Biomedical subjects

Chun Yang

Publications and source records attributed to Chun Yang.

At least 37 records · Page 2Linked to original sources

PubMed2006

Nasogastric feeding tube placement in patients with esophageal cancer: application of ultrathin transnasal endoscopy.

BACKGROUND: Patients with esophageal cancer often present with dysphagia and malnutrition. Obstructive symptoms may improve after radiotherapy and chemotherapy. Nutrition support via a nasogastric tube (NG) or gastrostomy is very important during treatment. The newly developed ultrathin endoscope (Olympus, GIF-N230, outer diameter: 6 mm) has a smaller diameter than the standard endoscope and can be introduced into the esophagus via the nasal cavity. This article reports on the use of an ultrathin endoscope for NG placement for patients with esophageal cancer who presented with dysphagia and failed traditional NG tube placement. METHODS: A consecutive series of 40 patients with esophageal cancer were referred to our hospital from November 2001 to October 2002 for endoscopic placement of NG tubes due to failure of traditional methods of NG placement. An ultrathin endoscope was used to advance the guidewire into the stomach via the nasal cavity. After withdrawal of the scope, the NG tube was inserted over the guidewire under fluoroscopy. OBSERVATIONS: A total of 71 procedures were performed in 40 patients (37 males, 3 females), age 57 +/- 15 years (range, 37-91 y). Seventy procedures (99%) were successful in completing NG tube placement by using an ultrathin transnasal endoscope. Only one procedure failed because the esophageal lumen was completely occluded and the guidewire was not able to be passed through the obstructed site. The average duration that the NG tube was left in place was 49 +/- 35 days (range, 2-144 days). No procedure-related complications, such as bleeding or perforation, occurred. CONCLUSIONS: Using ultrathin transnasal endoscopy to place an NG tube for esophageal cancer patients is effective and safe. It simplifies the procedures and increases the success rate.

Adult↗

PubMed2006

Control release effects of binders used in pills of traditional Chinese medicine herbs.

This research investigated the effects of control release of binders that are used in the pills of Chinese herbal medicine, namely, as processed honey, starch paste, beeswax, or mixtures thereof. Aspirin and baicalin were used as the active pharmaceutical ingredients (API). The processed honey was heated to 110 degrees C, 120 degrees C, or 130 degrees C. In these pills, the binders were the only excipients. The pills were prepared by the stir method using a mixer at 80 degrees C without pressure. The differential thermal analysis (DTA) showed that the melting points of aspirin and baicalin were changed by the binders. The Fourier Transform infrared spectra (FT-IR) of aspirin and baicalin suggest that there are different non-covalent molecular interactions between the API and the binders, such as C-H-pi and hydrogen bond interaction. The dissolution profiles indicate that changing the ratio of the binders altered the patterns of dissolution of the API; thus, this ration may be used to control the release of API from the pills.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2006

[Progress of research on Chinese material medica serum and hepatic stellate cells].

The activation and proliferation of hepatic stellate cells (HSCs) is the central link in the formation and progression of liver fibrosis. From the research of serum pharmacological method of Chinese material medica, we found Chinese material medica serum could interfere in the formation and progression of liver fibrosis. This paper reviewed the progress on Chinese material medica serum and HSCs. The authors pointed out Chinese material medica serum could effect on the activation, proliferation, contraction and apoptosis of HSCs, which probably is an effective therapy for liver fibrosis.

Animals↗

PubMed2006

[Inhibitory effects of 10-23 deoxyribozyme targeting ICL gene on the expression of isocitrate lyase and the infection of Mycobacterium tuberculosis in macrophages].

