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At least 73 records · Page 4Linked to original sources
PubMed2004

Histopathologic evaluation of tissue extracted on the radiofrequency probe after ablation of liver tumors: preliminary findings.

OBJECTIVE: Our aim was to evaluate the histologic characteristics of tissue extracted on the probe immediately after radiofrequency ablation of malignant tumors in the liver. MATERIALS AND METHODS: From April to December 2001, 20 radiofrequency ablations were performed in 19 patients with primary (n = 17) and metastatic (n = 2) liver masses. Track ablation according to device protocol was performed after each ablation. Tissue was adherent to the probe after all radiofrequency probe passes. All pieces of tissue found on the probe were collected and preserved in formalin. RESULTS: Tissue was examined by the study pathologist. In eight (40%) of 20 specimens, coagulation necrosis was present. In five (25%) of 20 specimens, possibly nonviable tissue was extracted, although some cell characteristics were identified. In seven (35%) of 20 specimens with hepatocellular carcinoma, possibly viable tissue was found. Five specimens were identified as hepatocellular carcinoma, and two, as cirrhotic nodules. CONCLUSION: Histopathologic evaluation of the tissue extracted on the radiofrequency probe after ablation is feasible. This study showed that coagulation necrosis was clearly present in at least 40% of the patients, which proves that nonviable tissue can be seen immediately after ablation. Whether this pathologic finding has prognostic value is not known.

Adult↗
PubMed1982

Immunodetection of insulin after transfer from gels to nitrocellulose filters. A method of analysis in tissue extracts.

This report describes the development of a rapid method for detection of nanogram quantities of insulin in tissue extracts after electrophoresis. Following electrophoresis the proteins are transferred to nitro-cellulose filters and treated with a photoreactive crosslinking agent. Filter bound insulin is detected by antiinsulin antibody and 125I-protein A, followed by autoradiography. The photoaffinity crosslinking is simple, rapid, and stable, and does not require reactive binding sites on derivatized paper. Under these conditions insulin maintains its immunoreactivity yet can be washed extensively to reduce nonspecific background; as little as 10 ng can be visualized. The method has proven to be useful for rapid analysis of qualitative as well as quantitative differences in immunoreactive insulin in tissue extracts.

Animals↗
PubMed1982

Minimizing Nitrate Reduction during Kjeldahl Digestion of Plant Tissue Extracts and Stem Exudates : APPLICATION TO N STUDIES.

From 10 to 60% of the nitrate present in plant tissue extracts and stem exudates of corn (Zea mays L.) was found to be reduced during Kjeldahl digestion, even in the absence of added reducing agents. This reduction is of particular concern in [(15)N]nitrate assimilation studies, because it results in an overestimate of nitrate reduction. To overcome this problem, a method was developed for removing nitrate prior to Kjeldahl digestion, thereby preventing nitrate reduction. The procedure utilizes hydrogen peroxide for partial oxidation of organic matter in order to minimize the nitration of organic compounds. The free nitrates are then volatilized as nitric acid from concentrated sulfuric acid at 95 degrees C. When the proposed method was used as a pretreatment to Kjeldahl digestion, less than 0.5% of the applied nitrate was recovered in the reduced nitrogen fraction of plant tissue extracts and stem exudates.

Journal Article↗
PubMed2005

Assessment of phosphodiesterase isozyme contribution in cell and tissue extracts.

Cyclic nucleotide phosphodiesterases (PDEs), which are ubiquitously distributed in mammalian tissues, play a major role in cell signaling by hydrolyzing cyclic adenosine 3',5'-monophosphate and cyclic guanosine 3',5'-monophosphate. Owing to their diversity, which allows specific distribution at the cellular and subcellular level, PDEs can selectively regulate various cellular functions. We present here a convenient and sensitive radioenzymatic assay for characterizing and determining the contribution of the various PDE families in cell and tissue extracts. This assay is based on the knowledge and use of chosen PDE family-specific inhibitors in order to determine the distinct PDE isozyme contribution in the overall cyclic nucleotide hydrolyzing activity. It can be used to characterize total, cytosolic, and membrane-associated PDE activities, as well as PDEs associated with purified subcellular structures. This approach is useful for comparing data of control and treated extracts and is therefore quite valuable for viewing the PDE status in different physiopathological conditions.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1992

Homogeneous trinder-coupled assay for the determination of glucose-6-phosphatase activity in tissue extracts.

