Ellen Schmidt

Isoenzymes of malic dehydrogenase, glutamic oxaloacetic transaminase and lactic dehydrogenase in serum in diseases of the liver

Abstract A simplified chromatographic method was used for quantitative determination of the isoenzyme activities of glutamic oxaloacetic transaminase (GOT), malic dehydrogenase (MDH) and lactic dehydrogenase (LDH) in the sera of 10 healthy individuals and 92 patients with liver disease. While mitochondrial GOT (M-GOT) was not demonstrated in the serum of the normal controls, there was evidence of mitochondrial MDH (M-MDH). The percentage of “liver”-LDH (LDH-5) was in agreement with data published by others. In liver disease, the most significant changes in isoenzyme relations have been found to occur in acute hepatitis, where the M-GOT activity slightly exceeded that of the mitochondrial enzyme glutamic dehydrogenase (GLDH). Considering the appreciable shorter half-life of M-GOT in serum noted in experimental studies on animals, it would appear from these results that M-GOT is released from the damaged cells at a much higher and more rapid rate than is true for the GLDH. The longer half-life of M-MDH may help to explain the significantly high fractions of this isoenzyme in serum which are also found in receding hepatitis. Thus, the varying behaviour of the mitochondrial enzymes GLDH, M-GOT, and M-MDH in serum suggests that isoenzyme determinations describe more precisely the extent and the type of mitochondrial damage in liver disease.

Glutamate dehydrogenase: biochemical and clinical aspects of an interesting enzyme

The molecular properties and possible metabolic functions of glutamate dehydrogenase (GLDH-EC 1.4.1.3) are described. The distribution of this enzyme in the body and particularly in the liver are outlined. The significance of these properties for GLDH release into the extracellular space, for the distribution and elimination of the enzyme and, foremost, for the assay of GLDH as a diagnostic indicator of hepatic and biliary disease are shown. Analytical methods are reviewed.

Enzymspiegel im Serum bei körperlicher Arbeit und ambulanten Patienten

ZusammenfassungDie Untersuchungen der Aktivitäten von Aldolase, Pyruvat-Kinase, Lactat-Dehydrogenase, Glutamat-Oxalacetat-Transaminase, Glutamat-Pyruvat-Transaminase und Malat-Dehydrogenase im Serum nach körperlicher Arbeit (Fahrrad-Ergometer) ergaben nach kurzfristigen Belastungen keine sicheren Veränderungen, eher einen geringen Abfall der Enzymaktivitäten. Ein deutlicher Anstieg der Enzymaktivitäten im Serum wurde erst nach langdauernder Arbeit (2–5 Std bei 50 Watt) erzielt.Auf Grund dieser Ergebnisse ist es unwahrscheinlich, daß die gegenüber der Norm gering vermehrten Aktivitäten von Glutamat-Oxalacetat-Transaminase, Glutamat-Pyruvat-Transaminase und Lactat-Dehydrogenase im Serum bei einer Gruppe von etwa 100 ambulanten Patienten ohne sicheren pathologischen Befund auf die relativ größeren Arbeitsbelastungen vor der Enzymaktivitätsbestimmung zurückgeführt werden können.Die Ergebnisse werden mit den Angaben anderer Autoren verglichen und ausführlich diskutiert.Die Untersuchungen der Aktivitaten von Aldolase, Pyruvat-Kinase, Lactat-Dehydrogenase, Glutamat-Oxalacetat-Transaminase, Glutamat-Pyruvat-Transaminase und Malat-Dehydrogenase im Serum nach korperlicher Arbeit (Fahrrad-Ergometer) ergaben nach kurzfristigen Belastungen keine sicheren Veranderungen, eher einen geringen Abfall der Enzymaktivitaten. Ein deutlicher Anstieg der Enzymaktivitaten im Serum wurde erst nach langdauernder Arbeit (2–5 Std bei 50 Watt) erzielt.

