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S Xu

Publications and source records attributed to S Xu.

At least 415 records · Page 23Linked to original sources
PubMed1996

Using the expectation or the distribution of the identity by descent for mapping quantitative trait loci under the random model.

We examine the ability of four implementations of the random model to map quantitative trait loci (QTLs). The implementations use either the expectation or the distribution of the identity-by-descent value at a putative QTL and either a 2 x 1 vector of sib-pair traits or their scalar difference. When the traits of both sibs are used, there is little difference between the expectation and distribution methods, while the expectation method suffers in both precision and power when the difference between traits is used. This is consistent with the prediction that the difference between the expectation and distribution methods is inversely proportional to the amount of information available for mapping. We find, though, that the amount of information must be very low for this difference to be noticeable. This is exemplified when both marker loci are fixed. In this case, while the expectation method is powerless to detect the QTL, the distribution method can still detect the presence (but not the position) of the QTL 59% of the time (when using trait values) or 14% of the time (when using trait differences). We also note a confounding between estimates of the QTL, polygenic, and error variance. The degree of confounding is small when the vector of trait values is used but can be substantial when the expectation method and trait differences are used. We discuss this in light of the general ability of the random model to partition these components.

Chromosome Mapping↗
PubMed1996

[The effects of cardioplegia and reperfusional blood containing captopril on myocardial ultrastructure alterations after cardiac arrest].

OBJECTIVE: To investigate the myocardial protective effect of captopril on the ischemia and reperfusion injury in the canine heart. METHODS: Twelve mongrel dogs were randomly divided into control and captopril groups. In the former, only modified St. Thomas cardioplegia was used, and in the latter, modified St. Thomas cardioplegia and reperfusional blood containing 4.6mumol/L captopril were used. Sixty minutes after reperfusion, myocardial renin activity (MRA), angiotensin II (AII) and melondyldialdehyde (MDA) content in myocardium were measured, and the subendocardial myocardium of the left ventricle was taken for electromicroscopy. RESULTS: The MRA in the Cp1 group was significantly higher than that in the control group (P < 0.01), while the AII and MDA content in the myocardium in the Cp1 group were significantly lower than those in the control group (P < 0.01). Electronmicroscopically, the damage of the myocardium including sarcomeres, mitochondria and microvascular endothelial cells were less obvious in the Cp1 group than that in the control. The mitochondrial average cross-section area and average volume (0.59 +/- 0.15 micron2 and 0.74 +/- 0.23 micron3) in the Cp1 group were significantly lower than those in the control (0.83 +/- 0.34 micron2, P < 0.01 and 1.1 +/- 0.4 micron3, P < 0.01). The numerical density (0.46 +/- 0.16 micron-3), specific surface of mitochondria (6.4 +/- 1.1 microns-1) and memberance density of mitochondrial cristae (21 +/- 10 microns-1) in the Cp1 group were significantly higher than those in the control (0.29 +/- 0.06 micron-3, P < 0.05, 4.8 +/- 0.8 micron-1, P < 0.01 and 15.3 +/- 2.0 microns-1, P < 0.01): CONCLUSION: Cardioplegia and reperfusional blood containing 4.6 mumol/L captopril could effectively protect the myocardial mitochondria and microvascular endothelial cells against ischemia and reperfusion injury.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1996

[Studies on anti-inflammatory and immune effects of moxibustion].

An animal model of adjuvant arthritis in rats was established, and the effects of anti-inflammatory and immune regulation of moxibustion at "Shenshu" point were investigated. The results showed that it could lighten a local inflammatory reaction, eliminate swelling of the metatarsal and reduce it's girth, prevent or reduce the polyarthritises, maintain the weight and shorten the course of the disease. The results also showed that moxibustion could recover and promote the effects of the Concanavalin A (ConA) inducing splenic lymphocyte proliferation in rats, promote interleukin 2 (IL-2) production, decrease IL-1 contents. The indexes mentioned above were significantly different as compared with contral group. Above results indicated that moxibustion had directly anti-inflammatory and subsidence of swelling effects, through enhancing the ability of immune response the immune functions were lightened and regulated. Therefore, the anti-inflammatory and immune and anti-allergy effects of body were enhanced.

