Quantification of the regional bioarchitecture in the human aorta.

Regional variance in human aortic bioarchitecture responsible for the elasticity of the vessel is poorly understood. The current study quantifies the elements responsible for aortic compliance, namely, elastin, collagen and smooth muscle cells, using histological and stereological techniques on human tissue with a focus on regional heterogeneity. Using donated cadaveric tissue, a series of samples were excised between the proximal ascending aorta and the distal abdominal aorta, for five cadavers, each of which underwent various staining procedures to enhance specific constituents of the wall. Using polarised light microscopy techniques, the orientation of collagen fibres was studied for each location and each tunical layer of the aorta. Significant transmural and longitudinal heterogeneity in collagen fibre orientations were uncovered throughout the vessel. It is shown that a von Mises mixture model is required accurately to fit the complex collagen fibre distributions that exist along the aorta. Additionally, collagen and smooth muscle cell density was observed to increase with increasing distance from the heart, whereas elastin density decreased. Evidence clearly demonstrates that the aorta is a highly heterogeneous vessel which cannot be simplistically represented by a single compliance value. The quantification and fitting of the regional aortic bioarchitectural data, although not without its limitations, including mean cohort age of 77.6 years, facilitates the development of next-generation finite element models that can potentially simulate the influence of regional aortic composition and microstructure on vessel biomechanics.

An actuatable soft reservoir modulates host foreign body response.

The performance of indwelling medical devices that depend on an interface with soft tissue is plagued by complex, unpredictable foreign body responses. Such devices-including breast implants, biosensors, and drug delivery devices-are often subject to a collection of biological host responses, including fibrosis, which can impair device functionality. This work describes a milliscale dynamic soft reservoir (DSR) that actively modulates the biomechanics of the biotic-abiotic interface by altering strain, fluid flow, and cellular activity in the peri-implant tissue. We performed cyclical actuation of the DSR in a preclinical rodent model. Evaluation of the resulting host response showed a significant reduction in fibrous capsule thickness (P = 0.0005) in the actuated DSR compared with non-actuated controls, whereas the collagen density and orientation were not changed. We also show a significant reduction in myofibroblasts (P = 0.0036) in the actuated group and propose that actuation-mediated strain reduces differentiation and proliferation of myofibroblasts and therefore extracellular matrix production. Computational models quantified the effect of actuation on the reservoir and surrounding fluid. By adding a porous membrane and a therapy reservoir to the DSR, we demonstrate that, with actuation, we could (i) increase transport of a therapy analog and (ii) enhance pharmacokinetics and time to functional effect of an inotropic agent. The dynamic reservoirs presented here may act as a versatile tool to further understand, and ultimately to ameliorate, the host response to implantable biomaterials.

Activated charcoal as a capture material for silver nanoparticles in environmental water samples.

Silver nanoparticles (AgNPs), due to their antibacterial activity, have been incorporated into numerous consumer products. Their environmental impact however, is currently unclear. Uncertainties surround the concentration, fate, and effects of AgNPs in aquatic environments. This study examined the suitability of activated charcoal as a capture material for AgNPs from water. Samples of 100 ppb AgNPs were initially generated and exposed to activated charcoal for 24 h to examine the ability of charcoal to capture AgNPs. The decrease in Ag concentration was measured using ICP-MS. Following initial investigations, the surface area of the charcoal was increased firstly with a pestle and mortar and secondly by milling the charcoal using a ball mill. The increased surface area of the milled charcoal increased the capture of the AgNPs from 11.9% to 63.6% for the 100 ppb samples. Further investigations were carried out examining the effect on the capture of AgNP concentration (with concentration ranging from 10 to 100 ppb), particle coating and the effect of exposure time to the activated charcoal. The capture of AgNP increased with decreasing concentration. A hydrochloric acid (HCl) leaching procedure was also developed which successfully removed the captured silver allowing the fraction captured by the charcoal to be quantified with an average of 94.8% recovery. The results show that milled activated charcoal, can successfully capture AgNPs from water samples, and that therefore, activated charcoal may prove to be a cost effective material for the remediation of waters impacted by AgNP or other nano-wastes.

