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Biomedical subjects

Ming Li

Publications and source records attributed to Ming Li.

At least 127 records · Page 7Linked to original sources
PubMed2006

[The relationship between the efficacy of interferon-alpha treatment and the variation of perforin protein expression in peripheral blood mononuclear cells in chronic hepatitis B patients].

OBJECTIVE: To study the relationship between the efficacy of interferon-alpha and the variation of perforin protein expression in the peripheral blood mononuclear cells in 35 patients with chronic hepatitis B (CHB). METHODS: The perforin protein in the peripheral blood mononuclear cells was detected by immunocytochemistry technique. RESULTS: The level of the perforin protein expression in the peripheral blood mononuclear cells was significantly higher in the post-treatment group with interferon-alpha than in the pre-treatment group. At the end of the treatment with interferon-alpha, there were 12 cases of complete responders, 14 cases of partial responders, and 9 cases of non-responders. After interferon-alpha treatment, the mean level of the perforin protein expression in the peripheral blood mononuclear cells was 12.1%, 6.9% and 3.9% respectively, and there existed significant differences among the three groups. Moreover, before treatment, the level of the perforin protein expression in the complete responder group was significantly higher compared to the partial responder group or the non-responder group. CONCLUSION: Treatment with interferon-alpha can increase the perforin protein expression in the peripheral blood mononuclear cells in patients with CHB. The variation of perforin protein expression in the peripheral blood mononuclear cells may be closely related to the efficacy of interferon-alpha treatment against hepatitis B virus.

Adult↗
PubMed2006

[Pathologic diagnosis of early syphilis in nasal cavity and oropharynx].

OBJECTIVE: To study the pathologic changes in nasal and oropharyngeal mucosa caused by treponema pallidum (TP) infection. METHODS: Twenty-five cases of nasal and oropharyngeal syphilis were retrieved from the archival files of Department of Pathology of Beijing Tong Ren Hospital collected during the period from June 1996 to September 2005. The hematoxylin and eosin-stained slides were reviewed. Histochemical study using modified Warthin-Starry stain and immunohistochemical study using polyclonal antibody for TP were carried out. The diagnosis of early syphilis was confirmed by rapid plasma regain (RPR) and TP hemagglutination (TPHA) tests. RESULTS: Among the 25 cases studied, 20 showed neutrophil infiltration, microabscess formation and plasma cell infiltration in the lamina propria. Endothelial swelling of small blood vessels and syphilitic vasculitis was also seen. Tonsillar ulcers associated with abundant plasma cells, lymphocytes and histiocytes were noted in 14 cases. One of which demonstrated florid reactive lymphoid proliferation, with transforming lymphoid cells of various stages identified. Pseudoneoplastic squamous cell proliferation was seen in one case. Spirochetes were detected by modified Warthin-Starry stain in mucosal microabscesses and squamous epithelium in 20 cases, around small blood vessels in 5 cases, and on the surface of tonsillar ulcers in 14 cases. Abundant TP were also found in smears of exudates in 6 cases. TP antigen was detected in 4 cases by immunohistochemical staining. All the 25 cases studied were RPR (1:8 to 128) and TPHA-positive. CONCLUSIONS: Early syphilis involving nasal cavity and oropharynx has distinctive pathologic features. Detailed histologic examination, together with modified Warthin-Starry stain for demonstration of spirochetes, is important to obtain a correct diagnosis.

Adult↗
PubMed2006

[Effect and mechanism of recombinant hirudin on fibrinolysis].

AIM: To study the effect of recombinant hirudin (rH) on tPA-induced fibrinolysis and the possible mechanism of its action. METHODS: The effect of rH on thrombin-fibrin complex (Th-Fn) was detected by 99mTc labeled rH. In the in vitro clot lysis, tPA as plasminogen activator, and recalcified plasma as plasminogen resource were used to study the influence of rH on fibrinolysis by detecting TAFIa, D-Dimer and FXIII. RESULTS: In a canine model of femoral artery thrombosis, a clear radioactivity strip was imaged in 30 - 60 min on a part image, and the femoral vein thrombosis developed at 30 min. rH efficiently inhibited clot regeneration. Addition of TM could inhibit clot lysis obviously, and CPI could shorten the delay of clot lysis which due to TAFIa. There was a dose-dependent relationship with TM concentration and TAFI activation. FXIII activation was inhibited by low concentration of rH ( < or = 0.2 u x mL(-1)), and the level of fibrinolysis product, D-Dimer, increased. CONCLUSION: rH could inhibit the thrombin binding to fibrin. rH inhibited the activation of TAFI and FXIII by combining with thrombin which resulted in enhancement of thrombolysis.

