Biomedical subjects

Di Wu

Publications and source records attributed to Di Wu.

At least 55 records · Page 3Linked to original sources

PubMed2006

Royal crown-shaped electride Li3-N3-Be containing two superatoms: new knowledge on aromaticity.

The structure and aromaticity of a royal crown-shaped molecule Li(3)-N(3)-Be are studied at the CCSD(T)/aug-cc-pVDZ level. This molecule is a charge-separated system and can be denoted as Li(3) (2+)N(3) (3-)Be(+). It is found that the Li(3) (2+) ring exhibits aromaticity mainly because the Li(3) (2+) ring can share the pi-electron with the N(3) (-3) ring. The 4n+2 electron counter rule can be satisfied for the Li(3) (2+) subunit if the shared pi valence electron of N(3) (3-) subunit is also taken into account. This new knowledge on aromaticity of a ring from the interactions between subunits is revealed first time in this paper. Li(3)-N(3)-Be can be also regarded as a molecule containing two superatoms (Li(3) and N(3)), which may be named as a "superomolecule." Li(3)-N(3)-Be is a new metal-nonmetal-metal type sandwich complex. The N(3) (3-) trianion in the middle repulses the electron clouds of the two metal subunits (mainly to the Li(3) superatom) to generate an excess electron, and thus Li(3)-N(3)-Be is also an electride. This phenomenon of the repulsion results in: (a) the HOMO energy level increased, (b) the electron cloud in HOMO distended, (c) the area of the negative NICS value extended, and (d) the VIE value lowered. So the superomolecule Li(3)-N(3)-Be is not only a new metal-nonmetal-metal type sandwich complex but also a new type electride, which comes from the interaction between the alkali superatom (Li(3)) and the nonmetal superatom (N(3)).

Journal Article↗

PubMed2006

On the adaptive detection of blood vessels in retinal images.

This paper proposes an automated blood vessel detection scheme based on adaptive contrast enhancement, feature extraction, and tracing. Feature extraction of small blood vessels is performed by using the standard deviation of Gabor filter responses. Tracing of vessels is done via forward detection, bifurcation identification, and backward verification. Tests over twenty images show that for normal images, the true positive rate (TPR) ranges from 80% to 91%, and their corresponding false positive rates (FPR) range from 2.8% to 5.5%. For abnormal images, the TPR ranges from 73.8% to 86.5% and the FPR ranges from 2.1% to 5.3%, respectively. In comparison with two published solution schemes that were also based on the STARE database, our scheme has lower FPR for the reported TPR measure.

Algorithms↗

PubMed2006

Effect of epigallocatechingallate on ultraviolet B-induced photo-damage in keratinocyte cell line.

One type of traditional Chinese medicines, epigallocatechingallate (EGCG) has been commonly used as a clinical and skin health protective ingredient. It has been known to have photo-protective, anti-inflammatory, and anti-oxidant effects. However, little is known about the mechanisms of EGCG on UV-induced photo-aging and photo-carcinogenesis. In the present study, we investigated the photo-protective mechanisms of EGCG on UVB-induced skin damage, including the potency of EGCG to inhibit the UVB-induced cytotoxicity, secretion of cytokine (IL-6 and TNF-alpha), cellular apoptosis, expression of apoptosis-regulatory genes (p53-p21) and c-fos gene in cultured immortalized human keratinocyte HaCaT cells. EGCG treatment decreased UVB- induced cell cytotoxicity and apoptosis. It also inhibited the mRNA expressions of apoptosis-regulatory gene (p53 and p21) and c-fos gene. These results suggest that EGCG may have an inhibitory effect on UVB-induced photo-damage and apoptosis by blocking the cytokine secretion and the mRNA expressions of p53, p21 and c-fos genes.

Apoptosis↗

PubMed2006

A survey on adherence to secondary ischemic stroke prevention.