Allogeneic Mesenchymal Stromal Cells (MSCs) are of Comparable Efficacy to Syngeneic MSCs for Therapeutic Revascularization in C57BKSdb/db Mice Despite the Induction of Alloantibody.

Intramuscular administration of mesenchymal stromal cells (MSCs) represents a therapeutic option for diabetic critical limb ischemia. Autologous or allogeneic approaches may be used but disease-induced cell dysfunction may limit therapeutic efficacy in the former. Our aim was to compare the efficacy of allogeneic and autologous MSC transplantation in a model of hindlimb ischemia in diabetes mellitus and to determine whether allogeneic transplantation would result in the activation of an immune response. MSCs were isolated from C57BL/6 (B6) and diabetic obese C57BKSdb/db mice. Phosphate-buffered saline (control group), and MSCs (1 × 106) from B6 (allogeneic group) or C57BKSdb/db (syngeneic group) were administered intramuscularly into the ischemic thigh of C57BKSdb/db mice following the induction of hindlimb ischemia. MSCs derived from both mouse strains secrete several angiogenic factors, suggesting that the potential therapeutic effect is due to paracrine signaling. Administration of allogeneic MSCs significantly improved blood perfusion as compared with the control group on week 2 and 3, post-operatively. In comparison with the control group, syngeneic MSCs significantly improved blood perfusion at week 2 only. There was no statistical difference in blood perfusion between allogeneic and syngeneic MSC groups at any stages. There was no statistical difference in ambulatory and necrosis score among the three groups. Amputation of toes was only observed in the control group (one out of seven animals). Alloantibody was detected in three out of the eight mice that received allogeneic MSCs but was not observed in the other groups. In summary, we demonstrated comparable efficacy after transplantation of autologous and allogeneic MSCs in a diabetic animal model despite generation of an immune response.

Employing mesenchymal stem cells to support tumor-targeted delivery of extracellular vesicle (EV)-encapsulated microRNA-379.

Adult Mesenchymal Stem Cells (MSCs) have a well-established tumor-homing capacity, highlighting potential as tumor-targeted delivery vehicles. MSCs secrete extracellular vesicle (EV)-encapsulated microRNAs, which play a role in intercellular communication. The aim of this study was to characterize a potential tumor suppressor microRNA, miR-379, and engineer MSCs to secrete EVs enriched with miR-379 for in vivo therapy of breast cancer. miR-379 expression was significantly reduced in lymph node metastases compared to primary tumor tissue from the same patients. A significant reduction in the rate of tumor formation and growth in vivo was observed in T47D breast cancer cells stably expressing miR-379. In more aggressive HER2-amplified HCC-1954 cells, HCC-379 and HCC-NTC tumor growth rate in vivo was similar, but increased tumor necrosis was observed in HCC-379 tumors. In response to elevated miR-379, COX-2 mRNA and protein was also significantly reduced in vitro and in vivo. MSCs were successfully engineered to secrete EVs enriched with miR-379, with the majority found to be of the appropriate size and morphology of exosomal EVs. Administration of MSC-379 or MSC-NTC cells, or EVs derived from either cell population, resulted in no adverse effects in vivo. While MSC-379 cells did not impact tumor growth, systemic administration of cell-free EVs enriched with miR-379 was demonstrated to have a therapeutic effect. The data presented support miR-379 as a potent tumor suppressor in breast cancer, mediated in part through regulation of COX-2. Exploiting the tumor-homing capacity of MSCs while engineering the cells to secrete EVs enriched with miR-379 holds exciting potential as an innovative therapy for metastatic breast cancer.

Corrigendum to: Hypoxia limits mouse follicle growth in vitro.

