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Biomedical subjects

Q Yang

Publications and source records attributed to Q Yang.

At least 235 records · Page 13Linked to original sources
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

Clinical benefit of a diagnostic score for appendicitis: results of a prospective interventional study. German Study Group of Acute Abdominal Pain.

HYPOTHESIS: Clinical use of a diagnostic score improves decision making in acute appendicitis. DESIGN: A before-and-after trial comparing a group of patients undergoing standard diagnostic workup with no additional diagnostic support (phase 1) with a group of patients undergoing additional diagnostic support with a score (phase 2). SETTING: Eight departments of surgery in Germany and Austria. PATIENTS: Eight hundred seventy patients with acute abdominal pain in phase 1 (October 1, 1994, to April 30, 1995) and 614 patients in phase 2 (February 1, 1995, to August 15, 1995). INTERVENTIONS: Structured and standardized history and clinical investigation in all patients with computer-based documentation; introduction of the diagnostic score after phase 1 and computer-supported use of the score in phase 2. RESULTS: The 2 groups were comparable with respect to signs, symptoms, and investigations related to acute appendicitis. Diagnostic performance of the final examiner decreased with the score (specificity, 86% vs 78%; positive predictive value, 67% vs 50%; and accuracy, 88% vs 81%). There were no differences in the rates of perforated appendix, appendectomy with normal findings, and complications; however, the delayed appendectomy rate (2% vs 8%) and the delayed discharge rate (11% vs 22%) were significantly lower with diagnostic support by the score (P = .02). CONCLUSIONS: Integration of a score into the diagnostic process may have unforeseen clinical effects. The tested score cannot be recommended as a standard tool for diagnostic decision making in acute appendicitis.

Acute Disease↗
PubMed1999

Using case-control designs for genome-wide screening for associations between genetic markers and disease susceptibility loci.

We used a case-control design to scan the genome for any associations between genetic markers and disease susceptibility loci using the first two replicates of the Mycenaean population from the GAW11 (Problem 2) data. Using a case-control approach, we constructed a series of 2-by-3 tables for each allele of every marker on all six chromosomes. Odds ratios (ORs) and 95% confidence intervals (95% CI) were estimated for all alleles of every marker. We selected the one allele for which the estimated OR had the minimum p-value to plot in the graph. Among these selected ORs, we calculated 95% CI for those that had a p-value < or = adjusted alpha level. Significantly high ORs were taken to indicate an association between a marker locus and a suspected disease-susceptibility gene. For the Mycenaean population, the case-control design identified allele number 1 of marker 24 on chromosome 1 to be associated with a disease susceptibility gene, OR = 2.10 (95% CI 1.66-2.62). Our approach failed to show any other significant association between case-control status and genetic markers. Stratified analysis on the environmental risk factor (E1) provided no further evidence of significant association other than allele 1 of marker 24 on chromosome 1. These data indicate the absence of linkage disequilibrium for markers flanking loci A, B, and C. Finally, we examined the effect of gene x environment (G x E) interaction for the identified allele. Our results provided no evidence of G x E interaction, but suggested that the environmental exposure alone was a risk factor for the disease.

Alleles↗
PubMed1999

Whole genome association studies for genes affecting alcohol dependence.

We applied the transmission/disequilibrium test (TDT) for sibs (S-TDT) and for families with one parent (1-TDT), to the Collaborative Study on the Genetics of Alcoholism data set. The combined test is used to screen the whole genome to locate genes responsible for alcohol dependence. This analysis supports the previous finding that the region close to GABRB1 on chromosome 4 might be associated with alcohol dependence. The regions close to D6S474 and D11S1998 are also of particular interest. We found segregation distortion at the GR1K1 locus. The segregation distortion might be due to the binning method used in genotyping at this locus.

Alcoholism↗
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

Three new mutations in the hepatocyte nuclear factor-1alpha gene in Japanese subjects with diabetes mellitus: clinical features and functional characterization.

