Biomedical subjects
Publications and source records attributed to Bing Xu.
Two types of therapeutic agents, which have discrete yet complementary functions, self-assemble into nanofibers in water to formulate a new supramolecular hydrogel as a self-delivery biomaterial to reduce the toxicity of uranyl oxide at the wound sites.
This paper reports the synthesis, characterization, and cellular uptake of the conjugate of porphyrin and iron oxide nanoparticles, which may lead to a bimodal anticancer agent that can be used in the combinational treatment of photodynamic therapy (PDT) and hyperthermia therapy (HT).
Bacteriorhodopsin (bR) trimers naturally form two-dimensional hexagonal crystals in purple membrane (PM), which make it very stable. However, the dnaturation of bR was found to occur during a very narrow pH range when the pH was increased above 12.0, as indicated by inactivation of the photochemical cycle observed by flash photolysis kinetic spectra. Here, atomic force microscopy was used to study the surface structural changes of PM during the denaturation process induced by high pH. Together with the absorption and fluorescence spectra, it was found that the structural changes could be divided into three steps. First, some hydrophobic amino acids of bR become exposed to the aqueous environment and PM loses its 2D crystalline structure, transforming into the so-called "nonisland" structure. Second, bR molecules are extracted out of membrane and form protrusions on the surface like islands in the sea; therefore, the "nonisland" structure transforms into the "island" structure. Finally, most bRs break off from the membrane and form large depositions.
A new class of bisindole-based red fluorescent materials was prepared and used as non-doping red emitters to give the devices emitting saturated red colour at about 650 nm with a chromaticity coordinate of (x = 0.64, y = 0.34), matching the CIE 1931 standard red color very well.
On the basis of a fundamental property of nanoparticles, the self-assembling at a liquid-liquid interface to form "colloidosomes", a heterogeneous reaction takes place on the exposed surface of the nanoparticles to produce the heterodimers of two distinct nanospheres, which can be modified by two different functional molecules in a particle-specific manner.
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Ortho phthalic anhydride was modified with long chain alcohol (1-docosanol) to its corresponding monodocosyl phthalate (22-Phth). Subsequently, three novel lanthanide (Eu(3+), Tb(3+), and Dy(3+)) complexes with the long chain monodocosyl phthalate were synthesized and characterized by elemental analysis and Infrared spectra. The photophysical properties of these complexes were studied in detail with ultraviolet-visible absorption spectra, low temperature phosphorescence spectra and fluorescent spectra. The triplet state energy of 22-Phth was determined to be around 25,000 cm(-1) from the maximum phosphorescent peak at 400 nm, suggesting 22-Phth is suitable for the sensitization of the luminescence of Eu(3+), Tb(3+), and Dy(3+). The fluorescence excitation and emission spectra for these lanthanide complexes of the three ligands take agreement with the above predict from energy match principle.
Ortho-phthalic anhydride was modified with long chain alcohol (1-hexadecanol, 1-octadecanol and 1-eicosanol) to their corresponding mono-L phthalate (L=hexadecyl, octadecyl and eicosyl), i.e. monohexadecyl phthalate (16-Phth), monooctadecyl phthalate (18-Phth), and monoeicosyl phthalate (20-Phth), respectively. Nine novel lanthanide (Eu(3+), Tb(3+) and Dy(3+)) complexes with these three mono-L phthalate ligands were synthesized and characterized by elemental analysis and IR spectra. The photophysical properties of these complexes were studied in detail with various spectroscopes such as ultraviolet-visible absorption spectra, low temperature phosphorescence spectra and fluorescent spectra. The ultraviolet-visible absorption spectra show some band shifts with the different chain-length of phthalate monoester and homologous lanthanide complexes. From the low temperature phosphorescent emission, the triplet state energies for these three ligands were determined to be around 22,650 cm(-1) (16-Phth), 23,095 cm(-1) (18-Phth) and 22,400 cm(-1) (20-Phth), respectively, suggesting they are suitable for the sensitization of the luminescence of Eu(3+), Tb(3+) and Dy(3+). The fluorescence excitation and emission spectra for these lanthanides complexes of the three ligands take agreement with the above predict from energy match.
