PubMed Health⌕ Search

Biomedical subjects

Li Chen

Publications and source records attributed to Li Chen.

At least 91 records · Page 5Linked to original sources
PubMed2006

Roles of cortactin, an actin polymerization mediator, in cell endocytosis.

Cortactin, an actin-binding protein and a substrate of Src, is encoded by the EMS1 oncogene. Cortactin is known to activate Arp2/3 complex-mediated actin polymerization and interact with dynamin, a large GTPase and proline rich domain-containing protein. Transferrin endocytosis was significantly reduced in cells by knock-down of cortactin expression as well as in vivo introduction of cortactin immunoreagents. Cortactin-dynamin interaction displayed morphologically dynamic co-distribution with a change in the endocytosis level in cells treated with an actin depolymerization reagent, cytochalasin D. In an in vitro beads assay, a branched actin network was recruited onto dynamin-coated beads in a cortactin Src homology domain 3 (SH3)-dependent manner. In addition, cortactin was found to function in the late stage of clathrin coated vesicle formation. Taken together, cortactin is required for optimal clathrin mediated endocytosis in a dynamin directed manner.

Actin-Related Protein 2↗
PubMed2006

Independent contributions of polyomavirus middle T and small T to the regulation of early and late gene expression and DNA replication.

We previously showed that murine polyomavirus mutants that lack both middle T (MT) and small T (ST) functions have a severe pleiotropic defect in early and late viral gene expression as well as genome amplification. The respective contribution of MT and ST to this phenotype was unclear. This work separates the roles of MT and ST in both permissive mouse cells and nonpermissive rat cells. It demonstrates for the first time a role for both proteins. To gain insight into the signaling pathways that might be required, we focused on MT and its mutants. The results show that each of the major MT signaling connections, Shc, phosphatidylinositol 3'-kinase, and phospholipase C gamma1, could contribute in an additive way. Unexpectedly, a mutant lacking all these connections because the three major tyrosines had been converted to phenylalanine retained some activity. A mutant in which all six MT C-terminal tyrosines had been mutated was inactive. This suggests a novel signaling pathway for MT that uses the minor tyrosines. What is common to ST and the individual MT signaling pathways is the ability to signal to the polyomavirus enhancer, in particular to the crucial AP-1 and PEA3/ets binding sites. This connection explains the pleiotropy of MT and ST effects on transcription and DNA replication.

Animals↗
PubMed2006

Pharmacokinetics and pharmacodynamic effects of the oral DPP-4 inhibitor sitagliptin in middle-aged obese subjects.

Sitagliptin (MK-0431) is an oral, potent, and selective dipeptidyl peptidase-IV (DPP-4) inhibitor developed for the treatment of type 2 diabetes. This multicenter, randomized, double-blind, placebo-controlled study examined the pharmacokinetic and pharmacodynamic effects of sitagliptin in obese subjects. Middle-aged (45-63 years), nondiabetic, obese (body mass index: 30-40 kg/m2) men and women were randomized to sitagliptin 200 mg bid (n = 24) or placebo (n = 8) for 28 days. Steady-state plasma concentrations of sitagliptin were achieved within 2 days of starting treatment, and >90% of the dose was excreted unchanged in urine. Sitagliptin treatment led to approximately 90% inhibition of plasma DPP-4 activity, increased active glucagon-like peptide-1 (GLP-1) levels by 2.7-fold (P < .001), and decreased post-oral glucose tolerance test glucose excursion by 35% (P < .050) compared to placebo. In nondiabetic obese subjects, treatment with sitagliptin 200 mg bid was generally well tolerated without associated hypoglycemia and led to maximal inhibition of plasma DPP-4 activity, increased active GLP-1, and reduced glycemic excursion.

Adenosine Deaminase↗
PubMed2006

Accommodation with higher-order monochromatic aberrations corrected with adaptive optics.

Higher-order monochromatic aberrations in the human eye cause a difference in the appearance of stimuli at distances nearer and farther from best focus that could serve as a signed error signal for accommodation. We explored whether higher-order monochromatic aberrations affect the accommodative response to 0.5 D step changes in vergence in experiments in which these aberrations were either present as they normally are or removed with adaptive optics. Of six subjects, one could not accommodate at all for steps in either condition. One subject clearly required higher-order aberrations to accommodate at all. The remaining four subjects could accommodate in the correct direction even when higher-order aberrations were removed. No subjects improved their accommodation when higher-order aberrations were corrected, indicating that the corresponding decrease in the depth of field of the eye did not improve the accommodative response. These results are consistent with previous findings of large individual differences in the ability to accommodate in impoverished conditions. These results suggest that at least some subjects can use monochromatic higher-order aberrations to guide accommodation. They also show that some subjects can accommodate correctly when higher-order monochromatic aberrations as well as established cues to accommodation are greatly reduced.

