Search PubMed⌕ Search

Biomedical subjects

J Chen

Publications and source records attributed to J Chen.

At least 631 records · Page 35Linked to original sources
PubMed2001

Analysis of binding domain and function of chimeric mu/kappa opioid receptors to ohmefentanyl stereoisomers.

AIM: To investigate specific domains in mu opioid receptors that accounted for selective binding of three stereoisomers of ohmefentanyl (Ohm9204, Ohm9202, and Ohm9203) and study the function of chimera II. METHODS: Rat mu and kappa opioid receptors (RMOR, RKOR) and four mu/kappa chimeric receptors (chimeras) I, II, III, and IV were transiently expressed in COS-1 cells. The binding ability and binding domain of receptor to ligands were determined by radioactive ligand and receptor binding experiments. Through measuring cellular cAMP levels, we studied the function of chimera II in mediating signal transduction. RESULTS: Binding affinities of four chimeric receptors were similar to wild type opioid receptors (RMOR and RKOR). The binding affinities of Ohm9204 and Ohm9202 to chimera II were similar to that of RMOR. The binding affinities of Ohm9203 to all six receptors were low. U50488 possessed high binding affinity to chimera I, however dynorphie A(1-9) had some binding affinity to chimera II that was similar to RKOR, which indicated the domains of RKOR accounting for selectively binding to peptide ligand dynorphie A(1-9) and nonpeptide ligand U50488 were different. The efficacy of Ohm9204 and Ohm9203 on inhibiting forskolin-stimulated cAMP accumulation in cells transfected with chimera II was similar to that in cells transfected with RMOR. CONCLUSION: Replacing 194-268 residues of RMOR with 185-262 residues of RKOR does not influence the ability of mu opioid receptor to bind Ohm9204 and Ohm9202 and the receptor mediated inhibition of cellular cAMP level.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed2001

Effect of genistein and quercetin on proliferation, collagen synthesis, and type I procollagen mRNA levels of rat hepatic stellate cells.

AIM: To study the effects of genistein (GE) and quercetin (QU) on proliferation, collagen synthesis, and procollagen messenger RNA (mRNA) expression of rat hepatic stellate cell line HSC-T6 cells. METHODS: Cell proliferation was measured by crystal violet staining assay. Collagen synthesis was determined by [3H]proline incorporation assay. Type I mRNA level was determined by reverse transcription polymerase chain reaction (RT-PCR). RESULTS: GE (25 - 70 micromol/L) and QU (6.25 - 50 micromol/L) concentration-dependently reduced serum-driven HSC-T6 cell proliferation and collagen synthesis associated with a suppression of type I procollagen mRNA level. CONCLUSION: GE and QU inhibited hepatic stellate cell proliferation and collagen synthesis that might have a protective role against liver fibrosis.

Cell Division↗
PubMed2001

Evaluation of an (111)In-DOTA-rhenium cyclized alpha-MSH analog: a novel cyclic-peptide analog with improved tumor-targeting properties.