OBJECTIVE: To investigate the inhibitory effects of the 10-23 deoxyribozyme (DRZ) targeting ICL gene on the expression of isocitrate lyase (ICL) and the survival of Mycobacterium tuberculosis in macrophages. METHODS: Five 10-23 DRZ targeting ICL genes (DZ1-DZ5) were designed according to the predicted secondary structure of Mycobacterium tuberculosis ICL mRNA. Their cleavage activity and specificity were identified in cell free conditions. Then Mycobacterium tuberculosis pretreated with DZ4 with or without subinhibitory concentration of isoniazid (INH) were used to infect THP-1 cells. The bacterial burden of the infected THP-1 cells was monitored at indicated times after infection. The effect of 10-23 DRZ on the growth of Mycobacterium tuberculosis in vitro was also assayed by plating Mycobacterium tuberculosis treated with INH alone or DZ4 plus INH on M7H10 agar directly. RESULTS: Four of the five designed 10-23 DRZ, DZ1, DZ3, DZ4 and DZ5 could cleavage ICL mRNA efficiently and specifically. Treating Mycobacterium tuberculosis with 5 micromol/L DZ4 plus subinhibitory concentration of INH decreased the expression of ICL dramatically, by 34.9% - 46.7% (10 microg/L INH, P < 0.01) or 21.9% - 36.9% (5 microg/L INH, P < 0.01) when compared with corresponding concentration of INH alone. The survival of Mycobacterium tuberculosis in THP-1 cells was decreased significantly when Mycobacterium tuberculosis was pretreated with 5 micromol/L DZ4 plus subinhibitory concentration of INH. 4 or 7 days after infection, the bacteria burden in macrophages was decreased from 126.5 x 10(4) CFU, 307.5 x 10(4) CFU to 54.6 x 10(4) CFU, 114.3 x 10(4) CFU (when 10 microg/L INH used) or from 133.0 x 10(4) CFU, 325.4 x 10(4) CFU to 71.7 x 10(4) CFU, 174.4 x 10(4) CFU (when 5 microg/L INH used). 10-23 DRZ showed no obvious effect on the growth of Mycobacterium tuberculosis in M7H10 agar. CONCLUSIONS: INH at the subinhibitory concentration can improve the entry of 10-23 DRZ in Mycobacterium tuberculosis. In the presence of subinhibitory concentration of INH, 10-23 DRZ targeting ICL gene can strongly inhibit the expression of ICL and decrease the survival of Mycobacterium tuberculosis in macrophages.

Antitubercular Agents↗

PubMed2006

[Dynamic changes of plasma VEGF, SDF-1 and peripheral CD34+ cells in patients with acute myocardial infarction].

OBJECTIVE: To investigate the changes in plasma levels of vascular endothelial growth factor (VEGF) and stromal cell-derived factor-1 (SDF-1) and in peripheral CD34(+) cells in patients with acute myocardial infarction (AMI), and explore their role in AMI. METHODS: Enzyme-linked immunoassay (ELISA) was employed for measuring the levels of VEGF and SDF-1 in AMI patients on days 1, 3, 7, 10, and 14 of onset and in normal control subjects. The absolute counts of CD34(+) in the peripheral blood were measured on days 1, 7, and 14 by flow cytometry in AMI patients, with their myocardial enzyme and troponin I detected and electrocardiography (ECG) and echocardiography (UCG) recorded. RESULTS: Peripheral CD34(+) cells obviously increased on day 7 after AMI onset (2.35-/+0.72/microl vs 1.48-/+0.49/micro, P<0.05). VEGF levels were significantly higher in AMI patients than in the control subjects, reaching the peak level and on day 14 (197.56-/+39.87 vs 53.79-/+18.12 pg/ml, P<0.01). SDF-1 level obviously decreased on day 1 after AMI onset (1683.12-/+224.79 vs 2178.67-/+265.34 pg/ml, P<0.01), followed by gradually increased to the control level. Obvious correlation was noted between the level of VEGF on day 7 and the peak level of peripheral CD34(+) cells, and the peak plasma VEGF level was obviously associated with the peak serum CK-MB and troponin I levels. CONCLUSION: The stem cells are mobilized into the peripheral blood in the event of AMI. Obviously increased VEGF level following AMI may persist for at least 2 weeks, whereas SDF-1 level undergoes temporary decrement after AMI. The dynamic changes of VEGF and SDF-1 can be related to the mobilization and homing of the stem cells to the injured myocardium.

