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H Ueno

Publications and source records attributed to H Ueno.

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

Intracellular signaling of angiotensin II-induced p70 S6 kinase phosphorylation at Ser(411) in vascular smooth muscle cells. Possible requirement of epidermal growth factor receptor, Ras, extracellular signal-regulated kinase, and Akt.

Activation of p70 S6 kinase (p70(S6K)) by growth factors requires multiple signal inputs involving phosphoinositide 3-kinase (PI3K), its effector Akt, and an unidentified kinase that phosphorylates Ser/Thr residues (Ser(411), Ser(418), Ser(424), and Thr(421)) clustered at its autoinhibitory domain. However, the mechanism by which G protein-coupled receptors activate p70(S6K) remains largely uncertain. By using vascular smooth muscle cells in which we have demonstrated Ras/extracellular signal-regulated kinase (ERK) activation through Ca(2+)-dependent, epidermal growth factor (EGF) receptor transactivation by G(q)-coupled angiotensin II (Ang II) receptor, we present a unique cross-talk required for Ser(411) phosphorylation of p70(S6K) by Ang II. Both p70(S6K) Ser(411) and Akt Ser(473) phosphorylation by Ang II appear to involve EGF receptor transactivation and were inhibited by dominant-negative Ras, whereas the phosphorylation of p70(S6K) and ERK but not Akt was sensitive to the MEK inhibitor. By contrast, the phosphorylation of p70(S6K) and Akt but not ERK was sensitive to PI3K inhibitors. Similar inhibitory pattern on these phosphorylation sites by EGF but not insulin was observed. Taken together with the inhibition of Ang II-induced p70(S6K) activation by dominant-negative Ras and the MEK inhibitor, we conclude that Ang II-initiated activation of p70(S6K) requires both ERK cascade and PI3K/Akt cascade that bifurcate at the point of EGF receptor-dependent Ras activation.

Angiotensin II↗
PubMed1999

Defects in transforming growth factor-beta signaling cooperate with a Ras oncogene to cause rapid aneuploidy and malignant transformation of mouse keratinocytes.

Genetic inactivation of the transforming growth factor-beta (TGF-beta) signaling pathway can accelerate tumor progression in the mouse epidermal model of multistage carcinogenesis. By using an in vitro model of keratinocyte transformation that parallels in vivo malignant conversion to squamous cell carcinoma, we show that v-ras(Ha) transduced primary TGF-beta1-/- keratinocytes and keratinocytes expressing a TGF-beta type II dominant-negative receptor transgene have significantly higher frequencies of spontaneous transformation than control genotypes. Malignant transformation in the TGF-beta1-/- keratinocytes is preceded by aneuploidy and accumulation of chromosomal aberrations. Similarly, transient inactivation of TGF-beta signaling with a type II dominant-negative receptor adenovirus causes rapid changes in ploidy. Exogenous TGF-beta1 can suppress aneuploidy, chromosome breaks, and malignant transformation of the TGF-beta1-/- keratinocytes at concentrations that do not significantly arrest cell proliferation. These results point to genomic instability as a mechanism by which defects in TGF-beta signaling could accelerate tumor progression in mouse multistage carcinogenesis.

Aneuploidy↗
PubMed1999

Temperature-sensitive ZAP70 mutants degrading through a proteasome-independent pathway. Restoration of a kinase domain mutant by Cdc37.

CD8 deficiency is an autosomal recessive form of severe combined immunodeficiency diseases characterized by the absence of CD8(+) T lymphocytes and impaired T cell functions. We identified two novel mis-sense mutations in the zap70 genes of a CD8-deficiency patient. One mutation (P80Q) affects a residue in an SH2 domain and another (M572L) in the kinase subdomain XI. Both mutations cause a degradation of ZAP70 protein in a temperature-sensitive manner through an ATP-dependent and proteasome-independent pathway. We further demonstrated that Cdc37, a protein kinase-specific chaperone, bound to M572L but not P80Q mutant and restored the expression of the M572L mutant when overexpressed. The restoration of M572L mutant by Cdc37 required the function of HSP90. These results indicate that Cdc37 in conjunction with HSP90 functions as a molecular chaperone for a temperature-sensitive kinase domain mutant of ZAP70.

