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Gang Han

Publications and source records attributed to Gang Han.

18 recordsLinked to original sources
PubMed2006

Chiral translation and cooperative self-assembly of discrete helical structures using molecular recognition dyads.

Complementary diaminopyridine (DAP) and flavin derivatives self-assemble into discrete helically stacked tetrads in hydrocarbon solvents. The self-assembled structure was demonstrated through induced circular dichroism using DAPs with chiral side-chains and flavin with achiral side-chains. Flavin derivatives with chiral side-chains were synthesized; cooperativity in the self-assembly was established through circular dichroism (CD) profiles and melting curves. It was found that placing stereocenters in both recognition units resulted in a strong bisignated profile and enhancement of complex stability, indicative of cooperative self-assembly.

Magnetic Resonance Spectroscopy↗
PubMed2006

Mixed monolayer-protected gold nanoclusters as selective peptide extraction agents for MALDI-MS analysis.

Cationic and anionic nanoparticles selectively target peptides with low and high isoelectric points, respectively. Additionally, their high surface area-to-volume ratios make these nanoparticles (approximately 2-nm core diameter) very efficient extraction and concentration agents. Upon extraction, the peptide-bound nanoparticles can be analyzed by MALDI-MS to provide highly sensitive detection of the targeted peptides. We demonstrate that MALDI-MS can detect peptide concentrations as low as 500 pM from 250-microL solutions using these nanoparticle scaffolds as extraction and concentration agents.

Gold↗
PubMed2006

[Relationship between screening by stratifying cases into groups on prostate specific antigen level and the positive rate of transrectal ultrasound guided systematic sextant prostate biopsy].

OBJECTIVE: To evaluate the detection of prostate cancer in different prostate specific antigen (PSA) level and the predict value of PSA, digital rectal examination (DRE), transrectal ultrasound scan (TRUS) and PSA density (PSAD). METHODS: The clinical data of 634 cases who had underwent transrectal ultrasound guided systematic sextant prostate biopsies between April 1996 to December 2002 due to being suspicious of prostate cancer were retrospectively analyzed. The detection of prostate cancer in different PSA groups, namely PSA < or = 4.0, 4.1-, 10.1-, > 20.0 microg/L, and the predict values of PSA, DRE, TRUS and PSAD were statistically analyzed using t test, chi2 test and logistic regression analysis. RESULTS: The rates of prostate cancer detection in different PSA groups were 11.6%, 26.8%, 39.8% and 68.6%, respectively. The higher the PSA, the higher the rate of prostate cancer detection, the same was the positive predictive value of DRE and TRUS. The sensitivity and specificity of PSA > 4.0 microg/L were 93.0% and 33.0%, and the efficiency of DRE and TRUS were very low. Logistic regression analysis indicated that PSAD was the most risk factor of prostate cancer in the group of PSA 4.1-20.0 microg/L (OR = 687.09 +/- 646.96, P = 0.000). CONCLUSIONS: The rates of prostate cancer detection in different PSA groups are different compared with other countries. The screening roles of DRE and TRUS are dependent on PSA level. Utilization of the screening protocol which to stratify cases into three PSA groups, namely PSA < or = 4.0, 4.1 - 20.0, > 20.0 microg/L, can elevate the positive rate of prostate biopsies without sacrificing cancers detected.

Adult↗
PubMed2006

[The usefulness of percentage of free prostate specific antigen/prostate specific antigen density in the diagnosis of prostate cancer].

