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Biomedical subjects

S Xu

Publications and source records attributed to S Xu.

At least 253 records · Page 14Linked to original sources
PubMed1999

[Investigating the phenomenon of total erythrocyte destruction during an in-vitro hemolysis test by roller pump].

This study sought to address the question, "will the phenomenon of 'total erythrocyte destruction' come about during a long time of in vitro hemolysis test by roller pump". One-day-old boving blood was employed in the test by Polystan pump(group A) and Cobe pump (group B). TMB method was used to measure the level of plasma-free hemoglobin. The samples of plasma-free hemoglobin were taken at the time before pumping and pumping for 4,6,8,10, 12,14 and 16 hours. The index of hemolysis was calculated according to Koller's formula. The results showed that the levels of plasma-free hemoglobin in the two groups both increased linearly during the puming of blood. The index of hemolysis was 0.2960 mg/L group A, and 0.3993 mg/L in group B; no statistically significant difference was noted between the two groups. These data indicated that no phenomenon of "total erythrocyte destruction" was observed in this hemolysis test by roller pump.

Erythrocytes↗
PubMed1999

[Analysis of physicochemical property and composition of fatty acid of almond oil].

Almond oil was extracted from almond and saponified with saturated KOH-methanol. The mixed fatty acids methylated by methanol-H2SO4(4:1, V/V). Methyl esters were extracted by ether and detected by gas chromatography. The major fatty acids in Taiyuan almond oil were found to be about 68% oleic acid (C18:1), 25% linoleic acid(C18:2), 4.6%-4.8% palmitic acid(C16:0) and a little of palmitoleic acid(C16:1), stearic acid(C18:0). A trace of arachidic acid(C20:0) was also found.

Chromatography, Gas↗
PubMed1999

[Effect of triclabendazole on the ultrastructure of body wall and vitelline cells of Paragonimus westermani].

AIM: To observe the ultrastructural changes in the body wall and the vitelline cells of Paragonimus westermani in vitro and in vivo before and after triclabendazole treatment. METHODS: The worms were obtained from in vitro and in vivo tests. All of the samples were processed by conventional techniques, and observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). RESULTS: The external plasma membrane and matrix were cracked or disappeared after the treatment. The necrosis of the muscular layer differed. The cell membranes of cortex and vitelline cells were damaged. Nuclear membrane was damaged partially, heterochromatin solidified and condensed to brim and dissolved. The Golgi complex disappeared, endoplasmic reticulum expanded, mitochodria denatured and dissolved. The damage was more serious in vivo than in vitro. CONCLUSION: Triclabendazole is remarkablely effective against Paragonimus westermani by damaging the body wall and vitelline cells, mainly affecting the nuclei, membrane structures and microtubular system.

Animals↗
PubMed1999

[Endoscopic pituitary tumor surgery by nasal cavity and sphenoid sinus].

OBJECTIVE: For reducing surgical trauma to patients of pituitary tumor. METHOD: 12 patients of pituitary tumor were treated with endoscopy by nasal cavity and sphenoid sinus under general anaesthesia. RESULT: Except one died of bleeding within cranial cavity after operation, the rest recovered smoothly without severe complications. During 7 months to one and half year follwing-up, the function of endocrine in 9 cases resumed to normal and 8 of their vision improved to some extent. CONCLUSION: The good illumination and clear visual field under endoscopy could improve the accuracy and security of operation and minimize the injury to normal tissue. But for large or recurrent tumors, this approach should be selected carfully.

Adult↗
PubMed1999

[Gastrointestinal inhibitory effects of sesquiterpene lactones from Atractylodes macrocephala].

