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Biomedical subjects

Qi Zhang

Publications and source records attributed to Qi Zhang.

At least 73 records · Page 4Linked to original sources
PubMed2006

Focal cerebral ischemia alters the spatio-temporal properties, but not the amount of activity in mice.

Cerebral ischemia induces sensorimotor and cognitive dysfunctions in rodents; however, little is known about the changes in the spatio-temporal organization of locomotor activity after ischemia. In this study, we continuously assessed the spatio-temporal properties of locomotor activity in an enclosure (40 cm x 40 cm x 65 cm, arbitrarily divided into 16 zones) with feeding and drinking supplies, and observed the spatio-temporal changes in mice with focal cerebral ischemia. Locomotor tracks were recorded from 3rd to 24th h (total 22 h) after middle cerebral artery occlusion (MCAO) or sham operation. The absolute and relative distance traveled or time spent in different regions was analyzed. We found that there was no significant difference in total traveled distances over 22 h between the two groups. Control mice moved and stayed primarily in feeding and drinking zones, frequently in peripheral but rarely in central zones. However, ischemic mice lost such a property, almost evenly moved and stayed in 16 zones. Mice in both groups were more active (traveled more distances) shortly after they entered the enclosure, while ischemic mice returned to stable levels slower. The traveled distance had a remarkable circadian variation with more locomotion in the night in control mice, but not in ischemic mice. Most of the spatial parameters (ratios) of locomotor activity were closely correlated with the ischemic infarction, neuron densities (in cortex, hippocampal CA1 region and striatum), and typical behavioral assessments (neurological scores and inclined board test). Thus, these findings indicate that focal cerebral ischemia does not alter the amount of locomotor activity in mice, but impairs the spatio-temporal properties-prolonging the initial hyperactivity and losing regionally special distribution of the activity.

Analysis of Variance↗
PubMed2006

Solution structure and dynamics of human metallothionein-3 (MT-3).

Alzheimer's disease is characterized by progressive loss of neurons accompanied by the formation of intraneural neurofibrillary tangles and extracellular amyloid plaques. Human neuronal growth inhibitory factor, classified as metallothionein-3 (MT-3), was found to be related to the neurotrophic activity promoting cortical neuron survival and dendrite outgrowth in the cell culture studies. We have determined the solution structure of the alpha-domain of human MT-3 (residues 32-68) by multinuclear and multidimensional NMR spectroscopy in combination with the molecular dynamic simulated annealing approach. The human MT-3 shows two metal-thiolate clusters, one in the N-terminus (beta-domain) and one in the C-terminus (alpha-domain). The overall fold of the alpha-domain is similar to that of mouse MT-3. However, human MT-3 has a longer loop in the acidic hexapeptide insertion than that of mouse MT-3. Surprisingly, the backbone dynamics of the protein revealed that the beta-domain exhibits similar internal motion to the alpha-domain, although the N-terminal residues are more flexible. Our results may provide useful information for understanding the structure-function relationship of human MT-3.

Alzheimer Disease↗
PubMed2006

Five new iridoids from Patrinia rupestris.

Five new iridoids, namely rupesin A-E (1-5, resp.), together with six known iridoids, 6-11, were isolated from the roots of Patrinia rupestris. Their structures were elucidated by spectroscopic methods including IR, UV, MS, and 1D- and 2D-NMR experiments, and comparison with data of known analogues. Compounds 4 and 11, compounds 1, 2, 5, 6, 8, 9, and 10, and compounds 3, 4, and 8 showed significant antibacterial activities against Bacillus subtilis, Escherichia coli, and Staphylococcus aureus, respectively.

Anti-Bacterial Agents↗
PubMed2006

Increase of doxorubicin sensitivity for folate receptor positive cells when given as the prodrug N-(phenylacetyl) doxorubicin in combination with folate-conjugated PGA.

Folate receptor (FR) has been proposed as a promising target for tumor drug targeting. The aim of this study was to increase the chemo-sensitivity of FR-positive cells to doxorubicin by folate-directed enzyme prodrug therapy (FDEPT). Folate conjugated penicillin-G amidase was prepared and its ability to hydrolyze N-(phenylacetyl) doxorubicin was measured by HPLC. Fluorescence and confocal image analysis revealed that Folate-PGA can be specifically delivered into FR-positive HeLa and SKOV3 tumor cells. In vitro cytotoxity assays, IC50 was reduced with N-(phenylacetyl) doxorubicin versus doxorubicin for HeLa (3.1-fold reduction; p<0.001) and SKOV3 (3.3-fold reduction; p<0.001) when Folate-PGA was specifically bound to the cells. Complete activation was confirmed in HeLa and SKOV3 cells pretreated with free folic acid (1 mM), where the combination of N-(phenylacetyl) doxorubicin with Folate-PGA did not show any significant cell toxicity to the IC50 of doxorubicin. Pharmacokinetic clearance and biodistribution studies in vivo showed that 125I-Folate-PGA was cleared from blood within 24 h and had significantly higher tumor uptake compared to 125I-PGA (p<0.05). These results demonstrate that the FDEPT approach may be a potential promising strategy to improve chemotherapy-resistant cancers therapeutic ratio and warranted future studies.