UNLABELLED: The aim of this study was to examine the effect of rhenium-mediated peptide cyclization on melanoma targeting, biodistribution, and clearance kinetics of the alpha-melanocyte-stimulating hormone (alpha-MSH) analog 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) coupled ReO-cyclized [Cys(3,4,10),D-Phe(7)]alpha-MSH(3-13) (DOTA-ReCCMSH). METHODS: DOTA-ReCCMSH was compared with its reduced nonmetalated linear homolog, DOTA-CCMSH, and an analog in which rhenium cyclization was replaced by disulfide bond cyclization, DOTA-[Cys(4,10),D-Phe(7)]alpha-MSH(4-13) (CMSH). DOTA was also conjugated to the amino terminus of one of the highest-affinity alpha-MSH receptor-binding peptides, [Nle(4),D-Phe(7)]alpha-MSH (NDP), as a linear peptide standard. The DOTA-conjugated alpha-MSH analogs were radiolabeled with (111)In and examined for their in vitro receptor-binding affinity with B16/F1 murine melanoma cells, and their in vivo biodistribution properties were evaluated and compared in melanoma tumor-bearing C57 mice. RESULTS: The tumor uptake values of (111)In-DOTA-ReCCMSH were significantly higher than those of the other closely related (111)In-DOTA-alpha-MSH conjugates. Even at 24 h after injection, a comparison of the tumor uptake values for (111)In-DOTA-coupled ReCCMSH (4.86 +/- 1.52 percentage injected dose [%ID]/g), CCMSH (1.91 +/- 0.56 %ID/g), CMSH (3.09 +/- 0.32 %ID/g), and NDP (2.47 +/- 0.79 %ID/g) highlighted the high tumor retention property of ReCCMSH. Rhenium-coordinated cyclization resulted in less renal radioactivity accumulation of (111)In-DOTA-ReCCMSH (8.98 +/- 0.82 %ID/g) than of (111)In-DOTA-CCMSH (63.2 +/- 15.6 %ID/g), (111)In-DOTA-CMSH (38.4 +/- 3.6 %ID/g), and (111)In-DOTA-NDP (12.0 +/- 1.96 %ID/g) at 2 h after injection and significantly increased its clearance into the urine (92 %ID at 2 h after injection). A high radioactivity uptake ratio of tumor to normal tissue was obtained for (111)In-DOTA-ReCCMSH (e.g., 489, 159, 100, and 49 for blood, muscle, lung, and liver, respectively, at 4 h after injection). CONCLUSION: The novel ReO-coordinated cyclic structure of DOTA-ReCCMSH contributes significantly to its enhanced tumor-targeting and renal clearance properties and makes DOTAReCCMSH an excellent candidate for melanoma radiodetection and radiotherapy.

Animals↗
PubMed2001

[Preliminary approach to environmental risk assessment of drainage projects during oilfield exploitation in Daqing].

A qualitative analysis was made to assess the environmental risk and its impact of alternative drainage projects around Yong-5 oil-transport station at Yongle oilfield in Daqing. On the basis of this, a method of fuzzy comprehensive assessment was applied to set up corresponding indexes, to determine hazard environmental coefficients, and to calculate the environmental risk fuzzy assessment indexes which reflect the relative risk degrees of alternative drainage projects. The measures on environmental risk management were proposed according to the priority of alternative projects.

China↗
PubMed2001

[Experimental study on resistance to cisplatin and taxol in human ovarian cancer SKOV3ip1 multicellular aggregates].

OBJECTIVE: To investigate the chemosensitivity of ovarian cancer SKOV3ip1 multicellular aggregates to cisplatin and taxol and to explore the possible mechanisms accounting for the effect. METHODS: Liquid overlay system was employed to obtain multicellular aggregates (MCA). We detected the resistance with trypan blue exclusion testing, clonogenic assay, cell cycle profiles and apoptosis with flow cytometry. RESULTS: MCA cells showed higher cell viability than monolayer cells (P = 0.045 and P = 0.003, respectively). After 40 mumol/L cisplatin exposure for 12 hours, no clone (> or = 50 cells) was formed. After 10 mumol/L taxol exposure for 12 hours, the clone formation showed significant difference in 100-cell group between multicellular aggregates and monolayer cells (P < 0.05). MCA cells in G0 + G1 phase was significantly increased (P = 0.003). After cisplatin exposure, the apoptosis rate of MCA cells were not significantly changed (P = 0.100), and so were cell cycle profiles. Taxol exposure brought about significantly decreased apoptosis rate in MCA cells (P = 0.012). Abrogation of G2 + M arrest was also showed in MCA cells (P = 0.002). CONCLUSIONS: SKOV3ip1 MCA cells show varying degree but increased resistance to cisplatin and taxol, in particular the latter. Cisplatin has nearly equal cytotoxicity to monolayer and MCA cells. Cell cycle redistribution, abrogation of G2 + M arrest and multicellular-mediated inhibition of apoptosis can partially account for the resistance.

Antineoplastic Agents↗
PubMed2001

[Changes in serum neopterin levels in patients after trauma].

