Abstract:Protein reversible phosphorylation is critically involved in regulation of almost every cellular process. Several factors which influence or determine the specificity of protein kinases and the structural aspects of regulation of protein by phosphorylation are mainly discussed.

Abstract:Nerve growth factor (NGF) is the prototype of a family of neurotrophins (NTs), which control the development and maintenance of some vertebrate neurons in the peripheral and central nervous system. The three-dimensional structure of NGF is based on the cystine knot and β strands. It binds as a dimer to cell-surface receptors and shows its biological response. Residues involved in these interactions have been identified by chemical modification and site-directed mutagenesis. They have substantially advanced knowledge of NGF structure and function.

Abstract:Some common nonlinear dynamic parameters are introduced, then on the basis of the characteristics of the biological experimental data, the newly developed analysis methods are illustrated.

Abstract:The transcription initiation of eukaryotic class Ⅱ genes is very complicated and strictly regulated. Many events such as the alteration of chromatin structure, the interaction between cis-elements and trans-factors are involved in this process. Based on the results of in vitro reconstitution transcription and the discovery of RNAPⅡ holoenzyme in yeast respectively, two models, step-wise assembly model and RNAPⅡ holoenzyme model, were proposed on the assembly of basal transcription initiation complex at promoters. Two related processes, antirepression and true activation, were supposed to be the molecular mechanism of the transcriptional activation.

Abstract:Histone acetylation has profound effects on chromatin structure, and it is directly linked to the gene activation of specific domains on genomic DNA. Histone acetylation is one of the most important ways in transcriptional regulation, functioning in the processes of cellular proliferation, differentiation and senecence.

Abstract:A new gene which called multidrug resistant associated protein gene (MRP) was found in the study of the mechanism of multidrug resistance of cancer. The cognate gene is located on chromosome 16 at band P13∶3. Its mRNA encodes a member of the ATP-binding cassette transmemberance transporter superfa-mily with a mass of molecular 190 ku (p190). The MRP is mainly located on the plasma membrane and may play a role in the ATP dependent transport system. Further study indicates that apart from some kind of cancer cell lines, MRP overexpression was found in some blood malignancy, breast cancer, lung cancer and so on. The overexpression may be also related to the relapse of cancer.

Abstract:A new technology developed recently, termed scanning dielectric microscopy(SDM), to image the dielectric properties of colloidal particles and biological cells in an aqueous environment was introduced through practical examples, and the characteristics of its principle and measurement system were described. The application potentiality of SDM in biological system and medicine was reviewed briefly.

Abstract:The molecular entities of the NMDA receptor channels have been identified by molecular cloning. These studies clearly showed the molecular diversity of the NMDA receptors, underlying the functional heterogeneity of NMDA receptor channels in vivo. The obtained clones provide valuable tools for investigation on the distribution and physiological roles of these receptor channels.

Abstract:Selenium is an essential trace element for human, which correlated to cancer, atherosclerosis and heart disease. Recently the role of selenium in the activation of latent period and progression of HIV infected individuals was investigated. Significantly a progressive selenium depletion in AIDS-related complex (ARC) and AIDS patients has been described. The mRNAs of T cells as T4 and T8 and viral RNA have potential structures that may encoded selenoprotein, one of the viral selenoproteins has a potential function to decrease HIV replication. in vitro, selenium has the regulatory role on HIV replication by inhibition of transcription factor NF-κB and HIV-1 long terminal repeat (LTR) promoter activity. These demonstrated a basis for the potential therapy use of Se to control disease process.

Abstract:E156S and V165I mutation were introduced into subtilisin E gene by site-directed mutagenesis. The mutated gene fragments were recombined with pBE-2 which is a shuttle vector between E.coli and Bacillus subtilis. The recombinant plasmids were used to transform B.subtilis DB104，a mutant strain deficient in alkaline and neutral protease，then they were expressed. They were (M222A，E156S) and (M222A，E156S，V165I). The property analysis of these enzymes revealed that the Subtilisin E E156S substitution enhenced the hydrolysis K_cat/K_m by 90% while keeping thermal stability and oxidation-resistance unchanged，however the V165I mutation reduced the K_cat/K_m value.

