Biomedical subjects

J Y Zhou

Publications and source records attributed to J Y Zhou.

At least 19 recordsLinked to original sources

PubMed2005

Fluorescence probe assisted post-column detection for lipid analysis in microbore-LC.

A general approach, still few exploited so far and never associated with microbore-LC, consisting of detection of various lipid classes (i.e. phospholipids, triglycerides, ceramides and glycosphingolipids) by non-covalent association with 1,6-diphenyl-1,3,5-hexatriene (DPH) fluorescence probe is developed. This mode of detection was coupled with non-aqueous reversed-phase microbore-LC (C18) by using classical post-column fluorescence detection. The classical LC system was first adapted to microbore-chromatography (internal diameter 1 mm) without apparatus miniaturization of the solvent delivery system and the detection cell. For this purpose, the detection parameters (probe concentration, post-column flow rate, post-column reactor length and post-column system temperature) were optimized by a central composite design (CCD) using a mixture of phosphatidylcholine (PC) species as a lipid model and DPH (lambda(ex) = 350 nm, lambda(em) = 430 nm) as a fluorescence probe. The optimal conditions of detection for the various molecular species of PC were determined for a DPH concentration of 3.35 micromol/L, a post-column flow rate of 0.5 mL/min, a reactor length of 1.4 m and a temperature of 35 degrees C. The fluorescence response was linear over a wide range of PC species from 5 microg/mL to 100 microg/mL and the lower limit of detection (signal/noise = 3) was about 1 microg/mL, that is equivalent to evaporative light scattering detection (ELSD). Others molecular species of various classes of lipids, i.e. triglycerides, ceramides and glycosphingolipids were also easily detected. Thus, this study demonstrated the versatility of the proposed system of detection which was shown to be sensitive, easy to perform, non-destructive and allowed, in contrast to ELSD, for a linear response with various polarity lipid classes.

Chromatography, Liquid↗

PubMed2005

Clinical experience with the noninvasive ICP monitoring system.

The Noninvasive ICP (Intracranial Pressure) Monitoring System NIP-200/210 has been used in several hospitals with more than 2000 patients since March 2002. It is based on the N2 wave response to flash visual evoked potentials (FVEP). According to our data, the mean latency period for the FVEP-induced N2 wave in healthy controls was 126.61 +/- 14.64 ms, in which that of females was shorter than that of males (123.95 +/- 10.345 ms vs. 130.75 +/- 14.632 ms; p < 0.05). There was no significant difference between the left or right side response (126.71 +/- 14.91 ms vs. 124.468 +/- 15.043 ms, p > 0.05). No significant difference in latency was found across age groups in our patient pool. In general, the N2 wave was stable and easily identified in most of the patients or healthy controls. When the data obtained with the NIP-200/210 Noninvasive ICP Monitoring System was compared with that from invasive techniques, the results were quite consistent (correlation index 0.651-0.97, standard error 8-15%). From our clinical trial results, we conclude that the latency periods for the FVEP-induced N2 wave reflected ICP values. However this technique is not suitable in patients with bifrontal hematoma, retinal concussion, or contusion of the optical nerve, because an FVEP value cannot be measured accurately in these cases. In our clinical trials, we used the FVEP technique to determine the effectiveness of mannitol in decreasing the ICP. The data revealed that ICP values decreased significantly within 20 minutes after a mannitol injection, and reached a minimum level at 40 minutes. For a single bolus of mannitol, the duration of the ICP decrease ranged from 30-210 minutes. Elevated ICP is one of the most important clinical issues in neurosurgery and neurology. The present noninvasive technique is safe and easy to perform, with a minimal risk of complications.

Adolescent↗

PubMed2005

The effect of inducible nitric oxide synthase inhibitor on microvascular permeability after cerebral ischemia/reperfusion.

Our objective was to study the effect of inducible nitric oxide synthase (iNOS) inhibitor aminoguanidine (AG) on microvascular permeability after cerebral ischemia/reperfusion (I/R) injury. Cerebral I/R injury was produced by occlusion of both the carotid arteries for 60 min with restitution of blood flow for 60 min. AG (200 mg/kg) was intraperitoneally administrated 5 min before the onset of ischemia and again 5 min before reperfusion. Microvascular permeability was evaluated by 0.75% sodium fluorescein (FINa) extravasation during early 300 s. Cerebral I/R injury increased the permeability of microvessel to fluorescein and the concentration of fluorescein outside of microvessels was significantly higher than that in microvessels after 110 s. However, after AG administration, FINa extravasation appears much faster. From 80 s on, the fluorescence intensity outside is higher. I/R increased microvascular permeability. Nitric oxide derived from iNOS may maintain microvascular permeability at the early stage after I/R.

