Einflu? von Natriumehlorid auf den Abbau von Adenosintriphosphat und Glykogen im zerkleinerten Rindermuskelpost mortem

Zusammenfassung Ein Zusatz von 2% Natriumchlorid zu unmittelbar nach dem Schlachten zerkleinertem Rindermuskel bewirkt eine Beschleunigung des post-mortem-Abbaues von Adenosintriphosphat (ATP) zu Inosiumonophosphat, eine raschere Spaltung von Adenosindiphosphat, eine beschleunigte Freisetzung von anorganischem Phosphat und eine Verzögerung der Bildung von Hypoxanthin. Erhöhung des NaCl-Zusatzes von 2% auf 4% verstärkt diese Wirkung.Als Ursache für diese Wirkung von NaCl kommt eine Aktivierung der ATPasen des sarkoplasmatischen Reticulums und des Sarkolemms durch Na⁺-Ionen, eine Aktivierung der 5-Adenyl-säure-aminohydrolase durch NaCl oder eine verstärkte Freisetzung von Ca⁺⁺-Ionen aus dem sarkoplasmatischen Reticulum durch Austausch gegen Na in Betracht. Am wahrscheinlichsten ist die letztere Mbglichkeit.Ein Zusatz von 2% NaCl zum zerkleinerten Prae-rigor-Muskel beeinflußt die Geschwindigkeit der Umwandlung von Glykogen zu Lactat innerhalb der ersten 6 Std post mortem nicht; darnach tritt eine Hemmung des Glykogenabbaues und der Lactatbildung ein. Diese Wirkung wird durch Erhöhung des NaCl-Zusatzes auf 4% verstärkt. Der Einfluß von NaCl auf die pH-Veränderungen post mortem entspricht der Wirkung des Salzes auf die Lactatbildung. Die Bildung von Glucose-6-phosphat post mortem wird durch NaCl etwas gehemmt. Eine wesentliche Hemmung der Enzymaktivitäten durch NaCl scheint jedoch erst in späteren Stadien der Glykolyse einzutreten. Nur 70% des abgebauten Glykogens werden in Lactat umgewandelt.

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Influence of sodium chloride on the break-down of adenosine triphosphate and glycogen in ground beef muscle postmortem

Summary Addition of 2% sodium chloride to ground pre-rigor beef muscle causes an increase in the rate of break-down of adenosine triphosphate (ATP) to inosine monophosphate, a faster break-down of adenosine diphosphate, a faster increase in inorganic phosphate and a slower formation of hypoxanthin. Increasing the NaCl concentration from 2% to 4% enhances these effects.The following influences could be responsible for this effect of NaCl: (1) activation of the ATPases of the sarcoplasmic reticulum and sarcolemma by Na+ ions; (2) activation of 5'-adenylic acid-aminohydrolase by NaCI ; (3) enhanced release of Ca++ions from the sarcoplasmic reticulum by exchange against Na+. The last effect seems to be the most probable.Addition of 2% NaCl to ground pre-rigor muscle does not influence the rate of transformation of glycogen into lactate within the first 6 hours post mortem. After this period, NaCl has an inhibiting effect on the break-down of glycogen and the formation of lactate. This effect is enhanced by increasing the NaCl concentration up to 4%. The effect of NaCl on the change in pH post mortem reflects the influence of the salt on the formation of lactate. NaCl also causes some inhibition of the formation of glucose-6-phosphate post mortem. The main inhibition of enzymes by NaCl, however, seems to occur during the later stages of glycolysis. Only about 70% of the glycogen, which was broken-down, is metabolized to lactate.

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Diese Arbeit wurde durch Mittel des Forschungskreises der Ernährungsindustrie e.V. unter Beteiligung des Verbandes der Deutschen Fleischwaren- und Feinkostindustrie e.V. unterstützt.     

Thin-layer chromatography and mass spectrometry coupled using desorption electrospray ionization

Desorption electrospray ionization (DESI) was demonstrated as a means to couple thin-layer chromatography (TLC) with mass spectrometry. The experimental setup and its optimization are described. Development lanes were scanned by moving the TLC plate under computer control while directing the stationary DESI emitter charged droplet plume at the TLC plate surface. Mass spectral data were recorded in either selected reaction monitoring mode or in full scan ion trap mode using a hybrid triple quadrupole linear ion trap mass spectrometer. Fundamentals and practical applications of the technique were demonstrated in positive ion mode using selected reaction monitoring detection of rhodamine dyes separated on hydrophobic reversed-phase C8 plates and reversed-phase C2 plates, in negative ion full scan mode using a selection of FD&C dyes separated on a wettable reversed-phase C18 plate, and in positive ion full scan mode using a mixture of aspirin, acetaminophen, and caffeine from an over-the-counter pain medication separated on a normal-phase silica gel plate.     

Mechanical tests on the surface-coated Bi-2212 superconducting tapes

The strain dependence of the critical current of surface-coated Bi-2212 tapes is reported. Two methods are used in the measurements. The effect of bend strain on the critical current is obtained by a stepped cone apparatus. Peak stress or strain dependence of the critical current and the effect of the number of strain cycles on the critical current is also studied on multiple samples by employing a new in situ stress/strain device. The results show that the number of strain cycles does not significantly affect the critical current. Rather, the critical current of the tape depends only on the level of peak strain.     