OBJECTIVE: To evaluate the clinical significance of changes in serum neopterin levels in patients after trauma. METHODS: 41 patients with mechanical injury were divided into three groups according to the injury severity score (ISS). In all patients, blood collection was started within 24 h after injury, and blood samples were obtained at 3, 7, 14, and 21 d post-trauma. The relationship was determined between serum neopterin levels and ISS, multiple organ dysfunction syndrome (MODS) and prognosis in patients. RESULTS: Patients with ISS > or = 25 showed a high neopterin level compared with those with ISS < 16 (P < 0.05 or P < 0.01), and a correlation between mean neopterin levels and ISS was observed in severely injured patients (r = 0.518, P < 0.05). High neopterin levels were measured in patients who developed MODS, showing a persistent marked elevation from day 3 post-trauma onward. The difference between MODS and non-MODS patients was significant on days 3, 7, and 14 after acute insults (P < 0.05 or P < 0.01). In addition, serum neopterin levels of patients with fatal outcome were much higher than those of surviving patients, and it exceeded 50.0 nmol/L in most cases prior to termination (8/12 cases, 66.7%). CONCLUSIONS: Mechanical injury can cause a constant increase in neopterin level, implying an intact reaction by T lymphocytes and macrophage axis. The measurement of serum neopterin might serve as a tool for the evaluation of injury severity, early detection of MODS as well as prediction of outcome in patients after trauma.

Adult↗
PubMed2001

[Anterior thoracolumbar K-plate fixation system: design and clinical application].

OBJECTIVES: To develop an anterior thoracolumbar K-plate fixation system and to report its preliminary clinical application. METHODS: The K-plate system was developed with titanium alloy(TC4, Ti6A14V) and self-locking screw design was used. In 23 cases treated with this system, 13 had thoracolumbar fracture, 9 tuberculosis, and back syndrome after lumbar TFC operation. RESULTS: All the 23 cases were followed up for one to ten months, averaging 4.5 months. In the 13 cases of fracture, body height of injured vertebra were regained completely, and neurologic deficits improved 2.1 grades in Frankel scale. In the 9 cases of tuberculosis, neurologic functions recovered and no local recurrence was noted. In one case of back syndrome, symptoms and signs did not occur after anterior TFC removal, interbody fusion, and K-plate fixation. This patient received second operation to remove K-plate 3 months after solid osseous fusion, and no electric erosion or obvious tissue reaction was found. 18 of the 23 cases were followed up for four months or more, and solid fusion was found in these patients in three to four months after surgery. No early complications related to implant were noted during the follow-up. CONCLUSION: This K-plate system is suitable for reconstruction of thoracolumbar stability after anterior decompression in indicated patients.

Adult↗
PubMed2001

[The effect of the hyper-erupted third molar on chewing movement].

OBJECTIVE: To investigate the effect of the hyper-erupted third molar contacting closely to the distal surface of the opposing second molar on the chewing movement. METHODS: Twenty-three university student volunteers, 11 with hyper-erupted third molar teeth and 12 with normal occlusion, were enrolled in present study. There were totally 6 unilateral hyper-erupted third molars (3 upper and 3 lower) and 5 bilateral hyper-erupted third molars (1 bilateral upper and 4 bilateral lower). No other significantly abnormal occlusal phenomenon was observed. Five gum-chewing cycles masticated with an each side were separately recorded by means of K6-I mandibular kinesiograph (MKG) and the chewing cycles were analyzed. Both three-dimensional amplitudes and the related velocities were automatically documented with the instrument. RESULTS: (1) The chewing graphs recorded on both frontal and horizontal planes in controls were typically smooth cycles with clearly occlusal phase tracings. On the sagital plane the opening and closing traces around intercuspal position (ICP) were usually overlapped with each other. (2) 63.6% frontal cycles of the subjects with hyper-erupted third molar had an obvious table (0.2 mm to 1.0 mm in width) around ICP, 50% horizontal cycles of the subjects had a 0.2 mm to 0.5 mm step near to ICP, 72.7% opening and closing traces on the sagital plane separated into anterior and posterior branches. The abnormal traces on the three different planes of the hyper-erupted third molar tooth group appeared to be related each other, implying that they might be caused by the same characteristics of occlusion, namely, the hyper-erupted third molar. (3) Subjects with hyper-erupted third molar masticated in more posterior direction, together with a higher chewing terminal velocity. CONCLUSIONS: The hyper-erupted third molar had a significant effect on the chewing cycles around ICP, as well as on the amplitude and velocity of chewing movement.

