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At least 1,531 records · Page 85Linked to original sources
PubMed1977

Titration of herpes simplex virus antibodies in human sera by the enzyme-linked immunosorbent assay (ELISA).

100 sera from healthy adults were titrated simultaneously for herpes simplex virus (HSV) antibodies by ELISA and neutralization. The ELISA was performed on microtitre plates where approximately 100 ng of detergent solubilized and chromatographically purified HSV glycoproteins was bound covalently to the plastic bottom of each well. The optical density (OD) values obtained by the use of the peroxidase-1.2phenylendiamindihydrochloride system showed good correlation with the neuratlizing antibody titres. Sera with very low neutralizing titres were clearly positive in ELISA.

Adult↗
PubMed1995

Carprofen as an analgesic for postoperative pain in cats: dose titration and assessment of efficacy in comparison to pethidine hydrochloride.

The aim of this study was to titrate the optimal dose of carprofen for single dose usage, for alleviating postoperative pain, under a double-blind and randomised protocol, using both negative and positive controls. Renal tolerance was assessed by screening plasma urea and creatinine. Pre- and postoperative assessment of pain and sedation was made using a dynamic and interactive visual analogue scoring system in 60 cats undergoing ovariohysterectomy. The cats were randomly assigned to one of six groups: (1) carprofen at 1.0 mg/kg subcutaneously (sc); (2) carprofen at 2.0 mg/kg sc; (3) carprofen at 4.0 mg/kg sc; (4) pethidine at 5.0 mg/kg intramuscularly (im), (5) pethidine at 10.0 mg/kg im: and (6) no analgesics (injection of saline). All injections were given postoperatively on tracheal extubation and administered in a double-blind manner. Assessments were made up to 20 hours post extubation. Prior to induction and at 20 hours post extubation, blood samples were taken for laboratory analysis of the urea and creatinine content to check for any adverse effect on renal function. Cats given pethidine did not appear more sedated than the groups receiving carprofen or saline. Cats receiving carprofen were in less pain postoperatively overall, with 4.0 mg/kg being the most effective dose rate (significantly better than the other doses of carprofen at four and eight hours post extubation). The highest dose of pethidine provided significantly better analgesia than the highest dose of carprofen up to two hours post extubation, but from two to 20 hours post extubation carprofen at 4.0 mg/kg provided significantly better analgesia than the pethidine. None of the analgesic regimens appeared to affect renal function adversely, as measured by urea and creatinine levels.

Analgesics↗
PubMed1997

Effects of substitutions D73E, D73N, D103N and V106M on signaling and pH titration of sensory rhodopsin II.

Several mutations in the repellent phototaxis receptor sensory rhodopsin II (SRII), in residues homologous to residues important in the related proton pump bacteriorhodopsin, were expressed in Pho81Wr-, a Halobacterium salinarum strain deficient in production of SRII and its transducer protein HtrII. The lack of production of SRII and HtrII is shown to be due to insertion of an ISH2 transposon into the promoter region upstream of the htrII-sopII gene pair. Near wild-type phototaxis responses are rescued in Pho81Wr- by expression of HtrII with D73E, D103N or V106M receptors. Partial responses are restored by the HtrII-D73N pair. From absorption spectroscopy of his-tag-purified receptor protein from mutants D73N and D73E we conclude that Asp73 is the primary counterion to the protonated Schiff base in SRII, like the corresponding Asp85 in bacteriorhodopsin. The absorption maximum of SRII (487 nm) is shifted to 514 nm in mutant D73N, a 1080 cm-1 shift identical to that caused by D85N in bacteriorhodopsin. Acid titration of SRII also induces the red shift with a pK of 3.0 in wild type. The absorption shift and the pK are nearly the same in V106M and D103N, but the pK is raised to 5.1 in D73E, confirming that Asp73 is the residue responsible for this spectral transition.

Archaeal Proteins↗
PubMed1959

Titration of the protein paramyosin.