Adenosine Triphosphate↗
PubMed1999

Enhanced production and activation of matrix metalloproteinase-7 (matrilysin) in human endometrial carcinomas.

We examined production and tissue localization of 7 different matrix metalloproteinases (MMP-1, -2, -3, -7, -8, -9 and -13) and 2 tissue inhibitors of metalloproteinases (TIMP-1 and -2) in human endometrial-carcinoma tissues. Sandwich enzyme immunoassays showed enhanced production of MMP-7, MMP-8 and MMP-9 as well as TIMP-1 in the carcinoma tissues compared with non-carcinoma endometrial tissues. Among these MMPs, only the amount of MMP-7 correlated with clinicopathological factors of the carcinomas. The level was significantly 6.8-fold higher in the patient group with lymph-node metastases than in that without metastases (p < 0.05), and also increased with the progress of the clinical stage. MMP-7 was immunolocalized predominantly to the carcinoma cells in 73% of the cases, while MMP-8 and MMP-9 were immunostained in the inflammatory cells infiltrated in the carcinoma tissues. Immunoblotting revealed a definite band for the zymogen of MMP-7 (proMMP-7) of 28 kDa in 82% of the carcinoma samples, while only a faint band for proMMP-7 was seen in 57% of the non-carcinoma endometrial samples. Active MMP-7 species of 19 kDa and its activity were demonstrated in the carcinoma samples with proMMP-7 production by immunoblotting and zymography, respectively. RT-PCR using a specific primer pair for MMP-7 demonstrated expression in 86% of the carcinoma tissue and in 57% of the control tissue samples. In situ hybridization showed carcinoma cells selectively expressing MMP-7 mRNA. These data suggest that, among the 7 MMPs examined, MMP-7 may play a key role in invasion and lymph-node metastasis of human endometrial carcinomas.

Adult↗
PubMed1999

Hypomethylation of the proximal and intronic regulatory regions of the IFN-gamma gene is not essential for its transcription by naive CD4+ T cells cultured with IL-4.

Recently, long-term preculture with IL-4 or IL-7 has been reported to induce IFN-gamma-producing ability in naive CD4+ T cells without stimulation via TCR. The mechanism of IFN-gamma-transcription in naive CD4+ T cells precultured with IL-4 was analyzed and compared with that in typical Th1 cells by focusing on the TATA proximal and first intronic regulatory regions of the IFN-gamma gene. Both regulatory regions in these IL-4-primed naive CD4+ T cells, which produce a large amount of IFN-gamma upon stimulation with PMA and ionomycin, were completely methylated in contrast to the same hypomethylated regions in Th1 cells. DNase I hypersensitive site analysis suggested that both regulatory regions in IL-4-primed naive CD4+ T cells were not active for IFN-gamma-expression. Moreover, we demonstrated that the composition of transcriptional factors that can bind to the proximal regulatory region is different between IL-4-primed naive CD4+ T cells and Th1 cells. These results indicated that the transcriptional machinery involved in the expression of the IFN-gamma gene by CD4+ T cells varied depending on their modes of differentiation in both the responsive regulatory regions and the specific nuclear factors.

CD4-Positive T-Lymphocytes↗
PubMed1999

Gene 61.3 of bacteriophage T4 is the spackle gene.

