Biomedical subjects

Mei Zhang

Publications and source records attributed to Mei Zhang.

At least 55 records · Page 3Linked to original sources

PubMed2006

Growth-inhibitory effects of a beta-glucan from the mycelium of Poria cocos on human breast carcinoma MCF-7 cells: cell-cycle arrest and apoptosis induction.

Because of the reported immune-enhancing and anti-tumor activities of some mushroom polysaccharides, their applications as biological response modifiers have attracted significant attention. We have purified a water-soluble beta-glucan PCM3-II, comprising mainly 1right curved arrow 3 and 1right curved arrow 4 linkages, from the mycelia of Poria cocos (Schw.) Wolf (Fu-ling). In this study, the growth-inhibitory effect of PCM3-II was further explored on the human breast carcinoma MCF-7 cells in vitro. The dose effect of PCM3-II was studied by incubating the breast cancer cells with 12.5-400 microg/ml of the glucan for 72 h. The MTT study showed that PCM3-II reduced proliferation and viability of the MCF-7 cells dose-dependently, so that the cancer-cell growth was decreased by 50% of the control level at 400 microg/ml of the glucan. The time effect of PCM3-II was then investigated by treating the breast cancer cells with 400 microg/ml of the glucan for 24, 48 and 72 h, respectively. Results from the flow cytometry study demonstrated that PCM3-II induced cell-cycle G1 arrest time-dependently and about 90% of the cells in cell cycle were accumulated at G1 phase after 72 h of treatment. The G1 arrest was associated with downregulations of the unscheduled cyclin D1 and cyclin E expressions in the breast cancer cells. Apoptosis was also induced by PCM3-II in the MCF-7 cells, so that the subG1 cells in DNA histogram of the flow cytometry were elevated by 5-fold of the control level at 48 h and by 24-fold at 72 h of treatment. The immunoblot study also showed that the glucan induced depletion of the antiapoptotic Bcl-2 protein, but not the proapoptotic Bax protein, so that the Bax/Bcl-2 ratio was elevated in the breast cancer cells at the time when the most prominent apoptosis was also observed. In conclusion, although the detailed mechanism for the anti-tumor activity of the P. cocos beta-glucan still needs further investigation, this study provides preliminary insights into its mode of action and perspectives of its development as a water-soluble anti-tumor agent.

Apoptosis↗

PubMed2006

Effects of extract of dilong (pheretima) on the scalded skin in rats.

In order to investigate the effects of extract of Dilong (Pheretima) on the skin viability and lipid peroxidation after deep degree II scalds, the extract of Dilong (Pheretima) at two concentrations (5%, 10%) were respectively applied to the surface of wound. The oxygen consumption, the succinate dehydrogenase (SDH) activity, the Schiff's base content, and the healing time of wound surface were determined in Wistar rats at the 8th, 24th, 48th and 72th hour after scalds, with SD-Ag used as controls. The results indicated that the oxygen consumption and SDH activity decreased, and the schiff's base content increased after the scalds. After the application of the extract of Dilong, the oxygen consumption and SDH activity increased, and the schiff's base content decreased significantly as compared with the control group (P < 0.05 or P < 0.01), and the mean healing time of the wound surface was five days in advance in the two treatment groups as compared with the control group. It is suggested that the scalds are related with lipid peroxdation to a certain extent, and the extract of Dilong has actions of attenuating lipid peroxidation, and promoting healing of the wound.

Animals↗

PubMed2006

[Association of blood and cerebrospinal fluid IgG contents and severity of craniocerebral injury].

