Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “quantification”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 883 records · Page 49Linked to original sources
PubMed1983

Quantification of human serum lipoprotein Lp(a): zone immunoelectrophoresis assay, a new sensitive method as compared to electroimmuno assay.

This study aimed at improving the immunological procedures for the quantification of human serum lipoprotein Lp(a). Lipoprotein Lp(a) was estimated by two immunoelectrophoretic methods: electroimmunoassay and zone immunoelectrophoresis assay. Whereas the electroimmunoassay gave curvilinear calibration lines (in peak height versus concentration plots) the zone immunoelectrophoresis assay revealed linearity in the same concentration range. The results obtained are in good agreement with each other (r = 0.975). The inter-assay coefficient of variation for the zone immunoelectrophoresis assay was 12% as determined by the use of a lyophilised reference serum. Zone immunoelectrophoresis assay is recommended for the routine quantification of lipoprotein Lp(a). Although the levels for total cholesterol (p less than 0.0025), HDL-cholesterol (p less than 0.001) and triglycerides (p less than 0.025) differed significantly between male (n = 24) and female (n = 22) individuals, no difference could be detected comparing the frequency distributions of Lp(a)-levels found for the male and the female group.

Adolescent↗
PubMed1984

Efficacy of latex agglutination and quantification methods for determination of C-reactive protein (CRP) in pediatric sera.

Described is a procedure for serum C-reactive protein (CRP) determination, consisting of a semiquantitative rapid CRP latex agglutination test, using dilutions of the serum, and the quantitating spot immunoprecipitate assay (SIA). These methods are performed with standard laboratory equipment using no more than 30 microliters of serum for both assays. With visual inspection, the SIA results are available one to two hours after blood sampling. CRP levels obtained by agglutination testing with five batches of latex reagents coated with rabbit anti-CRP agree well with the quantification, i.e. essentially 100% for the negative sera and about 80% for positive sera containing greater than 40 mg CRP/l. The remaining 20% of the samples are classified as low positive at 10 to 40 mg/l on agglutination. False positive or negative agglutination findings are below 2.3% with concordance at 88% between SIA and the CRP agglutination with rabbit antibodies. Two lots of CRP-latex reagents coated with sheep antibodies, however, gave 15.3% and 10.1% false positive findings and poor concordance with SIA ratings, particularly for low positive sera at only 20 and 29%. SIA is suggested for CRP quantification because it compares well with radial immunodiffusion in accuracy (less than 91%) and provides results in 2 h rather than 1-2 days. Rocket electroimmunoassay is less reliable with lower ratings than found in SIA, probably due to the electrophoretic heterogeneity of CRP. This is demonstrated for two of three purified CRP preparations, for which varying agglutination is seen. The combination of methods is especially recommended for diagnosis and monitoring of CRP in infectious processes in neonates and infants because of the required small sample volume--0.5 ml heel-prick blood--the rapidity of reliable (greater than 80%) reporting and the possibility of rating sera with moderate levels of CRP.

Animals↗
PubMed1993

Quantification of 3-methylglutaconic acid in urine, plasma, and amniotic fluid by isotope-dilution gas chromatography/mass spectrometry.

A method is described for quantification of the trace metabolite, 3-methylglutaconic acid, by isotope-dilution gas chromatography/mass spectrometry using synthetic 3-[2,4,6-13C3]methylglutaconic acid. Results are shown for quantification of 3-methylglutaconic acid in plasma, urine, cerebrospinal fluid and amniotic fluid for both normal controls and patients with different forms of 3-methylglutaconic aciduria. A simple method for the synthesis and purification of 3-[2,4,6-13C3]methylglutaconic acid is also described.

Adult↗
PubMed1994

An improved method for quantification of very long chain fatty acids in plasma.

Most peroxisomal disorders can be detected via analysis of very long chain fatty acids (VLCFA) and phytanic acid in plasma or serum. Previous methods utilizing gas-liquid chromatography (GLC) alone are time consuming and are hampered by interference from cholesterol derivatives. We describe here a GLC-mass spectrometry method for the simultaneous quantification of VLCFAs and phytanic acid. The method employs single ion monitoring with deuterated internal standards. We studied 38 normal controls and 12 patients with peroxisomal diseases and found complete discrimination between the two groups. Comparison with other methodology is discussed. We believe this to be a practical and accurate method for the quantification of both VLCFAs and phytanic acid in serum or plasma. It should be useful for laboratories involved in the diagnosis of biochemical disorders.

Adrenoleukodystrophy↗
PubMed1989

24 hour continuous tremor quantification based on EMG recording.

