PubMed Health⌕ Search

Biomedical subjects

Ping Wang

Publications and source records attributed to Ping Wang.

At least 55 records · Page 3Linked to original sources
PubMed2006

Polyhedra formation and transient cone ejection of a resonant microdrop forced by an ac electric field.

New deformation or fission phenomena are reported for microdrops driven by an ac electric field at their resonant frequencies. The Maxwell forces that pull out the vertices from a drop can be enhanced when the ac frequency is comparable to both the drop resonant frequency and the inverse charge relaxation time of the diffuse layer. The selected polyhedra possess symmetries that ensure a global force balance of the Maxwell forces and a linear dimension consistent with a sphere whose nth harmonic (n is up to six in the observation) coincides with the applied ac frequency. At high voltages, the resonant focusing of charges by the vibration modes produces evenly distributed and transient Taylor cones that can eject charged nanodrops.

Acetonitriles↗
PubMed2006

The double lysine motif of tapasin is a retrieval signal for retention of unstable MHC class I molecules in the endoplasmic reticulum.

Tapasin (tpn), an essential component of the MHC class I (MHC I) loading complex, has a canonical double lysine motif acting as a retrieval signal, which mediates retrograde transport of escaped endoplasmic reticulum (ER) proteins from the Golgi back to the ER. In this study, we mutated tpn with a substitution of the double lysine motif to double alanine (GFP-tpn-aa). This mutation abolished interaction with the coatomer protein complex I coatomer and resulted in accumulation of GFP-tpn-aa in the Golgi compartment, suggesting that the double lysine is important for the retrograde transport of tpn from late secretory compartments to the ER. In association with the increased Golgi distribution, the amount of MHC I exported from the ER to the surface was increased in 721.220 cells transfected with GFP-tpn-aa. However, the expressed MHC I were less stable and had increased turnover rate. Our results suggest that tpn with intact double lysine retrieval signal regulates retrograde transport of unstable MHC I molecules from the Golgi back to the ER to control the quality of MHC I Ag presentation.

Alanine↗
PubMed2006

A review of statistical methods for expression quantitative trait loci mapping.

With high-throughput technologies now widely available, investigators can easily measure thousands of phenotypes for quantitative trait loci (QTL) mapping. Microarray measurements are particularly amenable to QTL mapping, as evidenced by a number of recent studies demonstrating utility across a broad range of biological endeavors. The early success stories have impelled a rapid increase in both the number and complexity of expression QTL (eQTL) experiments. Consequently, there is a need to consider the statistical principles involved in the design and analysis of these experiments and the methods currently being used. In this article we review these principles and methods and discuss the open questions most likely to yield significant progress toward increasing the amount of meaningful information obtained from eQTL mapping experiments.

Animals↗
PubMed2006

Seasonal and spatial distribution of nonylphenol in Lanzhou Reach of Yellow River in China.

Nonylphenol (NP) is known as an endocrine disruptor and consequently has drawn much environmental concern. This study focused on seasonal variation and spatial distribution of NP in various matrices including water, suspended particles, and sediment taken from Lanzhou Reach of Yellow River in China. NP was measured in July and November in 2004. Concentrations of NP in water ranged from 34.2 to 599.0 ng/l, in suspended particles from 49.6 to 2835.2 ng/g dry wt, and in sediment from 38.4 to 863.0 ng/g dry wt. In terms of most water and suspended particles samples, concentrations were higher in warmer seasons than in colder seasons. Good linear correlations (R(2)=0.90 in July, R(2)=0.97 in November) were obtained for NP concentrations between water and suspended particles. In terms of sediment samples, concentrations were higher in November than in July, probably due to greater deposition of suspended particles. Reasonable linear correlations (R(2)=0.60 in July, R(2)=0.79 in November) were obtained for NP concentrations between water and sediment.

China↗
PubMed2006

Evaluation of blood pressure changes using vascular transit time.