The bacteriophage T4 e gene encodes lysozyme (e-lysozyme), which releases progeny phage after normal infection of Escherichia coli cells. A mutation in the spackle gene suppresses the defect in e-lysozyme (Emrich, 1968). The spackle gene was mapped between genes 41 and 61, but its precise location has not previously been determined. In the current study, we constructed an amber mutant of gene 61.3, amST14, by site-directed mutagenesis. The gene 61.3 mutant shares phenotypes with spackle mutants: The amST14 mutant forms large plaques with sharp edges and exhibits truncated lysis inhibition, and furthermore, the mutation can suppress the defect in e-lysozyme activity. In addition, cloned gene 61.3 can rescue (by homologous recombination) as well as complement the S12 mutation in the spackle gene. These results strongly suggest that gene 61.3 is the spackle gene. Indeed, the S12 mutant has one base deletion of five in a consecutive A tract in the gene 61.3 coding region, substituting an unrelated 6-amino acid sequence for the 9 C-terminal amino acids in the gene 61.3 protein. The gene 61.3 protein is predicted to localize in the periplasmic space after cleavage of a signal sequence.

Amino Acid Sequence↗
PubMed1999

Dominant negative forms of Akt (protein kinase B) and atypical protein kinase Clambda do not prevent insulin inhibition of phosphoenolpyruvate carboxykinase gene transcription.

Transcriptional regulation of phosphoenolpyruvate carboxykinase (PEPCK), the rate-limiting enzyme in hepatic gluconeogenesis, by insulin was investigated with the use of adenovirus vectors encoding various mutant signaling proteins. Insulin inhibited transcription induced by dexamethasone and cAMP of a chloramphenicol acetyltransferase (CAT) reporter gene fused with the PEPCK promoter sequence in HL1C cells stably transfected with this construct. A dominant negative mutant of phosphoinositide (PI) 3-kinase blocked insulin inhibition of transcription of the PEPCK-CAT fusion gene, whereas a constitutively active mutant of PI 3-kinase mimicked the effect of insulin. Although a constitutively active mutant of Akt (protein kinase B) inhibited PEPCK-CAT gene transcription induced by dexamethasone and cAMP, a mutant Akt (Akt-AA) in which the phosphorylation sites targeted by insulin are replaced by alanine did not affect the ability of insulin to inhibit transcription of the fusion gene. Akt-AA almost completely inhibited insulin-induced activation of both endogenous and recombinant Akt in HL1C cells. Furthermore, neither a kinase-defective mutant protein kinase Clambda (PKClambda), which blocked insulin-induced activation of endogenous PKClambda, nor a dominant negative mutant of the small GTPase Rac prevented inhibition of PEPCK-CAT gene transcription by insulin. These data suggest that phosphoinositide 3-kinase is important for insulin-induced inhibition of PEPCK gene transcription and that a downstream effector of phosphoinositide 3-kinase distinct from Akt, PKClambda, and Rac may exist for mediating the effect of insulin.

Cell Line↗
PubMed1999

Heart-specific activation of LTK results in cardiac hypertrophy, cardiomyocyte degeneration and gene reprogramming in transgenic mice.

Leukocyte tyrosine kinase (LTK) is a receptor-type protein tyrosine kinase belonging to the insulin receptor superfamily. To elucidate its biological role, we generated transgenic mice expressing LTK under the control of cytomegarovirus enhancer and beta-actin promoter. The transgenic mice exhibited growth retardation and most of the transgenic mice died within several months after birth. Interestingly, although LTK was expressed in several major organs, the activation (tyrosine-phosphorylation, kinase activity, and multimerization) of LTK was observed selectively in the heart, where LTK was localized on intracellular membrane, presumably on endoplasmic reticulum. Echocardiography showed that the transgenic heart underwent severe concentric hypertrophy, which resulted in reduced cardiac output, low blood pressure, and increased heart rate. Histological examination of the heart exhibited focal degeneration of cardiomyocytes. These histological changes were considered to be due to apoptosis, based on the finding that the sarcolemmas of the degenerative cardiomyocytes were well preserved. In addition, expression of fetal genes, such as atrial natriuretic peptide and skeletal alpha-actin, was markedly induced in the transgenic heart. These results indicate that a certain tissue-specific mechanism of activating LTK exists in the heart and that the activated LTK resulted in cardiac hypertrophy, cardiomyocyte degeneration and gene reprogramming. These findings will provide novel insights into the activating mechanism and biological role of LTK in vivo.

