Are fluorescence-based chlorophyll quantification methods suitable for algae toxicity assessment of carbon nanomaterials?

Using a multiwalled carbon nanotube (MWCNT) and graphene oxide (GO) as representative test materials, we evaluated the applicability of in vivo and in vitro chlorophyll-a (Chl-a) fluorescence quantification methods, which are used in standard algae ecotoxicity tests such as OECD 201 and ISO 8692. In vivo quantification of Chl-a from Raphidocelis subcapitata indicated a significant reduction in Chl-a fluorescence in the presence of MWCNTs due to shading, but a significant autofluorescence from GO caused an overestimation of Chl-a concentration. In vitro Chl-a quantification methods employing a modified acetone and an ethanol extraction protocol reduced the influence of shading and autofluorescence, but both resulted in a significant loss of fluorescence signal in the presence of 100?mgL^?1 MWCNTs (99–100%) and GO (21–52%). Chl-a reduction was dose dependent for both tested carbon-based MNMs (CNMs), but effects were more pronounced for MWCNT, which caused a significant fluorescence reduction (16?±?0.3%) already at 1?mgL^?1. Further study of the CNM–algae–Chl-a interaction processes revealed that CNM can not only interact with live algae, but also efficiently adsorb extracted Chl-a. Our results showed that within 10?min, 95–100% of Chl-a extracted from two algae concentrations were adsorbed to MWCNT, while 35–60% of Chl-a was adsorbed to the GO. This study shows that Chl-a quantification by fluorescence determination is not a suitable method for ecotoxicity testing of CNM. However, a quick screening test for individual MNMs is recommended to determine whether Chl-a adsorption is a significant process prior to selection of a quantification method.     

Assessing the Use of the “Opening Angle Method” to Enforce Residual Stresses in Patient-Specific Arteries

Numerical and analytical studies on cylindrical geometries have shown the relevance of accounting for residual stresses in arterial modeling. However, multiple difficulties, both geometrical and numerical, arise when enforcing residual stresses in patient-specific arteries. This is the reason of the few simulations that have been developed on this kind of geometries. In this paper we present a methodology that allows to include residual stresses in arbitrary geometries. Since it is not necessary to know the opened configuration of the artery, it makes it possible to take advantage of non-invasive image acquisition techniques such as CT or MRI to create customized arterial models. A simplified initial strain field showing its accuracy when applied to actual in vivo closed geometries is hypothesized from an opening angle experiment. In addition to residual stresses, the anisotropic hyperelastic and multilayered nature of the arterial tissue was accounted for the simulations of the behavior of a human coronary and iliac arteries. Results show the relevance of considering all these features for getting realistic results and the relative accuracy of using approximate solutions of residual stresses in patient-specific arterial simulations.     

Bench Validation of a Handcrafted Prototype Catheter for Intra-gastric Pressure Monitoring

Background

Abdominal compartment syndrome is a sustained intra-abdominal pressure (IAP) >20 mm Hg associated with new organ dysfunction. In order to prevent its development and related complications, IAP monitoring should be performed in patients with risk factors. Although techniques for its monitoring have been developed, they are of high cost and not always available in low- and lower–middle-income countries. Therefore, we aim to develop and validate in a bench model a handcrafted catheter to be used as an alternative method to measure the intra-gastric pressure (IGP) as a surrogate of the IAP.

Methods

We used an acrylic water container as a model of the abdomen and four handcrafted catheters made of a 16 Fr Levin tube with a globe finger tied with silk in the distal end, inflated with 1 cm of air. They were placed on the bottom of the container where the water pressure was directly measured as a gold standard. The agreement between the two measures was assessed with the Bland–Altman method.

Results

We performed 120 simultaneous measures. The mean pressure difference was 0.218 (95% CI 0.074 to 0.363).

Conclusions

The handcrafted prototype catheter and the direct measure were highly correlated. The new catheter is a reliable and reproducible tool for pressure monitoring. However, before it can be used in the clinical setting for IAP monitoring, validation in human models in a real clinical setting needs to be performed.

     

Semen analysis of Golden Retriever healthy dogs and those affected by muscular dystrophy

This study aimed to characterise canine flow cytometry semen analysis, as well as seminal reactive oxygen species dosage using the Golden Retriever breed as model of study. Moreover, we searched for the influence of muscular dystrophy in Golden Retriever dogs on semen parameters. Thirty‐seven semen samples were obtained from healthy Golden Retrievers (n = 15) and from muscular dystrophy affected dogs (n = 22). Sperm‐rich fractions were analysed by standardised breeding soundness examination in addition to the assay of fluorescence assisted cell sorting for acrosome integrity, mitochondrial activity and DNA fragmentation. Volume of ejaculate, per cent of motile spermatozoa and vigour were similar between groups; there were no differences in the per cent of minor and major defects. Integrity of acrosomal membrane, mitochondrial potential and sperm DNA fragmentation had no significant differences between groups either. Animals from control group had higher concentration of spontaneous seminal oxidative species in comparison with affected animals. Dogs affected by dystrophy had seminal parameters similar to those observed in healthy dogs except for the lower concentration of oxidative species. Future studies aiming to establish reference values for canine seminal parameters should be considered preferably with distinction of breeds.     

Impact of the Learning Curve on the Outcome of Domino Liver Transplantation

Domino liver transplantation (DLT) is a strategy used to increase the number of available grafts. In this procedure, the transplant recipient is a living donor of her own liver. It is mandatory that the graft should be fully functional and the genetic defect should recur with sufficient latency period in the new recipient. Corino-Andrade disease, or familial amyloidotic polyneuropathy (FAP), satisfies these conditions. We retrospectively reviewed our prospective database of DLT. From July 2004 to April 2013, we performed 12 DLTs. We assessed age, sex, real Model for End-Stage Liver Disease (MELD) score, waiting list time, cold and warm ischemia times, intraoperative transfusion requirements, hospital stay, early peritransplantation morbidity (post-reperfusion syndrome, intraoperative cardiac arrest, post-transplantation thrombotic events, and biliary morbidity), acute cellular rejection, retransplantation, mortality, patient and graft survivals. With the intention to study the effect of the learning curve in the global survival results (including both donors and recipients of livers with FAP), we divided our series into 2 periods: the early period (from 2004 to 2008) and the present period (from 2009 to 2013). The crude mortality was 40% vs 0% (P = .042) in the early and present periods, respectively. The cumulative patient survival was also significantly in favor of the present period (P = .049). The graft loss prevalence was 60% vs 7.1% (P = .019) in the early and present periods, respectively. The cumulative graft survival was also significantly in favor of the present period (P = .030; Fig 2). In conclusion, we consider DLT to be a complex procedure, whose initial results are conditioned by the learning curve.