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PubMed2002

Comparative toxicity and ecdysone receptor affinity of non-steroidal ecdysone agonists and 20-hydroxyecdysone in Chironomus tentans.

Ecdysone agonists belonging to the bisacylhydrazine class of compounds are a new generation of insecticidal compounds that cause premature lethal molts in susceptible intoxicated insects. While two of the bisacylhydrazines (coded as RH-5992 and RH-2485) are predominantly toxic to lepidopteran pests, RH-5849, which has not been commercialized, has a broader spectrum of toxicity. We have carried out toxicity bioassays with last (4th) instar Chironomus tentans L. larvae, radioligand binding assays using bacterial fusion proteins of C. tentans ecdysone receptor and ultraspiracle (CtEcR, CtUSP), and C. tentans imaginal disc development assays to compare the relative potencies of the three bisacylhydrazine compounds as well as of 20-hydroxyecdysone (20E). In all three assays, the potency of the three bisacylhydrazines was in the order RH-2485>RH-5992>RH-5849. While in toxicity assays 20E was ineffective, most likely due to rapid metabolism, it was more potent than RH-5849 but less so than RH-5992 and RH-2485 in imaginal disc assays. In summary, we compared the potencies of the ecdysone agonists for C. tentans at three levels: whole organism, imaginal discs and the receptor level, and our results indicate that the increased toxicity of the non-steroidal ecdysone agonists for C. tentans has a high correlation to the affinity of these compounds for CtEcR/CtUSP bacterially expressed proteins. Our results, though, do not exclude reasons of metabolic stability of the compounds in C. tentans, which we have not investigated in this report.

Animals↗

PubMed2003

Hypoxia up-regulates prolyl hydroxylase activity: a feedback mechanism that limits HIF-1 responses during reoxygenation.

The mechanism by which hypoxia induces gene transcription is now well established. Hypoxia reduces activity of prolyl hydroxylases (PHD) that hydroxylate specific proline residues in the oxygen-dependent degradation domain (ODD) of hypoxia-inducible factor-1alpha (HIF-1alpha). As a consequence, HIF-1alpha accumulates and promotes hypoxic tolerance by activating gene transcription. This paper identifies the three forms of PHDs in rats and shows that a period of hypoxia selectively increases expression of PHD-2 mRNAs levels. We developed assays for PHD activity that used (i) the peptide-specific conversion of labeled 2-oxoglutarate into succinate and (ii) the binding of the von Hippel-Lindau protein to a glutathione S-transferase-ODD fusion protein. The two assays indicated a low enzymatic activity in normoxic and hypoxic cells and a rapid increase during reoxygenation. We also developed hydroxyproline-specific antibodies that recognized hydroxylated forms of a fusion protein (ODD-green fluorescent protein) that combined the ODD domain of HIF-1alpha and the green fluorescent protein. Using this antibody, we demonstrated that reoxygenation induced a rapid hydroxylation of Pro-564, which was followed by a massive degradation of the proteins. The results suggest that a hypoxic upregulation of PHD (presumably PHD-2) acts as a feedback mechanism to stop hypoxic responses in reoxygenated cells. We propose that proline hydroxylation might play a role in hypoxic preconditioning.

Animals↗

PubMed2005

Acute phase proteins in dogs and cats: current knowledge and future perspectives.

The acute phase response is a nonspecific inflammatory reaction of the host that occurs shortly after any tissue injury. The response includes changes in the concentration of plasma proteins called acute phase proteins (APPs), some of which decrease in concentration (negative APPs), such as albumin or transferrin, and others of which increase in concentration (positive APPs), such as C-reactive protein, serum amyloid A, haptoglobin, alpha-1-acid glycoprotein, and ceruloplasmin. Most positive APPs are glycoproteins synthesized mainly by hepatocytes upon stimulation by proinflammatory cytokines and released into the bloodstream. The acute phase response and clinical application of monitoring APPs in dogs and cats are reviewed in this article, including biochemical characteristics, assays developed for each individual APP, and preanalytic and analytic factors influencing APP results that should be taken into account for proper and adequate clinical interpretation. In addition, the diagnostic use of APPs and their possible application in monitoring treatment, which can be considered one of the most interesting and promising practical applications of these proteins, will be discussed. Finally, challenges and future developments of APPs in dogs and cats will be considered, because it is expected that new and cheaper automated assays for determination of the main APPs in small animals will contribute to a wider use of these proteins as biomarkers of infection and inflammatory lesions.

