Biomedical subjects

Y Zuo

Publications and source records attributed to Y Zuo.

34 records · Page 2Linked to original sources

PubMed1999

SSA/Ro antigen expressed on membrane of UVB-induced apoptotic keratinocytes is pathogenic but not detectable in supernatant of cell culture.

OBJECTIVES: To better understand the potential effect of ultraviolet light on the photosensitivity of patients with lupus erythematosus (LE), to elucidate the mechanisms of SSA/Ro antibody formation after UV exposure, and to investigate the role of this autoantibody in the pathogenesis of skin lesions. METHODS: Primary human keratinocytes were cultured in Medium-154. After ultraviolet-B light (UVB) irradiation, the keratinocytes were treated with affinity-purified anti-SSA/Ro sera and stained with FITC-labeled goat-anti-human IgG and propidium iodide (PI), followed by enzyme digestion with RNase, RNase-free DNase or RNase plus DNase. As target cells, the irradiated keratinocytes were incubated with affinity-purified anti-SSA/Ro sera, with or without fresh human sera as complement. The supernatants of irradiated keratinocytes were analyzed with ELISA method for SSA/Ro antigens. RESULTS: UVB irradiation induced apoptotic blebs on the cell surface. The blebs were composed of ribonucleoproteins and contained SSA/Ro antigens. SSA/Ro antigens expressed on UVB irradiated keratinocytes bound to affinity-purified anti-SSA/Ro sera, leading to complement-dependent cytotoxicity. However, no SSA/Ro antigens were detected in the supernatants. CONCLUSIONS: SSA/Ro, a ribonucleoprotein antigen expressed on UVB irradiated keratinocytes, may be recognized and presented to immune cells by a direct cell-cell contact other than be eliminated into the circulation.

Apoptosis↗

PubMed1999

[Observation on the clinical symptoms and sporocyst excretion in human volunteers experimentally infected with Sarcocystis hominis].

AIM: To investigate the excretion of sporocysts and clinical manifestations in humans experimentally infected of Sarcocystis hominis. METHODS: Three volunteers were infected by eating raw beef containing cysts of S. hominis. One ingested about 1,567 cysts in skeletal muscles of a naturally infected cattle; two volunteers each ingested about 14,740 cysts from an experimentally infected water buffalo meat. Fecal examination by zinc sulfate flotation method was conducted daily since d4 postinfection (pi). RESULTS: Free sporocysts and oocysts were found in their faeces from d11-40, d12-23, d10-30 pi, and peaked at d18, d14, d14. All of them presented clinical symptoms such as abdominal pain, distension, watery diarrhea and eosinophilia 1 wk approximately 4 wk pi and were spontaneously cured within 29 days pi without taking any medicine. CONCLUSION: All the experimentally infected persons had gastrointestinal symptoms and passed sporocysts and oocysts in faeces 10-12 days after infection and persisted for 11-29 days.

Adult↗

PubMed1998

The vacB gene required for virulence in Shigella flexneri and Escherichia coli encodes the exoribonuclease RNase R.

vacB, a gene previously shown to be required for expression of virulence in Shigella and enteroinvasive Escherichia coli, has been found to encode the 3'-5' exoribonuclease, RNase R. Thus, cloning of E. coli vacB led to overexpression of RNase R activity, and partial deletion or interruption of the cloned gene abolished this overexpression. Interruption of the chromosomal copy of vacB eliminated endogenous RNase R activity; however, the absence of RNase R by itself had no effect on cell growth. In contrast, cells lacking both RNase R and polynucleotide phosphorylase were found to be inviable. These data indicate that RNase R participates in an essential cell function in addition to its role in virulence. The identification of the vacB gene product as RNase R should aid in understanding how the virulence phenotype in enterobacteria is expressed and regulated. On the basis of this information we propose that vacB be renamed rnr.

Bacterial Proteins↗

PubMed1997

Identification of the antithrombin III heparin binding site.

