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At least 523 records · Page 29Linked to original sources
PubMed1991

Detection of Borrelia burgdorferi in biological samples using the polymerase chain reaction assay.

Oligonucleotide primers were used in the polymerase chain reaction assay to amplify specific DNA regions of the Borrelia burgdorferi 49-kb linear plasmid. One set of primers identifies a 442-bp DNA fragment in the OspA gene and a second pair of amplimers, a 176-bp DNA piece located in the OspB gene. The last set of primers, OspBpc3/pc4, outperformed the other pair in discriminating pathogenic North American or European isolates from related bacterial species, detected down to 4 spirochaetes, and was suitable for the identification of B. burgdorferi in biological samples, such as synovial and cerebrospinal fluids.

Borrelia burgdorferi Group↗
PubMed1987

Perspectives of analysis of carcinogenic and mutagenic metals in biological samples.

There is a continuing need to assess the status of exposure to humans of the carcinogenic and/or mutagenic metals in both biological and environmental samples to better ensure that current or past exposures do not entail unacceptable health risks or to detect potentially excessive exposure before the appearance of adverse health effects. In order to more readily evaluate both the extent of exposure and trends of human exposure as well as the bioavailability, bioaccumulation and transport of these elements and their compounds, sensitive analytical procedures are required for their determination of the various oxidative states (as well as their organic derivatives) in complex matrices such as those found in both environmental and biological samples. The major objective of this overview is to highlight the more recent trends and state-of-the-art methodologies for the determination and speciation of arsenic, selenium, cadmium, chromium and nickel in human and animal tissues while concomitantly noting germane aspects of their bioavailability and interactions. Aspects of biological monitoring of the above elements will be stressed due to their potential utility in augmenting diverse epidemiologic and occupational health studies.

Animals↗
PubMed2001

Neurotransmitter dopamine applied in electrochemical determination of aluminum in drinking waters and biological samples.

It was demonstrated that the decrease of the differential pulse voltammetric (DPV) anodic peak current of dopamine (3,4-dihydroxyphenylethylamine, DA) was linear with the increase of aluminum (Al) concentration. Under optimum experimental conditions (pH 4.6, 1.2 x 10(-3) M DA, and 0.04 M NaAc-HAc buffer solution), the linear range is 4.0 x 10(-7)-8.0 x 10(-5) M, the detection limit is 1.4 x 10(-7) M, and the relative standard deviation for 4 x 10(-5) M Al(III) is 3.5% (n=8). Many foreign species, especially some low-molecule-weight biological molecules, were chosen for interference testing. The proposed method was applied to the determination of Al in biological samples such as synthetic renal dialysate, Ringer's solution, human blood, cerebrospinal fluid of a patient, and urine of a diabetic patient. The corresponding recoveries were generally between 95 and 105%. The basic principle of the method was determined by examining Al complexed with DA. This results in the blockage of the electroactive sites on DA, followed eventually by the reduction of the electrochemical response of DA. This result was verified by examining the behavior of DA, both in the presence and absence of Al, using electrochemical, UV-Vis, Raman, and (13)C NMR spectroscopic methods.

Aluminum↗
PubMed1994

High-performance liquid chromatographic confirmation of cocaine and benzoylecgonine in biological samples using photodiode-array detection after toxicological screening.

In the later stages after intake, the important markers of cocaine abuse are its main metabolites in urine, benzoylecgonine and ecgonine methyl ester. The efficiency of the extraction of amphoteric benzoylecgonine together with cocaine from aqueous media by means of various solvents at various pH values and by means of a mixed solid phase was tested. The extraction of benzoylecgonine with diethyl ether is not efficient, whereas chloroform, dichloromethane or mixed solid-phase extraction give satisfactory results. The analytical strategy for the general chromatographic screening and identification of unknown drugs in biological samples based on diethyl ether extraction was modified to permit the sensitive detection of cocaine abuse also on the basis of benzoylecgonine. A complementary high-performance liquid chromatographic method with photodiode-array detection after solid-phase extraction was introduced for specific confirmation and determination of cocaine and benzoylecgonine.

