Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Biological samples”

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 199 records · Page 11Linked to original sources
PubMed2004

Identification of optimal classification functions for biological sample and state discrimination from metabolic profiling data.

MOTIVATIONS: Classification of biological samples for diagnostic purposes is a difficult task because of the many decisions involved on the number, type and functional manipulations of the input variables. This study presents a generally applicable strategy for systematic formulation of optimal diagnostic indexes. To this end, we develop a novel set of computational tools by integrating regression optimization, stepwise variable selection and cross-validation algorithms. RESULTS: The proposed discrimination methodology was applied to plasma and tissue (liver) metabolic profiling data describing the time progression of liver dysfunction in a rat model of acute hepatic failure generated by d-galactosamine (GalN) injection. From the plasma data, our methodology identified seven (out of a total of 23) metabolites, and the corresponding transform functions, as the best inputs to the optimal diagnostic index. This index showed better time resolution and increased noise robustness compared with an existing metabolic index, Fischer's BCAA/AAA molar ratio, as well as indexes generated using other commonly used discriminant analysis tools. Comparison of plasma and liver indexes found two consensus metabolites, lactate and glucose, which implicate glycolysis and/or gluconeogenesis in mediating the metabolic effects of GalN.

Algorithms↗
PubMed1997

Automated on-line sample pretreatment system for the determination of trace metals in biological samples by inductively coupled plasma mass spectrometry.

A fully automated on-line sample pretreatment system combining microwave digestion with sample preconcentration/matrix separation for the determination of trace metals (Fe, Ni, Cu, Zn, and Pb) in blood and serum samples by inductively coupled plasma mass spectrometry (ICPMS) was designed and evaluated. The samples were mixed with an appropriate reagent and digested in a flow-through, focused microwave-heated oven. After digestion, the sample solution was transferred on-line to a column packed with iminodiacetate-based resin for separation of matrix elements like Na, K, Ca, Mg, Cl, P, and S that might interfere with the measurement by ICPMS. The analytes chelated on the resin were subsequently eluted and led to ICPMS for multielement determination. The whole sample pretreatment process was automatically controlled by a self-designed expert system. The analytical reliability of data from this on-line system was confirmed to be good with the analysis of SRM samples (Seronorm Whole Blood and NIST SRM 1598 Bovine Serum), and the limits of detection (3 sigma) for Fe, Ni, Cu, Zn, and Pb were 68, 0.34, 3.5, 13.4, and 0.22 microgram/L, respectively. With this fully automated on-line system, the determination of analytes in biological fluid samples down to micrograms-per-liter levels has been proven to be feasible, and the sample throughput can achieve up to 6 samples/h.

Animals↗
PubMed2002

Simultaneous analysis for multiple heavy metals in contaminated biological samples.

In the present study, the conditions of analysis by inductively coupled plasma-atomic emission spectrometry (ICP-AES) were investigated. Twenty-six elements (Mg: 25 ppm; Sc: 10 ppm; Ti: 50 ppm; others: 100 ppm) were used as the elements interfering with selected 24 wavelengths. Consequently, the background values in 19 elements were subjected to some influences. However, all of these effects disappeared at low concentrations--less than 1 ppm of interfering elements. Next, the values from the ordinary calibration method were compared with those from the standard addition method using several biological samples. There was a discrepancy in the results obtained from both methods because of the sample, and three patterns were observed. However, no discrepancy was observed in the values for the standard reference materials using both methods. There was no significant difference between the certified values of the standard reference materials and the obtained ones by ICP. Therefore, the analytical wavelengths and the methods in the present study were suggested to be useful for ICP-AES analysis for environmental and/or biological samples.

Calibration↗
PubMed2002

Analysis of glycosaminoglycan-derived disaccharides in biologic samples by capillary electrophoresis and protocol for sequencing glycosaminoglycans.

