Biomedical subjects

Hui Ding

Publications and source records attributed to Hui Ding.

At least 19 recordsLinked to original sources

PubMed2006

Chaetominine, a cytotoxic alkaloid produced by endophytic Chaetomium sp. IFB-E015.

Chaetominine (1), an alkaloidal metabolite with a new framework, was characterized from the solid-substrate culture of Chaetomium sp. IFB-E015, an endophytic fungus on the apparently healthy Adenophora axilliflora leaves. Its structure was determined by a combination of its spectral data and single-crystal X-ray diffraction analysis, with its absolute configuration elucidated by Marfey's method. Chaetominine was more cytotoxic than 5-fluorouracil against the human leukemia K562 and colon cancer SW1116 cell lines. [structure: see text]

Antibiotics, Antineoplastic↗

PubMed2006

Physicochemical attack against solid tumors based on the reversal of direction of entropy flow: an attempt to introduce thermodynamics in anticancer therapy.

BACKGROUND: There are many differences between healthy tissue and growing tumor tissue, including metabolic, structural and thermodynamic differences. Both structural and thermodynamic differences can be used to follow the entropy differences in cancerous and normal tissue. Entropy production is a bilinear form of the rates of irreversible processes and the corresponding "generalized forces". Entropy production due to various dissipation mechanisms based on temperature differences, chemical potential gradient, chemical affinity, viscous stress and exerted force is a promising tool for calculations relating to potential targets for tumor isolation and demarcation. METHODS: The relative importance of five forms of entropy production was assessed through mathematical estimation. Using our mathematical model we demonstrated that the rate of entropy production by a cancerous cell is always higher than that of a healthy cell apart from the case of the application of external energy. Different rates of entropy production by two kinds of cells influence the direction of entropy flow between the cells. Entropy flow from a cancerous cell to a healthy cell transfers information regarding the cancerous cell and propagates its invasive action to the healthy tissues. To change the direction of entropy flow, in addition to designing certain biochemical pathways to reduce the rate of entropy production by cancerous cells, we suggest supplying external energy to the tumor area, changing the relative rate of entropy production by the two kinds of cells and leading to a higher entropy accumulation in the surrounding normal cells than in the tumorous cells. CONCLUSION: Through the use of mathematical models it was quantitatively demonstrated that when no external force field is applied, the rate of entropy production of cancerous cells is always higher than that of healthy cells. However, when the external energy of square wave electric pulses is applied to tissues, the rate of entropy production of normal cells may exceed that of cancerous cells. Consequently, the application of external energy to the body can reverse the direction of the entropy current. The harmful effect brought about by the entropy flow from cancerous to healthy tissue can be blocked by the reversed direction of entropy current from the irradiated normal tissue around the tumor.

Journal Article↗

PubMed2006

Ultrasound absorption and entropy production in biological tissue: a novel approach to anticancer therapy.

UNLABELLED: The entropy production of tumorous cells is higher than that of normal cells, and entropy flow is therefore directed from tumorous toward healthy cells. This results in information concerning the cancer propagating into the surrounding normal tissue. However, ultrasound absorption results in additional entropy production in tissues. The entropy mechanism possibly provides a basis for a novel approach to anticancer therapy through the use of ultrasound irradiation. METHODS: Through the calculation of ultrasound-induced entropy production and comparison of the theoretical results with the experimental data on ultrasound absorption in biological tissues, we have demonstrated that ultrasound absorption will increase the entropy in normal tissue more efficiently than in tumorous tissue due to the more acidic nature of the latter. Consequently, the direction of entropy flow between these two kinds of cells may be reversed on exposure to ultrasound. CONCLUSION: The higher entropy accumulation of normal cells during ultrasound irradiation may possibly lead to a change in the original direction of entropy flow and avoid the propagation of information on the cancer into the normal tissues. We suggest that low-intensity, low-frequency ultrasound irradiation may be an efficient tool for the therapy of solid tumors.

Journal Article↗

PubMed2006

RNA interference effectively inhibits mRNA accumulation and protein expression of hepatitis C virus core and E2 genes in human cells.

