Biomedical subjects

Jiang Jiang

Publications and source records attributed to Jiang Jiang.

7 recordsLinked to original sources

PubMed2006

The spine neck filters membrane potentials.

Dendritic spines receive most synaptic inputs in the forebrain. Their morphology, with a spine head isolated from the dendrite by a slender neck, indicates a potential role in isolating inputs. Indeed, biochemical compartmentalization occurs at spine heads because of the diffusional bottleneck created by the spine neck. Here we investigate whether the spine neck also isolates inputs electrically. Using two-photon uncaging of glutamate on spine heads from mouse layer-5 neocortical pyramidal cells, we find that the amplitude of uncaging potentials at the soma is inversely proportional to neck length. This effect is strong and independent of the position of the spine in the dendritic tree and size of the spine head. Moreover, spines with long necks are electrically silent at the soma, although their heads are activated by the uncaging event, as determined with calcium imaging. Finally, second harmonic measurements of membrane potential reveal an attenuation of somatic voltages into the spine head, an attenuation directly proportional to neck length. We conclude that the spine neck plays an electrical role in the transmission of membrane potentials, isolating synapses electrically.

Animals↗

PubMed2006

Imaging membrane potential in dendritic spines.

Dendritic spines mediate most excitatory inputs in the brain. Although it is clear that spines compartmentalize calcium, it is still unknown what role, if any, they play in integrating synaptic inputs. To investigate the electrical function of spines directly, we used second harmonic generation (SHG) imaging of membrane potential in pyramidal neurons from hippocampal cultures and neocortical brain slices. With FM 4-64 as an intracellular SHG chromophore, we imaged membrane potential in the soma, dendritic branches, and spines. The SHG response to voltage was linear and seemed based on an electro-optic mechanism. The SHG sensitivity of the chromophore in spines was similar to that of the parent dendritic shaft and the soma. Backpropagation of somatic action potentials generated SHG signals at spines with similar amplitude and kinetics to somatic ones. Our optical measurements of membrane potential from spines demonstrate directly that backpropagating action potentials invade the spines.

Action Potentials↗

PubMed2006

Mass spectrometry assisted assignments of binding and cleavage sites of copper(II) and platinum(II) complexes towards oxidized insulin B chain.

Interaction of cis-[Pt(en)(H2O)2]2+ and [CuL(H2O)]2+, where L is 2-[bis(2-aminoethyl)amino]ethanol, with oxidized insulin B chain in molar ratio of 1 : 1, 1 : 2 and 1 : 3 at pH 2.5 and 40 degrees C has been investigated by electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (MS/MS). The results show that the binding sites of the two complexes with oxidized insulin B chain are terminal NH2, imidazole groups of His5 and His10. The hydrolytic cleavage studies show that the [CuL(H2O)]2+, upon a pendant hydroxyl group of the ligand, selectively cleaves the peptide bonds at Gly8-Ser9, Asn3-Gln4 and Phe1-Val2, and the cis-[Pt(en)(H2O)2]2+ only cleaves the peptide bond at His10-Leu11. This is the first report of cis-[Pt(en)(H2O)2]2+-promoted cleavage of His-X peptide bond.

Copper↗

PubMed2005

[Changes in endothelin-1 and calcitonin gene-related peptide in myocardium after severe burn and delayed fluid resuscitation in rats at different altitudes on plateau].

OBJECTIVE: To explore changes in endothelin-1 (ET-1) and calcitonin gene-related peptide (CGRP) in the myocardium after severe burn and delayed fluid resuscitation in rats at different altitudes. METHODS: Two hundred and forty male Wistar rats were employed as the experimental models with full-thickness burn of 30% total body surface area (TBSA), and they were randomly divided into three groups: delayed fluid resuscitation group (DFR), immediate fluid resuscitation group (IFR) and control group (CG). Samples of myocardial tissue were harvested at 1 hour, 6 hours, 12 hours, 24 hours, 72 hours, 168 hours postburn respectively. The changes in ET-1 and CGRP contents were determined by means of radio immunological assay. RESULTS: (1)The contents of ET-1 and CGRP in DFR group tended to increase at 6 hours after burn, ET-1 was higher 2.8, 3.6 fold, while CGRP higher by 2.2, 1.5 fold (P<0.01), compared with that of CG respectively at 1517 m and 3840 m. The tendency of rise of ET-1 and CGRP was significantly less conspicuous in IFR group than that in DFR group. (2)The contents of ET-1 in DFR group tended to increase at 6 hours and reached the peak at 24 hours after burn at 1517 m, while the levels reached the peak at 72 hours after burn at 3840 m, and the change lasted for 168 hours in DFR group. The contents of CGRP increased significantly at 6 hours and reached the peak at 12 hours at 1517 m, while they reached the peak at 72 hours after burn at 3840 m. CONCLUSION: The myocardial contents of ET-1 tend to increase significantly with the elevation of altitude after severe burn in rats, but the contents of CGRP increased lagged behind. The result show that the higher the altitude is, the more the exhaustion of protective agents of the myocardium, thus resulting in changes in ET-1/CGRP.

