Gene/Protein Disease Symptom Drug Enzyme Compound
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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)

The influence of cardioplegic arrest (single or multidose cardioplegia) and subsequent long-term cold storage on myocardial high energy phosphate content was studied in 29 dogs divided into 6 groups of experiments. Three cardioplegic solutions were tested: Bretschneider HTK (intracellular-type solution), St. Thomas' Hospital and N.I.H. solutions (both extracellular-type solutions). In group I, II and III single dose cardioplegic arrest with respectively St. Thomas' Hospital, Bretschneider HTK and N.I.H. solutions was carried out and excised hearts were stored at 0.5 degrees C for 24 hours. In group IV-Bretschneider HTK and in group V-N.I.H. solutions were used for cardioplegic arrest and intermittent perfusion of the cooled hearts at 4, 8 and 12 hours of storage (multidose cardioplegia). In group VI, after cardioplegic arrest with Bretschneider HTK solution, different temperatures of storage (0.5 degrees C, 12 degrees C and 18 degrees C) were studied. Myocardial content of ATP and creatine phosphate was evaluated by means of bioluminescence techniques from serial left ventricular biopsies taken prior to aortic cross-clamping and after 1, 2, 3, 4, 5, 6, 8, 10, 12 and 24 hours. In group I ATP was significantly lower than in groups II and III after 6 h (p less than 0.005). After 24 hours of storage ATP-levels were significantly higher (p less than 0.05) after multidose Bretschneider HTK cardioplegia or N.I.H. cardioplegia than after single dose N.I.H. or St. Thomas' cardioplegia. There was no significant difference in ATP content between multidose Bretschneider and multidose N.I.H. cardioplegia.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Long-term preservation of donor hearts: the effect of intra- and extracellular-type of cardioplegic solutions on myocardial high energy phosphate content. 213 19

Synthetic peptides derived from the sequence surrounding tyrosine-857 in the human platelet-derived growth factor (PDGF) beta-receptor were used to elucidate the requirement for length and presence of negative and positively charged amino acids in substrates of the PDGF beta-receptor protein tyrosine kinase. The measured Km for the different peptides were all in the range 1-10 mM. A peptide of only five amino acids, lacking acidic amino acid residues, were found to be substrates for the receptor kinase. Ligand binding was found to stimulate the phosphorylation of peptides mainly by lowering the Km both for peptide and for ATP. Only minor changes in the Vmax occurred upon stimulation with PDGF. The reaction mechanism was found to be sequential, i.e. both the peptide and ATP have to bind to the enzyme before any product is released.
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PMID:Characterization of the platelet-derived growth factor beta-receptor kinase activity by use of synthetic peptides. 215 30

Clinically applied methods of cardioplegia show very different effects on the rapidity of decay of energy-rich phosphates as well as on kind and progression of ultrastructural alterations of the ischemic myocardium. Comparing the methods of cardioplegia according to Kirklin, St. Thomas's Hospital and Bretschneider (solution HTK) with pure ischemia at 25 degrees C (model A) and Kirklin's or St. Thomas's cardioplegia and subsequent 210 min or HTK cardioplegia and 300 min ischemia at 22 degrees C plus 20 min subsequent reperfusion (model B) leads to the following results: Model A: Compared with pure ischemia cardioplegia according to Kirklin and the St. Thomas's Hospital slows down the decay of the left ventricular ATP-concentration by a mean factor of 3 and the progression of structural alterations of the left ventricular subendocardium by a factor of 2. HTK retards the ATP-decay by a factor of 6, the alterations of ultrastructure by a factor of 6.5. St. Thomas's solution, in contrast to all other methods of cardioplegia, at the onset of ischemia already causes a cellular edema of myocytes; the edema increases during ischemia, and at the ATP-concentration of 4 mumol per gram myocardium is more pronounced than with pure ischemia, Kirklin or HTK. After application of Kirklin's solution, in contrast, a cellular edema of capillary endothelia develops during ischemia, which at 4 mumol ATP is more pronounced than with each of the other methods. Model B: After global ischemia until the ATP-concentration of left ventricular myocardium is 4 mumol/g and a subsequent 20 minutes post-ischemic recovery the ultrastructural alterations in principle resemble those occurring during ischemia (model A).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Myocardial protection: left ventricular ultrastructure after different forms of cardiac arrest. 244 33

