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Query: EC:2.7.10.1 (
ERK
)
95,504
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
A digestibility trial involving 20 Hampshire ram lambs and a 2-yr grazing study using 103 mature crossbred cows were conducted to determine the effects of methionine addition to a
urea
-grain supplement on intake and digestibility of dormant range grasses and on cow performance. In each trial, four treatment groups were supplemented with either a
urea
-grain control (CON),
urea
-grain plus methionine (
MET
, 3.3% DL-methionine),
urea
-grain plus inorganic sulfur (SUL, 3.0% sodium sulfate), or soybean meal (SBM). Supplements were designed to provide 45 and 360 g of CP.animal-1.d-1 (lambs and cows, respectively) and were balanced for ME, Ca, P, and K. Lambs had ad libitum access to mature prairie hay, whereas cows grazed dormant winter range from mid-November until mid-February. For the grazing study, forage OM intake (OMI) was determined in late November and in late January by the fecal output/indigestibility ratio technique. Controlled-release chromic oxide boluses were used as an external marker to estimate fecal output, and acid insoluble ash was used as an internal marker to predict OM digestibility (OMD). Mean daily DMI of mature prairie hay was 1,057 g/lamb and was not affected by supplementation. Apparent DM, NDF, and ADF digestibilities and N biological value did not differ (P > .10) among treatments. Nitrogen digestibility was increased (P = .06) for lambs fed the
MET
or SUL compared with CON.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Effect of methionine addition to a urea-grain supplement on intake and digestibility of mature, dormant grasses and performance of cows grazing winter range. 844 Jun 72
Urea
(200-400 milliosmolar) activates transcription, translation of, and trans-activation by the immediate-early gene transcription factor Egr-1 in a renal epithelial cell-specific fashion. The effect at the transcriptional level has been attributed to multiple serum response elements and their adjacent Ets motifs located within the Egr-1 promoter.
Elk
-1, a principal ternary complex factor and Ets domain-containing protein, is a substrate of the extracellular signal-regulated kinase (ERK) mitogen-activated protein kinases. In the renal medullary mIMCD3 cell line,
urea
(200-400 milliosmolar) activated both ERK1 and ERK2 as determined by in-gel kinase assay and immune-complex kinase assay of epitope-tagged] ERK1 and ERK2. Importantly,
urea
did not affect abundance of either ERK.
Urea
-inducible Egr-1 transcription was a consequence of ERK activation because the ERK-specific inhibitor, PD98059, abrogated transcription from the murine Egr-1 promoter in a luciferase reported gene assay. In addition, activators of protein kinase A, including forskolin and 8-Br-cAMP, which are known to inhibit ERK-mediated events, also inhibited
urea
-inducible Egr-1 transcription. Furthermore,
urea
-inducible activation of the physiological ERK substrate and transcription factor,
Elk
-1, was demonstrated through transient cotransfection of a chimeric
Elk
-1/GAL4 expression plasmid and a GAL4-driven luciferase reporter plasmid. Taken together, these data indicate that, in mIMCD3 cells,
urea
activates ERKs and the ERK substrate,
Elk
-1, and that ERK inhibition abrogates
urea
-inducible Egr-1 transcription. These data are consistent with a model of
urea
-inducible renal medullary gene expression wherein sequential activation of ERKs and
Elk
-1 results in increased transcription of Egr-1 through serum response element/Ets motifs.
...
PMID:Urea-inducible Egr-1 transcription in renal inner medullary collecting duct (mIMCD3) cells is mediated by extracellular signal-regulated kinase activation. 885 40
Human neutrophil elastase (HNE) and porcine pancreatic elastase (PPE) were incubated with two radiolabelled model poly(urethane), a poly(ester-
urea
-urethane) containing [14C]toluene diisocyanate ([14C]TDI), poly(caprolactone)(
PCL
) and ethylenediamine (ED), and a poly(ether-
urea
-urethane) containing [14C]TDI, poly(tetramethylene oxide) (PTMO) and ED. Ten-fold more radioactive carbon was released when PPE was incubated with [14C]TDI/
PCL
/ED than when HNE was used. The PPE-induced radioactive carbon release was significantly reduced by a specific elastase inhibitor. Ten-fold less radioactive carbon was released when [14C]TDI/PTMO/ED was incubated with PPE as compared to [14C]TDI/
PCL
/ED. Since neutrophils, which contain elastolytic activity, are present during the inflammatory response, the stability of biomaterials used in implanted devices may be affected.
...
