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Biomedical subjects

Qin Chen

Publications and source records attributed to Qin Chen.

50 records · Page 3Linked to original sources
PubMed2003

[The experimental study on inducing and expanding T/NK cells from mononuclear cells of human umbilical cord blood].

OBJECTIVE: To explore the most efficient culture system which can induce cord blood (CB)-mononuclear cells (MNC) to differentiate into mature T/NK cells in vitro. METHODS: The CB MNCs were cultured in six culture systems respectively for 4 weeks. The T/NK cell surface phenotypes were analyzed by flow cytometry and the absolute numbers of nucleated cells (NCs) were counted at each time point. Moreover, cell morphology was identified by Giemsa-Wright staining, and cytotoxicity of the cultured cells to K562 and Raji tumor cells was also evaluated by MTT method. RESULTS: Cultured in the cytokine cocktail of SCF + FLT-3L + IL-7 + IL-15 + TNF-alpha + IL-2, the NCs were (20 approximately 26) x 10(6)/ml in numbers at day 22. The percentage of lymphocytes in the NCs and that of CD(3)(+) T cells in the lymphocytes both exceeded 90% at the same time. Most of the CD(3)(+) T cells were CD(3)(+)CD(8)(+) and the percentage of CD(3)(+)CD(4)(+) T cells declined gradually. The percentage of CD(3)(+)CD(56)(+) NKT cells and gamma delta(+)T cells in the lymphocytes arised from lower than 2% to 30% approximately 40% and 10% approximately 15%, respectively. CD(3)(-)CD(56)(+) NK cells were not expanded. The cytotoxic activity of the cultured cells to K562 and Raji cells at an effector:target (E:T) ratio of 50:1 was over 75% and about 32% approximately 65%, respectively. CONCLUSION: The most efficient culture system which can induce CB MNC to differentiate into mature T/NK cells in vitro is the cytokines cocktail of SCF + FLT-3L + IL-7 + IL-15 + TNF-alpha + IL-2, and the optimum culture time is 22 days.

Cell Differentiation↗
PubMed2002

Discovery and analysis of hepatocellular carcinoma genes using cDNA microarrays.

PURPOSE: Microarray analysis on a genomic scale was used to profile changes in gene expression accompanying hepatocellular carcinoma. METHODS: Gene expression profiles of liver tissues from twelve hepatocellular carcinoma samples relative to the gene expression profile of the normal liver tissue were analyzed using 4096 chips and 12800 chips. The results of microarray experiments were verified by the Northern blot technique. RESULTS: A group of 1,820 genes with altered expression were identified in more than 50% of the patients examined. This highly concordant expression profile included human genes encoding proteins involved in the function of peroxisomes, serum control, polycyclic aromatic hydrocarbon carcinogenesis, cell growth and differentiation, metastasis, the function of the immune system, apoptosis, and remodeling of the cytoskeleton. CONCLUSIONS: The newly identified genes afford a quantitative view of the changes that accompany liver cancer at the genomic level, enable deeper insights into the molecular basis of disease, and provide an extensive list of potential early-onset molecular markers for improved diagnosis.

Adult↗
PubMed2002

CREB-binding protein/p300 co-activation of crystallin gene expression.

Although some of the transcription factors that are required for expression of crystallins during lens development have been identified, the molecular interactions that contribute to enhanced crystallin expression are not yet well defined. In this study, we designed experiments to test whether the co-activators CREB-binding protein (CBP) and/or p300 interact with c-Maf, Prox-1, or Sox-1 to enhance transcription of crystallin genes. Promoter regions from the mouse alphaA-, betaB2-, and gammaF-crystallin genes were linked to a luciferase reporter. Expression of c-Maf transactivated each of these promoters. Of particular interest, co-expression of CBP or p300 with c-Maf was found to synergistically co-activate each promoter. CBP and p300 were less effective or ineffective at co-activation with Prox-1 or Sox-1. Co-immunoprecipitation and mammalian two-hybrid experiments revealed that CBP and p300 bind to c-Maf and Prox-1 but not to Sox-1. The co-activation of c-Maf by CBP/p300 requires histone acetyltransferase activity. Our results suggest that c-Maf recruits CBP and/or p300 to crystallin promoters leading to up-regulation of crystallin gene expression through localized histone acetylation and consequent chromatin re-modeling. In a promoter-specific fashion, co-activation can be modulated by Prox-1 and/or Sox-1. This modulation may help to specify the endogenous levels of crystallin gene expression.

Acetyltransferases↗
PubMed2002

Inhibition of crystallin expression and induction of apoptosis by lens-specific E1A expression in transgenic mice.

