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Biomedical subjects

Q Yang

Publications and source records attributed to Q Yang.

At least 343 records · Page 19Linked to original sources
PubMed1997

Trends in capillary electrophoresis: 1997.

This article is intended to present an overview of developments in the field of capillary electrophoresis (CE) and its application to the analysis of micro-environments. Instrumental developments in injection and detection methods and the separation chemistries are outlined. Emphasis is placed on methods and means that have significantly improved the capability of CE. Subsequently, several selected applications to the exploration of microenvironments such as CE-based sensors, CE on microchip, and single cell analysis are described. The recent advancements in these areas are highlighted.

Electrochemistry↗
PubMed1997

Does periconceptional multivitamin use reduce the risk for limb deficiency in offspring?

There is accumulating evidence that periconceptional multivitamin use may prevent the occurrence of some birth defects other than neural tube defects. Using data from the population-based Atlanta Birth Defects Case-Control Study, we investigated the possible association between periconceptional multivitamin use and the occurrence of limb deficiency. We examined the periconceptional use of multivitamins among mothers of 117 babies with nonsyndromic limb deficiency who were liveborn or stillborn to residents of metropolitan Atlanta from 1968 to 1980 and among mothers of 3,029 control babies born without birth defects who were randomly selected through birth certificates. We found that children whose mothers were periconceptional multivitamin users had a lower risk of having a limb deficiency [odds ratio (OR) = 0.47; 95% confidence interval (CI) = 0.23-0.97]. This protective effect, however, was mostly seen for transverse limb deficiency (OR = 0.30; 95% CI = 0.07-1.32) and not for longitudinal deficiency (including preaxial and postaxial deficiencies; OR = 1.03; 95% CI = 0.17-4.30). Adjustment for potential confounding factors did not change these findings. We found a trend of decreasing risk for all transverse limb deficiencies with earlier vitamin use. These data indicate that mothers' periconceptional multivitamin use may reduce the risk for some types of limb deficiency among their offspring. In addition, because we did not find the protective effect for all types of limb deficiency, the data may also indicate causal heterogeneity of limb deficiencies.

Arm↗
PubMed1997

Transient expression of a winged-helix protein, MNF-beta, during myogenesis.

A novel winged-helix transcription factor, MNF-beta, is expressed coincidentally with cell cycle withdrawal and differentiation of skeletal myogenic cells. MNF-beta is closely related to the myocyte nuclear factor (MNF) protein previously described (now termed MNF-alpha), but expression of the two isoforms is differentially regulated, and they exhibit distinctive functional properties with respect to DNA binding in vitro and transcriptional regulatory activity in transient-transfection assays. A DNA sequence motif binding MNF-beta with high affinity was selected from a library of random oligonucleotides and was found to be similar to but distinct from the cognate binding site for HNF-3beta, a more distantly related winged-helix protein. The temporal pattern of MNF-beta expression and the presence of MNF binding motifs within conserved promoter elements of several genes that modulate cell cycle progression support a working hypothesis that MNF proteins may modulate proliferation of myogenic precursor cells during development and muscle regeneration.

Amino Acid Sequence↗
PubMed1997

Effects of dexamethasone on the basal and cytokine-stimulated release of endothelin-1 from guinea-pig cultured tracheal epithelial cells.