OBJECTIVE: To investigate the usefulness of percentage of free prostate specific antigen (FPSA/TPSA) in serum/PSA density [(F/T)/PSAD] in the diagnosis of prostate cancer. METHODS: Two hundred and four patients who had been carried out transrectal ultrasound guided prostate biopsy, were involved in this study. Among them, 90 patients were proved to be suffering from prostate cancer, and other 114 patients were identified as benign prostate hypertrophy. The effect of total serum PSA level, FPSA/TPSA, PSAD and (F/T)/PSAD in the diagnosis of prostate cancer were investigated, and at the same time, selecting patients who should be carried out a prostate biopsy. RESULTS: The mean values of (F/T)/PSAD were significantly lower for patients with prostate cancer in different PSA levels (<4.0, 4.0-, 10.1-, >20.0 microg/L), when compared with benign prostate hypertrophy patients. This difference has arrived statistical significance (P < 0.05). (F/T)/PSAD could provide higher specificity for diagnosing prostate cancer than FPSA/TPSA or PSAD. Among all patients, at the same higher sensitivity (about 90%), the specificity of FPSA/TPSA, PSAD and (F/T)/PSAD was 31.6%, 45.6% and 64.0%, respectively. At the same time, it was suggested that clinicians use different cutoffs for (F/T)/PSAD in different PSA level. When PSA level of patients was no more than 4.0 microg/L, 2.5 as the commended cutoff for (F/T)/PSAD was preferred; if PSA level was between 4.0 microg/L and 20.0 microg/L, 0.8 was a more suitable cutoff; 0.5 also could be taken as an appropriate cutoff in case of PSA level being higher than 20.0 microg/L. CONCLUSIONS: Keeping high sensitivity, using of (F/T)/PSAD can improve the diagnostic specificity of prostate cancer significantly.

Adult↗
PubMed2006

Glutathione-mediated delivery and release using monolayer protected nanoparticle carriers.

We demonstrate here the effective delivery of a dye payload into cells using 2-nm core gold nanoparticles, with release occurring via place exchange of glutathione onto the particle surface. In vitro experiments demonstrate effective release of drug analogues upon addition of glutathione. Cell culture experiments show rapid uptake of nanoparticle and effective release of payload. The role of glutathione in the release process was demonstrated through improved payload release upon transient increase in glutathione levels achieved via introduction of glutathione ethyl ester into the cell.

Delayed-Action Preparations↗
PubMed2006

Stability of gold nanoparticle-bound DNA toward biological, physical, and chemical agents.

Positively charged trimethylammonium-modified mixed monolayer protected clusters (MMPCs) interact with DNA by complementary electrostatic binding, serving as efficient DNA delivery systems. The stability of gold nanoparticle-bound DNA toward biological, physical, and chemical agents is investigated. The MMPC-bound DNA is efficiently protected from DNAse I digestion and experiences nicking/cleavage-induced morphology changes with higher concentrations of DNAse I. Significant protection of MMPC-bound DNA was also observed in a physical sonication assay. However, the MMPC-bound DNA was found to show enhanced cleavage upon exposure to chemically induced radicals. The latter may indicate that bound DNA is bent and wrapped on the surface of the cationic MMPC.

DNA↗
PubMed2006

DNA-binding by functionalized gold nanoparticles: mechanism and structural requirements.

A family of nanoparticles featuring surfaces of varying hydrophobicity was synthesized. The efficiency of DNA-binding was determined, demonstrating in a fivefold modulation in binding a 37-mer DNA strand. Nanoparticle-binding causes a reversible conformational change in the DNA structure, as demonstrated by circular dichroism and fluorescence experiments. Furthermore, the affinity of the nanoparticle for the DNA can be regulated by external agents, though stability of the complex is observed at relatively high ionic strengths.

Circular Dichroism↗
PubMed2006

[Preparation and release behavior of chitosan scaffolds encapsulating proteins loaded in PLGA microspheres].

AIM: To prepare cells scaffolds with the characteristics of sustained release of proteins. METHODS: Chitosan scaffolds was prepared by freeze-drying. Porosity and water content of scaffolds were determined. Bovine serum album (BSA) was selected as a model protein. Poly (lactic-co-glycolic acid) (PLGA) microspheres were prepared by double emulsion solvent evaporation and encapsulated into chitosan scaffolds. The morphology of PLGA microspheres and various scaffolds were observed using scanning electron microscope. Release behavior of BSA from various chitosan scaffolds was investigated. RESULTS: The chitosan scaffold represents porous. At the -70 degrees C of quenching temperature, the porosity and water content of chitosan scaffolds were 78.6% +/- 1.5% and 85.1% +/- 6.2%, respectively. PLGA microspheres can be uniformly encapsulated into scaffolds without any morphology change. Significant sustained release of BSA from PLGA microspheres encapsulated into scaffolds was obtained. The cumulative release at 168 h was only 33.5%, while that of BSA from chitosan scaffolds at 24 h was above 90%. The release behavior can be controlled by adjusting the amount of chitosan in scaffolds and the type of PLGA. CONCLUSION: The novel chitosan scaffolds encapsulating PLGA microspheres proved to be a promising cells scaffolds with controlling the release of growth factors in tissue engineering.

