Biomedical subjects

Jing Liu

Publications and source records attributed to Jing Liu.

At least 163 records · Page 9Linked to original sources

PubMed2005

The extract of huanglian, a medicinal herb, induces cell growth arrest and apoptosis by upregulation of interferon-beta and TNF-alpha in human breast cancer cells.

Huanglian (Coptidis rhizoma), a widely used herb in traditional Chinese medicine, has been shown recently to possess anticancer activities. However, the molecular mechanism underlying the anticancer effect of the herb is poorly understood. Specifically, whether huanglian extract affects the expression of cancer-related genes has not been defined. This study used DNA microarray technology to examine the effect of the herbal extract on expression of the common genes involved in carcinogenesis in two human breast cancer cell lines, the ER-positive MCF-7 and ER-negative MDA-MB-231 cells. Treatment of the cancer cells with huanglian extract markedly inhibited their proliferation in a dose- and time-dependent manner. The growth inhibitory effect was much more profound in MCF-7 cell line than that in MDA-MB-231 cells. DNA microarray assay revealed that treatment with huanglian dramatically increased the mRNA expression of interferon-beta (IFN-beta) and tumor necrosis factor-alpha in MCF-7 cells. Quantitative analysis by real-time PCR or western blotting confirmed the upregulation of the two genes (especially IFN-beta) in MCF-7 cells, but not in MDA-MB-231 cells. Addition of neutralizing antibody against IFN-beta to culture medium markedly inhibited the huanglian-induced antiproliferative effect, confirming the involvement of IFN-beta in the huanglian's effect and also suggesting an autocrine pathway for the action of IFN-beta in this setting. Given that IFN-beta is among the most important anticancer cytokines, the upregulation of this gene by huanglian is, at least in part, responsible for its antiproliferative effect. The results of this study implicate huanglian as a promising herb for chemoprevention and chemotherapy of certain cancers.

Apoptosis↗

PubMed2005

[The characteristics of anti-B-cell malignance cytotoxic T lymphocytic clones induced by lymphoma relative peptides].

OBJECTIVE: To analyze if the cytotoxic T-cell (CTLs) are peptide-special and HLA restrict, and what is the sequence characteristic of TCRbeta genes. METHODS: Using an antigen-specific T-cell expansion system in vitro, the peripheral blood mononuclear cells (PBMCs) from healthy HLA-A0201 positive donor were stimulated by PBMCs and T2 cells loading the IgHV1-QLVQSGAEV nonapeptide or IgHV3-QLVQSGAEV, B-lymphoma-related nonapeptides, as antigen presenting cells (APCs) once a week for four weeks so as to obtain peptide-specific CTLs. PBMCs from non-HLA-A * 0201 positive donors were used as controls. The immunophenotypes of the CTLs (CD3, CD4, or CD8) were identified by flow cytometry. The proportions of CD8 and peptide/tetramer double positive cells were assayed by using peptide/ HLA tetramer method, The IFN-gamma-releasing capacity of the CTLs incubated together with different target cells was assayed by ELISA. The changes of lymphocyte clones were analyzed TCR beta genes were identified by RT-PCR and spectral type method and then sequenced. RESULTS: After four times stimulation, the CD4/CD8 ratio of the cultured cell decreased obviously from 1.43 to 0.10 (P < 0.05), showing a proliferation of CD8(+) CTLs. The frequency of CD8 and IgHV1-QLVQSGAEV/ HLA-A * 0201 tetramer double positive CTLs was 49.83%, significantly higher than that before stimulation (0.04%). The IFN-gamma secretion detected by ELISA indicated that these CTLs were capable of recognizing the target cells in a peptide-specific and MHC-restricted way. Spectral type method showed that the TCRbeta repertoires were skewed in only a few TCR families. CONCLUSION: The peptides derived from IgHV succeeds in generation of peptide-specific CTLs in vitro in a clonality manner. These CTLs are capable of recognizing the target cells in a peptide-specific and MHC-restricted way, Understanding the function of these CTLs and the molecular structures of these TCR identification-related antigen peptides help discover the interaction between the B-cell and T-cell clones.

CD4-CD8 Ratio↗

PubMed2005

Dietary modulation of parathion-induced neurotoxicity in adult and juvenile rats.

