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Biomedical subjects

Y Ding

Publications and source records attributed to Y Ding.

At least 271 records · Page 15Linked to original sources
PubMed1995

Anti-CD2 monoclonal antibody-induced receptor changes: down modulation of cell surface CD2.

Anti-CD2 mAbs suppress T cell immunity and prolong allograft survival in vivo while inducing the down-modulation of CD2 expression. Manipulation of cell surface molecules may be important in inducing tolerance, so down-modulation of CD2 expression on T cells by anti-CD2 mAbs was further defined with an in vitro model. The anti-CD2 mAb 12-15 caused CD2 expression on purified splenic T cells to decrease from 83.4 to 22.7% total positive cells while CD3, CD4, and CD8 expression remained unchanged. The expression of other adhesion molecules, LFA-1 alpha (CD11a), LFA-1 beta (CD18), Pgp-1 (CD44), CD45, MEL-14 (L-selectin), and VLA-4 alpha (CD49d), were all increased as a result of anti-CD2 treatment, whereas CD25 (IL-2R), CD48 (CD2 ligand), and ICAM-1 (CD54) remained unchanged. Kinetics showed that CD2 down-modulation was persistent and at the same magnitude from day 1 through day 7 of culture. Anti-CD2 mAb could down modulate CD2 on both CD4 and CD8 splenic lymphocyte subsets, thymocytes, and the T cell lymphoma EL-4; and, non-T cells did not seem to participate in the process of modulation. Mechanistic studies of mAb action showed that, in addition to 12-15, other anti-CD2 mAbs could cause down-modulation of T cell CD2 expression in an epitope and isotype dependent fashion and that CD2 down-modulation correlated with inhibition of receptor-driven T cell stimulation. Intact antibody, including the Fc portion, was required to induce CD2 down-modulation, and additional experiments suggested an interaction with an Fc gamma R other than Fc gamma RII or Fc gamma RIII. CD2 down-modulation did not change with the addition of the cytokines IL-1, IL-2, IL-6, IL-10, TNF alpha, or TGF-beta 1. These results show that anti-CD2 mAbs significantly and persistently down-modulate CD2 on various T cell subpopulations. The mAbs must interact with both the CD2 receptor and an Fc gamma R. CD2 down-modulation is accompanied by changes in the array of other T cell surface receptors that may contribute to mechanisms of anti-CD2-induced immunosuppression.

Animals↗
PubMed1995

The role of cysteine residues in the erythrocyte plasma membrane anion exchange protein, AE1.

AE1 (Band 3), a congruent to 110-kDa integral plasma membrane protein, facilitates the electroneutral movement of Cl- and HCO3- across the erythrocyte membrane and serves as the primary attachment site for the erythrocyte spectrin-actin cytoskeleton. In this investigation, we have characterized the role of native cysteines in the function of AE1. We have constructed a mutant version of human AE1 (AE1C-) in which all five cysteines of AE1 were replaced with serines. Wild-type and AE1C- cDNAs were expressed by transient transfection of human embryonic kidney cells. Two of the mutated cysteines in AE1C- are in a region involved in ankyrin binding, and ankyrin binding has previously been shown to be sensitive to the oxidation state of these cysteines. However, the KD values for ankyrin binding by AE1 and AE1C- were indistinguishable, suggesting that AE1 cysteines are not essential components of the ankyrin-binding site. Using size exclusion chromatography, both AE1 and AE1C- were found to associate as a mixture of dimers and high molecular mass complexes. The rate of anion exchange by AE1C-, as measured in a reconstituted microsome sulfate transport assay, was indistinguishable from that by AE1 and was inhibited by 4,4'-diisothiocyanodihydrostilbene-2,2'-disulfonate. We conclude that the cysteines of AE1 are not required for the anion exchange or cytoskeletal binding roles of the protein.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1995

Multiple vectors effectively achieve gene transfer in a murine cardiac transplantation model. Immunosuppression with TGF-beta 1 or vIL-10.