Animals↗
PubMed2005

[Screening and preliminary identification of mimetic peptides of Plasmodium falciparum-infected erythrocyte membrane surface protein 1].

OBJECTIVE: To screen and identify mimetic peptides of Plasmodium falciparun-infected erythrocyte membrane surface protein 1 in order to explore anti-adhesive agent against cerebral malaria. METHODS: Phage-borne peptide KLYLIAEGSVAA was used as panning targets to select target binders in a disulfide-constrained heptapeptides library. Three rounds of biopanning were carried out and then ELISA and competitive ELISA were used to evaluate the binding character between phage-borne peptides and ICAM-1. The insert DNA sequences of positive clones were determined and their amino acid sequences were deduced. RESULTS: After three-round panning, 22 clones were randomly chosen from the third panning and analyzed. Three clones showed positive interaction with ICAM-1, and two of them possessed the amino acid sequence C-ITAVPVR-C, the other one was C-DIMGGYN-C. These peptides specifically inhibited the binding of 15.2 antibody to ICAM-1 detected by competitive ELISA. CONCLUSION: Two kinds of mimetic peptides of PfEMP-1 have been obtained, which can bind with ICAM-1 specifically.

Amino Acid Sequence↗
PubMed2005

Fourfold structure of vortex-core states in Bi2Sr2CaCu2O8+delta.

We present a detailed study of vortex-core spectroscopy in slightly overdoped Bi2Sr2CaCu2O8+delta using a low-temperature scanning tunneling microscope. Inside the vortex core, we observe a fourfold symmetric modulation of the local density of states with an energy-independent period of (4.3 +/- 0.3)a0. Furthermore, we demonstrate that this square modulation is related to the vortex-core states which are located at +/-6 meV. Since the core-state energy is proportional to the superconducting gap magnitude , our results strongly suggest the existence of a direct relation between the superconducting state and the local electronic modulations in the vortex core.

Journal Article↗
PubMed2005

Solution structure of the Set2-Rpb1 interacting domain of human Set2 and its interaction with the hyperphosphorylated C-terminal domain of Rpb1.

The phosphorylation state of the C-terminal repeat domain (CTD) of the largest subunit of RNA polymerase II changes as polymerase transcribes a gene, and the distinct forms of the phospho-CTD (PCTD) recruit different nuclear factors to elongating polymerase. The Set2 histone methyltransferase from yeast was recently shown to bind the PCTD of elongating RNA polymerase II by means of a novel domain termed the Set2-Rpb1 interacting (SRI) domain. Here, we report the solution structure of the SRI domain in human Set2 (hSRI domain), which adopts a left-turned three-helix bundle distinctly different from other structurally characterized PCTD-interacting domains. NMR titration experiments mapped the binding surface of the hSRI domain to helices 1 and 2, and Biacore binding studies showed that the domain binds preferably to [Ser-2 + Ser-5]-phosphorylated CTD peptides containing two or more heptad repeats. Point-mutagenesis studies identified five residues critical for PCTD binding. In view of the differential effects of these point mutations on binding to different CTD phosphopeptides, we propose a model for the hSRI domain interaction with the PCTD.

Amino Acid Sequence↗
PubMed2005

HSF1 down-regulates XAF1 through transcriptional regulation.

