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Biomedical subjects

Liang Li

Publications and source records attributed to Liang Li.

At least 91 records · Page 5Linked to original sources
PubMed2005

Rapid, accurate genotyping of alcohol dehydrogenase-1B and aldehyde dehydrogenase-2 based on the use of denaturing HPLC.

The genotypes of alcohol dehydrogenase-1B (ADH1B) and aldehyde dehydrogenase-2 (ALDH2) are related to alcohol dependence and some human disorders. Rapid, accurate genotyping methodologies for specific polymorphisms of these two genes are needed for molecular screening and testing of alcohol-related problems in populations. A polymerase chain reaction (PCR) composed of two separate amplicons was designed to generate sequences containing the polymorphic site of interest in the ADH1B and ALDH2 genes. The PCR amplicons for each sample were subjected to denaturing high-performance liquid chromatography (DHPLC), analysis performed under partially denaturing conditions as determined by profiling the mixture of a unique homozygous control and a tested sample amplicon. A total of 150 genomic DNA samples were tested to validate this assay by blind analysis. Direct DNA sequencing was performed on samples randomly selected from each of the genotype groups detected by DHPLC profiling. The results indicate 100% concordance between the sequencing analysis and the DHPLC detection. The method we present provides a reliable and fast genotyping procedure for molecular screening of alcohol-related problems.

Alcohol Dehydrogenase↗
PubMed2005

The role of aspirin in the prevention of thrombotic complications of thalidomide and anthracycline-based chemotherapy for multiple myeloma.

OBJECTIVE: To study the efficacy of daily low-dose aspirin (81 mg orally) in decreasing the incidence of venous thromboembolic events (VTEs) in patients with multiple myeloma receiving pegylated doxorubicin, vincristine, and decreased-frequency dexamethasone, plus thalidomide (DVd-T). PATIENTS AND METHODS: In this phase 2 clinical trial of DVd-T, conducted by the Cleveland Clinic Foundation from August 2001 to October 2003, 105 patients were enrolled. The first 35 patients experienced increased numbers of VTEs. von Willebrand levels and platelet aggregation to ristocetin before and after treatment with DVd-T increased significantly, suggesting a pathophysiology involving platelet-endothelial interaction. Aspirin was added to the regimen, thus generating 3 patient groups: group 1 received aspirin from the start of DVd-T treatment before the study began (58 patients), group 2 received aspirin after the start of DVd-T treatment and after the study began (26 patients), and group 3 did not receive daily low-dose aspirin during the study (19 patients). Two patients being treated with warfarin for other indications were excluded from the study. The primary end point for this study was the incidence of VTE in the form of either deep venous thrombosis or pulmonary embolism. Secondary end points were the time to the first VTE, time to the composite end point of death or first VTE, and incidence of bleeding complications. RESULTS: After a median follow-up of 24 months, on an intent-to-treat basis, 26 posttreatment VTEs occurred after a median of 90 days, with 19% occurring in group 1, 15% in group 2, and 58% in group 3. Following multivariate time-to-event analysis, aspirin use continued to be associated with lower relative risk of VTE (hazard ratio, 0.22; confidence interval, 0.10-0.47; P<.001) and of the composite end point (hazard ratio, 0.28; confidence interval, 0.15-0.51; P<.001). CONCLUSION: Daily low-dose aspirin (81 mg orally) given to patients with newly diagnosed and relapsed/refractory multiple myeloma who were receiving DVd-T reduced the incidence of VTEs without an increase in bleeding complications.

Adult↗
PubMed2005

[Influence of different-sized titanium particles loading on osteoblastic differentiation and mineralization].