Atractylenolide I (8,9-dehydroasterolide, B), 4,15-epoxy-8 beta-hydroxyasterolide (C) and atractylenolide III (8 beta-hydroasterolide, D) from Atractylodes macrocephala Koidz, 28.0, 56.0 mumol/L, inhibited the spontaneous movement of rat isolated ileum with contractile force decreased obviously (P < 0.001), but the rest force not affected (P > 0.05). B, C and D inhibited the spasm enhanced by Ach and His to rat ileum, rightly shifted the dose-response curves and reduced the maximal response (P < 0.05). Pretreatment with B, C or D 28.0, 56.0 mumol/L Ver 0.28 mumol/L significantly antagonized CaCl2-induced contraction of rat isolated ileum. Co bathing of B, C or D 56.0 mumol/L with Atr 0.19 mumol/L weakened the response of ileum to Ach. B, C or D 56.0 mumol/L restrained the spasm of ileum mediated by Neo 2.15 mumol/L. The modified Phenol Red Paste Model demonstrated that B, C or D in dose of 28.0 mg/kg inhibited the gastrointestinal prochoresis of mice significantly. These results suggested that B, C and D inhibit the gastrointestinal movement of rat and the spasm induced by the agonists. Their activities are related to the inhibition of cholinergic system and Ca2+.

Animals↗
PubMed1999

[Effects of abalong polysaccharide on the activity of the peritoneal macrophages and delayed-type hypersensitivity in mice bearing S180].

The effect of Abalone polysaccharide(Ap) which extracted from Haliotis discus hannai Ino on phagocytosis activity of the peritoneal macrophages and delayed-type hypersensitivity in mice bearing S180 were studied. The results showd that the ablong polysaccharide promoted the phagocytosis activity of the peritoneal macrophages and delayed-type hypersensitivity in mice bearing S180. It was suggested that the polysaccharide inhibited tumor growth maybe by activating the macrophage and T cells.

Animals↗
PubMed1999

[Effects of extract from Pegasus laternarius on the weight of immune organs and the antistress in mice].

Extract from Pegasus laternarius Cuvier (PLE) could increase the splenic and thymic weight in immunity-suppressed mice induced by hydrocortisone or cyclophosphamide and could increase the thymic weight in senile mice. PLE could prolonged the survival time of anoxic mice under normal pressure or chemically anoxic mice poisoned by potassium cyanide. It could also prolong the survival time of mice swimming in ice-water and enhance the tolerance of mice without food to eat and water to drink.

Adjuvants, Immunologic↗
PubMed1999

[Synergy and attenuation of cyclophosphamidum (CTX) activities by abalone polysaccharide].

Abalone polysaccharide (AP) was extracted from Haliotis discushannai Ino. The combined effects of AP and CTX against tumor-bearing mice were investigated. The results showed that AP could markedly promote the inhibition effects of CTX on S180 and HepA tumor, enhance protection against leukocytopenia, decrease of spleen and thymus weight and hemolysin in serum, and bone marrow supression induced by CTX.

Animals↗
PubMed1999

[The design of a reflection sensor of NIRS tissue oximetry].

A design of the reflection light-electric Sensor suited to monitoring the statues of tissue blood oxygen on the surface of body is described. The designed sensors have been used too to detect blood oxygen statues of brain and muscle respectively, and many useful informations have been acquired Therefore The above-mentioned design is reasonalle and Feasikle.

Algorithms↗
PubMed1999

[The application of modularity design in the pulse oximeter].

This paper presents a thought of modularity design and application in our pulse oximeter and its hardware and software composition of the function board, the application can improve the reliability of the instrument greatly and make it easy to expand its function.

Equipment Design↗
PubMed1998

RNA as a target of double-stranded RNA-mediated genetic interference in Caenorhabditis elegans.

Introduction of exogenous double-stranded RNA (dsRNA) into Caenorhabditis elegans has been shown to specifically and potently disrupt the activity of genes containing homologous sequences. In this study we present evidence that the primary interference effects of dsRNA are post-transcriptional. First, we examined the primary DNA sequence after dsRNA-mediated interference and found no evidence for alterations. Second, we found that dsRNA-mediated interference with the upstream gene in a polar operon had no effect on the activity of the downstream gene; this finding argues against an effect on initiation or elongation of transcription. Third, we observed by in situ hybridization that dsRNA-mediated interference produced a substantial, although not complete, reduction in accumulation of nascent transcripts in the nucleus, while cytoplasmic accumulation of transcripts was virtually eliminated. These results indicate that the endogenous mRNA is the target for interference and suggest a mechanism that degrades the targeted RNA before translation can occur. This mechanism is not dependent on the SMG system, an mRNA surveillance system in C. elegans responsible for targeting and destroying aberrant messages. We suggest a model of how dsRNA might function in a catalytic mechanism to target homologous mRNAs for degradation.

