Biomedical subjects

C Wan

Publications and source records attributed to C Wan.

At least 19 recordsLinked to original sources

PubMed2006

Abnormal changes of plasma acute phase proteins in schizophrenia and the relation between schizophrenia and haptoglobin (Hp) gene.

In this study we focused on detecting schizophrenia related changes of plasma proteins using proteomic technology and examining the relation between schizophrenia and haptoglobin (Hp) genotype. We investigated plasma proteins from schizophrenic subjects (n = 42) and healthy controls (n = 46) by two-dimensional gel electrophoresis (2-DE) in combination with mass spectrometry. To further reveal the genetic relationship between acute phase proteins (APPs) and schizophrenia disease, we tested Hp alpha1/Hp alpha2 (Hp 1/2) polymorphism and two single nucleotide polymorphisms (SNPs) of Hp, rs2070937 and rs5473, for associations with schizophrenia in the Chinese Han population. With the relatively high number of samples for 2-DE work, we found that four proteins in the family of positive APPs were all up-regulated in patients. In genetic association study, we found significant associations existing between schizophrenia and Hp polymorphisms, Hp 1/2 and rs2070937 variants. Schizophrenia is accompanied by both an altered expression of Hp protein and a different genotype distribution of Hp gene, demonstrating that Hp is associated with schizophrenia. The results from proteomic and genomic aspects both indicate that acute phase reaction is likely to be an aetiological agent in the pathophysiology of schizophrenia, but not just an accompanying symptom. The positive APPs are schizophrenic related proteins, with the highly concordant results on four positive APPs.

Acute-Phase Proteins↗

PubMed2006

Obesity risk associated with the K121Q polymorphism of the glycoprotein PC-1 gene.

BACKGROUND: Obesity is considered to be a multifactorial trait resulting from the combined influence of genetic and environmental determinants. Insulin resistance plays an important role in the development of obesity. Plasma-cell membrane differentiation antigene-1 (PC-1) inhibits insulin receptor signalling when overexpressed and thus causes insulin resistance. PC-1 gene polymorphism might be associated with adipocyte metabolism disturbance and energy imbalance. The purpose of this study was to determine whether K121Q polymorphism in PC-1 gene is involved in obesity susceptibility in Chinese Han population. METHODS: The genotype of the polymorphism was determined using polymerase chain reaction-restriction fragment length polymorphism analysis for 338 unrelated subjects of Beijing, China. Their Body mass index (BMI), plasma glucose, total cholesterol, triglyceride, high-density lipoprotein cholesterol (HDL), free fatty acid (FFA) and insulin level were measured. Chi-square analyses were applied to test the significance differences in genotypic and allelic frequencies. Association studies were undertaken using the t-test and logistic regression analyses. RESULTS: The obese had significantly higher frequency of KQ/QQ genotype or Q allele than non-obese in females (26.7% vs. 10.9%, p = 0.014 and 13.3% vs. 5.5%, p = 0.021). Significant elevation of insulin amongst the Q121 carrier women in obesity individuals and higher FFA level of Q121 carrier men in non-obese controls (BMI < or = 23 kg/m2) were observed. Binary logistic regression analysis revealed that PC-1 genotype together with higher glucose, total cholesterol, triglyceride and serum HDL were independently associated with the presence of obesity. CONCLUSIONS: The observed genotype distributions revealed a significant association of PC-1 K121Q with obesity. PC-1 Q121 carriers are more likely to be insulin-resistant or get fatter in respect to KK subjects and carriers of the Q allele are at higher risk for the development of obesity in female.

Adult↗

PubMed2005

The role of mPer1 in morphine dependence in mice.

Investigations using Drosophila melanogaster have shown that the circadian clock gene period can influence behavioral responses to cocaine, and the mouse homologues, mPer1 and mPer2, modulate cocaine sensitization and reward. In the present study, we applied DNAzyme targeting mPer1 to interfere the expression of mPer1 in CNS in mice and studied the role of mPer1 on morphine dependence. We found that the DNAzyme could attenuate the expression of mPer1 in CNS in mice. Mice treated with DNAzyme and morphine synchronously did not show preference to the morphine-trained side, whereas the control group did. In contrast, mice treated with DNAzyme after morphine showed preference to the morphine-trained side as well as the control group did. These results indicate that drug dependence seems to be influenced at least partially by mPer1, but mPer1 cannot affect morphine dependence that has been formed.