Imbalance of the human haemodynamic system can provide a prognosis of syncope, dizziness or hypertension. This can be assessed by monitoring its responses to postural change. Examining variations in blood pressure (BP) is deemed an effective means to identify symptoms of this associated condition. However, conventional methods do not promote prolonged monitoring due to the discomfort caused to patients. Established correlations between BP and pulse wave transmission have shown its usefulness in clinical applications. In this study, photoplethysmography and phonocardiography were used to estimate BP changes via observed variations in delay transmission or vascular transit time (VTT) at the upper limb. Thirty-one healthy adults (21 male) were recruited to perform three test activities, namely the arm held at heart level, fully raised up and held down. Association of the three BP indices and heart rate variations with transit time changes was then computed. The results showed that observed VTT changes were related to systolic BP (R(2) = 0.820; p < 0.05), diastolic BP (R(2) = 0.517; p < 0.05), mean arterial pressure (R(2) = 0.673; p < 0.05) and heart rate (R(2) = 0.000; p > 0.05). As systolic BP had the strongest correlation, a regression equation was formulated to associate the two parameters. The non-invasive measuring nature of VTT can be more accommodating to patients, especially during continual monitoring. Moreover, it has the added advantage that the pre-ejection period is not included in its time-related derivations.

Adult↗
PubMed2006

Relationship between neural, vascular, and BOLD signals in isoflurane-anesthetized rat somatosensory cortex.

Functional magnetic resonance imaging (fMRI) in anesthetized rodents has been commonly performed with alpha-chloralose, which can be used only for terminal experiments. To develop a survival fMRI protocol, an isoflurane (ISO) -anesthetized rat model was systematically evaluated by simultaneous measurements of field potential (FP) and cerebral blood flow (CBF) in the somatosensory cortex. A conventional forepaw stimulation paradigm with 0.3 ms pulse width, 1.2 mA current, and 3 Hz frequency induced 54% less evoked FP and 84% less CBF response under ISO than alpha-chloralose. To improve stimulation-induced responses under ISO, 10-pulse stimulations were performed with variations of width, current, and frequency. For widths of 0.1-5.0 ms and currents of 0.4-2.0 mA, evoked FP and CBF increased similarly and reached a plateau. The evoked FP increased monotonically for intervals from 50 to 500 ms, but the CBF peaked at an interval of 83 ms (approximately 12 Hz frequency). These data suggest that different anesthetics profoundly affect FP and CBF responses in different ways, which requires optimizing stimulation parameters for each anesthetic. With the refined stimulation parameters, fMRI consistently detected a well-localized activation focus at the primary somatosensory cortex in ISO-anesthetized rats. Thus, the ISO-anesthetized rat model can be used for cerebrovascular activation studies, allowing repeated noninvasive survival experiments.

Anesthetics, Inhalation↗
PubMed2006

Mucopolysaccharidosis I cats mount a cytotoxic T lymphocyte response after neonatal gene therapy that can be blocked with CTLA4-Ig.

Although gene therapy has reduced manifestations of genetic diseases, immune responses can abrogate the effect. One approach to inducing tolerance is to perform gene transfer in newborns when the immune system is immature. We demonstrate here that the dose of retroviral vector (RV) is important in mice, as mucopolysaccharidosis I (MPS I) mice that received neonatal intravenous gene therapy with a high dose of a canine alpha-L-iduronidase (cIDUA)-expressing RV had stable expression, while those that received a low dose did not. It was unclear, however, if neonatal transfer with any dose could induce tolerance in large animals. Therefore, newborn MPS I cats were injected intravenously with the RV expressing cIDUA. Although this resulted in high serum IDUA activity due to secretion by transduced cells, expression fell due to a CTL response. Cats that transiently received the immunosuppressive agent CTLA4-Ig did not develop a CTL response. In contrast, MPS I dogs, which can respond immunologically to canine IDUA, had stable serum IDUA activity after neonatal gene therapy. We conclude that cats, but not dogs, mount a potent CTL response to canine IDUA after neonatal gene therapy, which can be prevented with transient CTLA4-Ig.

Abatacept↗
PubMed2006

Microporous metal-organic framework constructed from heptanuclear zinc carboxylate secondary building units.

