Biomedical subjects
Publications and source records attributed to Jiang Bian.
Coumarin and thiocoumarin, which are usually thermally unreactive for dimerization, were dimerized in their inclusion crystalline complexes under thermal and high vacuum conditions.
It has been shown that exogenous antigens can access the MHC class I pathway of professional antigen-processing cells. However, details as to how the MHC class I-peptide complex forms in the presentation pathway are still poorly understood. Here we used MHC class I-peptide-specific antibodies to investigate the formation and intracellular location of class I-peptide complexes in macrophages. We observed that the formation of class I-peptide complexes occurs within a few hours and lasts for another few hours on the cell surface of macrophages following loading with filamentous phage particles. The class I-peptide complexes in the process were co-localized with MHC class II molecules and endocytic system markers. Moreover, endosomal compartments containing class I-peptide complexes were found within intracellular organelles stained by DiOC6 and calnexin. In addition, the cross-presentation of phage particles was transporter associated with antigen processing (TAP)-dependent and sensitive to proteasome inhibitors and NH(4)Cl. These data suggest that endocytosed phage particles may be processed and cross-presented in organelles positive for phagosome and endoplasmic reticulum (ER) markers via a classical ER MHC class I loading mechanism.
Using the recombinant technique in vitro, a new arsenic resistance plasmid pSDRA4 was constructed by subcloning the arsenic resistance genes from plasmid pUM3 into the wide-host-range IncQ plasmid pMMB24 with the hybrid trp-lac ( tac ) promoter, and followed by deleting the regulative gene of the promoter, the lacIQ gene. Then plasmid pSDRA4 was introduced from E. coli into extremely acidophilic obligately chemolithotrophic Acidithiobacillus caldus by conjugative transfer with a frequency of( 1.444 +/- 0.797) x 10(-4), and the engineered strain of Acidithiobacillus caldus (pSDRA4) for biomining was constructed. The successful transfer demonstrates the development of a conjugational system between strains of E. coli and A. caldus. The recombinant plasmid pSDRA4 is stable in A. caldus. Compared with wild type A. caldus, the level of the arsenic resistance of A. caldus (pSDRA4) is greatly raised from 10mmol/L to 45mmol/L.
The TaSi(n) (n=1-13) clusters with doublet, quartet, and sextet spin configurations have been systematically investigated by a relativistic density functional theory with the generalized gradient approximation available in Amsterdam density functional program. The total bonding energies, equilibrium geometries, Mulliken populations as well as Hirshfeld charges of TaSi(n) (n=1-13) clusters are calculated and presented. The emphasis on the stabilities and electronic properties is discussed. The most stable structures of the small TaSi(n) (n=1-6) clusters and the evolutional rule of low-lying geometries of the larger TaSi(n) (n=7-13) clusters are obtained. Theoretical results indicate that the most stable structure of TaSi(n) (n=1-6) clusters keeps the similar framework as the most stable structure of Si(n+1) clusters except for TaSi(3) cluster. The Ta atom in the lowest-energy TaSi(n) (n=1-13) isomers occupies a gradual sinking site, and the site moves from convex, to flatness, and to concave with the number of Si atom varying from 1 to 13. When n=12, the Ta atom in TaSi(12) cluster completely falls into the center of the Si frame, and a cagelike TaSi(12) geometry is formed. Meanwhile, the net Mulliken and Hirsheld populations of the Ta atom in the TaSi(n) (n=1-13) clusters vary from positive to negative, manifesting that the charges in TaSi(n) (n>/=12) clusters transfer from Si atoms to Ta atom. Additionally, the contribution of Si-Si and Si-Ta interactions to the stability of TaSi(n) clusters is briefly discussed. Furthermore, the investigations on atomic averaged binding energies and fragmentation energies show that the TaSi(n) (n=2,3,5,7,10,11,12) clusters have enhanced stabilities. Compared with pure silicon clusters, a universal narrowing of highest occupied molecular orbital-lowest unoccupied molecular orbital gap in TaSi(n) clusters is found.