Adult↗

PubMed2005

Sim1 and Sim2 are required for the correct targeting of mammillary body axons.

The mammillary body (MB), and its axonal projections to the thalamus (mammillothalamic tract, MTT) and the tegmentum (mammillotegmental tract, MTEG), are components of a circuit involved in spatial learning. The bHLH-PAS transcription factors SIM1 and SIM2 are co-expressed in the developing MB. We have found that MB neurons are generated and that they survive at least until E18.5 in embryos lacking both Sim1 and Sim2 (Sim1(-/-);Sim2(-/-)). However, the MTT and MTEG are histologically absent in Sim1(-/-);Sim2(-/-) embryos, and are reduced in embryos lacking Sim1 but bearing one or two copies of Sim2, indicating a contribution of the latter to the development of MB axons. We have generated, by homologous recombination, a null allele of Sim1 (Sim1(tlz)) in which the tau-lacZ fusion gene was introduced, allowing the staining of MB axons. Consistent with the histological studies, lacZ staining showed that the MTT/MTEG is barely detectable in Sim1(tlz/tlz);Sim2(+/-) and Sim1(tlz/tlz);Sim2(-/-) brains. Instead, MB axons are splayed and grow towards the midline. Slit1 and Slit2, which code for secreted molecules that induce the repulsion of ROBO1-producing axons, are expressed in the midline at the level of the MB, whereas Robo1 is expressed in the developing MB. The expression of Rig-1/Robo3, a negative regulator of Slit signalling, is upregulated in the prospective MB of Sim1/Sim2 double mutants, raising the possibility that the growth of mutant MB axons towards the midline is caused by a decreased sensitivity to SLIT. Finally, we found that Sim1 and Sim2 act along compensatory, but not hierarchical, pathways, suggesting that they play similar roles in vivo.

Animals↗

PubMed2005

Characterization, weathering, and application of sesquiterpanes to source identification of spilled lighter petroleum products.

Biomarkers have become increasingly important for identifying the source of spilled oil, due to their specificity and high resistance to biodegradation. The biomarkers most commonly used in forensic investigations are the high molecular weight (MW) tri- and pentacyclic terpanes and steranes. For lighter petroleum products such as jet fuels and diesels, the refining processes remove most high MW biomarkers from the original crude oil feedstock. The smaller bicyclic sesquiterpanes, however, are concentrated in these products. Sesquiterpanes are ubiquitous components of crude oils and ancient sediments. Examination of GC-MS chromatograms of these bicyclic biomarkers using their characteristic fragment ions (m/z 123, 179, 193, and 207) provides a highly diagnostic means for identifying spilled oil, particularly for lighter refined product samples that are difficult to identify by current techniques. In this work, sesquiterpanes in crude oils and petroleum products are identified and characterized, distributions of sesquiterpanes in oils and refined products are compared, the effects of evaporative weathering on sesquiterpane distributions are examined, and a methodology using diagnostic indices of sesquiterpanes is developed for oil correlation and differentiation. Finally, two case studies are presented to illustrate the unique utility of sesquiterpanes for fingerprinting and identifying unknown diesel spills.

Chromatography, Gas↗

PubMed2005

The flagellar motility of Chlamydomonas pf25 mutant lacking an AKAP-binding protein is overtly sensitive to medium conditions.

