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BACKGROUND: Tubulointerstitial kidney disease associated microenvironmental dysregulation, like acidification, inflammation and fibrosis, affects tubule cells and fibroblasts. Micromilieu homeostasis influences intracellular signaling and intercellular crosstalk. Cell-cell communication in turn modulates the interstitial microenvironment. We assessed the impact of acidosis on inflammatory and fibrotic responses in proximal tubule cells and fibroblasts as a function of cellular crosstalk. Furthermore, cellular signaling pathways involved were identified. METHODS: HK-2 (human proximal tubule) and CCD-1092Sk (human fibroblasts), in mono and coculture, were exposed to acidic or control media for 3 or 48 h. Protein expression of inflammation markers (TNF, TGF-ß and COX-2), dedifferentiation markers (N-cadherin, vinculin, ß-catenin and vimentin), fibrosis markers (collagen III and fibronectin) and phospho- as well as total MAPK levels were determined by western blot. Secreted collagen III and fibronectin were measured by ELISA. The impact of MAPK activation was assessed by pharmacological intervention. In addition, necrosis, apoptosis and epithelial permeability were determined. RESULTS: Independent of culture conditions, acidosis caused a decrease of COX-2, vimentin and fibronectin expression in proximal tubule cells. Only in monoculture, ß-Catenin expression decreased and collagen III expression increased in tubule cells during acidosis. By contrast, in coculture collagen III protein expression of tubule cells was reduced. In fibroblasts acidosis led to an increase of TNF, COX-2, vimentin, vinculin, N-cadherin protein expression and a decrease of TGF-ß expression exclusively in coculture. In monoculture, expression of COX-2 and fibronectin was reduced. Collagen III expression of fibroblasts was reduced by acidosis independent of culture conditions. In coculture, acidosis enhanced phosphorylation of ERK1/2, JNK1/2 and p38 transiently in proximal tubule cells. In fibroblasts, acidosis enhanced phosphorylation of p38 in a sustained and very strong manner. ERK1/2 and JNK1/2 were not affected in fibroblasts. Inhibition of JNK1/2 and p38 under coculture conditions reduced acidosis-induced changes in fibroblasts significantly. CONCLUSIONS: Our data show that the crosstalk between proximal tubule cells and fibroblasts is crucial for acidosis-induced dedifferentiation of fibroblasts into an inflammatory phenotype. This dedifferentiation is at least in part mediated by p38 and JNK1/2. Thus, cell-cell communication is essential for the pathophysiological impact of tubulointerstitial acidosis.
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Acidose , Fibronectinas , Proteínas Quinases p38 Ativadas por Mitógeno , Humanos , Acidose/metabolismo , Caderinas/metabolismo , Cateninas/metabolismo , Colágeno/metabolismo , Ciclo-Oxigenase 2/metabolismo , Fibroblastos/metabolismo , Fibronectinas/metabolismo , Fibrose , Inflamação/metabolismo , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo , Vimentina/metabolismo , Vinculina/metabolismo , Proteína Quinase 14 Ativada por Mitógeno/metabolismoRESUMO
BACKGROUND: The use of a quadriceps tendon-patellar bone (QTPB) autograft provides an alternative procedure in primary reconstruction of the anterior cruciate ligament (ACL). Using the press-fit technique for femoral fixation and knotting over a bone bridge as well as additional spongiosa filling for tibial fixation can completely eliminate the need for fixation implants. The objective of this study was to evaluate the long-term clinical, functional and radiological results of this operating method. METHODS: Sixty-nine patients (27 female-42 male) were included in this study. Fifty-seven patients (83%) received a comprehensive follow-up review after an average period of 7.5 years (range: 7-8.7). All other patients were surveyed by telephone. Six patients (9%) suffered a re-rupture of the ACL graft caused by a new related trauma and were therefore excluded from the statistical analysis. RESULTS: Of all patients, 98% were satisfied with the operation. Normal or almost normal results were recorded in the subjective IKDC scores form by 88% of the patients. The Lysholm score demonstrated very good and good results in 83% of the patients. Only 1 patient reported minor complaints in the donor area. Seven (12%) patients developed Cyclops syndrome with limited knee extension. This complication was treated arthroscopically within the first year postoperatively. Their results on follow-up were not worse than the results of the patients without Cyclops syndrome. Regarding the 57 patients who received a comprehensive evaluation, the stability test with the KT-1000 Arthrometer yielded a difference of less than 3 mm in the contralateral comparison for 89% of the operated knees. The pivot-shift test was normal in 79% and almost normal in 21%. In the Single-leg Triple Hop Test, patients achieved an average of 98% of the hopping distance attained with the contralateral leg. The radiological examination revealed a slight deterioration in the Kellgren-Lawrence Score in 2 patients. CONCLUSION: The ACL reconstruction using the QTPB autograft performed with the press-fit technique leads to good results in comparison with published results of established procedures for primary ACL surgery using other autografts. Further investigations should involve comparative studies with the objective of providing evidence-based, individually adapted therapy for ACL rupture.