AIMS/HYPOTHESIS: Mutations in the hepatocyte nuclear factor-1alpha gene are a common cause of the type 3 form of maturity-onset diabetes of the young. We examined the clinical features and molecular basis of hepatocyte nuclear factor-1alpha (HNF-1alpha) diabetes. METHODS: Thirty-seven Japanese subjects with early onset Type II (non-insulin-dependent) diabetes mellitus and 45 with Type I (insulin-dependent) diabetes mellitus were screened for mutations in this gene. Functional properties of mutant HNF-1alpha were also investigated. RESULTS: Three new mutations [G415R, R272C and A site of the promoter (+ 102G-to-C)] were found. Insulin secretion was impaired in the three subjects. Insulin and glucagon secretory responses to arginine in the subject with the R272C mutation were also diminished. Molecular biological studies indicated that the G415R mutation generated a protein with about 50% of the activity of wild-type HNF-1alpha. The R272C mutation had no transactivating or DNA binding activity and acted in a dominant negative manner. The + 102 G-to-C mutation in the A site of the promoter activity was associated with an increase in promoter activity and it had 42-75% more activity than the wild-type sequence. CONCLUSION/INTERPRETATION: Mutations in the HNF-1alpha gene may affect the normal islet function by different molecular mechanisms.

Adult↗
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

Expression of Bcl-2, but not Bax, correlates with estrogen receptor status and tumor proliferation in invasive breast carcinoma.

Bcl-2 and Bax have been demonstrated to be associated with apoptosis in breast carcinoma, and the ratio between Bax and Bcl-2 seems to be an important determinant of cellular sensitivity to induction of apoptosis. However, little information is available on the relationship between Bcl-2, Bax and the proliferative activity of breast carcinoma. The purpose of this study was to investigate the significance of apoptosis-related genes bcl-2 and Bax and their correlation with expression of p53, tumor proliferation defined by MIB-1 expression and estrogen receptor status. Immunohistochemistry was performed to determine Bcl-2, Bax, p53, estrogen receptor (ER) and MIB-1 expression in paraffin-embedded tissues of 177 invasive breast cancers. Expression of the anti-apoptotic protein Bcl-2 was not correlated with the pro-apoptotic Bax. Bcl-2 immunostaining displayed a negative correlation with increasing histologic grade, p53 and MIB-1 (P < 0.0001, P < 0.05 and P < 0.0001, respectively) and a positive correlation with rising ER immunostaining (r = 0.305, P < 0.0001). Conversely, expression of the apoptosis-promoting protein Bax did not correlate with increasing histologic grade, p53, MIB-1 or ER status. Neither Bcl-2 expression nor Bax expression correlated with age, menopausal status, tumor size, histologic type or axillary lymph node status. These results imply that Bcl-2 is associated with good prognostic markers and the regulation of Bax is complex and does not necessarily correlate with mutant p53 status in breast cancers.

Adenocarcinoma↗
PubMed1999

Transurethral resection or incision of the prostate and other therapies: a survey of treatments for benign prostatic obstruction in the UK.

OBJECTIVE: To establish the current usage of transurethral incision of the prostate (TUIP) and other forms of treatment for benign prostatic obstruction (BPO). METHODS: The Prostate Trial Office (PROTO) sent a survey questionnaire to all 376 consultant urologists in the UK which asked for estimates of their clinical practice in treating BPO. The survey had three principle aims: to assess the role that the determination of prostate size has in clinical practice, to determine the nature and frequency of use of a range of therapies including TUIP, and to examine the feasibility of conducting a randomized controlled trial comparing transurethral resection of the prostate (TURP) and TUIP. RESULTS: Of the 376 urologists, 349 replied (response rate 93%); most respondents used prostate size as a determinant when deciding on therapy for BPO (60%). Of their patients with BPO who were treated, 38% received surgical treatment, 33% drug therapies and 29% conservative management. Of the types of surgical treatment, the most commonly used procedure was TURP, in 79% of patients, with only 15% undergoing TUIP. When compared with TURP, TUIP tended to be used for patients with a mean prostate volume of </=25 mL. Only 6% of surgical patients were treated using minimally invasive techniques. CONCLUSION: This survey provides some evidence that prostate size plays an important role in determining the treatment; TUIP appeared to be under-used and other minimally invasive techniques are rarely used in the UK.

