A folyamatos szubkután glükózmonitorizálás szerepe az intenzív terápiában

A kritikus állapotú betegek stressz-hyperglykaemiájának értékelése az elmúlt évtizedben jelentősen megváltozott. A vércukor szoros kontrolljának mortalitást csökkentő hatását igazolta több jelentős vizsgálat, ugyanakkor az ezt célzó inzulinkezelés megnöveli a hypoglykaemia kockázatát, amely független mortalitási tényező lehet. A hypoglykaemia szempontjából kiemelt jelentőségű a gyermekpopuláció, a fejlődő idegrendszer miatt. Ezek alapján joggal merül fel a vércukorváltozások intenzív osztályos monitorizálásának igénye, különösen gyermek betegeknél. A hagyományos, vérmintából történő vércukor-meghatározások nem tesznek lehetővé kellően szoros monitorizálást. A cukorbetegek számára kifejlesztett, a szövet közti glükóz meghatározásán alapuló módszerek (continuous glucose monitoring) jó alternatívát jelenthetnek az intenzív osztályos monitorizálásra, amennyiben felmérjük a rendszer korlátait. A mérés a szövet közti folyadékban történik, így a szöveti perfúzió változásai zavarhatják a pontosságát. A folyamatos glükózmonitoring módszer intenzív osztályos alkalmazását jelenleg még nem javasolják, amíg a rendszer megbízhatóságáról nem áll rendelkezésre elegendő adat. Összefoglaló közleményükben a szerzők a magyar klinikai gyakorlatban elterjedt Medtronic folyamatos szubkután glükózmonitorizáló rendszert értékelik, részben saját eredményeik alapján. Orv. Hetil., 2013, 154, 1043–1048. | Critical care associated with stress hyperglycaemia has gained a new view in the last decade since the demonstration of the beneficial effects of strong glycaemic control on the mortality in intensive care units. Strong glycaemic control may, however, induce hypoglycaemia, resulting in increased mortality, too. Pediatric population has an increased risk of hypoglycaemia because of the developing central nervous system. In this view there is a strong need for close monitoring of glucose levels in intensive care units. The subcutaneous continuous glucose monitoring developed for diabetes care is an alternative for this purpose instead of regular blood glucose measurements. It is important to know the limitations of subcutaneous continuous glucose monitoring in intensive care. Decreased tissue perfusion may disturb the results of subcutaneous continuous glucose monitoring, because the measurement occurs in interstitial fluid. The routine use of subcutaneous continuous glucose monitoring in intensive care units is not recommended yet until sufficient data on the reliability of the system are available. The Medtronic subcutaneous continuous glucose monitoring system is evaluated in the review partly based on the authors own results. Orv. Hetil., 2013, 154, 1043–1048

Natural stimulus responsive scaffolds/cells for bone tissue engineering : influence of lysozyme upon scaffold degradation and osteogenic differentiation of cultured marrow stromal cells induced by CaP coatings

This work proposes the use of nonporous, smart, and stimulus responsive chitosan-based scaffolds for bone tissue engineering applications. The overall vision is to use biodegradable scaffolds based on chitosan and starch that present properties that will be regulated by bone regeneration, with the capability of gradual in situ pore formation. Biomimetic calcium phosphate (CaP) coatings were used as a strategy to incorporate lysozyme at the surface of chitosan-based materials with the main objective of controlling and tailoring their degradation profile as a function of immersion time. To confirm the concept, degradation tests with a lysozyme concentration similar to that incorporated into CaP chitosan-based scaffolds were used to study the degradation of the scaffolds and the formation of pores as a function of immersion time. Degradation studies with lysozyme (1.5 g=L) showed the formation of pores, indicating an increase of porosity (*5–55% up to 21 days) resulting in porous threedimensional structures with interconnected pores. Additional studies investigated the influence of a CaP biomimetic coating on osteogenic differentiation of rat marrow stromal cells (MSCs) and showed enhanced differentiation of rat MSCs seeded on the CaP-coated chitosan-based scaffolds with lysozyme incorporated. At all culture times, CaP-coated chitosan-based scaffolds with incorporated lysozyme demonstrated greater osteogenic differentiation of MSCs, bone matrix production, and mineralization as demonstrated by calcium deposition measurements, compared with controls (uncoated scaffolds). The ability of these CaP-coated chitosan-based scaffolds with incorporated lysozyme to create an interconnected pore network in situ coupled with the demonstrated positive effect of these scaffolds upon osteogenic differentiation of MSCs and mineralized matrix production illustrates the strong potential of these scaffolds for application in bone tissue engineering strategies.The authors would like to acknowledge Dr. Serena Danti. This work was supported by the European NoE EX-PERTISSUES (NMP3-CT-2004-500283), the European STREP HIPPOCRATES (NMP3-CT-2003-505758), and the Portuguese Foundation for Science and Technology (FCT) through POCTI and/or FEDER programs. This work was also supported by a grant from the National Institutes of Health (NIH; R01 DE15164) (A. G. M.) and a Bioengineering Research Partnership with the Baylor College of Medicine through the National Institute of Biomedical Imaging and Bioengineering (NIH Grant 5 R01 EB005173-02). F. K. K. is supported by a training fellowship from the Keck Center Nanobiology Training Program of the Gulf Coast Consortia (NIH Grant 5 T90 DK070121-03)

