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Biomedical subjects

X H Song

Publications and source records attributed to X H Song.

At least 19 recordsLinked to original sources
PubMed2003

Crosslinked collagen/chitosan matrix for artificial livers.

Matrices composed of collagen and chitosan may create an appropriate environment for the regeneration of livers. In this study, we have prepared, characterized and evaluated a new collagen/chitosan matrix (CCM). The CCM was made by using crosslinking agent 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) in N-hydroxysuccinimide (NHS) and a 2-morpholinoethane sulfonic acid (MES) buffer system. The chemical characteristics were evaluated by Fourier-transformed infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The mechanical strength was measured by tensile tests. The platelet deposition and hepatocyte culture experiments show that CCM has excellent blood and cell compatibility. The results suggest that the CCM is a promising candidate matrix for implantable bioartificial livers.

Animals↗
PubMed2001

Quantification of ATOFMS data by multivariate methods.

Aerosol time-of-flight mass spectrometry (ATOFMS) is capable of measuring the sizes and chemical compositions of individual polydisperse aerosol particles in real time. A qualitative estimate of the particle composition is acquired in the form of a mass spectrum that must be subsequently interpreted in order to draw conclusions regarding atmospheric relevance. The actual problem involves developing a calibration that allows the mass spectral data to be transformed into estimates of the composition of the atmospheric aerosol. A properly calibrated ATOFMS system should be able to quantitatively determine atmospheric concentrations of various species. Ideally, it would be able to accomplish this more rapidly, accurately, with higher size and time resolution, and at a far lower marginal cost than the manual sampling methods that are currently employed. Attempts have already been made at using ATOFMS and similar techniques to extract the bulk chemical species concentration present in an ensemble of particles. This study represents the use of a multivariate calibration method, two-dimensional partial least-squares analysis, for calibrating single-particle mass spectral data. The method presented here is far less labor-intensive than the univariate methods attempted to date and allows for less observer bias. Because of the labor savings, this is also the most comprehensive calibration performed to date, resulting in the quantification of 44 different chemical species.

Aerosols↗
PubMed2001

Amino-terminal modification and tyrosine phosphorylation of [corrected] carboxy-terminal fragments of the amyloid precursor protein in Alzheimer's disease and Down's syndrome brain.

The carboxy-terminal fragments (CTFs) of the amyloid precursor protein (APP) are considered beta-amyloid (Abeta) precursors as well as molecular species possibly amyloidogenic and neurotoxic by [corrected] in vitro or in animal models. The CTF's role in the pathogenesis of Alzheimer's disease (AD) is however relatively unexplored in human brain. In this study, we analyzed brain extracted CTFs in subjects with AD, non-AD control, and Down's syndrome (DS) cases. Our data indicate that: (i) In fetal DS subjects CTFs levels are increased in comparison to age-matched control, suggesting that the enhanced CTFs formation is important for the early occurrence of plaques deposition in DS. No significant difference in CTFs level [corrected] between AD and age-matched control cases. (ii) CTFs modified at their N-terminus are the direct precursors of similarly N-terminally modified Abeta peptides, which constitute the most abundant species in AD and DS plaques. This observation suggests that N-truncated Abeta peptides are formed directly at beta-secretase level and not through a progressive proteolysis of full-length Abeta1-40/42. (iii) Among the differently cleaved CTFs, only the 22- and 12.5-kDa CTF polypeptides are tyrosine phosphorylated in both AD and control brain while the full-length APP and the CTFs migrating below the 12.5-kDa marker are not phosphorylated, suggesting that APP and CTFs may be involved in different pathways depending on their length and sequences. This study provides evidence that CTFs constitute in human brain a molecular species directly involved in AD pathogenesis and in the development of the AD-like pathology in DS subjects.

Adolescent↗
PubMed2000

Quantitative determination of PEG-hirudin in human plasma using a competitive enzyme-linked immunosorbent assay.