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Lesões do Ligamento Cruzado Anterior/cirurgia , Reconstrução do Ligamento Cruzado Anterior/métodos , Instabilidade Articular/epidemiologia , Patela/transplante , Ligamento Patelar/transplante , Adolescente , Adulto , Reconstrução do Ligamento Cruzado Anterior/efeitos adversos , Autoenxertos , Feminino , Seguimentos , Humanos , Instabilidade Articular/etiologia , Instabilidade Articular/fisiopatologia , Articulação do Joelho/fisiopatologia , Articulação do Joelho/cirurgia , Masculino , Amplitude de Movimento Articular , Estudos Retrospectivos , Transplante Autólogo/efeitos adversos , Transplante Autólogo/métodos , Resultado do Tratamento , Adulto JovemRESUMO
Despite a long history of research, the mode of action of the mycotoxin ochratoxin A (OTA) is still not clear. Based on our observation that OTA-exposed cells consume more glucose and produce more lactate than control cells, with this study, we want to suggest another possible mode of action of OTA, involving cellular metabolism and mitochondria. We exposed human proximal tubule cells (HK2 cells) to OTA and studied its influence on mitochondrial performance as well as on the expression of energy homeostasis-involved routing proteins (AMPK and TXNIP) and on glucose transporting and metabolizing proteins. OTA reduced the capacity of mitochondria to increase their oxygen consumption rate forcing the cells to switch to the ineffective anaerobic glycolysis which demands higher glucose availability. The higher glucose demand is met by augmented cellular glycogen degradation and increased glucose uptake capabilities by increasing glucose transporter expression. We conclude that OTA exposure leads to impaired mitochondria, which forces the cells to alter their metabolism in order to ensure energy supply. We suggest to consider a possible effect of OTA on metabolism and mitochondria and to have a closer look on OTA-induced changes in the metabolome as possible additional players in OTA toxicity.
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Micotoxinas , Ocratoxinas , Humanos , Ocratoxinas/toxicidade , Micotoxinas/toxicidade , Homeostase , Glucose/metabolismoRESUMO
Crosstalk of renal epithelial cells with interstitial fibroblasts plays an important role in kidney pathophysiology. A previous study showed that crosstalk between renal epithelial cells and renal fibroblasts protects against acidosis-induced damage. In order to gain further mechanistic insight into this crosstalk, we investigated the effect of acidosis on the transcriptome of renal epithelial cells (NRK-52E) and renal fibroblasts (NRK-49F) in co-culture by RNASeq, bioinformatics analysis and experimental validation. Cells were exposed to acidic media or control media for 48 h. RNA and protein from whole cell lysate were isolated. In addition, cells were fractionated into cytosol, nucleus and chromatin. RNASeq data were analyzed for differential expression and pathway enrichment (ingenuity pathway analysis, IPA, QIAGEN). Total and phosphorylated protein expression was assessed by Western blot (WB). Transcription factor activity was assessed by luciferase reporter assay. Bioinformatic analysis using differentially expressed genes according to RNASeq (7834 for NRK-52E and 3197 for NRK-49F) predicted the antioxidant and cell-protective Nrf2 pathway as acidosis-induced in NRK-52E and NRK-49F cells. Activation of Nrf2 comprises enhanced Nrf2 phosphorylation, nuclear translocation, DNA binding and initiation of a cell protective transcriptional program. Our data show that acidosis enhances chromatin-associated Nrf2 expression and the abundance of phosphorylated Nrf2 in the chromatin fraction of NRK-52E cells in co-culture but not in monoculture. Furthermore, acidosis enhances the activity of a reporter for Nrf2 (ARE-luciferase). Despite the bioinformatics prediction, NRK-49F cells did not respond with Nrf2 activation. Transketolase (TKT) is an important regulator of antioxidant and homeostatic responses in the kidney and a canonical Nrf2 target gene. We show that protein and mRNA expression of TKT is increased in NRK-52E cells under co-culture but not under monoculture conditions. In conclusion, our data show that extracellular acidosis activates the cytoprotective transcription factor Nrf2 in renal epithelial cells co-cultivated with renal fibroblasts, thereby enhancing the expression of cytoprotective TKT. This protective response is not observed in monoculture. Activation of the Nrf2 pathway represents a co-operative cellular strategy of protection against acidosis.