Chromatography, High Pressure Liquid↗
PubMed2003

Global analyses of cellular lipidomes directly from crude extracts of biological samples by ESI mass spectrometry: a bridge to lipidomics.

Lipidomics is a rapidly expanding research field in which multiple techniques are utilized to quantitate the hundreds of chemically distinct lipids in cells and determine the molecular mechanisms through which they facilitate cellular function. Recent developments in electrospray ionization mass spectrometry (ESI/MS) have made possible, for the first time, the precise identification and quantification of alterations in a cell's lipidome after cellular perturbations. This review provides an overview of the essential role of ESI/MS in lipidomics, presents a broad strategy applicable for the generation of lipidomes directly from cellular extracts of biological samples by ESI/MS, and summarizes salient examples of strategies utilized to conquer the lipidome in physiologic signaling as well as pathophysiologically relevant disease states. Because of its unparalleled sensitivity, specificity, and efficiency, ESI/MS has provided a critical bridge to generate highly accurate data that fingerprint cellular lipidomes to facilitate insight into the functional role of subcellular membrane compartments and microdomains in mammalian cells. We believe that ESI/MS-facilitated lipidomics has now opened a critical door that will greatly increase our understanding of human disease.

Alzheimer Disease↗
PubMed1983

Analysis of monobutyryl and dibutyryl derivatives of adenosine 3',5'-monophosphate in biological samples using isocratic ion pair high-performance liquid chromatography.

Adenosine 3',5'-monophosphate (cyclic AMP), its dibutyryl and monobutyryl derivatives, and a number of other naturally occurring adenine-containing compounds were separated by isocratic ion pair high-performance liquid chromatography. A mobile phase consisting of 30% methanol in 0.1 M KH2PO4 (pH 4.0) containing 1 mM tetramethylammonium hydroxide as the counterion was used to separate the butyryl derivatives. To sufficiently separate cyclic AMP from other adenine-containing compounds, a mobile phase containing 6% methanol in the same aqueous buffer plus counterion was used. Extraction of these cyclic nucleotides from deproteinized biological samples using disposable reverse-phase extraction columns is described. This not only eliminated lipophilic contaminants, but also served to concentrate the samples. The outlined procedures were used to determine the concentrations of the butyryl derivatives in lung tissue and perfusate following a 35-min lung perfusion with 100 microM N6-O2'-dibutyryl cyclic AMP. The role of this technique in the analysis of cyclic nucleotide derivatives as compared with conventional assay procedures is discussed.

Animals↗
PubMed2005

Biocompatible channels for field-flow fractionation of biological samples: correlation between surface composition and operating performance.

Biocompatible methods capable of rapid purification and fractionation of analytes from complex natural matrices are increasingly in demand, particularly at the forefront of biotechnological applications. Field-flow fractionation is a separation technique suitable for nano-sized and micro-sized analytes among which bioanalytes are an important family. The objective of this preliminary study is to start a more general approach to field-flow fractionation for bio-samples by investigation of the correlation between channel surface composition and biosample adhesion. For the first time we report on the use of X-ray photoelectron spectroscopy (XPS) to study the surface properties of channels of known performance. By XPS, a polar hydrophobic environment was found on PVC material commonly used as accumulation wall in gravitational field-flow fractionation (GrFFF), which explains the low recovery obtained when GrFFF was used to fractionate a biological sample such as Staphylococcus aureus. An increase in separation performance was obtained first by conditioning the accumulation wall with bovine serum albumin and then by using the ion-beam sputtering technique to cover the GrFFF channel surface with a controlled inert film. XPS analysis was also employed to determine the composition of membranes used in hollow-fiber flow field-flow fractionation (HF FlFFF). The results obtained revealed homogeneous composition along the HF FlFFF channel both before and after its use for fractionation of an intact protein such as ferritin.

Animals↗
PubMedDate not supplied

A solid liquid extraction and preconcentration method for the atomic absorption spectrometric determination of trace cobalt in various alloys and biological samples.