Polyethylene glycol (PEG) coupled r-hirudin mutein is determined by biological methods-the coagulation system. In the present study, a competitive enzyme-linked immunosorbent assay (ELISA) is described that permits the measurement of PEG r-hirudin. The ELISA system adopts a rabbit IgG antibody to quantitatively detect PEG-hirudin in human plasma. A PEG-hirudin calibration curve ranged from 50 to 7000 ng/mL. The limit of detection was 87 ng/mL. The intraassay coefficients of variation (CV) ranged between 16 and 21%, and interassay CV between 8 and 22% for low and high PEG-hirudin concentrations, respectively. The recovery of the compound in plasma was between 96 and 111.5%. The interindividual differences between 100 and 5000 ng/mL PEG-hirudin were between 12 and 22%. The correlation of the concentration of PEG-hirudin determined with the ELISA and the ecarin clotting time was r = 0.902. No interactions between unfractionated heparin, low molecular-weight heparin, or phenprocoumon and PEG-hirudin were observed in the ELISA. Deficiencies of thrombin or antithrombin as well as low, normal, and high fibrinogen levels did not interfere with the assay. It is concluded that the ELISA determines the concentration of PEG-hirudin and is not influenced by other major anticoagulants or by plasma levels of some coagulation proteins.

Calibration↗
PubMed2000

Treatment of an acute flush reaction caused by subcutaneous r-hirudin with pegylated hirudin.

We report a patient who was treated with recombinant (r)-hirudin for heparin-induced thrombocytopenia and developed a flush reaction twice upon re-exposure to 25 mg of subcutaneous r-hirudin. Antihirudin IgG antibodies developed. The patient received 50 mg of PEG-hirudin subcutaneously over 2 days. No side-effects occurred. The level of IgG antihirudin antibodies increased. Ecarin clotting time and thrombin inhibition S2238 assay were not influenced by the patient's IgG antihirudin antibody. PEG-hirudin may be used in patients with intolerance to r-hirudin because of a dissociation of the allergenic and immunogenic properties of the pegylated drug.

Acute Disease↗
PubMed2000

Determination of serotonin release from platelets by enzyme immunoassay in the diagnosis of heparin-induced thrombocytopenia.

[14C]-Serotonin release assay (14C-SRA) from platelets is considered to be the most sensitive test for laboratory confirmation of heparin-induced thrombocytopenia (HIT). This study compared 14C-SRA with an enzyme immunoassay (EIA) to determine the release of serotonin from platelets in the presence of heparin and serum from HIT patients. The normal range (median, 2.5 and 97.5 percentiles) of serotonin release from platelets in healthy subjects (n = 149) is 38 ng/ml (19 and 62) measured by EIA-SRA. Serum from HIT patients (n = 42) released 2548 ng/ml (244 and 7987) serotonin in the presence of 0.1 IU/ml heparin and 29 ng/ml (13 and 76) in the presence of 100 IU/ml heparin. One hundred per cent and 15% of HIT samples exhibited an elevated serotonin release from platelets in the presence of 0.1 IU/ml low molecular weight (LMW) heparin, 2100 ng/ml (869 and 5968), or danaparoid, 272 ng/ml (143 and 403), respectively. The sensitivity and specificity of the EIA-SRA was 100% and 97.4% and of the 14C-SRA 100% and 92.9% in HIT patients. No false-positive results were found in patients receiving heparin (n = 28), in patients with elevated levels of bilirubin (n = 5), in patients with antiphospholipid antibody syndrome (n = 10) or in non-HIT patients (n = 78) with both assays. The EIA technique to quantify serotonin release from platelets provides a reliable non-radioactive method to diagnose heparin-induced thrombocytopenia and to assess in vitro crossreactivity of low molecular weight heparins and heparinoid.

Anticoagulants↗
PubMed2000

Re-exposure to recombinant (r)-hirudin in antihirudin antibody-positive patients with a history of heparin-induced thrombocytopenia.

Patients with a history of heparin-induced thrombocytopenia (HIT) and antibodies to hirudin were re-exposed to recombinant (r)-hirudin for prophylaxis of thromboembolism. Four patients were re-exposed to 2 x 25 mg of subcutaneous r-hirudin for 8-27 d. Two patients were re-exposed once, one patient twice and one four times. Re-exposure was well tolerated in all patients and no thromboembolism occurred. Antihirudin IgG (4/4 patients), IgA and IgM (1/4 patients) antibody levels increased. Baseline ecarin clotting times showed high variability. Patients with antibodies to hirudin may be re-exposed but anticoagulant monitoring is mandatory.

