Plug-and-play adaptive optics for commercial laser scanning fluorescence microscopes based on an adaptive lens.

In this Letter, we present a solution for simple implementation of adaptive optics in any existing laser scanning fluorescence microscope. Adaptive optics are implemented by the introduction of a multiactuator adaptive lens between the microscope body and the objective lens. Correction is performed with a sensorless method by optimizing the quality of the images presented on screen by the microscope software. We present the results acquired on both a commercial linear excitation confocal microscope and a custom-made multiphoton excitation microscope.

Modal-based phase retrieval using Gaussian radial basis functions.

In this paper, we propose the use of Gaussian radial basis functions (GRBFs) to model the generalized pupil function for phase retrieval. The selection of the GRBF hyper-parameters is analyzed to achieve an increased accuracy of approximation. The performance of the GRBF-based method is compared in a simulation study with another modal-based approach considering extended Nijboer-Zernike (ENZ) polynomials. The almost local character of the GRBFs makes them a much more flexible basis with respect to the pupil geometry. It has been shown that for aberrations containing higher spatial frequencies, the GRBFs outperform ENZ polynomials significantly, even on a circular pupil. Moreover, the flexibility has been demonstrated by considering the phase retrieval problem on an annular pupil.

Nonlinear spline wavefront reconstruction through moment-based Shack-Hartmann sensor measurements.

We propose a spline-based aberration reconstruction method through moment measurements (SABRE-M). The method uses first and second moment information from the focal spots of the SH sensor to reconstruct the wavefront with bivariate simplex B-spline basis functions. The proposed method, since it provides higher order local wavefront estimates with quadratic and cubic basis functions can provide the same accuracy for SH arrays with a reduced number of subapertures and, correspondingly, larger lenses which can be beneficial for application in low light conditions. In numerical experiments the performance of SABRE-M is compared to that of the first moment method SABRE for aberrations of different spatial orders and for different sizes of the SH array. The results show that SABRE-M is superior to SABRE, in particular for the higher order aberrations and that SABRE-M can give equal performance as SABRE on a SH grid of halved sampling.

Abdominal vagus nerve stimulation as a new therapeutic approach to prevent postoperative ileus.

BACKGROUND: Electrical stimulation of the cervical vagus nerve (VNS) prevents postoperative ileus (POI) in mice. As this approach requires an additional cervical procedure, we explored the possibility of peroperative abdominal VNS in mice and human. METHODS: The effect of cervical and abdominal VNS was studied in a murine model of POI and lipopolysaccharide (LPS)-induced sepsis. Postoperative ileus was quantified by assessment of intestinal transit of fluorescent dextran expressed as geometric center (GC). Next, the effect of cervical and abdominal VNS on heart rate was determined in eight Landrace pigs to select the optimal electrode for VNS in human. Finally, the effect of sham or abdominal VNS on LPS-induced cytokine production of whole blood was studied in patients undergoing colorectal surgery. KEY RESULTS: Similar to cervical VNS, abdominal VNS significantly decreased LPS-induced serum tumor necrosis factor-α (TNFα) levels (abdominal VNS: 366±33 pg/mL vs sham: 822±105 pg/mL; P<.01). In line, in a murine model of POI, abdominal VNS significantly improved intestinal transit (GC: sham 5.1±0.2 vs abdominal VNS: 7.8±0.6; P<.01) and reduced intestinal inflammation (abdominal VNS: 35±7 vs sham: 80±8 myeloperoxidase positive cells/field; P<.05). In pigs, heart rate was reduced by cervical VNS but not by abdominal VNS. In humans, abdominal VNS significantly reduced LPS-induced IL8 and IL6 production by whole blood. CONCLUSIONS & INFERENCES: Abdominal VNS is feasible and safe in humans and has anti-inflammatory properties. As abdominal VNS improves POI similar to cervical VNS in mice, our data indicate that peroperative abdominal VNS may represent a novel approach to shorten POI in man.

High speed wavefront sensorless aberration correction in digital micromirror based confocal microscopy.

The quality of fluorescence microscopy images is often impaired by the presence of sample induced optical aberrations. Adaptive optical elements such as deformable mirrors or spatial light modulators can be used to correct aberrations. However, previously reported techniques either require special sample preparation, or time consuming optimization procedures for the correction of static aberrations. This paper reports a technique for optical sectioning fluorescence microscopy capable of correcting dynamic aberrations in any fluorescent sample during the acquisition. This is achieved by implementing adaptive optics in a non conventional confocal microscopy setup, with multiple programmable confocal apertures, in which out of focus light can be separately detected, and used to optimize the correction performance with a sampling frequency an order of magnitude faster than the imaging rate of the system. The paper reports results comparing the correction performances to traditional image optimization algorithms, and demonstrates how the system can compensate for dynamic changes in the aberrations, such as those introduced during a focal stack acquisition though a thick sample.

Preoperative arterial embolization facilitates multivisceral transplantation for portomesenteric thrombosis.

