Tyrosine phosphorylation of c-ErbB-2 is regulated by the cellular form of prostatic acid phosphatase in human prostate cancer cells

Human prostatic acid phosphatase (PAcP) is a prostate epithelium-specific differentiation antigen. In prostate carcinomas, the cellular PAcP is decreased. We investigated its functional role in these cells. Several lines of evidence support the hypothesis that cellular PAcP functions as a neutral protein-tyrosine phosphatase and is involved in regulating prostate cell growth. In this study, we identify its in vivo substrate. Our results demonstrated that, in different human prostate cancer cell lines, the phosphotyrosine (Tyr(P)) level of a 185-kDa phosphoprotein (pp185) inversely correlates with the cellular activity of PAcP. On SDS-PAGE, this pp185 co-migrates with the c-ErbB-2 oncoprotein. Immunodepletion experiments revealed that c-ErbB-2 protein is the major pp185 in cells. Results from subclones of LNCaP cells indicated the lower the cellular PAcP activity, the higher the Tyr(P) levels of c-ErbB-2. This inverse correlation was further observed in PAcP cDNA-transfected cells. In clone 33 LNCaP cells, L-(+)-tartrate suppresses the cellular PAcP activity and causes an elevated Tyr(P) level of c-ErbB-2 protein. Epidermal growth factor stimulates the proliferation of LNCaP cells, which concurs with a decreased cellular PAcP activity as well as an increased Tyr(P) level of c-ErbB-2. Biochemically, PAcP dephosphorylates c-ErbB-2 at pH 7.0. The results thus suggest that cellular PAcP down-regulates prostate cell growth by dephosphorylating Tyr(P) on c-ErbB-2 oncoprotein in those cells.

Use of the Malthus-AT system to assess the efficacy of permeabilizing agents on the activity of antibacterial agents against Pseudomonas aeruginosa

The Malthus-AT system provided a satisfactory method for examining the effects of permeabilizing agents on the activity of sub-inhibitory concentrations of antibacterial agents against Pseudomonas aeruginosa G48. Under this system, disodium edetate potentiated the activity of chlorhexidine diacetate (CHA), cetylpyridinium chloride, para-chlorometaxylenol and triclosan. Nitrilotriacetic acid enhanced the activity of some of the antibacterials tested, whereas sodium polyphosphate markedly reduced the efficacy of CHA.

Is acid phosphatase activity present in bone matrix at sites of endochondral ossification in rabbit fracture callus?

It has been suggested that acid phosphatase activity is present in newly formed bone matrix at sites of endochondral ossification in rabbit fracture calluses. Because acid phosphatases are usually found intracellularly, it was decided to test this possibility more rigorously. Tissue from 10- and 14-day healing rabbit fractures was subjected to a series of critical tests for acid phosphatases with a pH optimum of 5.0. Fluoride, tartrate and molybdate were used as potential inhibitors of acid phosphatase activity. The effects of several counterstaining protocols were also investigated. A fluoride- and tartrate-resistant acid phosphatase is located in osteoclasts and mononuclear phagocytes. Diffuse staining of the bone matrix is seen, but it is dependent upon the length of incubation in the substrate medium and the distance from the acid phosphatase-reacting cells. It is concluded that the coloration of the bone matrix is probably caused by diffusion of the dye and reaction product and is, therefore, artifactual.

Prostatic acid phosphatase: structural aspects of inhibition by L-(+)-tartrate ions

The crystal structure of the complex between rat-prostatic acid phosphatase (PAP) and L-(+)-tartrate (Lindqvist et al., J. Biol. Chem., 1993, 268, 20744-20746) contains the model of the ligand with incorrect chirality. We report here the correct model and discuss the relation between this model and the model of the inhibitory complexes between PAP and oxy-anions.

