Modification of alkaline phosphatases by treatment with glycosidases

The tissue-specific variants of alkaline phosphatase that are characteristic of human liver and bone are believed to possess identical protein cores; nevertheless, they differ in certain properties such as electrophoretic mobility and stability to heat. Their electrophoretic mobilities are modified by digestion with various glycosidases. Furthermore, the difference in heat stability between them is reduced by treatment with a glycosidase preparation from Trichomonas foetalis. These results are consistent with the view that these enzyme variants differ only in their carbohydrate moieties.

Tartrate-resistant acid phosphatase in human alveolar macrophages

Tartrate-resistant acid phosphatase has been extracted from human alveolar macrophages, in which its specific activity is 10-fold that in whole lung. The apparent identity of the alveolar macrophage isoenzyme with that associated with osteoclasts suggests that both types of cell belong to the mononuclear phagocyte system. Within this system, expression of tartrate-resistant acid phosphatase appears to accompany certain kinds of differentiation.

Tartrate-resistant acid phosphatase of human lung: apparent identity with osteoclastic acid phosphatase

Extracts of human lung tissue contain appreciable activities of a tartrate-resistant acid phosphatase which is apparently identical with the analogous enzyme in bone extracts, with respect to electrophoretic mobility, apparent molecular weight (ca. 37,000), Michaelis constants and relative rates of hydrolysis of various substrates. The acid phosphatase appears to be a constituent of alveolar macrophages. Lung provides a convenient source for the preparation of tartrate-resistant acid phosphatase.

Interpretation of changes in the activity of creatine kinase MB isoenzyme in serum after coronary artery bypass grafting

Measurement of CK-MB in the sera of patients undergoing coronary artery bypass grafting shows a significant increase above pre-operative levels in all cases. However, the timing of the peak post-operative activity and its level allow criteria to be proposed which differentiate between two classes of patients: those with myocardial infarction or lesser myocardial damage, in whom peak activities are seen in specimens taken 21 hours after operation; and those in whom peak activities are found in specimens taken 4-7 hours after operation, presumably reflecting reversible myocardial changes. Activity peaks of more than 50 U/l occurring at 21 hours are considered to support a diagnosis of myocardial infarction.

Alkaline phosphatase isoenzymes

The human alkaline phosphatases constitute a system of multiple molecular forms of enzymes in which heterogeneity is partly due to genetic factors and partly to posttranslational modifications. Recognition of the nature and occurrence of these multiple forms has made a significant contribution both to the understanding of changes in alkaline phosphatase values for serum in disease and to the use of alkaline phosphatase measurements in diagnosis. Many of the diagnostic advantages of alkaline phosphatase isoenzyme analysis can be obtained with the aid of qualitative methods such as zone electrophoresis. However, quantitative methods are needed to take full advantage of the potential benefits of isoenzyme analysis. Selective inactivation methods can be applied successfully to the quantitative analysis of bone and liver alkaline phosphatases in serum. However, the aim of future research should be to remove the limitations at present imposed on quantitative analysis by the close similarities of bone and liver alkaline phosphatases.

A variant alkaline phosphatase in renal cell carcinoma

We report a case of renal cell carcinoma in which up to 32% of the abnormally increased alkaline phosphatase activity in serum was contributed by a variant alkaline phosphatase originating in the primary tumor and its secondary deposits. The variant enzyme was probably an altered form of normal renal alkaline phosphatase. The rest of the alkaline phosphatase activity in the serum was of hepatic origin, but no abnormality of the liver was discovered at autopsy.

A variant alkaline phosphatase in renal cell carcinoma

We report a case of renal cell carcinoma in which up to 32% of the abnormally increased alkaline phosphatase activity in serum was contributed by a variant alkaline phosphatase originating in the primary tumor and its secondary deposits. The variant enzyme was probably an altered form of normal renal alkaline phosphatase. The rest of the alkaline phosphatase activity in the serum was of hepatic origin, but no abnormality of the liver was discovered at autopsy.

Activity of creatine kinase in sera from healthy women, carriers of Duchenne muscular dystrophy and cord blood, determined by the "European" recommended method with NAC-EDTA activation

Creatine kinase activity has been measured at 37 degrees C in sera from healthy women, carriers of Duchenne muscular dystrophy and cord blood, with activation by N-acetyl cysteine (NAC) and EDTA as recommended by several European committees on standardisation. The upper limit of the reference range for healty women was found to be 170 U/l. The distributions of creatine kinase activities in healthy and carrier women have been used to calculate probability of carrier status as a function of creatine kinase activity. Although the range of creatine kinase activities in normal cord blood is wide, the data provide a basis for interpretation when Duchenne muscular dystrophy is suspected.

Malabsorption and macroamylasemia. Response to gluten withdrawal

A 36 year old woman presented with malabsorption and macroamylasemia. The macroamylase was characterized and shown to be a complex of pancreatic amylase and immunoglobulin A(IgA). The patient had the clinical and histologic features of adult celiac disease, and responded to a gluten-free diet. The macroamylase complex disappeared from the serum after gluten withdrawal, a hitherto unreported finding in the syndrome of malabsorption and hyperamylasemia.