Previous studies indicated that dietary glucose (15% in drinking water) could markedly exacerbate the toxicity of parathion in adult rats. The present study evaluated the effect of consumption of the commonly used sweetener, high fructose corn syrup (HFCS), on parathion toxicity in adult and juvenile rats. Animals were given free access to either water or 15% HFCS in drinking water for a total of 10 days and challenged with parathion (6 or 18 mg/kg, s.c., for juveniles or adults, respectively) on the 4th day. Signs of cholinergic toxicity, body weight and chow/fluid intake were recorded daily. Acetylcholinesterase (AChE) activity and immunoreactivity (AChE-IR) in frontal cortex and diaphragm were measured at 2, 4, and 7 days after parathion. As HFCS was associated with significant reduction in chow intake, adult rats were also pair-fed to evaluate the effect of similar reduced chow intake alone on parathion toxicity. The results indicated that the cholinergic toxicity of parathion was significantly increased by HFCS feeding in both age groups. The excess sugar consumption, however, did not significantly affect parathion-induced AChE inhibition in either tissue or either age group. Enzyme immunoreactivity in frontal cortex was generally not affected in either age group while diaphragm AChE-IR was significantly reduced by parathion and HFCS alone in adult animals at 2 and 4 days timepoints, and more so by the combination of sugar feeding and parathion exposure in both age groups. Food restriction alone did not exacerbate parathion toxicity. While the mechanism(s) remains unclear, we conclude that voluntary consumption of the common sweetener HFCS can markedly amplify parathion acute toxicity in both juvenile and adult rats.

Acetylcholinesterase↗

PubMed2005

[The effect of lipoprotein lipase (LPL) polymorphism on plasma LPL concentration and triglyceride].

OBJECTIVE: To study the effect of lipoprotein lipase (LPL)-HindIII and PvuII polymorphisms on preheparin plasma LPL concentration and triglyceride. METHODS: A cross-sectional study was carried out in a general population of Beijing in 1999, using stratified-random sampling method. LPL-HindIII and PvuII polymorphism and preheparin plasma LPL concentration were determined in 670 individuals aged 45 - 64. RESULTS: (1) The frequencies of H1H1, H1H2, and H2H2 genotypes were 0.646, 0.322, and 0.031 respectively; and the frequencies of P1P1, P1P2, and P2P2 genotypes were 0.410, 0.472, and 0.118 respectively. The distribution of genotypes and that of alleles were homogeneous in both sexes. (2) The plasma LPL concentrations of the 12 type heterozygotes (H1H2 and P1P2) and those of the 22 type (H2H2 and P2P2) homozygotes were all higher than that of the 11 type homozygotes (H1H1 and P1P1) (all P < 0.01). And the LPL concentration varied greatly among different individuals of the same genotype. (3) Smoking, alcohol consumption, BMI, and waist level influenced LPL concentration more significantly in the H1H1 and P1P1 homozygotes and P1P2 heterozygotes. Multivariate analysis showed that smoking and obesity were independent influencing factors of serum LPL concentration (both P < 0.01). (4) The prevalence rate of hypertriglyceridemia was significantly different among different genotypes, the 11 type homozygotes having the highest rate, and the 22 type homozygotes having the lowest. In the same genotype, along with the increase of the serum LPL concentration the prevalence of hypertriglyceridemia decreased (P < 0.05). CONCLUSION: LPL-HindIII and PvuII polymorphisms are determinants of plasma LPL concentration. This genetic effect can be modified by some environmental factors, such as smoking and obesity.

Body Mass Index↗

PubMed2005

PKC-{epsilon}-dependent survival signals in diabetic hearts.

Diabetes mellitus is complicated by the development of a primary cardiomyopathy, which contributes to the excess morbidity and mortality of this disorder. The protein kinase C (PKC) family of isozymes plays a key role in the cardiac phenotype expressed during postnatal development and in response to pathological stimuli. Hyperglycemia is an activating signal for cardiac PKC isozymes that modulate a myriad of cell events including cell death and survival. The epsilon-isozyme of the PKC family transmits a powerful survival signal in cardiac muscle cells. Accordingly, to test the hypothesis that endogenous activation of cardiac PKC-epsilon will protect against hyperglycemic cell injury and left ventricular dysfunction, diabetes mellitus was induced using streptozotocin in genetically engineered mice with cardiac-specific expression of the PKC-epsilon translocation activator [psiepsilon-receptors for activated C kinase (psiepsilon-RACK)]. The results demonstrate a striking PKC-epsilon cardioprotective phenotype in diabetic psiepsilon-RACK (epsilon-agonist) mice that is characterized by inhibition of the hyperglycemia apoptosis signal, attenuation of hyperglycemia-mediated oxidative stress, and preservation of parameters of left ventricular pump function. Hearts of diabetic epsilon-agonist mice exhibited selective trafficking of PKC-epsilon to membrane and mitochondrial compartments, phosphorylation/inactivation of the mitochondrial Bad protein, and inhibition of cytochrome c release. We conclude that activation of endogenous PKC-epsilon in hearts of diabetic epsilon-agonist mice promotes the survival phenotype, attenuates markers of oxidative stress, and inhibits the negative inotropic properties of chronic hyperglycemia.