The titration curve of an aqueous solution of crystalline paramyosin shows a unique buffering zone which can be attributed to a shift in the pK of its glutamic acid residues. A possible explanation of this phenomenon on the basis of the presence of polyanionic segments in the molecule is discussed.

Muscle Proteins↗
PubMed1960

Effects of temperature and anions on titration curves of frog muscle.

Titration curves of frog muscle at 2 degrees C and 25 degrees C were determined in vivo. Lowered temperature decreases respiration without change of colloidal charge or of ion distribution as estimated from charge. Anions which are inhibitors or metabolites combine with muscle colloids, changing the distribution of other ainions and cations.

Animals↗
PubMed1971

Dye uptake assay: an efficient and sensitive method for human interferon titration.

Currently, human interferon (IF) assays are generally performed by plaque reduction or visual cytopathic effect methods. Both are time-consuming, subjective in interpretation, and, in the case of the latter, relatively insensitive. An adaption of the dye uptake method for human IF titration which uses foreskin-derived fibroblasts and vesicular stomatitis virus is described. This assay is reproducible and sensitive (1 unit = 3 international units). By direct comparison, however, it is somewhat less sensitive than the plaque reduction assay (1 unit = 1.1 international units). This assay is especially recommended for use in needed clinical investigations of human IF because of its technical simplicity, allowing efficient handling of large numbers of specimens.

Cell Count↗
PubMed1973

Microtissue culture test for the titration of low concentrations of diphtheria antitoxin in minimal amounts of human sera.

A microtissue culture method for the assay of low concentrations of diphtheria antitoxin in human sera has been developed, using a monkey kidney cell (VERO) culture technique. Results obtained with sera from nonvaccinated children and with immune sera from children vaccinated with three and four injections of diphtheria pertussis tetanus vaccine were in agreement with antitoxin levels considered necessary to denote immunity to diphtheria. The use of microplates and organic buffer for culturing the animal cells improved the stability of the tissue culture system. The described method is sensitive, economical, and applicable for the titration of antitoxin in human sera particularly from infants and children from whom a minimum amount of serum is available.

Animals↗
PubMed2002

Performance characteristics of the PolyTiter Immunofluorescent Titration system for determination of antinuclear antibody endpoint dilution.

Conventional screening for circulating antinuclear antibodies (ANA) is generally performed by immunofluorescent (IF) microscopy with a 1:40 dilution of serum. Intensity of IF staining is then semiquantitated by using twofold serial dilutions, where the highest dilution in which staining intensity equals the endpoint control is expressed as an endpoint titer. The PolyTiter Immunofluorescent Titration system (Polymedco, Inc.) facilitates ANA-IF assay (IFA) testing by relating the intensity of IF staining to reference calibrators (defined in PolyTiter units), providing an endpoint titer directly from a 1:40 dilution. This study was conducted to assess the performance characteristics of the PolyTiter system. Two technologists each evaluated 10 replicates of three specimens and two controls on five sequential days. Endpoint dilution agreement (defined as +/-2 dilutions) with the reference was 100% for all controls and for all specimens by one technologist. The second reader reported agreement of 98, 88, and 100% for the low, medium, and high specimens, respectively. Analysis of PolyTiter unit values yielded between-reader, between-run, and within-run precision coefficients of variation of less than 10%. The variance component in the lot-to-lot analysis was zero, indicating all of the variation was due to run-to-run differences. Overall endpoint dilution agreement between PolyTiter and serial dilution in the evaluation of 125 specimens at three sites was 90, 93, and 86%. Pattern identification with the PolyTiter was similar to that with serial dilution. The PolyTiter system demonstrates acceptable performance for routine ANA-IFA testing in the clinical laboratory.

Antibodies, Antinuclear↗
PubMed2005

Antibiotic-free plasmid stabilization by operator-repressor titration for vaccine delivery by using live Salmonella enterica Serovar typhimurium.