Adult↗
PubMed1999

Atrial natriuretic-like peptide and its prohormone within metasequoia.

Metasequoia glyptostroboides was one of the dominant conifers in North America, Asia, and Europe for more than 100 million years since the late Cretaceous Albian Age, but Quaternary glaciations drove the Metasequoia population to apparent extinction. A small pocket of Metasequoia, however, was found in central China in the 1940s representing the only surviving population of this "living fossil" species. Atrial natriuretic peptide, a 28-amino-acid peptide hormone that causes sodium and water excretion in animals, has been found to be part of the first peptide hormonal system in lower plants. The existence of this hormonal system has never been examined within trees of any genus. High-performance gel permeation chromatography of the leaves and stems (i.e., branches) of Metasequoia followed by atrial natriuretic peptide radioimmunoassay revealed an ANP-like peptide and its prohormone (i.e., approximately 13,000 mol wt) were present in both leaves and stems of this conifer. The elution profile of ANP-like peptide in stems of Metasequoia had a shoulder to the left of where pure synthetic ANP elutes suggesting the possibility of a slightly larger peptide eluting within this shoulder secondary to alternate processing of the ANP-like prohormone and similar to what occurs with the kidney of animals. The elution profile of ANP-like peptide in the leaves of Metasequoia revealed two peaks; one where ANP elutes and a second peak suggesting a smaller peptide that has been metabolically processed. The presence of the ANP-like prohormone strongly suggests that ANP-like gene expression is occurring in both leaves and stems of Metasequoia since this prohormone is the gene product of this hormonal system. The presence of the ANP-like hormonal system in trees implies that this hormonal system may have been present early in land plant evolution to allow trees to reach heights of greater than 30 feet where a water flow-enhancing substance is absolutely necessary for water flow to occur to these heights.

Atrial Natriuretic Factor↗
PubMed1999

Perforating appendicitis: is it a separate disease? Acute Abdominal Pain Study Group.

OBJECTIVE: To find out whether perforated and unperforated appendicitis are separate diseases and can be distinguished clinically. DESIGN: Prospective multicentre study. SETTING: 11 departments of surgery in Germany and Austria. SUBJECTS: 519 patients over 6 years old who had histologically confirmed acute appendicitis between October 1994 and March 1996. MAIN OUTCOME MEASURES: Differences in history, clinical findings, lab results, clinical course and outcome. RESULTS: 92 of the 519 patients (18%) had perforated appendicitis. The following variables were shown by univariate analysis to be significantly more common in the group with perforated appendicitis: rigidity, reduced abdominal wall movement, abdominal distension, reduced bowel sounds (all p<0.001), pale skin (p<0.005), generalised abdominal tenderness, severe abdominal tenderness (both p<0.01), WCC > or =10(9)/L (p<0.05). By multivariate analysis the following variables were significantly more common in the group with perforated appendicitis: age over 50 years (p<0.0001); change in bowel habit and rigidity of the abdominal wall (both p = 0.001); generalised tenderness (p<0.01); male sex (p<0.01); and distended abdomen (p<0.05). Rectal examination failed to make the distinction. CONCLUSIONS: Perforated and unperforated appendicitis behave clinically like two different diseases. They can in most cases reliably be distinguished using clinical criteria alone. Although greater diagnostic accuracy may result in a higher rate of perforation, close observation and timely intervention will only marginally affect the outcome.

Adult↗
PubMed1999

Cigarette smoke induces direct DNA damage in the human B-lymphoid cell line Raji.

