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Biomedical subjects

W Lu

Publications and source records attributed to W Lu.

At least 271 records · Page 15Linked to original sources
PubMed1997

[Reversal of drug resistance in multidrug resistant tumor cells by an oligomer complementary to the MDR1 gene].

OBJECTIVE: To overcome the multidrug resistance (MDR) in tumor cells. METHODS: Human drug resistant cell line KB-8-5 was transfected with a synthetic oligodeoxynucleotide complementary to the 5' end region of MDR1 gene (ODN). In vitro drug sensitivity was measured by MTT assay. Intracellular drug concentration was assessed by flow cytometric analysis and expression of P-glycoprotein (Pgp) was determined by immunohistochemistry method. RESULTS: The administration of ODN for 72 hours increased daunorubicin (DNR) accumulation and decreased Pgp expression in KB-8-5 cells. Incomplete reversal of MDR in the KB-8-5 cells was observed when lipofectin was used to deliver ODN to the cells. Lipofectin enhanced the reversing activity, and approximately 74.43% of the cells lost their resistance to DNR. CONCLUSION: ODN circumvents resistance in the KB-8-5 cells may be ascribed to the reduced expression of Pgp in the cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

[Packed glass capillary column with multi-cores].

The paper describes the preparation of the columns with multi-cores and their plate heights, optimum gas velocity, minimum plate heights (HETP) and corresponding pressure drop (deltaP=Pi-Po) were measured. It is found that HETP increases as core number increase, but column pressure drop (deltaP) decrease with increase of core number. The conclusion is: 1. The column with multi-cores have a better permeability than the conventional packed capillary column. Although its column efficiency is lower than that of the conventional one when packed particles is in the same column size, the comprehensive properties (N/deltaP) are evidently superior than the conventional capillary column. 2. The pressure drop decreasesas the number and diameter of the core in packed capillary column increase. 3. When packed column particle size gets smaller, column efficiency gets higher, but the particle inlay bacomes difficult. The existence of the cores will make the column efficiency get some loss, but it can improve the column permeability and the inlaid geomery. 4. In considering pressure drop, HETP and the particle inlaid condition in column fabrication as a whole, the optimum column type is the packed capillary column with three cores. 5. Ideal column size is: deltad=1-1. 5dp,d=1-2dp,n> or =3, dp=140-250 mesh.

English Abstract↗
PubMed1997

[Study on self-activation of phosphorylated amino acids to form peptides by FTIR].

The self-activation of six phosphorylated amino acids to form peptides was studied in i-propyl alcohol by FTIR. The results indicated that the phosphorylated amino acids could be self-activated to form peptides in alcohol and the FTIR method in the study on the self-activation of phosphorylated amino acids to form peptides can provide useful information for life process.

2-Propanol↗
PubMed1997

[TR-FTIRS study of crystal phase transformation in polyvinylidene fluoride].

The study of polyvinylidene fluoride (PVDF) by time-resolved Fourier transform infrared spectroscopy (TR-FTIRS) was reported. The instantaneous change and process of both alpha-form and beta-form during transformation were studied under the pulse electric field excitation. Transformation of alpha-form to beta-form was indicated by the increasing of the peak at 508cm(-1), the decreasing of the peak at 528cm(-1) and a shift of those peaks. The transient change time was about 5ms. The decreasing of the peak at 528cm(-1) was nonlinear. A hysteresis-like loop was observed, which was related with the biaxially orientated property of PVDF and was in good agreement with its polarizated hysteresis loop.

English Abstract↗
PubMed1997

Effects of lifelong ethanol consumption on cerebellar layer volumes in AA and ANA rats.