OBJECTIVE: To construct a mutant enhanced green fluorescence protein (pEGFP) human telomerase reverse transcriptase (hTERT) gene expression vector (pEGFP-hTERT), to observe its expression in transfected human bladder cancer cell line T24 and its role in the molecular regulatory mechanisms of telomerase, and to provide a new target gene for bladder cancer therapy. MATERIALS AND METHODS: Polymerase chain reaction (PCR) amplification was performed using primers based on the gene sequence of hTERT. The PCR product was cloned into plasmid pGEMT-T Easy and the sequence of mutant hTERT gene analysed. A recombinant mutant hTERT vector (pEGFP-hTERT) was constructed at the EcoR I and Sal I sites of the pEGFP-C1 vector. After transfecting the fusion gene into T24 cells by the method of calcium phosphate-DNA co-precipitation, we detected steady expression of the GFP-hTERT fusion protein by fluorescent-light microscopy. Changes in the proliferation of T24 cells were detected by light microscopy, and beta-galactosidase staining correlated with senescence. RESULTS: Identification of pEGFP-hTERT by enzyme digestion showed that the mutant hTERT fragment had been cloned into EcoR I and Sal I sites of the pEGFP-C1 vector. Steady expression of GFP-hTERT fusion protein was located in the nucleus of transfected cells. Positive expression senescence-associated beta-galactosidase staining in transfected cells increased gradually with extended cultured time, and their growth was suppressed. CONCLUSION: The recombinant mutant vector (pEGFP-hTERT) was successfully constructed and expressed steadily in T24 cells. The mutant-type hTERT gene suppresses the proliferation of T24 cells by a competitive effect on telomerase activity. This suggests that the hTERT gene might be a suitable gene target for bladder cancer therapy.
Ectomycorrhizal fungal communities can be structured by abiotic and biotic factors. Here, we present evidence for community structuring by species interactions. We sampled ectomycorrhizas and forest floor seven times during a 13-month period. The presence of various ectomycorrhizal fungal species was determined for each sample, and species co-occurrence analyses were performed. For both ectomycorrhizas and forest floor samples there was significantly less co-occurrence among species within the community than expected by chance, mostly because of negative associations involving Cenococcum geophilum or Clavulina cinerea. For some species pairs, there was significantly more co-occurrence than expected by chance. Both nitrogen and tannin additions to the forest floor altered some interactions among species. The causes of these nonrandom distributions are currently unknown. Future investigations on competition, antibiosis, parasitism and facilitation among ectomycorrhizal fungal species appear to be warranted.
Ectomycorrhizal fungal communities have been characterized in a number of ways. Here we compare colonized root-tip and mycelia views of an ectomycorrhizal fungal community. Ectomycorrhizal fungi, both as mycelia and colonized root tips, were identified in soil samples taken from a pine plantation. We determined that for some ectomycorrhizal fungal species multiple root tips from a single soil sample were not independent. Therefore in the comparison of root-tip and mycelia views, we considered species to be present or absent from each soil sample irrespective of the number of root tips colonized by the species. We observed 39 ectomycorrhizal fungal species in total, but 12 were observed exclusively as mycelia and 11 exclusively colonizing root tips. The relative frequencies of 10 species occurring as both mycelia and root tips were not independent of the method of observation. Our results suggest that ectomycorrhizal fungal species differ in their spatial distributions on root tips, and that root-tip and mycelia views of the community are different.
This review discusses the recent development of multivalent antibiotics as potential therapeutic agents against infections caused by antimicrobial drug resistant microbes. The discussion focuses on vancomycin because of its important clinical relevance and well-elucidated molecular mechanism of antimicrobial drug resistance. The first section recounts the increased occurrence of vancomycin resistance in the world; the second section briefly discusses the mechanistic study of vancomycin resistance; the third section presents the currently established design principles of multivalent vancomycins; the fourth section examines the structural-activity relationships of multivalent vancomycins; the fifth section describes relevant studies on multivalent antibiotics; and the last section summarizes advantages and limitations of multivalent antibiotics.
OBJECTIVE: To evaluate the diagnostic value of multi-slice spiral CT (MSCT) for plasma cell mastitis. METHODS: Radiographs of MSCT for forty-six patients with plasma cell mastitis diagnosed by pathological examination were reviewed. RESULTS: The findings of MSCT of plasma cell mastitis could be divided into four types, including the inflammation type, the abscess type, the sinus and fistula type, and the mixed type, and each type had its radiographic characteristics. CONCLUSION: MSCT is helpful for diagnosing plasma cell mastitis and should be used as an examination of first choice for the patients.