Live, attenuated bacteria are effective vectors for heterologous antigen delivery. However, loss of heterologous gene-bearing plasmids is problematic, and antibiotics and their resistance genes are not desirable for in vivo DNA vaccine delivery due to biosafety and regulatory concerns. To solve this problem, we engineered the first vaccine delivery strain that has no requirement for antibiotics or other selectable marker genes to maintain the recombinant plasmid. This model strain of Salmonella enterica serovar Typhimurium, SLDAPD, uses operator-repressor titration (ORT) technology, which requires only the short, nonexpressed lacO sequence for selection and maintenance. SLDAPD, recovered from the spleens and Peyer's patches of mice following oral inoculation, was shown to maintain a plasmid that, in contrast, was lost from parental strain SL3261. We also demonstrated successful application of this technology to vaccine development, since SLDAPD carrying a plasmid without an antibiotic resistance gene that expressed the Yersinia pestis F1 antigen was as efficacious in protecting vaccinated mice against plague as the parental SL3261 strain carrying an antibiotic-selected version of this plasmid. Protection of mice against plague by immunization with Salmonella expressing F1 has previously required two or more doses; here we demonstrated for the first time protective immunity after a single oral immunization. This technology can easily be used to convert any suitable attenuated strain to an antibiotic-free ORT strain for recombinant protein vaccine delivery in humans.

Animals↗
PubMed1984

Regulation of the F-factor pif operon: pifO, a site required in cis for autoregulation, titrates the pifC product in trans.

F factor pifC, pifA, and pifB gene expression is subject to negative regulation by the product of the pifC locus (J.F. Miller and M. H. Malamy, J. Bacteriol. 156:338-347, 1983). In this paper, we describe the properties of a new regulatory site in the pif region, pifO, which is required in cis for autoregulation of pif gene expression. Spontaneous pifO mutations were isolated that allow expression of a pifC-lacZ protein fusion in the presence of pifC product in trans. Recombination of these pifO mutations onto F'lac results in increased pifA and pifB activity. Thus, a single regulatory element, pifO, regulates pifC, pifA, and pifB expression in cis. The presence of multiple copies of a fragment from the pif region carrying wild-type pifO sequences (F coordinates 42.9 to 42.43 kilobases) in trans to F'lac results in an increase in pifA and pifB activity as measured by inhibition of T7 plating. When the pifO mutations are recombined onto a plasmid carrying pifO, the resulting recombinants are greatly decreased in the ability to increase F'lac pif expression. These results suggest that increased F'lac pifA and pifB expression caused by pifO sequences in trans is a consequence of titration of pifC product and derepression of the pif operon.

Base Sequence↗
PubMed1986

Comparison of methods for isolation and titration of Crimean-Congo hemorrhagic fever virus.

The fluorescence focus assay and the plaque assay in CER cells were compared with mouse inoculation for the isolation and titration of Crimean-Congo hemorrhagic fever virus. The fluorescence focus assay and the plaque assay were of similar sensitivity, but both produced 10- to 100-fold lower titers than did mouse inoculation. For specimens from 26 Crimean-Congo hemorrhagic fever patients in South Africa, virus was isolated from 20 by mouse inoculation and from only 11 by cell culturing. Although cell cultures were less sensitive for the isolation of virus from clinical specimens, they produced diagnostic results much more rapidly.

Animals↗
PubMed1991

Development of simian immunodeficiency virus isolation, titration, and neutralization assays which use whole blood from rhesus monkeys and an antigen capture enzyme-linked immunosorbent assay.

Assays that use rhesus macaque whole blood and an antigen capture enzyme-linked immunosorbent assay for the simian immunodeficiency virus (SIV) p27 core protein were developed for the isolation of SIV from the blood of infected animals, the titration of infectivity of SIV inocula, and the quantitation of virus neutralizing antibodies in serum. These assays required small amounts of whole blood, were adaptable to a microtiter format, and used substrates mainly of rhesus macaque origin.