Animals↗

PubMed2003

The benefit of the retrofitting of a conventional LC system to micro LC: a practical evaluation in the field of bioanalysis with fluorimetric detection.

The interests in liquid micro-chromatography (higher column efficiencies, increase in sensitivity) are now well established. The enhancement of fluorimetric response induced by the reduction of the inner diameter of columns (4.6, 3.0, 1.0 and 0.3 mm respectively) coupled with adapted detection cells to control the loss of efficiency (8 micro L for the two first columns and 100 nL for the two smaller ones) has been studied in the bioanalytical field, using the plasma determination of native fluorescent antibacterial agents: fluoroquinolones. Ten-fold enhancement of the signal can easily be obtained when substituting a 0.3 mm i.d. column and 100 nL detection cell for a 4.6 mm i.d. column, and 8 micro L detection cell. In addition to inner diameter reduction, the detection cell geometry appears to be an essential parameter to obtain the best enhancement of the recorded signal. Hence, the enhancement of signal with micro-chromatography with fluorimetric detection appears to be a compromise between column inner diameter and flow cell volume reduction.

Chromatography, Liquid↗

PubMed2001

G beta association and effector interaction selectivities of the divergent G gamma subunit G gamma(13).

G gamma(13) is a divergent member of the G gamma subunit family considered to be a component of the gustducin G-protein heterotrimer involved in bitter and sweet taste reception in taste bud cells. G gamma(13) contains a C-terminal asparagine-proline-tryptophan (NPW) tripeptide, a hallmark of RGS protein G gamma-like (GGL) domains which dimerize exclusively with G beta(5) subunits. In this study, we investigated the functional range of G gamma(13) assembly with G beta subunits using multiple assays of G beta association and G beta gamma effector modulation. G gamma(13) was observed to associate with all five G beta subunits (G beta(1-5)) upon co-translation in vitro, as well as function with all five G beta subunits in the modulation of Kir3.1/3.4 (GIRK1/4) potassium and N-type (alpha(1B)) calcium channels. Multiple G beta/G gamma(13) pairings were also functional in cellular assays of phospholipase C (PLC) beta 2 activation and inhibition of G alpha(q)-stimulated PLC beta 1 activity. However, upon cellular co-expression of G gamma(13) with different G beta subunits, only G beta(1)/G gamma(13), G beta(3)/G gamma(13), and G beta(4)/G gamma(13) pairings were found to form stable dimers detectable by co-immunoprecipitation under high-detergent cell lysis conditions. Collectively, these data indicate that G gamma(13) forms functional G beta gamma dimers with a range of G beta subunits. Coupled with our detection of G gamma(13) mRNA in mouse and human brain and retina, these results imply that this divergent G gamma subunit can act in signal transduction pathways other than that dedicated to taste reception in sensory lingual tissue.

Amino Acid Sequence↗

PubMed2001

The dual role of ultraspiracle, the Drosophila retinoid X receptor, in the ecdysone response.

The Drosophila homolog of the retinoid X receptor, ultraspiracle (USP), heterodimerizes with the ecdysone receptor (EcR) to form a functional complex that mediates the effects of the steroid molting hormone ecdysone by activating and repressing expression of ecdysone response genes. As with other retinoid X receptor heterodimers, EcR/USP affects gene transcription in a ligand-modulated manner. We used in vivo, cell culture, and biochemical approaches to analyze the functions of two usp alleles, usp(3) and usp(4), which encode stable proteins with defective DNA-binding domains. We observed that USP is able to activate as well as repress the Z1 isoform of the ecdysone-responsive broad complex (BrC-Z1). Activation of BrC-Z1 as well as EcR, itself an ecdysone response gene, can be mediated by both the USP3 and USP4 mutant proteins. USP3 and USP4 also activate an ecdysone-responsive element, hsp27EcRE, in cultured cells. These results differ from the protein null allele, usp(2), which is unable to mediate activation [Schubiger, M. & Truman, J. W. (2000) Development 127, 1151--1159]. BrC-Z1 repression is compromised in all three usp alleles, suggesting that repression involves the association of USP with DNA. Our results distinguish two mechanisms by which USP modulates the properties of EcR: one that involves the USP DNA-binding domain and one that can be achieved solely through the ligand-binding domain. These newly revealed properties of USP might implicate similar properties for retinoid X receptor.