A protein-tyrosine kinase (PTK, EC 2.7.1.112) from human platelets was purified with high yield. Purification of the enzyme involved sequential chromatography on casein-agarose, tyrosine-agarose, heparin-Sepharose and hydroxylapatite. The procedure resulted in substantially enriched 54/52 kDa polypeptides on SDS-polyacrylamide gel electrophoresis and a yield of about 25% in PTK activity. About 250 micrograms of purified protein could be obtained from 1 g of cell protein. The purification factor varied between 1000 and 1500. Determination of the molecular mass of the purified PTK under nondenaturating conditions by molecular sieve chromatography revealed that the enzyme is a monomer of about 50 kDa. Among various protein substrates tested, casein was most prominently phosphorylated. All substrates were exclusively phosphorylated at tyrosine residues. Autophosphorylation at tyrosine residues of the 54/52 kDa proteins was observed in the presence of Mg2+ or Mn2+. At each purification step, the 54/52 kDa proteins were precipitated by sera from tumor-bearing rabbits immunoprecipitating pp60src, but not by control sera. The amount of the immunoprecipitated purified 54/52 kDa phosphoproteins was directly proportional to the amount of antiserum used. Partial peptide mapping by V8 proteinase showed a 26 kDa tyrosine-phosphorylated fragment for the 54 and the 52 kDa proteins as well as for the pp60c-src molecules of intact platelets. All these data indicated that purified PTK is closely related to pp60c-src of human platelets. Using casein as a substrate for the purified enzyme, the Km for ATP was 4 microM and the Vmax for the reaction was 2.0 nmol/min per mg.
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PMID:High-yield purification of a pp60c-src related protein-tyrosine kinase from human platelets. 245 18

The addition of the disaccharides maltose (10, 20, 30 mM) and sucrose (30, 60 mM) to Bretschneider's organ protective HTK solution was evaluated to improve renal protection by an enhanced glycolytic energy supply. Canine kidneys were perfused for 8 min with either HTK solution or HTK solution containing additional disaccharides. After nephrectomy the kidneys were incubated at 25 degrees C and metabolic parameters were determined at regular intervals. Maltose and sucrose are slowly cleaved during renal ischemia but maltose distinctly faster than sucrose. Maltose increases intraischemic ATP supply. However, 30 mM maltose was no better than 10 mM. 60 mM sucrose was about as effective for glycolysis as 10 mM maltose. However, possibly due to fructose release there was an accelerated decrease of adenine nucleotides with sucrose. Although fructose enters glycolysis it seems to have negative side-effects. Hence, probably neither sucrose nor fructose are appropriate for renal substrate supply during ischemia.
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PMID:Intraischemic metabolic effects of different disaccharides on protected canine kidneys. 251 81

In 12 dogs the hearts after excision were perfused for 24 hours with Bretschneider HTK cardioplegic solution. Six of these hearts were used only to assess myocardial HEP and ultrastructure during 24 hours of conservation. In the next six dogs orthotopic heart transplantation was performed to evaluate functional outcome after prolonged preservation. After 24 hours of continuous perfusion of the donor heart the ATP level was completely comparable with control, preischemic value. Also ultrastructure of the myocytes was perfectly preserved. All transplanted hearts recovered completely upon reperfusion without a need of inotropic support. Good functional outcome after transplantation was correlated with about 70% of myocardial HEP content and intact ultrastructure of the myocytes. We concluded that continuous perfusion with Bretschneider HTK cardioplegic solution makes successful heart transplantation possible after 24 hours of preservation.
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PMID:Successful orthotopic heart transplantation in dogs after 24 hours of continuous perfusion with Bretschneider HTK cardioplegic solution. 251 48

Actually the maximum preservation time for donor hearts is limited to 4 hours. The aim of this experimental study in dogs was to develop techniques allowing an extension of this period up to 24 hours. In the first part of the study the influence of diastolic arrest on the preservation of high energy phosphates was studied: The following methods of cardioplegic arrest were used: 1. hyperkalemic arrest 2. hyperkalemic arrest plus high magnesium 3. low sodium and calcium-free cardioplegia. In all experiments cardioplegic arrest was followed by cold storage (0.5 degrees C). Single dose K+ plus Mg2+ cardioplegia offered the least protection. The other two types of cardioplegia were better but the ATP content was still below 50% after 24 hrs preservation. Reperfusion after cardiac transplantation induced irreversible injury and function did not recover after transplantation. In the second part of the study continuous hypothermic perfusion with low sodium and calcium-free cardioplegia was studied. With this technique HEP content, myocardial structure and functional recovery were 100% after transplantation.
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PMID:[Long-term preservation of the heart in view of its transplantation. An experimental study]. 263 87