Studies have recently suggested that the coupling mechanism of bone formation and bone resorption are affected by particulate wear debris inducing aseptic loosening around the bone-prosthesis microenviroment. There may be direct impacts on osteoblasts, resulting in net decrease in bone formation. In addition, the influences of particulate wear debris in different size on the osteogenesis should be various. In order to investigate the hypothesis that particulate wear debris derived from prosthetic biomaterials affects the osteogenesis of osteblasts, we studied the influence of different-sized titanium particles loading on the osteoblastic differentiation by assaying the secretion of alkaline phosphatase (ALP), osteocalcin (OCN), N-terminal type I procollagen (PINP), and on the osteoblastic mineralization with the use of calcified node number, calcified node area and Alizarin Red S (ARS) concentration. Upon in vitro culture in the absence of titanium particles, we observed that cultures of osteoblasts isolated from newborn Japanese rabbits' cranium were excellently capable of differentiation and mineralization. Phi6.9 microm titanium particles did not evidently alter osteoblastic differentiation and mineralization. In comparison, phi2.7 microm and phi0.9 microm titanium particles, especially phi0.9 microm (submicron), significantly suppressed ALP expression, reduced PINP production, decreased OCN secretion and inhibited matrix mineralization. Results of transmission electron microscopy (TEM) of titanium particles-loaded osteoblastic cultures revealed that osteoblasts phagocytized titanium particles and exhibited ultrastructional changes consistent with cellular dysfuction. Combined with our previous studies in vitro findings, these results suggest that particles size play a key role in the process of aseptic loosening, which submicron particles are closely associated with inhibition of bone formation while bigger particles with enhancement of bone resorption. Further understanding the nature of osteoblastic bioreactivity to different-size wear particles should provide additional insights into mechanisms underlying aseptic loosening.

Animals↗
PubMed2005

[Osteogenic potential of bone marrow mesenchymal stem cells from ovariectomied osteoporotic rat].

OBJECTIVE: To investigate the difference of osteogenic potential of bone marrow mesenchymal stem cells (MSCs) between healthy rats and osteoporotic rats. METHODS: We established the animal model of osteoporosis by performing ovariectom on the 3-month-old female Sprague-Dawley rats. Bone marrow mesenchymal stem cells(MSCs) were isolated from the rats of control group and of ovariectomized (ovx) group by means of the density-gradient centrifugation method, and the 3rd-4th passage MSCs were used in all the experiments. The experiments comprised 4 groups: (1) Marrow mesenchymal stem cells control group (MSCs control group); (2) Marrow mesenchymal stem cells ovx group (MSCs ovx group); (3) Osteogenesis induction control group (OSI control group); (4) Osteogenesis induction ovx group (OSI ovx group). Cell cycle and proliferation index (PI) of MSCs were detected by flow cytometry. The expression of alkaline phosphatase (ALP) was detected by dynamics method with substrate of phosphoric acid para-Nitro benzene. The levels of osteocalcin were detected with the isotope labelling method. RESULTS: (1) PI of MSCs was lower in MSCs ovx group than in MSCs control group. (2) The expression of alkaline phosphatase (ALP) was much higher in OSI control group than in the MSCs control group; the expression of alkaline phosphatase (ALP) was much higher in the OSI control group than in OSI ovx group after 7-day and 14-day osteogenic induction. (3) The level of osteocalcin was much higher in the OSI control group than in the MSCs control group after 14-day, 21-day, 28-day osteogenic induction. The level of osteocalcin was much higher in the OSI control group than in the OSI ovx group. CONCLUSION: Both the proliferative potential and the osteogenic potential of bone marrow mesenchymal stem cells (MSCs) from the ovariectomized osteoporotic rat are decreased.

Animals↗
PubMed2005

[Study of the expression profile of immunogenesis associated genes in tuberculosis by microarray].

OBJECTIVE: To explore the difference of gene expression profile in tuberculosis patients. METHODS: mRNA levels of pleural fluid and peripheral blood mononuclear cells (PBMC) in tuberculous pleurisy and lung cancer patients were compared by cDNA microarray. Paired mRNAs from fluid specimens of tuberculosis and lung cancer cases were labeled with different fluorochromes during cDNA probe synthesis in a reverse-transcription reaction. The signal intensity of each spot was measured by laser scanner and gene expression was quantified as the tubercle-to-normal fluorescence ratio (T:N ratio). The gene was defined as over expression when the T:N ratio was greater than 2.0 and under expression when the ratio was less than 0.5. RESULTS: Among 626 immunogenesis associated genes there were 53 differences, of which 31 (tnf-alpha, ig-lambda, il-17, il-17r, hla-dp, lcp1, tcralpha, tcrbeta, hsp75, cxcr4, fyb, hla-g, hla-a, il18bp, il-2r, lt-beta, il-8, ip-10, mcp-1, il-12, il-12r, il-10, canx, irf2, ifn-gamma, tlr, il-1, il-7, tlr, lsp-1, il-14)were higher and 22 (il-4, il-18, il-15, ifg-1, scya14, ablim, peci, ppid, hsf 2, actg2, maoa, ttid, gatm, tgfb3, insr, thbd, trap1, tcrgamma, tcrdelta, il-13r, il-11, igf1, a2m)were lower in tuberculous pleurisy than those in the control. CONCLUSIONS: The immunogenesis of tuberculosis involves multi-genetic expression changes, such as tnf-alpha, il-17, il-12, tcralpha, tcrbeta, hsp75, cxcr4, il-4, il-18, il-15 etc., the expression profile of which changed dramatically. The results provide new insight for understanding of the pathogenic mechanisms of tuberculosis and exploring new therapeutic strategies.