Aging and chronic alcohol consumption can cause degenerative changes in the cerebellar cortex. In this study, the effects of aging and lifelong alcohol consumption on cerebellar cortical layer volumes (molecular and granular) and also white matter layer volumes were studied in alcohol-preferring (AA) and nonpreferring (ANA) rats of both sexes. The ethanol-consuming animals (EtOH) had 12% (w/v) ethanol as the only available fluid from 4 to 22 months of age, whereas the young (3 month) and old controls (24 months) had only water to drink. The volumes of molecular, granular, and white matter layers of the cerebellar vermis in folia II, IV, VII, and X were measured by using systematic sampling and a point-counting method. The volumes of the granular and white matter layers showed consistent increase between 3 and 24 months of age, whereas the volume of the molecular layer remained unchanged with increasing age. Individual ethanol intake was measured over a 1-week period at the beginning and at the end of chronic ethanol exposure. Significant (ANOVA, p = 0.000) sex difference was found in the drinking behavior in both lines, with females consuming more alcohol than males (daily ethanol consumption at 22 months of age 3.2 +/- 0.3 vs. 7.1 +/- 0.3 g/kg for AA males and females; 3.2 +/- 0.3 vs. 5.4 +/- 0.4 g/kg for ANA males and females, respectively). The only ethanol-induced effect on the cerebellum was observed in ANA-EtOH females with a 15% reduction in the volumes of the molecular and granular layer in folium II compared with age-matched controls and a significant (p < 0.05, analysis of covariance with ethanol intake as a covariate) line difference in folium II (molecular and granular layers) was observed between ANA-EtOH females and AA-EtOH females. Furthermore, the volume of the molecular layer in folium II was significantly (p < 0.05, analysis of covariance with ethanol intake and body weights as covariates) reduced for ANA-EtOH females, compared with ANA-EtOH males indicating a sex difference in the cerebellar degeneration due to chronic alcohol consumption. Of the three layers studied, the white matter layer was the most resistant layer to the effects caused by chronic alcohol consumption. In view of the fact that AA and ANA rats of both sexes differ regarding the drinking behavior and ethanol metabolism, they provide an important model for further research on ethanol-induced pathological changes in the central nervous system.

Acetaldehyde↗
PubMed1997

Extraction of implicit information in biosignals.

The first part of this paper explains the meaning of implicit information in biosignals. Image reconstruction from projections and ECG inverse problem are two typical examples. In the second part the limitation of conventional ECG inverse problem study is discussed, that is, the excitation propagation process that was not included in inverse study. In the third part a new approach to ECG inverse problem studies is introduced. To verify the new method, we used this method to localize the ventricular preexcitation site with simulated body surface potentials of WPW syndrome. The experimental results show that the inversely recovered preexcitation sites are in close agreement with the true preexcitation site.

Computer Simulation↗
PubMed1997

[Assessing indexes in the ECG data compression].

This paper describes various numerical assessing indexes in evaluating algorithms for the ECG data compression, such as numerical indexes of similarity (CC, RMS, PRD), indexes of error (amplitude error, peak error), efficiency of compression (Compression Ratio, bit rate), computing complexity, and so on. It also involves visual inspection which is more important in assessing algorithms.

Algorithms↗
PubMed1997

[The expression of calponin in Oddi's sphincters and its actions during gallstone formation].

OBJECTIVES: To study on the expression of calponin in an animal model of gallstone disease and investigate the molecular mechanisms of gallstone formation. METHODS: After feeding a high-cholesterol diet to guinea pigs, Oddi's sphincters were disseced on day 30 and day 60 respectively. We used RT-PCR, western-blotting to evaluate expression level of calponin gene. RESULTS: Down-regulation of calponin gene expression was observed in animals with gallstone. The levels of both protein and mRNA expression for calponin on day 30 and day 60 were lower than those of control group with the level from day 60 lower than that from day 60, while myosin expressions were relatively stable. CONCLUSION: Our results indicated that the decrease of calponin could increase the pressure of sphincter of Oddi, aggravate the stasis of bile and promote the gallstone formation.

Animals↗
PubMed1996

Experiments on the transmission of Babesia major and Babesia bigemina by Haemaphysalis punctata.

