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At least 217 records · Page 12Linked to original sources
PubMed1980

[Demonstration and characterization of tumor-associated antigenic components from cell membranes of a UV-induced murine sarcoma using the MEM technic].

Purification of tumour-associated antigenic material from the ascites sarcoma cells was attempted by extraction with 3 M KCl and SDS-polyacrylamide gel electrophoresis (SDS-PAGE). The antigenic activity was assayed in the macrophage-electrophoretic-mobility (MEM) test. Extraction of whole tumour cells with 3 M KCl results in preparations with low antigenic activity which on SDS-PAGE show a very heterogenous composition of more than 20 protein bands. On comparison of the antigenic activity of different subcellular fractions obtained by differential centrifugation of the homogenate, the antigenic activity could be alloted to the cell membrane fraction. With this cell membrane fraction, three extraction media -- 3 M KCl, 2% Triton X-100, and 5% sodium cholate -- were tested for their ability to selectively extract the antigenic membrane proteins. The Triton X-100 treatment solubilized the greatest amount of membrane protein. Both Triton X-100 and sodium cholate, however, produced very heterogeneous protein extracts. In contrast, 3 M KCl selectively extracted three membrane components: a glycoprotein of high molecular weight and two low-molecular-weight carbohydrate-free proteins. Removal of the KCl in the presence of Triton X-100 precipitates the carbohydrate-free proteins, while the glycoprotein remains in solution. Testing the components of the KCl-extracts in the MEM-test after isolation by preparative SDS-PAGE revealed antigenic activity only with the glycoprotein component.

Animals↗
PubMed1979

Kinetics and cell killing in dividing and nondividing leukemic cells in vitro and in vivo by natural splenic cytotoxic factor.

Ultrafiltered splenic extracts (30,000-50,000 daltons) were specifically cytotoxic in crowded cultures of murine leukemic lymphoblasts but were only inhibitory toward normal lymphocytes or sparse cultures of leukemic cells. This expression of cytotoxicity was quantitated by (i) vital dye exclusion, (ii) cytochemical metods, and (iii) the increased survival time of mice injected with L-1210 leukemic cells incubated in vitro with splenic extract. Selective cytotoxicity of splenic extract was not due to medium depletion or to complement-mediated cytolysis and could not be replicated using similar extracts of other lymphoid and nonlymphoid tissues. The selective effect of splenic extract on leukemic cells was characterized by the progressive shedding of cytochemically demonstrable RNA and the corresponding inhibition of 3H-uridine and 3H-thymidine incorporation. The comparison of progressive and gradual expression of cytotoxicity by splenic extract with the S phase specific inhibitor cytosine arabinoside suggests that the former is cytotoxic against leukemic cells predominantly in the G1 phase of the cell cycle.

Animals↗
PubMed1998

Simultaneous extraction of selected benzodiazepines and benzodiazepine-glucuronides from urine by immunoadsorption.

A rapid and selective cleanup procedure based on immunoadsorption is described for the simultaneous extraction of diazepam and its free or glucuronidated metabolites nordiazepam, temazepam, and oxazepam from urine. The method can also be used for the extraction of lorazepam and lorazepam-glucuronide. Because the samples do not have to be hydrolyzed before extraction, valuable information is preserved. With the exception of lorazepam-glucuronide, recoveries between 86 and 100% were obtained at spiking levels up to 200 ng of benzodiazepine or glucuronide per milliliter of urine. Using methanol/water (90:10, v/v) as an eluent, the immunoadsorber could be used at least 20 times. High-performance liquid chromatograms of urine samples from patients receiving low therapeutic dosages of diazepam or lorazepam are shown to demonstrate the high purity of the extracts.

Anti-Anxiety Agents↗
PubMed1996

Comparison of new solid-phase extraction methods for chromatographic identification of drugs in clinical toxicological analysis.