Adolescent↗
PubMed2001

[Effects of quinacrine on gut-origin bacteria/endotoxin translocation in rats with gut ischemia/reperfusion injury].

OBJECTIVE: To explore the influence of quinacrine, which is an inhibitor of phospholipase A2, on gut-origin bacteria/endotoxin translocation in rats with gut ischemia/reperfusion injury. METHODS: Forty-two Wistar rats were randomly divided into normal control (C, n = 6), gut ischemia/reperfusion injury control (IC, n = 12), quinacrine use at 3 hours after the injury(3 h, n = 12), and quinacrine use at 12 hours after the injury (12 h, n = 12) groups. The contents of blood endotoxin and TNF alpha in venae cavae and portal vein were measured in all groups. At the same time, tissue samples from mesenteric lymph nodes, liver, lungs and kidneys were harvested for bacterial culture. RESULTS: Plasma contents of endotoxin and TNF alpha were lowered in both quinacrine treatment groups (P < 0.01). The incidence of bacterial/endotoxin translocation was decreased by quinacrine use in mesenteric lymph nodes, lungs, liver and kidneys after the injury (P < 0.05 approximately 0.01). CONCLUSION: Early application of quinacrine in Wistar rats inflicted by gut ischemia reperfusion injury could obviously lower bacterial/endotoxin translocation and ameliorate the release of pro-inflammatory mediators and cytokines, thus attenuating injury to remote organs.

Animals↗
PubMed2001

[Changes of plasma p-selectin and nitric oxide in patients with pregnancy induced hypertension].

OBJECTIVE: To study the roles of P-selectin and nitric oxide (NO) on the etiology of pregnancy induced hypertension (PIH). METHODS: The levels of plasma P-selectin and nitrite and nitrate (NO2-/NO3-) were determined in 36 patients with PIH. The data were compared with those of normal pregnant group (n = 18) and healthy non-pregnant group (n = 19). The levels of plasma P-selectin were measured by means of enzyme-linked immunosorbent assay (ELISA) and levels of plasma NO2-/NO3- were measured by Griess reaction after the nitrate was reduced by a Cadmium-reduction method. RESULTS: The result showed: (1) The level of P-selectin in the normal pregnant group (48.92 +/- 15.16) micrograms/L was higher than that in non-pregnant group [(30.16 +/- 8.42) micrograms/L, P < 0.001]. There was no significantly statistical difference in the levels of P-selectin between the normal pregnant group and the mild PIH group (P > 0.05). The levels of P-selectin in the moderate and severe PIH group (70.11 +/- 17.65) micrograms/L were higher than those in the mild PIH group [(47.33 +/- 17.95) micrograms/L, P < 0.01] and the normal pregnant group (P < 0.001). (2) The concentration of NO2-/NO3- in normal pregnant group was higher than that in non-pregnant group (P < 0.01). The concentration of NO2-/NO3- in PIH group were lower than was in normal pregnant group (P < 0.001). The NO2-/NO3- in mild group was lower than that in normal pregnant group (P < 0.001). The Plasma concentration of NO2-/NO3- in moderate and severe PIH group was lower than that of mild group (P < 0.05). (3) There was a negative correlation between the plasma concentration of P-selectin and NO2-/NO3- in the PIH group. CONCLUSION: The changes of plasma levels of P-selectin and NO are related to the occurrence and development of PIH.

Adult↗
PubMed2001

Ultrastructure of intrahepatic biliary canaliculi and prognosis of congenital biliary atresia.

OBJECTIVE: To investigate the relationship between the ultrastructure of intrahepatic biliary canaliculi and the prognosis of congenital biliary atresia. METHODS: Liver biopsies from 25 patients who were operated on for congenital biliary atresia were examined under the transmission electron microscope. The relationship between the number of well-developed bile canaliculi and patient prognosis was studied. RESULTS: The survival rate for 13 patients with well-developed intrahepatic biliary canaliculi and 12 patients with poorly-developed intrahepatic biliary canaliculi were 92.3% (12/13) and 33.3% (4/12) respectively. The difference between two groups was statistically significant (P < 0.05). CONCLUSIONS: Intrahepatic biliary canaliculi ultrastructure could be used as one of the prognostic factors in congenital biliary atresia.

