Biomedical subjects

Y Zhang

Publications and source records attributed to Y Zhang.

At least 559 records · Page 31Linked to original sources

PubMed2001

Single capacitive discharge utilizing an auxiliary shock in the coronary venous system reduces the defibrillation threshold.

UNLABELLED: Auxiliary shocks (AS) from electrodes sutured to the left ventricle (LV) prior to primary biphasic shocks (PS) have been shown to reduce defibrillation thresholds (DFT). Two capacitors are required to generate these waveforms. We investigate delivery of AS from one capacitor using a novel waveform. The epicardial surface of the LV is accessed transvenously via the middle cardiac vein (MCV) avoiding a thoracotomy. METHODS: A defibrillation electrode was placed in the right ventricle (RV) and superior vena cava (SVC) in 12 pigs (37+/-2 kg). A 50x1.8 mm electrode was inserted in the MCV through a guide catheter. A can was placed in the left pectoral region. A monophasic AS (100 microF, 1.5 J) was delivered along one pathway before switching to deliver a biphasic waveform (40% tilt, 2 ms phase 2) along another. DFTs (PS+AS) were assessed using a binary search. Two configurations not incorporating AS acted as controls. DFTs were compared using repeated measures analysis of variance. RESULTS: DFTs of the four novel configurations (AS/PS) were: RV-->Can/MCV-->Can=14.9+/-3.7 J, MCV-->Can/RV-->Can=17.2+/-5.7 J, RV-->SVC+Can/MCV-->SVC+Can=13.4+/-4.6 J, MCV-->SVC+Can/RV-->SVC+Can=17.1+/-5.9 J. Delivering AS in the RV followed by PS in the MCV reduced the DFT (RV-->Can (19.9+/-7.3 J, P<0.01) and RV-->SVC+Can (19.2+/-6.0 J, P<0.05)). CONCLUSIONS: Delivering AS prior to PS in the MCV reduces the DFT by up to a third compared to conventional configurations of RV-->Can and RV-->SVC+Can. This is possible using only a single capacitor and an entirely transvenous approach to the LV.

Animals↗

PubMed2001

Chemical deglycosylation can induce methylation, succinimide formation, and isomerization.

Interpretation of deglycosylation studies relies heavily on the absence of modifications to the polypeptide chain. We have found that by using a common chemical deglycosylation technique, one can effect at least three changes in a peptide's structure: methylation, isomerization, and ring formation. It was determined that the conditions of chemical deglycosylation introduce a +14 Da shift in the masses of our model peptides, RKDVY, RKEVY, and horseradish peroxidase. This shift is localized to acidic functional groups and is interpreted as methylation of the free carboxylates in our models. An additional shift in mass of -18 Da is found in the model peptide RKDVY consistent with the loss of water associated with succinimide ring formation in this peptide. Chemical treatment induced isomerization of aspartyl residues to isoaspartyl residues in another model peptide, tetragastrin. These results indicate that one should use caution when interpreting the results of chemical deglycosylation experiments.

Amino Acid Sequence↗

PubMed2001

Variations in transmembrane Ca2+ gradient and apoptosis of macrophages induced by oxidized low density lipoprotein.

While Ca2+ has been proposed to be a messenger in OxLDL-induced cell death, few studies have addressed the possibility that it may influence the occurrence of apoptosis and necrosis of macrophages induced by OxLDL in virtue of change of transmembrane Ca2+ gradient including that across plasma membrane and intracellular organelle membranes. In this paper, various lipophilic Ca2+ fluorescent indicators and specific organelle markers were used to study the relationship between the changes of the transmembrane Ca2+ gradients and the OxLDL induced apoptosis of macrophages. Our results showed that following exposure of low dose OxLDL to macrophages, the transmembrane Ca2+ gradient across the plasma membrane, as well as the membrane-proximal Ca2+ gradient, the transnuclear, and the transmitochondrial membrane Ca2+ gradient were all changed significantly. These data suggested that changes in transmembrane Ca2+ gradients might be involved in the apoptosis of macrophages induced by OxLDL.

Animals↗

PubMed2001

Identification of human, mouse and rat PPP1R14A, protein phosphatase-1 inhibitor subunit 14A, & mapping human PPP1R14A to chromosome 19q13.13-q13.2.

