Wide-field time-of-flight measurements of highly scattering media.

We present a setup that makes use of a time-resolved single-photon camera to determine the scattering parameters of media. The measurement is realized in a non-contact way, both for the illumination laser and the detection. By fitting the time-of-flight acquired distributions at different spatial positions with the diffusion equation, we retrieve the reduced scattering coefficients of a highly diffusive isotropic reference media for wavelengths in the range from 540 to 840 nm.

Comparing PVP and Polymeric Micellar Formulations of a PEGylated Photosensitizing Phthalocyanine by NMR and Optical Techniques.

Phthalocyanines are ideal candidates as photosensitizers for photodynamic therapy (PDT) of cancer due to their favorable chemical and photophysical properties. However, their tendency to form aggregates in water reduces PDT efficacy and poses challenges in obtaining efficient forms of phthalocyanines for therapeutic applications. In the current work, polyvinylpyrrolidone (PVP) and micellar formulations were compared for encapsulating and monomerizing a water-soluble zinc phthalocyanine bearing four non-peripheral triethylene glycol chains (Pc1). 1H NMR spectroscopy combined with UV-vis absorption and fluorescence spectroscopy revealed that Pc1 exists as a mixture of regioisomers in monomeric form in dimethyl sulfoxide but forms dimers in an aqueous buffer. PVP, polyethylene glycol castor oil (Kolliphor RH40), and three different triblock copolymers with varying proportions of polyethylene and polypropylene glycol units (termed P188, P84, and F127) were tested as micellar carriers for Pc1. 1H NMR chemical shift analysis, diffusion-ordered spectroscopy, and 2D nuclear Overhauser enhancement spectroscopy was applied to monitor the encapsulation and localization of Pc1 at the polymer interface. Kolliphor RH40 and F127 micelles exhibited the highest affinity for encapsulating Pc1 in the micellar core and resulted in intense Pc1 fluorescence emission as well as efficient singlet oxygen formation along with PVP. Among the triblock copolymers, efficiency in binding and dimer dissolution decreased in the order F127 > P84 > P188. PVP was a strong binder for Pc1. However, Pc1 molecules are rather surface-attached and exist as monomer and dimer mixtures. The results demonstrate that NMR combined with optical spectroscopy offer powerful tools to assess parameters like drug binding, localization sites, and dynamic properties that play key roles in achieving high host-guest compatibility. With the corresponding adjustments, polymeric micelles can offer simple and easily accessible drug delivery systems optimizing phthalocyanines' properties as efficient photosensitizers.

Excluding Echo Shift Noise in Real-Time Pulse-Echo Speed-of-Sound Imaging.

Computed ultrasound tomography in echo mode (CUTE) allows real-time imaging of the tissue speed of sound (SoS) using handheld ultrasound. The SoS is retrieved by inverting a forward model that relates the spatial distribution of the tissue SoS to echo shift maps detected between varying transmit and receive angles. Despite promising results, in vivo SoS maps often show artifacts due to elevated noise in echo shift maps. To minimize artifacts, we propose a technique where an individual SoS map is reconstructed for each echo shift map separately, as opposed to a single SoS map from all echo shift maps simultaneously. The final SoS map is then obtained as a weighted average over all SoS maps. Due to the partial redundancy between different angle combinations, artifacts that appear only in a subset of the individual maps can be excluded via the averaging weights. We investigate this real-time capable technique in simulations using two numerical phantoms, one with a circular inclusion and one with two layers. Our results demonstrate that the SoS maps reconstructed using the proposed technique are equivalent to the ones using simultaneous reconstruction when considering uncorrupted data but show significantly reduced artifact level for data that are corrupted by noise.

A quantitative interspecies comparison of the respiratory mucociliary clearance mechanism.