Animals↗

PubMed2005

Neuroprotection by hypoxic preconditioning involves oxidative stress-mediated expression of hypoxia-inducible factor and erythropoietin.

BACKGROUND AND PURPOSE: Hypoxic preconditioning is an endogenous protection against subsequent lethal hypoxia, but the mechanism involved is not understood. Hypoxia is followed by reactive oxygen species (ROS) production and induces hypoxia-inducible factor (HIF) and its downstream factor erythropoietin (Epo), which is associated with neuroprotection. We hypothesized that these endogenous processes may contribute to hypoxic preconditioning. METHODS: We used a mouse neuronal culture model, with 2 hours of hypoxia as preconditioning followed by 15 hours of hypoxic insult, and examined the expression of HIF-1alpha, Epo, and their downstream proteins by Western blotting. Copper/zinc-superoxide dismutase (SOD1) transgenic (Tg) mice were used to detect the effect of ROS. Cell survival and apoptosis were detected by mitogen-activated protein 2 quantification, apoptotic-related DNA fragmentation, and caspase-3 fragmentation. Antisense Epo was used to block endogenously produced Epo. RESULTS: Hypoxic preconditioning was protective in wild-type (Wt) neurons but not in neurons obtained from SOD1 Tg mice. In Wt neurons, HIF-1alpha and Epo expression showed a greater increase after hypoxia compared with Tg neurons and reached a higher level with preconditioned hypoxia, followed by pJak2, pStat5, and nuclear factor kappaB (NF-kappaB) expression. Antisense Epo decreased these downstream proteins and the neuroprotection of hypoxic preconditioning. CONCLUSIONS: Hypoxic preconditioning induces ROS, which may downregulate the threshold for production of HIF-1alpha and Epo expression during subsequent lethal hypoxia, thus exerting neuroprotection through the Jak2-Stat5 and NF-kappaB pathways.

Animals↗

PubMed2005

Surface plasmon fluorescence measurements of human chorionic gonadotrophin: role of antibody orientation in obtaining enhanced sensitivity and limit of detection.

This paper describes the determination of limits of detection (LODs) of interactions between an antigen, human chorionic gonadotrophin (hCG), and antibodies, anti-alpha-hCG and anti-beta-hCG, using a sandwich assay by surface plasmon field-enhanced fluorescence spectroscopy (SPFS). Randomly biotinylated antibodies were adsorbed onto a structured self-assembled monolayer (SAM)-streptavidin matrix, tethered to gold via a SAM consisting of biotinylated thiol molecules interspersed with hydroxyalkanethiol molecules. The influence of the concentration of biotinylated thiol on the binding of biotinylated antibody and its functionality, in terms of its ability to bind to the hCG antigen, was studied. This allowed determination of the optimum biotin-thiol mole fraction in the mixed thiol solution and consequently in the SAM, to maximize binding of hCG of the streptavidin-bound antibody. SPFS studies of the binding of a secondary fluorescently labeled antibody to hCG immobilized on the optimized SAM-streptavidin-antibody layer showed that a LOD of hCG of 2 mIU mL(-1) (4 x 10(-12) mol L(-1)) could be realized. The system was further optimized by using a more oriented and organized surface by adsorbing monobiotinylated Fab-hCG in place of the whole antibody. A LOD of 0.3 mIU mL(-1) (6 x 10(-13) mol L(-1)) was achieved for this system. This work illustrates the importance of antibody orientation, both on the planar surface and in terms of position of binding site, in maximizing sensor sensitivity.

Antibodies↗

PubMed2005

A novel predictive pharmacokinetic/pharmacodynamic model of repolarization prolongation derived from the effects of terfenadine, cisapride and E-4031 in the conscious chronic av node--ablated, His bundle-paced dog.