Chitosan↗
PubMed2005

[Clinical research of hemiprosthesis arthroplasty for the treatment of unstable intertrochanteric fractures in elderly patients].

OBJECTIVE: To report the clinical results of hemiprosthesis for unstable intertrochanteric fractures in elderly patients. METHODS: 86 cases (male 35 and females 51) of unstable intertrochanteric fractures in elderly patients were treated with hemiprosthesis arthroplasty in our hospital. The average age was 87 years old (range from 80 to 98 years old). According to the Evans classification of intertrochanteric fractures, there were 31 cases in type IIIA, 35 cases in IIIB and 20 cases in type IV. Most of the patients fell in the room and fractured, with concomitant diseases. After admitted to the hospital, the patients were consulted and treated for the concomitant diseases, and after the general conditions got stable and no absolute contraindications were found, the hemiprosthesis arthroplasty was performed. Almost all of the patients were operated on within 3 days with general anesthesia under the multi-function monitoring. The greater trochanter was reconstructed with figure of 8 wire fixation, the lesser trochanter with figure of 8 wire fixation, the lesser trochanter was fixed with circular wire around proximal femur. The defect within the femoral calcar was filled with bone cement and in a part of the patients, the intertrochanteric fracture was transformed into femoral neck fracture and the femoral calcar was fixed with femoral prosthesis stem. RESULTS: All operations were successful and the duration of the operation was 45 to 70 minutes with an average of 55 minutes. Blood was transfused in 73 patients during the operation between 400-800 ml with an average 450 ml. The patients got out of the bed within 3 days in 33 cases, 4-7 days in 43 cases, more than 8 days in 8 cases, and 2 patients couldn't get out of the bed. The period of hospitalization was between 13 to 27 days with an average of 16.8 days. COMPLICATIONS: 2 patients got slight deep phlebitis, 5 patients showed psychological disorders, and disorders in bacterial spectrum appeared in 3 patients, and after appropriate treatments, the complications gradually recovered and had no effect on the function of the affected extremity. 2 cases died of multiple organ failure during the hospitalization. 59 patients were followed up for 6 to 48 months with an average 16 months. The result was excellent in 17 cases who resumed their activities as before they got fractured, good in 35 cases who could walk with walking aid, fair in 5 cases who could walk with others help, and poor in 2 cases who could not walk. 1 patient died of other diseases 5 months after discharged. No dislocation, loosening or late infections occurred. 88.1% showed excellent or good result. CONCLUSION: It's an effective method to treat the unstable intertrochanteric fractures in elderly patients with hemiprosthesis arthroplasty. The result was satisfactory. It can decrease the complications, reduce the mortality, improve the patient's the living quality, and reduce the burden of the patient's family.

Aged, 80 and over↗
PubMed2005

Expressions of inducible nitric oxide synthase and matrix metalloproteinase-9 and their effects on angiogenesis and progression of hepatocellular carcinoma.

AIM: To determine the expressions of inducible nitric oxide synthase (iNOS) and matrix metalloproteinase-9 (MMP-9) in hepatocellular carcinoma (HCC) and to investigate the relationship between iNOS and MMP-9 expression and their effects on angiogenesis and progression of HCC. METHODS: In this study, we examined iNOS, MMP-9, and CD34 expression in specimens surgically removed from 32 HCC patients and 7 normal liver tissues by immunohistochemical staining. Meanwhile, microvessel density (MVD) was determined as a marker of angiogenesis by counting CD34-positive cells. RESULTS: The positive rates of iNOS and MMP-9 expression were 71.88% (23/32) and 78.13% (25/32) in HCC. MMP-9 expression was significantly correlated with tumor size, capsule status, TNM stage, and risk of HCC recurrence (P = 0.032, P = 0.033, P = 0.007, and P = 0.001, respectively). There was also a significant relationship between iNOS expression and capsule status and risk of HCC recurrence (P = 0.049 and P = 0.004, respectively), but no correlation between iNOS expression and tumor size and TNM stage. There was a positive association between MVD and TNM stage and risk of HCC recurrence (P = 0.037 and P = 0.000, respectively). The count of MVD was significantly different in different iNOS and MMP-9 immunoreactivity groups (F = 17.713 and 17.097, P = 0.000 and P = 0.000, respectively). The examination of Spearman's rank correlation coefficient showed that there was a significant positive correlation between MVD and iNOS, MMP-9 immunoreactivity (r = 0.754 and 0.751, P = 0.000 and P=0.000, respectively). There was also a significant association between MMP-9 and iNOS expression in HCC (P = 0.010). CONCLUSION: Nitric oxide (NO) produced by iNOS could modulate MMP-9 production and therefore contribute to tumor cell angiogenesis and invasion and metastasis in HCC. The strong expression of iNOS and MMP-9 in HCC may be helpful in evaluating the recurrence of HCC, predicting poor prognosis. For patients with strong expression of MMP-9 and iNOS, the optimal treatment scheme needs to be selected.