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Extracellular pH is an important parameter influencing cell function and fate. Microenvironmental acidosis accompanies different pathological situations, including inflammation, hypoxia and ischemia. Research focussed mainly on acidification of the tumour micromilieu and the possible consequences on proliferation, migration and drug resistance. Much less is known regarding the impact of microenvironmental acidosis on the transcriptome of non-tumour cells, which are exposed to local acidosis during inflammation, hypoxia, ischemia or metabolic derailment. In the present hypothesis-generating study, we investigated the transcriptional impact of extracellular acidosis on five non-tumour cell types of human and rat origin, combining RNA-Sequencing and extensive bioinformatics analyses. For this purpose, cell type-dependent acidosis resiliences and acidosis-induced transcriptional changes within these resilience ranges were determined, using 56 biological samples. The RNA-Sequencing results were used for dual differential-expression analysis (DESeq and edgeR) and, after appropriate homology mapping, Gene Ontology enrichment analysis (g:Profiler), Ingenuity Pathway Analysis (IPA®), as well as functional enrichment analysis for predicted upstream regulators, were performed. Extracellular acidosis led to substantial, yet different, quantitative transcriptional alterations in all five cell types. Our results identify the regulator of the transcriptional activity NCOA5 as the only general acidosis-responsive gene. Although we observed a species- and cell type-dominated response regarding gene expression regulation, Gene Ontology enrichment analysis and upstream regulator analysis predicted a general acidosis response pattern. Indeed, they suggested the regulation of four general acidosis-responsive cellular networks, which comprised the integrated stress response (ISR), TGF-ß signalling, NFE2L2 and TP53. Future studies will have to extend the results of our bioinformatics analyses to cell biological and cell physiological validation experiments, in order to test the refined working hypothesis here.
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Acidose , Transcriptoma , Animais , Humanos , Ratos , Acidose/genética , Hipóxia , Análise de Sequência de RNA , Especificidade de Órgãos , Especificidade da EspécieRESUMO
Vascular smooth muscle cells (VSMC) are critical for the vascular tone, but they can also drive the development of vascular diseases when they lose their contractile phenotype and de-differentiate. Previous studies showed that the epidermal growth factor receptor (EGFR) of VSMC is critical for vascular health, but most of the underlying mechanisms by which VSMC-EGFR controls vascular fate have remained unknown. We combined RNA-sequencing and bioinformatics analysis to characterize the effect of EGFR-activation on the transcriptome of human primary VSMC (from different female donors) and to identify potentially affected cellular processes. Our results indicate that the activation of human VSMC-EGFR is sufficient to trigger a phenotypical switch toward a proliferative and inflammatory phenotype. The extent of this effect is nonetheless partly donor-dependent. Our hypothesis-generating study thus provides a first insight into mechanisms that could partly explain variable susceptibilities to vascular diseases in between individuals.
