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Xia Chen

Publications and source records attributed to Xia Chen.

At least 19 recordsLinked to original sources
PubMed2026

Genetic structure and selection signatures of Beijing-You chicken populations provide insight into breed conservation.

Preserving genetic diversity and maintaining population viability are critical yet challenging goals that demand rigorous evaluation of conservation strategies. Beijing-You chicken, as the sole indigenous chicken breed originating from Beijing, China, is currently maintained as four independent populations under distinct conservation programs. How different conservation regimes have shaped its genomic architecture remains largely unknown, limiting evidence-based evaluation. Here, we generated whole-genome resequencing data from 240 individuals representing four Beijing-You chicken populations to assess population structure, genetic diversity, and signatures of selection over decades of conservation. All four populations formed distinct clusters, reflecting measurable differentiation after decades of separate conservation. The differences in genetic diversity were broadly consistent with the variation in effective population size estimates. Runs of homozygosity and linkage disequilibrium decay patterns further characterized each population, with extended values indicating reduced effective population size and increased inbreeding under long-term conservation. We applied the fixation index (FST) and pairwise diversity ratio (θπ) methods to identify selection signatures. A total of 171 genes were identified as candidates. These genes were enriched in pathways related to reproduction, growth regulation, and environmental adaptation. These findings highlight patterns of reduced diversity and skewed relatedness, which could arise from management-related factors such as breeding preferences or mating strategies. Still, they are also compatible with neutral processes, including drift and founder effects. Regardless of the underlying cause, integrating scientifically informed conservation strategies with routine genomic monitoring across generations is essential for sustaining genetic diversity in Beijing-You chicken and other indigenous breeds.

Beijing-You chicken↗
PubMed2006

The zinc finger transcription factor 191 is required for early embryonic development and cell proliferation.

Human zinc finger protein 191 (ZNF191/ZNF24) was cloned and characterized as a SCAN family member, which shows 94% identity to its mouse homologue zinc finger protein 191 (Zfp191). ZNF191 can specifically interact with an intronic polymorphic TCAT repeat (HUMTH01) in the tyrosine hydroxylase (TH) gene. Allelic variations of HUMTH01 have been stated to have a quantitative silencing effect on TH gene expression and to correlate with quantitative and qualitative changes in the binding by ZNF191. Zfp191 is widely expressed during embryonic development and in multiple tissues and organs in adult. To investigate the functions of Zfp191 in vivo, we have used homologous recombination to generate mice that are deficient in Zfp191. Heterozygous Zfp191(+/-) mice are normal and fertile. Homozygous Zfp191(-/-) embryos are severely retarded in development and die at approximately 7.5 days post-fertilization. Unexpectedly, in Zfp191(-/-) and Zfp191(+/-) embryos, TH gene expression is not affected. Blastocyst outgrowth experiments and the RNA interference-mediated knockdown of ZNF191 in cultured cells revealed an essential role for Zfp191 in cell proliferation. In further agreement with this function, no viable Zfp191(-/-) cell lines were obtained by derivation of embryonic stem (ES) cells from blastocysts of Zfp191(+/-) intercrosses or by forced homogenotization of heterozygous ES cells at high concentrations of G418. These data show that Zfp191 is indispensable for early embryonic development and cell proliferation.

Animals↗
PubMed2006

c-kit delineates a distinct domain of progenitors in the developing kidney.