Animals↗
PubMed1976

Titration of Newcastle disease virus and its neutralizing antibodies in microplates by a modified hemadsorption and hemadsorption inhibition method.

Using the microtiter system, titration of Newcastle disease virus infectivity and neutralizing antibodies was carried out in chicken embryo fibroblasts grown in "U" or flat-bottomed plates. Infectivity was detected by a combined hemadsorption-hemagglutination method. Inhibition of that reaction indicated the presence of neutralizing antibodies. A 24-h microneutralization test was developed and compared to the plaque neutralization and microhemagglutination inhibition test. Reproducibility of the microneutralization test was statistically analyzed.

Animals↗
PubMed1993

Monoclonal antibody-based blocking enzyme-linked immunosorbent assay for specific detection and titration of peste-des-petits-ruminants virus antibody in caprine and ovine sera.

A blocking enzyme-linked immunosorbent assay (B-ELISA), using two neutralizing monoclonal antibodies (MAbs), was established and compared with the virus neutralization test (VNT) for detecting specific peste-des-petits-ruminants virus (PPRV) antibody in caprine and ovine sera. This technique was developed because VNT, the only available specific serological test for PPRV and the cross-reactive rinderpest virus (RPV), is time-consuming and unaffordable for most laboratories in regions where both peste des petits ruminants and rinderpest occur. The test depends on the blocking of the binding of the MAb to a specific epitope in the presence of positive serum. Test conditions were optimized by using peste-des-petits-ruminants and rinderpest sera that were known to be VNT positive and negative. A blocking format, in which serum is preincubated with a solid-phase PPRV antigen and then incubated with the MAb, yielded levels of sensitivity and specificity superior to those of a competitive format, in which the two reagents are added simultaneously. A threshold value of 45% inhibition, representing the mean for a negative population (n = 277) plus 2.7 standard deviations, was adopted for routine screening. A total of 605 serum samples were screened by B-ELISA and the VNT. The sensitivity and specificity of B-ELISA relative to the VNT were 90.4 and 98.9%, respectively. Of 264 field serum samples tested, 11 (4.2%) could not be assayed by the VNT because of contamination or cytotoxicity; the overall agreement quotient between results of the two tests (n = 253) was 0.91. A high correlation (r>/=0.98) was observed between B-ELISA and the VNT for endpoint titration of sera (n=57). Because B-ELISA proved to be nearlyas sensitive and specific as the VNT while being simpler and more rapid, it would be an adequate substitute for the VNT for assessing herd immune status and for epidemiologic surveillance.

Animals↗
PubMed1995

Simple enzyme immunoassay for titration of antibodies to the CD4-binding site of human immunodeficiency virus type 1 gp120.

We report the development of an immunoassay for the titration of antibody to the CD4-binding site (CD4BS) of the human immunodeficiency virus type 1 (HIV-1) surface glycoprotein gp120. This assay is a competitive enzyme-linked immunosorbent assay in which serum antibodies compete with labeled F105, a human monoclonal antibody whose corresponding epitope overlaps the conformation-dependent CD4BS, for binding to purified recombinant gp120 coated on a solid phase. Ninety-nine percent (109 of 110) of HIV-1-positive French patients and 91% (51 of 56) of HIV-1-positive African patients had CD4BS antibodies, indicating that the conformational CD4BS epitope is well conserved among different subtypes of HIV-1. Titers of CD4BS antibodies according to clinical status appeared to be not statistically different. A longitudinal study in 21 seroconverters showed that, for the majority of individuals, CD4BS antibodies appeared early and persisted at relatively high titers for several years. None of 21 HIV-2-seropositive patients had CD4BS antibodies in our assay, suggesting that the antibodies produced during HIV-2 infection are not cross-reactive with the CD4BS of HIV-1 gp120.

Amino Acid Sequence↗