Biomedical subjects

E S Oh

Publications and source records attributed to E S Oh.

16 recordsLinked to original sources

PubMed2004

Relationship between circulating cytokine levels and thyroid function following bone marrow transplantation.

The relation between thyroid hormone changes and cytokines in bone marrow transplantation (BMT) patients has not been studied. This prospective study was designed to determine the relation between thyroid hormones and cytokine levels after BMT and their effects on the mortality. We studied 80 patients undergoing allogeneic BMT. Serum thyroid hormone parameters and cytokine levels were measured before and serially during 6 months after BMT. Serum T(3) decreased to a nadir 3 weeks post-BMT and serum T(4) was lowest at 3 months post-BMT. Serum thyroid stimulating hormone (TSH) sharply decreased to a nadir at 1 week and recovered. Serum interleukin-6 increased for 2 weeks after BMT and declined thereafter. Serum tumor necrosis factor-alpha increased for 3 weeks after BMT and declined thereafter. After 3 weeks post-BMT, both cytokine levels were negatively correlated with serum T(3) and T(4) levels. A total of 29 patients died before 1 year post-BMT and 51 patients survived longer than 1 year. Those patients who died before 1 year post-BMT had significantly lower levels of T(4) at 3 weeks, 3 and 6 months than surviving patients. In conclusion, increased levels of serum IL-6 and TNF-alpha were negatively correlated with thyroid hormone concentrations in BMT recipients suggesting the role of these cytokines in euthyroid sick syndrome.

Adult↗

PubMed2002

The role of cytokines in the changes in bone turnover following bone marrow transplantation.

Osteoporosis is a common disease among patients undergoing transplantation and a loss of bone mass is usually detected after bone marrow transplantation (BMT), particularly during the immediate post-BMT period. Post-BMT bone loss is primarily related to gonadal dysfunction and immunosuppression. Cytokines, especially interleukin 6, play an important role in the pathogenesis of postmenopausal osteoporosis. However, the pathogenetic role of cytokines in post-BMT bone loss is unknown and data on the changes of cytokines in accordance with bone turnover markers are scarce. The aim of this study was to assess the relationship between bone turnover markers and cytokines, which are regularly sampled at peripheral blood and bone marrow before and after allogeneic BMT. This prospective study included two analyses. The first was a study of 46 BMT recipients (M/F 28/18), examining the relationship between bone turnover markers and serum cytokines that were measured before and at 1 week, 2 weeks, 3 weeks, 4 weeks and 3 months after BMT. Serum intact parathyroid hormone was measured before BMT and at 3 weeks after BMT and its relation to other cytokines and bone turnover markers was evaluated. The second analysis was a study of 14 (M/F 9/5) of 46 patients in whom bone marrow plasma cytokines [interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-alpha)] were measured at 3 weeks after BMT. The relationship between bone marrow plasma cytokines and bone turnover markers was studied because bone marrow is the microenvironment where the real changes in bone turnover occur. Serum type I collagen carboxyterminal telopeptide (ICTP), a bone resorption marker, increased progressively until 4 weeks (peak) after BMT and then decreased thereafter. Serum osteocalcin, a bone formation marker, decreased progressively until 3 weeks after BMT and then increased thereafter. Serum IL-6 increased until 2 weeks after BMT and declined thereafter. Serum TNF-alpha increased until 3 weeks after BMT and declined thereafter. There was a significant positive correlation between serum ICTP and bone marrow IL-6 levels at 3 weeks after BMT, when a marked change in bone metabolism occurs following BMT. However, a correlation between bone turnover markers and bone marrow TNF-alpha or peripheral blood cytokines was not found. At 3 months after BMT, there was a significant negative correlation between the mean daily steroid dose and the serum osteocalcin level (r = -0.43, p < 0.05). The correlation between the Mean daily steroid dose and serum ICTP was also significant (r = 0.41, p < 0.05). Our data suggest that the progressive increase in bone resorption during the immediate post-BMT period is related to both steroid dose and the increase in bone marrow IL-6, which is a potent stimulator of bone resorption in vivo.

