Variation of myelin basic protein and its antibody in serum in senile dementia patients.
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Adult↗
Biomedical subjects
Y Cheng
Publications and source records attributed to Y Cheng.
[A computational spectral analysis method for multi-component drugs based on wavelet transform].
A novel computational spectral analysis method for multi-component drugs is proposed. The method applies the wavelet denoise processing technique to principle component regression(PCR). Since noise in the original spectral data is effectively filtered, the performance of PCR is obviously improved. A typical example in multi-component drug analysis has been used to verify the effectiveness of the novel algorithm. Compared with that obtained by PCR, the average of mean relative error which obtained by PCRW decreases to 0.46% from 1.48%.
Algorithms↗
Virtual electrode-induced reexcitation: A mechanism of defibrillation.
Mechanisms of defibrillation remain poorly understood. Defibrillation success depends on the elimination of fibrillation without shock-induced arrhythmogenesis. We optically mapped selected epicardial regions of rabbit hearts (n=20) during shocks applied with the use of implantable defibrillator electrodes during the refractory period. Monophasic shocks resulted in virtual electrode polarization (VEP). Positive values of VEP resulted in a prolongation of the action potential duration, whereas negative polarization shortened the action potential duration, resulting in partial or complete recovery of the excitability. After a shock, new propagated wavefronts emerged at the boundary between the 2 regions and reexcited negatively polarized regions. Conduction velocity and maximum action potential upstroke rate of rise dV/dt (max) of shock-induced activation depended on the transmembrane potential at the end of the shock. Linear regression analysis showed that dV/dt(max) of postshock activation reached 50% of that of normal action potential at a V(m) value of -56.7+/-0.6 mV postshock voltage (n=9257). Less negative potentials resulted in slow conduction and blocks, whereas more negative potentials resulted in faster conduction. Although wavebreaks were produced in either condition, they degenerated into arrhythmias only when conduction was slow. Shock-induced VEP is essential in extinguishing fibrillation but can reinduce arrhythmias by producing excitable gaps. Reexcitation of these gaps through progressive increase in shock strength may provide the basis for the lower and upper limits of vulnerability. The former may correspond to the origination of slow wavefronts of reexcitation and phase singularities. The latter corresponds to fast conduction during which wavebreaks no longer produce sustained arrhythmias.
Animals↗
Murine Siva-1 and Siva-2, alternate splice forms of the mouse Siva gene, both bind to CD27 but differentially transduce apoptosis.
CD27, a member of the TNFR family known to provide essential co-stimulatory signals for T cell growth and B cell Ig synthesis, can also mediate cell death. Using the CD27 cytoplasmic tail as the bait in yeast two hybrid assay, we previously cloned human Siva, a pro-apoptotic molecule. Here we report the characterization of the mouse Siva gene as a 4 kb sequence containing 4 exons and 3 introns. RT-PCR has revealed the presence of two forms of mouse Siva mRNA, the longer full length form Siva-1 and the shorter Siva-2 lacking the sequence coded by exon 2. Immunoblotting with anti-Siva (human) antibodies clearly demonstrate the presence of both Siva-1 and Siva-2. Cotransfection experiments in 293T cells reveal that mouse CD27 receptor can interact with both forms of Siva. Although mouse Siva-1 can trigger apoptosis in Rat-1 cells and in some of the mouse cell lines in transient transfection experiments, similar to the observation made with human Siva, intriguingly its alternate splice form, Siva-2 appears to be much less toxic. It is therefore likely that Siva-2 could regulate the function of Siva-1.
3T3 Cells↗
Detection of IgM to hepatitis B core antigen in a reductant containing, chemiluminescence assay.
The Abbott PRISM(R) hepatitis B core (HBc) antigen assay is an automatic in vitro competitive chemiluminescence immunoassay for the detection of total antibody to HBc (anti-HBc) antigen in human serum or plasma. The assay utilizes cysteine solution as a reducing reagent in order to maximize specificity. To help understand the effect of cysteine on detection of anti-HBc antigen, we separated and purified anti-HBc IgM and IgG from human plasma using size exclusion, protein A/G, and affinity chromatography techniques. We showed that cysteine affected the reactivity of anti-HBc IgM with recombinant HBc (rHBc) antigen but not the reactivity of anti-HBc IgG. Anti-HBc IgM treated with cysteine yielded byproducts which were reactive in the PRISM HBcore assay. Reduction-sensitive factor (RSF) - IgM fraction from serum known to be non-specific for anti-HBc activity, similarly treated with cysteine, was no longer reactive in the PRISM HBcore assay. We showed that cysteine treatment is effective against non-specific IgM in human blood. Also, the inclusion of cysteine in the PRISM HBcore assay does not compromise the detection of HBc specific antibodies.