INTRODUCTION: Terfenadine, cisapride, and E-4031, three drugs that prolong ventricular repolarization, were selected to evaluate the sensitivity of the conscious chronic atrioventricular node--ablated, His bundle-paced Dog for defining drug induced cardiac repolarization prolongation. A novel predictive pharmacokinetic/pharmacodynamic model of repolarization prolongation was generated from these data. METHODS: Three male beagle dogs underwent radiofrequency AV nodal ablation, and placement of a His bundle-pacing lead and programmable pacemaker under anesthesia. Each dog was restrained in a sling for a series of increasing dose infusions of each drug while maintained at a constant heart rate of 80 beats/min. RT interval, a surrogate for QT interval in His bundle-paced dogs, was recorded throughout the experiment. RESULTS: E-4031 induced a statistically significant RT prolongation at the highest three doses. Cisapride resulted in a dose-dependent increase in RT interval, which was statistically significant at the two highest doses. Terfenadine induced a dose-dependent RT interval prolongation with a statistically significant change occurring only at the highest dose. The relationship between drug concentration and RT interval change was described by a sigmoid E(max) model with an effect site. Maximum RT change (E(max)), free drug concentration at half of the maximum effect (EC(50)), and free drug concentration associated with a 10 ms RT prolongation (EC(10 ms)) were estimated. A linear correlation between EC(10 ms) and HERG IC(50) values was identified. DISCUSSION: The conscious dog with His bundle-pacing detects delayed cardiac repolarization related to I(Kr) inhibition, and detects repolarization change induced by drugs with activity at multiple ion channels. A clinically relevant sensitivity and a linear correlation with in vitro HERG data make the conscious His bundle-paced dog a valuable tool for detecting repolarization effect of new chemical entities.

Animals↗

PubMed2005

Gene expression profiles of HeLa Cells impacted by hepatitis C virus non-structural protein NS4B.

By a cDNA array representing 2308 signal transduction-related genes, we studied the expression profiles of HeLa cells stably transfected by Hepatitis C virus nonstructural protein 4B (HCV-NS4B). The alterations of the expression of four genes were confirmed by real-time quantitative RTPCR; and the aldo-keto reductase family 1, member C1 (AKR1C1) enzyme activity was detected in HCV-NS4B transiently transfected HeLa cells and Huh-7, a human hepatoma cell line. Of the 2,308 genes we examined, 34 were up-regulated and 56 were down-regulated. These 90 genes involved oncogenes, tumor suppressors, cell receptors, complements, adhesions, transcription and translation, cytoskeleton and cellular stress. The expression profiling suggested that multiple regulatory pathways were affected by HCV-NS4B directly or indirectly. And since these genes are related to carcinogenesis, host defense system and cell homeostatic mechanism, we can conclude that HCV-NS4B could play some important roles in the pathogenesis mechanism of HCV.

Gene Expression Profiling↗

PubMed2005

The complete genomes and proteomes of 27 Staphylococcus aureus bacteriophages.

Bacteriophages are the most abundant life forms in the biosphere. They play important roles in bacterial ecology, evolution, adaptation to new environments, and pathogenesis of human bacterial infections. Here, we report the complete genomic sequences, and predicted proteins of 27 bacteriophages of the Gram-positive bacterium Staphylococcus aureus. Comparative nucleotide and protein sequence analysis indicates that these phages are a remarkable source of untapped genetic diversity, encoding 2,170 predicted protein-encoding ORFs, of which 1,402 cannot be annotated for structure or function, and 522 are proteins with no similarity to other phage or bacterial sequences. Based on their genome size, organization of their gene map and comparative nucleotide and protein sequence analysis, the S. aureus phages can be organized into three groups. Comparison of their gene maps reveals extensive genome mosaicism, hinting to a large reservoir of unidentified S. aureus phage genes. Among the phages in the largest size class (178-214 kbp) that we characterized is phage Twort, the first discovered bacteriophage (responsible for the Twort-D'Herelle effect). These phage genomes offer an exciting opportunity to discern molecular mechanisms of phage evolution and diversity.

Chromosome Mapping↗

PubMed2005

[Efficacy of anti-HIV treatment and drug-resistance mutations in some parts of China].

