57 research outputs found
Bone substitutes in the Netherlands - A systematic literature review
Autologous bone grafting is currently considered as the gold standard to restore bone defects. However, clinical benefit is not guar
Properties of commonly used calcium phosphate cements in trauma and orthopaedic surgery
Introduction
Half of the population sustains at least one fracture during their
lifetime, and the majority of these fractures heal successfully.
Successful fracture healing requires the following five elements; (i)
osteogenic cells (e.g., osteoblasts), (ii) osteoinductive stimuli (e.g.,
bone morphogenetic proteins); (iii) an osteoconductive matrix;
(iv) adequate blood and nutrient supply, and (v) sufficient
mechanical support. One or more elements can be compromised
due to the existence of a bone defect. Bone defects are
treated with bone grafts in order to avoid insufficient fracture
healing. Insufficient fracture healing is encountered in 5–10% of the
fractures, resulting in delayed union, malunion, or non-union
The FABRIC Project
The FABRIC project aims at the integration of middleware standards used in home networks to provide high quality streaming over a heterogeneous network without introducing new standards
A Framework for Time-Controlled and Portable WSN Applications
Abstract. Body sensor network applications require a large amount of data to be communicated over radio frequency. The radio transceiver is typically the largest source of power dissipation; improvements on energy consumption can thus be achieved by enabling on-node processing to reduce the number of packets to be transmitted. On-node processing is facilitated by a timely control over process execution to sequence operations on data; yet, the latter must be enabled while keeping highlevel software abstracted from both underlying software and hardware intricacies to accommodate portability to the wide range of hardware and software platforms. We investigated the challenges of implementing software services for on-node processing and devised constructs and system abstractions that integrate applications, drivers, time synchronization and MAC functionality into a system software which presents limited dependency between components and enables timely control of processes. We support our claims with a performance evaluation of the software tools implemented within the FreeRTOS micro-kernel
Selective laser melting-produced porous titanium scaffolds regenerate bone in critical size cortical bone defects
Porous titanium scaffolds have good mechanical properties that make them an interesting bone substitute material for large bone defects. These scaffolds can be produced with selective laser melting, which has the advantage of tailoring the structure's architecture. Reducing the strut size reduces the stiffness of the structure and may have a positive effect on bone formation. Two scaffolds with struts of 120-μm (titanium-120) or 230-μm (titanium-230) were studied in a load-bearing critical femoral bone defect in rats. The defect was stabilized with an internal plate and treated with titanium-120, titanium-230, or left empty. In vivo micro-CT scans at 4, 8, and 12 weeks showed more bone in the defects treated with scaffolds. Finally, 18.4 ± 7.1 mm3(titanium-120, p = 0.015) and 18.7 ± 8.0 mm3(titanium-230, p = 0.012) of bone was formed in those defects, significantly more than in the empty defects (5.8 ± 5.1 mm3). Bending tests on the excised femurs after 12 weeks showed that the fusion strength reached 62% (titanium-120) and 45% (titanium-230) of the intact contralateral femurs, but there was no significant difference between the two scaffolds. This study showed that in addition to adequate mechanical support, porous titanium scaffolds facilitate bone formation, which results in high mechanical integrity of the treated large bone defects. Copyrigh
Packet Skipping and Network Coding for Delay-Sensitive Network Communication
We provide an analytical study of the impact of packet skipping and
opportunistic network coding on the timely communication of messages through a
single network element. In a first step, we consider a single-server queueing
system with Poisson arrivals, exponential service times, and a single buffer
position. Packets arriving at a network node have a fixed deadline before which
they should reach the destination. To preserve server capacity, we introduce a
thresholding policy, based on remaining time until deadline expiration, to
decide whether to serve a packet or skip its service. The obtained goodput
improvement of the system is derived, as well as the operating conditions under
