Biomedical subjects

Hua Cao

Publications and source records attributed to Hua Cao.

At least 19 recordsLinked to original sources

PubMed2006

Systematic RNAi studies on the role of Sp/KLF factors in globin gene expression and erythroid differentiation.

Sp/KLF family of factors regulates gene expression by binding to the CACCC/GC/GT boxes in the DNA through their highly conserved three zinc finger domains. To investigate the role of this family of factors in erythroid differentiation and globin gene expression, we first measured the expression levels of selected Sp/KLF factors in primary cells of fetal and adult stages of erythroid development. This quantitative analysis revealed that their expression levels vary significantly in cells of either stages of the erythroid development. Significant difference in their expression levels was observed between fetal and adult erythroid cells for some Sp/KLF factors. Functional studies using RNA interference revealed that the silencing of Sp1 and KLF8 resulted in elevated level of gamma globin expression in K562 cells. In addition, K562 cells become visibly red after Sp1 knockdown. Benzidine staining revealed significant hemoglobinization of these cells, indicating erythroid differentiation. Moreover, the expression of PU.1, ETS1 and Notch1 is significantly down-regulated in the cells that underwent erythroid differentiation following Sp1 knockdown. Overexpression of PU.1 or ETS1 efficiently blocked the erythroid differentiation caused by Sp1 knockdown in K562 cells. The expression of c-Kit, however, was significantly up-regulated. These data indicate that Sp1 may play an important role in erythroid differentiation.

Cell Differentiation↗

PubMed2006

Definitive-like erythroid cells derived from human embryonic stem cells coexpress high levels of embryonic and fetal globins with little or no adult globin.

Human embryonic stem cells are a promising tool to study events associated with the earliest ontogenetic stages of hematopoiesis. We describe the generation of erythroid cells from hES (H1) by subsequent processing of cells present at early and late stages of embryoid body (EB) differentiation. Kinetics of hematopoietic marker emergence suggest that CD45+ hematopoiesis peaks at late D14EB differentiation stages, although low-level CD45- erythroid differentiation can be seen before that stage. By morphologic criteria, hES-derived erythroid cells were of definitive type, but these cells both at mRNA and protein levels coexpressed high levels of embryonic (epsilon) and fetal (gamma) globins, with little or no adult globin (beta). This globin expression pattern was not altered by the presence or absence of fetal bovine serum, vascular endothelial growth factor, Flt3-L, or coculture with OP-9 during erythroid differentiation and was not culture time dependent. The coexpression of both embryonic and fetal globins by definitive-type erythroid cells does not faithfully mimic either yolk sac embryonic or their fetal liver counterparts. Nevertheless, the high frequency of erythroid cells coexpressing embryonic and fetal globin generated from embryonic stem cells can serve as an invaluable tool to further explore molecular mechanisms.

Cell Differentiation↗

PubMed2006

[Early outcome of orthotopic heart transplantation: a report of 21 cases].

OBJECTIVE: To report the preliminary experience of 21 orthotopic heart transplantations without early death. METHODS: Between April 2002 and June 2005, 21 patients underwent orthotopic heart transplantation. Recipients' pulmonary vascular resistance ranged from 3.0 to 5.9 wood units [mean (4.3 +/- 1.4) wood units]; Stanford myocardial protective solution or HTK solution was perfused for donor heart myocardial preservation, donor heart cold ischemic period ranged from 52 to 310 min [mean (81 +/- 23) min]; Three patients had previous cardiac operations under cardiopulmonary bypass, conventional Stanford orthotopic cardiac transplantation in 20 cases and total heart technique in 1 case; Recipients received simulect preoperatively and cyclosporine A, cellcept and prednisone postoperatively for prevention of acute allograft rejection; Patients received appropriate medical control of hypertension, hyperglycemia, hypercholesterolemia and uricacidemia. RESULTS: Acute right heart failure in 3 cases and pericardial effusion in 4 cases were observed at the early postoperative stage, but no any infection and acute rejection were found. All patients survived with good life quality. CONCLUSIONS: Heart transplantation may produce satisfying early results. Suitable selection of recipients with low pulmonary vascular resistance, excellent donor heart conservation, practised anastomotic technique, proper immunosuppression treatment and efficient postoperative management are key measures of orthotopic heart transplantation with excellent early outcome.

Adolescent↗

PubMed2006

Histone deacetylase inhibitor FK228 is a potent inducer of human fetal hemoglobin.