Three novel cDNAs encoding putative protein phosphatase-1 inhibitory protein (PPP1R14A) were isolated from human, mouse and rat. The human, mouse and rat PPP1R14A proteins were all of 147 amino acids sharing about 90% sequence identity to porcine CPI17, an inhibitor of protein phosphatase-1 holoenzyme. The protein sequence 33RHARVTVK40, which is important for the inhibitory potency of porcine CPI17, was conserved in mammalian PPP1R14A. Northern blot analysis showed that human PPP1R14A was highly expressed as a 600 bp transcript in heart, prostate, testis, ovary, colon, small intestine and pancreas, lowly in brain, placenta, skeletal muscle and spleen and lung. The distribution of mouse and rat PPP1R14A was more specific and different from that of human PPP1R14A, abundant in lung, moderate/abundant in testis, moderate in brain and low in heart. In addition, we mapped human PPP1R14A to chromosome 19q13.13-q13.2 by radiation hybrid mapping, and determined that the human PPP1R14A gene spanned a 5.1-kb region and consisted of four exons and three introns.

Amino Acid Sequence↗

PubMed2001

A one pot synthesis of mono- and di-lactosyl sphingosines.

The importance of analogues of lactosyl ceramides as basic structures of many natural glycosphingolipids provided a rationale for developing an efficient synthetic route to these compounds. We report herein a novel approach to synthesize several members of this family. Glycosylation of N-diphenylmethylene-spingosine, which exists in an imine-oxazolidine tautomeric mixture, with acetobromolactose under a modified Koenigs-Knorr condition yielded lactosyl beta-(1 --> 1) sphingosine, lactosyl beta-(1 --> 3) sphingosine and dilactosyl sphingosine in good yields. A similar glycosylation could be applicable to the synthesis of other glycosphingolipids.

Carbohydrate Conformation↗

PubMed2001

A MAGE-3 peptide recognized on HLA-B35 and HLA-A1 by cytolytic T lymphocytes.

Antigens encoded by MAGE genes are of particular interest for cancer immunotherapy because of their strict tumoral specificity and because they are shared by many tumors. Antigenic peptide EVDPIGHLY encoded by MAGE-3 and known to be presented by HLA-A*0101 is currently being used in therapeutic vaccination trials. We report here that a cytolytic T-lymphocyte (CTL) clone, which is restricted by HLA-B*3501, recognizes the same peptide and, importantly, lyses HLA-B*3501 tumor cells expressing MAGE-3. These results infer that the current clinical use of peptide EVDPIGHLY can now be extended to HLA-B*3501 patients.

Amino Acid Sequence↗

PubMed2001

Lichen striatus. Histological, immunohistochemical, and ultrastructural study of 37 cases.

BACKGROUND: Lichen striatus (LS) is a papulosquamous disorder with a distinctive linear distribution. The linearity has been shown to correspond in many cases to the pattern of Blaschko's lines. The etiology is unknown. LS can usually be identified by clinical history and histology of typical lesions. However, the histologic features are diverse and some have stated they are nonspecific. METHODS: In an effort to identify those characteristic features, we have reviewed the routine slides in 37 cases for their diagnostic criteria. Ten cases were studied further by immunohistochemistry. RESULTS: The patient's ages ranged from 1.3 to 49 years with mean age of 17.5 years. A female-to-male ratio was 1.6 to 1. The lesions were predominantly distributed on the extremities in 26/34 cases. The consistent histologic features were: hyperkeratosis (29/37), parakeratosis (21/37) with a few necrotic keratinocytes (28/37) in the epidermis, mild spongiosis (29/37) with exocytosis of lymphocytes (33/37). The dermal infiltrate comprised mainly lymphocytes and macrophages. At the dermal-epidermal junction, the infiltrate was either focal (20/37) or lichenoid (17/37) patterns. Superficial and deep perivascular lymphocytic inflammatory infiltrate was present in most of the cases (33/37). Appendageal involvement (34/37) was in hair follicles (24/37) or eccrine glands or ducts (22/37) or both (12/37). Satellite cell necrosis may be seen (11/37). Colloid bodies were present in 16/37 of the cases. Immunohistochemistry showed that most of the small lymphocytes in the upper dermis and epidermis were positive for CD7. Most of the lymphocytes in the epidermis were positive for CD8. CD1a Langerhans' cells were either decreased (5/10) or increased (3/10) or normal (2/10) in the epidermis. CONCLUSION: The histologic diagnosis of LS can be made on the basis of the combination of these histologic features in the appropriate clinical context. Multiple biopsies may be necessary to determine whether all of these features are present in a given case.

