Biomedical subjects

Fei Zou

Publications and source records attributed to Fei Zou.

At least 37 records · Page 2Linked to original sources

PubMed2005

Improving quantitative trait loci mapping resolution in experimental crosses by the use of genotypically selected samples.

One of the key factors contributing to the success of a quantitative trait locus (QTL) mapping experiment is the precision with which QTL positions can be estimated. We show, using simulations, that QTL mapping precision for an experimental cross can be increased by the use of a genotypically selected sample of individuals rather than an unselected sample of the same size. Selection is performed using a previously described method that optimizes the complementarity of the crossover sites within the sample. Although the increase in precision is accompanied by a decrease in QTL detection power at markers distant from QTL, only a modest increase in marker density is needed to obtain equivalent power over the whole map. Selected samples also show a slight reduction in the number of false-positive QTL. We find that two features of selected samples independently contribute to these effects: an increase in the number of crossover sites and increased evenness in crossover spacing. We provide an empirical formula for crossover enrichment in selected samples that is useful in experimental design and data analysis. For QTL studies in which the phenotyping is more of a limiting factor than the generation of individuals and the scoring of genotypes, selective sampling is an attractive strategy for increasing genome-wide QTL map resolution.

Chromosome Mapping↗

PubMed2005

[Effect of hypoxia on the viability of rat brain astrocytes in vitro].

OBJECTIVE: To investigate the effect of hypoxia on the viability of rat brain astrocytes in vitro and determine the optimal duration of hypoxic treatment for studying the biological behavior of the in vitro cultured cells in response to hypoxia. METHODS: Rat astrocytes were cultured and identified by glial fibrillary acidic protein (GFAP) immunofluorescent staining. After incubation with 5%; CO(2)+95%; N(2) for different time to induce hypoxia, the cells were harvested and observed microscopically for morphological changes and counting of the dead cells. The culture media of the cells were also collected and pO(2), concentrations of glucose and lactate as well as lactate dehydrogenase (LDH) activity were analyzed. RESULTS: As the hypoxia prolonged, the astrocytes appeared swollen and floating in the medium with some becoming necrotic. Compared with the cells in the control group, the changes in the number of necrotic cells, concentrations of glucose and lactate, and LDH activity in the cells of the hypoxic group were significantly different after 10 h of hypoxia (P<0.05). However, the flat and polygonal morphology of the astrocytes almost remained unchanged after 8 h of hypoxia in spite of significant changes in the concentrations of glucose and lactate and LDH activity. CONCLUSION: Hypoxia induced injury and necrosis of rat brain astrocytes in vitro, and 8 h of hypoxia can be the optimal time point for studying the biological behaviors of the cells in response to hypoxia.

Animals↗

PubMed2005

[Study of genes that differentially expressed in eosinophils of patients with asthma by suppression subtractive hybridization technology].

OBJECTIVE: To study genes that differentially expressed in peripheral blood eosinophils of patient with asthmatic. METHODS: Total RNA extracted from eosinophils of patient at the time of exacerbation was taken as the tester and the total RNA from eosinophils of the same patient after improvement as driver. The ds cDNA was synthesized by SMART PCR cDNA Synthesis technology. The differentially expressed genes were obtained by suppression subtractive hybridization (SSH) technology and were further identified by Southern blot. RESULTS: Twelve differentially expressed genes including transformation growth factor beta activated kinase like (TAK1L) protein, cGMP gated channel protein were obtained. CONCLUSION: Increased expression of these genes were involved in the regulation of proinflammatory response, signal transduction, energy metabolism and cell apoptosis, which may help to clarify the molecular mechanism of eosinophils in asthma and may provide the theoretical base for finding out the new medicines towards eosinophils.

Asthma↗

PubMed2005

[Mechanism of Ca2+ on the hyperthermia-induced apoptosis of rat hippocampal neurons in vitro].

