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Biomedical subjects

Lin Chen

Publications and source records attributed to Lin Chen.

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

[Water exposure modes and times of different populations in mountainous schistosomiasis endemic areas near Qionghai lake].

OBJECTIVE: To investigate water exposure modes and times of different populations in mountainous schistosomiasis endemic areas and to inform about the control strategies. METHODS: All 1054 residents from populations around Qionghai Lake were randomly sampled according to occupation for a retrospective questionnaire survey in November 2001. Each individual was interviewed for his/her mode, frequency, and duration of water exposure occurring between April and October 2001. RESULTS: The average exposure times and intensity were higher in farmers (median: 16 - 18 min/day and 2.41 - 2.5, respectively) who grow rice, tobacco, and vegetables than others (median: 3.74 - 7.39 min/day and 0.81 - 1.52, respectively); exposure frequency was found highest in farmers (median: 2.04 times/day) in all occupations; schoolchildren had low exposure frequency and times, but very high exposure intensity (median 2.34). Between April and June it is an agriculturally busy season, that is also a peak season of water exposure of adults. Schoolchildren's water exposure peaks on July and August, mainly due to playing water and swimming. Exposure times and intensities were higher in females than in males. CONCLUSION: Water exposure modes, times, and intensities of different populations were different in mountainous schistosomiasis endemic areas of Xichang. Between April and June should be the peak infection season of adults who are engaging in agricultural activities, while July to August should be the peak infection season for schoolchildren with non-agricultural activities.

Adult↗
PubMed2006

[Human immunodeficiency virus type 1 strains epidemic in Shenzhen].

OBJECTIVE: To study the epidemic status of human immunodeficiency virus type 1 (HIV-1) subtypes in Shenzhen and to study their transmission source and routes. METHODS: HIV-1 env and gag genes were amplified by nested PCR from uncultured peripheral blood mononuclear cells (PBMCs) obtained from 122 HIV-1 carriers confirmed in Shenzhen. The C2-V3 region (about 450 bp) of HIV-1 env and P17/ P24 region were sequenced. RESULTS: Among 122 samples, 6 HIV-1 strains including 3 circulating recombinant forms (CRFs) of CRF01_AE, CRF08_BC, CRF07_BC and 3 subtypes of B', B, C were found in Shenzhen, and the percentages were 45.1% (55/122) for CRF01_AE, 31.1% (38/122) for CRF08_BC, 6.6% (8/122) for CRF07_BC, 14.8% (18/122) for B' subtype, 1.6% (2/122) for B subtype, and 0.8% (1/122) for C subtype. The intragroup genetic distances were (4.455 +/- 1.478)%, (2.997 +/- 1.345)%, (4.380 +/- 2.024)%, (5.186 +/- 2.487)%, and (4.869 +/- 2.638)%, respectively. In comparison with the sequence of respective international strains 01AE. TH. 90. CM240, 97CNGX-9F, CN. 97. C54A, B. US. 83. JRFL, and RLA2, the genetic distances were (5. 228 +/- 0.823)%, (3.634 +/- 1.073)%, (4.233 +/- 1.119)%, (4.950 +/- 2.564)%, and (5.795 +/- 2.198)%, respectively. The major subtypes found in injection drug users (IDUs) were CRF07_BC, CRF08_BC, and CRF01_AE strains. CRF01_AE and B' strains were epidemic mainly in sexual workers. CONCLUSION: There are 3 HIV-1 subtypes (B', B, C) and 3 CRFs (CRF01_AE, CRF08_BC, CRF07_BC) epidemics in Shenzhen. The predominant subtypes varies among different transmission routes. While CRF01_AE is predominant among sexual workers, CRF08_BC and CRF01_AE are major subtypes among IDU population.

Adolescent↗
PubMed2006

[Effects of Sini decoction on vascular stenosis after iliac artery balloon injury and oxidative stress in rabbits].

