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Biomedical subjects

C Xia

Publications and source records attributed to C Xia.

At least 55 records · Page 3Linked to original sources
PubMed1998

[Preliminary studies on chemical constituents and pharmacological action of Eclipta prostrata L].

OBJECTIVE: To study the pharmacologically active components of Eclipta prostrata. METHOD: The components were extracted by alcohol and isolated by silica gel column and subjected to pharmacological screening. RESULT: Four compounds were isolated from E. prostrata, of which two were identified as stigmasterol and alpha-terthienyl. CONCLUSION: alpha-Terthienyl was isolated from the plant for the first time. The EtOAc part of alcoholic extraction exhibits significant hepatoprotective activity against carbon terachloride-induced liver injury in rats.

Alanine Transaminase↗
PubMed1998

HPLC analysis of quinolinic acid, a NAD biosynthesis intermediate, after fluorescence derivatization in an aqueous matrix.

Quinolinic acid (2,3-pyridine dicarboxylic acid), a biological intermediate in nicotinamide adenine dinucleotide (NAD) biosynthesis in microbes and mammals and a brain excitotoxin, is not fluorescent nor electrochemically active and its detection sensitivity by UV absorption is comparatively low. Quinolinic acid was successfully derivatized in water-based samples by monodansylcadaverine, a fluorescence tag, and analysed by high-performance liquid chromatography (HPLC). No extraction procedure was needed and quinolinic acid was activated by water-soluble carbodiimide and derivatized under mild conditions. As little as 3 pmol (500 pg) of quinolinic acid in 5 microliter of artificial cerebrospinal fluid sample volume could be derivatized and detected at a signal to noise ratio of 3:1. Thus, detection on a mass basis by HPLC after fluorescence derivatization is about 300 times as sensitive as direct determination of quinolinic acid by UV absorbance (500 pg vs 150 ng). A variety of activators, fluorescent tags and reaction solvents and conditions were tested but found to be less effective.

Cadaverine↗
PubMed1997

Accumulation of pro-apolipoprotein A-II in mouse senile amyloid fibrils.

Apolipoprotein A-II (apoA-II), the major apoprotein of serum high-density lipoprotein, is deposited as amyloid fibrils (AApoAII) in murine senile amyloidosis. We have identified and purified a more basic amyloid protein from old-mouse liver. N-terminal sequencing of the protein revealed that the pro-segment of five amino acid residues (Ala-Leu-Val-Lys-Arg) extended from the N-terminal glutamine residue of mature apoA-II protein. MS analysis revealed the deposit of intact pro-apoA-II protein (molecular mass 9319 Da). Antiserum was prepared for staining of the AApoAII amyloid deposition. The relative abundance of pro-apoA-II to mature apoA-II in the amyloid-fibril fraction isolated from livers of mice with severe amyloidosis was 14.1%. The similar abundance of pro-apoA-II in the amyloid fibril fraction from the spleen (16.3%) suggested that deposited pro-apoA-II originated from the blood. The concentration of pro-apoA-II was much lower in the serum (1.5% of mature apoA-II) than in the amyloid-fibril fraction. There was no difference in the content of pro-apoA-II between the amyloidogenetic R1.P1-Apoa2c and amyloid-resistant SAMR1 strains at the age of 3 months. The abundance of pro-apoA-II in the amyloid-fibril fraction compared with the serum suggested that it plays a key role in the initialization of mouse senile amyloidosis.

Amino Acid Sequence↗
PubMed1997

Cross-talk between transcription factors NF-kappa B and C/EBP in the transcriptional regulation of genes.