Bile Canaliculi↗
PubMed2001

In vitro study on the morphology of human blood dendritic cells and LPAK cells inducing apoptosis of the hepatoma cell line.

OBJECTIVE: To observe in vitro effects and morphological changes of human peripheral blood dendritic cells (DCs) on the ability of lymphokine and phytohaemagglutininum (PHA) activated killer (LPAK) cells to induce apoptosis of the human hepatoma cell line (BEL-7402, B). METHODS: Experimental groups were divided into LD group (DCs + L + B), L group (L + B), D group (DCs + B) and B group. The methods of neutral red uptake, ordinary light microscopy, electron microscopy, TDT mediated X-dUTP nick end labeling (TUNEL) were used. RESULTS: The difference between the D group and the B group was not distinct (P > 0.05). The difference between the LD group and the L group was distinct, with DCs + LPAK > LPAK (P < 0.01) in cytotoxicity. Apoptotic cells were TUNEL positive in light microscopy, and apoptotic nuclei were stained yellow brown and dark brown, with size and shape varying from cell to cell. Ultrastructural change in apoptotic tumor cells comprised of compaction and condensation of nuclear chromatin, and condensation of cytoplasm and apoptotic bodies. At the same time, LPAK cells manifested the characteristics of autophagic apoptosis, and there were some autophagic bodies in it. CONCLUSIONS: The combination of human blood DCs and LPAK cells could induce apoptosis of BEL-7402 cells effectively, with some LPAK cells manifesting the characteristics of autophagic apoptosis.

Apoptosis↗
PubMed2001

Magnetic resonance imaging in distinguishing malignant from benign pleural disease.

OBJECTIVE: To explore the role of magnetic resonance imaging (MRI) in distinguishing malignant from benign pleural disease. METHODS: All 64 patients were examined with both computed tomography (CT) and MRI. The morphologic features of pleural lesions and MR signal intensity on T1-weighted, T2-weighted and contrast-enhanced T1-weighted images were evaluated. RESULTS: Mediastinal pleural involvement, circumferential pleural thickening, nodularity, irregularity of pleural contour, and infiltration of the chest wall and/or diaphragm were most suggestive of a malignant cause on CT and MR images. Contrary to what has been reported in the literature, pleural thickness greater than 1 cm either on CT or on MRI did not reveal a significant difference between malignant and benign pleural disease (P > 0.05, chi-square test). Using morphologic features in combination with signal intensity features, MRI had a sensitivity of 98% and a specificity of 92% in the detection of pleural malignancy. CONCLUSIONS: Compared with those on CT, the morphologic features on MRI allowed a mostly equal and in some cases superior detection and evaluation of the spread of pleural disease. In combination with signal intensity and morphologic features, MRI is very useful in distinguishing malignant from benign pleural disease.

Adult↗
PubMed2001

[The clinical significance of E-cadherin and alpha-catenin expression in human gastric cancer].

OBJECTIVE: To evaluate the expression of cell adhesion molecules E-cadherin (E-CD) and alpha-catenin (alpha-CA) in relation to biologic behavior of gastric cancer. METHODS: The level of E-CD and alpha-CA expression was examined in 70 cases of primary gastric cancer by immunohistochemical technique. RESULTS: The rate of E-CD and alpha-CA expression was significantly reduced in gastric cancer with more prominent malignant phenotype, such as tumor in stage III/IV with poor cell differentiation, invasion through serosa and lymph node (LN) metastasis. With the increase in the number and frequency of LN metastasis and its dissemination distal to second group LNs, the reduction in expression of the two adhesion molecules was increasingly significant. The frequency of LN metastasis and shed cancer cells in the peritoneum in patients with E-CD(-)/alpha-CA(-) and E-CD(+)/alpha CA(-) cancer were significantly higher than those in patients with E-CD(+)/alpha-CA(+) tumor. Liver metastasis was most frequent in all cases with E-CD(+)/alpha-CA(-) tumor. CONCLUSION: Down regulation of E-CD and/or alpha-CA correlates with the malignant behavior of gastric cancer. Examination of E-CD and alpha-CA expression in primary gastric cancer helps evaluate its intensity of LN metastasis, TNM staging and prognosis.

