[Multidisciplinary treatment of amelogenesis imperfecta]. / Multidisciplinaire behandeling van amelogenesis imperfecta.

A healthy 13-year-old patient with amelogenesis imperfecta was referred by her orthodontist to the joint consultation hour (Center for Specialised Dentistry and Oral and Maxillofacial Surgery). In addition to her amelogenesis imperfecta, she was diagnosed with a class 2 malocclusion and a mandibular hypoplasia. She was treated successfully through a multidisciplinary approach.

Ektacytometry Analysis of Post-splenectomy Red Blood Cell Properties Identifies Cell Membrane Stability Test as a Novel Biomarker of Membrane Health in Hereditary Spherocytosis.

Hereditary spherocytosis (HS) is the most common form of hereditary chronic hemolytic anemia. It is caused by mutations in red blood cell (RBC) membrane and cytoskeletal proteins, which compromise membrane integrity, leading to vesiculation. Eventually, this leads to entrapment of poorly deformable spherocytes in the spleen. Splenectomy is a procedure often performed in HS. The clinical benefit results from removing the primary site of destruction, thereby improving RBC survival. But whether changes in RBC properties contribute to the clinical benefit of splenectomy is unknown. In this study we used ektacytometry to investigate the longitudinal effects of splenectomy on RBC properties in five well-characterized HS patients at four different time points and in a case-control cohort of 26 HS patients. Osmotic gradient ektacytometry showed that splenectomy resulted in improved intracellular viscosity (hydration state) whereas total surface area and surface-to-volume ratio remained essentially unchanged. The cell membrane stability test (CMST), which assesses the in vitro response to shear stress, showed that after splenectomy, HS RBCs had partly regained the ability to shed membrane, a property of healthy RBCs, which was confirmed in the case-control cohort. In particular the CMST holds promise as a novel biomarker in HS that reflects RBC membrane health and may be used to asses treatment response in HS.

Porous titanium scaffolds with injectable hyaluronic acid-DBM gel for bone substitution in a rat critical-sized calvarial defect model.

Demineralized bone matrix (DBM) is an allograft bone substitute used for bone repair surgery to overcome drawbacks of autologous bone grafting, such as limited supply and donor-site comorbidities. In view of different demineralization treatments to obtain DBM, we examined the biological performance of two differently demineralized types of DBM, i.e. by acidic treatment using hydrochloric acid (HCl) or treatment with the chelating agent ethylene diamine tetra-acetate (EDTA). First, we evaluated the osteo-inductive properties of both DBMs by implanting the materials subcutaneously in rats. Second, we evaluated the effects on bone formation by incorporating DBM in a hyaluronic acid (HA) gel to fill a porous titanium scaffold for use in a critical-sized calvarial defect model in 36 male Wistar rats. These porous titanium scaffolds were implanted empty or filled with HA gel containing either DBM HCl or DBM EDTA. Ectopically implanted DBM HCl and DBM EDTA did not induce ectopic bone formation over the course of 12 weeks. For the calvarial defects, mean percentages of newly formed bone at 2 weeks were significantly higher for Ti-Empty compared to Ti-HA + DBM HCl, but not compared to Ti-HA + DBM EDTA. Significant temporal bone formation was observed for Ti-Empty and Ti-HA + DBM HCl, but not for Ti-HA + DBM EDTA. At 8 weeks there were no significant differences in values of bone formation between the three experimental constructs. In conclusion, these results showed that, under the current experimental conditions, neither DBM HCl nor DBM EDTA possess osteo-inductive properties. Additionally, in combination with an HA gel loaded in a porous titanium scaffold, DBM HCl and DBM EDTA showed similar amounts of new bone formation after 8 weeks, which were lower than using the empty porous titanium scaffold. Copyright © 2016 John Wiley & Sons, Ltd.

A systematic review on the long-term success of calcium phosphate plasma-spray-coated dental implants.

