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Biomedical subjects

Ming Jiang

Publications and source records attributed to Ming Jiang.

At least 73 records · Page 4Linked to original sources
PubMed2003

Bcl-2 constitutively suppresses p53-dependent apoptosis in colorectal cancer cells.

To dissect apoptotic genes governing the survival of colorectal carcinoma cells, we employed RNAi to silence Bcl-2 and Bcl-x(L) in isogenic clones of p53+/+ and p53-/- cells, and of Bax+/- and Bax-/- cells. We identify a novel proapoptotic function of p53 that does not require activation by genotoxic agents and that appears to be constitutively suppressed by Bcl-2. Silencing of Bcl-2 induced massive p53-dependent apoptosis. The "Bcl-2/p53 axis" requires Bax and caspase 2 as essential apoptotic mediators. This newly discovered Bcl-2/p53 functional interface represents a key regulator of apoptosis which can be activated by targeting Bcl-2 in colorectal carcinoma cells.

Apoptosis↗
PubMed2003

Spatial variation of resolution and noise in multi-detector row spiral CT.

RATIONALE AND OBJECTIVES: The authors performed this study to evaluate an approach for measuring the variations of three-dimensional spatial resolution and image noise throughout a field of view imaged with multi-detector row spiral computed tomographic (CT) scanners. MATERIALS AND METHODS: The authors designed a phantom (diameter, 320 mm) that contained 37 metallic spheres (diameter, approximately 0.8 mm) positioned between two disks made of a material with attenuation being that of water. One sphere was located at the isocenter of the phantom, and the rest were evenly spaced in three concentric rings with diameters of 100, 200, and 300 mm, respectively. The phantom was imaged with two widely used multi-detector row CT scanners by using a standard protocol and four variations of that protocol. Because a recently developed theory holds that image resolution should be proportional to the square root of the trace of the covariance matrix of a point spread function, the authors developed a software package to segment high-attenuation spheres from the CT image volume and compute point spread functions from blurred images of the spheres. Three-dimensional spatial resolution and image noise were calculated as a function of radial distance within the field of view. RESULTS: Resolution and noise were quantified in the resultant CT image volumes and found to be nonisotropic, with worse resolution and less noise occurring at the periphery of the field of view. CONCLUSION: The method enabled measurement of variations in spatial resolution and of their distribution on images obtained with multi-detector row CT scanners. These findings may contribute to the development of an improved algorithm for image reconstruction.

Humans↗
PubMed2003

Convergence studies on iterative algorithms for image reconstruction.

We introduce a general iterative scheme for image reconstruction based on Landweber's method. In our configuration, a sequential block-iterative (SeqBI) version can be readily formulated from a simultaneous block-iterative (SimBI) version, and vice versa. This provides a mechanism to derive new algorithms from known ones. It is shown that some widely used iterative algorithms, such as the algebraic reconstruction technique (ART), simultaneous ART (SART), Cimmino's, and the recently designed diagonal weighting and component averaging algorithms, are special examples of the general scheme. We prove convergence of the general scheme under conditions more general than assumed in earlier studies, for its SeqBI and SimBI versions in the consistent and inconsistent cases, respectively. Our results suggest automatic relaxation strategies for the SeqBI and SimBI versions and characterize the dependence of the limit image on the initial guess. It is found that in all cases the limit is the sum of the minimum norm solution of a weighted least-squares problem and an oblique projection of the initial image onto the null space of the system matrix.

Algorithms↗
PubMed2003

Blind deblurring of spiral CT images.