OBJECTIVE: To explore the association of blood and cerebrospinal fluid (CSF) IgG contents and the severity of craniocerebral injury. METHODS: Totalling 143 patients with craniocerebral injury were divided into 3 groups according Glasgow Coma Scale (GCS) scores, namely the mild injury group with GCS score of 12-15 (n=41), moderate injury group with GCS score of 9-11 (n=71) and severe injury group (GCS score 3-8, n=32). Another 9 patients with congenital hydrocephalus were also recruited as the control group. The CSF and blood samples were collected from these patients to measure the IgG contents 4 and 14 days and 1, 2, and 6 months after the injury, respectively. Physical disabilities of the patients were estimated with Rappaport's disability rating scale (DRS), whose correlations with CSF and blood IgG contents were analyzed. RESULTS: In the early stage of moderate to severe brain injury, the IgG content was lowered significantly in the blood but increased in CSF as compared with the control patients (P<0.05), and the changes in CSF and blood IgG displayed a significant correlation with the severity of the injury (r=0.950, P<0.01). During the recovery of severe brain injury, DRS score was in inverse correlation with blood IgG content but in positive correlation with CSF IgG content (Spearman's correlation coefficient of 0.800, P<0.05). CONCLUSION: In the early stage of brain injury, detection of blood IgG content may help with the assessment of the injury severity. During the recovery of the injury, dynamic monitoring of blood and CSF IgG contents provides clues of the outcome of the patients and benefit the modification of the treatment plan.

Adolescent↗

PubMed2006

[PPARgamma1 overexpression on caveolin-1 expression of Raw264.7 cells].

OBJECTIVE: To investigate the effect of PPARgamma1 gene overexpression on caveolin-1 mRNA and protein expressions in a murine macrophage cell line Raw264.7. METHODS: Replication-deficient recombinant adenovirus expression vector of PPARgamma1 was constructed using the AdEasy system. Raw264.7 cells were randomly treated as follows: P group (PPARgamma1 gene overexpression), T group (Troglitazone 40 micromol/L in DMSO), PT group (PPARgamma1 gene overexpression and Troglitazone) and control group. Changes of PPARgamma1 and caveolin-1 at mRNA and protein levels were investigated. RESULTS: Caveolin-1 expression can be detected by RT-PCR in Raw264.7, by immunocytochemistry method in cell and nuclear membrane but not by immunoblotting at protein level. Caveolin-1 expression at mRNA and protein levels in Raw264.7 were significantly higher in P, T and PT groups compared to control group and the expression was also significantly higher in PT group than that in P group and T group (P < 0.05). PPARgamma expression was significantly increased in PT group and P group where remained unchanged in T group compared to control group. CONCLUSION: PPARgamma1 overexpression can upregulate caveolin-1 expression in macrophages. Troglitazone upregulated caveolin-1 expression in the absence of increased PPARgamma1 expressions at mRNA and protein levels.

Adenoviridae↗

PubMed2006

[The role of atherosclerotic plaque stability and inflammation in the pathogenesis of acute coronary syndrome].

OBJECTIVE: To elucidate the effect of inflammation and coronary atherosclerotic plaque destabilization in the pathogenesis of acute coronary syndromes (ACS). METHODS: Twenty-eight patients with ACS and 13 patients with stable angina pectoris (SA) were examined by intravascular ultrasound (IVUS). Coronary plaque morphology and areas in culprit lesions were analyzed. The serum levels of hs-CRP, MMP-9, TIMP-1, sCD40L were also measured. RESULTS: Soft plaques were dominant in culprit lesions of ACS patients (71.4%, 20/28), and hard plaques were dominant in culprit lesions of SA patients [76.9% (10/13), P = 0.004]. At the culprit site, plaque area, plaque burden and remodeling index were all significantly larger in culprit lesions of ACS patients than those of SA patients (all P < 0.05). Positive remodeling was more frequent in ACS patients than in SA patients, whereas negative remodeling was more frequent in SA patients (P < 0.05). The serum levels of hs-CRP, MMP-9, sCD40L were higher in ACS group compared with SA group (P < 0.05, respectively). Moreover, hs-CRP level was positively correlated with MMP-9 (r = 0.671, P = 0.000) and sCD40L (r = 0.494, P = 0.008), respectively, in ACS patients. There was no difference in TIMP-1 between two groups (P = 0.234). CONCLUSIONS: These results suggest that structurally vulnerable plaques are essential element in the pathogenesis of ACS and inflammation might play an important role in plaque vulnerability.

Acute Coronary Syndrome↗

PubMed2006

[Experimental study on the phenotype of human embryonic lung fibroblasts transfected with Ad-BMP-2].