OBJECTIVES: Newly presented solid-phase extraction methods (Solid Phase Disc Extraction, SPEC-Plus, Multi-Modal, and Solid Phase Micro Extraction, SPME have been checked with respect to their applicability to clinical toxicological analysis. In comparison with conventional liquid/liquid-extraction and a common mixed-phase column technology, their use in general screening and selective extraction methodology is discussed. DESIGN AND METHODS: Recovery studies were performed with urine-based samples including model substances, as well as drugs and metabolites from native urine samples. Chromatographic performance of the resulting extracts is presented in some examples. RESULTS: Liquid/liquid extraction, common mixed-phase column technique and the new SPEC-Plus, Multi-Modal disc extraction method gave the best recoveries with respect to broad-spectrum general screening. The purity of the concentrates was somewhat different, however. Solid-phase C18 and Solid-Phase Micro Extraction methodologies are better suited for selective drug extraction. In SPEC Disc or SPME extraction, the use of solvents is greatly reduced or omitted. Recovery of some volatile substances is enhanced. SPEC discs can be inserted directly into TLC chromatographic plates, SPME fibers into GC injection ports. CONCLUSIONS: The new solid-phase extraction technologies offer advantages in different respects: The mixed-phase disc extraction SPEC 1 Plus AR/MP3 Multi-Modal delivers promising results with respect to broad-spectrum general screening. Solvent consumption is low, throughput times are short, the extracts are clean, and recovery rates are good, comparable, or even higher than with common mixed-phase column techniques. The new SPME extraction method shows benefits in dedicated, selective extraction procedures (e.g., analysis of volatile substances such as amphetamines). Sampling is solvent-free, the handling is easy, and the yields of extraction are good, but only for selected substances. Broad-spectrum general screening still remains problematic with this technique. Further examinations have to be carried out including a larger number of drugs of toxicological relevance. Headspace sampling by SPME offers a good alternative to conventional mechanized sampling in the analysis of volatile substances in biological samples, omitting the need for expensive instrumentation.

Blood Chemical Analysis↗
PubMed1996

Remarkably Selective Ag(+) Extraction and Transport by Thiolariat Ethers.

Synthesis and metal binding properties of thiolariat ethers, where a sulfide side chain is introduced into a framework of a crown ether, have been performed. Remarkably high Ag(+) selectivity among heavy metal ions was observed in solvent extraction and transport across a liquid membrane using thiolariat ethers with a 15-crown-5 ring as carriers. Thiolariat ethers with a 12-crown-4 or a 18-crown-6 do not exhibit such a high Ag(+) selectivity. The former binds metal ions weakly, and the latter recognizes Pb(2+) as well as Ag(+). The corresponding oxygen analogs, i.e. lariat ethers, do not show Ag(+) selectivity. The Ag(+) binding strength of the sulfoxide and sulfone analogs is much lower than that of thiolariat ethers. Thiolariat ethers with a benzocrown framework containing a sulfide chain at the 4 position of the benzene nucleus showed very low affinity to Ag(+). Extractability and transport ability using various thiolariat ether derivatives strongly suggested that this high Ag(+) selectivity is a result of the synergistic coordination of the ring oxygen and the sulfur atom of the thiolariat ether. NMR chemical shifts of protons and carbons in the proximity of the sulfur atom of the thiolariat ether were changed significantly in accordance with the synergistic coordination described above. 1:1 Complexation between a thiolariat ether and Ag(+) were supported by a Job plot using the chemical shift of the methylene protons adjacent to the sulfur atom.

Journal Article↗
PubMed1974

Replication of colicin E1 plasmid DNA in cell extracts. II. Selective synthesis of early replicative intermediates.

The major products of colicin E1 plasmid DNA synthesis in cell extracts are completely replicated molecules and a class of molecules containing newly synthesized small DNA fragments. The addition of 10% glycerol and/or 2 mM spermidine to extracts blocks synthesis of completely replicated molecules while enhancing synthesis of molecules containing newly synthesized DNA fragments. The latter molecules, which contain on the average two DNA fragments of approximately 6 S, are early replicative intermediates for synthesis of completely replicated molecules. Synthesis of the intermediates is sensitive to rifampicin and depends on RNA synthesis. RNA components are linked to the 6S DNA molecules.

Centrifugation, Density Gradient↗
PubMed1993

Heat treatment of nuclear extract alters selection of the 3' splice site in pre-mRNA splicing.