Early inductive events in mammalian nephrogenesis depend on an interaction between the ureteric bud and the metanephric mesenchyme. However, mounting evidence points towards an involvement of additional cell types--such as stromal cells and angioblasts--in growth and patterning of the nephron. In this study, through analysis of the stem cell factor (SCF)/c-kit ligand receptor pair, we describe an additional distinct cell population in the early developing kidney. While SCF is restricted to the ureteric bud, c-kit-positive cells are located within the renal interstitium, but are negative for Foxd1, an established marker of stromal cells. In fact, the c-kit-positive domain is continuous with a central mesodermal cell mass ventral and lateral to the dorsal aorta, while Foxd1-expressing stromal cells are continuous with a dorsal perisomitic cell population suggesting distinct intraembryonic origins for these cell types. A subset of c-kit-positive cells expresses Flk-1 and podocalyxin, suggesting that this cell population includes angioblasts and their progenitors. c-kit activation is not required for the survival of these cells in vivo, because white spotting (c-kit(W/W)) mice, carrying a natural inactivating mutation of c-kit, display normal intrarenal distribution of the c-kit-positive cells at E13.5. In addition, early kidney development in these mutants is preserved up to the stage when anemia compromises global embryonic development. In contrast, under defined conditions in organ cultures of metanephric kidneys, c-kit-positive cells, including the Flk-1-positive subset, undergo apoptosis after treatment with STI-571, an inhibitor of c-kit tyrosine phosphorylation. This is associated with reductions in ureteric bud branching and nephron number. Conversely, exogenous SCF expands the c-kit-positive population, including Flk-1-positive angioblasts, and accelerates kidney development in vitro. These data suggest that ureteric bud-derived SCF elicits growth-promoting effects in the metanephric kidney by expanding one or more components of the interstitial c-kit-positive progenitor pool.

Animals↗
PubMed2006

Angiopoietin-related growth factor (AGF) supports adhesion, spreading, and migration of keratinocytes, fibroblasts, and endothelial cells through interaction with RGD-binding integrins.

Angiopoietin-related growth factor (AGF) is a newly identified member of angiopoietin-related proteins (ARPs)/angiopoietin-like proteins (Angptls). AGF has been considered as a novel growth factor in accelerating cutaneous wound healing, as it is capable of stimulating keratinocytes proliferation as well as angiogenesis. But in our paper, we demonstrate that AGF stimulates keratinocytes proliferation only at high protein concentration, however, it can potently promote adhesion, spreading, and migration of keratinocytes, fibroblasts, and endothelial cells. Furthermore, we confirm that the adhesion and migration cellular events are mediated by RGD-binding integrins, most possibly the alpha(v)-containing integrins, by in vitro inhibition assays using synthetic competitive peptides. Our results strongly suggest that AGF is an integrin ligand as well as a mitogenic growth factor and theoretically participates in cutaneous wound healing in a more complex mechanism.

Angiopoietin-Like Protein 6↗
PubMed2006

Identification of a new Neisseria meningitidis serogroup C clone from Anhui province, China.

BACKGROUND: Outbreaks of a new serogroup C meningococcal disease emerged during 2003-04 (five outbreaks with 43 cases) and in 2004-05 (five outbreaks with 29 cases), all in Anhui province, China. We describe the molecular epidemiology and features of the causative bacterial strains. METHODS: We used pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) to analyse the strains. FINDINGS: Of 34 strains of Neisseria meningitidis cultured during 2003-04 from Anhui province, 31 were group C meningococci, 28 of which were associated with three of five outbreaks; one from a patient and 27 from close contacts of eight patients. Of 30 strains isolated from Anhui province during 2004-05, 17 were identified as serogroup C meningococci, ten of which were associated with four of five outbreaks. In a nationwide survey, 542 strains were isolated during 2004-05; 58 were serogroup C meningococci interspersed among 11 other provinces where no serogroup C outbreak occurred. Of the 106 serogroup C strains analysed, 89 had identical PFGE patterns, designated AH1. Of 28 strains selected for MLST analyses, 25 were sequence type 4821 (ST-4821), which did not belong to any of the previously reported sequence types that can form a new hypervirulent lineage. INTERPRETATION: ST-4821 seems to be unique and caused the serogroup C meningitis outbreaks during the two seasons from 2003 to 2005 in Anhui province. The emergence of this sequence type has epidemiological importance that should be monitored for future spread in China and the rest of the world.

Child↗
PubMed2006

Effects of histone deacetylase inhibitors on transcriptional regulation of the hsp70 gene in Drosophila.