Adolescent↗

PubMed2001

Caenorhabditis elegans auxilin: a J-domain protein essential for clathrin-mediated endocytosis in vivo.

The budding of clathrin-coated vesicles is essential for protein transport. After budding, clathrin must be uncoated before the vesicles can fuse with other membranous structures. In vitro, the molecular chaperone Hsc70 uncoats clathrin-coated vesicles in an ATP-dependent process that requires a specific J-domain protein such as auxilin. However, there is little evidence that either Hsc70 or auxilin is essential in vivo. Here we show that C. elegans has a single auxilin homologue that is identical to mammalian auxilin in its in vitro activity. When RNA-mediated interference (RNAi) is used to inhibit auxilin expression in C. elegans, oocytes show markedly reduced receptor-mediated endocytosis of yolk protein tagged with green fluorescent protein (GFP). In addition, most of these worms arrest during larval development, exhibit defective distribution of GFP-clathrin in many cell types, and show a marked change in clathrin dynamics, as determined by fluorescence recovery after photobleaching (FRAP). We conclude that auxilin is required for in vivo clathrin-mediated endocytosis and development in C. elegans.

Adaptor Proteins, Vesicular Transport↗

PubMed2001

Evidence that RME-1, a conserved C. elegans EH-domain protein, functions in endocytic recycling.

In genetic screens for new endocytosis genes in Caenorhabditis elegans we identified RME-1, a member of a conserved class of Eps15-homology (EH)-domain proteins. Here we show that RME-1 is associated with the periphery of endocytic organelles, which is consistent with a direct role in endocytic transport. Endocytic defects in rme-1 mutants indicate that the protein is likely to have a function in endocytic recycling. Evidence from studies of mammalian RME-1 also points to a function for RME-1 in recycling, specifically in the exit of membrane proteins from recycling endosomes. These studies show a conserved function in endocytic recycling for the RME-1 family of EH proteins.

Animals↗

PubMed2001

Parkin ubiquitinates the alpha-synuclein-interacting protein, synphilin-1: implications for Lewy-body formation in Parkinson disease.

Parkinson disease is a common neurodegenerative disorder characterized by the loss of dopaminergic neurons and the presence of intracytoplasmic-ubiquitinated inclusions (Lewy bodies). Mutations in alpha-synuclein (A53T, A30P) and parkin cause familial Parkinson disease. Both these proteins are found in Lewy bodies. The absence of Lewy bodies in patients with parkin mutations suggests that parkin might be required for the formation of Lewy bodies. Here we show that parkin interacts with and ubiquitinates the alpha-synuclein-interacting protein, synphilin-1. Co-expression of alpha-synuclein, synphilin-1 and parkin result in the formation of Lewy-body-like ubiquitin-positive cytosolic inclusions. We further show that familial-linked mutations in parkin disrupt the ubiquitination of synphilin-1 and the formation of the ubiquitin-positive inclusions. These results provide a molecular basis for the ubiquitination of Lewy-body-associated proteins and link parkin and alpha-synuclein in a common pathogenic mechanism through their interaction with synphilin-1.

Animals↗

PubMed2001

Protection of vascular wall function in insulin-resistant rats from copper oxidative stress.

The effects of oxidative stress on vascular function in the insulin-resistant state were assessed in mesenteric resistance arteries of obese, insulin-resistant (cp/cp) and lean, normal (+/?) JCR : LA-cp rats. Nitric oxide-mediated relaxation of noradrenaline-contracted arteries in response to acetylcholine was impaired after 2 h of incubation with Cu(2+) in both genotypes, with or without the continuing presence of Cu(2+). Relaxation was enhanced on initial exposure to Cu(2+), and post-incubation removal of the Cu(2+) resulted in a greater impairment of relaxation. Arteries from cp/cp rats were less impaired in function by Cu(2+) incubation than were those of +/? controls. Sodium nitroprusside-mediated relaxation was impaired by exposure to Cu(2+), with an accompanying increase in EC(50). The impairment in acetylcholine-mediated relaxation in the arteries from both cp/cp and +/? rats was completely inhibited by co-incubation with copper-zinc superoxide dismutase and catalase, confirming that the impairment associated with Cu(2+) incubation was due to oxidative stress. The impairment appears to involve both smooth muscle and the endothelium. The cp/cp rats showed greater resistance to the effects of oxidative stress on arterial function, possibly due to an adaptation to oxidative stress on arterial function associated with the insulin-resistant state.

Analysis of Variance↗

PubMed2001

Characterization of 13 newly isolated strains of anaerobic, cellulolytic, thermophilic bacteria.