RNA interference (RNAi) has been widely used for the analysis of gene function and represents a new promising approach to develop effective antiviral drugs. In this study, several small interfering RNAs (siRNAs) corresponding to two structural genes (core and E2) of hepatitis C virus (HCV) were designed and in vitro transcribed to explore the possibility of silencing these two genes. The plasmids pEGFP-C and pEGFP-E2, which contain the EGFP reporter gene and the core or E2 gene as silencing targets, were co-transfected with siRNAs into HEK 293T cells. At various time points of post-transfection, core and E2 expression levels were detected by fluorescence microscopy, flow cytometry, Western blotting, and real-time quantitative PCR. The results showed that the mean fluorescence intensity, protein expression, and RNA transcripts of siRNAs transfected cells were significantly reduced. This may provide an approach for the development of novel prophylactic or therapeutic agents for HCV infection.

Blotting, Western↗

PubMed2006

Lead and cadmium in leaves of deciduous trees in Beijing, China: development of a metal accumulation index (MAI).

Lead and cadmium uptake was investigated for common deciduous street trees in Beijing in this study. Species having Cd accumulation included Populus tomentosa, Sophora japonica and Catalpa speciosa. P. tomentosa had the highest ratios between leaf and soil Cd (0.848), followed by S. japonica (0.536), C. speciosa (0.493), Paulownia tomentosa (0.453) and Juglans regia (0.415). Pb levels were high in leaves of C. speciosa, J. regia and Pa. tomentosa. S. japonica had the highest ratio between leaf Pb and soil Pb (0.146), followed by Pa. tomentosa (0.143), Ginko biloba (0.103) and C. speciosa (0.095). A predictive foliar metal accumulation index (MAI) was developed and C. speciosa was calculated to have the highest MAI value (53.8). This suggests that C. speciosa would be a good choice for planting in areas of Beijing where soil contamination with Cd and Pb may be a problem.

Cadmium↗

PubMed2006

Radiosensitization by a modified nucleotide that produces DNA interstrand cross-links under hypoxic conditions.

This paper describes the reactivity of a molecule that combines two desirable chemical processes into one molecule for the first time. Interstrand cross-links (ISCs) are an effective family of lesions produced by cytotoxic agents that target DNA. For instance, ISCs are the source of mitomycin C's cytotoxicity. Radiosensitizing agents are molecules that enhance DNA damage produced by ionizing radiation, especially under O2-deficient conditions. Phenyl selenide 1 is the first example of a modified nucleotide that can be incorporated in DNA by polymerases, which produces ISCs when DNA containing it is exposed to gamma-radiolysis under O2-deficient conditions. These experiments suggest that 1 could be useful as a novel type of radiosensitizing agent.

DNA↗

PubMed2006

Oxygen independent DNA interstrand cross-link formation by a nucleotide radical.

A 5-(2'-Deoxyuridinyl)methyl radical (1) was independently generated from three photochemical precursors and is the first example of a DNA radical that forms interstrand cross-links. Oxygen labeling experiments support generation of 1 by all precursors. Interstrand cross-links are produced upon irradiation of DNA containing any of the precursors. Cross-linking occurs via reaction with the opposing 2'-deoxyadenosine and is independent of O(2). The independence of cross-link formation on O(2) is explained by kinetic analysis, which shows that the radical reacts reversibly with O(2). Examination of the effects of glutathione on cross-link formation under anaerobic conditions suggests that adoption of the syn-conformation by 1 is the rate-limiting step in the process. Interstrand cross-link formation is reversible in the presence of a good nucleophile. The stability of the interstrand cross-link suggests that the isolated molecule is a rearrangement product of that formed in solution. The rearrangement is a consequence of the isolation procedure but also occurs slowly in solution. Oxygen independent cross-link formation may be useful for the purposeful damage of DNA in hypoxic tumor cells, where O(2) is deficient.

Base Sequence↗

PubMed2006

Dual activation in asymmetric allylsilane addition to chiral N-acylhydrazones: method development, mechanistic studies, and elaboration of homoallylic amine adducts.