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Endothelial cells (EC) are key players in vascular function, homeostasis and inflammation. EC show substantial heterogeneity due to inter-individual variability (e.g. sex-differences) and intra-individual differences as they originate from different organs or vessels. This variability may lead to different responsiveness to external stimuli. Here we compared the responsiveness of female human primary EC from the aorta (HAoEC) and coronary arteries (HCAEC) to Epidermal Growth Factor Receptor (EGFR) activation. EGFR is an important signal integration hub for vascular active substances with physiological and pathophysiological relevance. Our transcriptomic analysis suggested that EGFR activation differentially affects the inflammatory profiles of HAoEC and HCAEC, particularly by inducing a HCAEC-driven leukocyte attraction but a downregulation of adhesion molecule and chemoattractant expression in HAoEC. Experimental assessments of selected inflammation markers were performed to validate these predictions and the results confirmed a dual role of EGFR in these cells: its activation initiated an anti-inflammatory response in HAoEC but a pro-inflammatory one in HCAEC. Our study highlights that, although they are both arterial EC, female HAoEC and HCAEC are distinguishable with regard to the role of EGFR and its involvement in inflammation regulation, what may be relevant for vascular maintenance but also the pathogenesis of endothelial dysfunction.
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Vasos Coronários , Células Endoteliais , Humanos , Feminino , Vasos Coronários/metabolismo , Células Endoteliais/metabolismo , Células Cultivadas , Aorta , Receptores ErbB/metabolismo , Inflamação/metabolismo , Endotélio Vascular/metabolismoRESUMO
This review summarizes the work conducted in the last decade on the fabrication of mesostructured patterns, which have lateral dimensions within the nano- and microscales, over a wafer-scaled size by means of dynamic self-assembly using Langmuir-Blodgett (LB) transfer or dip-coating. First, strategies to form mesostructures from a homogeneous Langmuir monolayer with controlled shape, size, and patterns alignment will be presented, followed by a detailed theoretical explanation of the pattern formation. In addition, the patterning of nanocrystals and other chemicals with LB transfer or other dynamic processes, such as dip-coating, will be summarized.
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The influence of the subphase temperature on the stripe pattern formation during Langmuir-Blodgett transfer (LB patterning) is investigated in a combined experimental and theoretical study. According to our experiments on the LB transfer of dipalmitoylphosphatidylcholine (DPPC) on planar mica substrates, even small temperature changes between 21.5 and 24.5 °C lead to significant changes in the monolayer patterns. For a constant surface pressure and dipper speed, the width of the stripes and the overall spatial period of the patterns increase with increasing subphase temperature. Because the stripe patterns are ascribed to alternating monolayer domains in the liquid-expanded and the liquid-condensed phases, the working regime for the formation of stripes is found to depend strongly on the respective surface pressure-area isotherm. These experimental findings are in accordance with the results of a theoretical investigation based on a model that takes hydrodynamics and the monolayer thermodynamics into account.
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1,2-Dipalmitoilfosfatidilcolina/química , Silicatos de Alumínio/química , Temperatura , Microscopia de Força Atômica , Modelos Teóricos , Propriedades de Superfície , TermodinâmicaRESUMO
Infective endocarditis (IE) is an uncommon, potentially life-threatening microbial infection of the endocardial surface of the heart. An increased risk for IE is associated with a variety of pre-existing structural intracardiac conditions, including a bicuspid aortic valve, which provide a nidus for infection. A bicuspid aortic valve affects 0.5 to 2% of the population, the majority of patients are male, and patients usuallyremain unaware of their condition until infection or calcific valvular dysfunction occurs. We report two cases of native valve IE in otherwise healthy young men seen within a recent two-month period; both cases involved a previously undiagnosed bicuspid aortic valve and required a combination of aggressive antimicrobial therapy and early surgery as definitive treatment. Any patient, especially a young male, presentingwith a febrile illness and a previously or newly diagnosed heart murmur should raise the index of clinical suspicion for this disease.
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Valva Aórtica/anormalidades , Endocardite Bacteriana/diagnóstico , Adulto , Antibacterianos/uso terapêutico , Terapia Combinada , Diagnóstico Diferencial , Endocardite Bacteriana/tratamento farmacológico , Endocardite Bacteriana/cirurgia , Implante de Prótese de Valva Cardíaca/métodos , Humanos , MasculinoRESUMO
The kidney is threatened by a lot of potentially toxic substances. To study the influence of the nephrotoxin ochratoxin A (OTA) we established a cell co-culture model consisting of human renal proximal tubule cells and fibroblasts. We studied the effect of OTA on cell survival, the expression of genes and/or proteins related to cell death, extracellular matrix and energy homeostasis. OTA-induced necrosis was enhanced in both cell types in the presence of the respective other cell type, whereas OTA-induced apoptosis was independent therefrom. In fibroblasts, but not in tubule cells, a co-culture effect was visible concerning the expression of the cell-cycle-related protein p21. The expression of the epithelial-to-mesenchymal transition-indicating protein vimentin was independent from the culture-condition. The expression of the OTA-induced lncRNA WISP1-AS1 was enhanced in co-culture. OTA exposure led to alterations in the expression of genes related to energy metabolism with a glucose-mobilizing effect and a reduced expression of mitochondrial proteins. Together we demonstrate that the reaction of cells can be different in the presence of cells which naturally are close-by, thus enabling a cellular cross-talk. Therefore, to evaluate the toxicity of a substance, it would be an advantage to consider the use of co-cultures instead of mono-cultures.
