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At least 487 records · Page 27Linked to original sources
PubMed2006

Heavy metal sequential extraction methods--a modification for tropical soils.

Sequential extractions of metals can be useful to study metal distributions in various soil fractions. Although several sequential extraction procedures have been suggested in the literature, most were developed for temperate soils and may not be suitable for tropical soils with high contents of Mn and Fe oxides. The objective of this study was to develop a sequential fractionation procedure for Cu and Zn in tropical soils. Extractions were performed on surface (0-20 cm) samples of ten representative soils of Sao Paulo State, Brazil. Chemically reactive Mn forms were satisfactorily assessed by the new modified procedure. Amorphous and crystalline Fe oxides were more selectively extracted in a new two-step extraction. Soil-born Zn and Cu were primarily associated with recalcitrant soil fractions. The proposed procedure provided more detailed information on metal distribution in tropical soils and better characterization of the various components of the soil matrix. The new procedure is expected to be an important tool for predicting the potential effects of environmental changes and land application of metals on the redistribution of chemical forms of metals in tropical soils.

Copper↗
PubMed1985

Histochemical demonstration of desialation and desulphation of normal and inflammatory bowel disease rectal mucus by faecal extracts.

Experiments were carried out to assess the susceptibility of normal and inflammatory bowel disease rectal mucus to desulphation and desialation by faecal extracts and by bacterial sialidase. The effects were assessed histochemically using a combined high iron diamine (HID) and alcian blue (AB) stain for sulphomucins and sialomucins. Rectal mucus in biopsies from controls (irritable bowel syndrome) and patients with ulcerative colitis or Crohn's disease was resistant to desialation by Clostridium perfringens sialidase, but susceptible to desialation and desulphation by bacteria-free extracts of normal faeces. Periodic acid-Schiff (PAS) staining of adjacent sections similarly treated showed retention of neutral mucus. One faecal extract selectively desulphated all 42 biopsies, causing the goblet cells to change from HID positive to AB positive, suggesting that most, or all HID positive cells also contain sialomucins. This alters the interpretation of previous histochemical studies. Faecal extracts from patients with active ulcerative colitis (n = 6) had desialating and desulphating effects similar to faecal extracts from normal subjects (n = 6). Ulcerative colitis (n = 21), Crohn's disease (n = 18), and control (irritable bowel syndrome) (n = 17) rectal biopsies all showed similar susceptibility to desulphation by a pooled normal faecal extract, but rectal biopsies from patients with Crohn's disease proved more resistant to desialation than control or ulcerative colitis biopsies (p less than 0.02). These studies imply that colonic mucus undergoes continual desulphation and desialation in vivo as a result of faecal enzyme activity that is probably mainly of bacterial origin. Altered susceptibility of colonic mucus to this may be important in the pathogenesis of colonic disease.

Adolescent↗
PubMed1987

The application of flow cytometry to the study of nuclear matrix. A multiparametric analysis.

The nuclear matrix, which in situ corresponds essentially to the interchromatin ribonucleoprotein particles, once isolated appears constituted by a peripheral lamina connected to the nucleolar remnant by a fibrous network. The features of the matrix components depend on the procedure employed during its purification, a multistep method commonly involving nuclease digestion, low and high salt extractions and treatment with a non ionic detergent. Here is reported the application of flow cytometry to the analysis of matrix purification. The experimental data indicate that, despite deep changes of the nuclear content due to the selective extraction of almost all nucleohistone and membrane components, the scatter pattern of the matrix, which is drastically lowered as the nucleic acid content decreases, closely resembles that of the starting nuclei. This behaviour permits one to follow the different matrix populations deriving from diploid and polyploid parenchymal liver nuclei throughout the isolation procedure and confirms the feasibility of flow cytometry for both analysis and sorting of nuclei and nuclear matrices. In addition, an ultrastructural analysis on thin sections and a morphometric study by means of semiautomated image analysis of phase contrast micrographs have been performed. The image analysis showed a decrease in particle dimension to about 50% of the nuclear value, which could partially explain the reduction of forward light scatter.

Animals↗
PubMed1979

[Direct determination of clonazepam (Rivotril) and 7-amino clonazepam in plasma by gas-chromatography (author's transl)].