A new method is described that allows continuous quantification of parkinsonian and essential tremor over a period of up to 24 h on the basis of surface EMG recording from antagonistic forearm muscles. Tremor extraction from EMG data and all other calculations are performed on a digital computer. The occurrence, intensity and frequency of tremor are calculated. The data evaluation is fully automatic, including quality control and elimination of artifacts. Since tremor changes considerably over a 24 h period, long-term quantification gives more reliable data to study diurnal variations and to control the effects of medical treatment on tremor. As an additional advantage tremor recording is not restricted to a laboratory environment. Tremor can be monitored under everyday conditions and in the presence of moderate voluntary EMG activity.

Electromyography↗
PubMed1990

Trypanosoma cruzi: quantification in tissues of experimentally infected mice by limiting dilution analysis.

A limiting dilution assay (LDA) was developed for the quantification of Trypanosoma cruzi in the heart and blood of infected mice. Three groups of swiss mice were injected ip with "CL", "Colombiana," and "Y" strains. At 1-day intervals after infection, blood and the heart were removed. Serial blood dilutions in LIT medium were performed and distributed in four groups of 24 microplate wells. The growth of parasite was visually checked in an inverted microscope. It was found that curves of parasitemia obtained by parasite counting in a hemocytometer or estimated by LDA were similar. A similar method was used to quantify parasites in the heart of mice. The heart was cut, washed, dried, and its weight was determined. The heart pieces were disrupted by passage through a mesh stainless-steel screen into LIT. Serial dilutions of the heart homogenate were made in LIT and added to at least 24 replicate microplate wells. Parasites were detectable earlier in the heart of mouse infected with Y strain when compared to CL and Colombiana strains. Parasites were detected in the heart of mice of all strains by 6 days after infection. This LDA for quantification of T. cruzi permits a more precise evaluation of the number of living parasites in infected tissues.

Animals↗
PubMed1991

Quantification of enzyme activities in brain sections by microphotometry.

1. Catalytic enzyme histochemistry offers the possibility to demonstrate enzyme activities quantitatively (microphotometry) in brain sections of those sites where they are localized. 2. A prerequisite for quantification are appropriate histochemical procedures for the demonstration of enzymes, which are shortly discussed. 3. For the microphotometric determination of enzymes in brain sections the scanning microphotometry is at present the technique of choice. 4. This is described in the example of an image plane scanning system. 5. Using this technique two measuring procedures can be applied for the quantification of enzyme activities, i.e. kinetic and end-point measurements. 6. Methods for the microphotometric determination of certain important oxido-reductases and further enzymes are presented. 7. It is concluded that quantitative catalytic enzyme histochemistry could be a source of results complementary to those provided by conventional biochemistry.

Animals↗
PubMed1993

Rapid, sensitive high-performance liquid chromatographic method for the quantification of promethazine in human serum with electrochemical detection.

A method of analysis has been developed to quantify promethazine in human serum with a sensitivity that was suitable for bioavailability studies following a 50.0-mg rectal dose. The limit of quantification from 1.0 ml of serum for promethazine using electrochemical detection was 0.200 ng/ml. At this concentration, the total coefficient of variation obtained from seven replicates over the course of three days of validation was 7.53%. The amount of serum required, the ease of sample preparation and the precision of the method at the limit of quantification demonstrated an improvement over previous assays. A validation study was completed that included an evaluation of recovery, ruggedness, linearity of response, accuracy, precision, sensitivity, stability and selectivity. The method was then used to determine promethazine serum levels in a 36-subject bioavailability study following a 50.0-mg suppository dose.

Chromatography, High Pressure Liquid↗
PubMed1989

Vectorcardiographic bites. A method for detection and quantification applied on a normal material.

Vectorcardiographic bites as an expression of small fibrotic or necrotic areas in the myocardium have been discussed for many years. Distinct definitions of bites and normal limits for bites have, however, not been established. Therefore, an algorithm for computer detection and quantification of bites is presented. To find a bite, sectors of the QRS loop rotating opposite the way of the main part of the loop (eg, a clockwise-rotating sector in an otherwise counterclockwise-rotated loop) are detected. The bite is then delineated, using an iterative procedure. Finally the amplitude, duration, and area of the bite are calculated. The method for detection and quantification was applied on a well-defined normal material to obtain normal limits for bites. The commonly used criterion for an abnormal bite (amplitude greater than or equal to 0.1 mV and duration greater than or equal to 10 msec in the horizontal or sagittal plane) results in a specificity of only 87%. A specificity of 95% is yielded with the criterion of bite amplitude greater than 0.15 mV in the horizontal or sagittal plane.