OBJECTIVE: To investigate the effect of Sini decoction (SND) in preventing vascular restenosis and protecting against oxidative stress after rabbit iliac artery balloon injury. METHODS: Twenty-four male New Zealand albino rabbits were equally randomized into control group, model group and SND group. Rabbits in the control group were fed with common forage, and those in the model and SND groups with high-fat diet. Two weeks later, the iliac arteries of the rabbits in the latter two groups were subjected to balloon injury. Four weeks after the operation, the rabbits were killed and the vascular structure was observed by scanning electron microscope and optical microscope, with the serum cholesterol level, superoxide dismutase (SOD) activity and malondialdehyde (MDA) level determined. RESULTS: Scanning electron microscopy showed that the endothelial cell lining in the iliac artery of the control and SND group remain regular, but the arteries in the model group presented with desquamated and exposure of the collagen fibril beneath the endothelium. Optical microscope revealed narrowed vascular lumen, thicken intima and numerous arteriosclerotic plaques in the model group in comparison with the control group, whereas the vascular lumen and intima thickness remained basically normal in SND group. The levels of total cholesterol, low-density lipoprotein cholesterol and triglyceride were decreased with high-density lipoprotein cholesterol levels increased in SND group, which was not observed in the model group. The serum SOD activity was higher in the control group than in the model and SND groups, but SND group had higher serum SOD activity than the model group. The serum MDA level was lower in the control group than in the other two groups, but SND group had lower MDA level than the model group. CONCLUSION: SND can alleviate intimal hyperplasia and vascular stenosis in injured rabbit iliac artery, possibly in relation to increased SOD activity and decreased lipid peroxidation as a result of SND treatment.

Angioplasty, Balloon, Coronary↗
PubMed2006

[Diffusion tensor imaging of the white matter tracts in preoperative patients with cerebral neoplasm].

OBJECTIVE: To evaluate the quantitative relationship between white matter tract (WMT) variation resulting from cerebral tumors and shifting of the fractional anisotropy (FA) index in magnetic resonance (MR) diffusion tensor imaging (DTI). METHODS: Four female and 8 male patients aged from 21 to 62 years with brain malignancies (2 malignant lymphomas, 2 low-grade astrocytomas, and 8 high-grade cerebral gliomas) underwent conventional contrast-enhanced MR and DTI examinations before operation. Routine T(2)-weighted image, fractional anisotropic (FA) map, color-coded directional map, three-dimensional white matter tractography (WMT), and the FA index of bilateral internal capsule were obtained in every patient. RESULTS: Fiber tractography derived from DTI was consistent with known white matter fiber anatomy. The DTI patterns in WMT altered by the tumor were categorized on the basis of FA1/FA2 ratio as follows: pattern 1, FA1/FA2> or =75% with normal or only slightly decreased FA; pattern 2, 50%< or =FA1/FA2<75% with WMT displacement; pattern 3, 25%< or =FA1/FA2/50% with WMT involvement; pattern 4, FA1/FA2<25% with WMT destruction. CONCLUSIONS: DTI allows for visualization of WMT and benefits surgical planning for patients with intrinsic brain tumor. There is a positive relationship between the bilateral FA ratio (FA1/FA2) variation and WMT alterations resulting from the tumor.

Adult↗
PubMed2006

[Collagen type I and interleukin-1 beta gene expression in human atria during atrial fibrillation].

OBJECTIVE: To determine whether gene expression of collagen type I and interleukin-1 beta (IL-1beta) is altered in patients with atrial fibrillation (AF). METHODS: Right atrial tissue samples were taken from 75 patients with rheumatic heart disease who underwent heart valve replacement surgery. 34 patients had no history of AF, 11 patients had paroxysmal AF and 30 patients had persistent AF. The mRNA content of collagen type I and IL-1beta was measured with semi-quantitative RT-PCR. RESULTS: The mRNA content of collagen type I was significantly increased in the persistent AF group (P < 0.001) and increased in the paroxysmal AF group (P < 0.05) as compared with that in the sinus rhythm group. The mRNA content of IL-1beta was up-regulated in the persistent AF group (P < 0.05), but the trend of increase did not reach statistical significance in the paroxysmal AF group (P > 0.05). The mRNA content of IL-1beta was significantly correlated with the mRNA content of collagen type I (r = 0.295, P = 0.011), left atrial dimension (r = 0.385, P = 0.001) and AF duration (r = 0.326, P = 0.004). CONCLUSION: The upregulation of IL-1beta gene expression in atrium may contribute to the atrial fibrosis during AF through influencing collagen metabolism.

