Biomedical subjects

X Y Song

Publications and source records attributed to X Y Song.

17 recordsLinked to original sources

PubMed2001

Bayesian estimation and test for factor analysis model with continuous and polytomous data in several populations.

The main purpose of this paper is to develop a Bayesian approach for the multisample factor analysis model with continuous and polytomous variables. Joint Bayesian estimates of the thresholds, the factor scores and the structural parameters subjected to some simple constraints across groups are obtained simultaneously. The Gibbs sampler is used to produce the joint Bayesian estimates. It is shown that the conditional distributions involved in the implementation are the familiar uniform, gamma, normal, univariate truncated normal and Wishart distributions. The Bayes factor is introduced to test hypotheses involving constraints among the structural parameters of the factor analysis models across groups. Two procedures for computing the test statistics are developed, one based on the Schwarz criterion (or Bayesian information criterion), while the other computes the posterior densities and likelihood ratios by means of draws from the appropriate conditional distributions via the Gibbs sampler. The empirical performance of the proposed Bayesian procedure and its sensitivity to prior distributions are illustrated by some simulation results and two real-life examples.

Bayes Theorem↗

PubMed2001

[ICAM-1 expression of rat brain microvascular endothelial cells caused by fluid shear force].

We studied the effect of shear stress (SS) on intercellular adhesion molecule-1 (ICAM-1) expression of rat brain microvascular endothelial cells (RBMECs) using the parallel plate flow chamber method. It was demonstrated that RBMECs showed a time-dependent, but not a force-dependent, upregulation in ICAM-1 expression. Endothelial cell surface expression of ICAM-1 in the supernatants of RBMECs exposed to SS was not changed, thus excluding the possibility that the upregulated expression is due to the factors synthesized by these cells. These data throw light on understanding the signal transduction pathway inside the endothelial cells under the effect of SS.

Animals↗

PubMed2000

Suppression of streptococcal cell wall-induced arthritis by human chorionic gonadotropin.

OBJECTIVE: To determine whether human chorionic gonadotropin (HCG) contributes to pregnancy-associated immunosuppression, as observed clinically by an amelioration of symptoms in human autoimmune diseases, including rheumatoid arthritis, during pregnancy. METHODS: Administration of HCG was initiated 2 days prior to an arthritogenic dose of streptococcal cell wall (SCW) in nonpregnant female rats, and the development and severity of SCW-induced arthritis was monitored. Inflammatory mediators, including plasma nitrite/nitrate and cytokine levels, were measured. Inducible nitric oxide synthase (iNOS) protein and cytokine messenger RNA expression in joint tissue were compared between treated and untreated arthritic animals. RESULTS: Systemic administration of HCG resulted in a dose-dependent reduction in the clinical arthritis index. Consistent with the amelioration of clinical symptoms, HCG significantly reduced the inflammatory cell infiltration, pannus formation, and bone and cartilage degradation. Mechanistically, HCG therapy was associated with suppression of the overzealous production of tumor necrosis factor alpha, interleukin-6 (IL-6), and IL-1beta, which contribute to synovial pathology in animals with SCW-induced arthritis. Circulating nitric oxide and the amount of iNOS protein were also reduced. Furthermore, circulating transforming growth factor beta levels were elevated by the HCG, all of which suggest monocytes/macrophages as a potential target. CONCLUSION: These findings indicate that HCG exerts a protective effect in this experimental arthritis model, through modulation of inflammatory mediators.

Animals↗

PubMed2000

Secretory leukocyte protease inhibitor mediates non-redundant functions necessary for normal wound healing.

Secretory leukocyte protease inhibitor (SLPI) is a serine protease inhibitor with anti-microbial properties found in mucosal fluids. It is expressed during cutaneous wound healing. Impaired healing states are characterized by excessive proteolysis and often bacterial infection, leading to the hypothesis that SLPI may have a role in this process. We have generated mice null for the gene encoding SLPI (Slpi), which show impaired cutaneous wound healing with increased inflammation and elastase activity. The altered inflammatory profile involves enhanced activation of local TGF-beta in Slpi-null mice. We propose that SLPI is a pivotal endogenous factor necessary for optimal wound healing.