We describe an automated, homogeneous, glucose oxidase-coupled method for the determination of glucose-6-phosphatase activity in tissue extracts. The method is based on measurement of the rate of glucose formation by the Trinder reaction, in which the end product is a quinoneimine dye which absorbs maximally at 505 nm and has a molar extinction coefficient of 5700. The incubation mixture contains 20 microL of tissue extract, 25 microL of 0.5 M phosphate buffer, pH 7.0, 175 microL of Trinder/glucose-6-phosphate reagent, and 30 microL of distilled water. After a delay period of 15 min, to exhaust any glucose endogenously present in the extract, glucose production from glucose-6-phosphate is monitored at 505 nm for 5 min in a centrifugal analyzer. The Km was 13 mM over a 10-fold range in glucose-6-phosphate concentration and the reaction was linear up to about 250 U/L. Within-run CV of the assay at activities of 48 and 190 U/L ranged between 2.5-5.0%. The between-run CV at 190 U/L was 5.1%.

Animals↗
PubMed1989

A simple enzymic method to separate [3H]inositol 1,4,5- and 1,3,4-trisphosphate isomers in tissue extracts.

A novel method to separate [3H]Ins(1,4,5)P3 and [3H]Ins(1,3,4)P3 in tissue extracts is described. It is based on the selective metabolism of Ins(1,3,4)P3 by a crude cerebral supernatant in a Mg2+-free buffer followed by separation of [3H]inositol trisphosphates using conventional anion-exchange chromatography. Evaluation of the assay was performed using [3H]Ins(1,3,4)P3 standards and tissue extracts containing different proportions of [3H]Ins(1,4,5)P3 and [3H]Ins(1,3,4)P3. Parallel h.p.l.c. separations of extracts established the selective and complete metabolism of [3H]Ins(1,3,4)P3 under the above conditions and demonstrated that the enzymic method provides an accurate estimate of the trisphosphate isomers in rat cerebral cortex, parotid gland and bovine tracheal smooth muscle.

Animals↗
PubMed1994

Identification of ethanolamine in rat and gerbil brain tissue extracts by NMR spectroscopy.

Some NMR resonances which have previously been observed but not identified in mammalian brain tissue extracts have been shown to arise from ethanolamine. This conclusion is drawn from a systematic study of the perchloric acid extracts of rodent brain tissue in which several NMR experiments were used to assign the peaks unambiguously. The extraction procedure used in this work gave samples with highly reproducible spectra, and ethanolamine was observed in all our extract samples. A localized increase in the concentration of ethanolamine was seen in the spectra of extracts produced from a cerebral infarct induced by occlusion of the middle cerebral artery in the rat.

Animals↗
PubMed2003

Guanosine deaminase in human serum and tissue extracts--a reappraisal of the products.

Of the human salvage enzymes that deaminate ribonucleosides, two--cytidine deaminase and adenosine deaminase--have been found particularly useful for diagnostic purposes. In humans, no enzymes are present that can directly deaminate the bases of these ribonucleosides. Indeed, the only enzyme present that can directly deaminate a base is guanine deaminase, and the diagnostic usefulness of this enzyme has been well documented. The aim of this study is to identify the origin of the ammonia formed when human sera and tissue extracts are incubated with buffered guanosine, and to clarify whether the ammonia comes from the deamination of guanosine by guanosine deaminase or is produced as a result of deamination of guanine formed as a breakdown product of guanosine by purine nucleoside phosphorylase (PNP). Apparent deamination of guanosine by guanosine deaminase in human sera and tissue extracts was found to be due to two enzymes acting in tandem when the products of the reaction were examined by HPLC. The ribose was first removed from guanosine by PNP to form guanine, which was then deaminated to xanthine by guanine deaminase.

Ammonium Sulfate↗
PubMed1987

Study of metabolism of psychotomimetic indolealkylamines by rat tissue extracts using liquid chromatography.

The use of a series of liquid chromatographic techniques involving cation-exchange, reverse-phase and normal-phase chromatography has permitted the separation and characterisation of a number of metabolites of the psychotomimetic indolealkylamines N,N-dimethyltryptamine and 5-methoxy-N,N-dimethyltryptamine which were isolated following incubation of these compounds with rat tissue extracts. In liver, kidney and brain tissue extracts the routes of metabolism identified included oxidative deamination, N-demethylation, O-demethylation and N-oxidation. The quantitative significance of individual routes of metabolism in these tissues was assessed using N,N-dimethyltryptamine as a substrate.

Animals↗
PubMed1995

Detection and characterization of the prostate-specific membrane antigen (PSMA) in tissue extracts and body fluids.