Animals↗
PubMed2006

Optical and electrochemical detection techniques for cell-based microfluidic systems.

The ability to fabricate microfluidic systems with complex structures and with compatible dimensions between the microfluidics and biological cells have attracted significant attention in the development of microchips for analyzing the biophysical and biochemical functions of cells. Just as cell-based microfluidics have become a versatile tool for biosensing, diagnostics, drug screening and biological research, detector modules for cell-based microfluidics have also undergone major development over the past decade. This review focuses on detection methods commonly used in cell-based microfluidic systems, and provides a general survey and an in-depth look at recent developments in optical and electrochemical detection methods for microfluidic applications for biological systems, particularly cell analysis. Selected examples are used to illustrate applications of these detection systems and their advantages and weaknesses.

Biosensing Techniques↗
PubMed2006

Structural insights into the specific binding of huntingtin proline-rich region with the SH3 and WW domains.

The interactions of huntingtin (Htt) with the SH3 domain- or WW domain-containing proteins have been implicated in the pathogenesis of Huntington's disease (HD). We report the specific interactions of Htt proline-rich region (PRR) with the SH3GL3-SH3 domain and HYPA-WW1-2 domain pair by NMR. The results show that Htt PRR binds with the SH3 domain through nearly its entire chain, and that the binding region on the domain includes the canonical PxxP-binding site and the specificity pocket. The C terminus of PRR orients to the specificity pocket, whereas the N terminus orients to the PxxP-binding site. Htt PRR can also specifically bind to WW1-2; the N-terminal portion preferentially binds to WW1, while the C-terminal portion binds to WW2. This study provides structural insights into the specific interactions between Htt PRR and its binding partners as well as the alteration of these interactions that involve PRR, which may have implications for the understanding of HD.

Amino Acid Sequence↗
PubMed2006

Are American children and adolescents of low socioeconomic status at increased risk of obesity? Changes in the association between overweight and family income between 1971 and 2002.

BACKGROUND: A good understanding of the association between obesity and socioeconomic status (SES) has many important public health and policies implications, particularly for the prevention and management of obesity. OBJECTIVE: The objective was to examine secular trends in the relations between overweight (body mass index > or = 95th percentile) and SES. DESIGN: We examined secular trends in the relation between overweight and SES using nationally representative data collected in the National Health and Nutrition Examination Surveys (NHANES) between 1971 and 2002 for 30 417 US children aged 2-18 y. Poverty income ratio tertiles at each survey were used to indicate low, middle, and high SES. RESULTS: Considerable race, sex, and age differences were observed in the association between overweight and SES. A reverse association only existed in white girls; African American children with a high SES were at increased risk. Socioeconomic disparities in overweight have changed over time, with an overall trend of weakening. Compared with the medium-SES group, the adjusted odds ratios and 95% CIs were 0.79 (0.47, 1.33), 1.08 (0.73, 1.61), 1.24 (0.73, 2.09), and 1.04 (0.82, 1.33) in NHANES I, II, and III and in the 1999-2002 NHANES for the low-SES group and 0.66 (0.43, 1.00), 0.60 (0.35, 1.03), 0.42 (0.23, 0.76), and 0.99 (0.68, 1.43) for the high-SES group, respectively. Between 1988-1994 and 1999-2002, the ratio in the prevalence of overweight between adolescent boys with a low or high SES decreased from 2.5 to 1.1 and from 3.1 to 1.6 in girls. Consistently across almost all SES groups, the prevalence of overweight was much higher in blacks than in whites. CONCLUSIONS: Complex patterns in the association between SES and overweight exist. Efforts solely targeting reductions in income disparities probably cannot effectively reduce racial disparities in obesity.

Adolescent↗
PubMed2006

Comparative measurements of piezoelectric coefficient of PZT films by Berlincourt, interferometer, and vibrometer methods.

