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Dong Chen

Publications and source records attributed to Dong Chen.

51 records · Page 3Linked to original sources
PubMed2004

[In vitro cleavage activity of the ribozymes constructed specifically for the second exons of pro alpha I and III collagen genes].

OBJECTIVE: To study the in vitro cleavage activity and the reaction conditions of the hammerhead ribozymes for the second exons of pro alpha 1I and III collagen genes, and observe the effect of the two ribozymes on collagen synthesis by the fibroblasts in scar tissue. METHODS: The fragments of the second exons of pro alpha 1I and III collagen genes were cloned into the plasmids pT-I and pT-III and labeled with (32)P during transcription to obtain the target RNA. The transcription products of the plasmids pT-gI and pT-gIII containing specific ribozymes were incubated with the label target RNAs, respectively, under various conditions, and the results observed by electrophoresis autoradiography. The constructed ribozymes were transduced into cultured fibroblasts via liposomes for investigation of their effects on mRNA synthesis of type I and III collagen protein by image analysis. RESULTS: The two ribozymes (rgI and rg III) could efficiently cleave their target RNAs at both 37 degrees Celsius and 42 degrees Celsius, in the presence of Mg(2+) within a relatively wide concentration range form 10 to 20 mmol/L. When the temperature was lowered from 65 degrees Celsius to 37 degrees Celsius and maintained at 37 degrees Celsius, the cleavage activity of the ribozymes reached the maximum. The expression of mRNA of I and III collagen decreased accompanied by reduced collagen synthesis. CONCLUSION: Hammerhead ribozymes for the fragments of the second exons of pro alpha 1I and III collagen genes can cleave its target RNAs in vitro and effectively inhibit the collagen synthesis by the scar-derived fibroblasts.

Cicatrix↗
PubMed2004

[The application of transgenic plant in evaluating the genotoxicity of environmental contaminants].

Environmental contaminants are powerful mutagenic factors for organisms. Several testing materials and methods have been used to assess the genotoxicity of environmental factors. Transgenic plants testing system can not only evaluate the level of genotoxicity, but also provide information on the genetic effects at molecular level. We introduce the use of transgenic plants in biomonitoring environmental factors.

Animals↗
PubMed2003

Screening the genome for rheumatoid arthritis susceptibility genes: a replication study and combined analysis of 512 multicase families.

OBJECTIVE: A number of non-HLA loci that have shown evidence (P < 0.05) for linkage with rheumatoid arthritis (RA) have been previously identified. The present study attempts to confirm these findings. METHODS: We performed a second genome-wide screen of 256 new multicase RA families recruited from across the United States by the North American Rheumatoid Arthritis Consortium. Affected sibling pair analysis on the new data set was performed using SIBPAL. We subsequently combined our first and second data sets in an attempt to enhance the evidence for linkages in a larger sample size. We also evaluated the impact of covariates on the support for linkage, using LODPAL. RESULTS: Evidence of linkage at 1p13 (D1S1631), 6p21.3 (the HLA complex), and 18q21 (D18S858) (P < 0.05) was replicated in this independent data set. In addition, there was new evidence for linkage at 9p22 (D9S1121 [P = 0.001]) and 10q21 (D10S1221 [P = 0.0002] and D10S1225 [P = 0.0038]) in the current data set. The combined analysis of both data sets (512 families) showed evidence for linkage at the level of P < 0.005 at 1p13 (D1S1631), 1q43 (D1S235), 6q21 (D6S2410), 10q21 (D10S1221), 12q12 (D12S398), 17p13 (D17S1298), and 18q21 (D18S858). Linkage at HLA was also confirmed (P < 5 x 10(-12)). Inclusion of DRB1*04 as a covariate significantly increased the probability of linkage on chromosome 6. In addition, some linkages on chromosome 1 showed improved significance when modeling DRB1*04 or rheumatoid factor positivity as covariates. CONCLUSION: These results provide a rational basis for pursuing high-density linkage and association studies of RA in several regions outside of the HLA region, particularly on chromosomes 1p, 1q, and 18q.