Studies have indicated the role of HSF1 (heat-shock transcription factor 1) in repressing the transcription of some nonheat shock genes. XAF1 (XIAP-associated factor 1) was an inhibitor of apoptosis-interacting protein with the effect of antagonizing the cytoprotective role of XIAP. XAF1 expression was lower in gastrointestinal cancers than in normal tissues with the mechanism unclear. Here we showed that gastrointestinal cancer tissues expressed higher levels of HSF1 than matched normal tissues. The expression of XAF1 and HSF1 was negatively correlated in gastrointestinal cancer cell lines. Stress stimuli, including heat, hypo-osmolarity, and H2O2, significantly suppressed the expression of XAF1, whereas the alteration of HSF1 expression negatively correlated with XAF1 expression. We cloned varying lengths of the 5'-flanking region of the XAF1 gene into luciferase reporter vectors, and we evaluated their promoter activities. A transcription silencer was found between the -592- and -1414-nucleotide region that was rich in nGAAn/nT-TCn elements (where n indicates G, A, T, or C). A high affinity and functional HSF1-binding element within the -862/-821-nucleotide region was determined by electrophoretic mobility shift assay and chromatin immunoprecipitation assay. Inactivation of this "heat-shock element" by either site-directed mutation or an HSF1 inhibitor, pifithrin-alpha, restored the promoter activity of the silencer structure. Moreover, pretreatment with antioxidants suppressed HSF1 binding activity and increased the transcriptional activity and expression of XAF1. These findings suggested that endogenous stress pressure in cancer cells sustained the high level expression of HSF1 and subsequently suppressed XAF1 expression, implicating the synergized effect of two anti-apoptotic protein families, HSP and inhibitors of apoptosis, in cytoprotection under stress circumstances.

5' Flanking Region↗
PubMed2005

Crystal structure of a non-hemorrhagic fibrin(ogen)olytic metalloproteinase complexed with a novel natural tri-peptide inhibitor from venom of Agkistrodon acutus.

Thrombotic occlusive diseases pose a great threat to human health. Thrombolytic agents are in widespread use for the dissolution of arterial and venous pathologic thrombi in these kinds of diseases. Snake venom metalloproteinases (SVMPs) can act directly on fibrin/fibrinogen and are therefore potential candidates for therapeutic use against thrombotic occlusive diseases. In this study, we have determined the crystal structure of FII, a novel non-hemorrhagic SVMP isolated from Anhui Agkistrodon acutus snake venom by molecular replacement. The structure reveals that FII is a member of the P-I class SVMPs. The Zn2+ ion essential for hydrolytic activity is found in the active site and is tetrahedrally co-ordinated by three histidine residues and water molecule. Unambiguous electron density for a tri-peptide with sequence KNL is also found located near the active site. Biochemical evidences show that the tri-peptide KNL can inhibit the enzymatic activity of FII.

Amino Acid Sequence↗
PubMed2005

[Polymorphism of metabolic gene and genetic susceptibility to prostate cancer].

OBJECTIVE: To study the possible relationship between the single nucleotide polymorphism (SNP) of cytochrome P-450 CYP1A1 (CYP1A1) m1, m2 and GSTM1 [null] genotype and genetic susceptibility to prostate cancer (PC). METHODS: Eighty-three PC patients and 115 age-matched healthy controls were enrolled in this study. All DNA samples from peripheral blood were genotyped for genetic polymorphisms of CYP1A1 and GSTM1 genes by genechip technique. RESULTS: There was a significant difference in the frequency of GSTM1 [null] genotype in PC cases (57.8%) compared to healthy controls (41.7%) (chi(2) = 4.99, P = 0.025). Individuals with the GSTM1 [null] genotype demonstrated increased risk (OR = 1.9, 95% CI = 1.10-1.34). The frequency of the GSTM1 [null] genotype was also higher in patients with advanced stage or high grade disease. There were no significant differences in the frequent distribution of two locate of CYP1A1 polymorphisms between prostate cancer patients and healthy controls (P > 0.05). CONCLUSIONS: GSTM1 [null] genotype may be linked to prostate cancer risk in Chinese population. GSTM1 [null] genotype was also related to the stage and grade, which may be helpful in determining the risk of locally disease and advanced PC.

Aged↗
PubMed2005

Saikosaponin-d inhibits T cell activation through the modulation of PKCtheta, JNK, and NF-kappaB transcription factor.

