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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↗
PubMed1989

Inhibition of osteoclastic acid phosphatase abolishes bone resorption.

Osteoclastic acid phosphatase is a member of a widely-distributed class of iron-containing proteins with acid phosphatase activity. Antibodies raised against one member of this class cross-react with other members from the same or different species, but not with acid phosphatase isoenzymes of different types. When antibodies to one such protein, porcine uteroferrin, are added to medium in which rat osteoclasts are incubated on devitalised cortical bone, both bone resorption and acid phosphatase activity are markedly inhibited. Furthermore, addition of molybdate (an inhibitor of this class of acid phosphatases) also inhibits both bone resorption and enzyme activity. These observations strongly suggest a functional role for osteoclastic acid phosphatase in bone resorption.

Acid Phosphatase↗
PubMed1989

An immunoassay of human band 5 ("tartrate-resistant") acid phosphatase that involves the use of anti-porcine uteroferrin antibodies.

We describe an immunoassay for human band-5 acid phosphatase in which antibodies to porcine uteroferrin, immobilized on Sepharose particles, are used. Band-5 acid phosphatase is the tartrate-resistant isoenzyme normally expressed in tissue macrophages such as osteoclasts and alveolar macrophages. The immunoassay is similar in reproducibility and sensitivity to assays based on inhibition by d-tartrate. However, compared with the latter, the greater specificity of the immunoassay makes it markedly less susceptible to errors arising from the presence of non-band-5 acid phosphatases, e.g., from prostate.

Acid Phosphatase↗
PubMed1988

The place of reference materials in clinical enzymology.

Standardization embraces two concepts: achievement of a uniform standard of practice, or comparison with a standard of known or defined properties. In clinical enzymology the former concept can be equated with the adoption of recommended standardized methodology, which has had noteworthy successes in improving comparability of results. The use of enzyme standards or calibrators has received relatively little attention so far, but is increasingly important with the introduction of analysers which cannot readily utilize recommended methods. The main factor in the use of calibrators is that of commutability of calibrators and patients' samples between methods, which must be the subject of thorough experimental tests.

Calibration↗
PubMed1988

Gamma glutamyl transferase activity in rat colon during experimental colonic carcinogenesis.

Colonic gamma glutamyl transferase activity is raised in colonic malignancy. This study was undertaken to determine how early and how extensively this raised activity occurs during carcinogenesis. Sixty rats were given weekly injections of dimethylhydrazine for 16 weeks, and 20 rats acted as controls. Groups of treated and control rats were sacrificed at regular intervals during the pre-cancerous phase of carcinogenesis, and gamma glutamyl transferase activity was measured at several sites in the colon. Gamma glutamyl transferase activity was raised as early as 4 weeks after the first injection of dimethylhydrazine (p less than 0.05), and the elevation persisted until the development of overt tumours. The raised gamma glutamyl transferase activity was observed throughout both the proximal and distal colon long before the appearance of macroscopic tumours. We conclude that an early and widespread elevation of colonic gamma glutamyl transferase activity occurs during carcinogenesis. This may have useful applications in the early detection of colonic malignancy.

1,2-Dimethylhydrazine↗
PubMed1988

Osteocalcin: a potential marker of metastatic bone disease and response to treatment.

Serum osteocalcin (BGP) is an osteoblast product that probably reflects the rate of bone formation. It is a potential marker of skeletal metastases and, to investigate this, BGP was measured by radioimmunoassay in the serum of normal subjects and patients with breast or prostate cancer. Significantly higher levels were found in patients with metastatic bone disease in comparison to both normal subjects (P less than 0.001) and patients with non-metastatic cancer (P less than 0.05 for breast cancer and less than 0.001 for prostate cancer). The range of values was wide. Levels were higher in sclerotic than lytic bone metastases (P less than 0.01) and lower in patients with hypercalcaemia (P less than 0.001). Serial measurements of BGP were made in 53 patients with skeletal metastases from breast cancer receiving systemic therapy. At 1 month BGP rose by greater than 0.5 ng/ml in 15/16 responding patients compared with 7/23 patients with progressive disease (P less than 0.01). Responding patients also showed a rise in the bone isoenzyme of alkaline phosphatase and a paradoxical deterioration in the bone scan appearance, both reflecting a flare in osteoblast activity. The early increase in responding patients was followed by a gradual decrease over subsequent months as the osteoblast reaction induced by systemic therapy subsided. We conclude that BGP measurements reflect a wide variability of bone formation rates in metastatic bone disease. Bone formation was usually increased, particularly when metastases were sclerotic in appearance, but in patients with hypercalcaemia the low BGP levels suggest uncoupling of bone resorption and formation. Serial measurements of BGP may be useful in monitoring response to treatment.

Biomarkers, Tumor↗
PubMed1988

Biochemical prediction of response of bone metastases to treatment.

Assessment of response of skeletal metastases to systemic therapy is currently dependent on radiological evidence of bone healing. We have performed a prospective study of additional response criteria in patients with progressive bone metastases from breast cancer. Changes in these potential markers of response were correlated with the radiological response and the time to treatment failure (TTF). Successful systemic therapy typically led to a transient increase in osteoblast activity ('flare'), a reduction in osteoclast activity and symptomatic improvement. After 1 month a greater than 10% rise in serum osteocalcin (BGP) and alkaline phosphatase bone isoenzyme (ALP-BI) and a greater than 10% fall in urinary calcium excretion were seen in 14/16 patients with radiographic evidence of bone healing (UICC partial responders). In comparison similar biochemical changes at 1 month were seen in only 4/20 patients with progressive disease (P less than 0.001). The predictive value and diagnostic efficiency (DE) of changes at 1 month in biochemical measurements and symptom score has been calculated. The combination of a greater than 10% rise in ALPBI and BGP and a greater than 10% fall in urinary calcium excretion had a DE of 89% for discriminating response from progression, 88% for response from non-response (progressing + no change patients), and 76% for TTF of greater than 6 months from TTF of less than 6 months. Serum calcium, tartrate resistant acid phosphatase (TRP), urinary hydroxyproline excretion and bone scan changes were unhelpful in discriminating between patient groups. Independent confirmation is needed, but our results suggest there are reliable alternatives to plain radiography in the early assessment of response of bone metastases to treatment.

Adult↗
PubMed1988

Bone scan flare predicts successful systemic therapy for bone metastases.

Changes in osteoblast function, assessed by serial bone scans and serum alkaline phosphatase bone isoenzyme (ALP-Bl) and osteocalcin, have been studied in 53 patients receiving systemic therapy for bone metastases from advanced breast cancer. In 12/16 patients with healing of lytic disease on x-ray a paradoxical deterioration in the bone scan appearances after 3 mo treatment was seen. This was characterized by increased activity in baseline lesions and the appearance of new foci of tracer uptake; changes which are indistinguishable from progressive disease. After 6 mo successful treatment the bone scan improved with reduced tracer uptake and no new lesions since the 3-mo scan. New lesions appearing after 6 mo indicated progressive disease. These changes are attributed to a flare in osteoblast activity induced by successful systemic therapy and confirmed by a transient rise in osteocalcin and ALP-Bl. After 1 mo of treatment 15/16 responders showed a rise in both parameters compared with only 5/23 nonresponders (p = less than 0.001). The flare response is the rule rather than the exception after successful systemic therapy for bone metastases. The appearance of new lesions or increasing activity in known lesions during the first 3 mo is as likely to herald radiological response as disease progression.

Adult↗