PubMed Health⌕ Search

Biomedical subjects

Yong Zhao

Publications and source records attributed to Yong Zhao.

At least 37 records · Page 2Linked to original sources
PubMed2006

Inhibition of cell growth and induction of G1-phase cell cycle arrest in hepatoma cells by steroid extract from Meretrix meretrix.

In this study, we report that the steroid extract 5alpha, 8alpha-epidioxycholest-6-ene-3beta-ol (MME) from Meretrix meretrix has the ability to inhibit growth of hepatoma cells and to induce G1-phase cell cycle arrest in two human hepatoma cell lines, HepG2 and Hep3B. HepG2 cells were more sensitive than Hep3B to MME. The extract markedly up-regulated the expression of p53 and p21WAF1/CIP1 in HepG2, suggesting that MME-induced G1 phase cell cycle arrest in HepG2 might be p53-dependent. Therefore, the up-regulation of p27KIP1and p16INK4A in both cell lines indicates that a p53-independent pathway might be involved in the mechanism of MME inducing cell cycle arrest. In conclusion, MME induces G1 phase cell cycle arrest via both p53-dependent and p53-independent pathways.

Bivalvia↗
PubMed2006

The macrophage heterogeneity: difference between mouse peritoneal exudate and splenic F4/80+ macrophages.

Macrophages isolated from various tissues manifest differences in cell shape, the expression of surface markers, as well as metabolic and functional activities. However, the heterogeneity of macrophages expressing the same marker in different tissues has not been fully addressed. In the present study, mouse F4/80+ peritoneal exudate macrophages (PEMs) and splenic macrophages (SPMs) appeared similar in most respects. But the percentages of cells expressing CD80, CD40, MHC-II, TLR2, or TLR4, but not CD11c, CD54, or CD23, in freshly isolated F4/80+ SPMs were significantly higher than those in PEMs, whereas the levels of CD86+ cells in F4/80+ SPMs were markedly lower than those in PEMs. After lipopolysaccharide (LPS) stimulation, F4/80+ SPMs expressed significantly higher levels of CD86, CD40, or MHC-II than F4/80+ PEMs, but not CD11c, CD80, CD54, or CD23. F4/80+ SPMs had remarkably lower non-opsonic phagocytotic capacity against chicken RBCs or allo-T cells than PEMs as determined by two-photon microscopes and flow cytometry. SPMs produced markedly more NO than PEMs when cultured with LPS or allo-T cells. Furthermore, SPMs exhibited stronger immunogenicity than PEMs, as determined by the ability to stimulate T cell proliferation, delayed type hypersensitivity, and IFN-gamma production. The data showed the differences between SPMs and PEMs with regard to the phenotypes, phagocytosis, and immunogenicity, which may offer important information for us to better understand the distinguished immune responses of macrophages in spleens and the peritoneal cavity.

Animals↗
PubMed2006

Does home internet use influence the academic performance of low-income children?

HomeNetToo is a longitudinal field study designed to examine the antecedents and consequences of home Internet use in low-income families (http://www.HomeNetToo.org). The study was done between December 2000 and June 2002. Among the consequences considered was children's academic performance. Participants were 140 children, mostly African American (83%), mostly boys (58%), and most living in single-parent households (75%) in which the median annual income was 15,000 (U.S. dollars) or less. Average age was 13.8 years. Ages ranged between 10 and 18 years, Internet use was continuously recorded, and multiple measures of academic performance were obtained during the 16-month trial. Findings indicated that children who used the Internet more had higher scores on standardized tests of reading achievement and higher grade point averages 6 months, 1 year, and 16 months later than did children who used it less. Older children used the Internet more than did younger children, but age had no effect on the nature or the academic performance benefits of Internet use. Implications for the digital "use" divide are discussed.

Black People↗
PubMed2006

Transforming growth factor-beta: an important role in CD4+CD25+ regulatory T cells and immune tolerance.

The transforming growth factor-beta (TGF-beta) protein family is highly evolutionarily conserved and they have been implicated in many biological processes. Also, TGF-beta can exert pivotal functions in the immune system. It is widely accepted that regulatory T cells (Treg cells) play an important role in the maintenance of the immune homeostasis, but the underlying molecular mechanisms through which they can gain and/or perform suppressive functions in an active way remains to be defined. Though the engagement of TGF-beta in the Treg cells has been discounted for a period of time, an emerging body of data has established a close link between Treg cells and TGF-beta, as TGF-beta has been demonstrated to induce the expression of Foxp3, which acts as a master regulator for the development and function of Treg cells. We will, herein, focus on the crucial role of TGF-beta signaling in Treg cell biology and summarize the current studies regarding TGF-beta in the generation and function of CD4+CD25+Treg cells both in vivo and in vitro.