Glycosaminoglycans are biologically significant carbohydrates which either as free chains (hyaluronan) or constituents of proteoglycans (chondroitin/dermatan sulfates, heparin, heparan sulfate and keratan sulfate) participate and regulate several cellular events and (patho)physiological processes. Capillary electrophoresis, due to its high resolving power and sensitivity, has been successfully used for the analysis of glycosaminoglycans. Determination of compositional characteristics, such as disaccharide sulfation pattern, is a useful prerequisite for elucidating the interactions of glycosaminoglycans with matrix effective molecules and, therefore, essential in understanding the biological functions of proteoglycans. The interest in the field of characterization of such biologically important carbohydrates is soaring and advances in this field will signal a new revolution in the area of glycomics equivalent to that of genomics and proteomics. This review focuses on the capillary electrophoresis methods used to determine the disaccharide pattern of glycosaminoglycans in various biologic samples as well as advances in the sequence analysis of glycosaminoglycans using both chromatographic and electrophoretic techniques.

Carbohydrate Sequence↗
PubMed1976

A rapid, enzymatic assay for measurement of inorganic pyrophosphate in biological samples.

An enzymatic assay for measurement of inorganic pyrophosphate (PPi) in biological samples is described using the UDPG pyrophosphorylase reaction and coupling it with three other enzymes in a system of phosphorylation and double reduction to form NADPH, which is measured fluorometrically. The method is specific for PPi in the presence of inorganic orthophosphate and can be used on small volumes of deproteinized ultrafiltrates of fluids or cell extracts. The assay was used here to determine the concentration of PPi in human plasma and serum, and the intracellular content of PPi in human skin fibroblasts, chondrocytes, and red blood cells. The mean PPi concentration of plasma was found to be 2.72 +/- 0.14 muM (mumo/l +/- S.E.M.); for serum it was 6.09 +/- 0.36 muM. The range (95% confidence limits) was 2.14-3.30 muM for plasma and 4.62-7.51 muM for serum. The average intracellular PPi content (pmoles PPi per 10(6) cells +/- S.E.M.) was as follows: (a) skin fibroblasts, 332 +/- 66; (b) articular chondrocytes, 655 +/- 46; red blood cells, 1.74 +/- 0.28.

Animals↗
PubMed1984

An enzyme specific method for estimation of pyruvic acid radioactivity in biological samples.

A method for the estimation of pyruvate radioactivity in complex biological samples is presented. After perchloric acid deproteinization, the samples were divided in two aliquots. All pyruvate was removed from the first aliquot with lactate dehydrogenase and NADH; the other was left undisturbed. Then all hydrophilic components of the sample were removed through an Amberlite XAD-7 column. The samples were treated with dinitrophenylhydrazine to obtain the corresponding hydrazones, which were retained in an Amberlite XAD-7 column and then were eluted with acetone and their radioactivity counted. The difference between both aliquots corresponded to the pyruvate radioactivity in the sample. No contamination by lactate, glycerol, glucose or amino acids was observed. The mean recovery of 5 determinations of pyruvate radioactivity was 91.3% +/- 1.0.

Acrylic Resins↗
PubMed2001

Determination of 226Ra in biological samples by adsorption on specific adsorbers.

The determination of 226Ra in biological samples, such as milk and grass, was studied. 226Ra analysis of cow's milk was studied starting from de-fatted milk. The proteins were eliminated by coagulation of the colloidal phase with trichloroacetic acid. Phosphorus was then removed by precipitating it as molybdophosphate and finally adsorption was carried out by using two different adsorbers in order to concentrate and purify radium. Lead rhodizonate (LEHRO) adsorbed on charcoal and partially reduced tin dioxide (PRTD) were utilised. A method for the determination of 226Ra in grass ashes was also investigated. The main interference, due to magnesium, hinders the use of LERHO, so the proposed procedure is based on adsorption of radium on PRTD at pH 9.5. The magnesium concentration was depleted by precipitating barium (carrier) and radium with calcium carbonate at pH 8 before the adsorption step. The high phosphorus concentration in grass also interferes in the determination of 226Ra; phosphorus was eliminated as above via molybdophosphate precipitation. The radium was carried by barium and spiked with 133Ba. The yield of the chemical procedure was evaluated on the basis of 133Ba activity. Radium samples were alpha-counted and the activity was evaluated with a suitable calibration curve. Both exchangers in the milk analysis and PRTD in grass analysis were shown to be helpful in order to set up an easily performed procedure, which allows many samples to be processed simultaneously. All the methods adopted were shown to be very sensitive. Under the experimental conditions used, with 1 L of milk or 5 g of grass ashes, the limit was about 3 mBq 226Ra L-1 milk and < 1 mBq 226Ra g-1 grass ashes.