A method is developed for direct gas-chromatographic determination of clonazepam (Rivotril) and its main metabolite, 7-amino clonazepam, in plasma, using desmethylflunitrazepam as internal standard. Following selective extraction, the benzodiazepines are analyzed by gas-chromatography, with a glass column filled with 3% OV17 on Gas Chrom Q and 63Ni electron capture detector. The procedure, which requires neither hydrolysis nor derivatisation, has a good selectivity. The sensitivity is 5 ng/ml of plasma for a valid quantitative determination. We have to improve this limit for fine pharmacokinetic studies, but the method is already available for therapeutic and pharmacovigilance controls. It is also suitable for diagnostic of eventual overdosing or poisoning, based on plasma or urine analysis.

Benzodiazepinones↗
PubMedDate not supplied

On-line immunoaffinity extraction and HPLC analysis of flunitrazepam and its main metabolites in serum.

A sensitive, simple, and rapid method for the determination of flunitrazepam and its major metabolites (7-aminoflunitrazepam, 7-acetamidoflunitrazepam, and norflunitrazepam) in serum and plasma is presented. The on-line procedure uses an immobilized, highly reusable antibody against benzodiazepines for selective extraction from serum followed by analysis by high-performance liquid chromatography with ultraviolet detection. This reliable method provides a limit of detection of 1 ng/mL serum, and results are obtained in less than 40 min.

Chromatography, Affinity↗
PubMed2005

Analysis of steroid conjugates in sewage influent and effluent by liquid chromatography-tandem mass spectrometry.

Environmental endocrine disruptors such as estrone (E1) and beta-estradiol (E2) are excreted in human urine primarily as water-soluble glucuronides and sulfates that can dissociate in wastewater treatment systems to the more active free estrogens. Measurement of the distribution and fate of the steroid conjugates and the corresponding free estrogens in treatment plants and receiving waters is critical for understanding the reproductive and developmental effects of these substances on aquatic organisms. A sensitive method to measure steroid estrogen conjugates in matrix-rich sewage influents and effluents (method detection limits ranged from 0.04 to 0.28 ng/L) has been developed using HPLC tandem mass spectrometry with electrospray ionization. The method employs extensive sample purification by selective extraction from an Oasis HLB solid-phase cartridge followed by separation by anion exchange chromatography. This purification scheme, combined with a stable isotope dilution approach, was used to overcome problems of matrix suppression of ionization and permitted selective and sensitive detection of six target conjugates of E1 and E2. Accurate quantitation was highly dependent on the method of sample preservation. Acidification of each sample (pH 2.0) was effective in preventing enzymatic or chemical decomposition of steroid conjugates in all sample types, whereas glucuronide conjugates were hydrolyzed in the presence of mercury and formalin preservatives. Measured concentrations of steroid sulfates in the influent to a sewage treatment plant were approximately 100 times greater than that of the respective steroid glucuronides, suggesting that the preponderance of glucuronides had dissociated prior to reaching the treatment plant. A small percentage of the steroid sulfates persisted through biological treatment of sewage and was measured in the effluent. Steroid conjugates that survive decomposition or bypass biological treatment of municipal wastewater are released into surface waters and may serve as a source of free steroids.

Chromatography, Liquid↗
PubMed1977

Spectrofluorometric determination of substituted tetrahydrocarbazoles by a methylene blue sensitized photolytic reaction.

A spectrofluorometric method was developed for the determination of 6-chloro-9-[2-(2-methyl-5-pyridyl)ethyl]-1,2,3,4-tetrahydrocarbazole-2-methanol hydrochloride and its carboxylic acid analog in blood and urine. It involves extraction of both compounds at neutral pH, either from blood into ethyl acetate (the residue of which is dissolved in either) or from urine directly into ether. Both the alcohol and the acid are separated from each other by selective extraction into acid or base, respectively, and then reextracted into either from the respective aqueous medium by appropriate pH adjustment. The residues of the ether extracts containing the compounds are dissolved separately in 0.25 N NH4OH. Methylene blue is added to all samples, which are then exposed to UV energy for 15 min to produce the fluorophores. The fluorescence of the solutions is read at 370 nm, with excitation at 340 nm. The linear range of quantitation of both compounds is 0.02-10 mug/each/ml of final solution. The method was applied to the determination of blood levels and urinary excretion of the alcohol and its acid metabolite in a dog.

Animals↗
PubMed2006

Evaluation of the antioxidant activity of wheatgrass (Triticum aestivum L.) as a function of growth under different conditions.

