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Biomedical subjects

M Jiang

Publications and source records attributed to M Jiang.

At least 127 records · Page 7Linked to original sources
PubMed1998

[WAF1/CIP1/p21 gene in wild type p53 and mutant p53 human breast cancer cell lines in relation to its cytobiological features].

OBJECTIVE: To study the WAF1/CIP1 gene DNA status, mRNA and protein expressions in human breast cancer cell line and its significance. METHODS: Using cell culture, molecular biological techniques such as Southern blot, Northern blot and immunocytochemical methods, the WAF1/CIP1 gene DNA status, mRNA and protein expression levels in MCF-7 expressing wild type p53(wtp53) and MDA-MB-231 expressing mutant p53 (mtp53) human breast cancer cell lines were detected respectively. The p53 and mdm-2 protein expression levels and cytobiological features of the 2 cell lines were compared and correlated to their WAF1/CIP1 gene expression levels. RESULTS: (1) There was no difference in WAF1/CIP1 gene DNA status in the two breast cancer cell lines. Neither of them showed gene amplificatian or deletion. However, the WAF1/CIP1 mRNA and p21WAF1/CIP1 protein expression levels of MCF-7 cells were higer than those of MDA-MB-231 cells (P < 0.05). (2) The character and cellular distribution of p53 protein in the two cell lines were clearly different. The expression level of mdm-2 proteion was significantly higher in MCE-7 than in MDA-MB-231 cells (P < 0.05). (3) Compered to the other breast cancer cell line, MCF-7 cells were better differentiated, grew more slowly and adhered more closely with each other. CONCLUSION: The WAF1/CIP1 gene expression at mRNA and protein levels is associated with p53 phenotype and some cytobiological features of human breast cancer.

Breast Neoplasms↗
PubMed1998

[Rheumatoid arthritis synoviocyte hyperplasia and expression of fas and bcl-2 genes].

OBJECTIVE: To determine whether apoptosis occurs in the proliferative synovial tissue and cells from patients with rheumatoid arthritis (RA). METHODS: In situ hybridization was carried out by using labeled RNA probes of fas, fasL, and bcl-2 synthesized by in vitro transcription. Apoptosis was examined by DNA electrophoresis and flow cytometry. RESULTS: fas mRNAs were expressed in 6 of 7 patients with RA. bcl-2 mRNAs were positive in 5 of 7 patients with RA. fasL mRNAs were not detectable in all the patients. bcl-2 mRNAs were always coexpressed with fas in RA synovial lining cells. The positive rates of fas and bcl-2 expression in RA synovial tissues were significantly higher than those of patients with osteoarthritis (OA) and normal synovial tissues (P < 0.05). Immunochemistry staining showed that Fas and Bcl-2 proteins were expressed in the synovial lining cells. Nucleic DNA extracted from the synovial tissues of 6 patients with RA, 4 patients with OA and 2 normal controls. Agarose gel electrophoresis demonstrated that DNA ladders occurred in only one OA synovial tissue. The spontaneous apoptosis in cultured synoviocytes from patients with RA and OA was lower as analyzed by immunofluorescence staining and flow cytometry. CONCLUSION: The phenomena of apoptosis in RA synoviocytes was not significant and overexpression of bcl-2 perhaps inhibited apoptosis in these cells, leading to hyperplasia of RA synoviocytes.

Apoptosis↗
PubMed1998

[Construction and secretory expression of single-chain Fv fragment M97 with therapeutic potential against tumor invasion and metastasis].