Animals↗
PubMed1996

[Extremity gangrene caused by rare co-infection of multiple bacteria: a case report].

UNLABELLED: Because of progressive infectious necrosis on right hand and forearm for 3 months and the necrosis on left mid-finger for 2 months, a girl patient, Yang Xiaoxia was admitted on 15th, Nov. 1994. Systemic intoxicative symptom was slight and the necrotic tissue presented black scar. After 3 months treatment by application of multiple antibiotics, local dressing changes and an amputation of right froearm, the necrosis could not be stopped but keeping deteriorating. Through experts' consultation, systemic surpportive therapy, wide-spectrum antibiotics cilastatin sodium and complete debridement were adopted. One week later, the fresh surface of granulation tissue was seen, and skin grafting was performed. The wound healed 3 months later. After further rehabilitation, the left thumb, index and fifth finger showed normal function. A mechanical motional artificial limb was installed on right forearm and discharged. The deep necrotic tissue of left mid-finger was examined. Results of culture from several hospital presented 2 kinds of aerobic bacteria and 10 kinds of the anaerobic, of which, the names of 3 kinds are still unknown. Pathological examination showed chronic pyogenic necrotic infection, spreading from skin to deep muscles and interosseous membrane. And infiltration of eosinophilic granulocytes was found in the infectious region. CONCLUSION: This patients is progressive gangrene of the extremity caused by rare co-infection of multiple bacteria. The characteristics were slight systemic intoxicative symptom, local progressive necrosis and formation of black scar. By means of systemic surpportive therapy, application of wide-spectrum antibiotics cilastatin sodium, complete debridement and skin grafting, the patient was cured.

Adolescent↗
PubMed1996

[The value of determining guanine deaminase in diagnosis of hepatic diseases].

We determined the Guanine Deaminase (GD) activity of 200 patients with different diseases. It was found that GD activity of hepatic patients is higher than that of health adults, while the GD activity of other patients is in the normal range. There is a linear correlation between GD activity and ALT in patients with chronic hepatitis, billiary obstruction, and between GD activity and total bilirubin in patients with chronic active hepatitis, biliary obstruction and liver cirrhosis. Moreover, the GD activity of patients positive for anti-HCV is significantly increased. So GD activity in serum is a specific and sensitive index to estimating hepatic functions and can be used in the diagnosis of acute and chronic hepatitis, cirrhosis of liver, and C virus hepatitis.

Adult↗
PubMed1996

[Hashimoto's disease with thyroid cancer: report of six cases].

Hashimoto's disease associated with thyroid cancer is not common. From January 1976 to December 1994, a total of 95 patients with Hashimoto's disease were treated surgically. Six (5 Papillary 1 folicular) of 95 patients had thyroid cancer which was concomitantly revealed pathologically. They were all women with mean age of 30.3 years. The size of tumor was 0.3-2.0 cm. Follow-up for 1-17 years showed that they were all alive and healthy. Two patients were misdiagnosed as having anaplastic carcinoma but the definitive diagnosis by immunohistochemical analysis was thyroid malignant lymphoma (B-cell type). Hashimoto's disease and thyroid cancer relationship, diagnosis, and treatment are discussed.

Adult↗
PubMed1995

Isolation of MEK5 and differential expression of alternatively spliced forms.

The prototype mitogen-activated protein (MAP) kinase module is a three-kinase cascade consisting of the MAP kinase, extracellular signal-regulated protein kinase (ERK) 1 or ERK2, the MAP/ERK kinase (MEK) MEK1 or MEK2, and the MEK kinase, Raf-1 or B-Raf. This and other MAP kinase modules are thought to be critical signal transducers in major cellular events including proliferation, differentiation, and stress responses. To identify novel mammalian MAP kinase modules, polymerase chain reaction was used to isolate a new MEK family member, MEK5, from the rat. MEK5 is more closely related to MEK1 and MEK2 than to the other known mammalian MEKs, MKK3 and MKK4. MEK5 is thought to lie in an uncharacterized MAP kinase pathway, because MEK5 does not phosphorylate the ERK/MAP kinase family members ERK1, ERK2, ERK3, JNK/SAPK, or p38/HOG1, nor will Raf-1, c-Mos, or MEKK1 highly phosphorylate it. Alternative splicing results in a 50-kDa alpha and a 40-kDa beta isoform of MEK5. MEK5 beta is ubiquitously distributed and primarily cytosolic. MEK5 alpha is expressed most highly in liver and brain and is particulate. The 23 amino acids encoded by the 5' exon in the larger alpha isoform are similar to a sequence found in certain proteins believed to associate with the actin cytoskeleton; this alternatively spliced modular domain may lead to the differential subcellular localization of MEK5 alpha.