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Comunicação Celular , Fibroblastos/efeitos dos fármacos , Túbulos Renais Proximais/efeitos dos fármacos , Ocratoxinas/toxicidade , Apoptose/efeitos dos fármacos , Células Cultivadas , Técnicas de Cocultura , Metabolismo Energético/efeitos dos fármacos , Transição Epitelial-Mesenquimal/efeitos dos fármacos , Fibroblastos/metabolismo , Fibroblastos/patologia , Regulação da Expressão Gênica , Humanos , Túbulos Renais Proximais/metabolismo , Túbulos Renais Proximais/patologia , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Necrose , Transdução de SinaisRESUMO
The EGF receptor (EGFR) has been extensively studied in tumor biology and recently a role in cardiovascular pathophysiology was suggested. The mineralocorticoid receptor (MR) is an important effector of the renin-angiotensin-aldosterone-system and elicits pathophysiological effects in the cardiovascular system; however, the underlying molecular mechanisms are unclear. Our aim was to investigate the importance of EGFR for MR-mediated cardiovascular pathophysiology because MR is known to induce EGFR expression. We identified a SNP within the EGFR promoter that modulates MR-induced EGFR expression. In RNA-sequencing and qPCR experiments in heart tissue of EGFR KO and WT mice, changes in EGFR abundance led to differential expression of cardiac ion channels, especially of the T-type calcium channel CACNA1H. Accordingly, CACNA1H expression was increased in WT mice after in vivo MR activation by aldosterone but not in respective EGFR KO mice. Aldosterone- and EGF-responsiveness of CACNA1H expression was confirmed in HL-1 cells by Western blot and by measuring peak current density of T-type calcium channels. Aldosterone-induced CACNA1H protein expression could be abrogated by the EGFR inhibitor AG1478. Furthermore, inhibition of T-type calcium channels with mibefradil or ML218 reduced diameter, volume and BNP levels in HL-1 cells. In conclusion the MR regulates EGFR and CACNA1H expression, which has an effect on HL-1 cell diameter, and the extent of this regulation seems to depend on the SNP-216 (G/T) genotype. This suggests that the EGFR may be an intermediate for MR-mediated cardiovascular changes and that SNP analysis can help identify subgroups of patients that will benefit most from MR antagonists.
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Canais de Cálcio Tipo T/genética , Receptores ErbB/genética , Hipertrofia/genética , Receptores de Mineralocorticoides/genética , Aldosterona/genética , Animais , Sistema Cardiovascular/efeitos dos fármacos , Sistema Cardiovascular/patologia , Linhagem Celular , Feminino , Genótipo , Células HEK293 , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Antagonistas de Receptores de Mineralocorticoides/farmacologia , Miócitos Cardíacos/efeitos dos fármacos , Polimorfismo de Nucleotídeo Único/genética , RatosRESUMO
The formation of regular stripe patterns during transfer of surfactant monolayers onto solid substrates is investigated. Two coupled differential equations describing the surfactant density and the height profile of the water subphase are derived within the lubrication approximation. If the transfer is carried out in the vicinity of a first order phase transition of the surfactant, the interaction with the substrate plays a key role. This effect is included in the surfactant free-energy functional via a height-dependent external field. Using transfer velocity as a control parameter, a bifurcation from a homogeneous transfer to regular stripe patterns arranged parallel to the contact line is investigated in one and two dimensions. Moreover, in the two-dimensional case, a secondary bifurcation to perpendicular stripes is observed in a certain control parameter range.