Adolescent↗
PubMed2005

[Role of bcl-2 transcriptional regulation induced by calmodulin I pressure overload rat hypertrophic hearts].

This study was designed to evaluate the role of bcl-2 transcriptional regulation induced by calmodulin I (CaM I) in pressure overload rat hypertrophic hearts. The model of hypertensive Sprague-Dawley rat was established by abdominal aortic constriction. The hearts were collected four weeks after abdominal aortic constriction. Velocity and isopyknic gradient centrifugation was employed to fractionate rat myocardial nuclei. Western blot analysis revealed a marked increase in phosphorylated cAMP response-element binding protein (pCREB) of cardiac hypertrophy group compared with that in control group (P<0.05), while the protein level of cAMP response-element binding protein (CREB) was constant (P>0.05). Immunohistochemistry results showed a significant increase of CaM I protein in cardiac hypertrophy group relative to the control group (P<0.05). Nuclear run off transcription assay displayed a significant increase in bcl-2 mRNA treated with trifluoperazne compared with non-drug treatment (P<0.05). The results obtained suggest that the transcription of bcl-2 is possibly regulated by CaM I hypertrophic rat hearts, and CREB phosphorylation seems to be a minor factor in bcl-2 transcriptional regulation.

Animals↗
PubMed2005

[Arresten expressed in vivo suppresses the growth of SGC-7901 tumor xenografts in nude mice].

OBJECTIVE: To investigate the inhibitory effect of arresten on the growth of SGC-7901 tumor xenograft nude mice model with the localized expression of arresten. METHODS: The secretable eukaryotic expression vector pcDNA3.1 (+)-ss-arresten was constructed by molecular clone strategy, and then was transfected into human gastric cancer cell line SGC-7901 using liposome. The Western blot method was used to examine whether the protein was secreted into cell medium, and the biological behaviors of genetically modified SGC-7901 cell clone was further investigated with MTT and flow cytometry analysis system (FCAS). At last, the SGC-7901 cells expressing arresten were implanted subcutaneously into nude mice, and the weights of tumor xenografts were recorded and analyzed. RESULTS: The eukaryotic expression vector containing secretable arresten cDNA was constructed successfully. The SGC-7901 cell line with the character of expression of arresten was obtained. The growth of arresten cDNA genetic-modified SGC-7901 tumor xenograft was suppressed. CONCLUSIONS: The anti-tumor effect of arresten in the SGC-7901 xenograft is by inhibition of the proliferation of vascular endothelial cell of the tumor.

Angiogenesis Inhibitors↗
PubMed2005

[Reversal of the multidrug resistance in human hepatocellular carcinoma cells by recombinant adenoviral delivery of the MRP antisense RNA in vitro].

OBJECTIVE: To explore the effect of multidrug resistance-associated protein (MRP) antisense RNA mediated by recombinant adenoviruses on reversal of the multidrug resistance in human drug-resistant hepatocellular carcinoma (HCC) cells. METHODS: The HCC cells were first treated in vitro by the recombinant adenoviruses containing antisense MRP. Chemosensitivity of all of the cells to ADM and DNR was determined by MTT assay. The levels of the MRP mRNA and its product P190 were measured by RT-PCR and flow cytometry (FCM) respectively according to the time after transfection. The accumulation of the DNR in these cells was analyzed by FCM simultaneously. RESULTS: IC50 of the cells infected by Ad-Asmrp to ADM and DNR was 0.487 microg/ml and 0.328 microg/ml respectively, with the factors of resistance (RF) decreased by 36.8 and 35.4 respectively (P < 0.05). Continuous decrease in levels of MRP mRNA and P190 was observed 24 h and 48 h after infection respectively (P < 0.01). The intracellular DNR accumulation was increased simultaneously in the Ad-Asmrp transfectants (P < 0.001). CONCLUSIONS: MRP antisense RNA mediated by recombinant adenoviruses could increase chemosensitivity and partially reverse the MDR in HCC cells in vitro by inhibit expression of MRP gene. The study would provide experimental basis for the reversal of MDR in HCC by antisense RNA technology mediated by recombinant adenoviruses.

