Biological Optimization of Cortical Bone Allografts: A Study on the Effects of Mesenchymal Stem Cells and Partial Demineralization and Laser Perforation

Background: Despite promising results have shown by osteogenic cell-based demineralized bone matrix composites, they need to be optimized for grafts that act as structural frameworks in load-bearing defects. The purpose of this experiment is to determine the effect of bone marrow mesenchymal stem cells seeding on partially demineralized laser-perforated (DLP) structural allografts that have been implanted in critical femoral defects.Methods: Thirty-two Wistar rats were divided into four groups according to the type of structural bone allograft; the first: partially demineralized only (Donly), the second: partially demineralized stem cell seeded (DST), the third: partially DLP, and the fourth: partially demineralized laser-perforated and stem cell seeded (DLPST). Trans-cortical holes were achieved in four rows of three holes approximated cylindrical holes 0.5 mm in diameter, with centers 2.5 mm apart. P3 mesenchymal stromal cells (MSCs) were used for graft seeding. Histologic and histomorphometric analysis was performed at 12 weeks.Results: DLP grafts had the highest woven bone formation, where most parts of laser pores were completely healed by woven bone. DST and DLPST grafts surfaces had extra vessel-ingrowth-like porosities. Furthermore, in the DLPST grafts, a distinct bone formation at the interfaces was noted.Conclusions:This study indicated that surface changes induced by laser perforation, accelerated angiogenesis induction by MSCs, which resulted in endochondral bone formation at the interface. Despite non-optimal results, stem cells showed a tendency to improve osteochondrogenesis, and the process might have improved if they could have been supplemented with the proper stipulations

Development of PLGA-coated β-TCP scaffolds containing VEGF for bone tissue engineering

Bone tissue engineering is sought to apply strategies for bone defects healing without limitations and short-comings of using either bone autografts or allografts and xenografts. The aim of this study was to fabricate a thin layer poly(lactic-co-glycolic) acid (PLGA) coated beta-tricalcium phosphate (β-TCP) scaffold with sustained release of vascular endothelial growth factor (VEGF). PLGA coating increased compressive strength of the β-TCP scaffolds significantly. For in vitro evaluations, canine mesenchymal stem cells (cMSCs) and canine endothelial progenitor cells (cEPCs) were isolated and characterized. Cell proliferation and attachment were demonstrated and the rate of cells proliferation on the VEGF released scaffold was significantly more than compared to the scaffolds with no VEGF loading. A significant increase in expression of COL1 and RUNX2 was indicated in the scaffolds loaded with VEGF and MSCs compared to the other groups. Consequently, PLGA coated β-TCP scaffold with sustained and localized release of VEGF showed favourable results for bone regeneration in vitro, and this scaffold has the potential to use as a drug delivery device in the future

Energy-efficient dual-sink algorithms for sink mobility in event-driven wireless sensor networks

Improving energy-efficiency especially in routing mechanisms is one of the main goals in wireless sensor networks (WSNs). One of the issues of multi-hop routing is the phenomenon of fast energy depletion around the sink known as “sink neighborhood problem”. Recently, employing a dual-sink algorithm has become a popular trend to solve this problem. However, sink selection problem, optimizing the next destination for mobile sink, and finding the optimum next-hop in routing scheme are three other issues that need to be addressed properly in dual-sink approaches. This research firstly presents an energy-efficient dual-sink algorithm with role switching mechanism (EEDARS) to address the sink selection problem in scenarios with non simultaneous events. To this end, a role switching mechanism is applied to the dual-sink algorithm for sending the nearest sink to the event area, hence shorten the path. Secondly, an energy-efficient dual-sink algorithm with fuzzybased sink mobility (EDAFSM) is developed in which the mobile sink adaptively relocates to an optimum location among multiple events using fuzzy logic. Finally, a fuzzy logic scheme for routing optimization is proposed to improve further energyefficiency in EEDARS and EDAFSM. The aforementioned proposed algorithms are known as joint dual-sink and fuzzy-based geographic routing in single-event (JDFGR-S) and multi-event (JDFGR-M) WSNs. These algorithms are compared to seven recent and established techniques. Extensive simulation of these algorithms with different conditions through NS2 framework showed significant improvements on the network metrics especially lifetime, residual energy, number of nodes alive, delivery ratio and load distribution without negative effect on the end-to-end delay. The lifetime of JDFGR-S is 10% higher than EEDARS and the lifetime of JDFGR-M is 22% more than EDAFSM. The validation of simulation results show 96.53% and 98.98% reliability for lifetime and energy consumption metrics, respectively. As a conclusion, the proposed algorithms have improved the energy-efficiency in eventdriven based WSNs

