PubMed Health⌕ Search

Biomedical subjects

Hui Li

Publications and source records attributed to Hui Li.

At least 253 records · Page 14Linked to original sources

High glucose levels down-regulate glucose transporter expression that correlates with increased oxidative stress in placental trophoblast cells in vitro.

OBJECTIVE: To study glucose transporter expression and oxidative stress in placental trophoblasts under hyperglycemic conditions in vitro. METHODS: Trophoblasts were isolated from term normal human placentas and incubated with Dulbecco's modified eagle medium containing 1000, 2500, and 4500 mg/L glucose for 3 days. At the end of incubation, culture medium was collected. Trophoblast RNA was extracted and mRNA expression of glucose transporters was determined by RNase protection assay. Messenger RNA expression for copper-zinc-superoxide dismutase (CuZn-SOD) was determined by real-time polymerase chain reaction. Lipid peroxide production was determined by measuring malondialdehyde concentration in the culture supernatant. Protein expression of sodium-glucose transporter 2 (SGLT-2) was determined by Western blot analysis. RESULTS: Messenger RNA expression for glucose transporter 1 (GLUT1) and SGLT-2 were reduced in trophoblast cells incubated with 4500 mg/L glucose compared with those incubated with 1000 and 2000 mg/L glucose. mRNA expression of CuZn-SOD was also decreased in trophoblasts incubated with 4500 mg/L glucose. Malondialdehyde production was significantly increased by trophoblasts incubated with 4500 mg/L glucose compared with those by trophoblasts incubated with 1000 and 2000 mg/L glucose (4.69 +/- 0.60 versus 2.10 +/- 0.29 and 2.89 +/- 0.47 nmol/mg protein; P < .01, respectively). CONCLUSIONS: Down-regulation of gene expression of glucose transporters correlates with increased lipid peroxide production and decreased superoxide dismutase expression in placental trophoblasts cultured under hyperglycemic conditions.

Cells, Cultured↗

Automation of protein purification for structural genomics.

A critical issue in structural genomics, and in structural biology in general, is the availability of high-quality samples. The additional challenge in structural genomics is the need to produce high numbers of proteins with low sequence similarities and poorly characterized or unknown properties. 'Structural-biology-grade' proteins must be generated in a quantity and quality suitable for structure determination experiments using X-ray crystallography or nuclear magnetic resonance (NMR). The choice of protein purification and handling procedures plays a critical role in obtaining high-quality protein samples. The purification procedure must yield a homogeneous protein and must be highly reproducible in order to supply milligram quantities of protein and/or its derivative containing marker atom(s). At the Midwest Center for Structural Genomics we have developed protocols for high-throughput protein purification. These protocols have been implemented on AKTA EXPLORER 3D and AKTA FPLC 3D workstations capable of performing multidimensional chromatography. The automated chromatography has been successfully applied to many soluble proteins of microbial origin. Various MCSG purification strategies, their implementation, and their success rates are discussed in this paper.

Automation↗

Cloning and characterization of chicken adipocyte fatty acid binding protein gene.

Fatty acid binding proteins (FABPs) are members of a superfamily of lipid-binding proteins and occur intracellularly in vertebrates and invertebrates. This study was designed to clone and characterize the adipocyte fatty acid binding protein (A-FABP) gene in the chicken. PCR primers were designed according to mammalian A-FABP gene sequence to amplify partial cDNA of A-FABP gene from chicken adipose tissues, and the full length of the gene was cloned by 5'RACE and 3'RACE. Analysis of sequence showed that the cDNA of the chicken A-FABP gene was 74 and 73% homologous with porcine and human A-FABP gene, respectively. The similarity was 77, 28, and 23% at the predicted amino acid level with human A-FABP, human L-FABP, and human I-FABP, respectively. RT-PCR and Northern blot analysis indicated that the chicken A-FABP gene, similar to that of the mammal, is only expressed in fat tissues. This is the first report to identify and characterize A-FABP gene in the chicken.

Adipocytes↗

Suppression of bcl-2 gene by RNA interference increases chemosensitivity to cisplatin in nasopharyngeal carcinoma cell line CNE1.