Experiments on the transmission by Haemaphysalis punctata of three large Babesia strains were carried out. Three Babesia-free batches of laboratory reared H. punctata ticks were infected with two strains of Babesia major, B. major (Xingjiang strain), isolated with adult ticks of H punctata and B. major (Henan strain), isolated with H. longicornis) and a strain of Babesia bigemina by feeding them on the calves infected by inoculation of blood stabilates. H. punctata was shown to be capable of transmitting the B. major strains transovarially. The larvae, nymphs and adults developed from female ticks engorged on the calf infected with B. major (Xingjiang strain) transmitted the pathogen to splenectomised calves with prepatent periods of 15, 11 and 12 days, respectively. The calves infested with larvae and nymphs died of babesiosis with parasitemias of 400 and 710 per 1000 erythrocytes. The calf infested with adult ticks survived babesiosis, but the number of erythrocytes and the amount of haemoglobin were reduced greatly. H. punctata transmitted B. major (Henan strain) in the same way. The prepatent periods of the calves infested with larvae, nymph and adult ticks were 9, 10 and 12 days, respectively. Calves infested with larvae survived, but those infested with nymphal and adult ticks died of babesiosis with parasitemias of 410 and 100 per 1000 erythrocytes, respectively. H. punctata ticks did not transmit the B. bigemina strain to splenectomised calves. There were no clinical symptoms and no parasites were discovered in the blood films during a 2 month observation period after the calves were infested with larval, nymphal and adult ticks derived from female ticks engorged on calves inoculated with B. bigemina.

Animals↗
PubMed1996

Analysis of tamoxifen and its metabolites by on-line capillary electrophoresis-electrospray ionization mass spectrometry employing nonaqueous media containing surfactants.

On-line capillary electrophoresis-electrospray ionization mass spectrometry (CE-ESMS) has been employed for the analysis of metabolites of the anticancer drug tamoxifen. Nonaqueous (methanol) CE electrolyte provided better resolution and detection sensitivity compared to aqueous systems or highly aqueous water-methanol electrolyte mixtures. Nonaqueous methanol also permitted the use of lower ES voltages presumably owing to its lower surface tension, which facilitated droplet breakup. This decreased the tendency to produce electric discharges, thus improving the stability of electrospray conditions. The relative ease of methanol solvent evaporation may contribute to an improved yield of protonated analytes as compared to highly aqueous solutions. Enhanced CE resolution can be at least partially attributed to the improved solubility of analytes in methanol relative to water. Higher solubility implies less aggregation of hydrophobic analytes, thus improving homogeneity in solution. Moreover, electroosmotic flow toward the detector decreased in methanol relative to water. The reduction of this force pushing all analytes through the capillary, but not aiding in separation, implies that other factors such as slight differences in electrophoretic mobilities are more apt to lead to successful separations. Surfactants were employed as nonaqueous CE-ESMS buffer additives. An SDS concentration of 7 mM lowered the ESMS signal response for N-desmethyltamoxifen by a factor of approximately 3. However, separation of tamoxifen metabolites using 7 mM SDS was augmented relative to the unadulterated methanol electrolyte. This enabled the separation of alpha-hydroxytamoxifen and 4-hydroxytamoxifen, which were not resolvable in methanol electrolyte devoid of SDS. The methanol-surfactant electrolyte system has been successfully used to determine metabolites formed after incubation of tamoxifen with mouse hepatocytes.

Animals↗
PubMed1996

Hematotoxicity among Chinese workers heavily exposed to benzene.

Benzene is a well-established hematotoxin. However, reports of its effects on specific blood cells have been somewhat inconsistent and the relative toxicity of benzene metabolites on peripheral blood cells in humans has not been evaluated. We compared hematologic outcomes in a cross-sectional study of 44 workers heavily exposed to benzene (median: 31 parts permillion [ppm] as an 8-hr time-weighted average [TWA] and 44 age and gender-matched unexposed controls from Shanghai, China. All hematologic parameters (total white blood cells [WBC], absolute lymphocyte count, platelets, red blood cells, and hematocrit) were decreased among exposed workers compared to controls, with the exception of the red blood cell mean corpuscular volume (MCV), which was higher among exposed subjects. In a subgroup of workers who were not exposed to more than 31 ppm benzene on any of 5 sampling days (n = 11, median 8 hr TWA = 7.6 ppm, range = 1-20 ppm), only the absolute lymphocyte count was significantly different between exposed workers (mean [sd]1.6 [0.4] x 10(3) mu L) and controls (1.9 [0.4] x l0(3) uL, p = 0.03). Among exposed subjects, a dose response relationship with various measures of current benzene exposure (i.e., personal air monitoring, benzene metabolites in urine) was present only for the total WBC count, the absolute lymphocyte count, and the MCV. Correlations between benzene metabolites and hematologic parameters were generally similar, although hydroquinone was somewhat more strongly associated with a decrease in the absolute lymphocyte count, and catechol was more strongly associated with an increase in MCV. Morphologic review of peripheral blood slides demonstrated an excess of red blood cell abnormalities (i.e., stomatocytes and target cells) only in the most heavily exposed workers, with no differences in granulocyte, lymphocyte, or platelet morphology noted. Although benzene can affect all the major peripheral blood elements, our results support the use of the absolute lymphocyte count as the most sensitive indicator of benzene-induced hematotoxicity.

