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1.
Cell ; 156(3): 469-81, 2014 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-24485455

RESUMO

Autophagy is a catabolic pathway that sequesters undesired cellular material into autophagosomes for delivery to lysosomes for degradation. A key step in the pathway is the covalent conjugation of the ubiquitin-related protein Atg8 to phosphatidylethanolamine (Atg8-PE) in autophagic membranes by a complex consisting of Atg16 and the Atg12-Atg5 conjugate. Atg8 controls the expansion of autophagic precursor membranes, but the underlying mechanism remains unclear. Here, we reconstitute Atg8 conjugation on giant unilamellar vesicles and supported lipid bilayers. We found that Atg8-PE associates with Atg12-Atg5-Atg16 into a membrane scaffold. By contrast, scaffold formation is counteracted by the mitochondrial cargo adaptor Atg32 through competition with Atg12-Atg5 for Atg8 binding. Atg4, previously known to recycle Atg8 from membranes, disassembles the scaffold. Importantly, mutants of Atg12 and Atg16 deficient in scaffold formation in vitro impair autophagy in vivo. This suggests that autophagic scaffolds are critical for phagophore biogenesis and thus autophagy.


Assuntos
Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/metabolismo , Autofagia , Família da Proteína 8 Relacionada à Autofagia , Membrana Celular/química , Membrana Celular/metabolismo , Proteínas Associadas aos Microtúbulos/química , Proteínas Associadas aos Microtúbulos/metabolismo , Modelos Moleculares , Proteínas de Saccharomyces cerevisiae/química , Ubiquitina-Proteína Ligases/química , Ubiquitina-Proteína Ligases/metabolismo
2.
Cell ; 150(5): 909-21, 2012 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-22939620

RESUMO

Some Ts in nuclear DNA of trypanosomes and Leishmania are hydroxylated and glucosylated to yield base J (ß-D-glucosyl-hydroxymethyluracil). In Leishmania, about 99% of J is located in telomeric repeats. We show here that most of the remaining J is located at chromosome-internal RNA polymerase II termination sites. This internal J and telomeric J can be reduced by a knockout of J-binding protein 2 (JBP2), an enzyme involved in the first step of J biosynthesis. J levels are further reduced by growing Leishmania JBP2 knockout cells in BrdU-containing medium, resulting in cell death. The loss of internal J in JBP2 knockout cells is accompanied by massive readthrough at RNA polymerase II termination sites. The readthrough varies between transcription units but may extend over 100 kb. We conclude that J is required for proper transcription termination and infer that the absence of internal J kills Leishmania by massive readthrough of transcriptional stops.


Assuntos
Glucosídeos/metabolismo , Leishmania/genética , Leishmania/metabolismo , Transcrição Gênica , Uracila/análogos & derivados , Técnicas de Inativação de Genes , RNA Polimerase II/metabolismo , RNA de Cadeia Dupla/metabolismo , Uracila/metabolismo
3.
Am J Transplant ; 24(7): 1110-1126, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38184242

RESUMO

Normothermic machine perfusion (NMP) has emerged as a promising tool for the preservation, viability assessment, and repair of deceased-donor kidneys prior to transplantation. These kidneys inevitably experience a period of ischemia during donation, which leads to ischemia-reperfusion injury when NMP is subsequently commenced. Ischemia-reperfusion injury has a major impact on the renal vasculature, metabolism, oxygenation, electrolyte balance, and acid-base homeostasis. With an increased understanding of the underlying pathophysiological mechanisms, renoprotective strategies and therapeutic interventions can be devised to minimize additional injury during normothermic reperfusion, ensure the safe implementation of NMP, and improve kidney quality. This review discusses the pathophysiological alterations in the vasculature, metabolism, oxygenation, electrolyte balance, and acid-base homeostasis of deceased-donor kidneys and delineates renoprotective strategies and therapeutic interventions to mitigate renal injury and improve kidney quality during NMP.


