Biomedical subjects
Publications and source records attributed to W Luo.
The contents of Zn, Cu, Fe, Mn and Ni in five groups of Suxiaoweiningchongii were determined by AAS. The results showed that he Fe content is the highest and Cu is the lowest, and the reduced order of contents from highest to lowest is Fe to Zn to Mn to Ni to Cu. The relationship between the trace elements in Suxiaoweiningchongji and the curative effect was discussed.
We present new limits on low mass accelerator-produced pointlike Dirac magnetic monopoles trapped and bound in matter surrounding the D0 collision region of the Tevatron at Fermilab (experiment E-882). In the context of a Drell-Yan mechanism, we obtain cross section limits for the production of monopoles with magnetic charge values of 1, 2, 3, and 6 times the minimum Dirac charge of the order of picobarns, some 100 times smaller than found in similar previous Fermilab searches. Mass limits inferred from these cross section limits are presented.
Phospholamban (PLB) can be phosphorylated at Ser(16) by cyclic AMP-dependent protein kinase and at Thr(17) by Ca(2+)-calmodulin-dependent protein kinase during beta-agonist stimulation. A previous study indicated that mutation of S16A in PLB resulted in lack of Thr(17) phosphorylation and attenuation of the beta-agonist stimulatory effects in perfused mouse hearts. To further delineate the functional interplay between dual-site PLB phosphorylation, we generated transgenic mice expressing the T17A mutant PLB in the cardiac compartment of the null background. Lines expressing similar levels of T17A mutant, S16A mutant, or wild-type PLB in the null background were characterized in parallel. Cardiac myocyte basal mechanics and Ca(2+) kinetics were similar among the three groups. Isoproterenol stimulation was associated with phosphorylation of both Ser(16) and Thr(17) in wild-type PLB and Ser(16) phosphorylation in T17A mutant PLB, whereas there was no detectable phosphorylation of S16A mutant PLB. Phosphorylation of Ser(16) alone in T17A mutant PLB resulted in responses of the mechanical and Ca(2+) kinetic parameters to isoproterenol similar to those in wild-type myocytes, which exhibited dual-site PLB phosphorylation. However, those parameters were significantly attenuated in the S16A mutant myocytes. Thus, Ser(16) in PLB can be phosphorylated independently of Thr(17) in vivo, and phosphorylation of Ser(16) is sufficient for mediating the maximal cardiac responses to beta-adrenergic stimulation.
Enamel biomineralization is a complex process that involves interactions between extracellular matrix proteins. To identify proteins interacting with tuftelin, a potential nucleator of enamel crystallites, the yeast two-hybrid system was applied to a mouse tooth expression library and a tuftelin-interacting protein (TIP) was isolated for further characterization. Polyclonal antibodies were prepared against two recombinant variants of this protein. Both antibodies identified a major protein product in tooth organs at 39 kDa, and this protein has been called TIP39. Northern analysis showed TIP39 messenger RNA in multiple organs, a pattern similar to that of tuftelin messenger RNA. In situ hybridization of mandibles of 1-day-old mice detected TIP39 RNA in secretory ameloblasts and odontoblasts. Immunolocalization of TIP39 and tuftelin in cultured ameloblast-like cells showed that these two proteins colocalize. Within the developing tooth organ, TIP39 and tuftelin immunolocalized to the apical pole of secretory ameloblasts (Tomes' processes) and to the newly secreted extracellular enamel matrix. TIP39 amino acid sequence appears to be highly conserved with similarities to proteins in species as diverse as yeast and primates. Available sequence data and the findings reported here suggest a role for TIP39 in the secretory pathway of extracellular proteins.
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[reaction: see text] Further oxidation of the common DNA lesion 8-oxo-7,8-dihydroguanosine by one-electron oxidants such as IrCl6(2-), Fe(CN)6(3-), or SO4-* leads to two major products, depending upon reaction conditions. In nucleosides at pH 7, 22 degrees C, the principal product is shown herein to be a spiroiminodihydantoin nucleoside, as a diastereomeric mixture, that can be characterized by NMR, ESI-MS/MS, and independent synthesis.
