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Biomedical subjects

M Kitagawa

Publications and source records attributed to M Kitagawa.

At least 127 records · Page 7Linked to original sources
PubMed2000

[Pathological diagnosis--practical treatment of surgical specimens with lung cancer].

The importance of gross examination before histology of the surgically removed lung cancers was stressed by depicting the practical methods of formalin filling fixation, slicing the specimens, drawing and noting the findings, photographing, and cutting the tissue blocks. On gross examination of the sliced specimens it was guided that besides the pathological features of cancers themselves, secondary changes such as bronchiectasis, obstructive pneumonia, hemorrhagic infarction etc, background lesions such as anthracosed scar, honeycombing etc, or apparently independent lesions like centrilobular emphysema should be described, and then not occupying but arising site of cancer should be decided on each case, expressing by the bronchial branching number and generation in central cases and the segment number in peripheral ones.

Histological Techniques↗
PubMed2000

[Rheumatoid arthritis-associated bronchiolitis successfully treated with erythromycin].

A 52-year-old man with a 4-year history of rheumatoid arthritis, and who had an episode of suspected BOOP in early 1994, was admitted to our hospital because of cough and fever. A chest X-ray film on admission showed small patchy infiltrates, and a computed tomographic (CT) scan showed centrilobular nodules and patchy infiltrates with thickened broncho-vascular bundles in both lungs. Transbronchial and thoracoscopic lung biopsies disclosed the coexistence of interstitial pneumonia with BOOP pattern, follicular bronchiolitis, and diffuse panbronchiolitis-like purulent and obliterative bronchiolitis. Due to findings of chronic sinusitis, the patient was treated with erythromycin for 8 weeks, and the abnormal CT shadows regressed. This was an interesting case of various pulmonary lesions associated with rheumatoid arthritis, and successfully treated with erythromycin.

Anti-Bacterial Agents↗
PubMed2000

Effect of a novel anti-inflammatory compound, YM976, on antigen-induced eosinophil infiltration into the lungs in rats, mice, and ferrets.

We evaluated the effects of YM976, a selective inhibitor of phosphodiesterase type 4, on antigen-induced eosinophil infiltration into the lungs in rats, mice, and ferrets. In rats, YM976 inhibited the accumulation of eosinophils at an oral ED(50) value of 1.7 mg/kg, and in C57Black/6 mice, exhibited a dose-dependent inhibition at an ED(50) value of 5.8 mg/kg. In the same dose range in the same mouse model, YM976 suppressed interleukin-5 production. We then compared the inhibitory effect of chronic administration with that of single administration in another rat model of eosinophilia induced by repeated antigen exposure. YM976 administered chronically offered more potent inhibition (ED(50) = 0.32 mg/kg p.o.) than a single dose (1.4 mg/kg p.o.). These results indicated that chronic administration is more effective in antigen-induced eosinophilia than a single administration. Emetogenicity is known to be a major adverse effect of phosphodiesterase type 4 inhibitors. We compared the anti-inflammatory activity of YM976 with its emetic activity in ferrets, in which it dose dependently suppressed eosinophil infiltration at an ED(50) value of 1.2 mg/kg, but induced no emesis at 10 mg/kg. This suggested that the compound exhibits a considerable dissociation between its anti-inflammatory and emetic effects. In summary, YM976 inhibited eosinophil infiltration in a dose-dependent manner in rats, mice, and ferrets. In ferrets, it suppressed antigen-induced eosinophil infiltration without emesis. Additionally, we demonstrated that the inhibitory effect on eosinophil infiltration was increased by chronic administration. In conclusion, YM976 is a promising drug for the treatment of diseases involving eosinophil activity, such as asthma.

Animals↗
PubMed2000

An approach to identify new genes in autoimmune diseases: lessons from rheumatoid arthritis.

We have searched the human genome for genes that predispose to rheumatoid arthritis using fluorescence-based microsatellite marker analysis and affected sib-pair linkage studies. A panel of 41 Japanese families, each with at least two affected siblings, was typed for genome-wide 358 polymorphic microsatellite marker loci. Three principal chromosome regions of linkage, D1S253/214, D8S556 and DX1232, have been assigned, which we call RA1, RA2 and RA3 for rheumatoid arthritis disease loci. We are now assigning the death receptor 3 as a candidate gene for RA1, and the truncated form of Dbl proto-oncogene, which does not contain the 23rd and 24th exons, as disease gene for RA3. Microsatellite marker analyses seem to be promising and new genes are now being identified by reference to sequence tag sites.

