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Biomedical subjects

Ming Li

Publications and source records attributed to Ming Li.

At least 343 records · Page 19Linked to original sources
PubMed2003

Analysis of the polycystins in aortic vascular smooth muscle cells.

The leading cause of death in autosomal dominant polycystic kidney disease (ADPKD) is cardiovascular. However, little is known about the pathogenesis of these manifestations. The present study was undertaken to characterize the ADPKD proteins, the polycystins, in vascular smooth muscle cells. It was demonstrated that the expression of polycystin-1 is developmentally regulated, whereas polycystin-2 has a more constant level of expression. A polycystin-1 subpopulation was immunoprecipitated by polycystin-2, indicating an in vivo interaction of these two proteins. Analysis with glycosidase and cell surface biotinylation indicates that some polycystin-1 products, but not polycystin-2, are located on the plasma membrane. Immunofluorescence showed that most of the polycystin-1 and polycystin-2 was cytoplasmic but that persistent polycystin-1 staining was located in proximity to the cell surface after a Triton-X extraction, whereas no clear surface localization of polycystin-2 was detected. Immuno-gold electron microscopy revealed that polycystin-1 was localized at the plasma membrane and sarcoplasmic reticulum, whereas polycystin-2 was mainly located in the sarcoplasmic reticulum. Both polycystins were found to be associated with dense plaques. These observations are consistent with an important role of the polycystins in the development, maintenance, and function of the myoelastic arterial organization and with the vascular phenotype associated with ADPKD.

Animals↗
PubMed2003

Resting CD4+ T lymphocytes but not thymocytes provide a latent viral reservoir in a simian immunodeficiency virus-Macaca nemestrina model of human immunodeficiency virus type 1-infected patients on highly active antiretroviral therapy.

Despite suppression of viremia in patients on highly active antiretroviral therapy (HAART), human immunodeficiency virus type 1 persists in a latent reservoir in the resting memory CD4(+) T lymphocytes and possibly in other reservoirs. To better understand the mechanisms of viral persistence, we established a simian immunodeficiency virus (SIV)-macaque model to mimic the clinical situation of patients on suppressive HAART and developed assays to detect latently infected cells in the SIV-macaque system. In this model, treatment of SIV-infected pig-tailed macaques (Macaca nemestrina) with the combination of 9-R-(2-phosphonomethoxypropyl)adenine (PMPA; tenofovir) and beta-2',3'-dideoxy-3'-thia-5-fluorocytidine (FTC) suppressed the levels of plasma virus to below the limit of detection (100 copies of viral RNA per ml). In treated animals, levels of viremia remained close to or below the limit of detection for up to 6 months except for an isolated "blip" of detectable viremia in each animal. Latent virus was measured in blood, spleen, lymph nodes, and thymus by several different methods. Replication-competent virus was recovered after activation of a 99.5% pure population of resting CD4(+) T lymphocytes from a lymph node of a treated animal. Integrated SIV DNA was detected in resting CD4(+) T cells from spleen, peripheral blood, and various lymph nodes including those draining the gut, the head, and the limbs. In contrast to the wide distribution of latently infected cells in peripheral lymphoid tissues, neither replication-competent virus nor integrated SIV DNA was detected in thymocytes, suggesting that thymocytes are not a major reservoir for virus in pig-tailed macaques. The results provide the first evidence for a latent viral reservoir for SIV in macaques and the most extensive survey of the distribution of latently infected cells in the host.

Animals↗
PubMed2003

RAPTOR: optimal protein threading by linear programming.

This paper presents a novel linear programming approach to do protein 3-dimensional (3D) structure prediction via threading. Based on the contact map graph of the protein 3D structure template, the protein threading problem is formulated as a large scale integer programming (IP) problem. The IP formulation is then relaxed to a linear programming (LP) problem, and then solved by the canonical branch-and-bound method. The final solution is globally optimal with respect to energy functions. In particular, our energy function includes pairwise interaction preferences and allowing variable gaps which are two key factors in making the protein threading problem NP-hard. A surprising result is that, most of the time, the relaxed linear programs generate integral solutions directly. Our algorithm has been implemented as a software package RAPTOR-RApid Protein Threading by Operation Research technique. Large scale benchmark test for fold recognition shows that RAPTOR significantly outperforms other programs at the fold similarity level. The CAFASP3 evaluation, a blind and public test by the protein structure prediction community, ranks RAPTOR as top 1, among individual prediction servers, in terms of the recognition capability and alignment accuracy for Fold Recognition (FR) family targets. RAPTOR also performs very well in recognizing the hard Homology Modeling (HM) targets. RAPTOR was implemented at the University of Waterloo and it can be accessed at http://www.cs.uwaterloo.ca/~j3xu/RAPTOR_form.htm.