Arthritis, Rheumatoid↗
PubMed2003

Mouse and human embryonic stem cell models of hematopoiesis: past, present, and future.

Human embryonic stem (ES) cells provide a unique model and an important resource to analyze early hematopoietic development. Other systems to study mammalian hematopoiesis include mouse ES cells, dissection of timed mouse embryos, or use of human postnatal hematopoietic tissue typically isolated from bone marrow or umbilical cord blood. All these models have particular strengths and weaknesses. The extensive studies on murine hematopoiesis provide a basis for work on the human developmental system. Since there are likely some important species differences, use of human ES cells now provides an optimal means to evaluate basic cellular and molecular mechanisms that regulate the beginning stages of human blood development, prior to derivation of hematopoietic stem cells (HSCs). Eventually, research on human ES cells may provide an alternative source of HSCs and other blood products for hematopoietic cell transplantation or other cellular therapies.

Animals↗
PubMed2003

[Adjustment of lipiodol dose according to tumor blood supply during the transcatheter arterial chemoembolization for large hepatic carcinoma by mulitdetector helical CT].

OBJECTIVE: To work out an individualized lipiodol dose in transcatheter arterial chemoembolization (TACE) for large hepatic carcinoma (HCC) according to its blood supply evaluated by CT. METHODS: One hundred patients with HCC (diameter more than 8 cm) were studied by triphasic 5-mm-thick-section scan of multidetector helical CT. Patterns of HCC blood supply were divided into sufficient blood supply, poor blood supply, mixed blood supply and arterial-venous shunt. The dose of ultra-fluid lipiodol was determined by diameter and blood supply type of HCC. The patients were divided two groups (50 cases each), with the lipiodol perfused according to the diameter and the blood supply of tumor in one group and the iodized oil perfused according to the actual tumor diameter in the other. The filling of lipiodol in HCC was observed and conformation rate was compared in the two groups. When the diameter of HCC was less than 10 cm, 10 - 20 ml and 5 - 10 ml lipiodol was injected in to the sufficient blood supply and the poor supply groups. When the diameter of HCC was more than 10 cm, 20 - 30 ml iodized oil was injected in the sufficient blood supply group. The lipiodol dose in the mixed blood supply group was determined by the diameter of sufficient blood supply area. RESULTS: The conformation and effective rate were 82%, 84% in the first group and 36%, 46% in the second group (P < 0.01). CONCLUSION: A relative individualized lipiodol dose may be determined according to the blood supply pattern and the tumor diameter by CT imaging.

Adult↗
PubMed2003

[Detection of SARS-CoV RNA in stool samples of SARS patients by nest RT-PCR and its clinical value].

OBJECTIVE: To investigate of severe acute respiratory syndrome (SARS) convalescent stool shedding by RT-PCR. METHODS: One hundred and three stool samples from 46 SARS patients were collected on May 16th, 20th, and 23rd, 2003. For each sample, RNA was extracted using commercial kit and 7 Nest RT-PCR using a 14-pair different SARS-associated coronavirus (SARS-CoV) special primers were carried out simultaneously. RESULTS: Among these 46 SARS patients, 17 cases (37.0%) were stool SARS-CoV RT-PCR negative, and 29 cases (63.0%) were SARS-CoV RT-PCR positive. The duration of positive cases lasted (31.76 +/- 10.78) d (12-64 d). The longest stool shedding case in this study lasted 64 days. Two serial stool samples and for each sample 2 RT-PCR tests using different primers were positive in this case. CONCLUSIONS: Our study observed longest stool shedding of SARS patients to be 64 days after initial onset of SARS. The average stool shedding was 32 days. Hence it is important to think highly of SARS convalescent patient stool sterilization.

Adolescent↗
PubMed2003

[Effects of long-term oral administration of lanthanum nitrate on the liver of rats].

