Search PubMed⌕ Search

Biomedical subjects

Yi Li

Publications and source records attributed to Yi Li.

At least 145 records · Page 8Linked to original sources
PubMed2005

Erythropoietin treatment improves neurological functional recovery in EAE mice.

Erythropoietin (EPO), originally recognized for its central role in erythropoiesis, has been shown to improve neurological outcome after stroke. Here, we investigated the treatment of experimental autoimmune encephalomyelitis (EAE) in mice with EPO. Mice were treated with recombinant human EPO (rhEPO) upon onset of paresis. Neurological functional tests were scored daily by grading of clinical signs (score 0-5). Hematoxylin and eosin (HE) staining of cerebral tissue was performed to detect inflammatory infiltrates. Double staining for Luxol fast blue and Bielshowsky was used to demonstrate myelin and axons, respectively. Immunohistochemistry was performed to measure the expression of bromodeoxyuridine (BrdU, a marker for cell proliferation), NG2 (a marker for oligodendrocyte progenitor cells) and brain-derived neurotrophic factor (BDNF). Treatment with rhEPO significantly improved neurological functional recovery, reduced inflammatory infiltrates and demyelination, and increased oligodendrocyte progenitor cell proliferation and BDNF+ cells compared to the EAE controls. These data indicate that rhEPO treatment improved functional recovery after EAE in mice, possibly, via stimulating oligodendrogenesis, downregulating proinflammatory infiltrates and by elevating BDNF expression.

Animals↗
PubMed2005

Association of cyclin D1, p16 and retinoblastoma protein expressions with prognosis and metastasis of gallbladder carcinoma.

AIM: To investigate the role of cyclin D1, p16 and retinoblastoma in cancerous process of gallbladder carcinomas and to assess the relation between cyclin D1, p16, Rb and the biological characteristics of gallbladder carcinoma. METHODS: Forty-one gallbladder carcinoma, 7 gallbladder adenoma and 14 chronic cholecystitis specimens were immunohistochemically and histopathologically investigated for the relation of cyclin D1, p16 and Rb with Nevin staging and pathologic grading. RESULTS: The expression rates of abnormal cyclin D1 in gallbladder carcinoma (68.3%) and gallbladder adenoma (57.1%) were significantly higher than those in chronic cholecystitis (7.1%) (P<0.05). No significant difference was found both among the pathological grades G(1), G(2) and G(3) and among Nevin stagings S(1)-S(2), S(3) and S(4)-S(5) of gallbladder carcinoma. The positive rates of p16 (48.8%) and Rb (58.5%) in gallbladder carcinoma were significantly lower compared to those in adenoma (100.0%) and cholecystitis (100.0%) (P<0.05). The positive rates of p16 and Rb in Nevin stagings S(1)-S(2) (80.0% and 90.0%) and S(3) (46.2% and 61.5%) gallbladder carcinomas were significantly higher than those in S(4)-S(5) (33.3% and 38.8%) (P<0.05), and those in pathologic grades G(1) (54.5% and 81.8%) and G(2) (50.0% and 62.5%) gallbladder carcinoma were significantly higher than those in G(3) (28.6% and 35.7%) (P<0.05). The protein expression of p16 and Rb had a negative-correlation in gallbladder carcinoma (r = -0.2993, P<0.05), and this negative-correlation was correlated with Nevin staging (P<0.05). Moreover, the protein expression of p16 and cyclin D1 had a negative-correlation in gallbladder carcinoma (r = -0.9417, P<0.05). CONCLUSION: Cyclin D1 may play a role in the early stage of gallbladder carcinoma. Mutation of p16 and Rb genes might be correlated with progression of gallbladder carcinoma. Analysis of p16 and Rb can estimate the prognosis of gallbladder carcinoma. Expression of p16 and Rb may be correlated with Nevin staging and pathologic grading in gallbladder carcinoma.

Adenoma↗
PubMed2005

Effectiveness of intra-arterial anesthesia for uterine fibroid embolization using dilute lidocaine.

A modified protocol of uterine fibroid embolization (UFE) is proposed for alleviating the postinterventional pain. This randomized and double-blinded clinical trial is to evaluate the effectiveness of intra-arterial infusion of dilute lidocaine for postinterventional pain relief in UFE. Forty-six patients who underwent UFE were randomly grouped equally. In the test group, after the poly(vinyl alcohol) embolization was complete, a dilute lidocaine solution with 40 mg in 6.0 ml, 3.0 ml for each side or 4.0 and 2.0 ml for two sides, was given through the catheter. In the control group, the patients received 6.0 ml of saline solution as a placebo. A simple pain degree classification method for patient self-evaluation was developed. A questionnaire was completed by each patient to record the degree of pain during five periods; these were during the procedure, the first 12 h, the second 12 h, between 24 and 48 h, and between 48 and 72 h. The numbers of patients with the same degree of pain in the five time segments from the two groups were statistically compared. Compared with the control group, the patients in the test group experienced less pain within 48 h after the procedure (p<0.01). The results suggest that this improved UFE protocol is a simple approach to prevent the acute postinterventional pain of UFE.