Reduced adherence and compliance to discharge instructions and protocols could significantly influence the ability of any stroke prevention strategy. The goals of this investigation were to evaluate the adherence to secondary prevention strategies within 1 year after ischemic stroke and to identify possible causes of poor compliance with these strategies. Patients who had suffered either acute ischemic stroke or transient ischemic attacks (TIA) were recruited retrospectively through telephone follow-up. The survey included whether the patient was prescribed antithrombotic treatment at discharge and reasons for non-compliance with this prescription both immediately after discharge and 1 year after discharge. Of 472 (73.8%) patients with detailed clinical data who were finally evaluated in this survey, 326 (69.1%) were still under antithrombotic treatment and 172 (36.4%) underwent the same antithrombotic agent as prescribed when discharged. We found that medical insurance and free medical care were able to promote compliance with medication in stroke patients for secondary prevention, while administration of non-aspirin antithrombotic agents or a poor ability for daily activities (Barthel index, BI) had significantly negative effects on medication compliance in stroke patients. Under the conditions of this observational study, adherence to stroke prevention strategies was poor. Income levels, categories of antithrombotic agents and the personal living ability are closely related to compliance. The results suggest that doctors should pay more attention to the secondary prevention of stroke. We suggest that providing stroke patients with detailed instructions for medication usage, physicians could increase the potential that their secondary prevention of stroke could be increased.

Aged↗

PubMed2006

[Study of the dento-facial features in children of Han nationality with normal occlusion in Shandong district].

PURPOSE: To establish the standard values of roentgengraphic cephalometry in children with normal occlusion in Shandong district and to make the facial model. METHODS: 156 children were selected to take lateral cephalograph, and were divided into two groups: mixed dentition and early permanent dentition. Cephalograms were analyzed for all subjects with WinCeph7.0. Data were obtained for student's t test between the two groups and between males and females. RESULTS: The norms with derivation for all measurement of X ray cephalometrical analysis on hard tissues were established. Meanwhile, the difference between males and females was compared and the facial model of children with normal occlusion was made. CONCLUSION: Gender difference was shown in linear measurements, with greater growth in males in general. The growing tendency of children from mixed dentition to early permanent dentition was that the maxilla of the male grows faster while the mandible of the female grows faster.

Cephalometry↗

PubMed2006

[Clinical features and epidemiological survey of perianal warts in 72 males].

OBJECTIVE: To investigate the clinical features and epidemiological data of 72 cases of male perianal warts. METHODS: Seventy-two cases of perianal warts in our clinic dated from June, 2004 to April, 2006 were enrolled in the study, whose clinical information and epidemiological data were collected and analyzed. RESULTS: Perianal warts were most commonly seen in young and middle-aged men aged from 18 to 45, only 12.5% of whom had homosexual behaviors. Sauna was another predisposing factor of perianal warts in males in China (chi2 = 5.03, P < 0.05). Primary eruptions of the anus and rectum, like perianal pruritus, eczema, anus fissure, and haemorrhoids, often impaired the local integrity of skin/mucosa. Classical condyloma acuminate was found in 61 (84.72%) of patients, who were susceptive to the infections of HPV 6/11, and were flat condylomas related to HPV16/18. Cryotherapy was believed to be one of the most efficient therapeutic choices for flat perianal warts. Suppression of cellular immune response was identified in the patients by comparison between the subgroups of peripheral T cells and the normal control. CONCLUSION: Sauna is an essential predisposing factor of perianal warts in males, while anus sexual intercourse is not the main route of HPV infection. Classical condylomata acuminate constitute the majority of the eruptions, and flat condylomata come next. The study also provides some useful data for understanding the clinical and epidemiological features of perianal warts in Chinese males for the sake of prevention and treatment of the disease.

Adolescent↗

PubMed2006

[Effects of interferon-gamma combined with all-trans retinoic acid on proliferation and differentiation of leukemia cell lines NB4 and MR2].