PMID:Elastase-induced hydrolysis of synthetic solid substrates: poly(ester-urea-urethane) and poly(ether-urea-urethane). 898 79
Inner medullary collecting duct (IMCD) cells adapt to a hypertonic environment by synthesizing transporters that allow for accumulation of organic osmolytes. To examine for activation of additional mitogen-activated protein (MAP) kinases, extracts of IMCD-3 cells subjected to a hypertonic medium (600 mosmol/kgH2O) for 15 min were fractionated by Mono Q fast-performance liquid chromatography and assayed with the epidermal growth factor receptor [
EGFR
-(662-681)] peptide as substrate. Three peaks of activity were identified. Western blotting revealed that these peaks coincided with Jun NH2-terminal kinase (JNK), extracellular signal-regulated protein kinases, ERK1 and ERK2, and p38 MAP kinase. To assess the functional significance of ERK2 activation in IMCD-3 cells, the effect of PD-098059, an inhibitor of the upstream regulatory protein kinase MAP/
ERK
kinase (MEK) was assessed. PD-098059 inhibited
ERK
activation by hypertonicity. Yet, the stimulation of inositol uptake, a marker of adaptation, after 16 h was unaltered. Direct measurements of JNK activity [phosphorylation of GST-cJun-(1-79)] revealed a marked (20- to 40-fold) increase in activity as medium osmolality was increased from 300 to 900 mosmol/kgH2O with either NaCl or mannitol.
Urea
induced a more modest increase in activity. The response is prompt and detected as early as 2 min after exposure, reaching a maximum activation at 10-15 min. Downregulation of cellular protein kinase C (PKC) by chronic exposure to phorbol esters only minimally attenuated the JNK response to hyperosmolality, indicating a lack of involvement of PKC. We conclude that, in IMCD-3 cells, inhibition of
ERK
activation by hyperosmolality does not prevent osmoregulatory increase in inositol transport. This is not consistent with a role for ERKs in the response. The roles for JNK and p38 have not been ruled out, and these pathways may represent the initiating event in the subsequent transcription of organic osmolyte transporter genes and adaptation to extracellular hypertonicity.
...
PMID:Multiple mitogen-activated protein kinases are regulated by hyperosmolality in mouse IMCD cells. 908 72
Urea
activates a characteristic subset of signaling pathways in a tissue-specific fashion, including transcription of immediate early genes through activation of the mitogen-activated protein kinase (MAPK),
ERK
(extracellular signal-regulated kinase), and activation of its transcription factor substrate,
Elk
-1. The ability of
urea
to activate the
ERK
effector and pivotal regulatory kinase, ribosomal S6 kinase (RSK), was investigated in mIMCD3 renal inner medullary collecting duct cells.
Urea
upregulated RSK activity in a time-dependent fashion in serum-deprived mIMCD3 cells; the effect was maximal at 5 min. Activation by hypertonic NaCl, in contrast, was negligible at 5 min and peaked at 15 min. Both stimuli induced the nuclear translocation of cytosolic RSK, as determined via immunofluorescence. Importantly, activation of RSK by both solutes was MAPK/ERK kinase (MEK) dependent, as determined by the ability of the specific MEK inhibitor, PD-98059, to abrogate the response. Taken together, these data indicate that
urea
activates the
ERK
effector, RSK, in cells of the renal medulla in an
ERK
-dependent fashion, further emphasizing the functional significance of
urea
signaling through
ERK
activation in renal medullary cells.
...
PMID:Urea activates ribosomal S6 kinase (RSK) in a MEK-dependent fashion in renal mIMCD3 cells. 945 25
To prove that perfused liver can be preserved at room temperature (22 degrees C), we made the experiment, in which
HTK
was basic solution, perfluorocarbon acted as oxygen carrier and lipid acted as energy substrate in the homoiothermy condition, pig liver organs were perfused extracorporeally through the V. portal with perfusion solution. In fixed period of time the perfusion solution from the liver was taken and analysed to determine for liver biochemical function and observe the concentration and size of hepatocellular mitochondria. In oxygen carrier perfusion solution the ammonia concentration was low,
urea
concentration was high, damage to mitochondria was minimum and by addition of lipid emulsion the concentration of glucose can be maintained. The experimental and control data were obviously significant. The result demonstrated that oxygen carrier (perfluorocarbon) as oxygen supplier can provides enough oxygen to liver cell, at the sametime, lipid emulsion intralipid) provides energy so as the perfused liver can be preserved at high temperature, i.e. 22 degrees C at relative long time (40 hours) and still has the function of removing toxic substance such as ammonia and converting it to
urea
, meanwhile maintain the normal structure of mitochondria. The preservation of perfused liver at homoiothermy is possible.
...
PMID:[Experimental study on homoiothermic extracorporeal liver preservation]. 959 56
Serum stem cell factor (SCF) and soluble
KIT
(sKIT) levels were estimated in patients with chronic renal failure (CRF) and anaemia, and compared with clinical parameters of blood cells and renal function. Serum SCF levels in CRF patients were 5-fold higher than those in healthy controls. However, serum sKIT levels in haemodialysis (HD)-CRF patients were only slightly higher than those of healthy controls. In untreated CRF patients and healthy controls, serum SCF levels were significantly correlated with blood
urea
nitrogen (BUN), creatinine. haemoglobin, red blood cell (RBC) count and sKIT. In untreated CRF patients, serum SCF levels were significantly correlated with BUN, creatinine, and sKIT. These results suggest that serum SCF levels increased with the deterioration of renal function and might be related to erythropoiesis.