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Environmental food contaminants constitute a threat to human health. For instance, the globally spread mycotoxin Ochratoxin A (OTA) contributes to chronic kidney damage by affecting proximal tubule cells via unknown mechanisms. We applied a top-down approach to identify relevant toxicological mechanisms of OTA using RNA-sequencing followed by in-depth bioinformatics analysis and experimental validation. Differential expression analyses revealed that OTA led to the regulation of gene expression in kidney human cell lines, including for genes enriched in cell cycle-related pathways, and OTA-induced gap 1 and 2 (G1 and G2) cell-cycle arrests were observed. Weighted correlation network analysis highlighted cyclin dependent kinase 2 (CDK2) as a putative key regulator of this effect. CDK2 was downregulated by OTA exposure, and its overexpression partially blocked the OTA-induced G1 but not G2 cell-cycle arrest. We, therefore, propose CDK2 as one of the key regulators of the G1 cell-cycle arrest induced by low nanomolar concentrations of OTA.
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Pontos de Checagem do Ciclo Celular/genética , Quinase 2 Dependente de Ciclina/metabolismo , Poluentes Ambientais/toxicidade , Redes Reguladoras de Genes , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Linhagem Celular , Inibidor de Quinase Dependente de Ciclina p21/metabolismo , Regulação para Baixo/efeitos dos fármacos , Fator de Transcrição E2F1/metabolismo , Fator de Transcrição E2F4/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Redes Reguladoras de Genes/efeitos dos fármacos , Humanos , Ocratoxinas/toxicidade , FenótipoRESUMO
Jet aerated loop reactors (JLRs) provide high mass transfer coefficients (kLa) and can be used for the intensification of mass transfer limited reactions. The jet loop reactor achieves higher kLa values than a stirred tank reactor (STR). The improvement relies on significantly higher local power inputs (â¼104) than those obtainable with the STR. Operation at high local turnover rates requires efficient macromixing, otherwise reactor inhomogeneities might occur. If sufficient homogenization is not achieved, the selectivity of the reaction and the respective yields are decreased. Therefore, the balance between mixing and mass transfer in jet loop reactors is a critical design aspect. Monitoring the dissolved oxygen levels during the turnover of a steady sodium sulfite feed implied the abundance of gradients in the JLR. Prolonged mixing times at identical power input and aeration rates (â¼100%) were identified for the JLR in comparison to the STR. The insertion of a draft tube to the JLR led to a more homogenous dissolved oxygen distribution, but unfortunately a reduction of mixing time was not achieved. In case of increased medium viscosities as they may arise in high cell density cultivations, no gradient formation was detected. However, differences in medium viscosity significantly altered the mass transfer and mixing performance of the JLR.
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In industrial biotechnology increasing reactor volumes have the potential to reduce production costs. Whenever the achievable space time yield is determined by the mass transfer performance of the reactor, energy efficiency plays an important role to meet the requirements regarding low investment and operating costs. Based on theoretical calculations, compared to bubble column, airlift reactor, and aerated stirred tank, the jet loop reactor shows the potential for an enhanced energetic efficiency at high mass transfer rates. Interestingly, its technical application in standard biotechnological production processes has not yet been realized. Compared to a stirred tank reactor powered by Rushton turbines, maximum oxygen transfer rates about 200% higher were achieved in a jet loop reactor at identical power input in a fed batch fermentation process. Moreover, a model-based analysis of yield coefficients and growth kinetics showed that E. coli can be cultivated in jet loop reactors without significant differences in biomass growth. Based on an aerobic fermentation process, the assessment of energetic oxygen transfer efficiency [kgO2 kW-1 h-1] for a jet loop reactor yielded an improvement of almost 100%. The jet loop reactor could be operated at mass transfer rates 67% higher compared to a stirred tank. Thus, an increase of 40% in maximum space time yield [kg m-3 h-1] could be observed.