We investigated in vitro splicing reaction using an artificially created mRNA precursor containing a single 5' splice site and tandemly duplicated 3' splice sites. We found that the 3' splice site proximal to the 5' splice site is predominantly used under the standard splicing conditions. However, when the preheated nuclear extract was employed, the intermediate in which the distal 3' splice site was selected accumulated exclusively. This shows that heat treatment of nuclear extract abolishes the activity involved in the selection of the 3' splice sites that are in cis-competition for the common 5' splice site. The results presented here suggest the presence of a factor(s) required for the selection of the proximal 3' splice site.

Base Sequence↗
PubMed2005

Discovery, clinical development, and therapeutic uses of bisphosphonates.

OBJECTIVE: To review the literature concerning the history, development, and therapeutic uses of bisphosphonates. DATA SOURCES: English-language articles were identified through a search of MEDLINE (through December 2004) using the key word bisphosphonate. Reference lists of pivotal studies, reviews, and full prescribing information for the approved agents were also examined. STUDY SELECTION AND DATA EXTRACTION: Selected studies included those that discussed the discovery and initial applications of bisphosphonates, as well as their historical development, pharmacokinetic and pharmacodynamic properties, and current therapeutic uses. DATA SYNTHESIS: Bisphosphonates structurally resemble pyrophosphates (naturally occurring polyphosphates) and have demonstrated similar physicochemical effects to pyrophosphates. In addition, bisphosphonates reduce bone turnover and resist hydrolysis when administered orally. The information gained from initial work with etidronate generated a considerable scientific effort to design new and more effective bisphosphonates. The PCP moiety in the general bisphosphonate structure is essential for binding to hydroxyapatite and allows for a number of chemical variations by changing the 2 lateral side chains (designated R(1) and R(2)). The R(1) side chain determines binding affinity to hydroxyapatite, and the R(2) side chain determines antiresorptive potency. Accordingly, each bisphosphonate has its own characteristic profile of activity. CONCLUSIONS: The bisphosphonates reduce bone turnover, increase bone mass, and decrease fracture risk and therefore have a significant place in the management of skeletal disorders including osteoporosis, Paget's disease, bone metastases, osteogenesis imperfecta, and heterotopic ossification.

Bone Diseases↗
PubMed2005

Interferon gamma-1b in the treatment of idiopathic pulmonary fibrosis.

OBJECTIVE: To examine the clinical aspects of idiopathic pulmonary fibrosis (IPF) and the efficacy and safety of interferon gamma-1b (IFNgamma-1b) in its treatment. DATA SOURCES: Epidemiologic, preclinical, and clinical studies published in the English language were identified by a MEDLINE search (1966-January 2005) using the search terms idiopathic pulmonary fibrosis, cryptogenic fibrosing alveolitis, and interferon. Additional citations were identified from the reference lists of related publications. STUDY SELECTION AND DATA EXTRACTION: Selected preclinical studies describing the pathophysiologic basis for IFNgamma-1b therapy and all clinical studies were included. Additional trials describing other treatment modalities and the determinants of response to therapy in patients with IPF were also reviewed. DATA SYNTHESIS: IFNgamma-1b targets the fibrotic rather than inflammatory processes of IPF. The efficacy of IFNgamma-1b in patients with IPF is inconsistent with regard to changes in pulmonary function and mortality, although a modest survival benefit was observed in the largest clinical trial. Adverse events related to IFNgamma-1b are frequent although transient. Several cases of respiratory failure occurring subsequent to the administration of IFNgamma-1b are documented. CONCLUSIONS: To date, although trials suggest that earlier-stage IPF may be responsive to IFNgamma-1b, study results overall are inconsistent; further investigation is needed.

Clinical Trials as Topic↗
PubMedDate not supplied

Evaluation of the allergenicity of spore and mycelia extracts of Pisolithus tinctorius.

