Biomedical subjects

S X Yang

Publications and source records attributed to S X Yang.

At least 37 records · Page 2Linked to original sources

PubMed1994

Triptolide suppresses T-lymphocyte proliferation by inhibiting interleukin-2 receptor expression, but spares interleukin-2 production and mRNA expression.

The purpose of this study was to elucidate the mechanism of action of triptolide on the T-lymphocyte-mediated immune response. Lymphocytes were incubated with a suboptimal dose of Con A or PHA in the presence or absence of varying doses of triptolide to assess the effect of triptolide on lymphocyte proliferation, interleukin-2 (IL-2) production and IL-2 receptor expression. Then, Con A or PHA induced T-blast cells were cultured with a sufficient dose of recombinant human IL-2 in the presence or absence of triptolide to evaluate the effect of triptolide on the interaction of IL-2 and IL-2 receptors. The effect of triptolide on the immune response in vivo was also investigated. The results of these studies clearly demonstrated that triptolide selectively inhibited the T-lymphocyte proliferative response to Con A and PHA, but had less effect on LPS-induced B-lymphocyte proliferation. Triptolide also suppressed the expression of IL-2 receptors on PHA induced T-blast cells, but did not alter the production of IL-2 by mouse splenic cells and human tonsil lymphocytes. Furthermore, the results also showed that triptolide at higher concentration had a slight inhibitory effect on the interaction of IL-2 and IL-2 receptors, and addition of exogenous IL-2 did not reverse the inhibiting action of triptolide on T-cell proliferation. Taken together, these results suggest that triptolide inhibits T-lymphocyte proliferation mainly by affecting IL-2 receptor expression rather than IL-2 production.

Animals↗

PubMed1994

Enhancement of interleukin-2 production and its mRNA expression by dihydroartemisinin.

Immunoregulatory properties of a novel antimalarial drug dihydroartemisinin (DHA) were investigated in vitro. DHA 0.5-5 mumol.L-1 enhanced the lymphocyte proliferation induced by Con A. Interleukin 2 (IL-2) production and its mRNA expression by both Con A-stimulated mouse splenocytes and a T cell line LBRM-33-1A5 were also augmented by DHA. In contrast, DHA 0.5-5 mumol.L-1 did not show any effect on the lipopolysaccharides (LPS)-induced lymphocyte proliferation and the spontaneous and mitogen-induced proliferation of transformed T cells. These results indicated that DHA might regulate lymphocyte responses through the induction of IL-2 production and that the enhanced T cell proliferation and IL-2 production might be mediated through different pathways.

Animals↗

PubMed1994

[Application of microsurgical technique in the intrasinus renalis pyeloureteroplasty in pelvic atresia in children].

Seven cases of pelvic atresia in children were treated by the intrasinus renalis pyeloureteroplasty with the application of microsurgical technique. The site of pelviureteric anastomosis was unobstructed and the hydronephrosis was greatly improved through postoperative examinations of intravenous urography and renogram. This procedure provides clear field, simple performance and high successful rate. The prevention of complete pelviureteric laceration and pelvic atresia in children, the advantages of the microsurgical technique, and the operation precautions are discussed.

Adolescent↗

PubMed1993

Thyroglobulin glycosylation: location and nature of the N-linked oligosaccharide units in bovine thyroglobulin.

The cDNA sequence of bovine thyroglobulin (bTg) predicts 14 putative N-linked glycosylation sites. We have characterized the glycopeptides contained in a tryptic digest of bovine thyroglobulin in order to establish actual glycosylation sites. The distribution of oligosaccharide types within the known sites of N-linked glycosylation has also been examined. Each glycopeptide was subjected to neutral and amino sugar analysis, as well as sialic acid analysis. Thirteen of the 14 putative N-linked glycosylation sites in bTg were confirmed as glycopeptides in the mature protein. Nine of these confirmed glycosylation sites appear to bear complex or hybrid type oligosaccharide units and four contain oligosaccharide structures in which only mannose and glucosamine were seen. Complex or hybrid type glycosylation was confirmed at asparagine residues 91, 464, 476, 834, 928, 1121, 1757, 1851, and 2232, while oligosaccharides containing only mannose and glucosamine were found at asparagine residues 1346, 1995, 2104, and 2277. Analysis of the amino acid sequence in the region of each putative glycosylation site predicts a high probability of a beta turn at 10 of the 13 sites. While glycosylation was distributed through most of the length of the thyroglobulin sequence, no oligosaccharides containing only mannose and glucosamine were found in the N-terminal half of the molecule. Several of the glycosylated peptides showed microheterogeneity and occurred in two or more discrete peaks on HPLC. A single putative site at asparagine residue 179 was not recovered in the purified glycopeptide population.