Adult↗
PubMed1983

Quantification of human immunoglobulins by semiautomatic polyethylene glycol precipitation radioimmunoassays. Estimation of circulating immune complexes and immunoglobulin synthesized in vitro.

Simple, reliable semiautomatic radioimmunoassays have been developed for the measurement of human immunoglobulins (IgG, IgA, IgM, IgK and Ig lambda). The assays are based on the separation of free from antibody-bound radiolabelled fragments of immunoglobulin by precipitation with 13% polyethylene glycol. The precipitate is harvested and washed on glass fibre filters by means of a commercial cell harvester. Radiolabelled lambda chain from Bence Jones urine was used for lambda chain assay and Fab' gamma from pooled IgG for the kappa assay. Labelled Fab or Fc fragments of IgG, IgA and IgM were used for the class specific assays. Selected commercial antisera were used throughout. The sensitivity limits of the assays performed according to the standard procedure were about 20 ng Ig per ml. The assays have been used for the quantification of circulating immune complexes and both cellular and secreted immunoglobulin produced in cell cultures. The results demonstrate the importance of the simultaneous quantification by L chain and H chain specific assays.

Animals↗
PubMed1985

Quantification of lymphocyte activation by measurement of DNA polymerase alpha activity.

Measurement of the activity of the enzyme DNA polymerase alpha has been investigated with regard to its potential usefulness as a method for the detection and quantification of lymphocyte activation in vivo. A modified enzyme assay was developed in order to optimise measurement of activity in crude homogenates of cells or tissues, thus allowing the convenient handling of multiple samples. Specificity of the assay for polymerase alpha was ensured by the inclusion in the assay mixture of dideoxythymidine triphosphate, an inhibitor of the other eukaryotic DNA polymerases. The activity of DNA polymerase alpha was found to be closely correlated with [3H]thymidine incorporation in a mitogen-stimulated in vitro system. The usefulness of the polymerase alpha method for the quantification of lymphocyte activation was validated in 3 different in vivo systems of either immune-mediated or drug-induced lymphoid cell response.

Animals↗
PubMed1987

A unique epitope exposed in native complement component C9 and hidden in the terminal SC5b-9 complex enables selective detection and quantification of non-activated C9.

Recently, monoclonal antibodies recognizing epitopes exposed in activation products of complement but hidden in the native components have been characterized and used for selective quantification of the activated protein. We now demonstrate that an epitope in the native component C9 is hidden in the terminal SC5b-9 complex. A monoclonal antibody against this epitope enabled selective detection of C9 without influence of the amount of SC5b-9 present. This antibody recognizing native soluble C9 was used to construct a quantitative double-antibody ELISA with unique sensitivity and specificity. Combination of this assay with an assay previously described for selective quantification of the SC5b-9 complex provides an important tool for evaluating terminal pathway activation of complement.

Animals↗
PubMed1989

An ELISA method for the quantification of anti-streptolysin-O antibodies.

This paper describes a new assay, based on the ELISA technique, for the quantification of antibodies to streptolysin-O (ASLO). We have compared its performances with that of a standard method (inhibition of hemolysis). Using a panel of 137 sera covering the whole range of ASLO titers, the results showed a good correlation between both methods but the ELISA method was more reproducible than the standard technique, thus represents a convenient alternative for the quantification of ASLO.

Antibodies, Bacterial↗
PubMed1989

Quantification of IgG and IgG4 antibodies to bee venom phospholipase A2 by competitive inhibition in ELISA.

Phospholipase A2 (PLA) is the major antigen of bee venom. Individuals often stung by bees, such as bee keepers, show a restricted immune response mainly of anti-PLA IgG4 antibodies. In contrast, patients allergic to bee venom produce high levels of PLA-specific IgE. This isotype restriction, the clinical relevance and the well defined structure of the PLA antigen, provide a useful model for the study of the principles regulating isotype expression in the human antibody response. A fundamental requirement for such studies is the availability of quantitative and sensitive assays to measure PLA-specific antibodies. Here we describe an ELISA method for direct isotype-specific quantification of anti-PLA IgG and IgG4 antibodies. Serum containing anti-PLA IgG antibodies was added at a predetermined dilution to PLA coated microtiter plates. Then mouse monoclonal antibodies to human IgG or IgG4 and different concentrations of purified human IgG and IgG4, respectively, were added simultaneously. The concentration of anti-PLA IgG and IgG4 antibodies in the serum was calculated from the resulting inhibition curve. Additionally, an analytical method to compare unknown antibody samples with a standard in ELISA - avoiding problems of different affinities - is described. Using the technique described here, isotype-specific quantification of anti-PLA antibodies can be performed at a sensitivity of approximately 70 pg/ml with a reproducibility range of 10-15%.