Adult↗
PubMed2005

[Preparation of stationary phases of four beta-cyclodextrin derivatives for gas chromatography by sol-gel technique].

Heptakis (2,3,6-tri-O-ethyl)-beta-cyclodextrin (CD) (perethylated-beta-CD), heptakis (2,3,6-tri-O-propyl)-beta-CD (perpropylated-beta-CD), heptakis (2,3,6-tri-O-octyl)-beta-CD (peroctylated-beta-CD), and (2,6-di-O-benzyl)-beta-CD were used as stationary phases to prepare columns for gas chromatography by sol-gel technique. The method of coating the columns is similar to the dynamic method and the time required was shortened. Chromatographic characteristics such as column efficiency (around 3000 plates/m), column stability and reproducibility (relative standard deviation below 8.5%) were studied. The columns exhibited good separation ability for disubstituted benzene isomers, especially for xylenes and cresols. In addition, the three peralkylated-beta-CD columns offer better selectivity than the (2,6-di-O-benzyl)-beta-CD column.

Chromatography, Micellar Electrokinetic Capillary↗
PubMed2005

[Investigation of dietary fiber intakes and varies in 53 patients with diabetes].

OBJECTIVE: To investigate the intakes of total dietary fiber (TDF), soluble dietary fiber (SDF) and insoluble dietary fiber (IDF) in Subjects With Type 2 Diabetes so as to provide the base for making the adequate intakes of dietary fiber. METHODS: The enzymatic-gravimetric methods for dietary fiber were established on basis of a collaborative study. Dietary intake was measured by means of 3-day food records through weighting and using food pictures. TDF, SDF and IDF were analyzed by enzymatic-gravimetric methods. RESULTS: The reproducibility relative standard deviations for DF ranged from 2.63% to 9.67%. Vegetable foods were the mainly sources of DF. The total dietary intakes, insoluble and soluble fibers were 26.5 +/- 9.8, 14.6 +/- 5.8, 10.4 +/- 4.4 (g/d) respectively. CONCLUSION: The dietary fiber intake of the diabetes remains in the range of intakes recommended by American Diabetes Association.

Aged↗
PubMed2005

[Study on chemical constituents of Lagotis yunnanensis].

OBJECTIVE: To study the chemical constituents of Lagotis yunnanensis W. W. Smith. METHODS: Compounds were isolated from the ethanolic extract of the title herb by silicagel column chromatography and polyamide column chromatography, and their structures were identified by physical and chemical evidences and spectral methods. RESULTS: Six compounds were isolated and identified as quercetin-3-O-beta-D-glucoside (1), apigenin-7-methyl ether (2), E-cinnamic acid (3), Z-cinnamic acid (4), E-p-coumatic acid (5), Z-p-coumatic acid (6). CONCLUSION: All the compounds are isolated from this plant for the first time.

Flavonoids↗
PubMed2004

Changes of adrenomedullin and its receptor components mRNAs expression in the brain stem and hypothalamus-pituitary-adrenal axis of stress-induced hypertensive rats.