[reaction: see text] Chiral N-acylhydrazones derived from commercially available 4-benzyl-2-oxazolidinone provide a rigid, conformationally restricted template to impart facial selectivity in additions to C=N bonds. In the presence of indium(III) trifluoromethanesulfonate [In(OTf)3], N-acylhydrazones undergo highly diastereoselective fluoride-initiated additions of allylsilanes (aza-Sakurai reaction). Mechanistic studies including control experiments and comparisons with allyltributylstannane, allylmagnesium bromide, and allylindium species implicate a dual activation mechanism involving addition of an allylfluorosilicate species to a chelate formed from In(OTf)3 and the chiral N-acylhydrazone. The N-N bonds of the adducts are readily cleaved in a two-step protocol to provide synthetically useful homoallylic N-trifluoroacetamides. Further elaboration of the latter compounds through Wacker oxidation and olefin metathesis provides diversely functionalized building blocks and expands the potential applications of this C-C bond construction approach to asymmetric amine synthesis.

Acetamides↗

PubMed2006

Synthesis and cytotoxic evaluation of a series of genistein derivatives.

Thirty genistein (= 5,7-dihydroxy-3-(4-hydroxyphenyl)-4H-1-benzopyran-4-one; GEN) derivatives were synthesized from genistein through a facile approach in high yields. Compounds 9, 11, 12, 23-30 were reported for the first time, while 13-22 have already been reported in our recent paper. The cytotoxic activities of these compounds were evaluated against a human nasopharyngeal epidermoid tumor cell line KB. Compounds 7-9, 12, 14, 16-19, 21, 24, 27, 29 showed remarkable antitumor activities in vitro, which was comparable with 5-fluorouracil, an anticancer drug. On the basis of the obtained experimental data, structure-effect relationships were discussed.

Cell Line, Tumor↗

PubMed2006

Synthesis and cytotoxic evaluation of a series of resveratrol derivatives.

A total of 17 resveratrol (=(E)-5-[2-(4-hydroxyphenyl)ethenyl]benzene-1,3-diol) derivatives were synthesized from resveratrol (RES) through a facile approach. Among them, 13 compounds, 2 and 6-17, were reported for the first time, while 1 and 3-5 had already been reported several years ago. The cytotoxic activities of these compounds were evaluated against human nasopharyngeal epidermoid tumor cell line KB, and compounds 1 and 8-11 showed strong anticancer activities in vitro, comparable with that of 5-fluorouracil, an anticancer drug. On the basis of the experimental data obtained, structure-activity relationships are discussed.

Antineoplastic Agents, Phytogenic↗

PubMed2006

Two-step fluorescence screening of CD21-binding peptides with one-bead one-compound library and investigation of binding properties of N-(2-hydroxypropyl)methacrylamide copolymer-peptide conjugates.

Using the one-bead one-compound (OBOC) combinatorial method, four heptapeptide ligands of CD21 receptor, a cell surface marker of malignant B cell lymphoma, were identified with an innovative two-step fluorescence screening method to overcome the limitation caused by autofluorescence of TentaGel resin. The binding affinities of selected peptides, YILIHRN (B1), PTLDPLP (B2), and LVLLTRE (B3), were in the micromolar region as determined by a fluorescence quenching assay. Peptide B1 was conjugated to N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer via spacers of different lengths, composed of one to four repeats of the 8-amino-3,6-dioxaoctanoic acid (A) group. The evaluation of the biorecognizability of HPMA copolymer-B1 conjugates by the CD21 receptor revealed that increasing the number of repeats of A in the spacer from one to three resulted in continuous improvements in the biorecognition by the CD21 receptor; the increase from three to four repeats showed no significant effect. This work showed the potential of the OBOC combinatorial approach to select peptide ligands as targeting moieties for CD21 specific polymeric drug carriers.

Acrylamides↗

PubMed2006

Isoform of vascular endothelial cell growth inhibitor (VEGI72-251) increases interleukin-2 production by activation of T lymphocytes.