Altitude↗

PubMed2004

[Re-survey on epidemiological history of 1 091 probable cases with severe acute respiratory syndrome in Beijing].

OBJECTIVE: To know their real epidemiological histories in 1,091 probale cases of severe acute respiratory syndrome (SARS) without definite history of contact with SARS patients in the first survey. METHODS: All the probable SARS cases until June 9, 2003 without definite history of contact with SARS patients in the first epidemiological survey were included in a re-survey with questionnaire. The second survey was carried out during June 9 to 30, 2003. RESULTS: The results showed that history of contact with other SARS patients was obtained in 15.9% of 1 091 probale SRAS cases in the second survey, transmission of SARS to others was found in 10.5% of them, and source of infection in hospital was found in 46.5%. Comprehensive judgement based on epidemiological history showed that probale history of contact with SARS patients could be found in 72.9% of 1,091 probale cases of SARS in the second survey. CONCLUSION: Source of infection could be found through additional survey in part of probale cases of SARS without it in initial epidemiological survey.

China↗

PubMed2002

Determination of alkylphosphonic acids using micellar electrokinetic chromatography with laser-induced fluorescence detection and high-salt stacking.

Methyl-, ethyl- and propylphosphonic acids (MPA, EPA, and PPA, respectively) were derivatized with panacyl bromide in dry N,N-dimethylformamide (DMF). After mixing with a high-salt dilution buffer, the derivatives were separated by micellar electrokinetic chromatography in 35 min and detected by laser-induced fluorescence (He-Cd laser excitation at 325 nm and detection at 500 nm). Baseline resolution was achieved using a separation buffer containing 50 mM sodium cholate, 40% (v/v) of acetonitrile and 50 mM borate. Addition of 400 mM NaCl to the dilution buffer allowed the injection time to be increased to 30 s while still maintaining baseline resolution. Limits of detection for MPA, EPA, and PPA were 0.13 microM (12 ppb), 0.13 microM (14 ppb) and 0.14 microM (17 ppb) injected, respectively. The reproducibility of corrected peak area at 15 microM was 3.7 approximately 4.3%.

Chromatography, Micellar Electrokinetic Capillary↗

PubMed2002

Capillary sodium dodecyl sulfate-DALT electrophoresis with laser-induced fluorescence detection for size-based analysis of proteins in human colon cancer cells.

Capillary sodium dodecyl sulfate (SDS)-DALT electrophoresis (SDS-DALT-CE) refers to CE separation of proteins based on their size; DALT is the abbreviation for Dalton, the unit used to describe molecular weight. In this work, seven proteins from 18 to 116 kDa were denatured by SDS, labeled by 3-(2-furoyl) quinoline-2-carboxaldehyde, separated by SDS-DALT-CE in polyethylene oxide sieving matrix, and detected by laser-induced fluorescence (LIF) in a sheath flow cuvette. This method was combined with detergent differential fractionation, which is a protein fractionation method using a series of detergent-containing buffers to sequentially extract protein fractions from cells, to analyze the proteins in HT29 human colon adenocarcinoma cells. In addition, on-column labeling was demonstrated for protein analysis by SDS-DALT-CE with LIF, and applied to analysis of proteins in a single HT29 cancer cell. Most proteins had molecular masses from 10 to 120 kDa. Similar protein profiles were obtained for single cells and protein extract of a large cell population.

Adenocarcinoma↗