Cobalt is quantitatively retained as cobalt-2-nitroso-4-sulfonic acid (nitros-S)-tetradecyldimethylbenzylammonium (TDBA+) ion-pair complex on microcrystalline naphthalene in the pH range 6.2-9.0 from a large volume of its aqueous solution of various complex samples. After filtration, the solid mass consisting of cobalt complex and naphthalene is dissolved in 5 ml of dimethylformamide (DMF) and the metal is determined by flame atomic absorption spectrometry (FAAS). Cobalt complex can alternatively be quantitatively adsorbed on tetradecyldimethylbenzylammonium chloride-naphthalene adsorbent packed in a column and determined similarly. The calibration curve is linear over the concentration range 0.2-11.5 micrograms of cobalt in 5 ml of the final DMF solution. In this case, 0.2 microgram of cobalt may be concentrated in a column from 250 ml of aqueous sample where its concentration is as low as 0.8 ng/ml. Eight replicate determinations of 3.0 micrograms of cobalt in the final DMF solution give a mean absorbance of 0.045 with a relative standard deviation of 1.8%. The sensitivity for 1% absorption is 59 ng/ml. The interference of a large number of anions and cations on the determination of cobalt has been studied and the optimum conditions developed utilized for its trace determination in various alloys and biological samples. The method may also be used for the determination of cobalt in some environmental samples.

Alloys↗
PubMed1999

A new HPLC method for the direct analysis of triglycerides of dicarboxylic acids in biological samples.

Dicarboxylic acids (DA) are alternate lipid substrates recently proposed in parenteral nutrition. Two new derivatives of DA, a triglyceride of sebacic (TGC10) and one of dodecanedioic (TGC12) acid have been synthesised in order to reduce the amount of sodium given with the unesterified forms. The present paper describes a rapid and direct high-performance liquid chromatographic method (HPLC) for the analysis of these substances in both plasma and urine. Thirty-six male Wistar rats were rapidly injected with 64 mg of TGC10 or 53 mg of TGC12. The triglycerides and their products of hydrolysis were measured in plasma samples taken at different times. For the dose of 500 ng the intra-assay variations ranged from 6. 80+/-0.35% for TGC10 to 18.6+/-3.20% for TGC12 and the inter-assay variations were from 4.44+/-2.21% for TGC10 to 15.0+/-6.72% for TGC12. The detection limit for both triglycerides was 5 ng. This rapid and direct HPLC method could have practical implications in monitoring the concentration of both triglycerides and free forms of DA in biological samples of patients who might benefit from the administration of these substances during parenteral nutrition regimens.

Animals↗
PubMed2001

Spectrophotometric determination of vanadium(V) in minerals, steels, soil and biological samples using phenothiazine derivatives.

Two simple, rapid and sensitive spectrophotometric methods have been proposed for the determination of vanadium(V) using butaperazine dimaleate (BPD) and propionyl promazine phosphate (PPP). These methods are based on the formation of red-colored radical cations on reaction with vanadium(V) in phosphoric acid medium, with their absorbance maxima at 513 nm. Beer's law is valid over the concentration range of 0.25-5.0 micrograms ml-1 and 0.2-4.0 micrograms ml-1, with Sandell's sensitivity values of 6.1 ng cm-2 and 6.0 ng cm-2 for BPD and PPP respectively. The proposed methods have been successfully applied to the analysis of vanadium steels, minerals, biological samples and soil samples.

Humans↗
PubMed2000

Determination of boronophenylalanine in biological samples using precolumn o-phthalaldehyde derivatization and reversed-phase high-performance liquid chromatography.

A reversed-phase high-performance liquid chromatographic method for the detection of boronophenylalanine is described. Determination was obtained by precolumn reaction of o-phthalaldehyde with a mixture of standard amino acids containing boronophenylalanine and separating the corresponding o-phthalaldehyde derivatives, using a Kromasil C-18, 250 x 4.6 mm, 5-microm particle size column, a step gradient with two buffers, a flow rate of 1.2 ml/min, a column temperature of 23 degrees C, and fluorimetric detection (excitation and emission wavelengths of 330 and 430 nm, respectively). The use of such a method for assaying boronophenylalanine in biological samples was tested in neutralized perchloric acid blood and cerebral tissue extracts of rats treated with intracarotid administration of 300 mg/kg of body weight boronophenylalanine. Results of these experiments showed that the present HPLC method represents a valid alternative to currently available analytical techniques for assaying boronophenylalanine based on boron determination in terms of reproducibility, recovery, or sensitivity. Therefore, it is suggested that the present method may routinely be used in all preclinical and clinical studies in which quantification of circulating and tissue concentrations of boronophenylalanine is critical for the application of boron neutron capture therapy.