BACKGROUND & OBJECTIVE: More than 90% patients with acute promyelocytic leukemia (APL) achieve clinical complete remission by using all-trans retinoic acid (ATRA). However, the rapid development of ATRA-resistance has become a problem in treating APL. Many researches indicate that the mechanism of ATRA-resistance is related to lack of some proteins synthesized by interferon (IFN). This study was to explore the possibility and the possible mechanism of treating ATRA-resistant APL with IFN in combination with ATRA. METHODS: Interferon-gamma (IFNgamma) alone or IFNgamma combined with ATRA was used to treat ATRA-sensitive cell line NB4 and ATRA-resistant cell line MR2. Cell proliferation was tested by MTT assay. Light microscope and NBT test were used to evaluate cell differentiation. The expression of promyelocytic leukemia (PML) protein was observed by indirect immune fluorescent method. RESULTS: On the 8th day, the growth inhibition rates of NB4 cells and MR2 cells were significantly higher in combination group than in IFNgamma group and ATRA group (95.2% vs. 68.0% and 85.0%, P<0.05; 51.5% vs. 24.1% and 4.3%, P<0.05). On the 3rd day, the positive rates of NBT in NB4 cells and MR2 cells were significantly higher in combination group than in IFNgamma group and ATRA group (93.3% vs. 19.3% and 74.7%, P<0.05; 31.5% vs. 16.8% and 5.2%, P<0.05). After treatment of IFNgamma, the fluorescent particles in NB4 and MR2 cell nuclei were obviously increased as compared with those in control group. CONCLUSION: IFNgamma and ATRA have synergistic inhibitory effect on the proliferation of NB4 cells and MR2 cells, and can partially induce the differentiation of ATRA-resistant MR2 cells.

Antineoplastic Agents↗

PubMed2006

[Bone marrow mesenchymal cell transplantation reduces left ventricular remodeling in heart failure following acute myocardial infarction].

OBJECTIVE: Bone marrow mesenchymal cell (MSC) transplantation has been shown to improve heart failure but the mechanism and the subsequent effects are unclear. We tested the hypothesis that MSC transplantation reduces left ventricular remodeling through the MMP/TIMP system in heart failure following acute myocardial infarction. METHODS: Female SD rats underwent coronary artery ligation to induce myocardial infarction. Four weeks later, the rats were divided into the test group (n = 7) and the control group (n = 7), respectively. The donor MSCs were harvested and expanded from male SD rats (5 x 10(6) in 50 microl PBS) and injected into the ischemic myocardium, while the control group received the same volume of PBS. Left ventricular morphology was then evaluated in both groups through staining with H&E and Masson's trichrome. Immunohistochemical staining was used to examine the expressions of MMP2 and TIMP1, as well as type I and type III collagens, in the scar zones. The protein levels of MMP2 and TIMP1 were determined by Western blotting. RESULTS: MSC differentiated into fibroblast-like cells at 21 days after transplantation in the test group. In addition, many inflammatory cells infiltrated and aggregated in the scar area, but this effect was reduced at day 7 after transplantation. The following changes were noted in the test group compared to the control group: ejection fraction and shortening fraction were higher [(63.43 +/- 3.97)% vs. (36.20 +/- 3.99)%, (31.71 +/- 1.98)% vs. (18.00 +/- 2.07)%, P < 0.05]; dp/dt(min) was reduced [(-4756.24 +/- 270.00) mm Hg/s vs. -2789.53 +/- 624.13) mm Hg/s, P < 0.05]; the left ventricular thinning ratio was significantly higher [(76.34 +/- 2.66)% vs. (64.37 +/- 2.36)%, P < 0.05]; the infarct size was smaller [(36.19 +/- 0.83)% vs. (42.12 +/- 1.88)%, P < 0.05]; type I collagen expression in the scar area was much higher; type III collagen expression was much lower; MMP2 expression was reduced and TIMP1 expression was increased. CONCLUSION: MSC transplantation led to dynamic changes in the collagen network through regulation of MMP2/TIMP1 system and consequently interrupted the progress of adverse LV remodeling in heart failure following acute myocardial infarction.

Animals↗

PubMed2005

Pharmacokinetics and metabolism of a selective androgen receptor modulator in rats: implication of molecular properties and intensive metabolic profile to investigate ideal pharmacokinetic characteristics of a propanamide in preclinical study.