A method to determine the local surface profile from reconstructed exit waves

Reconstructed exit waves are useful to quantify unknown structure parameters such as the position and composition of the atom columns at atomic scale. Existing techniques provide a complex wave in a flat plane which is close to the plane where the electrons leave the atom columns. However, due to local deviation in the flatness of the exit surface, there will be an offset between the plane of reconstruction and the actual exit of a specific atom column. Using the channelling theory, it has been shown that this defocus offset can in principle be determined atom column-by-atom column. As such, the surface roughness could be quantified at atomic scale. However, the outcome strongly depends on the initial plane of reconstruction especially in a crystalline structure. If this plane is further away from the true exit, the waves of the atom columns become delocalized and interfere mutually which strongly complicates the interpretation of the exit wave in terms of the local structure. In this paper, we will study the delocalization with defocus using the channelling theory in a more systematic way.     

Note: Temperature derivative of the refractive index of binary mixtures measured by using a new thermodiffusion cell

A thermodiffusion cell is developed for performing Soret experiments on binary mixtures at high pressure and in the presence of a porous medium. The cell is validated by performing experiments at atmospheric pressure. The experiments are performed by applying different temperature gradients to binary mixtures in order to determine their thermal contrast factor. These measurements provide a first demonstration of the good reproducibility of this kind of measurements upon calibration.     

CO_2/PS等静压微孔发泡研究

对CO_2与PS在高压设备中进行等静压处理的微孔发泡进行了研究。结果表明,改变CO_2的压力可以控制发泡的泡孔密度和泡孔大小。增加等静压的压力和PS中CO_2的浓度,可以提高泡孔的密度、减小泡孔的直径。结合CO_2的扩散及释压发泡,获得了CO_2在PS中扩散过程的数据,采用剩余界面法得出了CO_2在PS中的扩散厚度与扩散时间的关系。根据CO_2在PS中解吸附的特征,对泡沫不发泡皮层的厚度控制也进行了研究。     

Laboratory techniques for evaluating solid oxide fuel cells

The construction of a small solid oxide fuel cell laboratory is described in terms of required materials, measuring techniques and equipment design. Details of various electrode deposition techniques and ways of making contacts to the electrodes are also outlined.     

Electrolysis of MgCl2 with a top inserted anode and an Mg-Pb cathode

High energy consumption in the production of magnesium by molten salt electrolysis is mainly due to the recombination of magnesium and chlorine. The large interelectrode distance used, in conventional techniques, to reduce the extent of back reaction, results in a significant potential drop. A laboratory cell that enables the operation with smaller interelectrode distance and easy separation of electrode products has been used to study electrolytic magnesium production. The cell features a top inserted graphite anode and a Mg-Pb alloy cathode at the bottom. Current efficiency and power consumption were determined at 690° C using a current density of 0.48 A cm^–2. Experiments were performed to study the effects of MgCl₂ concentration and anode-cathode distance (a.c.d.) on cell operation. Results indicated that an electrolyte containing 20% MgCl₂ (equiweight NaCl:KCl and 1 % NaF) with a 3 cm a.c.d. reduced the cell voltage to 3.72 V. This value corresponds to an energy consumption of 11.3 kWh kg^–1 including the refining of Mg-Pb alloy produced at the cathode. This cell performance is more energy efficient compared to conventional magnesium cells.     

Structure-activity studies of human tumour necrosis factors

The mechanism by which tumour necrosis factors (TNF and lymphotoxin,also called TNFß and TNFß respectively) exerttheir cytotoxic activity on many malignant cells, remains largelyunknown. Furthermore, the broad array of differentiation (geneinduction) and mitogenic activities towards many primary cellsis still a subject of intensive investigation. TNF is an importantmediator in inflammation, immune responses and infection-relatedphenomena and these activities contribute to the severe toxidtyseen when TNF is used as an anticancer agent. The first stepin the mechanism of action is the specific binding of the ligandto its receptors and dissection of the molecular mechanism involvedin this interaction is the subject of this review. The reasonsfor the interest in this aspect are obvious: first, the developmentof strong antagonistic TNF analogues can be useful in dampeningthe potentially lethal or debilitating effects of an overproductionof the cytokine (as in septic shock or rheumatoid arthritis).Secondly, since two distinct TNF receptors exist, constructionof TNF muteins that distinguish between both types may leadto derivatives of this plekrtropic agent with a more restrictedbiological activity pattern. Ideally, one would like to developa TNF mutant that has retained its cytotoxic action on tumourcells without inducing the deleterious systemic toxteity. Suchan optimized TNF molecule could become a potent anticancer agent     

THE DEVELOPMENT OF HIGH INTENSITY GAS-LIQUID JET REACTORS

A novel type of gas-liquid contactor was researched and developed to enhance phase mixing. These high velocity impinging stream reactors are characterised by small reactor volumes supplied with nozzles, which are directed towards each other. The gas and liquid feed streams are jetted through the nozzles into the reactor volume, resulting in a highly turbulent mixture of the phases. Under these enhanced mixing conditions, mass transfer rates are increased dramatically. A mechanism for bubble formation and breakup in gas —liquid jet reactors. operated in the bubble mode, is proposed and a design philosophy of such reactors is also formulated.