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Biomedical subjects

D W Moss

Publications and source records attributed to D W Moss.

At least 19 recordsLinked to original sources
PubMed1992

Changes in enzyme expression related to differentiation and regulatory factors: the acid phosphatase of osteoclasts and other macrophages.

Human tartrate-resistant Type 5 acid phosphatase is a unique isoenzyme encoded by a gene located on chromosome 19. It is a member of a widely-distributed and structurally highly-conserved group of iron-containing proteins. It is normally expressed in certain tissue macrophages, notably osteoclasts and alveolar macrophages, but is virtually absent from the precursor monocytes. Factors which enhance or inhibit expression of this specific isoenzyme can be studied in monocytes and osteoclasts cultured in vitro. This provides opportunities to develop the use of Type 5 acid phosphatase as a reporter of pathophysiological events and an essential, though not sufficient, role in bone resorption by osteoclasts has been established by such studies.

Acid Phosphatase↗
PubMed1992

Circulating levels of tartrate-resistant acid phosphatase in macrophage-activated lung disease.

Tartrate-resistant acid phosphatase (TrACP) is abundant in alveolar macrophages, suggesting that these cells might contribute to the activity of this isoenzyme in sera of patients with conditions characterized by activation of alveolar macrophages. TrACP was therefore measured in patients with pulmonary sarcoidosis and cryptogenic fibrosing alveolitis and compared with values in controls. Since osteoclasts are known to be the main source of TrACP in serum several indices of bone-turnover were also measured: serum bone-specific alkaline phosphatase and urine hydroxyproline:creatinine ratios. Patients with Paget's disease of bone constituted a reference group presenting increased bone turnover. TrACP was not significantly higher in the lung-disease groups than in controls, although there was a strong positive correlation with angiotensin-converting enzyme in pulmonary sarcoidosis. As expected, TrACP activity was elevated together with the other indices of bone turnover in Paget's disease. It is unlikely that TrACP from alveolar macrophages contributes significantly to serum acid phosphatase activity in lung disease.

Acid Phosphatase↗
PubMed1992

A reference preparation of human prostatic acid phosphatase: purification, characterization and field trials.

Acid phosphatase has been prepared in an apparently pure state by affinity chromatography from human prostatic tissue. When dissolved in an acidic albumin solution, lyophilized and stored at -20 degrees C for up to 2 years, no time-dependent loss of catalytic activity was detectable in the reconstituted material. Accelerated degradation tests also predicted complete stability. A preliminary distribution of the lyophilized preparation to 143 laboratories confirmed its robustness and demonstrated its potential usefulness as a calibrant to unify the results of different methods of measuring acid phosphatase activity.

Acid Phosphatase↗
PubMed1992

Perspectives in alkaline phosphatase research.

Gene cloning and site-directed mutagenesis have had a profound effect on alkaline phosphatase research. Four distinct structural genes encoding placental, intestinal, and tissue-nonspecific isoenzymes have been cloned, sequenced, and mapped to human chromosomes. Differences in properties between the respective gene products are due to variations in primary structure involving only one, or a few, key amino acid residues. Recognition that alkaline phosphatase belongs to the category of molecules that are localized to cell membranes through a COOH-terminal glycan-phosphatidylinositol anchor provides a basis for understanding the generation of isoforms observed in plasma in disease. Isoforms produced by differential cleavage or preservation of the glycan-phosphatidylinositol anchor may offer new correlations with disease that are of diagnostic value. However, a more important contribution of alkaline phosphatase research to clinical chemistry may prove to be an increased understanding of disease processes at the molecular level.

Alkaline Phosphatase↗
PubMed1991

Regulation and expression of type V (tartrate-resistant) acid phosphatase in human mononuclear phagocytes.

Human type V (tartrate-resistant) acid phosphatase belongs to a unique group of iron-binding proteins that includes uteroferrin and other purple phosphatases. The enzyme is normally restricted to osteoclasts and certain phagocytic cells but its rôle is unknown. We show that phosphatase mRNA is abundant in cells of monohistiocytic phenotype and that enzyme expression in cultured human monocyte-derived macrophages is depressed by gamma-interferon and bacterial lipopolysaccharide, agents that promote functional differentiation in these cells. In contrast, phorbol ester, which stimulates intracellular calcium-mediated events, greatly enhances type V phosphatase expression and mRNA abundance. Lymphokine and phorbol ester-modulated expression of type V acid phosphatase expression thus represents a model system for investigating proliferative responses that are specific to cells of the mononuclear macrophage system.

Acid Phosphatase↗
PubMed1990

Type 5 acid phosphatase. Sequence, expression and chromosomal localization of a differentiation-associated protein of the human macrophage.