Algorithms↗
PubMed2003

Determination of carbamazepine by chemiluminescence detection using chemically prepared tris(2,2'-bipyridine)ruthenium(III) as oxidant.

A new chemiluminescence method for the determination of carbamazepine (CBZ) has been developed. The method is based on the chemiluminescence produced in the reaction of tris(2,2'-bipyridine)ruthenium(III) and CBZ in an acidic medium. The chemiluminescence intensity was enhanced by organic solvents in the reaction system. Under the optimum experimental conditions, the calibration curve was linear over the range 4.0 x 10(-3)-8.6 x 10(-7) mol/L for CBZ. The detection limit (S/N = 3) was 2.5 x 10(-7) mol/L and the relative standard deviation of six replicate measurements was 2.6% for 4.0 x 10(-4) mol/L of CBZ. The possible reaction mechanism were also discussed. The chemiluminescence method was successfully applied to assay the CBZ contents in pharmaceutical tablets.

2,2'-Dipyridyl↗
PubMed2003

Overexpression of PACAP in transgenic mouse pancreatic beta-cells enhances insulin secretion and ameliorates streptozotocin-induced diabetes.

Pituitary adenylate cyclase-activating polypeptide (PACAP), a member of the vasoactive intestinal peptide/secretin/glucagon family, stimulates insulin secretion from islets in a glucose-dependent manner at femtomolar concentrations. To assess PACAP's pancreatic function in vivo, we generated transgenic mice overexpressing PACAP in the pancreas under the control of human insulin promoter. Northern blot and immunohistochemical analyses showed that PACAP is overexpressed in pancreatic islets, specifically in transgenic mice. Plasma glucose and glucagon levels during a glucose tolerance test were not different between PACAP transgenic mice and nontransgenic littermates. However, plasma insulin levels in transgenic mice were higher after glucose loading. Also, increases of streptozotocin-induced plasma glucose were attenuated in transgenic compared with nontransgenic mice. Notably, an increase in 5-bromo-2-deoxyuridine-positive beta-cells in the streptozotocin-treated transgenic mice was observed but without differences in the staining patterns by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling. Morphometric analysis revealed that total islet mass tends to increase in 12-month-old transgenic mice but showed no difference between 12-week-old transgenic and nontransgenic littermates. This is the first time that PACAP has been observed to play an important role in the proliferation of beta-cells.

Animals↗
PubMed2003

Angiography for diagnosis and treatment of colorectal cancer.

AIM: To evaluate the role of preoperative angiography in the diagnosis and treatment of colorectal cancer. METHODS: The authors performed selective arterial cannulation by Seldinger's method in 47 patients to locate the primary cancer and to diagnose metastasis to the liver. Each patient was then given intra-arterial regional chemotherapy, and received 5-fluorouracil (5-Fu, 1 000 mg), mitomycin C (MMC, 20 mg), and cisplatinum (CDDP, 80 mg). RESULTS: The location and shape of each tumor were observed, including metastatic tumors in the liver, in 42 of the 47 (89.4 %) patients. The site of the primary tumor was difficult to identify in 5 cases because the patients had a recurrence of cancer. Arterial chemotherapy was performed successfully in all patients. The authors recorded no partial or significant morbidity resulted from angiography. The only incident was bleeding from the artery puncture site in one patient, which was successfully stopped by general medication. CONCLUSION: Preoperative selective arterial angiography can help the diagnosis and locate primary tumors and to detect liver metastasis. At the same time, regional arterial chemotherapy can be an important form of preoperative therapy.

Adult↗
PubMed2003

Protein threading by linear programming.

Protein three-dimensional structure prediction through threading approach has been extensively studied and various models and algorithms have been proposed. In order to further explore ways to improve accuracy and efficiency of the threading process, this paper investigates the effectiveness of a new method: protein threading via linear programming. Based on the contact map model of protein 3D structure, we formulate the protein threading problem as a large scale integer programming problem, then relax to a linear programming problem, and finally solve the integer program by a branch-and-bound method. The final solution is optimal with respect to energy functions incorporating pairwise interaction and allowing variable gaps. The algorithm has been implemented as software package RAPTOR--RApid Protein Threading predictOR. Experimental results for fold recognition show that RAPTOR significantly outperforms other programs at the fold similarity level. The RAPTOR webserver is at http://www.cs.uwaterloo.ca/-j3xu/RAPTOR_form.htm.

Algorithms↗
PubMed2003

Met receptor overexpression and oncogenic Ki-ras mutation cooperate to enhance tumorigenicity of colon cancer cells in vivo.