The antioxidant activity of wheatgrass, which is consumed as a dietary supplement, was estimated at different levels. The methods employed include FRAP (ferric reducing antioxidant power), ABTS (2,2'-azobis-3-ethylbenzthiazoline-6-sulfonic acid) and DPPH (1,1'-diphenyl-2-picrylhydrazyl) assays. Aqueous and ethanol extracts of wheatgrass grown under different conditions over a period of 6, 7, 8, 10 and 15 days were used. Lipid peroxidation and oxygen radical absorbance capacity (ORAC) were determined and utilized to check the potency of a few selected extracts. Different conditions used for growth were (1) tap water, (2) tap water with nutrients, (3) soil and tap water, and (4) soil with nutrients. For comparison, a commercially available wheatgrass tablet was analysed. To explain the reasons behind the observed differences, the total phenolic and flavonoid contents of the extracts were measured. These contents increased with growth under all the conditions. The ethanol extracts were found to have a higher phenolic and flavonoid content than the aqueous extracts. The highest FRAP values occurred on day 15 of growth under condition 4, the values being 0.463 and 0.573 mmol of ascorbic acid and Trolox equivalents/100 g fresh wheatgrass for aqueous and ethanol extracts, respectively. In the aqueous extracts no specific trend was observed with the DPPH assay for the different conditions nor for the growth period. In the case of ethanol extracts, however, it increased with the growth period and the wheatgrass grown in condition 4 was found to be the most effective. These extracts were also found to inhibit significantly ascorbate-Fe2+ induced lipid peroxidation in rat liver mitochondria. The ORAC values of aqueous and ethanol extracts of day 10 with condition 4 were found to be 39.9 and 48.2, respectively, being higher than those reported for many natural extracts or vegetables.

Animals↗
PubMed2005

[Skin tests in allergology: really so simple?].

In allergology, skin tests (ST) are one of the main tools. Their simplicity, rapidity of the result, low cost, near absence of risk make them complements of choice to the patient history which remains the crucial step of the diagnosis. ST demonstrate in vivo the capacity of the cutaneous mast cells to potentially react to allergens. Their sensitivity is good, some precautions have to be taken into account (no antihistaminic drugs, quality of the extracts). Specificity is also good, but a positive test (which is suggestive of the presence of IgE) not always predicts clinical allergic manifestations. Knowledge of limits and pitfalls of ST is of major importance, especially when it comes to selecting extracts for specific immunotherapy and to investigate severe anaphylactic reactions to food or drugs.

Diagnosis, Differential↗
PubMedDate not supplied

Optimization of solid-phase microextraction for the gas chromatography/mass spectrometry analysis of persistent organic pollutants.

In this work, solid-phase microextraction (SPME) has been applied as an alternative for the selective extraction of 3 polybrominated diphenyl ethers (PBDEs), 2,2',4,4'-tetrabromodiphenyl ether (PBDE-47); 2,2',4,4',5-pentabromodiphenyl ether (PBDE-99); and 2,2',4,4',6-pentabromodiphenyl ether (PBDE-100), and 2 alkylphenols, 4-tert-OP and 4-NP, prior to their analysis by gas chromatography/mass spectrometry (GC/MS). The advantages of this technique are mainly its simplicity, cost-effectiveness, and time-saving sample preparation, as well as being a solvent-free technique. With the aim of optimizing the conditions for an efficient extraction of the studied compounds, different fiber coatings and the main parameters affecting the extraction procedure have been evaluated. The results obtained showed a good linearity in the range of concentrations investigated, and adequate relative standard deviation values were found according to the range accepted for SPME. Recovery values were in the range of 78-108%, and good detection and quantitation limits at ppt levels were obtained for both methods, allowing the determination of the selected compounds in samples at trace levels. The results obtained clearly show the potential of SPME for efficient concentration of the target compounds and also demonstrate the reliability of this extraction technique for their GC/MS analysis.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Effect of different proteases on bitterness of hemoglobin hydrolysates.