An improved simple chromatographic method for separating the isoenzymes of malic dehydrogenase and glutamic oxaloacetic transaminase

Abstract A method for serial separation of the two isoenzymes of malic dehydrogenase (MDH) and glutamic oxaloacetic transaminase (GOT) by chromatography on DEAE-Sephadex is described. It can also be used successfully for separation of lactic dehydrogenase fraction 5 (LDH-5) from the other LDH isoenzymes. The distribution of the total activities of those enzymes among their isoenzymes, is reproducible within narrow limits. By rechromatography, the individual fractions have been shown to be uniform. The percent distribution for rat liver which has been established by this method (62% cytoplasmic (C-)MDH/38% mitochondrial (M-)MDH and 21% cytoplasmic (C-)GOT/79% mitochondrial (M-)GOT) is in good agreement with the distribution of enzyme activity over the two large cell compartments of the liver cell obtained by other methods.

Sex differences of plasma cholinesterase in the rat.

Plasma cholinesterase activity of adult female HAN-Wistar rats was found to be 5.5-fold higher than that of adult male rats kept under constant specified pathogen-free (SPF) conditions up to their 870th day of life.

Isozyme und Veränderungen der Isozym-Verteilung von Malat- und Isocitrat-Dehydrogenase und Glutamat-Oxalacetat-Transaminase in der normalen und pathologisch veränderten tierischen und menschlichen Leber

ZusammenfassungDie Isozyme von Malat- und Isocitrat-Dehydrogenase und Glutamat-Oxalacetat-Transaminase lassen sich auch in isolierten Leber-parenchymzellen nachweisen. Ihre Verteilung auf cytoplasmatischen und mitochondrialen Raum oder auf chromatographisch getrennte C- und M-Isozyme zeigt Unterschiede zwischen der Rattenleber und der menschlichen Leber. Bei der akuten CCl4-Intoxikation der Ratte kommt es zu einem stärkeren Verlust der cytoplasmatischen Isozyme. Erst bei chronischer Thioacetamid-Vergiftung wird eine deutliche Abnahme der M-Isozyme nachweisbar, wie sie sich in der menschlichen Leber bei akuter Hepatitis findet.Bei anderen Lebererkrankungen mit geringer ausgeprägter Zellschädigung konnte bisher keine deutliche Veränderung der C-/M-Isozym-Relationen von GOT und MDH nachgewiesen werden.Weitere Untersuchungen müssen zeigen, ob der beobachtete geringe Anstieg schwerer eluierbarer Lactat-Dehydrogenase-Fraktionen relevant ist.SummaryThe isozymes of malate and isocitrate dehydrogenase and glutamate oxalacetate transaminase can also be detected in isolated liver parenchymal cells. Their distribution to the cytoplasmic and mitochondrial spaces or to chromatographically separated C(ytoplasmic) and M(itochondrial) isozymes shows differences between the rat liver and the human liver.The acute CCl4 intoxication of the rat leads to a mayor loss of C-isozymes. Only in the case of chronic thiaocetamide poisoning can a distinct decrease in M-isozyme be detected, as found in the human liver in acute hepatitis. In other liver diseases with less pronounced cell damage, up to now it has not been possible to prove any distinct alteration of the C/M isozyme relations of GOT and MDH. Further investigations will have to show, whether the observed slight increase of more difficultly eluable lactate dehydrogenase fractions is relevant.

Optimale Bedingungen zur Bestimmung der Transaminasen und der Kreatin-Phosphokinase im Serum und ihre Konsequenzen für die Diagnostik