Animals↗

PubMed2005

Relationship between the regulatory region polymorphism of human tissue kallikrein gene and essential hypertension.

Ten alleles with length and nucleotide sequence variations were identified in the regulatory region of human tissue kallikrein gene. This present study aimed to study the polymorphisms of the regulatory region of human tissue kallikrein gene of the Chinese and investigate the relationship of the polymorphisms with essential hypertension. A case-control study was conducted in 200 hypertensive and 200 normotensive subjects of unrelated Chinese Han origin. All subjects were aged from 30 to 70 years and had no history of diabetes mellitus, kidney failure, or thyroid gland disease. The alleles were detected by polymerase chain reaction (PCR) and genotyping was performed with allele-specific oligonucleotide analysis (ASO). Data from the essential hypertensive and control subjects were statistically analysed by the Student's t-test and chi2-test. The age- and gender-matching of the groups were accurate. The case group and the control group were in Hardy-Weinberg equilibrium at this locus (cases, P=0.313; control subjects, P=0.457). There were nine alleles among the case and control groups, and the allele frequencies were found to be significantly different between cases and controls (chi2=25.701, P<0.001). The genotype frequencies were also significantly different (chi2=70.100, P<0.001) between these two groups. In conclusion, there are polymorphisms in the regulatory region of human tissue kallikrein gene in the Chinese Han people. Differences in both allele frequencies and genotype frequencies between these two groups have provided evidence towards the association of hypertension with the polymorphisms in this studied site.

Asian People↗

PubMed2004

Use of a quantitative gene expression assay based on micro-array techniques and a mathematical model for the investigation of chlamydial generation time.

Chlamydia is an important pathogen which possesses a unique developmental cycle. We used real-time PCR technology to measure gene transcript levels in Chlamydia trachomatis strain L2. By measuring 16S rRNA transcript levels, and developing a mathematical model of the chlamydial developmental cycle fitting the data, we predict an average generation time of approximately 2.6 h. Additionally, potentially this modelling also provides the foundation for the application of emerging micro-array technology in which identification of the gene signals that trigger a chlamydial body to start replicating or transform to its infectious form can be made possible.

Chlamydia trachomatis↗

PubMed2002

Novel PCR-EIA method for the detection of Chlamydia pneumoniae in respiratory specimens.

We report the development of a microtitre plate-based PCR-EIA assay (ELAHA; Enzyme Linked Amplification and Hybridization Assay) for the sensitive and specific detection of Chlamydia pneumoniae in sputum samples from patients with chronic obstructive airways disease (COAD). Following PCR amplification of a segment of the chlamydial heat shock 60 protein gene, the 587 bp sized amplicon is captured onto the streptavidin coated surface of a microtitre plate using a C. pneumoniae specific biotinylated probe and the level of captured product is subsequently determined via a colorimetric reaction using an automated plate reader. The ELAHA is a simple, rapid and inexpensive method for detection of low levels of infectious agents and is readily adaptable to current clinical laboratory equipment. The assay was evaluated with a cohort of hospital respiratory patients: (i) COAD patients with acute exacerbation, (ii) COAD patients without exacerbation (stable) and (iii) a non-respiratory control group. The ELAHA produced 6/12 (50%) C. pneumoniae positives in the COAD with exacerbation group, 3/13 (23%) positives in the COAD without exacerbation group and only 1/6 (17%) positives in the control non-respiratory group. This sensitive and robust PCR-EIA method can provide clinically relevant diagnostic evidence of current C. pneumoniae infection contributing to serious respiratory tract diseases such as COAD.

Case-Control Studies↗

PubMed2001

The anticancer drug-DNA complex: femtosecond primary dynamics for anthracycline antibiotics function.

