Strategies against acid induced hydroxyapatite dissolution of human dental enamel

Dental erosion is the dissolution of dental hard tissue without the involvement of bacteria. It is well known that acid containing food and beverages lead to the erosive damage of dental enamel. This disease occurs mainly in children and has increased dramatically in the last years and, thus, moved in the focus of scientific investigations. The current work investigated the process of tooth erosion with an in vitro model system and developed new strategies against the process of dental erosion based on the modification of erosion inducing acidic soft drinks. Influencing factors were systematically changed and the erosion effect on in vitro enamel was investigated quantitatively and qualitatively. New insights are presented to much better understand the process of erosion and to possibly reduce the erosion on human dental enamel. Profilometry and AFM-based nanoindentation were used to investigate the long time and the short time erosion process on human dental enamel. Moreover, different food-approved polymers (propylene glycol alginate, high-esterified pectin and gum arabic) were investigated for their erosion inhibiting effects. The addition of these polymers to citric acid solutions showed a significantly reduced hardness loss of enamel compared to enamel treated with unmodified citric acid solutions. The current work gives also insights into the interaction of the polymers and the enamel surface in vitro. This interaction led to the formation of a layer consisting of polymer molecules and hydroxyapatite particles, which protects the underlying enamel against erosion caused by citric acid. In addition, with a proper choice of the acids used for soft drinks, the enamel softening can be significantly influenced. The strategies presented in the current study are based on the modification of acidic soft drinks and give the possibility to significantly reduce the acid triggered process of dental erosion

Combined Application of 17β-Estradiol and Progesterone Enhance Vascular Endothelial Growth Factor and Surfactant Protein Expression in Cultured Embryonic Lung Cells of Mice

Preterm delivery is associated with disruption of the placental supply with 17β-estradiol (E2) and progesterone (P). The aim is to evaluate the role of E2 and P on the regulation of key proteins in lung development in embryonic lung cells. Alveolar cell type II (AT-II) and central lung fibroblast cultures were established from mouse embryos. Cells were exposed for 24 hours to E2 and/or P, the estrogen receptor antagonist ICI 182.780 (ICI) and the progesterone receptor antagonist mifepristone (RU 486). The mRNA expression of vascular endothelial growth factor (VEGF) and surfactant protein B and C (SB-B, SB-C) was determined, and protein levels of VEGF were measured. Only the combined treatment with E2 and P increased mRNA expression and VEGF protein in AT-II cells and lung fibroblasts. Combined treatment also promoted SP-B and SP-C expression in AT-II cells. Pretreatment with ICI and RU 486 completely abolished the E2 and P induced effects. E2 and P enhanced expression of VEGF and surfactant proteins in primary embryonic lung cells and may be involved in regulating expression of key molecules for the prenatal lung development and postnatal lung function

Prognostic relevance of MMP-2 (72-kD collagenase IV) in gastric cancer

The association of MMP-2 (matrix metalloproteinase 2, 72-kD collagenase IV) with invasive and metastatic capacity of tumor cells has implicated a potential role in the prognosis for cancer patients. However, no larger study has been done to prove this hypothesis. The present study was therefore designed to investigate the prognostic impact of MMP-2 in a prospective series of 203 gastric cancer patients. MMP-2 expression was measured immunohistochemically and scored semiquantitatively (score 0-3) in carcinoma cells, and results were correlated with clinicopathological tumor parameters and parameters of the urokinase-type plasminogen activator (uPA) system. Survival analyses were done using the Kaplan-Meier method (log-rank statistics) and multivariate Cox analysis. Significant correlations were found for MMP-2 and Lauren's classification, M stage and proteases/inhibitors of the uPA system in the primary tumor. Kaplan-Meier analysis revealed an association of increasing MMP-2 expression with worse prognosis. This was especially seen in patients with a parallel high expression of uPA receptor. However, differences in survival probabilities between low and high MMP-2 levels were not significant. In a separate analysis of diffuse-type cancers, MMP-2 was significantly associated with disease-free (p = 0.0056) and overall survival (p = 0.0426). Multivariately, MMP-2 was not an independent parameter. Our results demonstrate that there is an association of immunohistochemical detection of MMP-2 with prognosis of cancer patients. For diffuse gastric cancers, it is a significant prognostic parameter, however, not of independent impact. The study further suggests that consideration of interrelated tumor-associated proteases like uPA receptor in combination with MMP-2 may improve its prognostic power