Radial spokes are a conserved axonemal structural complex postulated to regulate the motility of 9 + 2 cilia and flagella via a network of phosphoenzymes and regulatory proteins. Consistently, a Chlamydomonas radial spoke protein, RSP3, has been identified by RII overlays as an A-kinase anchoring protein (AKAP) that localizes the cAMP-dependent protein kinase (PKA) holoenzyme by binding to the RIIa domain of PKA RII subunit. However, the highly conserved docking domain of PKA is also found in the N termini of several AKAP-binding proteins unrelated to PKA as well as a 24-kDa novel spoke protein, RSP11. Here, we report that RSP11 binds to RSP3 directly in vitro and colocalizes with RSP3 toward the spoke base near outer doublets and dynein motors in axonemes. Importantly, RSP11 mutant pf25 displays a spectrum of motility, from paralysis with flaccid or twitching flagella as other spoke mutants to wildtype-like swimming. The wide range of motility changes reversibly depending on the condition of liquid media without replacing defective proteins. We postulate that radial spokes use the RIIa/AKAP module to regulate ciliary and flagellar beating; absence of the spoke RIIa protein exposes a medium-sensitive regulatory mechanism that is not obvious in wild-type Chlamydomonas.

Adaptor Proteins, Signal Transducing↗

PubMed2005

Looking for trouble: a search for developmental defects of the hypothalamus.

The hypothalamus is a critical integrator of several homeostatic processes that are required for the survival of vertebrates. Disruption of the development of the hypothalamus thus has the potential of perturbing important physiological processes with lifelong consequences. We review current knowledge about how cell types are specified and circuits are formed within the developing hypothalamus. We emphasize the potential clinical impact of the perturbations of these pathways using the regulation of energy balance as a model. We predict that disruption of hypothalamic development is a common, previously unsuspected cause of disorders of homeostatic processes such as obesity and high blood pressure.

Animals↗

PubMed2005

Dynamic expression of apoptosis-related genes during development of laboratory hepatocellular carcinoma and its relation to apoptosis.

AIM: To explore the expression of p53, bcl-2, bax, survivin and the cell apoptosis during the development of tree shrew hepatocellular carcinoma (HCC), the relationship between expression of these genes, its impact on HCC development, and its relation to cell apoptosis. METHODS: Tree shrew HCC was induced with aflatoxin B1 (AFB1), and regular biopsy of liver tissues was carried out and the biopsy tissues were collected during cancer inducement. Liver biopsy tissue and HCC tissue were collected from 35 pre-cancerous experimental animals at wk 30 and 60 and at the 30th-, 60th-, and 90th-wk. Liver biopsy tissues were collected from 13 blank control animals at wk 30, 60, and 90. Expression of p53, bcl-2, bax, and survivin at each stage was examined by immunohistochemistry method. Apoptotic cells were detected in situ by the terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) technique. RESULTS: The apoptosis rate of normal hepatic cells was extremely low, whereas it increased during the formation of HCC. Expression of the apoptosis-related genes p53, bcl-2, bax, and survivin during the formation of HCC presented an increasing tendency. Expression of p53 did not noticeably relate to that of bcl-2, bax, and survivin, whereas expression of bcl-2 and bax was closely related. In HCC, p53 did not present a distinct relation to cell apoptosis, whereas its high level expression was probably related to liver cell proliferation. Survivin negatively correlated apoptosis index, and its overexpression could inhibit cell apoptosis. CONCLUSION: Apoptosis-related genes p53, bcl-2, bax, and survivin are all related to the occurrence of HCC. The anti-apoptosis effect of bcl-2 is influenced by bax, and ratio bcl/bax reflects more correctly the extent of cell apoptosis.

Aflatoxin B1↗

PubMed2005

Direct liquid chromatography determination of the reactive imine SJG-136 (NSC 694501).