Abstract:The purified Beijing duck serum lipoproteins were observed by electronmicroscope for its shape and size. The distributions of total cholesterol and LCAT activities and their gradient gel elctrophoresis, the amino acid composition and partial amino acid sequences of each fragment of apo A-I were studied and determined, respectively. Furthermore, their hydrophilicity and hydrophobicity of α-helices were also studied and compared with human and other species. When the above results were integrated together they provided further evidence for the hypothesis that the cholesterol of Beijing duck is carried and transported by HDL instead of LDL and apo A-I played an important role in the cholesterol metabolism.

Abstract:Based on the conservative sequences, topological, biochemical, physiological and immunological data of anion exchanger (AE, band 3 protein) families, a peptide included 12 amino acids (position 476～487: SKLIKIFQDYPL) was synthesized and the antibodies against this peptide and the native segment of band 3 from rat erythrocyte membrane were prepared. The findings of immunoblotting and anion transport studies indicated that the peptide is an essential segment of the anion transport which is a conservative sequence in mammals (rat, mouse as well as human). Immunoscanning electron microscopic study proved directly that the peptide is located at the peripheral domain of band 3 in rat erythrocyte membrane. The antibodies against band 3 are useful tools in studying the structures and functions of the anion transport protein and investigating the relationship between band 3 and diseases.

Abstract:To study the protective effects of apolipoprotein AⅡ (apoAⅡ) on endothelial cells injured by low density lipoprotein (LDL) in vitro, human umbilical vein endothelial cells were cultured and divided into four groups: control, HDL+LDL, apoAⅡ+LDL and LDL group, which were observed the morphological changes with phase-contrast and transmission electron microscope and measured the release of lacate dehydrogenase (LDH) and level of 6-keto-prostaglandin F1α (PGF1α). The endothelial cells injured by LDL showed cell contraction, increased release of LDH and decreased level of 6-keto-PGF1α. However, normal morphology and LDH release as well as PGI₂ synthesis in endothelial cells were found when HDL or apoAⅡ was added to culture media before LDL injury. The results indicated that both HDL and apoAⅡ could resist the injurious effect of LDL on cultured endothelial cells.

Abstract:Single-copy and specific repeated DNA sequences of human Y chromosome were amplified and detected by in situ PCR in cultured human small intestine cancer metastastic ascites cell line cells. The results show that in situ PCR is much more sensitive than in situ hybridization.

Abstract:Regeneration of liver after hepatec-tomy is a complex process. It has been thought that there might be some growth factors and genes which play important roles in this process. In order to understand the regulatory mechanism of liver regeneration at molecular level, the changes in gene expression of regenerating liver have been demonstrated by mRNA differential display. As a result, four candidate cDNA fragments were obtained, including one down-regulated and three up-regulated. DNA sequencing demonstrated that all of them were novel. These sequences have been assigned the database accession numbers in EMBL as below: X95721, X95722, X95723, X97973.

Abstract:Sarcoplasmic reticulum Ca²⁺-ATPase proteoliposomes were reconstituted with ganglioside GM3 and soybean phospholipid by addition of detergent, sonication and chromatography. It was observed that GM3 may enhance the activity of Ca²⁺-ATPase in proteoliposomes and increase the diameter of uniform protein particles in sealed-well proteoliposomes vesicles which was evidenced by the negative-staining microscopy and freeze-fracture replica.

Abstract:The reduction of malondialdehyde (MDA) on hanging mercury drop electrode was studied by 2.5th order differential voltammetry.The linear response range of current (e″) against the concentration of MDA was given from 1.0×10^-6 to 1.0×10^-3 mol/L in the condition of a base solution of 0.1 mol/L NH₄Cl at scanning rate of 80 mV/s. The detection limit was 1.0×10^-7 mol/L. The method provids succesfully a rapid and simple way to determine the concentration of MDA in the sample of cardiac myocytes.