Antibody Specificity↗
Gadolinium induces domain and pore formation of human erythrocyte membrane: an atomic force microscopic study.
Lanthanide cations bind to human erythrocyte membranes and enhance cell permeability. It was postulated that this effect is due to their likeness with calcium ions, which have been used to induce perforation of cells. However, the nature and mechanism of the perforation are still not clear. In the present work, the change in surface topography of erythrocyte membranes exposed to various gadolinium species was imaged with an atomic force microscope (AFM) in order to get direct evidence of perforation. The images of the whole cell and regions in nanometer scale showed that the normal surface is featured by closely packed nanometer size particles. The AFM images showed that Gd(3+) binding to erythrocytes led to domain structure at low concentration and pore formation at higher concentration. The domain structures that appeared after incubation with 1.0x10(-6)-1.0x10(-5) mol/l Gd(3+) solution for 30 min are featured by the particles aggregated to form ranges and the separations among them enlarged to gorges. With a higher concentration, 2.5x10(-5) mol/l Gd(3+), the further aggregation developed into crater-shaped 'pores'. By washing with EDTA the 'pores' can be resealed but the domain structure remained. The anionic complex of Gd(3+), [Gd(Cit)(2)](3-) of this concentration, can only induce the domain structure formation. The domain and 'pore' structures mediated by Gd(3+) concentrations might be responsible for both enhanced permeability and perforation. The mechanism of Gd-induced domain formation and perforation is discussed on the basis of aggregation of membrane proteins and the coexistence of different phases of membrane lipids resulting from Gd(3+) binding.
Animals↗
The events relating to lanthanide ions enhanced permeability of human erythrocyte membrane: binding, conformational change, phase transition, perforation and ion transport.
The binding and uptake of Gd3+ ions by human erythrocytes in vitro were studied by determining the Gd contents in membrane and in cytosol by means of particle-induced X-ray emission (PIXE) spectrometry. Results obtained from varied incubation time revealed that the Gd3+ ions bind to the membrane proteins and lipids at first. Gd3+ binding to the membrane lipids and proteins lasts 0 approximately 20 and 20 approximately 100 ms respectively, as shown by the stopped-flow studies. Then a fraction of Gd3+ ions diffuses through the membrane. The kinetics of Gd3+ binding indicates that the binding to phospholipids is prior to that to the membrane proteins, but a portion of the lipid-bound Gd3+ redistributed later to the proteins. PIXE studies showed that the entry of Gd3+ increased the influx of Ca2+ and Cl-. By monitoring the changes in fluorescence of proteins and that of the Ln3+, the uptake of La3+, Eu3+, Gd3+ and Tb3+ was shown to be a process comprising a series of events. Binding to the membrane molecules induces the phase transition of lipid bilayer and conformational changes and aggregation of membrane proteins. Conformational changes of the proteins were characterized by Fourier transform IR spectroscopy (FT-IR) deconvolved spectra, i.e. alpha-helix content decreases while beta-sheet increases. ESR spectra of MSL-labeled proteins reflect the aggregation state related with the conformational change. [31P]NMR spectra of membrane lipid bilayer revealed the Ln3+ ions induced hexagonal (H(II)) phase formation. Phase transition and aggregation of membrane proteins cause the formation of domain structure and perforation in the membrane. These alterations in membrane structure are responsible for the Ln3+ enhanced membrane permeability. Thus the previous Ln3+ binding will facilitate the across-membrane transport of other Ln3+ ions through the membrane.
Blood Proteins↗
The projection structure of the membrane protein microsomal glutathione transferase at 3 A resolution as determined from two-dimensional hexagonal crystals.
The formation of two-dimensional crystals of the membrane-bound enzyme microsomal glutathione transferase is sensitive to fractional changes in the lipid-to-protein ratio. Variation of this parameter results in crystal polymorphism. The projection structure of a p6 crystal form of the enzyme has been determined by the use of electron crystallography. The unit cell at 3 A resolution is comprised of two trimers. The hexagonal p6 and the orthorhombic p21212 crystal types have common elements in the packing arrangement which imply dominant crystal contacts. An overall structural similarity between the protein molecules in the two crystal forms is suggested by the projection maps. Furthermore, a comparison of the p6 and p21212 projection maps identifies additional corresponding protein densities which could not be assigned to the microsomal glutathione transferase trimer previously. Surprisingly, an ambiguity of the rotational orientation was found for trimers interspersed at certain positions within the crystal lattice.
Animals↗
The 69 bp circadian regulatory sequence (CRS) mediates per-like developmental, spatial, and circadian expression and behavioral rescue in Drosophila.