Fundamental Lifetime Mechanisms in Routing Protocols for Wireless Sensor Networks: A Survey and Open Issues

sensor

Classification of energy-efficient routing protocols for wireless sensor networks

In recent years, research on Wireless Sensor Networks (WSNs) has become one of the main topics in electronic and computer fields. Since, the WSNs include many low cost and low power sensor nodes and battery replacement in harsh environments is usually impossible, an energy-efficient paradigm for all layers of protocol stack specially routing schemes is necessary to prolong the sensors' lifetime. In this paper, we first specify the sources of energy consumption in a typical sensor node, and then we classify the energy-efficient routings into three main categories such as flat, hierarchical, and geographic mechanisms based on underlying network structure. However, protocols employing simultaneous schemes such as bio-inspired methods, quality of service, multi-path and querybased manners are also discussed. In this taxonomy, special attention has been devoted to the energy-aware QoS-based and bio-inspired routing algorithms which have not yet obtained much consideration in the literature. Moreover, each class covers a variety of the state-of-the-art routing and cross-layer protocols, which motivate potential ideas for future works. Finally, we compare these mechanisms and discuss open research issues

Eedars: an energy-efficient dual-sink algorithm with role switching mechanism for event-driven wireless sensor networks

Energy conservation is a vital issue in wireless sensor networks. Recently, employing mobile sinks for data gathering become a pervasive trend to deal with this problem. The sink can follow stochastic or pre-defined paths; however the controlled mobility pattern nowadays is taken more into consideration. In this method, the sink moves across the network autonomously and changes its position based on the energy factors. Although the sink mobility would reduce nodes’ energy consumption and enhance the network lifetime, the overhead caused by topological changes could waste unnecessary power through the sensor field. In this paper, we proposed EEDARS, an energy-efficient dual-sink algorithm with role switching mechanism which utilizes both static and mobile sinks. The static sink is engaged to avoid any periodic flooding for sink localization, while the mobile sink adaptively moves towards the event region for data collection. Furthermore, a role switching mechanism is applied to the protocol in order to send the nearest sink to the recent event area, hence shorten the path. This algorithm could be employed in event-driven and multi-hop scenarios. Analytical model and extensive simulation results for EEDARS demonstrate a significant improvement on the network metrics especially the lifetime, the load and the end-to-end delay

The Effects of the Preconception Endurance Exercise Training and Voluntary Exercise Activity during Pregnancy in C57BL/6 Mice on Lipid Profile of the Adult Offsprings