Animals↗
PubMed1999

Adenovirus-mediated local expression of human tissue factor pathway inhibitor eliminates shear stress-induced recurrent thrombosis in the injured carotid artery of the rabbit.

The main cause of acute coronary syndrome may be recurrent thrombosis, which is initiated by the activation of the extrinsic coagulation pathway. Tissue factor (TF) pathway inhibitor (TFPI) efficiently inhibits an early step in this pathway by the formation of a complex with factor VIIa, TF, and factor Xa. We determined whether local TFPI gene transfer can inhibit thrombosis in an injured artery without inducing systemic side effects. Balloon-injured rabbit carotid arteries were infected with an adenoviral vector that expressed either human TFPI (AdCATFPI) or bacterial beta-galactosidase (AdCALacZ). Two to 6 days after gene transfer, thrombosis was induced by the production of constant stenosis of the artery, and blood flow was measured continuously with an electromagnetic flow probe. A cyclic flow variation, which is thought to reflect the recurrent formation and dislodgment of mural thrombi, was observed in all AdCALacZ-infected arteries as well as in saline-infused arteries. In contrast, no cyclic flow variation was detectable in AdCATFPI-transfected arteries, even in the presence of epinephrine (1 microg. kg-1. min-1 infusion). Prothrombin time, activated partial thromboplastin time, and the ex vivo platelet aggregation induced by either adenosine diphosphate or collagen were unaltered in AdCATFPI-infected rabbits. We found that in vivo TFPI gene transfer into an injured artery completely inhibits the recurrent thrombosis induced by shear stress even in the presence of catecholamine, without affecting systemic coagulation status. Adenovirus-mediated local expression of TFPI may have the potential for the treatment of human thrombosis.

Adenoviridae↗
PubMed1999

Platelet-derived growth factor activates p38 mitogen-activated protein kinase through a Ras-dependent pathway that is important for actin reorganization and cell migration.

Members of the mitogen activated protein (MAP) kinase family, extracellular signal-regulated kinase, stress-activated protein kinase-1/c-Jun NH2-terminal kinase, and p38, are central elements that transduce the signal generated by growth factors, cytokines, and stressing agents. It is well known that the platelet-derived growth factor (PDGF) activates extracellular signal-regulated kinase, which leads to cellular mitogenic response. On the other hand, the role of the other MAP kinases in mediating the cellular function of PDGF remains unclear. In the present study, we have investigated the functional role of the other MAP kinases in PDGF-mediated cellular responses. We show that ligand stimulation of PDGF receptors leads to the activation of p38 but not stress-activated protein kinase-1/c-Jun NH2-terminal kinase. Experiments using a specific inhibitor of p38, SB203580, show that the activation of p38 is required for PDGF-induced cell motility responses such as cell migration and actin reorganization but not required for PDGF-stimulated DNA synthesis. Analyses of tyrosine residue-mutated PDGF receptors show that Src homology 2 domain-containing proteins including Src family kinases, phosphatidylinositol 3-kinase, the GTPase-activating protein of Ras, the Src homology 2 domain-containing phosphatase SHP-2, phospholipase C-gamma, and Crk do not play a major role in mediating the PDGF-induced activation of p38. Finally, the expression of dominant-negative Ras but not dominant-negative Rac inhibited p38 activation by PDGF, suggesting that Ras is a potent mediator in the p38 activation pathway downstream of PDGF receptors. Taken together, our present study proposes the existence of a Ras-dependent pathway for the activation of p38, which is important for cell motility responses elicited by PDGF stimulation.

Actins↗
PubMed1999

VEGF activates protein kinase C-dependent, but Ras-independent Raf-MEK-MAP kinase pathway for DNA synthesis in primary endothelial cells.