In this study, reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the changes in mRNAs levels of preproadrenomedullin (ppADM) gene encoding adrenomedullin (ADM) and the essential receptor components of ADM, calcitonin receptor-like receptor (CRLR), and the receptor activity modifying protein 2 and 3 (RAMP2 and RAMP3) in the medulla oblongata, hypothalamus, midbrain, pituitary gland and adrenal gland of the stress-induced hypertensive rats. It was shown that chronic foot-shock and noise stress for 15 consecutive days induced a significant increase in systolic blood pressure (SBP) and unique changes in ppADM and its receptor components mRNAs in all areas studied. As compared with the control group, the level of ppADM mRNA, normalized against a glyceraldehydes-3-phosphate dehydrogenase (GAPDH) control, was up-regulated in the hypothalamus-pituitary-adrenal (HPA) axis, but down-regulated in the medulla oblongata and midbrain (P<0.01 and P<0.05, respectively). The relative amount of CRLR mRNA was higher in the hypothalamus than that in other areas. The level of CRLR mRNA expression was significantly increased in the medulla oblongata of the stress group (P<0.01), but decreased in the midbrain (P<0.01) as well as hypothalamus(P<0.05), as compared with that of the control group. Chronic stress for 15 consecutive days produced an increase in the level of RAMP2 mRNA expression in the medulla oblongata (P<0.01) and a decrease in the adrenal gland (P<0.01), as compared with the control. No significant stress-related changes in RAMP2 mRNA were observed in the midbrain, hypothalamus and pituitary gland. The amount of RAMP3 mRNA was relatively higher in the midbrain and hypothalamus than that in the medulla oblongata, adrenal gland and adrenal gland. Stress-induced hypertensive rats exhibited an increased RAMP3 mRNA expression in the hypothalamus and pituitary gland (P<0.01 and P<0.05, respectively) and a decrease in the adrenal gland and midbrain (P<0.05). No significant stress-related change in RAMP3 mRAN was observed in the medulla oblongata. Taken together, our results indicate that the significant changes in ppADM and its receptor components mRNAs expression in the HPA axis and autonomic centers may be related to the development of the stress-induced hypertension. Nevertheless, the pathophysiological significance of brain-derived ADM and its receptors in stress and blood pressure regulation and their roles in stress-induced hypertension still await further investigation.

Adrenomedullin↗
PubMed2004

Inhibition of CaMKII-mediated c-FLIP expression sensitizes malignant melanoma cells to TRAIL-induced apoptosis.

TRAIL can induce apoptosis in melanoma cells and thus may offer new hope for melanoma therapy. However, many melanoma cells are resistant to TRAIL. To examine molecular mechanisms in cell resistance, we analyzed TRAIL-induced DISC in TRAIL-sensitive melanoma cells and showed that apoptosis-initiating caspase-8 and caspase-10 were recruited to the DISC where they became activated through autocatalytical cleavage, leading to apoptosis through cleavage of downstream substrates such as caspase-3 and DFF45. In TRAIL-resistant melanoma cells, however, c-FLIP proteins were recruited to the DISC, resulting in the inhibition of caspase-8 and caspase-10 cleavage in the DISC. Both calmodulin-dependent protein kinase II (CaMKII) protein and enzymatic activity were upregulated in resistant cells and CaMKII inhibitor KN-93 downregulated expression of c-FLIP proteins, thus sensitizing resistant cells to TRAIL-induced apoptosis. Transfection of CaMKII cDNA in sensitive melanoma cells resulted in cell resistance to TRAIL, where transfection of CaMKII dominant-negative cDNA in resistant cells restored TRAIL sensitivity in cells. These results indicate that the CaMKII-mediated pathway for c-FLIP upregulation protects melanoma cells from TRAIL-induced apoptosis and targeting this pathway may provide novel therapeutic strategies in treatment of melanomas.

Apoptosis↗
PubMed2004

Bacterial identification by protein mass mapping combined with an experimentally derived protein mass database.

A protein mass mapping approach using mass spectrometry (MS) combined with an experimentally derived protein mass database is presented for rapid and effective identification of bacterial species. A prototype mass database from the protein extracts of nine bacterial species has been created by off-line high-performance liquid chromatography (HPLC) matrix-assisted laser desorption/ionization (MALDI) MS, in which the microbiological parameter of bacterial growth time is considered. A numerical method using a statistical weight factor algorithm is devised for matching the protein masses of an unknown bacterial sample against the database. The sum of these weight factors produces a corresponding summed weight factor score for each bacterial species listed in the database, and the database species producing the highest score represents the identity of the respective unknown bacterium. The applicability and reliability of this protein mass mapping approach has been tested with seven bacterial species in a single-blind study by both direct MALDI MS and HPLC electrospray ionization MS methods, and identification results with 100% accuracy are obtained. Our studies have demonstrated that the protein mass database can be rapidly established and readily adopted with relatively less dependency on experimental factors. Furthermore, it is shown that a number of proteins can be detected using a protein sample amount equivalent to an extract of less than 1000 cells, demonstrating that this protein mass mapping approach can potentially be highly sensitive for rapid bacterial identification.

