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D W Moss

Publications and source records attributed to D W Moss.

At least 55 records · Page 3Linked to original sources
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↗
PubMed1987

Association of alkaline phosphatase with an autoantigen recognised by circulating anti-neutrophil antibodies in systemic vasculitis.

A solid phase radioimmunoassay has been developed to detect circulating autoantibodies to neutrophil cytoplasmic antigens in systemic vasculitis. After fractionation of these antigens by size, with gel filtration high performance liquid chromatography, sera from patients with clinically different forms of systemic vasculitis, Wegener's granulomatosis (WG) and microscopic polyarteritis (MP), showed contrasting specificities of binding. WG sera bound to 100, 6.2, and 1.8 kD components, whereas MP sera bound only to the 100 kD component, allowing immunological distinction between the syndromes. The 100 kD component recognised by both WG and MP sera also showed alkaline phosphatase activity. Further evidence for this association was obtained by direct binding experiments between systemic vasculitis sera and calf-intestinal or human neutrophil alkaline phosphatase and by the cross-reactivity of W8, a monoclonal antibody raised to a neutrophil cytoplasmic autoantigen, with various preparations of the enzyme.

Alkaline Phosphatase↗
PubMed1987

Effect of bromelain on alkaline phosphatases of intestinal and non-intestinal tissues and serum.

Human alkaline phosphatases extracted with butanol from liver, kidney and placenta, and from foetal and adult small intestine each contain fragments with molecular masses within the range of approximately 8 kDa to 20 kDa which can be removed by digestion with bromelain. However, in the case of adult intestine, this fragment (which is presumed to represent a membrane-binding domain) can only be demonstrated in tissue extracted immediately after removal at operation. Similar fragments are also present in foetal intestinal phosphatase in amniotic fluid, and in liver and bone alkaline phosphatases recovered from serum. Again, however, adult intestinal phosphatase from serum differs in the absence of the bromelain-sensitive fragment. These observations indicate differences in the ways in which intestinal and non-intestinal alkaline phosphatases gain access to the circulation, and also have implications for structural studies on intestinal phosphatase extracted post mortem from adult tissue.

Adult↗
PubMed1987

Diagnostic aspects of alkaline phosphatase and its isoenzymes.

The changes in serum alkaline phosphatase that are of main diagnostic importance result from increased entry of enzyme into the circulation. This results from increased osteoblastic activity in bone disease, and increased synthesis of alkaline phosphatase by hepatocytes in hepatobiliary disease. The liver and bone forms of alkaline phosphatase are differently-glycosylated forms of a single gene product. The main value of their specific estimation is found in patients in whom bone and liver diseases co-exist, for example, as a result of cancer. Abnormal expression of genetically-distinct alkaline phosphatase isoenzymes is valuable in monitoring cancers, particularly germ-cell tumors. These isoenzymes include Regan and Nagao isoenzymes, which correspond respectively to normal placental and placental-like alkaline phosphatases, and the Kasahara isoenzyme which appears to result from re-expression of a fetal intestinal alkaline phosphatase gene.

Alkaline Phosphatase↗
PubMed1987

The physical characteristics and enzymatic modification of fetal intestinal alkaline phosphatase in amniotic fluid.

The predominant form of alkaline phosphatase in amniotic fluid at 16 to 18 weeks gestation has the inhibition characteristics of the isoenzymes from adult and fetal small intestine. These characteristics are shared by an alkaline phosphatase of presumed intestinal origin occasionally found in the sera of premature neonates. However, in contrast to the rapid anodal migration of the latter enzyme, amniotic fluid phosphatase is of low electrophoretic mobility in polyacrylamide gel, and it has a high molecular weight. Digestion of amniotic fluid with bromelain produces a rapidly-migrating active enzyme form, with a molecular weight of about 135,000, compared with 145,000 for the fetal intestinal phosphatase in serum. The bromelain-treated amniotic fluid phosphatase is similar in size to a Kasahara isoenzyme in the serum of a cancer patient, which is itself thought to result from re-expression of a fetal intestinal phosphatase gene.

Adult↗
PubMed1987

Subtle hyperthyroidism presenting as suspected hepatobiliary disease.

Three patients, each with a nonspecific clinical history and raised serum alkaline phosphatase levels, were referred for investigation of hepatobiliary disorders. Isoenzyme analysis showed both hepatic and bony isoenzymes to be elevated, and eventually hyperthyroidism was diagnosed in each patient. Hyperthyroidism can be difficult to recognize clinically, and isolated elevation of serum alkaline phosphatase levels may be a useful clue.

Adult↗
PubMed1987

Antibodies to porcine uteroferrin used in measurement of human tartrate-resistant acid phosphatase.

The immunological similarity between human tartrate-resistant acid phosphatase (EC 3.1.3.2) and porcine uteroferrin previously reported for the isoenzyme from spleens of patients with leukemic reticuloendotheliosis (Ketcham et al., J Biol Chem 1985;260:5768-76) has been confirmed for partly purified acid phosphatase found in the spleen of a patient with Gaucher's disease, and for the corresponding isoenzyme in other tissues and serum. Anti-uteroferrin antibodies raised in rabbits have been used to demonstrate the feasibility of their application in an immunoassay for tartrate-resistant acid phosphatase in serum.

Acid Phosphatase↗