Animals↗
PubMed2006

Automatic quantification of changes in bone in serial MR images of joints.

Recent innovations in drug therapies have made it highly desirable to obtain sensitive biomarkers of disease progression that can be used to quantify the performance of candidate disease modifying drugs. In order to measure potential image-based biomarkers of disease progression in an experimental model of rheumatoid arthritis (RA), we present two different methods to automatically quantify changes in a bone in in-vivo serial magnetic resonance (MR) images from the model. Both methods are based on rigid and nonrigid image registration to perform the analysis. The first method uses segmentation propagation to delineate a bone from the serial MR images giving a global measure of temporal changes in bone volume. The second method uses rigid body registration to determine intensity change within a bone, and then maps these into a reference coordinate system using nonrigid registration. This gives a local measure of temporal changes in bone lesion volume. We detected significant temporal changes in local bone lesion volume in five out of eight identified candidate bone lesion regions, and significant difference in local bone lesion volume between male and female subjects in three out of eight candidate bone lesion regions. But the global bone volume was found to be fluctuating over time. Finally, we compare our findings with histology of the subjects and the manual segmentation of bone lesions.

Algorithms↗
PubMed2006

Compatibility of porcine and human interleukin 2: implications for xenotransplantation.

BACKGROUND: Xenotransplantation provides a possible solution to the severe shortage of allogeneic organ donors. The pig, which shares many physiological similarities with humans, makes it an optimal species for preclinical experimentation and clinical applications. Interleukin 2 (IL2) is a potent growth factor secreted primarily by T helper lymphocytes and it is vital to the cellular expansion required for a productive immune response and the development and peripheral expansion of CD4+CD25+ regulatory T cells. Therefore, it is essential to understand of the compatibility of IL2 between pigs and humans. METHODS: We first compared the cDNA and protein sequences and the crystal structures of human and porcine IL2 and IL2 receptors, respectively. The effect of IL2 to induce T cell proliferation was determined by 3H-thymidine incorporation and cell cycle detection. RESULTS: Porcine IL2 induced very limited proliferation of human lymphocytes while it functioned well on porcine lymphocytes. Human IL2 had remarkably reduced effects on porcine lymphocytes whereas it worked well on human lymphocytes. CONCLUSION: Our present study showed that the interaction of IL2 and IL2R across species might have defects. Together with the wide physiological functions of IL2, our data indicated that physiological disorders could be caused by the poor function of xenogeneic donor IL2 on host cells in full hematopoietic chimera. Our data suggested an additional potential advantage for the mixed xenogeneic chimeras.

Amino Acid Sequence↗
PubMed2006

Induction of regulatory T cells from mature T cells by allogeneic thymic epithelial cells in vitro.

The ability of thymic epithelial cells (TEC) to re-educate mature T cells to be regulatory T cells has not been addressed. In the present study, this issue was directly investigated by co-culturing of mature T cells and allo-TECs. B6 macrophage cell line 1C21-cultured BALB/c splenocytes responded to B6 antigens in vitro. However, BALB/c splenocytes precultured with B6-derived TECs 1-4C18 or 1C6 did not proliferate to B6 antigens, but responded to rat antigens. Exogenous interleukin-2 (IL-2) failed to revise the unresponsiveness of these T cells. Allo-TEC-cultured T cells predominantly expressed Th2 cytokines (IL-4 and IL-10). B6 TEC-cultured BALB/c splenocytes markedly inhibited the immune responses of naïve BALB/c splenocytes to B6 antigens, but not to rat or the third-party mouse antigens. BALB/c nude mice that received naïve syngeneic splenocytes rejected B6 or rat skin grafts by 17 days postskin grafting; however, co-injection of B6 TEC-cultured BALB/c splenocytes significantly delayed B6 skin graft rejection (P < 0.01), with the unchanged rejection of rat skin grafts. These studies demonstrate that allo-TECs are able to 'educate' mature T cells to be regulatory cells, and suggest that regulatory cells derived from mature T cells by TECs may play an important role in T cell tolerance to allo- and auto-antigens.

Animals↗
PubMed2006

[An efficient method for DNA extraction from compost].