To discriminate fine anatomical features in the inner ear, it has been desirable that spiral computed tomography (CT) may perform beyond their current resolution limits with the aid of digital image processing techniques. In this paper, we develop a blind deblurring approach to enhance image resolution retrospectively without complete knowledge of the underlying point spread function (PSF). An oblique CT image can be approximated as the convolution of an isotropic Gaussian PSF and the actual cross section. Practically, the parameter of the PSF is often unavailable. Hence, estimation of the parameter for the underlying PSF is crucially important for blind image deblurring. Based on the iterative deblurring theory, we formulate an edge-to-noise ratio (ENR) to characterize the image quality change due to deblurring. Our blind deblurring algorithm estimates the parameter of the PSF by maximizing the ENR, and deblurs images. In the phantom studies, the blind deblurring algorithm reduces image blurring by about 24%, according to our blurring residual measure. Also, the blind deblurring algorithm works well in patient studies. After fully automatic blind deblurring, the conspicuity of the submillimeter features of the cochlea is substantially improved.

Algorithms↗
PubMed2003

Blocking immune evasion as a novel approach for prevention and treatment of herpes simplex virus infection.

Many microorganisms encode immune evasion molecules to escape host defenses. Herpes simplex virus type 1 glycoprotein gC is an immunoevasin that inhibits complement activation by binding complement C3b. gC is expressed on the virus envelope and infected cell surface, which makes gC potentially accessible to blocking antibodies. Mice passively immunized with gC monoclonal antibodies prior to infection were protected against herpes simplex virus challenge only if the gC antibodies blocked C3b binding. Mice treated 1 or 2 days postinfection with gC monoclonal antibodies that block C3b binding had less severe disease than control mice treated with nonimmune immunoglobulin G (IgG). Mice immunized with gC protein produced antibodies that blocked C3b binding to gC. Immunized mice were significantly protected against challenge by wild-type virus, but not against a gC mutant virus lacking the C3b binding domain, suggesting that protection was mediated by antibodies that target the gC immune evasion domain. IgG and complement from subjects immunized with an experimental herpes simplex virus glycoprotein gD vaccine neutralized far more mutant virus defective in immune evasion than wild-type virus, supporting the importance of immune evasion molecules in reducing vaccine potency. These results suggest that it is possible to block immune evasion domains on herpes simplex virus and that this approach has therapeutic potential and may enhance vaccine efficacy.

Animals↗
PubMed2003

[PTEN expression and its significance in human primary hepatocellular carcinoma].

OBJECTIVES: To explore the significance of PTEN (phosphatase and tensin homolog deleted on chromosome 10) in the development of human primary hepatocellular carcinoma (HCC). METHODS: PTEN protein expression in cancerous liver tissues and paired para-carcinoma liver tissues from 60 HCC patients was detected by immunohistochemistry and PTEN mRNA expression was analyzed by northern blot. The significance of PTEN in the development of HCC was analyzed by investigating the relationship between the expression levels of PTEN protein and mRNA, and the clinicopathological parameters of HCC patients. RESULTS: PTEN protein was immunohistochemically stained in the cytoplasmic region of para-carcinoma liver tissues in all the 60 patients, while only 48.3% (29/60) of the patients were positive for PTEN protein in cancerous liver tissues. The positive rate of PTEN protein in HCC tissues were relative to the histological gading and the presence of tumor thrombus. In grade I - II, III, and IV, the positive rates were 84.0%, 23.8%, and 21.4% respectively, and in the group with tumor thrombus was 26.7%, while in the group without tumor thrombus was 55.6%. Northern blot showed that there existed four PTEN mRNA transcripts with the length of 5.5kb, 4.4kb, 2.4kb, and 1.8kb respectively. The level of PTEN mRNA expression in HCC tissues was much lower than that in the paired para-carcinoma liver tissues. The low expression level of the 5.5kb and 4.4kb transcripts was significantly associated with serum AFP value, presence of tumor thrombus, state of satellite lesion and histological grading. The low expression level of the 2.4kb transcript in HCC was significantly associated with the presence of tumor thrombus and satellite lesions in HCC patients. However, no evident relationship between the lowered expression level of the 1.8kb transcript and the clinicopathological parameters of HCC was observed in these 60 patients. CONCLUSIONS: Down-regulation of PTEN expression may play an important role in the development of HCC and the expression level of PTEN may be a potential adjuvant parameter in forecasting the progress and prognosis of HCC.

