Biomedical subjects
Publications and source records attributed to Z Li.
The article reports the morphological characters, the histological structure, TLC and UV spectrum identification for the adulterant of Cortex Mori, the root bark of Broussonetia papyrifera. The results show that they can be distinguished each other.
Essential oil from Angelica formosana Boiss was obtained by steam distillation. The chemical components of the oil were examined by means of capillary gas chromatography and gas chromatography-mass spectrometry. 23 of the 62 separated constituents were identified. The content of each component identified was determined by area normalization method. Of these, the content of 11 compounds was higher than 1%.
OBJECTIVE: In order to investigate the expression of ferritin receptor (FnR) on human placental microvillous membrane in mid-pregnancy and its implication. METHODS: Radioligand binding assay was used, with horse spleen 125I-apo-ferritin as radioligand. RESULTS: The FnR expression in normal placental microvillous membrane in mid-pregnancy was (9.63 +/- 4.72) x 10(12) sites/mg pro, similar to that in normal placental of term delivery,and the dissociation constants (Kd) between them had also no significant difference: Competitive binding assay indicated that the receptor bound basic ferritin with higher affinity than acidic one. CONCLUSIONS: The expression of FnR in mid-pregnancy almost come to mature level; The FnR on placenta might be involved in maternal-fetal iron transport, transfering iron from mother to fetal.
A simple, rapid and accurate quantitative method was established for the determination of beta-carotene in Fructus lycii by isocratic nonaqueous RP-HPLC. Separation was obtained by using Shim-Pack CLC-ODS column (6 mm i.d. x 150 mm, 5 microm) and mobile phase of methanol/ethyl acetate (50:55, V/V) with flow rate of 1 mL/min. The eluates were monitored with UV/VIS detector at 448 nm. The retention time for beta-carotene was 7.33 min. The calibration curve was linear in the range of 1.0-5.0 mg/L with r=0.9998. The average recovery for beta-carotene was 97.1% with a coefficient of variation of 1.9%. The content of beta-carotene in Fructus lycii from different areas was also determined.
A method for qualitative and quantitative analysis by GC/MS and GC of ethers and related olefines in light gasoline from catalytic cracking before and after etherification has been presented. By means of the analysis of the reactive olefines and the ethers produced it is concluded that six kinds of olefines had taken part in the etherification process, they were, 2-methyl propene-1,2-methyl butene-2,2-methyl butene-1,2-methyl pentene-1,2-ethyl butene-1, and 2-methyl pentene-2, and the four ethers produced were 2-methoxy-2-methyl propane, 2-methoxy-2-methyl butane, 2-methoxy-2-methyl pentane and 3-methoxy-3-methyl pentane. These ethers are all contributing to enhance the octane number.
In this paper, a method for electrokinetic packing capillary columns is reported. A higher column effeciency was obtained by performing electrochromatography on electrokinetic packing columns. The highest column efficiency in number of theoretical plate per meter was more than 200000, corresponding to reduced plate height less than 2. The reproducibilities of the same column in different intervals and different columns prepared from the same or different batches were compared. The relative standard deviations of the number of theoretical plate and retention time were less than 10% and 8%, respectively. The results indicated that high column efficiency and good reproducibility can be obtained on these new capillary packed columns.
The essential oil of the Vitexd rotundifolia L. was abstracted by steam distillation. The oil obtained was dried with anhydrous sodium sulfate. The chemical constituents were analyzed by GC/MS. More than 30 peaks were separated by GC, and 28 compounds were identified by using NBS mass spectral data, and the Wiley/NBS registry of mass spectral data. The structrure of delta3-carene was further verified by GC/FTIR. The identified constituents represent over 95% of the peak area on TIC of the essential oil. The major chemical constituents of them are delta3-carene, 1,8-cineole, sabinene, beta-phellandrene and isoterpinolene.
According to US EPA 8270 method the semi-volatile organic compounds in chemical waste were analysed by internal standard method which could eliminate the systematic and injection errors and increase the accuracy of the results. Through this experiment, ten prior pollutants of US EPA and eleven organic chlorinated compounds with concentrations between 0.4 microg/g and 80 microg/g in the waste were determined. It is concluded that the waste was hazardous and could not be disposed without proper treatment.
The saliva thiocyanate contents were determined among smokers and passive smokers. The saliva thiocyanate contents of passive smokers in smoking environment and non-smoking environment were compared. The results showed that the saliva thiocyanate in smoking environment was higher than that in non-smoking environment (P<0.01). The results indicate that the saliva thiocyanate detecting is a direct and sensitive index for evaluating the hazard of passive smoking.