Adult↗
PubMed1990

Quantification of radiolabelled granulocyte migration in vivo.

Quantification of the tissue localisation of granulocytes is difficult, particularly in man. With the aim of facilitating such quantification, a technique is described which combines the micropore filter skin window technique with the infusion of autologous 111In-labelled granulocytes. The radioactivity in the removable micropore filters, placed on small forearm skin window abrasions, was compared with peripheral blood radioactivity following injection of 111In-labelled 'pure' granulocytes in normal subjects. Radioactivity in filters from abrasions which were made 8 h or more before injection of labelled cells followed the same time course as the cell-associated radioactivity in whole blood, but radioactivity in filters from abrasions made nearer to the time of labelled granulocyte injection increased to reach a peak 3-8 h after cell injection, at a time when cell-associated blood radioactivity had fallen to about 50% of its initial value. Exercise appeared to induce a transient decrease in radiolabelled granulocyte migration into the filters. This technique offers a means of studying the kinetics of granulocyte migration in vivo.

Cell Movement↗
PubMed1991

Identification and quantification of human peripheral blood lymphocytes and monocytes following migration into nitrocellulose filters.

Previously, in order to evaluate the migration of specific types of lymphocytes (e.g., T or B cells, CD4 or CD8 subsets) using the Boyden chamber technique, the relevant cell populations have first been purified. We report here a method which permits identification of the lymphocytes following migration into the nitrocellulose filters. After fixation, the filters are exposed to specific anti-lymphocyte monoclonal antibodies and the reaction is visualized via a second gold-linked antibody. Monocyte-depleted lymphocytes isolated from human peripheral blood are routinely used for migration but mixed mononuclear cell preparations can also be used. This was shown by comparing lymphocyte migration in monocyte-containing and monocyte-depleted cell suspensions isolated from the same donor. The presence of monocytes did not influence the migration of normal resting T lymphocytes. With human peripheral blood as starting material the method is most suitable for the evaluation of T cell migration since, in most instances, T cells are the predominant lymphocyte population. When the B cell count is normal (5-10% total lymphocytes), quantification of B cell migration requires enrichment but not complete purification of this population. Migrating monocytes can also be identified. However, the antibody staining is less intense on the spread monocytes and, therefore, quantification must be performed by eye rather than with the Optomax image analyser.

Cell Movement↗
PubMed1993

Rapid fluorometric quantification of monocyte attachment in tissue culture wells.

A simple fluorometric assay that permits rapid quantification of attachment of monocytes or macrophages in tissue culture wells is described. Using 4,6-diamidino-2-phenylindole (DAPI) as a specific fluorochrome marker for DNA, we observed a dose-dependent increase with strong linear correlation in fluorescent emission over a broad range of DNA concentrations. Measurements of the DNA content of the human monocytic cell line THP-1 demonstrated a linear correlation between fluorescence intensity and cell number from 5 x 10(4) to 1 x 10(6) cells, with an estimated average DNA content of 7.5 pg DNA per cell. While untreated THP-1 cells were not detectably adherent, PMA induction for 24 h results in 57-76% adherence to plastic surface. This method was found to be useful for measuring the number of peripheral blood monocytes separated from lymphocytes by attachment. 16 subjects were sampled and the standard deviation of each individual did not exceed 10%. The number of attached cells was between 10-16% of the total mononuclear cells. Fluorescence measurement of DNA with DAPI permits rapid and accurate determination of cell numbers and appears useful in the quantification of adherent populations such as myelocytic cells and cell lines.

Cell Adhesion↗
PubMed1994

An ultrasensitive chemiluminoenzyme immunoassay for the quantification of human tissue kininogens: application to synovial membrane and cartilage.

A sandwich enzyme immunoassay using a chemiluminescent detection has been developed for the quantification of total human (high and low molecular weight) kininogens in tissue extracts. This assay uses monospecific polyclonal IgG labelled with alkaline phosphatase and the commercially available dioxetane derivatives as substrates, for the detection of immune complexes. This method exhibits a sensitivity level of 1 fmol/ml and allows a precise quantification of total kininogens in synovium and cartilage extracts. When characterized by Western blot, the immunoreactive material reveals the presence of both high and low molecular weight kininogens.

Aged↗