The study of the acute phase response has attracted substantial interest, not only for its medical implication, but also its provision as an excellent system with which to elucidate the molecular mechanisms involved in the modulation of gene expression. Our previous data suggest that the synergistic induction of the major acute phase reactant serum amyloid A2 (SAA2) expression by interleukin-1 (IL-1) and interleukin-6 (IL-6) is mediated by two families of transcription factors, namely NF-kappa B and C/EBP. To understand the molecular mechanisms of this synergy, we have undertaken a molecular dissection of the factors involved in the formation of the regulatory complex. Electrophoretic mobility shift analysis indicates that NF-kappa B p65 (RelA) and p50, but not p52 or c-Rel, bind specifically to the NF-kappa B site of the SAA2 promoter in response to IL-1 stimulation. In addition, C/EBP beta and C/EBP delta, but not C/EBP alpha, bind specifically to the C/EBP site of SAA2 in response to IL-6 stimulation. Transient co-transfection analysis indicates that co-operative association of NF-kappa B p65 with C/EBP beta and, in particular, with C/EBP delta, results in synergistic transcriptional activation of the SAA2 promoter. When incubated together, NF-kappa B p65 and C/EBP beta form a ternary complex by direct protein/protein interaction. Mutational analysis demonstrates that the C-terminus region of the Rel homology domain (RHD) and the C-terminus of the activation domain of p65 are important for its interaction with C/EBP beta. These results suggest the NF-kappa B and C/EBP may form a new complex of transcription factors that mediates the synergistic induction of SAA2 by IL-1 and IL-6.

Acute-Phase Reaction↗
PubMed1997

[Detection of Epstein-Barr virus in lymphoproliferative diseases by in situ hybridization].

OBJECTIVE: To study the relationship between Epstein-Barr virus and various lymphoproliferative diseases in China. METHODS: Tissues from 214 patients with lymphoproliferative diseases were examined for the presence of Epstein-Barr virus (EBV) using in situ hybridization with EBV's LMP gene as probe. RESULTS: The positive rate of EBV in Hodgkin's disease(HD), Non-Hodgkin's Lymphoma(NHL), benign lymphoid proliferative disease(BLP) was 30.0%(15/50), 14.0%(18/129), 2.9%(1/35), respectively. Among NHL, EBV was detected in 28.1%(9/32) of high grade lymphoma (HNHL), 10.5%(9/84) of medium grade lymphoma(MNHL) and in none(0/9) of low grade lymphoma(LNHL). Significantly higher rates than that of BLP were observed in HD and HNHL. No significant differences in rates among patients with MNHL, LNHL and BLP. CONCLUSION: EBV may be involved in the pathogenesis of HD and HNHL, but not in MNHL and LNHL.

Adult↗
PubMed1997

[HLA-DR-positive T lymphocytes in the bone marrow and peripheral blood of patients with severe aplastic anemia and their in vitro inhibitory effecton BFU-E and CFU-GM].

OBJECTIVE: [corrected] To elucidate the role of immunodysfunction in the pathogenesis of severe aplastic anemia (SAA). METHODS: HLA-DR+ T cells were detected in bone marrow (BM) and peripheral blood (PB) of 20 SAA patients and controls (9 for BM and 11 for PB). PHA-LYCM conditioned medium was prepared, and its in vitro effect on normal bone marrow BFU-E and CFU-GM was studied. RESULTS: The percentages of HLA-DR+ T lymphocytes in BM and PB of newly diagnosed SAA patients were significantly higher than that of controls (P<0.001), and that of recovered SAA (rSAA) patients after ALG therapy (P<0.05). Compared with controls, the PBA-LYCMs from newly diagnosed SAA patients showed significant inhibitory effect on normal BFU-E and CFU-GM (P<0.001). CONCLUSION: The activated T lymphocyte may play an important role in the pathogenesis of SAA.

Adolescent↗
PubMed1997

[Colony formation of bone marrow hematopoietic progenitor cells in patients with severe aplastic anemia and its relation to the results of immunosuppressive therapy].

