Biomedical subjects

Q Yang

Publications and source records attributed to Q Yang.

At least 19 recordsLinked to original sources

PubMed1999

[Detection of ABO genotypes by simultaneous PCR-RFLP method]

OBJECTIVE: To study human ABO genotyping by means of multiplex PCR and restriction fragment length polymorphism. METHODS: Two specific fragments of ABO gene were simultaneously amplified in a single tube, and then the double restriction digestion with RE Kpn I and Alu I was performed in the same tube. The amplified products were analyzed by PAGE and silver staining. A total of 125 Han unrelated individuals living in Wuhan were genotyped. RESULTS: Six genotypes of ABO were detected and the distribution was in good agreement with Hardy-Weinberg equilibrium. CONCLUSION: The results demonstrate that PCR-RFLP based approach is convenient, reliable and should be of value in forensic application.

Journal Article↗

PubMed1999

Enhancement of UV-induced cytotoxicity by the adeno-associated virus replication proteins.

Adeno-associated virus (AAV) normally requires co-infection of a helper virus to complete its life cycle. However, under conditions of cellular stress, such as treatment with carcinogens or ultraviolet (UV) light, a permissive intracellular environment is established and AAV completes its replicative cycle producing low levels of progeny virus. AAV DNA replication is dependent upon viral replication proteins, Rep78 and Rep68. The detailed mechanism by which these proteins interact with host cell factors is unknown. We have used a cell line (Neo6) that inducibly expresses the AAV Rep proteins to study their effects on cells that have undergone UV-induced DNA damage. Induction of Rep protein expression immediately after a sub-lethal dose of UV irradiation resulted in rapid cell killing. Those cells that die had chromatin condensation while cellular membranes remained intact, suggesting that concurrent Rep expression and UV damage induces an apoptosis-like response. However, we did not observe any DNA degradation. Thus we believe that the combination of Rep expression and UV irradiation induces cell death that shares some of the characteristics of apoptosis. UV irradiation and Rep expression induced an increase in the level of the CDK inhibitor, p21Cip, and the appearance of modified forms of both p21Cip and Bcl-2. Alteration of normal expression of these cytostatic/apoptotic proteins provides insight into the intracellular targets of the AAV replication proteins.

Apoptosis↗

PubMed1999

Covalent immobilization of unilamellar liposomes in gel beads for chromatography.

For immobilized (proteo)liposome chromatography, unilamellar liposomes were covalently bound within gel beads that had been activated by CNBr, N-hydroxysuccinimide, tresyl, or chloroformate. Liposomes composed of phosphatidylcholine (PC) and 2 mol% of amino-containing lipid (phosphatidylethanolamine-caproylamine) were immobilized in the activated gels at 5-35 micromol lipid/ml gel and yields of 11-70%. The highest immobilized amount was found in chloroformate-activated TSK G6000PW gel, which contains large pore size (>100 nm). Liposomes composed of PC alone could also be attached to the chloroformate-activated gels at 33-42 micromol/ml gel and yields of 58-65%, probably by crosslinking of the phosphate moiety of phospholipid with the active group of the adsorbent. Liposomes prepared by various phospholipids with or without amino-containing lipids can generally be immobilized in the chloroformate-activated gels. The covalently bound liposomes were characterized by their high stability, unilamellarity, permeability of the membranes, and drug-membrane partition properties. A stable membrane phase was constructed for chromatographic experiments to be performed under extreme elution conditions.

Chromatography, Gel↗

PubMed1999

Chemokine and chemokine receptor gene variants and risk of non-Hodgkin's lymphoma in human immunodeficiency virus-1-infected individuals.

Normal B-lymphocyte maturation and proliferation are regulated by chemotactic cytokines (chemokines), and genetic polymorphisms in chemokines and chemokine receptors modify progression of human immunodeficiency virus-1 (HIV-1) infection. Therefore, 746 HIV-1-infected persons were examined for associations of previously described stromal cell-derived factor 1 (SDF-1) chemokine and CCR5 and CCR2 chemokine receptor gene variants with the risk of B-cell non-Hodgkin's lymphoma (NHL). The SDF1-3'A chemokine variant, which is carried by 37% of whites and 11% of blacks, was associated with approximate doubling of the NHL risk in heterozygotes and roughly a fourfold increase in homozygotes. After a median follow-up of 11.7 years, NHL developed in 6 (19%) of 30 SDF1-3'A/3'A homozygotes and 22 (10%) of 202 SDF1-+/3'A heterozygotes, compared with 24 (5%) of 514 wild-type subjects. The acquired immunodeficiency syndrome (AIDS)-protective chemokine receptor variant CCR5-triangle up32 was highly protective against NHL, whereas the AIDS-protective variant CCR2-64I had no significant effect. Racial differences in SDF1-3'A frequency may contribute to the lower risk of HIV-1-associated NHL in blacks compared with whites. SDF-1 genotyping of HIV-1-infected patients may identify subgroups warranting enhanced monitoring and targeted interventions to reduce the risk of NHL.