Animals↗
PubMed1999

Second transmembrane segment of FtsH plays a role in its proteolytic activity and homo-oligomerization.

The FtsH (HflB) protein of Escherichia coli is a membrane-bound ATP-dependent zinc protease. The role(s) of the N-terminal membrane-anchoring region of FtsH were studied by fusion with a maltose-binding protein (MBP) at five different N-termini of FtsH. The MBP-FtsH fusions were expressed in the cytoplasm of E. coli, and were purified as soluble proteins. The four longer constructs, which have a second transmembrane segment and the C-terminal cytoplasmic region in common, retained ATP-dependent protease activity toward heat-shock transcription factor sigma(32), and were found to be homo-oligomers. In contrast, the shortest construct which has the C-terminal cytoplasmic region but not the second transmembrane segment showed neither protease activity nor oligomerization. Therefore, the second transmembrane segment, which neighbors the C-terminal cytoplasmic region of the FtsH, participates in not only its membrane-anchoring, but also its protease activity and homo-oligomerization.

ATP-Binding Cassette Transporters↗
PubMed1999

Immunological enhancement with a low dose of cyclophosphamide in aged mice.

Aged mice treated with a low dose of cyclophosphamide (CY) showed significantly enhanced immune capacity in cellular proliferation and antibody response. In these mice, total cell numbers were increased both in the thymus and spleen, compared to those in non-treated mice. Treatment with a low dose of CY induced apoptosis of thymocytes in the atrophic thymus of the aged mice, being followed by an increase of proliferation of thymocytes and leading to an increase of thymocytes and splenic T cells. Treatment with a high dose of CY also induced apoptosis in the thymus, but suppressed the proliferative capacity, therefore not leading to an enhancement of immune capacity. In young mice, however, CY suppressed immune capacity regardless of the dose. Thymocytes and splenic T cells of young mice were more susceptible to CY than those of old mice and were decreased in number after the treatment with even a low dose of CY.

Aging↗
PubMed1999

pRb phosphorylation is regulated differentially by cyclin-dependent kinase (Cdk) 2 and Cdk4 in retinoic acid-induced neuronal differentiation of P19 cells.

The retinoblastoma protein (pRb) is a key regulator of cell growth, differentiation and survival. pRb(-/-) mice show abnormal neuronal cell death in the developing brain. The function of pRb is regulated by its phosphorylation state. In this study, the phosphorylation of pRb during retinoic acid (RA)-induced neuronal differentiation of P19 cells was examined using site-specific antibodies against pRb phosphorylated at Ser601, Ser605 and Ser773. Although pRb was hyperphosphorylated in undifferentiated P19 cells, Ser601 and Ser773 were not phosphorylated. Upon exposure to RA, however, these two sites became strongly phosphorylated. Cdk4 kinase activity was almost undetectable in undifferentiated P19 cells, but was strongly activated on exposure to RA. In contrast, Cdk2 kinase activity and the phosphorylation of Ser605 were observed in undifferentiated cells as well as in RA-treated cells. These observations suggest that Cdk2 and Cdk4 may phosphorylate different sites of pRb in vivo and that the two sites of pRb examined here are newly phosphorylated during RA-induced neuronal differentiation in P19 cells.

Amino Acid Sequence↗
PubMed1999

Luminal ATP stimulates fluid and HCO3- secretion in guinea-pig pancreatic duct.

1. The location of purinoceptors in the pancreatic duct and their role in regulating ductal secretion have been investigated by applying ATP and UTP to basolateral and luminal surfaces of pancreatic ducts isolated from the guinea-pig pancreas. 2. Changes in intracellular Ca2+ concentration were measured by microfluorometry in microperfused interlobular duct segments. Fluid and HCO3- secretion were estimated by monitoring luminal pH and luminal volume in sealed duct segments microinjected with BCECF-dextran. 3. Both ATP and UTP (1 microM) caused biphasic increases in intracellular Ca2+ concentration in pancreatic duct cells when applied to either the basolateral or luminal membrane. 4. Luminal application of both ATP and UTP evoked fluid and HCO3- secretion. The maximum response to 1 microM ATP or UTP was about 75 % of that evoked by secretin. By contrast, basolateral application of ATP or UTP inhibited spontaneous secretion by 52 % and 73 %, respectively, and secretin-evoked secretion by 41 % and 38 %, respectively. 5. The data suggest that luminal nucleotides may act in an autocrine or paracrine fashion to enhance ductal secretion while basolateral nucleotides, perhaps released from nerve terminals, may have an inhibitory effect. The fact that both apical and basolateral purinoceptors elevate intracellular Ca2+, but that they have opposite effects on secretion, suggests that additional signalling pathways are involved.