OBJECTIVE: To manufacture single chain Fv antibody fragment for cancer targeting therapy. METHODS: Based on recombinant phage display techniques, the construction, screening and expression of functional single-chain Fv fragment (scFv) from murine hybridoma C2H5 which secretes antibody specifically binding to (92 kD) type IV collagenase were performed. By RT-PCR for VH and VL genes, assembly of scFv genes and cloning into phagemid pCANTAB5E, transformation of TG1 cells and M13KO7 helper phage rescue, a recombinant phage scFv library with titre of 5 x 10(9) pfu/ml was established. Panning against immobilized type IV collagenase (92 kD) was performed by one round. Finally, 30 antigen-positive recombinant phage clones were isolated and identified by ELISA. RESULTS: DNA sequencing result showed that the entire gene of scFv against type IV collagenase (92 kD) designated as scFv-M97 is 732 bp, consisting of the 351 bp VH gene encoding 117 amino acids, the 336 bp VL gene encoding 112 amino acids and a 45 bp linker encoding (Gly4Ser)3. The antigen-positive phage with titre of 10(10) pfu/ml was used to infect HB2151 cells in which soluble scFv was expressed. After induction of Lac promotor by 1 mM IPTG for 20 h, the scFv-M97 yield of HB2151 in SBA medium is about 2 micrograms/ml. Immuno-blot indicated that the 27 kD scFv-M97 retained the affinity and specificity of the original intact antibody to type IV collagenase (92 kD). CONCLUSIONS: Single chain antibody scFv-M97 expressed by secretion was successfuly produced. As type IV collagenase plays an important role in tumor invasion and metastasis by the mechanism of proteolytic degradation of type IV collagen in the basement membrane, scFv-M97 may have therapeutic potential against tumor invasion and metastasis.

Amino Acid Sequence↗
PubMed1998

[Chemical changes of compatibility for shaoyao decoction].

OBJECTIVE: To probe the regular patterns of interactions among chemical components in Chinese medicinal complex prescriptions. METHOD: The active components of Rhubarb, Coptis root and Baikal skullcap root in different patterns of compatibility were determined by TLC-scanner. RESULT: The berberine content in Coptis root can be decreased obviously by Rhubarb, Baikai skullcap root and Licorice root, especially by Rhubarb. Coptis root can also decrease the contents of acid components. CONCLUSION: The acid components can affect each other, thus reducing the contents of effective components.

Berberine↗
PubMed1998

[Ultrastructure of Schistosoma japonicum sperm].

AIM: To understand the ultrastructure of Schistosoma japonicum sperm. METHODS: Testis and oviduct were cut from male and female of S. japonicum respectively, location was assured by observing with microscope. Specimens preparation for transmission electron microscope were made by traditional way. RESULTS: The sperm of S. japonicum includes two parts: a head and a single tail. The elongated ovoid head measures by 6.2 x 1.4 microns, lacking an acrosome, rounding anteriorly and tapering posteriorly. A prominent anterior mass of mitochondria lies beneath the plasma membrane. A layer of microtubes under the plasma membrane are parallel with long axis of the head. A coil of longitudinal microtubes were present beneath the plasma membrane. The nucleus is largely electron-opaque with some electron-lucent patches or less electrondense material. The tail is a single flagellum with a unique axoneme, which originated from a centriole. The axoneme in main part of the flagellum (including middle and posterior parts of the tail) consists of nine doublets and a single diffuse central structure, forming 9 x 2 + <<1>> type. But the axoneme in the transition area (anterior part of the tail) lacks central material, forming 9 x 2 + 0 type. CONCLUSION: The sperm ultrastructure in the schistosomes is homogeneous, but differs distinctly from those trematodes of other Digenea.

Animals↗
PubMed1998

[Studies on dynamic changes of SOD and MDA in cultured cells from Schistosoma japonicum schistosomula].

AIM: To observe the dynamic changes of superoxide dismutase(SOD) and maldondialdehyde(MDA) in cultured cells from Schistosoma japonicum schistosomula and to explore the degeneration process of cultured cells. METHODS: Pyrogallol method and thiobarbituric acid method were used to determinate the levels of SOD and MDA, respectively, in the cells cultured for 0-54 days. RESULTS: SOD in the cells reached a peak level on d12 of the early stage of culture and then decreased. The MDA levels in the cultures cells ascended gradually, and had two peaks on d18 and d48, during the period of culture. CONCLUSION: The cultured cells from S. japonicum schistosomula degenerated progressively.

Animals↗
PubMed1997

Mismatch-sensitive hybridization detection by peptide nucleic acids immobilized on a quartz crystal microbalance.

A quartz crystal microbalance DNA hybridization biosensor, based on thiol-derivatized peptide nucleic acid (PNA) probes, offers unusual in situ differentiation of single-base mismatches. A large excess of a single-base mismatch oligonucleotide has no effect on the frequency response of the target. Such remarkable distinction between perfect matches and mismatches is illustrated by the detection of a common mutation in the p53 gene. The greater specificity of the new mass-sensitive indicatorless hybridization device over those of analogous PNA-based carbon electrodes is attributed to the formation of a PNA monolayer and the use of a hydrophilic ethylene glycol linker. The improved specificity is coupled to very fast (3-5 min) hybridization in a low-ionic-strength medium.