Hemoglobin was hydrolyzed by several enzymes (Proctase, Alcalase, Neutrase, papain). Hydrolysates were analyzed (degree of hydrolysis, gel permeation on Superose 12 column, tasting) and fractionated by ultrafiltration and 2-butanol extraction. The bitter peptides were isolated and identified. The results were compared with those already obtained with peptic hemoglobin hydrolysates. All the findings were confirmed. Ultrafiltration concentrated bitter compounds in the fraction corresponding to 500-5000 Da, and these compounds were selectively extracted by 2-butanol. All the bitter peptides belonged to the same fragment of the beta-chain of bovine hemoglobin. Finally, the use of a Superose 12 chromatographic column for easy detection of bitter hydrolysates without sensory analysis could be generalized for hemoglobin hydrolysates.

Amino Acid Sequence↗
PubMed2004

Quality of life after traumatic brain injury: a review of research approaches and findings.

OBJECTIVES: To assess existing knowledge of quality of life (QOL) of people with traumatic brain injury (TBI) and to make recommendations for methodologic and substantive research in this area. DATA SOURCES: Published research on QOL of persons with TBI, identified from databases, ancestry search, and the author's files. STUDY SELECTION: Empirical, theoretical, and methodologic articles relevant to 5 areas: QOL as achievements, QOL as subjective well-being (SWB), QOL as utility, QOL experienced, and QOL measurement instruments applicable to TBI or specifically developed for people with this impairment. DATA EXTRACTION: Selection of QOL indicators, with focus on TBI versus non-TBI differences. DATA SYNTHESIS: Studies of QOL as achievements show that in almost all areas, people with TBI score lower than they did before injury and lower than comparisons groups. There are limited gaps in our knowledge in this area. Research into QOL as SWB shows that after TBI, people typically report, for example, somewhat lower life satisfaction and affect than do comparison groups, and that injury severity is not necessarily a predictor of SWB. There are almost no studies of QOL as utility of life after TBI. CONCLUSIONS: Major research recommendations include: exploring the ability of TBI subjects to self-report; determining the salience of domains of life for this group; developing utility instruments that are sensitive to differences in deficits in cognition and other health and life domains; and doing qualitative studies that explore the experience of QOL.

Brain Injuries↗
PubMedDate not supplied

Reverse micellar extraction of antibiotics from aqueous solutions.

Several antibiotics such as erythromycin, oxytetracyclin, benzylpenicillin, and actidione were extracted from aqueous buffers into reverse micellar solution of bis(2-ethylhexyl) sulfosuccinate sodium salt (AOT) in isooctane and recovered with high efficiency under mild conditions. Preliminary experiments with oxytetracycline dissolved in a fermentation broth indicate that the antibiotic can be selectively extracted from the broth and recovered efficiently without serious loss of potency.

Anti-Bacterial Agents↗
PubMed2000

The application of supercritical fluid extraction to cocaine and its metabolites in blood and urine.

Supercritical fluid extraction (SFE) is emerging as a valuable analytical technique for use as an alternative to conventional solid-phase (SPE) and liquid-liquid extraction techniques. It is a relatively new technique based on the use of supercritical fluids for the isolation of analytes from various matrices and is attracting great interest because of the increasing need for a simple, rapid, environmentally friendly, automated, and selective extraction method. A new method using SFE procedures for the extraction of cocaine and its major metabolites, benzoylecgonine and ecgonine methyl ester, from whole blood and urine was developed. This study has shown that cocaine and its metabolites can be successfully extracted from blood and urine using SFE techniques. Levels measured using SFE have shown analyte recovery better than 70% for cocaine, better than 40% for benzoylecgonine, and better than 85% for ecognine methyl ester from whole blood and urine. Good run-to-run reproducibility was observed between each extraction with limits of detection and quantitation of 1 ng and 10 ng based on 200 microL of blood and urine. A comparison between SPE and developed SFE techniques was investigated to observe if a correlation existed between the two methods. Studies proved that a correlation did exist between the two methods for spiked blood and urine samples with comparative results. This paper details a procedure for the extraction of cocaine and its metabolites from blood and urine.

Chromatography, High Pressure Liquid↗
PubMed1996

Pulpal response to dentin etched with 10% phosphoric acid.