Ovarian follicle culture is useful for elucidation of factors involved in the regulation of follicular function. We examined the effects of gas phase oxygen concentration, an oil overlay, serum type and medium supplementation with FSH, insulin-transferrin-selenium (ITS) and I-ascorbic acid on cultured preantral mouse follicle growth in a spherical, non-attached follicle culture system. Follicle growth in 5% oxygen was significantly (P<0.01) inferior to growth in 20% oxygen in terms of follicle diameter. This was likely due to hypoxia, as evidenced by significantly (P<0.05) increased follicle secretion of vascular endothelial growth factor (VEGF), a marker of cell hypoxia. Follicular growth was not (P>0.05) affected by an oil overlay, ITS supplementation or serum type. Culture in medium with 5% mouse serum, 1 IU mL-1 FSH, 25 µgmL-1 l-ascorbic acid and 20% oxygen without an oil overlay supported the growth of follicles to a maximum diameter of 380 µm in 6 days. Compared with mature preovulatory mouse follicles in vivo that often have diameters >500 µm within the same time frame, in vitro-grown follicles clearly exhibit limited growth. Thus, adequate oxygenation is an essential factor in the process of optimising follicle growth.

Silver nanoparticles in the environment: Sources, detection and ecotoxicology.

The environmental impact of silver nanoparticles (AgNP) has become a topic of interest recently, this is due to the fact that AgNPs have been included in numerous consumer products including textiles, medical products, domestic appliances, food containers, cosmetics, paints and nano-functionalised plastics. The production, use and disposal of these AgNP containing products are potential routes for environmental exposure. These concerns have led to a number of studies investigating the release of particles from nano-functionalised products, the detection of the particles in the aquatic environment and the potential environmental toxicology of these AgNPs to aquatic organisms. The overall aim of this review is to examine methods for the capture and detection of AgNPs, potential toxicity and transmission routes in the aquatic environment.

Point of care optical diagnostic technologies for the detection of oral and oropharyngeal squamous cell carcinoma.

BACKGROUND: Despite significant advances in treatment modalities, the 5 year survival rate in oral and oropharyngeal squamous cell carcinoma (SCC) is less than 60%. Clinical examination, white light endoscopy followed by blind biopsies and histopathological analysis remains the gold standard for diagnosis and surveillance. These modalities continue to have a limited diagnostic accuracy of less than 55%. METHODS: Novel optical-based diagnostic methods are promising new technologies for improving both screening and detection of cancer. This review will discuss their role in oral and oropharyngeal cancer detection with particular emphasis on optical imaging in oral and oropharyngeal cancer diagnosis, including the use of surface enhanced Raman spectroscopy, optical coherence tomography, fluorescence diagnosis, confocal laser endomicroscopy, confocal reflectance microscopy and narrow band imaging. RESULTS: Aided by the use of differing wavelengths of light, these methods are capable of detecting physical and biochemical changes that precede and mirror malignant change within tissue. CONCLUSION: Our review of the currently utilized optical diagnostic modalities suggests the possibility of a cost effective, point of care diagnosis that could facilitate early detection, reduce healthcare costs and improve patient survival and quality of life.

Hypoxia limits mouse follicle growth in vitro.

Ovarian follicle culture is useful for elucidation of factors involved in the regulation of follicular function. We examined the effects of gas phase oxygen concentration, an oil overlay, serum type and medium supplementation with FSH, insulin-transferrin-selenium (ITS) and l-ascorbic acid on cultured preantral mouse follicle growth in a spherical, non-attached follicle culture system. Follicle growth in 5% oxygen was significantly (P < 0.01) inferior to growth in 20% oxygen in terms of follicle diameter. This was likely due to hypoxia, as evidenced by significantly (P < 0.05) increased follicle secretion of vascular endothelial growth factor (VEGF), a marker of cell hypoxia. Follicular growth was not (P > 0.05) affected by an oil overlay, ITS supplementation or serum type. Culture in medium with 5% mouse serum, 1 IU mL-1 FSH, 25 µg mL-1 l-ascorbic acid and 20% oxygen without an oil overlay supported the growth of follicles to a maximum diameter of 380 µm in 6 days. Compared with mature preovulatory mouse follicles in vivo that often have diameters >500 µm within the same time frame, in vitro-grown follicles clearly exhibit limited growth. Thus, adequate oxygenation is an essential factor in the process of optimising follicle growth.