Accommodation, Ocular↗
PubMed2006

Proliferation of endothelial cell on polytetrafluoroethylene vascular graft materials carried VEGF gene plasmid.

OBJECTIVE: To investigate whether vascular endothelial growth factor (VEGF) gene plasmid carried by polytetrafluoroethylene (PTFE) vascular graft materials could transfect endothelial cells (ECs) and promote their growth. METHODS: PTFE vascular graft materials carried with pCDI-hVEGF(121), pCDI or pEGFP were incubated in Tris-buffer solution and the values of optical density of 260 nm at different time were plotted, then the DNA controlled release curve was made. ECs derived from human umbilical vein were seeded on the pCDI-hVEGF(121)/pCDI/pEGFP-PTFE materials or tissue culture plates, ECs numbers were counted and VEGF protein concentrations at different time were measured by enzyme-linked immunoadsorbent assay method. Green fluorescent protein (GFP) expression in ECs on pEGFP-PTFE materials was examined with fluorescence microscopy. RESULTS: The controlled release curve showed that the gene released from PTFE materials was rapid within 8 h, then slowed down and that the gene released continuously even after 72 h. At 24, 72 and 120 h, ECs number and proliferation rate of pCDI-hVEGF(121)-PTFE materials were higher than those of pCDI or pEGFP-PTFE materials (P<0.05). VEGF protein concentration of pCDI-hVEGF(121)-PTFE materials was higher than that of pCDI or pEGFP-PTFE materials at 6, 24, 72 and 120 h (P<0.01). GFP expression in ECs on the pEGFP-PTFE materials could be detected by fluorescence microscopy. CONCLUSION: PTFE graft can be used as a carrier of VEGF gene plasmid, VEGF gene carried by PTFE can transfect ECs and promote ECs growth.

Blood Vessel Prosthesis↗
PubMed2006

Osteogenic potential of human periosteum-derived progenitor cells in PLGA scaffold using allogeneic serum.

The use of periosteum-derived progenitor cells (PCs) combined with bioresorbable materials is an attractive approach for tissue engineering. The aim of this study was to characterize the osteogenic differentiation of PC in 3-dimensional (3D) poly-lactic-co-glycolic acid (PLGA) fleeces cultured in medium containing allogeneic human serum. PCs were isolated and expanded in monolayer culture. Expanded cells of passage 3 were seeded into PLGA constructs and cultured in osteogenic medium for a maximum period of 28 d. Morphological, histological and cell viability analyses of three-dimensionally cultured PCs were performed to elucidate osseous synthesis and deposition of a calcified matrix. Furthermore, the mRNA expression of type I collagen, osteocalcin and osteonectin was semi-quantitively evaluated by real-time reverse transcriptase-polymerase chain reaction (RT-PCR). The fibrin gel immobilization technique provided homogeneous PCs distribution in 3D PLGA constructs. Live-dead staining indicated a high viability rate of PCs inside the PLGA scaffolds. Secreted nodules of neo-bone tissue formation and the presence of matrix mineralization were confirmed by positive von Kossa staining. The osteogenic differentiation of PCs was further demonstrated by the detection of type I collagen, osteocalcin and osteonectin gene expression. The results of this study support the concept that this tissue engineering method presents a promising method for creation of new bone in vivo.

Biocompatible Materials↗
PubMed2006

A biomechanical comparison between two volar locking plate systems for distal radius fractures.

The biomechanical properties of two distal radius volar locking plate systems were investigated. A cadaveric model simulating distal radius fractures with dorsal comminution was selected. The biomechanical properties of fracture fixation using the Synthes volar locking T-plate and the Hand Innovation DVR plate were characterized. The average stiffness was 137.1 +/- 19.9 N/mm for the DVR group and 119.1 +/- 9.9 N/mm for the Synthes group (P = .49), and the average changes of the opening angle describing plastic deformation were 10.1 degrees +/- 4.0 degrees and 8.6 degrees +/- 13.2 degrees, respectively (P = .23). This study demonstrates that both the Synthes T-plate and Hand Innovations DVR plate fixation systems show comparable biomechanical characteristics.