Characteristics of 13 newly isolated thermophilic, anaerobic, and cellulolytic strains were compared with previously described strains of Clostridium thermocellum: ATCC 27405 and JW20 (ATCC 31549). Colony morphology, antibiotic sensitivity, fermentation end-products, and cellulose degradation were documented. All 13 strains were sensitive to erythromycin (5 microg/ml) and chloramphenicol (25 microg/ml), and all strains but one were sensitive to kanamycin (20 microg/ml). Polymerase chain reaction (PCR) amplification using primers based on gene sequences from C. thermocellum ATCC 27405 was successful for all 13 strains in the case of the hydrogenase gene and 11 strains in the case of phosphotransacetylase/acetate kinase genes. Ten strains amplified a product of the expected size with primers developed to be specific for C. thermocellum 16SrRNA primers. Two of the 13 strains did not amplify any product with the PCR primers designed for the phosphotransacetylase/acetate kinase and 16SrRNA primers. A MboI-like GATC- recognizing restriction activity was present in all of the five strains examined. The results of this study have several positive implications with respect to future development of a transformation system for cellulolytic thermophiles.

Bacteria, Anaerobic↗

PubMed2001

Electrochemical determination of dopamine using a poly(2-picolinic acid) modified glassy carbon electrode.

A poly(2-picolinic acid) chemically modified electrode (CME) for the determination of dopamine (DA) by cyclic voltammetry is described. Compared with a bare glassy carbon electrode, the CME exhibits a 200 mV shift of the oxidation potential of DA in the cathodic direction and a marked enhancement of the current response. In pH 7.0 buffer solution, a linear calibration graph is obtained over the range from 2.5 x 10(-7) to 1.0 x 10(-5) mol dm-3 with a correlation coefficient of 0.998. The detection limit is 3.0 x 10(-8) mol dm-3. The modified electrode eliminated efficiently the interference from ascorbic acid (AA) when present in a 150-fold concentration ratio. It also showed excellent stability and reproducibility.

Cardiotonic Agents↗

PubMed2001

Development of a thickness shear mode acoustic sensor based on an electrosynthesized molecularly imprinted polymer using an underivatized amino acid as the template.

The preparation and characterization of electrosynthesized poly(o-phenylenediamine) (iPoPD) as a molecular imprinting material were studied by an in situ quartz crystal impedance method. The changes of delta f0, delta R1, delta L1 and delta C0 suggest that the polymer film was compact and rigid. The thickness shear mode (TSM) acoustic sensor modified with this material exhibits molecular recognition ability to the template molecule of DL-phenylalanine. In the range 2-20 mM, a linear relationship between the frequency shift delta f0 and logC was found from the calibration graph. Scatchard analysis of the relevant calibration graph offers information on the equilibrium of the binding interaction and the recognition sites. Using this electropolymerization technology, the preparation of the sensor was very simple and the reproducibility of preparation was very good. In particular, it offers possibilities for sensor miniaturization.

Journal Article↗

PubMed2001

Extracorporeal photochemotherapy in patients with steroid-dependent Crohn's disease: a prospective pilot study.

BACKGROUND: Extracorporeal photochemotherapy has been proven effective in selected T-cell mediated diseases. AIM: To evaluate the safety and efficacy of extracorporeal photochemotherapy in patients with steroid-dependent Crohn's disease by an open, monocentric trial in three phases of 24 weeks each. METHODS: In phase 1 standardized steroid tapering was initiated in patients with a history of steroid-dependent Crohn's disease. Those with a prospectively evaluated maintenance dose of at least 10 mg/day prednisolone continued steroid-withdrawal under the application of extracorporeal photochemotherapy in phase 2. The duration of remission or response was followed during phase 3. Colonic tissue bioptically obtained before and after extracorporeal photochemotherapy was studied by immunofluorescence microscopy for the presence of photoadduct positive cells. RESULTS: Out of 24 patients included in phase 1, 10 entered phase 2 for extracorporeal photochemotherapy. Four subjects achieved remission and four others response. Significant reductions in serum C-reactive protein levels and intestinal permeability were measured, as well as increases in quality of life and plasma adrenocorticotropic hormone levels. No major side-effects were observed. Remission remained stable in three out of four patients during phase 3. In three patients, positive nuclear stainings of photoadducts were detected in colonic mononuclear cells after extracorporeal photochemotherapy. CONCLUSIONS: Extracorporeal photochemotherapy represents a safe steroid-sparing approach in patients with Crohn's disease and is associated with intestinal homing of photopheresed cells.