Previous studies have shown that the adenovirus E1A oncoprotein can bind to and inactivate the retinoblastoma tumor suppressor protein (pRb) and the transcriptional coactivators CBP/p300. In this study, wild-type E1A12S or two deletion mutants (delN, which binds pRb but not CBP/p300; delCR2, which binds to CBP/p300 but not pRb) were linked to the lens-specific alphaA-crystallin promoter, and used to generate transgenic mice. Lens fiber cells expressing E1A12S or delCR2, both of which bind to CBP/p300, failed to upregulate beta-crystallin and gamma-crystallin expression. In contrast, lens fiber cells expressing delN showed significant expression of beta- and gamma-crystallins. Lens fiber cells expressing delN showed cell cycle entry, marked apoptosis, and evidence for p53 activation, while cells expressing either 12S or delCR2 showed limited apoptosis and no evidence for upregulation of the p53-inducible gene p21. Our results suggest that the transcriptional coactivators CBP and/or p300 are required for the dramatic increases in crystallin expression that accompany terminal differentiation in the lens, and also for activation of p53 in response to inactivation of pRb in the lens.

Acetyltransferases↗
PubMed2002

Retinal ablation and altered lens differentiation induced by ocular overexpression of BMP7.

The alphaA-crystallin promoter was used to target expression of bone morphogenetic protein 7 (BMP7) to lens fiber cells in transgenic mice. Surprisingly, lens-specific expression of BMP7 induced widespread apoptosis and rapid ablation of the neural retina in multiple families. Subsequent to retinal ablation, the lens bow region shifted posteriorly until lens epithelial cells completely enveloped the lens. Lens-specific expression of FGF3 was found to rescue the loss of fiber cell differentiation. Our results show that elevated BMP7 levels can induce rapid retinal degeneration accompanied by disruption of the endogenous ocular system for fiber cell induction.

Animals↗
PubMed2002

User fees impact access to healthcare for female children in rural Zambia.

The World Bank and International Monetary Fund favor healthcare user fees. User fees offer revenue and may decrease inappropriate care. However, user fees may deter needed care, especially in vulnerable populations. A cross-sectional analysis of healthcare utilization in a large Zambian hospital was conducted for children 3-6 years of age during a 1-month observation period. Diagnoses and treatments were compared using paired t-tests. Chi-squared tests compared outpatient service use. The relative risk of admission was determined for each stratum. Logistic models were developed to evaluate the impact of age, gender, and the age-gender interaction on hospital admissions. Trends suggest female children may be less likely to present for care when user fees are imposed. However, treatment type, treatment number, and number of diagnoses did not differ between genders. The relative risk of admission was highest for males 5-6 years old. Neither age nor gender alone was a significant determinant of hospital admission. However, the age-gender interaction was significant with female admissions least likely when costs were incurred. We conclude that user fees appear to decrease differentially utilization of inpatient care for female children in rural Zambia.

Ambulatory Care↗
PubMed2002

BMP signaling is required for development of the ciliary body.

The ciliary body in the eye secretes aqueous humor and glycoproteins of the vitreous body and maintains the intraocular pressure. The ciliary muscle controls the shape of the lens through the ciliary zonules to focus the image onto the retina. During embryonic development, the ciliary epithelium is derived from the optic vesicle, but the molecular signals that control morphogenesis of the ciliary body are unknown. We report that lens-specific expression of a transgenic protein, Noggin, can block BMP signaling in the mouse eye and result in failure in formation of the ciliary processes. Co-expression of transgenic BMP7 restores normal development of the ciliary epithelium. Ectopic expression of Noggin also promotes differentiation of retinal ganglion cells. These results indicate that BMP signaling is required for development of the ciliary body and may also play a role in regulation of neuronal differentiation in the developing eye.

Animals↗
PubMed2002

[Study on genomic diversity among different isolates of Schistosoma japonicum in China].

OBJECTIVE: To study genomic diversity among the isolates of Schistosoma japonicum in China. METHODS: Schistosome adults were collected from different endemic areas. Mitochondrial NADH dehydrogenase 1 (ND1) and cytochrome C oxidase 1 (CO1) gene fragments of the worms were amplified by PCR, cloned into plasmid, and finally sequenced. Program MEGA was used for sequence analysis. RESULTS: The ND1 and CO1 genes amplified from different geographic strains were 476 bp and 1,033 bp, respectively. There are two distinct haplotypes, type I and II, for both ND1 and CO1 nucleotide sequences. The differences between the two types were 4.0% and 3.4%. They are considered to be two different genetypes by the phylogenetic analysis. In individual mitochondrial gene, type I of ND1 was fixedly accompanied with type I of CO1 gene, and type II of ND1 with type II of CO1. CONCLUSION: There are two different genetypes of ND1 and CO1 genes of S. japonicum in China.

Animals↗
PubMed2002

[Sequence analysis of rDNA-LSU gene of Orientobilharzia turkestanicum from mainland of China].

OBJECTIVE: To classify the taxonomic status of O. cheni in relation to O. turkestanicum var. tuberculata from the mainland of China by comparing their nucleotide sequences of nuclear ribosomal partial large subunit gene (LSU). METHODS: The genomic DNA of adult worms were extracted by the GNT-K method. The target gene was amplified by PCR using specific primers. The PCR products were purified before ligation into the plasmid PCR-blunt (Invitrogen). Recombinant plasmids were amplified in E. coli, extracted and purified using routine methods and then sequenced using M13 primers (F/R) on a Licor long-read auto-sequencer. Sequences of O. turkestanicum was retrieved from GenBank and aligned with our data in BioEdit. RESULTS: The nucleotide sequences of LSU between O. turkestanicum var. tuberculata and O. cheni was 100% identical, and 99.99% identical between O. turkestanicum var. tuberculata and O. turkestanicum. CONCLUSION: This study demonstrated high similarity in LSU nucleotide sequences, and the results do not support O. cheni as an independent species. O. cheni may be a synonym of O. turkestanicum var. tuberculata, and O. turkestanicum var. tuberculata is probably also a synonym of O. turkestanicum.