SJG-136 (NSC 694501), 8,8'-[[(propane-1,3-diyl)dioxy]bis[(11aS)-7-methoxy-2-methylidene-1,2,3,11a-tetrahydro-5H-pyrrolo[2,1-c][1,4]benzodiazepin-5-one], which is being developed as a DNA-interactive antitumor agent, contains highly reactive imines in the diazepinone portions of the molecule. Water or alcohol adds readily to the imino moiety to form the corresponding carbinolamine or its alkyl ether, respectively. This sensitivity to protic substances poses a formidable challenge to the formulation and HPLC assay development for the compound. After studying the solution chemistry of SJG-136 and its potential interaction with various stationary phases, two reversed-phase liquid chromatographic assays for the compound have been developed. A direct assay that separates SJG-136 from its water or methanol adducts and an indirect assay that quantifies SJG-136 as its dihydrate adduct are reported. The latter method, which is more practical for drug development, has been validated. It is reproducible (R.S.D.<2%), linear (r2=0.9999) and accurate (within 98-102% recovery), with a lower detection limit of 2.5 ng.

Benzodiazepinones↗

PubMed2005

Two-fluid electroosmotic flow in microchannels.

This paper presents a mathematical model to describe a two-fluid electroosmotic pumping technique, in which an electrically non-conducting fluid is delivered by the interfacial viscous force of a conducting fluid; the latter is driven by electroosmosis. The electrical potential in the conducting fluid and the analytical solution of the steady two-fluid electroosmotic stratified flow in a rectangular microchannel was presented by assuming a planar interface between the two immiscible fluids. The effects of viscosity ratio, hold-up, concentration, and interfacial zeta potential are analyzed to show the potential feasibility of this technique.

Journal Article↗

PubMed2005

On-line combination of capillary isoelectric focusing and capillary non-gel sieving electrophoresis using a hollow-fiber membrane interface: a novel two-dimensional separation system for proteins.

A novel two-dimensional (2D) separation system for proteins was reported. In the system, a piece of dialysis hollow-fiber membrane was employed as the interface for on-line combination of capillary isoelectric focusing (CIEF) and capillary non-gel sieving electrophoresis (CNGSE). The system is similar equivalent to two-dimensional polyacrylamide gel electrophoresis (2D PAGE), by transferring the principal of 2D PAGE separation to the capillary format. Proteins were focused and separated in first dimension CIEF based on their differences in isoelectric points (pIs). Focused protein zones was transferred to the dialysis hollow-fiber interface, where proteins hydrophobically complexed with sodium dodecyl sulfate (SDS). The negatively charged proteins were electromigrated and further resolved by their differences in size in the second dimension CNGSE, in which dextran solution, a replaceable sieving matrix instead of cross-linked polyacrylamide gel was employed for size-dependent separation of proteins. The combination of the two techniques was attributed to high efficiency of the dialysis membrane interface. The feasibility and the orthogonality of the combined CIEF-CNGSE separation technique, an important factor for maximizing peak capacity or resolution elements, were demonstrated by examining each technique independently for the separation of hemoglobin and protein mixtures excreting from lung cancer cells of rat. The 2D separation strategy was found to greatly increase the resolving power and overall peak capacity over those obtained for either dimension alone.

Animals↗

PubMed2005

Hepatitis B virus mutations associated with fulminant hepatitis induce apoptosis in primary Tupaia hepatocytes.

Hepatitis B virus (HBV) core promoter mutations have been implicated in the pathogenesis of fulminant hepatitis B. Due to the limited availability of primary human hepatocytes, the functional characterization of HBV mutants has been performed predominantly in transformed cells, which may not represent ideal model systems for studying virus-cell interactions. We and others have shown that primary hepatocytes of the tree shrew Tupaia belangeri support HBV infection and replication. In this study, we used primary Tupaia hepatocytes to analyze the phenotype of two HBV core promoter mutations that have been associated with a clinical outbreak of fatal fulminant hepatitis. Similar to previous findings in human hepatoma cells, the HBV core promoter mutations resulted in enhanced viral replication and core expression. Surprisingly, however, the presence of the mutations had a marked effect on hepatocyte viability not previously observed in hepatoma cells. Reduced cell viability was found to be due to the induction of apoptosis, as evidenced by caspase-3 activation and nuclear fragmentation. In conclusion, HBV mutants exhibit a novel phenotype in primary hepatocytes distinctly different from previous findings in hepatoma cell lines. This phenotype may have important implications for the understanding of the fulminant clinical course associated with HBV mutations.

