Okadaic acid inhibits alkaline phosphatase activity in MC3T3-E1 cells

Alkaline phosphatase activity is regulated by various hormones and growth factors at least in part through the phosphorylation of target proteins during the bone cell differentiation. To investigate the role of protein phosphorylation in alkaline phosphatase activity in MC3T3-E1 osteoblast, we used okadaic acid which is a potent specific inhibitor of serine/threonine protein phosphatases to type 1 and 2A. Alkaline phosphatase activity in cellular layer was measured by spectrophotometer using p-nitrophenyl phosphate as substrate and data were expressed as p-nitrophenyl of nmol/min/mg of protein. Okadaic acid (1-50 ng/ml) caused the inhibition of alkaline phosphatase activity in MC3TC-E1 cells. At 50 ng/ml of okadaic acid showed the maximal inhibitory effect on alkaline phosphatase activity. Okadaic acid (50 ng/ml) also inhibited alkaline phosphatase activity in all differentiation stages. These results indicate that okadaic acid inhibits alkaline phosphatase activity in MC3T3-E1 cells.     

Colchicine increases hepatic alkaline phosphatase activity

In vivo administration of colchicine increases the activity of alkaline phosphatase significantly in the livers of rats. Prior treatment with cycloheximide prevented the induction of the enzyme by colchicine suggesting that de novo protein synthesis was essential for the effect of colchicine on alkaline phosphatase activity. Bilateral adrenalectomy did not affect the response of alkaline phosphatase following the administration of colchicine. This indicates that the rise in the level of alkaline phosphatase in liver caused by colchicine is not secondary to the release of glucocorticoids.     

Regulation of alkaline phosphatase gene expression in human hepatoma cells by bile acids

HHV8 is a new herpesvirus recently identified in the Kaposi's sarcoma lesions, and initially named Kaposi's sarcoma-associated herpesvirus. It is a member of gamma-2 herpesvirus family and it shows a number of homologies with the Epstein-Barr virus and the herpesvirus saimiri. HHV8 genome also codes for several proteins which are homologous to cellular proteins and could disturb the regulation mechanisms of cellular proliferation and apoptosis. This is the case for a viral IL6, an antiapoptotic factor homologous to Bcl2, a viral cyclin, a member of the IRF family (interferon regulatory factors) and a G-protein-coupled receptor homologous to the IL8 receptor. Seroprevalence studies showed that HHV8 infection was not ubiquitous but rather limited to some geographic areas (Italy, Greece, Africa), and to some populations of homosexual and bisexual individuals with sexually transmitted diseases. To date, several lines of epidemiologic evidence suggest that this virus is sexually transmitted, although other routes of transmission cannot be excluded.     

Extracts of Prevotella intermedia and Actinobacillus actinomycetemcomitans inhibit alkaline phosphatase activity in osteoblastic cells in vitro

A prospective, randomized study was carried out to evaluate functional and biomicroscopic long-term results of different posterior chamber intraocular lenses (IOLs) over a period of two years after clear corneal cataract surgery. PATIENTS AND METHODS: 2 years after phacoemulsification through a temporal two-step clear corneal incision a total of 67 patients were examined. In 26 eyes (group A) a foldable plate-haptic silicone IOL (Chiron Adatomed, C10), in 25 eyes (group B) a foldable disc silicone IOL (Chiron Adatomed, 90D) had been implanted through a 3.5 (group A) or 4 mm (group B) corneal incision using a cartridge injector. In 16 eyes (group C) a one-piece PMMA-IOL (Pharmacia & Upjohn, 809C) had been implanted through a 5 mm incision. All eyes underwent functional and biomicroscopic examinations, as well as computerized videokeratographic analysis to obtain corneal topography data. RESULTS: In group A uncorrected visual acuity valued 0.64 (+/-0.29 SD), in group B 0.59 (+/-0.24) and in group C 0.56 (+/-0.27). Median of uncorrected visual acuity was 0.6 for all groups. Corrected visual acuity was 0.81 (+/-0.29) in group A, 0.8 (+/-0.25) in group B and 0.83 (+/-0.3) in group C. Intraocular pressure (mm Hg) was 13 (+/-2.5) in group A, 14.7 (+/-2) in group B and 15.1 (+/-2.5) in group C. Fibrosis of the anterior capsular rim occurred in 42% of the cases. One eye demonstrated folds in the posterior capsule (group B). Posterior capsular opacification valued 11.9% for all groups. In one eye a Nd:YAG-capsulotomy had already been performed. In group A a decentration of more than 1 mm was objected in one case, in group B in two cases and in group C in one case, but no patient complained about any functional impairment. Two years postoperatively, no signs of a re-flattening in the incision area could be detected using difference mapping tools in the videokeratographic analysis. CONCLUSION: Two years after implantation of foldable silicone IOLs and PMMA-IOLs via a temporal clear corneal tunnel incision after phacoemulsification only slight functional and morphologic differences between the three IOL-types could be observed.     