The objective of this study is to investigate the characteristics of the recombinant variant of human vascular endothelial cell growth inhibitor, VEGI72-251, and compare its biological activities with that of its prototype VEGI24-174. The recombinant plasmid containing the variant VEGI72-251 gene was constructed and expressed in Escherichia coli. The effects of the expressed VEGI72-251 on cell proliferations were checked in the human umbilical vein endothelial cell line and certain tumor cell lines (ECV304 and B16). The inhibition of VEGI72-251 on angiogenesis was detected in the chorioallantoic membrane of chick embryos. In comparison with VEGI24-174, the recombinant human VEGI72-251 seems to have no effect on the proliferation of endothelial cells and the angiogenesis of the chorioallantoic membrane in vitro. An enzyme-linked immunosorbent assay-based method was used for the measurement of interleukin-2 (IL-2) production by peripheral blood monocytes (PBMCs) treated with VEGI72-251. PBMCs were pretreated with VEGI72-251 (1.25-12.50 microg/ml) for 24 h in vitro, and the IL-2 concentration in PBMC medium was increased from 354 pg/ml to 1256 pg/ml. It can be concluded that VEGI72-251 is able to increase the level of human IL-2 production by the activation of T lymphocytes. Differing from VEGI24-174 on anti-angiogenesis, VEGI72-251 may serve as an anti-cancer factor through its activation of T lymphocytes.

Animals↗

PubMed2006

[Relationship between depression symptoms and stress in occupational populations].

OBJECTIVE: To explore the relationship between the depression symptoms and occupational stress in occupational populations. METHODS: Depression symptoms were measured by using the center for epidemiological survey-depression scale. The occupational stress instrument were employed to investigate the stressors, personalities, social support, and coping strategies as well as the subject's age, length of service, sex, educational level and marriage status. Chi(2) test was used for analyzing the difference of depression. The multiple covariance analysis was used for testing the difference of stressors, personalities, social support, and coping strategies among the groups with different scores of depression. The variables obtained in the optional prediction equation were identified by multiple stepwise regression analysis. RESULTS: The incidence rate of definite depression symptoms was 40.2%. The total average score was 21.74 +/- 8.99. Henan province had the highest incidence rate of depression symptoms, 43.8%, Hebei 39.4%, and Beijing the lowest, 23.4%. The male workers had the higher incidence rate of depression symptoms, 43. 0% than female, 35.4% (P < 0.01). The older group had the lower incidence rates of depression symptoms, compared with the younger group (P < 0.01). The workers divorced or with the bereft spouse had the higher incidence rate of depression symptoms than the workers married and unmarried (P < 0.05). The workers with middle school education had the higher incidence rates of depression symptoms than those with master degree. Incidence rates in the most occupational groups were more than 30%. The significant difference was shown between the different jobs (P < 0.01). The difference of the adjusted means among three groups of different depression score were analyzed. The results showed the workers with definite depression symptoms had the higher scores than the other two groups in physical factors, role ambiguity, role conflict, job monotony, mental load, responsibility for persons, job future ambiguity, job hazards, type A behavior and work locus of control, and social support (P < 0.05, P < 0.01). The former had the lower scores than the other two groups in the scores of promotion, participation, autonomy, task identity, feedback, friendship opportunity, speed control, training adequacy, challenge, self-esteem, organizational commitment, and coping strategies. Fifteen variables entered the predictive equation of depression score explaining 33.1% of variance. CONCLUSION: There are serious mental health problems in the occupational population in our country. Stressors and personalities affect the mental health.

Adolescent↗

PubMed2006

[Study on the maternal mortality ratio from 1995 to 2004 among residential and migrant women in Beijing].