Adsorption↗
PubMed1992

The quantification of fluorescent emission from biological samples using analysis of polarization.

The quantification of fluorescent emission from biological specimens can only be carried out in cellular regions where the relationship between fluorophore concentration and fluorescent emission is linear. Using a confocal scanning laser microscope, we show that quantification of fluorescent emission from biological samples labelled with fluorescein and fluorescein analogues mounted in a viscous medium can be readily achieved. Where the distribution of fluorophore is highly localized, for example in cells labelled for immunofluorescence analysis, we demonstrate that analysis of fluorescence depolarization can identify regions in which fluorophore concentration exceeds the range in which the relationship to fluorescent emission is linear. We also demonstrate that, under the conditions examined, depth-dependent effects, fading and quenching are either small enough to be ignored or can be corrected for mathematically when quantifying fluorescent emission.

Animals↗
PubMed1976

Use of a tissue sectioner to expose internal structures of biological samples for scanning electron microscopy.

A procedure yielding sections of unembedded biological samples for observation by scanning electron microscopy is described. Sections of samples, fixed and hardened in OsO4, were obtained in quantity with a tissue sectioner. Subsequent treatments to osmium-coat cut surfaces were employed prior to critical point drying. The procedure yields cleanly cut surfaces through cells and cytoplasmic organelles which are retained in their normal position. Sections of apple leaf and mouse kidney are illustrated. Sections can be readily cut in a desired plane with less structural damage than is typically encountered by other sectioning or dissection techniques.

Animals↗
PubMed1981

Conjoint radioenzymatic measurement of catecholamines, their catechol metabolites and DOPA in biological samples.

An assay is described for the simultaneous determination of dopamine, noradrenaline, adrenaline, dopa, 3,4-dihydroxyphenylacetic acid, 3,4-dihydroxyphenylethanol, 3,4-dihydroxymandelic acid and 3,4-dihydroxy-phenylglycol, capable of detecting amounts in the femtomol range. The assay is based on the O-methylation of the catechol moiety utilizing S-[3H-methyl]-adenosyl-L-methionine and a partially purified catechol-O-methyl transferase to form the various O-[3H-methyl]-catechol derivatives. The O-[3H-methyl]-catechol derivatives are purified by thin layer chromatography, solvent partitions and/or ion exchange chromatography. The assay was successfully applied to biological sample. It was possible for the first time, to detect free 3,4-dihydroxyphenylglycol, free 3,4-dihydroxyphenylethanol and 3,4-dihydroxymandelic acid in a small volume (25 microliter) of blood plasma of man, rat, dog and rabbit. The conjoint measurement of catecholamines and their catechol metabolites in minute amounts of biological samples may contribute to a more detailed understanding of catecholamine metabolism in the peripheral and central nervous system.

Animals↗
PubMed2005

Lead levels in some biological samples of auto-mechanics in Abeokuta, Nigeria.

Lead levels were determined in the blood, scalp hair and fingernails of 38, all male auto-mechanics (aged 18-45 years) from Abeokuta, South-western Nigeria. The subjects were classified into four sub-groups based on the period of exposure namely: 1-5, 6-10, 11-15, and >16 years. Thirty-two occupationally unexposed subjects (mainly office workers) served as the control. The weight, height and body mass indexes of all subjects were noted, in addition to other information obtained through structured questionnaire. The mean values of blood lead (BPb), hair lead (HPb) and fingernail lead (NPb) of the occupationally exposed subjects (n=38) were 48.50 +/- 9.08 microg/dL, 17.75 +/- 5.16 microg/g, and 5.92 +/- 3.30 microg/g respectively, while the corresponding mean values for these parameters in the control subjects (n = 32) were 33.(,5 +/- 10.09 microg/dL, 14.30 +/- 5.90 microg/g and 5.31 +/- 2.77 microg/g respectively. The differences in BPb and HPb levels of the two groups were statistically significant (P <0.05 and P <0.01 respectively), while that of NPb was not significant. The levels of lead in the biological samples appeared to have no relationship with the number of years on the job. From these results, it was obvious that the higher levels of lead in the biological samples of test subjects, compared with those of the controls were from environmental sources.

