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Biomedical subjects

Wei Zhao

Publications and source records attributed to Wei Zhao.

At least 73 records · Page 4Linked to original sources
PubMed2006

Screen optics effects on detective quantum efficiency in digital radiography: zero-frequency effects.

Indirect flat panel imagers have been developed for digital radiography, fluoroscopy and mammography, and are now in clinical use. Screens made from columnar structured cesium iodide (CsI) scintillators doped with thallium have been used extensively in these detectors. The purpose of this article is to investigate the effect of screen optics, e.g., light escape efficiency versus depth, on gain fluctuation noise, expressed as the Swank factor. Our goal is to obtain results useful in optimizing screens for digital radiography systems. Experimental measurements from structured CsI samples were used to derive their screen optics properties, and the same methods can also be applied to powder screens. CsI screens, all of the same thickness but with different optical designs and manufacturing techniques, were obtained from Hamamatsu Photonics Corporation. The pulse height spectra (PHS) of the screens were measured at different x-ray energies. A theoretical model was developed for the light escape efficiency and a method for deriving light escape efficiency versus depth from experimental PHS measurements was implemented and applied to the CsI screens. The results showed that the light escape efficiency varies essentially linearly as a function of depth in the CsI samples, and that the magnitude of variation is relatively small, leading to a high Swank factor.

Algorithms↗
PubMed2006

Amorphous selenium flat panel detectors for digital mammography: validation of a NPWE model observer with CDMAM observer performance experiments.

Model observers have been developed which incorporate a specific imaging task, system performance, and human observer characteristics and can potentially overcome some of the limitations in using detective quantum efficiency for optimization and comparison of detectors. In this paper, a modified nonprewhitening matched filter (NPWE) model observer was developed and validated to predict object detectability for an amorphous selenium (a-Se) direct flat-panel imager (FPI) where aliasing is severe. A preclinical a-Se digital mammography FPI with 85 microm pixel size was used in this investigation. Its physical imaging properties including modulation transfer function (MTF), noise power spectrum, and DQE were fully characterized. An observer performance study was conducted by imaging the CDMAM 3.4 contrast-detail phantom designed specifically for digital mammography and presenting these images to a panel of seven observers. X-ray attenuation and scatter due to the phantom were determined experimentally for use in development of the model observer. The observer study results were analyzed via threshold averaging and signal detection theory (SDT) based techniques to produce contrast-detail curves where threshold contrast is plotted as a function of disk diameter. Validity of the model was established using SDT analysis of the experimental data. The effect of aliasing on the detectability of small diameter disks was determined using the NPWE model observer. The signal spectrum was calculated using the presampling MTF of the detector with and without including the aliased terms. Our results indicate that the NPWE model based on Fourier domain parameters provides reasonable prediction of object detectability for the signal-known-exactly task in uniform image noise for a-Se direct FPI.

Calibration↗
PubMed2006

Deletion of the regulatory subunit of protein kinase A in Aspergillus fumigatus alters morphology, sensitivity to oxidative damage, and virulence.

Aspergillus fumigatus is an important opportunistic fungal pathogen. The cAMP-dependent protein kinase (PKA) signaling pathway plays an important role in regulating morphology, growth, and virulence in a number of fungal pathogens of plants and animals. We have constructed a mutant of A. fumigatus that lacks the regulatory subunit of PKA, pkaR, and analyzed the growth and development, sensitivity to oxidative damage, and virulence of the mutant, along with those of the wild type and a complemented mutant. Both growth and germination rates of the mutant are reduced, and there are morphological abnormalities in conidiophores, leading to reduced conidiation. Conidia from the DeltapkaR mutant are more sensitive to killing by hydrogen peroxide, menadione, paraquat, and diamide. However, the hyphae of the mutant are killed to a greater extent only by paraquat and diamide, whereas they are less susceptible to the effects of hydrogen peroxide. In an immunosuppressed mouse model, intranasally administered conidia of the mutant are significantly less virulent than those of the wild type or a complemented mutant. Unregulated PKA signaling is detrimental to the virulence of A. fumigatus, perhaps through the reduced susceptibility of the mutant to damage by oxidizing agents and reduced growth kinetics.