The prostate-specific membrane antigen (PSMA) glycoprotein is recognized by the monoclonal antibody (MAb) 7E11-C5.3 as a predominant 100 kDa and minor 180 kDa component in LNCaP cell line extracts and its expression has been shown by immunohistochemistry to be highly restricted to prostate epithelium. The aim of the present study was to utilize Western blot analysis to determine if PSMA could be detected in human tissue extracts and body fluids and if so, which molecular forms were present. PSMA was detected as 120 and 200 kDa bands in normal, benign and malignant prostate tissues and seminal plasma. Further analysis demonstrated that the larger molecular form of PSMA may be a dimer of the lower m.w. species. The PSMA glycoprotein was not detected in the majority of non-prostate tissue extracts examined except for a low yet significant amount in normal salivary gland, brain and small intestine, suggesting that PSMA may not be as prostate-specific as originally thought. Since the prostate-specific antigen (PSA) has been shown to be maximally shed into the serum in high-grade and metastatic prostate carcinomas, it was surprising that PSMA could not be detected in serum by Western blot analysis even in patients with actively progressive metastatic disease. Second generation antibodies generated against different epitopes may be required to determine if PSMA is shed into serum. Our results support the hypothesis that PSMA is a novel prostate biomarker.

Animals↗
PubMed1982

Growth from regenerating goldfish retinal cultures in the absence of serum or hormonal supplements: tissue extract effects.

The minimal requirements for the regeneration of optic nerve fibers in vitro were established in a serum-free retinal explant preparation. This serum-free preparation was developed as a prerequisite for testing the growth-promoting activity of tissue extracts prepared from the primary target of regenerating fibers. Explants taken from goldfish retinas 14 days after a prior optic nerve crush were capable of long-term survival and regenerated neurite outgrowth without serum or hormonal supplements. Serum-free conditions for explant outgrowth required only a basic Leibovitz (L-15) media containing 0.6% methyl cellulose (MC). Explants were also capable of neurite outgrowth in L-15 media alone when culture dishes were preplated with MC. MC treatment permitted both the regeneration of neurites in serum-free L-15 and a significant increase in the rate and extent of neurite outgrowth when combined with 10% fetal calf serum (FCS). Explants grown in L-15 with both MC and FCS produced a 2.5-fold increase in the length of neurite outgrowth over MC alone and a 1.5-fold increase in the length of neurite outgrowth over FCS alone. MC activity which permitted minimal serum-free regeneration and optimal serum supplemented regeneration was determined to be substrate related. Retinas were dissociated to determine if ganglion cells, like the intact explant, were capable of survival and neurite regeneration in serum-free conditions. These cells survived and extended long neurites when grown in L-15 with FCS or with FCS and MC, but they did not survive in serum-free L-15 with MC. The minimal serum-free conditions for explant survival and neurite regeneration were used as a model system to test the growth-promoting activity of crude tissue extracts prepared from the goldfish brain. Extracts prepared from the primary target region, the optic tectum, stimulated a significant 2.5-fold increase in the length of regenerating neurites. The optic tectal extract (OTex) stimulated outgrowth with significantly high specific activity when compared with extracts of identical protein concentrations prepared from the cerebellum (Cex). At a minimal protein concentration of 150 micrograms/ml, the OTex stimulated a 1.5-fold increase in neurite outgrowth above Cex. These results indicated that a serum-free culture preparation had been established for optic nerve regeneration. This culture system has proven to be an extremely sensitive bioassay model without the masking effect of a serum supplement. Serum-free cultures may be used in further studies to determine the role neurotrophic factors may play in a widely used model of successful central nervous system (CNS) regeneration.

Animals↗
PubMed1991

Determination of released CD4 and CD8 antigens in the suction-blister fluid and horny-tissue extract in patients with psoriasis.

The amounts of soluble CD4 and CD8 antigens were measured in suction-blister fluid and extracts of horny tissue in patients with psoriasis. The levels of soluble CD4 and CD8 in the suction-blister fluid of lesional skin in psoriasis was significantly higher than from normal skin and the uninvolved skin in psoriasis. Levels of soluble CD4 and CD8 in the extracts of horny tissue in psoriasis were significantly higher than those from non-psoriatic skin.

Adolescent↗
PubMed1976

Absence of collagen stimulating factors for L929 cells in granulation tissue extracts.

We have attempted to find collagen synthesis stimulating activity in polyvinyl sponge granulation tissue extracts and inflammatory fluid. The cells studied in culture were mouse L929 cells grown in monolayers. A prior study by another group reported such factors to be present in healing wound extracts and in extracts of CHHl3 injured liver. We have been unable to find such stimulating activity for L929 cells in granuloma tissue fluid. In addition we have examined the procedures used by the prior group and have found major problems in their methodology which are discussed below.

