Relaxin stimulates leukocyte adhesion and migration through a relaxin receptor LGR7-dependent mechanism

Leukocytes are critical effectors of inflammation and tumor biology. Chemokine-like factors produced by such inflammatory sites are key mediators of tumor growth that activate leukocytic recruitment and tumor infiltration and suppress immune surveillance. Here we report that the endocrine peptide hormone, relaxin, is a regulator of leukocyte biology with properties important in recruitment to sites of inflammation. This study uses the human monocytic cell line THP-1 and normal human peripheral blood mononuclear cells to define a novel role for relaxin in regulation of leukocyte adhesion and migration. Our studies indicate that relaxin promotes adenylate cyclase activation, substrate adhesion, and migratory capacity of mononuclear leukocytes through a relaxin receptor LGR7-dependent mechanism. Relaxin-stimulated cAMP accumulation was observed to occur primarily in non-adherent cells. Relaxin stimulation results in increased substrate adhesion and increased migratory activity of leukocytes. In addition, relaxin-stimulated substrate adhesion resulted in enhanced chemotaxis to monocyte chemoattractant protein-1. These responses in THP-1 and peripheral blood mononuclear cells are relaxin dose-dependent and proportional to cAMP accumulation. We further demonstrate that LGR7 is critical for mediating these biological responses by use of RNA interference lentiviral short hairpin constructs. In summary, we provide evidence that relaxin is a novel leukocyte stimulatory agent with properties affecting adhesion and chemomigration

Mineralization capacity of Runx2/Cbfa1-genetically engineered fibroblasts is scaffold dependent

Development of tissue-engineered constructs for skeletal regeneration of large critical-sized defects requires the identification of a sustained mineralizing cell source and careful optimization of scaffold architecture and surface properties. We have recently reported that Runx2-genetically engineered primary dermal fibroblasts express a mineralizing phenotype in monolayer culture, highlighting their potential as an autologous osteoblastic cell source which can be easily obtained in large quantities. The objective of the present study was to evaluate the osteogenic potential of Runx2-expressing fibroblasts when cultured in vitro on three commercially available scaffolds with divergent properties: fused deposition-modeled polycaprolactone (PCL), gas-foamed polylactide-co-glycolide (PLGA), and fibrous collagen disks. We demonstrate that the mineralization capacity of Runx2-engineered fibroblasts is scaffold dependent, with collagen foams exhibiting ten-fold higher mineral volume compared to PCL and PLGA matrices. Constructs were differentially colonized by genetically modified fibroblasts, but scaffold-directed changes in DNA content did not correlate with trends in mineral deposition. Sustained expression of Runx2 upregulated osteoblastic gene expression relative to unmodified control cells, and the magnitude of this expression was modulated by scaffold properties. Histological analyses revealed that matrix mineralization co-localized with cellular distribution, which was confined to the periphery of fibrous collagen and PLGA sponges and around the circumference of PCL microfilaments. Finally, FTIR spectroscopy verified that mineral deposits within all Runx2-engineered scaffolds displayed the chemical signature characteristic of carbonate-containing, poorly crystalline hydroxyapatite. These results highlight the important effect of scaffold properties on the capacity of Runx2-expressing primary dermal fibroblasts to differentiate into a mineralizing osteoblastic phenotype for bone tissue engineering applications.

Time-dependent analysis of length of stay and mortality due urinary tract infections in ten developing countries : INICC findings

Catheter associated urinary tract infections (CAUTI) are a worldwide problem that may lead to increased patient morbidity, cost and mortality.1e3 The literature is divided on whether there are real effects from CAUTI on length of stay or mortality. Platt4 found the costs and mortality risks to be largeyetGraves et al found the opposite.5 A reviewof the published estimates of the extra length of stay showed results between zero and 30 days.6 The differences in estimates may have been caused by the different epidemiological methods applied. Accurately estimating the effects of CAUTI is difficult because it is a time-dependent exposure. This means that standard statistical techniques, such asmatched case-control studies, tend to overestimate the increased hospital stay and mortality risk due to infection. The aim of the study was to estimate excess length of stay andmortality in an intensive care unit (ICU) due to a CAUTI, using a statistical model that accounts for the timing of infection. Data collected from ICU units in lower and middle income countries were used for this analysis.7,8 There has been little research for these settings, hence the need for this paper.

Alexithymia in alcohol dependent patients is partially mediated by alcohol expectancy

Background: Up to fifty percent of alcohol dependent individuals have alexithymia, a personality trait characterised by difficulties identifying and describing feelings, a lack of imagination and an externalised cognitive style. Although studies have examined alexithymia in relation to alcohol dependence, no research exists on mechanisms underlying this relationship. The present study examined the mediational effect of alcohol expectancies on alexithymia and alcohol dependence.----- ----- Methods: 230 outpatients completed the Toronto Alexithymia Scale (TAS-20), the Drinking Expectancy Questionnaire (DEQ) and the Alcohol Use Disorder Identification Test (AUDIT). Results: Regression analysis showed that alexithymia and alcohol dependence was, in two of three cases, partially mediated through alcohol expectancy.----- ----- Conclusions: Alcohol expectancies of assertion and affective change show promise as mediators of alcohol dependence in individuals with alexithymia.