Animals↗
PubMed2006

Abnormal activation of the synuclein-gamma gene in hepatocellular carcinomas by epigenetic alteration.

Liver cancer is the fifth most common neoplastic disease and the fourth leading cause of cancer-related death. Identification of the key molecular targets involved in hepatocarcinogenesis has significant therapeutic implications. In this study, by conducting immunohistochemistry, we show that the neuronal protein, synuclein-gamma (SNCG), is abnormally expressed in a high percentage of liver cancer (46/70, 65.7%). The expression of SNCG in liver cancer exhibits a clear stage-specific pattern of low expression in stage I (1/19, 5.3%) and high expression in stages III to IV (44/50, 88%). Importantly, all patients with metastatic diseases expressed SNCG in their primary tumors (15/15, 100%). Consistent with the IHC results, RT-PCR assays demonstrate that SNCG mRNA is highly expressed in the tumor tissue of advanced hepatocellular carcinomas. Analyses of the methylation status of the CpG island of the SNCG gene by methylation-specific PCR confirmed that all tumor samples contained the demethylated gene. To determine whether demethylation of SNCG is an early event of genetic abnormality in the process of hepatocarcinogenesis, we examined the methylation status of SNCG in 70 non-malignant cirrhotic liver samples and showed that 64.3% cirrhotic liver samples contained the partially or completely demethylated gene. We further show that SNCG expression in liver cancer is not restricted to HBV- and HCV-infected tumors, implying the involvement of other hepatocarcinogenic risk factors in SNCG gene reactivation. Utilizing human hepatoma-derived cell line HepG2 as an in vitro model, we demonstrate that hepatic carcinogens aflatoxin B1 and N-nitrosodimethylamine (DMN) are strong inducers of SNCG expression. Collectively, these new findings suggest that SNCG protein expression in primary tumors is a strong indicator of distant metastasis and demethylation of SNCG CpG island is an early sign of genetic abnormality in liver cirrhosis preceding hepatocarcinogenesis. Our studies also suggest that inducing demethylation of SNCG by hepatocarcinogens may represent one underlying mechanism for the aberrant expression of SNCG in HCC.

Adult↗
PubMed2006

[A short-term efficacy and safety study of infliximab in active ankylosing spondylitis].

OBJECTIVE: To evaluate the efficacy and safety profile of a loading regimen of the anti-TNFalpha antibody infliximab in ankylosing spondylitis (AS). METHODS: This was an open-labeled trial. Subjects eligible for this study were adults with a diagnosis of definite AS. Active disease was a Bath AS disease activity index (BASDAI) > or = 4 and spinal pain VAS > or = 4. Concurrent stable treatment with nonsteroidal anti-inflammatory drugs was permitted during the study. Subjects were not permitted to be on methotrexate, systemic corticosteroids, cytotoxic drugs or disease-modifying anti-rheumatic drugs for various time periods before screening. Infliximab 5 mg/kg was infused at weeks 0, 2, 6. All patients were followed up to 10 weeks. The primary endpoint was proportion of ASAS 20 responders at week 10. The secondary endpoints were the proportion of subjects achieving an ASAS partial remission, the change from baseline in bath AS functional index and in the physical component summary score of the short form-36 in health survey questionnaire at week 10. Other secondary endpoints, related to reducing signs and symptoms of AS and improving range of motion and physical function, were evaluated. RESULTS: 63 patients (79% males, 90% HLA-B(27)(+), median age 32 yr, median disease duration 10 yr) completed the treatment. The proportion of ASAS 20 responders at 2, 6, 10 week was 75%, 84%, 84% respectively. The proportion of ASAS partial remission patients at 2, 6, 10 week was 10%, 21%, 30% respectively. Results for other secondary efficacy endpoints showed that infliximab could provide substantial benefits to patients with AS by reducing clinical signs and symptoms and improving range of motion, physical function, and quality of life. Sixty-five percent of subjects reported treatment-related adverse events. The most frequently occurred were upper respiratory tract infection and skin and appendages. Secondary was elevation of liver enzymes. Most treatment-related adverse events were mild to moderate in severity. Two patients had serious dermatitis and one stopped treatment owing to an infusion reaction. Short-term follow up indicated that effect of Remicade lasted for about 2 to 8 months without any new side effect. CONCLUSION: A loading regimen of infliximab demonstrated consistent evidence of efficacy and was well tolerated in the treatment of active AS.

