SEARCH · PubMed Health
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Explore the source record for details and available documents.
Alkaline phosphatase activity in obese mice (C57BL/6J ob/ob) was significantly increased from 18 to 63 weeks of age when compared to that of their lean controls (C57BL/6J +/?). In 5 week old animals, the earliest age examined, the circulating activity of alkaline phosphatase was similar in both obese mice and their lean counterparts. To characterize the circulating alkaline phosphatase activity in the obese mouse and its lean counterpart, the response of the enzyme to fasting, various inhibitors, heat inactivation, and urea denaturation was examined and compared. L-homoarginine and L-p-bromotetramisole inhibited to a large extent the circulating activity of alkaline phosphatase in both obese mice and their lean controls in the fed state, while L-phenylalanine had essentially no effect. Even though the response of alkaline phosphatase in plasma to several inhibitors was similar, the rate of denaturation by urea of enzyme activity in plasma was significantly slower in obese mice than in their lean controls in the fed state. While the rate of inactivation of alkaline phosphatase activity in plasma for the initial two minutes at 56 degrees C was similar in obese mice and their lean counterparts, the subsequent rate of heat inactivation was significantly slower in the plasma from obese mice. Thus, both obese and lean mice in the fed state have a circulating activity of alkaline phosphatase in plasma with a greater contribution from a skeletal isoenzyme and a lesser one of intestinal origin.(ABSTRACT TRUNCATED AT 250 WORDS)
The serum of patients with obstructive liver disease may contain a high molecular weight form of alkaline phosphatase (high Mr alkaline phosphatase). The presence of this form of alkaline phosphatase is associated with hepatic malignancies. We have investigated the use of anti-alkaline phosphatase monoclonal antibodies which do not bind high Mr alkaline phosphatase in assays for high Mr alkaline phosphatase. Direct immunoprecipitation of liver and bone alkaline phosphatase with solid phase anti-liver alkaline phosphatase antibody (which also reacts with bone alkaline phosphatase) and measurement of the residual supernatant alkaline phosphatase activity led to a precise assay. Intestinal alkaline phosphatase interfered in this assay which, consequently, was of little use in the differential diagnosis of liver disease. Indirect precipitation of liver, bone, placental and intestinal alkaline phosphatase by soluble anti-liver alkaline phosphatase (which reacts with liver and bone alkaline phosphatases), soluble anti-intestinal alkaline phosphatase (which reacts with placental and intestinal alkaline phosphatases) and solid phase anti-mouse IgG led to an assay which, although less precise, showed more promise of being useful clinically.
Human prostatic acid phosphatase (hPAP) directly enhances the differentiated characteristics of isolated bone cells in vitro. This enzyme, when added to cell cultures for 24 h in vitro stimulates collagen synthesis and the production of alkaline phosphatase. The effects are dose dependent, with statistically significant effects occurring from 0.1-100 nM hPAP. Concentrations higher than 100 nM do not evoke greater effects. The maximal effect of hPAP occurs between 12 and 24 h of exposure. The cells stimulated to the greatest degree are osteoprogenitor cells and osteoblasts. Fibroblasts isolated from the same tissue show a lesser sensitivity to hPAP. hPAP has no detectable effect on cell proliferation, as measured by radiolabeled thymidine incorporation or total DNA synthesis. None of the observations reported in this work can be attributed to contaminating proteins in the hPAP preparation. hPAP was radiolabeled with 125I and was used for affinity binding and cross-linking studies. Scatchard analysis of specific binding indicated the presence of 1.0 X 10(5) high affinity binding sites/cell, with a Kd of 6.5 nM. Cross-linking studies demonstrated the presence of one 320-kDa binding complex. The pH profile and kinetic determinations of Km and maximum velocity for hPAP were similar to those previously reported, except for the finding of positive cooperativity of the substrate with the enzyme under the conditions of our assay. We believe that the direct stimulation of bone-forming cells by hPAP may contribute to the sclerotic nature of skeletal bone around sites of neoplastic prostatic metastases and that the effect of the enzyme is probably mediated by a plasma membrane receptor.
Rat intestinal alkaline phosphatase activity was found to be greater in the fetus near term than in the progeny at birth. A set back in the orderly development of the enzyme was observed in the duodenum of pups born to protein-deficient mothers. Electrophoretic studies on polyacrylamide gel showed homogeneity of the enzyme in fetus and newborn pups. Severe intrauterine growth retardation was associated with reduced size of the enterocytes and their nuclei.
