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C L Yu

Publications and source records attributed to C L Yu.

At least 37 records · Page 2Linked to original sources
PubMed2000

Monoclonal anti-double-stranded DNA autoantibody stimulates the expression and release of IL-1beta, IL-6, IL-8, IL-10 and TNF-alpha from normal human mononuclear cells involving in the lupus pathogenesis.

In our previous reports, we found polyclonal anti-double-stranded DNA antibodies (anti-dsDNA) purified from patients with active systemic lupus erythematosus (SLE) exerted inhibitory effect on [3H]thymidine incorporation of human mononuclear cells (MNC). However, the other immunological effects of anti-dsDNA on the functions of MNC have not yet been reported. In this study, two monoclonal antibodies, 12B3 and 9D7, with different anti-dsDNA activity were evaluated for their effects on the expression and release of different cytokines from human MNC. We confirmed absence of endotoxin in the two monoclonal antibody preparations and the used medium as detected by Limulus amoebocyte lysate test. The mRNA expression and release of different cytokines including interleukin (IL)-1beta, IL-2, IL-4, IL-6, IL-8, IL-10, tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) were measured. We found the two monoclonal anti-dsDNA not only dose-responsively suppressed the phytohaemagglutinin (PHA)-induced thymidine uptake of human MNC but stimulated the mRNA expression of IL-1beta, IL-6 and IL-8 in normal human MNC detected by reverse transcription-polymerase chain reaction (RT-PCR). Enzyme-linked immunosorbent assay (ELISA) measurement of cytokines in MNC culture supernatants revealed that anti-dsDNA enhanced IL-1beta, IL-8, TNF-alpha and IL-10 release from resting MNC. These effects of anti-dsDNA antibodies were not affected by polymyxin B, a potent binder and neutralizer of lipopolysaccharide (LPS). These in vitro studies suggest that anti-dsDNA possess a dual effect on normal human MNC: (a) to enhance the release of proinflammatory cytokines (IL-1beta, IL-8 and TNF-alpha) from MNC to augment inflammatory reaction; and (b) to polarize the immune reaction towards the T helper 2 (Th2) (increased IL-10 production) pathway. This unique effect of anti-dsDNA may play a role in lupus pathogenesis by augmenting inflammatory reactions and autoantibody production which are commonly found in patients with active SLE.

Animals↗
PubMed2000

IgG anti-melanocyte antibodies purified from patients with active vitiligo induce HLA-DR and intercellular adhesion molecule-1 expression and an increase in interleukin-8 release by melanocytes.

An immunologic hypothesis is currently proposed as a possible pathogenesis of nonsegmental-type vitiligo. IgG antibodies against melanocyte surface antigens exist in the serum of patients with vitiligo vulgaris. IgG anti-melanocyte antibodies were reported to induce melanocyte damage in vitro by a complement-mediated mechanism and antibody-dependent cellular cytotoxicity. Perilesional melanocytes express major histocompatibility complex class II antigens and a higher intercellular adhesion molecule-1 compared with those in normal skin. The purpose of this study was to determine the role of IgG anti-melanocyte antibodies in the inappropriate expression of major histocompatibility complex class II antigens and intercellular adhesion molecule-1 on melanocytes. IgG anti-melanocyte antibody samples were purified from the individual serum of patients with active vitiligo. After incubation of IgG anti-melanocyte antibodies with cultured melanocytes, the results revealed: (i) IgG anti-melanocyte antibody stimulated HLA-DR expression on melanocytes; (ii) intercellular adhesion molecule-1 expression on melanocytes was significantly induced by IgG anti-melanocyte antibodies; and (iii) IgG anti-melanocyte antibodies induced an increase in interleukin-8 release from melanocytes. The major histocompatibility complex class II molecules expressed in melanocytes can present antigens to CD4 helper cells as antigen-presenting cells and elicit an immune response. Intercellular adhesion molecule-1 is an important adhesion molecule involved in leukocyte and parenchymal cell interaction and thus plays an essential part in immunologic and inflammatory reactions. It is reasonable to speculate that abnormal expressions of HLA-DR and intercellular adhesion molecule-1 on melanocytes by IgG anti-melanocyte antibodies would present vitiligo antigens and allow the antigen-specific immune effector cell attack that results in melanocytotoxicity.