which thresholding can enhance performance. Subsequently, we focus our analysis
on a system that supports network coding instead of thresholding. We
characterize the impact of network coding at a router node on the delivery of
packets associated with deadlines. We model the router node as a queueing
system where packets arrive from two independent Poisson flows and undergo
opportunistic coding operations. We obtain an exact expression for the goodput
of the system and study the achievable gain. Finally, we provide an analytical
model that considers both network coding and packet skipping, capturing their
joint performance. A comparative analysis between the aforementioned approaches
is provided
MRNA expression profiles of colorectal liver metastases as a novel biomarker for early recurrence after partial hepatectomy
Background: Identification of specific risk groups for recurrence after surgery for isolated colorectal liver metastases (CRLM) remains challenging due to the heterogeneity of the disease. Classical clinicopathologic parameters have limited prognostic value. The aim of this study was to identify a gene expression signature measured in CRLM discriminating early from late recurrence after partial hepatectomy. Methods: CRLM from two patient groups were collected: I) with recurrent disease ≤12 months after surgery (N = 33), and II) without recurrences and disease free for ≥36 months (N = 30). The patients were clinically homogeneous; all had a low clinical risk score (0-2) and did not receive (neo-) adjuvant chemotherapy. Total RNA was hybridised to Illumina arrays, and processed for analysis. A leave-one-out cross validation (LOOCV) analysis was performed to identify a prognostic gene expression signature. Results: LOOCV yielded an 11-gene profile with prognostic value in relation to recurrent disease ≤12 months after partial hepatectomy. This signature had a sensitivity of 81.8%, with a specificity of 66.7% for predicting recurrences (≤12 months) versus no recurrences for at least 36 months after surgery (X2 P < 0.0001). Conclusion: The current study yielded an 11-gene signature at mRNA level in CRLM discriminating early from late or no relapse after partial hepatectomy
Salvage treatment for recurrences after first resection of colorectal liver metastases: the impact of histopathological growth patterns
The majority of patients recur after resection of colorectal liver metastases (CRLM). Patients with CRLM displaying a desmoplastic histopathological growth pattern (dHGP) have a better prognosis and lower probability of recurrence than patients
with non-dHGP CRLM. The current study evaluates the impact of HGP type on the pattern and treatment of recurrences after
first resection of CRLM. A retrospective cohort study was performed, including patients with known HGP type after complete
resection of CRLM. All patients were treated between 2000 and 2015. The HGP was determined on the CRLM resected at
first partial hepatectomy. The prognostic value of HGPs, in terms of survival outcome, in the current patient cohort were
previously published. In total 690 patients were included, of which 492 (71%) developed recurrent disease. CRLM displaying
dHGP were observed in 103 patients (21%). Amongst patients with dHGP CRLM diagnosed with recurrent disease, more
liver-limited recurrences were seen (43% vs. 31%, p=0.030), whereas patients with non-dHGP more often recurred at multiple locations (34% vs. 19%, p=0.005). Patients with dHGP CRLM were more likely to undergo curatively intended local
treatment for recurrent disease (adjusted odds ratio: 2.37; 95% confidence interval (CI) [1.46–3.84]; p<0.001) compared
to patients with non-dHGP. The present study demonstrates that liver-limited disease recurrence after complete resection o
Angiogenic desmoplastic histopathological growth pattern as a prognostic marker of good outcome in patients with colorectal liver metastases
Abstract
Background In patients with resectable colorectal liver metastases (CRLM), distinct histopathological growth patterns
(HGPs) develop at the interface between the tumour and surrounding tissue. The desmoplastic (d) HGP is characterised by
angiogenesis and a peripheral fibrotic rim, whereas non-angiogenic HGPs co-opt endogenous sinusoidal hepatic vasculature.
Evidence from previous studies has suggested that patients with dHGP in their CRLM have improved prognosis as compared
to patients with non-desmoplastic HGPs. However, these studies were relatively small and applied arbitrary cut-off values
for the determination of the predominant HGP. We have now investigated the
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