The period (per) gene is an essential component of the circadian timekeeping mechanism in Drosophila. This gene is expressed in a circadian manner, giving rise to a protein that feeds-back to regulate its own transcription. A 69 bp clock regulatory sequence (CRS) has been identified previously upstream of the period gene. The CRS confers wild-type mRNA cycling when used to drive a lacZ reporter gene in transgenic flies. To determine whether the CRS also mediates proper developmental and spatial expression and behavioral rescue, we used the CRS to drive either lacZ or per in transgenic flies. The results show that the CRS is able to activate expression in pacemaker neuron precursors in larvae and essentially all tissues that normally express per in pupae and adults. The CRS is sufficient to rescue circadian feedback loop function and behavioral rhythms in per01 flies. However, the period of locomotor activity rhythms shortens if a stronger basal promoter is used. This study shows that regulatory elements sufficient for clock-dependent and tissue-specific per expression in larvae, pupae, and adults are present in the CRS and that the period of adult locomotor activity rhythms is dependent, in part, on the overall level of per transcripts.
Animals↗
Influence of various nucleotides on the in situ crystallization of Ca2+-ATPase.
A reproducible in situ crystallization of the Ca2+-ATPase in isolated sarcoplasmic reticulum (SR) membranes was studied. The addition of various nucleotides to the washing buffer allowed the formation of tubular crystals, which is induced by vanadate. SR membranes washed with nucleotide-free buffer could not form tubular crystals upon subsequent incubation with vanadate.
Adenosine Triphosphate↗
The transport kinetics of lanthanide species in a single erythrocyte probed by confocal laser scanning microscopy.
A novel method has been developed to visualize and follow the temporal course of lanthanide transport across the membrane into a single living erythrocyte. By means of confocal scanning microscopy and the optical section technique, the entry of lanthanide ions was followed by the fluorescence quenching of fluorescein isothiocyanate (FITC)-labeled membrane and cytosol. From the difference of the quenching kinetics of the whole section and the central area, the time for diffusion through the membrane and the diffusion in the extracellular and intracellular media can be deduced. To clarify the mechanism of lanthanide-induced fluorescence quenching of FITC-labeled erythrocytes and to ensure that this reaction can be used in this method, the reaction was investigated by steady-state fluorescence techniques. The results showed that the lanthanides strongly quenched the florescence emitted by FITC covalently bound to membrane proteins and cytosolic proteins. The static quenching mechanism is responsible for the fluorescence quenching of FITC-labeled proteins by Ln species. The quenching mechanism is discussed on the basis of complex formation. The dependence of fluorescence quenching on both ion size and the total orbital angular momentum L supports the complexation mechanism. The transport time across the membrane is strikingly correlated with Ln species and extracellular concentration. For a given concentration, the transport time of [Ln(cit)2]3- is much shorter than that of Ln3+, since they enter the cells via the anion channel. This is supported by the inhibition effect of 4,4'-diisothiocyanato-2,2'-stilbenendisulfonate on the transport of [Ln(cit)2]3-. On the other hand, the transport of free Ln3+ might be attributed to the enhanced permeability of erythrocytes owing to Ln3+ binding. These findings strongly demonstrate the existence of the non-internalization mechanism of Ln species uptake by erythrocytes.
Animals↗
Degradation of Bowman-Birk protease inhibitor mRNA with a cell-free extract.
A cell-free mRNA degradation system consisting of the polysomal and postpolysomal fractions was obtained from cultured soybean cotyledons for studying Bowman-Birk protease inhibitor (BBPI) mRNA stability. This in vitro system reflected the shorter in vivo half-life of BBPI mRNA of cotyledons cultured in basal-medium as compared to cotyledons cultured in methionine-supplemented medium. Most of the BBPI mRNA degradative activity was found to be present in the postpolysomal supernatant fraction. The higher rate of BBPI mRNA degradation in basal medium-cultured cotyledons was due to an increased destabilizing activity specific to BBPI mRNA in the postpolysomal fraction from basal-medium cultured cotyledons. The specificity was absent when purified RNA was used as the substrate. Degradation of the mRNA was not divalent cation-dependent and was inhibited in the presence of higher concentrations of monovalent and divalent cations.
Cell-Free System↗
Genetic alterations in pediatric high-grade astrocytomas.