Adult↗

PubMed2001

Acholeplasma laidlawii up-regulates granulysin gene expression via transcription factor activator protein-1 in a human monocytic cell line, THP-1.

An antimicrobial protein granulysin is constitutively expressed in cytotoxic T lymphocytes (CTL) and natural killer (NK) cells. However, little is known about the precise regulatory mechanisms underlying granulysin gene expression. In this study, we examined the regulatory mechanisms underlying granulysin gene expression using a human monocytic cell line, THP-1, treated with Acholeplasma laidlawii. The level of granulysin mRNA expression in THP-1 cells was significantly augmented in response to stimulation with A. laidlawii. The transfection of reporter gene constructs into THP-1 cells indicated that DNA sequences between residues -329 and -239, relative to the transcriptional start site of the granulysin gene, are responsible for mediating gene induction. In addition, mutagenesis of a putative activator protein-1 (AP-1)-binding site between residues -277 and -271 in the granulysin promoter resulted in the reduction of granulysin promoter activity. Electrophoretic mobility shift assays (EMSA) demonstrated that nuclear extract prepared from A. laidlawii-treated THP-1 cells can generate specific binding to DNA oligonucleotides encompassing the AP-1-binding site, whereas unstimulated nuclear extract from the cells failed to do so. Furthermore, competition and supershift assays confirmed that A. laidlawii can induce the activation of AP-1. These results indicate that AP-1 dominantly participates in the regulation of inducible granulysin gene expression in THP-1 cells. Therefore, the finding of inducible granulysin gene expression by A. laidlawii suggests that inducible granulysin in macrophages may function as a protective weapon when microbial invasion occurs.

Acholeplasma laidlawii↗

PubMed2001

A fast neutron deletion mutagenesis-based reverse genetics system for plants.

A new reverse genetics method has been developed to identify and isolate deletion mutants for targeted plant genes. Deletion mutant libraries are generated using fast neutron bombardment. DNA samples extracted from the deletion libraries are used to screen for deletion mutants by polymerase chain reaction (PCR) using specific primers flanking the targeted genes. By adjusting PCR conditions to preferentially amplify the deletion alleles, deletion mutants were identified in pools of DNA samples, each pool containing DNA from 2592 mutant lines. Deletion mutants were obtained for 84% of targeted loci from an Arabidopsis population of 51 840 lines. Using a similar approach, a deletion mutant for a rice gene was identified. Thus we demonstrate that it is possible to apply this method to plant species other than Arabidopsis. As fast neutron mutagenesis is highly efficient, it is practical to develop deletion mutant populations with more complete coverage of the genome than obtained with methods based on insertional mutagenesis. Because fast neutron mutagenesis is applicable to all plant genetic systems, this method has the potential to enable reverse genetics for a wide range of plant species.

Arabidopsis↗

PubMed2001

Expression of antisense SnRK1 protein kinase sequence causes abnormal pollen development and male sterility in transgenic barley.

A chimaeric gene was constructed comprising a wheat high molecular weight glutenin subunit gene promoter, a 304-bp sucrose non-fermenting-1-related (SnRK1) protein kinase sequence in the antisense orientation, and the cauliflower mosaic virus 35S RNA gene terminator. Transgenic barley plants containing the antisense SnRK1 chimaeric gene were produced by particle bombardment of barley immature embryos with the aim of obtaining plants expressing the antisense SnRK1 sequence in the seeds. Despite the fact that the promoter was expected to be active only in seeds, two independent transgenic lines were found to fail to transmit the transgene to the T1 generation. These T0 plants had matured and died before this was discovered, but subsequently four other independent transgenic lines were found to be affected in the same way. Cytological analysis of the pollen grains in these lines showed that about 50% were normal but the rest had arrested at the binucleate stage of development, were small, pear-shaped, contained little or no starch and were non-functional. The presence of antisense SnRK1 transcripts was detected in the anthers of the four lines analyzed and a ubiquitin promoter/UidA (Gus) gene, one of the marker genes codelivered with the antisense gene, was found to be expressed only in the abnormal pollen. Expression analyses confirmed that SnRK1 is expressed in barley anthers and that expression of one class of SnRK1 transcripts (SnRK1b) was reduced in the abnormal lines. All of the abnormal lines showed approximately 50% seed set, and none of the transgenes were detected in the T1 generation.

Cell Differentiation↗