We have investigated the influence of Ki-ras oncogene on Met/hepatocyte growth factor (HGF) receptor signaling in human carcinoma cells. The model system used in these studies included the DLD-1 colon cancer cell line with a mutated Ki-ras allele, and the DKO-4 cell line generated from DLD-1, with its mutant Ki-ras allele inactivated by targeted disruption. These cell lines were transduced with cDNAs of either active Met receptor or dominant negative Met receptor. As compared to the DLD-1 cells, constitutive overexpression of Met receptor in this cell line (DLD-1-Met) resulted in increased tumorigenicity in SCID mice. In contrast, overexpression of Met in DKO-4 cells (DKO-4-Met) that have lost oncogenic Ras activity demonstrated suppressed tumorigenicity with respect to the parent DKO-4 cell line. Tumors formed by the DLD-1-Met cells showed increased levels of mitogen-activated protein kinase (MAPK) and lower levels of apoptosis compared to the DKO-4-Met tumors. Overexpression of the dominant negative Met receptor cDNA decreased the Met phosphorylation levels in both DLD-1 and DKO-4 cells, but only suppressed tumorigenicity in the DKO-4 cell line. In vitro, HGF stimulation of DLD-1 cells resulted in a prolonged duration of MAPK activation, while DKO-4 cells exhibited a rapid attenuation of MAPK phosphorylation. The results suggest that Ki-ras mutations and HGF signaling cooperate to enhance tumor growth by increased duration of MAPK activation and decreased apoptosis in human carcinoma cells.

Apoptosis↗
PubMed2003

[Immunohistochemical identification of adrenomedullin in adrenal diseases].

OBJECTIVE: Adrenomedullin (ADM) is a hypotensive peptide isolated from human pheochromocytoma tissue. In order to identify the pathophysiological effects of ADM on the etiology of adrenal diseases which can induce hypertension, the localization of immunoreactive adrenomedullin (ir-ADM) in adrenal tissue of subjects with normal adrenal and patients with different adrenal diseases was investigated by means of immunohistochemical staining. METHODS: Peroxidase anti-peroxidase complex method was undertaken in the tissue of human adrenal cortex (n = 10) and medulla (n = 10)of subjects with normal adrenal, as well as in the tissue of pheochromocytoma (n = 31), primary aldosteronism including adrenocortical adenoma (n = 13) and hyperplasia (n = 9), Cushing's syndrome including adrenocortical adenoma (n = 12), hyperplasia (n = 10), carcinoma (n = 4) and non-functional adrenocortical carcinoma (n = 7). RESULTS: Positive immunohistochemical staining of ir-ADM was observed in all the cases of normal adrenal medulla and 16 of the 31 cases of pheochromocytoma. The intensity of immunohistochemical staining of ir-ADM in the majority of pheochromocytoma was lower than that in normal adrenal medulla (P < 0.01). The number of pheochromocytoma cases with positive staining in paroxysmal hypertensive group was higher than that in sustained hypertensive group (P < 0.05). Negative immunohistochemical staining was found in all the cases of normal human adrenal cortex, adrenocortical adenoma, hyperplasia and carcinoma. CONCLUSION: It is suggested that heterogeneous of localization of ir-ADM in pheochromocytoma tissue may be correlated to the diversity of blood pressure in patients with pheochromocytoma. The pathophysiological effects of ADM on the etiology of pheochromocytoma should be further investigated.

Adrenal Cortex↗
PubMed2003

[Cloning of hepatitis C virus open reading frame sequence and non structural protein expressions of the virus].

OBJECTIVE: To induce the expressions of the constituent proteins of hepatitis C virus (HCV) using a vaccinia virus expression system. METHODS: The open reading frame (ORF) sequence encoding HCV large polyprotein precursor was cloned into a vaccinia virus promoter to construct the recombinant plasmid pVHCV, which was subsequently used, along with a control plasmid (pSC59) in a parallel experiment, to transfect BHK21 cells via Lipofectamine 2000 reagent, followed by infection of the cells with vTF7-3 vaccinia viruses. After a 48-h culture, the expressions of HCV nonstructural proteins NS3 and NS5a in the cells were detected using Western blotting and immunofluorescence assay. RESULTS: Western blotting analysis presented the nonstructural proteins NS3 and NS5a detected in pVHCV-transfected BKH21 cells as two bands with molecular weights of 70,000 and 56,000, respectively. In the immunofluorescence assay, intense granular fluorescence signal was detected in the cytoplasm of pVHCV-transfected cells, irrespective of the use of either NS3- or NS5a- specific mouse monoclonal antibody. CONCLUSION: HCV nonstructural proteins NS3 and NS5a can be expressed in BKH21 cells.

Animals↗
PubMed2003

[Surgical treatment and function rehabilitation of Monteggia fracture in children].

