Biomedical subjects

Y Shen

Publications and source records attributed to Y Shen.

At least 181 records · Page 10Linked to original sources

PubMed2000

Nuclear assembly of purified Crythecodinium cohnii chromosomes in cell-free extracts of Xenopus laevis eggs.

Incubation of dinoflagellate Crythecodinium cohnii chromosomes in cytoplasmic extracts of unfertilized Xenopus laevis eggs resulted in chromosomes decondensation and recondensation, nuclear envelope assembly, and nuclear reconstitution. Dinoflagellate Crythecodinium cohnii is a kind of primitive eukaryote which possesses numerous permanently condensed chromosomes and discontinuous double-layered nuclear membrane throughout the cell cycle. The assembled nuclei, being surrounded by a continuous double membrane containing nuclear pores and the uniformly dispersed chromatin fibers are morphologically distinguishable from that of Dinoflagellate Crythecodinium cohnii. However, incubation of dinoflagellate Crythecodinium cohnii chromosomes in the extracts from dinoflagellate Crythecodinium cohnii cells does not induce nuclear reconstitution.

Animals↗

PubMed2000

Post-earthquake quality of life and psychological well-being: longitudinal evaluation in a rural community sample in northern China.

This study aims to observe longitudinal change of quality of life (QOL) and psychological well-being in a community sample affected by an earthquake and to examine the relationship between QOL and disaster exposure, post-disaster support and other related variables. The subjects, from two villages at different distances from the epicenter, were assessed using the brief version of the World Health Organization Quality of Life Assessment (WHOQOL-BREF) and three subscales of a symptoms checklist at 3 months (n=335) and 9 months (n=253) after the earthquake, respectively. Exposure to the earthquake was associated with multidimensional impairment in QOL, including physical, psychological and environmental domains at 3 months, and psychological and environmental domains at 9 months. The victims also suffered significantly more psychological distress in terms of depression, somatization and anxiety. At both assessment points the group that experienced lower initial exposure but then received less post-disaster help reported poorer QOL and psychological well-being. The two victim groups also differed significantly in changing trend along time. The group that received more support showed a general improvement in post-disaster well-being from 3 months to 9 months. The results confirm that post-disaster variables could be as important to post-disaster psychosocial outcomes as variables of pre-disaster vulnerability and disaster per se. A comprehensive and prospective assessment of disaster effects is imperative for the better organization of disaster relief programs and psychosocial interventions.

Adolescent↗

PubMed2000

Estrogen enhances uptake of amyloid beta-protein by microglia derived from the human cortex.

In recent years, inflammatory mechanisms have been increasingly appreciated as important steps in the pathology of Alzheimer's disease (AD). There are two pathological defects in AD: chronic inflammation and impaired clearance of amyloid beta-peptide (Abeta). In the periphery, estrogen both increases macrophage phagocytosis and has antiinflammatory effects. If estrogen had a similar effect in the CNS, it could reverse inflammatory defects in AD. Although microglia are a key component of the immune system and help clear Abeta deposits in the AD brain, little is known about the effects of estrogen on CNS microglia. Therefore, we sought to determine the relationship between estrogen treatment and internalization of Abeta by microglia by quantifying the internalization of aggregated Abeta by human cortical microglia. Abeta uptake was found to be dose- and time-dependent in cultured microglia. Increased Abeta uptake was observed at 1.5 and 24 h after addition of aggregated Abeta (50, 100, or 1,000 nM: Abeta), and this uptake was enhanced by pretreatment with estrogen. The expression of estrogen receptor (ER) beta (ER-beta) was also up-regulated by estrogen treatment. Cells cotreated with ICI 182,780, an ER antagonist, showed significantly reduced internalization of Abeta in cultured microglia. These results indicate that microglia express an ER-beta but that the effect of estrogen on enhancing clearance of Abeta may be related to the receptor-independent action of estrogen or to nonclassical ER effects of estrogen. Thus, stimulation of the ER might contribute to the therapeutic action of estrogen in the treatment of AD.

Amyloid beta-Peptides↗

PubMed2000

Optimization of a solid sorbent dynamic personal air sampling method for aldehydes.

