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Results for “selective extraction”

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At least 163 records · Page 9Linked to original sources
PubMed1978

A new rapid method for selective extraction of RNA from fixed mammalian tissues.

Treatment of formalin-fixed mammalian tissues with concentrated or 50% phosphoric acid at 5 degrees C for 20 and 50 min. respectively reveals complete extraction of RNA as judged by methyl green followed by staining with pyronin. This procedure also causes depolymerisation of DNA as indicated by the red staining of the nuclei. Sections treated with concentrated phosphoric acid at 5 degrees C for 30 min. causes disruption of the double helical structure of DNA what results in the depression of the pyronin staining. Similarly treated sections show Feulgen positive nuclei. Treatment of sections in 25 % phosphoric acid at 60 degrees C for 15 min. followed by staining with methyl green and pyronin show red nuclei, nucleoli and the cytoplasm. This indicates that extraction of RNA is only possible in cold and not at elevated temperature.

Animals↗
PubMed1996

Electrophoretic analysis of protein selectively extracted with chaotropic agents from membranes of rat sperm.

Sperm from rat cauda epididymis was washed, sonicated and centrifuged to obtain fractions sedimenting at 600 x g for 5 min, 27.000 x g for 5 min, and 100.000 x g for 40 min. All fractions were observed with the electron microscopy and assayed for cytochrome c oxidase activity. The 100.000 x g fraction contained only small membranous vesicles and less than 0.5% of the total enzymatic activity. This fraction was considered to represent sperm plasmalemma and it was extracted with Tris-HCl buffer before treating it with one of the following chemicals: acetate buffer, pH: 4.5; 0.6 M KCl; bicarbonate buffer, pH 11.0; Triton X-100, and Sodium Dodecyl Sulfate (SDS). After centrifuging, the residual sediments were solubilized in hot 2% SDS. The extracts and the solubilized sediments (hot SDS) were analyzed in SDS-PAGE. The extracts obtained with the first three chemicals contained 11,9, and 25% of total proteins respectively. The bicarbonate buffer solubilized 45%, and the detergents 55% and 65% respectively. A total of 30 bands were seen in the extracts and sediments. Acid pH extracted a low number of bands of high mobility and low molecular weight. Instead, the KCl and bicarbonate buffer, extracted a great number of bands over a wide range of molecular weights (23, 38.5, 55, 100, and 140 KD). The detergents had similar effects: both solubilized four new bands. In residual sediments there were no new proteins and the bands corresponded to those extracted with the detergents, but they varied in staining intensity. According to the results obtained with the mild chaotropic agents of 0.6 M KCl and bicarbonate buffer, 50% of the mass of membraneous proteins may be peripheric. Proteins partially extracted with the detergents were also found in the residual sediment, and they may constitute the skeleton of sperm membrane.

Animals↗
PubMed1977

Selective extraction of membrane-bound proteins by phospholipid vesicles.

Extraction of membrane proteins from erythrocytes into sonicated phosphatidylcholine vesicles is described. In a process involving phospholipid and neutral lipid exchange, cell membrane proteins associate with the vesicles and can be separated from the cells by centrifugation. The protein transfer appears to be reversible; phospholipid vesicles mediate the delivery of small amounts of previously extracted protein into cell membranes. Prior to extraction, all but one of the proteins are accessible to lactoperoxidase iodination, and lipid analysis indicates that primarily the outer monolayer of the cell is involved in phospholipid exchange. Among the extracted proteins is acetylcholinesterase which is removed much more efficiently by this procedure than by concentrated salt solutions. The most abundant proteins of the erythrocyte membrane are not represented in the vesicle extract.

Acetylcholinesterase↗
PubMed2006

Solid phase extraction method for selective determination of Pb(II) in water samples using 4-(4-methoxybenzylidenimine) thiophenole.

A sensitive and selective extractive preconcentration procedure for the determination of traces of lead in water samples has been developed. An alumina-sodium dodecyl sulfate (SDS) coated modified with 4-(4-methoxybenzylidenimine) thiophenole (MBITP) was used for preconcentration and determination of Pb(II) by flame atomic absorption spectrometry. Lead was adsorbed quantitatively on modified column due to its complexation with MBITP and quantitatively eluted using 5 mL 1 mol L(-1) nitric acid in acetone. The effects of parameters such as pH, amount of solid phase, amount of MBITP, flow rate, type and concentration of eluting agent were examined. The effect of interfering ions on the determination of Pb(II) was also investigated. The response of proposed method is linear in the concentration range 0.05-1.2 microg mL(-1) of Pb(II). The limit of detections (3S.D.(b)/m, n=4) and relative standard deviations (n=11) are 1.6 ng mL(-1) and 0.9%, respectively. The presented procedure was successfully applied for determination of lead content in real samples such as river, spring, waste and drinking water.

Benzene Derivatives↗
PubMed1998

Selecting allergenic extracts for inhalant allergy testing and immunotherapy.

The proper selection of allergen extracts is important in maintaining an efficient allergy practice. This article discusses pollen extract selection. The selection of tree, grass, and weed pollen extracts depends very much on where the clinician's practice is located. The floral zones of the continental United States are discussed, and several specific lists of pollen extracts are provided. Mold spore, dust, dust mite, and cat allergen selection are much less geography specific, yet they have their own complexity.

Allergens↗
PubMed2001

An altered Pseudomonas diversity is recovered from soil by using nutrient-poor Pseudomonas-selective soil extract media.