Assuntos
Transplante de Rim , Preservação de Órgãos , Perfusão , Traumatismo por Reperfusão , Traumatismo por Reperfusão/prevenção & controle , Humanos , Preservação de Órgãos/métodos , Rim/irrigação sanguínea , Rim/fisiopatologia , Animais
4.
Am J Transplant ; 24(9): 1547-1557, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-38719094

RESUMO

Kidney transplantation remains the gold standard for patients with end-stage renal disease, but severe donor organ shortage has led to long waiting lists. The utilization of expanded criteria donor kidneys within the category of deceased donors has enlarged the pool of available kidneys for transplantation; however, these grafts often have an increased risk for delayed graft function or reduced graft survival following transplantation. During brain or circulatory death, neutrophils are recruited to the vascular beds of kidneys where a proinflammatory microenvironment might prime the formation of neutrophil extracellular traps (NETs), web-like structures, containing proteolytic enzymes, DNA, and histones. NETs are known to cause tissue damage and specifically endothelial damage while activating other systems such as coagulation and complement, contributing to tissue injury and an unfavorable prognosis in various diseases. In lung transplantation and kidney transplantation studies, NETs have also been associated with primary graft dysfunction or rejection. In this review, the role that NETs might play across the different phases of transplantation, already initiated in the donor, during preservation, and in the recipient, will be discussed. Based on current knowledge, NETs might be a promising therapeutic target to improve graft outcomes.


Assuntos
Armadilhas Extracelulares , Transplante de Rim , Doadores de Tecidos , Humanos , Transplante de Rim/efeitos adversos , Armadilhas Extracelulares/metabolismo , Doadores de Tecidos/provisão & distribuição , Neutrófilos/imunologia , Neutrófilos/metabolismo , Falência Renal Crônica/cirurgia , Transplantados , Sobrevivência de Enxerto/imunologia , Rejeição de Enxerto/etiologia , Rejeição de Enxerto/imunologia
5.
Am J Transplant ; 2024 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-38615901

RESUMO

Normothermic machine perfusion (NMP) is increasingly considered for pretransplant kidney quality assessment. However, fundamental questions about differences between in vivo and ex vivo renal function, as well as the impact of ischemic injury on ex vivo physiology, remain unanswered. This study utilized magnetic resonance imaging (MRI), alongside conventional parameters to explore differences between in vivo and ex vivo renal function and the impact of warm ischemia on a kidney's behavior ex vivo. Renal MRI scans and samples were obtained from living pigs (n = 30) in vivo. Next, kidney pairs were procured and exposed to minimal, or 75 minutes of warm ischemia, followed by 6 hours of hypothermic machine perfusion. Both kidneys simultaneously underwent 6-hour ex vivo perfusion in MRI-compatible NMP circuits to obtain multiparametric MRI data. Ischemically injured ex vivo kidneys showed a significantly altered regional blood flow distribution compared to in vivo and minimally damaged organs. Both ex vivo groups showed diffusion restriction relative to in vivo. Our findings underscore the differences between in vivo and ex vivo MRI-based renal characteristics. Therefore, when assessing organ viability during NMP, it should be considered to incorporate parameters beyond the conventional functional markers that are common in vivo.

6.
Nephrol Dial Transplant ; 39(8): 1239-1247, 2024 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-38400561

RESUMO

Through improved insights into the increasing incidence and detrimental effects of acute kidney injury (AKI), its clinical relevance has become more and more apparent. Although treatment strategies for AKI have also somewhat improved, an adequate remedy still does not exist. Finding one is complicated by a multifactorial pathophysiology and by heterogeneity in the patient population. Alkaline phosphatase (ALP) has been suggested as a therapy for sepsis-associated AKI because of its protective effects against lipopolysaccharide (LPS)-induced inflammation and kidney injury in animals. However, its effectiveness as an AKI treatment has not been demonstrated definitively. Because the anti-inflammatory properties of ALP are likely not reliant on a direct effect on LPS itself, we postulate that other pathways are much more important in explaining the renoprotective properties ascribed to ALP. The re-evaluation of which properties of the ALP enzyme are responsible for the benefit seen in the lab is an important step in determining where the true potential of ALP as a treatment strategy for AKI in the clinic lies. In this review we will discuss how ALP can prevent activation of harmful pro-inflammatory receptors, redirect cell-cell signalling and protect barrier tissues, which together form the basis for current knowledge of the role of ALP in the kidney. With this knowledge in mind and by analysing currently available clinical evidence, we propose directions for new research that can determine whether ALP as a treatment strategy for AKI has a future in the clinical field.