Adult↗

PubMed2001

C-terminal heparin-binding domain of fibronectin regulates integrin-mediated cell spreading but not the activation of mitogen-activated protein kinase.

Fibronectin (FN) stimulates multiple signalling events including mitogen-activated protein kinase (MAPK) activation. During cell spreading, both the cell-binding domain and the C-terminal heparin-binding domain (HepII) of FN co-operatively regulate cytoskeleton organization. However, in comparison with the large number of studies on the functions of cell-binding domain, there is little information about the role of HepII. We therefore investigated the effect of HepII on integrin-mediated cell spreading and adhesion on FN and MAPK activation. In contrast with cells on FN substrates, rat embryo fibroblasts on FN120, which lacks HepII, were less spread, had weaker adhesion to FN and failed to form focal adhesions and actin stress fibres. Phosphotyrosine was present in the focal contacts of rat embryo fibroblasts on FN within 30 min but was absent from cells on FN120. Overall, tyrosine phosphorylation was much less in cell lysates from cells on FN120, with decreased phosphorylation of focal adhesion kinase ('pp125FAK') on tyrosine-397, implying additional regulation of tyrosine phosphorylation by HepII. Nevertheless, adhesion-mediated MAPK activity was similar in cells on FN and on FN120. Furthermore, cells spread on FN and on FN120 substrates showed similar MAPK activation in response to treatment with epidermal growth factor and with platelet-derived growth factor. Consistently, overexpression of syndecan-4, which binds to HepII, enhanced cell spreading and adhesion on FN but did not affect integrin-mediated MAPK activation. We therefore conclude that both HepII and syndecan-4 regulate integrin-mediated cell spreading but not MAPK activation.

Actins↗

PubMed2001

Solution structure of the dimeric cytoplasmic domain of syndecan-4.

The syndecans, transmembrane proteoglycans which are involved in the organization of cytoskeleton and/or actin microfilaments, have important roles as cell surface receptors during cell-cell and/or cell-matrix interactions. Since previous studies indicate that the function of the syndecan-4 cytoplasmic domain is dependent on its oligomeric status, the conformation of the syndecan-4 cytoplasmic domain itself is important in the understanding of its biological roles. Gel filtration results show that the syndecan-4 cytoplasmic domain (4L) itself forms a dimer stabilized by ionic interactions between peptides at physiological pH. Commensurately, the NMR structures demonstrate that syndecan-4L is a compact intertwined dimer with a symmetric clamp shape in the central variable V region with a root-mean-square deviation between backbone atom coordinates of 0.95 A for residues Leu(186)-Ala(195). The molecular surface of the 4L dimer is highly positively charged. In addition, no intersubunit NOEs in membrane proximal amino acid resides (C1 region) have been observed, demonstrating that the C1 region is mostly unstructured in the syndecan-4L dimer. Interestingly, two parallel strands of 4L form a cavity in the center of the dimeric twist similar to our previously reported 4V structure. The overall topology of the central variable region within the 4L structure is very similar to that of 4V complexed with the phosphatidylinositol 4,5-bisphosphate; however, the intersubunit interaction mode is affected by the presence of C1 and C2 regions. Therefore, we propose that although the 4V region in the full cytoplasmic domain has a tendency for strong peptide--peptide interaction, it may not be enough to overcome the repulsion of the C1 regions of syndecan-4L.

Amino Acid Sequence↗

PubMed2001

Rat embryo fibroblasts require both the cell-binding and the heparin-binding domains of fibronectin for survival.