Animals↗

PubMed2005

Protocol of capillary isoelectric focusing to separate extremely acidic and basic proteins.

A new set-up was constructed for capillary isoelectric focusing (CIEF) involving a sampling capillary as a bypass fixed to the separation capillary. Sample solutions were subjected to a previously established pH gradient from the sample capillary. Besides performing conventional CIEF, the separation of ampholytic compounds with isoelectric points (p/s) beyond the pH gradient was carried out on this system. This method was termed as pH gradient driven electrophoresis (PGDE) and the basic mathematical expressions were derived to express the dynamic fundamentals. Proteins such as lysozyme, cytochrome C, and pepsin with p/s higher than 10 or below 3 were separated in a pH gradient provided by Pharmalyte (pH 3-10). Finally, this protocol convincingly exhibited its potential in the separation of a solution of chicken egg white.

Animals↗

PubMed2005

Local maximal stress hypothesis and computational plaque vulnerability index for atherosclerotic plaque assessment.

It is believed that atherosclerotic plaque rupture may be related to maximal stress conditions in the plaque. More careful examination of stress distributions in plaques reveals that it may be the local stress/strain behaviors at critical sites such as very thin plaque cap and locations with plaque cap weakness that are more closely related to plaque rupture risk. A "local maximal stress hypothesis" and a stress-based computational plaque vulnerability index (CPVI) are proposed to assess plaque vulnerability. A critical site selection (CSS) method is proposed to identify critical sites in the plaque and critical stress conditions which are be used to determine CPVI values. Our initial results based on 34 2D MRI slices from 14 human coronary plaque samples indicate that CPVI plaque assessment has an 85% agreement rate (91% if the square root of stress values is used) with assessment given by histopathological analysis. Large-scale and long-term patient studies are needed to further validate our findings for more accurate quantitative plaque vulnerability assessment.

Coronary Artery Disease↗

PubMed2005

Quantifying effects of plaque structure and material properties on stress distributions in human atherosclerotic plaques using 3D FSI models.

BACKGROUND: Atherosclerotic plaques may rupture without warning and cause acute cardiovascular syndromes such as heart attack and stroke. Methods to assess plaque vulnerability noninvasively and predict possible plaque rupture are urgently needed. METHOD: MRI-based three-dimensional unsteady models for human atherosclerotic plaques with multi-component plaque structure and fluid-structure interactions are introduced to perform mechanical analysis for human atherosclerotic plaques. RESULTS: Stress variations on critical sites such as a thin cap in the plaque can be 300% higher than that at other normal sites. Large calcification block considerably changes stress/strain distributions. Stiffness variations of plaque components (50% reduction or 100% increase) may affect maximal stress values by 20-50%. Plaque cap erosion causes almost no change on maximal stress level at the cap, but leads to 50% increase in maximal strain value. CONCLUSIONS: Effects caused by atherosclerotic plaque structure, cap thickness and erosion, material properties, and pulsating pressure conditions on stress/strain distributions in the plaque are quantified by extensive computational case studies and parameter evaluations. Computational mechanical analysis has good potential to improve accuracy of plaque vulnerability assessment.

Blood Pressure↗

PubMed2005

Encapsulation and photoluminescent property of [Eu(bpy)2]3+ in mesoporous material HMS.

The photoluminescence properties of europium (III) ions and its complex with 2,2'-bipyridine, [Eu(bpy)2]3+, encapsulated in the hexagonal mesoporous material HMS are reported. X-ray diffraction spectra, ICP analysis, IR spectra, N2 adsorption measurements, and the photoluminescence spectra were used to characterize the corresponding impregnated samples. All the impregnated HMS samples exhibit the typical photoluminescence properties of Eu3+ when excited with a xenon lamp. These results show that HMS is an efficient host lattice for the photoluminescence of the europium (III) ions bound to an appropriate ligand.

Europium↗