Assuntos
Injúria Renal Aguda , Fosfatase Alcalina , Injúria Renal Aguda/etiologia , Injúria Renal Aguda/terapia , Humanos , Fosfatase Alcalina/metabolismo , Animais
8.
J Surg Res ; 301: 248-258, 2024 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-38970873

RESUMO

INTRODUCTION: Normothermic machine perfusion (NMP) of donor kidneys provides the opportunity to assess and improve organ viability prior to transplantation. This study explored the necessity of an oxygen carrier during NMP and whether the hemoglobin-based oxygen carrier (HBOC-201) is a suitable alternative to red blood cells (RBCs). METHODS: Porcine kidneys were perfused with a perfusion solution containing either no-oxygen carrier, RBCs, or HBOC-201 for 360 min at 37°C. RESULTS: Renal flow and resistance did not differ significantly between groups. NMP without an oxygen carrier showed lower oxygen consumption with higher lactate and aspartate aminotransferase levels, indicating that the use of an oxygen carrier is necessary for NMP. Cumulative urine production and creatinine clearance in the RBC group were significantly higher than in the HBOC-201 group. Oxygen consumption, injury markers, and histology did not differ significantly between these two groups. However, methemoglobin levels increased to 45% after 360 min in the HBOC-201 group. CONCLUSIONS: We conclude that HBOC-201 could be used as an alternative for RBCs, but accumulating methemoglobin levels during our perfusions indicated that HBOC-201 is probably less suitable for prolonged NMP. Perfusion with RBCs, compared to HBOC-201, resulted in more favorable renal function during NMP.

9.
Artif Organs ; 48(6): 595-605, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38164041

RESUMO

BACKGROUND: Normothermic machine perfusion (NMP) is a promising pretransplant kidney quality assessment platform, but it remains crucial to increase its diagnostic potential while ensuring minimal additional injury to the already damaged kidney. Interventions that alter tubular transport can influence renal function and injury during perfusion. This study aimed to determine whether furosemide and desmopressin affect renal function and injury during NMP. METHODS: Eighteen porcine kidneys (n = 6 per group) were subjected to 30 min of warm ischemia and 4 h of oxygenated hypothermic perfusion before being subjected to 6 h of NMP. Each organ was randomized to receive no drug, furosemide (750 mg), or desmopressin (16 µg) during NMP. RESULTS: Compared with the other groups, the addition of furosemide resulted in significantly increased urine output, fractional excretion of sodium and potassium, and urea clearance during NMP. Urinary neutrophil gelatinase-associated lipocalin levels decreased significantly with furosemide supplementation compared with the other groups. The addition of desmopressin did not result in any significantly different outcome measurements compared with the control group. CONCLUSIONS: This study showed that the addition of furosemide affected renal function while attenuating tubulointerstitial injury during NMP. Therefore, furosemide supplementation may provide renal protection and serve as a functional test for pretransplant kidney viability assessment during NMP.


Assuntos
Furosemida , Rim , Preservação de Órgãos , Perfusão , Animais , Furosemida/farmacologia , Suínos , Perfusão/métodos , Rim/efeitos dos fármacos , Rim/patologia , Preservação de Órgãos/métodos , Desamino Arginina Vasopressina/farmacologia , Transplante de Rim , Isquemia Quente/efeitos adversos
10.
Artif Organs ; 2024 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-39193869

RESUMO

INTRODUCTION: A growing interest in renal normothermic machine perfusion (NMP) has resulted in more clinically available perfusion devices. While all perfusion systems have the same aim, there are significant differences in their circuits, pumps, sensors, and software. Therefore, our objective was to assess the impact of different perfusion protocols and devices on kidney function and perfusion parameters during NMP. METHODS: Porcine kidneys were subjected to 30 min of warm ischemia, 24 h of static cold storage, and subsequently perfused for 6 h using (1) the Kidney Assist (KA) machine with a pressure of 75 mm Hg, (2) the KA device incorporating several adjustments and a pressure of 85 mm Hg (modified KA), or (3) the Perlife (PL) perfusion device (n = 4). Consecutively, discarded human kidneys were perfused using the KA or modified KA (n = 3) protocol. RESULTS: The PL group quickly reached the device's upper flow limit and consequently received a significantly lower pressure compared to the KA groups. The arterial pO2 was significantly lower in the PL group. Yet, hemoglobin concentration increased over time, and oxygen consumption was significantly higher compared to the KA groups. Fractional sodium excretion was significantly lower in the PL group. Tissue ATP levels, urine production, and creatinine clearance rates did not differ between groups. In human kidneys, the modified KA group showed significantly lower vascular resistance, higher oxygen delivery, and lower levels of lactate in the perfusate compared to the KA group. CONCLUSIONS: This study shows that perfusion characteristics and kidney function are significantly influenced by the perfusion protocol and the device and its settings during normothermic machine perfusion and therefore should be interpreted with caution.