Enamel formation is a powerful model for the study of biomineralization. A key feature common to all biomineralizing systems is their dependency upon the biosynthesis of an extracellular organic matrix that is competent to direct the formation of the subsequent mineral phase. The major organic component of forming mouse enamel is the 180-amino-acid amelogenin protein (M180), whose ability to undergo self-assembly is believed to contribute to biomineralization of vertebrate enamel. Two recently defined domains (A and B) within amelogenin appear essential for this self-assembly. The significance of these two domains has been demonstrated previously by the yeast two-hybrid system, atomic force microscopy, and dynamic light scattering. Transgenic animals were used to test the hypothesis that the self-assembly domains identified with in vitro model systems also operate in vivo. Transgenic animals bearing either a domain-A-deleted or domain-B-deleted amelogenin transgene expressed the altered amelogenin exclusively in ameloblasts. This altered amelogenin participates in the formation an organic enamel extracellular matrix and, in turn, this matrix is defective in its ability to direct enamel mineralization. At the nanoscale level, the forming matrix adjacent to the secretory face of the ameloblast shows alteration in the size of the amelogenin nanospheres for either transgenic animal line. At the mesoscale level of enamel structural hierarchy, 6-week-old enamel exhibits defects in enamel rod organization due to perturbed organization of the precursor organic matrix. These studies reflect the critical dependency of amelogenin self-assembly in forming a competent enamel organic matrix and that alterations to the matrix are reflected as defects in the structural organization of enamel.
In a field experiment on dew formation in tropical paddy rice, the threshold value for the nocturnal net radiative loss required for dew formation was investigated during 23 nights from February to April 1994. The onset and cessation of dew were visually observed on both the top leaves of a rice crop and on a glass sphere, the "dewball", installed in the field 1.0 m above the ground. The threshold value for the nocturnal net radiative loss (Rn,thresh) necessary for dew formation on the ball was deduced from the maximum zenith angle on the ball surface reached by the dew formed. Rn,thresh was found to be linearly related to the nightly minimum vapour-pressure deficit. This linear relationship as well as the Penman-Monteith equation (an energy-balance approach) were used to predict both the time of dew onset and the duration of dew on the ball. These predicted values agreed well with the observed results. Dew duration and time of dew onset on the ball were well correlated. During most nights, dew began to form on the top leaf surfaces at almost the same time as it reached the zenith angle of 60 degrees on the ball. A linear relationship was found between the observed daily duration of dew on the top leaf surfaces of the rice crop and the estimated time when dew reached the zenith angle of 60 degrees on the ball. This relationship gave as accurate an estimation of dew duration on the top leaf surface of the rice crop as did the Penman-Monteith combination equation. This study showed that the dewball is a potentially useful device for observing dew formation.
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Improper application of antibiotic chemicals to livestock and aquaculture species may lead to the occurrence of residues in food supplies. An appropriate depletion period is needed after the administration of drugs to animals for ensuring that residues in edible tissues are below established tolerance levels. This study was conducted to determine incurred amoxicillin residues in catfish muscle following oral administration. Dosed fish were harvested after four depletion periods, and muscle fillets were analyzed for amoxicillin residues using an HPLC method with precolumn derivatization and fluorescence detection. The residue levels in fish after a 6-h depletion ranged from 40 to 64 ng/g with one exception at 297 ng/g. Average residue levels decreased to 5.4 and 2. 8 ng/g after 24- and 48-h depletions, respectively. Residue levels after a 72-h depletion decreased to below the method's limit of quantitation (1.2 ng/g). An LC-MS/MS confirmatory method was developed. Confirmation of the presence of amoxicillin was demonstrated in incurred fish samples containing residues at approximately 50-300 ng/g.
Mucosal cell-mediated immunity (CMI) by CD4+ T cells is postulated to be important for host defence against several vaginal pathogens. In addition to the recognized phenotypic distinctions of resident vaginal T lymphocytes, we recently provided evidence by fluorescence-activated cell sorter (FACS) that murine vaginal CD4+ T lymphocytes, are differentially recognized by two epitope-distinct anti-CD4 antibodies, suggesting that the CD4 protein on vaginal CD4+ cells is atypically expressed. In the present study, we confirm this by FACS and immunohistochemistry under non-denaturing conditions using two additional anti-CD4 antibodies. However, positive immunohistochemical staining of vaginal CD4+ cells under denaturing conditions revealed that the CD4 epitope in question is indeed present within the CD4 protein. Using reverse transcription polymerase chain reaction, amplification of CD3, T-cell receptor-beta (TCR-beta), and TCR-delta mRNA from lymph node and vaginal tissue, and CD4 mRNA from lymph node tissue was demonstrable. In contrast, amplification of CD4 mRNA from vaginal tissue, vaginal enriched lymphoid cells, or a purified (FACS-sorted) population of vaginal-specific CD4+ cells using two distinct primer sets was not demonstrable. Altogether, our results provide evidence that the CD4 protein on vaginal CD4+ T cells is conformationally distinct compared with its systemic counterpart, either as a result of a unique CD4 mRNA sequence or from a stable interaction of soluble CD4 with the surface of vaginal T cells.