Histone acetyltransferases/deacetylases contribute to the activation or inactivation of transcription by modifying the structure of chromatin. Here we examined the effects of histone deacetylase inhibitors (HDIs), trichostatin A, and sodium butyrate on hsp70 gene transcriptional regulation in Drosophila. The chromatin immunoprecipitation assays revealed that HDI treatments induced the hyperacetylation of histone H3 at the promoter and the transcribing regions of hsp70 gene, increased the accessibility of heat-shock factor to target heat-shock element, and promoted the RNA polymerase II-mediated transcription. Moreover, the quantitative real-time PCR confirmed that the HDI-induced hyperacetylation of histone H3 enhanced both the basal and the inducible expression of hsp70 mRNA level. In addition, the acetylation level of histone H3 at the promoter exhibited a fluctuated change upon the time of heat shock. These experimental data implicated a causal link between histone acetylation and enhanced transcription initiation of hsp70 gene in Drosophila.

Acetylation↗
PubMed2005

Novel regulators of kidney development from the tips of the ureteric bud.

Mammalian nephrogenesis depends on the interaction between the ureteric bud and the metanephric mesenchyme. As the ureteric bud undergoes branching and segmentation, the stalks differentiate into the collecting system of the mature kidney, while the tip cells interact with the adjacent cells of the metanephric mesenchyme, inducing their conversion into nephrons. This induction is mediated by secreted factors. For identifying novel mediators, the tips of the ureteric tree were isolated and microarray analyses were performed using manually refined, multistep gene ontology annotations. For identifying conserved factors, two databases were developed, one from mouse E12.5 and one from rat E13.5 ureteric buds. The overlap of mouse and rat data sets yielded 20 different transcripts that were enriched in the ureteric bud compared with metanephric mesenchyme and predicted to code for secreted proteins. Real-time reverse transcriptase-PCR and in situ hybridization confirmed these identifications. One of the genes that was highly specific to the ureteric bud tip was cytokine-like factor 1 (CLF-1). Recombinant CLF-1 in complex with its physiologic ligand, cardiotrophin-like cytokine (CLC), triggered phosphorylation of signal transducer and activator of transcription 3 in mesenchyme, a pathway characteristic of mesenchymal-to-epithelial conversion. Indeed, when applied to isolated rat metanephric mesenchyme, CLF-1/CLC (3 nM) induced mature nephron structures expressing glomerular and tubular markers. These results underline the power of this first comprehensive gene expression analysis of the ureteric bud tip to identify bioactive molecules.

Animals↗
PubMed2005

Histone acetylation regulates both transcription initiation and elongation of hsp22 gene in Drosophila.

Histone acetylation is associated with transcriptional activation of many genes. However, the role of acetylation in transcriptional regulation of heat shock protein genes (hsp) still remains an obscure issue. Here we examined the effects of histone deacetylase inhibitors (HDIs), trichostatin A, and sodium butyrate, on changes in acetylation level of core histones and on expression of hsp22 gene in Drosophila melanogaster. The results showed that both HDIs elevated the acetylation level of histone H3. By using the chromatin immunoprecipitation, we located the HDI-induced H3 hyperacetylation at both the promoter and the downstream of RNA polymerase II of the transcribing hsp22 gene. Meanwhile, the elevated acetylation level increased the accessibility of heat shock factor to target cis-acting regulatory sites. We conclude that histone acetylation stimulates the transcription initiation and promotes the transcription elongation, thereby up-regulating both basal and inducible expression of hsp22 in D. melanogaster.

Acetylation↗
PubMed2005

Endocytic delivery of lipocalin-siderophore-iron complex rescues the kidney from ischemia-reperfusion injury.