11.
Artif Organs ; 48(8): 862-875, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38546373

RESUMO

BACKGROUND: Ex vivo normothermic machine perfusion (NMP) is a promising tool for assessing an isolated kidney prior to transplantation. However, there is no consensus on the perfusate's optimal oxygen-carrying capacity to support renal function. To investigate the association of hemoglobin levels with renal function parameters, a retrospective analysis of isolated, normothermically, perfused porcine kidneys was performed. METHODS: Between 2015 and 2021, a total of 228 kidneys underwent 4 h of NMP with perfusates that varied in hemoglobin levels. A generalized linear model was used to determine the association of hemoglobin levels with time-weighted means of renal function markers, such as fractional sodium excretion (FENa) and creatinine clearance (CrCl). Stratified by baseline hemoglobin level (<4.5, 4.5-6, or >6 mmol/L), these markers were modeled over time using a generalized linear mixed-effects model. All models were adjusted for potential confounders. RESULTS: Until a hemoglobin level of around 5 mmol/L was reached, increasing hemoglobin levels were associated with superior FENa and CrCl. Thereafter, this association plateaued. When hemoglobin levels were categorized, hemoglobin <4.5 mmol/L was associated with worse renal function. Hemoglobin levels were neither significantly associated with proteinuria during NMP nor with ATP levels at the end of NMP. Hemoglobin levels >6 mmol/L showed no additional benefits in renal function. CONCLUSION: In conclusion, we found an association between baseline hemoglobin levels and superior renal function parameters, but not injury, during NMP of porcine kidneys. Furthermore, we show that performing a retrospective cohort study of preclinical data is feasible and able to answer additional questions, reducing the potential use of laboratory animals.


Assuntos
Hemoglobinas , Rim , Preservação de Órgãos , Perfusão , Animais , Estudos Retrospectivos , Hemoglobinas/análise , Hemoglobinas/metabolismo , Perfusão/métodos , Rim/fisiopatologia , Suínos , Preservação de Órgãos/métodos , Transplante de Rim , Testes de Função Renal/métodos , Creatinina/sangue
12.
Int J Mol Sci ; 25(4)2024 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-38397090

RESUMO

Volatile anesthetics have been shown in different studies to reduce ischemia reperfusion injury (IRI). Ex vivo lung perfusion (EVLP) facilitates graft evaluation, extends preservation time and potentially enables injury repair and improvement of lung quality. We hypothesized that ventilating lungs with sevoflurane during EVLP would reduce lung injury and improve lung function. We performed a pilot study to test this hypothesis in a slaughterhouse sheep DCD model. Lungs were harvested, flushed and stored on ice for 3 h, after which EVLP was performed for 4 h. Lungs were ventilated with either an FiO2 of 0.4 (EVLP, n = 5) or FiO2 of 0.4 plus sevoflurane at a 2% end-tidal concentration (Cet) (S-EVLP, n = 5). Perfusate, tissue samples and functional measurements were collected and analyzed. A steady state of the target Cet sevoflurane was reached with measurable concentrations in perfusate. Lungs in the S-EVLP group showed significantly better dynamic lung compliance than those in the EVLP group (p = 0.003). Oxygenation capacity was not different in treated lungs for delta partial oxygen pressure (PO2; +3.8 (-4.9/11.1) vs. -11.7 (-12.0/-3.2) kPa, p = 0.151), but there was a trend of a better PO2/FiO2 ratio (p = 0.054). Perfusate ASAT levels in S-EVLP were significantly reduced compared to the control group (198.1 ± 93.66 vs. 223.9 ± 105.7 IU/L, p = 0.02). We conclude that ventilating lungs with sevoflurane during EVLP is feasible and could be useful to improve graft function.