A solid sorbent personal dynamic air sampling method for aldehydes using chemisorption with 20 percent (w/w) O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) on Tenax TA has been optimized for several aldehydes. The method for formaldehyde was developed after optimization for valeraldehyde and acrolein. The effects of temperature, intermittent exposure, and flow rate on sampling efficiency were investigated. Vapors of known concentrations were generated in Tedlar gas bags by syringe injection. Aldehyde chemisorption by reaction with 200-mg coated solid sorbent in a Pyrex Tube (7-cm length, 7-mm OD, and 5-mm ID) occurred during dynamic collection with a personal sampling pump operated at 10, 50, or 100 mL/min. The oxime derivatives were 81-87 percent desorbed by shaking with hexane for two minutes or more, resulting in coefficients of variation ranging between 4-7 percent. Aliquots were then injected for gas chromatographic analysis on a nonpolar capillary column with mass spectrometric or 63Ni electron capture detection. Formaldehyde at 8 ppm-hours equivalent to the permissible exposure limit (PEL) concentration was sampled with a recovery of 94 +/- 4 percent at 50.0 +/- 0.5 mL/min. Valeraldehyde and acrolein at their PELs showed no significant differences (P < 0.05) in recoveries at different relative humidities (1 and 90%), temperatures (1, 25, and 40 degrees C), or intermittent sampling protocol. The sampler capacity at 75 percent recovery was at a PFBHA:aldehyde molar ratio of 12:1 at 10.0 +/- 0.1 mL/min, 17:1 at 50.0 +/- 0.5 mL/min, and 26:1 at 100 +/- 1 mL/min.

Adsorption↗

PubMed2000

NF-kappaB/p50 and NF-kappaB/c-Rel differentially regulate the activity of the 3'alphaE-hsl,2 enhancer in normal murine B cells in an activation-dependent manner.

The enhancer complex located 3' to the C(H)alpha gene in the IgH locus (3alphaE) may regulate B cell function through its ability to act as a locus control region. Multiple, functionally relevant NF-kappaB binding sites are located within the 3'alphaE. NF-kappaB subunits, especially p50 and c-Rel, have also been shown to play critical and differential roles in regulating B cell proliferation, Ig secretion, germline C(H) transcription and Ig class switching. Thus, NF-kappaB could regulate B cell function in part through modulation of 3'alphaE activity. In this study we determined whether p50 and/or c-Rel regulate 3'alphaE activity in normal murine B cells and whether this depends on the nature of the B cell activator. For this purpose, we crossed p50- and c-Rel-deficient mice with mice that are transgenic for a 3'alphaE-hsl,2-human beta-globin reporter gene, and established p50(-/-) or c-Rel(-/-) mice homozygous for the enhancer transgene. We show, using optimal stimulating conditions, that p50 selectively augments 3'alpha E-hsl,2 activity in lipopolysaccharide-activated B cells, whereas c-Rel is required for optimal 3'alphaE-hs1,2 induction in B cells activated through CD40.

Animals↗

PubMed2000

Cloning and functional analysis of cDNAs with open reading frames for 300 previously undefined genes expressed in CD34+ hematopoietic stem/progenitor cells.

Three hundred cDNAs containing putatively entire open reading frames (ORFs) for previously undefined genes were obtained from CD34+ hematopoietic stem/progenitor cells (HSPCs), based on EST cataloging, clone sequencing, in silico cloning, and rapid amplification of cDNA ends (RACE). The cDNA sizes ranged from 360 to 3496 bp and their ORFs coded for peptides of 58-752 amino acids. Public database search indicated that 225 cDNAs exhibited sequence similarities to genes identified across a variety of species. Homology analysis led to the recognition of 50 basic structural motifs/domains among these cDNAs. Genomic exon-intron organization could be established in 243 genes by integration of cDNA data with genome sequence information. Interestingly, a new gene named as HSPC070 on 3p was found to share a sequence of 105bp in 3' UTR with RAF gene in reversed transcription orientation. Chromosomal localizations were obtained using electronic mapping for 192 genes and with radiation hybrid (RH) for 38 genes. Macroarray technique was applied to screen the gene expression patterns in five hematopoietic cell lines (NB4, HL60, U937, K562, and Jurkat) and a number of genes with differential expression were found. The resource work has provided a wide range of information useful not only for expression genomics and annotation of genomic DNA sequence, but also for further research on the function of genes involved in hematopoietic development and differentiation.

Alternative Splicing↗

PubMed2000

Multislice helical CT: image temporal resolution.