Neutrophil gelatinase-associated lipocalin (Ngal), also known as siderocalin, forms a complex with iron-binding siderophores (Ngal:siderophore:Fe). This complex converts renal progenitors into epithelial tubules. In this study, we tested the hypothesis that Ngal:siderophore:Fe protects adult kidney epithelial cells or accelerates their recovery from damage. Using a mouse model of severe renal failure, ischemia-reperfusion injury, we show that a single dose of Ngal (10 microg), introduced during the initial phase of the disease, dramatically protects the kidney and mitigates azotemia. Ngal activity depends on delivery of the protein and its siderophore to the proximal tubule. Iron must also be delivered, since blockade of the siderophore with gallium inhibits the rescue from ischemia. The Ngal:siderophore:Fe complex upregulates heme oxygenase-1, a protective enzyme, preserves proximal tubule N-cadherin, and inhibits cell death. Because mouse urine contains an Ngal-dependent siderophore-like activity, endogenous Ngal might also play a protective role. Indeed, Ngal is highly accumulated in the human kidney cortical tubules and in the blood and urine after nephrotoxic and ischemic injury. We reveal what we believe to be a novel pathway of iron traffic that is activated in human and mouse renal diseases, and it provides a unique method for their treatment.

Acute-Phase Proteins↗
PubMed2005

Lifespan extension and elevated hsp gene expression in Drosophila caused by histone deacetylase inhibitors.

The heat shock proteins (Hsps) play a positive role in lifespan determination, and histone acetylation has been shown to be involved in transcription of hsp genes in Drosophila. To further determine if hsp22 and hsp70 expression is correlated with lifespan, and if histone acetylation participates in this process, RNA levels for hsp22 and hsp70 were analyzed throughout the lifespan in the long-lived and short-lived iso-female lines. The results showed that hsp22 and hsp70 RNA levels were higher in long-lived line than in short-lived line and that the long-lived flies responded more rapidly to heat but were more tolerant to high temperature. Moreover, we investigated the influences of histone acetylation modification on longevity and on hsp gene expression by using histone deacetylase (HDAC) inhibitors TSA and BuA. The results demonstrated that both inhibitors were able to extend the lifespan and promote hsp22 and hsp70 expression. However, the optimal concentrations of these inhibitors, and probably the mechanisms of their actions, vary with the genetic background. In addition, we showed that HDAC inhibitors caused the hyperacetylation of core histone H3, implicating the involvement of chromatin modulation in hsp gene transcription. These data suggested a close correlation among histone acetylation, hsp gene expression and longevity in D. melanogaster.

Animals↗
PubMed2005

[Stereoacuity before and after surgery in patients with acquired excyclotorsion].

OBJECTIVE: To investigate the stereoacuity before and after superior oblique sagittal transposition in patients with acquired excyclotorsion. METHODS: 14 cases of acquired excyclotorsion who had complaints of forward and downward torsional diplopia were treated with superior oblique sagittal transposition. All patients were examined with Titmus test prior and after surgery. RESULTS: Surgical treatment greatly improved torsional diplopia. The stereoacuity improved gradually from 800 to 60 seconds of arc, peripheral to macular stereoacuity, and even foveal stereoacuity. CONCLUSION: The superior oblique sagittal transposition is an effective method for primary and down gaze acquired excyclotorsion. The operation not only alleviated diplopia in the practical fixation field, but also improved stereoacuity.

Adult↗
PubMed2005

[A clinical analysis of sixty-seven cases with Duane's retraction syndrome].