The anthracycline-DNA complex, which is a potent agent for cancer chemotherapy, has a unique intercalating molecular structure with preference to the GC bases of DNA, as shown by Rich's group in studies of single-crystal x-ray diffraction. Understanding cytotoxicity and its photoenhancement requires the unraveling of the dynamics under the solution-phase, physiological condition. Here we report our first study of the primary processes of drug function. In a series of experiments involving the drug (daunomycin and adriamycin) in water, the drug-DNA complexes, the complexes with the four nucleotides (dGTP, dATP, dCTP, and dTTP), and the drug-apo riboflavin-binding protein, we show the direct involvement of molecular oxygen and DNA base-drug charge-separation-the rates for the reduction of the drug and dioxygen indicate the crucial role of drug/base/O(2) in the efficient and catalytic redox cycling. These dynamical steps, and the subsequent reactions of the superoxide product(s), can account for the photoenhanced function of the drug in cells, and potentially for the cell death.

Animals↗

PubMed2001

Femtosecond dynamics of a drug-protein complex: daunomycin with Apo riboflavin-binding protein.

In this contribution, we report studies of the primary dynamics of the drug-protein complexes of daunomycin with apo riboflavin-binding protein. With femtosecond resolution, we observed the ultrafast charge separation between daunomycin and aromatic amino acid residues of the protein, tryptophan(s). Electron transfer occurs from tryptophan(s) to daunomycin with two reaction times, 1 ps and 6 ps, depending on the local complex structure. The formation of anionic daunomycin radical is crucial for triggering a series of chemical reactions in redox cycling. One of the subsequent reactions is the reduction of dioxygen to form active superoxide by the reduced daunomycin. This catalytic process was found to occur within 10 ps. In the absence of dioxygen, charge recombination takes a much longer time, more than 100 ps. These results, along with similar findings in DNA and nucleotides, elucidate that the ultrafast generation of reduced daunomycin radicals by photoactivation is a primary step for the observed photoenhancement of drug cytotoxicity by several orders of magnitude. We also studied the dependence of the dynamics on protein conformations at different ionic strengths and denaturant concentrations. We observe a sharp transition from the tertiary structure to the unfolding state at 2 M of denaturant concentration.

Carrier Proteins↗

PubMed2001

Giant Hall effect in nonmagnetic granular metal films.

Nearly 3 orders of magnitude enhancement in the Hall coefficient is observed in Cu(x)-(SiO(2))(1--x) granular films. This large enhancement of the Hall coefficient not only is significantly larger than the prediction of the classical percolation theory, but also occurs at a metal concentration identified to be the quantum percolation threshold. Measurements of the electron dephasing length and magnetoresistance, plus the TEM characterization of microstructures, yield a physical picture consistent with the mechanism of the local quantum interference effect.

Journal Article↗

PubMed2001

An amplified fragment length polymorphism map of the silkworm.

The silkworm (Bombyx mori L.) is a lepidopteran insect with a long history of significant agricultural value. We have constructed the first amplified fragment length polymorphism (AFLP) genetic linkage map of the silkworm B. mori at a LOD score of 2.5. The mapping AFLP markers were genotyped in 47 progeny from a backcross population of the cross no. 782 x od100. A total of 1248 (60.7%) polymorphic AFLP markers were detected with 35 PstI/TaqI primer combinations. Each of the primer combinations generated an average of 35.7 polymorphic AFLP markers. A total of 545 (44%) polymorphic markers are consistent with the expected segregation ratio of 1:1 at the significance level of P = 0.05. Of the 545 polymorphic markers, 356 were assigned to 30 linkage groups. The number of markers on linkage groups ranged from 4 to 36. There were 21 major linkage groups with 7-36 markers and 9 relatively small linkage groups with 4-6 markers. The 30 linkage groups varied in length from 37.4 to 691.0 cM. The total length of this AFLP linkage map was 6512 cM. Genetic distances between two neighboring markers on the same linkage group ranged from 0.2 to 47 cM with an average of 18.2 cM. The sex-linked gene od was located between the markers P1T3B40 and P3T3B27 at the end of group 3, indicating that AFLP linkage group 3 was the Z (sex) chromosome. This work provides an essential basic map for constructing a denser linkage map and for mapping genes underlying agronomically important traits in the silkworm B. mori L.