Acute-Phase Proteins↗

PubMed2003

Peptide-assisted delivery of steric-blocking antisense oligomers.

Cationic transport peptides conjugated to steric blocking antisense oligomers (oligos) increase oligo uptake in eukaryotic cell lines, bacteria and mice. Recent reports of arginine-rich transport peptide conjugates strongly suggest that the mechanism of uptake is primarily endocytotic and that previous assay techniques produced confounding artifacts that led to the old non-endocytotic, membrane-penetrating peptide model. The artifacts result from fixing cells for fluorescent microscopy and from using non-trypsinized cells for flow cytometry. Fixing cells redistributes the peptide or peptide-oligo conjugates associated with the outside of cell membranes and trapped in endosomes, giving apparent diffuse cytosolic and nuclear fluorescence. Cationic peptides bound to the outer surface of cells, if not removed, skew fluorescence data obtained by flow cytometry, leading to the earlier conclusions. Upregulation assays now provide a tool for comparing the efficacy of conjugates, measuring oligo uptake by quantitating antisense activity of conjugates. These assays, developed in cell culture and mouse models, are faster and have higher signal-to-noise ratios than downregulation assays. Thus, a convenient and effective method now exists to screen transport peptides.

Carrier Proteins↗

PubMed1989

Effect of multiple phosphorylations of smooth muscle and cytoplasmic myosins on movement in an in vitro motility assay.

The Nitella-based in vitro motility assay developed by Sheetz and Spudich (Sheetz, M.P., and Spudich, J. A. (1983) Nature 303, 31-35) is a quantitative assay for measuring the velocity of myosin-coated beads over an organized substratum of actin. We have used this assay to analyze the effect of phosphorylation of various sites on the 20,000-Da light chain of smooth muscle and cytoplasmic myosins. Phosphorylation by myosin light chain kinase at serine 19 on the 20,000-Da light chain subunit of smooth muscle myosin from turkey gizzard, bovine trachea and aorta, and of cytoplasmic myosin from human platelets was required for bead movement. The individual phosphorylated myosin-coated beads moved at characteristic rates under the same conditions (turkey gizzard myosin, 0.2 micron/s; aorta or trachea myosin, 0.12 micron/s; and platelet myosin, 0.04 micron/s; in contrast, rabbit skeletal muscle myosin, 2 micron/s). Myosin light chain kinase can also phosphorylate threonine 18 in addition to serine 19, and this phosphorylation resulted in an increase in the actin-activated MgATPase activity (Ikebe, M., and Hartshorne, D.J. (1985) J. Biol. Chem. 260, 10027-10031). Phosphorylation at this site had no effect on the velocity of smooth muscle myosin-coated beads. Protein kinase C (Ca2+/phospholipid-dependent enzyme) can also phosphorylate two to three sites on the 20,000-Da light chain, and this phosphorylation alone did not result in the movement of myosin-coated beads. When myosin that had been previously phosphorylated by myosin light chain kinase at serine 19 was also phosphorylated by protein kinase C, myosin-coated beads moved at the same velocity as beads coated with myosin phosphorylated by myosin light chain kinase alone. Tropomyosin binding to actin also had an activating effect on the actin-activated MgATPase activity through an effect on the Vmax and also resulted in an increase in the velocity of myosin-coated beads.

Actins↗

PubMed1977

Evaluation of estrogen receptor assays in human breast cancer tissue.

Standard dextran-coated charcoal (DCC) and sucrose gradient centrifugation assays for estrogen receptor were compared in a series of human breast cancer tissues. From a quantitative standpoint the results were remarkably similar. A simplified version of the DCC assay compared to the sucrose gradient assay yielded acceptable results. We conclude that, in spite of the lack of specificity controls inherent in the sophisticated standard assays, the simplified DCC assay might be useful if the biopsy specimen is too small to provide the number of aliquots for a standard DCC assay or sufficient protein for a sucrose gradient analysis. It also might be useful in research laboratories attempting to develop assays for multiple receptors or other constituents in a single tumor biopsy specimen.

Breast Neoplasms↗

PubMed1998

[The significance of telomerase activity in patients with gastric cancer].

The activation of telomerase is one of step in carcinogenesis. Therefore, it indicates that the detection of telomerase activity in tissues is useful for cancer diagnosis. TRAP assay developed by Kim et al. is sensitive enough to detect telomerase activity from a telomerase expressing cell. Using TRAP assay kit provided by Oncor Inc., we estimated quantitatively the telomerase activity from benign (atrophic gastritis), premalignant (intestinal metaplasia), and malignant tissues in the stomach. Telomerase activity in gastric cancer tissues was significantly higher than that in tissues which are characterized histologically as intestinal metaplasia or atrophic gastritis. In addition, to exclude interference with TRAP assay by telomerase or PCR inhibitor when telomerase activity was not observed in cancer tissues, the use of internal control (ITAS or TSNT) and dilution of samples should be performed.