OBJECTIVE: The aim of the present study was to investigate the expression levels of heat shock proteins (HSP) mRNA in the peripheral blood mononuclear cells (PBMC) of patients with asthma and chronic bronchitis to elucidate the role of HSP in the pathogenesis of asthma and chronic bronchitis. METHOD: Using reverse transcription-DNA polymerase chain reaction, the expression levels of HSP70, HSP90alpha and HSP90beta genes in PBMC in normal state and after heat shock were investigated. RESULTS: No HSP70 gene but HSP90alpha and HSP90beta expressions were found in non-heat-shocked PBMC of normal controls; HSP90alpha and HSP90beta genes may be expressed in PBMC of all patients, independently of acute episodes. Expression of HSP70 was found in PBMC of asthmatic patients in acute episodes and three symptom-free patients with Aas 3, step 2. Among patients with chronic bronchitis, no HSP70 gene expression was found in PBMC of patients in convalescent period but in PBMC of patients in acute episode. HSP90alpha and HSP90beta genes were expressed in PBMC of both patient groups. After heat shock, expressions of the three genes increased significantly in PBMC of both normal controls and patients. CONCLUSION: Expression of HSP70 gene in PBMC of asthmatic and chronic bronchitis patients was different, indicating that HSP, especially HSP70, might be involved in the pathogenesis of asthma.
The activation of Nef-associated kinase (NAK) by Nef from human and simian immunodeficiency viruses is critical for efficient viral replication and pathogenesis. This induction occurs via the guanine nucleotide exchange factor Vav and the small GTPases Rac1 and Cdc42. In this study, we identified NAK as p21-activated kinase 1 (PAK1). PAK1 bound to Nef in vitro and in vivo. Moreover, the induction of cytoskeletal rearrangements such as the formation of trichopodia, the activation of Jun N-terminal kinase, and the increase of viral production were blocked by an inhibitory peptide that targets the kinase activity of PAK1 (PAK1 83-149). These results identify NAK as PAK1 and emphasize the central role its kinase activity plays in cytoskeletal rearrangements and cellular signaling by Nef.
The realization that tumor cells utilize multiple mechanisms to escape from immune recognition and destruction has stimulated interest in developing and applying immunotherapeutic strategies which target both humoral and cellular immunity to malignant cells. As a result, the tumor-associated antigens (TAA) used as targets have to be expressed on the cell surface membrane of malignant cells. Furthermore, since most of the TAA used for active specific immunotherapy are self-antigens, a challenge facing tumor immunologists is to develop strategies which are effective in breaking tolerance to self-antigens. This chapter describes one strategy which relies on the use of peptide mimics of the human high molecular weight-melanoma associated antigen (HMW-MAA) as immunogens to implement active specific immunotherapy in patients with malignant melanoma. These mimics, which are isolated from phage display peptide libraries by panning with anti-HMW-MAA monoclonal antibodies, are expected to induce both humoral and cellular anti-HMW-MAA immunity.
The temperature effectiveness for wheat development was non-linearized and the apical and phenological development stages were systematically predicted by the scale of physiological development time which was based on the ecophysiological development process. The predicted apical development stages included single ridge stage, double ridge stage, floral initiation stage, stamen and pistil initiation stage, anther seperation stage, tetrad stage, and heading stage, while the predicted phenological development stages included germination stage, emergence stage, tillering stage, winterovering stage, green-turning stage, jointing stage, booting stage, heading stage, flowering stage, grain filling stage, and maturity stage. Four cultivar specific parameters were used to describe the genotypic differences of wheat development. They were temperature sensitivity, physiological vernalization time, photoperiod sensitivity, and intrinsic earliness, reflecting the genetic properties of different cultivars in thermal effectiveness, vernalization, photoperiod response and shortest time required for reaching flowering, respectively. The four parameters determined the physiological development time required for each development stage of different cultivars.