S-1 [3-(4-fluorophenoxy)-2-hydroxy-2-methyl-N-[4-nitro-3-(trifluoromethyl)phenyl]-propanamide] is one member of a series of potent selective androgen receptor modulators (SARMs) that are being explored and developed for androgen-dependent diseases. Recent studies showed that S-1 holds great promise as a novel therapeutic agent for benign hyperplasia [W. Gao, J. D. Kearbey, V. A. Nair, K. Chung, A. F. Parlow, D. D. Miller, and J. T. Dalton (2004) Endocrinology 145:5420-5428]. We examined the pharmacokinetics and metabolism of S-1 in rats as a component of our preclinical development of this compound and continued interest in structure-activation relationships for SARM action. Forty male Sprague-Dawley rats were randomly assigned to treatment groups and received either an i.v. or a p.o. dose of S-1 at a dose level of 0.1, 1, 10, or 30 mg/kg. S-1 demonstrated a low clearance (range, 3.6-5.2 ml/min/kg), a moderate volume of distribution (range, 1460-1560 ml/kg), and a terminal half-life ranging from 3.6 to 5.2 h after i.v. doses. The oral bioavailability of S-1 ranged from 55% to 60%. Forty phase I and phase II metabolites of S-1 were identified in the urine and feces of male Sprague-Dawley rats dosed at 50 mg/kg via the i.v. route. The two major urinary metabolites of S-1 were a carboxylic acid and a sulfate-conjugate of 4-nitro-3-trifluoromethylphenylamine. Phase I metabolites arising from A-ring nitro reduction to an aromatic amine and B-ring hydroxylation were also identified in the urinary and fecal samples of rats. Furthermore, a variety of phase II metabolites through sulfation, glucuronidation, and methylation were also found. These studies demonstrate that S-1 is rapidly absorbed, slowly cleared, moderately distributed, and extensively metabolized in rats.

Administration, Oral↗

PubMed2005

Humoral immune responses of amphioxus Branchiostoma belcheri to challenge with Escherichia coli.

Humoral parameters of amphioxus Branchiostoma belcheri, including lysozyme, antimicrobial activity, microbial agglutinin and haemagglutinins were measured before and after challenge with Escherichia coli. Humoral fluids from unchallenged B. belcheri had lysozyme, antimicrobial, microbial agglutinating and haemagglutinating activities, which may represent part of the baseline level of innate immunity in this organism. After challenge with E. coli, the lysozyme activity, growth-inhibiting activities against E. coli and Vibrio alginolyticus, microbial agglutinating activities against Micrococcus lysodeikticus, Bacillus subtilis and Staphylococus aureus, and haemagglutinating activities against rabbit and human A and O erythrocytes in the humoral fluids were all increased significantly. In contrast, the agglutinating activities against Vibrio harveyi and E. coli and the haemagglutinating activity against human B erythrocytes in the humoral fluids were reduced in response to E. coli challenge. It appears that the humoral fluids of B. belcheri contain components that are able to differentiate different microbes and different human blood cell types.

Agglutination↗

PubMed2005

The trigonal bipyramidal MN3M species: a new kind of aromatic complex containing a multiple-fold aromatic N3 subunit.

A new kind of aromatic trigonal bipyramidal MN3M (M=Be, B, Mg, Al, and Ca) species, with all real frequencies, is obtained at the MP2/6-311+G(3d) level. The nucleus-independent chemical shift values are -102.16 ppm for the N3 (3-) ring, and -74.09, -79.39, -65.06, -74.44, and -62.33 ppm (at the geometrical center of the trigonal bipyramid) for BeN3Be, BN3B, MgN3Mg, AlN3Al, and CaN3Ca, respectively. Molecular orbital analysis indicates that the regular triangular N3 (3-) ring and each MN3M species have three aromatic six-electron systems (pi, sigma(p), and sigma(s)) and exhibit threefold aromaticity. The CaN3Ca species has a very low vertical ionization energy of 3.64 eV at the CCSD(T)/6-311+G(3d) level, which is even lower than the ionization energy (3.9 eV) of the Cs atom. Therefore, CaN3Ca can be considered as a new superalkali species. A further study on the CaN3CaCl molecule confirms the superalkali characteristics of CaN3Ca. Two interesting phenomena are explored in the MN3M species: the delocalized electron cloud of the N3 subunit is elongated by two M cations, and the electron clouds of two M cations are distended by the N3 (3-) ring.