Collectively coordinated ciliary activity propels the airway mucus, which lines the luminal surface of the vertebrate respiratory system, in cranial direction. Our contemporary understanding on how the quantitative characteristics of the metachronal wave field determines the resulting mucociliary transport is still limited, partly due to the sparse availability of quantitative observational data. We employed high-speed video reflection microscopy to image and quantitatively characterize the metachronal wave field as well as the mucociliary transport in excised bovine, porcine, ovine, lapine, turkey and ostrich samples. Image processing techniques were used to determine the ciliary beating frequency (CBF), the velocity and wavelength of the metachronal wave and the mucociliary transport velocity. The transport direction was found to strongly correlate with the mean wave propagation direction in all six species. The CBF yielded similar values (10-15 Hz) for all six species. Birds were found to exhibit higher transport speeds (130-260 [Formula: see text]m/s) than mammals (20-80 [Formula: see text]m/s). While the average transport direction significantly deviates from the tracheal long axis in mammals, no significant deviation was found in birds. The metachronal waves were found to propagate at about 4-8 times the speed of mucociliary transport in mammals, whereas in birds they propagate at about the transport speed. The mucociliary transport in birds is fast and roughly follows the TLA, whereas the transport is slower and proceeds along a left-handed spiral in mammals. The longer wavelengths and the lower ratio between the metachronal wave speed and the mucociliary transport speed provide evidence that the mucociliary clearance mechanism operates differently in birds than in mammals.

Multi-scale alignment of respiratory cilia and its relation to mucociliary function.

The tracheobronchial tree is lined by a mucociliary epithelium containing millions of multiciliated cells. Their integrated oscillatory activity continuously propels an overlying pollution-protecting mucus layer in cranial direction, leading to mucociliary clearance - the primary defence mechanism of the airways. Mucociliary transport is commonly thought to co-emerge with the collective ciliary motion pattern under appropriate geometrical and rheological conditions. Proper ciliary alignment is therefore considered essential to establish mucociliary clearance in the respiratory system. Here, we used volume electron microscopy in combination with high-speed reflection contrast microscopy in order to examine ciliary orientation and its spatial organization, as well as to measure the propagation direction of metachronal waves and the direction of mucociliary transport on bovine tracheal epithelia with reference to the tracheal long axis (TLA). Ciliary orientation is measured in terms of the basal body orientation (BBO) and the axonemal orientation (AO), which are commonly considered to coincide, both equivalently indicating the effective stroke as well as the mucociliary transport direction. Our results, however, reveal that only the AO is in line with the mucociliary transport, which was found to run along a left-handed helical trajectory, whereas the BBO was found to be aligned with the TLA. Furthermore, we show that even if ciliary orientation remains consistent between adjacent cells, ciliary orientation exhibits a gradual shift within individual cells. Together with the symplectic beating geometry, this intracellular orientational pattern could provide for the propulsion of highly viscous mucus and likely constitutes a compromise between efficiency and robustness.

A novel technique for laser-assisted revascularization: an in vitro pilot study.

The common limitation of surgical revascularization procedures for severe tissue ischemia due to cardiovascular diseases is the need to interrupt blood flow during the intervention. We aim to introduce a new technique that allows a sutureless, non-occlusive revascularization. A 3-step technique was developed using rabbit's aorta to simulate a side-to-side anastomosis model. It enables the creation of a bypass circuit for revascularization. The first step was the soldering of 2 vessels in a side-to-side fashion based on the laser-assisted vascular anastomosis (LAVA) principle using a diode laser emitting irradiation at 810 nm with an albumin-based solder patch between them, followed by the creation of a channel within the patch using either a holmium-doped yttrium aluminum garnet laser (Ho:YAG) at λ = 2100 nm or a xenon-chloride excimer laser (XeCl) at λ = 308 nm. Thereby, a bypass circuit was created, thus allowing a non-ischemic revascularization. The system was deemed functional when a flow was observed across the anastomosis. The highest average tensile strength recorded after side-to-side LAVA using a diode laser power of 3.2 W for 60 s was 2278.6 ± 800 mN (n = 20). The Ho:YAG laser created the channels with less tension on the anastomosis than the excimer laser. Histological analysis showed limited thermal damage and good patch-tissue adaptation. The preliminary results of this feasibility study outline the foundations for an entirely sutureless laser-assisted revascularization procedure. The next studies will evaluate the rheological parameters across the bypass circuit to optimize the post-anastomotic flow.