Animals↗
PubMed1998

The efficient cellular uptake of high density lipoprotein lipids via scavenger receptor class B type I requires not only receptor-mediated surface binding but also receptor-specific lipid transfer mediated by its extracellular domain.

The class B type I scavenger receptor, (SR-BI), is a member of the CD36 superfamily of proteins and is a physiologically relevant, high affinity cell surface high density lipoprotein (HDL) receptor that mediates selective lipid uptake. The mechanism of selective lipid uptake is fundamentally different from that of classic receptor-mediated uptake via coated pits and vesicles (e.g. the low density lipoprotein receptor pathway) in that it involves efficient transfer of the lipids, but not the outer shell proteins, from HDL to cells. The abilities of SR-BI and CD36, both of which are class B scavenger receptors, to bind HDL and mediate cellular uptake of HDL-associated lipid when transiently expressed in COS cells were examined. For these experiments, the binding of HDL to cells was assessed using either 125I- or Alexa (a fluorescent dye)-HDL in which the apolipoproteins on the surface of the HDL particles were covalently modified. Lipid transfer was measured using HDL noncovalently labeled by the fluorescent lipid 1,1'-dioctadecyl-3,3, 3',3'-tetramethylindocarbocyanine perchlorate. Although both mSR-BI and human CD36 (hCD36) could mediate the binding of HDL in a punctate pattern across the surfaces of cells, only mSR-BI efficiently mediated the transfer of lipid to the cells. Analysis of point mutants established that the major sites of fatty acylation of mSR-BI are Cys462 and Cys470 and that fatty acylation is not required for receptor clustering, HDL binding, or efficient lipid transfer. Generation of mSR-BI/hCD36 domain swap chimeras showed that the differences in lipid uptake activities between mSR-BI and hCD36 were not due to differences between their two sets of transmembrane and cytoplasmic domains but rather result from differences in their large extracellular loop domains. These results show that high affinity binding to a cell surface receptor is not sufficient to ensure efficient cellular lipid uptake from HDL. Thus, SR-BI-mediated binding combined with SR-BI-dependent facilitated transfer of lipid from the HDL particle to the cell appears to be the most likely mechanism for the bulk of the selective uptake of cholesteryl esters from HDL to the liver and steroidogenic tissues.

Amino Acid Sequence↗
PubMed1998

Relative importance of cytotoxic T lymphocytes and nitric oxide-dependent cytotoxicity in contractile dysfunction of rejecting murine cardiac allografts.

BACKGROUND: Previous in vitro studies have suggested that both cytotoxic T lymphocyte (CTL)-mediated and non-CTL-mediated myocyte lysis occur during murine cardiac heterotopic allograft rejection, but the relative importance of these injury mechanisms on myocardial function is not established. We therefore compared the in vivo effects of depletion of CTL and inhibition of nitric oxide synthase (NOS) on contractility of the rejecting heart. METHODS: Syngeneic (BALB/c into BALB/c) and allogeneic (BALB/c into C57/B16) heterotopic abdominal cardiac transplants were performed. In some of the allogeneic transplants, CD8+ lymphocytes were depleted by intraperitoneal injection of anti-CD8 monoclonal antibody. NOS inhibition was accomplished by continuous infusion of NG-monomethyl-L-arginine via a subcutaneous osmotic pump. Five days after transplantation, the abdominal cavity was opened and the transplanted heart exposed. Base to apex developed force was measured during spontaneous beating at a diastolic stretch of 4 g by placing a suture through the apex of the heart and attaching it to a strain gauge. Effects of interventions on graft survival were determined by recording the days required for loss of palpable graft contractions. RESULTS: Allogeneic hearts showed a significant reduction in systolic force compared to non-rejecting syngeneic hearts. Depletion of CD8+ cells improved contractility significantly relative to non-depleted allogeneic hearts, but contractility remained significantly reduced relative to syngeneic hearts. Developed force in allogeneic hearts was also improved by NOS inhibition (P<0.01), and NG-monomethyl-L-arginine infusion slightly prolonged graft survival. CONCLUSION: Both CTL-mediated and NOS-dependent (possibly macrophage-mediated) mechanisms contribute to contractile dysfunction during early cardiac allograft rejection in this model. However, NOS inhibition combined with CTL depletion only slightly prolongs graft survival in this model.