Biosensing Techniques↗
PubMed1997

Cloning and expression of a novel mammalian homolog of Drosophila transient receptor potential (Trp) involved in calcium entry secondary to activation of receptors coupled by the Gq class of G protein.

Hormonal stimulation of Gq-protein coupled receptors triggers Ca2+ mobilization from internal stores. This is followed by a Ca2+ entry through the plasma membrane. Drosophila Trp and Trpl proteins have been implicated in Ca2+ entry and three mammalian homologues of Drosophila Trp/Trpl, hTrp1, hTrp3 and bTrp4 (also bCCE) have been cloned and expressed. Using mouse brain RNA as template, we report here the polymerase chain reaction-based cloning and functional expression of a novel Trp, mTrp6. The cDNA encodes a protein of 930 amino acids, the sequence of which is 36.8, 36.3, 43.1, 38.6, and 74. 1% identical to Drosophila Trp and Trpl, bovine Trp4, and human Trp1 and Trp3, respectively. Transient expression of mTrp6 in COS.M6 cells by transfection of the full-length mTrp6 cDNA increases Ca2+ entry induced by stimulation of co-transfected M5 muscarinic acetylcholine receptor with carbachol (CCh), as seen by dual wavelength fura 2 fluorescence ratio measurements. The mTrp6-mediated increase in Ca2+ entry activity was blocked by SKF-96365 and La3+. Ca2+ entry activity induced by thapsigargin was similar in COS cells transfected with or without the mTrp6 cDNA. The thapsigargin-stimulated Ca2+ entry could not be further stimulated by CCh in control cells but was markedly increased in mTrp6-transfected cells. Records of whole cell transmembrane currents developed in response to voltage ramps from -80 to +40 mV in control HEK cells and HEK cells stably expressing mTrp6 revealed the presence of a muscarinic receptor responsive non-selective cation conductance in Trp6 cells that was absent in control cells. Our data support the hypothesis that mTrp6 encodes an ion channel subunit that mediates Ca2+ entry stimulated by a G-protein coupled receptor, but not Ca2+ entry stimulated by intracellular Ca2+ store depletion.

Amino Acid Sequence↗
PubMed1997

p21/waf1/cip1 and mdm-2 expression in breast carcinoma patients as related to prognosis.

p21/waf1/cip1 and mdm-2 are downstream effectors of p53. p21 plays a major role in negatively regulating cell-cycle progression, while mdm-2 inhibits p53 effects, and its role has been implicated in oncogenesis. In this study, we investigated the expression profiles of p21, mdm-2 and p53 in human breast-carcinoma tissues. The aim was to determine whether a correlation exists between the expression profiles of these markers and tumor differentiation, ER status and prognosis. We studied tumor specimens obtained from 106 patients and found a highly significant association among low histology grade, p53 over-expression, high mdm-2 expression and lack of p21 expression. Our studies also demonstrate that, in human breast cancer, low levels of p21 and higher mdm-2 levels directly correlate with the onset of lymph-node metastases and shortened patient survival. Furthermore, the expression profiles of p21, mdm-2 and p53 were independently correlated with patient survival.

Adult↗
PubMed1997

Suppression of slow delayed rectifier current by a truncated isoform of KvLQT1 cloned from normal human heart.

It has been suggested that the cardiac slow delayed rectifier channel is formed by the association of two subunits: IsK (also called minK) and KvLQT1. N-terminal splice variants of the human KvLQT1 gene have been identified, but the functional roles of different KvLQT1 isoforms are not clear. Using the nested 5'-rapid amplification of cDNA ends technique, we obtained a truncated isoform of KvLQT1 (termed tKvLQT1) that lacks the N-terminal cytoplasmic domain and the initial one-third of the first transmembrane domain. The function of tKvLQT1 was tested by oocyte expression, alone or together with the full-length KvLQT1 or a human IsK clone (hIsK). tKvLQT1 alone did not generate functional channels. However, it suppressed the KvLQT1 current when coexpressed with the full-length isoform. It also suppressed the slow delayed rectifier current induced by hIsK, probably by competing with the KvLQT1 subunit endogenous to Xenopus oocytes in coassembly with the hIsK subunit. On the other hand, tKvLQT1 did not suppress the expression of Kv1.4, Kv4.3, or hERG. Using the reverse transcription-polymerase chain reaction technique, we further show that the truncated and full-length isoforms are coexpressed in different regions of human heart. Therefore, tKvLQT1 may modulate the function of IKs in human cardiac myocytes.