Polarimetric imaging in backscattering for the structural characterization of strongly scattering birefringent fibrous media.

Interpreting the polarimetric data from fiber-like macromolecules constitutive of tissue can be difficult due to strong scattering. In this study, we probed the superficial layers of fibrous tissue models (membranes consisting of nanofibers) displaying varying degrees of alignment. To better understand the manifestation of membranes' degree of alignment in polarimetry, we analyzed the spatial variations of the backscattered light's Stokes vectors as a function of the orientation of the probing beam's linear polarization. The degree of linear polarization reflects the uniaxially birefringent behavior of the membranes. The rotational (a-)symmetry of the backscattered light's degree of linear polarization provides a measure of the membranes' degree of alignment.

Threshold of the skull injury for blunt force impacts under free and constraint boundary conditions.

The formation of skull fractures is an important topic in legal medicine. In particular, the influence of boundary conditions is controversially discussed in the literature. A study focusing solely on this aspect was missing. This study aimed to investigate the influence of boundary conditions on the energy threshold for head fractures. Because of the great variability of biological tissue of real skulls, we opted for a head model made from a polyurethane sphere filled with gelatin. Furthermore, we decided to investigate two opposite situations: A fixed configuration where a model was placed on a rigid surface and a (quasi) free boundary configuration where the head model was held at a force of 5 N compensating for gravity. For both configurations, we determined the acceleration signal of the impactor, the force, and the energy threshold for head fracture. It turned out that the fracture forces for both configurations were the same whereas the energy threshold was 11.0 J for the fixed and 13.6 J for the free boundary. The difference seems to be negligible if compared to the effect of varying structural mechanical properties of real human heads. This means that in a forensic case, the two situations most probably cannot be distinguished. To investigate the influence of the impactor mass, we developed a mathematical model and fitted the experimental data. As a result, we found that in the free configuration, a larger mass increases the energy threshold for head fracture. So that in principle, the two configurations are distinguishable.

Influence of a soft tissue layer covering the kidney upon blunt impact.

Blunt abdominal organ injury is an abundant and relevant topic in forensic medicine, yet comparatively few experimental studies have been performed to quantify organ injury threshold parameters. The goal of this study was to relate an impact to a kidney injury determining an energy threshold while taking account of the influence of the overlaying soft tissue thickness. A model consisting of ballistic gelatin with an embedded filled porcine kidney was made such that a gelatin layer of 2 or 4 cm thickness covered the organ. An impactor was dropped on this model from different heights and the resulting organ damage was categorized according to the abbreviated injury scale (AIS). The 50% energy threshold for damage and the 50% energy threshold causing injuries ≥ AIS 3 were determined for the two protecting soft layers to be 22 J and 32 J and 27 J and 36 J, respectively. A finite element model was created to determine the strain energy densities at the depth of the organ's surface for these energies. The strain energy densities for the 50% damage thresholds were 88.9 mJ/cm3 and 86.7 mJ/cm3 for 2 and 4 cm and for the injuries ≥ AIS 3104.2 mJ/cm3 and 98.7 mJ/cm3. For forensic cases, this means that the thickness of the abdominal layers must be taken into account when the severity of an injury is used to draw conclusions about the applied impact strength.

AMICAI: A Method Based on Risk Analysis to Integrate Responsible Research and Innovation into the Work of Research and Innovation Practitioners.

