Liner characterisation and leak detection using electrical resistivity techniques

The resistivity of soil ranges from 7-15 Ωm for Leachate #1 to 20-50 Ωm for Leachate #2. The resistivity decreases with an increase in the proximity to the leak point. Furthermore, the resistivity values obtained with water were nearly 10 times the values observed with landfill leachate as the leaching liquid. Based on the resistivity profiles of soil as observed at different time intervals, the method is found to be effective in determining leakages in the liner. The test results have also been presented for the leakage of Bayer liquor obtained from aluminium manufacturing company in Western Australia. The resistivity values were found to range from 1 to 3 Ωm. A similar trend in the resistivity values was found with distance/depth for Bayer liquor contamination as observed with other leachates. Therefore, the installation of this innovative detection system below the liners in the aluminium industry can enable the effective monitoring of the lining systems and in case of failures, to take timely action for hazard mitigation. Finally, based on the leak detection test results, empirical correlations and analytical modelling have been developed and presented for the relationship between resistivity, leakage duration and distance/depth. These can be used to predict the velocity of flow of leachate at any point within a liner base soil specimen. A numerical model for the seepage analysis of the leak detection test has been developed using the SEEP/W software. The flow velocity obtained from this model has then been used in conjunction with the new correlations to generate resistivity profiles for any specific soil type and leachate, in the leak detection test. Any other suitable seepage analysis software (e.g. GGU-SEEP, GGU-SS-FLOW2D, GGU-SSFLOW3D, etc.) can be used by practicing engineers to predict resistivity, and therefore, to design a suitable lining system for waste containment facilities. This research work is particularly useful in generating awareness about the state of landfilling and will help various environmental protection agencies in making informed decisions for the development of rules and regulations to govern landfills. It is demonstrated that this system can be used to effectively detect and locate the liner leaks by simulating the field condition. The newly developed innovative diagnostic technique can be useful in designing the monitoring systems for waste storage and handling facilities, subbase contamination detection, liner leak detection, development and placement of sensors, soil and corrosion studies and so on, in Australia as well as worldwide

Temporal studies into attachment, VE-cadherin perturbation, and paracellular migration of human umbilical mesenchymal stem cells across umbilical vein endothelial monolayers

Mesenchymal stem cells from Wharton’s jelly of human umbilical cords (WJ-MSC) are a valuable alternate source of stem cells. Their role in situ and whether they can interact and cross intact endothelial monolayers requires elucidation. The aim of this study was to investigate the dynamic interactions between WJ-MSC and human umbilical vein endothelial cells (HUVEC), including attachment, transit times, extravasation pathway, and the effects of WJ-MSC on junctional vascular endothelial (VE)-cadherin. HUVEC were grown to near confluence in endothelial media and to full confluence in mixed media before the addition of PKH26-labelled WJ-MSC. Time lapse fluorescence microscopy showed stem cells undergoing membrane blebbing followed by amoeboid movement on HUVEC monolayers before rounding up and changing shape toward the spindleshaped morphology during/after transmigration to subendothelial positions. Cells demonstrated a time lag of 60 min before paracellular extravasation, confirmed by confocal microscopy. Forty-six percent of attached cells crossed in the first 2 h. By 16 h, a majority of cells had transmigrated with > 96% of cells crossing by 22 h. There were concomitant changes in endothelial junctional VE-cadherin with statistically significant increases in discontinuous staining at 2 h, return to control values at 16 h, even as from 22 h onward HUVEC displayed increased percentage of junctions with continuous staining and upregulation of protein. Our data suggests that WJ-MSC crosses the endothelial barrier through the paracellular pathway and can influence junctional organization of HUVEC with discreet perturbation of VE-cadherin preceding transmigration followed by upregulation once the adluminal side is reached. The latter may reflect a perivascular support function of WJ-MSC in the umbilical cord

Mutational Profiles Reveal an Aberrant TGF-β-CEA Regulated Pathway in Colon Adenomas.

Mutational processes and signatures that drive early tumorigenesis are centrally important for early cancer prevention. Yet, to date, biomarkers and risk factors for polyps (adenomas) that inordinately and rapidly develop into colon cancer remain poorly defined. Here, we describe surprisingly high mutational profiles through whole-genome sequence (WGS) analysis in 2 of 4 pairs of benign colorectal adenoma tissue samples. Unsupervised hierarchical clustered transcriptomic analysis of a further 7 pairs of adenomas reveals distinct mutational signatures regardless of adenoma size. Transitional single nucleotide substitutions of C:G\u3eT:A predominate in the adenoma mutational spectrum. Strikingly, we observe mutations in the TGF-β pathway and CEA-associated genes in 4 out of 11 adenomas, overlapping with the Wnt pathway. Immunohistochemical labeling reveals a nearly 5-fold increase in CEA levels in 23% of adenoma samples with a concomitant loss of TGF-β signaling. We also define a functional role by which the CEA B3 domain interacts with TGFBR1, potentially inactivating the tumor suppressor function of TGF-β signaling. Our study uncovers diverse mutational processes underlying the transition from early adenoma to cancer. This has broad implications for biomarker-driven targeting of CEA/TGF-β in high-risk adenomas and may lead to early detection of aggressive adenoma to CRC progression