The antigenic and allergenic chemical analysis of spore and mycelia extracts of Pisolithus tinctorius was carried out. The spores were collected from basidiocarps in plantations of Eucalyptus spp and the mycelia from culture in MNM medium. With basis on the fungus growth curve, the mycelia masses were obtained after 10, 20, 30, and 40 days of incubation, which correspond, respectively, to the beginning, middle and end of the log phase, and beginning of the decline phase. The mycelia masses, together with the spores, were submitted to the action of three extractors (Coca, Tris-HCl, and ammonium bicarbonate). The contents of carbohydrates and proteins were determined. The SDS-PAGE electrophoretical analysis revealed separate fractions in these extracts, besides common fractions, in function of cultivation time and extraction methods. The selected extracts for the allergic tests were the ones with the highest number of fractions. The prick-tests were conducted in 374 patients--rural workers, eucalyptus plantation workers, and college students. The positivity to the "prick test" with the antigenic extract of P. tinctorius was, respectively, 3.78%, 28.20% and 6.40%. Most prick-test positive patients (82.75%) also presented symptoms of respiratory allergy (asthma and rhinitis). There was no reactivity difference when the spore and mycelia extracts were employed. The analysis of the positive patients' sera revealed the presence of IgE specific to the P. tinctorius antigens. Since Pisolithus tinctorius is found as mycorrhiza of Eucalyptus spp, and this plant is used in reforestation in most countries, the importance of that fungus should be regarded as a possible cause of respiratory allergies, especially in occupationally exposed workers.

Allergens↗
PubMedDate not supplied

Validation of procedures to quantify nonextractable polycyclic aromatic hydrocarbon residues in soil.

This study was conducted to optimize butanol solvent shake extraction, dichloromethane soxtec extraction, and methanolic saponification extraction for the selective extraction of aged polycyclic aromatic hydrocarbons from soil. Extraction kinetics for these methods was established to determine the optimal time necessary to achieve exhaustive compound extraction. This resulted in times of 12, 6, and 5 h, respectively, for butanol, dichloromethane, and saponification, to extract polycyclic aromatic hydrocarbons from previously spiked, then aged soil. Increasing the soil mass to butanol volume ratio reduced the proportion of polycyclic aromatic hydrocarbon extracted by butanol, highlighting the importance of determining and maintaining a constant soil to solvent ratio for comparative purposes. Drying soil samples before dichloromethane soxtec extraction reduced by 30 to 76% the amount of polycyclic aromatic hydrocarbons extracted. The effect of sample drying is discussed with relevance to enhancing the formation of nonextractable compounds in soil and compound losses previously assumed by volatilization. The optimized extraction procedures provided low variability with relative standard deviations < or = 5.2% for analysis of multiple replicates. The results obtained by the optimized procedures provided equivalent or improved reproducibility to those obtained by other methods reported in the literature.

Environmental Monitoring↗
PubMed1992

Small-incision manual extracapsular cataract extraction using selective hydrodissection.

Hydrodissection is a technique in which balanced salt solution is injected through a cannula into various layers of a cataractous lens to separate the lens lamella in a nonspecific location. Selective hydrodissection allows separation of the lens lamella at different desired anatomical layers. The technique allows the smallest possible nucleus, ie, the hard-core nucleus, to be hydroexpressed as a separate entity, requiring, correspondingly, a relatively small capsulorhexis and limbal incision. Then, in a second maneuver, the epinucleus, which engulfs the hardcore nucleus to form the adult nucleus, also can be aspirated or hydroexpressed as a whole. Selective hydrodissection permits scleral incision and stitchless surgery in planned extracapsular cataract extraction and also may serve as an intermediate step for surgeons who wish to convert to or learn phacoemulsification techniques.

Cataract Extraction↗
PubMed1978

[Extraction of membrane proteins in low ionic strengths].

Hemoglobin and the low molecular weight proteins 8 and 9 are extracted from ghosts during low ionic washing after the hypotonic hemolysis of erythrocytes. Furthermore, a loss of the proteins 4.5 and 7 was observed. The protein patterns of ghosts after isotonic hemolysis by freezing and thawing resemble the ghost protein patterns after hypotonic hemolysis and incomplete deprivation of Hb. Many if not all membrane proteins are eluted by repeated incubations of the ghosts in solutions of low ionic strength in the presence of EDTA. The spectrins, the proteins 5, 4.5, 7 and residual Hb are extracted preferentially. A selective extraction of the spectrins and the protein 5 is not detectable under these conditions. Often the spectrin bands are subdivided following low ionic incubation.