The integration of ethics into the day-to-day work of research and innovation (R&I) is an important but difficult challenge. However, with the Aachen method for identification, classification and risk analysis of innovation-based problems (AMICAI) an approach from an engineering perspective is presented that enables the integration of ethical, legal and social implications into the day-to-day work of R&I practitioners. AMICAI appears in particular capable of providing a procedural guidance for R&I practitioners based on a method established in engineering science, breaking down the object of consideration into partial aspects and prioritizing the innovation-based problems in dependence of potential risk. This enables the user to apply AMICAI continuously during all stages of the research and development (R&D) process and to analyze and choose between certain sociotechnical alternatives. In this way, problems that affect ethical, legal, and social aspects can be understood, reflected and considered in the mostly technically focused R&D process. The paper gives a general guidance about AMICAI by describing principles and assumptions, providing the steps of analysis and application aids, giving an example application, explaining the necessary adjustments of AMICAI compared to the methodical basis of failure mode, effects, and criticality analysis and discussing the advantages and limits. AMICAI's simple applications can stimulate interdisciplinary cooperation in the R&D process and be a starting point for the development of an "open RRI risk analysis platform" allowing society to evaluate innovation-based problems.

Interpretation of backscattering polarimetric images recorded from multiply scattering systems: a study on colloidal suspensions.

Extracting a system's physical features from polarimetric experiments constitutes a challenging task, especially in the presence of multiple scattering. This can be attributed to the difficulty in interpreting the polarimetric measurements. In this study, we demonstrate that polarimetric images recorded in the backscattering geometry can be interpreted by analyzing the spatial variations of the backscattered light's Stokes vectors and using symmetry/geometry arguments. To illustrate the applicability of our method, we examine experimental and simulation data collected by probing colloidal suspensions. We present an analytical model based on the coherency matrix and the geometric phase to describe the polarimetric behavior of the probed samples.

Silica nanoparticle-exposure during neuronal differentiation modulates dopaminergic and cholinergic phenotypes in SH-SY5Y cells.

BACKGROUND: Silica-ε-polycaprolactone-nanoparticles (SiPCL-NPs) represent a promising tool for laser-tissue soldering in the brain. After release of the SiPCL-NPs in the brain, neuronal differentiation might be modulated. The present study was performed to determine effects of SiPCL-NP-exposure at different stages of neuronal differentiation in neuron-like SH-SY5Y cells. The resulting phenotypes were analyzed quantitatively and signaling pathways involved in neuronal differentiation and degeneration were studied. SH-SY5Y cells were differentiated with all-trans retinoic acid or staurosporine to obtain predominantly cholinergic or dopaminergic neurons. The resulting phenotype was analyzed at the end of differentiation with and without the SiPCL-NPs given at various times during differentiation. RESULTS: Exposure to SiPCL-NPs before and during differentiation led to a decreased cell viability of SH-SY5Y cells depending on the differentiation protocol used. SiPCL-NPs co-localized with the neuronal marker ß-3-tubulin but did not alter the morphology of these cells. A significant decrease in the number of tyrosine hydroxylase (TH) immunoreactive neurons was found in staurosporine-differentiated cells when SiPCL-NPs were added at the end of the differentiation. TH-protein expression was also significantly downregulated when SiPCL-NPs were applied in the middle of differentiation. Protein expression of the marker for the dopamine active transporter (DAT) was not affected by SiPCL-NPs. SiPCL-NP-exposure predominantly decreased the expression of the high-affinity choline transporter 1 (CHT1) when the NPs were given before the differentiation. Pathways involved in neuronal differentiation, namely Akt, MAP-K, MAP-2 and the neurodegeneration-related markers ß-catenin and GSK-3ß were not altered by NP-exposure. CONCLUSIONS: The decrease in the number of dopaminergic and cholinergic cells may implicate neuronal dysfunction, but the data do not provide evidence that pathways relevant for differentiation and related to neurodegeneration are impaired.

Phyllotaxis involves auxin drainage through leaf primordia.