High-grade astrocytomas are tumors that are uncommon in children. Relatively few studies have been performed on their molecular properties and so it is not certain whether they follow different genetic pathways from those described in adult diffuse astrocytomas. In this study, we evaluated 24 pediatric high-grade astrocytomas (11 anaplastic astrocytomas and 13 glioblastomas) all of which were sporadic and primary. We studied mutations of p53, phosphatase and tensin homolog (PTEN), loss of heterozygosity (LOH) of chromosomes 17p13, 9p21 and 10q23-25, amplification of epidermal growth factor receptor (EGFR), and overexpression of EGFR and p53 protein. In addition, we searched for microsatellite instability (MSI) by using MSI sensitive and specific microsatellite markers. p53 mutations were found in 38% (9/24) of the high-grade astrocytomas and all brain stem tumors except 2 (71%, 5/7) had p53 mutations. PTEN mutations were found in 8% (2/24) of high-grade astrocytomas. However, no EGFR amplification was found in any of them. LOH was found at 17p13.1 in 50% (3/6 informative tumors), 9p21 in 83% (5/6 informative tumors), and 10q23-25 in 78% (7/9 informative tumors). Four tumors showed MSI, and 2 of them that showed widespread MSI were regarded as tumors with replication error (RER+) phenotype. All 4 tumors with MSI showed concurrent LOH of 9p21 and 10q23-25. Combining gene alterations, LOH, MSI, and gene mutations, inactivation of both alleles of PTEN and p53 was found in 57% (4/7 informative tumors) and 50% (3/6 informative tumors) of the cases respectively. We conclude that development of pediatric high-grade astrocytomas may follow pathways different from the primary or secondary paradigm of adult glioblastomas. In a subset of these tumors, genomic instability was also implicated.
Adolescent↗
Molecular analysis of barley yellow mosaic virus isolates from China.
The complete sequences of both RNAs of an isolate of barley yellow mosaic virus from Yancheng, Jiangsu province, China, were determined. The sequences resembled those of an isolate from Japan (96.8% identical nucleotides for RNA1; 95.7% for RNA2) more closely than one from Germany (93.9 and 91.0%, respectively). The greatest differences between the Chinese and Japanese isolates were in the 5'-UTRs of RNAs 1 and 2 (88.9 and 91.6% identical nucleotides, respectively) and there were also some other regions of difference in P1 (RNA2) and P3, CI, NIa and the 5' end of the coat protein (CP) (RNA1). Molecular differences between isolates from ten sites widely distributed in Eastern China were studied by sequencing RNA regions coding for the CP (RNA1) and the N-terminus of the P2 protein (RNA2). The P2 fragment was more variable than the CP, and phylogenetic analysis of both regions showed that Asian and European isolates formed distinct clusters. Differences between isolates were also revealed by single-strand conformation polymorphism of reverse transcription-polymerase chain reaction products, spanning the full lengths of both RNA1 and RNA2. However, molecular variations between isolates could not be linked to earlier results showing differences in cultivar response.
Base Sequence↗
Ursodeoxycholic acid increases the activities of alkaline sphingomyelinase and caspase-3 in the rat colon.
BACKGROUND: Ursodeoxycholic acid (UDCA) has been found to inhibit the development of colon carcinoma induced by chemical carcinogens with unidentified mechanisms. Sphingomyelin metabolism has emerged as a novel signal transduction pathway closely related to cell proliferation and apoptosis. We recently found that alkaline sphingomyelinase (SMase) activity was decreased in human colon cancer. The present study is to investigate whether UDCA has effect on the levels of SMase and whether the activity of caspase-3, a key regulatory protease in apoptosis that can be activated by sphingomyelin breakdown products, is also influenced by UDCA. METHODS: Rats were fed UDCA in amounts ranging from 37.5 to 300 mg/kg/day for 10 days by gavage. The colonic mucosa was scraped, homogenized, and sonicated. The activities of acid, neutral and alkaline SMases, and caspase-3 were determined. RESULTS: UDCA dose-dependently increased alkaline SMase activity in colonic mucosa and faeces, slightly increased acid SMase activity in the mucosa, and had no effect on neutral SMase. UDCA also dose-dependently increased caspase-3 activity in the colonic mucosa, and the increase correlated significantly with the changes in alkaline but not that in acid or neutral SMase activity. CONCLUSIONS: UDCA increases alkaline sphingomyelinase and caspase-3 activities, which might be a mechanism involved in its anticarcinogenic effect on colon cancer development.
Acid Phosphatase↗
Effects of genistein and daidzein on membrane characteristics of HCT cells.