The objectives of the current review were (1) to systematically appraise, and (2) to evaluate long-term success data of calcium phosphate (CaP) plasma-spray-coated dental implants in clinical trials with at least 5 years of follow-up. To describe the long-term efficacy of functional implants, the outcome variables were (a) percentage annual complication rate (ACR) and (b) cumulative success rate (CSR), as presented in the selected articles. The electronic search yielded 645 titles. On the basis of the inclusion criteria, 8 studies were finally included. The percentage of implants in function after the first year was estimated to be 98.4 % in the maxilla and 99.2 % in the mandible. The estimates of the weighted mean ACR-percentage increased over the years up to 2.6 (SE 0.7) during the fifth year of function for the maxilla and to 9.4 (SE 8.4) for the mandible in the tenth year of function. After 10 years, the mean percentage of successful implants was estimated to be 71.1 % in the maxilla and 72.2 % in the mandible. The estimates seem to confirm the proposed, long-term progressive bone loss pattern of CaP-ceramic-coated dental implants. Within the limits of this meta-analytic approach to the literature, we conclude that: (1) published long-term success data for calcium phosphate plasma-spray-coated dental implants are limited, (2) comparison of the data is difficult due to differences in success criteria among the studies, and (3) long-term CSRs demonstrate very weak evidence for progressive complications around calcium phosphate plasma-spray-coated dental implants.

Toward accelerated bone regeneration by altering poly(D,L-lactic-co-glycolic) acid porogen content in calcium phosphate cement.

This work aimed to compare in vitro degradation of dense PLGA microspheres and milled PLGA particles as porogens within CPC, considering that the manufacturing of milled PLGA is more cost-effective when compared with PLGA microspheres. Additionally, we aimed to examine the effect of porogen amount within CPC/PLGA on degradation and bone formation. Our in vitro results showed no differences between both forms of PLGA particles (as porogens in CPC; spherical for microspheres, irregular for milled) regarding morphology, porosity, and degradation. Using milled PLGA as porogens within CPC/PLGA, we evaluated the effect of porogen amount on degradation and bone forming capacity in vivo. Titanium landmarks surrounded by CPC/PLGA with 30 and 50 wt % PLGA, were implanted in forty femoral bone defects of twenty male Wistar rats. Histomorphometrical results showed a significant temporal decrease in the amount of CPC, for both formulas, and confirmed that 50 wt % PLGA degrades faster than 30 wt%, and allows for a 1.5-fold higher amount of newly formed bone. Taken together, this study demonstrated that (i) milled PLGA particles perform equal to PLGA microspheres, and (ii) tuning of the PLGA content in CPC/PLGA is a feasible approach to leverage material degradation and bone formation.

[Evidence-based clinical practice guidelines in oral care 2: process and content of evidence-based guideline development]. / Evidencebased klinische praktijkrichtlijnen in de mondzorg 2. Proces en inhoud van evidencebased richtlijnontwikkeling.

In 2014, an advisory report was published by a national working committee concerning how the current, applied method of evidence-based guideline development in healthcare can be used in oral care in a national guideline programme. In an independent Institute of Knowledge Translation in Oral Care, as yet to be established, primary and secondary oral care providers will participate in the programme in order to improve the quality of oral care in the Netherlands. With the launching of the Institute of Knowledge Translation in Oral Care, clinical guideline development will have the benefit of a structural approach, in which 3 successive steps can be distinguished: preparation, development and authorisation. In each of these steps, oral care providers and associations will be actively involved. In this way the aim is to give as much consideration as possible to the needs of those in the field of oral care in the choice of topics for guideline development and to secure the specific character of oral care in the actual establishment of guidelines for clinical practice.

Protein kinase A regulates expression of p27(kip1) and cyclin D3 to suppress proliferation of leukemic T cell lines.

Peripheral homeostasis and tolerance requires the suppression or removal of excessive or harmful T lymphocytes. This can occur either by apoptosis through active antigen-induced death or cytokine withdrawal. Alternatively, T cell activation can be suppressed by agents that activate the cAMP-dependent protein kinase (PKA) signaling pathway, such as prostaglandin E2. Stimulation of PKA inhibits lymphocyte proliferation and immune effector functions. Here we have investigated the mechanism by which activation of PKA induces inhibition of proliferation in human leukemic T cell lines. Using a variety of agents that stimulate PKA, we can arrest Jurkat and H9 leukemic T cells in the G(1) phase of the cell cycle, whereas cell viability is hardly affected. This G(1) arrest is associated with an inhibition of cyclin D/Cdk and cyclin E/Cdk kinase activity. Interestingly, expression of cyclin D3 is rapidly reduced by PKA activation, whereas expression of the Cdk inhibitor p27(kip1) is induced. Ectopic expression of cyclin D3 can override the growth suppression induced by PKA activation to some extent, indicating that growth inhibition of leukemic T cells by PKA activation is partially dependent on down-regulation of cyclin D3 expression. Taken together our data suggest that immunosuppression by protein kinase A involves regulation of both cyclin D3 and p27(kip1) expression.