Biomechanical Phenomena↗
PubMed2006

Interleukin-10 promoter polymorphisms in patients with hepatitis B virus infection or hepatocellular carcinoma in Chinese Han ethnic population.

BACKGROUND: Since single nucleotide polymorphisms (SNPs) can serve as gene markers, polymorphism profiles may help scientists to identify the full collection of genes that contribute to the development of complex diseases such as cancer. The distribution of interleukin-10 (IL-10) promoter polymorphisms in Chinese Han ethnic patients with hepatitis B virus (HBV) infection and hepatocellular carcinoma (HCC) was investigated in this study. METHODS: The polymorphisms of IL-10 promoter region were detected by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and sequencing. Sixty-six health controls, 42 patients with HBV infection, 30 HCC patients, and cell line SMMC-7721 were examined this way. RESULTS: Polymorphisms of T/C or T/N on -872 site occurred frequently in Han ethnic population. Polymorphisms were detected in HBV and HCC patients and cell line SMMC-7721. The hotspot among the polymorphisms was inserting base A between -1058 and -1057. CONCLUSION: Polymorphisms of IL-10 promoter in HBV and HCC patients may be associated with HBV infection and HCC development.

Asian People↗
PubMed2006

[Expression of NET-1 gene and protein in hepatocellular carcinoma and related tissues].

BACKGROUND & OBJECTIVE: NET-1 is a new tumor-related gene. So far, its expression in hepatocellular carcinoma (HCC) hasn't been reported. This study was to screen and compare the expression of NET-1 among fetal liver tissue, adult normal liver tissue, HCC and adjacent noncancerous tissues; explore its expression feature in HCC. METHODS: The expression of NET-1 mRNA in 3 specimens of fetal liver tissue, 4 specimens of adult liver tissue, 4 specimens of test HCC tissue, and 28 specimens of HCC and adjacent noncancerous tissues was detected by reverse transcription-polymerase chain reaction (RT-PCR). The expression level of NET-1 gene was analyzed by Four-Star image analysis software. NET-1 gene polyclonal antibody was generated by gene biological engineering, and its expression in human hepatic cancer cell line SMMC-7721 was observed under laser confocal microscope. The expression of NET-1 protein in the 28 specimens of HCC and adjacent noncancerous tissues was detected by immunohistochemistry. RESULTS: NET-1 mRNA was expressed in all of the 4 specimens of test HCC tissue, but didn't express in normal adult and fetal liver tissues; the positive rates of NET-1 mRNA were 85.71% (24/28) in both HCC and adjacent noncancerous tissues. The mRNA level of NET-1 was significantly higher in HCC than in adjacent noncancerous tissues (0.65 vs. 0.47, P<0.05). Observed under confocal microscope, NET-1 antibody was expressed in cytoplasm of SMMC-7721 cells. The positive rate of NET-1 protein was significantly higher in HCC than in adjacent noncancerous tissues (96.43% vs. 71.43%, P<0.05). In both HCC and adjacent noncancerous tissues, the positive rate of NET-1 mRNA was positively correlated to that of NET-1 protein (r=0.48, P<0.05; r=0.40, P<0.05). CONCLUSION: NET-1 gene expression might be an early event in HCC development, and may have specific value in HCC diagnosis.

Adult↗
PubMed2006

[Angiogenesis and metastasis of carcinoma].

Metastasis of cancer cells from original tumor region plays a major role for the malignancy. Released cancer cells attache on the outer membranes of endothelial cells of blood vessel, and can go through the wall and settle down in the tissue. Growing tumor needs blood supply for the high energy metabolism, but the hypoxic condition inside of tumor activates hypoxia inducible factors (HIFs), which transactivates several sets of angiogenic factors such as vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), and induces angiogenesis and promotes tumor growth. Physiological angiogenesis, however, is regulated under the balance between angiogenic and anti-angiogenic factors. We here focus on the role of angiogenesis in tumor metastasis.

Animals↗
PubMed2006

[Study on reproductive and developmental toxicity of the pregnant mice and their foetus co-administered by p, p'-DDE and beta-BHC].