The heparin binding site of the anticoagulant protein antithrombin III (ATIII) has been defined at high resolution by alanine scanning mutagenesis of 17 basic residues previously thought to interact with the cofactor based on chemical modification experiments, analysis of naturally occurring dysfunctional antithrombins, and proximity to helix D. The baculovirus expression system employed for this study produces antithrombin which is highly similar to plasma ATIII in its inhibition of thrombin and factor Xa and which resembles the naturally occurring beta-ATIII isoform in its interactions with high affinity heparin and pentasaccharide (Ersdal-Badju, E., Lu, A., Peng, X., Picard, V., Zendehrouh, P., Turk, B., Björk, I., Olson, S. T., and Bock, S. C. (1995) Biochem. J. 310, 323-330). Relative heparin affinities of basic-to-Ala substitution mutants were determined by NaCl gradient elution from heparin columns. The data show that only a subset of the previously implicated basic residues are critical for binding to heparin. The key heparin binding residues, Lys-11, Arg-13, Arg-24, Arg-47, Lys-125, Arg-129, and Arg-145, line a 50-A long channel on the surface of ATIII. Comparisons of binding residue positions in the structure of P14-inserted ATIII and models of native antithrombin, derived from the structures of native ovalbumin and native antichymotrypsin, suggest that heparin may activate antithrombin by breaking salt bridges that stabilize its native conformation. Specifically, heparin release of intramolecular helix D-sheet B salt bridges may facilitate s123AhDEF movement and generation of an activated species that is conformationally primed for reactive loop uptake by central beta-sheet A and for inhibitory complex formation. In addition to providing a structural explanation for the conformational change observed upon heparin binding to antithrombin III, differences in the affinities of native, heparin-bound, complexed, and cleaved ATIII molecules for heparin can be explained based on the identified binding site and suggest why heparin functions catalytically and is released from antithrombin upon inhibitory complex formation.

Anticoagulants↗

PubMed1997

Anemia and perinatal death result from loss of the murine ecotropic retrovirus receptor mCAT-1.

The mCAT-1 gene encodes a basic amino acid transporter that also acts as the receptor for murine ecotropic leukemia viruses. Targeted mutagenesis in embryonic stem cells has been used to introduce a germ-line null mutation into this gene. This mutation removes a domain critical for virus binding and inactivates amino acid transport activity. Homozygous mutant pups generated from these cells were approximately 25% smaller than normal littermates, very anemic, and died on the day of birth. Peripheral blood from homozygotes contained 50% fewer red blood cells, reduced hemoglobin levels, and showed a pronounced normoblastosis. Histological analyses of bone marrow, spleen, and liver showed a decrease in both erythroid progenitors and mature red blood cells. Mutant fetal liver cells behaved normally in in vitro hematopoietic colony-forming assays but generated an anemia when transplanted into irradiated C.B.-17 SCID mice. Furthermore, reconstitution of the white cell compartment of SCID mice by mutant fetal liver cells was less complete than that observed with a mixed population of wild-type and heterozygous fetal liver cells. Primary embryo fibroblasts from mutant mice were completely resistant to ecotropic retrovirus infection. Thus, mCAT-1 not only appears to be the sole receptor for a group of murine ecotropic retroviruses associated with hematological disease but also plays a critical role in both hematopoiesis and growth control during mouse development.

Anemia↗

PubMed1997

Large-scale production of class I bound peptides: assigning a signature to HLA-B*1501.

A peptide-based vaccine must be bound and presented by major histocompatibility complex class I molecules to elicit a CD8(+) T-cell response. Because class I HLA molecules are highly polymorphic, it has yet to be established how well a vaccine peptide that stimulates one individual's CD8(+) cytotoxic T lymphocytes will be presented by a second individual's different class I molecules. Therefore, to facilitate precise comparisons of class I peptide binding overlaps, we uniquely combined hollow-fiber bioreactors and mass spectrometry to assign precise peptide binding signatures to individual class I HLA molecules. In applying this strategy to HLA-B*1501, we isolated milligram quantities of B*1501-bound peptides and mapped them using mass spectrometry. Repeated analyses consistently assign the same peptide binding signature to B*1501; the degree of peptide binding overlap between any two class I molecules can thus be determined through comparison of their peptide signatures.