Amino Acid Sequence↗

PubMed1993

Artemisinin and its derivatives enhance T lymphocyte-mediated immune responses in normal mice and accelerate immunoreconstitution of mice with syngeneic bone marrow transplantation.

Artemisinin and its derivatives, dihydroartemisinin and sodium artesunate, enhanced DNA synthesis of mouse spleen cells that had been activated with alloantigens or T cell mitogen Con A, but not B cell mitogen LPS, both in vitro and ex vivo. In vivo experiments showed that DTH response and antibody response against sheep erythrocytes were augmented in sodium artesunate-treated animals. In addition, sodium artesunate, a representative of these compounds, increased IL-2 production from mouse splenocytes stimulated with Con A. Because of the long-term T cell function deficiency in mice after bone marrow transplantation, the effect of sodium artesunate on the immune reconstitution was assessed. The results demonstrated that 10 mg/kg sodium artesunate significantly accelerated the immune reconstitution in mice after syngeneic bone marrow transplantation. These data suggested that artemisinin and its derivatives appeared to promote T cell function selectively, and these compounds had a potential application for the recovery of immune function.

Adjuvants, Immunologic↗

PubMed1993

The setting of an occupational exposure limit for phosphamidon in the workplace--a Chinese approach.

This paper describes the approach of setting an occupational exposure limit for phosphamidon, an organophosphorus pesticide, in the workplace in China. Apart from a general review of the literature relating to various toxicological studies, special emphasis has been placed on the results of a systematic occupational health survey on the workers exposed to phosphamidon. As a result of the survey, together with the literature review, a 'maximum allowable concentration' (MAC) for phosphamidon in the air of workplace is suggested as 0.02 mg m-3 but on the condition that the route of skin entry be blocked effectively. In addition, based on the description of the standard-setting process in China, a comparison has been made to the current U.K. approach.

China↗

PubMed1993

[Comparison of lipoperoxidative damage in plasma and platelet with the ratio of thromboxane A2 and prostaglandin I2 in blood stasis syndrome with coronary heart disease].

In order to study the biochemical and pathophysiological mechanism of the Blood Stasis Syndrome (BSS) or Non-BSS of coronary heart disease (CHD) patients, the activities of SOD, Selenium-glutathione peroxidase, the content of LPO in plasma and platelets and the contents of TXB2 and 6-keto-PGF1 alpha in plasma were determined in 109 BSS and Non-BSS of CHD patients compared with 98 healthy controls. It was discovered that the contents of TXB2, LPO, PL-LPO, and the ratio of TXB2/6-keto-PGF1 alpha were significantly increased in BSS-CHD patients compared with controls and Non-BSS-CHD patients. It was also discovered that the SOD activities and the contents of 6-keto-PGF1 alpha decreased significantly in Non-BSS-CHD patients. The results suggested that the injury of platelets by oxygen free radicals might be one of the primary injury factors in BSS-CHD patients. Our conclusion is that PGI2, SOD belong to the category of Heart-Qi, while TXA2, LPO to the Blood category. Therefore TXB2, 6-keto-PGF1 alpha, SOD, LPO should serve as some of the objective indexes for BSS patients of CHD.

6-Ketoprostaglandin F1 alpha↗

PubMed1993

[Experimental study on kidney invigorating and lipid reducing decoction-yishen jiangzhi tang in the treatment of chronic renal failure].

In exploring the effect of treatment of supporting the body resistance on chronic renal failure, a chronic renal failure model of rat was created by gastroperfusion of adenine and evaluation was made on the therapeutic effect of Kidney Invigorating and Lipid Reducing Decoction (KILRD). The mental state and body weight of the treated group have recovered well with polyuria and proteinurea improving, BUN and Creatinine decreasing, which appeared to be superior to the naturally recovered group. Renal pathological examination showed that: although the renal parenchymal damage was not reversed but its compensation was satisfactory with compensatory hypertrophy appearing in unaffected nephron. The dominant reaction in the affected area was polynucleomacrocytosis, foreign body granulamatosis, and interstitial lymphocytic infiltration, the fibrosis was inevident, while the above-mentioned condition in the naturally recovered group was relatively more serious, with fibrosis being observed. It was indicated that KILRD could increase the compensatory capacity and immunity, promote protein synthetization and improve renal function. The study on KILRD proved to be a significant conservative medical treatment for chronic renal failure.

Adenine↗

PubMed1992

Evidence for clonal expansion of T cell receptor V gamma II+ T cells in the synovial fluid of patients with arthritis.

