventricular tachycardias, we also tested the effect of the drug on WT HERG (I(Kr)) and KvLQT1/KCNE1 (I(Ks)) currents expressed in COS7. CONCLUSION: Functional analyses of a novel missense mutation in the pore of HERG suggest that the mutation causes marked reduction of I(Kr) via a dominant negative effect.

Adult↗
PubMed1999

Suppression of STAT5 functions in liver, mammary glands, and T cells in cytokine-inducible SH2-containing protein 1 transgenic mice.

Various cytokines utilize Janus kinase (JAK) and the STAT (signal transducers and activators of transcription) family of transcription factors to carry out their biological functions. Among STATs, two highly related proteins, STAT5a and STAT5b, are activated by various cytokines, including prolactin, growth hormone, erythropoietin, interleukin 2 (IL-2), and IL-3. We have cloned a STAT5-dependent immediate-early cytokine-responsive gene, CIS1 (encoding cytokine-inducible SH2-containing protein 1). In this study, we created CIS1 transgenic mice under the control of a beta-actin promoter. The transgenic mice developed normally; however, their body weight was lower than that of the wild-type mice, suggesting a defect in growth hormone signaling. Female transgenic mice failed to lactate after parturition because of a failure in terminal differentiation of the mammary glands, suggesting a defect in prolactin signaling. The IL-2-dependent upregulation of the IL-2 receptor alpha chain and proliferation were partially suppressed in the T cells of transgenic mice. These phenotypes remarkably resembled those found in STAT5a and/or STAT5b knockout mice. Indeed, STAT5 tyrosine phosphorylation was suppressed in mammary glands and the liver. Furthermore, the IL-2-induced activation of STAT5 was markedly inhibited in T cells in transgenic mice, while leukemia inhibitory factor-induced STAT3 phosphorylation was not affected. We also found that the numbers of gamma delta T cells, as well as those of natural killer (NK) cells and NKT cells, were dramatically decreased and that Th1/Th2 differentiation was altered in transgenic mice. These data suggest that CIS1 functions as a specific negative regulator of STAT5 in vivo and plays an important regulatory role in the liver, mammary glands, and T cells.

Animals↗
PubMed1999

Studies of the active substances in herbs used for hair treatment. II. Isolation of hair regrowth substances, acetosyringone and polyporusterone A and B, from Polyporus umbellatus Fries.

Fractionation of the 50% ethanol extract of Polyporus umbellatus Fries by column chromatography on Amberlite XAD-2, silica gel, Sephadex LH-20 and octadecyl silica gel (ODS) (C18)) monitored by a hair-regrowth activity assay, afforded three active principles, 1, 2 and 3. The structures of 1, 2 and 3 were determined as acetosyringone, polyporusterone A, and polyporusterone B by comparison of their spectral data with that of authentic samples, respectively. The effects of several compounds related to acetosyringone, 3,4-dihydroxybenzaldehyde or polyporusterone A on hair regrowth were also investigated.

Animals↗
PubMed1999

New 6-O-acyl isoflavone glycosides from soybeans fermented with Bacillus subtilis (natto). I. 6-O-succinylated isoflavone glycosides and their preventive effects on bone loss in ovariectomized rats fed a calcium-deficient diet.

Three new 6-O-acylated isoflavone glycosides were isolated from soybeans fermented with Bacillus subtilis (natto) and identified as daidzein 7-O-beta-(6''-O-succinyl)-D-glucoside (1), genistein 7-O-beta-(6''-O-succinyl)-D-glucoside (2), and glycitein 7-O-beta-(6''-O-succinyl)-D-glucoside (3) on the basis of spectral data and chemical transformations. During fermentation, the content of the isoflavone glycosides first decreased and then increased, whereas the corresponding 6''-O-succinyl derivatives first accumulated and then decreased, in either soybeans or soybean cooking solution. These changes suggest that enzymatic interconversion of isoflavone glycosides and the corresponding 6''-O-succinylated derivatives occurs in these media during fermentation. The 6-O-succinylated isoflavone glycosides 1, 2 and 3 accounted for 4.8, 7.2 and 0.6%, respectively, of the total isoflavones in commercial fermented soybeans (Japanese natto). Oral administration of 1 or 2 alone for 4 weeks at a dose of 50 mg/kg/d prevented bone loss in ovariectomized (ovx) rats fed a calcium-deficient diet, being as effective as the positive controls, daidzin and genistin, respectively. Compound 1 seems to be proestrogenic, like daidzin, which suppresses bone resorption to prevent bone loss after ovariectomy by directly acting on bone sites, while 2 appears to have a different mechanism of action, like that of genistin.

Animals↗