Measurement results of laser induced autofluorescence spectra of tumor tissue from little rat are given in this paper it is compared with normal tissue of the same body After analyzing the origin of tumor tissue autofluorescence and the difference with normal tissue spectra, it is concluded that autofluorescence spectra of tissue may reflect the features of tumor tissue and be utilized to diagnose the tumor.
The principle of neural networks was briefly described. Backpropagation (BP) is a widely used algorithm to train NN with slow convergence and local optima. In order to overcome the above weakness of BP, a novel learning algorithm, extanded Kalman filtering (EKF, EF), was proposed with high performance. EFNN was used for simultaneous multi-component analysis with good results and no separation.
Hepatocyte growth factor/scatter factor (HGF/SF) is a mesenchymally derived glycoprotein with a strong scattering effect on epithelial cells. A receptor tyrosine kinase encoded by the met proto-oncogene has been identified as the cellular receptor for HGF/SF. Following stimulation with HGF/SF, cell scattering occurs concurrent with decreased cell-cell adhesion and disassembly of junctional components. In culture, junction formation is cell-cell contact dependent and can be regulated by modulating the Ca2+ concentrations of the growth media. Decreasing the Ca2+ concentrations below 50 microM causes rapid disassembly of junctions, whereas increasing the Ca2+ concentrations to 1.8 mM induces cell-cell contact and junction assembly. Although associated with decreased cell-cell adhesion and disassembly of the junctional complex, HGF/SF-induced scattering occurs under high extracellular Ca2+ concentrations. To gain insight into the mechanisms of HGF/SF-induced scattering of epithelial cells, we have studied the effect(s) of HGF/SF on junction assembly by examining the solubility, stability, phosphorylation, and subcellular localization of the major components of the adhering junctions, plakoglobin (Pg) and E-cadherin, in Madin-Darby canine kidney (MDCK) epithelial cells and in a MDCK cell line expressing an exogenous chimeric met receptor (CSF-MET) that scatters in response to colony-stimulating factor 1 (CSF-1). The results have shown that in HGF/SF-stimulated MDCK cells, adhering junctions were not assembled upon induction of cell-cell contact. Immunofluorescence analyses showed that larger amounts of Pg and E-cadherin were Triton X-100 extractable, and more significantly, these proteins were homogeneously distributed along the membrane and were not concentrated at the areas of cell-cell contact. Similar results were obtained for CSF-MET expressing MDCK cells in response to CSF-1. In contrast, none of the above effects were detected in MDCK cells expressing a mutant CSF-MET chimera containing a phenylalanine substitution at tyrosine 1356 in met, which fails to scatter in response to CSF-1. When compared with the unstimulated cells, the inhibition of cell adhesion promoted by HGF/SF correlated with an increased stability of the newly synthesized soluble E-cadherin and Pg and an altered phosphorylation pattern of E-cadherin, as determined by partial proteolytic peptide mapping.
A cross-sectional survey was undertaken to describe risk-taking behaviors and to assess the knowledge and risk perception of HIV and AIDS among young males aged 18 to 29 years in 82 villages in Longchuan, Yunnan, China, in 1994. Information on demographic, behavioral, and drug-using factors, and knowledge of HIV transmission and prevention, and risk perception was collected using an interviewer-administered anonymous questionnaire. A total of 1,548 individuals were interviewed and 433 drug users, including 52 nonsharing injectors and 140 sharing injectors, were identified. Over half the individuals scored 0 on HIV knowledge, but knowledge was greater among nonsharing drug injectors. Most drug injectors had initiated drug injection after 1990. The reported incidence continues to increase in all three major ethnic groups. Sharing of equipment was common (73%) among injectors. Drug users were four times more likely to have had premarital or extramarital sex, but condoms were used by only 2.5%. Thus, factors promoting spreading of HIV are common in this area. We recommend that a community-based intervention program, targeting both young men and women, be implemented and evaluated in Longchuan as soon as possible.
Hyperthermia is a recognized teratogen in animals and there is strong evidence that it also causes significant damage to human embryos. Studies with induced hyperthermia in pregnant animals defined the defects which are produced, the susceptible stages of development, and threshold doses of heat required to cause defects. The in vivo experiments lacked precision because of variability of embryonic development at a given conceptual age, varying maternal responses to agents causing temperature elevations, the difficulty in measuring embryonic temperature and the possibility that defects were caused by toxic changes in maternal metabolism. These variables were eliminated by the use of postimplantation whole rat and mouse embryo cultures, which were exposed to various doses of heat at closely defined stages of development. The studies showed that heat acts directly on embryos and that elevations of 2 degrees C and greater sustained over early rat organogenesis cause defects mainly by causing apoptotic cell death especially in the developing central nervous system. A moderate, non damaging exposure is followed within 15 min by protection for up to 8 h against a more severe and otherwise teratogenic exposure. The protective heat shock response is accompanied by a reduction of normal protein synthesis and concurrent synthesis of heat shock proteins (HSP90, 71, 47, 27). Most HSP in these families are also present constitutively in embryos, probably having important roles in protecting newly synthesized proteins from aggregation and facilitating folding into their normal functional configurations. The appearance of induced HSP and hsp mRNA at known sites of thermal damage suggests a protective role. Heat induced cell death by apoptosis is a feature of teratogenic damage to the developing brain. Apoptosis could be a by-product of a damaging heat exposure because of a priority favoring induction of the heat shock response over the normal gene program for organogenesis, survival being achieved at the expense of normal development.
