Biomedical subjects

L Lei

Publications and source records attributed to L Lei.

At least 19 recordsLinked to original sources

PubMed2003

Developmental biology meets with reproductive engineering; interdisciplinary science area as a breakthrough.

It has been postulated many times that different scientific topics and strategies often encounter each other, which create cutting edge research field resulting in further significant progresses of science. This was also a lesson bestowed by Prof. Raymond Wegmann where he created innovative research field for biology, molecular biology and biochemistry-biophysics. Progresses of developmental biology were boosted by molecular biology and reproductive engineering where ES cells and embryonic manipulation are necessary. There are no questions about the utility of their technologies. Reviews on their contributions with respect to the condition of genome manipulation are addressed.

Animals↗

PubMed2002

Simulation program for wastewater coagulation.

The lack of comprehensive simulation models for wastewater coagulation is one of the obstacles to achieving optimal coagulant dosing. Two approaches for developing a model to describe the coagulation process are presented. The comprehensiveness in describing the influent quality with several parameters, rather than with one parameter, is identified to give high efficiency in dosing models based on algorithms constructed using the partial least squares method. The concept was tested on two full-scale wastewater treatment plants, with coagulant savings and effluent quality improvements. Significant differences were observed with the increase of online parameters in the models. The second approach is based on distribution of coagulant for particle and phosphate removal processes and is discussed for inert fractions. The concept is integrated into existing simulation software as a module. The calibration results and dosage predictions are demonstrated.

Calibration↗

PubMed2001

Molecular cloning, genetic mapping, and expression analysis of four zebrafish c/ebp genes.

The CCAAT/enhancer binding protein family (C/EBP) are transcription factors that play integral roles in the development and function of many organ systems, including hematopoietic cells, adipose tissues, and liver. We have identified and characterized putative zebrafish orthologs of mammalian C/EBP alpha, beta, gamma, and delta using low-stringency hybridization screening and computer searches of the GenBank EST database. c/ebpa and g were mapped within 1 cM of each other on linkage group (LG) 7, syntenic with human CEBPA and G genes on chromosome 19. c/ebpb was mapped to LG8, and c/ebpd was mapped to LG24, on the same LG as a recently identified unique c/ebp in zebrafish, c/ebp1. The mapping of these genes established new syntenic relationships between LG8 and human chromosome 20, extended existing synteny between LG7 and human chromosome 19, and confirmed the synteny between LG24 and human chromosome 8. In addition, these syntenies between zebrafish and human chromosomes are also conserved in the mouse genome. To characterize the expression of these genes, RNA in situ hybridization in embryos of wild type and a hematopoietic mutant, cloche, was performed. The results showed that zebrafish c/ebpa, b, g, and d were expressed in many embryonic tissues. c/ebpa and b were expressed in a subset of hematopoietic cells in a region consistent with myeloid expression. In addition, there was expression of c/ebpa and b in the liver and c/ebpa, b, and d in regions of the gastrointestinal tract. The expression of the c/ebps may serve as important markers for analysis of myelopoiesis, hepatic development, and other developmental processes in the future.

Amino Acid Sequence↗

PubMed2001

Intercalation and controlled release of pharmaceutically active compounds from a layered double hydroxide.

A series of pharmaceutically active compounds including diclofenac, gemfibrozil, ibuprofen, naproxen, 2-propylpentanoic acid, 4-biphenylacetic acid and tolfenamic acid can be reversibly intercalated into a layered double hydroxide, initial studies suggest that these materials may have application as the basis of a novel tuneable drug delivery system.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2001

A single nucleotide polymorphism in the matrix metalloproteinase-1 promoter enhances lung cancer susceptibility.