The application of gene transfer techniques to organ transplantation offers the potential for modulation of immunity directly within an allograft without systemic side effects. Expression vectors and promoter elements are important determinants of gene transfer and expression. In this study, various vectors (naked plasmid DNA, retroviral vector, herpes simplex viral vector, and adenoviral vector) with various promoters (RSV-LTR, SV40, MuLV-LTR, HCMVie1) were directly compared to demonstrate the successful gene transfer and expression of beta-galactosidase in murine myoblasts in vitro and within murine heterotopic, nonvascularized cardiac isografts or allografts in vivo. Expression of transferred genes was not toxic to cells and strength of expression varied according to the type of vector. Plasmid DNA was expressed in myocytes, retroviral vector was expressed in the graft infiltrating cells, and herpes simplex and adenoviral vectors were expressed in both myocytes and graft-infiltrating cells. Preliminary studies evaluated the ability of these vectors to deliver immunologically important signals. Allografts injected with pSVTGF-beta 1, a plasmid-encoding transforming growth factor beta 1 (TGF-beta 1) under the control of the SV40 promoter, showed significant prolongation of graft survival of 26.3 +/- 2.5 days compared with 12.6 +/- 1.1 days for untreated allografts, and 12.5 +/- 1.5 days for the allografts injected with control plasmid (P < 0.05). Allografts injected with MFG-vIL-10, a retroviral vector encoding viral interleukin-10 under the control of the MuLV-LTR, showed prolongation of graft survival of 36.7 +/- 1.3 days versus 12.6 +/- 1.1 days for the untreated allograft, and 13.5 +/- 2.0 days for the allografts injected with control retroviral vector (P < 0.001). Both vectors were transcriptionally active in vivo and did not appear to have toxic effects. Gene therapy for transplantation can induce transient expression of immunologically relevant molecules within allografts that impede immune activation while avoiding the systemic toxicity of conventional immunosuppression.

Animals↗
PubMed1995

Absence of linkage between human obesity and the mouse agouti homologous region (20q11.2) or other markers spanning chromosome 20q.

Mutant alleles of the agouti gene cause obesity in the mouse and the homologous gene in humans has been mapped to chromosome 20q11.2. An allelic variant of the agouti gene could account for obesity in humans and we tested this hypothesis by genotyping 210 sibling pairs from 45 families segregating an obesity phenotype. Using sibling pair linear regression analysis, evidence for linkage between obesity and markers flanking the agouti locus and other markers spanning chromosome 20q was assessed. We found no correlation between identity-by-descent at these markers and obesity differences within pairs. In the mouse, obesity caused by mutations of the agouti gene develops later in life, so a subset of families with adult-onset obesity were also tested for linkage, with negative results. Although it is not possible to exclude alleles of the agouti gene as a contributor to obesity in humans, the absence of positive linkage in this study suggests that either the agouti gene has small effects or the allele frequency is low.

Age of Onset↗
PubMed1995

Synthesis and biological activity of oligosaccharide libraries.

Random glycosylation has proven remarkably effective for the generation of mixtures of oligosaccharides. Clearly, not all of the possible glycosidically-linked isomers are formed in equal quantity in these reactions. In the instances where product structures have been thoroughly investigated, however, all have been shown to be present. So far, only one random glycosylation step has been performed and the challenge will be to see if two tandem steps can generate a useful oligosaccharide library. Whether or not the present formulation of random glycosylation succeeds as a dominant strategy for the synthesis of oligosaccharide libraries, this important challenge is open to many approaches where creativity in both formulating the problem, as well as experimentally addressing it, warrants a major international effort.

Carbohydrate Sequence↗
PubMed1995

Post-herniorrhaphy pain in outpatients after pre-incision ilioinguinal-hypogastric nerve block during monitored anaesthesia care.