A multislice helical computed tomography (CT) halfscan (HS) reconstruction algorithm is proposed for cardiac applications. The imaging performances (in terms of the temporal resolution, z-axis resolution, image noise, and image artifacts) of the HS algorithm are compared to the existing algorithms using theoretical models and clinical data. A theoretical model of the temporal resolution performance (in terms of the temporal sensitivity profile) is established for helical CT, in general, i.e., for any number of detector rows and any reconstruction algorithm used. It is concluded that the HS reconstruction results in improved image temporal resolution than the corresponding 180 degrees LI (linear interpolation) reconstruction and is more immune to the inconsistent data problem induced by cardiac motions. The temporal resolution of multislice helical CT with the HS algorithm is comparable to that of single-slice helical CT with the HS algorithm. In practice, the 180 degrees LI and HS-LI algorithms can be used in parallel to generate two image sets from the same scan acquisition, one (180 degrees LI) for improved z-resolution and noises, and the other (HS-LI) for improved image temporal resolution.

Algorithms↗

PubMed2000

Approximate Bayesian evaluation of multiple treatment effects.

We propose an approximate Bayesian method for comparing an experimental treatment to a control based on a randomized clinical trial with multivariate patient outcomes. Overall treatment effect is characterized by a vector of parameters corresponding to effects on the individual patient outcomes. We partition the parameter space into four sets where, respectively, the experimental treatment is superior to the control, the control is superior to the experimental, the two treatments are equivalent, and the treatment effects are discordant. We compute posterior probabilities of the parameter sets by treating an estimator of the parameter vector like a random variable in the Bayesian paradigm. The approximation may be used in any setting where a consistent, asymptotically normal estimator of the parameter vector is available. The method is illustrated by application to a breast cancer data set consisting of multiple time-to-event outcomes with covariates and to count data arising from a cross-classification of response, infection, and treatment in an acute leukemia trial.

Antineoplastic Agents↗

PubMed2000

A perspective on inflammation in Alzheimer's disease.

Although there have been hundreds of recent papers that document a role for innate inflammatory responses in Alzheimer's disease (AD), several global issues and organizational points are still worth emphasizing. These include etiologic versus pathogenic roles for AD inflammation, the potency of AD inflammation, the sources of AD inflammation, and the highly interactive nature of AD inflammatory responses.

Alzheimer Disease↗

PubMed2000

Prolonged dominance of clonally restricted CD4(+) T cells in macaques infected with simian immunodeficiency viruses.

The repertoire of functional CD4(+) T lymphocytes in human immunodeficiency virus type 1-infected individuals remains poorly understood. To explore this issue, we have examined the clonality of CD4(+) T cells in simian immunodeficiency virus (SIV)-infected macaques by assessing T-cell receptor complementarity-determining region 3 (CDR3) profiles and sequences. A dominance of CD4(+) T cells expressing particular CDR3 sequences was identified within certain Vbeta-expressing peripheral blood lymphocyte subpopulations in the infected monkeys. Studies were then done to explore whether these dominant CD4(+) T cells represented expanded antigen-specific cell subpopulations or residual cells remaining in the course of virus-induced CD4(+) T-cell depletion. Sequence analysis revealed that these selected CDR3-bearing CD4(+) T-cell clones emerged soon after infection and dominated the CD4(+) T-cell repertoire for up to 14 months. Moreover, inoculation of chronically infected macaques with autologous SIV-infected cell lines to transiently increase plasma viral loads in the monkeys resulted in the dominance of these selected CDR3-bearing CD4(+) T cells. Both the temporal association of the detection of these clonal cell populations with infection and the dominance of these cell populations following superinfection with SIV suggest that these cells may be SIV specific. Finally, the inoculation of staphylococcal enterotoxin B superantigen into SIV-infected macaques uncovered a polyclonal background underlying the few dominant CDR3-bearing CD4(+) T cells, demonstrating that expandable polyclonal CD4(+) T-cell subpopulations persist in these animals. These results support the notions that a chronic AIDS virus infection can induce clonal expansion, in addition to depletion of CD4(+) T cells, and that some of these clones may be SIV specific.

Animals↗

PubMed2000

Assembly of double-shelled, virus-like particles in transgenic rice plants expressing two major structural proteins of rice dwarf virus.

Rice dwarf virus (RDV) is a double-shelled particle that contains a major capsid protein (P8), a major core protein (P3), several minor core proteins, and viral genomic double-stranded RNA. Coexpression of P8 and P3 in transgenic rice plants resulted in formation of double-shelled, virus-like particles (VLPs) similar to the authentic RDV particles. The VLPs were not detected in transgenic rice plant cells expressing P8 alone. This in vivo result suggests that P8 interacted with P3 and that these two proteins provide the structural integrity required for the formation of VLPs in rice cells independently of other structural proteins, nonstructural proteins, or viral genomic double-stranded RNAs.

Capsid↗

PubMed2000

Seeds induced to germinate rapidly by mentally projected 'qi energy' are apparently genetically altered.