PURPOSE: To histopathologically evaluate the effect of etching sound dentin with 10% phosphoric acid, in cavities prepared just within the DEJ on young patients. MATERIALS AND METHODS: Twenty-four orthodontic patients who required premolar extractions were selected for the study. Each of the patients had facial Class V resin composite restorations placed in two maxillary premolars selected for extraction. Each preparation was cut circular, 2 mm in circumference and 0.5 mm into dentin. The dentin of one maxillary premolar preparation, randomly selected, was etched with 10% phosphoric acid (Bisco) for 20 seconds. This was followed by the placement of a dentin bonding agent (All-Bond 2) and a microfilled composite restoration (Silux). The contralateral maxillary premolar, received a similar preparation, but the dentin surface was lined with a light-cured glass ionomer liner before etching of the enamel, followed by placement of a dentin bonding agent and a microfilled resin composite restoration. One of the mandibular premolars was randomly selected as a negative control, having no treatment. Fourteen days after the placement of the restorations, the teeth were extracted, and histologically examined for insult to the pulpal tissues. Injury to the pulp was evaluated by quantitative measures of histopathology, including necrosis, infiltration by inflammatory cells, and other indicators of tissue injury. RESULTS: Using a Kruskal-Wallis analysis, there was no statistically significant difference in pulpal histopathology of the teeth with etched dentin versus teeth with dentin protected by a liner or the negative control teeth (P < 0.05).

Acid Etching, Dental↗
PubMed2001

Development and application of immunoaffinity chromatography for the determination of the triazinic biocides in seawater.

The development of an immunoaffinity chromatography (IAC) procedure for the selective extraction of the anti-fouling agent Irgarol 1051 [2-(tert.-butylamino)-4-(cyclopropylamino)-6-(methylthio)-1,3,5-triazine] from seawater is described. The anti-Irgarol 1051 antibodies were covalently bound to agarose-based beads support. IAC column capacities were higher than 400 ng and ethanol-water (70:30) was selected as eluting mixture. After percolation of 250 ml of water sample containing Irgarol 1051 at environmental levels (ng l(-1) ), the breakthrough volume was still not achieved. Other triazine herbicides percolated through the IAC column showed good recoveries. Thus, this IAC procedure may be useful to extract related compounds. The developed IAC column was applied to real seawater samples and compared with RP-C18 cartridges. The limit of detection (LOD) reached by using the IAC procedure was twenty times lower than the LOD achieved by the RP-C 18 cartridges using the same detection system. Irgarol 1051 was detected at ng l(-1) levels in the Barcelona marina (northwestern Mediterranean Sea). An acceptable correlation between enzyme-linked immunosorbent assay and gas chromatography with nitrogen-phosphorus detection was observed, thus analysis of Irgarol 1051 can be performed by either one of the methods. In this work, further confirmation of the analyte identity for real samples was accomplished by gas chromatography-electron impact mass spectrometry.

Chromatography, Affinity↗
PubMed1981

Extractive alkylation of prostaglandins.

The simultaneous extraction and esterification of prostaglandins in aqueous solution is described. High yield of esters can be achieved in a one minute reaction time. The specificity of the alkylation can be controlled by the counterion. Thus, a long chain carboxylic acid can be selectively extracted and derivatized in the presence of PGF2 alpha.

6-Ketoprostaglandin F1 alpha↗
PubMed1981

Quantitative determination of nefopam in human plasma, saliva and cerebrospinal fluid by gas-liquid chromatography using a nitrogen-selective detector.

A sensitive and selective gas-liquid chromatographic method for the determination of nefopam in human plasma, saliva and cerebrospinal fluid has been developed. The method includes the selective extraction of nefopam and the internal standard, orphenadrine, from biological fluids by a double extraction procedure. The extracted nefopam and internal standard are analyzed by a gas chromatograph equipped with a 3% OV-17 glass column and a nitrogen-phosphorus flame ionization detector (NPFID) operated in the nitrogen mode. The detector provides the needed high sensitivity and also selectivity due to the inherent characteristics of NPFID to discriminate against non-nitrogen containing materials. Five nanograms nefopam per ml plasma or saliva are routinely quantitated with a 1-ml sample or as little as 2 ng per ml cerebrospinal fluid with a 3-ml sample. The intra-day reproducibilities, expressed as the relative standard deviation, are 5, 2 and 3% at 10, 35 and 75 ng/ml plasma levels, respectively. The accuracies expressed by relative error at these levels are 12, -4 and -2%, respectively. The inter-day reproducibility is demonstrated by the small relative standard, deviation, 2%, of the slopes from ten plasma standard curves run on ten different days. In various clinical studies in humans the method has been successfully applied to the study of single-dose pharmacokinetics of nefopam and the monitoring of nefopam concentrations in saliva and cerebrospinal fluids.

Gas Chromatography-Mass Spectrometry↗