After discussion of the practical difficulties in establishing optimum conditions for the determination of enzyme activities in serum, improved methods are described for the assay of glutamic oxalacetic transaminase (EC 2.6.1.1), glutamic pyruvic transaminase (EC 2.6.1.2) and creatine phosphokinase (EC 2.7.3.2) in serum and the normal ranges of the 3 enzymes in serum of adults with these methods are presented. For both transaminases the ratios of improved assay to conventional assay methods and data on the effect of temperature and the addition of pyridoxal-5-phosphate are given. The satisfying in-vitro stability of the 3 enzymes is shown. Finally, the consequences of the improved conditions of assay for diagnostic use are discussed. The opportunity of combining an impending variation of methods with their standardization is. stressed.ZusammenfassungNach Darlegung der praktischen Schwierigkeiten, zu optimalen Meß-bedingungen für Enzymaktivitäten im Serum zu gelangen, werden Verbesserungen der Methodik für die Bestimmung von Glutamat-Oxalat-Transaminase (EC 2.6.1.1), Glutamat-Pyruvat-Transaminase (EC 2.6.1.2) und Kreatin-Phosphokinase (EC 2.7.3.2) im Serum und die mit dieser Methodik ermittelten Normalbereiche, Temperaturfaktoren und für die Transaminasen Umrechnungsfaktoren vom konventionellen zum verbesserten Test angegeben, sowie der Effekt des Pyridoxal-5-phosphatzusatzes gezeigt. Die befriedigende in vitro-Stabilität aller drei Enzymaktivitäten wird beschrieben. Schließlich werden an Beispielen die Konsequenzen der Verbesserung der Meßbedingungen für die Enzymdiagnostik diskutiert und die günstige Gelegenheit, eine methodische Änderung dieser Routinemethoden mit einer Standardisierung zu verbinden, hervorgehoben.

Diagnostic application of mitochondrial enzymes and isoenzymes

Evolutionary, topological and metabolic aspects of mitochondrial enzymes and isoenzymes are reviewed, and the structural and functional heterogeneity of mitochondria is demonstrated. Primary deficiencies of mitochondrial enzymes are described and the need for their proper recognition is illustrated. Species differences of secondary dysfunction of mitochondrial enzymes are shown. The release of mitochondrial enzymes is compared to that of cytosolic enzymes from liver and heart muscle cells and the diagnostic significance of assays of mitochondrial enzymes in serum is evidenced. Possible mechanisms of mitochondrial enzyme release from cells and unresolved questions pertaining to this process are discussed in light of potential diagnostic utility of mitochondrial enzymes in serum.

The SZASZ-ratio (CK/GOT) as Example for the Diagnostic Significance of Enzyme Ratios in Serum * **

ZusammenfassungDie diagnostische Bedeutung von Enzym- und Isoenzym-Relationen im Serum beruht auf Verteilungs-Unterschieden auf verschiedenen Ebenen: Von Organen bis zu subcellulären Strukturen. Modifizierende Faktoren bestehen in den molekularen Eigenschaften der Enzyme und Isoenzyme und in ihrem Umsatz in den Zellen und im Extracellular-Raum. Diese pathophysiologischen Voraussetzungen werden für den Szasz-Quotienten CK/GOT dargestellt und seine Anwendung in der Differential-Diagnose des Herzinfarktes kritisch untersucht.SummaryThe diagnostic significance of enzyme and isoenzyme ratios in serum relies on their different distribution at various levels: from organs to subcellular structures. Factors which modify the ratios are the molecular properties of enzymes and isoenzymes and their turnover in the cells and in the extracellular space. These pathophysiological principles are considered with respect to the Szasz ratio CK/GOT and its application for the differential diagnosis of acute myocardial infarction.

Enzyme Patterns in Liver Failure

The determination of 29 enzyme activities in human liver tissue taken immediately after death from liver failure showed a loss of specific functions in favor of pathways which predominate in fetal or neoplastic cells. The determination of cellular and plasma-specific enzymes in serum before and during hepatic failure showed that the impaired synthesis capacity of the liver is reflected in the patterns of both groups of enzymes in serum. In acute viral hepatitis, the prognostic value of plasma-specific enzymes is better than that of cellular enzymes in serum, while in coma, success of hemo-perfusion could be better predicted by determination of the latter. Immediately after liver transplantation, liver-specific cell enzymes, and later, plasma-specific enzymes in serum, can be used to estimate the condition of the liver and the patient’s chance of survival. The ratio CHE/GPT in serum is proposed as a prognostic index.