OBJECTIVE: To study the mechanism of Ca(2+) on the apoptosis induced by hyperthermia in neonate rat hippocampal neurons to provide the applicative evidence of dantrolene for preventing brain injuries. METHODS: Dantrolene, Ca(2+) specific blocking agent, was used in the hyperthermia-induced apoptosis of primary hippocampal neurons in vitro to observe its effect on the apoptosis, fluorescent intensity, and dynamic change of Ca(2+) by flowcytometry and laser confocal microscopy. RESULTS: The rate of apoptosis was decreased significantly after hyperthermia treatment by dantrolene sodium. The intracellular Ca(2+) fluorescent intensity in 42 degrees C treatment group (107.35 +/- 6.0) was significantly lower than that in control group (159.12 +/- 33.8). The concentration of Ca(2+) began to decrease 20 approximately 25 s after adding dantrolene sodium, and reached the lowest level about 50 s later, and then kept lower than the basal level. CONCLUSION: Dantrolene sodium has an important protective effect on hippocampal neurons apoptosis induced by hyperthermia and may have some applicative value of preventing heat-induced brain injury.

Animals↗

PubMed2005

[Differentiation of neonatal rat striatal neural stem cells induced by all-trans retinoic acid].

OBJECTIVE: To investigate the role of all-trans retinoic acid (atRA) in inducing differentiation of neonatal rat striatal neural stem cells (NSCs). METHODS: Neonatal rat striatal NSCs were obtained by mechanical isolation and serum-free culture. The roles of atRA at different concentrations in inducing the differentiation of NSCs were observed by immunofluorescent cytochemical staining, and the expression of retinoic acid receptor (RAR) gene was determined by semi-quantitative RT-PCR. RESULTS: atRA could dose-dependently accelerate the differentiation of NSCs into neuron-like cells, and the physiological concentration of atRA was optimal for inducing NSC differentiation. atRA could induce the expression of RARbeta mRNA in a dose- and time-dependent manner. CONCLUSION: atRA can accelerate differentiation of NSCs into neuron-likes cells and up-regulate the expression of RAR-beta mRNA in neonatal rat striatal NSCs.

Animals↗

PubMed2005

[Effect of doxofylline on calcium-activated potassium channels in human peripheral blood eosinophils in asthma].

OBJECTIVE: To study the effects of doxofylline on calcium-activated potassium (K(Ca)) channels of human peripheral blood eosinophils in asthma. METHODS: Peripheral blood eosinophils from patients with asthma were isolated and divided equally into two groups, a control group and a doxofylline incubated group. The data were recorded using cell-attached configuration of patch-clamp technique and the kinetic changes of K(Ca) channels activated by 0.2 micromol/L platelet activating factor (PAF) were compared. RESULTS: As compared with the control group, the open probability of the K(Ca) channels decreased from 0.135 +/- 0.021 to 0.044 +/- 0.018, the open time from (5.75 +/- 0.40) ms to (2.39 +/- 0.13) ms, while the close time increased from (2.17 +/- 0.50) ms to (23.73 +/- 2.50) ms in the doxofylline incubated group. The differences were significant between the two groups (all P < 0.05). CONCLUSION: Doxofylline could decrease the open probability of the channels as a result of both the shortening of open period and the prolongation of close time.

Adolescent↗

PubMed2004

Assessing genomewide statistical significance in linkage studies.

Assessment of genomewide statistical significance in multipoint linkage analysis is a thorny problem. The existing analytical solutions rely on strong assumptions (i.e., infinitely dense or equally spaced genetic markers that are fully informative and completely observed, and a single type of relative pair) which are rarely satisfied in real human studies, while simulation-based methods are computationally intensive and may not be applicable to complex data structures and sophisticated genetic models. Here, we propose a conceptually simple and numerically efficient Monte Carlo procedure for determining genomewide significance levels that is applicable to all linkage studies. The pedigree structure is completely general; the marker data are totally arbitrary in respect to number, spacing, informativeness, and missingness; the trait can be qualitative, quantitative, or multivariate; the alternative hypothesis can be two-sided or one-sided; and the statistic can be parametric or nonparametric. The usefulness of the proposed approach is demonstrated through extensive simulation studies and an application to the nuclear family data from the Tenth Genetic Analysis Workshop.

Computer Simulation↗

PubMed2004

Nonparametric estimation of the effects of quantitative trait loci.

Interval mapping of quantitative trait loci from breeding experiments plays an important role in understanding the mechanisms of disease, both in humans and other organisms. Standard approaches to estimation involve parametric assumptions for the component distributions and may be sensitive to model misspecification. Some nonparametric tests have been studied. However, nonparametric estimation of the phenotypic distributions has not been considered in the genetics literature, even though such methods might provide essential nonparametric summaries for comparing different loci. We develop a sufficient condition for identifiability of the phenotypic distributions. Simple nonparametric estimators for the distributions are proposed for uncensored and right censored data. They have a closed form and their small and large sample properties are readily established. Their practical utility as numerical summaries which complement nonparametric tests is demonstrated on two recent genetics examples.