A novel barbed suture tie-over dressing for skin grafts: a comparison with traditional techniques.

INTRODUCTION: Barbed suture devices have a widespread application in plastic surgery. The unidirectional nature of the barbs facilitates a strong grip on tissues and reduces the need to constantly tension the suture manually. We hypothesized that a barbed suture tie-over suture to secure skin grafts would be quicker to perform than traditional tie-overs and would also exert a greater downward pressure on the skin graft. METHODS: Thirty uniform areas of skin were excised from a cadaver. A pressure transducer was placed on the wound bed and covered with the excised skin along with a mineral oil-soaked wool dressing to act as a bolster. Three different sutures were used to secure the graft in place and the pressure was recorded. The tie-over techniques used were the classic silk tie-over, a running Vicryl Rapide™ tie-over and a running barbed tie-over. RESULTS: The barbed tie-over exerted the most downward pressure (82.8 ± 7.3 mmHg) compared to the silk (46 ± 4.85 mmHg) and the Vicryl Rapide™ (18.6 ± 2.4 mmHg). Furthermore, the barbed tie-over was the quickest to perform (1:45 ± 22 s) when compared to the Vicryl Rapide™ (02:57 ± 27 s) and the silk tie-overs (04:26 ± 39 s). CONCLUSION: Barbed sutures are a viable option for securing skin grafts. They are quick to perform and provide significantly improved downward pressure on the skin graft. We feel that this technique would be especially suited to the sole operator as it can be carried out without the need of an assistant.

The path of screw insertion for stabilization of the scapholunate joint: a cadaveric study.

The aim of this study was to determine the path of screw placement to avoid breaching the articular surface of both lunate and scaphoid bones at the radiocarpal and midcarpal joints. An Acutrak screw was inserted into the right scapholunate joint of ten cadavers starting immediately distal to the tip of the radial styloid and aiming for the tip of the ulnar styloid. The articular surfaces of the scaphoid and lunate bones in all ten cadavers were exposed and examined. A computed tomography (CT) scan of four wrists was performed. Eight of the ten cadavers had no perforation or destruction of the articular surfaces. Screw stabilization of the scapholunate joint can be performed without perforation or destruction of the lunate or scaphoid surfaces. We recommend that if this form of fixation is being used then the screw should be inserted commencing at the radial styloid tip and aiming for ulnar styloid tip, under radiological guidance.

Digital sculpting in surgery: a novel approach to depicting mesosigmoid mobilization.

BACKGROUND: The aim of the present study was to develop a unique anatomic replica of the mesocolon using digital graphical software in order to provide an educational template for mesosigmoidectomy. METHODS: The colon and mesocolon were fully mobilized from ileocecal to mesorectal levels in a cadaver. Both colon and mesocolon provided a template from which to generate a three dimensional replica in ZBrush. The model was deformed in ZBrush, to compare and contrast current and classic interpretations of mesosigmoidal topography. An animation was developed in which the replica was deformed to mimic operative mobilization. Contiguous shape changes were captured in two-and-a-half-dimensional (2.5D) screen snapshots. This was repeated for medial to lateral and lateral to medial mobilization of the mesosigmoid. RESULTS: Topographic differences between classic and current appraisals of mesocolic anatomy were evident in 2.5D format. Using the model generated, contiguous shape changes during mesosigmoidal mobilization (i.e., between the left mesocolon, mobile/apposed mesosigmoid, and mesorectum) were replicated in animation format. By extracting and compiling 2.5D screen grabs a pictorial chronology of mobilization was developed. CONCLUSIONS: Recent advances in mesocolic topography can be captured and rendered using advanced digital sculpting software with high-end graphics capabilities. This approach permits a depiction of contiguous changes in mesosigmoidal topography during mesosigmoidal mobilization. A compilation of images in either animation or screen grab format obviates the interpolation of shape changes required using standard educational approaches.

Commonly used disinfectants fail to eradicate Salmonella enterica biofilms from food contact surface materials.