Adult↗
PubMed2003

[Effect of monocrotophos on Na+/K(+)-ATPase activity and ultramicrostructure of Sciaenops ocellatus branchiae].

The exposure of Sciaenops ocellatus to monocrotophos at its concentration of 0.25, 0.5, 1.0 or 2.0 mg L-1 for 4 days demonstrated that under the stress of low concentration (0.25 mg.L-1) monocrotophos, the chloride cells of branchiae proliferated, accompanied with the increase of Na+/K(+)-ATPase activity, while under high concentrations of monocrotophos, the damage of gill was much heavier, and the Na+/K(+)-ATPase activity also decreased. The damage in gill under sublethal monocrotophos exposure included hypertrophy and edema, and thus, the lamellar epithelium became thick and lifting, and the lamellae were bulbing or fusing. The ultramicrostructural changes of the gill of the exposure fish were the swollen and even rupture of rER, mitochondria, microtubule and nuclear membrane.

Animals↗
PubMed2003

[Three cyclic dipeptides from the root of Psammosilene tunicoides].

OBJECTIVE: [corrected] To study the cyclic peptides from Psammosilene tunicoides. METHOD: The constituents were separated and purified with chromatographic methods, identified by NMR, MS, UV and IR. RESULT: Three cyclic dipeptides: cyclo(-Pro-Val-) (1), cyclo(-Pro-Ala-) (2) and cyclo(-Pro-Pro-) (3), were isolated and identified. CONCLUSION: Compound 1 and 2 are new natural products, compound 3 was isolated for the first time from Psammosilene tunicoides.

Caryophyllaceae↗
PubMed2002

[Periodic changes in serum testosterone levels after ejaculation in men].

The purpose of this study was to determine the changes in sex hormone level in men after ejaculation. The serum testosterone concentrations of 28 male volunteers were investigated daily during abstinence period after ejaculation. We found that fluctuations of testosterone levels from day 2 to day 5 of abstinence were minimal. On day 7 of abstinence, a peak of serum testosterone appeared, reaching 145.7% of the baseline (P<0.01). After the peak, no regular fluctuation was observed. Ejaculation was the premise and beginning of the 7 days' periodic phenomenon. If there was no ejaculation, there was no periodical changes in serum testosterone level. These results indicate that the periodic change in serum testosterone level is caused by ejaculation.

Adult↗
PubMed2002

Selective silencing of viral gene expression in HPV-positive human cervical carcinoma cells treated with siRNA, a primer of RNA interference.

Selective silencing of mammalian gene expression has recently been achieved using short interfering RNA (siRNA). Synthetic siRNA targets homologous mRNA for degradation and the process is highly efficient. Here we demonstrate siRNA silencing of pathogenic viral gene expression. As a well characterized model we chose cervical carcinoma cells positive for human papillomavirus type 16. Over 90% of human cervical cancers are positive for papillomavirus and abnormal cell proliferation is driven by co-operative effects of viral E6 and E7 genes. We sought to silence HPV E6 and E7 gene expression using siRNAs to target the respective viral mRNAs. Our results indicate selective degradation of E6 and E7 mRNAs. Silencing was sustained for at least 4 days following a single dose of siRNA. E6 silencing induced accumulation of cellular p53 protein, transactivation of the cell cycle control p21 gene and reduced cell growth. In contrast, E7 silencing induced apoptotic cell death. HPV-negative cells appeared unaffected by the anti-viral siRNAs. Thus we demonstrate for the first time (i) that siRNA can induce selective silencing of exogenous viral genes in mammalian cells, and (ii) that the process of siRNA interference does not interfere with the recovery of cellular regulatory systems previously inhibited by viral gene expression.

Apoptosis↗
PubMed2002

PDZ7 of glutamate receptor interacting protein binds to its target via a novel hydrophobic surface area.