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The impact of mass transfer on productivity can become a crucial aspect in the fermentative production of bulk chemicals. For highly aerobic bioprocesses the oxygen transfer rate (OTR) and productivity are coupled. The achievable space time yields can often be correlated to the mass transfer performance of the respective bioreactor. The oxygen mass transfer capability of a jet aerated loop reactor is discussed in terms of the volumetric oxygen mass transfer coefficient kLa [h-1] and the energetic oxygen transfer efficiency E [kgO2 kW-1 h-1]. The jet aerated loop reactor (JLR) is compared to the frequently deployed aerated stirred tank reactor. In jet aerated reactors high local power densities in the mixing zone allow higher mass transfer rates, compared to aerated stirred tank reactors. When both reactors are operated at identical volumetric power input and aeration rates, local kLa values up to 1.5 times higher are possible with the JLR. High dispersion efficiencies in the JLR can be maintained even if the nozzle is supplied with pressurized gas. For increased oxygen demands (above 120 mmol L-1 h-1) improved energetic oxygen transfer efficiencies of up to 100 % were found for a JLR compared to an aerated stirred tank reactor operating with Rushton turbines.
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The reduction of CO2 emissions is a global effort which is not only supported by the society and politicians but also by the industry. Chemical producers worldwide follow the strategic goal to reduce CO2 emissions by replacing existing fossil-based production routes with sustainable alternatives. The smart use of CO and CO2 /H2 mixtures even allows to produce important chemical building blocks consuming the said gases as substrates in carboxydotrophic fermentations with acetogenic bacteria. However, existing industrial infrastructure and market demands impose constraints on microbes, bioprocesses and products that require careful consideration to ensure technical and economic success. The mini review provides scientific and industrial facets finally to enable the successful implementation of gas fermentation technologies in the industrial scale.
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Bactérias/metabolismo , Dióxido de Carbono/metabolismo , Monóxido de Carbono/metabolismo , Gases/metabolismo , Hidrogênio/metabolismo , Bactérias/genética , Bactérias/crescimento & desenvolvimento , Fermentação , Microbiologia Industrial , Transferência de TecnologiaRESUMO
BACKGROUND: The use of continuous positive airway pressure (CPAP) perioperatively in bariatric surgery patients with obstructive sleep apnea (OSA) has been controversial. Although studies have demonstrated that CPAP use is safe in bariatric patients, prior studies have not shown improvement in outcomes in these patients. METHODS: A retrospective review of patients who underwent bariatric surgery from 2005 to 2009 was performed. All patients underwent polysomnography preoperatively. Patient age, sex, BMI, comorbidities, polysomnogram data, type of bariatric procedure, length of hospital stay, and postoperative complications were reviewed. The Fisher exact test was used for statistical analysis. RESULTS: Among the 352 patients studied, 47 with apnea-hypopnea index (AHI) ≥5 did not receive CPAP postoperatively. A total of 7/47 (14.9 %) developed postoperative pulmonary complications. There were no non-pulmonary complications. Some 9/305 (2.95 %) with CPAP developed pulmonary complications. There were 26/305 patients with all-cause complications (8.52 %). The AHI was higher in the group receiving treatment. There was a statistically significant difference in pulmonary complications between patients with and those without treatment (p value 0.0002). The average length of stay was 3.0 and 3.2 days in treatment and comparison groups, respectively, a difference that did not reach statistical significance. CONCLUSIONS: Patients who did not receive CPAP postoperatively developed more pulmonary complications than those with CPAP, suggesting that CPAP might be beneficial in decreasing pulmonary complications in patients undergoing bariatric surgery. However, further investigation is warranted to better delineate other risk factors due to small sample size in our study group.
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Obesidade Mórbida/cirurgia , Apneia Obstrutiva do Sono/complicações , Cirurgia Bariátrica/efeitos adversos , Comorbidade , Pressão Positiva Contínua nas Vias Aéreas , Feminino , Humanos , Hipóxia/etiologia , Masculino , Pessoa de Meia-Idade , Obesidade Mórbida/complicações , Pneumonia/etiologia , Complicações Pós-Operatórias/etiologia , Estudos Retrospectivos , Fatores de Risco , Estados UnidosRESUMO
Mechanical stress normal to the boundary of a tissue sheet can arise in both constrained as well as unconstrained epithelial layers through pushing and pulling of surrounding tissue and substrate adhesiveness, respectively. A continuum model is used to investigate how such stress influences the epithelial dynamics. Four types of spreading and motility can be identified: a uniformly stretched stationary state, uniform sheet migration, active stress compensation by polarization close to the boundary, and a wormlike progression by deformation waves. Analytical and numerical solutions are presented along with bifurcation diagrams using normal stress and active force as control parameters.