OBJECTIVE: To evaluate the Virologic and Immunologic efficacy of HAART on Chinese HIV/AIDS patients and to assess the impact of of HAART on drug resistance mutations. METHODS: Three cohorts of Liaoning, Jilin and Henan province received three different regimens for 6 months respectively. Regimen of Liaoning cohort comprised Efavirenz + Indinavir (EFV + IDV), regimen of Jilin cohort comprised Stavudine + Didanosine + Efavirenz (d4T + ddI + EFV) and regimen of Henan cohort comprised Stavudine + Didanosine + Nevirapine (d4T + ddI + NVP). Viral load, CD4(+) T cell count and drug resistance genotype were detected on the three cohorts before and after treatment. Partial HIV-1 pol genes encoding protease and 1 - 220 amino acid of reverse transcriptase were amplified by RT-PCR and then automatically sequenced. All sequences were compared with the data of Stanford HIV Drug Resistance Database to assess resistance mutations against reverse transcriptase inhibitors (RTIs) and protease inhibitors (PIs). RESULTS: During observation of 6 months, viral suppression to undetectable level and Elevated CD4(+)T cell count efficacy were achieved on partial Chinese HIV/AIDS patients in each of the three different regimens, even in some patients with rather low CD4(+)T cell count baseline. Before HAART, no primary mutations against PIs and RTIs were detected on the three cohorts, except one patient in Liaoning cohort. But after HAART, drug resistance mutations against RTIs occurred on each of the three cohorts. K103N is the most common mutation against NNRTIs, which can cause high-level resistance to each of the available NNRTIs. Y181C is another common mutation occurred in Henan cohort, which causes crossing drug resistance and multi-drug resistance to NNRTIs. In addition, intermediate level and low level resistance against NRTIs caused by K65R and L74V can also be found, but less commonly. CONCLUSION: Treatment naive Chinese HIV/AIDS patients were sensitive to HAART. Expected virologic and immunologic efficacy of HAART were achieved on Chinese HIV/AIDS patients, but after the introduce of HAART, the high prevalence of drug resistance mutations against NNRTIs and NRTIs, crossing drug resistance and multi-drug resistance reminded us to pay more attention to the drug resistance mutations detection, treatment standardization, and to avoid drugs wasting and prevent the prevalence of drug resistance strains.

Adult↗

PubMed2005

Effect of operation-synchronizing transfusion of apoptotic spleen cells from donor rats on acute rejection of recipient rats after liver transplantation.

AIM: To study effect of operation-synchronizing transfusion of apoptotic spleen cells from donor rats on acute rejection of recipient rats after liver transplantation. METHODS: Two of Wistar rats were chosen randomly for normal liver pathology control and ten of SD rats chosen randomly for liver function control as blank group (no operation). The rest of Wistar and SD rats were divided into four groups: control group (only liver transplantation), Dex group (donors receiving intraperitoneal injection of dexamethasone), SpC group (recipients receiving infusion of spleen cells of donors), Dex-SpC group (recipients receiving infusion of apoptotic spleen cells of donors), with each group except blank group, containing 10 SD rats and 10 Wistar rats, respectively. Wistar rats received liver transplantation from SD rats, in the meantime they received infusion of spleen cells of donors, which were induced by an intraperitoneal injection of dexamethasone (3 mg/(d.kg).b.w) for three days before liver transplantation. The serum alanine transaminase (ALT), total bilirubin (T bili), liver pathological changes and survival time were analysed. Statistical analysis was carried out using SPSS 10.0 for Windows. Differences of the parametric data of ALT in means were examined by one-way ANOVA. Differences of ALT between two groups were examined by LSD. Differences of the nonparametric data of T bili in means and scores of pathology classification for acute rejection were examined by Kruskal-Willis H test. The correlations between ALT and T bili were analysed by Bivariate. Kaplan-Meier curves were used to demonstrate survival distribution. The log-rank test was used to compare the survival data. RESULTS: There were significant differences in ALT of the five groups (F = 23.164 P = 0.000), and ALT in Dex-SpC group was significantly higher than that in blank control, control, Dex, and SpC groups (P = 0.000), and ALT in SpC group was significantly higher than that in blank control (P = 0.000), control (P = 0.004), and Dex groups (P = 0.02). Results of nonparametric analysis of T bili showed that there were differences in T bili of the five groups (chi(2) = 33.265 P = 0.000). T bili in Dex-SpC group was significantly higher than that in blank control, control, Dex, and SpC groups. T bili in SpC group was higher than that in blank control, control, and Dex groups. There were significant differences in scores of pathology classification for acute rejection in each of the groups (chi(2) = 25.933,P = 0.000). The pathologically more serious acute rejection was found in Dex-SPC group than in other groups. No sign of acute rejection was observed in the blank control group. Slight acute rejection was observed in the control group. Slight-moderate acute rejection was observed in the Dex group. Moderate-acute rejection was observed in the SpC group. Severe-acute rejection was observed in the Dex-SpC group. The survival time in Dex-SpC group was shorter than in other groups (statistic = 11.13, P = 0.011). ALT and T bili were positively correlated (r = 0.747, P = 0.000, two-tailed). CONCLUSION: In order to reduce quantity of blood loss from rats after liver transplantation, only one of ALT or T bili is needed for liver function measurement of rats. Simultaneous injection of apoptotic spleen cells from donors induced by dexamethasone to liver transplantation rats aggravates acute rejection. One important mechanism of aggravation of acute rejection may be that apoptotic cells are not removed in time and that dead cells including apoptotic cells release inflammatory factors.