Extracellular matrix-degrading matrix metalloproteinase-1 (MMP-1) is one of the interstitial collagenases likely to be involved in tumor invasion and metastasis. MMP-1 may also contribute to tumor initiation and development by altering the cellular microenvironment that facilitates tumor formation. Recent studies have found that overexpression of MMP-1 is associated with the initial stages of cancer development in addition to promoting cellular invasion; however, preexisting oncogenic mutations or chemical carcinogens are required to initiate tumorigenesis as well. There is a single nucleotide polymorphism located in the promoter region of MMP-1 that partially regulates gene expression. The 2G/2G genotype enhances transcriptional activity and may be associated with an increased lung cancer risk. Using a case-control study, we tested the hypotheses that (a) individuals with the 2G/2G genotype may be at an increased risk for lung cancer; and (b) the risk should be greatly elevated in smoking individuals. PCR-RFLP was used to determine the MMP-1 genotypes in 456 lung-cancer cases and 451 frequency-matched controls of Caucasian ethnicity. Overall, there was a significant association between the 2G/2G genotype and lung cancer risk [odds ratio (OR), 1.76; 95% confidence interval (CI), 1.29-2.39]. In current smokers, the lung cancer risk associated with the 2G/2G genotype was significantly elevated (OR, 3.16; 95% CI, 1.87-5.35). However, this association was less evident in former smokers (OR, 1.23; 95% CI, 0.81-1.87) and absent in never smokers (OR, 1.09; 95% CI, 0.31-3.91). Similarly, this risk was more evident in heavy smokers (OR, 2.55; 95% CI, 1.61-4.03) than in light smokers (OR, 1.40; 95% CI, 0.84-2.32). Interestingly, men were observed to have a 2.15-fold increased lung cancer risk (OR, 2.15; 95% CI, 1.42-3.26) compared with women (OR, 1.34; 95% CI, 0.84-2.15). Furthermore, subjects with 2G/2G genotype developed lung cancer earlier (60.94 +/- 0.64 years old) than patients with 1G/1G and 1G/2G genotypes (62.91 +/- 0.59 years old; P = 0.024). Our data demonstrate that the 2G/2G genotype enhances lung cancer susceptibility especially in current smokers. To our knowledge, these results report the first molecular epidemiological evidence of the MMP-1 promoter polymorphism associated with the development of lung cancer in the presence of continuing carcinogenic exposure.

Age Factors↗

PubMed2001

Preparative isolation and purification of acteoside and 2'-acetyl acteoside from Cistanches salsa (C.A. Mey.) G. Beck by high-speed counter-current chromatography.

High-speed counter-current chromatography (HSCCC) was applied to the separation and purification of phenylethanoid glycosides (PhGs) acteoside and 2'-acetylacteoside from Cistanches salsa (C.A. Mey) G. Beck with a quaternary two-phase solvent system composed of ethyl acetate-n-butanol-ethanol-water (4:0.6:0.6:5, v/v). HPLC analyses of the CCC fractions revealed that the two main PhGs were over 98% purity. Their chemical structures were identified by 1H NMR, 13C NMR and MS.

Chromatography, High Pressure Liquid↗

PubMed2001

Modulation of nucleotide excision repair capacity by XPD polymorphisms in lung cancer patients.

Sequence variations have been identified in a number of DNA repair genes, including XPD, but the effect of these polymorphisms on DNA repair capacity (DRC) is uncertain. We therefore examined XPD polymorphisms at Lys751Gln and Asp312Asn in 341 white lung cancer cases and 360 age-, sex-, ethnicity-, and smoking-matched controls accrued in a hospital-based molecular epidemiological study of susceptibility markers for lung cancer. As previously reported, DRC was statistically significantly lower in the cases than in the controls (7.8% versus 9.5%; P < 0.001), which represents an average 18% reduction among the cases. The variant Lys751Gln and Asp312Asn allele frequencies were 0.36 and 0.29, respectively, for the cases and 0.33 and 0.27, respectively, for the controls. For subjects homozygous for the variant genotype at either locus, the adjusted odds ratio [95% confidence interval (CI)] was 1.84 (1.11-3.04; P = 0.018, for trend). Both cases and controls with the wild-type genotypes exhibited the most proficient DRC. The risk (95% CI) for suboptimal DRC (defined as less than the median DRC value among the controls) was 1.57 (0.74-3.35) for those with the Gln/Gln751 genotype. For cases with the Asn/Asn312 genotype, the risk (95% CI) was 3.50 (1.06-11.59). For cases who were homozygous at either locus, the risk was 2.29 (1.03-5.12; P = 0.048, for trend). The pattern was less evident among the controls, although there was a nonsignificant 41% increase in the risk of suboptimal DRC for controls who were homozygous at either locus. These results suggest that the two XPD polymorphisms have a modulating effect on DRC, especially in the cases.