The objective of this study was to evaluate the effect of an ilioinguinal-hypogastric nerve block (IHNB) with bupivacaine 0.25% on the postoperative analgesic requirement and recovery profile in outpatients undergoing inguinal herniorrhaphy with local anaesthetic infiltration. Thirty consenting healthy men undergoing elective unilateral inguinal herniorrhaphy procedures were randomly assigned to receive an IHNB with either saline or bupivacaine according to a double-blind, IRB-approved protocol. All patients received midazolam, 2 mg iv, and fentanyl 25 microgram iv, prior to injection of 30 ml of either bupivacaine 0.25% or saline through the oblique muscle approximately 1.5 cm medial to the anterior superior iliac spine. Subsequently, the surgeon infiltrated the incision site with a lidocaine 1% solution. Sedation was maintained during the operation with a variable-rate propofol infusion, 25-140 micrograms.kg-1.min-1. No significant differences were noted in the intraoperative doses of lidocaine, propofol and fentanyl in the two treatment groups. However, the pain visual analogue score at 30 min after entering the PACU was lower in the bupivacaine (versus saline) group (P < 0.05). Although the times to ambulation (86 +/- 18 vs 99 +/- 27 min) and being judged "fit for discharge" (112 +/- 49 vs 126 +/- 30 min) were similar in the two groups, the bupivacaine-treated (vs saline) patients required less oral analgesic medication after discharge (46% vs 85%). We concluded that the use of an ilioinguinal-hypogastric nerve block with bupivacaine 0.25% as an adjuvant during inguinal herniorrhaphy under monitored anaesthesia care decreased pain in the PACU and oral analgesic requirements after discharge from the day-surgery unit.

Ambulatory Surgical Procedures↗
PubMed1995

Proteolytic enzymes as indicators of periodontal health in gingival crevicular fluid of patients with Sjögren's syndrome.

The present study characterizes the periodontal status of patients with Sjögren's syndrome (SS) and measures collagenase, elastase and gelatinase in gingival crevicular fluid (GCF) from these patients compared with adult individuals with periodontitis and healthy controls. The periodontal status was assessed by the Gingival Bleeding Index (GBI), the Visible Plaque Index (VPI), and pocket depth. Activity measurements were performed for collagenase with SDS-PAGE/laser densitometry, for elastase spectrophotometrically using a synthetic N-succinyl-Ala-Ala-Val p-nitroanilide peptide substrate, and for gelatinase with zymography. Seven of the 8 patients with SS and xerostomia showed a periodontium comparable to that seen in healthy controls. The GCF collagenase and elastase were significantly lower in patients with SS and in healthy controls than in patients with adult periodontitis. It was noteworthy that the one SS patient with periodontitis had high GCF collagenase and elastase activity. In all study groups multiple forms of gelatinases were present, indicating that they represent constitutively expressed proteinases involved in normal tissue remodeling processes. Our findings suggest that periodontal pockets/GCF form a micromilieu not affected by involvement of glandular tissue and, therefore, patients with SS show, clinically and biochemically, a periodontal status comparable to that seen in healthy controls.

Adult↗
PubMed1995

Modulation of host matrix metalloproteinases by bacterial virulence factors relevant in human periodontal diseases.

OBJECTIVE: Bacterial pathogens involved in periodontal diseases exert a part of their destructive effect by triggering and inducing host cells to elevate their secretion of matrix metalloproteinases (MMPs). Pathogen-secreted phospholipase (PLC) is one bacterial product that may trigger this host response. The roles of exogenous PLC leading to the release, secretion and expression of MMPs by peripheral blood neutrophils (PMNs), cultured epithelial cells of human gingiva and porcine periodontal ligament were investigated. Also the activities of PLC in the diseased and healthy gingival sulcular fluid (crevicular fluid, GCF) and molecular forms of gelatinases present in dental plaque were investigated. MATERIALS AND METHODS: GCF, salivary and dental plaque samples were analyzed for PLC and proteinase activities. The abilities of PLC to induce PMNs and oral epithelial cells to release and express their MMPs were examined by specific functional, immunological and molecular biology means. RESULTS: PMN-derived MMPs were found to predominate in periodontitis GCF and plaque, and PLC activities were higher in GCF of adult periodontitis patients than in healthy controls. Purified bacterial PLC (1 mU ml(-1)) efficiently induced PMN degranulation. PLC also induced MMP expression in the cultured epithelial cells. The strongest response was seen in MMP-9 and less in MMP-2. The induction was dose-dependent in the range of 0.0-1.0 U ml(-1) PI-PLC, and quiescent cultures were more responsive than proliferating ones. PLC induction of MMPs was polar, with increased levels of MMP-9 in the apical region and increased MMP-2 levels secreted in the basal direction. Northern analysis showed a strong increase in mRNA levels of MMP-9 and a smaller increase for MMP-2 and MMP-1. In the second part of the study we investigated the molecular forms of the released MMPs during periodontitis. In bacterial plaque of periodontitis patients the MMP-9 were found to be converted into lower molecular weight forms. Isolated proteinase from Porphyromonas gingivalis (ATCC 33277) was able to convert human proMMPs to their active forms. CONCLUSION: Bacterial PLC may induce degranulation of PMN MMPs and increase MMP expression in oral epithelial cells. The released proteases can be converted into active form by the proteases of plaque bacteria. Thereby, the pathogenic oral bacteria may indirectly participate in the destruction of periodontal tissues.