We investigated the induction of the human fetal globin gene using five potent histone deacetylase (HDAC) inhibitors: FK-228, HC-Toxin, Trichostatin, MS-275, and Apicidin, using in vitro assays and cultures of primary human erythroblasts. The results showed that FK228 is the most potent inducer of fetal hemoglobin and exhibits its effects in picomolar concentrations. FK228 should be considered as a potential therapeutic for induction of fetal hemoglobin in patients with beta chain hemoglobinopathies.

Antibiotics, Antineoplastic↗

PubMed2006

Genome-scale mapping of DNase I sensitivity in vivo using tiling DNA microarrays.

Localized accessibility of critical DNA sequences to the regulatory machinery is a key requirement for regulation of human genes. Here we describe a high-resolution, genome-scale approach for quantifying chromatin accessibility by measuring DNase I sensitivity as a continuous function of genome position using tiling DNA microarrays (DNase-array). We demonstrate this approach across 1% ( approximately 30 Mb) of the human genome, wherein we localized 2,690 classical DNase I hypersensitive sites with high sensitivity and specificity, and also mapped larger-scale patterns of chromatin architecture. DNase I hypersensitive sites exhibit marked aggregation around transcriptional start sites (TSSs), though the majority mark nonpromoter functional elements. We also developed a computational approach for visualizing higher-order features of chromatin structure. This revealed that human chromatin organization is dominated by large (100-500 kb) 'superclusters' of DNase I hypersensitive sites, which encompass both gene-rich and gene-poor regions. DNase-array is a powerful and straightforward approach for systematic exposition of the cis-regulatory architecture of complex genomes.

Chromatin↗

PubMed2006

Effects of human gamma-globin in murine beta-thalassaemia.

Murine models of beta-thalassaemia have been used to test therapeutic globin gene vectors. However, the level of gamma-globin expression necessary to achieve full phenotypic correction in these models is unclear. In order to address this issue, we carried out breeding and transplantation studies in murine models of beta-thalassaemia intermedia (Hbb(th-3)/+) and severe beta-thalassaemia major (Hbb(th-3)/Hbb(th-3)) using transgenic lines expressing various levels of human gamma-globin. Expression of gamma-globin RNA at a modest 7-14% of total alpha-globin RNA resulted in the selective survival of HbF(+) erythrocytes, a fivefold increase in total HbF, and a phenotypic improvement in the beta-thalassaemia intermedia model. Full normalisation of erythrocyte indices in this model required gamma-globin RNA expression at 27% of alpha-globin, resulting in an average 40% (6.8 g/dl) HbF. Studies using the homozygous Hbb(th-3) model of lethal beta-thalassaemia major demonstrated that even this high level of gamma-globin expression, for reasons related to the function of the hybrid globin tetramers, could only prolong, but not fully support, survival. Taken together, these results indicate that only the heterozygous Hbb(th-3) model of beta-thalassaemia intermedia can be reliably used for the pre-clinical assessment of gamma-globin gene therapy vectors, as well as other means of gamma-globin gene induction.

Animals↗

PubMed2006

[Speaker identification based on Mel frequency cepstrum coefficient and complexity measure].

In present, the most basically used parameters for speaker identification are linear predictive coding (LPC) parameter, Mel frequency cepstrum coefficient(MFCC), etc. First in this paper only MFCC was used as the parameter and then Lempel-Ziv Complexity was combined with MFCC as parameters. The text-dependent recognition rate of 50 speakers increased from 42% to 80% and the text-independent recognition rate of 50 speakers increased from 60% to 72%. This test shows that Lempel-Ziv complexity, as a new parameter, can be applied to speaker identification.

Algorithms↗

PubMed2005

Hydroxamide derivatives of short-chain fatty acid have erythropoietic activity and induce gamma gene expression in vivo.

OBJECTIVE: The hydroxamic acid derivatives of short-chain fatty acids, butyryl and propionyl hydroxamate, subericbishydoxamic acid, and suberoylanilide hydroxamic acid, are potent inhibitors of histone deacetylase (HDAC) and have been shown to induce fetal hemoglobin in vitro. In this study we examined whether these compounds have erythropoietic activity and can induce gamma globin gene expression in vivo. MATERIALS AND METHODS: Transgenic mice heterozygous for a deletion beta thalassemia and hemizygous for a human gamma globin transgene were treated with these compounds and hematologic responses as well as the induction of gamma gene expression were evaluated. Hematologic studies included measurement of reticulocytes, hematocrit, and the in vivo levels of BFU-E. Effects on globin gene expression were assessed by measuring F reticulocytes and the human gamma/murine alpha globin mRNA ratios by RNAse protection assay. RESULTS: Propionyl and butyryl hydroxamate increased reticulocytes by 71% and 139%, the in vivo BFU-E counts by 75% and 51%, and the in vivo gamma gene expression by 33.9% and 71% respectively. SBHA and SAHA had no erythropoietic activity in vivo. CONCLUSION: Hydroxamic acid derivatives can stimulate the in vivo erythropoiesis and fetal globin production in a thalassemic murine model. The combined effect of certain histone deacetylase inhibitors on erythropoiesis and on gamma gene expression make these compounds desirable targets for development of therapeutics for beta chain hemoglobinopathies.