Adenosine Triphosphate↗
PubMed1999

Down-regulation of p27(Kip1) by two mechanisms, ubiquitin-mediated degradation and proteolytic processing.

The intracellular level of p27(Kip1), a cyclin-dependent kinase (CDK) inhibitory protein, is rapidly reduced at the G1/S transition phase when the cell cycle pause ceases. In this study, we demonstrated that two posttranslational mechanisms were involved in p27(Kip1) breakdown: degradation via the ubiquitin (Ub)-proteasome pathway and proteolytic processing that rapidly eliminates the cyclin-binding domain. We confirmed that p27(Kip1) was ubiquitinated in vitro as well as in vivo. The p27(Kip1) -ubiquitination activity was higher at the G1/S boundary than during the G0/G1 phase, and p27(Kip1) ubiquitination was reduced significantly when the lysine residues at positions 134, 153, and 165 were replaced by arginine, suggesting that these lysine residues are the targets for Ub conjugation. In parallel with its Ub-dependent degradation, p27(Kip1) was processed rapidly at its N terminus, reducing its molecular mass from 27 to 22 kDa, by a ubiquitination-independent but adenosine triphosphate (ATP)-dependent mechanism with higher activity during the S than the G0/G1 phase. This 22-kDa intermediate had no cyclin-binding domain at its N terminus and virtually no CDK2 kinase inhibitory activity. These results suggest that p27(Kip1) is eliminated by two independent mechanisms, ubiquitin-mediated degradation and ubiquitin-independent processing, during progression from the G1 to S phase.

3T3 Cells↗
PubMed1999

An F-box protein, FWD1, mediates ubiquitin-dependent proteolysis of beta-catenin.

beta-catenin plays an essential role in the Wingless/Wnt signaling cascade and is a component of the cadherin cell adhesion complex. Deregulation of beta-catenin accumulation as a result of mutations in adenomatous polyposis coli (APC) tumor suppressor protein is believed to initiate colorectal neoplasia. beta-catenin levels are regulated by the ubiquitin-dependent proteolysis system and beta-catenin ubiquitination is preceded by phosphorylation of its N-terminal region by the glycogen synthase kinase-3beta (GSK-3beta)/Axin kinase complex. Here we show that FWD1 (the mouse homologue of Slimb/betaTrCP), an F-box/WD40-repeat protein, specifically formed a multi-molecular complex with beta-catenin, Axin, GSK-3beta and APC. Mutations at the signal-induced phosphorylation site of beta-catenin inhibited its association with FWD1. FWD1 facilitated ubiquitination and promoted degradation of beta-catenin, resulting in reduced cytoplasmic beta-catenin levels. In contrast, a dominant-negative mutant form of FWD1 inhibited the ubiquitination process and stabilized beta-catenin. These results suggest that the Skp1/Cullin/F-box protein FWD1 (SCFFWD1)-ubiquitin ligase complex is involved in beta-catenin ubiquitination and that FWD1 serves as an intracellular receptor for phosphorylated beta-catenin. FWD1 also links the phosphorylation machinery to the ubiquitin-proteasome pathway to ensure prompt and efficient proteolysis of beta-catenin in response to external signals. SCFFWD1 may be critical for tumor development and suppression through regulation of beta-catenin protein stability.

Adenomatous Polyposis Coli Protein↗
PubMed1999

73-kDa heat shock cognate protein interacts directly with P27Kip1, a cyclin-dependent kinase inhibitor, during G1/S transition.

Although heat shock proteins (HSPs) were discovered as inducible proteins by the physical stress to protect cells, recent evidence has suggested that HSPs are likely involved in cell cycle control under normal conditions without stress. In the present study, we demonstrated that 73hsc (heat shock cognate protein), which belongs to the HSP70 family of molecular chaperones, interacts with P27Kip1, an inhibitor of cyclin-dependent kinase, during G1/S transition. 73hsc was detected in the immunoprecipitates with anti-P27Kip1 antibody and, vice versa, P27Kip1 was present in the immunoprecipitates with anti-73hsc antibody by Western blotting using growth-stimulated rat thyroid FRTL-5 cells. This complex formation of 73hsc and P27Kip1 was cell cycle dependent and its maximum formation was observed at G1/S transition where the level of P27Kip1 dramatically decreased. ATP dissociated this complex formation in a dose-dependent manner. These data indicated that 73hsc might be involved in the cell cycle progression through the regulation of cell cycle regulators such as P27Kip1.