OBJECTIVE: To probe the effects of long-term oral administration of lanthanum nitrate [La(NO(3))(3)] on morphological change in the liver, aftereffect of deposited La in the liver and their mechanism in rats. METHODS: Young Wistar rats were divided into two groups, one fed with 0.1, 0.2, 2.0, 10.0 and 20.0 mg/kg of La(NO(3))(3) for six months and the other for the control. Changes in ratio of liver to body weight were observed after exposure to La(NO(3))(3) at varied doses for six months and one month after six-month exposure, as well as morphology of the liver in the rats with routine histochemistry and transmission electron microscopy (TEM) technique. Content of La in the liver was measured with inductively coupled plasma-mass spectrometry (ICP-MS). RESULTS: Ratio of liver to body weight was significantly higher in the male rats exposed to 20.0 mg/kg of lanthanum for six months than that in the control group. Ratio of liver to body weight restored to normal in the rats exposed to 20.0 mg/kg of La one month after six-month exposure. Infiltration of inflammatory cells in the portal region of the liver, small amount of fat drops in hepatocytic cytoplasm, increased density of mitochondria stroma, lysosome containing highly-electronic-density bodies and dense granules, normal nucleus and slightly deformed nucleus of hepatocytes could be found in the rats exposed to 20.0 mg/kg. Areas of the liver deposited with glycogen after six-month exposure to 20.0 mg/kg of La accounted for (26.1 +/- 1.5)% and (4.1 +/- 1.4)%, respectively for male and female rats, significantly lower than those in the control group [(31.3 +/- 1.4)% and (39.4 +/- 0.9)%, respectively], with a statistical significance and very statistical significance, respectively. There was a little infiltration of inflammatory cells in the portal region of the liver one month after six-month exposure to 20.0 mg/kg of La, and amount of the dense bodies was lower in the rats exposed to La for six months. Liver contents of La in the rats of all experimental groups were lower one month after six-month exposure than those in the rats exposed for six months. CONCLUSIONS: Exposure to a dose of 20.0 mg/kg La(NO(3))(3) for a long term could damage the liver structure to certain extent, but lanthanum deposited in the liver could be eliminated from the body gradually.

Administration, Oral↗
PubMed2002

[Percutaneous radiofrequency ablation combined with transcatheter arterial chemoembolization for hepatocellular carcinoma].

OBJECTIVE: To assess the significance of the method of percutaneous radiofrequency ablation (PRFA) combined with transcatheter arterial chemoembolization for hepatocellular carcinoma. METHODS: Thirty patients with hepatocellular carcinoma were divided into PRFA group and TACE + PRFA group between January 2000 and July 2001. All patients were followed up to examine the value of AFP, MRI or CT. Kaplan-Meier estimation was used for the analysis of disease-free survival and the cumulative survival rate. RESULTS: The complete necrosis rates were 86.7% (13/15) and 26.7% (4/15) in the TACE + PRFA group and group PRFA group respectively. The rates of AFP positive down to negative were 66.7% (6/9) for the former and 20% (2/10) for of the latter, and the six-month disease-free survival rates were 100% (13/13) and 75% (3/4) in the two groups. The 1-, 1.5- and 2-year survival rates of the group TACE + PRFA were 100%, 100% and 66.7% respectively. The survival rates of 1 and 1.5 years of the group PRFA only were 80% and 40%. CONCLUSIONS: For those hepatocellular carcinomas over 3 cm in size, located in the porta hepatis, or with indistinct boundary or the presence of foci, TACE can be performed first and then followed by PRFA in suitable time. This method can enlarge the necrosis range and increase the rate of complete necrosis of tumors, thereby decrease the recurrence and improve the disease-free survival and total survival of patients.

Adult↗
PubMed2002

[Transarterial embolization for hemorrhage due to spontaneous rupture in hepatocellular carcinoma].