Journal Article↗

PubMed2005

Genomic instability in radiation-induced mouse lymphoma from p53 heterozygous mice.

Although radiation can directly induce DNA damage and is a known human and animal carcinogen, the number of genetic changes in radiation-induced tumors, and the pathways responsible for generating them, are unknown. We have used high-density BAC arrays covering >95% of the mouse genome for analysis of genomic patterns of aberrations in spontaneous and radiation-induced mouse lymphomas. The majority of radiation-induced tumors exhibit one of three 'signatures' based on gene copy number changes. Some exhibit extensive scrambling of the genome, with very high numbers of recurrent gains and losses. Two other signatures are characterized by excess gains but relatively few losses, or vice versa. Changes in spontaneous tumors often involve whole chromosomes, whereas radiation-induced tumors exhibit a high frequency of localized deletion/amplification events. The number of copy number abnormalities does not correlate with the latency or pathology of the tumors. We propose that specific early events following radiation exposure induce changes in 'caretaker' genes that control specific downstream pathways involved in DNA damage repair. The nature of these early events may determine the overall genomic signature observed in the resulting tumor.

Animals↗

PubMed2005

Heart rate-corrected QT interval duration is significantly associated with blood pressure in Chinese hypertensives.

INTRODUCTION: Many studies demonstrated that a prolonged heart rate-corrected QT interval (QTc) increases the risk of malignant ventricular arrhythmias and sudden death. METHODS: We measured the electrocardiogram and blood pressure of 1480 hypertensive patients and assessed the relationship between the length of QTc and blood pressure. RESULTS: The mean QTc is longer in female than in male participants. There was a positive association between QTc and blood pressure in both men and women. The estimated increase in systolic and diastolic blood pressure for each 100-millisecond increase in QTc was 6.4 and 5.0 mm Hg in men and 3.7 and 2.5 mm Hg in women, respectively. CONCLUSION: Our study demonstrated a significant positive relationship between the QTc interval and baseline blood pressure in a Chinese hypertensive population.

Adult↗

PubMed2005

Li3-O-Li3 molecule: a metal-nonmetal-metal sandwichlike compound with a distending electron cloud.

The D3d and D2d isomers of the Li3-O-Li3 molecule are metal-nonmetal-metal sandwichlike structures that contain two Li3 superalkali atoms. Their geometries and the real frequencies are obtained at the CCSD(T)/aug-cc-pVDZ level. They are different from the traditional types of the nonmetal-metal-nonmetal sandwich compounds. The natural bond orbital calculation and the topological property nabla2rho(r) calculation indicate that they are typical ionic compounds. In two isomers, the O2- anion is sandwiched in between two Li3+ cation rings. However, the different orientations of two Li3+ planes give the D3d isomer its own special characteristics. Under the action of the O2- anion in the center, the valence electrons of the D3d isomer are pushed out from two Li3+ triangle rings. This special interaction causes three phenomena. First, the valence electron clouds are distended. Second, the vertical ionization energy of the D3d isomer is considerably low, 4.39 eV, so that it may also be viewed as a superalkali atom. Third, we find that the D3d isomer owns the out-of-plane aromaticity and the largest negative nucleus-independent chemical shift value (-10.8 ppm) exists at 2.5 A above the center of the Li3+ ring, not at the center of the Li3+ ring like the isolated aromatic Li3+ cation.

Journal Article↗

PubMed2005

Asymmetrical linear structures including three-electron hemibonds or other interactions in the (ABA)-type triatomic cations: Ne3+, (He-Ne-He)+, (Ar-Ne-Ar)+, (Ar-O-Ar)+, (He-O-He)+, and (Ar-He-Ar)+.

By the counterpoise geometry optimization at the level of CCSD(T)aug-cc-pVDZ, the asymmetrical linear structures with all the real frequencies were obtained for the triatomic cations of (ABA)+ type: Ne3+, (He-Ne-He)+, (Ar-Ne-Ar)+, (Ar-He-Ar)+, (He-O-He)+, and (Ar-O-Ar)+. The validity of this optimization method is confirmed by comparing with the method of the potential-energy surface for the calculations of Ne3+ and (He-Ne-He)+. Using the molecular-orbital theory, it is found that the interaction within the triatomic cations is dominated by the contribution from the first two atoms while the contribution from the third atom is small. This result is justified as a direct consequence of forming an asymmetrical linear structure. Specifically, four types of interaction within the triatomic cations are identified: three-electron sigma-type hemibond, three-electron pi-type hemibond, two-electron sigma bond, and the attraction between cation and atoms. For Ne3+, (He-Ne-He)+, and (He-O-He)+ clusters, it is shown that the electron correlation effect supports the asymmetry.