Animals↗

PubMed2004

Broadband generation of terahertz radiation in a waveguide.

We report a novel geometry that allows for the phase-matched generation of broadband terahertz radiation in a polymer-based parallel-plate metal waveguide by means of optical rectification. Both the optical pump beam and the generated terahertz radiation propagate in the fundamental mode of the waveguide. This allows for noncritical phase matching over a broad range of terahertz frequencies. We demonstrate guided-wave interaction lengths of up to 3 mm.

Journal Article↗

PubMed2004

Pharmacological induction of fetal hemoglobin synthesis using histone deacetylase inhibitors.

A number of pharmacological agents are currently available for the induction of the fetal hemoglobin (Hb F) to treat the patients with sickle cell disease and beta-thalassemia. In the present review, we summarized the investigation and development of these Hb F-inducing agents and introduced histone deacetylase inhibitors as the new strategy to induce Hb F to treat the hemoglobin disorders

Anemia, Sickle Cell↗

PubMed2003

Induction of human gamma globin gene expression by histone deacetylase inhibitors.

We investigated the induction of human gamma globin gene activity by 3 classes of histone deacetylase inhibitors: amide analogues of trichostatin A, hydroxamic acid analogues of trapoxin, and scriptaid and its analogues. The screening consisted of measuring the effects of these compounds on gamma and beta human gene promoter activity by using cultures of GM979 cells stably transfected with a construct containing a gamma promoter linked to firefly luciferase and a beta promoter linked to renilla luciferase. Compounds belonging to all 3 classes induced gamma gene promoter activity in the screening assay in low micromolar concentrations. Histone deacetylase (HDAC) inhibitors increased acetylation of histone H4 and induced the expression of endogenous murine embryonic genes. They also increased the levels of gamma mRNA and the frequency of fetal hemoglobin-containing erythroblasts in erythroid burst-forming unit (BFUe) cultures from healthy adult individuals. Compounds that displayed very similar degrees of inhibition of the HDAC activity in an HDAC enzymatic assay differed strikingly on their effects on gamma gene promoter activity, raising the possibility of selectivity of HDACs that interact with the gamma globin gene chromatin.

Amides↗

PubMed2003

Induction of umbilical cord blood mesenchymal stem cells into neuron-like cells in vitro.

Mesenchymal stem cells (MSCs) in human umbilical cord blood are multipotent stem cells that differ from hematopoietic stem cells. They can differentiate in vitro into mesenchymal cells such as osteoblasts and adipocytes. However, differentiation into nonmesenchymal cells has not been demonstrated. Here, we report the isolation, purification, expansion, and differentiation of human umbilical cord blood MSCs into neurocytes in vitro. Cord blood samples were allowed to drain from the end of the cord into glass bottles with 20 U/mL preservative-free heparin. MSCs were isolated from human umbilical cord blood, purified, and expanded in Mesencult medium. Surface antigens of MSCs were analyzed by fluorescence-activated cell sorting (FACS). MSC passages 2,5, and 8 were induced to differentiate into neuron-like cells. Neurofilament (NF) and neuron-specific enolase (NSE) were detected by immunohistochemistry staining. Special Nissl bodies were observed by histochemical analysis. The results showed that 6.6 x 10(5) primary MSCs were expanded for 10 passages to obtain 9.9 x 10(8) MSCs, an increase of approximately 1.5 x 10(3)-fold. FACS results showed that the MSCs did not express antigens CD34, CD11a, and CD11b and expressed CD29 and CD71, an expression pattern identical to that of human bone marrow-derived MSCs. Induction results indicated that approximately 70% of the cells exhibited a typical neuron-like phenotype. Immunohistochemistry staining suggested that induced MSCs of different passages expressed NF and NSE. Special Nissl bodies were obvious in the neuron-like cells. These results suggest that MSCs in human umbilical cord blood are capable of differentiating into neuron-like cells in vitro.

Cell Culture Techniques↗

PubMed2003

Prevalence of psychiatric disorder following the 1988 Yun Nan (China) earthquake--the first 5-month period.