We designed five Pseudomonas-selective soil extract NAA media containing the selective properties of trimethoprim and sodium lauroyl sarcosine and 0 to 100% of the amount of Casamino Acids used in the classical Pseudomonas-selective Gould's S1 medium. All of the isolates were confirmed to be Pseudomonas by a Pseudomonas-specific OprF antibody and a Pseudomonas-specific PCR targeting 16S ribosomal DNA. The Pseudomonas isolates were characterized by classical physiological tests, repetitive extragenic palindromic-PCR, Fourier transform infrared spectroscopy, and carbon source utilization patterns. Several of these analyses showed that the amount of Casamino Acids significantly influenced the diversity of the recovered Pseudomonas isolates. Furthermore, the data suggested that specific Pseudomonas subpopulations were represented on the nutrient-poor media. The NAA 1:100 medium, containing ca. 15 mg of organic carbon per liter, consistently gave significantly higher Pseudomonas CFU counts than Gould's S1 when tested on four Danish soils. NAA 1:100 may, therefore, be a better medium than Gould's S1 for enumeration and isolation of Pseudomonas from the low-nutrient soil environment.

Bacterial Typing Techniques↗
PubMed1997

Characterization of hydroperoxides and carbonyl compounds obtained by lipoxygenase extracts of selected microorganisms.

Partially purified lipoxygenase (LOX) extracts were obtained from Fusarium proliferatum, Fusarium oxysporum, Chlorella pyrenoidosa, and Saccharomyces cerevisiae; the enzymatic extract of F. proliferatum showed the highest LOX activity while those of F. oxysporum and S. cerevisiae demonstrated only 27.8 and 16.5% of the activity at pH 8.0, and 61.2 and 9.7% of the enzyme activity at pH 10.0, respectively. The lowest LOX activity was that in the C. pyrenoidosa extract. The microbial enzymatic preparations were assayed with linoleic acid as substrate, which was bioconverted into 9- and 13-hydroperoxides (HPODEs) by all four extracts; in addition, the LOX activity in the F. oxysporum extract produced the 10- and 12-HPODEs from linoleic acid while that of the C. pyrenoidosa extract produced only the 10-HPODE. When assayed with the 9- and 13-HPODEs as substrates, the selected microbial extracts had secondary enzyme activities, one of which produced hexanal. The highest hexanal-producing activity was 1.51 and 1.39 nmol hexanol/mg protein/min in the F. proliferatum and C. pyrenoidosa extracts, respectively, while those of F. oxysporum and S. cerevisiae had approximately 15% of the HPODE-cleaving enzyme activity. The C. pyrenoidosa extract had the highest proportion of pentanone, which was produced at only one-fourth the concentration by the HPODE-cleaving enzyme activity in the three other microbial enzymatic extracts.

Chlorella↗
PubMed1983

Development of a standardized analysis strategy for basic drugs using ion-pair extraction and high-performance liquid chromatography - I. Philosophy and selection of extraction technique.

The first of a series of papers on the development of a standardized analysis strategy for basic drugs explains the possible advantages and philosophy of the strategy. The scheme uses ion-pair extraction with direct injection of the extracts into an HPLC system emanating, from two previously-selected systems. The extraction efficiency of sodium-n-octylsulphate as the ion-pairing reagent is compared with that of di(2-ethylhexyl) phosphoric acid (previously shown to be generally applicable to the extraction of basic drugs). Direct injection of the ion-pair extracts into an HPLC system is possible because retention behaviour is independent of whether the basic drugs are injected as an ion-pair or as a base.

Journal Article↗
PubMed2000

Selective chemical extraction and grainsize normalisation for environmental assessment of anoxic sediments: validation of an integrated procedure.

An integrated selective extraction and size normalisation procedure for use in metal partitioning and diagenetic studies of anoxic sediments and soils is presented. Data obtained by this procedure can readily be combined with other primary data (e.g. sulfur concentrations, carbonate concentrations, cation exchange capacity, etc.) and derived parameters (e.g. degrees of pyritisation and sulfidisation) that enhance interpretation of the behaviour of trace metals in anoxic sediments. Achieving size normalisation during extraction, allows direct comparison of sediments from dissimilar sedimentary environments, and simplifies assessment of the processes that determine whether a sediment is a source of or a sink for trace metals. Aspects of a study of trace metals in sediments from the Brisbane River estuary, Australia, are used to illustrate applications of the integrated procedure.

Environment↗
PubMed2002

Elimination of polymer interference in chromatographic analysis of estradiol degradation products in a transdermal drug delivery formulation by proper selection of extraction solvents.

This article describes the proper selection of extraction solvents to eliminate interference from a polymer matrix to the quantitation of estradiol degradation products in a transdermal formulation by reversed-phase liquid chromatography. The separation is performed by gradient elution with acetonitrile and water as the mobile phase on Inertsil ODS columns. Severe band distortion and insufficient recovery are observed for two geometric degradation products (or impurities) when the sample is prepared by acetonitrile. It is anticipated that the poor resolution and recovery are caused by multiple retention processes due to the reversible binding of degradation products to the polymer matrix (or the impurity-polymer interaction). This interaction is eliminated by adding formamide, a solvent that possesses similar properties to the matrix, in the extraction solvent. It is believed that the favorable interaction between formamide and the polymer matrix releases the impurity molecules, and they can then be separated by a single retention mode. It has been confirmed experimentally that the use of formamide in the extraction solvent not only sharpens the peaks tremendously, but also recovers the degradation products completely.

Administration, Cutaneous↗