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Stem Cells and Development Apr 2017High post-transplantation cell mortality is the main limitation of various approaches that are aimed at improving regeneration of injured neural tissue by an injection... (Review)
Review
High post-transplantation cell mortality is the main limitation of various approaches that are aimed at improving regeneration of injured neural tissue by an injection of neural stem cells (NSCs) and mesenchymal stromal cells (MStroCs) in and/or around the lesion. Therefore, it is of paramount importance to identify efficient ways to increase cell transplant viability. We have previously proposed the "evolutionary stem cell paradigm," which explains the association between stem cell anaerobic/microaerophilic metabolic set-up and stem cell self-renewal and inhibition of differentiation. Applying these principles, we have identified the main critical point in the collection and preparation of these cells for experimental therapy: exposure of the cells to atmospheric O, that is, to oxygen concentrations that are several times higher than the physiologically relevant ones. In this way, the primitive anaerobic cells become either inactivated or adapted, through commitment and differentiation, to highly aerobic conditions (20%-21% O in atmospheric air). This inadvertently compromises the cells' survival once they are transplanted into normal tissue, especially in the hypoxic/anoxic/ischemic environment, which is typical of central nervous system (CNS) lesions. In addition to the findings suggesting that stem cells can shift to glycolysis and can proliferate in anoxia, recent studies also propose that stem cells may be able to proliferate in completely anaerobic or ischemic conditions by relying on anaerobic mitochondrial respiration. In this systematic review, we propose strategies to enhance the survival of NSCs and MStroCs that are implanted in hypoxic/ischemic neural tissue by harnessing their anaerobic nature and maintaining as well as enhancing their anaerobic properties via appropriate ex vivo conditioning.
Topics: Animals; Brain Ischemia; Cell Hypoxia; Cell Proliferation; Glycolysis; Neural Stem Cells; Stem Cell Transplantation
PubMed: 28103744
DOI: 10.1089/scd.2016.0268 -
Revista Espanola de Quimioterapia :... Apr 2023The objective of this study was to perform a systematic review of the characteristics, causative microorganisms and outcome of brain abscesses caused by anaerobic...
The objective of this study was to perform a systematic review of the characteristics, causative microorganisms and outcome of brain abscesses caused by anaerobic bacteria over the past 25 years. We reviewed studies on brain abscesses which included infection due to anaerobic microorganisms published between 1998 and 2022. We excluded reports with polymicrobial infections (more than 2 anaerobic bacteria isolated) and those that do not provide enough information to make comparisons, the reports with only one case of brain abscess due to anaerobes, as well as those focused on an only anaerobic bacterium. Also, we have excluded the cases in pediatric population. We searched the scientific literature through the Cochrane Library, EMBASE and PubMed/MEDLINE databases for studies of this condition. We finally included 28 studies with 6,167 patients, of which 715 (11.5%) were cases caused by anaerobic bacteria. There was a male predominance (70%) and mean age of 40.3 years. Most infections were monomicrobial (59.4%). The most common anaerobic microorganisms isolated were Bacteroides spp (43.4%) and Gram-positive anaerobic cocci (35.1%). Cases of brain abscesses caused by anaerobic bacteria were most frequent in Asia and Europe. The source of infection most frequent was otogenic in 84.6% followed by a neurosurgery procedure infection in 23% of patients. The main symptom observed was headache in 95.6% of patients followed by fever (69.5%). Surgical treatment was performed in 48 % of patients and the percentage of patients in whom antibiotic treatment was applied range 88.8% to 100%. The main limitation of this review is the non-inclusion of studies published before of 1998 in which MALDI-TOF MS system had not been introduced in the majority of laboratories for routine identification. The patient rate with isolation of anaerobic bacteria in brain abscesses is low, but these data could be underestimated mainly due to the fastidious nature of these microorganisms and the difficulties in the identification of some anaerobes.
Topics: Humans; Male; Child; Adult; Female; Anaerobiosis; Base Composition; Phylogeny; RNA, Ribosomal, 16S; Sequence Analysis, DNA; Brain Abscess; Bacteria, Anaerobic; Gram-Positive Cocci
PubMed: 36733997
DOI: 10.37201/req/114.2022 -
The Science of the Total Environment Feb 2021Anaerobic digestion (AD) is one of the most energy-efficient waste treatment technologies for biodegradable wastes. Owing to the increasing trend of metallic...