Adolescent↗
PubMed2006

[Variability analysis of S2 gene of SARS-CoV].

OBJECTIVE: To determine the sequence of S2 gene of SARS-associated coronavirus (SARS-CoV) GD322 and analyze the phyletic evolution of S2 gene. METHOD: S2 gene fragment was amplified from SARS-CoV GD322 genome with RT-PCR and ligated to pGEM-T vector for sequence analysis after transformation of the plasmid into E. coli DH5a. The variability of S2 genes and S2 proteins from 12 strains isolated in the early, intermediate and advanced stages of the SARS outbreak were analyzed and the phylogenetic tree was constructed with Lasergene, Clustal X, DNAman and Treeview. T cell antigen epitopes of S2 protein were predicted on the basis of Internet database. RESULT: With the epidemic spread of SARS-CoV, the S2 genes of the virus tended to become stable. Homology of S2 genes of SARS-CoV isolated in advanced stage of the outbreak reached 99.9%. Prediction of T cell antigen epitope showed that mutation at the 57th amino acid effected T cell antigen epitope. CONCLUSION: S2 gene of GD322 SARS-CoV is relatively stable during the epidemic spread of the virus, and mutation at the 57th amino acids of S2 protein may affect the T cell antigen epitope.

Escherichia coli↗
PubMed2006

[Construction and identification of genomic cDNA subclones of dengue 2 virus NGC strain].

OBJECTIVE: To construct the cDNA subclones spanning the entire genome of dengue 2 virus NGC strain for further construction of full-length infectious viral cDNA clone. METHODS: Two pairs of primers were designed according to the restriction endonuclease sites in the viral genome of dengue 2 virus NGC strain. After viral RNA extraction from the brain of infected new-born mice, two parts of full-length viral cDNA were amplified by long RT-PCR and cloned into the vector pCR-XL-TOPO. The partial sequence of the recombinant plasmid was determined. RESULTS AND CONCLUSION: Sequence analysis and digestion with restriction enzymes demonstrated that the two cDNA subclones were specific for dengue 2 virus NGC strain, suggesting the successful construction of the two cDNA subclones of dengue 2 virus NGC strain.

Animals↗
PubMed2006

[The expression of TLR4 in rat acute lung injury induced by lipopolysaccharide and the influence of Eucalyptus globulus oil].

OBJECTIVE: To observe the distribution of toll-like receptor 4 (TLR4) in rats' respiratory tract. To study the influence of LPS and Eucalyptus globulus oil on the distribution of TMR4. METHOD: The Sprague-Dawley rats were intratracheally instilled with lipopolysaccharide (LPS,2 mg x kg(-1) per day) for two days to induce acute lung injury. The rats were sacrificed at 72 hours after LPS instillation. Lung morphology was studied. Leukocytes in Bronchoalveolar lavage fluid (BALF) were measured and TLR4 were detected by immunohistochemistry. RESULT: The result of immunohistochemistry showed that TLR4 distributed widely in common rats' respiratory tract. In the group of acute lung injury, the number of leucocyte in BALF was increased apparently, the inflammation in bronchus and bronchioles was more apparently than that of the control group in morphology. And the expression of TLR4 was reinforced in main bronchus and bronchioles. In the group of E. globules oil (300 mg x kg(-1)), the leucocyte number was decreased apparently in BALF, the inflammation was lightened and the expression of TLR4 decreased as compared with the group of models. CONCLUSION: The expression of TLR4 distributes widely in rats' respiratory tract. The stimulation of LPS can reinforce the expression of TLR4. The E. globules oil can reduce the increase of TLR4 induced by LPS in bronchioles.

Animals↗
PubMed2006

The effects of age and sex on the expression of aromatase in the rat temporomandibular joint.