OBJECTIVE: To explore the defect of hematopoietic stem cell and analyze the relationship between the colony formation capacity of bone marrow hematopoietic progenitor cells and the results of immunosuppressive therapy (IST) in severe aplastic anemia (SAA) patients. METHODS: Methylcellulose semisolid culture was used. RESULTS: Thirty patients with SAA at diagnosis were studied. In 90% of the patients, the CFU-E and CFU-GM yields were strikingly decreased and in 56.7% of the patients there was no colony formation at all. Nevertheless, there was still 10% of the patients having normal CFU-E, BFU-E or/ and CFU-GM yields. After IST, 59.1% of the patients showed colony formation improvement. The difference between the results obtained pre- and post-IST(for CFU-E and BFU-E, P < 0.01, for CFU-GM, P < 0.05) was significant. In the majority of the patients, the colony formation capacities were still under the normal post-IST. Moreover, 22.7% of the patients remained no colony formation post-IST. The IST response rates between the patients with or without colony formation had no statistically difference (80% versus 50%, P < 0.05). The increment of colony formation appeared later than the therapeutic effect did, but frequently concurred with the appearance of magkaryocytes in the bone marrow smear. CONCLUSION: In the majority of SAA patients, the hematopoietic stem cells or progenitors were defective perhaps caused by immune damage; IST can improve the hematopoiesis in vitro and in vivo of SAA patients.

Adolescent↗
PubMed1996

The organization of the human GSTP1-1 gene promoter and its response to retinoic acid and cellular redox status.

High levels of expression of GSTP1-1 are associated with cell proliferation, embryogenesis and malignancy. Given the role of glutathione S-transferase (GST) in detoxication, it is possible that GSTP1-1 evolved specifically to protect proliferating cells and share regulatory mechanisms with other cellular genes which are involved in cell division and tumorigenesis. We have previously shown that the expression of GSTP1 is suppressed by retinoic acid (RA) in the presence of the retinoic acid receptor (RAR) as a result of decreased transcription from its promoter. Through deletion analysis, we show here that the RA-RAR-dependent repression is mediated by the region -73 to +8. Further mutation analysis of this region indicates that the DNA sequence required for RA-RAR-dependent repression co-localizes with a consensus activator protein-1 (AP1) site essential for the promoter activity. The degree of repression correlates with the residual activity of the AP1 site. There are two adjacent G/C boxes. The one immediately downstream from the AP1 site is not essential for the promoter activity, but mutation of the second, further downstream, impairs the promoter. On the other hand, mutation of either of these two G/C boxes has little effect on RA-RAR suppression. We also show that the expression of GSTP1 is regulated by the redox status of the cell. Using the chloramphenicol acetyltransferase assay system, we have demonstrated that treatment with H2O2 induced transcription from the promoter and that this effect can be blocked by pre-incubation with N-acetylcysteine (NAC). It was shown that the induction by H2O2 is mediated by trans-acting factor NF-kappa B (nuclear factor kappa B), via a putative NF-kappa B site, 'GGGACCCTCC', located from -96 to -86. Co-transfection with an NF-kappa B (p65) expression construct increased the promoter activity, an effect which could be blocked by co-transfection with an I kappa B (MAD-3) expression construct. Deletion of the NF-kappa B site abolished the effect of both H2O2 and co-transfection of NF-kappa B. Interestingly, NAC is also an inducer for GSTP1. The effect of NAC was shown to be mediated largely by the AP1 site, since mutation of this site abolished the induction by NAC.

Base Sequence↗
PubMed1996

Expression of RANTES by human bronchial epithelial cells in vitro and in vivo and the effect of corticosteroids.