Biomarkers, Tumor↗

PubMed1992

Immunomagnetic separation of tumor necrosis factor alpha. I. Batch procedure for human temporomandibular fluid.

A batch separation procedure has been developed for retrieval of tumor necrosis factor (TNF) alpha from the microliter volumes of fluid isolated from the human temporomandibular joint (TMJ). Paramagnetic beads coated with monoclonal antibodies for TNF were used. The beads, and bound TNF, were recovered from solution with the aid of a magnetic field. The amount of bead-bound TNF was quantified using an immuno-based assay developed in this laboratory called the cluster assay. The cluster assay was specific for TNF and linear up to 10 ng. Using these methods we found that TMJ fluid contained 0.2-4.2 ng per 100 microliters of fluid with a mean value of 1.9 ng and a standard deviation of 1.1 ng. This study demonstrates the utility of batch immunomagnetic separation for the concentration and purification of proteins, and the cluster assay for quantification of proteins from microliter volumes of body fluids.

Antibodies, Monoclonal↗

PubMed1995

The comet moment as a measure of DNA damage in the comet assay.

The development of rapid assays of radiation-induced DNA damage requires the definition of reliable parameters for the evaluation of dose-response relationships to compare with cellular endpoints. We have used the single-cell gel electrophoresis (SCGE) or 'comet' assay to measure DNA damage in individual cells after irradiation. Both the alkaline and neutral protocols were used. In both cases, DNA was stained with ethidium bromide and viewed using a fluorescence microscope at 516-560 nm. Images of comets were stored as 512 x 512 pixel images using OPTIMAS, an image analysis software package. Using this software we tested various parameters for measuring DNA damage. We have developed a method of analysis that rigorously conforms to the mathematical definition of the moment of inertia of a plane figure. This parameter does not require the identification of separate head and tail regions, but rather calculates a moment of the whole comet image. We have termed this parameter 'comet moment'. This method is simple to calculate and can be performed using most image analysis software packages that support macro facilities. In experiments on CHO-K1 cells, tail length was found to increase linearly with dose, but plateaued at higher doses. Comet moment also increased linearly with dose, but over a larger dose range than tail length and had no tendency to plateau.

Animals↗

PubMed2001

High-throughput development and characterization of a genomewide collection of gene-based single nucleotide polymorphism markers by chip-based matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

We describe here a system for the rapid identification, assay development, and characterization of gene-based single nucleotide polymorphisms (SNPs). This system couples informatics tools that mine candidate SNPs from public expressed sequence tag resources and automatically designs assay reagents with detection by a chip-based matrix-assisted laser desorption/ionization time-of-flight mass spectrometry platform. As a proof of concept of this system, a genomewide collection of reagents for 9,115 gene-based SNP genetic markers was rapidly developed and validated. These data provide preliminary insights into patterns of polymorphism in a genomewide collection of gene-based polymorphisms.

Alleles↗

PubMed1989

Time-resolved fluoroimmunoassay of 5-methyl-2'-deoxycytidine employing europium-labeled antigen as tracer.

We describe a solid-phase fluoroimmunoassay, based on competition between europium-labeled 5 MeCyd (5-methylcytidine) and sample 5MedCyd (5-methyl-2'-deoxycytidine) for polyclonal anti-5MedCyd antibodies (rabbit). Europium labeling of antigen was performed using a novel polylysine-5MeCyd conjugate. Standard and sample preparations containing 5MedCyd inhibited the binding of the europium-labeled 5MeCyd to the antibody molecules. A second antibody, directed against rabbit IgG, was coated on the solid phase, and bound the IgG-5MeCyd-polylysine-europium complex, giving rapid and complete separation of antibody-bound and free antigen. The measuring range was from 3.7 to 2500 pmol of 5MedCyd per assay. A good correlation between the results obtained with TR-FIA and HPLC was demonstrated when the methods were applied to the measurement of methylation in various DNA samples, enzymatically hydrolyzed to their constituent deoxyribonucleosides. This new TR-FIA possesses the same advantages (high sensitivity, wide assay range, rapidity, simplicity, and low cost) as the previous assay developed in our laboratories. The superiority of the new system is based on (i) its low inter- and intra-assay variation, (ii) low antiserum consumption, and (iii) a protocol, which permits the use of second-antibody-coated microtitration strips common to other assays.