Alleles↗

PubMed2001

Overexpression of BCL2 blocks TNF-related apoptosis-inducing ligand (TRAIL)-induced apoptosis in human lung cancer cells.

The tumor necrosis factor (TNF) related apoptosis-inducing ligand (TRAIL or Apo2L) and its receptors are members of the tumor necrosis factor superfamily. TRAIL triggers apoptosis by binding to its two proapoptotic receptors DR4 and DR5, a process which is negatively regulated by binding of TRAIL to its two decoy receptors TRID and TRUNDD. Here, we show that TRAIL effectively induces apoptosis in H460 human non-small-cell lung carcinoma cells via cleavage of caspases 8, 9, 7, 3, and BID, release of cytochrome c from the mitochondria, and cleavage of poly (ADP-ribose) polymerase (PARP). However, overexpression of Bcl2 blocked TRAIL-induced apoptosis in H460 cells, which correlated with the Bcl2 protein levels. Importantly, the release of cytochrome c and cleavage of caspase 7 triggered by TRAIL were considerably blocked in Bcl2 overexpressing cells as compared to vector control cells. Moreover, inhibition of TRAIL-mediated cytochrome c release and caspase 7 activation by Bcl2 correlated with the inability of PARP to be cleaved and the inability of the Bcl2 transfectants to undergo apoptosis. Thus, these results suggest that Bcl2 can serve an anti-apoptotic function during TRAIL-dependent apoptosis by inhibiting the release of cytochrome c and activation of caspase 7, thereby blocking caspase 7-dependent cleavage of cellular substrates.

Apoptosis↗

PubMed2001

Quantitative determination of fat emulsion using 1,6-diphenyl-1,3,5-hexatriene as fluorescence probe: application to the compounding of all-in-one parenteral nutrition admixtures.

The potential contamination of binary bags by traces of fat emulsion stemmed from ternary bags prepared just before, led us to determine traces of lipids into the line set of the automated compounder MM23. Diphenylhexatriene (DPH) was chosen as fluorescence probe due to its strong fluorescence enhancement in a lipid environment. Optimization of experimental conditions (i.e. DPH amounts, pH of fat emulsion samples, ultrasounds use, light, temperature and contact duration) for fluorescence measurement and validation of analytical method were performed. This method was linear over 0.5-8.0 mg l(-1) (r=0.999) of fat emulsion. The intra-day and inter-day precisions were inferior to 2% for the 2.0 and 8.0 mg l(-1) standards. Under optimized conditions, the detection limit and quantitation limit were 0.10 and 0.29 mg l(-1) of lipids respectively. Compared to the colorimetric method using sodium dichromate, it is at least 100 times more sensitive. The proposed method permitted to rapidly measure fat emulsion traces in automated compounder line set for parenteral nutrition solutions and thus, to assess the risk of contamination of binary bags by lipids. At last, this method was shown to be conveniently applied to the analysis of fat emulsion in the final total parenteral nutrition bag.

Diphenylhexatriene↗

PubMed2001

The investigational new drug XK469 induces G(2)-M cell cycle arrest by p53-dependent and -independent pathways.

PURPOSE: XK469 (2-[4-(7-chloro-2-quinoxalinyloxy) phenoxy]propionic acid), a synthetic quinoxaline phenoxypropionic acid derivative, has broad activity against murine tumors and is entering Phase I clinical development as a topoisomerase IIbeta inhibitor. This study investigated the underlying molecular mechanism of XK469's effects on the cell cycle. EXPERIMENTAL DESIGN: Growth inhibition, cell cycle arrest, induction of p53 and p21 mRNA and protein, and cdc2 phosphorylation and kinase activity were studied in treated cells from the H460 lung cancer line and p21 and p53 knockout cells of the HCT 116 colon cancer line. RESULTS: XK469 arrested H460 cells at G(2)-M, which was associated with cdc2 phosphorylation and decreased cdc2 kinase activity. Moreover, XK469 stabilized p53 and subsequently increased p21(WAF1/CIP1). Furthermore, HCT116 p21(-/-) cells were less sensitive than wild-type cells to XK469-induced growth inhibition, but p53(+/+) and p53(-/-) cells were equally sensitive despite the absence of p21 induction in the p53(-/-) cells. CONCLUSIONS: When considered with published data, our study suggests a complex mechanism of XK469-mediated anticancer activity involving multiple pathways, including p53-dependent and -independent G(2)-M arrest via inactivation of cdc2-cyclin B1 kinase activity.

Antineoplastic Agents↗

PubMed2001

[A study on cellular matrix via cell extraction from bovine pericardium].