Animals↗
PubMedDate not supplied

Chemical exchange in tissue extracts revisited: bicarbonate and deuterium isotope effects on 31P resonances of phosphoethanolamine and phosphocreatine.

It is not sufficiently appreciated that chemical exchange can markedly affect the appearance of 31P tissue extract NMR spectra. In addition to the commonly recognized 31P chemical shift effects of divalent metal cation (e.g. Mg2+) binding upon ATP resonances, multiple resonances for phosphoethanolamine (PE) and phosphocreatine (PCr) are observed under certain conditions of pH, temperature, and D2O and bicarbonate concentrations. In the presence of bicarbonate ion (commonly used to neutralize acidic extractions) carbamate formation causes a second 31P resonance for PE to appear. This effect has been described previously for 13C and 1H amino acid resonances in tissue extracts [Sherry et al. J. Magn. Reson. 89, 391-398 (1990)]. The observation of a splitting of the PCr 31P resonance in aqueous solutions containing D2O has been recently ascribed to proton scalar coupling but was described earlier in an underappreciated report [Kupriyanov et al. Biochem. Biophys. Res. Comm. 114, 1117-1125 (1983)] as due to a deuterium isotope effect. These effects, carbamate formation and deuterium isotope shift, are verified herein to cause marked shifts in PE and PCr 31P resonances. The dependence upon experimental parameters is explored.

Bicarbonates↗
PubMedDate not supplied

EORTC Receptor and Biomarker Study Group Report: a sandwich enzyme-linked immunosorbent assay for vascular endothelial growth factor in blood and tumor tissue extracts.

A four-antibody sandwich enzyme-linked immunosorbent assay (ELISA) for vascular endothelial growth factor (VEGF) for application in blood (serum and plasma) and tumor tissue extracts was set up within the framework of the EORTC Receptor and Biomarker Study Group (RBSG). Polyclonal antibodies against VEGF165 were raised in chickens and rabbits, and used in a previously described assay format. The assay was validated and characterized for use in serum, plasma and tumor tissue extracts. The resulting VEGF ELISA was found to be specific for VEGF165 and VEGF121, the main isoforms of VEGF. The assay showed good precision and parallelism in serial dilutions of samples. The assay was not susceptible to interference by heterophilic antibodies because avian antibodies (duck anti-chicken and chicken anti-VEGF) were used in the pre-analyte stage and mammalian antibodies (rabbit anti-VEGF and goat anti-rabbit) in the post-analyte stage. In conclusion, a sensitive, robust and specific VEGF ELISA has been developed. Research into the prognostic value of VEGF employing this assay is currently underway.

Animals↗
PubMedDate not supplied

Muscle trophic factor: III. Effect of hormones and tissue extracts on muscle trophic-factor activity.

The ability of classical hormones or extract from adult chicken tissues to replace or influence the activity of chicken skeletal muscle cell trophic factor was investigated. Pituitary gland extract did not replace the trophic factor in a range equivalent to the serum concentrations of somatotropin, although high concentrations of such extract showed a significant ability to mimic trophic-factor activity. Insulin, triiodothyronine, testosterone, dihydrotestosterone (Stanolone), and estradiol did not show any ability to mimic trophic-factor activity. Both pituitary extract and insulin showed a potentiating effect on the trophic factor when added to the medium; however, the concentrations necessary for this effect were too high to be considered physiologic. Triiodothyronine, testosterone, Stanolone, and estradiol did not potentiate the trophic factor; indeed, at higher concentrations, these hormones actually suppressed the activity of the trophic factor. Every tissue extract examined showed, to a greater or lesser extent, the ability to potentiate the trophic factor.

Animals↗
PubMed1981

Methods for tissue extraction of sodium diphenylhydantoinate.

Procedures (I and II) are described here for tissue extraction of sodium diphenylhydantoin. Both methods imply: a) cell lysis with distilled water and sodium hydroxide respectively, and b) protein precipitation. Procedure I utilizing trichloroacetic acid to a 20 per cent dilution in tissue homogenates and II requiring two protein precipitation stages, one with hot acetone and the second with concentrated hydrochloric acid. Sediment and acidified aqueous phases were extracted several times with chloroform. An experiment implied in vitro application of the radioactive compound to previously weighed portions of the brain, cerebellum, liver and kidney of gerbo mongol. Another experiment consisted in applying the same procedures for tissue drug extraction after injection of the marked compound. In both experiments recoveries ranged from 95 to 98 per cent with variation coefficients under 8 per cent and p less than 0.01. Therefore we recommend both procedures although the second yields more transparent end extracts.

Animals↗