| 1. |
- Säll, Johanna, et al.
(författare)
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The antimicrobial peptide LL-37 alters human osteoblast Ca2+ handling and induces Ca2+-independent apoptosis
- 2013
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Ingår i: Journal of Innate Immunity. - : S. Karger. - 1662-811X .- 1662-8128. ; 3:5, s. 290-300
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Tidskriftsartikel (refereegranskat)abstract
- The human antimicrobial peptide cathelicidin LL-37 has, besides its antimicrobial properties, also been shown to regulate apoptosis in a cell type-specific manner. Mechanisms involved in LL-37-regulated apoptotic signaling are not identified. Here, we show that LL-37 reduces the human osteoblast-like MG63 cell number and cell viability in the micromolar concentration range with an IC50 value of about 5 µM. Treatment with 4 µM LL-37 increased the number of annexin V-positive cells and stimulated activation of caspase 3 showing that LL-37 promotes apoptosis. Treatment with 4 µM LL-37 caused an acute and sustained rise in intracellular Ca(2+) concentration assessed by laser-scanning confocal microscopy of Fluo-4-AM-loaded MG63 cells. LL-37 increased Ca(2+) also in the presence of the respective L- and T-type voltage-sensitive Ca(2+) channel blockers nifedipine and NiCl2. LL-37 had no effect on Ca(2+) in cells incubated with Ca(2+)-free solution. LL-37 (4 and 8 µM) reduced the MG63 cell number both in the presence and absence of Ca(2+) in the medium. In conclusion, LL-37 reduces the osteoblast cell number by promoting apoptosis, and furthermore, LL-37 stimulates Ca(2+) inflow via a mechanism independent of voltage-sensitive Ca(2+) channels. Interestingly, LL-37-induced lowering of the cell number seems to be mediated via a mechanism independent of Ca(2+).
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| 2. |
- Aidoukovitch, Alexandra, et al.
(författare)
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Strontium chloride promotes cell proliferation in a human osteoblast cell line
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Strontium ranelate (SrRan) is the active component of drugs currently used for reducing the risk of fractures in patients suffering from osteoporosis. Despite extensive use, the underlying mechanisms of action of Sr2+ are not fully understood. In the present study, we assess the impact of SrCl2 on human osteoblast activity and proliferation. Cultures of the human osteoblast-like cell line MG63 were treated for 72 h in presence of 0.1 mM, 1 mM, 5 mM and 10 mM SrCl2 or vehicle, used in control groups. Cells were counted manually using a Bürker chamber. Total protein content was determined by colorimetric analysis performed by a microplate reader using Bio-Rad protein assay. Alkaline phosphatase (ALP) activity was determined enzymatically and normalized to total protein content in each sample. Cell viability was assessed using the MTT assay. Treatment with 5 mM SrCl2 for 72 h enhanced total MG63 cell protein content by 37% compared to controls (p<0.01). A lower concentration (0.1 mM) of SrCl2 had no effect on total protein. Incubation with 5 mM SrCl2 for 72 h increased MG63 cell number by 38% compared to controls (p<0.001). The SrCl2-induced increase in cell number was associated with enhanced (+14% compared to controls, p<0.05) cell viability. Treatment with a higher concentration (10 mM) of SrCl2 enhanced cell number similar to 5 mM SrCl2 (+54% compared to controls, p<0.05). Treatment with 0.1 or 5 mM SrCl2 for 72 h had no effect (p>0.05) on MG63 cell ALP activity, while 1 mM SrCl2 reduced ALP activity as well as total protein content by about 25% compared to controls (p<0.05). The current results demonstrate that treatment with SrCl2 for 72 h, at concentrations higher than 1 mM promotes cell proliferation in human osteoblast-like cells, suggesting that Sr2+ may enhance bone formation through this mechanism.
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| 3. |
- Baravdish, George, et al.