Fibronectin (FN) is known to transduce signal(s) to rescue cells from detachment-induced apoptosis (anoikis) through an integrin-mediated survival pathway. However, the functions of individual FN domains have not been studied in detail. In the present study we investigated whether the interaction of the cell-binding domain of FN with integrin is sufficient to rescue rat embryo fibroblasts (REFs) from detachment-induced apoptosis. REFs attached and spread normally after plating on substrates coated with either intact FN or a FN fragment, FN120, that contains the cell-binding domain but lacks the C-terminal heparin-binding domain, HepII. REFs on FN maintained a well-spread fibroblastic shape and even proliferated in serum-free medium at 20 h after plating. In contrast, previously well-spread REFs on FN120 started losing fibroblastic shape with time and detached from FN120-coated plates after approx. 8 h. Nuclear condensation indicated apototic cell death. This was due to the decreased activity/stability of focal adhesion kinase (pp125FAK) in the absence of HepII domain. A peptide in the HepII domain [peptide V, WQPPRARI (single-letter amino acid codes)], which has previously been implicated in cytoskeletal organization, rescued apoptotic changes. Consistently, pp125FAK phosphorylation was increased, and both cleavage of pp125FAK and activation of caspase 3 on FN120 were partly blocked by peptide V. Thus the interaction of the cell-binding domain with integrin has a major role in cell survival but is itself not sufficient for cell survival. One or more additional survival signals come from the HepII domain to regulate pp125FAK activity/stability.

Amino Acid Sequence↗

PubMed2001

Changes in autoimmune thyroid disease following allogeneic bone marrow transplantation.

Autoimmune diseases can be transmitted and eliminated by bone marrow transplantation (BMT). There have been several cases of autoimmune thyroid disease (AITD) occurring after BMT, but AITD remission has been rarely reported. We present four cases in which the remission or transfer of AITD occurred after an allogeneic BMT. Two patients with severe aplastic anemia (SAA) showed evidence of remission of Hashimoto's thyroiditis which they had before allogeneic BMT. One patient with SAA, which developed during treatment with propylthiouracil for Graves' disease, underwent allogeneic BMT and showed evidence of Graves' disease remission following BMT. In one patient, new AITD occurred after an allogeneic BMT from an HLA-matched sibling who already had AITD. These cases support the evidence that the immune system is newly reconstituted after BMT, and severe autoimmune disease can be an indication for BMT. To fully understand the real changes in autoimmune status after BMT, long-term prospective studies are necessary.

Adolescent↗

PubMed2000

Responsiveness of the state of O-linked N-acetylglucosamine modification of nuclear pore protein p62 to the extracellular glucose concentration.

O-linked N-acetylglucosamine (O-GlcNAc) modification has been described in many proteins, including nuclear pore glycoproteins. In the present study we investigated the effect of extracellular glucose on the level of modification of nuclear pore protein p62 by O-GlcNAc. We found that exposure of cells to a high concentration of glucose caused an increased level of modification of p62 with O-GlcNAc, whereas the modification of other proteins did not change detectably. The increased O-GlcNAc modification of p62 in response to glucose required the metabolism of glucose to glucosamine. The exposure of the cells to glucosamine itself also caused increased O-GlcNAc modification, whereas mannosamine and galactosamine did not. Furthermore, changes in glucose concentrations within the physiological range induced the O-GlcNAc modification in p62 in rat aortic smooth-muscle cells, indicating that this modification of p62 might occur in an intact animal. These results imply that the ambient glucose concentration has an impact on the level of O-GlcNAc modification of proteins such as p62, and that functional changes in some of these proteins might ensue.

Acetylglucosamine↗

PubMed1999

Regulation of early events in integrin signaling by protein tyrosine phosphatase SHP-2.