The purple acid phosphatases and uteroferrin belong to a diverse multifunctional class of binuclear iron-containing proteins that includes haemerythrin and ribonucleotide reductase. In the pig, uteroferrin has been implicated in the delivery of iron to the foetus, but the role of the related human type 5 acid phosphatase that is principally found in resident tissue macrophages is not yet clear. To define further the function of this metalloenzyme, we have isolated and sequenced a cDNA clone for type 5 acid phosphatase and investigated expression of its gene in human tissues. The phosphatase clone contains an open reading frame of 975 bp and encodes a protein of 325 amino acids, including a signal peptide of 19 residues and two potential sites for N-glycosylation. The type 5 acid phosphatase gene mapped to the short arm of human chromosome 19 and was found to have a restriction fragment length polymorphism on digestion with XbaI. Expression of phosphatase mRNA was restricted to mononuclear phagocytes and the enzyme was induced greater than 20-fold on transformation of normal human monocytes to macrophages by culture in serum-supplemented medium. Type 5 acid phosphatase thus represents a tightly regulated system for the study of molecular events in the differentiation programme of the normal macrophage.

Acid Phosphatase↗
PubMed1990

Intracellular regulation of enzyme secretion from rat osteoclasts and evidence for a functional role in bone resorption.

1. Osteoclasts are known to secrete acid phosphatase, an iron-containing phosphohydrolase. We have investigated (a) the possibility that acid phosphatase has a functional role in bone resorption and (b) the factors controlling enzyme secretion from isolated rat osteoclasts. 2. Osteoclasts were freshly disaggregated from neonatal rat long bones and dispersed at low densities on devitalized cortical bone slices or on plastic substrate. The levels of acid phosphatase in culture medium were measured spectrophotometrically using 4-nitrophenyl phosphate as hydrolysable substrate. The total plan area of bone resorbed was quantified by scanning electron microscopy in combination with image processing and analysis. 3. Ninety-three per cent of the total enzyme activity detected in the supernatant exposed to bone-osteoclast preparations was resistant to inhibition by D-tartaric acid and was bound to an antibody known to be highly specific for the osteoclast-derived isoenzyme, showing that it originated from osteoclasts. 4. A diminution in the level of supernatant enzyme activity achieved by incubating bone-osteoclast preparations with an antiserum specifically binding the osteoclast isoenzyme, or with a non-competitive inhibitor, molybdate or with competitive inhibitors, disphosphonates, led to a marked reduction of osteoclastic bone resorption. 5. The rate of the enzyme released into the culture supernatant, whether from resorbing (cultured on bone) or non-resorbing (cultured on plastic) osteoclasts declined gradually over 22 h, but that from the former was significantly depressed within the first 30 min of incubation. The supernatant enzyme concentration increased linearly up to 3 h; the levels released from resorbing osteoclasts remained consistently lower than those from non-resorbing cells. 6. Exposure of osteoclasts for 18 h to elevated [Ca2+]o levels produced a concentration-dependent inhibition of supernatant acid phosphatase levels. In the presence of 20 mM [Ca2+]o enzyme secretion from resorbing osteoclasts was significantly lower than that from non-resorbing cells. 7. Exposure of bone-osteoclast preparations to pertussis toxin produced no significant change of acid phosphatase release, while cholera toxin, dibutyryl cyclic AMP and forskolin produced a marked elevation of enzyme secretion. Ionomycin was found to inhibit enzyme release and this was less marked when osteoclasts were incubated on plastic substrate.(ABSTRACT TRUNCATED AT 400 WORDS)

Acid Phosphatase↗
PubMed1990

The source and significance of raised serum enzymes in rheumatoid arthritis.

Hepatobiliary dysfunction in rheumatoid arthritis has been suggested on the basis of raised serum activity of alkaline phosphatase, 5-nucleotidase, lactic dehydrogenase and gamma-glutamyl transferase, but a specific pathological lesion has not been demonstrated and serum transaminases and bilirubin are almost invariably normal. This paper reports a series of studies designed to determine the tissues of origin of the enzymes and offers an alternative interpretation of the enzymological findings. The results suggest that only alkaline phosphatase originates from the liver, while lactic dehydrogenase and 5-nucleotidase originate from synovial fluid polymorphs and synovial lining cells, respectively. Serum alkaline phosphatase may be induced by inflammatory mediators such as interleukin-1 because it correlates with the acute phase response. Serum lactic dehydrogenase is an integrated measure of polymorph lysis in all joints and offers a marker of joint inflammation more specific than measures such as the ESR. Levels of serum 5-nucleotidase provide information about the activity of the synovium. Finally, because hepatic necrosis does not normally occur, the transaminases may be used to monitor drug toxicity.

5'-Nucleotidase↗
PubMed1985

An enzyme-amplified monoclonal immunoenzymometric assay for prostatic acid phosphatase.

An immunoassay for prostatic acid phosphatase is described in which a high degree of specificity for the prostatic isoenzyme, obtained by the use of monoclonal antibodies, is combined with great sensitivity, made possible by enzyme-amplified measurement of the combination of the isoenzyme with its antibody. The increase in sensitivity thus achieved is of the order of 170 times that of conventional methods of measurement. The advantages of the enzyme-amplified method have been shown to be particularly useful in detecting and monitoring small abnormalities of prostatic acid phosphatase levels in patients with prostatic cancer.

Acid Phosphatase↗
PubMed1979

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.

Alkaline Phosphatase↗
PubMed1979

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.

Electrophoresis, Agar Gel↗
PubMed1979

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.

Adult↗
PubMed1979

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.

Autoanalysis↗
PubMed1979

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.

Creatine Kinase↗