To explore the effect of suppressing BCL-2 expression using RNA interference (RNAi) technique in nasopharyngeal carcinoma cell line CNE1. CNE1 cell lines stably expressing shRNAs targeted bcl-2 and GL3 gene were established and gene expression inhibition was assessed by Western blotting analysis. The effect of suppressing bcl-2 by RNAi on cell growth was studied, the apoptosis induction and the sensitization of CNE1 cells to cisplatin were quantified by MTT assays and flow cytometry. The results showed that: stable transfection of CNE1 cells with vectors expressing shRNAs against bcl-2 decreased the expression of BCL-2 protein; suppression of BCL-2 expression did not affect cell proliferation but could increase the chemosensitivity to cisplatin in CNE1 cells. This will help physicians to make some clinical trials of gene therapy on nasopharyngeal carcinoma by RNAi.

Antineoplastic Agents↗

Computerized analysis of mammographic parenchymal patterns for assessing breast cancer risk: effect of ROI size and location.

The long-term goal of our research is to develop computerized radiographic markers for assessing breast density and parenchymal patterns that may be used together with clinical measures for determining the risk of breast cancer and assessing the response to preventive treatment. In our earlier studies, we found that women at high risk tended to have dense breasts with mammographic patterns that were coarse and low in contrast. With our method, computerized texture analysis is performed on a region of interest (ROI) within the mammographic image. In our current study, we investigate the effect of ROI size and ROI location on the computerized texture features obtained from 90 subjects (30 BRCA1/BRCA2 gene-mutation carriers and 60 age-matched women deemed to be at low risk for breast cancer). Mammograms were digitized at 0.1 mm pixel size and various ROI sizes were extracted from different breast regions in the craniocaudal (CC) view. Seventeen features, which characterize the density and texture of the parenchymal patterns, were extracted from the ROIs on these digitized mammograms. Stepwise feature selection and linear discriminant analysis were applied to identify features that differentiate between the low-risk women and the BRCA1/BRCA2 gene-mutation carriers. ROC analysis was used to assess the performance of the features in the task of distinguishing between these two groups. Our results show that there was a statistically significant decrease in the performance of the computerized texture features, as the ROI location was varied from the central region behind the nipple. However, we failed to show a statistically significant decrease in the performance of the computerized texture features with decreasing ROI size for the range studied.

Algorithms↗

Comparison of radiographic texture analysis from computed radiography and bone densitometry systems.

Osteoporosis is a disease that results in an increased risk of bone fracture due to a loss of bone mass and deterioration of bone structure. Bone mineral density (BMD) provides a measure of bone mass and is frequently measured by bone densitometry systems to diagnose osteoporosis. In addition, computerized radiographic texture analysis (RTA) is currently being investigated as a measure of bone structure and as an additional diagnostic predictor of osteoporosis. In this study, we assessed the ability of a peripheral bone densitometry (PD) system to yield images useful for RTA. The benefit of such a system is that it measures BMD by dual-energy x-ray absorptiometry and therefore provides high- and low-energy digital radiographic images. The bone densitometry system investigated was the GE/Lunar PIXI, which provides 512 x 512 digital images of the heel or forearm (0.2 mm pixels). We compared texture features of heel images obtained with this PD system to those obtained on a Fuji computed radiography (CR) system (0.1 mm pixels). Fourier and fractal-based texture features of images from 24 subjects who had both CR and BMD exams were calculated, and correlation between the two systems was analyzed. Fourier-based texture features characterize the magnitude, frequency content, and orientation of the trabecular bone pattern. Good correlation was found between the two modalities for the first moment (FMP) with r=0.71 (p value<0.0001) and for minimum FMP with r=0.52 (p value=0.008). Root-mean-square (RMS) did not correlate with r=0.31 (p value>0.05), while the standard deviation of the RMS did correlate with r=0.79 (p value<0.0001). Good correlation was also found between the two modalities for the fractal-based texture features with r=0.79 (p value<0.0001) for the global Minkowski dimension and r=0.63 (p value=0.0007) for the fractal dimension from a box counting method. The PD system therefore may have the potential for yielding heel images suitable for RTA.

Absorptiometry, Photon↗

Nine mutants of Chlorobium tepidum each unable to synthesize a different chlorosome protein still assemble functional chlorosomes.