OBJECTIVE: To establish better treatment for Monteggia fracture by evaluating the operative effect and function rehabilitation in children. METHODS: From 1994 to 2001, 78 children with Monteggia fracture (30 cases of new fracture, 48 cases of old fracture) were treated with open reduction and internal fixation. The patients were randomly divided into two groups. In the first group (45 cases, 16 new and 29 old), radius-humeral joint was fixed with a Kirschner wire after reduction and without fixation of ulna fracture; in the second group(33 cases, 14 new and 19 old), both radiohumeral joint and ulna fracture were fixed with Kirschner wire. Two groups were treated with plaster-splint after operation. The effect of operation was evaluated according to the function criteria for bending elbow and rotation of forearm. RESULTS: All patients were followed up 6 months to 7 years (4.6 years on average). All wound healed well without bone nonunion, delayed union and infection after operation. In the first group, 37 cases were rated as excellent, 5 good and 3 poor. The effective rate was 93.3%. In the second group, 22 cases were rated as excellent, 7 good and 4 poor. The effective rate was 87.9%. There was no significant difference between two groups (P > 0.05). CONCLUSION: Surgical treatment is the choice for Monteggia fracture in children. It should be treated with single Kirschner wire fixing after open reduction of radiohumeral and plaster-splint. This method is simple, safe and has satisfactory results in fracture healing and function rehabilitation after operation.

Adolescent↗
PubMed2003

[A dual-color fluorescence in situ hybridization study on the detection of inv(16) in acute myeloid leukemia].

OBJECTIVE: To explore the value of dual-color fluorescence in situ hybridization (D-FISH) in the detection of inv(16) in acute myeloid leukemia (AML). METHODS: Eleven AML patients were investigated by D-FISH with two-color break apart probe for MYH11 labeled directly by fluorescein isocyanate (FITC) and a Texas Red. The results were associated or compared with those of cell morphology, cytogenetics, single color fluorescence in situ hybridization (FISH) and reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: Four cases (M4Eo three cases, M2a one case) had inv(16), of which one had trisomy 22 in addition to inv(16), while the other seven cases had no inv(16), of which, five cases (M4Eo three cases, M4 two cases)had a normal karyotype, one (M2a) had 5p+ and trisomy 22, one (M4Eo) had a translocation t(9;22) on G-banded karyotypic analysis. All 11 cases of AML were positive for the rearrangement of inv(16) detected by D-FISH. The average positive cell rate for these 11 AML patients was 93.45% (range 86.6%-98.7%). Of them, four had a minimal deletion of 16p13 in addition to inv(16). The results of D-FISH coincided with those of RT-PCR or single color FISH. CONCLUSION: D-FISH is a powerful tool for the detection of inv(16) due to its sensitivity and specificity. For raising the detecting rate of inv(16), it is necessary to screen inv(16) rearrangement by D-FISH in all M4- and M2-AML cases or the cases with trisomy 22, no matter whether they are accompanied by bone marrow eosinophilia.

Chromosome Inversion↗
PubMed2003

[Synthesis, cloning, expression and antigenicity of the therapeutic multi-epitope gene of hepatitis B virus and of its products].

OBJECTIVE: To study the synthesis, cloning, expression and antigenicity of therapeutic multi-epitope gene of hepatitis B virus. METHODS: The therapeutic multi-epitope gene of hepatitis B virus was synthesized and cloned into the vector pWR450-1, then was expressed in E.coli and the products were purified. The immunogenicity of the expressed protein was analyzed by Western-blotting. RESULTS: Recombinant plasmid PWR/BPT was constructed successfully and the protein of multi-epitope gene of hepatitis B virus was expressed in E. coli, which showed ideal antigenicity by Western-blotting. CONCLUSIONS: The designed multi-epitope therapeutic gene of hepatitis B virus was proved to be correct and the expressed protein may be a good therapeutic vaccine.

Blotting, Western↗
PubMed2003

[Influence of simulated weightlessness on the morphology of nerve endings of muscle spindle in rat soleus muscle].

OBJECTIVE: To study changes in structure and innervation of soleus muscle spindle in rats induced by simulated weightlessness. METHOD: Weightlessness was simulated by tail suspension in female rats. The technique of Fawosky's Staining was used to detect the morphology of nerve endings of soleus muscle spindle in 7 d, 14 d, 21 d tail-suspended and control rats. RESULT: The intrafusal muscle fibers were regular and nerve endings were intact and clear in the soleus spindles of control rats. No obvious change was observed in muscle spindles of 7 d tail-suspended rats. Intrafusal muscle fibers became irregular, with rough and vague nerve endings in 14 d tail-suspended rats. The distinct retrograde change of muscle spindles and nerve endings were observed in 21 d tail-suspended rats. Degeneration and rupture were found in nerve endings, which made it unclear and pale in staining. CONCLUSION: Simulated weightlessness could induce time-related changes in structure and innervation of soleus muscle spindle in rats.

Animals↗