Animals↗
PubMed1998

Apolipoprotein(a) binds to low-density lipoprotein at two distant sites in lipoprotein(a).

Lipoprotein(a) [Lp(a)] consists of low-density lipoprotein (LDL) and apolipoprotein(a) [apo(a)] linked with a disulfide bond. Scanning force microscopy (SFM) of Lp(a) showed, for the first time, a belt-like structure of apo(a) with both ends attached to a spherical LDL. The two ends of apo(a) were bound to the LDL sphere at two distant sites. Occasionally, the ends were attached to two touching spheres. Under the same imaging conditions, LDL appeared as individual spheres. Electron microscopy (EM) studies of Lp(a) by several groups over the past decade failed to reveal this belt-like structure of apo(a). Images of isolated apo(a) in air or in phosphate buffer showed apo(a) as individual belts, and these belts tended to crowd together. Lp(a) formed leaf-like aggregates; apo(a) aggregates were fishnet-like, whereas LDL aggregates were less characteristic. Quantitative analysis of Lp(a) showed the diameter of the LDL to be 24.8 +/- 8.7 nm (n = 46), which is close to the reported value of 24.2 +/- 4.2 nm found with EM. The length of the belts attached to the spheres was measured to be 173.5 +/- 6.6 nm (n = 15). I also found, by using a functionalized tip, that the interaction force between apo(a) and its ligand, lysine, was related to the ionic strength of the bulk solution. This force can be reduced by the presence of epsilon-aminocaproic acid.

Apolipoproteins A↗
PubMed1998

Study of relapsing remitting experimental allergic encephalomyelitis SJL mouse model using MION-46L enhanced in vivo MRI: early histopathological correlation.

MION-46L, a superparamagnetic iron oxide contrast agent, was investigated for its ability to increase the sensitivity of in vivo 3D MRI in the detection of brain lesions in a chronic experimental allergic encephalomyelitis (crEAE) mouse model. Lesion conspicuity on postcontrast 3D MRI was dramatically enhanced as compared to precontrast images corresponding to areas of inflammatory and demyelinating lesions. MION-46L could be detected on Prussian blue iron stain in the vascular endothelium, the perivascular space, and in macrophages within perivascular cuffs and areas of inflammation and demyelination. By taking advantage of the MION-46L induced macroscopic susceptibility effect, acute early lesions measuring only 100 microm in diameter could be detected. MION-46L enhanced MRI may be used to 1) provide a unique sensitivity in EAE lesion detection and correlate imaging to histopathology; 2) help to understand EAE lesion development and its underlying pathophysiology; and 3) eventually assist in preclinical screening of new experimental therapies directed at patients with multiple sclerosis (MS).

Animals↗
PubMed1998

Cloning genes encoding receptors related to chemoattractant receptors.

We report the cloning of a novel human gene (GPR32) encoding a putative G-protein-coupled receptor (GPCR) of 356 amino acids and a related pseudogene psi GPR32. The deduced amino acid sequence of GPR32 shares 35-39% identity with members of the chemoattractant receptor family. psi GPR32 shares 93% nucleotide identity with GPR32. We identified a mouse EST encoding a putative GPCR (GPR33) of 309 amino acids. The deduced amino acid sequence of GPR33 shares 30-35% identity with members of the chemoattractant receptor family and 36% identity with the receptor encoded by GPR32. The human orthologue of GPR33 contains a single basepair substitution with respect to the mouse, resulting in the presence of an in-frame stop codon within the predicted second intracellular loop, demonstrating that it is a pseudogene. Through fluorescence in situ hybridization and physical mapping of YACs, both GPR32 and psi GPR32 were mapped to chromosomal 19, region q13.3, while psi GPR33 was mapped to chromosome 14q12.

Amino Acid Sequence↗