A new method for constructing nonorthogonal localized molecular orbitals (NOLMOs) is presented. The set of highly localized NOLMOs is obtained by minimization of the spread functional starting from an initial set of canonical orthogonal molecular orbitals. To enhance the stability and efficiency, the centroids of the NOLMOs are constrained to be those of the corresponding orthogonal localized molecular orbitals (OLMOs), which are obtained with the Boys criterion in advance. In particular, these centroid constraints make the optimization for each NOLMO independent of the others, which is an attractive feature for application to large systems. The minimization with the constraints incorporated through the multiplier-penalty function method is stable and efficient in convergence. While exhibiting the classical bonding pattern in chemistry and sharing a spatial distribution similar to that of the corresponding OLMOs, the obtained NOLMOs are more compact than the corresponding OLMOs with about 10%-28% reduction in the value of the spread functional and devoid of the troublesome "orthogonalization tails."
OBJECTIVE: To study the effect of rhTNF-alpha on human sperm mitochondrial function and motility in vitro. METHODS: Fifty-six semen samples collected by masturbation were analyzed according to WHO protocols. Semen samples from 40 healthy men were prepared using Percoll centrifugation. Sperm suspension was diluted to a concentration of 10 x 10(6)/ml in Ham's F10 medium. Sperm samples were incubated with rhTNF-alpha solution (final concentration 0.03 microg/L, 0.06 microg/L, 0.09 microg/L and 0.27 microg/L, respectively) for 0.5 h, 1 h, 2 h, 3 h and 4 h at 37 degrees C in 5% CO2, and comparative studies were made with a control group. Ten microl sperm samples were examined with CASA technique, 250 microl stained in the presence of 10 microg/ml Rh123 and PI, and mitochondrial function analyzed by flow cytometry. RESULTS: Significant differences were found between the experimental groups (final concentration 0.06 microg/L, 0.09 microg/L and 0.27 microg/L) and the control group in viability, straight line velocity, curvilinear velocity, average path velocity, progressive motility of human sperm and the number of spermatozoa with normal mitochondrial function (P < 0.01) except the final concentration 0.03 microg/L group (P > 0.05). Motility of human sperm lowered with the increase of rhTNF-alpha concentration and incubation time, and r values were 0.675, 0.691, 0.762, 0.693, 0.724 and 0.571, 0.594, 0.752, 0.791, 0.816, respectively (P < 0.01). The number of spermatozoa with normal mitochondrial function decreased with the increased rhTNF-alpha concentration and incubation time, and r values were 0.615, 0.643, 0.752, 0.691, 0.754 and 0.532, 0.567, 0.782, 0.692, 0.854, respectively (P < 0.01). CONCLUSION: rhTNF-alpha can reduce human sperm motility function in vitro, possibly by interfering with human sperm mitochondrial function.
OBJECTIVE: To study the relationship of the long-term incidence rate of benign prostate hyperplasia (BPH) after vasectomy to age and time after operation. METHOD: Questionnaire survey, physical examination, and ultrasonography were conducted among 850 healthy males, aged 55 - 76 who underwent vasectomy more than 20 years before and 390 healthy males, aged 53 - 75, who had not undergone vasectomy in Yichang, Hubei province, selected by randomized cluster sampling. The data such as international prostate symptom scoring (IPSS), quality of life (QOL) index, maximum urine flow rate (MFR), and average flow rate (AFR), digital rectal examination (DRE), volume of prostate gland (V), and residual urine (R) were analyzed. RESULTS: The general BPH incidence rate of the vasectomy group was 10.8%, significantly lower than that of the control group (40.8%, P < 0.01). The age-specific BPH incidence rates in the vasetomy group were all significantly lower than those of the control group, especially that of the subjects aged over 70 (10.8% vs. 56.5%, P < 0.001). The BPH incidence rate of those who had undergone vasectomy 25 years or over before was 7.8%, significantly lower than that of those who had undergone vasectomy 20 years before (13.2%, P < 0.05), but not significantly difference from that of those who had undergone vasectomy 30 years or over before (5.5%, P > 0.05). The volumes of prostate gland in all age subgroups were significantly smaller in the vasectomy group than in the control group. CONCLUSION: Vasectomy reduces the incidence rate of BPH significantly.