Cyclin D3 regulates proliferation and apoptosis of leukemic T cell lines.

Activation of the T cell receptor in leukemic T cell lines or T cell hybridomas causes growth inhibition. A similar growth inhibition is seen when protein kinase C is activated through addition of phorbol myristate acetate. This inhibition is due to an arrest of cell cycle progression in G(1) combined with an induction of apoptosis. Here we have investigated the mechanism by which these stimuli induce inhibition of proliferation in Jurkat and H9 leukemic T cell lines. We show that expression of cyclin D3 is reduced by each of these stimuli, resulting in a concomitant reduction in cyclin D-associated kinase activity. This reduction in cyclin D3-expression is crucial to the observed G(1) arrest, since ectopic expression of cyclin D3 can abrogate the G(1) arrest seen with each of these stimuli. Moreover, ectopic expression of cyclin D3 also prevents the induction of programmed cell death by phorbol myristate acetate and T-cell receptor activation, leading us to conclude that cyclin D3 not only plays a crucial role in progression through the G(1) phase, but is also involved in regulating apoptosis of T cells.

Epidermal growth factor-induced activation and translocation of c-Src to the cytoskeleton depends on the actin binding domain of the EGF-receptor.

In the epidermal growth factor (EGF)-receptor signal transduction cascade, the non-receptor tyrosine kinase c-Src has been demonstrated to become activated upon EGF stimulation. In this paper we show that c-Src associates with the cytoskeleton and co-isolates with actin filaments upon EGF treatment of NIH-3T3 cells transfected with the EGF receptor. Immunofluorescence studies using CLSM show colocalization of F-actin and endogenous c-Src predominantly around endosomes and not on stress fibers and cell-cell contacts. Stimulation of EGF receptor-transfected NIH-3T3 cells with EGF induces an activation and translocation of c-Src to the cytoskeleton. These processes depend upon the presence of the actin binding domain of the EGF-receptor since in cells that express EGF-receptors lacking this domain, EGF fails to induce an activation and translocation to the cytoskeleton of c-Src. These data suggest a role for the actin binding domain of the EGF-receptor in the translocation of c-Src.

Protein tyrosine phosphatase activity as a diagnostic parameter in breast cancer.

Cellular phosphotyrosine levels are regulated by the balance between protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs). It is supposed that this balance is disturbed in tumour cells, making the increased or altered activity of PTKs and PTPs likely hallmarks of tumour tissues. Indeed it could be shown that the PTK activity was increased in breast cancer in correlation with prognosis (Hennipman et al., Cancer Res. 49, 516-522, 1989). In the present report we measured the PTP activities in breast cancer and normal breast tissues. An increase of approximately three- to four-fold was measured in the cytosolic tumour fractions compared to normal, whereas the solubilized membrane fraction PTP activity showed an increase in tumours of approximately 1.5-fold. Remarkably, the membrane PTP activity correlated with the presence of tumour positive axillary lymph nodes (p = 0.004), whereas the cytosolic PTP activity correlated with the mitotic index, a higher PTP activity occurring when the mitotic index was higher than 10 (p = 0.0004). These results indicate the membrane PTP activity may be considered as an index of metastatic potential, whereas cytosolic PTP activity may be a measure of the growth capacity of the tumour. The increase of PTP activity in breast cancers was confirmed by enzyme-histochemical studies. In frozen sections of tumours a strong to moderate activity was found in both tumour cells and interstitial cells. In the interstitium membrane activity was most pronounced, whereas in the tumour cells diffuse staining of the cytoplasm together with a clear membrane staining was demonstrated. Immunoblotting with anti-phosphotyrosine antibodies also reveals differences between the tumours and normal tissues, confirming the disturbance of the balance between protein tyrosyl phosphorylation and dephosphorylation in the tumour cells.

Protein tyrosine (de-)phosphorylation in head and neck squamous cell carcinoma.