Animals↗
PubMed2003

Rearrangement patterns of JC virus noncoding control region from different biological samples.

The JC virus (JCV) is generally considered the etiological agent of progressive multifocal leukoencephalopathy (PML), a demyelinating brain illness, often associated with immunosuppression and significantly frequent in acquired immunodeficiency syndrome (AIDS) patients. The primary infection by JCV is usually asymptomatic and the virus can remain in a latent status in the kidney. As a consequence of immunological alterations of the host, the virus can show a genetic variability in the noncoding control region (NCCR) due to deletions, duplications, and insertions as compared with the archetype. The NCCR of the archetype strain can be divided into six regions, named boxes A to F. In this study, the authors evaluated the presence of the JCV genome in different biological samples, such as urine, peripheral blood mononuclear cells (PBMCs) and cerebral spinal fluid (CSF) by means of polymerase chain reaction (PCR). After sequencing of the PCR fragments, the NCCR structure of isolated JCV strains was analyzed in order to verify the presence of different viral variants. An analysis of the homology and of the multiple alignment of the obtained sequences in comparison with the archetype strain has been carried out. The results indicated the presence of different rearrangements among the analyzed samples. Whereas in the urine, the NCCR structure always appeared very similar to that of the archetype, in the PBMCs and CSF, the NCCR sequences showed specific and characteristic rearrangements as compared to the archetype. These different rearrangements could be correlated with the emerging of an NCCR organization more suitable for the development of PML.

AIDS-Related Opportunistic Infections↗
PubMed2004

Analysis of fluorophore-labelled hyaluronan and chondroitin sulfate disaccharides in biological samples.

In this report, we describe a polyacrylamide gel electrophoresis for the analysis of fluorophore-labelled hyaluronan (HA) and chondroitin sulfate (CS) Delta-disaccharides. The method utilizes derivatization of reducing ends of hyaluronan and the variously sulfated chondroitin sulfate Delta-disaccharides with 2-aminoacridone (AMAC), followed by electrophoresis in Tris-HCl buffer (pH 8.8), and polyacrylamide gel (T 25%/C 3.75%). The method was applied to the analysis of GAGs secreted into the culture medium of human aortic smooth muscle cells and the obtained results were compared with those analysed by fluorophore assisted carbohydrate electrophoresis (FACE). The described method is a useful and sensitive tool for the rapid monitoring of GAGs in high number of biologic samples.

Aminoacridines↗
PubMed1989

Target materials suitable for projection X-ray microscope observation of biological samples.

Trials for improving the contrast of projection X-ray images by finding better target materials than Ti (lambda K alpha: 2.75 A), which has been found to be suitable for many kinds of specimens, were carried out, considering the factors of melting point, thermal conductivity, mechanical strength, chemical stability, absorption of the X-ray, etc. Au, Ta, and Ge were found to be suitable, giving 5-10 A X-rays when low electron beam energies around 10 kV were used. In order to take advantage of the long wavelength X-rays of these targets, we tried to minimize the attenuation of the imaging X-rays in the air or to use a vacuum camera. Even in non-stained biological samples such as HeLa cells and lingual muscle section, their microstructures were visible with sufficient contrast.

Animals↗
PubMed1994

Application of an electrochemical detector with a graphite electrode to liquid chromatographic determination of penicillamine and captopril in biological samples.

A high-performance liquid chromatographic determination of penicillamine and captopril in rat serum, liver and kidney samples is described. An electrochemical detector with a graphite working electrode at a potential of +0.9 V vs the Ag/AgCl reference electrode is used for the detection system. Linear responses of the peak height to the amount of samples injected were obtained in a range of 0.1-500 ng on-column and 0.5-500 ng on-column for penicillamine and captopril with correlation coefficients of 0.997 and 0.995, respectively. Detection limits at a signal-to-noise ratio of 3 were 20 and 300 pg for penicillamine and captopril, respectively. The graphite electrode has a long lifetime of about 4 months with continuous use, even with the high voltage supplied. The analytical application of this method to the determination of penicillamine and captopril in biological samples was successful.