Adenoviridae↗
PubMed2005

Successful combination of local CpG-ODN and radiotherapy in malignant glioma.

Oligodeoxynucleotides containing CpG motifs (CpG-ODN) display broad immunostimulating activity and are currently under clinical trial in various malignancies, including recurrent glioblastomas. Combining CpG-ODN with another therapy that could induce antigen release might enhance tumor-specific immune response. We investigated whether radiotherapy (RT) could be associated advantageously to intratumoral injections of CpG-ODN. Fisher rats bearing 9L glioma were treated with various combinations of RT and CpG-28, an oligonucleotide with good immunostimulating activity. RT and CpG-28 induced complete tumor remission in one-third of the animals. When both treatments were combined, complete tumor remission was achieved in two-thirds of the animals (p < 0.001 when compared to non-treated rats, p < 0.03 when compared to CpG-28 alone). Such efficacy was not observed in nude mice, underlying the role of T cells in antitumor effects. The combination of both treatments appeared optimal when the delay between RT and CpG-28 administration was <3 days (from 100% survival for a 3 days delay, to 57% survival for a 21 days delay, p < 0.05). Tumor infiltration by immune cells and expression within tumors of the CpG receptor, TLR9, were not modified by irradiation. These results support an attractive strategy of sequential radiotherapy and immunotherapy by CpG-ODN and have potential implications for future clinical trials with CpG-ODN.

Animals↗
PubMed2005

Spindlin1, a novel nuclear protein with a role in the transformation of NIH3T3 cells.

spindlin1, a novel human gene recently isolated by our laboratory, is highly homologous to mouse spindlin gene. In this study, we cloned cDNA full-length of this novel gene and send it to GenBank database as spindlin1 (Homo sapiens spindlin1) with Accession No. AF317228. In order to investigate the function of spindlin1, we studied further the subcellular localization of Spindlin1 protein and the effects of spindlin1 overexpression in NIH3T3 cells. The results showed that the fusion protein pEGFP-N1-spindlin1 was located in the nucleus and the C-terminal is correlated with nuclear localization of Spindlin1 protein. NIH3T3 cells which could stably express spindlin1 as a result of RT-PCR analysis compared with the control cells displayed a complete morphological change; made cell growth faster; and increased the percentage of cells in G2/M and S phase. Furthermore, overexpressed spindlin1 cells formed colonies in soft agar in vitro and formed tumors in nude mice. Our findings provide direct evidence that spindlin1 gene may contribute to tumorigenesis.

Agar↗
PubMed2005

Value of CT-guided core-needle biopsy in diagnosis and classification of malignant lymphomas using automated biopsy gun.

AIM: To evaluate the value of CT-guided core-needle biopsy in diagnosis and classification of malignant lymphomas. METHODS: From January 1999 to October 2004, CT-guided core-needle biopsies were performed in 80 patients with suspected malignant lymphoma. Biopsies were performed with an 18-20 G biopsy-cut (CR Bard, Inc., Covington, GA, USA) needle driven by a spring-loaded Bard biopsy gun. RESULTS: A definite diagnosis and accurate histological subtype were obtained in 61 patients with a success rate of 76.25% (61/80). Surgical sampling was performed in 19 patients (23.75%) with non-diagnostic core-needle biopsies. The success rate of CT-guided core-needle biopsy varied with the histopathologic subtypes in our group. The relatively high success rates of core-needle biopsy were noted in diffuse large B-cell non-Hodgkin's lymphoma (NHL, 88.89%) and peripheral T-cell NHL (90%). However, the success rates were relatively low in anaplastic large cell (T/null cell) lymphoma (ALCL, 44.44%) and Hodgkin's disease (HD, 28.57%) in our group. CONCLUSION: CT-guided core-needle biopsy is a reliable means of diagnosing and classifying malignant lymphomas, and can be widely applied in the management of patients with suspected malignant lymphoma.