Antibodies, Anti-Idiotypic↗
PubMed2000

Polyclonal anticardiolipin antibodies purified from sera of patients with active systemic lupus erythematosus induce apoptosis of the cultured glomerular mesangial cells.

OBJECTIVE: To test the effect of anticardiolipin antibodies (aCL) on cultured glomerular mesangial cells with regard to their expression of apoptosis-related genes. METHODS: aCL purified from active lupus sera by cardiolipin micelles were incubated with cultured rodent mesangial cells (RMC). Morphological changes of the RMC were observed. The genomic DNA was extracted for the detection of apoptosis. The total cell RNA was extracted for detection of Fas, c-myc, p53, and bcl-2 transcripts by reverse transcription-polymerase chain reaction. RESULTS: aCL (100 GPL-U/0.1 mg protein/ml) bound to RMC more prominent than human IgG (100 microg/ml). The antibodies suppressed RMC proliferation in a dose-dependent manner. The RMC were undergoing apoptosis as evidenced by morphologic changes, fluoresceinannexin V staining and appearance of nucleosome-sized DNA fragments. RMC spontaneously express p53 and c-myc but not Fas or bcl-2. aCL (100 GPL-U/ml) enhanced the expression of Fas but not other apoptosis-related genes and suppressed the intracellular tyrosine phosphorylation. CONCLUSIONS: Binding of aCL can induce apoptosis of the RMC. The aCL may be implicated in the pathogenesis of lupus nephritis.

Animals↗
PubMed2000

Regioselectivity and enantioselectivity of naphthalene dioxygenase during arene cis-dihydroxylation: control by phenylalanine 352 in the alpha subunit.

The naphthalene dioxygenase (NDO) system catalyzes the first step in the degradation of naphthalene by Pseudomonas sp. strain NCIB 9816-4. The enzyme has a broad substrate range and catalyzes several types of reactions including cis-dihydroxylation, monooxygenation, and desaturation. Substitution of valine or leucine at Phe-352 near the active site iron in the alpha subunit of NDO altered the stereochemistry of naphthalene cis-dihydrodiol formed from naphthalene and also changed the region of oxidation of biphenyl and phenanthrene. In this study, we replaced Phe-352 with glycine, alanine, isoleucine, threonine, tryptophan, and tyrosine and determined the activity with naphthalene, biphenyl, and phenanthrene as substrates. NDO variants F352W and F352Y were marginally active with all substrates tested. F352G and F352A had reduced but significant activity, and F352I, F352T, F352V, and F352L had nearly wild-type activities with respect to naphthalene oxidation. All active enzymes had altered regioselectivity with biphenyl and phenanthrene. In addition, the F352V and F352T variants formed the opposite enantiomer of biphenyl cis-3,4-dihydrodiol [77 and 60% (-)-(3S,4R), respectively] to that formed by wild-type NDO [>98% (+)-(3R,4S)]. The F352V mutant enzyme also formed the opposite enantiomer of phenanthrene cis-1,2-dihydrodiol from phenanthrene to that formed by biphenyl dioxygenase from Sphingomonas yanoikuyae B8/36. A recombinant Escherichia coli strain expressing the F352V variant of NDO and the enantioselective toluene cis-dihydrodiol dehydrogenase from Pseudomonas putida F1 was used to produce enantiomerically pure (-)-biphenyl cis-(3S,4R)-dihydrodiol and (-)-phenanthrene cis-(1S,2R)-dihydrodiol from biphenyl and phenanthrene, respectively.

Anthracenes↗
PubMed2000

Increased excretions of beta2-microglobulin, IL-6, and IL-8 and decreased excretion of Tamm-Horsfall glycoprotein in urine of patients with active lupus nephritis.