Human placental alkaline phosphatase was inactivated with tetranitromethane in a biphasic process. Spectral and amino acid analysis demonstrated that the inactivation was due to the conversion of tyrosine residues to 3-nitrotyrosine. The inactivation process showed saturation kinetics. Protection of the enzyme against tetranitromethane inactivation was afforded by inorganic phosphate. The binding affinity between the modified enzyme and inorganic phosphate was decreased. Our results suggest the involvement of tyrosyl residues in the locus of phosphoryl site of the phosphorylated enzyme forms.
A novel alkaline phosphatase (AP) isozyme was found in human adipose tissue. Adipose tissue alkaline phosphatase differed in enzymatic properties from liver, placental and intestinal alkaline phosphatases. On electrophoresis it showed the same mobility as intestinal alkaline phosphatase, but after treatment with neuraminidase its mobility was decreased to the same as or slightly less than that of neuraminidase-treated liver alkaline phosphatase. Its inhibition by amino acids, inactivation by urea and activation by Mg2+ were almost the same to those of liver alkaline phosphatase. However, at 56 and 65 degrees C it was more stable than liver alkaline phosphatase. Alkaline phosphatase activity was demonstrated histochemically in adipose tissue with naphthol AS-MX phosphate as substrate. It was localized in the wall of blood capillaries, but not present in adipocytes.
Calf intestinal alkaline phosphatase is inactivated by 2,3-butanedione and phenylglyoxal. The reaction with either reagent results in a biphasic loss of enzymatic activity. Inactivation by 2,3-butanedione in borate buffer can be reversed after gel-filtration in Tris buffer but no enzyme reactivation is observed after phenylglyoxal treatment. Phosphate, ATP and NADH protect the enzyme from both compounds while no protection is displayed by L-phenylalanine. The selective chemical modification indicates that two differently reacting types of arginines are present in the active site domains of the dimeric enzyme.
Three placental alkaline phosphatases purified to homogeneity, i.e., the F, I, and S variants, were investigated for catalytic and stability properties. All three forms of the enzyme were found to have almost identical pH optima (10.7--10.8), similar sensitivity to the uncompetitive inhibitors L-phenylalanine (70%) and L-leucine (30%), and identical Km values against p-nitrophenylphosphate, beta-glycerophosphate, and alpha-naphthylphosphate. Significant differences among the three types were observed in thermal stability. The F variant was found to be most stable and the I variant most labile at 79 C. At 70 C all three forms were stable.
Bovine liver alkaline phosphatase has been purified to homogeneity by procedures that include reverse-phase HPLC. The pure enzyme has an apparent Mr of 160,000 and is composed of what appears to be two identical monomers of Mr 82,000. About 80% of the material yielded the amino-terminal sequence Leu-Val-Pro-Glu-Lys-Glu-Lys-Asp-Pro-?-Tyr-?-Arg-Asp-Gln-Ala-Gln. The minor component was extended at the amino terminus by two residues that have not yet been identified, i.e., ?-?-Leu-Val-Pro-Glu-Lys-Glu-Lys-Asp-Pro-?-Tyr-?-Arg-Asp-Gln-Ala-Gln.
Partially purified alkaline phosphatase (ALP) from canine intestine, liver, and bone were injected into rabbits to elicit anti-canine intestinal, hepatic, and osseous ALP antibodies, respectively. The antibody formed a soluble enzyme-antienzyme complex when directly interacted with the ALP antigen. In order to form an insoluble complex, it was then necessary to interact the initial soluble complex with the goat anti-rabbit gamma-globulin antibody in the 2nd step. Antiintestinal ALP antibody was highly specific and did not cross react with canine hepatic, osseous, splenic, and renal ALP. Antiliver and antibone ALP antibodies, on the other hand, did cross react with hepatic, osseous, splenic, and renal ALP, but not with the intestinal ALP.
Alkaline phosphatase (AP) activity on cryostat sections of the skin of 38 cases of non-Hodgkin's lymphomas of the B cell type and of 10 cases of lymphadenosis benigna cutis have been studied. Membrane-bound AP activity has been found in 8 out of 28 cases of low-grade malignant lymphomas of the B cell type and in 2 out of 10 cases of lymphadenosis benigna cutis. This is a known phenomenon in the latter. In the literature of non-Hodgkin's lymphoma AP activity is related to the intermediate type of lymphocytic lymphoma. Further studies are needed to demonstrate that the AP activity correlates with a specific cell type in the B lymphoid cell differentiation.