Adolescent↗
PubMed2005

Sodium salicylate reduces gamma aminobutyric acid-induced current in rat spinal dorsal horn neurons.

Sodium salicylate is one of the nonsteroidal antiinflammatory drugs and is clinically used for antiinflammation and chronic pain relief. In the present study, we investigated the actions of sodium salicylate on gamma-aminobutyric acid type A receptor (GABA(A)) current in cultured rat spinal dorsal horn neurons. Sodium salicylate was found to reduce GABA(A) current in a reversible and concentration-dependent manner, but did not change its ion selectivity. Sodium salicylate was effective only when GABA and sodium salicylate were applied together. Application of sodium salicylate immediately before, but not during, the application of GABA did not result in a significant reduction of GABA(A) current. Our results demonstrate that sodium salicylate reversibly attenuates the GABA(A) response of dorsal horn neurons, suggesting that GABA(A) receptors in the region are pharmacological targets of sodium salicylate.

Animals↗
PubMed2005

Proapoptotic Bak is sequestered by Mcl-1 and Bcl-xL, but not Bcl-2, until displaced by BH3-only proteins.

Commitment of cells to apoptosis is governed largely by the interaction between members of the Bcl-2 protein family. Its three subfamilies have distinct roles: The BH3-only proteins trigger apoptosis by binding via their BH3 domain to prosurvival relatives, while the proapoptotic Bax and Bak have an essential downstream role involving permeabilization of organellar membranes and induction of caspase activation. We have investigated the regulation of Bak and find that, in healthy cells, Bak associates with Mcl-1 and Bcl-x(L) but surprisingly not Bcl-2, Bcl-w, or A1. These interactions require the Bak BH3 domain, which is also necessary for Bak dimerization and killing activity. When cytotoxic signals activate BH3-only proteins that can engage both Mcl-1 and Bcl-x(L) (such as Noxa plus Bad), Bak is displaced and induces cell death. Accordingly, the BH3-only protein Noxa could bind to Mcl-1, displace Bak, and promote Mcl-1 degradation, but Bak-mediated cell death also required neutralization of Bcl-x(L) by other BH3-only proteins. The results indicate that Bak is held in check solely by Mcl-1 and Bcl-x(L) and induces apoptosis only if freed from both. The finding that different prosurvival proteins have selective roles has notable implications for the design of anti-cancer drugs that target the Bcl-2 family.

Amino Acid Sequence↗
PubMed2005

Roles of FGF signaling in skeletal development and human genetic diseases.

Fibroblast growth factor receptors (FGFRs) exist as a gene family of 4 membrane bound receptor tyrosine kinases (FGFR1-4) that mediate signals of at least 22 fibroblast growth factors (FGF1-22). FGFs/FGFRs play important roles in multiple biological processes, including mesoderm induction and patterning, cell growth and migration, organ formation and bone growth. Furthermore, it has been shown that missense mutations of FGFR1-3 in human result in, at least, 14 congential bone diseases that are broadly classified into two groups: chondrodysplasia syndromes and craniosynostosis syndromes. The chondrodysplasia affects primarily the skeleton formed through endochondral ossification, resulting short-limbed dwarfisms, while the craniosynostosis affects mainly bones formed through intramembraneous ossification, leading to premature fusion of the craniofacial sutures. Using gene targeting, mouse models mimicking some of these human diseases have been created. Analysis of these mutant mice revealed essential functions of FGFs/FGFRs in skeletal development and maintenance. These models may be beneficial in future studies aimed at developing novel therapeutic strategies for FGFR-related skeletal dysplasias. In this review, we discuss the results of recent studies on FGF receptors to illustrate mechanisms through which the abnormally activated FGF/FGFR signaling results in these diseases.