Chlorosomes of the green sulfur bacterium Chlorobium tepidum comprise mostly bacteriochlorophyll c (BChl c), small amounts of BChl a, carotenoids, and quinones surrounded by a lipid-protein envelope. These structures contain 10 different protein species (CsmA, CsmB, CsmC, CsmD, CsmE, CsmF, CsmH, CsmI, CsmJ, and CsmX) but contain relatively little total protein compared to other photosynthetic antenna complexes. Except for CsmA, which has been suggested to bind BChl a, the functions of the chlorosome proteins are not known. Nine mutants in which a single csm gene was inactivated were created; these mutants included genes encoding all chlorosome proteins except CsmA. All mutants had BChl c contents similar to that of the wild-type strain and had growth rates indistinguishable from or within approximately 90% (CsmC(-) and CsmJ(-)) of those of the wild-type strain. Chlorosomes isolated from the mutants lacked only the protein whose gene had been inactivated and were generally similar to those from the wild-type strain with respect to size, shape, and BChl c, BChl a, and carotenoid contents. However, chlorosomes from the csmC mutant were about 25% shorter than those from the wild-type strain, and the BChl c absorbance maximum was blue-shifted about 8 nm, indicating that the structure of the BChl c aggregates in these chlorosomes is altered. The results of the present study establish that, except with CsmA, when the known chlorosome proteins are eliminated individually, none of them are essential for the biogenesis, light harvesting, or structural organization of BChl c and BChl a within the chlorosome. These results demonstrate that chlorosomes are remarkably robust structures that can tolerate considerable changes in protein composition.

Bacterial Proteins↗

Retinoid X receptor regulates Nur77/TR3-dependent apoptosis [corrected] by modulating its nuclear export and mitochondrial targeting.

Retinoid X receptor (RXR) plays a central role in the regulation of intracellular receptor signaling pathways by acting as a ubiquitous heterodimerization partner of many nuclear receptors, including the orphan receptor Nur77 (also known as TR3 [corrected] or NGFI-B), which translocates from the nucleus to mitochondria, where it interacts with Bcl-2 to induce apoptosis. Here, we report that RXRalpha is required for nuclear export and mitochondrial targeting of Nur77 through their unique heterodimerization that is mediated by dimerization interfaces located in their DNA-binding domain. The effects of RXRalpha are attributed to a putative nuclear export sequence (NES) present in its carboxyl-terminal region. RXRalpha ligands suppress NES activity by inducing RXRalpha homodimerization or altering RXRalpha/Nur77 heterodimerization. The RXRalpha NES is also silenced by RXRalpha heterodimerization with retinoic acid receptor or vitamin D receptor. Consistently, we were able to show that the mitochondrial targeting of the RXRalpha/Nur77 heterodimer and its induction of apoptosis are potently inhibited by RXR ligands. Together, our results reveal a novel nongenotropic function of RXRalpha and its involvement in the regulation of the Nur77-dependent apoptotic pathway [corrected]

Active Transport, Cell Nucleus↗

Role of EGFR transactivation in preventing apoptosis in Pseudomonas aeruginosa-infected human corneal epithelial cells.

PURPOSE: To determine the role of epidermal growth factor (EGF) receptor (EGFR)-mediated signaling pathways in preventing infection-induced apoptosis in human corneal epithelial cells (HCECs). METHODS: Epithelial monolayers of a telomerase-immortalized HCEC line, HUCL, and primary culture of HCECs were infected with Pseudomonas aeruginosa in the presence of the EGFR inhibitor tyrphostin AG1478, the extracellular signal-regulated kinase (ERK) inhibitor U0126, the phosphoinositide 3-kinase (PI3K) inhibitor LY294002, the heparin-binding EGF-like growth factor (HB-EGF) antagonist CRM197, the HB-EGF neutralizing antibody, or the matrix metalloproteinase inhibitor GM6001. The activation of EGFR was analyzed by immunoprecipitation using EGFR antibodies, followed by Western blot analysis with phosphotyrosine antibody. Phosphorylation of ERK and Akt, a major substrate of PI3K, and generation of cleaved caspase-3 and poly (ADP-ribose) polymerase (PARP) were determined by Western blot analysis. Apoptotic cells were characterized by positive staining of active caspase-3, loss of mitochondrial cytochrome c, and condensation of chromosomes. Apoptosis was also confirmed by measuring caspase-3 activity and assessing the generation of cleaved caspase-3 and PARP. RESULTS: P. aeruginosa infection of HUCL cells resulted in EGFR activation and EGFR-dependent ERK1/2 and PI3K phosphorylation. Inhibition of EGFR, ERK1/2, and PI3K activities with kinase-specific inhibitors (AG1478, U0126, and LY294002, respectively) resulted in an increase in the number of apoptotic cells, in elevated cellular caspase-3 activity, and/or in increased cleaved PARP in P. aeruginosa-infected HUCL cells or primary culture of HCECs. Blocking HB-EGF ectodomain shedding by inhibition of matrix metalloproteinase-mediated proteolysis, downregulation of HB-EGF, or neutralization of its activity retarded infection-induced EGFR transactivation and, as a consequence, increased infection-induced HUCL apoptosis. CONCLUSIONS: Bacterial infection of HCECs induces EGFR transactivation through HB-EGF ectodomain shedding. EGFR and its downstream ERK and PI3K signaling pathways play a role in preventing epithelial apoptosis in the early stage of bacterial infection.