Tubulointerstitial nephritis is a less frequently recognized but important complication of systemic lupus erythematosus. We have investigated the cytokine beta2-microglobulin (beta2M) and Tamm-Horsfall glycoprotein (THG) excretions in the urine of systemic lupus erythematosus patients to identify indices for evaluation of tubulointerstitial inflammation in lupus nephritis (LN). Daily urine was collected from 15 patients with active LN, from 12 patients with inactive LN, and from 17 normal subjects. The amounts of soluble interleukin (IL) 2 receptor, IL-6, IL-8, beta2M, and THG in urine were measured. Beta2M and THG were regarded as indicators of proximal and distal renal tubule function, respectively. The urinary excretions of IL-6 and IL-8 were significantly higher in patients with active LN than in those with inactive LN and in normal individuals. The excretion of soluble IL-2 receptor in all three groups of subjects was not significantly different. On the other hand, the excretion of beta2M in patients with LN was significantly higher than that in normal individuals. The excretion of beta2M in patients with active or inactive LN was not significantly different. The THG excretion was lower in patients with active LN and tubulointerstitial inflammation as compared with patients with inactive LN or normal individuals. Six patients underwent pulse cyclophosphamide therapy during the course of experiments. Five of them showed a decrease in IL-8 and IL-6 excretions in urine after the treatment. The excretions of beta2M and THG in urine, in addition to IL-6 and IL-8, can reflect the renal inflammatory activity in patients with lupus tubulointerstitial nephritis as well as in those having lupus glomerulonephritis.

Case-Control Studies↗
PubMed2000

Anesthesia with deep hypothermic circulatory arrest for giant basilar aneurysm surgery.

The application of deep hypothermic circulatory arrest (DHCA) as an adjutant technique in anesthetic management for surgery of giant and complex cerebral aneurysm has been clinically recognized with piling up experience in many institutes. DHCA provides the advantages such as a bloodless surgical field and protection of the brain, all of which make a precise clipping of the aneurysm possible and thus it lowers the mortality rate which could be extremely high without it. Nevertheless, in application, the disadvantages of this technique includes comparatively inefficient and uneven cooling or rewarming, severe physiological change, cardiac distension and arrhythmia during cardiopulmonary bypass (CPB), hemorrhage from systemic heparinization and brain damage due to inadequate protection, none of which has ever been stressed. Since many giant aneurysms are found inoperable during exploration with application of DHCA, it would change the fate of the patients, and the clinical value of DHCA in such an instance becomes contradictive and disputable. We would like to present our experience in a case who, because of a giant basilar aneurysm, underwent surgical correction under DHCA retrograde cerebral perfusion (RCP) with cerebral function monitoring including electroencephalography (EEG), brainstem auditory evoked potentials (BAEP), thermal diffusion cerebral blood flowmetry, study of the change of extracellular concentration of excitatory amino acid, glutamate and aspartate, and off-line neurochemical analysis with cerebral microdialysis technique.

Adult↗
PubMed1999

Human 70-kDa SHP-1L differs from 68-kDa SHP-1 in its C-terminal structure and catalytic activity.

The tyrosine phosphatase SHP-1 functions as a negative regulator in hematopoietic cell development, proliferation, and receptor-mediated cellular activation. In Jurkat T cells, a major 68-kDa band and a minor 70-kDa band were immunoprecipitated by a monoclonal antibody against the SHP-1 protein-tyrosine phosphatase domain, while an antibody against the SHP-1 C-terminal 19 amino acids recognized only the 68-kDa SHP-1. The SDS-gel-purified 70-kDa protein was subjected to tryptic mapping and microsequencing, which was followed by molecular cloning. It revealed that the 70-kDa protein, termed SHP-1L, is a C-terminal alternatively spliced form of SHP-1. SHP-1L is 29 amino acids longer than SHP-1, and its 66 C-terminal amino acids are different from SHP-1. The C terminus of SHP-1L contains a proline-rich motif PVPGPPVLSP, a potential Src homology 3 domain-binding site. In contrast to SHP-1, tyrosine phosphorylation of SHP-1L is not detected upon stimulation in Jurkat T cells. This is apparently due to the lack of a single in vivo tyrosine phosphorylation site, which only exists in the C terminus of SHP-1 (Y564). COS cell-expressed glutathione S-transferase-SHP-1L can dephosphorylate tyrosine-phosphorylated ZAP70. At pH 7.4, SHP-1L was shown to be more active than SHP-1 in the dephosphorylation of ZAP70. At pH 5.4, SHP-1L and SHP-1 exhibited similar catalytic activity. It is likely that these two isoforms play different roles in the regulation of hematopoietic cell signal transduction.