Broiler skin color as affected by organic acids: influence of concentration and method of application

Color of broiler skin was evaluated after exposure to organic acids under various concentrations and simulated potential plant application conditions. Breast skin from chilled broiler carcasses was treated with acetic (AA), citric (CA), lactic (LA), malic (ML), mandelic (MN), propionic (PA), or tartaric (TA) acids at 0.5, 1, 2, 4, and 6% concentrations. Each acid and concentration was applied in simulated dip (23 C for 15 s), scalder (50 C for 2 min), and immersion chiller (1 C for 60 min) conditions. A tap water control was included with each application method. Objective color values of L* (lightness), a* (redness), and b* (yellowness) were measured before and after the treatments to calculate color differentials under a factorial arrangement of organic acids and concentrations. Skin lightness increased (P < 0.01) in simulated chiller as compared to dip and scalder applications. Skin redness was reduced significantly in scalder, and yellowness in dip and scalder applications, respectively. In simulated dip application, with the exception of PA, all acids decreased lightness and increased redness and yellowness values. Propionic acid had little affect on lightness and redness values, but decreased yellowness values. In simulated scalder application, with the exception of PA, all acids decreased lightness with increasing concentration. The redness values changed little in scalder application. However, yellowness values were increased with all acids, except for PA, which decreased yellowness values. In simulated chiller conditions, all acids, except for PA, decreased lightness and redness and increased yellowness values. Propionic acid increased lightness and decreased yellowness values significantly in chiller conditions. Alterations in skin color should be taken into account in the selection and application of organic acids as carcass disinfectants.

An active efflux system for heavy metals in cisplatin-resistant human KB carcinoma cells

The mechanism for cisplatin resistance in cisplatin-resistant KCP-4 cells was studied. Although multidrug resistance-associated protein (MRP) was not detected in KCP-4 cells, the cells were more resistant to heavy metals than multidrug-resistant C-A120 cells that overexpressed MRP. KCP-4 cells expressed metallothionein, but it was scarcely involved in cisplatin resistance in these cells. KCP-4 cells did not express canalicular multispecific organic anion transporter (cMOAT). The glutathione (GSH) level was 4.7-fold higher in KCP-4 cells than in KB-3-1 cells. When the GSH level in KCP-4 cells was decreased by treating the cells with buthionine sulfoximine and nitrofurantoin, the accumulation of and sensitivity to cisplatin in the cells were increased. C-A120 cells were only 3.0-fold more resistant to cisplatin than KB-3-1 cells and this resistance was not affected by the increased glutathione level. The accumulation of platinum in C-A120 and KCP-4 cells was 68.5 and 20.4% of that in KB-3-1 cells, respectively, while the intracellular levels of antimony potassium tartrate in C-A120 and KCP-4 cells were 13.2 and 9.9% of that in KB-3-1 cells, respectively. The ATP-dependent efflux of antimony was enhanced in both C-A120 and KCP-4 cells. These results, taken together, suggest an efflux pump for heavy metals different from MRP and cMOAT is involved in cisplatin resistance in KCP-4 cells.

Murine bone marrow stromally derived BMS2 adipocytes support differentiation and function of osteoclast-like cells in vitro

Stromal cells are required for in vitro osteoclast differentiation and maturation. The murine bone marrow stromally derived BMS2 cell line exhibits adipocytic and osteoblastic features as well as the ability to support lymphopoiesis and myelopoiesis. This work examined the ability of the BMS2 cell in either the preadipocyte or adipocyte state to support the formation of osteoclast-like cells. BMS2 cells can be induced to undergo adipogenic differentiation in response to treatment with glucocorticoids or thiazolidinedione compounds. Primary bone marrow cells, enriched for hematopoietic progenitors and depleted of their adherent stromal and macrophage populations, were stimulated with vitamin D3 (vitamin D; 10(-8) M) to undergo osteoclast differentiation and maturation when cocultured with BMS2 cells. In both preadipocyte and adipocyte-enriched BMS2 stromal layers, comparable numbers of tartrate-resistant acid phosphatase-positive osteoclast-like cells, characterized by their response to salmon calcitonin with an increase in cAMP and formation of resorption pits on bovine bone slices, were formed. The gene expression and protein levels of macrophage colony-stimulating factor produced by preadipocyte and adipocyte-rich BMS2 layers were comparable. However, adipocyte-rich stromal layers supported osteoclast-like cell formation longer in culture than preadipocytes, independent of the agent used to induce adipocyte differentiation. These studies demonstrate for the first time that fully differentiated adipocyte stromal cells can support osteoclast-like cell formation and function in vitro.