The nontransmembrane protein tyrosine phosphatase SHP-2 plays a critical role in growth factor and cytokine signaling pathways. Previous studies revealed that a fraction of SHP-2 moves to focal contacts upon integrin engagement and that SHP-2 binds to SHP substrate 1 (SHPS-1)/SIRP-1alpha, a transmembrane glycoprotein with adhesion molecule characteristics (Y. Fujioka et al., Mol. Cell. Biol. 16:6887-6899, 1996; M. Tsuda et al., J. Biol. Chem. 273:13223-13229). Therefore, we asked whether SHP2-SHPS-1 complexes participate in integrin signaling. SHPS-1 tyrosyl phosphorylation increased upon plating of murine fibroblasts onto specific extracellular matrices. Both in vitro and in vivo studies indicate that SHPS-1 tyrosyl phosphorylation is catalyzed by Src family protein tyrosine kinases (PTKs). Overexpression of SHPS-1 in 293 cells potentiated integrin-induced mitogen-activated protein kinase (MAPK) activation, and potentiation required functional SHP-2. To further explore the role of SHP-2 in integrin signaling, we analyzed the responses of SHP-2 exon 3(-/-) and wild-type cell lines to being plated on fibronectin. Integrin-induced activation of Src family PTKs, tyrosyl phosphorylation of several focal adhesion proteins, MAPK activation, and the ability to spread on fibronectin were defective in SHP-2 mutant fibroblasts but were restored upon SHP-2 expression. Our data suggest a positive-feedback model in which, upon integrin engagement, basal levels of c-Src activity catalyze the tyrosyl phosphorylation of SHPS-1, thereby recruiting SHP-2 to the plasma membrane, where, perhaps by further activating Src PTKs, SHP-2 transduces positive signals for downstream events such as MAPK activation and cell shape changes.

Animals↗

PubMed1998

Solution structure of a syndecan-4 cytoplasmic domain and its interaction with phosphatidylinositol 4,5-bisphosphate.

Syndecan-4, a transmembrane heparan sulfate proteoglycan, is a coreceptor with integrins in cell adhesion. It has been suggested to form a ternary signaling complex with protein kinase Calpha and phosphatidylinositol 4,5-bisphosphate (PIP2). Syndecans each have a unique, central, and variable (V) region in their cytoplasmic domains, and that of syndecan-4 is critical to its interaction with protein kinase C and PIP2. Two oligopeptides corresponding to the variable region (4V) and whole domain (4L) of syndecan-4 cytoplasmic domain were synthesized for nuclear magnetic resonance (NMR) studies. Data from NMR and circular dichroism indicate that the cytoplasmic domain undergoes a conformational transition and forms a symmetric dimer in the presence of phospholipid activator PIP2. The solution conformations of both free and PIP2-complexed 4V have been determined by two-dimensional NMR spectroscopy and dynamical simulated annealing calculations. The 4V peptide in the presence of PIP2 formed a compact dimer with two twisted strands packed parallel to each other and the exposed surface of the dimer consisted of highly charged and polar residues. The overall three-dimensional structure in solution exhibits a twisted clamp shape having a cavity in the center of dimeric interface. In addition, it has been observed that the syndecan-4V strongly interacts not only with fatty acyl groups but also the anionic head group of PIP2. These findings reveal that PIP2 promotes oligomerization of syndecan-4 cytoplasmic domain for transmembrane signaling and cell-matrix adhesion.

Amino Acid Sequence↗

PubMed1998

Syndecan-4 proteoglycan cytoplasmic domain and phosphatidylinositol 4,5-bisphosphate coordinately regulate protein kinase C activity.

Phosphatidylinositol 4,5-bisphosphate (PIP2) is involved in the organization of the actin cytoskeleton by regulating actin-associated proteins. The transmembrane heparan sulfate proteoglycan syndecan-4 also plays a critical role in protein kinase C (PKC) signaling in the formation of focal adhesions and actin stress fibers. The cytoplasmic domain of syndecan-4 core protein directly interacts with and potentiates PKCalpha activity, and it can directly interact with the phos- phoinositide PIP2. We, therefore, investigated whether the interaction of inositol phosphates and inositol phospholipids with syndecan-4 could regulate PKC activity. Data from in vitro kinase assays using purified PKCalpha beta gamma show that in the absence of phosphatidylserine and diolein, PIP2 increased the extent of autophosphorylation of PKCalpha beta gamma and partially activated it to phosphorylate both histone III-S and an epidermal growth factor receptor peptide. This activity was dose-dependent, and its calcium dependence varied with PKC isotype/source. Addition of the cytoplasmic syndecan-4 peptide, but not equivalent syndecan-1 or syndecan-2 peptides, potentiated the partial activation of PKCalpha beta gamma by PIP2, resulting in activity greater than that observed with phosphatidylserine, diolein, and calcium. This study indicates that syndecan-4 cytoplasmic domain may bind both PIP2 and PKCalpha, localize them to forming focal adhesions, and potentiate PKCalpha activity there.