OBJECTIVE: To investigate the effects on the phenotype, especially the mineralization ability of human embryonic lung fibroblasts(HELFs) by transfection with adenovirus vector ecoding human bone morphogenetic protein-2 gene (Ad-BMP-2). METHODS: The HELFs were primarily cultured, then transfected with Ad-BMP-2. The morphologic characteristics of the cells were observed. The cell proliferation, alkaline phosphatase activities, BMP-2 protein expression, and the mineralization ability were detected with the methods of MTT, ALP staining, Western blot, and alizarin red S staining, respectively. RESULTS: After transfection, the shape of HELFs changed from silm spindle to multifigure, the cells became bigger than before. The colonies changed from unilaminar into multilaminar. The proliferation of HELFs was severely inhibited after transfection. An obvious BMP-2 lane was shown in Western blotting. Most cells presented positive in ALP staining, and large number of nacarat mineralized nodes were observed after alizarin red S staining. CONCLUSION: HELFs were capable of transforming into osteoblast-like phenotype, and were endowed with the ability of mineralization while being transfected with Ad-BMP-2.

Bone Morphogenetic Protein 2↗

PubMed2006

[Separation and determination of donepezil hydrochloride enantiomers in plasma by capillary electrophoresis].

AIM: To establish chiral separation method for donepezil hydrochloride (E2020) enantiomers by capillary electrophoresis (CE) and determine the two enantiomers in plasma. METHODS: Alkalized plasma was extracted by isopropanol-n-hexane (3 : 97) and L-butefeina was used as the internal standard. Enantioresolution was achieved using 2.5% sulfated-beta-cyclodextrin as chiral selector in 25 mmol x L(-1) triethylammonium phosphate solution (pH 2.5) on the uncoated fused-silica capillary column (70 cm x 50 microm ID). The feasibility of the method to be used as quantitation of E2020 enantiomers in rabbit plasma was also investigated. RESULTS: E2020 enantiomers were separated at a baseline level under the above condition. The linearity of the response was evaluated in the concentration range from 0.1 to 5 mg x L(-1). The linear regression analysis obtained by plotting the peak area ratio (A(s)/A(i)) of the analyte to the internal standard versus the concentration (C) showed excellent correlation coefficient (r = 0.999 2 for R(-)-E2020, r = 0.999 7 for S(+)-E2020) and the equations were A(s)/A(i) = 0.024 2 + 0.289 2C and A(s)/A(i) = 0.010 8 + 0.273 7C, respectively. The low limit of detection was 0.05 mg x L(_1). The inter- and intra-day precision (RSD) were all less than 20% . CONCLUSION: Compared with CSP by HPLC, the CE method is simple, reliable, inexpensive and suitable for studying the stereoseletive pharmacokinetics in rabbits.

Animals↗

PubMed2006

[Trans-membrane transport kinetic models in peritoneal dialysis].

The peritoneum is a biologic semi-permeable membrane. This article presents some kinetic models of fluid and solute trans-peritoneal transport in peritoneal dialysis including the membrane model, the three-pore model, the extended three-pore model and the distributed model. In these models different trans-peritoneal transport mechanisms were revealed. The three-pore model is emphasized.

Animals↗

PubMed2006

[A new sesqui-norlignan from Herpetospermum pedunculosum].

AIM: To study the chemical components from the bioactive extract of Herpetospermum pedunculosum, a Tibetan medicinal herb for liver diseases. METHODS: The isolation and purification of this extract were conducted by means of silica gels column chromatography and preparative HPLC. The structures of the compounds were elucidated based on their physical and chemical features, and spectral data. RESULTS: Two lignans were isolated from this extract. They were elucidated as herpetone (I), dehydrodiconiferyl alcohol (II). CONCLUSION: Compound I is a new compound with the rare structure of sesqui-norlignan. Compound II is isolated from the genus of Herpetospermum for the first time.

Chromatography, Gel↗

PubMed2006

[IL-10 gene modification on immature dendritic cells induces antigen-specific tolerance in experimental autoimmune myocarditis].