The cellular actions of interleukin-11 on bone resorption in vitro

The pleiotropic cytokine interleukin-11 (IL-11) stimulates osteoclast formation in vitro, but it is not known whether it influences other steps in the bone-resorptive cascade. Using a variety of in vitro model systems for studying bone resorption we have investigated the effects of IL-11 on 1) osteoclast formation, fusion, migration, and activity; and 2) osteoblast-mediated osteoid degradation. The involvement of matrix metalloproteinases (MMPs) and products of arachidonic acid metabolism in IL-11-mediated resorption were also assessed. We first examined the bone-resorptive effects of IL-11 by assessing 45Ca release from neonatal mouse calvarial bones. IL-11 dose-dependently stimulated bone resorption with an EC50 of 10(-10) M. The kinetics of IL-11-mediated 45Ca release demonstrated that it was without effect for the first 48 h of culture, but by 96 h, it stimulated 45Ca release to the same level as that produced by 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] (a hormone that stimulates osteoclast formation and activity). IL-11 also produced a dose-dependent increase in osteoblast-mediated type I collagen degradation with a maximum of 58.0 +/- 6.2% at 5 x 10(-9) M; this effect of IL-11 was less than that produced by 1,25-(OH)2D3 (76.5 +/- 7.1%) and was prevented by an inhibitor of MMPs, but not those blocking arachidonic acid metabolism. We then tested the effects of IL-11 on isolated mouse osteoclasts cultured on ivory slices in the presence and absence of primary mouse osteoblasts. IL-11 had no effect on isolated osteoclast activity even in coculture with primary osteoblasts. We then examined the effects of IL-11 on the formation of osteoclast-like multinucleate cells in mouse bone marrow cultures and the resorptive activity of such cultures using ivory as a substrate. IL-11 dose-dependently increased 1) the number of tartrate-resistant acid phosphatase-positive osteoclast-like multinucleate cells and 2) the surface area of lacunar resorption, although the effects were less than that of 1,25-(OH)2D3. The effect of IL-11 on bone marrow lacunar resorption was prevented by a combination of inhibitors of 5-lipoxygenase and cyclooxygenase. In 17-day-old metatarsal bones, IL-11 prevented the migration of (pre)osteoclasts to future resorption sites, whereas their fusion was unaffected. These results provide strong evidence that IL-11 stimulates bone resorption by enhancing osteoclast formation and osteoblast-mediated osteoid degradation rather than stimulating osteoclast migration and activity. Our data also suggest that the stimulatory effects of IL-11 involve both MMPs and products of arachidonic acid metabolism.

Analysis of DNA binding proteins associated with hemin-induced transcriptional inhibition. The hemin response element binding protein is a heterogeneous complex that includes the Ku protein

Hemin inhibits transcription of the tartrate resistant acid phosphatase (TRAP) gene. Using deletion mutagenesis of the mouse TRAP 5'-flanking region, we previously identified a 27-bp DNA segment containing a central GAGGC tandem repeat sequence (the hemin response element [HRE]), which bound nuclear proteins (hemin response element binding proteins [HREBPs]) from hemin-treated cells and appeared to be responsible for mediating transcriptional inhibition in response to hemin. We now have used affinity binding to HRE-derivatized beads to identify four HREBP components with apparent molecular masses of 133-, 90-, 80-, and 37-kD, respectively. The 80- and 90-kD components correspond to the p70 and p80/86 subunits of Ku antigen (KuAg) as documented by partial amino acid microsequencing of tryptic digests and immunologic reactivity. Based on reactivity of the HREBP gel shift band with antibodies to the redox factor protein (ref1) in shift Western experiments, it is shown that the 37-kD component represents ref1. The 133-kD component appeared to be a unique protein. KuAg participation in HREBP complexes was specific as it was present in HREBPs bound to HRE microcircles. Results of depletion/reconstitution experiments suggested that KuAg does not bind alone or directly to HRE DNA, but does so only in conjunction with the 133- and/or 37-kD proteins. We conclude that HREBP is a heterogeneous complex composed of KuAg, ref1, and a unique 133-kD protein. We speculate that the role of heme may be to promote interactions among these components, thereby facilitating HRE binding and downregulation of hemin responsive genes.