Selective laser sintering of hydroxyapatite reinforced polyethylene composites for bioactive implants and tissue scaffold development

Selective laser sintering (SLS) has been investigated for the production of bioactive implants and tissue scaffolds using composites of high-density polyethylene (HDPE) reinforced with hydroxyapatite (HA) with the aim of achieving the rapid manufacturing of customized implants. Single-layer and multilayer block specimens made of HA-HDPE composites with 30 and 40 vol % HA were sintered successfully using a CO2 laser sintering system. Laser power and scanning speed had a significant effect on the sintering behaviour. The degree of particle fusion and porosity were influenced by the laser processing parameters, hence control can be attained by varying these parameters. Moreover, the SLS processing allowed exposure of HA particles on the surface of the composites and thereby should provide bioactive products. Pores existed in the SLS-fabricated composite parts and at certain processing parameters a significant fraction of the pores were within the optimal sizes for tissue regeneration. The results indicate that the SLS technique has the potential not only to fabricate HA-HDPE composite products but also to produce appropriate features for their application as bioactive implants and tissue scaffolds

Opportunities and limitations for functional agrobiodiversity in the European context

To counteract the negative effects of intensive agriculture there is increasing interest in approaches that reconcile agricultural production with the conservation and sustainable use of biodiversity and associated ecosystem services. Integration of functional agrobiodiversity (FAB) in agricultural systems holds promise to meet these challenging objectives, but requires the generation, transfer and implementation of tailor-made knowledge, and policy development. Currently various initiatives are undertaken across Europe to develop and assess the potential of biodiversity-based management practices by farmers, industry, researchers and governmental and non-governmental organizations. In this paper we show that the Convention on Biological Diversity and planned reforms in EU policy offer scope to further implement FAB concepts via legislation for biodiversity conservation, pesticide use, water quality, environmental protection and conservation of genetic resources. At the same time we observe that there are still impediments to the adoption of FAB approaches, including (i) translation of general knowledge to tailored, ready-to-use management practices, (ii) limited information on the effectiveness of FAB measures in terms of crop yield and quality, profitability, and reduction of agrochemical inputs, (iii) lack of appropriate financial accounting systems that allow fair accounting of the private investments and public benefits, and (iv) the implementation of FAB measures at the right spatial scales, which requires coordination among the various actors in a region. Current and new legislation may provide incentives to address these limitations and contribute to the further development and integration of FAB concepts in agricultural systems in Europe

Fabrication and characterization of multiscale electrospun scaffolds for cartilage regeneration

Recently, scaffolds for tissue regeneration purposes have been observed to utilize nanoscale features in an effort to reap the cellular benefits of scaffold features resembling extracellular matrix (ECM) components. However, one complication surrounding electrospun nanofibers is limited cellular infiltration. One method to ameliorate this negative effect is by incorporating nanofibers into microfibrous scaffolds. This study shows that it is feasible to fabricate electrospun scaffolds containing two differently scaled fibers interspersed evenly throughout the entire construct as well as scaffolds containing fibers composed of two discrete materials, specifically fibrin and poly(?-caprolactone). In order to accomplish this, multiscale fibrous scaffolds of different compositions were generated using a dual extrusion electrospinning setup with a rotating mandrel. These scaffolds were then characterized for fiber diameter, porosity and pore size and seeded with human mesenchymal stem cells to assess the influence of scaffold architecture and composition on cellular responses as determined by cellularity, histology and glycosaminoglycan (GAG) content. Analysis revealed that nanofibers within a microfiber mesh function to maintain scaffold cellularity under serum-free conditions as well as aid the deposition of GAGs. This supports the hypothesis that scaffolds with constituents more closely resembling native ECM components may be beneficial for cartilage regeneration

"Smart'' and stimulus responsive chitosan-based scaffolds/cells for bone tissue engineering: Influence of lysozyme upon scaffold degradation and osteogenic differentiation of cultured marrow stromal cells induced by cap coatings

