biodegradability Dotaz Zobrazit nápovědu
Úvod a cíl: Standardním materiálem užívaným pro osteosyntézu obličejového skeletu je titan a jeho sloučeniny. Jednou z nevýhod konvenčního materiálu je nutnost jeho extrakce v indikovaných případech. Řešení situace nabízí degradovatelné materiály. V minulosti se pro tyto účely užívaly materiály na bázi polylaktidové nebo polyglykolidové kyseliny, které se klinicky prokázaly být nevyhovující. Moderním řešením je použití osteosyntetického materiálu z kovových degradovatelných slitin. Autoři prezentují původní práci – výzkum vstřebatelnosti kovových materiálů na bázi magnezia a zinku na biomodelech. Materiál a metodika: K výzkumu bylo použito celkem 12 zvířecích biomodelů – králíků, kterým byly implantovány do tibií šrouby ze tří typů kovů (dvě vstřebatelné slitiny – Zn-2Mg a WE43 – a titan jako standardní materiál). Zvířata byla ve čtyřtýdenních intervalech eutanazována, vzorky kostní tkáně s implantovaným materiálem byly skenovány v mikrofokus-CT a histologicky vyšetřeny. Byla posouzena rychlost degradace materiálů. Výsledky: Doba degradace materiálu je u WE43 za fyziologických podmínek krátká pro stabilizaci fraktury do doby její konsolidace. Materiál Zn-2Mg během 16 týdnů prokázal minimální schopnost degradace. Oba materiály prokázaly přiměřené biologické vlastnosti. Závěr: Degradovatelné materiály na bázi magnezia a zinku jsou z biologického hlediska vyhovující materiály. Z výsledků výzkumu ale vyplývá, že použití obou typů slitin nevyhovuje požadavkům na materiál, tj. zachování pevnosti po dobu 12–24 týdnů a současně vstřebání v racionálním časovém rámci.
Introduction and aim: The standard material used for osteosynthesis of the facial skeleton is the titan and its compounds. One of the disadvantages of the conventional material is the need for its extraction in indicated cases. Degradable material offer a solution to the situation. In the past, materials based on polylactic or polyglycolic acid were used for these purposes. It clinically proved to be unsatisfactory. The modern solution is the use of biodegradable metal alloys. The authors present original research on the degradation of metal materials based on magnesium and zinc on the biomodels. Materials and methods: A total of 12 animal models (rabbits) were used. Screws of 3 types of metals (Zn-2Mg and WE43 degradable alloys and the titanium as a standard material) were implanted in the rabbit’s tibias. The animals were euthanasied in 4-weeks intervals, samples of bone tissue with an implanted material have been scaned under mikrofocus CT and were histologically examined. The rate of degradation of the materials was examined. Results: Time period of degradation of the material WE43 under physiological conditions has been shown to be too short to stabilize the fracture. Material of Zn-2 mg during the 16 weeks showed a minimum ability to degradation. Both materials have demonstrated reasonable biological properties. Conclusion: Degradable materials based on magnesium and zinc are from the biological point of view matching materials. The results of this research indicates that the use of both types of alloys does not satisfy the materials requirments, i.e. retained strength for 12–24 weeks and degradation in reasonable time frame..