Adolescent↗
PubMed2005

Polymorphisms in DNA base excision repair genes ADPRT and XRCC1 and risk of lung cancer.

Adenosine diphosphate ribosyl transferase (ADPRT) and X-ray repair cross-complementing 1 (XRCC1) are two major DNA base excision repair (BER) proteins and act interactively in stimulating and executing BER processes. Polymorphisms of ADPRT Val762Ala and XRCC1 Arg399Gln have been associated with altered protein function and BER activity. This case-control study examined the contribution of these two polymorphisms, alone and in combination, or in interaction with smoking, to the risk of developing lung cancer. We estimated the risk of lung cancer associated with these polymorphisms in 1,000 cases and 1,000 cancer-free controls using logistic regression models. Subjects having the ADPRT Ala/Ala genotype had an odds ratio (OR) of 1.68 [95% confidence interval (95% CI), 1.27-2.23] compared with those having the Val/Val genotype. A greater than multiplicative joint effect between the ADPRT polymorphism and smoking was observed. The ORs (95% CI) of the Ala/Ala genotype for nonsmokers and smokers who smoked < or =16, 16 to 28, or >28 pack-years were 1.13 (0.79-1.62), 1.35 (0.68-2.70), 2.46 (1.35-4.51) or 17.09 (8.15-35.83), respectively (P trend test < 0.001). Gene-gene interaction of ADPRT and XRCC1 polymorphisms increased risk of lung cancer in a supermultiplicative manner (OR for the presence of both ADPRT 762Ala/Ala and XRCC1 399Gln/Gln genotypes, 5.91; 95% CI, 2.09-16.72), although the XRCC1 polymorphism itself was not associated with the risk. In conclusion, the ADPRT Val762Ala polymorphism plays an important role in smoking-related lung cancer and the XRCC1 Arg399Gln polymorphism may serve as a risk modifier.

Aged↗
PubMed2005

Gliosis and brain remodeling after treatment of stroke in rats with marrow stromal cells.

The long-term (4-month) responses to treatment of stroke in the older adult rat, using rat bone marrow stromal cells (MSCs), have not been investigated. Retired breeder rats were subjected to middle cerebral artery occlusion (MCAo) alone, or injected intravenously with 3 x 10(6) MSCs, at 7 days after MCAo. Functional recovery was measured using an adhesive-removal patch test and a modified neurological severity score. Bromodeoxyuridine, a cell proliferation marker, was injected daily for 14 before sacrifice. Animals were sacrificed 4 months after stroke. Double immunostaining was used to identify cell proliferation and cell types for axons, astrocytes, microglia, and oligodendrocytes. MSC treatment induced significant improvement in neurological outcome after MCAo compared with control rats. MSC treatment reduced the thickness of the scar wall (P < 0.05) and reduced the numbers of microglia/macrophages within the scar wall (P < 0.01). Double staining showed increased expression of an axonal marker (GAP-43), among reactive astrocytes in the scar boundary zone and in the subventricular zone in the treated rats. Bromodeoxyuridine in cells preferentially colocalized with markers of astrocytes (GFAP) and oligodendrocytes (RIP) in the ipsilateral hemisphere, and gliogenesis was enhanced in the subventricular zone of the rats treated with MSCs. This is the first report to show that MSCs injected at 7 days after stroke improve long-term neurological outcome in older animals. Brain tissue repair is an ongoing process with reactive gliosis, which persists for at least 4 months after stroke. Reactive astrocytes responding to MSC treatment of ischemia may also promote axonal regeneration during long-term recovery.

Animals↗
PubMed2005

Stem/progenitor cells in mouse mammary gland development and breast cancer.

Breast cancer is a genetically and clinically heterogeneous disease. It is unclear whether different target cells contribute to this heterogeneity and which cell types are most susceptible to oncogenesis. Stem cells are speculated to be the cellular origin of at least a subset of human breast cancers. To begin to address these issues, we have isolated and characterized cell populations enriched in normal mammary stem/progenitors and have studied the expression of putative stem/progenitor markers in tumors derived from genetically engineered mice. Specifically, transgenic activation of Wnt signaling in the mammary gland induces tumors comprised of epithelial and myoepithelial cells harboring the same genetic defect implying that the tumor arose from transformation of a bipotent progenitor cell. On the other hand, transgenic activation of Neu signaling induces tumors comprising cells of more limited lineage capacity. Thus, the heterogeneity of different breast cancers may reflect the activation of different oncogenic pathways, different cellular targets in which these genetic changes occur, or both.