Cytotoxicity, Immunologic↗

PubMed1997

[The experimental study of Pseudomonas contamination in soft drinks].

Bymeans of this study, we have found out about the situation of Pseudomons contamination in the soft drinks which are manufactured and sold at the area of Nanchang City. In the course of this study, we examined total 416 specimens, in which we found that 69 specimens were positive reaction. The positive rate made up 16.59% of the total specimens. From these 69 positive specimens we separate isolated andidentified the following Pseudomonas 111 strains including 16 different species: P. aeruginosa, 9; P. fluorescens biovars; 11; P. putida biovars, 14; P. syringae pathovars, 5; P. mendocina, 5; P. alcaligenes, 23; P. pseudoalcaligenes, 10; P. cepacia, 17; P. solanacearum, 1; P. testosteroni, 1; P. delafieldii, 3; P. facilis, 6; P. flava 1; P. psenudoflava, 2; P. palleronii, 1; and a new species of Pseudomonas--P. halosensibilis. The achievement of this study will provide scientific basis for working out the standards of food safety control and inspection, raising the level of food hygieneinspection, and directing the drinks menufacturers and selling units to strengthen the food safety control and inspection.

Carbonated Beverages↗

PubMed1996

Biochemical evidence that patched is the Hedgehog receptor.

The protein Sonic hedgehog (Shh) is essential for a variety of patterning events during development. It is the signal from the notochord that induces ventral cell fate in the neural tube and somites, and is the polarizing signal for patterning of the anterior-posterior axis of the developing limb bud. Because of these and other inductive functions of Shh, it is important to understand how the Hedgehog (Hh) signal is received by the target cells. Here we describe binding studies using labelled Shh that strongly suggest that the Hh receptor is encoded by patched (ptc), a gene first identified in genetic screens in Drosophila.

Animals↗

PubMed1996

Candidacidal activity of human salivary histatin recombinant variants produced by site-directed mutagenesis.

Histatin 5 (Hst5) is a 24-amino acid (aa) member of the Hst family that is found in human salivary secretions and exhibits candidacidal activity. Hst5 contains a 13-aa region that alone is capable of killing fungal pathogens and is referred to as the functional domain. To investigate the role of specific aa located within the functional domain, the pRSET bacterial expression system was used to produce recombinant Hst5 (re-Hst5) and several re-variants that were generated by site-directed mutagenesis. The vector pRSETC expresses genes of interest as fusion proteins attached to the carboxy end of an N-terminal His6 tag that binds to nickel (Ni2+). The re-variants were generated using the polymerase chain reaction (PCR) and had Gly substituted for either the His, Glu or Lys/Arg within the functional domain. PCR products that encoded either the wild-type or variant forms of re-Hst5 were inserted into pRSETC and produced as fusion proteins which were affinity purified from cell lysates by Ni(2+)-Sepharose chromatography. Fusion proteins were digested with CNBr and re-Hsts were purified by reversed-phase high performance liquid chromatography (RP-HPLC). Re-Hsts were tested in bioassays to measure the ability to kill both Candida albicans (C. albicans) blastoconidia and spheroplasts which were generated by removal of the cell wall. In both assays, re-Hst5 displayed dose-dependent candidacidal activity that was nearly identical to that of native Hst5 purified from human salivary secretions. Re-Hst5 variants with either Glu or Lys/Arg substitutions demonstrated significantly lower candidacidal activity in both assays, while the variant with His mutated showed essentially no activity at physiological concentrations. These results indicate that acidic and basic aa within the functional domain contribute to candidacidal activity and that the His are essential for candidacidal activity. Additionally, since C. albicans spheroplasts were also susceptible to Hsts, the cell wall is not an essential component in the Hst mechanism of candidacidal action.

Amino Acid Sequence↗

PubMed1996

Digestion responses to low oligosaccharide soybean meal by ileally-cannulated dogs.