Adenosine Diphosphate↗
PubMed1999

Ubiquitin-dependent degradation of IkappaBalpha is mediated by a ubiquitin ligase Skp1/Cul 1/F-box protein FWD1.

Activation of the transcription factor nuclear factor kappa B (NF-kappaB) is controlled by proteolysis of its inhibitory subunit (IkappaB) via the ubiquitin-proteasome pathway. Signal-induced phosphorylation of IkappaBalpha by a large multisubunit complex containing IkappaB kinases is a prerequisite for ubiquitination. Here, we show that FWD1 (a mouse homologue of Slimb/betaTrCP), a member of the F-box/WD40-repeat proteins, is associated specifically with IkappaBalpha only when IkappaBalpha is phosphorylated. The introduction of FWD1 into cells significantly promotes ubiquitination and degradation of IkappaBalpha in concert with IkappaB kinases, resulting in nuclear translocation of NF-kappaB. In addition, FWD1 strikingly evoked the ubiquitination of IkappaBalpha in the in vitro system. In contrast, a dominant-negative form of FWD1 inhibits the ubiquitination, leading to stabilization of IkappaBalpha. These results suggest that the substrate-specific degradation of IkappaBalpha is mediated by a Skp1/Cull 1/F-box protein (SCF) FWD1 ubiquitin-ligase complex and that FWD1 serves as an intracellular receptor for phosphorylated IkappaBalpha. Skp1/Cullin/F-box protein FWD1 might play a critical role in transcriptional regulation of NF-kappaB through control of IkappaB protein stability.

Amino Acid Sequence↗
PubMed1999

Effects of guanylin and uroguanylin on rat jejunal fluid and electrolyte transport: comparison with heat-stable enterotoxin.

The effects of rat guanylin, human guanylin, human uroguanylin and STa on net fluid and electrolyte transport in the closed jejunal loop were compared in anesthetized rats. STa administered into the lumen caused a concentration-dependent (10(-8) to 10(-6) M) inhibition of net fluid and NaCl absorption in the jejunal loop. Uroguanylin had a similar but weaker effect than STa. Both rat and human guanylin inhibited fluid and NaCl absorption only at 10(-6) M. Their order of potency was STa > human uroguanylin > rat guanylin = human guanylin. Changing the luminal pH from 5 to 8 failed to affect the action of guanylin on fluid absorption. Both STa and uroguanylin, but not guanylin, increased the luminal pH by stimulating bicarbonate secretion. Pretreatment of the jejunal loop with guanylin (10(-6) M) 5 min before the instillation of STa (10(-7) M) significantly reduced the inhibitory effect of STa on fluid absorption. It is concluded that guanylin and uroguanylin administered into the rat jejunal lumen have an STa-like action on fluid and electrolyte transport. Guanylin may act as an endogenous antagonist of STa in the rat jejunum and prevent excessive fluid loss by STa.

Animals↗
PubMed1999

Transcriptional regulation of cellular retinol-binding protein, type II gene expression in small intestine by dietary fat.

We have previously demonstrated that dietary fat, especially unsaturated fatty acids, induces cellular retinol-binding protein, type II (CRBPII) gene expression in rat jejunum. In the present study, we showed that feeding a high-fat diet caused parallel increases in jejunal CRBPII mRNA and CRBPII pre-mRNA levels. Nuclear run-on assay also revealed that this increase of CRBPII mRNA level by high-fat diet was, at least in part, triggered at a transcription level. Moreover, peroxisome proliferator-activated receptor alpha (PPARalpha) mRNA level was also increased in the jejunum by high-fat diet. Gel shift assay showed that the binding activity of rat jejunal nuclear protein to the nuclear receptor response elements located in the rat CRBPII gene (RXRE and RE3) was greater in rats fed high-fat diet than in those fed fat-free diet and were enhanced by addition of bacterially expressed PPARalpha protein. Also PPARalpha-retinoid X receptor alpha (RXRalpha) heterodimer was capable of binding to the CRBPII-RXRE and RE3 elements and these binding activities were enhanced by addition of some PPARalpha ligands in the gel shift assay. Taken together, these studies suggest that dietary fatty acids may lead to induction of CRBPII gene transcription through increases of PPARalpha as well as its ligand levels.