The effects of saikosaponin-d, a triterpene saponin derived from Bupleurum falcatum L. (Umbelliferae), on the signaling pathways of T cell activation were examined. The results showed that saikosaponin-d potently suppressed both early (CD69) and late (CD71) expressions of mouse T cells stimulated with Con A or PMA. It interfered with PKCtheta translocation from cytosol to membrane fraction and inhibited the phosphorylations of IkappaBalpha and JNK, but not ERK, in PMA-activated mouse T cells. Additionally, it inhibited PMA and ionomycin-stimulated IL-2 production in mouse T cells. In summary, these results indicate that the mechanism by which saikosaponin-d inhibits T cell activation would involve the suppression of CD69 and CD71 expressions and IL-2 production, and the modulation of PKC pathway through PKCtheta, JNK, and NF-kappaB transcription factor. This may herald a novel approach for further studies of saikosaponin-d as a candidate for use in the treatment of inflammatory and autoimmune diseases.

Animals↗
PubMed2005

[Shape-memory alloy net-like stent for the management of ureteral stricture: a long-term follow-up report].

OBJECTIVE: To investigate the long-term outcome of treatment of ureteral stricture with shape-memory alloy net-like stent. METHODS: Nickel-titanium shape-memory alloy net-like stent was used to treat 9 patients with ureteral stricture, 4 males and 5 females, aged 41 (29-63), with the length of ureteral stricture of 1.0-4.0 cm, the etiology being radical operation for rectal carcinoma in 2 cases, chronic inflammation in 3 case, and operation for benign diseases in 4 cases. A total of 10 stents were inserted under spinal anesthesia. The mean follow-up time was 27.2 months (5-96 months). RESULTS: Ureteral obstruction was relieved in 7 cases (77.8%) with the relief or disappearance of hydronephrosis. The ureteral stents were blocked and re-obstruction appeared in 2 cases within 5-6 months due to hyperplasia of fibrous tissue. One of the cases underwent removal of stent and the other case underwent insertion of double-J with improvement of renal function. No radiological evidence of migration of stent and encrustation was found. CONCLUSION: More tolerable and with less side-effect and lower re-stricture rate, shape-memory alloy stent is better then Double-J in treatment of ureteral obstruction.

Adult↗
PubMed2005

From dopamine to salience to psychosis--linking biology, pharmacology and phenomenology of psychosis.

How does an excess in a neurochemical lead someone to being paranoid about the intentions of their neighbour? And why does blocking a dopamine receptor improve this symptom? In this article we present a heuristic framework which attempts to link the biology, phenomenology and pharmacology of psychosis. Focussing on dopamine's role in reward prediction and motivational salience we propose that psychosis arises from an aberrant assignment of novelty and salience to objects and associations. Antipsychotics block dopamine receptors and decrease dopamine transmission, which leads to the attenuation of aberrant novelty and salience. This 'salience' framework accounts for existing data and questions several current assumptions about the speed of onset phenomenological effects of antipsychotics and their behavioral effects in animal models. We review new data to show that in contrast to the prevailing idea of a "delayed onset" of antipsychotic action, the improvement is evident in the first few days. Antipsychotics do not eradicate symptoms, but create a state of "detachment" from them. And the actions of antipsychotics in the conditioned avoidance response model, one of the best established animal models for identifying antipsychotic action, are consistent with the idea that they dampen aberrant as well as normal motivational salience. The article discusses the caveats, limitations as well as the clinical implications of the salience framework.

Antipsychotic Agents↗
PubMed2005

Ab initio computational insight into the ion-pair S(N)2 reaction of lithium isothiocyanate and methyl fluoride in the gas phase and in acetone solution.

The ion-pair S(N)2 reaction LiNCS + CH3F with two mechanisms, inversion and retention, was investigated at the MP2(full)/6-311+G**//HF/6-311+G** level in the gas phase and in acetone solution. All HF-optimized structures were confirmed by vibrational frequency analysis. Based on IRC analyses, eight possible reaction pathways in the title reaction are proposed. The inversion mechanism through a six-membered-ring transition-state structure is the most favorable. Methyl thiocyanate should form preferentially in the gas phase and the more stable methyl isothiocyanate will be the main product in CH3COCH3. The retardation of the reaction in CH3COCH3 solution was attributed to the differences in the solvation free energies in the separated reactants and transition structures. All of the theoretical results are consistent with the experiment.

Acetone↗
PubMed2005

Resveratrol reduces intracellular free calcium concentration in rat ventricular myocytes.