Adult↗
PubMed2000

Identification of sources of Phoenix aerosol by positive matrix factorization.

Chemical composition data for fine and coarse particles collected in Phoenix, AZ, were analyzed using positive matrix factorization (PMF). The objective was to identify the possible aerosol sources at the sampling site. PMF uses estimates of the error in the data to provide optimum data point scaling and permits a better treatment of missing and below-detection-limit values. It also applies nonnegativity constraints to the factors. Two sets of fine particle samples were collected by different samplers. Each of the resulting fine particle data sets was analyzed separately. For each fine particle data set, eight factors were obtained, identified as (1) biomass burning characterized by high concentrations of organic carbon (OC), elemental carbon (EC), and K; (2) wood burning with high concentrations of Na, K, OC, and EC; (3) motor vehicles with high concentrations of OC and EC; (4) nonferrous smelting process characterized by Cu, Zn, As, and Pb; (5) heavy-duty diesel characterized by high EC, OC, and Mn; (6) sea-salt factor dominated by Na and Cl; (7) soil with high values for Al, Si, Ca, Ti, and Fe; and (8) secondary aerosol with SO4(-2) and OC that may represent coal-fired power plant emissions. For the coarse particle samples, a five-factor model gave source profiles that are attributed to be (1) sea salt, (2) soil, (3) Fe source/motor vehicle, (4) construction (high Ca), and (5) coal-fired power plant. Regression of the PM mass against the factor scores was performed to estimate the mass contributions of the resolved sources. The major sources for the fine particles were motor vehicles, vegetation burning factors (biomass and wood burning), and coal-fired power plants. These sources contributed most of the fine aerosol mass by emitting carbonaceous particles, and they have higher contributions in winter. For the coarse particles, the major source contributions were soil and construction (high Ca). These sources also peaked in winter.

Aerosols↗
PubMed1994

Focal adhesion-associated proteins p125FAK and paxillin are substrates for bradykinin-stimulated tyrosine phosphorylation in Swiss 3T3 cells.

In this study we examined the involvement of the focal adhesion-associated proteins p125FAK and paxillin as substrates for bradykinin (BK)-stimulated tyrosine phosphorylation in Swiss 3T3 cells and the potential role of protein kinase C and Ca2+ in these events. BK (1 microM) stimulated tyrosine phosphorylation of p125FAK and paxillin. In addition, BK also increased the phosphotyrosine content of the src transformation-associated protein p130. The responses were rapid and transient and peaked at approximately 1 min after BK addition. Furthermore, the responses were dose-dependent with half-maximal effects occurring at 1-10 nM BK. The phosphotyrosine content of p125FAK, paxillin, and p130 was also increased following stimulation with phorbol 12-myristate 13-acetate (PMA) (0.1 microM). In contrast, PMA had no effect on the phosphotyrosine content of p125, a Ras-GAP-associated tyrosine phosphoprotein that we recently identified. Long term pretreatment (18 h) of cells with 0.3 microM PMA partially attenuated BK-stimulated phosphorylation of p125FAK but was without effect on phosphorylation of paxillin and Ras-GAP-associated p125. Furthermore, only a small inhibition of BK- and PMA-stimulated phosphorylation of p125FAK was observed following pretreatment with 25 microM BAPTA/AM. In all, these results show that multiple mechanisms are involved in BK-stimulated tyrosine phosphorylation of p125FAK, paxillin, Ras-GAP-associated p125, and src transformation-associated p130.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1994

Artificial neural networks applied to classification of mutagenic activity of nitro-substituted polycyclic aromatic hydrocarbons.

Three-layer artificial neural networks (ANN) with back-propagation of error have been applied to classification of nitro-substituted polycyclic aromatic hydrocarbons (NPAH) based on the regularity that the structure difference of NPAH compounds leads to different mutagenic activity towards Salmonella typhimurium. The network's architecture and parameters were optimized to give maximum correct classification rate of 93.8% for two different classes of NPAHs: weakly active and strongly active ones. The results compared favourably with those obtained by nonlinear mapping pattern recognition method. Considering that the most important factor for NPAH's mutagenicity might be the electron effect of the substituted nitro-groups, an electrotopological state index of nitrogen atom was introduced additionally as one of network's inputs, and the correct classification rate was consequently raised to 97.5%. The network's prediction ability for untrained samples was also satisfactory.