Animals↗

PubMed1999

Hemoglobin protects from streptococcal cell wall-induced arthritis.

OBJECTIVE: To investigate the ability of hemoglobin (Hgb), a nitric oxide (NO) scavenger, to deplete excess NO and reduce inflammation and injury in synovial tissue from joints with inflammatory arthritis. METHODS: The severity of streptococcal cell wall-induced arthritis was monitored following administration of Hgb. Plasma nitrite and nitrate levels were measured, and inducible NO synthase (iNOS) and cytokine messenger RNA (mRNA) expression in peripheral blood mononuclear cells (PBMC) and joint tissue were evaluated. RESULTS: Following systemic administration of Hgb to arthritic rats, plasma levels of nitrite and nitrate as well as iNOS mRNA expression in the joints and PBMC were significantly reduced. Moreover, inflammatory cell accumulation and disease pathology in the joint tissue were dramatically attenuated without obvious side effects. Consistent with this reduction in the inflammatory response, cytokine gene expression was decreased in the synovium of Hgb-treated rats. CONCLUSION: Modulation of NO levels through the use of a NO scavenger, Hgb, influences the development and severity of arthritis. These findings suggest that depletion of excess NO by NO scavengers provides a prototype for further exploration of potential treatments for chronic arthritis.

Animals↗

PubMed1998

Plasmid DNA encoding transforming growth factor-beta1 suppresses chronic disease in a streptococcal cell wall-induced arthritis model.

Transforming growth factor beta is a potent immunomodulator with both pro- and antiinflammatory activities. Based on its immunosuppressive actions, exogenous TGF-beta has been shown to inhibit autoimmune and chronic inflammatory diseases. To further explore the potential therapeutic role of TGF-beta, we administered a plasmid DNA encoding human TGF-beta1 intramuscularly to rats with streptococcal cell wall-induced arthritis. A single dose of 300 microg plasmid DNA encoding TGF-beta1, but not vector DNA, administered at the peak of the acute phase profoundly suppressed the subsequent evolution of chronic erosive disease typified by disabling joint swelling and deformity (articular index = 8.17+/-0. 17 vs. 1.25+/-0.76, n = 6, day 26, P < 0.01). Moreover, delivery of the TGF-beta1 DNA even as the chronic phase commenced virtually eliminated subsequent inflammation and arthritis. Both radiologic and histopathologic as well as molecular evidence supported the marked inhibitory effect of TGF-beta1 DNA on synovial pathology, with decreases in the inflammatory cell infiltration, pannus formation, cartilage and bone destruction, and the expression of proinflammatory cytokines that characterize this model. Increases in TGF-beta1 protein were detected in the circulation of TGF-beta1 DNA-treated animals, consistent with the observed therapeutic effects being TGF-beta1 dependent. These observations provide the first evidence that gene transfer of plasmid DNA encoding TGF-beta1 provides a mechanism to deliver this potent cytokine that effectively suppresses ongoing inflammatory pathology in arthritis.

Animals↗

PubMed1997

The accuracy of clinical examination versus frozen section in the diagnosis of parotid masses.

PURPOSE: This study evaluated the role of clinical examination and frozen sections in the diagnosis and management of parotid masses. PATIENTS AND METHODS: One hundred seventy patients underwent parotidectomy. Of these, the data on 65 were analyzed, with emphasis on accuracy of the clinical diagnosis and frozen section results compared with the final histologic diagnosis. RESULTS: The results showed that the sensitivity of frozen sections for malignancy was 93.3%, and the specificity for a benign tumor was 95.74%, with a 4.2% false-negative rate and a 6.7% false-positive rate. Of the 65 patients, 58 patients had an explicit clinical diagnosis; 88.4% were correctly identified as benign tumors, and 78.6% were correctly diagnosed as malignancies. The false-positive and false-negative rates were 21.4% and 7.0%, respectively. CONCLUSIONS: The results of this study suggest that clinical examination can provide information that is not very reliable, and the surgical plan should be based on intraoperative frozen sections rather than the history and clinical features.

Adolescent↗

PubMed1996

[Synthesis and antimicrobial activities of tetrahydro-2H-1,3,5-thiadiazine-2-thiones].