Case-Control Studies↗

PubMed2001

On the degradability of printing and dyeing wastewater by wet air oxidation.

A modified first-order kinetics model was used to study the wet air oxidation of printing and dyeing wastewater. The model simulations are in good agreement with experimental data. The results indicate that a certain fraction of organic pollutants in the printing and dyeing wastewater could not be removed even at elevated temperature and prolonged reaction time. The ratio of degradable organic matter is found independent of temperature and can be improved by using a catalyst.

Catalysis↗

PubMed2001

Construction and application of phenytoin anion-selective electrode based on bulk acoustic wave (BAW) sensing technique.

This paper describes the construction of an anion-selective bulk acoustic wave (BAW) sensor for the direct determination of phenytoin sodium for the first time. Based on the sensitive mass response of a piezoelectric quartz crystal (PQC) and selective adsorption-desorption across the modified film, the BAW sensor was fabricated by coating a polyvinylchloride (PVC) film containing activator on one side of a PQC. The method was found to be sensitive, rapid and easy to handle without pretreatment of the sample. The logarithm of the frequency shift of the PQC shows a linear relationship to the logarithm of the concentration of phenytoin over the range 6.7 x 10(-8)-8.0 x 10(-4) M with a detection limit of 1.0 x 10(-8) M at pH 10.0. Recoveries were in the range 98.5-102.0%. Influencing factors were examined and optimized. Also discussed is the preliminary application of the phenytoin BAW sensor in serum and injection. The results for real samples obtained by the proposed method agreed with those obtained by conventional methods.

Anions↗

PubMed2001

mKlf7, a potential transcriptional regulator of TrkA nerve growth factor receptor expression in sensory and sympathetic neurons.

Development of the nervous system relies on stringent regulation of genes that are crucial to this process. TrkA, the receptor for nerve growth factor (NGF), is tightly regulated during embryonic development and is essential for the survival and differentiation of neural crest-derived sensory and sympathetic neurons. We have previously identified a mouse TrkA enhancer and have characterized several cis regulatory elements that are important for appropriate TrkA expression in vivo. We now report the cloning of a novel gene encoding a Kruppel-like factor from a mouse dorsal root ganglion expression library. This Kruppel-like factor, named mKlf7, binds specifically to an Ikaros core binding element that is crucial for in vivo TrkA enhancer function. Using in situ hybridization, we demonstrate that mKlf7 is coexpressed with TrkA in sensory and sympathetic neurons during embryogenesis and in adulthood. These data are consistent with the idea that mKlf7 may directly regulate TrkA gene expression in the peripheral nervous system.

Amino Acid Sequence↗

PubMed2001

Induction of interleukin-8 in human neutrophils after MHC class II cross-linking with superantigens.

Neutrophils have been shown to express major histocompatibility complex class II (MHC II) after stimulation. However, reports concerning the functional effect of MCH II expression are still lacking. In our hands, granulocyte-monocyte colony-stimulating factor (GM-CSF) alone and in combination with interferon (IFN)-gamma, but not IFN-gamma or interleukin (IL)-3, induced a significant level of expression of human leukocyte antigen DR on neutrophils. The addition of staphylococcal enterotoxin E to neutrophils resulted in a significant increase in IL-8 production only after prestimulation with GM-CSF alone or in combination with IFN-gamma but had no effect on neutrophils preincubated with IFN-gamma alone or IL-3. Staphylococcal enterotoxin A, another bivalent superantigen, also stimulated production of IL-8 by preincubated polymorphonuclear neutrophils, whereas staphylococcal enterotoxin A mutants that are not able to cross-link MHC II molecules failed to induce IL-8 production. Taken together, our results clearly demonstrate that after induction of MHC II, neutrophils are able to respond to MHC II-specific stimulation. These findings support the ideas that the induced MHC II complex is completely functional and that neutrophils may be able to present antigens.