Glutamate receptor interacting protein 1 (GRIP1) is a scaffold protein composed of seven PDZ (Postsynaptic synaptic density-95/Discs large/Zona occludens-1) domains. The protein plays important roles in the synaptic targeting of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors. The interaction between GRIP1 PDZ7 and a Ras guanine nucleotide exchange factor, GRASP-1, regulates synaptic distribution of AMPA receptors. Here, we describe the three-dimensional structure of GRIP1 PDZ7 determined by NMR spectroscopy. GRIP1 PDZ7 contains a closed carboxyl group-binding pocket and a narrow alphaB/betaB-groove that is not likely to bind to classical PDZ ligands. Unexpectedly, GRIP1 PDZ7 contains a large solvent-exposed hydrophobic surface at a site distinct from the conventional ligand-binding alphaB/betaB-groove. NMR titration experiments show that GRIP1 PDZ7 binds to GRASP-1 via this hydrophobic surface. Our data uncover a novel PDZ domain-mediated protein interaction mode that may be responsible for multimerization of other PDZ domain-containing scaffold proteins.

Amino Acid Sequence↗
PubMed2002

[Effect of interleukin I receptor antigonist gene therapy on arthritis induced by type II collagen in mice].

OBJECTIVE: To investigate the effect of interleukin-1 receptor antagonist gene therapy on type II collagen induced arthritis in DBA/1 mice. METHODS: Plasmid pcDI-IL-1ra that expresses IL-1ra in eukaryotes was constructed by inserting human IL-1ra cDNA into the eukaryotic expression vector pcDI. Eukaryotes were transfected with the plasmid pcDI-IL-1ra in vivo and in vitro. The expression of 8 IL-1ra was examined by ELISA and immunohistochemistry. Type II collagen was used to induced arthritis in 32 DBA/1 mice. This plasmid was injected into the muscles of DBA/1 mice with arthritis induced by type II collagen by gene gun (20 micro g/mouse) and into the muscle of 8 mice by intramuscular injection (200 micro g/mouse). After the administration, the condition of arthritis was observed. The serum IL-ira was examined 6 and 12 days after administration. The expression of IL-ira in muscles was tested by computerized imaging analysis. RESULTS: PCR and DNA sequencing proved the accuracy of the inserted fragment. ELISA and immunohistochemistry detected high expression of IL-ira in vivo and in vitro. The absorbance ( A ) 490 value of IL-ira in the mouse muscle was 0.52 +/- 0.03 in gene gun group, and 0.48 +/- 0.02 in intramuscular injection group, all higher than that in the control group (0.41 +/- 0.02,P < 0.01 and P < 0.05). The serum IL-ira values in the gene gun group and in tramuscular injection group 6 days and 12 days after therapy were all significantly higher than that in the control group (all P < 0.01; and P < 0.01 and P < 0.05). Since the 6 th day after therapy, the redness and swelling of joints in both therapies groups were alleviated. Pathological examination made 12 days after therapy showed relief at different degrees of the infiltration of inflammatory cells, hyperplasia of synovia, bone infiltration, and cartilage destruction, especially in the gene gun group. CONCLUSION: Gene therapy of IL-ira via non-virus eukaryotic expression vactor, especially by gene gun, is effective in treating arthritis induced by type II collagen.

Animals↗
PubMed2002

[Idiopathic retroperitoneal fibrosis: a clinical analysis of 7 cases].

OBJECTIVE: To investigate the clinical characteristics of idiopathic retroperitoneal fibrosis. METHODS: The clinical manifestations, laboratory examination, and CT and MIR features of seven patients with idiopathic retroperitoneal fibrosis were analyzed. RESULTS: (1) The initial symptoms were nonspecific and variable and included abdominal pain, low back pain, and weigh loss. Later symptoms, depending on the organs affected, included abdominal mass, ascites, urinary symptoms, and and intestinal obstruction. (2) Diagnosis of IRF could be based on elevated erythrocyte sedimentation rate and gamma globulin and positive findings by CT and MIR. For masses in retroperitoneal space and adhesion of abdominal organs, CT was more sensitive than B mode ultrasonography. However, for hydronephrosis and lesions in ureter, B mode ultrasonography was the first choice. (3) Steroid and immunosuppressant were effective during the early stage of IRF. In the advanced stage, operation was necessary. CONCLUSION: Imaging examination is important for diagnosis of IRF. However, the final diagnosis depends on pathological examination. Treatment depends on the stage of disease. The prognosis is optimistic.