Recent studies have demonstrated that RANTES, a member of the CC chemokine family affecting monocytes, T cells, basophils, and eosinophils, is expressed by several cell types. To investigate whether human bronchial epithelial cells can also express this chemokine, we investigated human bronchial epithelial cells for their ability to synthesize RANTES, both in vitro and in vivo. Additionally, we investigated the effect of treatment for 4 mo with inhaled corticosteroids on the expression of RANTES in these cells in vivo. Human bronchial epithelial cells cultured from surgical tissue expressed the mRNA for RANTES and synthesized RANTES, as demonstrated by polymerase chain reaction and immunocytochemical staining and enzyme-linked immunosorbent assay, respectively. Incubation of the cultures with 50 ng/ml of tumor necrosis factor-alpha (TNF-alpha) significantly increased the release of RANTES into culture medium after 18 to 48 h of incubation, an effect that was abolished by treatment of the cultures with anti-TNF-alpha antibody. RANTES was also expressed in the bronchial epithelium in vivo, as indicated by positive immunocytochemical staining of bronchial biopsy tissues obtained from mild asthmatic patients before and after treatment with 500 micrograms of inhaled beclomethasone dipropionate (BDP) twice daily or matched placebo for 4 mo. Quantitation, by color image analysis, of the percentage of epithelium staining for RANTES showed that treatment with BDP decreased the expression of RANTES in the bronchial epithelium from 17.12% to 4.22% (P < 0.05). The numbers of EG2-staining cells in the epithelium were also reduced, from 790.1/mm2 to 203.3/mm2 (geometric mean; P < 0.01), after BDP treatment. These results suggest that human bronchial epithelial cells are capable of synthesizing RANTES and may therefore play an important role in the development of inflammation in allergic airways disease. Furthermore, corticosteroids may prevent airway inflammation by downregulating the expression of proinflammatory cytokines in the bronchial epithelium.

Administration, Inhalation↗
PubMed1996

Percutaneous transluminal balloon pulmonary valvuloplasty using domestic balloon catheter for congenital pulmonary valve stenosis in children.

OBJECTIVE: To estimate the effect of percutaneous balloon pulmonary valvuloplasty (PBPV) using domestic balloon catheter for congenital pulmonary valve stenosis (PVS) in infants and children. PATIENTS AND METHODS: The data of 70 patients aged from 1.5 to 12 years (mean 5.5 +/- 3.4 years) who underwent PBPV using domestic balloon catheter for PVS in our institution were reviewed. Sixty-six patients had dome-shaped valve stenosis, and 4 had displastic valve stenosis. SaO2 reduced in 5 patients and associated open foramen ovale was noted in 23. Predilatation, right ventricular systolic pressure ranged from 60 to 234 mmHg (mean 115.75 +/- 36.15 mmHg). The systolic gradient (delta P) from right ventricle to pulmonary artery was 89.92 +/- 38.25 mmHg. Balloon diameter was selected 120%-142% of pulmonary valve annulus diameter (mean 132%). All patients were followed up for 3 months-4 years by means of clinical examination. ECG, 2D-UCG, and Doppler-UCG. RESULTS: After dilatation, delta P reduced from 89.92 +/- 38.25 to 14.65 +/- 11.40 mmHg (P < 0.001). The rate of decrease in transvalve gradient (delta P) was 83.7%. No patients experienced procedure-related events. Mid-term follow-up showed that no patients had clinical and instrumental complications. Doppler and ECG analyses showed that delta P did not change significantly similar to immediate gradient after PBPV and right ventricular hypertrophy disappeared progressively 6 months after PBPV. CONCLUSIONS: PBPV is a useful, safe and definitive procedure in the treatment of isolated PVS in infants and children. The properties and features of the balloon catheter produced by Shanghai Med-Tech Factory are similar to those of Med-Tech balloon catheter of U.S.A.

Catheterization↗
PubMed1995

Myasthenia gravis-like syndrome induced by expression of interferon gamma in the neuromuscular junction.

Abnormal humoral responses toward motor end plate constituents in muscle induce myasthenia gravis (MG). To study the etiology of this disease, and whether it could be induced by host defense molecules, we examined the consequences of interferon (IFN) gamma production within the neuromuscular junction of transgenic mice. The transgenic mice exhibited gradually increasing muscular weakness, flaccid paralysis, and functional disruption of the neuromuscular junction that was reversed after administration of an inhibitor of acetylcholinesterase, features which are strikingly similar to human MG. Furthermore, histological examination revealed infiltration of mononuclear cells and autoantibody deposition at motor end plates. Immunoprecipitation analysis indicated that a previously unidentified 87-kD target antigen was recognized by sera from transgenic mice and also by sera from the majority of human MG patients studied. These results suggest that expression of IFN-gamma at motor end plates provokes an autoimmune humoral response, similar to human MG, thus linking the expression of this factor with development of this disease.