We investigated digestion responses to conventional and low oligosaccharide soybean meal (SBM) incorporation into diets for dogs. Five female dogs were fitted with T-type cannulas at the terminal ileum and fed five diets in a 5 x 5 Latin square design. Corn grain + poultry meal-based diets containing different levels and types of SBM (0% SBM, 18.55% conventional SBM, 18.55% low oligosaccharide SBM, 37.1% conventional SBM, 37.1% low oligosaccharide SBM) were formulated. Each period consisted of 11 d (7-d diet adaptation; 4-d collection of ileal digesta and feces). Intakes of DM, OM, CP, fat, and GE were not affected (P > .10) by treatment. Higher (P < .01) starch intakes and higher (P < .05) total dietary fiber (TDF) intakes were noted for dogs fed diets with SBM. Digestibilities of CP (P < .04) and starch (P < .002) at the ileum were higher for dogs fed the higher levels of SBM. Ileal digestibilities of most individual amino acids followed the CP response. Total tract digestibility of CP was higher (P < .006) in dogs fed the SBM diets. There were no significant differences in nutrient digestibilities between conventional and low oligosaccharide SBM. Stachyose and raffinose intakes by dogs were decreased dramatically (P < .001) as a result of substituting the low oligosaccharide SBM for conventional SBM at the higher dietary concentration, although sucrose intake by dogs fed low oligosaccharide SBM was higher (P < .001). Galactinol was present in low oligosaccharide SBM but not in conventional SBM. Total tract digestion of all oligosaccharides was near 100%. The low oligosaccharide SBM was digested as extensively, but no better than, conventional SBM.

Amino Acids↗

PubMed1995

Recombinant histatins: functional domain duplication enhances candidacidal activity.

Histatin 3 (Hst3) is a 32-amino-acid (aa) His-rich protein with antimicrobial activity found in human salivary secretions. To explore further the structure/function relationship of Hst, we utilized a bacterial system for the efficient production of recombinant Hst3 (re-Hst3) and Hst variants. Previously, we demonstrated that the middle portion of Hst3 (aa 13-24) contains the functional domain responsible for killing Candida albicans. Using PCR and splice overlap extension, a Hst variant (re-Hst3rep) was made in which the functional domain was repeated in tandem. Using the pRSET bacterial expression system, re-Hst3 and the variant re-Hst3rep were produced as chimeric fusions and were isolated from bacterial sonicates by affinity chromatography. Affinity purified fusion proteins were digested with CNBr and re-Hst were separated from their fusion partners by reverse-phase high-performance liquid chromatography. The activity of re-Hst3 and re-Hst3rep was compared to that of native Hst3 from human salivary secretions in the C. albicans killing assay. The LD50 values for candidacidal activity of native Hst3, re-Hst3 and re-Hst3rep were 7.2, 6.8 and 4.1 nmol/ml, respectively. At lower concentrations re-Hst3rep was five times more active than native Hst3 or re-Hst3 and at even lower concentrations re-Hst3rep exhibited significant candidacidal activity while native Hst3 and re-Hst3 were inactive. These results demonstrate an expression system for production of biologically active functional Hst and Hst variants and shows that repetition of the functional domain of Hst3 enhances candidacidal activity.

Amino Acid Sequence↗

PubMed1995

Differences in the effect of acute ischemia on late potentials in susceptible and resistant dogs for sudden cardiac death.

The low predictive value of the signal averaged ECG (SAECG) at rest may be due to the absence of any physiological perturbation. This study assessed changes of late potentials (LP) in the SAECG due to acute ischemia in five susceptible (S) and five resistant (R) dogs for sudden cardiac death. SAECGs were measured at rest prior to and during the last 3 min of 4 min transient occlusion of the left circumflex artery (CAO). At rest no significant differences were seen in the QRS duration (QRSD), the low amplitude signal duration (LAS40) and the root mean square voltage (RMS20) between S and R dogs. However, acute ischemia caused significant increases in QRSD and LAS40, but only in the S dogs. These results indicate differences in the ischemic modulation of the arrhythmogenic substrate in S and R group. Analysis of LP during acute ischemia may provide an important increase in the positive predictive value of the SAECG.