Mentally controlled qi energy can induce crop seeds to sprout and root for several cm within about 20 min. The RAPD method was used to compare treated groups of wheat and pea seeds and their controls using 11 selected primers. Seven primers amplified polymorphisms in wheat seeds and 5 in pea seeds. It was thought preliminarily that qi energy changed the structure of a germination-correlated gene site speeding up expression and advancing it in time.

Germination↗

PubMed2000

beta-amyloid-induced migration of monocytes across human brain endothelial cells involves RAGE and PECAM-1.

In patients with amyloid beta-related cerebrovascular disorders, e.g. , Alzheimer's disease, one finds increased deposition of amyloid peptide (Abeta) and increased presence of monocyte/microglia cells in the brain. However, relatively little is known of the role of Abeta in the trafficking of monocytes across the blood-brain barrier (BBB). Our studies show that interaction of Abeta(1-40) with monolayer of human brain endothelial cells results in augmented adhesion and transendothelial migration of monocytic cells (THP-1 and HL-60) and peripheral blood monocytes. The Abeta-mediated migration of monocytes was inhibited by antibody to Abeta receptor (RAGE) and platelet endothelial cell adhesion molecule (PECAM-1). Additionally, Abeta-induced transendothelial migration of monocytes were inhibited by protein kinase C inhibitor and augmented by phosphatase inhibitor. We conclude that interaction of Abeta with RAGE expressed on brain endothelial cells initiates cellular signaling leading to the transendothelial migration of monocytes. We suggest that increased diapedesis of monocytes across the BBB in response to Abeta present either in the peripheral circulation or in the brain parenchyma may play a role in the pathophysiology of Abeta-related vascular disorder.

Adult↗

PubMed2000

Longitudinal study of earthquake-related PTSD in a randomly selected community sample in north China.

OBJECTIVE: This study longitudinally described rates of posttraumatic stress disorder (PTSD) in two groups with different levels of severity of exposure to an earthquake in North China. The effects of diagnostic criteria on the frequency of detected PTSD were also examined. METHOD: Subjects were randomly sampled in two villages at different distances from the earthquake epicenter. A total of 181 and 157 subjects were assessed at 3 months and 9 months after the earthquake, respectively, for PTSD by using both DSM-IV and DSM-III-R criteria. The brief version of the World Health Organization Quality of Life Assessment and three subscales of the SCL-90-R were also administered at both assessment points. RESULTS: The village with a higher level of initial exposure to the earthquake and a higher level of postearthquake support had a lower frequency of PTSD than the village with a lower level of initial exposure and less postearthquake support. The rate of onset of DSM-IV PTSD within 9 months for the two villages was 19.8% and 30.3%, respectively. In both villages, the rate of onset of earthquake-related PTSD within 9 months was 24.2% by using DSM-IV criteria and 41.4% by using DSM-III-R criteria. The introduction in DSM-IV of a criterion requiring clinically significant distress or impairment in functioning for a diagnosis of PTSD was a major contributor to the lower rate of DSM-IV PTSD. CONCLUSIONS: PTSD may be as prevalent and persistent in disaster victims in China as in those elsewhere. Prompt and effective postdisaster intervention could mitigate the impact of initial exposure and reduce the probability of PTSD occurrence. Caution should be used in comparing rates of postdisaster PTSD identified by using different diagnostic criteria.

Adult↗

PubMed2000

Expression of ERCC1 antisense RNA abrogates gemicitabine-mediated cytotoxic synergism with cisplatin in human colon tumor cells defective in mismatch repair but proficient in nucleotide excision repair.