Alternative Splicing↗
PubMed1995

Electrostatic force microscope for probing surface charges in aqueous solutions.

A scanning force microscope was converted to an electrostatic force microscope by charging the usually neutral cantilever with phospholipids. The electrostatic force microscope was used to study surface electrostatic charges of samples in aqueous solutions. Lysozymes, DEAE-Sephadex beads, 3-propyltriethoxysilane-treated glass and mica were imaged in water or phosphate buffer with electrostatic force microscopy. The adhesion force measured when a charged probe and oppositely charged specimen interacted was up to 500 times greater than when a bare probe was used. This dramatic increase in measured adhesion force can be attributed to the energy required to break the salt bridges formed between the charged probe and the specimen. The use of phospholipids to functionalize the cantilever tip allows the incorporation of other biomolecules and ligands that can be used as biologically specific tips (e.g., receptors, drugs) for the study of intermolecular interactions.

Aluminum Silicates↗
PubMed1995

Specific induction of cAMP in Langerhans cells by calcitonin gene-related peptide: relevance to functional effects.

Epidermal Langerhans cells (LC) are associated anatomically with epidermal nerves, and a product of these nerves, calcitonin gene-related peptide (CGRP), inhibits the antigen-presenting capacity of LC and macrophages. As the CGRP receptor appears to be coupled to Gs alpha protein, which in turn activates adenylate cyclase, the ability of CGRP to induce cAMP in LC was examined and correlated with functional effects. LC were isolated from murine epidermal cells using antibodies on magnetic microspheres. Exposure to CGRP induced a significant increase in cAMP content, which could be inhibited by coculture with a truncated form of CGRP [CGRP-(8-37)] that is a specific competitive inhibitor of CGRP. Substance P and calcitonin failed to induce cAMP in LC. Although culture in CGRP reduced the ability of murine epidermal cells enriched for LC content to present pigeon cytochrome c to a responsive clone or to present antigen for elicitation of delayed-type hypersensitivity in immune mice, culture in forskolin had little or no effect on antigen presentation despite increased cAMP content of LC as much or more than that induced by CGRP. The effect of CGRP on antigen presentation in these systems could be blocked with CGRP-(8-37). CGRP inhibited the induction of B7-2 by lipopolysaccharide on peritoneal macrophages and a LC line, whereas calcitonin did not. CGRP induces specific accumulation of cAMP in LC and inhibits LC antigen-presenting function by a receptor-mediated event. However, the induction of cAMP by itself does not account for inhibition of antigen presentation. Suppression of the expression of B7-2 may be one mechanism by which CGRP inhibits antigen presentation.

Animals↗
PubMed1995

MEKK1 phosphorylates MEK1 and MEK2 but does not cause activation of mitogen-activated protein kinase.

A constitutively active fragment of rat MEK kinase 1 (MEKK1) consisting of only its catalytic domain (MEKK-C) expressed in bacteria quantitatively activates recombinant mitogen-activated protein (MAP) kinase/extracellular signal-regulated protein kinase (ERK) kinases 1 and 2 (MEK1 and MEK2) in vitro. Activation of MEK1 by MEKK-C is accompanied by phosphorylation of S218 and S222, which are also phosphorylated by the protein kinases c-Mos and Raf-1. MEKK1 has been implicated in regulation of a parallel but distinct cascade that leads to phosphorylation of N-terminal sites on c-Jun; thus, its role in the MAP kinase pathway has been questioned. However, in addition to its capacity to phosphorylate MEK1 in vitro, MEKK-C interacts with MEK1 in the two-hybrid system, and expression of mouse MEKK1 or MEKK-C in mammalian cells causes constitutive activation of both MEK1 and MEK2. Neither cotransfected nor endogenous ERK2 is highly activated by MEKK1 compared to its stimulation by epidermal growth factor in spite of significant activation of endogenous MEK. Thus, other as yet undefined mechanisms may be involved in determining information flow through the MAP kinase and related pathways.