Adult↗
PubMed1999

[Separation and detection of tryptophan metabolites in biological samples].

A reversed phase HPLC method for separation and determination of the major tryptophan (TRP) metabolites in both pyrrolas pathway and TRP hydroxylase pathway, including TRP, kynurenine(KN), 3-hydroxykynurenine(3-HKN), kynurenic acid(KA), xanthurenic acid(XA), 5-hydroxytryptophan(5-HTP), 5-hydroxytryptamin(5-HT) and 5-hydroxyindoleacetic acid(5-HIAA), has been developed by sequential optimization of mobile phase based on acetate buffer and methanol. Trichloroacetic acid(TCA) was used as ion-pairing reagent to increase the retention of 3-HKN. The effects of pH and concentrations of TCA on separation were studied. Good separation can be achieved at pH 4.0-5.0 of mobile phase in less than 25 min. When TCA was not used, 3-HKN was hard to be detected in biological samples. The maximum retention of 3-HKN was obtained at pH 4.0 with mobile phase containing 50 mmol/L TCA. Combination of electrochemical (ED) and ultraviolet (UV) detection was used in which ED was responsible for detection of 3-HKN, 5-HTP, 5-HT and 5-HIAA and UV for the others. The influences of potential of ED and wavelength of UV on detection were studied. The optimization of conditions for separation and detection in different biological samples was also discussed.

Chromatography, High Pressure Liquid↗
PubMed2003

Fluorometric assays of phospholipase A2 activity with three different substrates in biological samples of patients with schizophrenia.

The rationale of this study was to understand the complexity of kinetics of fluorogenic phospholipid substrates as well as contradictory findings of clinical papers measuring phospholipase A2 (PLA2) activity using different methodologies. The aim was to recommend to clinicians and researchers what substrate in conjunction with what assay should be used. Two methods, (i) continuous fluorometric assay and (ii) high performance thin layer chromatography (HPTLC) on microplates combined with quantitative image scanning, were studied with three different substrates (bis-BODIPY FL C11-PC, NBDC6-HPC, PED6). The study demonstrates that NBD-PC is not a suitable substrate to measure PLA2 activity using a spectrofluorometer. On the other hand, NBD-PC gives the highest and most reproducible integrated light intensities (ILls) in HPTLC studies. Slow time-dependent increases in fluorescence intensities recorded with biological samples in fluorometers, but not caused by substrate splitting, had to be classified as "perturbation kinetics". PLA2 activities in blood samples of 26 unmedicated schizophrenia patients and 26 age-matched healthy controls were measured by the spectrofluorometric method and then compared with the activity data obtained with the HPTLC method. A significant group difference was found only with the HPTLC. In order to get more reliable results, we recommend that clinicians and researchers use NBD-phosphatidylcholines as PLA2 substrates in biological samples and start with an analytical separation of reaction products followed by image analysis of the fluorescent spots.

Chromatography, High Pressure Liquid↗
PubMed2006

Raman spectra of biological samples: A study of preprocessing methods.

In this study preprocessing of Raman spectra of different biological samples has been studied, and their effect on the ability to extract robust and quantitative information has been evaluated. Four data sets of Raman spectra were chosen in order to cover different aspects of biological Raman spectra, and the samples constituted salmon oils, juice samples, salmon meat, and mixtures of fat, protein, and water. A range of frequently used preprocessing methods, as well as combinations of different methods, was evaluated. Different aspects of regression results obtained from partial least squares regression (PLSR) were used as indicators for comparing the effect of different preprocessing methods. The results, as expected, suggest that baseline correction methods should be performed in advance of normalization methods. By performing total intensity normalization after adequate baseline correction, robust calibration models were obtained for all data sets. Combination methods like standard normal variate (SNV), multiplicative signal correction (MSC), and extended multiplicative signal correction (EMSC) in their basic form were not able to handle the baseline features present in several of the data sets, and these methods thus provide no additional benefits compared to the approach of baseline correction in advance of total intensity normalization. EMSC provides additional possibilities that require further investigation.

Algorithms↗
PubMed1998

Recycling immunoaffinity chromatography for multiple analyte analysis in biological samples.