Apoptosis↗

Gene and protein kinase expression profiling of reactive oxygen species-associated lipotoxicity in the pancreatic beta-cell line MIN6.

Oligonucleotide microarrays were used to define oleic acid (OA)-regulated gene expression and proteomic technology to screen protein kinases in MIN6 insulinoma cells. The effects of oxidative stress caused by OA and potential protective effects of N-acetyl-L-cysteine (NAC), a scavenger of reactive oxygen species (ROS), on global gene expression and beta-cell function were investigated. Long-term exposure of MIN6 cells to OA led to a threefold increase in basal insulin secretion, a 50% decrease in insulin content, an inhibition of glucose-stimulated insulin secretion (GSIS), and a twofold increase in the level of ROS. The addition of NAC normalized both the OA-induced insulin content and ROS elevation, but it failed to restore GSIS. Microarray studies and subsequent quantitative PCR analysis showed that OA consistently regulated the expression of 45 genes involved in metabolism, cell growth, signal transduction, transcription, and protein processing. The addition of NAC largely normalized the expression of the OA-regulated genes involved in cell growth and differentiation but not other functions. A protein kinase screen showed that OA regulated the expression and/or phosphorylation levels of kinases involved in stress-response mitogen-activated protein kinase, phosphatidylinositol 3-kinase, and cell cycle control pathways. Importantly, these findings indicate that chronic OA exposure can impair beta-cell function through ROS-dependent and -independent mechanisms.

Acetylcysteine↗

Laboratory diagnosis of four recent sporadic cases of community-acquired SARS, Guangdong Province, China.

Four cases of severe acute respiratory syndrome (SARS) that occurred from December 16, 2003, to January 8, 2004, in the city of Guangzhou, Guangdong Province, China, were investigated. Clinical specimens collected from these patients were tested by provincial and national laboratories in China as well as members of the World Health Organization SARS Reference and Verification Laboratory Network in a collaborative effort to identify and confirm SARS-associated coronavirus (SARS-CoV) infection. Although SARS-CoV was not isolated from any patient, specimens from three patients were positive for viral RNA by reverse transcription-polymerase chain reaction assay, and all patients had detectable rises in SARS-CoV-specific antibodies. This study shows the effectiveness of a collaborative, multilaboratory response to diagnose SARS.

Adult↗

[Sputum analysis in patients with "disharmony of stomach"].

OBJECTIVE: To analyze the amount and inflammatory components of the sputum in patients with "disharmony of stomach", including gastroesophageal reflux disease, peptic ulcer and chronic gastritis. METHODS: Sputum production was induced by inspiration of aerosol of 3.5% hypertonic saline with ultrasonic nebulizer, and the total cell count in the sputum was examined. Sputum smear stained with Gimsa was used in differential counting under light microscope. Bacterial culture in the sputum was performed in the usual way. Peak expiratory flow (PEF) was tested to study the airway responsiveness. RESULTS: The amount of sputum, the total cells and eosinophils in the sputum of the patients with "disharmony of stomach" were higher than those of the control. PEF decreased following sputum induction. These parameters returned to control level after treatment with Chinese herbs. Bacterial culture was negative. CONCLUSION: "Disharmony of stomach" can cause the bronchial inflammation (non-infection) characterized by eosinophil increase.