AIMS: To investigate the expression of aromatase in temporomandibular joints(TMJs) of male and female rats of different ages. METHODS: The expression of aromatase in terms of protein and mRNA was examined by immunohistochemistry, Western blot, and in situ hybridization in the TMJs of Sprague-Dawley rats. The expression level of aromatase protein was also quantified by the density of aromatase-positive chondrocytes in TMJ condylar cartilage. A tritiated water assay was used to analyze the activity of aromatase in cartilage chondrocytes. RESULTS: Strong aromatase protein and mRNA hybridization signals were detected in hypertrophic and mature chondrocytes in all the cases examined. The density of aromatase-positive chondrocytes was relatively stable at higher levels before 8 weeks of age. The density decreased gradually in females after 8 weeks of age but not in males. CONCLUSION: These results demonstrate that aromatase is expressed intensely in condylar cartilage and suggest that it may play an important role in pathophysiological mechanisms in condylar cartilage.

Age Factors↗
PubMed2006

[Impact of acupuncture on NP-1 expression in spared dorsal root ganglion].

OBJECTIVE: To investigate the impact of acupuncture on NP-1 expression in spared dorsal root ganglion (DRG). METHODS: Twenty-five male adult cats were divided into five groups. The five cats in the pseudo-operation group were kept intact. Ten cats were subjected to unilateral root rhizotomy(unilateral L1-L5 DRGs were transected, but L6 DRG was spared), with five sacrificed seven days later and another five sacrificed 14 days later. Ten cats with unilateral root rhizotomy received acupuncture (electron-needle stimulation in Zusanli, Xuanzhong, Futu and Sanyinjiao which are located in the distribution area of L6 spinal nerve) for 30 minutes per day. Five cats in the acupuncture group were sacrificed seven days and 14 days later respectively. The L6 DRG from the experimental side of each animal was taken and made into frozen sections 20 microm in thickness. The sections were stained under the same conditions using NP-1 specific antibody (1:600, Santa) by immunohistochemistry ABC method. The amounts of NP-1 immunoreaction neurons of DRG were measured. RESULTS: The NP-1 immunoreactants were mainly located in the small and medium-sized neurons and a few large sized neurons in the cats of the pseudo-operation group. Less NP-1 positive medium-small sized neurons were found seven days after partial dorsal root rhizotomy (P<0.05). But they returned back to the original level 14 days after operation. The NP-1 positive large neurons had no significant changes after operations. With seven days of acupuncture, the amounts of NP-1 positive small and medium-sized neurons increased significantly (P<0.05) but were still less than the original level (P<0.05). There were no differences in neurons 14 days after operations between the acupuncture and non-acupuncture group (P>0.05) and between the groups with seven days acupuncture and 14 days of acupuncture (P>0.05). CONCLUSION: Acupuncture increases the expression of NP-1 in small and medium-sized neurons of spared DRG.

Acupuncture↗
PubMed2006

[Variant fusion transcript in ALL children with E2A-PBX1 fusion gene positive].

The study was aimed to investigate the expression of E2A-PBX1 fusion gene in children with acute lymphoblastic leukemia (ALL). The primers located at different sites of E2A and PBX1 gene were used to screen for the fusion gene in 410 children with ALL, including 362 cases of B cell ALL and 48 cases of T cell ALL. The results showed that 17 children carried the fusion gene. The positive rate was 4.1%. Furthermore, all the positive cases expressed a variant type of fusion transcript. It resulted from different splicing of the 13th exon (159 bp) of E2A gene. Analyses with BLASTn indicated that the variant type of transcript retained the open reading frame. However, the loss of 53 amino acid residues which were located at the 2nd activation domain resulted in the partial deletion of the putative loop-helix (LH) structure as well as the complete deletion of the heptad leucine repeat. It is concluded that all the children with ALL positive for the E2A-PBX1 fusion gene express typical and variant fusion transcripts. The latter resulted from different splicing of the 13th exon (159 bp) of E2A gene. The loss of 53aa would lead to the partial deletion of the putative loop-helix (LH) structure as well as the complete deletion of the heptad leucine repeat.

Amino Acid Sequence↗
PubMed2006

[Clinicopathologic features of gallbladder adenocarcinoma with marked stromal fibrosis--a report of 19 cases].