Animals↗

PubMed2001

[Influence of different clipping intensity and R/FR ratio in light radiation on tillering of weeping lovegrass].

Pot experiment with weeping lovegrass was conducted laboratory in the Department of Rangeland, Wildlife and Fisheries Management, Texas Tech University in 1996. The plants grown in green house were used to study the effect of different clipping intensities on tillering, and those grown in laboratory were used to study the interaction between different R/FR(red/farred) ratio of the light reaching to the lower strata of the canopy and different clipping intensities on tillering. The results show that increasing clipping intensity decreased the net gain tillers, bt R/FR ratio had no significant effect on tillering, except no clipping treatment. The compensatory growth effect of tillering did not existed at all clipping intensities, but the elongation speed of young leaves quickened with clipping intensities. It is suggested that suitable utilization, intensified utilization and no utilization were all not beneficial to the growth and development of weeping lovegrass.

Light↗

PubMed2001

[A pilot study on the value of duplex polymerase chain reaction method in early diagnosis of Legionella pneumonia].

OBJECTIVE: To investigate the value of duplex polymerase chain reaction (DPCR) in early diagnosis of Legionella pneumonia by detecting Legionella DNA in sputum and bronchoalveolar lavage fluid(BALF). METHODS: During the process of DPCR, two different sets of oligonucleotide primers were simultaneously used to amplify 386bp 16SrRNA gene fragment and 206bp mip gene fragment. These two primers were designed according to the sequences of 16SrRNA gene and mip gene of Legionella. The sputum and BALF of patients from two groups, including a Legionella pneumonia group (n = 15) and an ordinary pneumonia group (n = 31) were collected at early course of the disease. All of the samples were detected with DPCR for Legionella DNA. Simulated samples were also detected to investigate the sensitivity of the method for testing clinical samples. RESULTS: All the samples collected from the Legionella pneumonia patients, including 25 of sputum,and 8 of BALF showed positive DPCR. The results of DPCR, which could distinguish Legionella pneumophila from non-pneumophila Legionella spp. to some degree, were in good accordance with those of the specific serum antibodies. All of the samples from the ordinary pneumonia group including 40 of sputum and 16 of BALF demonstrated negative DPCR. Different samples of the same patient showed the same DPCR results. The lowest detection level of simulated sputum sample was the same as that of simulated BALF sample, being 1 x 10(3) cfu/ml. CONCLUSIONS: This preliminary study showed that DPCR had satisfactory sensitivity, specificity and stability for detecting Legionella DNA in sputum and BALF. The method is of value in early diagnosis of Legionella pneumonia. Its wide use for clinical work requires further investigation.

Adult↗

PubMed2001

[Investigation on an outbreak of Legionnaires' disease caused by Lboz in a suburb of Beijing].

OBJECTIVE: To demonstrate the infectious rates and incidence rates through epidemiological investigation. METHODS: Serum samples from 203 new soldiers were detected from Lboz by TAT. RESULTS: Infectious rates was 33.00% (67/203), and the incidence rates was 8.87% (18/203) with 2 cases of pneumonic type and 16 cases of pontiac fever type. CONCLUSION: The results suggested that an outbreak of Legionnaires' desease caused by Legionella bozemanii (Lboz) took place in a suburb of Beijing. However the report of the outbreak caused by Lboz had not been found in related references.

China↗

PubMed2000

Femtosecond direct observation of charge transfer between bases in DNA.