Alternative Splicing↗
PubMed1999

Anti-dsDNA autoantibody cross-reacts with the C-terminal hydrophobic cluster region containing phenylalanines in the acidic ribosomal phosphoprotein P1 to exert a cytostatic effect on the cells.

The present study was an attempt to map the epitope in P1 protein which may cross-react with anti-dsDNA. In addition to wild-type P1, the genes of its C-terminal mutants were cloned and expressed. The binding activity of these proteins with anti-dsDNA was determined by Western blot and ELISA. The P1 mutants with complete deletion of the acidic charge and hydrophobic clusters, deletion of the hydrophobic cluster, or replacement of the phenylanlanines with alanine in the hydrophobic cluster lost the binding activity. Moreover, P1 mutants with mutation at the serine phosphorylation sites (positions 102 and 105) retained their binding activities with anti-dsDNA. However, those with mutation at the serine phosphorylation sites and without the hydrophobic cluster lost their binding activities. These findings suggest that phenylalanines in the C-terminal hydrophobic cluster region of ribosomal P proteins are essential to their cross-reactivity with anti-dsDNA.

Amino Acid Sequence↗
PubMed1999

Increased cutaneous blood flow but impaired post-ischemic response of nutritional flow in obese children.

It is well known that cardiovascular risk factors and dyslipidemia along with obesity can be identified early in life. Serum lipids and lipoproteins influence skin vessel reactivity in adults. The purpose of this study was to investigate the cutaneous microcirculation and its correlation to dyslipidemia in obese children. Thirty-four obese children and an equal number of age- and sex-matched healthy children were enrolled in this study. Laser Doppler flowmetry and dynamic capillaroscopy were performed to measure total cutaneous blood flow and nutritional blood flow, respectively. A significantly higher cutaneous baseline flow and peak flow after a 1-min arterial occlusion was noticed in obese group as compared to normal control. Results of dynamic capillaroscopy revealed values of resting capillary blood cell velocity that did not differ from controls but a significantly lower peak CBV after a 1-min arterial occlusion in obesity. Plasma lipids examination showed a high triglycerides and low high density lipoprotein cholesterol levels in obesity. Pearson analysis detected no significant correlations between pCBV, baseline flow and peak flow and dyslipidemia in obesity. These results may be explained by the fact that the duration of dyslipidemia in our study population was not long enough to cause vascular damage or the dyslipidemia was not pronounced enough to have an impact on skin vessel activity tests. It is also possible, that the combination of methods used in the present study was not sensitive enough to detect an existing correlations between flow values and high triglycerides/low HDL-cholesterol values in the obese group. Our results suggest that all the responses of the cutaneous microcirculation were mainly due to physiological compensatory rather than pathological reactions in young obese children. The results of cutaneous microcirculatory assessment in obese children provide follow-up parameters for assessing the risk of cardiovascular diseases later in life.

Adolescent↗
PubMed1998

Interleukin-13 increases prostaglandin E2 (PGE2) production by normal human polymorphonuclear neutrophils by enhancing cyclooxygenase 2 (COX-2) gene expression.