OBJECTIVE: To investigate whether IL-10 gene modification on immature dendritic cells (iDC) could induce autoimmune tolerance in rat experimental autoimmune myocarditis (EAM). METHODS: EAM was induced by cardiac myosin immunization on day 0 and day 7 in rats. A total of 2 x 10(6) mature DC (mDC), iDC, pcDNA3 transfected iDC, pcDNA3-IL-10 transfected iDC or PBS were injected intravenously at 5th immunization day. Three weeks later, echocardiography and HE staining were performed to observe the cardiac function and myocardial inflammation. Th1/Th2 cytokines were detected by ELISA and MHC-II molecules, costimulatory molecules were identified by flow cytometry. In vitro T lymphocyte proliferation assay and adoptive transfer of DCs were performed to determine the antigen specific tolerance induced by IL-10 gene modification on iDCs. RESULTS: EAM rats treated with pcDNA3-IL-10 transfected iDC showed improved cardiac function and reduced inflammatory cells infiltration into myocardium. Moreover, lower Th1 and higher Th2-type response was induced, MHC-II and costimulatory molecules down-regulated and antigen specific immunological responses towards cardiac myosin inhibited in pcDNA3-IL-10-iDC treated EAM rats. CONCLUSION: Treatment with IL-10 gene modified iDCs could ameliorates EAM by inducing Th2 polarization and down-regulation of MHC-II molecules and costimulatory molecule expressions.

Animals↗

PubMed2006

[Assessment methods and evolution on vitamin A status].

Vitamin A is one of nutrients which are indispensable to all people, especially children and pregnant women. In the world, severe vitamin A deficiency (VAD) has been controlled efficiently. But to many countries, especially those developing, subclinical or marginal vitamin A deficiency is still a public health problem. It is very important and necessary to assess the status of vitamin A of the population who are in risk of VAD before drawing and carrying out the intervention strategy. Currently, clinical, histological, functional and biochemical methods can be used to evaluate the level of vitamin A.

Animals↗

PubMed2006

Time course of age-dependent changes in intraocular pressure and retinal ganglion cell death in DBA/2J mouse.

PURPOSE: To characterizes the progression of glaucoma in DBA/2J mice by measuring intraocular pressure (IOP) and retinal ganglion cells (RGCs) numbers in mice of various ages. METHODS: A quantitative assessment of the pathophysiology of the DBA/2J mice was performed and the C57/BL6 mice was used as control. The IOP was measured by the servo-null micropipette system; the regional patterns of the loss of RGCs were determined by cell count of retrogradely-labeled RGCs. RESULTS: The baseline IOP for DBA/2J mice at 7 weeks was (16.6 +/- 1.2)mm Hg. Then IOP increased extend to 12 months, with the peak of (25.2 +/- 1.2)mm Hg at 6 months of age. Retinal ganglion cell numbers did not decrease relative to control until 12 months of age (P = 0.006), when the loss was proportionally higher in peripheral regions (P < 0.05). CONCLUSION: The elevation in IOP precedes the loss of RGCs by several months. RGCs cell loss occurs particularly in peripheral regions of the retina. These findings expand our understanding of the changes in DBA/2J mice and provide information for experiments design when they are used as a glaucoma model for future studies of RGCs degeneration in glaucoma.

Aging↗

PubMed2006

[Effects of interferon-gamma combined with all-trans retinoic acid on proliferation and differentiation of leukemia cell lines NB4 and MR2].