OBJECTIVE: To explore the possibility of using autologous bone marrow mesenchymal stem cells (BMSC) as a vehicle to deliver recombinant adeno-associated virus 2-mediated enhanced green fluorescent protein (rAAV-2-eGFP) in vitro, therefore to find an alternative solution for gene therapy of hematological malignancy. METHODS: BMSCs isolated from the bone marrow of patients with acute myelogenous leukemia (AML) at the onset of disease were infected by rAAV-2-eGFP at different multiplicity of infection (MOI=10(2), 10(3), 10(4), 10(5), 10(6), and 10(7), respectively). Phase-contrast fluorescent microscope and flow cytometry were employed to evaluate the expression of enhanced green fluorescent protein (eGFP). RESULTS: Ten to fourteen days after the transfection, eGFP expression began to be detected and the transfection efficiency ranged between 0.3% to 2%, which failed to be increased with the increase of MOI. The transduced eGFP could maintain a long-term stable expression in vitro in the 61 days of observation, and from 12 to 33 days after transfection, eGFP percentage underwent a decrease from the initial 1.16% to 0.5%-0.6% and maintained this expression level till 61 days after transfection. CONCLUSION: rAAV can be used with BMSCs for in vitro gene therapy, but the poor transfection efficiency of these cells remains a significant obstacle for its further application.
OBJECTIVE: To explore the association between chimerism, minimal residual disease (MRD) and relapse after sex-mismatched allogeneic hematopoietic stem cell transplantation (allo-HSCT) for leukemia. METHODS: Fifty-seven patients with leukemia received allogeneic hematopoietic stem cell grafts from HLA-matched or partially matched, but sex-mismatched donors. Chimeric status and MRD were detected by dual-color interphase fluorescence in situ hybridization (I-FISH) using X/Y sex chromosome centromere DNA probe and bcr/abl dual fusion DNA probe, respectively, at different time points after transplantation. SPSS software was used to analyse the correlation between chimeric status, MRD and relapse. RESULTS: In comparison with karyotype analysis, I-FISH was of higher sensitivity in detecting sex chromosome and bcr/abl fusion gene. Chimeric status was negatively correlated with MRD (r=-0.9690, P<0.01). In the early times of transplantation (within 3 months), mixed chimerism had higher relapse rate than did complete chimerism. Chimeric status and MRD were correlated with leukemic relapse (r=-8240, P<0.01; r=-0.9040, P<0.01). The decrease in chimeric status occurred before leukemic relapse in hematology. CONCLUSION: I-FISH is a more specific and sensitive test for monitoring MRD after transplantation. The clinical value of sex chromosome is identical to that of the special tumor gene for monitoring MRD after transplantation. Chimeric status is negatively correlated with MRD. Chimeric status and MRD are associated with leukemic relapse. The decrease in chimeric status is considered a mark of leukemic relapse after transplantation.
To investigate the relationship between the single nucleotide polymorphism (SNPs) of the bcr and abl gene and chronic myelogeous leukemia (CML), the 9 sequence-tagged sites (STS) in bcr and abl gene were screened by DNA pooling and denaturing high performance liquid chromatography (dHPLC), and the results were varified by sequencing. The results showed that the polymorphism sites were detected in 4 out of the 9 STS fragments and there were 3 bases different from the reference sequence found in 3 fragments. In conclusion, the novel SNP in U07000 fragment shows significantly different frequencies between CML and controled people.
OBJECTIVE: To analyze Fms-like tyrosine kinase 3 (FLT3) gene and FLT3 internal tandem duplication (ITD) mutation in acute lymphoblastic leukemia (ALL) patients of different immunological subtypes. METHODS: Polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) was used to detect FLT3 gene and FLT3/ITD mutation in 63 ALL cases. RESULTS: Among the 63 ALL cases, FLT3 gene was detected in 41 (61.5%) cases. The positivity rate of FLT3 gene in pre-pre B-lineage ALL, pre-B-ALL, B-lineage ALL and T-lineage ALL cases were 93.3% (14/15), 77.8% (14/18), 41.7% (5/12) and 28.6% (4/14), respectively. The positivity rate of FLT3 gene was significantly higher in pre-pre B-ALL/pre B-ALL subtypes (84.8%) than in B-ALL subtypes (41.7%, P<0.005), and the rate was significantly higher in B-ALL subtypes (73.3%) than in T-ALL subtypes (28.6%, P<0.001). Two cases (3.2%) were found to have FLT3/ITD mutation, which were also positive for myeloid antigen expression and diagnosed as acute mixed-lineage leukemia, showing leukocytosis and high percentage of bone marrow blast cells with poor prognosis. CONCLUSIONS: FLT3 gene can be detected in both B-and T-lineage ALL patients, but more frequently in the former. In B-lineage ALL patients, FLT3 gene is more frequent in cases with undifferentiated than those with differentiated blast cells. FLT3/ITD is rarely detected in ALL patients and FLT3/ITD mutation detection might be helpful to identify the genotypes and evaluate the prognosis of acute leukemia.
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