Animals↗

PubMed2004

Mapping quantitative trait loci with censored observations.

The existing statistical methods for mapping quantitative trait loci (QTL) assume that the phenotype follows a normal distribution and is fully observed. These assumptions may not be satisfied when the phenotype pertains to the survival time or failure time, which has a skewed distribution and is usually subject to censoring due to random loss of follow-up or limited duration of the experiment. In this article, we propose an interval-mapping approach for censored failure time phenotypes. We formulate the effects of QTL on the failure time through parametric proportional hazards models and develop efficient likelihood-based inference procedures. In addition, we show how to assess genome-wide statistical significance. The performance of the proposed methods is evaluated through extensive simulation studies. An application to a mouse cross is provided.

Chromosome Mapping↗

PubMed2004

An efficient resampling method for assessing genome-wide statistical significance in mapping quantitative trait Loci.

Assessing genome-wide statistical significance is an important and difficult problem in multipoint linkage analysis. Due to multiple tests on the same genome, the usual pointwise significance level based on the chi-square approximation is inappropriate. Permutation is widely used to determine genome-wide significance. Theoretical approximations are available for simple experimental crosses. In this article, we propose a resampling procedure to assess the significance of genome-wide QTL mapping for experimental crosses. The proposed method is computationally much less intensive than the permutation procedure (in the order of 10(2) or higher) and is applicable to complex breeding designs and sophisticated genetic models that cannot be handled by the permutation and theoretical methods. The usefulness of the proposed method is demonstrated through simulation studies and an application to a Drosophila backcross.

Animals↗

PubMed2004

[Preventive effects of heat-shock response against circulatory collapse induced by hyperthermia].

OBJECTIVE: To investigate the preventive effects of heat-shock response (HSR) against circulatory collapse induced by hyperthermia and understand its mechanism. METHODS: Twenty-four SD rats were randomized equally into heat-shock group (HS group), high temperature control group (HC group) and normal temperature control group (NC group). The rats in HS group, but not HC group, were subjected to heat shock pretreatment. After a recovery period for 20 h at room temperature, the rats in HS and HC groups were exposed to high temperature environment, and their blood pressures and electrocardiograms were measured continuously. Heat exposure was terminated at 73 min and the contents of myocardial malondialdehyde (MDA) and NO were measured. Using Chart software, the data of the mean arterial pressure (MAP), systolic pressure (SP), diastolic pressure (DP), heart rate (HR) were acquired. The rats in NC group did not receive any treatment to obtain the measurements in normal condition. RESULTS: Compared with NC group, the MAP, SP and DP were significantly lowered (P P<0.01) in HS and HC group and HR accelerated (P P<0.01) after a 73-min heat exposure, and HS group had significantly higher measurements of the above indices than HC group did. In comparison with NC group, the contents of MDA and NO in the myocardium in HC group were significantly elevated after the exposure (P P<0.01). The MDA content in HS group, which was comparable with that of NC group, was significantly lower than that of HC group (P P<0.05), and compared with HC group, HS also had lower NO content (P<0.01). CONCLUSION: HSR may relieve circulatory collapse induced by hyperthermia, which involves the inhibitory effect of HSR on the production of MDA and NO in the myocardium.

Animals↗

PubMed2004

[Changes in Ca2+ concentration mediated by N-methyl-D-aspartate receptor in PO/AH neurons of anoxic SD rats].

OBJECTIVE: To study the changes of Ca2+ concentration mediated by N-methyl-D-aspartate (NMDA) receptor in the neurons in the preoptic area/anterior hypothalamus (PO/AH) of anoxic SD rats by investigating the properties of NMDA receptor. METHODS: The effects of NMDA receptor agonist NMDA and antagonist vaproic acid (VPA) on the [Ca2+]i in PO/AH neurons were observed in SD rats with anoxia. RESULTS: Under normal condition, the fluorescencet ratio was 0.95, which increased obviously in response to treatment with NMDA at 40 s and reached the peak value, 2.054, after 25 s with an increment of (109+/-52) %. After the addition of the agonist, the peak value reached 3.783 in 30 s and maintained the high level. The concentration of Ca2+ increased by (286+/-91) % after the treatment with NMDA. While in the anoxia group, the concentration of Ca2+ decreased by (103+/-45)% after the addition of VPA. CONCLUSIONS: The increase in the concentration of Ca2+ results predominantly from the opening of NMDA receptor channel which allows Ca2+ influx. VPA may decrease the activity of NMDA receptor to reduce the Ca2+ concentration for the protection of the neurons against anoxia.