OBJECTIVE: To evaluate the efficacy of transarterial embolization (TAE) for intraperitoneal hemorrhage due to spontaneous rupture in hepatocellular carcinoma (HCC). METHODS: Fourty-two patients with ruptured HCC were divided into 4 groups according to the type of their previous treatment: Group A-TAE followed by elective hepatectomy 15, Group B- TAE alone 11, Group C-emergency operation 6 and group D-medical conservative management 10. RESULTS: Celiac arteriography done before the present treatment showed extravasation of contrast material in 7 (26.9%) of the 26 patients in group A and B, and hypervascular tumor was observed in the rest. The hemostasis success rate of group A, B and C were 100%, which were much higher than that of group D (40%) (P < 0.05). The in-hospital mortality rates of group A, B and C were 0, 3.8% and 16.7% (P > 0.05), which were much lower than that of group D (80%) (P < 0.01). The 1-year survival rate of group A (76.3%) was higher than those in groups B (47.5%) and C (43.7%) (P < 0.05). There was no 1-year survivor in group D. CONCLUSION: Transarterial embolization is safe and effective for hemorrhage due to spontaneous rupture in hepatocellular carcinoma. For resectable lesions, TAE is a preferential treatment to be given first, then followed by elective hepatectomy.

Adult↗
PubMed2002

[The upper airway CT scan in patients with obstructive sleep apnea syndrome].

OBJECTIVE: To compare the CT scan results in OSAS patients and normal adults so as to explore its value in measuring upper airway structure. METHOD: 53 patients with OSAS and 53 normal adults were included in the study. The upper airway from roof of nasopharynx to glottis was evaluated with the use of a Phlips Tomoscan AV Expander E1 spiral scanner. The area and the dimensions of palate, uvula, lingua and epiglottis region was studied, and the thickness of retropharyngeal and lateral pharyngeal tissue were evaluated, too. RESULT: There were obviously differences between OSAS patients and normal adults in the areas of palate, uvula, lingua, and there are differences of dimension and thickness in different sites. CONCLUSION: The study suggests that there is a obviously difference between the patients with OSAS and normal adult in upper airway by CT scan. The anatomic structure of upper airway is one of causes of OSAS.

Adult↗
PubMed2002

[Localization of upper airway stricture in patients with obstructive sleep apnea syndrome by CT scan].

OBJECTIVE: To evaluate the diagnostic significance of CT scan in the localization of the stricture in the upper airway in patients with obstructive sleep apnea syndrome (OSAS). METHODS: Fifty-four patients with OSAS were included in this study. CT scan evaluated the upper airway from the roof of nasopharynx to the glottis using a Phlips Tomoscan AV Expander E1 spiral scanner. The areas and the dimensions of palate, uvula, lingua and epiglottis region, as well as the thickness of retropharyngeal and lateral pharyngeal tissue was evaluated. The reference values had been set-up in 225 normal adult upper airways CT scan, some patients' results were compared with the CT scan results during apnea. RESULTS: There were no any upper airway stricture in 12 patients with OSAS, and there were one or more upper airway stricture sites in other 42 patients. Twenty-four patients had only one stricture site. Fourteen patients had 2 adjacent stricture sites. One patient had three stricture sites. Three patients had 4 upper airway strictures. There was a good concordance between the results of CT scans during awakening and sleeping in 14 patients. CONCLUSION: Most patients with OSAS had anatomic upper airway strictures, the CT scan can localize the stricture site very well.

Adult↗
PubMed2002

Multi-slice three-dimensional spiral CT cholangiography: a new technique for diagnosis of biliary diseases.