Human lymphoid cells (Raji) were exposed to water-soluble compounds from cigarette smoke (CS) generated in a smoking machine. DNA damage, as detected by alkaline single-cell microelectrophoresis (COMET assay), was induced in a time- and concentration-dependent manner in the cells. Most of the rapidly induced DNA damage was attributable to direct-acting compounds since cytochrome P450-related metabolic activities (ethoxy- and pentoxyresorufin-O-deethylases and coumarin-7-hydroxylase) were absent or very low. In addition, induction of DNA damage could be inhibited only slightly by beta-naphthoflavone and coumarin. Vitamin C enhanced DNA damage in Raji cells probably by redox cycling of catechol and hydroquinone present in CS implicating reactive oxygen intermediates as another source of DNA damage. N-acetylcysteine, a radical scavenger and glutathione precursor, reduced DNA damage in Raji cells when exposure to CS was followed by 2 h post-incubation in culture medium. Unrepaired DNA damage caused by CS persisted longer than gamma-irradiation-induced DNA damage. Among the CS constituents, acrolein, but not formaldehyde and acetaldehyde, induced DNA damage although less intensely than CS itself. At 50 and 100 microM concentrations, acrolein also inhibited repair of gamma- irradiation-induced DNA damage in the COMET assay. Inhibition of DNA synthesis by acrolein at 50 microM was demonstrated by an immunochemical assay for bromo-deoxyuridine incorporation; however, inhibition of a representative repair enzyme, 8-oxoguanosine hydrolase, by either CS or acrolein was not observed. The present results further confirm the presence of direct-acting genotoxic components and inhibitors of DNA repair in the gas phase of tobacco smoke, that may contribute to DNA damage and smoking-associated cancers of the upper aerodigestive tract.

Acetaldehyde↗
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

Testing for age-at-onset anticipation with affected parent-child pairs.

The tendency for the onset of a genetic disease to occur at progressively earlier ages or with progressively greater severity in successive generations is known as anticipation. Following the discovery of trinucleotide repeat expansion as a plausible genetic mechanism for anticipation, interest in testing for anticipation has increased. Studies of anticipation can be biased when parents with late onset or children with early onset are preferentially ascertained. This paper presents a nonparametric approach to testing for age-at-onset anticipation that adjusts for such preferential ascertainment. The approach is illustrated through application to data on panic disorder.

Adolescent↗
PubMed1999

Influence of G protein type on agonist efficacy.

An agonist at a specific G protein-coupled receptor may exhibit a range of efficacies for any given response in a cell-specific manner. We report that the relationship between different states of agonism is regulated by the type of G protein expressed in the cell. In NIH-3T3 alpha(2)-adrenergic receptor (AR) transfectants, the alpha(2)-AR agonists clonidine, oxymetazoline, UK-14304, and epinephrine increased [(35)S]guanosine-5'-O-(3-thio)triphosphate binding in a dose-dependent manner from a basal value of 101.2 +/- 6. 5 fmol/mg to a maximal response (100 microM) of 196.6 +/- 9.8, 182.3 +/- 2, 328.1 +/- 11.2, and 340.6 +/- 3 fmol/mg, respectively. Thus, clonidine and oxymetazoline behaved as partial agonists. Receptor-mediated activation of G proteins in membrane preparations was blocked by cell pretreatment with pertussis toxin, indicating receptor coupling to the subgroup of pertussis toxin-sensitive G protein (Gialpha2,3) expressed in NIH-3T3 cells. Ectopic expression of Goalpha1 but not Gialpha1 increased the relative efficacy of clonidine and oxymetazoline such that the two ligands now behaved as close to full agonists in this assay system. The relationship between full and partial agonists in the different genetic backgrounds was not altered by progressive reduction in the amount of G protein available for coupling to receptor. The increased efficacy observed for clonidine in the Goalpha1 transfectants was not due to changes in the relative affinities or amounts of high-affinity, Gpp(NH)p-sensitive binding of agonist. These data suggest that there is little difference in the ability of clonidine to interact with or stabilize alpha(2)-AR-Gialpha2/Gialpha3 versus alpha(2)-AR-Goalpha1 complexes, but that the subsequent step of signal transfer from receptor to G protein is more readily achieved for the clonidine/alpha(2)-AR/Goalpha1 complex. Such observations have important implications for receptor theory and drug development.

3T3 Cells↗