Incompatibility properties of tartrate utilization plasmids derived from Agrobacterium vitis strains

The incompatibility properties of two tumor-inducing (Ti) and seven tartrate (Tr) plasmids, derived from various Agrobacterium vitis strains, were characterized using incRh1, incRh2, incRh3, and incRh4 clones which were established for the identification and classification of Agrobacterium plasmids. The tested A. vitis plasmids could be allocated into four groups on the basis of their incompatibility with incRh1, incRh2, and incRh4 clones. The two octopine tumor-inducing plasmids, pTiAT6 and pTiAB3, expressed incompatibility both to incRh1 and to incRh2 clones. Three pTrs could not be allocated either to incRh1-4 and incAg1 or to the wide-host-range incP1, incQ, and incW groups.

Improved method for measuring tartrate-resistant acid phosphatase activity in serum

We describe an improved method for the kinetic measurement of tartrate-resistant acid phosphatase (TrACP; EC 3.1.3.2) activity in serum. Of the TrACP derived from erythrocytes, platelets, and macrophages (osteoclasts and others), that from the first two sources is also resistant to fluoride, whereas skeletal TrACP is sensitive to fluoride. Thus, osteoclast-derived TrACP can be measured specifically by exploiting its sensitivity to fluoride. We measured the activity of tartrate-resistant and fluoride-sensitive acid phosphatase (TrFsACP) by using 2,6-dichloro-4-acetylphenyl phosphate as substrate at pH 6.2. The activity of TrFsACP in serum was increased by adding hexadimethrine bromide (Polybrene) to the reaction mixture. This method was not influenced by hemolysis with hemoglobin concentrations as great as 0.9 g/L. The mean +/- SD values of TrFsACP activity by this method were 20.4 +/- 2.8 and 16.4 +/- 2.3 U/L for young (ages 20-29 years) men (n = 34) and women (n = 50), respectively. The highest mean TrFsACP activity was found among children younger than 15 years, followed by that in elderly subjects (older than 60).

Effects of LY-117018 HCl on bone remodeling and mineral density in the oophorectomized rat

OBJECTIVE

LY-117018 HCl is a recently developed, selective estrogen receptor modulator and an analog of raloxifene. Its mode of action on the skeleton is similar to that of estrogens, although it does not have the same side effects. The aim of the current study was to compare the effects produced by the administration of 17alpha-ethinyl estradiol (0.1 mg/kg/day) and LY-117018 HCl (1 mg/kg/day) on bone remodeling, bone mineral density, and body and uterus weight in sham-operated and oophorectomized rats (experimental model of postmenopausal osteoporosis).

STUDY DESIGN

Twelve-week-old female Wistar rats were used. Treatment was given for 3 months after oophorectomy or sham operation. Bone mineral density was determined in the lumbar spine (L2, L3, and L4) and in the left femur with use of a Hologic QDR 1000 (S/N 277) densitometer. Bone remodeling was estimated with use of the formation markers osteocalcin (bone gla protein) and alkaline phosphatase and the resorption markers type I collagen carboxyterminal telopeptide and tartrate-resistant acid phosphatase.

RESULTS AND CONCLUSIONS

The newly developed derivative of raloxifene, LY-117018 HCl, offsets the reduction in bone mineral density and the accompanying increase in bone remodeling markers observed in oophorectomized rats compared with control animals. 17Alpha-ethinyl estradiol also prevents the loss of bone mass attributed to oophorectomy, but this is accompanied by an increase in body mass and a greater increase in uterus weight than that observed after treatment with LY-117018 HCl.

Dicaffeoylquinic and dicaffeoyltartaric acids are selective inhibitors of human immunodeficiency virus type 1 integrase