Chemical solution deposition (CSD) techniques were used to prepare lead zirconate (Zr) titanate (Ti) (PZT) thin films with Zr/Ti ratios of 30/70 and 52/48. Usually CSD processing is restricted to making crack-free, single-layer films of 70-nm thick, but modifications to the sol-gel process have permitted the fabrication of dense, crack-free, single layers up to 200 to 300 nm thick, which can be built-up into layers up to 3-microm thick. Thicker PZT films (> 2-microm single layer) can be produced by using a composite sol-gel/ceramic process. Knowledge of the electroactive properties of these materials is essential for modeling and design of novel micro-electromechanical systems (MEMS) devices, but accurate measurement of these properties is by no means straightforward. A novel, double-beam, common-path laser interferometer has been developed to measure the longitudinal (d33) piezoelectric coefficient in films; the results were compared with the values obtained by Berlin-court and laser scanning vibrometer methods. It was found that, for thin-film samples, the d(33,f) values obtained from the Berlincourt method are usually larger: than those obtained from the interferometer and the vibrometer methods; the reasons for this are discussed.

Electric Impedance↗
PubMed2006

Electrophysiological evidence for the interaction of substance P and glutamate on Adelta and C afferent fibre activity in rat hairy skin.

1. The purpose of the present study was to investigate whether there was a cooperative interaction between substance P (SP) and glutamate (GLU) administered subcutaneously on Adelta and C primary afferent fibre activity in dorsal hairy skin of the rat in vivo. The single unit activities of Adelta and C afferent fibres were recorded by isolation of fibre filaments from the dorsal cutaneous nerve branches and the effects of subcutaneous injections of low doses of SP, GLU and SP + GLU on activity were determined. 2. Sub-threshold doses of SP (1 micro mol/L, 10 microL) administered subcutaneously into the dorsal hairy skin had no effect on the afferent discharges of either Adelta or C units. 3. The afferent discharges of 35% (11/31) of Adelta fibres and 33% (6/18) of C fibres were increased by local injection of the submaximal doses of GLU (10 micro mol/L, 10 microL) into the receptive fields. 4. The GLU-induced excitatory response was significantly enhanced by coinjection of subthreshold doses of SP. The mean discharge rates of Adelta fibres and C fibres were increased from 5.84 +/- 1.54 and 5.02 +/- 2.65 impulses/min to 19.91 +/- 4.35 and 17.58 +/- 5.59 impulses/min, respectively, whereas the excitatory proportions of Adelta and C fibres were increased from 35 and 33% to 84 and 83%, respectively. The duration of the excitation for Adelta fibres and C fibres was also significantly increased after coinjection of SP + GLU compared with that observed when either substance was given alone. 5. The present study provides electrophysiological evidence for an interaction between receptors for SP and GLU on the fine fibres activities in rat hairy skin, which may be involved in the mechanisms of hyperalgesia.

Animals↗
PubMed2006

Chlorhexidine varnish for preventing dental caries in children, adolescents and young adults: a systematic review.

This systematic review aimed to determine the caries-inhibiting effect of chlorhexidine (CHX) varnishes on the permanent dentition of children, adolescents and young adults, and to explore two possibly related factors, namely application frequency and the time between evaluation and the last application. The literature search identified 14 publications of randomized controlled trials or controlled clinical trials where the effect of CHX varnish was compared with placebo controls or controls that received no preventive treatment. To obtain uniform outcome effects, the prevented fraction and 95% confidence intervals of caries increment were calculated. Owing to insufficient data presentation, only eight publications were included. Another two publications were included after receiving additional data from the authors. This systematic review did not result in a meta-analysis as an overall prevented fraction could not be computed because of the large variation of outcome results. The variation could not be explained by the time between evaluation and last application but might be explained by application frequency. It is tentatively concluded that CHX varnish has a moderate caries-inhibiting effect when applied every 3-4 months. However, this effect seems to have diminished by around 2 yr after the last application. There is no evidence for a caries-inhibiting effect of CHX varnish with longer intervals between applications.

Adolescent↗
PubMed2006

Tpc1808 increases expression of NF-H in PC12 cells.

Tpc1808 is a candidate chemotropic factor induced by nerve injury, and we report here the role of rat Tpc1808 in the expression of high-molecular-weight neurofilament (NF-H) in PC12 cells. A full-length Tpc1808 cDNA encoding the 275-amino-acid protein was constructed into pcDNA-HA and transfected into PC12 cells. The increased expression of NF-H was detectable in PC12-Tpc1808 clones by semi-qRT-PCR, real-time PCR, Western blot, and immunofluorescence. Such an increase could also be observed in PC12 cells subjected to recombinant Tpc1808 protein by real-time PCR and immunohistochemistry. At a concentration of 0.1 microg/mL, Tpc1808 protein, similar to NGF, could promote the expression of NF-H in a time-dependent manner. Our findings suggest that Tpc1808 is the gene related to promotion of nerve growth, and both the Tpc1808 gene and the Tpc1808 recombinant protein up-regulate the expression of NF-H in PC12 cells.