Effect of polyethylene on osteocalcin, alkaline phosphatase and procollagen secretion by human osteoblastic cells

BACKGROUND AND STUDY AIMS: Anastomotic leakage is a severe complication in gastric surgery and it is associated with a high rate of mortality. Conservative treatment sometimes is not sufficient to stem the leakages and, even when it is sufficient, it takes a long time. The present study describes the first experience in the treatment of anastomotic leakages with endoscopic clipping. PATIENTS AND METHODS: From May 1995 to December 1996, seven patients with postoperative anastomotic leakages after gastric surgery were prospectively treated in our Endoscopy Service. Metallic endoclips (MD 850, Olympus Corp., Tokyo, Japan) with prongs 12 mm long and 6 mm wide were applied, controlling the closure of the leakage by endoscopy, using radiographs to confirm the closure 24 hours later. RESULTS: Complete closure of the leakage was obtained in all seven cases. A single session of endoscopic clipping was needed for five patients while two other required, respectively, two and three sessions. The median time of leakage closure after endoscopic clipping was 2.3 days (range 1-5 days). The clips spontaneously dislodged within 1 month in five patients and within the second month in the other two patients. CONCLUSION: Endoscopic treatment of anastomotic leakages by metallic clips represents a safe and easily repeated method and, compared to conservative treatment, it seems to offer several time and cost advantages. Further studies involving a larger number of patients are needed to verify this finding.     

Plasma bone-specific alkaline phosphatase as an indicator of osteoblastic activity

The total plasma alkaline phosphatase level has long been recognised as an indicator of osteoblastic activity, but lack of specificity makes it an insensitive index of the progress of disease and the response to treatment. Selective precipitation by wheatgerm lectin allows measurement of the plasma bone-specific alkaline phosphatase. We measured the plasma levels of this isoenzyme in 170 normal Chinese adolescents and adults, in 49 adults with fractures of a long bone, in 15 patients with osteosarcoma and in 38 patients with osteolytic metastases. The enzyme activity was also determined in 39 patients with liver disease. Of the patients with fractures, 94% had increased plasma activity during the healing process. The level was also increased in those with osteosarcoma but not in those with osteolytic bone metastases. There was no significant increase in activity in the patients with liver disease. We conclude that the plasma bone-specific alkaline phosphatase activity is a sensitive and reliable measure of osteoblastic activity.     