KDR/FIk-1 tyrosine kinase, one of the two VEGF receptors induces mitogenesis and differentiation of vascular endothelial cells. We have previously reported that a major target molecule of KDR/Flk-1 kinase is PLC-gamma, and that VEGF induces activation of MAP kinase, mainly mediated by protein kinase C (PKC) in the NIH3T3 cells overexpressing KDR/FIk-1 (Takahashi and Shibuya, 1997). However, the signal transduction initiated from VEGF in endothelial cells remains to be elucidated. In primary sinusoidal endothelial cells which showed strictly VEGF-dependent growth, we found that VEGF stimulated the activation of Raf-1-MEK-MAP kinase cascade. To our surprise, an important regulator, Ras was not efficiently activated to a significant level in response to VEGF. Consistent with this, dominant-negative Ras did not block the VEGF-induced phosphorylation of MAP kinase. On the other hand, PKC-specific inhibitors severely reduced VEGF-dependent phosphorylation of MEK, activation of MAP kinase and subsequent DNA synthesis. A potent PI3 kinase inhibitor, Wortmannin, could not inhibit either of them. These results suggest that in primary endothelial cells, VEGF-induced activation of Raf-MEK-MAP kinase and DNA synthesis are mainly mediated by PKC-dependent pathway, much more than by Ras-dependent or PI3 kinase-dependent pathway.

3T3 Cells↗
PubMed1999

1,25-Dihydroxyvitamin D3 induces differentiation of a retinoic acid-resistant acute promyelocytic leukemia cell line (UF-1) associated with expression of p21(WAF1/CIP1) and p27(KIP1).

Retinoic acid (RA) resistance is a serious problem for patients with acute promyelocytic leukemia (APL) who are receiving all-trans RA. However, the mechanisms and strategies to overcome RA resistance by APL cells are still unclear. The biologic effects of RA are mediated by two distinct families of transcriptional factors: RA receptors (RARs) and retinoid X receptors (RXRs). RXRs heterodimerize with 1, 25-dihydroxyvitamin D3 [1,25(OH)2D3] receptor (VDR), enabling their efficient transcriptional activation. The cyclin-dependent kinase (cdk) inhibitor p21(WAF1/CIP1) has a vitamin D3-responsive element (VDRE) in its promoter, and 1,25(OH)2D3 enhances the expression of p21(WAF1/CIP1) and induces differentiation of selected myeloid leukemic cell lines. We have recently established a novel APL cell line (UF-1) with features of RA resistance. 1,25(OH)2D3 can induce growth inhibition and G1 arrest of UF-1 cells, resulting in differentiation of these cells toward granulocytes. This 1, 25(OH)2D3-induced G1 arrest is enhanced by all-trans RA. Also, 1, 25(OH)2D3 (10(-10) to 10(-7) mol/L) in combination with RA markedly inhibits cellular proliferation in a dose- and time-dependent manner. Associated with these findings, the levels of p21(WAF1/CIP1) and p27(KIP1) mRNA and protein increased in these cells. Northern blot analysis showed that p21(WAF1/CIP1) and p27(KIP1) mRNA and protein increased in these cells. Northern blot analysis showed that p21(WAF1/CIP1) and p27(KIP1) transcripts were induced after 6 hours' exposure to 1,25(OH)2D3 and then decreased to basal levels over 48 hours. Western blot experiments showed that p21(WAF1/CIP1) protein levels increased and became detectable after 12 hours of 1,25(OH)2D3 treatment and induction of p27(KIP1) protein was much more gradual and sustained in UF-1 cells. Interestingly, the combination of 1, 25(OH)2D3 and RA markedly enhanced the levels of p27(KIP1) transcript and protein as compared with levels induced by 1, 25(OH)2D3 alone. In addition, exogenous p27(KIP1) expression can enhance the level of CD11b antigen in myeloid leukemic cells. In contrast, RA alone can induce G1 arrest of UF-1 cells; however, it did not result in an increase of p21(WAF1/CIP1) and p27(KIP1) transcript and protein expression in RA-resistant cells. Taken together, we conclude that 1,25(OH)2D3 induces increased expression of cdk inhibitors, which mediates a G1 arrest, and this may be associated with differentiation of RA-resistant UF-1 cells toward mature granulocytes.