Animals↗
PubMed1995

Colony-stimulating factor-1 secreted by fibroblasts promotes the growth of dendritic cell lines (XS series) derived from murine epidermis.

We have established recently from mouse epidermis long-term dendritic cell lines (XS series) that resemble epidermal Langerhans cells (LC) by their surface phenotype, Ag-presenting profile and cytokine mRNA profile. The growth of XS lines was promoted maximally by granulocyte-macrophage-CSF or by a factor secreted by NS lines, which are fibroblastic cell lines established from dispase-separated specimens of mouse epidermis. The purpose of this study was to determine the identity of XS cell growth factor secreted by NS cells. We report the following: 1) NS cells express constitutively mRNA for CSF-1; 2) XS cells express the CSF-1R at mRNA and protein levels; 3) rCSF-1 mimics NS culture supernatant in its ability to promote XS cell growth; 4) NS supernatant-dependent XS cell growth is blocked completely by each of two Abs against the CSF-1R. We conclude that CSF-1 is responsible for the XS growth-promoting activity secreted by NS lines. We also report the following: 5) LC freshly isolated from skin express CSF-1R mRNA; and 6) fibroblasts derived from specimens of dermis also express mRNA and secrete large amounts (50-100 ng/ml) of CSF-1. These observations give rise to a new concept that dermal fibroblasts may support the survival and growth of LC (and their precursors) through the paracrine effect of elaborated CSF-1.

Animals↗
PubMed1995

Successive generation of antigen-presenting, dendritic cell lines from murine epidermis.

Dendritic cells are specialized APCs that exhibit an extraordinary capacity to activate naive T cells. Langerhans cells (LC), as epithelial tissue-specific members of this family, play key roles in the induction of T cell-mediated immunity against environmental, infectious, and tumor-associated Ags in skin. A major limitation in studying the biology of dendritic cells or LC has been the absence of stable, long-term cell lines. To overcome this limitation, we have established a series of APC lines (XS series) from newborn BALB/c mouse epidermis. XS lines, which have grown for more than 12 mo in culture, exhibit high similarity to LC freshly procured from skin in terms of: a) tissue of derivation (epidermis), b) phenotype (lalow/CD45+/E-cadherin+/B7-1-), c) shape (elongated dendrites), and d) Ag-presenting profile (modest ability to activate naive, allogeneic T cells and remarkable ability to present a protein Ag to primed CD4+ T cells). The availability of XS lines as well as the methodologies used for their growth enhance our capability of studying the biology of LC at biochemical and molecular levels.

Animals↗
PubMed1995

Cytokine-dependent regulation of growth and maturation in murine epidermal dendritic cell lines.

We have recently established dendritic cell (DC) lines (XS series) from the epidermis of newborn mice by repeated feeding with granulocyte/macrophage-colony-stimulating factor (GM-CSF) and culture supernatants from skin-derived stromal cell lines (NS series). XS lines resemble resident Langerhans cell (LC), which are immature DC that reside in epidermis, by their surface phenotype and antigen-presenting profile. XS lines further resemble resident LC in that they express mRNA for interleukin-1 beta and macrophage inflammatory protein (MIP)-1 alpha, and by the absence of mRNA for IL-6. Their growth is promoted by GM-CSF, colony-stimulating factor-1 (CSF-1), or NS culture supernatant, and inhibited by interferon-gamma or tumor necrosis factor-alpha. The expression by the XS lines of Ia molecules is up-regulated by GM-CSF, and down-regulated by NS supernatant. These results suggest the existence of negative regulatory mechanisms in which the growth and/or maturation of DC is suppressed by selected cytokines.

Animals↗
PubMed1995

Measurement of water diffusion in hormone-treated rat uteri by diffusion-weighted magnetic resonance imaging.

