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Biomedical subjects

A Betz

Publications and source records attributed to A Betz.

At least 91 records · Page 5Linked to original sources
PubMed1982

[Wound infection and its treatment in accident surgery].

A so-called atraumatic operative technique is required to prevent post-traumatic wound infection. Especially in open fractures, closing a wound can lead to infection despite tension at the wound edges. Postoperative hematomas may also lead to infection, whereupon a further operation is necessary. Palliative treatment of the acute stages of infection consists in immediate evacuation, drainage and careful débridement. The wound must be closed without dead space remaining, but this proves impossible the dead space may be filled with a vascularized pedicle graft from adjacent muscle. The treatment of chronic infection, often accompanied by loss of skin and bone substance, has been improved by microsurgical techniques that allow the combination of autogenous bone grafting with vascularized musculocutaneous flap transplantation. Acute empyema requires early synovectomy.

Accidents↗
PubMed1982

Flux regulation in glycogen-induced oscillatory glycolysis in cell-free extracts of Saccharomyces carlsbergensis.

To localise the controlling point of the glycolytic system, the temporal changes in concentrations of glycolytic intermediates have been analysed after addition of glycogen to a substrate-depleted yeast extract. Three sequential metabolic states are clearly observable: a transition state at which there is continuous accumulation of the intermediates before the glyceraldehydephosphate dehydrogenase (GAPDH, EC 1.2.1.12) step; a stationary state with all glycolytic intermediates having concentrations oscillating at nearly stationary mean values; and a depletion state at which the intermediates before the GAPDH step are being depleted due to the exhaustion of glycogen. In all these states, the mean ethanol production rate and the concentration of ATP and the intermediates beyond the GAPDH-step are maintained fairly constant, while the glycogen consumption rate and intermediate concentrations of the upper part of the glycolytic system changes considerably: the glycogen consumption rate varies 4-fold and fructose-bis-phosphate concentration more than 10-fold. Doubling of the initial glycogen concentration and the addition of a great excess of fructose-bis-phosphate do not affect the ethanol production rate and the mean glycerate-3-phosphate (3-PGA) and pyruvate levels. By contrast, ethanol production was accelerated by an increase of the net ATP consumption rate resulting from either the addition of apyrase or by substitution of trehalose for glycogen. Neither the mean absolute ATP level nor the adenylate energy charge were measurably affected, however, all this data can be interpreted in terms of a very strong stoichiometric regulation and stabilization of the lower part of the glycolytic system.

Adenosine Triphosphate↗
PubMed1979

Partial purification, substrate specificity and regulation of alpha-L-glycerolphosphate dehydrogenase from Saccharomyces carlsbergensis.

alpha-L-Glycerolphosphate dehydrogenase (sn-glycerol-3-phosphate:NAD+ 2-oxidoreductase, EC 1.1.1.8) from Saccharomyces carlsbergensis was purified 400-fold. The enzyme preparation is free of interfering activities, such as glyceraldehyde phosphate dehydrogenase, alcohol dehydrogenase, triose phosphate isomerase and glycerolphosphatase. At pH 7.0 it is specific for NADH (Km = 0.027 mM with 0.8 mM dihydroxyacetone phosphate) and dihydroxyacetone phosphate (Km = 0.2 mM with 0.2 mM NADH). Between pH 5.0 and 6.0 the enzyme functions with NADPH, but only at 7% of the rate with NADH. Various anions (I- greater than SO42- greater than Br- greater than Cl-) act as inhibitors competing with the substrate dihydroxyacetone phosphate. Inorganic phosphate (Ki = 0.1 mM), pyrophosphate and arsenate are strong inhibitors. The nucleotides ATP and ADP are also inhibitory, but their action seems to be of the same type as the general anion competition (Ki = 0.73 mM for ATP). The results are consistent with the notion that the enzyme may regulate the redox potential of the NAD+/NADH couple during fermentation.

Adenine Nucleotides↗
PubMed1978

Fermentative Metabolism of Hydrogen-evolving Chlamydomonas moewusii.

The anaerobic metabolism of Chlamydomonas moewusii under both light (160 lux) and dark conditions has been examined using manometric and enzymic techniques. During anaerobiosis starch is broken down to glycerol, acetate, ethanol, CO(2), and H(2). The release of CO(2) and H(2) comes to an end when the starch pool is depleted.There are only slight differences in the ratio of the end products of fermentation between light and dark metabolism. In the light, glycerol production is diminished and H(2) evolution is enhanced, whereas the production rate of all other end products generally does not change.

Journal Article↗
PubMed1975

Allosteric activation and competitive inhibition of yeast phosphofructokinase by d-fructose.

Purified phosphofructokinase from bakers yeast is activated by D-fructose in low concentrations (up to 1 mM) and inhibited by high concentrations. The stimulatory effect of D-fructose is similar, but smaller than that of AMP. In the presence of AMP (0.4 mM or higher) D-fructose does no longer stimulate, but its inhibitory effect persists (KI = 8 mM). Its dualistic action on phosphofructokinase activity indicates that D-fructose might induce low frequency in glycolytic oscillations by direct interaction with the enzyme.

Adenosine Monophosphate↗
PubMed1975

The response of oscillating glycolysis to perturbations in the NADH/NAD system: a comparison between experiments and a computer model.

The glycolytic pathway is described by a set of coupled non linear differential equations of first order with respect to time. The individual terms of these equations consist of enzyme velocities assuming a steady state hypothesis for the enzymatic forms. These are specified and the system is solved numerically. Oscillations are explained by interaction of PFK with the adenylate system. The conditions for the occurrence of oscillations are tested in a series of computer runs. The phase relations between intermediates of the model agree with those found in yeast cells. As an application of the model the disturbation of oscillations by the addition of acetaldehyde is simulated. The predictions of the model agree with experimental results.

Acetaldehyde↗