The spatial arrangement of leaves and flowers around the stem, known as phyllotaxis, is controlled by an auxin-dependent reiterative mechanism that leads to regular spacing of the organs and thereby to remarkably precise phyllotactic patterns. The mechanism is based on the active cellular transport of the phytohormone auxin by cellular influx and efflux carriers, such as AUX1 and PIN1. Their important role in phyllotaxis is evident from mutant phenotypes, but their exact roles in space and time are difficult to address due to the strong pleiotropic phenotypes of most mutants in phyllotaxis. Models of phyllotaxis invoke the accumulation of auxin at leaf initials and removal of auxin through their developing vascular strand, the midvein. We have developed a precise microsurgical tool to ablate the midvein at high spatial and temporal resolution in order to test its function in leaf formation and phyllotaxis. Using amplified femtosecond laser pulses, we ablated the internal tissues in young leaf primordia of tomato (Solanum lycopersicum) without damaging the overlying L1 and L2 layers. Our results show that ablation of the future midvein leads to a transient accumulation of auxin in the primordia and to an increase in their width. Phyllotaxis was transiently affected after midvein ablations, but readjusted after two plastochrons. These results indicate that the developing midvein is involved in the basipetal transport of auxin through young primordia, which contributes to phyllotactic spacing and stability.

Polypyrrole-Coated Perfluorocarbon Nanoemulsions as a Sono-Photoacoustic Contrast Agent.

A new contrast agent for combined photoacoustic and ultrasound imaging is presented. It has a liquid perfluorocarbon (PFC) core of about 250 nm diameter coated by a 30 nm thin polypyrrole (PPy) doped polymer shell emulsion that represents a broadband absorber covering the visible and near-infrared ranges (peak optical extinction at 1050 nm). When exposed to a sufficiently high intensity optical or acoustic pulse, the droplets vaporize to form microbubbles providing a strong increase in imaging sensitivity and specificity. The threshold for contrast agent activation can further drastically be reduced by up to 2 orders of magnitude if simultaneously exposing them with optical and acoustic pulses. The selection of PFC core liquids with low boiling points (i.e., perfluorohexane (56 °C), perfluoropentane (29 °C), and perfluorobutane (-2 °C)) facilitates activation and reduces the activation threshold of PPy-coated emulsion contrast agents to levels well within clinical safety limits (as low as 0.2 MPa at 1 mJ/cm2). Finally, the potential use of these nanoemulsions as a contrast agent is demonstrated in a series of phantom imaging studies.

INVESTIGATION OF THE TRACHEAL MUCOCILIARY CLEARANCE IN SNAKES WITH AND WITHOUT BOID INCLUSION BODY DISEASE AND LUNG PATHOLOGY.

Pneumonia is a common complication of boid inclusion body disease (BIBD) in snakes. The tracheal mucociliary apparatus of eight boas ( Boa constrictor) and two pythons ( Python regius, Morelia viridis) was examined to assess whether absent or reduced mucociliary clearance could be a predisposing factor. Nine of the examined snakes were positive for BIBD by detection of inclusion bodies and three had lung pathologies other than the formation of inclusion bodies. A considerable individual variation of ciliary beat frequency (CBF, 3.0 ± 0.75 Hz to 7.8 ± 1.27 Hz), transport speed (23.1 ± 12.56 µm/sec to 189.2 ± 41.17 µm/sec), and transport direction (-12.5° ± 11.43° to 36.1° ± 7.53°) was found. CBFs of the BIBD-affected snakes with or without lung pathologies were markedly lower than ranges published for birds or mammals, but the net transport speeds and directions lay well within. The present investigation does therefore not reveal any signs of an inadequate mucociliary clearance in BIBD-affected snakes.

Effects of silica nanoparticle exposure on mitochondrial function during neuronal differentiation.