The effect of high concentrations of calcium hydroxide in neutralised synthetic supernatant liquor : implications for alumina refinery residues

The presence of calcium hydroxide (Ca(OH)2) in Bayer residue slurry inhibits the effectiveness of the seawater neutralisation process to reduce the pH and aluminium concentration in the residue. An increase in the slurry pH (reversion), after seawater neutralisation, is caused by the dissolution of calcium hydroxide and hydrocalumite (solid components found in bauxite refinery residue). Reversion was not observed when the final solution pH was greater than 10.5, due to hydrocalumite being in a state of equilibrium at high pH. Hydrocalumite has been found to form during the neutralisation process when high concentrations of calcium hydroxide are present in the residue liquor. The dissolution of hydrocalumite releases hydroxyl (OH-) and aluminium ions back into solution after the seawater neutralisation (SWN) process, which causes pH and aluminium reversion to occur. This investigation looks at the effect of Ca(OH)2 and subsequently hydrocalumite on the pH and aluminium concentration in bauxite refinery residue liquors after the SWN process.

Preparation of porous calcium phosphate ceramic scaffold in bone tissue engineering

Calcium Phosphate ceramic has been widely used in bone tissue engineering due to its excellent biocompatibility and biodegradability. However, low mechanical properties and biodegradability limit their potential applications. In this project, hydroxyapatite (HA) and calcium phosphate bioglass were used to produce porous tri-calcium phosphate (TCP) bio-ceramic scaffolds. It was found that porous TCP bioceramic could be obtained when 20wt percent bioglass addition and sintered in 1400 degrees celsius for 3 h. Significantly higher compressive strength (9.98 MPa) was achieved in the scaffolds as compared to those produced from tCP power (<3 MPa). The biocompatibility of the scaffold was also estimated.

Corrected mean-field models for spatially-dependent advection-diffusion-reaction phenomena

In the exclusion-process literature, mean-field models are often derived by assuming that the occupancy status of lattice sites is independent. Although this assumption is questionable, it is the foundation of many mean-field models. In this work we develop methods to relax the independence assumption for a range of discrete exclusion process-based mechanisms motivated by applications from cell biology. Previous investigations that focussed on relaxing the independence assumption have been limited to studying initially-uniform populations and ignored any spatial variations. By ignoring spatial variations these previous studies were greatly simplified due to translational invariance of the lattice. These previous corrected mean-field models could not be applied to many important problems in cell biology such as invasion waves of cells that are characterised by moving fronts. Here we propose generalised methods that relax the independence assumption for spatially inhomogeneous problems, leading to corrected mean-field descriptions of a range of exclusion process-based models that incorporate (i) unbiased motility, (ii) biased motility, and (iii) unbiased motility with agent birth and death processes. The corrected mean-field models derived here are applicable to spatially variable processes including invasion wave type problems. We show that there can be large deviations between simulation data and traditional mean-field models based on invoking the independence assumption. Furthermore, we show that the corrected mean-field models give an improved match to the simulation data in all cases considered.

Depth-dependent biomechanical and biochemical properties of fetal, newborn, and tissue-engineered articular cartilage

Adult articular cartilage has depth-dependent mechanical and biochemical properties which contribute to zone-specific functions. The compressive moduli of immature cartilage and tissue-engineered cartilage are known to be lower than those of adult cartilage. The objective of this study was to determine if such tissues exhibit depth-dependent compressive properties, and how these depth-varying properties were correlated with cell and matrix composition of the tissue. The compressive moduli of fetal and newborn bovine articular cartilage increased with depth (p < 0.05) by a factor of 4-5 from the top 0.1 mm (28 +/- 13 kPa, 141 +/- 10 kPa, respectively) to 1 mm deep into the tissue. Likewise, the glycosaminoglycan and collagen content increased with depth (both p < 0.001), and correlated with the modulus (both p < 0.01). In contrast, tissue-engineered cartilage formed by either layering or mixing cells from the superficial and middle zone of articular cartilage exhibited similarly soft regions at both construct surfaces, as exemplified by large equilibrium strains. The properties of immature cartilage may provide a template for developing tissue-engineered cartilage which aims to repair cartilage defects by recapitulating the natural development and growth processes. These results suggest that while depth-dependent properties may be important to engineer into cartilage constructs, issues other than cell heterogeneity must be addressed to generate such tissues. (c) 2005 Elsevier Ltd. All rights reserved.