Genistein and daidzein are two major isoflavonoids in soybeans. They have received increasing attention because of their possible role in cancer prevention. In the present investigation, the human colon tumor (HCT) cell line was used to investigate the effect of isoflavonoids on cell growth with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide colorimetric assay. We found that genistein and/or daidzein could inhibit growth in HCT cells. The 50% inhibitory concentrations of genistein and daidzein were 15 and 40 microM, respectively. Fluorescent polarization, quasielastic light scattering, and circular dichroism were used to study the influence of isoflavonoids on membrane characteristics of HCT cells, including membrane fluidity, density of cell surface charge, and membrane protein conformation. Membrane fluidity of HCT cells was obviously reduced by genistein, but not by daidzein. The effect of genistein was time and dose dependent. In addition, genistein and daidzein could reduce the density of cell surface charge and increase the order of membrane protein conformation. All these changes may represent one of the mechanisms of the effect of isoflavonoids on growth inhibition, differentiation promotion, and transfer interference in a tumor cell line.
Anticarcinogenic Agents↗
Molecular analysis of microdissected de novo glioblastomas and paired astrocytic tumors.
Glioblastoma multiforme (GBM) often displays morphological heterogeneity in that low-grade (LG) area with well-differentiated cells are commonly found adjacent to high-grade (HG) area with poorly-differentiated cells. This heterogeneity may cause difficulty in obtaining representative tumor samples. Nevertheless, the genetic composition of these cells has only been occasionally examined. In the present study, we examined 29 de novo glioblastomas in which distinct LG and HG areas of sufficient volumes could be identified. These areas were microdissected from paraffin-embedded tissues and analyzed for genetic alterations: p53 mutations and immunohistochemistry; allelic losses at 17p13.1, 9p21, and 10q23-25; and amplification of the epidermal growth factor receptor (EGFR) gene and immunohistochemistry. We also examined 14 paired astrocytic tumors, in which a primary Grade II astrocytoma progressed over a period of time to a Grade III or Grade IV tumor. Our findings showed that the LG areas of the de novo glioblastomas exhibited numerous genetic aberrations, the proportion of which was increased in the HG areas. Genetic abnormalities seen in the LG areas were conserved in the HG areas suggesting that these morphologically different cellular subsets were derived from a common transformed clone. Also, the LG areas were genetically different from Grade II astrocytomas of the paired tumor group, in spite of their morphological similarity. In particular, the LG areas had more deletions on 10q23-25 (75% vs 20%, p = 0.04), but fewer p53 mutations (24% vs 71%, p = 0.003) and less p53 protein labeling (45% vs 79%, p = 0.04). These differences suggest that LG and HG areas in de novo glioblastoma are genetically closer to each other compared with paired low- and high-grade tumors that have progressed over time. Moreover, only a small proportion (17%) of our de novo glioblastomas exhibited EGFR amplification while a high proportion (62%) showed either p53 mutations or allelic loss of 17p13.1. We speculate that some de novo GBMs with copious LG areas may constitute a separate group with rapid progression from Grade II astrocytomas.
Adult↗
Evidence of three-dimensional scroll waves with ribbon-shaped filament as a mechanism of ventricular tachycardia in the isolated rabbit heart.
INTRODUCTION: Rotating vortices have been observed in excitable media of different nature. Vortices may sustain life or kill in different species, by underlining morphogenesis in Dictiostelium discoideum during starvation, or arrhythmias during sudden cardiac death in mammals. Investigation of vortices in the heart has been limited by two-dimensional experimental techniques. In contrast, three-dimensional (3D) Belousov-Zhabotinsky excitable medium and mathematical models have been shown to sustain scroll-shaped waves. The heart is a 3D structure; therefore, scroll waves may underlie cardiac arrhythmias. METHODS AND RESULTS: We used potentiometric dye and optical mapping techniques to study vortices during ventricular arrhythmias. The core of all observed vortices were linearly shaped and > or = 9 mm (48 episodes, six hearts). As shown by Allessie et al. in the rabbit atrium, ventricular signals recorded within 1 to 2 mm from the line of block were dual humped, suggesting there is electrotonic interaction across the line of block. We hypothesized that the line of block represents epicardial intersection of ribbon-shaped filaments, which in some cases may be oriented under an angle or parallel to the epicardium. In 14 episodes we observed dual-humped optical recordings at one side of the line of block at a distance up to 12 mm. The two humps may represent the signatures of two activation wavefronts propagating above and below the filament, which in this area is close to the epicardial surface. The activation sequence of the two waves is consistent with the idea of a scroll wave with ribbon-like filament. CONCLUSION: Our data provide new insights into the shape and dynamics of the filament of the 3D scroll wave, which underlies the mechanism of ventricular tachycardia in the rabbit heart. The filament of the scroll wave may be ribbon shaped, with a significant width > or = 9 mm and a thickness of 1 to 2 mm. No evidence of fully excitable cells in the core of vortex was observed.
Action Potentials↗