Adolescent↗
PubMed2005

Tunable inhibition and denaturation of alpha-chymotrypsin with amino acid-functionalized gold nanoparticles.

Water-soluble gold nanoparticles bearing diverse l-amino acid terminals have been fabricated to probe the effect of receptor surface on protein surface binding. The interaction of these nanoparticles with alpha-chymotrypsin (ChT) was investigated by activity assay, gel electrophoresis, zeta-potential, circular dichroism, and fluorescence spectroscopy. The results show that both electrostatic and hydrophobic interactions between the hydrophobic patches of receptors and the protein contribute to the stability of the complex. The microscopic binding constants for these receptor-protein systems are 10(6)-10(7) M(-1), with the capacity of the nanoparticle receptors to bind proteins determined by both their surface area and their surface charge density. Furthermore, it is found that the hydrophilic side chains destabilize the ChT structure through either competitive hydrogen bonding or breakage of salt bridges, whereas denaturation was much slower with hydrophobic amino acid side chains. Significantly, correlation between the hydrophobicity index of amino acid side chains and the binding affinity and denaturation rates was observed.

Amino Acids↗
PubMed2004

[Study on preparation of the inclusion compound of curcumin with beta-cyclodextrin].

OBJECTIVE: The inclusion compound of curcumin with, beta-CD was preparated to increase the solubility and bioavaliability of curcumin. METHODS: Prepare inclusion compound was studied with orthogonal design. The inclusion compound was verified with fluorometry, TLC, and phase solubility. RESULT: The best way to prepare inclusion compound are as follows: the molar ratio between curcumin and, beta-CD is 1:1, temperture is 40 degrees C, reaction time is 2 h. CONCLUSION: Solubility of inclusion compound is 10 times than curcumin.

Biological Availability↗
PubMed2004

Expression of TIMP-3 gene by construction of a eukaryotic cell expression vector and its role in reduction of metastasis in a human breast cancer cell line.

The present study is aimed at studying the gene for TIMP-3, a mammalian tissue inhibitor, by constructing a recombinant eukaryotic cell vector for gene therapy in human breast cancer. We obtained the TIMP-3 gene from the human placent by RT-PCR. TIMP-3 gene was subcloned into pcDNA3.1 vetor from pMD18T vector by means of gene cloning to construct pcDNA3.1 recombinant vector. Human breast cancer cell line MDA-MB-453 was transfected with pcDNA3.1-TIMP3 recombinant vector using lipofectamine reagent. Then the expression of TIMP-3 and the effect on the metastasis of MDA-MB-453 were examined. The correct construction of pcDNA-TIMP3 was identified by means of restriction enzyme analysis, PCR amplication and nucleotide sequencing. Western blotting showed that the transfected cells were able to express TIMP-3, indicating that our construction of the pcDNA-TIMP3 eukaryotic expression vector was constructed successfully. Our experiments further indicated that the potential of metastasis was significantly reduced for the transfected cell line MDA-MB-453.

Breast Neoplasms↗
PubMed2003

Surgical mortality in patients with malignant obstructive jaundice: a multivariate discriminant analysis.