Anaerobic digestion (AD) is one of the most energy-efficient waste treatment technologies for biodegradable wastes. Owing to the increasing trend of metallic nanoparticle applications in industry, they are ubiquitous to the waste streams, which may lead to remarkable impacts on the performance of the AD process. This review addresses the knowledge gaps and summarises the findings from the academic articles published from 2010 to 2019 focusing on the influences on both AD processes of biochemical hydrogen-generation and methane-production from selected metallic nano-materials. Both qualitative and quantitative analyses were conducted with selected indicators to evaluate the metallic nanoparticles' influences on the AD process. The selected metallic nanoparticles were grouped in the view of their chemical formulations aiming to point out the possible mechanisms behind their effects on AD processes. In summary, most metallic nanoparticles with trace-element-base (e.g. iron, cobalt, nickel) have positive effects on both AD hydrogen-generation and methane-production processes in terms of gas production, effluent quality, as well as process optimisation. Within an optimum concentration, they serve as key nutrients providers, aid key enzymes and co-enzymes synthesis, and thus stimulate anaerobic microorganism activities. As for the nano-additives without trace-element base, their positive influences are relied on providing active sites for the microorganism, as well as absorbing inhibitory factors. Moreover, comparisons of these nano-additives' impacts on the two gas-production phases were conducted, while methane-production phases are found to be more sensitive to additions of these nanoparticles then hydrogen-production phase. Research perspectives and research gaps in this area are discussed.
Topics: Anaerobiosis; Biofuels; Bioreactors; Metal Nanoparticles; Methane; Nickel; Trace Elements
PubMed: 33257063
DOI: 10.1016/j.scitotenv.2020.143747 -
Journal of Environmental Management Apr 2024Digestate processing is a strategy to improve the management of digestate from biogas plants. Solid-liquid separation is usually the primary step and can be followed by... (Review)
Review
Digestate processing is a strategy to improve the management of digestate from biogas plants. Solid-liquid separation is usually the primary step and can be followed by advanced treatments of the fractions. The knowledge about the performance of the separators and the quality of the fractions is scattered because of many available techniques and large variability in digestate characteristics. We performed a systematic review and found 175 observations of full-scale solid-liquid separation of digestate. We identified 4 separator groups, 4 digestate classes based on substrate, and distinguished whether chemical conditioners were used. We confirmed the hypothesis that the dominant substrate can affect the efficiency of the digestate separation. Furthermore, the results showed that centrifuges separated significantly more dry matter and total P than screw presses. Use of chemical conditioners in combination with a centrifuge lowered the dry matter concentration in the liquid fraction by 30%. Screw presses consumed 4.5 times less energy than centrifuges and delivered 3.3 tonne ammonium N in the liquid fraction and 0.3 tonne total P in the solid fraction using 1 MWh. The results can provide data for systems analyses of biogas solutions and can support practitioners when choosing among full-scale separator techniques depending on the digestate type. In a broader perspective, this work contributes to the continuous improvement of biogas plants operations and to their role as nutrients recovery sites.
Topics: Anaerobiosis; Biofuels
PubMed: 38508011
DOI: 10.1016/j.jenvman.2024.120585 -
Journal of Environmental Management Dec 2023Anaerobic digestion (AD) as a waste management strategy for the organic fraction of municipal waste (OFMSW) has received attention in developed countries for several...
Anaerobic digestion (AD) as a waste management strategy for the organic fraction of municipal waste (OFMSW) has received attention in developed countries for several decades, leading to the development of large-scale plants. In contrast, AD of OFMSW has only recently drawn attention in developing countries. This systematic review was carried out to investigate the implementation of AD to treat the OFMSW in developing countries, focusing on assessing pilot and full-scale AD plants reported in the last ten years. Studies that met the selection criteria were analyzed and data regarding operating parameters, feedstock characteristics, and biogas, digestate, and energy production were extracted. As outlined in this systematic review, AD plants located in developing countries are mostly one-stage mesophilic systems that treat OFMSW via mono-digestion, almost exclusively with the aim of producing electrical energy. Based on the analysis done throughout this systematic review, it was noted that there is a large difference in the maturity level of AD systems between developing and developed countries, mainly due to the economic capacity of developed countries to invest in sustainable waste management systems. However, the number of AD plants reported in scientific papers is significantly lower than the number of installed AD systems. Research articles regarding large-scale implementation of AD to treat OFMSW in developed countries were analyzed and compared with developing countries. This comparison identified practices used in plants in developed countries that could be utilized in the large-scale implementation and success of AD in developing countries. These practices include exploiting potential products with high market-values, forming partnerships with local industries to use industrial wastes as co-substrates, and exploring different biological and physical pretreatment technologies. Additionally, the analysis of capital and operational costs of AD plants showed that costs tend to be higher for developing countries due to their need to import of materials and equipment from developed countries. Technical, economical, and political challenges for the implementation of AD at a large-scale in developing countries are highlighted.
Topics: Solid Waste; Refuse Disposal; Anaerobiosis; Developing Countries; Bioreactors; Biofuels; Methane
PubMed: 37751665
DOI: 10.1016/j.jenvman.2023.118993