Current pharmacological agents for human immunodeficiency virus (HIV) infection include drugs targeted against HIV reverse transcriptase and HIV protease. An understudied therapeutic target is HIV integrase, an essential enzyme that mediates integration of the HIV genome into the host chromosome. The dicaffeoylquinic acids (DCQAs) and the dicaffeoyltartaric acids (DCTAs) have potent activity against HIV integrase in vitro and prevent HIV replication in tissue culture. However, their specificity against HIV integrase in cell culture has been questioned. Thus, the ability of the DCQAs and DCTAs to inhibit binding of HIV type 1 (HIV-1) gp120 to CD4 and their activities against HIV-1 reverse transcriptase and HIV RNase H were studied. The DCQAs and DCTAs inhibited HIV-1 integrase at concentrations between 150 and 840 nM. They inhibited HIV replication at concentrations between 2 and 12 microM. Their activity against reverse transcriptase ranged from 7 microM to greater than 100 microM. Concentrations that inhibited gp120 binding to CD4 exceeded 80 microM. None of the compounds blocked HIV-1 RNase H by 50% at concentrations exceeding 80 microM. Furthermore, when the effects of the DCTAs on reverse transcription in acutely infected cells were measured, they were found to have no activity. Therefore, the DCQAs and DCTAs exhibit > 10- to > 100-fold specificity for HIV integrase, and their activity against integrase in biochemical assays is consistent with their observed anti-HIV activity in tissue culture. Thus, the DCQAs and DCTAs are a potentially important class of HIV inhibitors that act at a site distinct from that of current HIV therapeutic agents.

Alpha hydroxyacids modulate stratum corneum barrier function

Alpha hydroxyacids (AHAs) are used to enhance stratum corneum desquamation and improve skin appearance. The purpose of this study was to evaluate whether some AHAs improve skin barrier function and prevent skin irritation. Eleven healthy subjects (aged 28 +/- 6 years, mean +/- SD) entered the study. Six test sites of 8 x 5 cm (four different AHAs, vehicle only (VE) and untreated control (UNT) were selected and randomly rotated on the volar arm and forearm. The four different AHAs at 8% concentration in base cream were glycolic acid (GA), lactic acid, tartaric acid (TA) and gluconolactone (GLU). The products were applied twice a day for 4 weeks (2 mg/cm2). At week 4, a 5% sodium lauryl sulphate (SLS) challenge patch test was performed under occlusion for 6 h (HillTop chamber, 18 mm wide) on each site. Barrier function and skin irritation were evaluated by means of evaporimetry (Servomed EP-1) and chromametry (a* value, Minolta CR200) weekly, and at 0, 24 and 48 h after SLS patch removal. No significant differences in transepidermal water loss (TEWL) and erythema were observed between the four AHAs at week 4. After SLS challenge, GLU- and TA-treated sites resulted in significantly lower TEWL compared with VE, UNT (P < 0.01) and GA (P < 0.05) both at 24 and 48 h. Similarly, a* values were significantly reduced after irritation in GLU- and TA-treated sites. This study shows that AHAs can modulate stratum corneum barrier function and prevent skin irritation; the effect is not equal for all AHAs, being more marked for the molecules characterized by antioxidant properties.

Validation by image analysis of a turbidimetric method to study calcium oxalate crystallization

Numerous studies of calcium oxalate crystal formation have been carried out in the past two decades. In the present study, experiments were carried out to validate a turbidimetric method allowing to assess the calcium oxalate crystallization process. This method is quick and reproducible and can be used to quantify the inhibition of calcium oxalate crystal growth by various compounds. An experimental method of validation has been developed, which consisted in filtering solutions pure or containing modifiers at given crystallization times, photographing the filters used on scanning electron microscopy and analyzing the images using mathematical methodology. The results obtained through image analysis, namely crystal density (mean particle number per unit volume) and mean area, were correlated with the turbidimetric parameters. This finding was consistent with the qualitative examination of the photographs. Moreover, the morphological differences in crystals observed on the photographs were confirmed by the calculated length/width ratio. One can therefore assume that inhibition of calcium oxalate crystal growth is at least, partly explained by surface adsorption phenomena, which may add to complex formation.

The measurement of urinary amino-terminal telopeptides of type I collagen to monitor bone resorption in patients with primary hyperparathyroidism