OBJECTIVE: To investigate whether interleukin-13 (IL-13) can affect arachidonic acid metabolism and phagocytic activity of normal human polymorphonuclear neutrophils (PMN). METHODS: Normal human PMN (1 x 10(6) cells/ml) were incubated with different concentrations of IL-13 (0.1-10 ng/ml) for a variety of times (30-120 min). Phagocytosis and intracellular cyclooxygenase-2 (COX-2) were detected by flow cytometry. The expression of COX-1 and COX-2 mRNA was detected by RT-PCR. The concentration of PGE2 in the PMN cultured supernatants was determined by EIA. RESULTS: We found that IL-13 at an optimal concentration of 1 ng/ml significantly enhanced COX-2 gene expression and PGE2 production (121.57 +/- 22.17 pg/ml in IL-13 stimulation vs. 73.16 +/- 11.72 pg/ml in controls) by PMN. In addition, IL-13 stimulated PMN phagocytosis via increased complement receptor type 1 (CR1) and type 3 (CR3), but not IgG Fcgamma receptor type 3 (FcgammaRIII). The cytoplasmic neutral esterase activity of PMN was also enhanced by IL-13 stimulation for 24 h. CONCLUSIONS: These results suggest that IL-13 can stimulate PMN and modulates the inflammatory reactions via the cyclooxygenase pathway.

Cells, Cultured↗
PubMed1998

Defective IL-2 receptor expression in lymphocytes of patients with arsenic-induced Bowen's disease.

The immune function of peripheral mononuclear cells (MNC) in patients with endemic arsenic-induced Bowen's disease (BD) was investigated. Many cytokines and immune-related factors were determined in the present study. Interleukin-1beta and TNF-alpha production was used as an indicator of monocyte/macrophage function. II-2 and sIL-2R production was used as an indicator of lymphocyte activation. The release of sCD4 and sCD8 was used as an indicator of activation of respective T-cell subpopulations. Production of IFN-gamma and IL-2 reflected the cellular effector function of helper T-cells type 1. In vivo cell-mediated immunity was also assessed by estimation of the percentage of T-cells in peripheral blood MNC and the nonspecific delayed-type hypersensitivity (DTH) response to 2,4-dinitrochlorobenzene (DNCB). Both assays revealed depressed cell-mediated immunity in BD. Compared with healthy controls, spontaneous and PHA-induced IFN-gamma and TNF-alpha production was significantly decreased in BD whereas spontaneous release of IL-2, sCD4 and sCD8 was significantly increased. Although PHA stimulation increased IL-2 release, the expression of IL-2R alpha and beta chains and the release of sIL-2R were not proportionately increased in BD. In addition, IL-2-mediated [3H]-thymidine incorporation by MNC in patients with BD was significantly decreased. These findings suggest that the defective cell-mediated immune function in BD is due to impairment of membrane IL-2R expression in lymphocytes after stimulation.

Aged↗
PubMed1998

In vitro cytotoxicity of IgG antibodies on vascular endothelial cells from patients with endemic peripheral vascular disease in Taiwan.

A unique peripheral vascular disorder called 'blackfoot disease' is endemic in a limited area on the south-west coast of Taiwan. Clinically, the signs and symptoms of blackfoot disease (BFD) are similar to those of arteriosclerosis and Buerger's disease. A destruction of vascular endothelial cells (ECs) takes place at an early stage in the affected limbs. Currently, the cause of BFD is believed to be artesian drinking water containing a high concentration of arsenic and/or humic substances, although the mechanism of EC destruction is not entirely understood. The purpose of the present study was to examine the factors related to EC damage in BFD. Thus, we investigated the effects of purified IgG collected from patients with BFD (BFD-IgG) and from normal controls (N-IgG) on cultured EC. We found that: (1) EC binding activity of BFD-IgG was significantly higher than that of N-IgG; (2) BFD-IgG, at a concentration higher than 100 microg/ml but not N-IgG, induced concentration-dependent EC cytotoxicity; (3) BFD-IgG at a concentration of 100 microg/ml stimulated neither the release of von Willebrand factor nor the expression of intercellular adhesion molecule-1 by EC. Fluorescent video microscopic examination revealed an increase in transcapillary and interstitial diffusion of nailfold capillary loops in clinically normal fingers of BFD patients. These findings strongly suggested that immunological mechanisms played a significant role in the pathogenesis of BFD. We propose that only persons who produce the IgG anti-endothelial cell antibody are potential victims of BFD.