Protein phosphorylation plays an important role in signal transduction of both normal and neoplastic cells. Since increased protein tyrosine phosphorylation may be associated with malignant transformation, we studied the activities of protein tyrosine kinases (PTK) and protein tyrosine phosphatases (PTPase) in patients with various head and neck tumors. Furthermore, we determined the patterns of tyrosine phosphorylated protein (P-tyr) in tissues by western blotting. Enzyme activities were studied in tumor and histologically normal, non-tumorous tissues of 54 patients and in 11 controls. P-tyr patterns were determined in 3 patients and 2 controls. PTK and PTPase activities were greater in tumor tissues than in normal tissue of the cancer patients as well as controls. P-tyr levels in tumors were also higher than in normal tissues. Additionally, PTK activity in normal tissue of tumor patients was significantly higher than in normal tissue of the control group. The same trend was observed for the PTPase activity and P-tyr levels.

Partial characterization of protein tyrosine kinases in human lymphoid cells.

We have examined several aspects of protein tyrosine kinase (PTK)-activity in the cytosolic and membrane fractions of both normal and malignant lymphoid cells. The expression of the PTK-encoding oncogenes fes, abl and src, was investigated with the use of antibodies generated to their respective gene products. These antibodies recognized proteins in all cell types examined, most frequently in both the cytosolic and the membrane fraction. PTKs were partially characterized by FPLC. PTK-activities of column fractions were assayed using a non-radioactive dot blot assay. Cytosolic and membrane fractions showed FPLC patterns with a constant as well as a variable part in both normal and malignant cells, suggestive of PTKs with specialized functions in normal cell growth and transformation. Lastly, using antibodies to phosphotyrosine, we found that cytosolic fractions contained the majority of proteins phosphorylated at tyrosine in all cell types. Normal peripheral blood lymphocytes and B-lymphoma cells showed a great similarity in tyrosine phosphorylation pattern, while in tonsillar lymphocytes a clearly different pattern was found. These methods further characterize PTK-activities in lymphoid cells, and the results give evidence that PTKs in normal and malignant cells have both similar and different aspects.

Pyruvate kinase activity and isozyme composition in normal fibrous tissue and fibroblastic proliferations.

Pyruvate kinase (PK) was studied in 57 fibroblastic and fibrohistiocytic proliferations and normal fibrous tissue (n = 10). The specific activity was significantly increased in malignant tumors (1.67 +/- 0.25) compared with normal tissue (0.26 +/- 0.04; P less than 0.001) and benign proliferations (0.52 +/- 0.05; P less than 0.005). Although an overlap exists between aggressive fibromatosis and the benign group, high values of PK activity are indicative of Grade 2 and 3 malignancy. Significant shifts in isozyme pattern, favoring the expression of K-type subunits were found in tumors with a metastasizing potential and aggressive fibromatosis. These changes in the isozyme pattern of PK in aggressive fibromatosis may act as another argument to place them in the category of malignant fibroblastic tumors.

Activity of glycolytic enzymes and glucose-6-phosphate dehydrogenase in smooth muscle proliferation.

The specific activity of hexokinase, phosphofructokinase, aldolase, enolase, pyruvate kinase and glucose-6-phosphate dehydrogenase was measured in 41 smooth muscle cell tumors: 20 leiomyomas and 21 cases of leiomyosarcoma. Statistical analysis revealed no significant differences in specific activity between normal smooth muscle tissue and the benign and malignant tumors originating from it. Quantification of the isozyme composition of pyruvate kinase showed a significant shift in isozyme pattern towards K-type subunits in leiomyosarcomas as compared to leiomyomas.

Activity of glycolytic enzymes and glucose-6-phosphate dehydrogenase in lipoblastic and neurogenic proliferations.

The alterations in specific activity and/or isozyme pattern of hexokinase, phosphofructokinase, aldolase, enolase, pyruvate kinase and glucose-6-phosphate dehydrogenase were studied in the tissue specimens of 26 patients with lipoblastic tumors and 28 patients with tumors of neurogenic origin. Although the biochemical data demonstrated that the activities of most enzymes studied were elevated in the specimens of the malignant tumors, only the differences in activity of hexokinase, pyruvate kinase and glucose-6-phosphate dehydrogenase measured between benign and malignant neurogenic tumors were significant. In malignant tumors, especially those of neurogenic origin, the isozyme pattern of pyruvate kinase showed a shift towards K-type subunits.