Journal Article↗

PubMed2005

Familial aggregation of bone mineral density and bone mineral content in a Chinese population.

Familial aggregation of bone mineral density (BMD) and bone mineral content (BMC) has been shown in twin and familial studies, but most sample sizes were small. We here report a large familial aggregation study in a Chinese population. A total of 13,973 siblings aged 25-64 years from 3,882 families were enrolled from Anhui, China. We assessed the whole-body, hip and lumbar spine BMD and BMC by dual-energy X-ray absorptiometry (DXA). Intra-class correlation coefficients of BMD and BMC between siblings varied among different skeletal sites and between different age groups of male sib-pairs and premenopausal and postmenopausal female sib-pairs, with a range of 0.228 to 0.397. The sibling recurrence risk ratio (lambdas) of osteoporosis was 2.6 in our population. We also evaluated the joint association of the BMD values of the first siblings and the second siblings with the risk of low BMD (defined as less than the 10th percentile of the same group population) of their younger siblings. If both the first and second siblings' BMDs were in the lowest tertile, the odd ratios (ORs) of low BMD in their subsequent siblings were 8.32 [95% confidence interval (CI) 5.59-12.39)], 8.71 (95% CI 5.74-13.22) and 5.90 (95% CI 3.57-9.76) for total body, total hip and lumbar spine, respectively. This study demonstrates a significant familial aggregation of BMD and BMC in a large sample of rural Chinese adults.

Absorptiometry, Photon↗

PubMed2005

Chronic wasting disease of elk: transmissibility to humans examined by transgenic mouse models.

Chronic wasting disease (CWD), a prion disease affecting free-ranging and captive cervids (deer and elk), is widespread in the United States and parts of Canada. The large cervid population, the popularity of venison consumption, and the apparent spread of the CWD epidemic are likely resulting in increased human exposure to CWD in the United States. Whether CWD is transmissible to humans, as has been shown for bovine spongiform encephalopathy (the prion disease of cattle), is unknown. We generated transgenic mice expressing the elk or human prion protein (PrP) in a PrP-null background. After intracerebral inoculation with elk CWD prion, two lines of "humanized" transgenic mice that are susceptible to human prions failed to develop the hallmarks of prion diseases after >657 and >756 d, respectively, whereas the "cervidized" transgenic mice became infected after 118-142 d. These data indicate that there is a substantial species barrier for transmission of elk CWD to humans.

Animals↗

PubMed2005

Phase-space overlap measures. II. Design and implementation of staging methods for free-energy calculations.

We consider staged free-energy calculation methods in the context of phase-space overlap relations, and argue that the selection of work-based methods should be guided by consideration of the phase-space overlap of the systems of interest. Stages should always be constructed such that work is performed only into a system that has a phase-space subset relation with the starting system. Thus multiple stages are required if the systems of interest are not such that one forms a phase-space subset with the other. Three two-stage methods are possible, termed umbrella sampling, overlap sampling, and funnel sampling. The last is appropriate for cases in which the subset relation holds, but only in the extreme, meaning that one system's important phase space constitutes a very small portion of the others. Umbrella sampling is most suitable for nonoverlap systems, and overlap sampling is appropriate for systems exhibiting partial phase-space overlap. We review recently introduced metrics that characterize phase-space overlap, showing that the performance of the single- and two-stage methods is consistent with the phase-space picture. We also demonstrate that a recently introduced bias-detection measure is effective in identifying inaccuracy in single- and multistage calculations. The examples used are the chemical-potential calculation for a Lennard-Jones liquid at moderate and at high densities, the same for model water at ambient conditions, and a process of charging a neutral ion in water.

Journal Article↗