Abstract Background: The aim of this study was to determine the effect of preconception endurance exercise training with voluntary exercise activity during pregnancy in mother mice on lipid profile in adult offsprings. Materials and Methods: Twenty four C57BL/6 female mice were randomly divided into four subgroups: trained in preconception period and exercised during pregnancy (TE)(20.3±1.02g); trained in preconception periods but unexercised during pregnancy (TC)(21.58±0.4g); untrained in preconception periods but exercised during pregnancy (CE)(21.02±0.23g); untrained and unexercised (CC)(19.23±0.45g). Trained mice were subjected to a protocol of moderate endurance exercise training over a period of 4 weeks for 5 days before pregnancy. The fasting blood samples were collected from adult mice(8 weeks old) and serum levels of glucose and lipid profile were measured. Data were analyzed using two way ANOVA and Tukey’s post hoc test. Results: The Glucose test results in offspring showed that there was a significant interaction between group and sex and group main effect (p<0.001) Glucose levels of male offspring were significantly lower in TC and TE groups. Results on LDL also showed that the sex main effect was significant (p<0.001), and LDL levels of male born to TE and TC dams lower than in female offspring. Conclusion: Improving the mother's physical fitness by providing regular endurance training in the preconception period and maintaining it by exercise activty throughout pregnancy may have potential for eliciting positive changes in lipid profile of offspring, specially males

Geographic wormhole detection in wireless sensor networks.

Wireless sensor networks (WSNs) are ubiquitous and pervasive, and therefore; highly susceptible to a number of security attacks. Denial of Service (DoS) attack is considered the most dominant and a major threat to WSNs. Moreover, the wormhole attack represents one of the potential forms of the Denial of Service (DoS) attack. Besides, crafting the wormhole attack is comparatively simple; though, its detection is nontrivial. On the contrary, the extant wormhole defense methods need both specialized hardware and strong assumptions to defend against static and dynamic wormhole attack. The ensuing paper introduces a novel scheme to detect wormhole attacks in a geographic routing protocol (DWGRP). The main contribution of this paper is to detect malicious nodes and select the best and the most reliable neighbors based on pairwise key pre-distribution technique and the beacon packet. Moreover, this novel technique is not subject to any specific assumption, requirement, or specialized hardware, such as a precise synchronized clock. The proposed detection method is validated by comparisons with several related techniques in the literature, such as Received Signal Strength (RSS), Authentication of Nodes Scheme (ANS), Wormhole Detection uses Hound Packet (WHOP), and Wormhole Detection with Neighborhood Information (WDI) using the NS-2 simulator. The analysis of the simulations shows promising results with low False Detection Rate (FDR) in the geographic routing protocols

Effects of Maternal Isocaloric Diet Containing Different Amounts of Soy Oil and Extra Virgin Olive Oil on Weight, Serum Glucose, and Lipid Profile of Female Mice Offspring

Background: Health status of offspring is programmed by maternal diet throughout gestation and lactation. The present study investigates the lasting effects of maternal supplementation with different amounts of soy oil or extra virgin olive oil (EVOO) on weight and biochemical parameters during gestation and lactation of female mice offspring. Methods: Eight weeks old female C57BL/6 mice (n=40) were assigned through simple randomization into four isocaloric dietary groups (16% of calories as soy oil (LSO) or EVOO (LOO) and 45% of calories as soy oil (HSO) or EVOO (HOO)) during three weeks of gestation and lactation. After weaning (at 3 weeks), all offspring received a diet containing 16% of calories as soy oil and were sacrificed at 6 weeks. Two-way ANOVA was used to adjust for confounding variables and repeated measures test for weight gain trend. Statistical analyses were performed with the IBM SPSS package. Results: At birth and adolescence, the weight of offspring was significantly higher in the soy oil than the olive oil groups (P<0.001 and P<0.001, respectively). Adolescence weight was significantly higher in the offspring born to mothers fed with 16% oil than those with 45% oil (P=0.001). Serum glucose, triglyceride and total cholesterol were significantly higher in the LSO than LOO (P<0.001, P<0.001 and P<0.001), LSO than HSO (P<0.001, P=0.03 and P<0.001), and LOO than HOO (P<0.001, P<0.001 and P<0.001) dietary groups, respectively. Serum triglyceride and total cholesterol were significantly higher in the offspring of HSO than HOO fed mothers (P<0.001 and P<0.001, respectively). Conclusion: A maternal diet containing EVOO has better effects on birth weight, as well as weight and serum biochemical parameters in offspring at adolescence