Amidohydrolases↗
PubMed2006

[Different expression and significance of VEGF and PCNA in aorta and pulmonary artery smooth muscle cells of rats with hypoxia pulmonary hypertension].

AIM: To study the expression of vascular endothelial growth factor (VEGF) and proliferating cell nuclear antigen(PCNA) in aorta and pulmonary artery smooth muscle cells of rats with hypoxia pulmonary hypertension(HPH). METHODS: The rat chronically HPH models were set up in the hypobaric hypoxia cabin. The experimental rats were divided into 3 groups: control group (rearing in a normoxia environment), two hypoxia groups (oxygen-deficient time being 2 weeks and 3 weeks, respectively). Expression of VEGF and PCNA were detected by immunohistochemical staining and image analysis. RESULTS: There was VEGF expression in vascular smooth muscle cells of aorta, pulmonary artery trunk and pulmonary arteriole in control group. In two hypoxia groups VEGF expression in vascular smooth muscle cells of pulmonary artery, trunk and pulmonary arteriole increased significantly, while no difference was found in smooth muscle cells of aorta. Expression of PCNA was very little in vascular smooth muscle cells of aorta, pulmonary artery trunk and pulmonary arteriole in control group. In two hypoxia groups, the PCNA expression increased only in vascular smooth muscle cells of pulmonary arteriole; there was no difference of PCNA expression in vascular smooth muscle cells of aorta and pulmonary artery trunk between hypoxia groups and control group. CONCLUSION: There is difference of VEGF expression in pulmonary artery trunk and aorta smooth muscle cells during the formation of chronic HPH, suggesting that VEGF expression may play very important role in the formation of chronic HPH.

Animals↗
PubMed2006

[Repair of peripheral nerve defect by a scroll of amnion derivative compound with cultured autogenous Schwann cell in a rat model].

OBJECTIVE: To test a nerve bridge substitute for peripheral nerve repair by tissue-engineering approach. METHODS: An artificial nerve fabricated with a scroll of amnion derivative (ZQ membrane) and cultured autogenous Schwann cell was sutured to bridge sciatic nerve defect of 2.5 cm in length in rats. The specimens were assessed with tracking study, histology, electrophysiological technique, NF200, and synaptophysin-38 (SYP) immuno histochemical staining 3 months postoperatively. RESULTS: The regenerated nerve sprouted 3 months after the operation. The regenerated nerve fibers were plentiful and could grow into the recipient nerve and target muscle's motor end plate (MEP) areas to reinnervate target muscle, and reconstruct function of nerve-muscle junction. Functional recovery could reach to 40%-60% of normal control. Nerve-muscle conduction velocity (N-MCV) arrived at 21.77 +/- 1.15 m/s. CONCLUSIONS: A tissue engineering material fabricated with a scroll of ZQ membrane and cultured autologous Schwann cell may be a useful substitute for nerve repair.

Amnion↗
PubMed2006

[Clinical study of continual jejunal interposition after subtotal gastrectomy].

OBJECTIVE: To explore the clinical effect of continual jejunal interposition in digestive tract reconstruction after subtotal gastrectomy. METHODS: Thirty-four patients with distal gastric cancer were divided randomly into two groups. In group A, the digestive continuity was reconstructed by continual jejunal interposition in 16 patients after subtotal gastrectomy. In group B, the digestive tract of other 18 cases were reconstructed by Billroth II procedure. The postoperative comp1ications, nutritional status, food intake and gastroscopic results were compared. RESULTS: There were no complications such as anastomotic leakage or obstruction in the two groups. The Visick scoring of group A was better than that of group B, and the difference was significant one year after operation (mu= 1.98, P< 0.05). All patients retrieved 85% of preoperative food intake per meal in group A, while only l4 patients got such results in group B. The weight loss was significantly higher in group B than that in group A(t = - 2.181, P= 0.037) after operation. The serum albumin level after operation in group A was significantly higher than that in group B (t=2.125, P=0.041), the level one year after operation in group A was also significantly higher than that before operation (t= - 2.175, P= 0.011). Gastroscopy one year after operation revealed fluent stoma,no bile reflux,and no congestion and edema in stomal mucosa and interposed jejunum in group A, while bile retention in 11 cases (61.1%), stomal inflammation in 13 cases (72.2%), and stomal ulcer in 2 cases (11.1%) in group B. CONCLUSION: Continual jejunal interposition after subtotal gastrectomy can recover physiological continuity of digestive tract and improve the quality of 1ife without reflux gastritis.