Endothelins (ETs) are potent bronchoconstrictor agents postulated to contribute to the pathophysiology of asthma and other respiratory disorders. An increase in both the expression and release of immunoreactive (ir) ETs was reported in bronchial epithelial cells and the bronchoalveolar lavage fluid of asthmatic patients. We investigated whether dexamethasone (DEX), a potent anti-inflammatory and anti-asthmatic drug, regulates the basal and stimulated release of ETs from guinea-pig cultured tracheal epithelial cells. These airway epithelial cells spontaneously release ET-1 over 24 h. When incubated in the presence of 10(-7) and 10(-6) M DEX for 24 h, basal production of ET-1 decreased by 32 and 29%. Lipopolysaccharide (LPS; 1, 5, 10 micrograms/mL), tumor necrosis factor-alpha (TNF alpha; 5, 10 ng/mL), and interleukin-1 beta (IL-1 beta; 1, 5 ng/mL) significantly increased the basal release of ET-1 after 24 h. When these cells were pretreated with DEX (10(-7) M) for a 24-h period, then incubated in the presence of LPS (10 micrograms/mL), TNF alpha (10 ng/mL), or IL-1 beta (1 ng/mL) for another 24 h, the stimulated release of ET-1 was inhibited by 48, 31, and 38%, respectively. At 10(-6) M, DEX decreased the stimulated release by 45, 37, and 46%, respectively. The present results show that DEX can regulate the basal release and inhibit the pro-inflammatory cytokine-stimulated production of ET-1 from guinea-pig cultured tracheal epithelial cells. They suggest that the beneficial effect of glucocorticoids in asthma may be related to the inhibition of ET synthesis.

Animals↗
PubMed1997

Modified LDL decreases the binding of prostaglandin E2, I2, and E1 onto monocytes in patients with peripheral vascular disease.

Recent data suggest that various eicosanoids including prostaglandins play an important regulatory role in the development of atherosclerotic lesions. Peripheral blood monocytes have been implemented in early atherogenesis because they express receptors specific for modified LDL. In this study we investigated the binding of tritium prostaglandins E2 (3H-PGE2), E1 (3H-PGE1) and I2 (3H-PGI2) onto intact peripheral monocytes isolated from 20 patients (32-71 years) with manifested ischemic peripheral vascular disease stage II according to Fontaine and compared the results with those obtained in 16 healthy volunteers (21-68 years). In control subjects, Scatchard analyses of the binding data indicated a single class of high-affinity binding sites for 3H-PGE2 (maximal binding capacity [Bmax] = 11,400 +/- 3200 sites/cell; dissociation constant [Kd] = 1.3 +/- 0.5 nmol/L) and two classes of binding sites for 3H-PGE1 (Bmax1 = 11,200 +/- 4900 sites/cell, Kd1 = 1.5 +/- 0.5 nmol/L; Bmax2 = 47,800 +/- 6100 sites/cell, Kd2 = 12.8 +/- 5.9 nmol/L) as well as for 3H-PGI2 (Bmax1 = 10,100 +/- 3700 sites/cell, Kd1 = 1.7 +/- 0.7 nmol/L; Bmax2 = 81,200 +/- 5200 sites/cell, Kd2 = 14.2 +/- 6.5 nmol/L). In the patients, an absence of the higher-affinity binding class and significantly (P < .01) fewer lower-affinity binding sites were found for each ligand (PGE2: Bmax = 6600 +/- 3600 sites/cell, Kd = 12.1 +/- 3.2 nmol/L; PGI2: Bmax = 6400 +/- 3100 sites/cell, Kd = 22.1 +/- 8.3; PGE1: Bmax = 5300 +/- 1700 sites/ cell, Kd = 20.5 +/- 7.0 nmol/L). After incubation of monocytes with modified LDL (oxidized LDL or acetylated LDL), the binding of prostaglandins was significantly (P < .01 to P < .001) decreased, whereas native VLDL, LDL, and HDL did not interfere with prostaglandin binding. Prostaglandin-induced adenosine 3'-5' cyclic monophosphate (cAMP) formation by monocytes was significantly (P < .01) lower in patients (the concentrations causing 50% elevation of basal cAMP formation [ED50] were 3.8 +/- 2.4 nmol/L for PGE2, 6.3 +/- 3.5 nmol/L for PGE1, and 5.6 +/- 4.1 nmol/L for PGI2) than in the control subjects (ED50 was 1.6 +/- 1.2 nmol/L for PGE2, 4.8 +/- 2.5 nmol/L for PGE1, and 3.1 +/- 1.4 nmol/L for PGI2). After preincubation with modified LDL, the PG-induced cAMP production by monocytes was remarkably decreased in both patients and control subjects (P < .05). Our results suggest a direct effect of modified LDL on PGE2, PGE1, and PGI2 binding onto monocytes by reducing the number of cell surface-expressed receptors available. Modified LDL also reduces the sensitivity of monocytes to prostaglandins, which results in decreased cAMP production. The complex interactions between prostaglandins and lipoproteins may play an important role during atherogenesis.