OBJECTIVE: To validate multi-slice three-dimensional spiral CT cholangiography (3-D CTC) in clinical diagnosis of biliary diseases. METHODS: This study included 146 patients with biliary diseases, involving 73 cases of biliary tumor, 87 cases of radioparent calculus, 12 cases of post cholangio-jejunostomy and one case of congenital choledochocyst. The data of thin-slice volumetric CT scan were sent to the workstation (GE Advantage Windows 3.1). Rational 3-D CTC including maximum intensity projection, minimum intensity projection, surface shaded display, CT virtual endoscopy and ray sumption was performed. The diagnostic accuracy of 3-D CTC was compared with that of conventional CT, ultrasonography and endoscopic retrograde cholangiopancreaticography (ERCP). RESULTS: Different biliary diseases showed distinct imaging manifestations on 3-D CTC. As a new technique for assessing the status of post cholangio-jejunostomy, 3-D CTC was superior to conventional CT, ultrasonography and ERCP in diagnosis of negative biliary calculus, extrahepatic cholangiocarcinoma, cancer embolus of the biliary duct, carcinoma of the pancreas head and periampullar carcinoma. It was also superior to conventional CT, ultrasonography or equal to ERCP in diagnosis of hilar cholangiocarcinoma, but inferior to conventional CT and ultrasonography in diagnosis of gallbladder cancer. CONCLUSION: 3-D CTC as a non-invasive and sensitive technique for the diagnosis of biliary diseases with high diagnostic accuracy will greatly increase the detection rate of biliary diseases.

Adult↗
PubMed2002

Plane and weighted tri-phase helical CT findings in the diagnosis of liver focal nodular hyperplasia.

OBJECTIVE: To analyze the pre- and post-contrast CT findings of liver focal nodular hyperplasia (FNH) so as to improve their diagnostic accuracy. METHODS: Pre- and post-contrast tri-phase (arterial, portal venous and delayed) scans were performed in 21 patients with FNH proved surgically and pathologically. Transcatheter arterial angiography was performed in 2 patients. RESULTS: Pre-contrast scans showed hypodensity in 16 patients, isodensity in 5, and punctate, streak and radial scars in 12. Except central scar, all lesions were markedly and homogeneously enhanced in the arterial phase. Nine of the 21 patients showed dilated and tortuous arteries in the central and peripheral areas of the focus. In the portal venous phase, focal density was decreased, though still higher or slightly higher in FNH than in parenchyma. In the delayed phase, the lesions showed isodensity or slight hypodensity. Enhanced capsules were seen in 3 patients. Dilated arteries and drainage veins were seen on angiographic images. CONCLUSION: The characteristic manifestations of FNH on multiphasic helical CT scan are of great significance in diagnosing FNH and choosing viable therapy.

Adolescent↗
PubMed1996

SOS phosphorylation and disassociation of the Grb2-SOS complex by the ERK and JNK signaling pathways.

Insulin activation of Ras is mediated by the plasma membrane targeting of the guanylnucleotide exchange factor SOS associated with the small adapter protein Grb2. SOS also lies in an insulin-stimulated feedback pathway in which the serine/threonine phosphorylation of SOS results in disassociation of the Grb2-SOS complex thereby limiting the extent of Ras activation. To examine the relative role of the mitogen-activated protein kinases in the feedback phosphorylation of SOS we determined the signaling specificity of insulin, osmotic shock, and anisomycin to activate the ERK (extracellular-signal regulated kinase) and JNK (c-Jun kinase) pathways. In Chinese hamster ovary cells expressing the human insulin receptor and murine 3T3L1 adipocytes, insulin specifically activated ERK with no significant effect on JNK, whereas anisomycin specifically activated JNK but was unable to activate ERK. In contrast, osmotic shock was equally effective in the activation of both kinase pathways. Insulin and osmotic shock, but not anisomycin, resulted in SOS phosphorylation and disassociation of the Grb2-SOS complex, demonstrating that the JNK pathway was not involved in the insulin-stimulated feedback uncoupling of the Grb2- SOS complex. Both the insulin and osmotic shock-induced activation of ERK was prevented by treatment of cells with the specific MEK inhibitor (PD98059). However, expression of dominant-interfering Ras (N17Ras) inhibited the insulin- but not osmotic shock-stimulated phosphorylation of ERK and SOS. These data demonstrate that activation of the ERK pathway, but not JNK, is responsible for the feedback phosphorylation and disassociation of the Grb2-SOS complex.

Adaptor Proteins, Signal Transducing↗