Animals↗
PubMed2005

A nonparametric comparison of conditional distributions with nonnegligible cure fractions.

Survival data with nonnegligible cure fractions are commonly encountered in clinical cancer clinical research. Recently, several authors (e.g. Kuk and Chen, Biometrika 79 (1992) 531; Maller and Zhou, Journal of Applied Probability, 30 (1993) 602; Peng and Dear, Biometrics, 56 (2000) 237; Sy and Taylor, Biometrics 56 (2000) 227) have proposed to use semiparametric cure models to analyze such data. Much of the existing work has been emphasized on cure detections and regression techniques. In contrast, this project focuses on the hypothesis testing in the presence of a cure fraction. Specifically, our interest lies in detecting whether there exists survival differences among noncured patients between treatment arms. For this purpose, we investigate the use of a modified Cramér-von Mises statistic for two-sample survival comparisons within the framework of cure models. Such a test has been studied by Tamura et al., (Statistics in Medicine 19, 2000, 2169) using bootstrap procedure. We will focus on developing asymptotic theory and convergent algorithms in this paper. We show that the limiting distributions of the Cramér-von Mises statistic under the null hypothesis can be represented by stochastic integrals and a weighted noncentral chi-squares. Both representations lead to concrete numerical schemes for computing the limiting distributions. The algorithms can be easily implemented for data analysis and significantly reduce computing time compared to the bootstrap approach. For illustrative purposes, we apply the proposed test to a published clinical trial.

Algorithms↗
PubMed2005

Identification of a naturally occurring recombinant isolate of Sugarcane mosaic virus causing maize dwarf mosaic disease.

The complete nucleotide sequence of a potyvirus causing severe maize dwarf mosaic disease in Shaanxi province, northwestern China was determined (GenBank accession No. AY569692). The full genome is 9596 nucleotides in length excluding the 3 '-terminal poly (A) sequence. It contains a large open reading frame (ORF) flanked by a 149 nt 5'-untranslated region (UTR) and a 255 nt 3'-UTR. The putative polyprotein encoded by this large ORF comprises of 3063 amino acid residues. Sequence comparisons and phylogenetic analyses showed that this potyvirus is an isolate of Sugarcane mosaic virus (SCMV). The entire sequences shared identities of 89.6-97.6 % and 79.3-93.3% with 9 sequenced SCMV isolates at the nucleotide and deduced amino acid levels, respectively. But it showed much lower identities with Maize dwarf mosaic virus (MDMV), Sorghum mosaic virus (SrMV) and Johnsongrass mosaic virus (JGMV) isolates. The putative coat protein sequence is identical to that of a Chinese maize isolate SCMV-HZ. However, partition comparisons and phylogenetic profile analyses of the viral nucleotide sequences indicated that it is a recombinant isolate of SCMV. The recombination sites are located within the 6K1 and CI coding regions.

3' Untranslated Regions↗
PubMed2005

vlf-1 deletion brought AcMNPV to defect in nucleocapsid formation.

Recent studies have provided direct evidence that the baculovirus very late factor 1 (VLF-I) of Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) was essential for BV production. To elucidate how vlf-1 deletion blocks BV production we generated a vlf-1 knockout bacmid by ET-recombination technology on AcMNPV bacmid propagated in Escherichia coli. Bacmid DNA transfection and supernatant passage assay revealed that the vlf-1 knockout bacmid was unable to replicate in cell culture, while vlf-1 repair bacmid, which was generated by transposition of the vlf-1 ORF under control of its native promoter into polyhedrin gene locus of vlf-1 knockout bacmid, resumed viral replication ability at wildtype levels. Results of these assays proved the correct construction of the vlf-1 knockout bacmid. Subsequent electron microscopy revealed that the vlf-1 knockout bacmid failed to form nueleocapsid in the nuclei of the transfected cells. Instead, intensely electron-dense virogenic stroma characteristic of viral DNA synthesis were observed. Thus, it is demonstrated for the first time that vlf-1 knockout blocked nucleocapsid formation and the defective nucleocapsid formation resulted in the abolishment of BV and ODV production. Possible roles of vlf-1 in genome processing are suggested and discussed.

Animals↗
PubMed2005

Human bone marrow stromal cell treatment improves neurological functional recovery in EAE mice.