Adult↗
PubMed1997

Modulation of endothelin production and metabolism in guinea-pig tracheal epithelial cells by peptidase inhibitors.

Endothelins (ET-1, ET-2, ET-3) are potent bronchoconstrictors and growth-promoting mediators. They are released from various cells such as endothelial and epithelial cells. In the airways, ETs are released under basal and stimulated conditions. In patients with status asthmaticus and other pulmonary disorders, the expression and production of ET-1 are increased. We investigated the activities of endothelin-converting enzymes (ECE) and endothelin-degrading enzymes, mostly neutral endopeptidases (NEP), in guinea-pig tracheal epithelial cells in culture through the use of various enzyme inhibitors. We found that among ETs, only ET-1 was steadily released under basal conditions over 24 h. The basal production was attenuated by both phosphoramidon and CGS 26 303, dual NEP and ECE inhibitors. Conversely, thiorphan, a selective NEP inhibitor, did not attenuate but rather increased the concentration of ET-1 in cell supernatants. CGS 24 592 and SQ 28 603, other NEP inhibitors, also increased the concentrations of ET-1 in cell supernatants in a concentration-dependent manner. However, at a high concentration, SQ 28 603 also inhibited the basal release of ET-1, which would suggest a non-selective inhibitory activity against ECE. These data suggest that ET-1 is simultaneously produced and degraded by guinea-pig tracheal epithelial cells via phosphoramidon-sensitive ECE and NEP pathways, respectively. This observation is of interest when considering that asthmatic patients were shown to have a damaged airway epithelium combined with the loss of NEP activity, which was associated with an increased expression and production of ET-1.

Animals↗
PubMed1997

Orientation of photosynthetic reaction center reconstituted in neutral and charged liposomes.

The photosynthetic reaction center from the photosynthetic bacterium Rhodobacter sphaeroides was reconstituted into neutral, positively charged, or negatively charged liposomes. About 70% of photosynthetic reaction centers were reconstituted in the proteoliposomes exposing their H-subunit outside with positively charged lipids while only 30-40% of them were in the same topological orientation with neutral or negatively charged lipids.

Cytochrome c Group↗
PubMed1997

A systematic approach to the assessment of user satisfaction with health care systems: constructs, models and instruments.

In this paper an overview is given about research in the field of user satisfaction with health care systems and a new systematic model is set up. The model distinguishes between system-independent and system-dependent factors, the latter characterised by satisfaction with the content, the interface and the organisation. Evaluated instruments for assessing user satisfaction are classified according to the model and recommendation for an appropriate use are given.

Computer Simulation↗
PubMed1997

[Endoscopic reconstruction of 192 patients with traumatic urethral stenosis].

We treated traumatic urethral stenosis with endoscopic technique and observed effects. 192 men with traumatic urethral stenosis (47 with anterior urethral stenosis and 145 with posterior urethral stenosis) were treated with hydroelectric shock wave, cold knife, microwave and electroincission through transurethral endoscopy. We punched hole in the centre of the scar with hydroelectric shock waves for long segment urethral complete occlution. 43 patients were treated with obliteration and 50 with endoscopic operation again for 1-3 times. With a mean of 29. 3 months (range 3-60 months) of followup, 187 patients were treated successfully. Endoscopic operation has good effects on traumatic urethral stenosis with smaller trauma, and few complications.

Accidents, Traffic↗
PubMed1997

[Studies on the quality control of shangke wangshui].