OBJECTIVE: To obtain an acellular matrix from bovine pericardial tissue, as a scaffold for tissue engineering of heart valves or cardiovascular patching applications. METHODS: A four step detergent and enzyme link extraction procedure was practiced in this study. The mechanic properties of the acellular matrix were evaluated, and the components were analyzed biochemically. RESULTS: HE staining confirmed the removal of cells and Von Gieson staining showed the integrality of collagen and elastin. Biochemical analysis demonstrated the retention of collagen and some glycosaminoglycans while the percentage of the soluble proteins reduced slightly. The tissue fracture strength and shrinkage temperature made no significant difference after extraction. CONCLUSIONS: The extraction process is effective to remove cells from bovine pericardial tissue while maintains its mechanical strength. This approach may eventually lead to a scaffold for heart valves and cardiovascular patching applications in tissue engineering.

Animals↗

PubMed2001

[Investigation on the excited state dynamics properties of hemicyanine molecules].

In this paper, the excited state dynamics properties of hemicynine were investigated by using time-resolved fluorescence and 3D fluorescence spectra techniques. The interaction of hemicyanine molecules caused formation of H-aggregates and a blue shift of the 3D fluorescence spectra in interleaving hemicyanine/arachidic acid multilayers. The peak of fluorescence was a red shift along with the time decay. The lifetime of the LB fluorescence was much shorter and the difference of beginning luminescence was less than that of the hemicyanine solution due to the stronger intermolecule interactions in the aggregates.

English Abstract↗

PubMed2000

Selective regulation of N-type Ca channels by different combinations of G-protein beta/gamma subunits and RGS proteins.

We examined the effects of G-protein beta and gamma subunit heterodimers on human alpha(1B) (N-type) Ca channels expressed in HEK293 cells. All of the known beta subunits (beta1-beta5) produced voltage-dependent inhibition of alpha(1B) Ca channels, depending on the gamma subunit found in the heterodimer. beta1-beta4 subunits inhibited Ca channels when paired with gamma1-gamma3. However, beta5 subunits only produced inhibition when paired with gamma2. In contrast, heterodimers between beta5 subunits and RGS (regulators of G-protein signaling) proteins containing GGL domains did not produce inhibition of Ca channels. However, GGL domain-containing RGS proteins (e.g., RGS6 and RGS11) did block the ability of Gbeta5/gamma2 heterodimers to inhibit Ca channels. Because all of the G-protein beta subunits are found in the nervous system, we conclude that they may all potentially participate in Ca channel inhibition. The interaction of GGL-containing RGS proteins with Gbeta5gamma2 suggests a novel way in which Ca channels can be regulated.

Analysis of Variance↗

PubMed2000

Germline INI1 mutation in a patient with a central nervous system atypical teratoid tumor and renal rhabdoid tumor.

We describe a four-month-old child who presented with an atypical teratoid/rhabdoid tumor of the brain and subsequently developed a renal rhabdoid tumor. Distinct histologic features, immunophenotypic profiles, and deletions of chromosome 22 were supportive of two primary tumors. An identical mutation in exon 7 of the INI1 rhabdoid tumor suppressor gene was identified in both tumors, as well as in normal kidney tissue. We propose that this germline INI1 mutation predisposed the child to the development of both malignancies. These findings lend support to the hypothesis that rhabdoid tumors in all sites have a common genetic etiology.

Central Nervous System Neoplasms↗

PubMed2000

Mutations of the INI1 rhabdoid tumor suppressor gene in medulloblastomas and primitive neuroectodermal tumors of the central nervous system.

Germ-line and somatic mutations of the hSNF5/INI1 gene have been reported in atypical teratoid/rhabdoid tumors (AT/RTs) of the brain, consistent with its role as a tumor suppressor gene. In the present study, we determined the frequency of deletions and mutations of INI1 in 52 children whose original diagnosis was medulloblastoma (MB) or primitive neuroectodermal tumor (PNET) of the central nervous system. Mutations were detected in DNA isolated from four tumors, all from children less than 3 years of age at diagnosis. Two of the four were reviewed and reclassified as atypical teratoid tumor, whereas there was insufficient material to establish this diagnosis in the two remaining cases. The relatively low frequency of mutations, even in a large series of infants, suggests that loss of sequences from chromosome 22 and/or mutations of INI1 do not account for the poor prognosis of children with MB or PNET who are less than 3 years of age at diagnosis. Nevertheless, chromosome 22 deletion and INI1-mutation analysis of infants with MB/PNET should be considered for all children who are less than 1 year of age. Detection of these mutations suggests that the child has an AT/RT, rather than a MB/PNET, a finding with important prognostic value.