We investigated the treatment of remitting-relapsing experimental autoimmune encephalomyelitis (EAE) in mice with human bone marrow stromal cells (hBMSCs). hBMSCs were injected intravenously into EAE mice upon onset of paresis. Neurological functional tests were scored daily by grading clinical signs (score 0-5). Immunohistochemistry was performed to measure the transplanted hBMSCs, cell proliferation (bromodeoxyuridine, BrdU), oligodendrocyte progenitor cells (NG2), oligodendrocytes (RIP), and brain-derived neurotrophic factor (BDNF). The maximum clinical score and the average clinical scores were significantly decreased in the hBMSC-transplanted mice compared to the phosphate-buffered-saline-treated EAE controls, indicating a significant improvement in function. Demyelination significantly decreased, and BrdU(+) and BDNF(+) cells significantly increased in the hBMSC-treated mice compared to controls. Some BrdU(+) cells were colocalized with NG2(+) and RIP(+) immunostaining. hBMSCs also significantly reduced the numbers of vessels containing inflammatory cell infiltration. These data indicate that hBMSC treatment improved functional recovery after EAE in mice, possibly, via reducing inflammatory infiltrates and demyelination areas, stimulating oligodendrogenesis, and by elevating BDNF expression.

Animals↗
PubMed2005

Cloning and biochemical properties of CDPK gene OsCDPK14 from rice.

A rice CDPK gene, OsCDPK14 (AY144497), was cloned from developing caryopses of rice (Oryza sativa cv. Zhonghua 15). Its cDNA sequence (1922 bp) contains an ORF encoding a 514 amino acids protein (56.7kD, pl 5.18). OsCDPK14 shows the typical structural features of the CDPK family, including a conserved catalytic Ser/Thr kinase domain, an autoinhibitory domain and a CaM-like domain with four putative Ca2+-binding EF hands. Subcellular targeting indicated that OsCDPK14 was located in the cytoplasm, probably due to the absence of myristoylation and palmitoylation motifs. OsCDPK14 was expressed in Escherichia coli and purified from bacterial extracts. The recombinant protein was shown to be a functional protein kinase using Syntide-2, a synthetic peptide. Kinase activity was shown to be Ca2+-dependent, and this activation was strongly enhanced by Mn2+ and inhibited by W7 in vitro. These results provide significant insights into the regulation and biochemical properties of OsCDPK14, suggesting OsCDPK14 may be a signal factor of cytoplasm in rice plant.

Amino Acid Sequence↗
PubMed2005

The role of quantitative structural imaging in the early diagnosis of Alzheimer's disease.

The goal of this article is to review the role of structural neuroimaging in the diagnosis of Alzheimer's disease (AD). We present relevant neuroanatomy, highlight progress in the domain of AD imaging, and review the clinical characteristics of the prodromal phase of AD. We describe the history of the diagnostic issue by examining at cross-section and longitudinally the differences between patients who have AD and normal controls. We also present how subsequent works applied these characteristic traits to the early detection of the prodromal disease and to prediction of future decline. The article delineates the differences between subjects who have mild cognitive impairment and AD, which illustrate the spreading of the pathology with disease progression. The last section describes problems encountered in the differential diagnosis.

Aged↗
PubMed2005

Atorvastatin induction of VEGF and BDNF promotes brain plasticity after stroke in mice.

Molecular mechanisms underlying the role of statins in the induction of brain plasticity and subsequent improvement of neurologic outcome after treatment of stroke have not been adequately investigated. Here, we use both in vivo and in vitro studies to investigate the potential roles of two prominent factors, vascular endothelial growth factor (VEGF) and brain-derived neurotrophic factor (BDNF), in mediating brain plasticity after treatment of stroke with atorvastatin. Treatment of stroke in adult mice with atorvastatin daily for 14 days, starting at 24 hours after MCAO, shows significant improvement in functional recovery compared with control animals. Atorvastatin increases VEGF, VEGFR2 and BDNF expression in the ischemic border. Numbers of migrating neurons, developmental neurons and synaptophysin-positive cells as well as indices of angiogenesis were significantly increased in the atorvastatin treatment group, compared with controls. In addition, atorvastatin significantly increased brain subventricular zone (SVZ) explant cell migration in vitro. Anti-BDNF antibody significantly inhibited atorvastatin-induced SVZ explant cell migration, indicating a prominent role for BDNF in progenitor cell migration. Mouse brain endothelial cell culture expression of BDNF and VEGFR2 was significantly increased in atorvastatin-treated cells compared with control cells. Inhibition of VEGFR2 significantly decreased expression of BDNF in brain endothelial cells. These data indicate that atorvastatin promotes angiogenesis, brain plasticity and enhances functional recovery after stroke. In addition, VEGF, VEGFR2 and BDNF likely contribute to these restorative processes.