Adult↗

[Osteogenesis characteristics of cultured rat mesenchymal stem cells under bone induction condition].

OBJECTIVE: To investigate the osteogenesis characteristics of cultured rat mesenchymal stem cells (MSCs) under bone induction condition. METHODS: MSCs were isolated from adult rat by using density gradient separation method. The osteogenic inducers were compounds of Dexone, beta-glycerophosphate sodium and vitamin C. RESULTS: The MSC attachment formed soon after the seeding and grew into colonies with the appearance of fibroblastic cells. The osteogenic inducer with low dose of Dexone could promote the osteogenic differentiation of MSC. In the group of osteogenic inducer with low dose of Dexone, the expression of alkaline phosphatase (ALP) was remarkably increased after one week's induction, and the number of positive cells was (15.1 +/- 2.6), significantly higher than that of the control group (12.0 +/- 3.5) (P < 0.01). The calcified deposits began to appear in the group of osteogenic inducer with low dose of Dexone after one week's induction and was increased remarkably after three weeks, and the number of calcified deposits was (9.0 +/- 1.7), significantly higher than that of the control group (2.0 +/- 1.8) (P < 0.01). CONCLUSION: MSC can differentiate into osteogenesis by osteogenic induction and may be used to provide seed cells for bone tissue engineering.

Alkaline Phosphatase↗

[Expression of BP1 gene in adult acute leukemia].

OBJECTIVE: To explore the expression of beta protein 1 (BP1) gene in adult acute leukemia (AL) and its relationship with acute leukemia. METHODS: Expression of BP1 gene mRNA was detected in 70 adult AL, 10 normal controls and HEL cell line, by reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: No detectable BP1 gene was found in peripheral blood or bone marrow cells of normal controls and 20 acute myeloid leukemia (AML) in complete remission (CR) stage. BP1 gene was highly expressed in HEL cell line, 57% (20/35) of AML and 80% (8/10) of AML-M(5) cases. BP1 gene could not be detected in adult acute lymphoid leukemia. CONCLUSION: BP1 gene was highly expressed in AML. It might be used as a molecular marker of AML.

Acute Disease↗

[Expression of cellular FLICE inhibitory protein (cFLIP) in endometrial adenocarcinoma].

BACKGROUND & OBJECTIVE: Cellular FLICE inhibitory protein (cFLIP) is a new-found member of the inhibitors of apoptosis. It has been reported to be overexpressed in various human cancers. We investigated the expression of cFLIP in endometrial adenocarcinoma and its association with clinicopathological features and proliferating cell nuclear antigen-labeling index (PCNA-LI). METHODS: cFLIP and PCNA-LI were determined in endometrial tissue samples including 42 endometrial adenocarcinoma tissues, 20 normal proliferative endometrial tissues, and 40 hyperplastic tissues with (n=10) or without (n=30) atypia by immunohistochemistry. RESULTS: The positive rates of cFLIP expression in normal proliferative samples of endometrium, hyperplastic samples, and endometrial adenocarcinomas were (55.0+/-11.4)%, (72.5+/-7.1)%, and (83.3+/-5.8)%, respectively. Scoring on the basis of the percentage of positive cells and the intensity of positive immunostaining indicated that the expression level of cFLIP was significantly higher in adenocarcinoma than in normal proliferative endometrium (P< 0.01) and hyperplastic endometrium with or without atypia (P< 0.05);but no significant difference was found between the later two groups. PCNA-LI were (12.01+/-2.07)%,(20.26+/-6.99)%, (27.10+/-3.01)%, and (41.65+/-10.16)%, respectively in the adenocarcinoma groups with different cFLIP levels showed as -, +, ++, +++. Statistical analysis showed that cFLIP expression was significantly associated with PCNA-LI (r=0.7471,P< 0.01). In addition, cFLIP expression was also significantly associated with clinical stage (P< 0.05), the presence of invasion to >1/2 myometrium (P< 0.05) and positive lymph node metastasis (P< 0.01) of endometrial adenocarcinomas. CONCLUSION: Overexpression of cFLIP is tumor specific, which may be a late event in the tumor development of endometrial adenocarcinoma.