A nonradioactive dot-blot assay for protein tyrosine kinase activity.

A new procedure for the assay of protein tyrosine kinase, based on the detection of phosphorylated tyrosyl residues by using monoclonal antibodies to phosphotyrosine, is described. After incubation of a protein tyrosine kinase sample with the substrates poly-(GluNa,Tyr)4:1 and unlabeled ATP an aliquot of the reaction mixture is transferred to a polyvinylidene difluoride membrane. The extent of tyrosine phosphorylation is measured by probing the membrane with antiphosphotyrosine antibody followed by detection by the immunogold silver staining procedure. The signal is quantified by densitometry. The assay is linear with time and is quantitative in a wide range of sample protein concentrations. Its sensitivity allows the kinetic characterization of protein tyrosine kinases at low substrate concentrations, whereas on the other hand the avoidance of radioactivity enables the use of high ATP concentrations as well. Protein tyrosine kinase activities of human breast carcinomas and normal breast tissues measured with this method correlated well with the conventional assay, in which the incorporation of [32P]phosphate is measured by TCA precipitation and liquid scintillation counting. Compared to the latter, the new assay is at least as sensitive and accurate and harbors the advantage of the avoidance of radioactivity, thus enabling one to perform a large number of protein tyrosine kinase assays simultaneously.

Characterization of pyruvate kinase from human rhabdomyosarcoma in relation to immunohistochemical and morphological criteria.

We have compared the pyruvate kinase (PK) isoenzyme pattern of three rhabdomyosarcomas with foetal skeletal muscle tissue of 19 and 23 weeks of gestation, together with adult muscle in relation to immunohistochemical and morphological criteria. In foetal tissue of 19 weeks of gestation a focal immunopositivity for desmin and myoglobin was observed, whereas in tissue of 23 weeks an overall positivity for these proteins was present. Two of the three neoplasms were poorly differentiated and of the alveolar subtype. They were desmin immunoreactive. Some large spindle-shaped cells expressed myoglobin. The third one was more differentiated in microscopic characteristics and all cells showed immunoreactivity for desmin and myoglobin. In the foetal tissues five forms of pyruvate kinase isoenzymes were present with K2M2 as the predominant form. In adult muscle tissue only M4 was present. The tumors were characterized by a profound shift to the K-type, whereas the M4-type was not expressed at all. A difference in isoenzyme composition of pyruvate kinase was found between the morphologically less differentiated tumors and the more differentiated tumor; in the latter more M-subunits were expressed.

Tyrosine kinase activity in breast cancer, benign breast disease, and normal breast tissue.

Tyrosine specific protein kinase activity was determined in 70 specimens of the human mammary gland. These included 28 cancers of the breast, 21 benign breast diseases, and 21 normal breast tissues. We measured tyrosine kinase activity in the cytosol fraction and in the membrane fraction of the homogenates. In addition cytosolic aldolase activity was measured. Tyrosine kinase activity was determined using poly(glutamic acid:tyrosine = 4:1) as an artificial substrate. Cancers of the breast exhibited considerable higher tyrosine kinase activities in both cytosol and membrane fractions, compared to benign breast tumors (P less than or equal to 0.001). Benign tumors demonstrated increased activities in cytosol in comparison to normal breast tissues (P less than 0.001). Furthermore, there appears to be a strong association of an enhanced expression of activity of tyrosine kinase in cytosol of primary carcinomas and early systemic relapse. In combination with aldolase activity a nearly complete discrimination is achieved between malignant specimens on one hand and benign and normal tissues on the other.

Glycolytic enzyme activities in breast cancer metastases.

The activities of hexokinase, phosphofructokinase, aldolase, enolase and pyruvate kinase were studied in breast cancer metastases occurring at various sites and compared with the enzyme activities in a series of primary breast cancers. The activities of all enzymes studied were significantly higher in the metastases compared to the primary tumors (p less than or equal to 0.05). However, no changes in the isoenzyme patterns of enolase and pyruvate kinase were observed when the metastases were compared with primary breast cancers. Differences in location of the metastases did not lead to differences in enzyme activities. Our data suggest an association of an increasing rate of glycolysis with tumor progression.