Adult↗
PubMed1995

CD3 and CD2 ligation alters CD49d epitope expression.

The combination of anti-CD2 plus anti-CD3 monoclonal antibodies (mAbs) synergistically prolongs allograft survival and induces antigen-specific tolerance. Since altered expression of cell surface molecules might be important for tolerance induction, the effect of anti-CD2 and anti-CD3 mAbs on the expression of adhesion molecules was analyzed on splenic T cells with an in vitro model. The anti-CD2 mAb, 12-15, alone had no effect on the expression of integrin alpha 4-chain epitopes recognized by two anti-CD49d (VLA-4 alpha) mAbs, R1-2 and PS/2. The anti-CD3 mAb, 2C11, caused R1-2 epitope expression to decrease, while PS/2 epitope expression remained unchanged. The combination of anti-CD2 and anti-CD3 mAbs further decreased R1-2 epitope expression while preserving PS/2 epitope expression. The expression of integrin beta 1 and beta 7 chains, each of which form heterodimers with alpha 4 chains, also remained unchanged. Expression of other integrin, selectin, or immunoglobulin superfamily molecules (CD11a, CD18, CD44, CD45, CD48, CD54 and CD62L) were all significantly increased by anti-CD2 or anti-CD3 mAbs. Decreased R1-2 epitope expression was anti-CD3 dependent and specifically augmented by anti-CD2 mAb. CD2-regulated decreases in R1-2 epitope expression correlated with increased cAMP and could be prevented by addition of high doses of IL-2 but was not affected by the addition of other cytokines. R1-2 alpha 4 epitope expression could be specifically restored by the divalent cation Mn2+, which also increased functional binding to the VCAM-1 ligand. Significantly, the R1-2 but not the PS/2 mAb prolonged graft survival in a cardiac allograft model. These results show that anti-CD2 and anti-CD3 mAbs selectively decrease integrin alpha 4 chain epitope expression on T cells through conformational regulation. Decreased expression of a CD49d epitope is unique in comparison to the up-modulation of other T-cell adhesion receptors. These changes correlate with functional effects and provide an additional mechanistic explanation for the synergistic effect of anti-CD2 plus anti-CD3 in producing tolerance.

Animals↗
PubMed1995

Increased cAMP and cAMP-dependent protein kinase activity mediate anti-CD2 induced suppression of anti-CD3-driven interleukin-2 production and CD25 expression.

Anti-CD2 monoclonal antibody (mAb) can act synergistically with anti-CD3 to produce tolerance and diminish the anti-CD3-induced cytokine syndrome. Since interleukin(IL)-2 production and IL-2 receptor (IL-2R; CD25) expression are important determinants of CD3-driven T cell activation, the effects of anti-CD2 on anti-CD3-induced CD25 expression and IL-2 production were analyzed and related mechanistically to CD2-stimulated cAMP signaling with an in vitro model of T cell activation. The anti-CD2 mAb, 12-15, alone had no effect on splenic T cell CD25 expression and IL-2 production, while the anti-CD3 mAb, 145-2C11, caused significant increases in both CD25 expression and IL-2 production. The addition of anti-CD2 inhibited anti-CD3-induced increases in CD25 and IL-2. The inhibitory signal delivered by anti-CD2 was effective in many forms of T cell activation, since other stimuli which increased CD25, such as concanavalin A, phytohemagglutinin, and Staphylococcal enterotoxin B (SEB), could also be inhibited by anti-CD2. The inhibitory effect of anti-CD2 on CD25 could not be reversed by high doses of supplemental IL-2 added to the culture. Anti-CD2 increased cytoplasmic cAMP in a dose- and time-dependent manner. Reagents that increased cytoplasmic cAMP such as forskolin, cholera toxin, and 3'-isobutyl-1-methylxanthine could mimic the inhibitory effect of anti-CD2 on anti-CD3-driven CD25 expression. Anti-CD2 also increased the activity of cAMP-dependent protein kinase (PKA). H8, a PKA antagonist, blocked the inhibitory effect of anti-CD2 on CD25 expression, further confirming the role of PKA in CD2-induced negative signaling. The use of paired agonists to PKA demonstrated that a type I PKA was the preferential enzyme isoform stimulated by CD2 ligation. These findings show that increased cAMP and PKA activity mediate anti-CD2-induced suppression of anti-CD3-driven IL-2 production and CD25 expression, and provide mechanisms for anti-CD2-induced immunosuppression and inhibition of the cytokine syndrome associated with anti-CD3 treatment.