Adolescent↗

PubMed2000

[Effects of components isolated from Astragalus membranaceus Bunge on cardiac function injured by myocardial ischemia reperfusion in rats].

OBJECTIVE: To investigate the effects of components isolated from Astragalus membranaceus on myocardial ischemia reperfusion injury. METHODS: The myocardial ischemia reperfusion injury model was created by the left anterior descending coronary artery occlusion from the oracotouated rats, and the total saponins, total flavonids and astragaloside i.v. isolated from A. membranaceus on hemodynamics during acute myocardial ischemia, Na(+)-K(+)-ATPase activity, cAMP and malondialdehyede (MDA) contents in the ischemic myocardium were observed. RESULTS: The total saponins, total flavonids and astragaloside i.v. attenuated the declines of the amplitudes of LVSP and +/- LVdp/dtmax in rat heart injured by ischemia reperfusion in vivo, and decreased Na(+)-K(+)-ATPase activity in the ischemic myocardium. Otherwise, the total saponins increased the cAMP content and the total flavonids decreased the level of MDA production in the ischemic myocardium. CONCLUSION: The effects of different components isolated from A. membranaceus on protecting the cardiac function in the process of ischemia reperfusion may be related to the mechanism of improving energy metabolism, scavenging the oxygen free radicals and inhibiting the production of free radicals in the ischemic myocardium.

Animals↗

PubMed1999

Postcolumn fluorescence as an alternative to evaporative light scattering detection for ceramide analysis with gradient elution in non-aqueous reversed-phase liquid chromatography.

Ceramide analysis was developed with gradient elution in non-aqueous reversed-phase liquid chromatography with evaporative light scattering detection (ELSD) or postcolumn fluorescence detection. Fluorescence detection (excitation, 360 nm; emission, 425 nm) after postcolumn formation of mixed assemblies between eluted ceramides and 1,6-diphenyl-1,3,5-hexatriene was developed. In comparison with ELSD, fluorescence detection allows a better detection of the minor species ceramide from ceramide type III (commercial mixture of non-hydroxy fatty acid-sphingosine) and appears to be more sensitive for quantitation of ceramides at low concentrations. The fluorescence response is linear over a wide range of injected amount of ceramide III (expressed as stearoyl-phytosphingosine): 10 ng to 1000 ng. The response of ELSD is non linear but can be linearized in double logarithmic coordinates for calculations over a narrow range, e.g. between 10 to 350 ng ceramide III injected. The lower quantitation limits of these two detectors are similar: 5 ng ceramide III was injected.

Ceramides↗

PubMed1999

Cardiac-directed adenylyl cyclase expression improves heart function in murine cardiomyopathy.

BACKGROUND: We tested the hypothesis that increased cardiac myocyte adenylyl cyclase (AC) content increases cardiac function and response to catecholamines in cardiomyopathy. METHODS AND RESULTS: Transgenic mice with cardiac-directed expression of AC type VI (ACVI) were crossbred with mice with cardiomyopathy induced by cardiac-directed Gq expression. Gq mice had dilated left ventricles, reduced heart function, decreased cardiac responsiveness to catecholamine stimulation, and impaired beta-adrenergic receptor (betaAR)-dependent and AC-dependent cAMP production. Gq/AC mice showed improved basal cardiac function in vivo (P=0.01) and ex vivo (P<0.0005). When stimulated through the betaAR, cardiac responsiveness was increased (P=0.02), and cardiac myocytes showed increased cAMP production in response to isoproterenol (P=0.03) and forskolin (P<0.0001). CONCLUSIONS: Increasing myocardial ACVI content in cardiomyopathy restores cAMP-generating capacity and improves cardiac function and responsiveness to betaAR stimulation.

Adenylyl Cyclases↗

PubMed1999

Germ-line and acquired mutations of INI1 in atypical teratoid and rhabdoid tumors.

We examined 18 atypical teratoid and rhabdoid tumors of the brain and 7 renal and 4 extrarenal rhabdoid tumors for mutations in the candidate rhabdoid tumor suppressor gene, INI1. Fifteen tumors had homozygous deletions of one or more exons of the INI1 gene, and the other 14 tumors demonstrated mutations. Germ-line mutations of INI1 were identified in four children, one with an atypical teratoid tumor of the brain and three with renal rhabdoid tumors. These studies suggest that INI1 is a tumor suppressor gene involved in rhabdoid tumors of the brain, kidney, and other extrarenal sites.

Child↗