OBJECTIVES: To investigate the possibility and efficacy of vasoligation and deferent vein ligation in treating and preventing benign prostatic hyperplasia(BPH). METHODS: 40 male pooches were divided into A, B, C and D groups randomly. Each group has 10 pooches group A and B were made into the model of BPH. Two years later, the pooches in group A and C accepted the operation of vasoligation and deferent vein ligation on both sides. Group B and D only accepted the operation of dissection and relieving its deferent duct. Then continuing to feed the 40 pooches after the operation, they were killed another two years later. After taking out their prostates and calculating their volume and weight, the sections of the prostates were checked by microscope to observe their histology and pathology changes. RESULTS: There were significant differences of weight and volume as well as the changes of histology and pathology between group A and group C (P < 0.01). It was the same with group B and D (hyperplasia changes). CONCLUSIONS: Vasoligation and deferent vein ligation before benign prostatic hyperplasia at pooches grow-up stage can reduce the extent of BPH at old age, and treatment after benign prostatic hyperplasia can make prostatic tissue appear different degrees of atrophy.
The efficacy of phage display particles expressing tumor antigen P1A35-43 in inducing protective and therapeutic anti-tumor immune responses were studied. A protective immune response against a lethal progressive P815 mastocytoma tumor cell challenge was established after subcutaneous injection of phage display particles. Furthermore, the vaccine suppressed growth of pre-existing tumors. Immunization with the hybrid phage particles elicited P1A(35-43) specific CTL responses and a Th1-dominated immune response with phage particle-specific secretion of IFN-gamma but not IL-4. Our results indicate that phage display particles might be a useful vaccine form for tumor-associated antigen epitopes in tumor immunotherapy.
Poly(ethyleneglycol) (PEG), anchored at the surface of liposomes via the conjugation to a lipid, is commonly used for increasing the liposome stability in the blood stream. In order to gain a better understanding of the protective properties of interfacial polymers, we have studied the binding of melittin to PEG-lipid-containing membranes as well as the melittin-induced efflux of a fluorescent marker from liposomes containing PEG-lipids. We examined the effect of the polymer size by using PEG with molecular weights of 2000 and 5000. In addition, we studied the role of the anchoring lipid by comparing PEG conjugated to phosphatidylethanolamine (PE) which results in a negatively charged PEG-PE, with PEG conjugated to ceramide (Cer) which provides the neutral PEG-Cer. Our results show that interfacial PEG does not prevent melittin adsorption onto the interface. In fact, PEG-PE promotes melittin binding, most likely because of attractive electrostatic interactions with the negative interfacial charge density of the PEG-PE-containing liposomes. However, PEG-lipids limit the lytic potential of melittin. The phenomenon is proposed to be associated with the change in the polymorphic tendencies of the liposome bilayers. The present findings reveal that the protective effect associated with interfacial hydrophilic polymers is not universal. Molecules like melittin can sense surface charges borne by PEG-lipids, and the influence of PEG-lipids on liposomal properties such as the polymorphic propensities may be involved in the so-called protective effect.
CD8(+) cytotoxic T lymphocytes (CTLs) are now recognized as important mediators of immunity against intracellular pathogens, including human immunodeficiency virus and tumors. How to efficiently evoke antigen-specific CTL responses in vivo has become a crucial problem in the development of modern vaccines. Here, we developed a completely novel CTL vaccine-mimovirus, which is a kind of virus-size particulate antigen delivery system. It was formed by the self-assembly of a cationic peptide containing 18 lysines and a CTL-epitope peptide of HBsAg(28-39), with a plasmid encoding mouse interleukin-12 (IL-12) through electrostatic interactions. We examined the formation of mimovirus by DNA retardation assay, DNase I protection assay, and transmission electron microscopy and demonstrated that mimovirus could efficiently transfer the plasmid encoding IL-12 into mammalian cells such as P815 cells in vitro. Furthermore, it was proved that mimovirus could induce an HBsAg(28-39)-specific CTL response in vivo. Considering its effectiveness, flexibility, and defined composition, mimovirus is potentially a novel system for vaccination against intracellular pathogens and tumors.