Resveratrol (trans-3, 4', 5-trihydroxy stilbene), a phytoalexin found in grape skins and red wine, has been reported to have a wide range of biological and pharmacological properties. It has been speculated that resveratrol may have cardioprotective activity. The objective of our study was to investigate the effects of resveratrol on intracellular calcium concentration ([Ca(2+)](i)) in rat ventricular myocytes. [Ca(2+)](i) was detected by laser scanning confocal microscopy. The results showed that resveratrol (15~60 mumol/L) reduced [Ca(2+)](i) in normal and Ca(2+)-free Tyrode's solution in a concentration-dependent manner. The effects of resveratrol on [Ca(2+)](i) in normal Tyrode's solution was partially inhibited by pretreatment with sodium orthovanadate (Na3VO4, 1.0 mmol/L, P<0.01), an inhibitor of protein tyrosine phosphatase, or L-type Ca(2+) channel agonist Bay K8644 (10 mumol/L, P<0.05), but could not be antagonized by NO synthase inhibitor L-NAME (1.0 mmol/L). Resveratrol also markedly inhibited the ryanodine-induced [Ca(2+)](i) increase in Ca(2+)-free Tyrode's solution (P<0.01). When Ca(2+) waves were produced by increasing extracellular Ca(2+) concentration from 1 to 10 mmol/L, resveratrol (60 mumol/L) could reduce the velocity and duration of propagating waves, and block the propagating waves of elevated [Ca(2+)](i). These results suggest that resveratrol may reduce the [Ca(2+)](i) in isolated rat ventricular myocytes. The inhibition of voltage-dependent Ca(2+) channel and tyrosine kinase, and alleviation of Ca(2+) release from sarcoplasmic reticulum (SR) are possibly involved in the effects of resveratrol on rat ventricular myocytes. These findings could help explain the protective activity of resveratrol against cardiovascular disease.

Animals↗
PubMed2005

Effects of novel antipsychotics, amisulpiride and aripiprazole, on maternal behavior in rats.

RATIONALE: Rat maternal behavior, which entails complex motivational and social factors, is disrupted by the currently available typical and atypical antipsychotics. It is thought that this disruption reflects a side effect of antipsychotics, modeling the neuroleptic-induced negative or deficit state. Amisulpiride and aripiprazole are new atypical antipsychotics with mechanisms of action distinct from the current typical and atypical antipsychotics. The effects of these drugs on maternal behavior have not been explored. OBJECTIVE: In the present study, we systematically examined the behavioral effects of amisulpiride and aripiprazole on maternal behavior in postpartum female rats. METHODS: Various components of maternal behavior (pup retrieval, pup licking, nest building and pup nursing) were examined repeatedly over a period of 24 h after a single injection of three doses of amisulpiride (10, 30, and 100 mg/kg s.c.) and aripiprazole (3, 10, and 30 mg/kg). RESULTS: Amisulpiride at the lower doses (10 and 30 mg/kg) enhanced pup licking, and only at the highest dose disrupted the active components of maternal behavior such as pup retrieval and nest building. Its effect was delayed in onset and prolonged as compared to other antipsychotics. Aripiprazole, even at the highest dose (30 mg/kg) did not impair pup retrieval or pup licking. However, it did disrupt nest building and led to enhanced pup nursing. CONCLUSIONS: The unique effects of these two drugs may be due to their unique actions at the mesolimbic dopamine synapses. The sparing of the major components of maternal behavior by aripiprazole may be related to its partial agonist effects, whereas the enhancement of pup licking by amisulpiride may be related to its dose-dependent preferential effect on the presynaptic autoreceptors. The potential clinical implications of these findings are discussed.

Amisulpride↗
PubMed2005

Substrate temperature effect on the refractive index and a two-step film method to detect small inhomogeneities in optical films.

Nb2O5 films were deposited by a reactive magnetron sputtering technique. The average refractive index was found to increase with the rise of substrate temperature. Modulated interference transmittance spectra were observed in the two-step films, which were prepared by stopping the deposition process in the middle of the designed sputtering time, and then, after a full cooling down to room temperature, starting the same deposition process again to complete the whole preparation of the films. A linearly graded-index model was used to explain the interference behavior. It was proved that the two-step film method was sensitive to the small inhomogeneity in the films. We also suggest that the inhomogeneity of sputtered films can be minimized by controlling the substrate temperature at a constant value.

Journal Article↗