Edetic Acid↗
PubMedDate not supplied

Isolation of lipid and 2-alkylcyclobutanones from irradiated foods by supercritical fluid extraction.

The 2-alkylcyclobutanone method was adopted as a European Standard (EN1785) and MAFF Validated Method (MAFF V37) in 1996 for the detection of irradiated food containing fat. As the method requires a relatively long period (ca 2 days) of time for extraction of the 2-alkylcyclobutanones from a foodstuff, a means was sought to increase the speed at which these irradiation markers could be isolated while at the same time decreasing the amount of organic solvents required. Thus, the technique of supercritical fluid extraction (SFE) was investigated. Results showed that SFE can be used for the rapid extraction (60 min) of lipid from irradiated foods such as chicken, pork, liquid whole egg, ground beef, and from the seeds of irradiated mango and papaya with only 10 mL n-hexane being necessary for collection of the extracted sample. A method was also developed whereby the 2-alkylcyclobutanones can be selectively extracted from irradiated foods without prior extraction of the lipid. The sample extract, in 10 mL n-hexane, is purified through a Florisil SPE cartridge which is washed with 10 mL n-hexane and the 2-alkylcyclobutanones eluted with 10 mL 2% diethyl ether in n-hexane before analysis by gas chromatography/mass spectrometry. 2-Dodecylcyclobutanone and 2-tetradecylcyclobutanone were selectively extracted from irradiated chicken meat, liquid whole egg, ground beef, and mango as well as from beef burgers and baked products containing irradiated ground beef and liquid whole egg, respectively. Using this method, samples can be analyzed for irradiation treatment within 6 h as opposed to the 2-day period required for the EN1785/MAFF V37 validated method.

Animals↗
PubMed1995

Saiboku-To, a herbal extract mixture, selectively inhibits 5-lipoxygenase activity in leukotriene synthesis in rat basophilic leukemia-1 cells.

Saiboku-To, a mixture of extracts from 10 medicinal herbs, has been used for the treatment of bronchial asthma in Japan. Inhibitory action of this drug on arachidonate 5-lipoxygenase (5-LO) metabolism in rat basophilic leukemia cells (RBL-1 cells) was examined. Saiboku-To significantly inhibited calcium ionophore-stimulated synthesis of cysteinyl leukotrienes (cLTs) and leukotriene B4 (LTB4). Inhibition appeared 10 min after addition of the substance and reached a maximal value after 3 h. Saiboku-To did not inhibit the release of [3H]arachidonic acid (AA) from cell membrane by calcium ionophore stimulation, or the production of cLTs and LTB4 when LTA4-free acid was used as the substrate. However, it significantly inhibited the production of cLTs and LTB4 when free AA was used as the substrate. The production of thromboxane A2 (TXA2). a cyclooxygenase metabolite, was not inhibited when AA was used as the substrate in cell free study. These results indicate that Saiboku-To selectively inhibits 5-LO activity in the metabolic pathway of AA.

Animals↗
PubMed1998

Epitope mapping of monoclonal antibodies by mass spectrometry: identification of protein antigens in complex biological systems.

We describe the application of immunoaffinity extraction and mass spectrometry to the analysis of Ty1 Gag protein in lysates of Saccharomyces cerevisiae. A magnetic bead-conjugated monoclonal antibody was used to achieve selective extraction, the specificity of which was established by matrix-assisted laser desorption/ionization mass spectrometric (MS) analysis of an extract of the lysate of cells overexpressing the Ty1 Gag protein. MS analysis of similar extracts of lysates following tryptic hydrolysis confirmed selective extraction of the epitope-containing peptide fragment. Sufficient sensitivity was achieved to allow the application of this approach to the analysis of lysates of wild-type cells. Furthermore, the sequence of the epitope-containing peptide was confirmed by electrospray-tandem MS. To our knowledge, this constitutes the first report of the application of immunoaffinity extraction and tandem MS analysis to the characterization of an antigen recovered from a complex cellular system.

Antibodies, Monoclonal↗