Mutagens↗
PubMed1994

Okadaic acid induces marked shape change of human platelets.

Okadaic acid (OA) induced marked shape changes of human platelets but neither granule secretion nor increase in [Ca2+]i occurred. Morphological changes induced by OA were unique and different from those observed with thrombin mainly in two respects. One is that the pseudopods formed by OA treatment were longer and straighter than those by thrombin. The other is that no granule centralization was observed with OA-treatment, although central condensation of cytofilaments was observed as was with thrombin. The immunocytochemical analysis employing anti-myosin antibody revealed that myosin was distributed in the elongated pseudopods. Since OA induced phosphorylation of the 20-kDa myosin light chain (MLC20) corresponding to the change in shape of platelets but did not induce phosphorylation of the 47-kDa protein (pleckstrin) (Higashihara M. et al. FEBS Lett. 307:206-210, 1992), these results suggest that phosphorylation of MLC20 plays an important role in OA-induced unique morphological changes of platelets.

Blood Platelets↗
PubMed1994

[Detection of cervical human papillomavirus infection from women with external genital condyloma acuminata].

Cervical biopsy specimens were taken from 36 women with external genital condyloma acuminata in order to diagnose a concomitant cervical human papillomavirus (HPV) infection. Positive HPV infection rate of cervix was 16% (6/36) by routine visual examination, 69% (25/36) by colposcopy and 56% (18/32) by pathology. Among those patients 31% (10/32) have grade I-II cervical intraepithelial neoplasia (CIN) according to pathology. In 8 cases, both vulva and cervical specimens were examined by Southern blot, dot blot and polymerase chain reaction (PCR) technique. HPV DNA positive was detected in 7 of 8 cervical specimens. It is concluded cervical HPV infection was rather common in women with external genital condyloma acuminata and it is valuable to examine cervical HPV infection by colposcopy and biopsy to detect the concomitant CIN.

Adolescent↗
PubMed1994

[A comparable study of microwave tissue coagulation (MTC) and CO2 laser in treatment of cervical erosion].

In a randomized study, 300 patients with cervical erosion were allocated to either MTC(154) or CO2 Laser(146). The patients were treated on an outpatient basis without anesthesia. In the case of initial treatment failure the same method was to be used for retreatment. All the patients were followed-up for an average of 11 weeks (8-12). 142 of 154 microwave-coagulated patients (92.20%) and 116 of 146 Laser-evaporated patients (79.45%) were cured after one treatment, and there was significant difference between MTC and Laser group (P < 0.005). Bleeding during operation occurred in 5 of 154 MTC group (3.25%) and 32 of 146 Laser group (21.92) (P < 0.005). The result suggested that MTC had higher cure rate and less complications. It is easy to handle, safe and economic.

Adult↗
PubMed1993

Identification of p125, a component of a group of 120-kDa proteins that are phosphorylated on tyrosine residues in response to bradykinin and bombesin stimulation, in anti-ras-GTPase-activating protein immunoprecipitates of Swiss 3T3 cells.