OBJECTIVE: To estimate the operative mortality in patients with malignant obstructive jaundice. METHODS: Twelve risk factors were analyzed using multivariate discriminant analysis in 90 patients who had been operated on. RESULTS: Operative mortality was significantly related to the following factors: age, duration of jaundice, packed RBC volume, white blood cell count and concentration of blood urine nitrogen; it was not significantly related to diseases and types of operation. The following formula was obtained: packed RBC volume x 0.09954-age x 0.04018- blood urine nitrogen x 0.23693-duration of jaundice x 2.07388-WBC count x 0.21118+ 5.26593. With this formula, an operative mortality of 77.8% was predicted. CONCLUSION: With a positive value from the formula, the patient should be operated on; otherwise non-operative treatment is advocated.

Aged↗
PubMed2003

[The reconstruction of three-dimension morphology of proximal femur].

OBJECTIVES: To reconstruct the morphology of the proximal femur and measure the parameters of them by means of the computer-aided design (CAD) in order to provide help to the design and research of the domestic prosthesis, event for the selection of the adapted implant for the doctors before operation. METHODS: The data of 160 healthy Chinese proximal femur images were obtained by the PHLLIP SR7000 computer tomography. The correlative parameters were measured exactly by medical imaging software. Then the imaging data were input into an computerized contouring program which generates the three dimensional coordinates representing periosteal and endosteal contours of the femur for each CT slice. Though the computer-aided design (CAD) software, the three-dimensional solid model was reconstructed by the vectorisation of image contours. In the circumstance of CAD system, the bone axis is defined as the line across the geometric center of the cross-section of the isthmus and 20 mm above the lesser trochanter mid-point. We measured the parameters of the endosteal and periosteal dimensions of the medullary canal. RESULTS: The parameters of the medullary canal measured with the reconstructed normal Chinese femur have significant difference from that measured with the Caucasian's. The extracortical and endosteal parameters of male have significant differences from most of female's. However, there were no significant differences in endosteal width between different age groups in two gender groups. From the proximal to the distal femur, the intersection angles between the longest mediolateral endosteal diameters of the slices and the plane of the femoral neck were increased. CONCLUSIONS: The reconstructive femur contains more information and can be cut at arbitrary levels which means it is facility to the research of the Morphology of the Proximal femur and the measurement of relative parameters. It is necessary to design the prosthesis which fit anatomic parameters of the Chinese femur. It needs to further study whether the gender factor will be considered in the prosthesis design. The angle between the anteversion and the helitorsion at the level 20 mm above the lesser trochanter midpoint should be noticed by the implant designers and doctors.

Aged↗
PubMed2002

The relationship between bone-loss of steroid-induced osteonecrosis and local expression of OPG/OCIF.

OBJECTIVE: To probe the relationship between the osteoprotegerin/osteoclastogenesis inhibitory factor (OPG/OCIF) expression of bone and the relative bone-loss. METHODS: Steroid-induced osteonecrosis-model was reproduced in thirty-one new Zealand hares, and 24 ones were alive 3 days after administration of endotoxin and methylprednisolone. The alive creatures were divided into control group and trial groups randomly. After the creatures being executed, bone-density measurement of the femurs, HE staining, Ca(+ +) staining and OPG/OCIF immunohistochemistry staining were performed, followed by image processing and statistical analysis. RESULTS: In the early period of steroid-induced osteonecrosis, the local OPG/OCIF expression significantly decreased, with a large number of osteoclasts in the local medulla, followed by a progressively bone-loss. CONCLUSION: Corticosteroid could inhibit OPG/OCIF expression in the bone, increase the activity and differentiation of osteoclast relatively, and worsen bone-loss in steroid-induced osteonecrosis.

Bone Density↗
PubMedDate not supplied

Controlled recovery of the transcription of nanoparticle-bound DNA by intracellular concentrations of glutathione.

Positively charged trimethylammonium-functionalized mixed monolayer protected clusters (MMPCs) bind DNA through complementary electrostatic interactions, resulting in complete inhibition of DNA transcription of T7 RNA polymerase. DNA was released from the nanoparticle by intracellular concentrations of glutathione, resulting in efficient transcription. The restoration of RNA production was dose-dependent in terms of GSH, with considerable control of the release process possible through variation in monolayer structure. This work presents a new approach to controlled release of DNA, with potential applications in the creation of transfection vectors and gene regulation systems.

DNA↗