Acute Disease↗

PubMed2005

Lack of evidence for association between the serotonin transporter gene (SLC6A4) polymorphisms and autism in the Chinese trios.

Serotonin regulates several aspects of brain development, and it is involved in a range of behaviors frequently disturbed in autistic disorder. The serotonin transporter is a critical component of the serotonergic system. The serotonin transporter gene (SLC6A4) is of special interest given the nature of the biological findings and the reported effects of selective serotonin reuptake inhibitors of autistic symptoms. So far the genetics researches of the SLC6A4 gene have given conflicting results. The aim of study was to investigate the association between the SLC6A4 gene and autism in the Chinese Han population. The present study was conducted with the detection of three single nucleotide polymorphisms (SNP(S)) located within the SLC6A4 gene by using the polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP) analysis. We performed a family-based association study of these polymorphisms in 175 Chinese Han family trios. Linkage disequilibrium (LD) measurement (D') analysis showed the presence of LD between markers across the locus. No significant evidence of association was found at any of the markers detected by using the transmission disequilibrium test (TDT) and haplotype analyses in all samples and male samples. Our findings suggest that it is unlikely that DNA variations in the SLC6A4 gene play a significant role in the genetic predisposition to autism in the Chinese Han population or that allelic heterogeneity at the SLC6A4 loci dilutes potential disease-allele association.

Asian People↗

PubMed2005

Comparative carboxylesterase activities in infant and adult liver and their in vitro sensitivity to chlorpyrifos oxon.

Maturational expression of carboxylesterase activity in laboratory animals has been correlated with age-related differences in sensitivity to many organophosphorus insecticides including chlorpyrifos. Little information is available, however, on the maturational expression of liver carboxylesterases in humans. Human liver carboxylesterase activity was compared in tissues from infants (2-24 months) and adults (20-36 years). There was no significant difference between mean infant and adult carboxylesterase activities. The carboxylesterase activity rank order was: 2 months<3 months<20 years<24 months<4 months<36 years<21 years<8 months<34 years<35 years. Proteins (3 microg) were separated and blotted using antibodies against rat hydrolase S (HS), human carboxylesterase (HCE) types 1 and 2, and CYP3A4. Again, there were no significant differences in staining density between infant and adult tissues with any isozyme. Aliquots of each sample were pre-incubated (30 min, 37 degrees C) with chlorpyrifos oxon to evaluate in vitro sensitivity. Based on 95% confidence intervals, no significant differences in IC50 values were obtained in 3-month to 36-year samples (range: 1.42-2.12 nM), while the IC50 was significantly lower in the 2-month sample (0.45 nM). Carboxylesterase activity across samples was correlated with cytochrome b5 content and HS immunosignal but not with other microsomal activities (total cyt P450 content, testosterone hydroxylation, coumarin hydroxylation, and EROD). The results suggest that, in contrast to rodents, human liver carboxylesterase expression changes relatively little during postnatal maturation.

Adult↗

PubMed2005

Possible mechanism underlying the antiherpetic activity of a proteoglycan isolated from the mycelia of Ganoderma lucidum in vitro.