Shangke Wangshui is a new Chinese traditional patent medicine. Its main ingredients Coptis Chinsis Franch, Phellodendron amurense Rupr. and Gardenia jasminoides Ellis. were identified by TLC and PC. The content of active component berberine in Shangke Wangshui was determined by TLC-scanner. This mothod is simple, quick and highly reproducible and can be as a quality control standards for this preparation.

Berberine↗
PubMed1997

Prognostic modelling in peritonitis. Peritonitis Study Group of the Surgical Infection Society Europe.

OBJECTIVE: To develop and to evaluate a new score to aid management in peritonitis. DESIGN: Prospective, multicentre study. SETTING: 18 departments of surgery in Germany. Austria, and Switzerland. SUBJECTS: 355 patients with peritonitis confirmed at laparotomy. INTERVENTIONS: Computation of four different prognostic systems: APACHE II; APACHE II and successful operation; APACHE II, successful operation and Goris score on the first postoperative day: and multivariate analysis. Predictions were evaluated according to the following criteria: specificity with a fixed sensitivity at 80%, receiver operating characteristic (ROC-) curve, and predictive value. MAIN OUTCOME MEASURE: The ability to predict hospital death and infective complications. RESULTS: Multivariate analysis was superior to APACHE II: APACHE II and successful operation: and APACHE II, successful operation, and Goris score. From the analysis a new prognostic model was derived from which it was possible to identify patients early in the postoperative period who are at high risk of developing further complications (prognostic peritonitis model: PPM). CONCLUSIONS: None of the existing scores was of particular use for therapeutic decision making in peritonitis. The new prognostic model should be the focus of further trials in the management of peritonitis.

APACHE↗
PubMed1997

[Tumor necrosis factor in pregnancies associated with pregnancy induced hypertension].

OBJECTIVE: To determine TNF concentrations in maternal plasma, amniotic fluid and umbilical blood of normal term pregnant women and women with pregnancy induced hypertension (PIH). METHODS: Sixteen normal term-pregnant women as control and fourty-six women with PIH were enrolled for study. Maternal plasma including antepartum and 72 hours after labor, amniotic fluid and umbilical blood TNF concentrations were measured with a sensitive radioimmunoassay. RESULTS: Similar levels of TNF were found in the amniotic fluid and umbilical blood between the two groups. Before labor, maternal plasma TNF level in PIH was generally higher than that in the control, especially a higher level in the moderate and severe PIH (P < 0.05). However, the mean levels of plasma TNF were not significantly different between the two groups after labor. TNF levels in amniotic fluid were significantly lower than those in maternal plasma and umbilical blood. Amniotic fluid and umbilical blood TNF levels in PIH with intrauterine growth retardation (IUGR) were significantly higher than those in PIH without IUGR (P < 0.05). CONCLUSION: Our study demonstrated an increase of TNF level in maternal plasma with PIH. The results may show an abnormal maternal immune reaction to the fetus. An abnormal higher TNF level may have an effect on the pathogenesis of PIH.

Amniotic Fluid↗
PubMed1997

[The monitoring of post cesarean section uterine scal with B-ultrasonographic and clinical detections].

OBJECTIVE: To find out an effective method for monitoring the healing of uterine incision after cesarean section. METHODS: 1,145 patients with cesarean section were monitored by B-ultrasonography. In 19 patients who revealed fluid mass in uterine incision, 10 cases were treated by percutaneous drainage under sonographic guidance and 9 cases as control. RESULTS: According to sonographic characteristics, uterine incision healing can be divided into three conditions: normal type revealing a smooth strong echo's light band in uterine incision (93.97%), inflammatory type revealing an uneven parenchymatous light mass (3.67%), and fluid mass with inflammation revealing a complex light mass with low echo's or anechoic area (2.36%). There were abnormal clinical signs in most cases of inflammation. The percutaneous drainage therapy showed marked effect. CONCLUSIONS: The monitoring of uterine incision healing by B-ultrasonography plays an important role in preventing late post-partum hemorrhage.

Cesarean Section↗