(författare)
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Extension of p-Laplace Operator for Image Denoising
- 2016
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Ingår i: 27th IFIP TC 7 Conference, CSMO 2015, Sophia Antipolis, France, June 29 - July 3, 2015, Revised Selected Papers. - Cham : Springer. - 9783319557946 - 9783319557953 ; , s. 107-116, s. 107-116
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Bokkapitel (refereegranskat)abstract
- In this work we introduce a novel operator $$\displaystyle \varDelta _(p,q)$$ as an extended family of operators that generalize the p-Laplace operator. The operator is derived with an emphasis on image processing applications, and particularly, with a focus on image denoising applications. We propose a non-linear transition function, coupling p and q, which yields a non-linear filtering scheme analogous to adaptive spatially dependent total variation and linear filtering. Well-posedness of the final parabolic PDE is established via pertubation theory and connection to classical results in functional analysis. Numerical results demonstrates the applicability of the novel operator $$\displaystyle \varDelta _(p,q)$$ .
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| 4. |
- Baravdish, George, 1964-, et al.
(författare)
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Generalizations of p-Laplace operator for image enhancement : Part 2
- 2020
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Ingår i: Communications on Pure and Applied Analysis. - Springfield, MO, United States : American Institute of Mathematical Sciences. - 1534-0392 .- 1553-5258. ; 19:7, s. 3477-3500
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Tidskriftsartikel (refereegranskat)abstract
- We have in a previous study introduced a novel elliptic operator Delta((p,q))u = vertical bar del u vertical bar(q) Delta(1)u + (p - 1) vertical bar del u vertical bar(p-2)Delta(infinity) u, p >= 1, q >= 0, as a generalization of the p-Laplace operator. In this paper, we establish the well-posedness of the parabolic equation u(t) =vertical bar del u vertical bar(1-q) Delta((1+q,q)), where q = q(vertical bar del u vertical bar) is continuous and has range in [0, 1], in the framework of viscosity solutions. We prove the consistency and convergence of the numerical scheme of finite differences of this parabolic equation. Numerical simulations shows the advantage of this operator applied to image enhancement.
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| 5. |
- Baravdish, George, 1964-, et al.
(författare)
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On a new singular and degenerate extension of the p-Laplace operator
- 2024
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Ingår i: Nonlinear Analysis. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0362-546X .- 1873-5215. ; 244
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Tidskriftsartikel (refereegranskat)abstract
- We study a novel degenerate and singular elliptic operator Δ˜(τ,χ) defined by Δ˜(τ,χ)u=τ(x,Du)(|Du|Δ1u+χ(x,Du)Δ∞u), where the singular weights τ(x,s)>0 and χ(x,s)≥0 are continuous functions on Ω×Rn∖{0}. The operator Δ˜(τ,χ) is an extension of Δ(p,q)u=|Du|qΔ1u+(p−1)|Du|p−2Δ∞u,p≥1,q≥0, introduced by the authors in Baravdishet al. (2020), which in turn is an extension of the p-Laplace operator Δp. We establish the well-posedness of the Neumann boundary value problem for the parabolic equation ut=Δ˜(τ,χ)u in the framework of viscosity solutions. For the solution u, the weight χ controls the evolution along the tangential and the normal directions, respectively, on the level surface of u. The weight τ controls the total speed of the evolution of u. We also prove the consistency and the convergence of the numerical scheme for the finite differences method of the parabolic equation above. Numerical simulations show that our novel nonlinear operator Δ˜(τ,χ) gives better results than both the Perona–Malik (Perona and Malik, 1990) and total variation (TV) methods (Chan and Shen, 2005) when applied to image enhancement.
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| 6. |
- Fernandes, Cláudio Pinheiro, et al.