BACKGROUND: Nanomedicine offers a promising tool for therapies of brain diseases, but potential effects on neuronal health and neuronal differentiation need to be investigated to assess potential risks. The aim of this study was to investigate effects of silica-indocyanine green/poly (ε-caprolactone) nanoparticles (PCL-NPs) engineered for laser tissue soldering in the brain before and during differentiation of SH-SY5Y cells. Considering adaptations in mitochondrial homeostasis during neuronal differentiation, metabolic effects of PCL-NP exposure before and during neuronal differentiation were studied. In addition, kinases of the PI3 kinase (PI3-K/Akt) and the MAP kinase (MAP-K/ERK) pathways related to neuronal differentiation and mitochondrial function were investigated. RESULTS: Differentiation resulted in a decrease in the cellular respiration rate and the extracellular acidification rate (ECAR). PCL-NP exposure impaired mitochondrial function depending on the time of exposure. The cellular respiration rate was significantly reduced compared to differentiated controls when PCL-NPs were given before differentiation. The shift in ECAR was less pronounced in PCL-NP exposure during differentiation. Differentiation and PCL-NP exposure had no effect on expression levels and the enzymatic activity of respiratory chain complexes. The activity of the glycolytic enzyme phosphofructokinase was significantly reduced after differentiation with the effect being more pronounced after PCL-NP exposure before differentiation. The increase in mitochondrial membrane potential observed after differentiation was not found in SH-SY5Y cells exposed to PCL-NPs before differentiation. The cellular adenosine triphosphate (ATP) production significantly dropped during differentiation, and this effect was independent of the PCL-NP exposure. Differentiation and nanoparticle exposure had no effect on superoxide levels at the endpoint of the experiments. A slight decrease in the expression of the neuronal differentiation markers was found after PCL-NP exposure, but no morphological variation was observed. CONCLUSIONS: PCL-NP exposure affects mitochondrial function depending on the time of exposure before and during neuronal differentiation. PCL-NP exposure during differentiation was associated with impaired mitochondrial function, which may affect differentiation. Considering the importance of adaptations in cellular respiration for neuronal differentiation and function, further studies are needed to unravel the underlying mechanisms and consequences to assess the possible risks including neurodegeneration.

Binding of indocyanine green in polycaprolactone fibers using blend electrospinning for in vivo laser-assisted vascular anastomosis.

BACKGROUND AND OBJECTIVE: The clinical application of laser-assisted vascular anastomosis is afflicted by unreliable and low bonding strengths as well as tedious handling during microvascular surgery. The challenge to be met arises from the flow-off of the chromophore during soldering that changes the absorption and stains the surrounding tissue, leading to an uncontrollable thermal damage zone. In this study, we investigated the feasibility to produce an indocyanine green (ICG)-loaded patch by electrospinning and tested its applicability to both in vitro and in vivo microvascular laser soldering. MATERIALS AND METHODS: A blend of polycaprolactone and ICG was electrospun to produce a pliable patch. Prior to soldering, the patch was soaked in 40% wt. bovine serum albumin solution. The solder patch was wrapped in vitro around blood vessel stumps of rabbit aortas. An intraluminal balloon catheter enabled an easy alignment and held the setup in place. The soldering energy was delivered via a diffusor fiber from the vessel lumen using a diode laser at 810 nm. During the procedure, the surface temperature was observed with an infrared camera. Afterward, samples were embedded in methylmethacrylate and epon to study thermal damage. The quality of the fusion was assessed by measuring the tensile strength. After in vitro tests with rabbit aortas, eight large white pigs were subjected to an acute in vivo experiment, and the artery of the latissimus dorsi flap was anastomosed to the distal femoral artery. RESULTS: The ICG-loaded patch, produced by electrospinning, has a thickness of 279 ± 62 µm, a fiber diameter of 1.20 ± 0.19 µm, and an attenuation coefficient of 1,119 ± 183 cm-1 at a wavelength of 790 nm. The patch was pliable and easy to handle during surgery. No leakage of the chromophore was observed. Thermal damage was restricted to the Tunica adventitia and Tunica media and the area of the vessel wall that was covered with the patch. Six pigs were successfully treated, without any bleeding and with a continuous blood flow. The in vivo flap model yielded a similar tensile strength compared to in vitro laser-assisted vascular anastomoses (138 ± 52 vs. 117 ± 30 mN/mm2 ). CONCLUSION: Our study demonstrated the applicability of the ICG-loaded patch for laser-assisted vascular anastomosis. By using electrospinning, ICG could be bound to polymer fibers, avoiding its flow-off and the staining of the surrounding tissue. This patch demonstrated several advantages over liquid solder as it was easier to apply, ensured a high and reliable bonding strength while maintaining a constant concentration of ICG concentration during the surgery. Lasers Surg. Med. 49:928-939, 2017. © 2017 Wiley Periodicals, Inc.