Adult↗
PubMed1996

BDNF enhances the functional reinnervation of the striatum by grafted fetal dopamine neurons.

Transplantation of fetal dopaminergic neurons to the striatum can ameliorate neurological deficits exhibited by experimental animals and human graft recipients with Parkinson's disease. Recovery, however, is incomplete due to suboptimal survival of grafted cells and limited synaptic integration with the host brain. A number of neurotrophic factors have recently been shown to promote the survival and differentiation of dopamine neurons in vitro. In the present study we examined the effects of one such factor, brain-derived neurotrophic factor (BDNF), on the development of fetal substantia nigra following transplantation to the dopamine-depleted striatum of adult rats. Infusion of BDNF greatly enhanced the reinnervation of the host striatum by the engrafted dopamine neurons, as determined by tyrosine hydroxylase immunostaining, and also increased the effect of the graft on locomotor behavior induced by amphetamine administration. These effects became apparent during the 4-week period of BDNF infusion and persisted for an additional 6 weeks following the termination of BDNF delivery. These findings demonstrate that BDNF exerts a significant effect on the functional reinnervation of the striatum by transplanted fetal dopamine neurons in the rat, and suggest that application of this factor might similarly improve the clinical efficacy of neural transplantation employed in the treatment for Parkinson's disease.

Amphetamine↗
PubMed1996

Comparative immunocytochemical study of MHC class II expression in human donor pancreas and isolated islets.

Expression of major histocompatibility complex (MHC) molecules by pancreatic islets may influence the survival of pancreas or islet grafts in allogeneic recipients. This study compares the presence of MHC class II (HLA-DP, DQ, DX and DR)-positive cells in 27 pancreases and in 10 isolated islet preparations from human donors. Cells expressing MHC class II were present in all tissues examined as histiocytes located in interstitial areas in both the endocrine and nonendocrine components and as endothelial cells in the nonendocrine part. Endocrine, acinar and duct cells were MHC class II negative. In pancreases from donors under the age of 7 years the frequency of MHC class II-positive histiocytes was only one third of that in adults, and they rarely contained MHC class II-positive endothelial cells. The MHC class II-positive histiocytes were further phenotyped as macrophages positive for LCA and acid phosphatase, or dendritic cells negative for the latter markers. Dendritic cells were frequent in adult organs but rare in organs from donors under 7 years of age. In freshly isolated islet preparations from adult donors, less than 1% of the cells were MHC class II positive. These were identified as resident macrophages and dendritic cells. No MHC class II positive cells were encountered in the islet capillaries. The putative role of MHC class II-positive donor cells in allograft rejection suggests that these differences in MHC class II expression influence the immunogenicity of pancreatic and islet grafts in an age-dependent manner.

Adult↗
PubMed1996

Concentration of rare earth elements, As, and Th in human brain and brain tumors, determined by neutron activation analysis.

Toxic elements As and Th, six rare-earth elemental profiles of brain tumor tissues from 16 patients of astrocytomas (grade I-III), and normal human brain tissues of 18 male, age-matched autopsies serving as controls have been studied by radiochemical neutron activation analysis. P-204 [di(2-ethylhexyl) phosphate] extraction chromatography column was used for group separation of rare-earth element (REE) by one step. Compared with the normal brain tissues, the analytical results showed that the concentrations of Th, La, Ce, Gd, and Lu were significantly higher in tumor tissues (P < 0.01 or 0.001). The possible effects of REE on tumor cell were discussed.

Adult↗