Charge transfer in supramolecular assemblies of DNA is unique because of the notion that the pi-stacked bases within the duplex may mediate the transport, possibly leading to damage and/or repair. The phenomenon of transport through pi-stacked arrays over a long distance has an analogy to conduction in molecular electronics, but the mechanism still needs to be determined. To decipher the elementary steps and the mechanism, one has to directly measure the dynamics in real time and in suitably designed, structurally well characterized DNA assemblies. Here, we report our first observation of the femtosecond dynamics of charge transport processes occurring between bases within duplex DNA. By monitoring the population of an initially excited 2-aminopurine, an isomer of adenine, we can follow the charge transfer process and measure its rate. We then study the effect of different bases next to the donor (acceptor), the base sequence, and the distance dependence between the donor and acceptor. We find that the charge injection to a nearest neighbor base is crucial and the time scale is vastly different: 10 ps for guanine and up to 512 ps for inosine. Depending on the base sequence the transfer can be slowed down or inhibited, and the distance dependence is dramatic over the range of 14 A. These observations provide the time scale, and the range and efficiency of the transfer. The results suggest the invalidity of an efficient wire-type behavior and indicate that long-range transport is a slow process of a different mechanism.

2-Aminopurine↗

PubMed2000

Evaluation of neural network models with generalized sensitivity analysis

A sensitivity analysis method for discovering characteristic features of the input data using neural network classification models has been devised. The sensitivity is the gradient of the neural network model response function, and because neural network models are nonlinear, the gradient depends on the point where it is evaluated. Two criteria are used for measuring the sensitivity. The first criterion calculates the sensitivity or gradient of the neural network output with respect to the average of the objects that comprise each class. The second criterion measures the average sensitivity of the class objects. The sensitivity analysis was applied to temperature-constrained cascade correlation network models and evaluated with sets of synthetic data and experimental mobility spectra. The neural network models were built using temperature-constrained cascade correlation networks (TCCCNs). A weight constraint was devised for the output units of the network models. This method implements weight decay with conjugate gradient training and yields more sensitive neural network models. Temperature-constrained hidden units furnish more sensitive network models than networks without constraints. By comparing the sensitivities of the class mean input and the mean sensitivity for all the inputs of a class, the individual input variables may be assessed for linearity. If these two sensitivities for an input variable differ by a constant factor, then that variable is modeled by a simple linear relationship. If the two sensitivities vary by a nonconstant scale factor, then the variable is modeled by higher order functions in the network. The sensitivity method was used to diagnose errors in the training data, and the test for linearity indicated a TCCCN architecture that had better predictability.

Journal Article↗

PubMed2000

Fundus microvascular flow monitoring during retrograde cerebral perfusion: an experimental study.

BACKGROUND: Retrograde cerebral perfusion (RCP) through the superior vena cava was clinically introduced as a supportive technique to protect the brain during deep hypothermic circulatory arrest. This study searched for a direct monitor of cerebral blood flow to evaluate the effect of cerebral perfusion. METHODS: Retinal microvascular perfusions were studied in six piglets using fundus fluorescein angiography (FFA) and color Doppler sonography before cardiopulmonary bypass and retrograde cerebral perfusion during deep hypothermic circulatory arrest. RESULTS: FFA showed initial filling of the fundus venae in 2.5 minutes, and complete filling in 4.5 minutes with partial filling of the arteriae. Arteriae completely filled in 8 minutes, and all of the arteriae and venae filled from 15 to 17 minutes. Color Doppler sonography showed that flow signals were detected in all of the fundus vessels during RCP. CONCLUSIONS: FFA and color Doppler sonography are direct and sensitive methods for observing cerebral blood flow and assessing the effect of cerebral perfusion.

Animals↗

PubMed2000

[Modification of surface of Dacron materials by UV irradiation for prevention of microbial adhesion].

UV irradiation grafting method was used to modify the surface of Prosthetic Valve materials (Dacron) for prevention of bacteria-adhesion, and PEG was introduced to the surface of Dacron by this method. The result showed that the chemical magnifying effect of PEG improved the grafting of heparin on the material surface. This method can obviously reduce the number of adherent bacteria.

Bacterial Adhesion↗

PubMed2000

[Researches on surface modification for prevention of bacterial adhesion to implanting biomaterials].

The failure of operation caused by biomaterials centered infections (BCI) has seriously restricted the clinical application of biomaterials. Two mechanisms of bacterial adhesion and the relationship between surface free energy of bimaterials and bacterial adhesion are introduced and discussed in this paper. Increasing the surface free energy can improve (decrease) the adhesion of some kinds of bacteria. At last, some methods of the surface modification are reviewed.

Bacterial Adhesion↗