BACKGROUND: There is a continuing need to examine the psychiatric impact of natural disasters for the development of an understanding of the determinants of morbid outcomes. The study of culturally distinct groups provides evidence as to the robustness of psychopathology emerging in the context of traumatic exposures. METHOD: In this study, 1294 people were examined at 5 months after the 1988 Yun Nan earthquake in order to explore the psychiatric impact of this disaster. They were assessed with a number of instruments, including the General Health Questionnaire (28-item version), the Life Event Inventory, and the Post-traumatic Stress Disorder section of the Diagnostic Interview Schedule. Three groups were examined according to their distance from the epicenter of the quake. Their responses were compared with an additional sample of 908 people from a general population living 520 kilometers away from the epicenter. RESULTS: GHQ 'caseness' in the three disaster groups, from those closest to those more distant from the epicenter, were 60.4, 48.2 and 44.0%. These rates were significantly higher than the non-exposed control group (36.2). Among the three disaster groups, taking those who achieved GHQ 'caseness' criteria, the PTSD prevalence was 23, 13 and 16%, respectively. For the overall population experiencing the earthquake (the combined disaster group), a conservative estimate of disaster-related PTSD prevalence was 8.9%. CONCLUSION: The varied rate of morbidity (both general and PTSD-specific) could be attributed to the relative impact of the earthquake as represented by epicenter proximity and as measured by the rate of property damage and loss in the three earthquake-affected areas.

Adolescent↗

PubMed2003

Hydroxamide derivatives of short-chain fatty acids are potent inducers of human fetal globin gene expression.

OBJECTIVE: To examine whether hydroxamic acids are inducers of fetal hemoglobin expression, we tested the effects on gamma gene expression of butyric and propionic hydroxamic acids and of two other hydroxamic acids (SBHA and SAHA), which are potent inhibitors of histone deacetylase (HDAC). We also investigated whether there is a correlation between HDAC inhibitory activity of the compounds and their ability to induce gamma-globin gene expression. MATERIALS AND METHODS: Effects on gamma-globin expression were assessed by two methods: 1) a screening assay in which specific gamma-globin gene inducers are recognized by their ability to increase gamma firefly luciferase activity significantly more than beta-renilla luciferase activity; and 2) measurements of gamma-globin mRNA and the frequency of fetal hemoglobin-positive erythroblasts in cultures of burst-forming unit erythroid (BFU-E) from normal individuals. HDAC in vitro activity was measured with a partially purified rat liver HDAC and a fluorogenic substrate. RESULTS: All compounds tested increased gamma firefly luciferase activity, gamma/gamma+beta mRNA ratios, and percentage of fetal hemoglobin-containing erythroblasts in BFU-E cultures, in a dose-dependent fashion. Butyryl-hydroxamic acid 100 microM increased the gamma/gamma+beta mRNA ratios by 5.8-fold and the frequency of fetal hemoglobin-containing erythroblasts by 4.1-fold. Propionyl-hydroxamic acid 150 microM increased the gamma/gamma+beta ratios by 6.3-fold and the fetal hemoglobin-containing erythroblasts by 3.9-fold. SBHA induced gamma-globin gene expression at very low concentrations, 5 to 20 microM in the luciferase system and 2 to 8 microM in BFU-E cultures; SAHA at 1 to 7.5 microM in the luciferase system and 1 to 2.5 microM in the BFU-E cultures. HDAC in vitro inhibition was observed in the millimolar range for propionate and butyrate. IC(50) determinations led to values of 384 microM for propionyl-hydroxamate, 47 microM for butyryl-hydroxamate, 0.93 microM for SBHA, and 0.26 microM for SAHA. CONCLUCION: Our data indicate that hydroxamic acid-based HDAC inhibitors are potent gamma-globin gene inducers and that the concentration range of their effects on gamma gene expression can be correlated roughly with their HDAC inhibitory potencies.

Animals↗

PubMed2002

Coumarins and pyranocoumarins, potential novel pharmacophores for inhibition of measles virus replication.