Assuntos
Transplante de Pulmão , Animais , Ovinos , Sevoflurano/farmacologia , Estudos de Viabilidade , Projetos Piloto , Preservação de Órgãos , Pulmão , Perfusão
13.
Angew Chem Int Ed Engl ; : e202408295, 2024 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-39248369

RESUMO

Interacting with living systems typically involves the ability to address lipid membranes of cellular systems. The first step of interaction of a nanorobot with a cell will thus be the detection of binding to a lipid membrane. Utilizing DNA origami, we engineered a biosensor with single-molecule Fluorescence Resonance Energy Transfer (smFRET) as transduction mechanism for precise lipid vesicle detection and cargo delivery. The system hinges on a hydrophobic ATTO647N modified single-stranded DNA (ssDNA) leash, protruding from a DNA origami nanostructure. In a vesicle-free environment, the ssDNA coils, ensuring high FRET efficiency. Upon vesicle binding to cholesterol anchors on the DNA origami, hydrophobic ATTO647N induces the ssDNA to stretch towards the lipid bilayer, reducing FRET efficiency. As the next step, the sensing strand serves as molecular cargo that can be transferred to the vesicle through a triggered strand displacement reaction. Depending on the number of cholesterols on the displacer strands, we either induce a diffusive release of the fluorescent load towards neighboring vesicles or a stoichiometric release of a single cargo-unit to the vesicle on the nanosensor. Ultimately, our multi-functional liposome interaction and detection platform opens up pathways for innovative biosensing applications and controllable stoichiometric loading of vesicles with single-molecule control.

14.
Biophys J ; 122(11): 2325-2341, 2023 06 06.
Artigo em Inglês | MEDLINE | ID: mdl-36869591

RESUMO

Sphingolipids are a structurally diverse class of lipids predominantly found in the plasma membrane of eukaryotic cells. These lipids can laterally segregate with other rigid lipids and cholesterol into liquid-ordered domains that act as organizing centers within biomembranes. Owing the vital role of sphingolipids for lipid segregation, controlling their lateral organization is of utmost significance. Hence, we made use of the light-induced trans-cis isomerization of azobenzene-modified acyl chains to develop a set of photoswitchable sphingolipids with different headgroups (hydroxyl, galactosyl, phosphocholine) and backbones (sphingosine, phytosphingosine, tetrahydropyran-blocked sphingosine) that are able to shuttle between liquid-ordered and liquid-disordered regions of model membranes upon irradiation with UV-A (λ = 365 nm) and blue (λ = 470 nm) light, respectively. Using combined high-speed atomic force microscopy, fluorescence microscopy, and force spectroscopy, we investigated how these active sphingolipids laterally remodel supported bilayers upon photoisomerization, notably in terms of domain area changes, height mismatch, line tension, and membrane piercing. Hereby, we show that the sphingosine-based (Azo-ß-Gal-Cer, Azo-SM, Azo-Cer) and phytosphingosine-based (Azo-α-Gal-PhCer, Azo-PhCer) photoswitchable lipids promote a reduction in liquid-ordered microdomain area when in the UV-adapted cis-isoform. In contrast, azo-sphingolipids having tetrahydropyran groups that block H-bonding at the sphingosine backbone (lipids named Azo-THP-SM, Azo-THP-Cer) induce an increase in the liquid-ordered domain area when in cis, accompanied by a major rise in height mismatch and line tension. These changes were fully reversible upon blue light-triggered isomerization of the various lipids back to trans, pinpointing the role of interfacial interactions for the formation of stable liquid-ordered domains.