OBJECTIVE: To analyze the clinical manifestations and the methods and effects of surgical management on Duane's Retraction Syndrome (DRS). METHODS: 67 cases with DRS were summarized retrospectively. The data were recorded and analysed, including sex, age, type, clinical features, surgical methods and the results. RESULTS: 63 cases had only monocular involvement. The number of Type I DRS was 47 cases (35 cases with esotropia, 12 cases with exotropia). 8 cases were Type II DRS with exotropia and 12 cases were Type III DRS (11 of them with exotropia). In 37 cases with upshoot and/or downshoot phenomenon, 31 of them were associated with exotropia. Ipsilateral medial rectus or lateral rectus recession, or bilateral medial rectus recession, improved the head compensation position, narrow palpebral fissure and globe retraction, with improvement or elimination of the deviation. After the operation, 60 cases (90%) showed horizontal tropia less than 10 prism diopters. Upshoot and/or downshoot were improved in all of the 37 cases after recessing medial or/and lateral recti, or simultaneously weakening of the inferior oblique muscle. CONCLUSION: Weakening medial and/or lateral recti can improve the clinical manifestations of DRS. Upshoot and downshoot are more common in eyes with exotropia. Lateral rectus recession is the main treatment method for relieving upshoot and downshoot in DRS with exotropia. We infer that the upshoot and downshoot phenomenon mainly related to the "bridle" effect. Recession of both horizontal recti can improve the serious clinical manifestations.

Adolescent↗
PubMed2004

Detection of intracellular iron by its regulatory effect.

Intracellular iron regulates gene expression by inhibiting the interaction of iron regulatory proteins (IRPs) with RNA motifs called iron-responsive elements (IREs). To assay this interaction in living cells we have developed two fluorescent IRE-based reporters that rapidly, reversibly, and specifically respond to changes in cellular iron status as well as signaling that modifies IRP activity. The reporters were also sufficiently sensitive to distinguish apo- from holotransferrin in the medium, to detect the effect of modifiers of the transferrin pathway such as HFE, and to detect the donation or chelation of iron by siderophores bound to the lipocalin neutrophil gelatinase-associated lipocalin (Ngal). In addition, alternative configurations of the IRE motif either enhanced or repressed fluorescence, permitting a ratio analysis of the iron-dependent response. These characteristics make it possible to visualize iron-IRP-IRE interactions in vivo.

Acute-Phase Proteins↗
PubMed2004

Establishment of transgenic mice carrying gene encoding human zinc finger protein 191.

AIM: Human zinc finger protein 191 (ZNF191) was cloned and characterized as a Kruppel-like transcription factor, which might be relevant to many diseases such as liver cancer, neuropsychiatric and cardiovascular diseases. Although progress has been made recently, the biological function of ZNF191 remains largely unidentified. The aim of this study was to establish a ZNF 191 transgenic mouse model, which would promote the functional study of ZNF191. METHODS: Transgene fragments were microinjected into fertilized eggs of mice. The manipulated embryos were transferred into the oviducts of pseudo-pregnant female mice. The offsprings were identified by PCR and Southern blot analysis. ZNF 191 gene expression was analyzed by RT-PCR. Transgenic founder mice were used to establish transgenic mouse lineages. The first generation (F1) and the second generation (F2) mice were identified by PCR analysis. Ten-week transgenic mice were used for pathological examination. RESULTS: Four mice were identified as carrying copies of ZNF191 gene. The results of RT-PCR showed that ZNF 191 gene was expressed in the liver, testis and brain in one of the transgenic mouse lineages. Genetic analysis of transgenic mice demonstrated that ZNF 191 gene was integrated into the chromosome at a single site and could be transmitted stably. Pathological analysis showed that the expression of ZNF 191 did not cause obvious pathological changes in multiple tissues of transgenic mice. CONCLUSION: ZNF 191 transgenic mouse model would facilitate the investigation of biological functions of ZNF191 in vivo.

Animals↗
PubMed2004

Recurrent breast carcinoma arising in a transverse rectus abdominis myocutaneous flap.

Reconstruction after mastectomy for breast carcinoma with implants or myocutaneous flaps is a widely used surgical technique. Recurrence of breast carcinoma after these procedures is uncommon. Most recurrences occur in the skin or scar site of the mastectomy and are readily detectable by physical examination. There are rare reported cases of recurrent carcinoma occurring within the flaps that are usually diagnosed with the aid of imaging and subsequent pathologic examination. In most cases, these recurrences represent invasive or in situ ductal carcinoma. We report an additional 2 cases of breast carcinoma recurring within the myocutaneous flap, both of which exhibited uncommon histologic features not previously reported.