Enterotoxins↗

PubMed2001

Degradation of polyvinyl alcohol (PVA) by homogeneous and heterogeneous photocatalysis applied to the photochemically enhanced Fenton reaction.

The reaction mechanism of the oxidative degradation of polyvinyl alcohol (PVA) by the photochemically enhanced Fenton reaction was studied using a homogeneous (Fe2+(aq) + H2O2) and a heterogeneous reaction system (iron(III)-exchanged zeolite Y+ H2O2). In the homogeneous Fenton system, efficient degradation was observed in a batch reactor, equipped with a medium pressure mercury arc in a Pyrex envelope and employing 80% of the stoichiometric amount of H2O2 required for the total oxidation of PVA and a concentration ratio as low as I mole of iron(II) sulfate per 20 moles of PVA sub-units (C2H40). Model PVA polymers of three different molecular weights (15,000, 49,000 and 100,000 g mol(-1)) were found to follow identical degradation patterns. Strong experimental evidence supports the formation of supermacromolecules (MW: 1-5 x 10(6) g/mol) consisting of oxidized PVA and trapped iron(III) at an early reaction stage. Low molecular weight intermediates, such as oxalic acid, formic acid or formaldehyde were not found during PVA degradation in the homogeneous Fenton system, and we may deduce that the manifold of degradation reactions is mainly taking place within the super-macromolecules from which CO2 is directly released. However, in the heterogeneous Fenton system, the reaction behavior was found to be distinctly different: a decrease of the molecular weights of all three tested monodisperse PVA samples was observed by the broadening of the GPC-traces during irradiation, and oxalic acid was formed. The results lead to the mechanistic hypothesis that during the heterogeneous Fenton process, the cleavage of the PVA-chains may occur at random positions, the reactive centres being located inside the iron(III)-doped zeolite Y photocatalysts.

Hydrogen Peroxide↗

PubMed2001

Histochemical study of transmyocardial laser channels in dogs.

OBJECTIVE: Laser-induced myocardial injury was investigated in a canine transmyocardial laser revascularization model. METHODS: A total of 23 channels were created in the left ventricles of 5 animals with a CO2 laser. Four animals were sacrificed immediately and one at week 2. Lactate dehydrogenase and succinate dehydrogenase in channel regions were examined with a Nitro-BT method staining. RESULTS: Immediately after the procedure, laser channels and surrounding injured myocardium could be stratified from the center to the border into 5 concentric zones, i.e., vaporized zone, carbonized zone, enzyme-disappeared zone, enzyme-decreased zone and enzyme-concentrated zone. Two weeks later, the phenomenon disappeared. CONCLUSIONS: Immediately after transmyocardial revascularization, there is a ring of enzyme-concentrated zone at the outermost region of injured myocardium. Two weeks later, enzyme activities of reversibly injured myocytes appear to have recovered.

Animals↗

PubMed2001

[Distribution of beta-actin within hair cells in the chick: comparatived with those in the guinea pig cochleae].

OBJECTIVE: To study the distribution of beta-actin in the chicken and guinea pig cochlea hair cells. METHOD: beta-actin immunoreactivity was observed by immunohistochemistry. RESULT: beta-actin was located in stereocilia of hair cells and cytoplasm of marginal epithelium cells which tectorial membrane attached in basilar papilla; In the corti's organ beta-actin was present in three row outer hair cells cytoplasm and the phalangeal process and cytoplasm of the tunnel cells. CONCLUSION: There is a common cytoskeletal protein beta-actin in the chick and guinea pig cochleae, but the distribution of beta-actin in two species are different significantly.

Actins↗

PubMed2001

[Separation of echinacoside by reversed-phase preparative high performance liquid chromatography].

Echinacoside, one kind of phenylethanoid glycosides (PhGs), was isolated from the stems of Cistanche tubulosa (Schenk) R. Wight with a series of steps, including solvent extraction, D101 polymer adsorption column separation, Sephadex LH-20 separation, C18 column reversed-phase preparative high performance liquid chromatographic (RP-prep-HPLC) preparation and polyamide thin-layer chromatographic detection. The purity of the product was over 98%. The chemical structure of echinacoside was identified by 1H NMR and 13C NMR. To find out the optimum condition of mobile phase of RP-prep-HPLC, several systems were used in this work. Finally acetonitrile-1% HCOOH water (18:82, V/V) system was found to be the best. On the other hand D101 polymer adsorption column and Sephadex LH-20 were also effective for PhGs separation.