Membrane fractions enriched in sarcoplasmic reticulum (SR) were isolated from the cardiac ventricles of 10-month-old, stroke-prone spontaneously hypertensive rats (SHRSP) which had been maintained for nine months on one of four experimental diets: low protein (LP) (19% protein), standard (STD) (24% protein), high protein (HP) (32% protein), or high methionine (1.9% methionine) (MET). ATPase activities, as well as ATP-dependent Ca2+ binding and Ca2+-uptake activities, of the isolated SR were determined to examine the influence of diet on myocardial Ca2+-pump activity. SR from all four groups exhibited similar Mg2+-ATPase activity. However, the (Ca2+ + Mg2+)-ATPase activity was significantly elevated in SR from rats on the MET diet while the activity in the other groups showed no significant differences. After 15 sec of incubation, Ca2+-uptake (presence of oxalate) in SR from the LP group was significantly less than Ca2+-uptake in SR from each of the three other diet groups. Ca2+ binding (absence of oxalate) in the SR from the LP group was also significantly less than that from each of the three other diet groups. Kinetic analysis of SR Ca2+-uptake over 60 sec revealed that the Bmax of the MET group was significantly higher than Bmax of the STD diet group. In addition, the Bmax of the LP group was significantly lower than Bmax of the HP and MET groups. There was no significant difference in affinity of the SR Ca2+-uptake system among the four diet groups. These results indicate that modification of dietary protein can influence myocardial SR Ca2+-pump function.
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PMID:ATP-dependent calcium uptake in myocardial sarcoplasmic reticulum from spontaneously hypertensive rats: effect of modification of dietary protein. 293 82

A region of the primary amino acid sequence of the epidermal growth factor receptor (EGF) protein-tyrosine kinase, which is involved in ATP binding, was identified using chemical modification and immunological techniques. EGF receptor was 14C-labelled with the ATP analogue 5'-p-fluorosulphonylbenzoyladenosine and from a tryptic digest a single radiolabelled peptide was isolated. The amino acid sequence was determined to be residues 716-724 and hence lysine residue 721 is located within the ATP-binding site. Antisera were elicited in rabbits to a synthetic peptide identical to residues 716-727 of the EGF receptor and the homologous sequence in v-erb B transforming protein from avian erythroblastosis virus. The affinity-purified antibodies precipitated human ECF receptor from A431 cells and placenta, and the v-erb B protein from erythroblasts. The antibodies inhibited EGF-stimulated receptor protein-tyrosine kinase autophosphorylation and phosphorylation of an exogenous peptide substrate containing tyrosine. The antibodies did not immunoprecipitate the transforming proteins pp60v-src or P120gag-abl or cAMP-dependent protein kinase, proteins which have homologous but not identical sequences surrounding the lysine residue within the ATP-binding site, nor did they react with the platelet-derived growth factor receptor. The antibodies had no effect on the kinase activity of purified v-abl protein in solution. The antibodies may therefore be a specific inhibitor of the tyrosine kinase of the EGF receptor.
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PMID:Antibodies to the ATP-binding site of the human epidermal growth factor (EGF) receptor as specific inhibitors of EGF-stimulated protein-tyrosine kinase activity. 301 11

Kidneys were perfused either with Euro-Collins-solution or with HTK-solution of Bretschneider. The perfusion pressure as well as the perfusion flow were measured during a six-minute perfusion. The perfusion resistance was higher in Euro-Collins-kidneys than during HTK-perfusion. The venous outflow of the kidney as well as the ureteral outflow was measured during each minute of the perfusion and has analysed for osmolality, and for sodium and potassium concentrations. In Euro-Collins-kidneys a complete "equilibration" of the extracellular space was not achieved, while during HTK-perfusion concentrations in the venous as in the tubular outflow, similar to those in the HTK-solution itself, could be reached. At the end of the different perfusions, tissue was analysed for biochemical parameters such as ATP, ADP, AMP and lactate as well as for morphological features. Lactate had increased and ATP had decreased during perfusion with Euro-Collins-solution, while ATP had not changed and lactate had decreased during perfusion with HTK-solution. Normal glomerular, tubular and dilated vascular structures can be seen after HTK-perfusion, while a glomerular and vascular contraction takes place during Euro-Collins-perfusion.
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PMID:Short-term perfusion and "equilibration" of canine kidneys with protective solutions. 310 3


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