Acquired Immunodeficiency Syndrome↗

PubMed1999

Partitioning of triphenylalkylphosphonium homologues in gel bead-immobilized liposomes: chromatographic measurement of their membrane partition coefficients.

Unilamellar liposomes of small or large size, SUVs and LUVs, respectively, were stably immobilized in the highly hydrophilic Sepharose 4B or Sephacryl S-1000 gel beads as a membrane stationary phase for immobilized liposome chromatography (ILC). Lipophilic cations of triphenylmethylphosphonium and tetraphenylphosphonium (TPP+) have been used as probes of the membrane potential of cells. Interaction of TPP+ and triphenylalkylphosphonium homologues with the immobilized liposomal membranes was shown by their elution profiles on both zonal and frontal ILC. Retardation of the lipophilic cations on the liposome gel bed was increased as the hydrophobicity of the cations increased, indicating the partitioning of lipophilic cations into the hydrocarbon region of the membranes. The cations did not retard on the Sepharose or Sephacryl gel bed without liposomes, confirming that the cations only interact with the immobilized liposomes. Effects of the solute concentration, flow rate, and gel-matrix substance on the ILC were studied. The stationary phase volume of the liposomal membranes was calculated from the volume of a phospholipid molecule and the amount of the immobilized phospholipid, which allowed us to determine the membrane partition coefficient (KLM) for the lipophilic cations distributed between the aqueous mobile and membrane stationary phases. The values of KLM were generally increased with the hydrophobicity of the solutes increased, and were higher for the SUVs than for the LUVs. The ILC method described here can be applied to measure membrane partition coefficients for other lipophilic solutes (e.g., drugs).

Cations↗

PubMed1999

Demonstration of heterodimer formation between S100B and S100A6 in the yeast two-hybrid system and human melanoma.

S100B (S100beta) and S100A6 (calcyclin) are two 10-kDa Ca2+- and Zn2+-binding proteins coexpressed in melanoma and cell-cycle regulated. These proteins are members of the S100 subfamily and are thought to exert their function through interaction with intracellular target proteins. In order to search for potential target proteins interacting with S100B, we used a yeast two-hybrid strategy with human S100B as bait to screen a human brain cDNA library. The fusion proteins interacting with the S100B bait were identified as S100B, S100A1, and S100A6. This indicates the potential of S100B to form homodimers and heterodimers with other members of the S100 subfamily. By Northern and Western blotting, S100B and S100A6 were shown to be expressed at high levels in a panel of human melanoma cell lines. S100B and S100A6 were coimmunoprecipitated from melanoma cell lysates in the presence of 100 microM Zn2+. Confocal microscopy demonstrated that both proteins were distributed throughout the cytoplasm and concentrated in the nucleus. The demonstration of an association and colocalization of S100B and S100A6 in melanoma supports the possibility that an S100B/S100A6 heterodimer plays a functional role in these cells.

Animals↗

PubMed1999

Analysis of lipophilic peptides and therapeutic drugs: on-line-nonaqueous capillary electrophoresis-mass spectrometry.

This minireview addresses the usefulness of nonaqueous capillary electrophoresis-mass spectrometry (NACE-MS), mainly in the analysis of lipophilic peptides such as gramicidin S and bacitracin, and therapeutic drugs such as pyrazoloacridine, the H2-antagonist mifentidine, tamoxifen, and their metabolites. The beneficial effects of NACE-MS in typical bioanalytical applications are analyzed case by case. A suitable and widely applicable NACE-MS analysis is identified, which is an electrolyte buffer containing ammonium acetate (5-50 mM) and/or acetic acid (up to 100 mM) with varying composition of organic solvents. Either acetonitrile or methanol or a mixture of the two are mostly utilized in the nonaqueous media. Primary considerations in developing NACE-MS are also discussed.

Acridines↗

PubMed1999

Cloning, expression, and characterization of a DNA binding domain of gpNu1, a phage lambda DNA packaging protein.