OBJECTIVE: To explore effects of p, p'-DDE and beta-BHC on reproduction and development in mice. METHODS: The pregnant Kunming SPF mice of 12 to 14 days were co-administered by oral gavage for 3 days at different concentrations of 0, 1, 5 and 10 mg/kg bw of p, p'-DDE and beta-BHC. The concentrations of estradiol (E2) and progesterone (P) in sera of the dosed mice were determined by the Serozyme kits (Bio-Ekon biotechnology Co., Beijing, China), following the procedures described by the manufacturer. RT-PCR was employed to detect abundant expression of alpha-estrogen receptor (alpha-ER) gonadtropin releasing hormone (GnRH) and beta-endorphin (beta-EP) mRNA in placentae. RESULTS: (1) Reproductive effects: with increase of the administered p,p'-DDE and P-BHC,the organ coefficient of uterus and its intraluminal fluid increased, the unterine nidation quantity decreased, the anogenital distance (AGD) and ratio of female to male raised, the concentration of estradiol and progesterone in sera of the dosed mice went up, and the abundant expression of alpha-ER and GnRH mRNA rised while beta-EP dropped in placentae in a dose-dependant manner. Significant difference of these indexes were found between the treat groups and control (P < 0.05). (2) Developmental effects: with increase of the administered p,p'-DDE and beta-BHC, the gained weights of pregnant mice reduced, organ coefficient of liver increased,the quantity of live foetus decreased, the times of adverse pregnancy outcome went up, and the percent of female foetus increased. They all presented a dose-effect relation and significance of difference (P < 0.05). CONCLUSION: p, p'-DDE and beta-BHC disrupt reproductive function, thereby result in dysreproduction and maldevelopment, and unbalance of ratio of female to male.

Animals↗
PubMed2006

[Report of a case of hybrid acute leukemia with t (12; 22) and literature review].

OBJECTIVE: To report a hybrid acute leukemia (HAL) patient with t (12; 22) (p13; q12). METHODS: Chromosome specimens were prepared by direct method and/or short-time culture of bone marrow cells. Karyotyping was performed by R-banding technique. Leukemia surface markers were detected by anti-biotin-biotin complex and monoclonal antibodies. Chromosome painting (fluorescence in situ hybridization, FISH) was performed by using whole chromosome 12 and 22 probes labeled with green and red fluorescence, respectively. RESULTS: The clinical and hematological findings were compatible with the diagnosis of HAL. Lymphoid and myeloid markers were positive on the leukemia cells. Karyotype analysis showed that the patient had t (12; 22) (p13; q12) translocation. A reciprocal translocation between chromosomes 12p and 22q was proved by FISH. CONCLUSIONS: t (12; 22) translocation is a rare chromosome abnormality in leukemia. Patients with t (12; 22) had unique clinical, cytogenetic features. This translocation as a cytogenetic marker for poor-prognosis in leukemia needs to be further studied.

Adult↗
PubMed2006

[Comparison of therapeutic effects between normal acupuncture and shallow needling with short-needle on periarthritis of shoulder].

OBJECTIVE: To compare therapeutic effects between normal acupuncture and shallow needling with short-needle, and search for therapeutic tool and method easy to be accepted by the patient of periarthritis of shoulder. METHODS: One hundred and fifty-two cases of periarthritis of shoulder were randomly divided into 2 groups. They were treated by normal acupuncture and shallow needling with short-needle, respectively. The two groups were same in acupoints selected and the therapeutic course, and their therapeutic effects and the accepting degrees of the patient were investigated. RESULTS: The cured rate was 67.1% in the normal acupuncture group and 69.7% in the shallow needling with short-needle group, with no significant difference between the two groups (P>0.05). CONCLUSION: Normal acupuncture and shallow needling with short-needle have similar therapeutic effect on periarthritis of shoulder, but the shallow needling with short-needle can obviously relieve the pain and mental fear in treatment, easy to be accepted.

Acupuncture Therapy↗
PubMed2006

[A new thinking of acupuncture and moxibustion treatment of shoulder pain after hemiplegia].

Analysis from anatomy and physiology indicates that causes of shoulder pain are (1) decline and after-constriction of the scapula;(2) the adduction and intorsion of the humerus; (3) the spasm of the upper limb flexor. The acupuncture and moxibustion prescriptions stipulated for prevention and treatment of shoulder pain are Jianjing (GB 21), Jianzhongshu (SI 15), Jugu (LI 16), Tianzong (SI 11), Jianliao (SJ 14), Jiquan (HT 1) at the flaccid hemiplegia, and Jugu (LI 16), Jianyu (LI 15), Tianzong (SI 11), Jianliao (SJ 14), Xiaoluo (SJ 12), Shanglian (LI 9), Wenliu (LI 7) at the spastic hemiplegia , in combination with cupping at the Urinary Bladder Meridian on the back and around shoulder. Thus, it is indicated that shoulder pain not only is involved in the shoulder joint but also in all muscle groups of the shoulder girdle and the upper limb extensor at the affected side.