This study was carried out in order to evaluate clinical usefulness of cross-linked N-telopeptides (NTx) of type I collagen determination, in patients with primary hyperparathyroidism. Twenty-six consecutive patients (6 males and 20 females, aged 56.3 +/- 15.0, SD, yrs) with primary hyperparathyroidism were studied in basal conditions and, ten of them, after surgical cure of the disease. Cross-linked collagen peptides were measured by enzyme-linked immunosorbent assay and conventional markers of bone turnover according to standard procedures. Bone densitometry at the lumbar spine and proximal femur was performed using dual-energy X-ray absorptiometry. Bone mineral density, was also assessed at the junction of the distal and middle third of the radius and at the ultradistal radius of the non-dominant arm by a dual photon densitometer. Mean urinary NTx values (194.2 +/- 121.9 pmoles bone collagen equivalents/mumoles creatinine) were significantly higher (p < 0.001) in respect to those found in normal subjects. The mean increase of Z score values of both serum tartrate resistant acid phosphatase activity (1.4 +/- 1.8) and the fasting hydroxyproline/creatinine ratio (1.45 +/- 2.0) was significantly lower (p < 0.02) in respect to that of NTx Z score values (3.3 +/- 3.3); the latter values were not significantly different than mean Z score values of serum osteocalcin (4.0 +/- 3.9), serum alkaline phosphatase activity (2.6 +/- 2.6) and urinary calcium/creatinine ratio (3.2 +/- 3.3). We found a significant inverse correlation between NTx values and both lumbar spine (p < 0.01) and ultradistal radius bone mineral density (p < 0.05); a modest inverse correlation was also observed between serum tartrate resistant acid phosphatase activity and lumbar spine bone mineral density (p < 0.04). Following successful adenoma removal, the percentage decrease of both NTx and hydroxyproline was similar in patients with increased bone turnover rate; major discrepancies were observed in patients with normal values of NTx, the telopeptide reduction being greater than that of hydroxyproline. Finally, in a hypercalcemic patient with metastatic parathyroid cancer, telopeptide excretion was shown to be more sensitive in respect to urinary hydroxyproline when evaluating the effects of antiresorptive therapy. Our results seem to indicate that amongst the markers with good sensitivity, NTx is the only one that is inversely related with bone mineral density at two different skeletal sites. This assay should therefore have a place in both the initial screening and medical follow-up of patients with this glandular disorder; in fact, in both situations an increased urinary excretion of this marker should warn about the possibility of hidden bone loss.

Mice deficient in lysosomal acid phosphatase develop lysosomal storage in the kidney and central nervous system

Lysosomal acid phosphatase (LAP) is a tartrate-sensitive enzyme with ubiquitous expression. Neither the physiological substrates nor the functional significance is known. Mice with a deficiency of LAP generated by targeted disruption of the LAP gene are fertile and develop normally. Microscopic examination of various peripheral organs revealed progredient lysosomal storage in podocytes and tubular epithelial cells of the kidney, with regionally different ultrastructural appearance of the stored material. Within the central nervous system, lysosomal storage was detected to a regionally different extent in microglia, ependymal cells, and astroglia concomitant with the development of a progressive astrogliosis and microglial activation. Whereas behavioral and neuromotor analyses were unable to distinguish between control and deficient mice, approximately 7% of the deficient animals developed generalized seizures. From the age of 6 months onward, conspicuous alterations of bone structure became apparent, resulting in a kyphoscoliotic malformation of the lower thoracic vertebral column. We conclude from these findings that LAP has a unique function in only a subset of cells, where its deficiency causes the storage of a heterogeneously appearing material in lysosomes. The causal relationship of the enzyme defect to the clinical manifestations remains to be determined.

Basic studies for the practical use of bitterness inhibitors: selective inhibition of bitterness by phospholipids

PURPOSE

We examined the effects of phospholipids such as phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol (PI), and phosphatidic acid (PA) on human taste sensation to various substances.

METHODS

The effects were evaluated psychophysically using paid volunteers.

RESULTS

PA inhibited the bitterness of various substances dissolved in water without affecting sweetness, saltiness, and sourness, although its inhibitory activity was less than that of PA-LG. PI also showed inhibitory activity on bitterness, although its activity was less than PA. A soybean lecithin fraction containing high contents of PA and PI also demonstrated inhibitory activity on the bitterness of various substances. Both the incorporation of either PA or the lecithin fraction into granules containing quinine and the coating of the granules with PA or the fraction effectively inhibited the bitterness of quinine.

CONCLUSIONS

The lecithin fraction is permitted for use as an additive to drugs and food and can be produced on an industrial scale. It is expected that the lecithin fraction will be used safely as a bitterness inhibitor for practical applications.