Terminase is an enzyme from bacteriophage lambda that is required for insertion of the viral genome into an empty pro-capsid. This enzyme is composed of the viral proteins gpNu1 (20.4 kDa) and gpA (73.3 kDa) in a holoenzyme complex. Current models for terminase assembly onto DNA suggest that gpNu1 binds to three repeating elements within a region of the lambda genome known as cosB which, in turn, stimulates the assembly of a gpA dimer at the cosN subsite. This prenicking complex is the first of several stable nucleoprotein intermediates required for DNA packaging. We have noted a hydrophobic region within the primary amino acid sequence of the terminase gpNu1 subunit and hypothesized that this region constitutes a protein-protein interaction domain required for cooperative assembly at cosB and that is also responsible for the observed aggregation behavior of the isolated protein. We therefore constructed a mutant of gpNu1 in which this hydrophobic "domain" has been deleted in order to test these hypotheses. The deletion mutant protein, gpNu1DeltaK, is fully soluble and, unlike full-length protein, shows no tendency toward aggregation; However, the protein is a dimer under all experimental conditions examined as determined by gel permeation and sedimentation equilibrium analysis. The truncated protein is folded with evidence of secondary and tertiary structural elements by circular dichroism and NMR spectroscopy. While physical and biological assays demonstrate that gpNu1DeltaK does not interact with the terminase gpA subunit, the deletion mutant binds with specificity to cos-containing DNA. We have thus constructed a deletion mutant of the phage lambda terminase gpNu1 subunit which constitutes a highly soluble DNA binding domain of the protein. We further propose that the hydrophobic amino acids found between Lys100 and Pro141 define a self-association domain that is required for the assembly of stable nucleoprotein packaging complexes and that the C-terminal tail of the protein defines a distinct gpA-binding site that is responsible for terminase holoenzyme formation.

Bacteriophage lambda↗

PubMed1999

Positive regulation of adenylyl cyclase activity by a galphai homolog in Neurospora crassa.

GNA-1 and GNA-2 are two G protein alpha subunits from the filamentous fungus Neurospora crassa. Loss of gna-1 leads to multiple phenotypes, while Deltagna-2 strains do not exhibit visible defects. However, Deltagna-1Deltagna-2 mutants are more affected in Deltagna-1 phenotypes. Here we report a biochemical investigation of the roles of GNA-1 and GNA-2 in cAMP metabolism. Assays of Mg2+ ATP-dependent adenylyl cyclase activity (+/-GppNHp) in extracts from submerged cultures indicated that Deltagna-2 strains were normal, whereas Deltagna-1 and Deltagna-1Deltagna-2 strains had only 10-15% the activity of the wild-type control. Levels of the Gbeta protein, GNB-1, were normal in Deltagna-1 strains, excluding altered GNB-1 production as a factor in loss of adenylyl cyclase activity. Steady-state cAMP levels in Deltagna-1 and Deltagna-1Deltagna-2 mutants were reduced relative to wild-type under conditions that result in morphological abnormalities (solid medium), while levels in submerged culture were normal. cAMP phosphodiesterase activities in submerged cultures of Deltagna-1 and/or Deltagna-2 strains were lower than in wild-type; the individual deletions were additive in decreasing activity. These results suggest that in submerged culture, N. crassa, like mammalian systems, possesses compensatory mechanisms that maintain cAMP at relatively constant levels. Furthermore, the finding that Mg2+ATP-dependent adenylyl cyclase activity in wild-type cell extracts could be inhibited using anti-GNA-1 IgG suggests that GNA-1 directly interacts with adenylyl cyclase in N. crassa.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed1999

Ultrasonography for diagnosis of acute appendicitis: results of a prospective multicenter trial. Acute Abdominal Pain Study Group.

A prospective multicenter observational trial was performed to assess the performance and clinical benefit of ultrasonography of the appendix in the routine clinical examination. Included in the study were 2280 patients with acute abdominal pain from 11 surgical departments in Germany and Austria. Ultrasonography of the appendix was performed in 870 (38%) of the patients (range 16-85%). The overall sensitivity of ultrasonography of the appendix was 55% (13-90%), the specificity 95% (range 82-100%), positive predictive value 81% (50-100%), and negative predictive value 85% (68-96%). With respect to single ultrasound scan findings, adequate sensitivity (44%) was achieved only with the target phenomen, not with the other criteria. There were no correlations between the ultrasound findings of the appendix and the diagnostic accuracy of the clinician, the negative appendectomy rate, or the perforated appendix rate. From the study it can be concluded that there is no proven clinical benefit of ultrasound scanning of the appendix in the routine clinical diagnosis.