Uptake of silica nanoparticles in the brain and effects on neuronal differentiation using different in vitro models.

Nanomedicine offers a promising tool for therapies of brain diseases, but they may be associated with potential adverse effects. The aim of this study was to investigate the uptake of silica-nanoparticles engineered for laser-tissue soldering in the brain using SH-SY5Y cells, dissociated and organotypic slice cultures from rat hippocampus. Nanoparticles were predominantly taken up by microglial cells in the hippocampal cultures but nanoparticles were also found in differentiated SH-SY5Y cells. The uptake was time- and concentration-dependent in primary hippocampal cells. Transmission electron microscopy experiments demonstrated nanoparticle aggregates and single particles in the cytoplasm. Nanoparticles were found in the endoplasmic reticulum, but not in other cellular compartments. Nanoparticle exposure did not impair cell viability and neuroinflammation in primary hippocampal cultures at all times investigated. Neurite outgrowth was not significantly altered in SH-SY5Y cells, but the neuronal differentiation markers indicated a reduction in neuronal differentiation induction after nanoparticle exposure.

Endoluminal laser-assisted vascular anastomosis-an in vivo study in a pig model.

Microvascular surgery is time consuming and requires high expertise. Laser-assisted vascular anastomosis (LAVA) is a promising sutureless technique that has the potential to facilitate this procedure. In this study, we evaluate the handling of our soldering material and the 1-week patency rate in a porcine model. Six pigs were subjected to LAVA. For each pig, the saphenous artery on one side was transected while the contralateral side was used as control. A porous polycaprolactone scaffold soaked in 40% (w/w) bovine serum albumin solution in combination with 0.1% (w/w) indocyanine green was wrapped at the anastomosis site and at the control site. Both sides were then soldered with a diode laser coupled into a light diffuser fiber emitting radiation with a wavelength of 808 nm and a power of 2-2.2 W. Vessels were successfully soldered with a 100% immediate patency rate. The 1-week patency rate was 83% for the anastomoses versus 67% for the control side. Vessels irradiated for 80 to 90 s tended to maintain the highest patency rate. Macroscopically, there was no difference between the two sides. The patch was easy to handle provided that the environment could be kept dry. This study shows the potential and the limitations of endoluminal LAVA as a one-step procedure without the use of stay sutures. Further studies are needed to improve the soldering material, the long-term patency rate, and standardized irradiation parameters. The long-term effects of laser soldering on the vessel wall remain to be determined.

Evaluation of endocytosis of silica particles used in biodegradable implants in the brain.

Silica nanoparticles embedded in a biodegradable scaffold have been proposed to offer several advantages when used in laser-tissue-soldering of blood vessels in the brain. During degradation, these nanoparticles are likely to be released into the surrounding brain tissue. The aim of this study was to investigate possible cellular uptake mechanism(s) of the two silica nanoparticle types in microglial cells as well as their effect on autophagy and inflammatory cytokines. The nanoparticle uptake was analysed quantitatively using high-content analysis. Nanoparticle incubation did not modulate cytokine secretion and autophagy at any time point investigated. The nanoparticles were taken up by the microglia cells in a time- and particle-dependent manner. The maximal uptake was reached after 4hours and the nanoparticles were found in the endoplasmic reticulum and lysosomes. Macropinocytosis and phagocytosis were predominantly responsible for the uptake, whereas clathrin- and caveolin-independent endocytosis were involved to a minor extent.