Adenocarcinoma↗

Characterization of a new type HPV16 E7 variant isolated from cervical cancer highest incidence area in Hubei Province of China.

AIM: To investigate the variation and biological properties of HPV16 E7 isolated from cervical cancer biopsy samples from highest incidence area in HuBei province of China. METHODS: HVP16 E7 sequences isolated from the cervical cancer biopsies of 10 local patients were amplified, sequenced and compared with prototype E7 gene. Then the variant gene was cloned into different vectors to study the antigenicity, expression and immunogenicity of its protein by Western blot, immunofluorescence and genetic immunization in vitro or in vivo. RESULTS: The results showed that 7 of 10 samples had the same mutations which led to a nonsense mutation at codon 43 of E7 sequence. The truncated E7 protein could be recognized by standard E7 monoclonal antibody in Western blot and expressed in NIH3T3 cells. In the blood sera of mice immunized intramuscularly by the plasmid DNA expressing the variant E7 gene specific E7 antibodies could be detected at week 2, 3, 5 and 6 after inoculation. However, no specific lymphoproliferation after E7 protein stimulation in vitro was detected by MTT colorimetric assay in comparison to the prototype E7 protein. CONCLUSION: HPV16 E7 gene may show variation in China and the variant protein could be expressed and induce host humoral immune response, but could not elicit special cellular-immune response against it. These data might hold the key for future development of HPV16 vaccine in HuBei province of China.

Animals↗

[The effect of different fabrication methods and luting cements on post retention].

OBJECTIVE: This study was to compare the retention of posts fabricated by different methods and cemented with various cements in order to provide a guidance for clinical choice of post fabrication methods and luting cements. METHODS: Ninety human maxillary anterior teeth were sectioned by the cementoenamel junction and post-holes were prepared. All roots were embedded in the center of plastic cylinders and paralleled with the cylinder. All samples were divided into 9 groups randomly and equally. Posts fabricated with different methods were then cemented with different luting cements. Each sample was placed into a specialized jig and mounted on a tensile testing machine with crosshead speed of 5 mm/min. Constant tensile force was applied until the post was dislodged, and the tensile force required to dislodge the cemented post was recorded. RESULTS: The mean retention force of parapost and direct post demonstrated significantly higher than that of indirect post did (P < 0.05), but there was no significant difference between parapost and direct post(P > 0.05). The mean retention of parapost cement demonstrated significantly higher than that of ZPC and HY-Bond cement did (P < 0.05), but there was no significant difference between ZPC and HY-Bond cement (P > 0.05). CONCLUSION: Different fabrication methods and luting cements significantly affect the retention of posts; and there exists an interaction between different fabricating methods and luting cements.

Cementation↗

[Correlation analysis between single nucleotide polymorphism of the leptin receptor intron 8 and fatness traits in chickens].

Leptin receptor plays an important role in leptin functioning signal transduction and it may have direct effects on the deposition of adipose tissues and the body weight, the leptin receptor (OBR) gene, therefore, can be considered as a candidate gene in the study of fat deposition of the chicken. The function of OBR gene has been intensively studied in mammals, but study of OBR gene in the chicken is still rare. In this paper, the NEAU divergent selection broiler lines for abdominal fat were used. Body weight and fatness traits were measured in the sixth generation broiler population of the two lines at 7 week of age. Two pairs of primers for intron 8 of OBR gene were designed according to the database of chicken genomic sequence (Accession No. AF222783). The SNP was detected by DNA sequencing, and PCR-SSCP method was then developed to screen the population. The correlation analysis between the polymorphisms of the intron 8 of OBR gene and growth and fatness traits in the population was carried out using the appropriate statistical model. Two SNPs were found in the population. Those were T500C and G659A. The least square analysis showed that BB genotype birds had significant higher (P < 0.05) abdominal fat weight and percentage of abdominal fat than AA and AB genotype birds, and AA genotype birds had significant lower (P < 0.05) weights of livers than AB and BB genotype birds at the same time. From these results we can putatively drew the conclusion that OBR gene may be a major gene to affect the fatness traits or linked to the major gene, and the two polymorphisms found in OBR gene intron 8 region could be used to select the chicken for low abdominal fat in molecular marker-assisted selection programs.

Adipose Tissue↗