Animals↗
PubMed1995

Human neutrophil collagenase (MMP-8), identified in bronchiectasis BAL fluid, correlates with severity of disease.

Collagenases in bronchoalveolar lavage fluid (BALF) of patients with bronchiectasis and healthy subjects were characterized using specific functional and immunologic assays. The BAL fluid contained interstitial collagenase and collagenolytic proteinases of bacterial origin. Collagenase activities, obtained after organomercurial activation, correlated with the severity of bronchiectasis. In severe cases, collagenase activities were 3.5 x 10(-7) IU/L/48 h or 4.8 x 10(-6) IU/g/48 h (p < 0.01), in moderate ones 1.74 x 10(-7) IU/L/48 h or 3.35 x 10(-6) IU/g/48 h (p < 0.05), and in mild cases 0.32 x 10(-7) IU/L/48 h or 0.7 x 10(-6) IU/g/48 h (p < 0.05). The corresponding activities in healthy control subjects were 0.08 x 10(-7) IU/L/48 h or 0.13 x 10(-6) IU/g/48 h. The cellular origin of interstitial collagenase was assessed with doxycycline inhibition test utilizing the differential sensitivity of fibroblast-type collagenase/MMP-1 (IC50 = 280 microM) and neutrophil-type collagenase/MMP-8 (IC50 = 26 microM) to the anticollagenolytic, nonantimicrobial doxycycline action. Interstitial collagenase, contained in BALF, was totally inhibited by 100 microM of doxycycline. It can therefore be concluded that most of mammalian collagenase presented in inflamed fluid of bronchiectasis originated from neutrophils. The molecular forms of neutrophil-type collagenase/MMP-8 were confirmed and analyzed by Western-blot, which showed evidence of the proteolytic conversion of the latent 85-kD MMP-8 proenzyme species into active 65-kD molecular weight species. These findings strongly suggest involvement of proteolytic activation pathway of proMMP-8, especially in severe and moderate forms of bronchiectasis. Furthermore, collagenolytic proteases of bacterial origins may also participate in tissue destruction of the lung.

Adolescent↗
PubMed1995

[Predictive values for slow pathway modification of atrioventricular nodal reentrant tachycardia].

The predictive values of various ECG parameters for slow pathway modification were studied in 42 slow-fast AVNRT patients. The negative predictive values of a stable ECG, junctional rhythm, and slow pathway potential were as high as 94.8%, 94.9% and 84.9% respectively. But, their positive values were 29.4%, 15.1% and 23.9%. The possibility of success (PS) raised with increasing of width and peak number of A wave. When the width of A wave was > or = 80ms, PS was 50%. When the peak number of A wave was > 7, PS was 80%. A/V ratio varied from 0.14 to 1 in 93.2% of successful sites. When A/V ratio was 0.25, PS reached its peak value of 33.3%.

Adolescent↗
PubMed1995

[Serum anti-subtypical Klebsiella pneumoniae antibodies in ankylosing spondylitis].