A novel, three-dimensional, noninterpenetrating microporous metal-organic framework (MOF), [Zn7O2(pda)5(H2O)2]5 DMF4 EtOH 6 H2O (1) (H2PDA=p-phenylenediacrylic acid, DMF=N,N-dimethylformamide, EtOH=ethanol), was synthesized by constructing heptanuclear zinc carboxylate secondary building units (SBUs) and by using rigid and linear aromatic carboxylate ligands, PDA. The X-ray crystallographic data reveals that the seven zinc centers of 1 are held together with ten carboxylate groups of the PDA ligands and four water molecules to form a heptametallic SBU, Zn7O4(CO2)10, with dimensions of 9.8 x 9.8 x 13.8 A3. Furthermore, the heptametallic SBUs are interconnected by PDA acting as linkers, thereby generating an extended network with a three-dimensional, noninterpenetrating, intersecting large-channel system with spacing of about 17.3 A. As a microporous framework, polymer 1 shows adsorption behavior that is favorable towards H2O and CH3OH, and substantial H2 uptake. In terms of the heptanuclear zinc carboxylate SBUs, polymer 1 exhibits interesting photoelectronic properties, which would facilitate the exploration of new types of semiconducting materials, especially among MOFs containing multinuclear metal carboxylate SBUs.

Journal Article↗
PubMed2006

Embryonic stem cells as a novel cell source of cell-based biosensors.

To investigate the use of embryonic stem cells as biosensor elements, mouse embryoid bodies were cultured on the surface of the light-addressable potentiometric sensor and induce to in vitro differentiate into cardiomyocytes and neurons. Extracellular potentials of the cells were recorded by sensor, to detect stem cells potential applications in drugs screening. The experimental results show that known cardiac stimulants (isoproterenol) and relaxants (carbamylcholine) have characteristic effects on the cardiomyocytes in terms of the changes of beat frequency, amplitude and duration. Thus, the embryonic stem cells potentially represent a renewable cell source for the cell-based biosensors.

Action Potentials↗
PubMed2006

[Effects of cyclin dependent protein kinase inhibitor olomoucine on the microenvironment of axonal regeneration after spinal cord injury: an experiment with rats].

OBJECTIVE: To investigate the effects of olomoucine, a cyclin dependent protein kinase (CDK) inhibitor, on the microenvironment of axonal regeneration after spinal cord injury (SCI). METHODS: Forty-five SD rats were randomly divided into 3 equal groups: SCI group undergoing SCI by hemisection technique and peritoneal injection of dimethyl sulfoxide (DMSO) solution 30 min after the SCI, SCI + olomoucine (SCI + Olo) group undergoing SCI by hemisection technique and peritoneal injection of olomoucine solution 30 min after the SCI, and sham operation group undergoing sham operation and peritoneal injection of DMSO solution 30 min after the operation. Three days after the operation the injured spinal cord segments of 5 rats from each group were taken out. Western blotting was used to detect the expression of the cell cycle related proteins, cyclin A, cyclin B, cyclin E, and proliferating cell nuclear antigen (PCNA). Immunofluorescence (IF) staining was used to detect the expression of glial fibrillary acidic protein (GFAP), growth associated protein-43 (GAP-43) and chondroitin sulphate proteoglycan (CSPG). Four weeks after the operation specimens of the injured spinal cord segment 15 mm in length were taken out from 5 rats in each group to undergo histological examination. The locomotion function of the hindlimbs was determined by modified Gale combined behavioral scoring (SBS) 1 day and 1, 2, 4, 6, and 8 weeks after the operation. RESULTS: Western blotting 3 days after the operation showed that the expressions of cyclin A, cyclin B, cyclin E, and PCNA were very weak in the sham operation group, were significantly increased in the SCI group, and were significantly down-regulated in the SCI + Olo group compared with those of the SCI group. IF staining showed that the number of astrocytes was small and the expressions of GFAP, CSPG, and GAP-43 were weak in the sham operation group; in the SCI group the astrocytic proliferation and glial scar was obvious, and the expressions of GFAP, CSPG, and GAP-43 were significantly increased compared with those of the sham operation group (all P < 0.05); and the astrocytic proliferation was significantly weaker and no obvious glial scar could be seen, and the expressions of GFAP and CSPG were weaker in the SCI + Olo group in comparison with the SCI group, however, the GAP-43 expression of the sham operation group was significantly increased compared with that of the sham operation group (P < 0.05). The hindlimbs of the SCI + Olo group and sham operation group were paralyzed without significant difference in the CBS values between these 2 groups, however, two weeks after the operation, the locomotion function scores at different time points of the SCI + Olo group were all significantly improved in comparison with that of the SCI group (all P < 0.05). CONCLUSION: Olomoucine promotes the recovery of the locomotion function of the paralyzed hindlimbs, probably through microenvironmental improvement of axonal regeneration by inhibiting the glial scar formation and CSPG secretion as well as upregulating the GAP-43 expression.