Decreased leukocyte alkaline phosphatase (LAP) is a first line test for chronic myelogenous leukemia (CML), generally preceding a diagnostic algorithm which also includes bone marrow biopsy, cytogenetic analysis, and molecular diagnostics. We found the analytical uncertainty of LAP assays to range from over 100% coefficient of variation at low scores to about 20% at high scores. However, the receiver-operator characteristics derived from LAP determinations in 50 consecutive cases suggest that a suitably high diagnostic decision threshold still can eliminate false negatives. As a consequence of such a strategy, as many as half the tested patients, classified unequivocally as the negatives, can avoid further invasive and costly workup. On the other hand, serial LAP determinations, whether performed to detect change to a lower or to a higher score, are unlikely to produce conclusive diagnostic signals exceeding analytical 'noise.'
Calf intestinal alkaline phosphatase (CIP) was denatured in 3.0 M guanidine hydrochloride for 2 h at 25 degrees C, before being diluted 20-fold with 0.1 M, pH 8.0, Tris-HCl buffer solution containing various effector molecules such as Mg2+, Zn2+, and nucleotide phosphate. The reactivation courses of the enzyme were investigated by the level of activity recovery, the recovery rate constant, and the relative standard deviation of the data. In the presence of effectors, the courses under reducing and nonreducing conditions of disulfide bonds of protein were compared. It was concluded that for CIP, Mg2+ is a more efficient inducer of reconstitution of the active site and appears to play a specific role. In addition, the present study discusses the differences in the refolding effectors between bacterial and mammalian enzymes.
1. Rabbit alkaline phosphatases (APs) clearly fused with the anti-human AP antibodies. In particular, fetal liver and kidney APs reacted slightly less with the anti-intestinal AP antibody as did adult enzymes, suggesting that intestinal AP-like isozyme is expressed at earlier stages of gestation in rabbit liver and kidney. 2. Immunohistochemical data indicated that intestinal AP-like isozyme in the kidney was mainly localized in the distal convoluted tubules and slightly in the proximal straight tubules, whereas liver/bone/kidney AP-like enzyme was found more in the glomeruli and interstitial capillary walls as a major component. 3. The sugar-chain heterogeneity of adult and fetal rabbit APs displayed organ-specificity as did of rat and human APs. Moreover, in fetal development, the expression of high-mannose type or hybrid type sugar chains precedes the expression of complex type sugar chains in fetal development.
Serum alkaline phosphatase (AP), total bilirubin, total protein, serum albumin, and serum glutamic oxaloacetic transaminase (SGOT) were determined in 55 patients with biopsy proven carcinoma of the head and neck prior to their induction chemotherapy with cis-platinum and bleomycin. Of the 55 patients, 40 (73%) exhibited either a complete or partial response (tumor mass decreased by over 50%) to the chemotherapy. Responses were noted more frequently in patients with elevated AP levels. Nine of the 10 patients (90%) with AP levels greater than 100 mU/ml experienced a major response; whereas, only 8 of 16 patients (50%) with AP levels less than 60 mU/ml demonstrated a favorable response to the chemotherapeutic agents. The source of the elevated AP levels has not yet been established. Possible sources include liver, bone, kidney, intestinal mucosa, or the tumor itself. Total bilirubin, total protein, serum albumin, and SGOT levels did not differentiate the responders from the non-responders as accurately as did the AP levels.
Intestinal alkaline phosphatase (IALP) activity rises following the ingestion of a fat-containing meal. Previous studies on intestinal fluid and lymph have shown that the magnitude of this response is dependent upon fatty acid chain length. To examine this relation in the serum of healthy humans, 10 subjects consumed two standardized fat meals. One meal contained predominantly long chain fatty acid triglycerides, the other contained predominantly medium chain fatty acid triglycerides. Serum IALP activity was measured in serial blood samples using a sensitive immunological assay. IALP activity was ABO blood group and secretor status dependent. The post-prandial rise in serum IALP activity was significantly greater following the long chain fatty acid meal than following the medium chain fatty acid meal. Previous observations of the fatty acid chain length dependency of the IALP response to fat ingestion, therefore, also apply in the serum of healthy humans under normal physiological conditions. Standardized fat meals provide the basis of a useful method for the investigation of the role of IALP in fat absorption.
A technique using alkaline phosphatase histochemistry on routine sections of four jejunal biopsy specimens and one necropsy sample was applied to show that alkaline phosphatase activity, normally present in the brush border, occurs in the enterocytes of patients with microvillus inclusion disease. Sections were cut at 5 micron, mounted on to glass slides, and dried overnight at 37 degrees C before staining for alkaline phosphatase activity by the indoxyl phosphatase nitro blue tetrazolium method. Incubation periods amounted to 10 minutes for biopsy specimens and 30 minutes to one hour for necropsy samples. The demonstration of alkaline phosphatase activity in routinely processed biopsy specimens provides an effective, quick, and definitive test in the diagnosis of microvillus inclusion disease without recourse to electron microscopy.