Calcitriol↗
PubMed1999

Blockade of type beta transforming growth factor signaling prevents liver fibrosis and dysfunction in the rat.

We eliminated type beta transforming growth factor (TGF-beta) signaling by adenovirus-mediated local expression of a dominant-negative type II TGF-beta receptor (AdCATbeta-TR) in the liver of rats treated with dimethylnitrosamine, a model of persistent liver fibrosis. In rats that received a single application of AdCATbeta-TR via the portal vein, liver fibrosis as assessed by histology and hydroxyproline content was markedly attenuated. All AdCATbeta-TR-treated rats remained alive, and their serum levels of hyaluronic acid and transaminases remained at low levels, whereas all the AdCATbeta-TR-untreated rats died of liver dysfunction. The results demonstrate that TGF-beta does play a central role in liver fibrogenesis and indicate clearly in a persistent fibrosis model that prevention of fibrosis by anti-TGF-beta intervention could be therapeutically useful.

Adenoviridae↗
PubMed1999

Enhanced production and activation of progelatinase A mediated by membrane-type 1 matrix metalloproteinase in human papillary thyroid carcinomas.

Matrix metalloproteinases (MMPs) are believed to be involved in the invasion and metastasis of various human carcinomas. In the present study, the production levels of seven different MMPs (MMP-1, -2, -3, -7, -8, -9, and -13), the activation of the zymogen of MMP-2 (proMMP-2), the expression of membrane-type MMPs (MT1-, MT2-, and MT3-MMPs), and the tissue localization of the activated enzyme were examined in human invasive papillary thyroid carcinomas. Sandwich enzyme immunoassays revealed that among the MMPs examined, only the MMP-2 production level is significantly enhanced in the carcinoma tissues compared with the follicular adenoma and normal control thyroid tissues. Gelatin zymography indicated that the proMMP-2 activation ratio is considerably higher in carcinomas with lymph node metastasis than it is in those without metastasis, follicular adenomas, or normal controls (P < 0.01). Northern blot analysis of the expression of MT1-, MT2-, and MT3-MMPs, which are known to activate proMMP-2 in vitro, demonstrated the predominant expression of MT1-MMP mRNA in the carcinoma tissues (15 of 15 cases), whereas MT2-MMP expression was confined to 26% of the cases (4 of 15 cases), and no consistent expression of MT3-MMP was observed. MTI-MMP mRNA expression levels correlated with the proMMP-2 activation ratio (r = 0.692; P < 0.01), but such a correlation was not obtained with MT2-MMP. There was also a direct correlation between MT1-MMP expression and lymph node metastasis (P < 0.05). In situ hybridization indicated that both carcinoma and stromal cells express MT1-MMP transcripts (five of six cases). MT1-MMP was also immunolocalized to carcinoma and stromal cells in all of the carcinoma samples (26 of 26 cases), which were positive for MMP-2. In situ zymography indicated definite gelatinolytic activity in the carcinoma cell nests, which was abolished by incubation of the carcinoma samples with a synthetic MMP inhibitor before the reaction. These results suggest for the first time that among seven different MMPs, the production of proMMP-2 and its MT1-MMP-mediated activation in the carcinoma cell nests play an important role in the lymph node metastasis of human invasive papillary thyroid carcinomas.

Adult↗
PubMed1999

Inhibitory effects of FK506 on the development of experimental allergic/immune-mediated blepharoconjunctivitis in Lewis rats by systemic but not by topical administration.