[Excerpt] The present study reports the use of non-porous, ‘‘smart’’ and stimulus responsive chitosan-based scaffolds with the capability of gradual in situ pore formation for bone tissue engineering applications. Biomimetic calcium phosphate (CaP) coatings were used as a strategy to incorporate lysozyme at the surface of chitosan based materials the main objective of controlling their degradation profile as a function of immersion time. In order to confirm the concept, degradation tests with concentration similar to those incorporated into CaP chitosan-based scaffolds were used to study the degradation of the scaffolds and the formation of pores as function of immersion time. Degradation studies with lysozyme (1.5 g/L) showed the formation of pores, indicating an increase of porosity (~5% - 55% up to 21 days) resulting in porous 3-D structures with interconnected pores. […]info:eu-repo/semantics/publishedVersio

Imaging of poly(α-hydroxy-ester) scaffolds with X-ray phase-contrast microcomputed tomography

Porous scaffolds based on poly(α-hydroxy-esters) are under investigation in many tissue engineering applications. A biological response to these materials is driven, in part, by their three-dimensional (3D) structure. The ability to evaluate quantitatively the material structure in tissue-engineering applications is important for the continued development of these polymer-based approaches. X-ray imaging techniques based on phase contrast (PC) have shown a tremendous promise for a number of biomedical applications owing to their ability to provide a contrast based on alternative X-ray properties (refraction and scatter) in addition to X-ray absorption. In this research, poly(α-hydroxy-ester) scaffolds were synthesized and imaged by X-ray PC microcomputed tomography. The 3D images depicting the X-ray attenuation and phase-shifting properties were reconstructed from the measurement data. The scaffold structure could be imaged by X-ray PC in both cell culture conditions and within the tissue. The 3D images allowed for quantification of scaffold properties and automatic segmentation of scaffolds from the surrounding hard and soft tissues. These results provide evidence of the significant potential of techniques based on X-ray PC for imaging polymer scaffolds

Tensile Fracture of Welded Polymer Interfaces: Miscibility, Entanglements and Crazing

Large-scale molecular simulations are performed to investigate tensile failure of polymer interfaces as a function of welding time $t$. Changes in the tensile stress, mode of failure and interfacial fracture energy $G_I$ are correlated to changes in the interfacial entanglements as determined from Primitive Path Analysis. Bulk polymers fail through craze formation, followed by craze breakdown through chain scission. At small $t$ welded interfaces are not strong enough to support craze formation and fail at small strains through chain pullout at the interface. Once chains have formed an average of about one entanglement across the interface, a stable craze is formed throughout the sample. The failure stress of the craze rises with welding time and the mode of craze breakdown changes from chain pullout to chain scission as the interface approaches bulk strength. The interfacial fracture energy $G_I$ is calculated by coupling the simulation results to a continuum fracture mechanics model. As in experiment, $G_I$ increases as $t^{1/2}$ before saturating at the average bulk fracture energy $G_b$. As in previous simulations of shear strength, saturation coincides with the recovery of the bulk entanglement density. Before saturation, $G_I$ is proportional to the areal density of interfacial entanglements. Immiscibiltiy limits interdiffusion and thus suppresses entanglements at the interface. Even small degrees of immisciblity reduce interfacial entanglements enough that failure occurs by chain pullout and $G_I \ll G_b$

Detection, Mapping, and Quantification of Single Walled Carbon Nanotubes in Histological Specimens with Photoacoustic Microscopy

Contains fulltext : 110845.pdf (publisher's version ) (Open Access)AIMS: In the present study, the efficacy of multi-scale photoacoustic microscopy (PAM) was investigated to detect, map, and quantify trace amounts [nanograms (ng) to micrograms (microg)] of SWCNTs in a variety of histological tissue specimens consisting of cancer and benign tissue biopsies (histological specimens from implanted tissue engineering scaffolds). MATERIALS AND METHODS: Optical-resolution (OR) and acoustic-resolution (AR)--Photoacoustic microscopy (PAM) was employed to detect, map and quantify the SWCNTs in a variety of tissue histological specimens and compared with other optical techniques (bright-field optical microscopy, Raman microscopy, near infrared (NIR) fluorescence microscopy). RESULTS: Both optical-resolution and acoustic-resolution PAM, allow the detection and quantification of SWCNTs in histological specimens with scalable spatial resolution and depth penetration. The noise-equivalent detection sensitivity to SWCNTs in the specimens was calculated to be as low as approximately 7 pg. Image processing analysis further allowed the mapping, distribution, and quantification of the SWCNTs in the histological sections. CONCLUSIONS: The results demonstrate the potential of PAM as a promising imaging technique to detect, map, and quantify SWCNTs in histological specimens, and could complement the capabilities of current optical and electron microscopy techniques in the analysis of histological specimens containing SWCNTs