We have demonstrated among synovial fluid T cells a unique profile of V gamma II sequences likely arising from clonally expanded T cells. We have determined the junctional diversity associated with each expressed V gamma family by resolving amplified fragments of cDNA into component parts on large denaturing gels. Among synovial fluid T cells we frequently find dominant fragments of a unique size clearly smaller than the dominant band observed with peripheral blood T lymphocytes. In some cases the dominant bands are 12 or 15 nucleotides smaller than the corresponding most abundant band from peripheral blood T lymphocytes. Patterns of lower m.w. species not typical of a polyclonal population argues that clones of T cells expressing the V gamma II family are expanding in the joint and that a high proportion of these cells do not express the V gamma IIJP sequence typical of peripheral blood but rather express V gamma II in combination with a shorter J fragment, JP1, JP2, J1, or J2. In addition by examining joint effusions from the left and right knees from the same individual we have shown that the profiles of V gamma II sequences derived from the fluids are identical to each other but clearly distinct from that of peripheral blood. We have, in addition, quantitated with a series of synthetic internal standards the relative usage of each V gamma family expressed by T cells in the synovial fluid and peripheral blood of seven patients with arthritis including six patients who were either children or adolescents and one adult patient. All patients showed a reduction in the relative expression of V gamma II in synovial T cells relative to peripheral blood T lymphocytes and a corresponding increase in the expression of V gamma I or V gamma III or both. We did not detect expression of V gamma IV in either lymphocyte population.

Arthritis↗

PubMed1992

Thyroid peroxidase glycosylation: the location and nature of the N-linked oligosaccharide units in porcine thyroid peroxidase.

Highly purified, trypsin/detergent-solubilized thyroid peroxidase (TPO), prepared from pig thyroid tissue, was subjected to reduction and alkylation followed by trypsin digestion. The resulting peptides were fractionated using HPLC. Corresponding carbohydrate positive regions from three separate HPLC experiments were pooled and further chromatography was carried out to yield purified peptide suitable for sequence analysis and complete carbohydrate composition analysis. Four of the five putative sites for N-linked glycosylation were found to carry oligosaccharide units in which mannose and glucosamine were the sole or predominant sugars. Three of the four glycosylations occur at asparagine residues which are likely to be at beta turns or bends. The fifth putative glycosylation site could not be confirmed and may either be poorly glycosylated or escape glycosylation. All of the confirmed glycosylated sites occur in the N-terminal third of the TPO polypeptide chain, in the portion of the molecule believed to be extracellular. The isolation of at least two chromatographic forms of glycopeptide derived from each of the confirmed sites suggests microheterogeneity in the structure of the oligosaccharide units of thyroid peroxidase similar to that observed in many other glycoproteins.

Amino Acid Sequence↗

PubMed1992

Immunosuppression of triptolide and its effect on skin allograft survival.

In this study the immunosuppressive properties of triptolide were evaluated. Triptolide was found to inhibit skin allograft rejection in a dose-dependent manner. This inhibitory effect was time dependent. Triptolide at 0.1 mg/kg/day significantly prolonged the graft survival when triptolide was given for 9 days after transplantation, but not before transplantation. In vitro studies showed that triptolide markedly suppressed cytotoxic T-lymphocyte (CTL) induction and mixed lymphocyte reaction (MLR) at concentrations ranging from 0.08 to 10 ng/ml. The inhibition on MLR was also significant when triptolide was added to the cultures at 36 h after initial incubation. Furthermore, exogenous IL-2 did not reverse this inhibitory effect of triptolide. Our results suggest that triptolide inhibits lymphocyte activation at a relatively late stage, and its effect on immune response is not exerted through altering IL-2 production.

Animals↗

PubMed1992

T cell receptor V beta usage in synovial fluid of children with arthritis.

We have examined synovial fluid (SF) T cells from 5 children with various types of juvenile arthritis. Using the polymerase chain reaction (PCR) to determine the expression of 20 individual T cell receptor (TCR) beta variable (V) region families, we have shown with each patient that the SF T cells are polyclonal. Nevertheless, expanded usage of some families by SF T cells relative to peripheral blood T cells was evident in some cases. We conclude that the pattern of T lymphocytes in the inflamed joint may be a consequence in part of a polyclonal expansion or nonspecific homing of T cells to the joint, and in part a more restricted expansion of T cells potentially driven by arthritogenic antigens.

Antibodies, Antinuclear↗

PubMed1992

Influence of methionine-enkephalin on interleukin-2 production and interleukin-2 receptor expression.