BACKGROUND: FK506 has been used for treatment of cell-mediated immune disorders such as graft rejection in transplantation or Behçet disease. To evaluate the effectiveness of FK506 in another ocular disease model, we injected FK506 in rats with experimental allergic/immune-mediated blepharo conjunctivitis (EAC) the induction mechanism of which depends on cell-mediated immunity. METHODS: Lewis rats were immunized with ovalbumin (OVA) in emulsion of complete Freund's adjuvant (CFA). We injected 2 (n = 6), 20 (n = 6) or 200 (n = 5) microg of FK506 intramuscularly daily from the day of immunization (day 0) to day 6. Control rats were not treated with FK506 (n = 4). In addition, we injected 200 microg of FK506 from day 7 to day 13 (n = 12) to compare the timing of FK506 administration (day 0 to day 6, n = 12; control, n = 12). Twenty-one days after immunization, all rats were challenged with OVA by eye drops, and 24 h later they were killed after clinical evaluation and their eyes, blood and draining lymph nodes were harvested for histology, antibody titers and proliferation assay or flow cytometric analysis. In another set of experiments, rats that had received OVA-primed lymph node cells did (n = 9) or did not (n = 9) receive additional FK506 by injection daily for 4 days. Four days after transfer, these rats were challenged with OVA and evaluated as mentioned. To investigate possible suppression of disease by topical administration of FK506, both actively immunized and passively immunized rats received OVA together with 0.3% (weight/volume) of FK506 (n = 16) or vehicle (n = 10) by eye drops and 24 h after challenge, rats were evaluated as mentioned. RESULTS: Development of disease, induced by either active or passive immunization, was inhibited in the group treated with 200 microg of FK506, regardless of timing of administration. Cellular proliferative responses to OVA were inhibited only in this group. Flow cytometry demonstrated a decrease of about 20% in the proportion of all cells made up by CD4-positive T cells. Topical administration of FK506 inhibited the development of EAC, though not significantly. CONCLUSIONS: Systemic treatment with 200 microg of FK506 either in the induction or the effector phase inhibits the development of EAC in Lewis rats. Topical administration is not so effective as systemic administration.

Adoptive Transfer↗
PubMed1999

Accelerating effects of chitosan for healing at early phase of experimental open wound in dogs.

Chitosan is a polymeric beta(1 --> 4) glucosamine (2-amino-2-deoxy-D-glucose) and N-acetyl-D-glucosamine (2-acetamido-2-deoxy-D-glucose) which has been reported as a wound healing accelerator. In order to evaluate the efficacy of chitosan as an accelerator of wound healing, experimental open skin wounds were made on the dorsal side in three normal beagles. Cottonfiber-type chitosan (degree of acetylation = 18%) was applied for 15 days, and the process of wound healing was evaluated histologically and immunohistochemically. On day 3 postwounding, the chitosan-treated wounds showed histologically severe infiltration of polymorphonuclear (PMN) cells and an increase in effusion compared with that in the control. Granulation was more pronounced by the chitosan treatment on day 9 and 15 postwounding. Immunohistochemical typing of collagen I, III and IV showed increase of the production of type III collagen in the chitosan group. The appearance of mitotic cells occurred numerously in the control on postwounding day 3, and in the chitosan group on postwounding day 6. These results suggest chitosan to be having a function in the acceleration of infiltration of PMN cells at the early stage of wound healing, followed by the production of collagen by fibroblasts.

Animals↗
PubMed1999

Further characterization of memory T cells existing in a case of CD8 deficiency.

CD8 deficiency is a rare primary immunodeficiency caused by a defect of ZAP-70, which plays a pivotal role in T cell activation. We previously reported the existence of memory phenotype-CD4+ T cells in a case of CD8 deficiency, which demonstrates that activation signals through ZAP-70 are not essential to the phenotypic conversion of T cells from "naive" to "memory." In this study, we further characterized CD45RO+ T cells in a CD8 deficient patient. We showed that the patient's CD45RO+ T cell population had a wide variety of T cell receptor Vbeta-chain gene usage, and contained few clonally expanded T cells, while many clonally expanded T cells were present in the memory T cell population of age-matched healthy children. These results suggest that various kinds of antigens were involved in the differentiation of the patient's T cells, and that the differentiation into memory T cells was not accompanied by profound T cell proliferation. Moreover, our findings confirmed that the patient's CD45RO+CD4+ T cells had acquired effector-cytokine producing ability, indicating that there exists an alternative activation pathway which is independent of ZAP-70 for the acquisition of effector-cytokine producing ability.

CD8 Antigens↗