Ten 3-benzyl-5-substitued tetrahydro-2H-1,3,5-thiadiazine-2-thiones were synthesized and seven of them are reported for the first time. The structures of the compounds have been elucidated by UV, IR, H-NMR and elemental analysis. The in vitro activity of the compounds against 6 kinds of bacteria and 2 kinds of fungi was tested. The antimicrobial activities of all compounds are more potent than sulfadiazine sodium and less potent than norfloxacini. All compounds were found to be more active against gram-negative and less active against gram-positive bacteria and weak against fungi.

Anti-Bacterial Agents↗

PubMed1995

[Study on Chinese herb incense to disinfect wards' air].

The purpose of this study was to find out a proper way to do the air sterilization in the wards. In this study, Chinese herb-burn-incense was used to different wards. Its effect was compared with routine air sterilization methods such as ultraviolet radiator, formaldehyde, and lactiacid method. The bacterial culture of the air was done. The result indicated that Chinese herb-burn-incense not only had the same effect as routine methods in air sterilization but also had no irritation to the patients.

China↗

PubMed1995

An evaluation of velopharyngeal ring ligation in cleft palate repair.

PURPOSE: This article describes the details of the velopharyngeal ring ligation procedure (VPRL) and compares the results with those achieved with the von Langenbeck (VL) and pharyngeal flap procedures (PFP). PATIENTS AND METHODS: A random sample of 52 patients was evaluated postoperatively by phonation tests, measurement of oral pressure, pharyngeal fluoroscopy, and cineradiography. RESULTS: The results showed that the speech of the VPRL group was significantly better than that of the VL group. The velopharyngeal competence rate, the anteroposterior nasopharyngeal minimal diameter, the left-right nasopharyngeal minimal diameter (both in repose and on phonation), and the length of the soft palate were significantly different between VPRL and VL, and between VPRL and PFP. Differences in the velar angle were significant between VPRL and PFP and between PFP and VL, but there was no significant difference between VPRL and VL. CONCLUSIONS: VPRL is a better method for cleft palate repair than the VL or PFP procedures. It can reduce the nasopharyngeal space circumferentially, thus improving the patient's speech.

Adolescent↗

PubMed1994

Construction of an ordered genomic library of Mycoplasma genitalium.

As a first step towards sequencing the chromosome of the suspected human pathogen Mycoplasma genitalium, we attempted to clone its entire genome in a set of ordered cosmids. Cosmid libraries were established by partial digestion of M. genitalium genomic DNA with Sau3AI or EcoRI. A chromosome-walking strategy was used to identify 20 overlapping cosmid clones which contained over 99% of the genome. The final 5.1 kb could not be cloned in cosmids, and was eventually obtained from a genomic library established in a lambda vector. Correspondence of cloned and genomic EcoRI fragments indicated no detectable major deletions or rearrangements in the library. The library was oriented on established XhoI and SmaI physical maps of the chromosome with restriction sites present at the expected locations in the library. The genome contained 74 EcoRI fragments which added up to a total genome size of 578 kb. These were arranged in a partial EcoRI physical map, and those containing the MgPa major attachment protein-encoding operon and its repeat sequences were identified. The existence of this ordered genomic library, which accurately and completely encompasses the entire M. genitalium genome, should serve as a valuable tool for many future studies of this organism and facilitate our long-term goal of sequencing its genome.

Bacterial Proteins↗

PubMed1992

[Effects of imipramine on isolated rabbit basilar artery].

Imipramine (Imi) inhibited the contractile response to BAY k 8644 (IC50 = 2.39 +/- 0.33 mumol.L-1), KCl (IC50 = 1.00 +/- 0.09 mumol.L-1), in rabbit basilar artery rings. Imi was more effective in suppressing the contractile response evoked by KCl, CaCl2, and 5-HT in basilar artery rings than in mesenteric artery rings. The effect of Imi was the same as that of diltiazem (Dil). There was no difference between the inhibitory response of Imi on contraction induced by KCl in basilar artery rings with or without endothelium. The results suggest that Imi may block the calcium channel and inhibit the rabbit basilar artery selectively, and the effect is endothelium-independent.

Animals↗

PubMed1989