Animals↗
PubMed2006

Olfactory cell-based biosensor: a first step towards a neurochip of bioelectronic nose.

Human olfactory system can distinguish thousands of odors. In order to realize the biomimetic design of electronic nose on the principle of mammalian olfactory system, this article reports an olfactory cell-based biosensor as a real bionic technique for odorants detection. Effective cultures of olfactory receptor neurons and olfactory bulb cells have been achieved on the semiconductor chip. Using light-addressable potentiometric sensor (LAPS) as sensing chip to monitor extracellular potential of the neurons, the response under stimulations of the odorants or neurotransmitters, such as acetic acid and glutamic acid, was tested. The results demonstrate that this kind of hybrid system of LAPS and olfactory neurons, which is sensitive to odorous changes, has great potential and is promising to be used as a novel neurochip of bioelectronic nose for detecting odors.

Animals↗
PubMed2006

Zinc(II) and copper(II) complexes of beta-substituted hydroxylporphyrins as tumor photosensitizers.

Novel photosensitizers beta-(hydroquinon-2-yl)-5,10,15,20-tetra(4-hydroxylphenyl)porphyrinato zinc(II) (Zn(II)P) and beta-(hydroquinon-2-yl)-5,10,15,20-tetra(4-hydroxylphenyl)porphyrinato copper(II) (Cu(II)P) were synthesized and characterized. Their ability of producing singlet oxygen under irradiation was detected by the measurement of decomposition of 1,3-diphenylisobenzofuran (DPBF). The preliminary biological activity studies show that the Zn(II)P has photo-toxicity on human chronic myelogenous leukemia cell (K562) and could cleave supercoiled DNA (pBR 322 DNA), while the Cu(II)P has inferior biological activity. Results showed Zn(II)P having high anti-tumor activity, which presents a promising photosensitizer for photodynamic therapy.

Antineoplastic Agents↗
PubMed2006

The novel human gene MIP functions as a co-activator of hMafF.

The human transcription factor MafF (hMafF) lacks a transactivation domain, it contains a heptad-leucine repeat motif (viz., Leu-zipper) that may mediate protein-protein interactions to regulate transcriptional activities. A protein with a coiled-coil domain encoded by a novel human gene (GenBank Accession No. AF289559) was found to interact with hMafF in vitro and in vivo and is designated as a MafF interacting protein (MIP). Here, we provide evidence that the coiled-coil domain of MIP is essential for binding to the Leu-zipper of hMafF and that the interaction between MIP and hMafF causes the translocalization of MIP from cytoplasm to nucleolus in HELA cells. We used a promoter-reporter system containing six tandem repeats of the US2 element, located in the promoter of the human oxytocin receptor gene and reported to bind specifically to hMafF, to understand effects on transcriptional activation of hMafF, and its interaction with MIP. Expression of hMafF or MIP alone did not alter basal reporter transcription activity, whereas co-expression of hMafF and MIP activated transcription efficiently. Moreover, truncated MIP, still containing the coiled-coil domain, transactivated as well as the full-length MIP did, and highlighting that MIP acts as a co-activator of hMafF.