Animals↗
PubMed2005

Objective evaluation of skin pressure distribution of graduated elastic compression stockings.

BACKGROUND: The beneficial effects of graduated elastic compression stockings (GCSs) have been demonstrated. However, their pressure performances are variable and unstable in practical applications owing to many influencing factors. Comprehensive assessment of skin pressure profiles may help elucidate the mechanisms of action of compression stockings. OBJECTIVE: The objective of this study was to quantify and objectively evaluate the magnitude and distribution of skin pressure applied by different GCSs and to analyze the possible reasons influencing the stocking pressure performances. METHODS: Six healthy females were required to wear eight kinds of GCSs with different pressure levels while standing upright. The skin pressures of 16 different positions located in four heights and four directions of the lower limb were measured and recorded by FlexiForce interface pressure sensors (Tekscan, Inc., Boston, MA, USA) and a multichannel measuring system. RESULTS: The pressure gradients, pressure levels, and testing locations significantly influenced skin pressure (p < .001). All tested GCSs exerted the highest pressure at the ankle region, and the pressure gradually decreased toward the thigh, which follows the gradient design of GCSs. However, many of them failed to produce the perfect pressure gradients from the ankle region to the calf region. Obviously, reversed pressure gradients occurred in the medial side of the leg, where the pressure at the ankle region was lower than that on the prominent part of the calf by 36% on average. GCSs with higher pressure levels applied higher skin pressure on the lower limb. The pressure at the anterior side was far higher than that in the medial and lateral directions. The distribution patterns of skin pressure at transverse sections were similar to the anatomic outlines of cross sections of the leg. The measured average ankle pressure of all tested GCSs did not reach the pressures specified by the manufacturers. CONCLUSION: Skin pressure distributions and magnitudes applied by GCSs were significantly influenced by the locations of testing points in terms of height and direction, which are determined by the specific anatomic structure and body shape of individual human legs and potentially influenced by the pressure sensor and testing methods.

Adult↗
PubMed2005

Fatty acid desaturases from the microalga Thalassiosira pseudonana.

Analysis of a draft nuclear genome sequence of the diatom Thalassiosira pseudonana revealed the presence of 11 open reading frames showing significant similarity to functionally characterized fatty acid front-end desaturases. The corresponding genes occupy discrete chromosomal locations as determined by comparison with the recently published genome sequence. Phylogenetic analysis showed that two of the T. pseudonana desaturase (Tpdes) sequences grouped with proteobacterial desaturases that lack a fused cytochrome b5 domain. Among the nine remaining gene sequences, temporal expression analysis revealed that seven were expressed in T. pseudonana cells. One of these, TpdesN, was previously characterized as encoding a Delta11-desaturase active on palmitic acid. From the six remaining putative desaturase genes, we report here that three, TpdesI, TpdesO and TpdesK, respectively encode Delta6-, Delta5- and Delta4-desaturases involved in production of the health beneficial polyunsaturated fatty acid DHA (docosahexaenoic acid). Furthermore, we show that one of the remaining genes, TpdesB, encodes a Delta8-sphingolipid desaturase with strong preference for dihydroxylated substrates.

Chromatography, Gas↗
PubMed2005

Identification of an RNA silencing suppressor from a plant double-stranded RNA virus.

RNA silencing is a mechanism which higher plants and animals have evolved to defend against viral infection in addition to regulation of gene expression for growth and development. As a counterdefense, many plant and some animal viruses studied to date encode RNA silencing suppressors (RSS) that interfere with various steps of the silencing pathway. In this study, we report the first identification of an RSS from a plant double-stranded RNA (dsRNA) virus. Pns10, encoded by S10 of Rice dwarf phytoreovirus (RDV), exhibited RSS activity in coinfiltration assays with the reporter green fluorescent protein (GFP) in transgenic Nicotiana benthamiana line 16c carrying GFP. The other gene segments of the RDV genome did not have such a function. Pns10 suppressed local and systemic silencing induced by sense RNA but did not interfere with local and systemic silencing induced by dsRNA. Expression of Pns10 also increased the expression of beta-glucuronidase in transient assays and enhanced Potato virus X pathogenicity in N. benthamiana. Collectively, our results establish Pns10 as an RSS encoded by a plant dsRNA virus and further suggest that Pns10 targets an upstream step of dsRNA formation in the RNA silencing pathway.

Plant Diseases↗