Breast Neoplasms↗
PubMed2004

[A caregiver survey in Beijing, Xi'an, Shanghai and Chengdu: health services status for the elderly with dementia].

OBJECTIVE: In order to rationally allocate resources and to improve the quality of life of people with dementia, it is necessary to assess their current health services status. METHODS: A population-based door-to-door caregiver survey was conducted in Beijing, Xi'an, Shanghai and Chengdu in 1998. Totally 1 141 individuals with dementia were found among 34 807 residents aged 55 years and over on the basis of national prevalence study of dementia. Then 428 families with demented patients were randomly selected for questionare interview. Interviews were completed in 405 but refused by 23 families. Measurements included demographic characteristics of patients and their caregivers, perspective of the victim of the disease, current awareness of the disease and medical and welfare services provided. RESULTS: Among 405 cases of dementia (including 298 cases of AD and 81 cases of VaD), mean MMSE scores were 16.3 +/- 5.3 for 157 mild cases, 12.7 +/- 5.4 for 135 moderate cases, and 6.2 +/- 5.8 for 110 severe cases. Most patients (96%) were cared for at home by family members. Among caregivers, 189 (48.8%) considered the impairment of cognition, behavior and daily living activity in demented persons as a result of normal aging. Half of the caregivers spend over 8 hours each day looking after the patient. Whether the caregivers brought their relatives with dementia to a doctor was determined by disease severity, i.e. 8.3% for mild, 13.5% for moderate, and 19.4% for severe in 1996 to approximately 1997 and 14.4%, 25.6% and 33.6%, respectively in 1998-1999. Of those, only 26.9% reported receiving a dementia diagnosis, and only 21.3% received a recommedation to take medication. However, there was no established standard treatment and only 2% patient's used Ache-I. CONCLUSIONS: General education is needed to increase the public awareness of dementia. For patients with dementia, early diagnosis, early treatment and optimal care are important to improve their quality of life.

Activities of Daily Living↗
PubMed2004

[Comparative study on the clinical features of Alzheimer's disease and vascular dementia].

OBJECTIVE: To investigate the clinical features of Alzheimer's disease (AD) and vascular dementia (VaD), and to find effective methods for differential diagnosis between the two entities. METHODS: Totally 112 AD patients and 92 VaD patients were enrolled in this study, consisted of patients from the memory clinics and patients from the community population visited during the epidemiological survey from 1996 to 2000. Diagnosis of dementia, probable AD and probable VaD were made according to international criteria. Results of specific neuroimaging examination were referred to verify the diagnosis and the final diagnosis of each patient was determined from the discussion between clinical experts and radiological professionals. Analysis on clinical and neuroimaging data was performed, aiming at finding differential points between the two dementia-subtypes. A logistic binary multiple regression analysis was performed to pick out those statistically significant clinical features for differential diagnosis at last. RESULTS: AD and VaD patients have different clinical features in various demented stages, therefore the indexes that differentiate the two dementia subtypes change accordingly. The predominant features of mild AD appear to be deficits of prolonged memory and learning ability, while the major impairment of mild VaD patients is decline of calculating ability. With the progress of dementia, learning ability and attention turn to be the effective indexes for differential diagnosis. In the mild and moderate demented stage, AD patients are inferior to VaD patients in handling finacial affairs and making phone calls, while VaD patients often degenerate in daily activities concerning with both physical ability and intellectual level. Severe VaD patients appears more global degeneration of living ability compared to AD patients. The difference of ADL scores between the two subtypes is significant in moderate to severe demented patients (P < 0.05). Psychological behavior symptoms, such as repeatedly collecting useless things, are the characteristic manifestation to differentiate AD from VaD in all clinical stages. CONCLUSIONS: The results of our study indicate that substantial differences exist between AD and VaD patients. Such differences can be attributed to the differences of lesion nature and distribution, as well as the underlying pathophysiological procedures of each disease.

Activities of Daily Living↗