OBJECTIVE: To investigate the manifestations that heat shock proteins(HSPs) possess in the pathogenesis of asthma and chronic bronchitis. METHODS: Using reverse transcription-DNA polymerase chain reaction (RT-PCR), we investigated the expression levels of HSP70, HSP90 alpha and HSP90 beta genes in peripheral blood mononuclear cells(PBMC) at natural state and after heat shock in 14 healthy volunteers, 21 patients with asthma and 18 patients with chronic bronchitis. RESULTS: No HSP70 gene but HSP90 alpha and HSP90 beta expressions were found in non-heat-shocked PBMC of normal control; HSP90 alpha and HSP90 beta genes may be expressed in PBMC of patients no matter whether they were in acute episode or not. Expression of HSP70 was found in PBMC of patients in acute episodes and of three symptoms-free patients with Aas 3, step 2. No expression of HSP70 gene was found in PBMC of patients in convalescent period but in PBMC of patients in acute episode. HSP90 alpha and HSP90 beta genes were expressed in PBMC of the two patients groups; After heat shock, expressions of the three genes increased in amount significantly in PBMC of all normal controls and patients. CONCLUSION: Expression of HSP70 gene in PBMC of asthmatic patients and chronic bronchitis was different, indicating that HSPs, especially HSP70 might be involved in the pathogenesis of asthma.
OBJECTIVE: To study the relationship between the calcium signal and activation of mast cells, laying the foundation for discovering a new potential theraputical target of signal transduction for type I anaphylactic diseases like asthma. METHODS: The fluorescent Ca2+ indicator Fluo-3 was used to observe and quantitate the calcium signal directly in activated RBL-2H3 mast cells by a flow cytometer and a confocal fluorescence microscope with laser. RESULTS: Antigens elicited significant increase in intracellular Ca2+ concentration ([Ca2+]i) and histamine release in sensitized cells, maximal [Ca2+]i increase being reached (525 +/- 42) nmol/L (n = 12) within 90-110 s after stimulation. Increase of fluo-3-fluorescence intensity was also observed with the confocal fluorescence microscope in cytosol. No significant increase of [Ca2+]i was observed after addition of EDTA in sensitized cells from an initial value of (79 +/- 3) nmol/L, to (80 +/- 4) nmol/L (P > 0.05, n = 12), but tyrosine phosphorylation was readily observed, and the indirect fluorescent intensity was significantly greater than that in the control group. No significant change of [Ca2+]i was observed with the addition of DNP-BSA after PMA (P > 0.05, n = 8). CONCLUSION: Calcium is involved in the activation process of mast cells stimulated by antigens.
OBJECTIVE: To investigate extended-spectrum beta-lactamases (ESBLs) production in clinical isolates of the family Enterobacteriaceae in Shanghai, and compare the resistant rates of ESBLs-producing strains and non-ESBLs-producing strains to 11 antibiotics. METHODS: Double-disk synergy test was used to detect ESBLs in 1,026 strains of the family Enterobacteriaceae; Kirby-bauer agar diffusion method was used to judge drug sensitivity. RESULTS: 34.31% of strains of the family Enterobacteriaceae were considered ESBLs producers by double-disk synergy test. The prevalences of ESBLs in isolates of Klebsiella pneumoniae, Escherichia coli and Enterobacter cloacae were 37.40%, 30.21% and 41.82% respectively. Except Imipinem and Cefmetazole, the resistant rates of ESBLs-producing strains to other 9 antibiotics were much higher than that of non-ESBLs-producing strains(P < 0.01). The resistant rates of Imipinem to ESBLs-producing strains were the lowest. CONCLUSIONS: The prevalence of ESBLs in clinical isolates of the family Enterobacteriaceae in Shanghai was high; it is necessary for clinical laboratory to detect ESBLs in clinical isolates of the family Enterobacteriaceae routinely. The resistant rates of ESBLs-producing strains to most antibiotics were high. Imipinem and Cefmetazole were the effective antibiotics to infections caused by ESBLs-producing strains.