E B CHAIN

Imperial College London, Londinium, England, United Kingdom

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Publications (87)621.21 Total impact

  • David J. Hearse · David A. Stewart · Ernst B. Chain
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    ABSTRACT: In studies with the isolated perfused working hearts from rats with experimentally induced diabetes, the ability of the hearts to survive during, and recovery from, 30 min of anoxia has been studied. In contrast with hearts obtained from normal rats, which gave good and sustained recoveries, the hearts from diabetic animals after an initial period of recovery (approx. 2 min), exhibited cardiac failure for periods of up to 4 min. After this period the hearts entered a second phase of recovery but did not recover to the same extent as the hearts from normal animals. Hearts of diabetic animals therefore appear to be more vulnerable to anoxic damage than do those from normal rats.
    No preview · Article · Jul 1975 · Journal of Molecular and Cellular Cardiology
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    M Gorecki · A Bar-Eli · Y Burstein · A Patchornik · E B Chain
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    ABSTRACT: 1. A soluble D-alanine carboxypeptidase from Escherichia coli strain B was purified on a p-aminobenzylpenicillin-Sepharose column. This one-step chromatography followed by an (NH4)2SO4 precipitation yielded an enzyme purified 1200-fold and some of its properties are reported. 2. The pure D-alanine carboxypeptidase was devoid of D-alanine carboxypeptidase II activity and migrated as a single protein band on analytical disc gel electrophoresis. 3. Triton X-100 in the purification procedure is an absolute requirement for obtaining a stable enzyme. 4. The enzymic activity of D-alanine carboxypeptidase was greatly affected in solution of high salt concentrations and varied somewhat with the nature of the cation tested.
    Preview · Article · May 1975 · Biochemical Journal
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    D J Hearse · D A Stewart · E B Chain
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    ABSTRACT: Isolated perfused working rat hearts were subjected to elective cardiac arrest for 20 or 30 min. Various methods of arrest, either singly or in combination and with or without coronary perfusion, were studied. The functional recovery of the heart following the termination of arrest was related to the concentration of adenosine triphosphate (ATP) and creatine phosphate in the myocardium at the end of the period of arrest. In turn, these concentrations depended on the method used to induce arrest. Normothermic ischemic arrest or electrical fibrillation led to a marked reduction in high energy phosphates and a poor functional recovery. In contrast, coronary perfusion with hypothermic solutions or solutions containing high concentrations of potassium induced arrest without depleting ATP or creatine phosphate. These procedures conferred considerable protection on the myocardium and thus permitted good recovery. The energy status and the recovery associated with ischemic arrest were improved by combining the ischemia with potassium induced arrest, intermittent coronary perfusion, or hypothermia. In the latter instance, a time and temperature dependent relationship was demonstrated. The results stress the importance of maintaining ATP and creatine phosphate levels during arrest; such maintenance requires the provision of a continuous supply of oxygen and nutrient, which may perhaps be best achieved by ensuring continuous and adequate coronary perfusion.
    Preview · Article · Oct 1974 · Circulation Research
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    DAVID J. HEARSE · DAVID A. STEWART · ERNST B. CHAIN

    Preview · Article · Jun 1974 · Biochemical Society Transactions
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    D J Hearse · S M Humphrey · E B Chain
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    ABSTRACT: Studies were undertaken, using the isolated perfused rat heart, into various aspects of anoxia-induced enzyme release from the potassium arrested myocardium. Profiles for release, over periods of up to 8 h anoxia, were obtained for protein, creatine phosphokinase, myokinase, glutamate oxaloacetate transaminase, glyceraldehyde-3-phosphate dehydrogenase and α-hydroxybutyrate dehydrogenase. Two distinct peaks of enzyme release were observed; phase 1 release, which occurred during the first 10 to 60 min of anoxia and phase 2 release which followed phase 1 release and lasted for at least 7 to 8 h. In phase 1, 2 to 5% of the enzyme was released. Reoxygenation of the heart during phase 1 had a marginal effect upon overall enzyme release. Reoxygenation during phase 2 of enzyme release resulted in an immediate and massive increase in the rate of protein and enzyme release from the myocardium.
    Preview · Article · Sep 1973 · Journal of Molecular and Cellular Cardiology
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    D. J. HEARSE · S. M. HUMPHREY · E. B. CHAIN

    Preview · Article · Jul 1973 · Biochemical Society Transactions
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    D. J. HEARSE · S. M. HUMPHREY · E. B. CHAIN