Animals↗

PubMed1998

Characterization of a monoclonal antibody that recognizes a lymphocyte surface antigen for the cetacean homologue to CD45R.

As part of our current efforts to develop assays and reagents to study the immune system of marine mammals, and in view of the effort currently made to develop monoclonal antibodies to cell surface proteins of lymphocyte subsets in different species, the present paper reports on the characterization of a monoclonal antibody against the homologue of CD45R on cetacean lymphocytes. The specificity of this antibody has been characterized on the basis of immunoprecipitation of the antigen it recognized, immunoperoxidase staining on cetacean lymph node and thymus sections, as well as one and two-colour flow cytometric analysis of cetacean peripheral blood mononuclear cells and single-cell suspensions of thymus, lymph node and spleen. Anticetacean CD45R (F21.H) immunoprecipitated proteins of 180, 200 and 220 x 10(3) MW, with the 180 x 10(3) MW from being predominantly expressed on T cells and the 220 x 10(3) MW form expressed predominantly on B cells and thymocytes F21.H labelled all B cells and a proportion of T cells on single-cell suspensions of spleen cells. CD45R- killer whale peripheral blood lymphocytes expressed a higher density of CD2 than CD45R+, a characteristic of memory T cells. Killer whale T lymphocytes also lost the expression of CD45R upon activation with concanavalin A (Con A) and phytohaemagglutinin (PHA). This is the first report of a monoclonal antibody to CD45R in cetaceans, and this antibody is foreseen as a possible valuable diagnostic and research tool to assess immune functions of captive and wild cetaceans as part of the evaluation of their health status.

Animals↗

PubMed1996

Measurement of endothelial cell migration using an improved linear migration assay. Presented at the 1995 Microcirculatory Society Meeting.

OBJECTIVE: The under-agarose migration assay developed for use with endothelial cells provides a measurement of the intrinsic migratory behavior of a cell population. However, the assay is labor intensive and lacks experimental flexibility. This migration assay has been refined and tested on human microvessel endothelial cells in the presence of a migration stimulus or on differing matrix-coated substrates. METHODS: The improved assay retains the linear geometry and mathematical basis of the under-agarose assay. Cells migrating from a cell reservoir formed with a Delrin insert are counted using an automated image-analysis system utilizing a high-contrast, fluorescent nuclear stain. From the cell counts, a stochastic measure of random migration is calculated. RESULTS: Values for random migration between the improved migration assay and the traditional under-agarose assay were very similar. Furthermore, a stochastic measure of endothelial cell migration on fibronectin was determined. CONCLUSIONS: This improved linear migration assay permits readily obtainable measures of endothelial cell migration for a number of experimental conditions. Improvements in the assay include the use of a removable fence for forming cell reservoirs, a nuclear stain to facilitate cell counting, and a more comprehensive analysis of the cell migration.

Animals↗

PubMed1992

PCR and other test systems in human gene therapy.

Three protocols using retroviral-mediated gene transfer are currently undergoing clinical trials. The uniqueness of these protocols, which were the first approved experiments in which genetically engineered cells were administered to human beings, necessitated the development of novel biological and physical safety testing procedures. In addition to standard testing for contamination with exogenous pathogens and toxins, specific tests were developed to assay for the presence of recombinant helper virus in both retroviral vector preparations and in the engineered human cells. Two new assays were developed, an enhanced S+/L-virus assay called 3T3 amplification, and a specific polymerase chain reaction protocol of great sensitivity. The results of these safety tests, along with pre-clinical primate safety studies, and the accumulating clinical data, suggest that retroviral-mediated gene transfer does not pose any serious short-term safety problems for patients enrolled in gene therapy protocols.

Animals↗

PubMed2005

Human tumor cell lysates as a protein source for the detection of cancer antigen-specific humoral immunity.