Salmonellosis is the second most common cause of food-borne illness worldwide. Contamination of surfaces in food processing environments may result in biofilm formation with a risk of food contamination. Effective decontamination of biofilm-contaminated surfaces is challenging. Using the CDC biofilm reactor, the activities of sodium hypochlorite, sodium hydroxide, and benzalkonium chloride were examined against an early (48-h) and relatively mature (168-h) Salmonella biofilm. All 3 agents result in reduction in viable counts of Salmonella; however, only sodium hydroxide resulted in eradication of the early biofilm. None of the agents achieved eradication of mature biofilm, even at the 90-min contact time. Studies of activity of chemical disinfection against biofilm should include assessment of activity against mature biofilm. The difficulty of eradication of established Salmonella biofilm serves to emphasize the priority of preventing access of Salmonella to postcook areas of food production facilities.

Salmonella enterica biofilm formation and density in the Centers for Disease Control and Prevention's biofilm reactor model is related to serovar and substratum.

Foodborne pathogens can attach to, and survive on, food contact surfaces for long periods by forming a biofilm. Salmonella enterica is the second most common cause of foodborne illness in Ireland. The ability of S. enterica to form a biofilm could contribute to its persistence in food production areas, leading to cross-contamination of products and surfaces. Arising from a large foodborne outbreak of S. enterica serovar Agona associated with a food manufacturing environment, a hypothesis was formulated that the associated Salmonella Agona strain had an enhanced ability to form a biofilm relative to other S. enterica. To investigate this hypothesis, 12 strains of S. enterica, encompassing three S. enterica serovars, were assessed for the ability to form a biofilm on multiple food contact surfaces. All isolates formed a biofilm on the contact surfaces, and there was no consistent trend for the Salmonella Agona outbreak strain to produce a denser biofilm compared with other strains of Salmonella Agona or Salmonella Typhimurium. However, Salmonella Enteritidis biofilm was considerably less dense than Salmonella Typhimurium and Salmonella Agona biofilms. Biofilm density was greater on tile than on concrete, polycarbonate, stainless steel, or glass.

Predicting and avoiding subcellular compartmentalization artifacts arising from acetoxymethyl ester calcium imaging probes. The case of fluo-3 AM and a general account of the phenomenon including a problem avoidance chart.

Stimulated by difficulties experienced when using fluo-3 AM, we developed a general mechanistic model to aid understanding and practical application of calcium probes applied as acetoxymethyl (AM) esters. Several practical issues previously overlooked or under-emphasized are considered by this model. First, some AM ester probes are "super" lipophilic, e.g., calcium orange, fluo-3, fura red, and these are trapped in the plasma membrane. Entry of such compounds into cells requires the presence of serum albumin in the incubation medium or esterase in the plasma membrane or both. Second, visible cytosolic calcium signals require significant cytosolic esterase, which varies considerably among cell lines and within cell populations of a single cell line. Finally, compartmentalization artefacts are most likely when incompletely hydrolyzed esters are present in the cytosol. This can occur because of low cytosolic esterase concentration or activity, and especially when long incubation times or high extracellular probe concentrations are used. An additional factor favoring compartmentalization is the presence of the "salt" form of the probe in the cytosol in the absence of significant concentrations of calcium ions. We provide an algorithmic chart to aid assessment of possible compartmentalization, guides to relevant QSAR models, and notes on estimation of the structural parameters required when using these models.

Pretreatment of endothelial progenitor cells with osteopontin enhances cell therapy for peripheral vascular disease.