Methodological principles in the enzymatic determination of substrates illustrated by the measurement of uric acid

The enzymatic method of Haeckel for the determination of uric acid in serum has been used to compare three different kinetic approaches with the corresponding equilibrium (end-point) procedure. The kinetic methods were: measurement of the difference in absorbance between two pre-selected fixed instants during the course of the reaction under first-order conditions; measurement of the initial rate of reaction at substrate concentrations sufficiently low for first-order kinetics to apply, and determination of initial rate with substrate concentrations approximating to, or greater than, the Michaelis constant (pseudo-zero order kinetics). In the third method results were obtained by solving the Michaelis-Menten equation. The results emphasise the superiority of the two-point kinetic approach, which is apparent even when the timed absorbance values are obtained from an analogue signal displayed on a recorder chart. Conditions are described for the determination or uric acid in serum according to this principle.

Comparison of radioactive peptides obtained from specifically labelled human renal and placental alkaline phosphatases

Peptides with different chromatographic and electrophoretic properties were obtained from human placental and renal alkaline phosphatases by tryptic digestion of the enzymes labelled with radioactive orthophosphate at their active centres. These results provide structural evidence for the distinct genetic origins of the two isoenzymes that had previously been inferred from their different properties and from the observed phenotypic variation of placental phosphatase.

Electrophoretic patterns of gamma-glutamyltransferase activity eluted from liver tissue

Up to three zones of gamma-glutamyltransferase activity were present in 89 samples of human serum after agarose-gel electrophoresis at pH 8.6. Their mobilities relative to albumin were zero, 0.3--0.5, and 0.7--0.9. Incubation of human liver tissue in serum increased the activity of the zones with zero and 0.7--0.9 mobilities, and transiently, of the zone of intermediate mobility. More prolonged incubation caused the intermediate zone to decline, and produced new zones of mobility greater than that of albumin which were not seen in native sera. The mobility of partially-purified liver gamma-glutamyltransferase incubated in serum or protein-free solutions was 0.7--0.8. The intermediate zone was not produced when liver tissue was incubated in protein-free solutions, nor with the purified enzyme in serum or protein-free solutions. The possible relevance of these observations to the electrophoretic patterns of gamma-glutamyltransferase in pathological sera is discussed.

Selective effects of clofibrate on alkaline phosphatase isoenzymes in serum

Administration of clofibrate to both hyperlipidaemic patients and normolipidaemic subjects produced a significant decrease, averaging 22%, in serum alkaline phosphatase activity. Quantitative isoenzyme analysis showed that this change was entirely attributable to an average reduction of 39% in the activity of liver alkaline phosphatase, and that no significant change in the bone isoenzyme occurred. An accompanying fall in serum gamma-glutamyltransferase activity was seen in some subjects but this change was not statistically significant in the group as a whole.

A comparison of reaction conditions for the automated determination of gamma-glutamyltransferase activity in serum

The methods of Rosalki and Tarlow and the Scandinavian Committee on Enzymes for the determination of gamma-glutamyltransferase activity in serum have been compared, with an automatic reaction-rate analyzer in which the reaction is initiated by the addition of a concentrated solution of gamma-glutamyl-p-nitroanilide. Results are approximately 4% lower by the Scandinavian method, because of its lower substrate concentration. However, both methods are of comparable reproducibility. The greater stability of the more dilute substrate solution specified in the Scandinavian method has been confirmed, but attempts to stabilize solutions of gamma-glutamyl-p-nitroanilide at the higher concentrations recommended by Rosalki and Tarlow by the addition of organic solvents were accompanied by some enzyme inhibition. The comparative instability of the substrate solutionof Rosalki and Tarlow is unlikely to lead to erroneous results; however, the Scandinavian formulation offers the advantage of a more economical use of reagents, at the expense of a small and probably unimportant reduction in sensitivity.

A fluorescent artefact resembling BB-creatine kinase in sera of patients with prostatic disease

A fluorescent zone with mobility towards the anode almost equal to that of human BB-creatine kinase has been detected after electrophoresis on cellulose acetate of sera from each of 28 patients with prostatic carcinoma. The zone is not due to the BB isoenzyme and its appearance does not depend on the presence of substrates of creatine kinase. It therefore appears to be a further example of a fluorescent artefact resembling a creatine kinase ieoenzyme. These observations indicate a need for caution in assessing the possible value of BB-creatine kinase in patients with prostatic disease.

Analytical subcellular fractionation studies on different cell types isolated from normal rat liver

1. Parenchymal, Kupffer and biliary tract cells were isolated from normal rat liver by perfusion with collagenase solution. 2. The specific activities (munits of enzyme activity/mg of protein) of marker enzymes for the principal subcellular organelles were determined in the isolated cell homogenates and compared with whole liver homogenates. 3. The cells were disrupted and the extracts subjected to analytical subcellular fractionation by sucrose-density-gradient centrifugation. Lysosomal integrity was determined by assaying latent beta-N-acetylglucosaminidase in the extracts. 4. Similar subcellular distributions were found for lysosomal, endoplasmic reticulum and plasma membrane marker enzymes in the whole liver and in parenchymal and biliary tract cells. In Kupffer cells, the proportion of these enzymes in the cytosol was significantly increased compared with the other fractions. In addition the equilibrium densities of the various organelles in these cells were lower than those from parenchymal cells.