Amino Acid Sequence↗
PubMed2006

DNA hydrolysis promoted by 1,7-dimethyl-1,4,7,10-tetraazacyclododecane.

Several acyclic and macrocyclic polyamines were evaluated for their ability to cleave DNA. 1,7-Dimethyl-1,4,7,10-tetraazacyclododecane (DMC) could hydrolyze double-strand DNA at a concentration of 25microM. pH 7.2 was the optimal condition to cleave DNA in the presence of DMC. Supercoiled DNA hydrolytic cleavage by DMC was supported by the evidence from free radical quenching and T4 ligase ligation.

DNA↗
PubMed2006

CXCR3 chemokine receptor-induced chemotaxis in human airway epithelial cells: role of p38 MAPK and PI3K signaling pathways.

Human airway epithelial cells (HAEC) constitutively express the CXC chemokine receptor CXCR3, which regulates epithelial cell movement. In diseases such as chronic obstructive pulmonary disease and asthma, characterized by denudation of the epithelial lining, epithelial cell migration may contribute to airway repair and reconstitution. This study compared the potency and efficacy of three CXCR3 ligands, I-TAC/CXCL11, IP-10/CXCL10, and Mig/CXCL9, as inducers of chemotaxis in HAEC and examined the underlying signaling pathways involved. Studies were performed in cultured HAEC from normal subjects and the 16-HBE cell line. In normal HAEC, the efficacy of I-TAC-induced chemotaxis was 349 +/- 88% (mean +/- SE) of the medium control and approximately one-half the response to epidermal growth factor, a highly potent chemoattractant. In normal HAEC, Mig, IP-10, and I-TAC induced chemotaxis with similar potency and a rank order of efficacy of I-TAC = IP-10 > Mig. Preincubation with pertussis toxin completely blocked CXCR3-induced migration. Of interest, intracellular [Ca(2+)] did not rise in response to I-TAC, IP-10, or Mig. I-TAC induced a rapid phosphorylation (5-10 min) of two of the three MAPKs, i.e., p38 and ERK1/2. Pretreatment of HAEC with the p38 inhibitor SB 20358 or the PI3K inhibitor wortmannin dose-dependently inhibited the chemotactic response to I-TAC. In contrast, the ERK1/2 inhibitor U0126 had no effect on chemotaxis. These data indicate that in HAEC, CXCR3-mediated chemotaxis involves a G protein, which activates both the p38 MAPK and PI3K pathways in a calcium-independent fashion.

Bronchi↗
PubMed2006

Cortical layer-dependent BOLD and CBV responses measured by spin-echo and gradient-echo fMRI: insights into hemodynamic regulation.

Spatial specificity of functional magnetic resonance imaging (fMRI) signals to sub-millimeter functional architecture remains controversial. To investigate this issue, high-resolution fMRI in response to visual stimulus was obtained in isoflurane-anesthetized cats at 9.4 T using conventional gradient-echo (GE) and spin-echo (SE) techniques; blood oxygenation-level dependent (BOLD) and cerebral blood volume (CBV)-weighted data were acquired without and with injection of 10 mg Fe/kg monocrystalline iron oxide nanoparticles (MION), respectively. Studies after MION injection at two SE times show that the T2' contribution to SE fMRI is minimal. GE and SE BOLD changes were spread across the cortical layers. GE and SE CBV-weighted fMRI responses peaked at the middle cortical layer, which has the highest experimentally-determined microvascular volume; full-width at half-maximum was <1.0 mm. Parenchymal sensitivity of GE CBV-weighted fMRI was approximately 3 times higher than that of SE CBV-weighted fMRI and approximately 1.5 times higher than that of BOLD fMRI. It is well known that GE CBV-weighted fMRI detects a volume change in vessels of all sizes, while SE CBV-weighted fMRI is heavily weighted toward microvascular changes. Peak CBV change of 10% at the middle of the cortex in GE measurements was 1.8 times higher than that in SE measurements, indicating that CBV changes occur predominantly for vasculature connecting the intracortical vessels and capillaries. Our data supports the notion of laminar-dependent CBV regulation at a sub-millimeter scale.

Animals↗