- MeSH
- adjuvancia anestetická MeSH
- analgetika MeSH
- anestetika lokální MeSH
- antibakteriální látky aplikace a dávkování terapeutické užití MeSH
- antiflogistika nesteroidní MeSH
- biologické modely MeSH
- diazepam aplikace a dávkování terapeutické užití MeSH
- hořčík terapeutické užití MeSH
- ketamin aplikace a dávkování terapeutické užití MeSH
- ketoprofen aplikace a dávkování terapeutické užití MeSH
- kovy terapeutické užití MeSH
- králíci MeSH
- modely u zvířat MeSH
- titan terapeutické užití MeSH
- trimekain aplikace a dávkování terapeutické užití MeSH
- vnitřní fixace fraktury metody MeSH
- vstřebatelné implantáty * dějiny využití MeSH
- zinek terapeutické užití MeSH
- zubní implantáty MeSH
- zubní slitiny terapeutické užití MeSH
- zvířata MeSH
- Check Tag
- králíci MeSH
- zvířata MeSH
Biodegradable polymer-based therapeutics have recently become essential drug delivery biomaterials for various bioactive compounds. Biodegradable and biocompatible polymer-based biomaterials fulfill the requirements of these therapeutics because they enable to obtain polymer biomaterials with optimized blood circulation, pharmacokinetics, biodegradability, and renal excretion. Herein, we describe an adaptable polymerization platform employed for the synthesis of long-circulating, stimulus-sensitive and biodegradable biomaterials, therapeutics, or theranostics. Four chain transfer agents (CTA) were designed and successfully synthesized for the reversible addition-fragmentation chain transfer polymerization, allowing the straightforward synthesis of hydrolytically biodegradable structures of block copolymers-based biomaterials. The controlled polymerization using the CTAs enables controlling the half-life of the hydrolytic degradation of polymer precursors in a wide range from 5 h to 21 days. Moreover, the antitumor drug pirarubicin (THP) was successfully conjugated to the polymer biomaterials via a pH-sensitive hydrazone bond for in vitro and in vivo experiments. Polymer conjugates demonstrated superior antitumor efficacy compared to basic linear polymer-based conjugates. Notably, the biodegradable systems, even though those with degradation in the order of hours were selected, increased the half-life of THP in the bloodstream almost two-fold. Indeed, the presented platform design enables the main chain-end specific attachment of targeting ligands or diagnostic molecules. The adaptable polymerization platform design allows tuning of the biodegradability rate, stimuli-sensitive drug bonding, and optimized pharmacokinetics to increase the therapy outcome and system targeting, thus allowing the preparation of targeted or theranostic polymer conjugates. STATEMENT OF SIGNIFICANCE: Biodegradable and biocompatible polymer-based biomaterials are recognized as potential future bioactive nanomedicines. To advance the development of such biomaterials, we developed polymerization platforms utilizing tailored chain transfer agents allowing the straightforward synthesis of hydrolytically degradable polymer biomaterials with tuned biodegradability from hours to several days. The platform allows for the synthesis of long-circulating, stimulus-sensitive and biodegradable biomaterial serving as drug carriers or theranostics. The therapeutic potential was validated by preparation of polymer biomaterials containing pirarubicin, anticancer drug, bound via pH sensitive bond and by showing prolonged blood circulation and increased antitumor activity while keeping the drug side effects low. This work paves the way for future development of biodegradable polymer biomaterials with advanced properties in drug delivery.
Brominated flame retardants (BFRs) have been routinely used as additives in a number of consumer products for several decades in order to reduce the risk of fire accidents. Concerns about the massive use of these substances have increased due to their possible toxicity, endocrine disrupting properties and occurrence in almost all the environmental compartments, including humans and wildlife organisms. Several conventional BFRs (e.g. polybrominated diphenylethers (PBDE)) have been included in the list of Persistent Organic Pollutants and their use has been restricted because of their established toxicity and environmental persistence. Over the past few years, these compounds have been replaced with "new" BFRs (NBFRs). Despite the fact that NBFRs are different chemical molecules than traditional BFRs, most of physical-chemical properties (e.g. aromatic moiety, halogen substitution, lipophilic character) are common to both groups; therefore, their fate in the environment is potentially similar to the banned BFRs. Therefore, this article has been compiled to summarize the published scientific data regarding the biodegradability of the most widely used NBFRs, a key factor in their potential persistency in the environment, and their ecotoxicological effects on humans and test organisms. The data reviewed here document that the mechanisms through NBFRs exibit their ecotoxicity and the processes leading to their biotransformation in the environment are still poorly understood. Thus emphasis is placed on the need for further research in these areas is therefore emphasized, in order to avoid the massive use of further potentially harmful and recalcitrant substances of anthropogenic origin.