BACKGROUND & OBJECTIVE: More than 90% patients with acute promyelocytic leukemia (APL) achieve clinical complete remission by using all-trans retinoic acid (ATRA). However, the rapid development of ATRA-resistance has become a problem in treating APL. Many researches indicate that the mechanism of ATRA-resistance is related to lack of some proteins synthesized by interferon (IFN). This study was to explore the possibility and the possible mechanism of treating ATRA-resistant APL with IFN in combination with ATRA. METHODS: Interferon-gamma (IFNgamma) alone or IFNgamma combined with ATRA was used to treat ATRA-sensitive cell line NB4 and ATRA-resistant cell line MR2. Cell proliferation was tested by MTT assay. Light microscope and NBT test were used to evaluate cell differentiation. The expression of promyelocytic leukemia (PML) protein was observed by indirect immune fluorescent method. RESULTS: On the 8th day, the growth inhibition rates of NB4 cells and MR2 cells were significantly higher in combination group than in IFNgamma group and ATRA group (95.2% vs. 68.0% and 85.0%, P<0.05; 51.5% vs. 24.1% and 4.3%, P<0.05). On the 3rd day, the positive rates of NBT in NB4 cells and MR2 cells were significantly higher in combination group than in IFNgamma group and ATRA group (93.3% vs. 19.3% and 74.7%, P<0.05; 31.5% vs. 16.8% and 5.2%, P<0.05). After treatment of IFNgamma, the fluorescent particles in NB4 and MR2 cell nuclei were obviously increased as compared with those in control group. CONCLUSION: IFNgamma and ATRA have synergistic inhibitory effect on the proliferation of NB4 cells and MR2 cells, and can partially induce the differentiation of ATRA-resistant MR2 cells.

Antineoplastic Agents↗

PubMed2005

Stem cells in the etiology and treatment of cancer.

Using approaches first applied in human leukemias, recent progress has been made in the identification of putative cancer stem cells in several different carcinomas and other solid cancers. Additional studies have suggested that cancer stem cells may be derived not only from transformation of quiescent, long-term stem cells but also from short-lived progenitors that then obtain the ability to undergo self-renewal. Therefore, the heterogeneity observed in many types of human cancers may reflect the activation of specific oncogenes and/or loss of specific tumor suppressor genes and the different stem and/or progenitor cell populations in which these genetic or epigenetic events occur. Similarities have been observed in the pathways regulating stem cell homing and metastasis, and increasing evidence also suggests that treatment failure and the recurrence of human cancer may reflect the intrinsic quiescence and drug resistance of cancer stem cells.

Drug Resistance, Neoplasm↗

PubMed2005

[Effects of losartan, ramipril and their combination on left ventricular remodeling and function in spontaneous hypertensive rats].

OBJECTIVE: To evaluate the effects of losartan, an angiotensin receptor blocker, ramipril, an angiotensin converting enzyme inhibitor, and their combination on left ventricular remodeling and diastolic function in SHR at the same level of blood pressure. METHODS: Sixty-two SHRs and 20 WKYs were divided randomly into 5 groups: WKY-control group, SHR-control group, SHR-ramipril group, SHR-losartan group, and SHR-combination group. Twelve weeks after feeding, 6 rats from each group were randomly selected to undergo hemodynamic examination and then killed to undergo further examinations, and 24 weeks after the remaining rats underwent the same examinations. The hemodynamic examination included the systolic blood pressure (SBP) of the caudal artery, left ventricular systolic pressure (LVSP), left ventricle end diastolic pressure (LVEDP), maximum uprising velocity of left ventricle pressure (dP/dtmax), and maximum declining velocity of left ventricle pressure (-dP/dtmax), and tau. Then the hearts were taken out to measure the weight of heart, undergo pathological examination, measure the intracellular free calcium concentrations, hydroxyproline concentration, interstitial collagen volume fraction (CVF), perivascular collagen area/luminal area (PVCA/LA), the mRNA expression of SR Ca(2+)-ATPase, phospholamban and L-type calcium channel, and the protein levels of SR Ca(2+)-ATPase. The myocardial ultrastructure was analyzed by electron microscopy. RESULTS: The speed, extent, and sustained time of blood pressure decrease were better in the combination group than in the other 2 treatment groups. Twelve and 24 weeks after treatment the levels of LVM/BW in the combination group were significantly lower than those of the control group, however, without significant differences among the 3 treatment groups. The values of LVSP, LVEDP, and tau 12 and 24 weeks after treatment in the 3 treatment groups were all significantly lower and the levels of -dP/dtmax significantly higher than those of the control group (all P < 0.01). The values of CVF in the myocardium and PCVA/VA of the heart wall arteriole 12 and 24 weeks after in the 3 treatment groups were significantly lower than those of the control group, and the CVF in the myocardium 12 weeks after in the combination group was significantly than that of the ramipril group. Microscopy showed that the degree of myocardial fibrosis in the 3 treatment groups were significantly milder than those of the control group, and the ultrastructure improvement improved along with the lapse of time in the sequence of combination group > losartan group > ramipril group. The concentrations of hydroxyproline in cardiac muscle cells of the 3 treatment 12 and 24 weeks after were significantly than those of the control group and decreased gradually time-dependently. The expression of Ca(2+)-ATPase mRNA 24 weeks after of the ramipril, losartan, and combination groups were 53.5%, 72.9%, and 76.7% higher than that of the control group, and the Ca(2+)-ATPase protein expression of the 3 treatment groups were 28.9%, 33.3%, and 49.3% higher than that of the control group. The expression of L-type Ca(2+) channel mRNA of the 3 treatment groups were 51.8%, 76.8%, and 98.2% than that of the control group. CONCLUSION: Both losartan and ramipril reverse LVH and left ventricular diastolic dysfunction. A combination of these two drugs is more effective than single drug treatment for improvement of myocardial fibrosis and ultrastructure. All three-treatment groups can raise calcium-handling proteins mRNA and protein expressions, which may be the underlying molecular mechanisms for their therapeutic effects.