Bacteria↗
PubMed2004

[The epidemic of childhood tuberculosis in China].

OBJECTIVE: To analyze the epidemic situation of children Tuberculosis (TB) in China. METHODS: To sum up the data of four times national TB epidemic survey from 1979 to 2000, and analyze the epidemic situation of children whose age were between 0 and 14. RESULTS: The TB prevalence rates in children were 8.8%, 9.6%, 7.5% and 9.0% in 1979, 1984/85, 1990, 2000. The active pulmonary TB (PTB) prevalence rates in children were 241.7/100 000 172.1/100 000, 91.8/100 000 in 1979, 1990 and 2000, the bacteriological positive PTB prevalence rates were 12.7/100 000, 12.3/100 000 in 1990 and 2000, the smear positive PTB prevalence rates were 7.5/100 000, 7.5/100 000 and 6.7/100 000 in 1979, 1990 and 2000; It was estimated there were 26.08 million children who were infected by microbacterial TB, 266 thousands children active PTB cases, 36 thousands children bacteriological positive PTB cases and 19 thousands children smear positive PTB cases in 2000 according to the data of the national population survey. the rates were 4.5%, 5.9%, 1.8%, 1.3% when comparing them to the all patients. the ratio of children TB prevalence rates between city and country were 1.8, 1.8, 1.7 and 1.2 in the four survey. CONCLUSIONS: The TB prevalence rates in children had not obvious decrease from 1979 to 2000 were not allowed to optimize to the epidemic of children TB. The bacteriological negative PTB had a bigger. The difference of children TB prevelance between city and country reduced gradually. The quantity of sample and other factors influenced the forecast value of PPD to disease, so it would be a trend of using the routine surveillance to replace the national epidemic survey. BCG still would be the an important content in our national TB control before the emergence of the new and more efficient vaccine.

Adolescent↗
PubMed2004

Hierarchical structure description of spatiotemporal chaos.

We develop a hierarchical structure (HS) analysis for quantitative description of statistical states of spatially extended systems. Examples discussed here include an experimental reaction-diffusion system with Belousov-Zhabotinsky kinetics, the two-dimensional complex Ginzburg-Landau equation, and the modified FitzHugh-Nagumon equation, which all show complex dynamics of spirals and defects. We demonstrate that the spatial-temporal fluctuation fields in the above-mentioned systems all display the HS similarity property originally proposed for the study of fully developed turbulence [Phys. Rev. Lett. 72, 336 (1994)]]. The derived values of a HS parameter beta from experimental and numerical data in various physical regimes exhibit consistent trends and characterize the degree of turbulence in the systems near the transition, and the degree of heterogeneity of multiple disorders far from the transition. It is suggested that the HS analysis offers a useful quantitative description for the complex dynamics of two-dimensional spatiotemporal patterns.

Journal Article↗
PubMed2004

Protein sequencing by mass analysis of polypeptide ladders after controlled protein hydrolysis.

The characterization of protein modifications is essential for the study of protein function using functional genomic and proteomic approaches. However, current techniques are not efficient in determining protein modifications. We report an approach for sequencing proteins and determining modifications with high speed, sensitivity and specificity. We discovered that a protein could be readily acid-hydrolyzed within 1 min by exposure to microwave irradiation to form, predominantly, two series of polypeptide ladders containing either the N- or C-terminal amino acid of the protein, respectively. Mass spectrometric analysis of the hydrolysate produced a simple mass spectrum consisting of peaks exclusively from these polypeptide ladders, allowing direct reading of amino acid sequence and modifications of the protein. As examples, we applied this technique to determine protein phosphorylation sites as well as the sequences and several previously unknown modifications of 28 small proteins isolated from Escherichia coli K12 cells. This technique can potentially be automated for large-scale protein annotation.

Algorithms↗
PubMed2004

A measurement error model with a Poisson distributed surrogate.

We study a linear model in which one of the covariates is measured with error. The surrogate for this covariate is the event count in unit time. We model the event count by a Poisson distribution, the rate of which is the unobserved true covariate. We show that ignoring the measurement error leads to inconsistent estimators of the regression coefficients and propose a set of unbiased estimating equations to correct the bias. The method is computationally simple and does not require using supplemental data as is often the case in other measurement error analyses. No distributional assumption is made for the unobserved covariate. The proposed method is illustrated with an example from the Wisconsin Sleep Cohort Study.

Bias↗