Amino Acid Sequence↗

PubMed1998

Syndecan proteoglycans and cell adhesion.

It is now becoming clear that a family of transmembrane proteoglycans, the syndecans, have important roles in cell adhesion. They participate through binding of matrix ligand to their glycosaminoglycan chains, clustering, and the induction of signaling cascades to modify the internal microfilament organization. Syndecans can modulate the type of adhesive responses induced by other matrix ligand-receptor interactions, such as those involving the integrins, and so contribute to the control of cell morphology, adhesion and migration.

Amino Acid Sequence↗

PubMed1997

Serine phosphorylation of syndecan-2 proteoglycan cytoplasmic domain.

Protein kinase C (PKC) is involved in cell-matrix and cell-cell adhesion, and the cytoplasmic domain of syndecan-2 contains two serines (residues 197 and 198) which lie in a consensus sequence for phosphorylation by PKC. Other serine and threonine residues are present but not in a consensus sequence. We investigated phosphorylation of syndecan-2 cytoplasmic domain by PKC, using purified GST-syndecan-2 fusion proteins and synthetic peptides corresponding to regions of the cytoplasmic domain. A synthetic peptide encompassing the entire cytoplasmic domain of syndecan-2 was phosphorylated by PKC with high affinity. Peptide mapping and substitution studies showed that both serines were phosphoacceptors, but each had slightly different affinity, with that of serine-197 being higher than serine-198. The efficiency of phosphorylation was concentration-dependent. At low concentrations, the cytoplasmic domain peptides were monomeric, with 2 mol/mol serine phosphorylation. At higher concentrations, however, the peptides formed dimers, with only 0.5 mol/mol phosphorylation. Concentration-dependent dimerization was not altered by phosphorylation. Phosphorylation is, therefore, dependent on the conformation of syndecan-2 cytoplasmic domain, but does not affect its oligomeric status.

Amino Acid Sequence↗

PubMed1997

Multimerization of the cytoplasmic domain of syndecan-4 is required for its ability to activate protein kinase C.

The transmembrane proteoglycan syndecan-4, which is a coreceptor with integrins in cytoskeleton-matrix interactions, appears to be multimerized in vivo. Both purified and recombinant core proteins form sodium dodecyl sulfate-resistant oligomers, and we now report that a synthetic peptide corresponding to the central region of syndecan-4 cytoplasmic domain (4V) also oligomerizes. The degree of oligomerization correlates with the previously reported ability to bind protein kinase C (PKC) and regulate its activity. Only multimeric recombinant syndecan-4 core protein, but not the monomeric protein, potentiated the activity of PKCalpha, and only oligomeric syndecan-4 cytoplasmic peptides were active. Changes in peptide sequence caused parallel loss of stable oligomeric status and ability to regulate a mixture of PKCalphabetagamma activity. A synthetic peptide encompassing the whole cytoplasmic domain of syndecan-4 (4L) containing a membrane-proximal basic sequence did not form higher order oligomers and could not regulate the activity of PKCalphabetagamma unless induced to aggregate by phosphatidylinositol 4,5-bisphosphate. Oligomerization and PKC regulatory activity of the 4V peptide were both increased by addition of N-terminal cysteine and reduced by phosphorylation of the cysteine thiol group. Concentration of syndecan-4 at sites of focal adhesion formation may enhance multimerization and both localize PKC and potentiate its activity to induce stable complex formation.

Adenosine Triphosphate↗

PubMed1997

Syndecan-4 proteoglycan regulates the distribution and activity of protein kinase C.