Influences of methionine enkephalin (met-enk) on delayed hypersensitivity (DH) against 2,4-dinitrofluoro-benzene (DNFB) and interleukin-2 (IL-2) production of mouse lymphocytes were examined. Met-enk enhanced the DH response to ear challenge when mice were treated with met-enk beginning at the same time as cpicutaneous sensitization with DNFB but not after being sensitized. When met-enk (10 nmol.L-1-100 mumol.L-1) was included in Con A-stimulated lymphocyte cultures, the IL-2 production increased in a concentration-dependent manner. Furthermore, in vivo treatment with met-enk also increased IL-2 production of splenocytes, and the enhancement of IL-2 production was parallel to that of lymphocyte proliferation. However, met-enk 10 nmol.L-1 had no effect on IL-2 receptor expression on thymocytes, splenocytes, and gut-associated lymphocytes. The data suggested that the stimulative effect of met-enk on lymphocytes may be mediated through the increase of IL-2, but not through the IL-2 receptor expression.

Animals↗

PubMed1991

Determination of trace iodine in food and biological samples by cathodic stripping voltammetry.

This paper describes a sensitive and selective method for the determination of iodine in food and biological samples. The method involves treatment of samples by combustion in an oxygen flask and determination of iodide by cathodic stripping voltammetry of the solid phase formed with the quaternary ammonium salt Zephiramine as the ionic associating agent; Br- is used as the complexing agent in the preconcentration process. We have studied the effect of concentration of Zephiramine, Br-, I-, and some other elements presented, deposition potential, preelectrolysis time, and scan rate, on the stripping curve shape and maximum stripping current. Determinations of trace iodine in table salt, laver, and eggs were demonstrated as practical examples.

Eggs↗

PubMed1990

[Rate of G gamma and A gamma chains in Dong ethnic newborns and gene mapping of a case with high G gamma value].

The G gamma to A gamma ratio of fetal hemoglobin in 120 cord blood samples of Dong ethnic newborns distributed over the Dong Autonomous Regions in Guangxi and Hunan provinces were determined with the method of polyacrylamide gel electrophoresis. The result showed that a case has the high G gamma value of 81.4% while 119 babies have the normal G gamma values of 56 to 76% (69.4 +/- 3.1%). The high G gamma case was identified as G gamma-AG gamma-A gamma/G gamma-A gamma genotype.

Asian People↗

PubMed1990

Immune enhancement of a polysaccharides peptides isolated from Coriolus versicolor.

A protein-bound polysaccharides (PSP) isolated from Coriolus versicolor in Shanghai, at the concentrations of 100-800 micrograms/ml promoted lymphocyte proliferation. PSP 25 mg/kg ip into mice for 5 d antagonized the inhibition of IL-2 production by cyclophosphamide from activated T lymphocytes and restored the suppressed T-cell-mediated delayed, type hypersensitivity response to normal. PSP 10-1000 micrograms/ml induced interferon alpha and gamma production from human peripheral leukocytes 4 and 8 times respectively higher than that of the control groups. Moreover, PSP also increased phagocytic functions of host reticulo-endothelial system. The results suggest that the anti-tumor effects of PSP may be related to its potentiation of host immunological responses.

Animals↗

PubMed1990

Enhancement of T lymphocyte proliferation and suppression of antibody producing cell formation by methionine-enkephalin.

Methionine-enkephalin (met-enk) 0.1-100 nmol/L significantly enhanced lymphocyte proliferation induced by T cell mitogens. On the other hand, the peptide markedly inhibited splenocyte blastogenesis induced by B cell mitogen lipopolysaccharides (LPS) and sheep red blood cell (SRBC)-driven plaque-forming cell (PFC) formation in vitro. Met-enk alone had no effect on immune responses. However, naloxone 50 nmol/L had also a stimulating effect on Con A-induced splenocyte proliferation. The similar results were also observed in vivo. The results also indicated that the enhancement of T cell function by met-enk was stronger in immunosuppressed mice than in the normal mice.

Animals↗

PubMed1989

Enhancement of interleukin-1 production in mouse peritoneal macrophages by methionine-enkephalin.

Methionine-enkephalin, an endogenous opioid, has been reported to have some effects on immune responses. By thymocyte proliferation method, we herein report that methionine-enkephalin over a wide range of concentrations (1 pmol-0.1 mumol/L) significantly increases both extracellular interleukin-1 release and intracellular interleukin-1 production from peritoneal macrophages induced by lipopolysaccharide in mice. Naloxone, having no effect per se on interleukin-1 production, does not block the enhancing effect of the neuropeptide. Interleukin-1 production was also elevated following ip methionine-enkephalin into mice. The results suggest that methionine-enkephalin mediates the enhancement of interleukin-1 synthesis and release as well, and that the effect is not mediated through classical opioid receptors. The results also provide the further links between immune and nervous systems.

Animals↗