Animals↗
PubMed1995

Expression of transmembrane-type protein tyrosine phosphatase mRNA along rat nephron segments.

Protein phosphorylation on tyrosine residues is one of the main cell signaling mechanisms. Cellular phosphotyrosyl levels are regulated by the activities of protein tyrosine kinases (PTK) and protein tyrosine phosphatases (PTPase). We have previously reported cDNA cloning of several types of PTPase from rat kidney, including LRP (leukocyte common antigen-related protein; also known as the transmembrane-type tyrosine phosphatase, i.e., RPTP alpha). LRP mRNA was shown to be abundant in the kidney; however, our understanding of the functional role of LRP in the kidney is very limited. To gain keener insight into the function of LRP in the kidney, our first approach was to reveal its mRNA distribution along rat nephron segments. Large signals were found in inner medulla by Northern blot analysis. By using a reverse transcription and polymerase chain reaction assay of individual microdissected tubule segments along the nephron [proximal convoluted tubule (PCT), medullary thick ascending limb (MTAL), cortical collecting duct (CCD), outer medullary collecting duct (OMCD), and inner medullary collecting duct (IMCD)] and glomeruli, we revealed intrarenal localization of LRP mRNA. LRP mRNA was detected in all nephron segments tested but was relatively rich in the IMCD. Rank order of the signal intensity was IMCD > PCT = OMCD > CCD > MTAL = glomeruli. Immunohistochemistry also revealed that LRP was abundant in IMCD. This pattern of expression gives rise to an interesting possibility that LRP might be involved in the specific renal tubule function, such as urinary concentrating mechanism; however, further study is required to describe the function of LRP in more detail.

Amino Acid Sequence↗
PubMed1995

Angiotensin II stimulates interleukin-6 release from cultured mouse mesangial cells.

Interleukin-6 (IL-6) is a multifunctional cytokine exerting a wide variety of biologic responses, including cell proliferation. Recently, IL-6 has been known to play a role in the pathogenesis of mesangial proliferative glomerulonephritis. IL-6 is now recognized as an autocrine growth factor for glomerular mesangial cells, and various inflammatory mediators have been shown to promote IL-6 release from mesangial cells. However, little is known about the noninflammatory stimuli of IL-6 release from mesangial cells. In this study, it was hypothesized that angiotensin II (AngII) is one of the noninflammatory mediators of IL-6 release in mesangial cells, and the effects of AngII on IL-6 release and mRNA expression in cultured mouse mesangial cells (CMMC) were investigated. It was demonstrated that AngII (10(-7) M or higher) caused IL-6 release and mRNA accumulation in CMMC. IL-6 release was detected at 4 h and reached a plateau at 8 h after the addition of AngII, whereas IL-6 mRNA expression peaked at 4 h. The effects of AngII on IL-6 release and gene expression were completely blocked by the AngII receptor type 1 (AT1 receptor) antagonist CV-11974. AngII and IL-6 were both shown to stimulate DNA synthesis in CMMC, and the blockade of IL-6 signaling with anti-IL-6 receptor antibody abolished the enhanced DNA synthesis induced by AngII. These results raise a possibility that the growth-promoting effect of AngII on mesangial cells is at least partially mediated by IL-6 released from mesangial cells.

Angiotensin II↗
PubMed1995

[Effects of Sichuan herba Epimedii on the concentration of plasma middle molecular substances and sulfhydryl group of "yang-deficiency" model animal].

The effects of tonifying the kidney and strengthening the "Yang" produced by the extracts of Chinese herbs Epimedium wushanense and E. pubescens were studied in this paper. The results showed that both two herbs could decrease the concentration of plasma middle molecular substances and increase the concentration of plasma sulfhydryl group of "Yang-deficiency" model mice, thus suggesting that the above-said tonifying and strengthening effects of Herba Epimedii may result from its effects on middle molecular substances and sulfhydryl group, so as to strengthen the body resistance and eliminate the invading pathogenic factors.