Bradykinin (BK) and bombesin (BN) stimulate an increase in the tyrosine phosphorylation of a 120-kDa group of proteins (pps120) in Swiss 3T3 cells (Leeb-Lundberg, L. M. F., and Song X.-H. (1991) J. Biol. Chem. 266, 7746-7749). Here, we show that a component of pps120, p125, was specifically immunoprecipitated with antibodies against the p21ras GTPase-activating protein (GAP). The major portion of GAP in nonstimulated cells (96%) was located in the cytosol, and this distribution was not affected by exposure of cells to 1 microM BK for 1 min. A significant amount of GAP in nonstimulated cells was recovered in anti-phosphotyrosine (anti-Tyr(P)) immunoprecipitates, and the cellular distribution of this GAP essentially paralleled that of total GAP. Recovery of GAP in anti-Tyr(P) immunoprecipitates of nonstimulated cells appeared to be caused at least in part by the presence of GAP complexed to a 190-kDa tyrosine-phosphorylated protein (p190). Exposure of cells to 1 microM BK for 1 min resulted in an increase in the recovery of a portion of the cellular GAP in anti-Tyr(P) immunoprecipitates. This increase was paralleled by the appearance of a tyrosine-phosphorylated protein species of 125 kDa (p125) in anti-GAP immunoprecipitates. Tyrosine-phosphorylated p125 was present also in anti-GAP immunoprecipitates after exposure of cells to 1 microM BN. High performance gel exclusion liquid chromatography of the anti-GAP-immunoprecipitated proteins on a Protein-Pak 300SW column revealed that p125 is not GAP. Anti-GAP immunoprecipitation of p125 was prevented by prior denaturation of cell lysates in sodium dodecyl sulfate suggesting that p125 is physically associated with GAP. Chromatography of cell lysates revealed that the pps120 group of tyrosine phosphoproteins includes a 125- and a 120-kDa protein. The anti-GAP-immunoprecipitable p125 migrated identically to the 125-kDa phosphoprotein component of pps120. These observations show that the pps120 group of tyrosine phosphoproteins is composed of at least two physically distinct protein components, p125 and p120. p125 is associated in some manner with a portion of the cellular GAP after exposure of cells to BK and BN.

3T3 Cells↗
PubMed1993

Organ-association phenomena during sepsis. TNF and IL-6 in different macrophages.

Sepsis was induced in rats by cecal ligation and perforation (CLP). Five and 15 hours post CLP, alveolar macrophage (AM), Kupffer cell (KC), and peritoneal macrophage (PM) were isolated and cultured for 18 hours. Culture supernatant was examined for bioactivity of tumor necrosis factor (TNF) and interleukin 6 (IL-6) and response to lipoplysaccharide (LPS) stimulation in vitro. Results showed that AM produced more TNF during sepsis as compared with KC and PM. Stimulation with LPS in vitro was responded only by AM at 15 hr after CLP. Pattern of IL-6 production was different from TNF while KC produced the highest level of IL-6 after induction of sepsis.

Animals↗
PubMed1993

Effect of subconjunctival daunorubicin on glaucoma surgery in rabbits.

Daunorubicin (DNR), an antibiotic-antimetabolite, was used as an adjunct to standardized partial-thickness filtration surgery in 21 rabbits to determine its effects on that surgery. Postoperatively, one of the eyes of each rabbit received subconjunctival injections of DNR 25 micrograms or 50 micrograms, while the fellow eyes received only diluent, daily for 2 to 14 days. Bleb survival, fistula patency, the thickness of the subconjunctival connective tissue, and postoperative complications were investigated. The filtration blebs lasted significantly longer (P < .005), the rate of fistula closure was significantly lower (P < .005), and the subepithelial connective tissue was much looser and thicker in the experimental eyes than in the control eyes. Corneal toxicity occurred more frequently in the eyes treated with the higher-dose DNR than in those treated with the lower dose and in the control eyes.

Animals↗
PubMed1992

The role of Kupffer cells in the development of hepatic dysfunction during sepsis.

The effect of Kupffer cell blockade on hepatic function during sepsis was evaluated in this study. Methyl palmitate suspension 100 mg/100 g administered intravenously suppressed the phagocytic activity as the phagocytic index K decreased from 0.0493 +/- 0.0089 to 0.0150 +/- 0.0035 in rats. Sepsis was produced by the method of cecal ligation and needling perforation (CLP). At the end of 15 hours after CLP the hepatic adenosine triphosphate (ATP) level and ketone body ratio decreased significantly. But in rats pretreated with methyl palmitate 24 hours prior to CLP, the ATP level returned to the normal control level (1.6906 +/- 0.06-2.2323 +/- 0.13 mumol/g) and ketone body ratio remained at significantly higher values (0.26 to 0.68). After CLP, the liver lipoperoxide (LPO) concentration increased and glutathione (GSH) contents decreased significantly. When the septic rats were pretreated with methyl palmitate, both the LPO and GSH returned to the normal control level (62.69 +/- 1.7 to 44.62 +/- 2.12 and 159.85 +/- 9.7 to 222.27 +/- 11.34). It is concluded that the hepatic dysfunction is modulated at least to a greater extent by many of the toxic mediators released by the activated Kupffer cells during sepsis.

Adenosine Triphosphate↗