Animals↗
PubMed1999

Eicosapentaenoic acid and docosahexaenoic acid inhibit vascular smooth muscle cell proliferation by inhibiting phosphorylation of Cdk2-cyclinE complex.

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the form of triacylglycerol (TG) were dose dependently incorporated into phospholipid fraction of vascular smooth muscle cells (VSMC) and suppressed the proliferation of VSMC. Flow cytometric analysis demonstrated both EPA and DHA inhibited G1/S progression. EPA and DHA inhibited the phosphorylation of Cdk2 protein and Cdk2 kinase activity without altering the amount of cyclin E and p27(kip1) proteins and cyclin dependent kinase activating kinase activity by growth stimulation. This mechanisms remained to be clarified but this is the first report of a novel mechanisms of inhibition of DNA synthesis by EPA and DHA.

Animals↗
PubMed1999

Amniotic fluid alpha-fetoprotein testing in native Japanese women.

Owing to differences in maternal serum alpha-fetoprotein, human chorionic gonadotrophin and oestriol levels between native Japanese and Caucasian women screened in this laboratory, a study was conducted to measure amniotic fluid alpha-fetoprotein (AFAFP) levels in native Japanese pregnancies. When the native Japanese AFAFP levels were compared with a United States (non-Black) population, the Japanese medians did not decrease as rapidly over the 14 to 22 weeks of gestation period investigated. At 14 weeks, the difference was negligible, graduating to a difference of 20 per cent by 22 weeks' gestation. Native Japanese pregnancy AFAFP levels should be interpreted based upon population data from that group alone. From these findings, prenatal screening laboratories should be encouraged to collect preliminary data for comparison before screening is initiated for a defined ethnic group.

Amniocentesis↗
PubMed1999

Differential regulation of rheumatoid synovial cell interleukin-12 production by tumor necrosis factor alpha and CD40 signals.

OBJECTIVE: To investigate the roles of tumor necrosis factor alpha(TNFalpha) and the CD40-CD154 interaction in interleukin-12 (IL-12) production by rheumatoid synovial cells (SC). METHODS: Levels of IL-12 (p40 and p70) in synovial tissue and culture supernatants of SC from patients with rheumatoid arthritis (RA), osteoarthritis (OA), and ankylosing spondylitis (AS) were assayed by enzyme-linked immunosorbent assay. Effects of anti-CD154 and anti-TNFalpha antibody on spontaneous and lipopolysaccharide (LPS)-stimulated IL-12 production by SC were examined. Effects of immobilized anti-CD3 treatment and depletion of CD4+ T cells on IL-12 production were also tested. CD154 expression by synovial T cells and intracellular IL-12 production during culture were analyzed by flow cytometry. RESULTS: IL-12 p40 and p70 levels in RA synovial tissue and spontaneous IL-12 p40 production by SC from RA patients were significantly higher than the levels in OA and AS patients. Spontaneous IL-12 production by SC from RA patients significantly decreased after depletion of CD4+ T cells from SC or after application of anti-CD154 antibody, but not by treatment with anti-TNFalpha antibody. Anti-CD3 antibody stimulation increased spontaneous IL-12 p40 production and CD154 expression by synovial T cells. The increment of IL-12 p40 production by anti-CD3 was abrogated by anti-CD154 antibody. IL-12 p40 production was also increased by LPS stimulation. LPS-stimulated IL-12 production was inhibited by anti-TNFalpha antibody, but not by T cell depletion and anti-CD154 antibody treatment. The TNFalpha inhibitor rolipram inhibited LPS-stimulated IL-12 p40 production by RA SC more strongly than spontaneous production. TNFalpha restored LPS-stimulated IL-12 production that had been inhibited by rolipram. CONCLUSION: IL-12 production in RA is regulated by 2 different pathways. One pathway is T cell dependent, predominantly through a CD40-CD154 interaction, while the other is T cell independent, mediated through TNFalpha. Inhibition of IL-12 production by interference with CD40-CD154 interaction and TNFalpha production may be a potential therapeutic strategy for treating RA.

Adjuvants, Immunologic↗