Animals↗
PubMed1999

Dispersive X-ray Spectroscopy Analysis of Porous beta-TCP Bioceramics after Implantation into Femur.

In this paper, energy dispersive X-ray spectroscopy and element ratio of implanted bioceramic, interface and rabbit femur when the bioceramic implanted into femur were measured by two different scan electron microscopy (SEM) EDXA modes. The changes of element ratio and components of materials and interface implanted into femur were compared. Thorough studies were made on the transformation of TCP from lifeless materials into living bones after implantation, by using SEM-EDXA, Raman spectra and infrared spectra. These results provided rich evidence for understanding biodegration and bone bonding mechanism of calcium phosphate bioceramics.

Journal Article↗
PubMed1999

Raman Spectra of Porous beta-TCP Bioceramics Implanted into Rabbit Femur.

The Raman spectra of porous beta-TCP(beta-tricalcium phosphate)bioceramics implanted into rabbits femur the boundary and rabbit femur were studied using Raman spectroscopy(excited with 514.5nm and 623.8nm laser)and near-infrared FT-Raman spectroscopy. The Raman characteristic frequencies were assigned. The advantages and disadvantages of visible and near IR excitation are described. The Raman characteristic frequencies of calcium phosphate collagen protein and lipid(or phospholipid)were shown in the Raman spectra. These results demonstrated that besides calcium phosphate collagen protein and lipids also existed in the implants and the boundary forming components of organic bone tissues. Results indicated that the beta-TCP bioceramic when implanted into rabbit femur was partly dissolved and degraded the new bone tissues were formed on the surface and in pores of implanted bioceramics.

Journal Article↗
PubMed1997

Multiiron Polyoxoanions. Synthesis, Characterization, X-ray Crystal Structure, and Catalytic H(2)O(2)-Based Alkene Oxidation by [(n-C(4)H(9))(4)N](6)[Fe(III)(4)(H(2)O)(2)(PW(9)O(34))(2)].

A tetranuclear ferric Keggin sandwich-type heteropolyanion has been synthesized by the reaction of the lacunary species Delta-Na(8)H[PW(9)O(34)] with FeCl(2) followed by O(2) oxidation in nonaqueous media. The structure of [(n-C(4)H(9))(4)N](6)[Fe(III)(4)(H(2)O)(2)(PW(9)O(34))(2)].4CH(3)CN.2CH(2)Cl(2).2H(2)O (TBA-1) was determined by single-crystal X-ray diffraction (orthorhombic, Pbca; R = 0.0693 for 14 963 reflections with F(o) > 4sigma(F(o))). The compound was further characterized by infrared and UV-visible spectroscopy, electrochemistry, magnetic susceptibility, FAB mass spectrometry (FAB-MS), and elemental analyses. Five lines of evidence are consistent with the Fe(III)(4) oxidation state: (i) valence sum calculations from the X-ray structure (ca. 2.86 +/- 0.07 per Fe); (ii) the rest potential from cyclic voltammetry; (iii) charge balance requirements; (iv) titration with Ce(IV)(SO(4))(2); and (v) oxidation by O(2). In contrast to the tetranuclear ferric Wells-Dawson-derived sandwich complex, [Fe(III)(4)(H(2)O)(2)(P(2)W(15)O(56))(2)](12-), TBA-1 can only be prepared from a ferrous precursor. TBA-1 is a catalyst for the oxidation of hydrocarbons with H(2)O(2). The selectivity for epoxide is low (10-50%). Unlike most other transition-metal-substituted polyoxometalates (TMSPs), TBA-1 is very stable under turnover conditions in aqueous H(2)O(2) (no detectable changes in the IR or NMR spectra after 48 h). The rate of H(2)O(2) disproportionation catalyzed by TBA-1 is relatively low (the ratio of rates, disproportionation to oxidation, is ca. 3:2).

Journal Article↗
PubMedDate not supplied

Comparison of healthcare utilization and direct costs in three degenerative dementias.

The authors conducted a survey of healthcare utilization in three dementia syndromes to determine whether type of dementia influenced utilization or resulting direct costs. Patients with Alzheimer disease (n=131), dementia with parkinsonism (n=85), and Huntington disease (n=51) were identified from a registry and enrolled. Caregivers completed the mailed survey, and direct costs were estimated. The presence of dementia with parkinsonism resulted in significantly greater utilization of long-term care services and higher total direct costs. In all three groups, long-term care costs accounted for the majority of direct costs. Unique patterns of utilization and costs are seen in specific neurodegenerative dementias.

Aged↗