BACKGROUND & OBJECTIVE: Macropathologic types of gallbladder cancer are mostly polyp type, intumescent type, and cauliflower form lump. Its histological types include well or poorly differentiated adenocarcinoma, mucinous adenocarcinoma, and undifferentiated cancer. This research was to explore the clinicopathologic features of gallbladder adenocarcinoma with marked stromal fibrosis. METHODS: Pathology of 19 cases of gallbladder adenocarcinoma with marked stromal fibrosis was observed using a light microscopy and SP immunohistochemistry. Clinicopathologic features of 19 patients were analyzed. RESULTS: Most of the patients had long-term history of cholecystitis gallbladder calculus. B ultrasound showed that the gallbladder wall was irregularly thickened or presented nodosity. Observed with naked eyes, gallbladder adenocarcinoma with marked stromal fibrosis did not form cancer nodule and extrude into the gallbladder lumen, the gallbladder wall showed regional thickening, a few cases showed diffuse irregular thickening. Observed under a light microscope, the adenocarcinoma cells were mostly arranged as single layers, seldom arranged as multiple layers, and formed adenoid structures with different sizes, various shapes, and irregular arrangement; the nuclei were heterogenic with haryomitosis presented in a few cases; inflammatory cells were infiltrated in hyperplastic fibrous connective tissue of some cases. According to immune phenotyping, CK (AE1/AE3), CK (AE1), CK7 (OV-TL12/30), CK8 (C51), CK18 (Dc-10), CK19 (RCK108), and EMA (Mc-5) showed strong expression, CEA (COL-1), CK20 (Ks20. 4), and MUC-5AC (CLH2) showed moderate expression, and MUC-2 (B306. 1) showed weak expression; CK17 (E3) showed focal expression. CONCLUSIONS: The clinical manifestation, macropathologic type, histological characteristics of gallbladder adenocarcinoma with stromal fibrosis are different from other types of adenocarcinoma. Its genesis may be related to chronic cholecystitis: long-term inflammation causes regional hyperplasia and heterogeneity of the gland body, lead to focal or regional thickening of the gallbladder wall, and result in gallbladder adenocarcinoma with stromal fibrosis finally.

Adenocarcinoma↗
PubMed2006

[Effect of compound glycyrrhizin on peripheral T-lymphocyte subset in AIDS patients].

OBJECTIVE: To probe the effect and mechanism of Compound Glycyrrhizin in treating AIDS. METHODS: Forty AIDS patients were randomly divided into a treatment group and a control group, both treated with HAART. In addition, the former was given Compound Glycyrrhizin for 6 months, and the CD4+ T count and the expressions of CD8+ and HLA-DR on the surface of peripheral blood lymphocytes (PBL) were studied before and after the treatment. RESULTS: After 6 months of treatment, the expressions of CD8+ and CD38+ of PBL in the treatment group [(6.6 +/- 2.1)%] were found lower than in the control [(11.4 +/- 3.8)%] (t = 5.043, P < 0.01) and CD4+ T count [(243.6 +/- 91.2) x 10(6)/L vs (170.8 +/- 55.7) x 10(6)/L] rose more significantly (t = 3.045, P < 0.01). CONCLUSION: Compound Glycyrrhizin can lower the expression of active T-lymphocyte subset, inhibit HIV and help immune reconstitution.

ADP-ribosyl Cyclase 1↗
PubMed2006

[Immunophenotypic characteristics of children with acute lymphoblastic leukemia carrying TEL-AML1 fusion gene].

To investigate the immunological and other clinical characteristics in TEL/AML1+ childhood B-acute lymphoblastic leukemia (B-ALL), immunophenotyping was performed with three-color flow cytometry, and the expression of TEL-AML1 fusion gene was detected with nested RT-PCR. Diagnosis was made according to FAB and MIC criteria. The results showed that (1) among 119 children with B-ALL, 22 (18.5%) were TEL-AML1 positive and classified as L2 morphological subtype. In TEL-AML1+ group, positive rate and score of PAS, which were 65% and 121 respectively, were all higher than that of TEL-AML1- group (P < 0.05); (2) compared with TEL-AML1- group, no significant difference was found in age, gender, white cell count and blasts count in peripheral blood of TEL-AML1+; (3) in TEL-AML1+ group, 21 out of 22 (95.5%) were common ALL, as compared with TEL-AML1- group, the positive rate of CD13 was higher (59.1%, 13/22) and the positive rate of CD20 was lower (22.7%, 5/22) than that in TEL-AML1- group, respectively (P < 0.05), and the mean fluorescence index of CD10 and HLA-DR significantly increased to 92.80 and 53.61, respectively (P < 0.05). It is concluded that TEL-AML1 rearrangement is a frequent molecular abnormality in childhood ALL. Leukemic blasts with this anomaly have special immunophenotypic characteristics. These characteristics may be useful in detection of minimal residual leukemia.