Administration, Oral↗
PubMed1990

Chemical and physical properties of the major serum albumin adduct of aflatoxin B1 and their implications for the quantification in biological samples.

Aflatoxin B1 (AFB1) is a potent carcinogen. It reacts with liver DNA and serum albumin in a dose-dependent manner. Serum albumin adducts of aflatoxins have been used for exposure assessment. The immunological methods used so far do not differentiate between the different adducts of AFB1 and of AFG1. In order to establish an analytical method to measure one specific AFB1 adduct, we investigated the structure and the chemistry of the major serum albumin adduct of aflatoxin B1 (lysine-AFB1). 13C-NMR, 1H-NMR, UV, IR, fluorescence and MS spectra of lysine-AFB1 (8-[N-(2-amino-hexanoyl-6-yl)-5-oxo-3-pyrrolin-3-yl]-7-hydroxy-5- methoxycyclopentenone[2.3-c]coumarin) were recorded and discussed. The quantification of lysine-AFB1 was demonstrated in biological samples. Serum albumin was digested with pronase and analysed by HPLC with a fluorimeter as detector. The detection limit found for lysine-AFB1 was 20 fmol.

Aflatoxin B1↗
PubMed2006

Detection of noncovalent complexes in biological samples by intensity fading and high-mass detection MALDI-TOF mass spectrometry.

Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry has not yet contributed widely to the study of intact noncovalent biomolecular complexes, because MALDI is known to cause dissociation of the interaction partners and induce formation of nonspecific aggregates. Here, we present a new strategy to circumvent this problem. It is based on intensity fading (in the low m/z range) and high-mass detection MALDI mass spectrometry (MS), using a cryodetector (in the high m/z range), with and without chemical cross-linking of the interaction partners. The study focuses on noncovalent interactions between the human enzyme carboxypeptidase A (hCPA) and three protease inhibitors (PCI, TCI, and LCI) present in heterogeneous mixtures of other nonbinding molecules derived from a biological source, an extract from leech (Hirudo medicinalis). Another example involves an extract of the sea anemone Stichodactyla helianthus, which is used without previous fractionation to detect the specific complex between the enzyme trypsin and the endogenous SphI-1 inhibitor. The results give insight into the mechanism of intensity fading MS and demonstrate that the specificity of binding is greatly favored when the overall concentrations of the analytes (nonbinding molecules, protease inhibitor and target enzyme) present in a biological sample of interest are kept at low concentrations, in the sub-micromolar range. Higher concentrations may lead to unspecific interactions and the formation of aggregates both during the MALDI process and during reaction with the cross-linking reagents. This strategy is expected to advance the field of high-throughput affinity-based approaches, by taking advantage of a new generation of high mass detectors for MALDI-TOF instruments.

Animals↗
PubMed1982

Two simple high-performance liquid chromatographic methods for simultaneous determination of 2'-deoxycytidine 5'-triphosphate and cytosine arabinoside 5'-triphosphate concentrations in biological samples.

Cytosine arabinoside (ara-C) has been used in the treatment of leukemia, but its exact mechanism of cytotoxicity is not yet known. One of the proposed mechanisms for the effectiveness of this drug in treating leukemias suggests that a metabolite of ara-C, i.e., 2'-deoxycytidine 5'-triphosphate (araCTP), competes with cytosine arabinoside 5'-triphosphate (dCTP) for binding to DNA polymerase. The ratio of the drug metabolite to the endogenous nucleotide (araCTP/dCTP) may, therefore, be important in determining the effectiveness of ara-C therapy. This ratio may also play a role in drug resistance. Previously published methods have focused on either araCTP or dCTP, along with metabolites and analogues of one of these compounds. The methods presented here provide two simple, sensitive ways to measure dCTP and araCTP in the same biological sample.

Arabinofuranosylcytosine Triphosphate↗