The ability to isolate and measure multiple complex analytes in a single biological sample holds great potential in many biomedical fields, especially immunology and diagnostic clinical chemistry. We have developed a procedure involving recycling immunoaffinity chromatography for the simultaneous measurement of a number of analytes in a single sample. The procedure is based on the passage of a fluorochrome-labelled sample through a battery of small immunoaffinity columns, each column extracting a single analyte. Detection is achieved by acid elution of the bound analytes and laser-induced fluorescence. We have applied this system to a number of different biological fluids and found that it is capable of reliably isolating and measuring up to ten different cytokines in a 25-microl sample of human body fluid.

Antibodies↗
PubMed1988

An amplification technology for improving sensitivity when measuring components in biological samples.

A new technology for improving the sensitivity in measuring components in biological samples is described. The method is based on the use of spherical microbeads (detection beads) which contain a large amount of immobilized enzyme and a reagent with biospecific affinity for the component to be detected. These microbeads have been used in a 'sandwich reaction' for visualization of P-fimbriated Escherichia coli which has a known receptor structure (Gal(alpha 1-4)Gal(beta)). In the initial step the bacteria were enriched on a solid support (e.g., a plastic film or beads (greater than 150 microns)) to which the receptor structure had been covalently bound. In the next step detection beads coupled with enzyme and receptor structure were added and finally a chromogenic substrate for the enzyme was used for visualization. A sensitivity of 10(5) bacteria/ml was reached. The detection beads are of general utility and might be useful for the detection of lectins on other pathogens.

Agglutination Tests↗
PubMed2004

Evaluation of the Biological Sampling Kit (BiSKit) for large-area surface sampling.

Current surface sampling methods for microbial contaminants are designed to sample small areas and utilize culture analysis. The total number of microbes recovered is low because a small area is sampled, making detection of a potential pathogen more difficult. Furthermore, sampling of small areas requires a greater number of samples to be collected, which delays the reporting of results, taxes laboratory resources and staffing, and increases analysis costs. A new biological surface sampling method, the Biological Sampling Kit (BiSKit), designed to sample large areas and to be compatible with testing with a variety of technologies, including PCR and immunoassay, was evaluated and compared to other surface sampling strategies. In experimental room trials, wood laminate and metal surfaces were contaminated by aerosolization of Bacillus atrophaeus spores, a simulant for Bacillus anthracis, into the room, followed by settling of the spores onto the test surfaces. The surfaces were sampled with the BiSKit, a cotton-based swab, and a foam-based swab. Samples were analyzed by culturing, quantitative PCR, and immunological assays. The results showed that the large surface area (1 m2) sampled with the BiSKit resulted in concentrations of B. atrophaeus in samples that were up to 10-fold higher than the concentrations obtained with the other methods tested. A comparison of wet and dry sampling with the BiSKit indicated that dry sampling was more efficient (efficiency, 18.4%) than wet sampling (efficiency, 11.3%). The sensitivities of detection of B. atrophaeus on metal surfaces were 42 +/- 5.8 CFU/m2 for wet sampling and 100.5 +/- 10.2 CFU/m2 for dry sampling. These results demonstrate that the use of a sampling device capable of sampling larger areas results in higher sensitivity than that obtained with currently available methods and has the advantage of sampling larger areas, thus requiring collection of fewer samples per site.

Air Pollution, Indoor↗
PubMed1996

Analytical methods for the measurement of leukotrienes and other eicosanoids in biological samples from asthmatic subjects.

This paper summarizes methodological aspects of measurements of eicosanoids in biological samples and describes some applications of such methods in studies on leukotriene formation in the human airways and the effects of drugs interfering with these compounds in asthmatic subjects. For estimations of in vivo production of eicosanoids, major, stable metabolites were selected for analysis in biological fluids. An enzyme immunoassay for LTE4 was validated for use in unextracted urine samples. To monitor thromboxane production, a radioimmunoassay for 11-dehydro-TXB2 was developed and used for measurements in samples of human plasma and urine. In vitro production of leukotrienes in chopped human lung was measured by UV-spectroscopy after extraction and separation on RP-HPLC. Corrections for losses during purification were performed with individually selected internal standards.

Asthma↗