During cell-matrix adhesion, both tyrosine and serine/threonine kinases are activated. Integrin ligation correlates with tyrosine phosphorylation, whereas the later stages of spreading and focal adhesion and stress fiber formation in primary fibroblasts requires interactions of cell surface proteoglycan with heparin-binding moieties. This correlates with protein kinase C (PKC) activation, and PKCalpha can become localized to focal adhesions in normal, but not transformed, cells. PKC activation has been thought to be downstream of initial receptor-ligand interactions. We now show, however, that syndecan-4 transmembrane heparan sulfate proteoglycan and PKC co-immunoprecipitate and co-patch in vivo. The core protein of syndecan-4 can directly bind the catalytic domain of PKCalpha and potentiate its activation by phospholipid mediators. It can also directly activate PKCalpha in the absence of other mediators. This activity resides in the sequence LGKKPIYKK in the center of the short cytoplasmic domain, and other syndecans lack this sequence and PKC regulatory properties. Syndecan-4 is a focal adhesion component, and this interaction may both localize PKC and amplify its activity at sites of forming adhesions. This represents the first report of direct transmembrane signaling through cell surface proteoglycans.

Amino Acid Sequence↗

PubMed1992

Plasma and urinary concentrations of methamphetamine after oral administration of famprofazone to man.

1. To obtain further evidence for the metabolic formation of methamphetamine from famprofazone in man, concentrations of methamphetamine in plasma, as well as in urine, were measured by g.l.c. In addition, intact famprofazone and famprofazone N-oxide were analysed in the urine. 2. Methamphetamine appeared in plasma 1 h after a single 100 mg dose of the drug to two male subjects, and the concentration maintained between 24 and 44 ng/ml over 2-12 h, declining to 10 ng/ml and an undetectable level respectively after 24 h. 3. Total urinary excretion of methamphetamine over 72 h was 1.9 mg for a 25 mg dose and 2.2 mg for a 50 mg dose. After a 100 mg dose, 4.6 mg of methamphetamine was excreted over 36 h. Neither intact famprofazone nor famprofazone N-oxide were detected when the urine samples after the 100 mg dose were examined. 4. The results provide further evidence that methamphetamine is a bona fide human metabolite of famprofazone and suggest that at least 20% dose may be broken down via the pathways leading to the formation of methamphetamine. This could have significant clinical implications as the result of pharmacological activity of this metabolite.

Administration, Oral↗

PubMedDate not supplied

The utility of in-phase/opposed-phase imaging in differentiating malignancy from acute benign compression fractures of the spine.

BACKGROUND AND PURPOSE: Benign and malignant fractures of the spine may have similar signal intensity characteristics on conventional MR imaging sequences. This study assesses whether in-phase/opposed-phase imaging of the spine can differentiate these 2 entities. METHODS: Twenty-five consecutive patients who were evaluated for suspected malignancy (lymphoma [4 patients], breast cancer [3], multiple myeloma [2], melanoma [2], prostate [2], and renal cell carcinoma [1]) or for trauma to the thoracic or lumbar spine were entered into this study. An 18-month clinical follow-up was performed. Patients underwent standard MR imaging with an additional sagittal in-phase (repetition time [TR], 90-185; echo time [TE], 2.4 or 6.5; flip angle, 90 degrees ) and opposed-phase gradient recalled-echo sequence (TR, 90-185, TE, 4.6-4.7, flip angle, 90 degrees ). Areas that were of abnormal signal intensity on the T1 and T2 sequences were identified on the in-phase/opposed-phase sequences. An elliptical region of interest measurement of the signal intensity was made on the abnormal region on the in-phase as well as on the opposed-phase images. A computation of the signal intensity ratio (SIR) in the abnormal marrow on the opposed-phase to signal intensity measured on the in-phase images was made. RESULTS: Twenty-one patients had 49 vertebral lesions, consisting of 20 malignant and 29 benign fractures. There was a significant difference (P < .001, Student t test) in the mean SIR for the benign lesions (mean, 0.58; SD, 0.02) compared with the malignant lesions (mean, 0.98; SD, 0.095). If a SIR of 0.80 as a cutoff is chosen, with >0.8 defined as malignant and <0.8 defined as a benign result, in-phase/opposed-phase imaging correctly identified 19 of 20 malignant lesions and 26 of 29 benign lesions (sensitivity, 0.95; specificity, 0.89). CONCLUSION: There is significant difference in signal intensity between benign compression fractures and malignancy on in-phase/opposed-phase MR imaging.

Adult↗