Cadherins↗
PubMed2001

[Alterations in DPC4 gene in pancreatic cancers].

OBJECTIVE: To examine the alterations in the DPC4 gene in pancreatic cancers. METHODS: Five pancreatic adenocarcinoma cell lines (P1, P2, P3, P4, and P7) and 11 fresh frozen pancreatic cancer tissues were monitored with polymerase chain reaction (PCR), single-strand conformation polymorphism (SSCP) analysis to demonstrate the sequence of deletion and mutation in 6 exons (1, 2, 3, 4, 8, and 11) of the DPC4 gene. RESULTS: Mutation in the DPC4 gene was found in 3 of 5 cells lines (P1, P2, and P3). Three of eleven fresh-frozen tissues showed homozygous deletions and two showed intragenic mutations, with a gene alteration frequency of 45.5% (5/11). CONCLUSION: Alterations in tumor-suppressor gene DPC4 may play an important role during the tumorigenesis of pancreatic cancer.

DNA Mutational Analysis↗
PubMed2001

[The change of plasma von Willebrand factor and endothelin levels in patients with pregnancy induced hypertension].

OBJECTIVE: To study the association of plasma von willebrand factor (vWF) and endothelin-1 (ET-1) levels in patients with pregnancy induced hypertension (PIH). METHODS: Plasma vWF and ET-1 were studied by ELISA method and immunoradiological method respectively in 36 patients with PIH, 18 normal pregnant women and 19 normal non-pregnant women. RESULTS: Circulation levels of vWF and ET-1 were increased with increasing severity of the PIH. In mild PIH patients, the levels of plasma vWF [(135.9 +/- 30.9)%, (P > 0.05)] weren't significantly higher than those in healthy pregnant women [(131.6 +/- 39.2)%, (P > 0.05)], but the levels of ET-1 [(63.7 +/- 4.8) pg/L] were significantly higher than those in healthy pregnant women [(47.1 +/- 4.7) pg/L, (P < 0.01)]. There were significant differences between groups of moderate-severe PIH [vWF (174.4 +/- 35.4)%, ET-1 (92.6 +/- 19.1) pg/L]. There was a positive correlation between the plasma vWF level and ET-1 level. CONCLUSION: The results suggested that plasma vWF and ET-1 concentration could be used as indicators for the severity of PIH.

Adult↗
PubMed2001

Arsenite activation of P13K/AKT cell survival pathway is mediated by p38 in cultured human keratinocytes.

BACKGROUND: Arsenic has been considered as a carcinogen. Recently the issue of arsenic in drinking water raised an unprecedented social concern on human health, and yet the molecular mechanisms through which arsenic induces cancer remain unknown. Activation of cell survival pathway leading to the activation of eNOS has been associated with various types of cancer. The objective of this study was to investigate the pathway leading to the activation of eNOS in response to arsenite using human keratinocytes. MATERIALS AND METHODS: Cultured keratinocytes (HaCat cells) were exposed to arsenite with or without pretreatment of various inhibitors. Western blot analysis was performed to determine the activation of p38, AKT, eNOS. EGFR tyrosine phosphorylation was detected by immunoprecipitation and Western blot analysis. pNPP assay was used to measure phosphatase activity in cell lysate. FACS analysis was performed for the determination of generation of reactive oxygen species. RESULTS: Arsenite induced the activation of AKT at both Ser473 and Thr308, and its downstream effector eNOS in cultured human keratinocytes. Arsenite also induced phosphorylation of p38. PI-3-kinase inhibitors, Wortmannin and LY294002 inhibited arsenite-induced phosphorylation of AKT and eNOS but had no effect on phosphorylation of p38. Interestingly, however, SB203580, a known p38 inhibitor, completely inhibited arsenite-induced phosphorylation of AKT and eNOS. Arsenite induced generation of reactive oxygen species and inactivated phosphatase activity, but did not activate EGF receptor tyrosine phosphorylation. CONCLUSIONS: Collectively, our data indicate that arsenite induces activation of AKT and eNOS, via PI-3-kinase and p38 pathway, likely bypassing the activation of EGF receptor in cultured human keratinocytes.

Arsenites↗