Digestive System Surgical Procedures↗
PubMed2006

[Mechanism of tau hyperphosphorylation in brain cortex of diabetic rats and effect of LiCl].

OBJECTIVE: To explore the mechanism of tau hyperphosphorylation and the effect of LiCl on tau phosphorylation and the memory retention deficits in streptozotocin-induced diabetes mellitus (DM) rats. METHODS: The rats were randomly divided into control, DM, DM + NaCl, and DM + LiCl groups and diabetes was induced by streptozotocin. The activity of glycogen synthase kinase-3 (GSK-3) was measured by 32P-labelling. The level of tau phosphorylated and changes of memory retention were examined by Western blotting and step down test, respectively. RESULTS: Compared with control group, the activity of GSK-3 and tau phosphorylation was increased, and the memory retention was impaired in DM group. When the rats were treated with LiCl, the activity of GSK-3 and hyperphosphorylation of tau were significantly arrested (P < 0.05, P < 0.01), and the memory retention deficit was significantly improved (P < 0.05). CONCLUSION: The hyperphosphorylation of tau can be induced by activation of GSK-3 in diabetic rats. Lithium protects tau from hyperphosphorylation and may rescue memory retention in the rats by inhibiting GSK-3 activity.

Animals↗
PubMed2006

[Relationship between glucocorticoid receptors in the peripheral blood lymphocytes and trabecular meshwork and glucocorticoid induced glaucoma].

OBJECTIVE: To measure the number of glucocorticoid receptors (GR) in the trabecular meshwork and peripheral blood lymphocytes of rabbits, and to explore their relationship with steroid-induced glaucoma. METHODS: Steroid-induced glaucoma model was induced by subconjunctival injection of 0.5 mg dexamethasone in the right eyes every two days for a month. Before the injection, GR concentration was measured in peripheral blood lymphocytes and trabecular meshwork of rabbits using the radio-ligand binding assay. GR concentration was measured again 30 days after the injection. The data was analyzed with SPSS software. RESULTS: The GR concentration in the peripheral blood lymphocytes and the trabecular meshwork of rabbits was (3642 +/- 947) site/cell and (2437.85 +/- 733.93) dmp/mg, respectively. The expression level in lymphocytes was significantly correlated with that in the trabecular (r = 0.862, P < 0.01). After treated with dexamethasone, the intraocular pressure of rabbits increased significantly, and the GR concentration in peripheral blood lymphocytes decreased significantly. Elevating level of IOP correlated positively with the primary and decreasing level of GR (r = 0.78, 0.79, P < 0.01). CONCLUSIONS: GR concentration in the peripheral blood lymphocytes of rabbits can reflect directly the GR number in the trabecular meshwork. There may be a close relationship between the GR number in peripheral blood lymphocytes and steroid-induced glaucoma.

Animals↗
PubMed2006

[The impact of expansion of sirolimus eluting stent on intimal hyperplasia: an intravascular ultrasound study].

OBJECTIVE: To assess the impact of expansion grade of sirolimus eluting stent on intimal hyperplasia with intravascular ultrasound (IVUS). METHODS: A total of 75 patients implanted with sirolimus eluting stents for at least 8 months were enrolled in this study and IVUS could be performed in 76 stents of 73 patients and 2 patients were excluded due to total coronary occlusion. External elastic membrane (EEM) cross-sectional areas (CSA) at stent inlet and outlet, at in-stent minimal CSA; in-stent CSA, cavity CSA, intimal area (in-stent area-cavity area), maximal and minimal diameter of stent, and symmetry index of stent (minimal diameter of stent/maximal diameter of stent) were measured. RESULT: Five out of 76 stents of 73 patients developed intimal hyperplasia and intimal proliferation was inhibited by sirolimus eluting stent in patients with either minimal stent CSA/EEM CSA < 0.5 (n = 56) or >or= 0.5 (n = 20), minimal stent CSA/reference CSA < 0.9 (n = 44) or >or= 0.9 (n = 32), minimal stent CSA < 5 mm(2) (n = 25) or CSA >or= 5 mm(2) (n = 51), symmetry index of stent at minimal CSA of stent < 0.9 (n = 37) or >or= 0.9 (n = 39) during IVUS follow up. CONCLUSION: Sirolimus eluting stent inhibited intimal hyperplasia independent of stent expansion grade.

Coronary Angiography↗