Assuntos
Esfingolipídeos , Esfingosina , Esfingolipídeos/análise , Esfingolipídeos/química , Esfingosina/análise , Bicamadas Lipídicas/química , Luz , Microdomínios da Membrana/química
15.
Curr Issues Mol Biol ; 45(7): 5437-5459, 2023 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-37504261

RESUMO

Recently, immense efforts have focused on improving the preservation of (sub)optimal donor organs by means of ex vivo perfusion, which enables the opportunity for organ reconditioning and viability assessment. However, there is still no biomarker that correlates with renal viability. Therefore, it is essential to explore new techniques for pre-transplant assessment of organ quality to guarantee successful long-term transplantation outcomes. The renal vascular compartment has received little attention in machine perfusion studies. In vivo, proper renal vascular and endothelial function is essential for maintaining homeostasis and long-term graft survival. In an ex vivo setting, little is known about vascular viability and its implications for an organ's suitability for transplant. Seeing that endothelial damage is the first step in a cascade of disruptions and maintaining homeostasis is crucial for positive post-transplant outcomes, further research is key to clarifying the (patho)physiology of the renal vasculature during machine perfusion. In this review, we aim to summarize key aspects of renal vascular physiology, describe the role of the renal vasculature in pathophysiological settings, and explain how ex vivo perfusion plays a role in either unveiling or targeting such processes. Additionally, we discuss potentially new vascular assessment tools during ex vivo renal perfusion.

16.
Ann Surg ; 278(5): 676-682, 2023 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-37503631

RESUMO

OBJECTIVE: To provide mechanistic insight into key biological alterations in donation after circulatory death kidneys during continuous pefusion we performed mass spectrometry profiling of perfusate samples collected during a phase 3 randomized double-blind paired clinical trial of hypothermic machine perfusion with and without oxygen (COMPARE). BACKGROUND: Despite the clinical benefits of novel perfusion technologies aiming to better preserve donor organs, biological processes that may be altered during perfusion have remained largely unexplored. The collection of serial perfusate samples during the COMPARE clinical trial provided a unique resource to study perfusate proteomic profiles, with the hypothesis that in-depth profiling may reveal biologically meaningful information on how donor kidneys benefit from this intervention. METHODS: Multiplexed liquid chromatography-tandem mass spectrometry was used to obtain a proteome profile of 210 perfusate samples. Partial least squares discriminant analysis and multivariate analysis involving clinical and perfusion parameters were used to identify associations between profiles and clinical outcomes. RESULTS: Identification and quantitation of 1716 proteins indicated that proteins released during perfusion originate from the kidney tissue and blood, with blood-based proteins being the majority. Data show that the overall hypothermic machine perfusion duration is associated with increasing levels of a subgroup of proteins. Notably, high-density lipoprotein and complement cascade proteins are associated with 12-month outcomes, and blood-derived proteins are enriched in the perfusate of kidneys that developed acute rejection. CONCLUSIONS: Perfusate profiling by mass spectrometry was informative and revealed proteomic changes that are biologically meaningful and, in part, explain the clinical observations of the COMPARE trial.


Assuntos
Transplante de Rim , Humanos , Transplante de Rim/métodos , Proteoma/metabolismo , Proteômica , Preservação de Órgãos/métodos , Rim/metabolismo , Perfusão/métodos , Doadores de Tecidos
17.
Nat Mater ; 21(6): 703-709, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35618822

RESUMO

Upscaling motor protein activity to perform work in man-made devices has long been an ambitious goal in bionanotechnology. The use of hierarchical motor assemblies, as realized in sarcomeres, has so far been complicated by the challenges of arranging sufficiently high numbers of motor proteins with nanoscopic precision. Here, we describe an alternative approach based on actomyosin cortex-like force production, allowing low complexity motor arrangements in a contractile meshwork that can be coated onto soft objects and locally activated by ATP. The design is reminiscent of a motorized exoskeleton actuating protein-based robotic structures from the outside. It readily supports the connection and assembly of micro-three-dimensional printed modules into larger structures, thereby scaling up mechanical work. We provide an analytical model of force production in these systems and demonstrate the design flexibility by three-dimensional printed units performing complex mechanical tasks, such as microhands and microarms that can grasp and wave following light activation.