Enhancing all-in-one bioreactors by combining interstitial perfusion, electrical stimulation, on-line monitoring and testing within a single chamber for cardiac constructs

Tissue engineering strategies have been extensively exploited to generate functional cardiac patches. To maintain cardiac functionality in vitro, bioreactors have been designed to provide perfusion and electrical stimulation, alone or combined. However, due to several design limitations the integration of optical systems to assess cardiac maturation level is still missing within these platforms. Here we present a bioreactor culture chamber that provides 3D cardiac constructs with a bidirectional interstitial perfusion and biomimetic electrical stimulation, allowing direct cellular optical monitoring and contractility test. The chamber design was optimized through finite element models to house an innovative scaffold anchoring system to hold and to release it for the evaluation of tissue maturation and functionality by contractility tests. Neonatal rat cardiac fibroblasts subjected to a combined perfusion and electrical stimulation showed positive cell viability over time. Neonatal rat cardiomyocytes were successfully monitored for the entire culture period to assess their functionality. The combination of perfusion and electrical stimulation enhanced patch maturation, as evidenced by the higher contractility, the enhanced beating properties and the increased level of cardiac protein expression. This new multifunctional bioreactor provides a relevant biomimetic environment allowing for independently culturing, real-time monitoring and testing up to 18 separated patches

Isolation, characterization and osteogenic differentiation of adipose-derived stem cells : from small to large size animal models

One of the most important issues in orthopaedic surgery is the loss of bone resulting from trauma, infections, tumours or congenital deficiency. In view of the hypothetical future application of mesenchymal stem cells isolated from human adipose tissue in regenerative medicine, we have analysed and characterized adipose-derived stem cells (ASCs) isolated from adipose tissue of rat, rabbit and pig. We have compared their in vitro osteogenic differentiation abilities for exploitation in the repair of critical osteochondral defects in autologous pre-clinical models. The number of pluripotent cells per millilitre of adipose tissue is variable and the yield of rabbit ASCs is lower than that in rat and pig. However, all ASCs populations show both a stable doubling time during culture and a marked clonogenic ability. After exposure to osteogenic stimuli, ASCs from rat, rabbit and pig exhibit a significant increase in the expression of osteogenic markers such as alkaline phosphatase, extracellular calcium deposition, osteocalcin and osteonectin. However, differences have been observed depending on the animal species and/or differentiation period. Rabbit and porcine ASCs have been differentiated on granules of clinical grade hydroxyapatite (HA) towards osteoblast-like cells. These cells grow and adhere to the scaffold, with no inhibitory effect of HA during osteo-differentiation. Such in vitro studies are necessary in order to select suitable pre-clinical models to validate the use of autologous ASCs, alone or in association with proper biomaterials, for the repair of critical bone defects

Optogenetic stimulation of the brainstem dorsal motor nucleus ameliorates acute pancreatitis

IntroductionInflammation is an inherently self-amplifying process, resulting in progressive tissue damage when unresolved. A brake on this positive feedback system is provided by the nervous system which has evolved to detect inflammatory signals and respond by activating anti-inflammatory processes, including the cholinergic anti-inflammatory pathway mediated by the vagus nerve. Acute pancreatitis, a common and serious condition without effective therapy, develops when acinar cell injury activates intrapancreatic inflammation. Prior study has shown that electrical stimulation of the carotid sheath, which contains the vagus nerve, boosts the endogenous anti-inflammatory response and ameliorates acute pancreatitis, but it remains unknown whether these anti-inflammatory signals originate in the brain.MethodsHere, we used optogenetics to selectively activate efferent vagus nerve fibers originating in the brainstem dorsal motor nucleus of the vagus (DMN) and evaluated the effects on caerulein-induced pancreatitis.ResultsStimulation of the cholinergic neurons in the DMN significantly attenuates the severity of pancreatitis as indicated by reduced serum amylase, pancreatic cytokines, tissue damage, and edema. Either vagotomy or silencing cholinergic nicotinic receptor signaling by pre-administration of the antagonist mecamylamine abolishes the beneficial effects.DiscussionThese results provide the first evidence that efferent vagus cholinergic neurons residing in the brainstem DMN can inhibit pancreatic inflammation and implicate the cholinergic anti-inflammatory pathway as a potential therapeutic target for acute pancreatitis

