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Selected Abstracts

Spatio-temporal statistical modelling of significant wave height

ENVIRONMETRICS, Issue 1 2009
A. Baxevani
Abstract In this paper, we construct a homogeneous spatio-temporal model to describe the variability of significant wave height over small regions of the sea and over short periods of time. Then, the model is extended to a non-homogeneous one that is valid over larger areas of the sea and for time periods of up to 10 h. To validate the proposed model, we reconstruct the significant wave height surface under different scenarios and then compare it to satellite measurements and the C-ERA-40 field. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Application of crosslinkers to dentin collagen enhances the ultimate tensile strength

JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2007
Ana Karina B. Bedran-Russo
Abstract The stabilization of dentin collagen with biocompatible crosslinking agents may be of clinical importance to improve dentin bond strength. The present study aimed to evaluate the effect of three collagen crosslinking agents on the ultimate tensile strength (UTS) of undemineralized and demineralized dentin. Ten freshly extracted sound molars were sectioned into 0.5 × 0.5 mm2 thick beams. The beams were either demineralized or kept undemineralized. Then, specimens were subdivided into four groups according to treatments,PBS solution (control), 5% glutaraldehyde (GD), 0.5% proanthocyanidin PBS solution (PA), and 0.625% genipin PBS solution (GE). Specimens were kept in their respective solutions for either 4 or 40 h. To assess UTS, specimens were subjected to tensile forces at a crosshead speed of 1 mm/min. Statistical analysis was performed using two-way ANOVA and Fisher's PLSD test (p < 0.05). Statistically significant increases in UTS were observed for demineralized dentin after PA and GE dentin treatment, when compared with those of the control group. Dentin treated with GD showed no statistically significant differences in UTS when compared with that the control. Undemineralized dentin revealed no significant differences as compared to that of the control, regardless of the collagen crosslinkers. The application of two naturally occurring crosslinkers, i.e., PA and GE, to dentin collagen significantly improves UTS, indicating its potential value in restorative dentistry. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007 [source]

Calcium channel blockers inhibit galvanotaxis in human keratinocytes

JOURNAL OF CELLULAR PHYSIOLOGY, Issue 1 2002
Donna R. Trollinger
Directed migration of keratinocytes is essential for wound healing. The migration of human keratinocytes in vitro is strongly influenced by the presence of a physiological electric field and these cells migrate towards the negative pole of such a field (galvanotaxis). We have previously shown that the depletion of extracellular calcium blocks the directional migration of cultured human keratinocytes in an electric field (Fang et al., 1998; J Invest Dermatol 111:751,756). Here we further investigate the role of calcium influx on the directionality and migration speed of keratinocytes during electric field exposure with the use of Ca2+ channel blockers. A constant, physiological electric field strength of 100 mV/mm was imposed on the cultured cells for 1 h. To determine the role of calcium influx during galvanotaxis we tested the effects of the voltage-dependent cation channel blockers, verapamil and amiloride, as well as the inorganic Ca2+ channel blockers, Ni2+ and Gd3+ and the Ca2+ substitute, Sr2+, on the speed and directionality of keratinocyte migration during galvanotaxis. Neither amiloride (10 ,M) nor verapamil (10 ,M) had any effect on the galvanotaxis response. Therefore, calcium influx through amiloride-sensitive channels is not required for galvanotaxis, and membrane depolarization via K+ channel activity is also not required. In contrast, Sr2+ (5 mM), Ni2+ (1,5 mM), and Gd3+ (100 ,M) all significantly inhibit the directional migratory response to some degree. While Sr2+ strongly inhibits directed migration, the cells exhibit nearly normal migration speeds. These findings suggest that calcium influx through Ca2+ channels is required for directed migration of keratinocytes during galvanotaxis and that directional migration and migration speed are probably controlled by separate mechanisms. J. Cell. Physiol. 193: 1,9, 2002. © 2002 Wiley-Liss, Inc. [source]

Effect of renal and non-renal ischemia/reperfusion on cell-mediated immunity in organs and plasma

APMIS, Issue 2 2010
ANNE C. BRŲCHNER
Brųchner AC, Dagnęs-Hansen F, Toft P. Effect of renal and non-renal ischemia/reperfusion on cell-mediated immunity in organs and plasma. APMIS 2010; 118: 101,7. Acute renal failure (ARF) is a common morbidity factor among patients in the intensive care unit, reaching an incidence from 3% to 30% depending on the definition of ARF and the population. Although the majority of the patients with ARF are treated with continuous renal replacement therapy, the mortality rate still remains above 50%. The causes of death are primarily extra-renal and include infection, shock, septicemia, and respiratory failure. We wanted to evaluate the cell-mediated inflammatory response of renal ischemia,reperfusion (I/R) and non-renal I/R, in blood and in distant organs. In our study, 80 mice were divided into four groups. The following surgeries were performed on the groups compared: bilateral renal I/R by clamping, unilateral renal ischemia, anesthesia only, and unilateral hind leg I/R. Half of the animals were killed after 2 h and the other half after 24 h. To assess the inflammatory response, we measured myeloperoxidase (MPO) in the organs, and CD 11b and major histocompatibility complex (MHC) II-positive cells in the blood. Non-renal I/R elicited the most elevated levels of MPO in extra-renal tissue such as the lungs. There was a trend toward higher MPO levels in the kidney following renal I/R. All kinds of I/R induced an upregulation of the adhesion molecule CD 11b and a downregulation of MHC II. Renal and non-renal I/R induced neutrophil infiltration in distant organs. Renal I/R does not induce a larger cell-mediated inflammatory response in blood and organs than non-renal I/R. [source]

Pharmacokinetic modelling of blood,brain barrier transport of escitalopram in rats

BIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 7 2007
Christoffer Bundgaard
Abstract This study examined the pharmacokinetics and distribution of escitalopram in the brain extracellular fluid in rats by the concurrent use of intracerebral microdialysis and serial blood sampling. Following three constant intravenous infusions, drug concentrations in the hippocampus and plasma were monitored for 6 h. To estimate the integrated pharmacokinetics and intercompartmental transport parameters, including blood,brain barrier (BBB) transport over the entire dose range, unbound brain and plasma escitalopram concentration data from all doses were simultaneously analysed using compartmental modelling. The pharmacokinetic analysis revealed that systemic clearance decreased as a function of dose, which was incorporated in the integrated model. Escitalopram was rapidly and extensively transported across the BBB and distributed into the brain extracellular fluid. The modelling resulted in an estimated influx clearance into the brain of 535 µl/min/g brain, resulting in an unbound brain-to-plasma AUC ratio of 0.8 independent of escitalopram dose. The model may be applied for preclinical evaluations or predictions of escitalopram concentration-time courses in plasma as well as at the target site in the CNS for various dosing scenarios. In addition, this modelling approach may also be valuable for studying BBB transport characteristics for other psychotropic agents. Copyright © 2007 John Wiley & Sons, Ltd. [source]