Tissue necrosis resulting from critical limb ischemia (CLI) leads to amputation in a significant number of patients. Autologous cell therapy using angiogenic cells such as endothelial progenitor cells (EPCs) holds promise as a treatment for CLI but a limitation of this treatment is that the underlying disease etiology that resulted in CLI may also contribute to dysfunction of the therapeutic EPCs. This study aimed to elucidate the mechanism of EPC dysfunction using diabetes mellitus as a model and to determine whether correction of this defect in dysfunctional EPCs ex vivo would improve the outcome after cell transplantation in the murine hind limb ischemia model. EPC dysfunction was confirmed in a homogenous population of patients with type 1 diabetes mellitus and a microarray study was preformed to identify dysregulated genes. Notably, the secreted proangiogenic protein osteopontin (OPN) was significantly downregulated in diabetic EPCs. Furthermore, OPN-deficient mice showed impaired recovery following hind limb ischemia, suggesting a critical role for OPN in postnatal neovascularization. EPCs isolated from OPN KO mice showed decreased ability to adhere to endothelial cells as well as impaired angiogenic potential. However, this dysfunction was reversed upon exposure to recombinant OPN, suggesting that OPN may act in an autocrine manner on EPCs. Indeed, exposure of OPN knockout (KO) EPCs to OPN was sufficient to induce the secretion of angiogenic proteins (IL-6, TGF-α, and FGF-α). We also demonstrated that vascular regeneration following hind limb ischemia in OPN KO mice was significantly improved upon injection of EPCs preexposed to OPN. We concluded that OPN acts in an autocrine manner on EPCs to induce the secretion of angiogenic proteins, thereby playing a critical role in EPC-mediated neovascularization. Modification of cells by exposure to OPN may improve the efficacy of autologous EPC transplantation via the enhanced secretion of angiogenic proteins.

An inverting circumferential suture for flexor tenorraphy.

Zone two flexor tendon repair remains challenging with significant outcome variation using recognised techniques. Tendon adhesion formation results in poor outcomes and rehabilitation regimes aim to limit this. Some repairs augment strength, but increasing bulk mitigates against movement. This novel epitendinous technique causes tendon inversion with potential gliding benefits and improved outcomes. 60 porcine tendons were randomised to a 2-stranded modified Kessler or a 4-stranded Adelaide repair, then sudivided into three different circumferential technique groups: locked running, Silfverskiold, or a new inverting repair. Tendon load to failure (LTF), 2 mm gap formation, bulking effect and method of failure were analysed during digital tensiometry. Four-stranded repairs demonstrated better LTF than 2-stranded techniques. The inverting epitendinous and Silfverskiold repairs showed higher LTF characteristics than the locked running suture, and better tissue holding capacity. The inverting repair has similar properties to commonly used suturing methods and the conformation creates a smooth inverted repair.

Hunter-Schreger Band patterns and their implications for clinical dentistry.

Hunter-Schreger Bands (HSBs) are an optical phenomenon visualised when a cut or fractured enamel surface is viewed under reflected light. These bands demonstrate the synchronous decussation of individual or groups of enamel prisms. While the role of HSB patterns has been investigated in comparative anatomical studies, until recently there has been little consideration of HSB patterns in human teeth. The aim of this paper is to consider the significance of HSB patterns in the human dentition and in relation to clinical dentistry. It is concluded that within the human dentition, HSB patterns have evolved to optimise resistance to attrition, abrasion and tooth fracture. It appears that certain aspects of HSB packing densities and distributions have beneficial roles in enamel bonding. Hunter-Schreger Band patterns seem to passively facilitate conditions such as abfraction and cracked tooth syndrome.

MCPH1/BRIT1 limits ionizing radiation-induced centrosome amplification.

Microcephalin (MCPH1/BRIT1) is a potential tumour suppressor that localizes to the centrosome, forms ionizing radiation-induced nuclear foci (IRIF) and is involved in the DNA damage checkpoints that ensure genome stability. Here, we report the impact of Mcph1 disruption in the hyper-recombinogenic DT40 cell line. Mcph1(-/-) cells were viable and proliferated at the same rate as wild-type controls. Mcph1-deficient cells had intact G2-to-M checkpoint responses after ionizing radiation (IR) treatment, but showed moderate radiosensitivity. Light and electron microscopy indicated normal centrosome structures in Mcph1 null cells, but IR induced massive amplification of centrosome numbers in the absence of Mcph1. Mcph1 null cells formed γ-H2AX and Rad51 IRIF, but resolved them more slowly than wild-type cells. Mcph1 deficiency caused sustained Chk1 phosphorylation after IR, dysregulating Cdk2 activity. These findings show that Mcph1 controls centrosome numbers after DNA damage, which may indicate a novel tumour suppressive mechanism for microcephalin.