GLPG (Ganoderma lucidum proteoglycan) was a bioactive fraction obtained by the liquid fermentation of the mycelia of Ganoderma lucidum, EtOH precipitation, and DEAE-cellulose column chromatography.GLPG was a proteoglycan with a carbohydrate: protein ratio of 10.4: 1. Its antiviral activities against herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) were investigated using a cytopathic inhibition assay. GLPG inhibited cell death in a dose-dependent manner in HSV-infected cells. In addition, it had no cytotoxic effect even at 2 mg/ml. In order to study the mode of action of the antiviral activity of GLPG, cells were treated with GLPG before, during, and after infection, and viral titer in the supernatant of cell culture 48 h post-infection was determined using a TCID((50)) assay. The antiviral effects of GLPG were more remarkable before viral treatment than after treatment. Although the precise mechanism has yet to be defined, our work suggests that GLPG inhibits viral replication by interfering with the early events of viral adsorption and entry into target cells. Thus, this proteoglycan appears to be a candidate anti-HSV agent.

Animals↗

PubMed2005

Purification and application of C-terminally truncated hepatitis C virus E1 proteins expressed in Escherichia coli.

AIM: To explore the possibility of expressing hepatitis C virus (HCV) envelope protein 1 (E1) in Escherichia coli (E. coli) and to test the purified recombinant E1 proteins for clinical and research applications. METHODS: C-terminally truncated E1 fragments were expressed in E. coli as hexa-histidine-tagged fusion proteins. The expression products were purified under denaturing conditions using immobilized-metal affinity chromatography. Purified E1 proteins were used to immunize rabbits. Rabbit anti-sera thus obtained were reacted with both E. coli- and mammalian cell-expressed E1 glycoproteins as detected by Western blot. RESULTS: Full-length E1 protein proved difficult to express in E. coli. C-terminally truncated E1 was successfully expressed in E. coli as hexa-histidine-tagged recombinant fusion protein and was purified under denaturing conditions on Ni(2+)-NTA agarose. Rabbit anti-sera raised against purified recombinant E1 specifically reacted with mammalian cell-expressed E1 glycoproteins in Western blot. Furthermore, E. coli-derived E1 protein was able to detect animal antibodies elicited by E1-based DNA immunization. CONCLUSION: These results demonstrate that the prokaryotically expressed E1 proteins share identical epitopes with eukaryotically expressed E1 glycoprotein. The E. coli-derived E1 proteins and corresponding antisera can become useful tools in anti-HCV vaccine research.

Animals↗

PubMed2005

Effect of sulfur dioxide hydrates on cell cycle, sister chromatid exchange, and micronuclei in barley.

The effects of sulfur dioxide (SO(2)) hydrates exposure on cell cycle, sister chromatid exchange (SCE), and micronuclei (MN) were investigated in barley (Hordeum vulgare) roots. A mixture of sodium bisulfite and sodium sulfite (1:3), at various concentrations from 1x10(-5) to 3x10(-2)M, was used for the treatments. The results showed that the mixture induced the formation of SCE and MN in barley root cells with different effective concentrations and with different trends as treatment concentrations increased. At high concentrations of 0.5-30.0mM, SO(2) hydrates inhibited the mitotic activity and the growth of barley roots by cell cycle delay and cell death, but at 0.1mM, the chemicals slightly stimulated mitotic activity and root growth. These remarkable effects in causing DNA damage and consequent chromosome damage suggest that SO(2) is genotoxic agent and its genotoxicity may influence the mitotic activity and plant growth under SO(2) stress.

Cell Cycle↗

PubMed2005

Correlation between speed perception and neural activity in the middle temporal visual area.

We conducted electrophysiological recording and microstimulation experiments to test the hypothesis that the middle temporal visual area (MT) plays a direct role in perception of the speed of moving visual stimuli. We trained rhesus monkeys on a speed discrimination task in which monkeys chose the faster speed of two moving random dot patterns presented simultaneously in spatially segregated apertures. In electrophysiological experiments, we analyzed the activity of speed-tuned MT neurons and multiunit clusters during the discrimination task. Neural activity was correlated with the monkeys' behavioral choices on a trial-to-trial basis (choice probability), and the correlation was predicted by the speed-tuning properties of each unit. In microstimulation experiments, we activated clusters of MT neurons with homogeneous speed-tuning properties during the same speed discrimination task. In one monkey, microstimulation biased speed judgments toward the preferred speed of the stimulated neurons. Together, evidence from these two experiments suggests that MT neurons play a direct role in the perception of visual speed. Comparison of psychometric and neurometric thresholds revealed that single and multineuronal signals were, on average, considerably less sensitive than were the monkeys perceptually, suggesting that signals must be pooled across neurons to account for performance.

Action Potentials↗