...
PMID:Elevated SCF levels in the serum of patients with chronic renal failure. 975 36
1. Cells of the mammalian renal medulla are routinely subjected to an enormously elevated and labile ambient osmolality as a consequence of the renal concentrating mechanism. The present review focuses on the most recent advances in hyperosmotic solute-mediated signal transduction and regulation of gene transcription in cells of the kidney medulla. 2. On the basis of osmolality alone, NaCl and
urea
are the principal renal medullary solutes. 3.
Urea
, which is membrane permeant, activates transcription of immediate-early genes via an extracellular signal-regulated kinase (ERK)/
Elk
-1-dependent pathway.
Urea
also activates multiple effectors characteristic of a receptor tyrosine kinase-like signalling cascade. 4. In contrast, the functionally impermeant solute NaCl activates transcription of tonicity responsive genes (principally genes encoding proteins essential for osmolyte uptake or synthesis) via a unique consensus element contained within their 5' flanking sequences. 5. An activity exhibiting tonicity inducible sequence-specific interaction with this DNA element has been identified. 6. Hypertonicity, like thermal stress, activates transcription of genes encoding heat shock proteins. The relationship between signalling events leading to tonicity mediated and heat shock-mediated gene transcription remains to be established.
...
PMID:Signalling and gene regulation by urea and NaCl in the renal medulla. 1002 73
We have developed specific antibodies against fragments of
anaplastic lymphoma kinase
(
ALK
) in order to develop tools for characterizing the expression and biological function of this orphan receptor. The first fragment consisted of residues 280 to 480 of the murine extracellular domain, was expressed in Escherichia coli (E. coli), purified in the presence of
urea
from the pellet of mechanically lysed cells and injected into rabbits as an unfolded protein in
urea
. The second fragment consisted of residues 1519 to 1619 of the murine sequence, corresponding to the C-terminal side of the kinase domain. It was expressed in E. coli as a soluble glutathione-S-transferase fusion protein, purified from the supernatant of broken cells and injected into rabbits as a folded protein. Both antisera were purified using antigen affinity chromatography, with the polyclonal antibodies eluted stepwise using three different buffers, 0.1 M glycine, pH 2.9, followed by 7 M
urea
, pH 4, followed by 6 M guanidine-HCl (GdnHCl), pH 4. Antisera prepared against either antigen contained antibodies that eluted in each of the three pools, indicating that solvents more chaotropic than acid were required to elute antibody populations that were tightly bound to the antigen column. All three antibody pools were reactive towards their respective antigens upon Western blot analysis. Purified polyclonal antibodies (pAbs) to both fragments also recognized the full-length protein expressed in Chinese hamster ovary cells. In every case, the pAbs eluting in GdnHCl were the most sensitive for detecting full-length
ALK
.
...
PMID:Fractionation of polyclonal antibodies to fragments of a neuroreceptor using three increasingly chaotropic solvents. 1037 56
Three multiparous Holstein cows (607 kg of BW) were surgically prepared with an elevated carotid artery and indwelling catheters in the hepatic, portal, and two mesenteric veins to study the effects of methionine supplementation on amino acid metabolism during the last 2 wk of pregnancy. The study began 15 d before the expected calving date. Dietary treatments were Control (1.53 Mcal NE(l)/kg, 15.6% CP, and 40% ruminally undegradable protein) and Control supplemented with 60 g/d of ruminally protected methionine (
MET
, supplying 39 g/d of DL-methionine and approximately 18 g/d of methionine available for intestinal absorption). Each cow received both dietary treatments in a crossover design. Cows were fed once daily. After 5 d on treatment, a blood flow marker (para-aminohippurate) was infused into a mesenteric vein, and arterial, portal, and hepatic blood samples were obtained at 0, 2, 6, 12, and 18 h after feeding. Net flux of methionine was calculated as the plasma arteriovenous difference multiplied by plasma flow. Dry matter intake (10.8 kg/d) and portal (824 L/h) and hepatic (995 L/h) plasma flows were not affected (P > .10) by treatment. Arterial plasma concentration of methionine was greater (P = .10) with
MET
(27.67 microM) than with Control (16.42 microM). Net portal absorption of methionine increased (P = .10) with
MET
(26.2 g/d) compared with Control (9.5 g/d). The net portal methionine flux was negatively correlated (r = -.59; P < .001) with arterial
urea
concentrations. Net flux of methionine across splanchnic tissues shifted (P = .06) from a net uptake with Control (4 g/d) to a net output with
MET
(11 g/d). Therefore,
MET
increased by 15 g/d the methionine supply to the rest of the body. The net uptake of methionine by splanchnic tissues observed with Control indicated a net mobilization of methionine by peripheral tissues. Results indicate that methionine was the limiting amino acid with Control and that
MET
was beneficial because it increased methionine supply to peripheral tissues and reduced arterial
urea
concentrations.
...
PMID:Response of nitrogen metabolism in preparturient dairy cows to methionine supplementation. 1076 83
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