Characterization of articular chondrocytes isolated from 211 osteoarthritic patients

We analyzed specific features of chondrocytes as cellular yield, cell doubling rates and the dependence between these parameters and patient-related data in a set of 211 osteoarthritic (OA) patients undergoing total joint replacement. For each patient the data available were joint type, age and gender. Knee samples chosen randomly among all biopsies were graded according to ICRS score. Patients\u2019 age ranged between 30 and 90 years with a mean age of 66 \ub1 9.7 years. Patients were divided into age classes and statistically significant differences in proliferation rate at passage 1 were found between chondrocytes derived from young and old donors, with the last ones characterized by a lower proliferation rate. A similar trend was observed for proliferation rate at passage 2. For all the samples, cellular yields ranged between 0.1 and 5.5 million cells/g of tissue. No significant correlation was observed between the level of cartilage degeneration (ICRS score) and cellular yield and proliferation rates. However, in samples with a high degree of cartilage degeneration (ICRS score 4) the cellular yield was lower compared to the other three groups (ICRS scores 1\u20133). In this study we performed a systematic characterization of basic parameters of chondrocytes originating from a wide group of OA patients. Considering the use of autologous chondrocytes in chondral treatments, the characterization of cell basic features may represent an important step to determine the quality of the cell source which is a major determinant in the outcome of cell-based therapies

Anti-L-NGFR and -CD34 Monoclonal Antibodies Identify Multipotent Mesenchymal Stem Cells in Human Adipose Tissue

Stem cells hold great promise in tissue engineering for repairing tissues damaged by disease or injury. Mesenchymal stem cells (MSCs) are multipotent cells able to proliferate and differentiate into multiple mesodermal tissues such as bone, cartilage, muscle, tendon, and fat. We have previously reported that the low-affinity nerve growth factor receptor (L-NGFR or CD271) defines a subset of cells with high proliferative, clonogenic, and multipotential differentiation ability in adult bone marrow (BM). It has been recently shown that adipose tissue is an alternative source of adult multipotent stem cells and human Adipose-derived Stem Cells, selected by plastic adherence (PA hASCs), have been extensively characterized for their functional potentials in vitro. In this study, immunoselected L-NGFR+ and CD34+ subpopulations have been analyzed and compared with the PA hASCs. Phenotypic profile of freshly purified subpopulations showed an enrichment in the expression of some stem cell markers; indeed, a great percentage of L-NGFR+ cells co-expressed CD34 and CD117 antigens, whereas the endothelial-committed progenitor markers KDR and P1H12 were mainly expressed on CD34+ cells. Differently from PA hASCs, the immunoseparated fractions showed high increments in cell proliferation, and the fibroblast colony-forming activity (CFU-F) was maintained throughout the time of culture. Furthermore, the immunoselected populations showed a greater differentiative potential toward adipocytes, osteoblasts, and chondrocyte-like cells, compared to PA hASCs. Our data suggest that both CD34+ and L-NGFR+ hASCs can be considered alternative candidates for tissue engineering and regenerative medicine applications

Human adipose-derived stem cells isolated from young and elderly women : their differentiation potential and scaffold interaction during in vitro osteoblastic differentiation

Background aims Several authors have demonstrated that adipose tissue contains multipotent cells capable of differentiation into several lineages, including bone, cartilage and fat. Methods This study compared human adipose-derived stem cells (hASC) isolated from 26 female donors, under 35 and over 45 years old, showing differences in their cell numbers and proliferation, and evaluated their in vitro adipocytic and osteoblastic differentiation potential. Results The cellular yield of hASC from older donors was significantly greater than that from younger donors, whereas their clonogenic potential appeared slightly reduced. There were no significant discrepancies between hASC isolated from young and elderly women regarding their in vitro adipocytic differentiation, whereas the osteoblastic potential was significantly reduced by aging. We also assessed the influence of hydroxyapatite (HAP) and silicon carbide (SiC-PECVD) on hASC. Even when cultured on scaffolds, hASC from younger donors had better differentiation into osteoblast-like cells than hASC from older donors; their differentiation ability was up-regulated by the presence of HAP, whereas SiC-PECVD produced no significant effect on hASC osteoblastic differentiation. Conclusions The large numbers of hASC resident in adipose tissue and their differentiation features suggest that they could be used for a successful bone regeneration process in vivo. We have shown that age does not seem to affect cell viability and in vitro adipocytic differentiation significantly, whereas it does affects osteoblastic differentiation, in the absence and presence of two-dimensional and three-dimensional scaffolds