- MeSH
- biodegradace MeSH
- bromované uhlovodíky metabolismus toxicita MeSH
- hodnocení rizik MeSH
- lidé MeSH
- monitorování životního prostředí MeSH
- retardanty hoření metabolismus toxicita MeSH
- vystavení vlivu životního prostředí * MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
Chlorhexidine (CHX) and octenidine (OCT), antimicrobial compounds used in oral care products (toothpastes and mouthwashes), were recently revealed to interfere with human sex hormone receptor pathways. Experiments employing model organisms-white-rot fungi Irpex lacteus and Pleurotus ostreatus-were carried out in order to investigate the biodegradability of these endocrine-disrupting compounds and the capability of the fungi and their extracellular enzyme apparatuses to biodegrade CHX and OCT. Up to 70% ± 6% of CHX was eliminated in comparison with a heat-killed control after 21 days of in vivo incubation. An additional in vitro experiment confirmed manganese-dependent peroxidase and laccase are partially responsible for the removal of CHX. Up to 48% ± 7% of OCT was removed in the same in vivo experiment, but the strong sorption of OCT on fungal biomass prevented a clear evaluation of the involvement of the fungi or extracellular enzymes. On the other hand, metabolites indicating the enzymatic transformation of both CHX and OCT were detected and their chemical structures were proposed by means of liquid chromatography-mass spectrometry. Complete biodegradation by the ligninolytic fungi was not achieved for any of the studied analytes, which emphasizes their recalcitrant character with low possibility to be removed from the environment.
- MeSH
- antiinfekční látky lokální metabolismus MeSH
- biodegradace * MeSH
- chlorhexidin chemie metabolismus MeSH
- houby metabolismus MeSH
- lidé MeSH
- metabolomika metody MeSH
- pyridiny chemie metabolismus MeSH
- stomatologická péče MeSH
- transformace genetická MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
The aim of our research was to assess the ecotoxicity and biodegradability of leachates originating from two parts of a municipal landfill before and after biological treatment in the existing treatment plant. Biotests represent important tools for adequate environmental characterization of landfill leachates and could be helpful in reliable assessment and monitoring of the treatment plant efficiency. For ecotoxicity testing of landfill leachate before and after biological treatment, different organisms were chosen: the bacteria Vibrio fischeri, a mixed culture of activated sludge, duckweed Lemna minor, white mustard Sinapis alba, brine shrimp Artemia salina, and water flea Daphnia magna. For assessment of biodegradability, the method for determination of oxygen demand in a closed respirometer was used. The investigated leachates were heavily polluted, and in some cases, effluent limits were exceeded even after treatment. Results indicated that toxicity tests and physico-chemical parameters determined before and after treatment equivalently assess the efficiency of the existing treatment plant. However, the investigated leachates showed higher toxicity to Daphnia magna and especially to Lemna minor in contrast to Vibrio fischeri and Artemia salina (neither was sensitive to any of the leachates). No leachates were readily biodegradable. Experiments confirmed that the battery of toxicity tests should be applied for more comprehensive assessment of landfill leachate treatment and for reliable assessment of the treated leachate's subsequent environmental impact. It was confirmed that treated leachate, in spite of its better physico-chemical characteristics, still represents a potential environmental risk and thus should not be released into the environment.
- MeSH
- biodegradace MeSH
- bioreaktory MeSH
- chemické látky znečišťující vodu chemie metabolismus toxicita MeSH
- měření biologické spotřeby kyslíku MeSH
- odpadní vody MeSH
- regenerace a remediace životního prostředí metody MeSH
- testy toxicity MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- MeSH
- biodegradace MeSH
- Evropská unie MeSH
- finanční podpora výzkumu jako téma MeSH
- látky znečišťující životní prostředí ekonomika normy MeSH
- povrchově aktivní látky ekonomika MeSH
- zákonodárství jako téma ekonomika normy využití MeSH
- Publikační typ
- srovnávací studie MeSH
- Geografické názvy
- Česká republika MeSH