Acupuncture Therapy↗
PubMed2006

[Studies on cytogeography of Pinellia ternata poliploid complex].

OBJECTIVE: In order to clarify the genetic background of Pinellia ternata germplasm resources in China, the chromosomal constitution and cytogeographical distribution of P. ternata were investigated in 27 different populations among 16 provinces and regions in China systematically. METHOD: Cytological and cytogeographical methods were used in the study. RESULT: P. ternata in China is a polyploid complex, which contains septuploid (2n = 7x = 91) , octoploid (2n = 8x = 104) , nonuploid (2n = 9x = 117) and decaploid (2n = 10x = 130). Meanwhile the aneuploid series (2n = 92, 103, 105, 115) of a minority of P. ternata were also found. CONCLUSION: The genetic differentiation and the phenomenon of ploidy miscellany commonly exist in the species of P. ternata in China, both for natural populations and cultivated populations. Toxicity and chemical components of different ploidy P. ternata should be clarified before the superior multiploid is selected for normalized plantation of the plant.

Aneuploidy↗
PubMed2006

[Analysis on relative factors of influencing limb functional recovery in the patient of hemiplegia].

OBJECTIVE: To investigate relative factors of influencing limb functional recovery in the patient of hemiplegia. METHODS: In 312 stroke patients with hemiplegia who were treated by a comprehensive rehabilitation program, 10 factors of possibly influencing limb functional recovery in the patient of hemiplegia were selected to make retrospective analysis and study on 48 cases with no improvement of limb function after treatment. RESULTS: Functional recovery of hemiplegic limbs was not correlated with gender and location of brain lesion, but was correlated with the age and courses of disease, types of stroke, aphasis, psychic disturbance as well as complications (P < 0.05), with the closest relation to the focus character and cognitive disturbance (P < 0.01). CONCLUSION: In establishing therapeutic project and evaluating prognosis, above relative factors should be considered.

Acupuncture Therapy↗
PubMed2006

[Effects of resolving phlegm method on fibrinolytic status in non-alcoholic steatohepatitis patients of phlegm and blood-stasis syndrome].

OBJECTIVE: To observe the effect of resolving phlegm method (RPM) on fibrinolytic status in non-alcoholic steatohepatitis (NASH) patients of phlegm blood-stasis (PBS) syndrome type. METHODS: Sixty-two patients were randomly assigned to 2 groups, namely the treated group (n = 34) treated with Chinese herbs for resolving phlegm and dampness, smoothing liver and gallbladder, promoting blood circulation and removing blood stasis (composition: Indigo Naturalis 10 g, Alumen 3 g, Semen Cassiae 15 g, Fructus Crataegi 15 g, vinegar prepared Radix Bupleuri 10 g, Radix Curcumae 10 g, Radix Salviae Miltiorrhizae 12 g, Herba Lycopi 12 g, talc 12 g and Radix Glycyrrhizae 2 g), one dose twice per day orally, and the control group (n = 28) with ursodeoxycholic acid tablet (UAT) 150 mg three times per day. The treatment course for both groups was 12 weeks. Liver function (ALT, AST, ALP), insulin resistance (IR) index represented by homeostasis model-IR (HOMA-IR) and insulin (Ins), levels of tissue plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1), as well as main symptoms and physical signs were assessed before and after treatment. RESULTS: (1) Compared with those before treatment, levels of ALT, AST, HOMA-IR, t-PA, PAl-1 and main symptoms were all improved in the treated group (P < 0.05 or P < 0.01); (2) There was significant difference in ALP, HOMA-IR, t-PA and PAI-1 between the treated group and the control group (P < 0.05 or P < 0.01); (3) The improvement in liver function related indexes in the control group was mainly the level of ALT, t-PA (P < 0.01), and also shown on HOMA-IR, Ins and PAI-1. CONCLUSION: RPM could effectively improve liver function and fibrinolytic status. Its effect was better than that of UAT.

Adult↗