Chromatography, High Pressure Liquid↗

PubMed2001

[Metabolic regulation of phenylethanoid glycosides from Herba cistanches in dogs' gastrointestine].

AIM: To study the metabolic process of phenylethanoid glycosides (PhGs) in the gastrointestine of beagle dogs that were administered intragastrially process, and develop some new methods of biopharmacology on the effective position of traditional Chinese medicine. METHODS: High-performance liquid chromatography was used to purify constituents from faeces and analyze relative contents of the three main compounds in the gastrointestinal tract at different times and in the faeces of dogs. Every sample was collected, extracted with methanol and analyzed with integration. RESULTS: Four compounds, based on reference substances, were identified as echinacoside, acteoside, isoacteoside, and 2'-acetylacteoside from extraction of faces of dogs. Quantitative "with HPLC" analysis reveals that variation of ratios of the three main compounds is not distinct when moving in the gastrointestinal tract 7 h, that is quite different from those in faeces, in which the content of echinacoside fell from 48.0% to 16.0%, and acteoside increased from 11.0% to 34.7%. CONCLUSION: PhGs are mainly metabolized in large intestine. Among them, a portion of echinacoside is transformed into aceteoside.

Animals↗

PubMed2001

[Biochemical remodeling of myocardial collagen and its relation to cardiac renin-angiotensin system in rats after myocardial infarction].

OBJECTIVE: This study aimed at the biochemical remodeling of myocardial collagen and its relation to cardiac renin-angiotensin system (RAS) after myocardial infarction(MI). METHODS: The ventricular and plasma angiotensin II (Ang II) content, total collagen content, and collagen concentration in left ventricle(LV) and right ventricle(RV) of MI and sham-operated control(SOC) rats on 3, 15 and 42 days after operation were measured dynamically by means of radioimmunoassay etc. RESULTS: The plasma Ang II content increased only in MI rats on day 3. The Ang II content in LV of the MI group increased markedly on day 3 after MI as compared with that of the SOC group. It sustained at this higher level on the 15th and 42th days, and the similar changes were observed in RV as well. The biochemical remodeling of collagen in LV and RV occurred after MI and the remodeling of collagen showed similar patterns with its Ang II content, except that collagen remodeling in RV was delayed than the change of Ang II content. CONCLUSION: The cardiac RAS was obviously activated after MI. Ventricular Ang II might play an important role in the biochemical remodeling of myocardial collagen, and its role was independent of circulating RAS.

Angiotensin II↗

PubMed2001

[Beta-actin changes during hair cell regeneration in the chick basilar papilla].

OBJECTIVE: To investigate the changes of beta-actin and beta-actin mRNA expression during hair cell regeneration in the chick basilar papilla(BP) following gentamicin ototoxicity. METHODS: Thirty-six chicks were given muscular injection of gentamicin at dosage of 100 mg/kg.d for 10 consecutive days, and twelve additional chicks received injection of normal saline instead of gentamicin as controls. At 1, 3, 7, 14, 21 and 28 days after the treatment, six chicks in experimental group and two chicks in control group were sacrificed. Basilar papillas were prepared for immunohistochemistry and in situ hybridization study. beta-actin and beta-actin mRNA expression in the damaged region were histologically analyzed by computer image system. RESULTS: beta-actin immunoreactivity of BP changed significantly after treatment with gentamicin. From the first day to the fourteenth day after gentamincin, beta-actin immunoreactivity turned positive gradually. It approximated the normal response level at the fourteenth day after treatment of gentamincin. Then increasing rate of beta-actin immunoreactivity positive response level slowed from the fourteenth day after the treatment. At seventh day after treatment, beta-actin mRNA expression in BP increased to peak value, which preceded the peak expression of beta-actin in the regenerated hair cells. CONCLUSION: Nascent hair cells seem to mature 14 days after hair cell damage, which may play a role in auditory functional recovery.

Actins↗