Antigens, CD20↗
PubMed2006

[Study on the biomechanical behavior of human intestine].

To investigate the biomechanical behavior of human intestines. The tensile test human intestine was performed with the electronic tension machine in this paper. The results indicate that the exponential relationship for the stress-strain of the human intestine was obtained, and the exponential coefficient a of each segment of the intestine is almost the same although the constant C is different. It also shows that the relative rate of stretch length of each segment intestines is different in longitudinal and circumferential directions. And the incremental elastic modulus of colon is less than those of small intestine. It is considered that the colon can be more easily deformed. The experimental results provide the theoretic basis for research on intestinal endoscopic microrobot.

Biomechanical Phenomena↗
PubMed2006

[Pegylated interferon alpha 2a in treating chronic hepatitis B patients].

OBJECTIVE: To evaluate the efficacy and safety of pegylated interferon alpha 2a (PEG-IFN alpha-2a) in treating patients with chronic hepatitis B. METHOD: Seventy-two patients with chronic hepatitis B were assigned to a PEG-IFN alpha-2a (experimental) group (n=42) and an interferon alpha (control) group (n=30) randomly. Each patient in the experimental group received 180 microg PEG-IFN alpha-2a every week. Each patient in the control group received 500 MU interferon alpha every day. All the patients were treated for 48 weeks, and then were followed for another 48 weeks with no treatment. RESULTS: At the end of the 12th week, the rate of HBeAg negative cases was 30% in the PEG-IFN alpha-2a group, which was much higher than in the control group (x2 = 4.162, P < 0.05). The values of HBeAg and the log value of HBV DNA in the PEG-IFN alpha-2a group were much lower than the values before the treatment (t = 2.689, t = 4.080, P <0.01), but there was no difference between before and after treatment in the control group ( t = 1.229, t = 1.009, P > 0.05). At the end of the 24th week, the rate of HBeAg negative cases in the PEG-IFN alpha-2a group was much higher than that in the control group (x2=6.190, P < 0.05). The value of HBeAg and the log value of HBV DNA in the PEG-IFN alpha-2a group were much lower than in the control group (t=2.215, t=2.122, P < 0.05). At the end of the 48th week, besides the reduction mentioned above, the rate of cases with HBeAg/antiHBe seroconversion and normalization of ALT and complete responsiveness in the PEG-IFN alpha-2a group were all much higher than those in the control group (x2=5.771, x2=5.617, x2=5.308, P < 0.05). At the end of 48 weeks with no treatment, all the parameters mentioned above in the PEG-IFN alpha-2a group were much better than those in the control group and they remained so, but they were different in the control group (x2=11.943, t=3.439, t=6.111, x2=9.930, x2=9.522, x2=7.920, P < 0.01). Nine patients in the PEG-IFN alpha-2a group had liver biopsies before their treatment and also at the end of their treatment. The expressions of HBsAg and HBcAg were decreased at the end of the treatment. The rate of expression of HBsAg in the liver tissues before the treatment was 88.9% but only 22.2% at the end of the treatment (x2=8.001, P < 0.01). The rate of expression of HBcAg in the livers before treatment was 66.7% but only 33.3% at the end of the treatment. Before and at the end of the PEG-IFN alpha-2a treatment, there were no significant changes in the degrees of inflammation and fibrosis and the quantity of collagen in the liver tissues. Three patients in the PEG-IFN alpha-2a group (10%) were HbsAg negative. Two of them were found so at the end of 32 weeks with treatment and one patient was found at the end of 24 weeks with no treatment, but there were no HBsAg negative patients in the control group. The adverse reactions that occurred in the PEG-IFN alpha-2a and in the control groups were similar. CONCLUSION: PEG-IFN alpha-2a was effective in inhibiting HBV replication. The effect of PEG-IFN alpha-2a was lasting. PEG-IFN alpha-2a was well tolerated during our treatment.

Adolescent↗