Animals↗
PubMed2005

Effect of anti-tuberculosis therapy on liver function of pulmonary tuberculosis patients infected with hepatitis B virus.

AIM: To observe the effect of anti-tuberculosis therapy on liver function of pulmonary tuberculosis patients with hepatitis B virus (HBV) infection, and to compare the differences of liver function by two treatments of anti-tuberculosis. METHODS: Forty-seven TB patients with HBV infection and 170 TB patients without HBV infection were divided into HPBE(S) and HLAMKO treatment groups. Liver function tests before and after the treatments were performed once in 2 wk or monthly, and their clinical manifestations were recorded. RESULTS: The rate of hepatotoxicity occurred in 26 (59%) TB patients with HBV during anti-TB treatment, higher than that in 40 (24%) TB patients without HBV. Hepatotoxicity occurred in 66 out of 217 patients, and the incidence of liver dysfunction was 46.1% in HPBE(S) group, significantly higher than that in HLAMKO group (12.7%) (P<0.01). CONCLUSION: TB patients with HBV should choose HLAMKO treatment because of fewer hepatotoxicity.

Adult↗
PubMed2005

The involvement of neutrophils in the resistance to Leishmania major infection in susceptible but not in resistant mice.

To understand the immunomodulatory roles of neutrophils in Leishmania major infection, we examined the expression of cytokine and chemokine mRNAs from neutrophils of the infected resistant C3H/HeJ and susceptible BALB/c mice. We also examined the effects of neutrophil depletion on the expression of cytokine by peritoneal macrophages and draining lymph node cells and on the footpad lesions and parasite burdens in these mice. Neutrophils from resistant C3H/HeJ but not from susceptible BALB/c mice expressed mRNAs for IL-12p40, IFN-gamma,TNF-alpha and monokine induced by IFN-gamma(MIG). Neutrophil depletion of the resistant mice reduced the expression of IFN-gammaandTNF-alpha in peritoneal macrophages but did not affect the expression of IL-12p40 and IFN-gamma in draining lymph node cells and the growth of footpad lesions. On the other hand, neutrophil depletion of susceptible BALB/c mice did not affect the expression of TNF-alpha and monocyte-derived chemokine (MDC) in peritoneal macrophages but induced the early stage expression of IL-4 in draining lymph node cells and exacerbated the footpad lesions and increased the parasite burden. The exacerbation of footpad lesions induced by neutrophil depletion was abolished by rIL-12 treatment. Our results suggest that even in susceptible BALB/c but not in C3H/HeJ mice there is a certain resistance requiring neutrophils at the early stage of infection.

Animals↗
PubMed2005

Synthetic analogues of migrastatin that inhibit mammary tumor metastasis in mice.

Tumor metastasis is the most common cause of death in cancer patients. Here, we show that two, fully synthetic migrastatin analogues, core macroketone and core macrolactam, are potent inhibitors of metastasis in a murine breast tumor model. Administration of these readily accessible compounds nearly completely inhibits lung metastasis of highly metastatic mammary carcinoma cells. Treatment of tumor cells with core macroketone and core macrolactam blocks Rac activation, lamellipodia formation, and cell migration, suggesting that these chemical compounds interfere with the invasion step of the metastatic process. These compounds also inhibit the migration of human metastatic breast cancer cells, prostate cancer cells, and colon cancer cells but not normal mammary-gland epithelial cells, fibroblasts, and leukocytes. These data demonstrate that the macroketone and macrolactam core structures are specific small-molecule inhibitors of tumor metastasis. These compounds or their analogues could potentially be used in cancer-therapy strategies.

Animals↗