Adenosine Triphosphate↗

PubMed2004

[Protective effects of heat shock response on circulatory collapse induced by hyperthermia].

OBJECTIVE: To investigate the protective effects and mechanism of heat shock response (HSR) on circulatory collapse induced by hyperthermia. METHODS: Two experiments were carried out: (1) Protective effects of HSR. Rats were divided into 2 groups: heat shock (HS) group, sham control (SC) group. After HS group was pretreated with heat shock and recovered for 20 h at room temperature, both groups were exposed to heat till death, and blood pressure, electrocardiogram were measured continuously during exposure. Mean arterial pressure (MAP), survival time etc were acquired through Chart software. (2) Mechanism of effects. Rats were divided into 3 groups: HS group, SC group and normal control (NC) group. The treatment in HS and SC groups was identical with that in the first experiment, but it would be terminated at 73 min after heat exposure. Systolic pressure (Ps), diastolic pressure (Pd) etc were recorded and content of NO and HSP70 in myocardium were measured. RESULTS: (1) The survival time in HS group [(102.3 +/- 11.4) min] was longer than that in SC group [(87.9 +/- 7.7) min] and shock revealed later (P < 0.01); (2) During early heat exposure MAP in HS group was not different from that in SC group, but after 60 min MAP in HS group were higher than that in SC group; (3) MAP, Ps, Pd, HR and HSP70 in HS group were significantly higher but content of NO was lower than those in SC group (P < 0.01, P < 0.05). CONCLUSION: HSR may induce upregulation of HSP70 and inhibit excessive production of NO in myocardium, thus result in relief of circulatory collapse induced by hyperthermia.

Animals↗

PubMed2004

[Cloning of differentially expressed genes of eosinophils from asthmatic patients by suppression subtractive hybridization].

OBJECTIVE: To explore the molecular mechanism of eosinophils for its role in bronchial asthma. METHODS: The total RNA extracted from the eosinophils of patients during the onset of asthma was used as the tester and the total RNA obtained after treatment served as the driver. cDNA suppression subtractive hybridization (SSH) was performed using the protocols described in the Clontech SMART PCR cDNA Syn thesis Kit and PCR-Select cDNA Subtraction Kit. The subtracted cDNA was then inserted into T vector to generate subtracted cDNA library. Clones of the subtracted cDNA library were screened by hybridization and the insert sequence of the positive clones was compared with the sequence in the GenBank. RESULTS: A total of 400 clones selected from the subtracted cDNA library were amplified by PCR and about 85% of these clones contained inserts. Six differential cDNA fragments were acquired after two differential screening. These genes were involved in the regulation of proinflammatory response, signal transduction, energy metabolism and cell apoptosis. CONCLUSION: Differentially expressed genes of the eosinophils during the onset and the remission stage of bronchial asthma can be effectively cloned by SSH, which provides a solid foundation for clarifying the molecular mechanism of eosinophils in asthma and a theoretical base for clinical treatment and prevention of asthma.

Asthma↗

PubMed2004

[Pretreatment with aspirin for protection against heat stroke in rats].

OBJECTIVE: To observe the changes in blood pressure and interleukin-1beta (IL-1beta) level after heat stroke in rats and to observe the protective effect of pretreatment with aspirin against heat stroke. METHODS: Rat models of heat stroke were established and randomly assigned into control (n=10) and aspirin groups (n=10). Arterial blood pressure, colonic temperature (T(co)), and electrocardiograph (ECG) were monitored and blood samples taken at 0 and 60 min after heat exposure for determining the plasma IL-1beta levels in the two groups. RESULTS: From 0 to 50 min after heat exposure, the mean arterial blood pressure MAP was not significantly different between the two groups, but at about 55-60 min, the MAP significantly decreased in the control group in comparison with the aspirin group (P<0.01). The K value and the height of the dicrotic notch (h(D)/H) were gradually decreased, especially at 40 min after heat exposure, and the control group showed greater reduction in the K value. T(co) of both groups were increased after heat exposure, without significant difference between groups. The time of the onset of heat stroke was similar in the two groups, but rats in the aspirin group had significantly longer survival time (P<0.05). ECG showed that the heart rate and QT intervals of both groups were increased, while PR intervals were decreased after heat exposure. Plasma IL-1beta levels in the two groups were significantly elevated at 60 min in comparison with the basal level (P<0.05), which was more obvious in the control group (P<0.05). CONCLUSION: Pretreatment with anti-inflammatory dose of aspirin can provide protection against heat stroke in rats, which may be associated with the inhibition of elevation of plasma IL-1beta levels by aspirin.