Amino Acid Sequence↗
PubMed1997

Uncoupled phosphorylation and activation in bacterial chemotaxis. The 2.3 A structure of an aspartate to lysine mutant at position 13 of CheY.

An aspartate to lysine mutation at position 13 of the chemotaxis regulatory protein CheY causes a constitutive tumbly phenotype when expressed at high copy number in vivo even though the mutant protein is not phosphorylatable. These properties suggest that the D13K mutant adopts the active, signaling conformation of CheY independent of phosphorylation, so knowledge of its structure could explain the activation mechanism of CheY. The x-ray crystallographic structure of the CheY D13K mutant has been solved and refined at 2.3 A resolution to an R-factor of 14.3%. The mutant molecule shows no significant differences in backbone conformation when compared with the wild-type, Mg2+-free structure, but there are localized changes within the active site. The side chain of lysine 13 blocks access to the active site, whereas its epsilon-amino group has no bonding interactions with other groups in the region. Also in the active site, the bond between lysine 109 and aspartate 57 is weakened, and the solvent structure is perturbed. Although the D13K mutant has the inactive conformation in the crystalline form, rearrangements in the active site appear to weaken the overall structure of that region, potentially creating a metastable state of the molecule. If a conformational change is required for signaling by CheY D13K, then it most likely proceeds dynamically, in solution.

Amino Acid Sequence↗
PubMed1997

Mutant human protein disulfide isomerase assists protein folding in a chaperone-like fashion.

Human protein disulfide isomerase with an extra 10 amino acid residues of AEITRIDPAM at the N-terminal was expressed in E. coli as a soluble protein comprising 20% of total cell proteins, and was purified to near homogeneity through one step of DEAE-Sephacel chromatography. The mutant enzyme, which had the same CD spectrum and comparable disulfide isomerase and thiol-protein oxidoreductase activities with that of the wild type human and bovine protein disulfide isomerases, also showed chaperone-like activity in stimulating the refolding of proteins containing no disulfide bond. The overall yield of the active product is about 20 mg 1-1 culture.

Amino Acid Sequence↗
PubMed1997

Expression of calretinin in diverse neuronal populations during development of rat hippocampus.

The prenatal and postnatal expression of calretinin was studied in hippocampus of the rat using immunohistochemical procedures. Calretinin was detected as early as embryonic day 15 in the primordial hippocampus where calretinin-containing neurons and fibres were localized to the primitive plexiform layer. Upon emergence of the hippocampal plate (the prospective stratum pyramidale), large numbers of immunopositive multipolar cells were observed in the marginal zone. Fewer cells with fusiform cell bodies were observed bordering the hippocampal plate and subplate. During the perinatal period (embryonic day 20 to postnatal day 0), large numbers of immunoreactive pyramidal-like neurons were observed at the margin of the hippocampal plate with the subplate. At this same time, many calretinin-containing neurons with irregularly shaped dendrites were observed in stratum radiatum. Soon after birth (postnatal day 3), the calretinin immunoreactivity of both these later cell types rapidly declined and a new population of calretinin-immunopositive cells emerged, the Cajal-Retzius cells of stratum lacunosum-moleculare and the dentate gyrus. The Cajal-Retzius cells rapidly matured but disappeared by the second postnatal week. During the second postnatal week, calretinin interneurons of the adult hippocampal formation began to appear. Their immunoreactivity increased by postnatal day 15, when the number of calretinin-immunopositive interneurons in area CA1 and stratum radiatum of CA3 exceeded that of the adult. At this time, the soma and proximal dendrites of many calretinin interneurons were found to contact each other. The frequency of such cellular appositions decreased in adulthood. The results presented here show that calretinin immunohistochemistry can be very useful in recording the development of subpopulations of hippocampal neurons that are present during distinct embryonic and postnatal periods. Although some neuronal types may exist only briefly during hippocampal development, others appear to express calretinin transiently during restricted phases of neuronal differentiation. Surprisingly, this includes some hippocampal pyramidal cells. However, even as the adult pattern of immunostaining emerges in week 2, morphological refinement of interneurons continues to take place, which eventually leads to the population of calretinin-containing interneurons of the mature hippocampus.