In this study, apparent water diffusion coefficients in hormone-treated rat uteri were measured by diffusion-weighted NMR imaging. Four groups of ovariectomized, mature young rats were treated with estrogen, progesterone, estrogen plus progesterone, or saline (as control). It was found that water diffusion is anisotropic in the myometrium, but not in the endometrium, and that it depends on hormonal conditions in the endometrium, but not in the myometrium. The anisotropy of water diffusion can be exploited to improve image contrast among the various uterine tissue types. The hormonal response suggests that diffusion imaging of human uterus may be useful in detecting endometrial pathology.

Animals↗
PubMed1995

VH and VL gene usage by anti-beta-amyloid autoantibodies in Alzheimer's disease: detection of highly mutated V regions in both heavy and light chains.

In a previous study, four human IgM kappa monoclonal antibodies (mAbs) secreted by Epstein-Barr-virus-transformed B cell lines independently derived from the peripheral blood of a patient with Alzheimer's disease (AD) were found to react with a conformational epitope of beta-amyloid protein and to stain amyloid plaques in AD brain. Three of these mAbs were studied further. They did not react with an additional panel of antigens and autoantigens. By a competitive inhibition ELISA, the Kd was determined to be 5.7 x 10(-8) M. The VH and V kappa of these mAbs were sequenced at the cDNA level and found to be identical. The corresponding VH and V kappa germline counterpart genes hsigghvm148 and hsiggkvm148 were identified to be analogous to the previous reported VH3 germline gene humighvf1/dp53 and the V kappa IV germline gene hsigk18. DA1/4 and JH4b were used by the heavy chain and J kappa 4 was used by the light chain. Multiple nucleotide substitutions were seen in both VH and V kappa when their sequences were compared to the germline sequences. High replacement/silent ratios in the CDR regions of both VH and V kappa indicate positive-selective pressure. Of a total of 22 amino acid replacements in VH and V kappa, 12 were nonconservative replacements. Furthermore, 7 of these 12 resulted in charge changes. The monoreactivity, the moderately high affinity constant, the clonal expansion evident by identical VH and VL used by these B cells secreting antibodies of interest, and the excessive replacement mutations in both VH and VL segments lead to the conclusion that these antibodies have been generated due to an antigen-driven process.

Alzheimer Disease↗
PubMed1995

Scleroderma-derived human fibroblasts retain abnormal phenotypic and functional characteristics following retroviral transduction with the SV40 tsT antigen.

In this study an amphotropic retrovirus has been used to efficiently transduce normal human (NF) and scleroderma (systemic sclerosis; SSc) dermal fibroblasts (SScF) with a sequence encoding a temperature-sensitive mutant of the SV40 large T antigen (tsA58-U19). From the primary outgrowths of skin explants, cultures were generated whose growth was stringently temperature-dependent. When grown at a low, permissive temperature (35 degrees C), both normal and SSc-transduced cells continuously divided with similar doubling times, whereas at a high, nonpermissive temperature (39.5 degrees C), division of both the NF and SScF cells was rapidly arrested. These cells have been passaged more than 50 times, have the typical morphological appearance of fibroblasts, and have retained an anchorage-dependent phenotype. The transduced normal cells (tsT-NF) synthesized the matrix molecules collagen and fibronectin and expressed phenotypic antigens characteristic of their nontransduced counterparts, including MHC Class I, VLA beta 1 (CD29), Hermes 1 (CD44), VLA-4 alpha (CD49d), ICAM-1 (CD54) and LFA-3 (CD58) and the cell surface ectoenzymes neutral endopeptidase (CD10), aminopeptidase N (CD13), and dipeptidyl peptidase IV (CD26). Analysis of the transduced SSc fibroblasts (tsT-SScF) showed that these cells exhibited certain major features of the SSc pathology, notably the abnormally high synthesis of type I collagen, increased expression of ICAM-1, and depressed levels of CD26. Moreover, these phenotypic characteristics were retained even after prolonged culture in vitro. The tsT-SScF cells also retained their responsiveness to cytokines, since interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) both produced a marked increase in ICAM-1 expression. Our findings show that infection of SScF with the SV40 tsT antigen extends the life span of these cells and does not ablate their abnormal phenotypic and functional characteristics.

Antibodies↗