Animals↗

PubMed2004

[Super SMART cDNA synthesis technology for amplifying small amount of total RNA of peripheral blood eosinophils from asthma patients].

OBJECTIVE: To amplify double-strand cDNA from small amount of total RNA of eosinophils from asthma patients by Super SMART cDNA synthesis technique. METHODS: The eosinophils were purified from the peripheral blood of asthma patients before and after treatment by Percoll gradient centrifugation, from which the total RNA was extracted using TRIzol kit. First-strand cDNA synthesis and double-strand cDNA amplification were performed using Super SMART cDNA synthesis technique. The quality of the obtained cDNA was evaluated by gradient cDNA electrophoresis, and the amplification efficiency determined by cDNA quantification. RESULT: From 20 ng total RNA, 7.155 microg and 6.568 microg of the tester and driver double- strand cDNAs respectively were obtained successfully, and the result of electrophoresis indicated high quality and purity of the cDNA acquired. CONCLUSION: Super SMART cDNA synthesis technique can effectively amplify high-quality double-strand DNA from a very small amount of total RNA, which may facilitate the exploration of the mechanism of asthma from the genetic level.

Asthma↗

PubMed2004

[Isolation, culture and identification of rat hippocampal neural stem cells].

OBJECTIVE: To explore the feasibility of the isolation, culture and identification of the neural stem cells originated from the hippocampi of neonatal rats (1-3 d) and adult rats respectively. METHODS: The neural stem cells were isolated from the hippocampi of neonatal and adult rats and cultured in serum-free medium containing basic fibroblast growth factor (bFGF), brain-derived neurotrophic factor (BDNF) and other growth factors using single-cell cloning technique. Immunochemistry was employed to identify the cloned cells and their daughter cells as well as mature neural cells differentiated from the cell clone. RESULTS: The floating neural spheres obtained by above culture procedures for isolated cells from the hippocampi of neonatal and adult rats were positive for nestin expression, with the potential for further cloning and capable of differentiation into neurons or glial cells, which formed reticular connection between the cells and expressed neuron-specific enolase (NSE) and glial fibrillary acidic protein (GFAP) respectively. CONCLUSION: The hippocampi of neonatal and adult rats contain neural stem cells.

Animals↗

PubMed2003

Formaldehyde-induced gene expression in F344 rat nasal respiratory epithelium.

Formaldehyde (FA), an occupational and environmental toxicant used extensively in the manufacturing of many household and personal use products, is known to induce squamous cell carcinomas in the nasal turbinates of rats and mice and squamous metaplasia in monkey noses. Tissue responses to FA include a dose dependent epithelial degeneration, respiratory cell hypertrophy, and squamous metaplasia. The primary target for FA-induced toxicity in both rodents and monkeys is the respiratory nasal epithelium. FA increases nasal epithelial cell proliferation and DNA-protein crosslinks (DPX) that are associated with subsequent nasal cancer development. To address the acute effects of FA exposure that might contribute to known pathological changes, cDNA gene expression analysis was used. Two groups of male F344 rats received either 40 ul of distilled water or FA (400 mM) instilled into each nostril. Twenty-four hours following treatment, nasal epithelium was recovered from which total RNA was used to generate cDNA probes. Significance analysis of microarrays (SAM) hybridization data using Clontech Rat Atlas 1.2 arrays revealed that 24 of the 1185 genes queried were significantly up-regulated and 22 genes were significantly downregulated. Results for ten of the differentially expressed genes were confirmed by quantitative real time RT PCR. The identified genes with FA-induced change in expression belong to the functional gene categories xenobiotic metabolism, cell cycle, apoptosis, and DNA repair. These data suggest that multiple pathways are dysregulated by FA exposure, including those involved in DNA synthesis/repair and regulation of cell proliferation. Differential gene expression profiles may provide clues that could be used to define mechanisms involved in FA-induced nasal cancer.

Administration, Intranasal↗