Angiotensin II Type 1 Receptor Blockers↗

PubMed2005

Determination of celecoxib in human plasma and breast milk by high-performance liquid chromatographic assay.

A rapid and simple HPLC assay was developed for the determination of celecoxib in human plasma and breast milk. After proteins were precipitated with acetonitrile, celecoxib was resolved on a C18 column and detected by UV detection at 254 nm. Standard curves were linear over the concentration range 10-2000 microg/L (r(2)>0.99). Bias was </=+/-15% from 20 to 2000 microg/L in both matrices, intra- and inter-day coefficients of variation (imprecision) were <10%, and the limit of quantification was 10 microg/L.

Celecoxib↗

PubMed2005

Lipopolysaccharide deacylation by an endogenous lipase controls innate antibody responses to Gram-negative bacteria.

T cell-independent type 1 agonists such as Gram-negative bacterial lipopolysaccharides can stimulate B lymphocytes to proliferate and produce antibodies by signaling through Toll-like receptors. This phenomenon is well established in vitro, yet polyclonal B cell responses after bacterial infection in vivo are often weak and short-lived. We show here that B cell proliferation and polyclonal antibody production in response to Gram-negative bacterial infection are modulated by acyloxyacyl hydrolase, a host enzyme that deacylates bacterial lipopolysaccharides. Deacylation of lipopolysaccharide occurred over several days, allowing lipopolysaccharide to act as an innate immune stimulant yet limiting the eventual amount of B cell proliferation and polyclonal antibody production. Control of lipopolysaccharide activation by acyloxyacyl hydrolase indicates that mammals can regulate immune responses to bacterial infection by chemical modification of a Toll-like receptor agonist.

Acetylation↗

PubMed2005

Dynamic conformational changes of extracellular S5-P linkers in the hERG channel.

The hERG channel has an unusually long 'S5-P linker' (residues 571-613) that lines the outer mouth of the pore. Previously, we have shown that residues along this S5-P linker are critical for the fast-inactivation process and K(+) selectivity of the hERG channel. Here we used several approaches to probe the structure of this S5-P linker and its interactions with other domains of the hERG channel. Circular dichroism and NMR analysis of a synthetic hERG S5-P linker peptide suggested that this linker is quite dynamic: its central region (positions 583-593) can be unstructured or helical, depending on whether it is immersed in an aqueous phase or in contact with a hydrophobic environment. Cysteine introduced into positions 583-597 of the S5-P linker can form intersubunit disulphide bonds, and at least four of them (at 584, 585, 588 and 589) can form disulphide bonds with counterparts from neighbouring subunits. We propose that the four S5-P linkers in a hERG channel can engage in dynamic conformational changes during channel gating, and interactions between S5-P linkers from neighbouring subunits contribute importantly to channel inactivation.

Amino Acid Sequence↗