(författare)
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A Novel Sensor for Bite Force Determinations
- 2003
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Ingår i: Dental Materials. - 0109-5641 .- 1879-0097. ; 19:2, s. 118-126
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- OBJECTIVES: The clinical usefulness, accuracy and precision of a novel bite force sensor based on force sensing resistors were tested in six subjects wearing maxillary removable partial dentures retained by conical crowns. METHODS: The surfaces of the sensor were manufactured in a silicone material that had mechanical properties similar to those of tough foodstuffs. In two separate series of standardized bite force tests, submaximum force levels were recorded with the sensor and with a strain gaged bite fork. Subjects were assisted in the loading tests with visual feedback instrumentation. Reliability estimates for the bite force sensor were calculated in order to show their reproducibility. Strain gages attached to the prostheses were used to determine the pattern of force distribution during loading tests. The bite force results obtained with the new bite force sensor and with the bite fork were analyzed with ANOVA and Scheffes tests. The strain patterns registered with strain gages were analyzed with F-test. RE-SULTS: The bite force sensor and the bite fork transducer showed no statistically significant differences in respect of intra-individual bite force levels (range 50-300N). The bite forces registered with the new sensor were dependent on the loading position (p<0.05), sex (p<0.05) and test subject (p<0.05). The reliability of the new sensor for sub-maximum bite forces was calculated to be 93%. Strain gage results showed that the new sensor generated strain patterns of less variance (p<0.05) than the bite fork and therefore allowed for higher precision during biting tests. SIGNIFICANCE: The presented instrument has such clinical merits, as to favor its use in experimental clinical studies on the biomechanics of prosthetic appliances.
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| 7. |
- Fernandes, CP, et al.
(författare)
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Reflection photoelasticity: a new method for studies of clinical mechanics in prosthetic dentistry
- 2003
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Ingår i: Dental Materials. - 0109-5641 .- 1879-0097. ; 19:2, s. 106-117
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Tidskriftsartikel (refereegranskat)abstract
- Objectives. This research was conducted to demonstrate the effectiveness of reflective photoelasticity as an in vivo technique for monitoring the strain/stress distribution in prosthetic devices during function. Methods. Seven subjects were selected for this study and divided into three groups according to the design of the prostheses. The buccal surfaces of the experimental prostheses were coated with a birefringent resin 2 mm thick. Using a reflection polariscope, fringe patterns were documented on video tape during standardized in vivo loadings. Strain and stress levels (gamma(max) and tau(max)) were calculated from isochromatic fringe order determinations. The intra-observer variability in counting fringe orders and the accuracy level of reflective photoelasticity as compared to strain gauge results were also studied. The strain results of in vivo loading of the prostheses were analyzed with ANOVA and Scheffes tests. The intra-observer variability was analyzed with the Friedman nonparametric test. Comparisons of photoelastic data and strain gauges were tested with Pearson's correlation. Results. Coated areas accessible to normally incident light, produced comprehensive maps of strain distribution. Significant differences were found in the in vivo gamma(max) values for the prostheses designs (p < 0.05). The test for intra-observer variability showed that no significant differences occurred in counting fringe orders. Strain values obtained with reflective photoelasticity showed a high correlation r = 0.98 and 0.99) with values obtained at the same areas using strain gauges. Significance. Reflective photoelasticity is a valid, reliable and accurate technique to be used for in vivo studies on the biomechanical behavior of prosthetic devices. (C) 2003 Academy of Dental Materials. Published by Elsevier Science Ltd. All rights reserved.
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| 8. |
- Haberska, Karolina, et al.
(författare)
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Activity of lactoperoxidase when adsorbed on protein layers
- 2008
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Ingår i: Talanta. - : Elsevier. - 0039-9140 .- 1873-3573. ; 76:5, s. 1159-1164
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Tidskriftsartikel (refereegranskat)abstract
- Lactoperoxidase (LPO) is an enzyme, which is used as an antimicrobial agent in a number of applications, e.g., food technology. In the majority of applications LPO is added to a homogeneous product phase or immobilised on product surface. In the latter case, however, the measurements of LPO activity are seldom reported. In this paper we have assessed LPO enzymatic activity on bare and protein modified gold surfaces by means of electrochemistry. It was found that LPO rapidly adsorbs to bare gold surfaces resulting in an amount of LPO adsorbed of 2.9 mg/m2. A lower amount of adsorbed LPO is obtained if the gold surface is exposed to bovine serum albumin, bovine or human mucin prior to LPO adsorption. The enzymatic activity of the adsorbed enzyme is in general preserved at the experimental conditions and varies only moderately when comparing bare gold and gold surface pretreated with the selected proteins. The measurement of LPO specific activity, however, indicate that it is about 1.5 times higher if LPO is adsorbed on gold surfaces containing a small amount of preadsorbed mucin in comparison to the LPO directly adsorbed on bare gold.
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