Abdominal Pain↗

PubMed1999

Needle-type lactate biosensor.

A needle-type lactate biosensor has been developed for continuous intravascular lactate monitoring. The sensor employs poly(1,3-phenylenediamine) as the inner layer on the platinum electrode in order to eliminate the interference from oxidizable physiological substances. Cross-linking with glutaraldehyde was used for enzyme immobilization. Dithiothreitol was used as the stabilizer of lactate oxidase. PVC (polyvinyl chloride) was chosen as the external diffusion control membrane. Sensor performance was evaluated in vitro and the sensor shows a sensitivity of 10-15 nA/mM, and a linear range from 1 mM to at least 15 mM lactate. Evaluation of the sensor response in blood plasma showed similar sensitivity and linear range as indicated by the calibration curves obtained in buffer solution. The sensor has a short response time of approximately 1 minute. The sensors were operated continuously for 7 days in phosphate buffer containing solution with a concentration at the physiological lactate level. No significant change in sensor sensitivity and its linear range has been observed. Sensors show a minimum change in its performance when stored in buffer at 4 degrees C for at least 9 months.

Biosensing Techniques↗

PubMed1999

Mutational activation of a Galphai causes uncontrolled proliferation of aerial hyphae and increased sensitivity to heat and oxidative stress in Neurospora crassa.

Heterotrimeric G proteins, consisting of alpha, beta, and gamma subunits, transduce environmental signals through coupling to plasma membrane-localized receptors. We previously reported that the filamentous fungus Neurospora crassa possesses a Galpha protein, GNA-1, that is a member of the Galphai superfamily. Deletion of gna-1 leads to defects in apical extension, differentiation of asexual spores, sensitivity to hyperosmotic media, and female fertility. In addition, Deltagna-1 strains have lower intracellular cAMP levels under conditions that promote morphological abnormalities. To further define the function of GNA-1 in signal transduction in N. crassa, we examined properties of strains with mutationally activated gna-1 alleles (R178C or Q204L) as the only source of GNA-1 protein. These mutations are predicted to inhibit the GTPase activity of GNA-1 and lead to constitutive signaling. In the sexual cycle, gna-1(R178C) and gna-1(Q204L) strains are female-fertile, but produce fewer and larger perithecia than wild type. During asexual development, gna-1(R178C) and gna-1(Q204L) strains elaborate abundant, long aerial hyphae, produce less conidia, and possess lower levels of carotenoid pigments in comparison to wild-type controls. Furthermore, gna-1(R178C) and gna-1(Q204L) strains are more sensitive to heat shock and exposure to hydrogen peroxide than wild-type strains, while Deltagna-1 mutants are more resistant. In contrast to Deltagna-1 mutants, gna-1(R178C) and gna-1(Q204L) strains have higher steady-state levels of cAMP than wild type. The results suggest that GNA-1 possesses several Gbetagamma-independent functions in N. crassa. We propose that GNA-1 mediates signal transduction pathway(s) that regulate aerial hyphae development and sensitivity to heat and oxidative stresses, possibly through modulation of cAMP levels.

Alleles↗

PubMed1999

Case-only design to measure gene-gene interaction.

The case-only design is an efficient and valid approach to screening for gene-environment interaction under the assumption of the independence between exposure and genotype in the population. In this paper, we show that the case-only design is also a valid and efficient approach to measuring gene-gene interaction under the assumption that the frequencies of genes are independent in the population. Just as the case-only design requires fewer cases than the case-control design to measure gene-environment interaction, it also requires fewer cases to measure gene-gene interactions.

Epidemiologic Studies↗

PubMed1999

[Detection of ABO genotypes by simultaneous PCR-RFLP method].

ABO Blood-Group System↗

PubMed1999

Evaluation of polycyclic aromatic hydrocarbon-DNA adducts in exfoliated oral cells by an immunohistochemical assay.