A series of coumarin and pyranocoumarin analogues were evaluated in vitro for antiviral efficacy against measles virus (MV), strain Chicago. Of the 22 compounds tested for inhibition, six were found to have selectivity indices greater than 10. These were compounds 5-hydroxy-7-propionyloxy-4-propylcoumarin (2a), 5,7-bis(tosyloxy)-4-propylcoumarin (7); 5-hydroxy-4-propyl-7-tosyloxy-coumarin (8); 6,6-dimethyl-9-propionyloxy-4-propyl-2H,6H-benzo[1,2-b:3,4-b']dipyran-2-one (9); 6,6-dimethyl-9-pivaloyloxy-4-propyl-2H,6H-benzo[1,2-b:3,4-b']dipyran-2-one (10); and 7,8-cis-10,11,12-trans-4-propyl-6,6,10,11-tetramethyl-7,8,9-trihydroxy-2H,6H,12H-benzo[1 ,2-b:3,4-b':5,6-b'']tripyran-2-one (18). Three of the active drugs were propyl coumarin analogues (2a, 7 and 8), two were dipyranone or chromeno-coumarins (9 and 10), and one was a benzotripyranone with a coumarin nucleus (18). Some appeared to be rather specific and potent inhibitors of MV with EC50 values ranging from 0.2 to 50 microg/ml and the majority of the EC50 values being less than 5 pg/ml. The compounds inhibited an additional nine strains of MV, and in virucidal tests the drugs did not physically disrupt the virion to inhibit virus replication. The inhibitory activity for one of the compounds tested (7) was somewhat dependent on virus concentration and it was still active when added to cells up to 24 h after virus exposure. When used in combination with ribavirin, compound 7 appeared not to profoundly affect the antiviral efficacy of ribavirin or its cell-associated toxicity. However, a slightly antagonistic MV-inhibitory effect was observed at the highest concentration of ribavirin used in combination with most concentrations of compound 7 tested. This and related compounds may be valuable leads in the development of a potent and selective class of MV inhibitors that could be used in future in the clinic.

Animals↗

PubMed2002

[Study of in vitro expansion and differentiation into neuron-like cells of human umbilical cord blood mesenchymal stem cells].

OBJECTIVE: To explore the isolation, purification and expansion of human umbilical cord blood mesenchymal stem cells (MSCs) into neuron-like cells in vitro. METHODS: Human cord blood samples were obtained sterilely with 20 U/ml preservative-free heparin. MSCs were isolated by lymphocyte separation medium (density 1.077 g/ml), and purified and expanded with Mesencult trade mark medium. The surface antigen expression of MSCs was detected by flow cytometry. The passage 2, 5 and 8 of the expanded MSCs were induced to differentiate to neuron-like cells. Specific markers and structures were detected by immunohistochemistry and histochemistry methods. RESULTS: The number of MSCs increased two- to three-fold with each expanded passage. 6.6 x 10(5) primary MSCs were expanded ten passages to reach a number of 9.9 x 10(8), and was increased about 1.5 x 10(3)-fold. Flow cytometry showed that MSCs did not express antigens CD(34), CD(11a) and CD(11b), but expressed strongly CD(29) and weakly CD(71), which was identical to human bone marrow-derived MSCs. 70% cells exhibited typical neuron-like phenotype after induction. Immunohistochemistry staining showed that all of the induced different-passage MSCs expressed neurofilament (NF) and neuron-specific enolase (NSE). Special Nissl body was found by histochemistry. CONCLUSION: MSCs in human umbilical cord blood can expand in vitro and differentiate into non-mesenchymal cells.

Antigens, CD↗

PubMed2002

[Construction of fetal mesenchymal stem cell cDNA subtractive library].

UNLABELLED: To identify differentially expressed genes between fetal mesenchymal stem cell (MSC) and adult MSC, especially specified genes expressed in fetal MSC, a cDNA subtractive library of fetal MSC was constructed using suppression subtractive hybridization (SSH) technique. At first, total RNA was isolated from fetal and adult MSC. Using SMART PCR synthesis method, single-strand and double-strand cDNAs were synthesized. After Rsa I digestion, fetal MSC cDNAs were divided into two groups and ligated to adaptor 1 and adaptor 2 respectively. Results showed that the amplified library contains 890 clones. Analysis of 890 clones with PCR demonstrated that 768 clones were positive. The positive rate is 86.3%. The size of inserted fragments in these positive clones was between 0.2 - 1 kb, with an average of 400 - 600 bp. CONCLUSION: SSH is a convenient and effective method for screening differentially expressed genes. The constructed cDNA subtractive library of fetal MSC cDNA lays solid foundation for screening and cloning new and specific function related genes of fetal MSC.

Cloning, Molecular↗

PubMed2002

[Progress on the study of tissue stem cells].

Stem cells in the individual life are the cell population with high self-renewal capacity and multiple differentiation potential. At present, embryonic stem cells and tissue stem cells are the major objects for study in the field of stem cell engineering. At the same time, with the development of tissue engineering, cell replacement therapy became a new approach to treat some diseases. Tissue stem cells were tried to expand and committedly induce in vitro to some cells that are needed, then implanted them into patients to repair damage, replace regressive tissue and improve the function of hereditarily defect tissue. Based on recent progress of research on stem cells, this paper reviewed the biological characters and clinic application prospects of tissue stem cells.

Animals↗