Assuntos
Procedimentos Cirúrgicos Robóticos , Robótica , Humanos , Impressão Tridimensional
18.
J Vasc Res ; 60(1): 1-11, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36882023

RESUMO

Endovascular revascularization is the preferred treatment for peripheral arterial disease. Restenosis often occurs as a response to procedure-induced arterial damage. Reducing vascular injury during endovascular revascularization may improve its success rate. This study developed and validated an ex vivo flow model using porcine iliac arteries, obtained from a local abattoir. Twenty arteries (of 10 pigs) were equally allocated to two groups: a mock-treated control group and an endovascular intervention group. Arteries of both groups were perfused with porcine blood for 9 min, including 3 min of balloon angioplasty in the intervention group. Vessel injury was assessed by calculating the presence of endothelial cell denudation, vasomotor function, and histopathological analysis. MR imaging displayed balloon positioning and inflation. Endothelial cell staining showed 76% of denudation after ballooning compared to 6% in the control group (p < 0.001). This was confirmed by histopathological analysis, showing a significantly reduced endothelial nuclei count after ballooning compared to the controls (median: 22 vs. 37 nuclei/mm, p = 0.022). In the intervention group, vasoconstriction and endothelium-dependent relaxation were significantly reduced (p < 0.05).We present an ex vivo flow model to test the effects of endovascular therapy on the vessel's wall morphology, endothelial denudation, and endothelial-dependent vasomotor function under physiological conditions. Additionally, it allows the future testing of human arterial tissue.


Assuntos
Angioplastia Coronária com Balão , Angioplastia com Balão , Humanos , Suínos , Animais , Angioplastia Coronária com Balão/métodos , Angioplastia com Balão/efeitos adversos , Imageamento por Ressonância Magnética , Vasoconstrição/fisiologia , Artéria Ilíaca/diagnóstico por imagem , Artéria Ilíaca/cirurgia
19.
Nephrol Dial Transplant ; 38(3): 787-796, 2023 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-36318454

RESUMO

BACKGROUND: To ensure optimal utilization of deceased donor kidneys, it is important to understand the precise reasons why kidneys are discarded. In this study we aimed to obtain a comprehensive overview of kidney utilization and discard during the entire donation process in the Netherlands. METHODS: In this retrospective cohort study we analysed kidney utilization of 3856 kidneys in the Netherlands between 1 January 2015 and 31 December 2020. For every kidney that was not transplanted, we determined the moment of and reason for discard through a unique case-by-case assessment. RESULTS: Kidney discard according to the traditional definition (procured but not transplanted) was 7.8%. However, when kidneys that seemed medically suitable at the beginning of the donation process were also included, many more potential donor kidneys were lost and the total non-utilization was 24.4%. Subjectively presumed impaired organ quality was responsible for 34.2% of all discarded kidneys. Two-thirds of kidneys discarded due to acute kidney injury (AKI) had only AKI stage 1 or 2. CONCLUSION: The classical definition of organ discard underestimates the non-utilization of deceased donor kidneys. Strategies to improve kidney utilization could be a revision of the maximum allowed agonal time in donation after circulatory death, careful consideration in reporting and accepting kidneys from donors with AKI and a prospectively filled registry of detailed organ discard reasons, including the 'silent' non-utilization before procurement.


Assuntos
Injúria Renal Aguda , Transplante de Rim , Obtenção de Tecidos e Órgãos , Humanos , Estudos Retrospectivos , Países Baixos , Seleção do Doador , Sobrevivência de Enxerto , Rim , Doadores de Tecidos
20.
Transpl Int ; 36: 11374, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37547751

RESUMO

The advent of Machine Perfusion (MP) as a superior form of preservation and assessment for cold storage of both high-risk kidney's and the liver presents opportunities in the field of beta-cell replacement. It is yet unknown whether such techniques, when applied to the pancreas, can increase the pool of suitable donor organs as well as ameliorating the effects of ischemia incurred during the retrieval process. Recent experimental models of pancreatic MP appear promising. Applications of MP to the pancreas, needs refinement regarding perfusion protocols and organ viability assessment criteria. To address the "Role of pancreas machine perfusion to increase the donor pool for beta cell replacement," the European Society for Organ Transplantation (ESOT) assembled a dedicated working group comprising of experts to review literature pertaining to the role of MP as a method of improving donor pancreas quality as well as quantity available for transplant, and to develop guidelines founded on evidence-based reviews in experimental and clinical settings. These were subsequently refined during the Consensus Conference when this took place in Prague.


Assuntos
Preservação de Órgãos , Transplante de Órgãos , Humanos , Preservação de Órgãos/métodos , Pâncreas , Perfusão/métodos , Doadores de Tecidos
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