An efficient method for obtaining DNA from compost which contained high levels of organic matter was developed. The protocol consisted of washing with phosphate-EDTA before extraction, cell lysis with hot-SDS and enzymes (lysozyme, lywalzyme, proteinase K), removing humic acid and other inhibitors with PVPP and precipitation with PEG-8000. The compost total DNA was extracted from four different composts, the DNA yield was 63.54 +/- 12.08 to approximately 106.50 +/- 28.36 microg/g of dry compost. Molecular size of DNA obtained using this protocol was about 23kb and contained low protein and humic acid contamination with the A260/A280 ratios exceeding 1.6 and A260/A230 ratios reaching 1.8. Usually, additional purification steps such as agarose gel electrophoresis, gel permeation chromatography, or affinity chromatography were needed to get PCR-amplifiable DNA, but the DNA obtained using this protocol could directly be used to PCR-amplification and restriction enzyme digestion. Just like purity of DNA template, lower DNA yield also appears to introduce a bias towards lower community diversity. In this study compared the purified DNA the direct DNA reveals higher microbial community diversity assessed by denaturing gradient gel electrophoresis(DGGE) of amplified V3 region of 16S rDNA.

DNA, Bacterial↗
PubMed2006

[Effects of early intervention on learning and memory in young rats of marginal vitamin A deficiency and it's mechanism].

OBJECTIVE: In recent years, some experiments on vitamin A-deprived animals reveal a progressive and ultimately profound impairment of hippocampal CA1 area's long-term potentiation and these losses are fully reversible by dietary vitamin A replenishment in vivo. Our previous study revealed that marginal vitamin A deficiency (MVAD) beginning from embryonic period impairs learning, memory and long-term potentiation (LTP) in young rats. But the losses might not be reversible if the vitamin A supplementation is late, especially when the critical period of hippocampus development is missed. The present study aimed to observe the recovery of learning and memory in vitamin A marginally deficient young rats after early intervention with vitamin A supplementation and begin to study the mechanism. METHODS: Rats were divided into control, MVAD, vitamin A intervention 1 (VAI1) and VAI2 groups in this study. In control group (10 young rats) the dams and pups were fed with normal diet (VA 6500 U/kg). In MVAD group (19 young rats) the dams and pups were fed with MVAD diet (VA 400 U/kg). In VAI1 group (10 young rats) the dams were fed with MVAD diet till day 14 of pregnancy, then were fed with normal diet and the pups were fed with normal diet. In VAI2 group (13 young rats) the dams were fed with MVAD diet till delivery, then were fed with normal diet and the pups were fed with normal diet too. All the young rats were killed at the age of 7 weeks. During the last week of the experiment, the shuttle box active avoidance reaction tests were carried out. At week 7, the hippocampal CA1 LTP was detected by electrophysiological technique. The expression of RAR-alpha, RAR-beta, RXR-beta, RXR-gamma, RC3 and tTG mRNA was detected by using semi-quantified RT-PCR in hippocampus. RESULTS: (1) The times to reach the learning standard in MVAD group (45.6 +/- 12.1) were more than those in control group (17.1 +/- 4.4) (P < 0.01), in both VAI1 group (20.8 +/- 3.1) and VAI2 group (22.1 +/- 4.0) were more than those in group MVAD (P < 0.01), and there were no significant differences among groups VAI1, VAI2 and control (P > 0.05) in active avoidance reaction tests. (2) The changes of field excitatory postsynaptic potentials (fEPSP) slope for MVAD group [(22.9 +/- 9.4)%] and VAI2 group [(39.1 +/- 4.33)%] were less than that of control group [(57.5 +/- 27.3)%], respectively (P < 0.05). No significant difference was found between VAI1 and control group (P > 0.05). (3) The expression of RAR-beta and RXR-beta mRNA decreased by 48.72% and 37.84% respectively (P < 0.05) compared with control, but the expression of RAR-beta mRNA in group VAI1 was higher than that in group MVAD (P = 0.065). The expression of RC3 mRNA in MVAD group was lower than that in control (P = 0.061) and RAR-alpha mRNA in MVAD group was higher than that in control (P = 0.061). The expression of RXR-gamma and tTG mRNA had no significant difference among different groups as determined with semi-quantified RT-PCR in hippocampus. CONCLUSION: Early vitamin A intervention may make the impaired learning and memory behavior due to marginal vitamin A deficiency recover to the normal level in young rats, but lip losses in group VAI2 might not be reversible. Vitamin A may modulate the expression of RC3 mRNA by affecting RAR-alpha, RAR-beta and RXR-beta to influence the LTP, learning and memory.

Animal Nutritional Physiological Phenomena↗
PubMed2006

[Therapeutic efficacy of oxymatrine on arrhythmia and heart rate variability in patients with coronary heart disease].