Gallium nitrate inhibits alkaline phosphatase activity in a differentiating mesenchymal cell culture

The effect of gallium nitrate on alkaline phosphatase activity in a differentiating chick limb-bud mesenchymal cell culture was monitored in order to gain insight into the observation that rachitic rats treated with gallium nitrate failed to show the expected increase in serum alkaline phosphatase activity. Cultures maintained in media containing 15 microM gallium nitrate showed drastically decreased alkaline phosphatase activities in the absence of significant alterations in total protein synthesis and DNA content. However, addition of 15 microM gallium nitrate to cultures 18 h before assay for alkaline phosphatase activity had little effect. At the light microscopic and electron microscopic level, gallium-treated cultures differed morphologically from gallium-free cultures: with gallium present, there were fewer hypertrophic chondrocytes and cartilage nodules were flatter and further apart. Because of altered morphology, staining with an antibody against chick cartilage alkaline phosphatase appeared less extensive; however, all nodules stained equivalently relative to gallium-free controls. Histochemical staining for alkaline phosphatase activity was negative in gallium-treated cultures, demonstrating that the alkaline phosphatase protein present was not active. The defective alkaline phosphatase activity in cultures maintained in the presence of gallium was also evidenced when cultures were supplemented with the alkaline phosphatase substrate, beta-glycerophosphate (beta GP). The data presented suggest that gallium inhibits alkaline phosphatase activity in this culture system and that gallium causes alterations in the differentiation of mesenchymal cells into hypertrophic chondrocytes.     

The effect of zinc on alkaline phosphatase activity in rheumatoid synovial tissue

To examine the reported beneficial effect of zinc in rheumatoid arthritis, rheumatoid synovial tissue has been maintained in vitro in non-proliferative culture with or without zinc sulphate in the culture medium. Alkaline phosphatase activity was measured by microdensitometry of the cytochemical reaction in cryostat sections; the activity in blood vessels was measured separately from that in the supporting tissue below the synovial surface. Zinc enhanced this activity optimally at concentrations of between 10(-5) and 10(-4) mol/l.     

3Beta-hydroxysteroid dehydrogenase activity in human osteoblast-like cells

In spite of improvements in single or double lung transplantation (LT) technique, complications after LT are not uncommon; the most frequent ale anastomotic complications, infections and rejection (acute or chronic). Early detection of complications of LT allows the optimal therapeutic option to be taken, yielding decreased morbidity and mortality. In some cases, CT plays a key role in early detection of several complications of LT that may not be depicted with other diagnostic modalities, so that knowledge of their CT features is important. In this pictorial review, the authors describe the spectrum of CT features of the complications of LT (including reimplantation response, mechanical problems, acute and chronic rejection, infection, lymphoproliferative disorders, recurrence of the initial disease and complications involving the pleura and the anastomotic sites). In addition, the authors analyze the value of CT compared to that of the other available modalities for the detection of complications of LT.     

Partial purification and some properties of human liver alkaline phosphatase

1. Alkaline phosphatase (EC 3.1.3.1) from human liver was solubilized from the homogenate using 0.2% Triton X-100 containing 0.2 M lithium 3,5-diiodosalicylate, and the pellet obtained was resolubilized with 20% n-butanol. The procedure resulting in 3842-fold purification included acetone fractionation, ammonium sulfate precipitation, DEAE-cellulose chromatography, Sephadex G-200 gel filtration, hydroxyapatite gel chromatography and further concanavalin A/Sepharose 4B affinity chromatography. 2. The highly purified enzyme showed one major protein band on acrylamide gel electrophoresis at pH 8.6, and exhibited one-seventh of the alkaline p-nitrophenylphosphatase activity in the hepatic enzyme preparation contains of the alkaline pyrophosphatase activity. 3. The highly purified enzyme was a sialic-acid containing glycoprotein. 4. Sialidase-treated hepatic enzyme clearly presented the phenomenon of delayed mobility, and the delayed enzyme fraction stained more strongly than that of non-treated hepatic alkaline phosphatase. 5. In order to investigate the role of the carbohydrate region(s) of the hepatic alkaline phosphatase molecule on substrate binding, the effect of sialidase treatment on the rate of substrate inhibition of alkaline phosphatase was studied. In the case of hepatic enzyme without sialidase, substrate inhibition of alkaline phosphatase activity was clearly shown, while in the case of the hepatic enzyme with sialidase, there was hardly any substrate inhibition in the range of 1-8 mM p-nitrophenylphosphate.