    Preview · Article · Jul 1973 · Biochemical Society Transactions
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    Ernst B. Chain · Peter M. Sender
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    ABSTRACT: In the absence of glucose, insulin stimulated the incorporation of (14)C-labelled amino acids into protein by perfused rat hearts that had been previously substantially depleted of endogenous glucose, glucose 6-phosphate and glycogen by substrate-free perfusion. This stimulation was also demonstrated in hearts perfused with buffer containing 2-deoxy-d-glucose, an inhibitor of glucose utilization. It is concluded that insulin exerts an effect on protein synthesis independent of its action on glucose metabolism. Streptozotocin-induced diabetes was found to have no effect either on (14)C-labelled amino acid incorporation by the perfused heart or on the polyribosome profile and amino acid-incorporating activity of polyribosomes prepared from the non-perfused hearts of these insulin-deficient rats, which show marked abnormalities in glucose metabolism. Protein synthesis was not diminished in the perfused hearts from rats treated with anti-insulin antiserum. The significance of these findings is discussed in relation to the reported effects of insulin deficiency on protein synthesis in skeletal muscle.
    Preview · Article · Apr 1973 · Biochemical Journal
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    D. J. HEARSE · A. J. MULLINS · E. B. CHAIN

    Preview · Article · Mar 1973 · Biochemical Society Transactions
  • D J Hearse · E B Chain

    No preview · Article · Feb 1973 · Recent advances in studies on cardiac structure and metabolism
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    E B Chain · P M Sender

    Preview · Article · Oct 1972 · Biochemical Journal
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    E B Chain · P M Sender

    Preview · Article · Oct 1972 · Biochemical Journal
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    D J Hearse · E B Chain
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    ABSTRACT: Studies with the isolated perfused working rat heart were carried out to investigate factors that may enable the heart to recover after periods of anoxia. It was found that the presence of glucose in the perfusion fluid during anoxia was essential for complete post-anoxic recovery and the presence of a high concentration of K(+) increased not only the rate of recovery but also the final extent of recovery. In an attempt to clarify the roles played by glucose and K(+) in aiding the survival and recovery of the anoxic myocardium the concentrations of parameters associated with energy liberation and anaerobic glycolysis (ATP, ADP, AMP, P(i), creatine phosphate, glycogen and lactate) were measured in the presence and absence of glucose during the anoxic phase. Determinations of these parameters were carried out during the working aerobic control period, the anoxic period (K(+) arrest) and the recovery period. The results demonstrated that glucose acted as an energy source during anoxia and thus maintained myocardial concentrations of high-energy phosphates, particularly ATP. These studies have also shown a direct relationship between the ability of the heart to recover and the concentration of myocardial ATP at the time of reoxygenation.
    Preview · Article · Sep 1972 · Biochemical Journal
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    I Das · E B Chain

    Preview · Article · Aug 1972 · Biochemical Journal
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    D J Hearse · E B Chain

    Preview · Article · May 1972 · Biochemical Journal
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    P R Dodd · H F Bradford · E B Chain