Antibodies, Anti-Idiotypic↗
PubMed1998

Inhibitory effects of berberine on voltage- and calcium-activated potassium currents in human myeloma cells.

The effects of berberine, an isoquinoline alkaloid, were investigated in human myeloma cells. In cells with intracellular Ca2+ concentration ([Ca2+]i) = 10 nM, the depolarizing square pulses from -80 mV elicited an instantaneous outward current with an inactivation. This outward current was voltage dependent, activating at -30 mV and showed inactivation with repetitive depolarization, and was hence believed to be n type voltage-activated K+ current (IK(V)). Berberine (30 microM) produced a prolongation in the recovery of IK(V) inactivation. In cells with [Ca2+]i = 1 microM, berberine also inhibited A23187-induced IK(Ca). Berberine (1-300 microM) caused the inhibition of IK(V) and IK(Ca) in the concentration-dependent manners. The IC50 values of berberine-induced inhibition of IK(V) and IK(Ca) were approximately 15 microM and 50 microM, respectively. In inside-out configurations, berberine inside the pipette suppressed the activity of K(Ca) channels without changing the single channel conductance. Berberine also inhibited the proliferation of this cell line and the IC50 value of berberine-induced inhibition of cell proliferation was 5 microM. Thus, the cytotoxic effect of berberine in cancer cells may be partially explained by its direct blockade of these K+ channels.

Antineoplastic Agents↗
PubMed1998

A reproducible, simple, and sensitive high-performance capillary electrophoresis method for simultaneous determination of capreomycin, ofloxacin and pasiniazide in urine.

Separation and determination of capreomycin (Cp), ofloxacin (Oflx) and pasiniazide (Ipa) in urine by high-performance capillary electrophoresis (HPCE) with 280 nm detection have been studied systematically. The calibration lines were linear in the range of 0.5 approximately 50 mg 1(-1), and the detection limits (S/N = 3) were 0.15, 0.20 and 0.10 mg 1(-1) for Cp, Oflx and Ipa, respectively. The recoveries for these materials from urine were higher than 93.5%. The accuracy and intra- and inter- day reproducibility of Cp, Oflx and Ipa were determined with satisfactory results. This method was successfully used for determining Cp. Oflx and Ipa in human urine.

Aminosalicylic Acid↗
PubMed1998

The effect of human polyclonal anti-dsDNA autoantibodies on apoptotic gene expression in cultured rat glomerular mesangial cells.

In our previous studies, we found that polyclonal anti-double-stranded DNA antibodies (anti-dsDNA) purified from sera of patients with active systemic lupus erythematosus (SLE) were cytotoxic to cultured rat glomerular mesangial cells (RMC) through an apoptotic mechanism. In order to determine whether these nephritogenic antibodies affect the expression of apoptosis-related genes in the tissues, the expression of Fas, p53, c-myc, and bcl-2 genes in the kidneys and livers of 12-week-old normal BALB/c and autoimmune MRL-lpr/lpr mice was detected by a reverse transcription-assisted polymerase chain reaction (RT-PCR). We found the mRNA of the four genes were expressed in the tissues of the normal mice. In contrast, decreased expression of the four genes in the kidney and absent expression of bcl-2 in the liver of the lpr mice were noted. Interestingly, RMC only expressed p53 and c-myc, but not Fas or bcl-2, in culture. The purified polyclonal anti-dsDNA dose-responsively (50-200 IU/ml) suppressed the 3H-thymidine incorporation of RMC after incubation for 48 h. However, the incubation of 100 IU/ml of anti-dsDNA with RMC for 4 h did not affect the expression of these apoptotic genes. The results suggest that anti-dsDNA induce RMC apoptosis via an unidentified mechanism different from Fas, c-myc or p53 pathway.

Animals↗