Polycyclic aromatic hydrocarbon-DNA adducts were evaluated in oral cells from 98 healthy volunteers by an immunohistochemical method using a specific antiserum against benzo(a)pyrene-DNA adducts revealed by the immunoperoxidase reaction. Mean adduct content, determined as relative staining intensity by absorbance image analyzer, was significantly higher in the cells from tobacco smokers compared with nonsmokers (330 +/- 98, n = 33 versus 286 +/- 83, n = 64, respectively) with a P = 0.013 obtained by two-sample t test with equal variances. We found that in the smoker group, the PAH-DNA adduct content increases with the number of cigarettes. Thus, the relative staining intensity was 305 +/- 105 in the group smoking 1-10 cigarettes/day (n = 16), 347 +/- 77 in the 11-20 group (n = 14), and 386 +/- 112 in the group smoking more than 20 cigarettes/day (n = 3; P = 0.03 by nonparametric test for trend). No significant association was detected between PAH-DNA adducts in oral cells and variables such as residential area, oral infections, alcohol or vitamin intake, grilled food consumption, and professional activity. This work confirms and extends previous data suggesting that this immunohistochemical method might be used as a valuable dosimeter of genotoxic damage in a carcinogen-exposed population, although further studies are needed to verify the applicability of the test in high-risk populations other than smokers.

Adolescent↗

PubMed1998

Hemochromatosis-associated mortality in the United States from 1979 to 1992: an analysis of Multiple-Cause Mortality Data.

BACKGROUND: Hemochromatosis, which can lead to serious chronic diseases resulting from iron overload, has an estimated prevalence of 50 to 80 cases per 10000 persons. However, little population-based information is available on the impact of hemochromatosis on morbidity and mortality. OBJECTIVE: To evaluate trends over 14 years in deaths and medical conditions associated with hemochromatosis in the United States. DESIGN: We searched Multiple-Cause Mortality Files compiled by the National Center for Health Statistics for the years 1979 to 1992 for all records listing hemochromatosis. We used these data to calculate age-adjusted and age-specific mortality rates, identify medical conditions associated with a known diagnosis of hemochromatosis at death, and calculate proportionate mortality ratios for these medical conditions. RESULTS: The listing of hemochromatosis on death certificates increased 60% from 1979 to 1992. Decedents with hemochromatosis were 23, 13, and 5 times more likely to have liver neoplasms, liver disease, and cardiomyopathy, respectively, than were decedents without hemochromatosis. Conversely, decedents with liver neoplasms, liver disease, and cardiomyopathy were 26, 14, and 5 times more likely, respectively, to have hemochromatosis than were decedents without these conditions. Hemochromatosis was 82 times more likely in persons with the combination of liver neoplasms and diabetes and 43 times more likely in those with the combination of liver disease and diabetes than in those without these conditions. CONCLUSIONS: Comparison of the reported prevalence of hemochromatosis among decedents with estimates of prevalence in the general U.S. population suggests that either the penetrance or the recognition of hemochromatosis, or both, is low. Nevertheless, substantial mortality resulting from liver disease, liver neoplasms, cardiomyopathy, and a combination of liver disease and diabetes in patients with hemochromatosis argues for the improved diagnosis and treatment of hemochromatosis in persons with these conditions.

Age Distribution↗

PubMed1998

A new method for estimating the risk ratio in studies using case-parental control design.

The authors describe a new simple noniterative, yet efficient method to estimate the risk ratio in studies using case-parental control design. The new method is compared with two other noniterative methods, Khoury's method and Flanders and Khoury's method, and with a maximum likelihood-based method of Schaid and Sommer. The authors found that the variance of the new estimation method is usually smaller than that of Khoury's method or Flanders and Khoury's method and that it is slightly larger than that of the maximum likelihood-based method of Schaid and Sommer. Despite the slightly large variance of the new estimator compared with that of the maximum likelihood-based method, the simplicity of the new estimator and its variance makes the new method appealing. When genotypic information for only one parent is available, the authors also describe a method to estimate the risk ratio without assuming Hardy-Weinberg equilibrium or random mating. A simple formula for the variance of the estimator is given.

Alleles↗

PubMed1998

5-Benzylidene 1,2-dihydrochromeno[3,4-f]quinolines, a novel class of nonsteroidal human progesterone receptor agonists.

A novel series of nonsteroidal progestins, 5-benzylidene-1, 2-dihydrochromeno[3,4-f]quinolines (2), was discovered, and a preliminary structure-activity relationship study around the 5-benzylidene ring generated several potent human progesterone receptor agonists (compounds 8, 16). These new progestins showed biological activities (EC50 = 5.7 and 7.6 nM) similar to progesterone (EC50 = 2.9 nM) in the cotransfection assay with high efficacy (132% and 166%) and binding affinity (Ki = 0.66 and 0.83 nM) similar to medroxyprogesterone acetate (MPA) (Ki = 0.34 nM). A representative analogue, 8, demonstrated similar oral potency to MPA in the uterine wet weight/mammary gland morphology assay in ovariectomized rats.

Animals↗