Abstract:According to the principle that NO^－₂ is able to enhance the fluorescence intensity of 4-hydroxycoumarin, a spectrofluorometric method for determination of nitric oxide in biological sample was developed. The nitrite concentration in the range of 2×10^-5 mol/L to 2×10^-8 mol/L in the sample can be measured. The method has been applied to determine the level of NO in cortex and hippcampus, cultural supernatant of macrophage actived by LPS and serum in rat.

Abstract:Using the hybridoma technique, a series of secretingmonoclonal antibodies (McAbs) against recombinant human interleukin-6 (rhIL-6) have been established after immunization of Balb/c mice with rhIL-6. Three of these McAbs 2H₂, 1D₂ and 4B₄ were well characterized. Their Ig class and subclass were determined as IgG1 and IgG2a respectively. These McAbs reacted with a high degree of specificity to rhIL-6 and did not have cross-reactivity with many other cytokines and irrelevant proteins. Immunoblotting results showed that these McAb only recognized a single band of rhIL-6 with molecular mass of 21 ku. These McAb reacted strongly with IL-6 molecules with an affinity constant (K_aff) 1.62×10⁹ (mol/L)^-1.

Abstract:It is revealed by difference spectra that cibacron blue F3GA could bind specifically to Trichosanthin(TCS). The spectral absorption maximum is on 690nm with molar absorption coefficient of 2.6×10^-3 (mol/L)^-1·cm^-1. The dissociation constant is 1.8 μmol/L, and 0.5 mol/L NaCl could dissociate the complex. Based on these results, TCS is purified from the root tuber of Trichosanthes Kirilowii by Blue Sepharose CL-6B. This method is rapid, simple, efficient and could be applied in mass preparation of TCS.

Abstract:A new way for affinity chromatography has been developed to purify the McAb in ascites. Using nitrocellulose membrane(NCM) as solid-phase to adsorb the antigen, filtrating the sample under negative pressure through the NCM which could bind the relevant antibody to the antigen adsorbed on, then dissociating the antibody from the NCM in the purified form, this is the process of the so called membrane filtration affinity chromatography(MFAC). The albumin(Alb) McAb in ascites has been purified with the MFAC. The purified McAb showed a single band in the polyacrylamide gel electrophoresis(PAGE).While used in dot immunofiltration assay(DIFA) to detect Alb standard, the sensibility of the purified McAb was 20 times more than that of the ascites. The simple and effective MFAC can be used as a new affinity chromatography to purify antibodies in ascites.

Abstract:An approach to detect K-ras oncogene mutated at codon 12 was devised by using a nested polymerase chain reaction strategy based on mismatched primers. A titration experiment showed that the sensitivity obtained by use of the nested PCR was 1/512. This represented the ability to detect one cell heterozygous for K-ras codon 12 mutation over 500 normal cells and was 100-fold greater than that obtained after one-step PCR. Application of this assay to 9 patients with adenocarcinoma of the lung showed 5 cases containing one or more K-ras mutation at codon 12. It is suggested that the method was practicable and worthy of application and dissemination.

Abstract:In order to prepare an ELISA plate which can be used for site-specific conjugation of oligonucleotide probe, partially hydrolysed nylon was used to coat ELISA plate, oligonucleotide probes were conjugated to ELISA plate by covalent conjugation of 5′ phosphate group of the probe with the amino groups of the hydrolysed nylon under the catalysis of water soluble carbodiimide. The method was used to detect PCR product of Mycoplasma pneumoniae, and reproducible result was acquired. The reported method can be used in molecular detection of clinical pathogens.

Abstract:Schering-Plough Pharmaceutical company successfully conducted small molecular drug screening with BIA technology. Using competitive methods they develop a high throughput assay for screening cytokine antagonisis.