Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Liver Extracts”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9Linked to original sources
PubMed1976

Inactivation of phosphoenolypyruvate carboxykinase (GTP) by liver extracts.

1. The inactivation of phosphoenolpyruvate carboxykinase (GTP) (EC 4.1.1.32) in liver extracts was catalysed by the microsomal fraction, and led to the enzyme becoming bound to the microsomal membranes. 2. Inactivation by microsomal fraction, typsin or heating at 48degreesC was accelerated by L-cystine, D-cystine and oxidized glutathione and decreased by dithiothreitol. 3. MnC1(2) and CoC1(2) protected the enzyme from inactivation by heat or microsomal fraction, but did not affect the inactivation caused by trypsin. 4. Several proteinase inhibitors had no effect on the microsomal inactivation reaction, suggesting that proteolysis was not involved. 5. It is argued that the initial step in the degradation of phosphoenolpyruvate carboxykinase (GTP) is an inactivation reaction, perhaps involving oxidized thiol compounds.

Animals↗
PubMed1979

Studies of ethylene-forming system in rat liver extract.

Evidence of enzymatic formation of ethylene from methionine by rat liver extracts is presented. The ethylene production is closely associated with growth of the animal. The conversion of L-methionine to ehtylene is oxygen dependent. Substrate analogue studies show that the ethylene-forming system is structurally specific and requires in the center of the molecule alpha-CH2-CH2- with one end attached to an unencumbered sulfur atom from a thioether moiety and the other end attached to a carboxyl group. Sylfhydryl agents are found to be very effective inhibitors of the ethylene-forming system. The finding of alpha-keto-4-methylthiobutyric acid to be a more efficient precursor of ethylene production suggests the possibility that alpha-keto-4-methylthiobutyric acid may be an intermediate in the biosynthesis of ethylene from methionine in mammalian tissues.

Aging↗
PubMed2002

Identification and quantification of metallothionein isoforms and superoxide dismutase in spiked liver extracts using HPLC-ESI-MS offline coupling and HPLC-ICP-MS online coupling.

A two-dimensional chromatographic method for the characterization of metallothionein isoforms (MT) and superoxide dismutase (SOD) in spiked liver extracts was developed for the optimization of extraction procedures from liver samples. Element-specific detection (ICP-MS) and molecule-specific detection (ESI-MS) were applied for maximum species information. A special focus was laid on the quantitative data evaluation (species stoichiometry, calibration with and without matrix, recovery), which is neglected in most MT/SOD publications with hyphenated techniques. Linearity, precision (residual standard deviation of calibration curves <10%), and detection limits (<0.6 mg L(-1) for MT isoforms and 13 mg L(-1) for SOD) prove the suitability of the method for quantification. An alternative quantification is proposed for the extension towards other lesser or even unknown trace element species, especially the native porcine MT and SOD.

Animals↗
PubMed1984

Catabolism and lability of S-adenosyl-L-methionine in rat liver extracts.

The fate of S-adenosyl-L-methionine was studied in rat liver extracts by analysing the distribution of radioactivity from labelled adenosylmethionine in decomposition products, which were separated from each other by chromatographic and electrophoretic means. Marked non-enzymic degradation to adenine, pentosylmethionine, methylthioadenosine and homoserine was evident at pH 6.9-7.8. Enzymic cleavage to methylthioadenosine was stoichiometric with the accumulation of spermidine and could be totally prevented by inhibiting S-adenosyl-L-methionine decarboxylase. The results rule out the existence of adenosylmethionine cyclotransferase in rat liver and indicate that only two quantitatively significant enzymic processes are involved in hepatic adenosylmethionine degradation. Excluding nonenzymic decomposition, more than 99% of adenosylmethionine is demethylated and exclusively catabolized further by S-adenosyl-L-homocysteine hydrolase. Less than 1% of adenosylmethionine is decarboxylated and immediately utilized totally for polyamine biosynthesis.

Adenosine↗
PubMed1997

A difference in responsiveness of isolated hepatic artery, aorta, portal vein and vena cava of pig to flavin adenine dinucleotide including liver extract.

1. Tension of isolated hepatic artery, aorta, portal vein and vena cava of pigs was measured isometrically to study the mode of action of flavin adenine dinucleotide, including liver extract (FADLE). 2. FADLE showed concentration-dependent relaxation of norepinephrine contraction in the hepatic artery, but FADLE had little influence on the aorta, portal vein and vena cava contracted by norepinephrine (NE). 3. In Ca(2+)-free solution, FADLE-induced relaxation in both the hepatic artery and aorta contracted by NE was significantly reduced, and its reduction was greater in the hepatic artery than in the aorta. Furthermore, extracellular Ca2+ dependence of norepinephrine-induced contraction was much larger in the hepatic artery than in the aorta. 4. Results suggest that FADLE shows regional variations in vasorelaxation through the alteration of Ca2+ movement by the cell, and that this may reflect one of the mechanisms in its ability to increase blood flow in hepatic tissue.

Animals↗
PubMed1975

Specific unresponsiveness to skin allografts in mice. IV. Immunological reactivity of mice treated with liver extracts, Bordetella pertussis, and antilymphocyte serum.

The strain-specific unresponsiveness to H-2 incompatible skin allografts induced by treatment of adult mice with single inoculations of donor strain liver extract and Bordetella pertussis vaccine, as well as three doses of antilymphocyte serum, has been investigated by several in vivo and in vitro methods, with a view to elucidating it mechanism. Lymphoid cells from mice with long surviving skin grafts were found to be reactive in graft-versus-host assays (as measured by splenomegaly or popliteal lymph node enlargement), and mixed lymphocyte culture tests gave positive results. Attempts to cause lethal runting of F1 hybrid mice injected at birth with spleen cells from unresponsive mice gave variable results. However, the injection of F1 hybrid cells into the footpads of unresponsive animals failed to elicit a significant host-versus-graft response. Although lymphoid cells from unresponsive animals did not include detectable numbers of cytotoxic cells, such cells could be generated by previous in vitro mixed lymphocyte culture stimulation or, to some degree, by the injection of the animals with F1 hybrid cells. Attempts to prevent mixed lymphocyte culture stimulation or cytotoxicity with serum from unresponsive mice failed at the serum concentrations used. The data indicate that long-term unresponsiveness in this system is maintained by the production in the hosts of factors that interfere with the cell-mediated response.

Animals↗