    Full-text · Article · May 1972 · Biochemical Journal
  • Barry N. Herbert · Hannah J. Gould · Ernst B. Chain
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    ABSTRACT: The crystal protein of Bacillus thuringiensis var. tolworthi has been separated into two polypeptide chains having molecular weights of 55000 (A) and 120000 (B). The ratio of A to B in the crystal appears to be 2:1 on a molar basis. Differences in amino-acid composition and biological activity exclude the possibility that the larger polypeptide chain is a dimer of the smaller one. The full toxicity of the unfractionated protein to larvae of Pieris brassicae is retained by fraction A, whereas fraction B is non-toxic.
    No preview · Article · Jan 1972 · European Journal of Biochemistry
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    P R Dodd · H F Bradford · E B Chain
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    ABSTRACT: 1. The metabolism of glucose 6-phosphate in rat cerebral-cortex slices in vitro was compared with that of glucose. It was found that a glucose 6-phosphate concentration of 25mm was required to achieve maximal oxygen uptake rates and ATP concentrations, whereas only 2mm-glucose was required. 2. When 25mm-[U-(14)C]glucose 6-phosphate was used as substrate, the pattern of labelling of metabolites was found to be quantitatively and qualitatively similar to the pattern found with 10mm-[U-(14)C]glucose, except that incorporation into [(14)C]lactate was decreased, and significant amounts of [(14)C]glucose and [(14)C]mannose phosphate and [(14)C]fructose phosphate were formed. 3. Unlabelled glucose (10mm) caused a tenfold decrease in the incorporation of 25mm-[U-(14)C]glucose 6-phosphate into all metabolites except [(14)C]glucose and [(14)C]mannose phosphate and [(14)C]fructose phosphate. In contrast, unlabelled glucose 6-phosphate (25mm) had no effect on the metabolism of 10mm-[U-(14)C]glucose other than to increase markedly the incorporation into, and amount of, [(14)C]lactate, the specific radioactivity of this compound remaining approximately the same. 4. The effect of glucose 6-phosphate in increasing lactate formation from glucose was found to occur also with a number of other phosphate esters and with inorganic phosphate. Further investigation indicated that the effect was probably due to binding of medium calcium by the phosphate moiety, thereby de-inhibiting glucose uptake. 5. Incubations carried out in a high-phosphate high-potassium medium gave a pattern of metabolism similar to that found when slices were subjected to depolarizing conditions. Tris-buffered medium gave similar results to bicarbonate-buffered saline, except that it allowed much less lactate formation from glucose. 6. Part of the glucose formed from glucose 6-phosphate was extracellular and was produced at a rate of 12mumol/h per g of tissue in Krebs tris medium when glycolysis was blocked. The amount formed was much less when 25mm-P(i) or 26mm-HCO(3) (-) was present, the latter being in the absence of tris. 7. Glucose 6-phosphate also gave rise to an intracellular glucose pool, whereas no intracellular glucose was detectable when glucose was the substrate.
    Full-text · Article · Jan 1972 · Biochemical Journal
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    ABSTRACT: 1. The metabolism of [U-(14)C]glucose in perfused resting and contracting diaphragm muscle from normal rats and rats made diabetic with streptozotocin was studied in the presence and absence of insulin. 2. The incorporation of [U-(14)C]-glucose into glycogen and oligosaccharides was stimulated by insulin under all experimental conditions studied. 3. In the normal perfused resting diaphragm muscle the incorporation of radioactivity from [(14)C]glucose into lactate and CO(2) was not affected by insulin. 4. Periodic contractions, induced by electrical stimulation of the perfused diaphragm muscle in the absence of insulin, caused an increased incorporation of (14)C into glycogen and hexose phosphate esters, whereas incorporation of (14)C into lactate was greatly decreased. Production of (14)CO(2) in the contracting muscle was not significantly different from that in resting muscle. Addition of insulin to the perfusion liquid caused a further increase in formation of [(14)C]-glycogen in contracting muscle to values reached in the resting muscle in the presence of insulin. Formation of [(14)C]lactate was also stimulated by insulin, to values close to those found in the resting muscle in the presence of insulin. 5. In the diabetic resting muscle the rate of glucose metabolism was very low in the absence of insulin. Insulin increased formation of [(14)C]glycogen to the value found in normal muscle in the absence of insulin. Production of (14)CO(2) and formation of [(14)C]hexose phosphate remained unchanged. 6. In the diabetic contracting muscle production of (14)CO(2) was increased to values approaching those found in normal contracting muscle. Formation of [(14)C]lactate and [(14)C]glycogen was also increased by contraction, to normal values. Only traces of [(14)C]hexose phosphate were detectable. Addition of insulin to the perfusion medium stimulated formation of [(14)C]glycogen, to values found in normal contracting muscle. Production of [(14)C]hexose phosphate was stimulated by insulin, to approximately the values found in the normal contracting muscle. Production of (14)CO(2) and [(14)C]lactate, however, was not significantly affected by insulin. 7. These results indicate that the defects of glucose metabolism observed in perfused resting diabetic diaphragm muscle can be partially corrected by contraction, and in the presence of insulin the contracting diabetic muscle has a completely normal pattern of glycogen synthesis and lactate production, but CO(2) production remains impaired.
    Preview · Article · Dec 1971 · Biochemical Journal
  • E. B. Chain · A. E. Lowe · K. R. L. Mansford
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    ABSTRACT: A computerised automatic scanner for the quantitative evaluation of paper radiochromatograms is described. In this instrument the paper chromatogram is held in a frame, vertically moveable, between two gas flow counters.The scanning operation is performed by moving the counters horizontally across the paper radiochromatograms, discontinuously exploring unit areas for programmed time periods, the period depending on the level of radioactivity.At the end of each line, the counters are made to return to their position of origin and simultaneously the radiochromatogram is moved vertically upwards to the next line of exploration. The coordinate positions, radioactive counts and time for each unit area are recorded on paper tape. Control and read-out of the coordinate positions is effected photo-electrically, employing perforated code plates.A battery of up to ten scanners can be used simultaneously. The scanners are arranged in a time sharing system so that a single tape punch is used for all machines. The punch tape is processed using a programme which gives, for each machine, number map representation of the radioactive spots on the chromatogram, together with automatically computed spot totals of absolute radioactivity. Mechanical construction details and schematic electronic circuits are presented together with performance data.
    No preview · Article · Dec 1970 · Journal of Chromatography A