Semi-Automated Location Planning for Urban Bike-Sharing Systems

Bike-sharing has developed into an established part of many urban transportation systems. However, new bikesharing systems (BSS) are still built and existing ones are extended. Particularly for large BSS, location planning is complex since factors determining potential usage are manifold. We propose a semi-automatic approach for creating or extending real-world sized BSS during general planning. Our approach optimizes locations such that the number of trips is maximized for a given budget respecting construction as well as operation costs. The approach consists of four steps: (1) collecting and preprocessing required data, (2) estimating a demand model, (3) calculating optimized locations considering estimated redistribution costs, and (4) presenting the solution to the planner in a visualization and planning front end. The full approach was implemented and evaluated positively with BSS and planning experts

Superhelasticity in aged single crystals of FeMnAlNi alloy

На [112]-монокристаллах Fe[43,5]Mnx[34]Al[15]Ni[7,5] показано, что при старении при T=437 K, 3 h наблюдается высокотемпературная сверхэластичность при деформации растяжением в температурном интервале от 298 K до 473 K. Экспериментально установлено, что механические и функциональные свойства зависят от ориентации кристалла, которая определяет вклад деформации раздвойникованием [epsilon][detw] в теоретическую величину деформации решетки

Stability study of a model for the Klein-Gordon equation in Kerr spacetime

The current early stage in the investigation of the stability of the Kerr metric is characterized by the study of appropriate model problems. Particularly interesting is the problem of the stability of the solutions of the Klein-Gordon equation, describing the propagation of a scalar field of mass $\mu$ in the background of a rotating black hole. Rigorous results proof the stability of the reduced, by separation in the azimuth angle in Boyer-Lindquist coordinates, field for sufficiently large masses. Some, but not all, numerical investigations find instability of the reduced field for rotational parameters $a$ extremely close to 1. Among others, the paper derives a model problem for the equation which supports the instability of the field down to $a/M \approx 0.97$.Comment: Updated version, after minor change

The Clinical and Socio-Economic Relevance of Increased IPMN Detection Rates and Management Choices

Background: Increased usage of computed tomography and magnetic resonance imaging has led to a large increase in identified pancreatic cysts of up to 25% in population-based studies. The clinical and economic relevance of identifying so many cystic lesions has not been established. Compared to other organs such as liver or kidney, dysontogenetic pancreatic cysts are rare. Pancreatic cysts comprise a variety of benign, premalignant or malignant lesions; however, precise diagnosis before resection has an accuracy of only 80%. The focus of recent research was the malignant potential of intraductal papillary mucinous neoplasms (IPMN) with the aim of establishing clinical pathways addressing risk of malignancy, age and comorbidity, treatment-related morbidity and mortality as well as cost-effectiveness of treatment and surveillance. The focus of this review is to analyze the clinical and socio-economic relevance as well as the cost-benefit relation for IPMNs. Methods: For analysis, the following MESH terms were used to identify original articles, reviews, and guidelines in PubMed: (‘intraductal papillary mucinous neoplasm' OR ‘pancreatic cysts') and (incidence OR relevance OR socio-economic OR economic OR cost-effectiveness OR cost-benefit). The retrieved publications were reviewed with a focus on clinical and socio-economic relevance in relation to the increasing incidence of IPMN. Results: Addressing the increasing prevalence of pancreatic cystic lesions, recent consensus guidelines suggested criteria for risk stratification according to ‘worrisome features' and ‘high-risk stigmata'. Recent prospective cohort studies evaluated whether these can be applied in clinical practice. Evaluation of three different clinical scenarios with regard to costs and quality-adjusted life years suggested a better effectiveness of surveillance after initial risk stratification by endoscopic ultrasound-guided fine-needle aspiration with cyst fluid analysis compared with immediate resection or follow-up without further intervention. Of interest, the ‘immediate surgery' strategy was lowest for cost-effectiveness. Conclusions: The increasing incidence of identified pancreatic cysts requires an improved strategy for non-invasive risk stratification based on advanced imaging strategies. In light of a malignancy risk of 2% for branch-duct IPMN, the socio-economic necessity of a balance between surveillance and resection has to be agreed on