Trypanosoma brucei: ecto-phosphatase activity present on the surface of intact procyclic forms

The results presented in this paper indicate that procyclic forms of Trypanosoma brucei possess a phosphatase activity detected in the external cell surface able to hydrolyze about 0.7 nmol.mg-1.min-1 p-nitrophenylphosphate. A faster rate of hydrolysis was observed when membrane-enriched fractions were used. This activity is weakly sensitive to 1 mM NaF, 10 mM tartrate and 10 mM levamizole but strongly inhibited by 0.1 mM vanadate. Inhibition by both NaF and vanadate have a competitive character. This phosphatase activity decreases by increasing the pH from 6.8 to 8.4, a pH range in which cell viability was maintained during at least 1 hour. In the membrane-enriched fractions this phosphatase activity showed to be an acid phosphatase. In addition, intact cells could catalyze the dephosphorylation of [32P]phosphocasein phosphorylated at serine and threonine residues.

Relationship between biochemical markers of bone turnover and bone scintigraphic indices in assessment of Paget's disease activity

OBJECTIVE

To evaluate the relationship between biochemical markers of bone turnover and bone scan indices of disease activity, as well as to analyze their variations based on skeletal involvement, in Paget's disease.

METHODS

Serum samples were obtained from 51 patients with Paget's disease to determine the levels of total alkaline phosphatase (total AP), bone alkaline phosphatase (bone AP), propeptide carboxyterminal of type I procollagen (PICP), propeptide aminoterminal of type I procollagen (PINP), osteocalcin, tartrate-resistant acid phosphatase, and telopeptide carboxyterminal of type I collagen. Urine samples were analyzed for levels of hydroxyproline (HYP), pyridinoline (PYR), deoxypyridinoline (DPYR), C-terminal telopeptide of type I collagen (CTx), and N-terminal telopeptide of type I collagen (NTx). In addition, 2 semiquantitative scintigraphic indices, disease activity (AI) and disease extent (EI), were obtained. Pagetic skeletal locations were evaluated individually, with special attention to skull involvement.

RESULTS

All biochemical markers correlated with the AI and the EI. Serum PINP, bone AP, and total AP showed the highest proportions of increased values among the bone formation markers (94%, 82%, and 76%, respectively). Among the bone resorption markers, urinary NTx showed the highest proportion of increased values in patients with Paget's disease (96%), compared with PYR (69%), DPYR (71%), CTx (65%), and HYP (64%). In patients with mild disease activity, serum PINP was the marker with the highest proportion of increased values (71%). In contrast, serum PICP and urinary CTx were the most discriminative markers for skull involvement. Except for higher values for most of the biochemical markers of bone turnover in flat bones, no major differences in other skeletal locations were observed.

CONCLUSION

The determination of serum PINP as a marker of bone formation and urinary NTx as a marker of bone resorption provided the best biochemical profile to ascertain the extent and activity of Paget's disease. In patients with skull involvement, serum PICP and urinary CTx were shown to be the most discriminative markers.

Acid phosphatase in the pathogenic and nonpathogenic hemoflagellates, Cryptobia spp., of fishes

Acid phosphatase (ACP) was detected in whole-cell lysates, membrane-bound and water-soluble fractions of Cryptobia salmositica (pathogenic and nonpathogenic vaccine strains), Cryptobia bullocki, and Cryptobia catostomi using p-nitro-phenylphosphate as the substrate. High activities were in acidic pH (3.0-5.5) and the optimal pH was 5.0 Highest ACP activity was in the membrane-bound fraction. The pathogenic strain of C. salmositica had significantly higher total ACP activity than the vaccine strain and the other 2 species. However, the activity in the pathogenic C. salmositica decreased significantly with prolonged in vitro cultivation. The membrane-bound ACP of the pathogenic C. salmositica had highest resistance to the ACP inhibitor, sodium tartrate.

Synthesis and activity of pseudotripeptide inhibitors of HIV-1 protease containing D(-)-O-(benzyl)tartaric acid

Four HIV-1 protease inhibitors containing [(S,S)-O-(benzyl) tartaric acid]-Pro as a transition-state mimic were prepared and evaluated by a spectrophotometric assay. Two pseudotripeptide derivatives showed weak inhibitory activity similar to acetylpepstatin.