Our laboratory is engaged in an effort to identify genes expressed primarily during plant embryogenesis. Genes which exhibit unique expression profiles in the plant are also being sought. To this end, several methods to identify and clone novel genes based on specific expression patterns have been developed. These methods include virtual subtraction, differential display and other PCR based technologies. In addition to this, a yeast one-hybrid approach has been established to identify transcription factors which regulate these genes. To date, this work has identified several novel genes.
Pulmonary arterial myocytes were cultured from normotensive and pulmonary hypertensive rats. Microfluorimetry of Ca2+ signals in fluo-3-loaded single myocytes at day 7 of culture was performed by a laser-scanned confocal imaging system. The resting level of cytoplasmic Ca2+ concentration ([Ca2+]i) in vascular myocytes obtained from hypertensive rats was higher than that in cultured myocytes obtained from normotensive rats. Angiotensin II elevated [Ca2+]i in the vascular myocytes cultured from both normotensive and hypertensive rats. However, a rise of [Ca2+]i induced by angiotensin II in the vascular myocytes obtained from pulmonary hypertensive rats was higher than that obtained from normotensive rats. On the other hand, the response of [Ca2+]i to A23187 did not differ between the vascular myocytes cultured from normotensive and hypertensive rats. The present results suggest that the resting and angiotensin II-responsive levels of [Ca2+]i in pulmonary arterial myocytes cultured from pulmonary hypertensive rats are higher than those cultured from normotensive rats.
A Phase 1, double-blind, placebo controlled trial was conducted in Longchuan County, China, to evaluate the safety and immunogenicity of a prototype HIV-1 synthetic peptide vaccine in a target population at risk for HIV infection, and to establish the infrastructure for future large-scale HIV vaccine efficacy trials. Subjects were randomly assigned to receive 100 microg or 500 microg of vaccine or alum placebo, and were given three injections at an accelerated 0, 1, and 2 month schedule. The vaccine was well tolerated with no significant local or systemic reactions observed in any subjects. Fifty-five percent (100 microg dose) and 64% (500 microg dose) of subjects who received the vaccine produced binding antibody to the immunogen as determined by ELISA. However, HIV-1 (MN) neutralizing antibody was detected in only 23% (3/13) of subjects with detectable HIV-1 specific binding antibody. It was concluded that this prototype HIV-1 synthetic peptide vaccine was well tolerated, safe and immunogenic, and that a 0, 1, 2 month schedule was not as effective in stimulating HIV-1 specific neutralizing antibodies compared with previous trials utilizing a 0, 1, 6 month schedule. Finally, this trial demonstrated that well-designed HIV vaccine trials can be performed at this clinical trials site in Yunnan, China, and that this site should be considered for conducting larger safety, immunogenicity and efficacy trials of candidate HIV vaccines.
Research over the past few years on the function of intermediate filaments in cells in culture has not produced convincing results, because the key role of intermediate filaments is within tissues and at certain periods of development. Only recently the technique of gene knockout has been used to examine intermediate filaments in mice and has provided the first evidence that intermediate filaments are directly involved in cell resilience and the maintenance of tissue integrity. Knockout of the gene encoding keratin K8 is lethal in the embryo, and results in hepatic or intestinal lesions, while knockout of the K14 or K10 genes leads to rupture of stratified epithelia. Knockout of the gene encoding desmin causes the rupture of skeletal and cardiac muscle, and collapse of blood vessel walls. Knockout of the gene coding for GFAP leads to a loss of cerebral white matter, and knockout of the gene coding for vimentin causes degeneration of the cerebellar Purkinje cells. The results reveal the lack of compensation by another intermediate filament. Tissues without intermediate filaments fall apart; they are mechanically unstable, unable to resist physical stress, and this leads to cell degeneration. By maintaining the shape and plasticity of the cell, the intermediate filament network acts as an integrator within the cell space. The state of mechanical force imposed on a tissue or a cell can alter the shape of certain elements of the cytoskeleton and thus participate to the control of cell functions.