Adult↗
PubMed2002

Blind deblurring of spiral CT images-comparative studies on edge-to-noise ratios.

A recently developed blind deblurring algorithm based on the edge-to-noise ratio has been applied to improve the quality of spiral CT images. Since the discrepancy measure used to quantify the edge and noise effects is not symmetric, there are several ways to formulate the edge-to-noise ratio. This article is to investigate the performance of those ratios with phantom and patient data. In the phantom study, it is shown that all the ratios share similar properties, validating the blind deblurring algorithm. The image fidelity improvement varies from 29% to 33% for different ratios, according to the root mean square error (RMSE) criterion; the optimal iteration number determined for each ratio varies from 25 to 35. Those ratios that are associated with most satisfactory performance are singled out for the image fidelity improvement of about 33% in the numerical simulation. After automatic blind deblurring with the selected ratios, the spatial resolution of CT is substantially refined in all the cases tested.

Algorithms↗
PubMed2002

Herpes simplex virus type 1 evades the effects of antibody and complement in vivo.

Herpes simplex virus type 1 (HSV-1) encodes a complement-interacting glycoprotein, gC, and an immunoglobulin G (IgG) Fc binding glycoprotein, gE, that mediate immune evasion by affecting multiple aspects of innate and acquired immunity, including interfering with complement components C1q, C3, C5, and properdin and blocking antibody-dependent cellular cytotoxicity. Previous studies evaluated the individual contributions of gC and gE to immune evasion. Experiments in a murine model that examines the combined effects of gC and gE immune evasion on pathogenesis are now reported. Virulence of wild-type HSV-1 is compared with mutant viruses defective in gC-mediated C3 binding, gE-mediated IgG Fc binding, or both immune evasion activities. Eliminating both activities greatly increased susceptibility of HSV-1 to antibody and complement neutralization in vitro and markedly reduced virulence in vivo as measured by disease scores, virus titers, and mortality. Studies with C3 knockout mice indicated that other activities attributed to these glycoproteins, such as gC-mediated virus attachment to heparan sulfate or gE-mediated cell-to-cell spread, do not account for the reduced virulence of mutant viruses. The results support the importance of gC and gE immune evasion in vivo and suggest potential new targets for prevention and treatment of HSV disease.

Animals↗
PubMed2002

[Comparison of radiographs and magnetic resonance imaging in the detection of carpal lesions in patients with rheumatoid arthritis].

OBJECTIVE: To compare MR imaging with radiographs in detection of the erosions of the wrists in patients with rheumatoid arthritis (RA). METHODS: In 50 wrists of 25 patients with RA, radiographs of AP projection and MR imaging examination were performed within 1 week. The MRI sequences were SE T1-weighted image, FSE T2-weighted image, and GE T2* weighted image in coronal plane. Gd-DTPA enhanced SE T1-weighted image with same parameters of pre-contrast administration SE T1WI was performed in 25 wrists, which showed prominent lesions in each 25 patients. RESULTS: In 50 wrists of 25 patients with RA, bone erosions were found by MR images compared to radiographs in 46 versus 14 wrists, respectively. There were 170 sites of carpal erosions found by MR images, while radiographs found only 23 sites of carpal erosions. Among them triquetrum and lunate were the most frequently involved sites. Significant difference (P < 0.001) was statistically found between conventional radiography and MR imaging in detection of erosions of the wrists of RA. MR imaging also permitted demonstrating synovitis and joint effusion in the wrists. Gd-DTPA-enhanced images allowed distinguishing pannus changes from joint effusion. CONCLUSION: MRI is superior to conventional radiography with respect to detection of bone erosion in wrists. For those whose conventional radiographs show suspected RA, MRI examination should be advised for the early diagnosis.

Adult↗