OBJECTIVE: To analyze the maternal mortality ratio (MMR) of residential and migrant women in Beijing. METHODS: A retrospective study from 1995 to 2004 was performed to analyze data from the maternal death cases. RESULTS: The MMR of resident and migrant of Beijing from 1995 to 2004 were 17.9 and 51.3 per ten thousand respectively. The main reasons of maternal deaths among residents were embolism (21.2%), hypertensive disorder complicating pregnancy (18.3%), postpartum hemorrhage (14.4%) and ectopic pregnancy/heart disease (9.6%). The main reasons of migrant maternal deaths were postpartum hemorrhage (25.2%), embolism (19.7%), hypertensive disorder complicating pregnancy (17.3%) and liver disease (9.5%). The avoidable deaths were accounted for 18.9%. CONCLUSION: The MMR in Beijing local residents was close to that in developed countries. To further reduce MMR in Beijing would depend on the better administration of related issues among floating population. Poor quatily delivery must be banned together with strengthening the training programs on health workers. It is also important to improve the knowledge and skills of medical staff for rescuing the complications of pregnancy and ectopic pregnancy.

China↗

PubMed2005

Catalytic effects of inorganic acids on the decomposition of ammonium nitrate.

In order to evaluate the catalytic effects of inorganic acids on the decomposition of ammonium nitrate (AN), the heat releases of decomposition or reaction of pure AN and its mixtures with inorganic acids were analyzed by a heat flux calorimeter C80. Through the experiments, the different reaction mechanisms of AN and its mixtures were analyzed. The chemical reaction kinetic parameters such as reaction order, activation energy and frequency factor were calculated with the C80 experimental results for different samples. Based on these parameters and the thermal runaway models (Semenov and Frank-Kamenestkii model), the self-accelerating decomposition temperatures (SADTs) of AN and its mixtures were calculated and compared. The results show that the mixtures of AN with acid are more unsteady than pure AN. The AN decomposition reaction is catalyzed by acid. The calculated SADTs of AN mixtures with acid are much lower than that of pure AN.

Calorimetry↗

PubMed2005

Charge couple device-based system for 3-dimensional real time positioning on the assessment of segmental range of motion of lumbar spine.

OBJECTIVE: To observe the tested results of the segmental range of motion (ROM) of lumbar spine by charge couple device (CCD)-based system for 3-dimensional real-time positioning (CCD system), and to analyze its clinical significance. METHODS: Seven patients with lumbar joint dysfunction and 8 healthy subjects were tested twice by the CCD-based system with an interval of 10 min. RESULTS: The ROM of the patients was obviously lesser than that of the healthy subjects. The measuring data of segmental ROM of lumbar spine by CCD system is correlated significantly to the same data checked later on the same subjects in every direction of the movements. The differences between two checks are usually less than 1 degree. CONCLUSION: Specially designed CCD based system for 3-dimensional real-time positioning could objectively reflect the segmental ROM of lumbar spine. The system would be of great clinical significance in the assessment of the biomechanical dysfunction of lumbar spine and the effect of the treatment applied.

Computer Systems↗

PubMed2005

[A study of gait recognition based on kinematics and kinetics parameters].

In order to recognize people by their gait, we propose a pattern recognizing method based on kinematics and kinetics parameters. The feature extraction methods of joint angle and vertical ground reaction force (VGRF) were given. 14 healthy male subjects participated in this experiment. The experimental results showed that the correct classification rates (CCR) was 87.1% at k = 1 and 90% at k = 3 (k-nearest neighbor) based on joint angle recognition; the CCR was 85.7% at k = 1 and 80% at k = 3 based on VGRF recognition. The multivariate analysis of the experimental data proved the feasibility of gait recognition. The principal component analysis and curves of VGRF also showed that the instant of foot strike plays an important role in gait recognition.

Adult↗

PubMed2005

[The frequency features and application of edge detection differential operators in medical image].

Edge detection is an absolutely necessary step in medical image processing, and the use of differential operators to detect edge is one of the most common and effective methods. In this paper are analyzed the frequency features of the Roberts operator, Prewitt operator, Sobel operator and Laplacian operator from the viewpoint of frequency domain, and it is proposed that the frequency features of the differential operators should be considered when differential operator is being used and/or constructed. Because edge detection operator is sensitive to the edge type, the appropriate operator should be adopted in different edge type detection. Finally, the importance and necessity of selecting edge detection operator are validated in the MRI image edge processing.

Algorithms↗