Animals↗
PubMed1997

Mechanism of enhancement of slow delayed rectifier current by extracellular sulfhydryl modification.

To explore the role of sulfhydryl (SH) groups in the function of cardiac slow delayed rectifier channels, we tested the effects of extracellular thimerosal (TMS, a hydrophilic SH modifier) on slow delayed rectifier current (IKs) induced by human IsK (hIsK) in oocytes and on the native IKs in canine ventricular myocytes. TMS (25 or 50 microM) had similar effects on the two currents: current amplitude increased, and there was an acceleration of activation and a slowing of deactivation. These effects showed little or no reversal after washout of TMS. The effects did not depend on intracellular Ca release or protein kinase activities but could be suppressed by dithiothreitol pretreatment. According to the current model of transmembrane topology, there is no cystein in the extracellular domain of hIsK. A likely candidate for TMS modification is the SH group on another subunit in oocyte cell membrane that interacts with IsK to form a functional channel. To explore the domain of hIsK involved in the interaction, extracellular serines of hIsK were mutated to cysteines at three locations: S37C (close to the transmembrane domain), S4C (close to the NH2-terminus), and S28C (in between). S37C and S28C mutations did not affect channel properties or hIsK response to TMS. On the other hand, S4C mutation reduced current expression even when S4C cRNA was injected at a quantity 50-fold higher than that of the other three proteins. Importantly, the response to TMS was markedly reduced in S4C compared with the other three proteins. Therefore, the NH2-terminus of hIsK may be involved in hIsK interaction with the SH-bearing subunit, and this interaction modulates slow delayed rectifier channel function.

Animals↗
PubMed1997

Effect of hypoxia on blood glucose, hormones, and insulin receptor functions in newborn calves.

At between 7 and 11 h after delivery, 14 fasted calves were randomly divided into two groups to examine the effects of neonatal hypoxia on blood glucose metabolism and its mechanisms. One group was subjected to breathe a gas mixture containing 4.8-5.9% oxygen in nitrogen from a hood for 2 h. The second control group breathed atmospheric gas. Several possible causes of changes in blood glucose were assessed, including insulin, glucagon, and hydrocortisone as prereceptor factors, insulin binding as a receptor factor, and insulin receptor tyrosine kinase (IR-TK) activity as a postbinding factor. The hypoxic animals exhibited increased concentrations of blood glucose (from 5.47 +/- 1.61 mmol/L to 7.97 +/- 1.30 mmol/L), plasma insulin, and hydrocortisone, but decreased concentrations of glucagon. The percentage of specific binding activity decreased in the hypoxic group compared with the control group (12.71 +/- 1.25% versus 15.14 +/- 1.27%, p < 0.01). Several parameters of insulin receptor binding, i.e. affinity constants, high and low binding capacities, and numbers of binding sites, showed a tendency to decrease after hypoxia. Only lower affinity binding sites decreased significantly. At the postreceptor level, IR-TK activity was decreased in the hypoxic group compared with controls. It is concluded that hypoxia induced insulin resistance in these newborn calves. The results suggest that the primary mechanism for insulin resistance in the hypoxic newborn was reduced insulin receptor responsiveness with attenuated activity of IR-TK at the postreceptor level.

Acid-Base Equilibrium↗
PubMed1997

[Study on the relationship between primary Sjögren syndrome and HLA-DRbeta gene].

The pathogenesis of primary Sjögren syndrome (PSS) is unclear yet. In order to investigate the role of genetic factor playing in the mechanism of this disorder, we studied the HLA-DR beta gene distributed in 70 patients with PSS and 136 normal subjects by using PCR-SSP technique. The results showed that the gene frequences of HLA-DR3, DR52 and DR2 in patients with PSS were significantly higher than that in normal controls. However, the gene frequencies of HLA-DR5 and DR9 in PSS patients were lower than that in the control group. There were the same genetic phenomena in the siblings of two PSS patients' families. We also found the relationship between HLA-DR52 and the anti-antibodies of SSA or SSB. Our results concluded that the genetic factor is involved in the pathogenesis of primary Sjögren syndrome.

Adult↗