OBJECTIVE: To evaluate the therapeutic efficacy of oxymatrine (Oxy) on arrhythmia and heart rate variability (HRV) in patients with coronary heart disease (CHD) by Holter electrocardiogram and HRV indexes. METHODS: One hundred and ten patients with CHD and frequent arrhythmia were randomly divided into the Oxy group and the propafenone group, 55 cases in each group. Changes of general conditions, 48 hrs Holter electrocardiogram, frequency of premature beats, P-R interval, R-R interval and 24 hrs HRV index in patients before and after treatment were evaluated. RESULTS: The amount of both atrial and ventricular premature beats decreased markedly in both groups (P < 0.01). Propafenone showed better effect in reducing atrial premature beats than that of Oxy (P < 0.05), while the two had similar effect on ventricular premature beats (P > 0.05). HRV was elevated in both groups after treatment (P < 0.01), but the effect of Oxy was superior to that of propafenone after treatment (P < 0.05). CONCLUSION: Oxymatrine could significantly improve HRV, and shows obvious effects on atrial and ventricular arrhythmia in patients with CHD.

Adult↗
PubMed2006

The phenotypic characterization of naturally occurring regulatory CD4+CD25+ T cells.

The homeostasis of the immune system depends on the balance between the immune response to an invaded pathogen and the immune tolerance to self antigens. Both central and peripheral tolerances are important mechanisms for the induction and maintenance of T cell tolerance. Recently, much attention has been paid to regulatory T cells (Treg), which play a significant role in maintaining peripheral immune tolerance. So far, there has been no satisfactory advance regarding the surface markers of Treg cells, as none is unique for Treg cells. In this review, we summarize some important molecules expressed in naturally occurring CD4+CD25+ Treg cells (nTreg), including forkhead/winged-helix family transcriptional repressor p3 (Foxp3), the tumor necrosis factor receptor (TNFR) family, CD28/CTLA4 molecules, chemokine receptors, Toll-like receptors (TLRs), membrane-bound TGF-beta and other molecules, such as neuropilin-1, lymphocyte activation gene-3 (LAG)-3 and granzyme. This review provides a collective view on current studies of nTreg cell activation and development related to the expression of molecules and cell phenotype markers, which is important for elucidation of nTreg cell origin, development and function.

Animals↗
PubMed2006

[A comparative Raman study of carbon nanotubes allays].

A series of comparative Raman study of carbon nanotubes arrays prepared by thermal chemical vapor deposition are reported. The results suggest that the G mode and D mode of carbon nanotubes (CNTs) arrays are all downshifted as compared to that of polycrystalline graphite, and the shifted number in well-aligned CNTs arrays is more than that in misaligned CNTs arrays. Moreover, the intensity ratio ID/IG indicates the ordering in CNTs arrays. A lower ID/IG means a higher graphitization and less amorphous carbon in CNTs arrays.

English Abstract↗
PubMed2005

[Transperitoneal laparoscopic enucleation of renal angiomyolipoma: a report of 10 cases].

OBJECTIVE: To evaluate the feasibility and clinical effect of transperitoneal laparoscopic enucleation of renal angiomyolipoma (RAML) without obstruction of renal pedicle. METHODS: Ten patients with renal angioleiomyoma (tumor diameter < 4 cm) were operated by transperitoneal laparoscopy without obstruction of renal pedicle. The operating time, blood loss, hospital stay after operation, intraoperative and postoperative complications and the operative effect were observed. RESULTS: All the 10 patients underwent the operation successfully. The average operating time was 90 min, average blood loss was 80 ml, the average hospital stay after operation was 7 d. No intraoperative or postoperative complications occurred. Follow-up period was 3-19 months and no tumor metastasized or occurred again. CONCLUSION: This mininvasive procedure is a more precise and complete method than before, which can minimize the blood loss and make patients recover quickly, so it is well worth clinical applying.

Adult↗
PubMed2005

Human umbilical cord blood-derived f-macrophages retain pluripotentiality after thrombopoietin expansion.

We have previously characterized a new type of stem cell from human peripheral blood, termed fibroblast-like macrophage (f-Mphi). Here, using umbilical cord blood as a source, we identified cells with similar characteristics including expression of surface markers (CD14, CD34, CD45, CD117, and CD163), phagocytosis, and proliferative capacity. Further, thrombopoietin (TPO) significantly stimulated the proliferation of cord blood-derived f-Mphi (CB f-Mphi) at low dosage without inducing a megakaryocytic phenotype. Additional experiments demonstrated that TPO-expanded cord blood-derived f-Mphi (TCB f-Mphi) retained their surface markers and differentiation ability. Treatment with vascular endothelial cell growth factor (VEGF) gave rise to endothelial-like cells, expressing Flt-1, Flk-1, von Willebrand Factor (vWF), CD31, acetylated low density lipoprotein internalization, and the ability to form endothelial-like cell chains. In the presence of lipopolysaccharide (LPS) and 25 mM glucose, the TCB f-Mphi differentiated to express insulin mRNA, C-peptide, and insulin. In vitro functional analysis demonstrated that these insulin-positive cells could release insulin in response to glucose and other secretagogues. These findings demonstrate a potential use of CB f-Mphi and may lead to develop new therapeutic strategy for treating dominant disease.