Measurement of humoral tumor-specific immunity can predict what proteins are specific tumor antigens, be used to evaluate patient diagnosis or prognosis, and function as a method by which one can measure the effects of an immune intervention, such as a vaccine. Antibody assays can easily be adapted to high throughput formats; however, specific reagents needed for assay development often are not available. Developing methods to produce large quantities of purified recombinant tumor antigen proteins for indirect ELISA is both laborious and expensive. In addition, using proteins derived from E. coli might preclude the detection of certain antibody epitopes. We questioned whether a human tumor cell-based ELISA could be developed to assess antibody immunity to common tumor-associated antigens and whether such an ELISA could be optimized to the clinical standards needed for evaluation of large scale trials. Assays were based on the detection of HER-2/neu and p53 antibodies by capture ELISA, using human tumor cell lysate as a protein source. After optimization, the HER-2/neu and p53 ELISA intra-assay coefficients of variation (CV) of positive control sera were consistently 9% and 12%, respectively, at a 1:100 dilution. The HER-2/neu and p53 inter-assay CV of positive control sera over a 5-month time period were 20% and 15%, respectively. The sensitivity and specificity of the ELISAs were evaluated based on comparison to immunoblot. Analysis demonstrated the HER-2/neu ELISA had a specificity of 77% and sensitivity of 89%, and the p53 ELISA had a specificity of 100% and sensitivity of 93%. Cell-based ELISA can be developed to be Clinical Laboratory Improvement Act (CLIA)-compliant and the flexibility of the approach will allow adaptation of the assay to multiple tumor antigen systems.

Antibodies, Neoplasm↗

PubMed2002

Development of a particle agglutination assay system for detecting Japanese encephalitis virus-specific human IgM, using hydroxyapatite-coated nylon beads.

Japanese encephalitis virus-specific IgM is a reliable indicator for serodiagnosis of Japanese encephalitis. A particle agglutination (PA) assay system was developed to detect anti-Japanese encephalitis virus IgM in human serum samples. The newly developed PA assay consisted of hydroxyapatite-coated nylon beads and V-bottom 96-well microplates. Hydroxyapatite-coated nylon beads were coated with Japanese encephalitis virus antigens. Japanese encephalitis virus antigen-coated, hydroxyapatite-coated nylon beads agglutinated in the IgM-captured wells when anti-Japanese encephalitis virus IgM-positive serum samples were used. A button pattern was formed at the bottom of the wells when anti-Japanese encephalitis virus IgM-negative serum samples were used. Thirty anti-Japanese encephalitis virus IgM-positive serum samples from Japanese encephalitis-confirmed cases were tested by the PA assay. All these serum samples were determined to be Japanese encephalitis virus IgM-positive. IgM titers determined by the PA assay corresponded to those determined by enzyme-linked immunosorbent assay. The titers were consistent in two independent PA assays. These results indicate that the newly developed PA assay is a reliable method for detecting anti-Japanese encephalitis virus IgM in human serum samples and that this assay will be a suitable diagnostic system especially in rural areas of Asia.

Agglutination Tests↗

PubMed2006

Intact free prostate-specific antigen and free and total human glandular kallikrein 2. Elimination of assay interference by enzymatic digestion of antibodies to F(ab')2 fragments.

Various blood constituents can interfere with immunoassays, usually by binding the Fc portion of antibodies. Our previously developed assays for intact free prostate-specific antigen (PSA), free human kallikrein 2 (hK2), and total hK2 frequently yielded falsely high results despite including an excess of scavenger antibodies. We investigated whether this interference could be eliminated by replacing monoclonal capture or tracer antibodies with F(ab')2 or recombinant Fab fragments. Female heparin plasma samples (n = 1092), which should have negligible PSA and hK2, and male samples (n = 957) were analyzed to identify samples manifesting interference, which then were used to optimize protocols for the immunoassays. We compared original assays (monoclonal antibodies) versus optimized assays (F(ab')2 fragments: denatured mouse IgG added as scavenger) using another set of EDTA plasma (n = 113), heparin plasma (n = 160), and serum samples (n = 171). With the original assays, the frequency of falsely elevated hK2 and intact free PSA was 15 and 13%, respectively. The optimized assays eliminated 70-85% of these falsely elevated results and importantly reduced the magnitude in the remainder. F(ab')2 fragmentation was the most important factor in reducing interference. The optimized intact free PSA, free hK2, and total hK2 assays manifested high accuracy close to the lower limit of detection.

Animals↗

PubMed1990

[Development of ELISPOT assay for thyroid autoantibody-producing cells].

A new assay system for detection of thyroid-autoantibody-producing cells was developed. This assay is based on the ELISPOT method with antigen-coated nitrocellulose membranes in 96-well microfilter plates. This was more sensitive than conventional methods such as a radioimmunoassay and a passive agglutination method for detection of thyroid-autoantibody production. The coefficients of inter- and intra-assay variations for antibody-producing cells were less than 6.5%. Thus, this assay system can be used to analyse the thyroid-specific immunological abnormalities as a routine test.

Agglutination Tests↗