Gemcitabine, or 2',2'-difluorodeoxycytidine (dFdC) is a new anticancer agent with significant activity against a broad spectrum of tumors either as a single agent or in combination with other active anticancer drugs. Studies in vitro and in vivo have demonstrated that dFdC produces cytotoxic synergism with cisplatin, or cis-diamminedi-choloroplatinum(II) (CDDP); however, the mechanism by which the synergism occurs has not been elucidated. We proposed that the nucleotide excision repair (NER) process, which is responsible for the cellular removal of CDDP-DNA adducts, may be a target for the mechanism of the cytotoxic synergism of dFdC and CDDP. Because the mismatch repair (MMR) pathway is involved in mediating CDDP cytotoxicity, making determination of the role of the NER in the cytotoxic synergism more complicated, and because tumors are often defective in MMR, we selected an NER-proficient, MMR-deficient, CP2.0 human colon carcinoma cell line as a model for this study. By an in vitro repair synthesis assay, we found that dFdC triphosphate (dFdCTP), the active metabolite of dFdC, inhibited the incorporation of [alpha-32P]dATP as well as the incorporation of [alpha-32P]dCTP, suggesting that the repair inhibition by dFdCTP does not result simply from competition for the incorporation site but rather is also due to prevention of chain elongation during the DNA resynthesis process. To determine whether the repair inhibition contributes to the cytotoxic synergism, we examined the effect of the constitutive expression of ERCC1 antisense RNA on the interaction of dFdC and CDDP. CP2.0 cells were transfected with pERCC1/AS, an ERCC1 antisense expression vector; eight hygromycine-resistant clones expressing various levels of the antisense RNA were selected for quantification of and correlation between the repair activity and cytotoxic synergism. The results show that stable expression of ERCC1 antisense RNA down-regulated the level of mRNA and repair activity; the down-regulation of the repair activity significantly correlated with the reduction of the cytotoxic synergism of the two agents. These data provide direct evidence to support the hypothesis that inhibition of the repair of CDDP-induced DNA lesions plays a critical role in dFdC-mediated cytotoxic synergism with CDDP in MMR-deficient tumor cells.

Antineoplastic Agents↗

PubMed2000

The application of CD71 and Hoechst33258 to staining method for sorting fetal nucleated red blood cells in the peripheral blood of pregnant women.

OBJECTIVE: To compare mononuclear cells labeled by CD71 single-staining method with CD71 and Hoechst33258(HO258) double-staining one, and sort nucleated red blood cells (NRBCs) in peripheral blood in pregnant women by use of the latter method. METHODS: Mononuclear cells in umbilical blood and peripheral blood in normal pregnant women and patients with mild or moderate pregnant hypertension syndrome were labeled by erythrocyte specific antibody CD71 and nuclear dye HO258. Furthermore, NRBCs were sorted in combination with the use of flow cytometry. RESULTS: Labeled by CD71 and Hoechst33258 double-staining method, the positive labeling rate of mononuclear cells in umbilical blood and peripheral blood in normal pregnant women and patients with pregnant hypertension syndrome was remarkably lower than that labeled by CD71 single-staining method (t-test, P<0.01). Meanwhile, CD71 and Hoechst33258 double-staining method was successfully used in sorting NRBCs in peripheral blood in pregnant women by flow cytometry. CONCLUSION: CD71 and HO258 double-staining method could exclude mature erythrocytes, thrombocytes and reticulocytes and this improve NRBCs' specific label and sorting purity.

Antigens, CD↗

PubMed2000

[Expression and characterization of two kinds of recombinant snake neurotoxins].

The cDNA encoding the precursor of cobrotoxin was cloned from the venom gland of the Chinese continental cobra (Naja naja atra) by RT-PCR. Its deduced amino acid sequence analysis showed that the mature protein was identical to that identified from the Taiwan cobra (Naja naja atra) by protein sequencing technique. The cDNA encoding the mature protein was then subcloned into the expression vector pMAL-P2. The gene of CM11, which was formed by ligation of the fragments of the synthetic oligonucleotides, was also cloned into the expression vector pMAL-P2. After induction of IPTG, both of the neurotoxins were overexpressed as soluble fusion proteins which were confirmed by SDS-PAGE and western blotting. The expressed fusion proteins was purified by sepharose 6B-amylose affinity chromatography and DEAE-sepharose FF chromatography. Both of the recombinant proteins achieved after digestion by factor Xa showed the in vivo toxicity.

Animals↗

PubMed2000

[Chromosome localization of the dentinogenesis imperfecta type II locus].

OBJECTIVE: To scrutinize the linkage between dentinogenesis imperfecta type II and chromosome 4q21 in a Tianjin-Tanggu family. METHODS: Blood samples were collected from 13 members of the family. DNA was analyzed with 4 short tandem repeat polymorphisms markers UGATA62A11, DSP(P), SPP1 and D4S1563 Y using fluorescence-based PCR. The linkage between four markers on chromosome 4q21 and dentinogenesis imperfecta type II was tested by Lod score analysis. RESULTS: GATA62A11 and DSP(P) suggested linkage and yielded a Lod score of 1.63 at theta =0, and 1.68 at theta =0 by means of the MLINK software, respectively. Genotype and haplotype were acquired. CONCLUSION: The disease gene of the dentinogenesis imperfecta type II family is located on chromosome 4q. The result will be helpful for the further identification of the dentinogenesis imperfecta type II gene.

Chromosome Mapping↗