Antigens, CD↗
PubMed2005

Tolerance by selective in vivo expansion of foreign major histocompatibility complex-transduced autologous bone marrow.

BACKGROUND: Application of gene therapy to induce antigen-specific immune tolerance could be important for transplantation or treatment of autoimmune diseases. Hematopoietic stem cell-based gene therapy has been hampered by relatively weak gene expression in vivo and loss of transduced cells over time. Selective expansion of transduced hematopoietic stem cells has been accomplished by incorporating the dihydrofolate reductase (DHFR) gene into the gene transfer vector. METHODS: To assess whether this strategy could be applied to transplantation, we constructed a retroviral vector plasmid (KA274) containing the cDNA encoding human leukocyte antigen (HLA)-A2.1 and a tyr22 mutant DHFR and generated vesicular stomatitis virus-G-pseudotyped recombinant retrovirus by transfection into 293GPG cells. Bone marrow cells from C57BL/6 mice were infected with KA274 at a multiplicity of infection of 100, and transplanted into lethally irradiated syngeneic mice. RESULTS: After transplantation with transduced bone marrow, the proportion of peripheral blood cells expressing HLA-A2 ranged from 3.2% to 38% and increased 2- to 4.9-fold after selection for DHFR-expressing cells using trimetrexate and nitrobenzylmercaptpurine riboside 5' monophosphate. HLA-A2 expression remained above pretreatment levels throughout the study. Cytotoxic spleen cells from reconstituted mice lysed third-party HLA-B7-expressing targets but were unable to lyse HLA-A2-expressing targets. All KA274 reconstituted C57BL/6 mice accepted skin grafts from HLA-A2.1 transgenic mice for more than 245 days but rejected third-party Balb/c skin grafts in 12 days. CONCLUSION: Long-term transgene expression and immunologic tolerance to retrovirus-encoded HLA-A2, equivalent to that obtained by donor bone marrow transplantation, was accomplished, and selective expansion of transduced bone marrow cells was induced using DHFR as a selectable marker.

Animals↗
PubMed2005

Serum response factor regulates a muscle-specific microRNA that targets Hand2 during cardiogenesis.

Gradients of signalling and transcription factors govern many aspects of embryogenesis, highlighting the need for spatiotemporal control of regulatory protein levels. MicroRNAs are phylogenetically conserved small RNAs that regulate the translation of target messenger RNAs, providing a mechanism for protein dose regulation. Here we show that microRNA-1-1 (miR-1-1) and miR-1-2 are specifically expressed in cardiac and skeletal muscle precursor cells. We found that the miR-1 genes are direct transcriptional targets of muscle differentiation regulators including serum response factor, MyoD and Mef2. Correspondingly, excess miR-1 in the developing heart leads to a decreased pool of proliferating ventricular cardiomyocytes. Using a new algorithm for microRNA target identification that incorporates features of RNA structure and target accessibility, we show that Hand2, a transcription factor that promotes ventricular cardiomyocyte expansion, is a target of miR-1. This work suggests that miR-1 genes titrate the effects of critical cardiac regulatory proteins to control the balance between differentiation and proliferation during cardiogenesis.

Algorithms↗
PubMed2005

The effects of intrinsic pathway protease deficiencies on plasminogen-deficient mice.

Plasminogen (Plg)-deficient mice experience wasting and have decreased longevity due to disseminated fibrin deposition. We generated mice with combined deficiencies of Plg and coagulation factor IX (fIX) or XI (fXI) to determine the effects on the Plg null phenotype. Mice lacking Plg and fIX (Plg(-/-)/fIX-/-) have lower mortality at age 6 months than Plg(-/-)/fIX+/+ mice (15% and 67%, respectively) and less severe wasting, consistent with the importance of fIX in fibrin formation. In contrast, combined Plg and fXI deficiency (Plg(-/-)/fXI-/-) reduces life span (more than 90% mortality at 6 months) and is associated with leukocyte infiltration of the lungs and pulmonary fibrosis. These abnormalities are not seen in Plg-/- or Plg(-/-)/fIX-/- animals. Activated fXI is thought to function primarily as a fIX activator; however, our observation suggests that fXI may have functions in regulation of inflammation or tissue repair distinct from its role in coagulation.

Animals↗