This study was performed in order to probe the possible pathogenesis of Klebsiella pneumoniae (KP) in ankylosing spondylitis (AS). 34 anti-KP antibody positive serum samples, including 26 patients with AS, 5 patients with rheumatoid arthritis (RA) and 2 healthy individuals, were selected to detect anti-subtypical KP antibodies by using an immunoblotting technique. The results showed that the number of antigenic bands to KP on nitrocellulose membrane was higher in AS patients than in RA patients and healthy individuals. Patients with AS had common antibodies response to KP components weight 64,600 (80.7%), 48,200 (61.5%) and 36,000 (65.4%), patients with RA and healthy individuals had anti-36,000 (75%) and anti-30,000 (50%) antibodies. Human anti-HLA-B27 serum and rabbit antisera against KP-derived synthetic peptide containing the hexapeptide sequence shared by HLA-B27 were able to cross react with 64,600 and 48,200 KP components. Our findings suggest that KP might play a role in the pathogenesis of AS by molecular mimicry between it and HLA-B27.

Antibodies, Bacterial↗
PubMed1995

Yeast-prepro-alpha-factor-leader-region-directed synthesis and secretion of truncated human macrophage colony-stimulating factor in the silkworm Bombyx mori.

Human macrophage colony-stimulating factor (hM-CSF) cDNA joined to the leader region of the precursor of the yeast mating pheromone alpha-factor (MF alpha L) was expressed at high levels in BmN cells and in silkworm (Bombyx mori) larvae, using recombinant Bombyx mori nuclear polyhedrosis virus, as a vector. The biological activity of rhM-CSF detected in the haemolymph was 1 x 10(6) colony-formation units/ml, approximately half of the expression level directed by the native signal peptide of hM-CSF in silkworm larvae. The secreted rhM-CSF was purified to homogeneity. N-terminal analysis showed that the signal peptide had been removed, indicating that insect cells possess the enzymic activity necessary to cleave the pro-alpha-factor leader region from the fusion protein at the carboxy side of Lys-Arg dibasic residues, which is the cleavage site recognized by KEX2 endopeptidase in yeast cells.

Amino Acid Sequence↗
PubMed1995

[A simple method for estimating half-life of drugs obeying Michaelis-Menten elimination kinetics].

AIM: To establish a simple method for estimating half-life of drugs obeying Michaelis-Menten elimination kinetics. METHODS: A linear relationship is sketched between elimination half-life and drug concentration in blood that obey Michaelis-Menten elimination kinetics. A simple method is proposed to draw a regression line of blood drug concentration vs time after a single bolus intravenous injection. RESULTS & CONCLUSION: The elimination half-life can be read from the regression line. The method can also be used to estimate the time required for the plasma concentration of a drug to decrease any fraction.

Half-Life↗
PubMed1995

[Fetal fibronectin diagnosis of premature rupture of the amniotic membranes].

OBJECTIVE: To determine whether fetal fibronectin is a sensitive test for the detection of premature rupture of the amniotic membranes. METHODS: Fetal fibronectin by ABC immunoblotting methods were measured in samples of cervicovaginal secretion from 80 cases with ruptured amniotic membranes (study group) and 50 cases of term pregnancy (control group A). Plasma fetal fibronectin were examined in 30 cases of normal pregnancy (control group B). RESULTS: The detection rate of fetal fibronectin in the women with ruptured membranes was 95.0%, While 6% in normal pregnancy. CONCLUSIONS: Fetal fibronectin is a sensitive test for detection of present of amniotic fluid. It can be used for diagnosis of ruptured amniotic membranes.

Amniotic Fluid↗
PubMed1995

Human obesity does not segregate with the chromosomal regions of Prader-Willi, Bardet-Biedl, Cohen, Borjeson or Wilson-Turner syndromes.

Prader-Willi, Bardet-Biedl, Cohen, Borjeson and Wilson-Turner syndromes are genetic disorders characterized by obesity and other diverse abnormalities. These disorders have been mapped to their respective chromosomal regions, and we hypothesize that each region contains a gene or genes important in the regulation of body weight. We tested this hypothesis by genotyping sibling pairs (n = 207; 17 markers) from 44 families who were segregating an extreme obesity phenotype but were otherwise clinically normal. The number of alleles shared between siblings from these chromosomal regions did not correlate with similarity in body mass index (kg/m2). If genes in these regions contribute to non-syndromal obesity, the prevalence is low and the corresponding alleles are rare.

Adult↗