Animals↗

PubMed1995

Functional comparison of native and recombinant human salivary histatin 1.

Histatin 1 is a histidine-rich phosphoprotein present in human parotid saliva that possesses candidacidal activity and functions in mineralization by adsorbing to hydroxyapatite. The objective of the present study was to develop a system for recombinant production of histatin 1 and to examine the role of phosphorylation in the functional activities of this molecule. Native histatin 1 (containing a phosphoserine at residue 2) was purified from parotid saliva, whereas a bacterial expression system was used to produce a recombinant form of histatin 1 (re-Hst1) that lacked phosphorylated serine. Histatin 1 cDNA was inserted into the vector pGEX-3X, which expresses foreign genes as soluble fusion proteins attached to the carboxyl-terminus of glutathione S-transferase (GST). The GST/re-Hst1 fusion protein was isolated from cell lysates by affinity chromatography on glutathione (GSH)-Sepharose and digested with cyanogen bromide to separate re-Hst1 from the GST fusion partner. The digest was subjected to reversed-phase high-performance liquid chromatography on a C18 column, and re-Hst1 was eluted as a well-defined peak. The yield of re-Hst1 was 4 mg/L of bacterial culture. Amino-terminal sequencing and amino acid analysis confirmed the final product as re-Hst1. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed that native histatin 1 and re-Hst1 had the same apparent molecular weights, while cationic PAGE showed that re-Hst1 was more basic. Phosphate analysis indicated 1 mol phosphate/mol of native histatin 1, while re-Hst1 lacked any detectable phosphate. Re-Hst1 demonstrated candidacidal activity comparable to that of native histatin 1, but displayed substantially lower binding to hydroxyapatite. These results show that phosphorylation of histatin 1 at residue 2 contributes significantly to its ability to bind to hydroxyapatite.

Antifungal Agents↗

PubMed1995

Immunoglobulin depositions in peripheral nerves in polymyositis.

An immunocytochemical study was performed in 6 peripheral nerve specimens from 6 cases of polymyositis. The results revealed that depositions of IgG, IgM, IgA and C3 were found in the epineurium, perineurium and the walls of capillaries. These findings demonstrated that depositions of immunoglobulins and the complement-mediated immunoreaction may play an important role in pathogenesis of polymyositis with peripheral nerve involvements.

Adult↗

PubMed1994

Oligonucleotide probes for mutans streptococci.

Oligodeoxyribonucleotide probes complementary to hypervariable regions of the 16S ribosomal RNA were designed for specificity toward Streptococcus mutans and Streptococcus sobrinus. The probes were tested for specificity and sensitivity by hybridization with nucleic acid from over 100 mutans and non-mutans oral streptococci and other common oropharyngeal bacteria. Probes designated SM002 and SM010 were 100% sensitive and > 99% specific for S. mutans. Probe SSP001, designed to detect both S. mutans and S. sobrinus, was 88% sensitive and > 99% specific. The probes were able to detect nucleic acid extracted from 3 x 10(4)-1 x 10(5) homologous bacteria. Sensitivity did not vary significantly with the growth state of the cells, except for diminished signals when using nucleic acid extracted from very old cultures. The probes correctly identified 72 S. mutans colonies isolated from 10 volunteer saliva samples, using sugar utilization patterns as a reference standard. Ten isolates resembling S. mutans by colony morphology but not by sugar utilization patterns were correctly distinguished from mutans streptococci by the probes. These results demonstrate that oligonucleotide probes can accurately identify S. mutans in saliva samples.

Base Sequence↗

PubMed1992

Are radar detector users less safe than nonusers?

One hundred and seventy-four drivers who had purchased special insurance coverage during 1988-1989 for in-vehicle equipment that included a radar detector were compared to a similarly sized and sociodemographically stratified driver population random sample. It was found that the radar detector owners had significantly more accident claims and speeding convictions during the period 1986-1989 than those representing the general driver population.

Accidents, Traffic↗