Animals↗
PubMed1995

[Influence of acupuncture on blood pressure, contents of NE, DA and 5-HT of SHR and the interrelation between blood pressure and whole blood viscosity].

Twenty spontaneous hypertensive rats (SHR) with systolic blood pressure (SBP) >or= 20 kPa were chosen and divided randomly into two groups (acupuncture group and control group). The former was acupunctured on bilateral Quchi (L1 11), Zusanli (ST 36). Another 46 immature SHRs which were about 7-week-old with SBP ranged from 16 kPa to 20 kPa were given 10% high molecular weight dextran (HMWD) or normal saline by intervention respectively. The results showed: 1. After three course of acupuncture, SHRs' SBP dropped remarkably from 25.493 +/- 0.73 kPa to 19.547 +/- 0.555 kPa (P < 0.01); 2. After three courses of acupuncture, NE and 5-HT contents in plasma were lowered (P < 0.05, < 0.01) and DA content in plasma was increased (P < 0.05) compared with that in the control group. 3. After three course of acupuncture, NE content in brainstem, hypothalamus, cerebral cortex increased (P < 0.005-0.01) and DA content in brainstem, cerebral cortex increased remarkably (P < 0.005-0.01) compared with that in the control group. 5-HT content in brainstem, hypothalamus, and cerebral cortex increased obviously compared with that in the control group. 4. After 1 or 2 hours of intervention of 10% HMWD to immature SHR, the whole blood viscosity and blood pressure rise remarkably compared with normal saline group. The experiment implies that the mechanism of lowering the blood pressure of SHR by acupuncture lies in that it can adjust NE, DA and 5-HT contents in plasma and central nervous system to adjust the activity of sympathetic, reduce whole blood viscosity etc.

Animals↗
PubMed1994

cDNA cloning of a cytosolic protein tyrosine phosphatase (RKPTP) from rat kidney.

A rat cDNA encoding a non-receptor type phosphotyrosine phosphatase (PTPase; EC 3.1.3.48) was identified. The 1608 bp cDNA contains a single open reading frame that predicts a 382 amino acid protein with M(r) 44,438. The predicted protein has no apparent signal or transmembrane sequences, suggesting that it is a cytosolic protein. The C-terminal region has a PTPase catalytic domain that has 40-50% nucleic acid homology to other known PTPases. The N-terminal region has little amino acid sequence homology to any other known sequences. The recombinant protein of the cloned cDNA expressed in Escherichia coli was shown to possess PTPase activity using myelin basic protein, tyrosine phosphorylated by p43v-abl tyrosine kinase, as a substrate.

Amino Acid Sequence↗
PubMed1993

Unusual reactivity of Tyr-7 of GSH transferase P1-1.

Reaction of human GSH transferase P1-1 (GSTP1-1) with diethylpyrocarbonate (DEPC) at pH 7.0 and 4 degrees C resulted in covalent modification of an equivalent of one histidine and one tyrosine residue per subunit, with loss of activity. Sequence analysis showed that His-71 and Tyr-7 were modified. Reference to the three-dimensional structure of GSTP1-1 [Reinemer, Dirr, Ladenstein, Huber, Lo Bello, Frederici and Parker (1992) J. Mol. Biol. 227, 214-226] shows that the modification of Tyr-7 is most likely to affect enzyme activity. Kinetic analysis of the DEPC modification of Tyr-7 in GSTP1-1 gave a k2 approx. 150 times that of a peptide comprising residues 1-11 of GSTP1-1. The reaction of Tyr-7 of GSTP1-1 with DEPC was poorly inhibited by 1 mM GSH (14%) or 10 microM S-hexylglutathione (18%). DEPC treatment of the enzyme altered the absorbance at 290 nm in second-derivative spectra, suggesting that a significant amount of tyrosinate ion occurs in the enzyme. GSH, however, did not significantly alter the A290. The data provide the first evidence of unusual chemical reactivity of Tyr-7 and are consistent with its proposed role as a proton acceptor during catalysis.

Diethyl Pyrocarbonate↗