Multivisceral transplantation (MvTx) for diffuse venous portomesenteric thrombosis is a surgically and anesthesiologically challenging procedure, partly because of the risk of massive bleeding during visceral exenteration. Preoperative visceral artery embolization might reduce this risk. In three consecutive MvTx, the celiac trunk (CT) and superior mesenteric artery (SMA) were embolized immediately pretransplant. We analyzed demographics, serum D-lactate, pH, base excess, hemoglobin, blood pressure, transfused packed cell (PC) units, intervention time and outcome. Results are reported as median (range). All recipients were male (43, 22, 47 years old). Portomesenteric thrombosis followed antiphospholipid syndrome, neuroendocrine tumor and liver cirrhosis. A peritransplant D-lactate peak of 6.1 (5.1-7.6) mmol/L, lowest pH of 7.24 (7.18-7.36) and lowest base excess level of -9.5 (-7.6 to -11.5) were observed. Values normalized within 3 h posttransplant. Embolization and exenteration times were 80 (70-90) min and 140 (130-165) min, respectively, during which blood pressure remained stable, lowest hemoglobin was 6.1 (6.1-7.6) g/dL and three (2-4) PC were administered. All procedures were uneventful. Follow-up was 7 (4-9) months. The first patient died 4 months post-MvTx after an intracranial bleeding; the other patients are doing well. Our experience suggests that preoperative embolization of CT and SMA facilitates native organ resection in MvTx.

Snapshot coherence-gated direct wavefront sensing for multi-photon microscopy.

Deep imaging in turbid media such as biological tissue is challenging due to scattering and optical aberrations. Adaptive optics has the potential to compensate the tissue aberrations. We present a wavefront sensing scheme for multi-photon scanning microscopes using the pulsed, near-infrared light reflected back from the sample utilising coherence gating and a confocal pinhole to isolate the light from a layer of interest. By interfering the back-reflected light with a tilted reference beam, we create a fringe pattern with a known spatial carrier frequency in an image of the back-aperture plane of the microscope objective. The wavefront aberrations distort this fringe pattern and thereby imprint themselves at the carrier frequency, which allows us to separate the aberrations in the Fourier domain from low spatial frequency noise. A Fourier analysis of the modulated fringes combined with a virtual Shack-Hartmann sensor for smoothing yields a modal representation of the wavefront suitable for correction. We show results with this method correcting both DM-induced and sample-induced aberrations in rat tail collagen fibres as well as a Hoechst-stained MCF-7 spheroid of cancer cells.

Automated spherical aberration correction in scanning confocal microscopy.

Mismatch between the refractive indexes of immersion media and glass coverslips introduces spherical aberrations in microscopes especially for high numerical aperture objectives. This contribution demonstrates an automated adjustment of the coverslip correction collar in scanning confocal microscopy to compensate for spherical aberrations due to coverslip thickness mismatch. With a motorized coverslip correction collar, the adjustment procedure consists of xz image scans, image processing, correction quality evaluation, the mismatch estimation, and eventually the optimal adjustment of the correction collar. For fast correction with less photodamage, coarse-fine Gaussian fitting algorithms are proposed and evaluated with various specimen for their estimation accuracy. The benefits of the proposed automated correction are demonstrated for various coverslips with biological specimens, showing the optimized resolution of the confocal microscope.

Iterative linear focal-plane wavefront correction.

We propose an efficient approximation to the nonlinear phase diversity (PD) method for wavefront reconstruction and correction from intensity measurements with potential of being used in real-time applications. The new iterative linear phase diversity (ILPD) method assumes that the residual phase aberration is small and makes use of a first-order Taylor expansion of the point spread function (PSF), which allows for arbitrary (large) diversities in order to optimize the phase retrieval. For static disturbances, at each step, the residual phase aberration is estimated based on one defocused image by solving a linear least squares problem, and compensated for with a deformable mirror. Due to the fact that the linear approximation does not have to be updated with each correction step, the computational complexity of the method is reduced to that of a matrix-vector multiplication. The convergence of the ILPD correction steps has been investigated and numerically verified. The comparative study that we make demonstrates the improved performance in computational time with no decrease in accuracy with respect to existing methods that also linearize the PSF.

Predictive control of thermally induced wavefront aberrations.

In this paper we experimentally demonstrate the proof of concept for predictive control of thermally induced wavefront aberrations in optical systems. On the basis of the model of thermally induced wavefront aberrations and using only past wavefront measurements, the proposed adaptive optics controller is able to predict and to compensate the future aberrations. Furthermore, the proposed controller is able to correct wavefront aberrations even when some parameters of the prediction model are unknown. The proposed control strategy can be used in high power optical systems, such as optical lithography machines, where the predictive correction of thermally induced wavefront aberrations is a crucial issue.

High precision wavelength estimation method for integrated optics.

A novel and simple approach to optical wavelength measurement is presented in this paper. The working principle is demonstrated using a tunable waveguide micro ring resonator and single photodiode. The initial calibration is done with a set of known wavelengths and resonator tunings. The combined spectral sensitivity function of the resonator and photodiode at each tuning voltage was modeled by a neural network. For determining the unknown wavelengths, the resonator was tuned with a set of heating voltages and the corresponding photodiode signals were collected. The unknown wavelength was estimated, based on the collected photodiode signals, the calibrated neural networks, and an optimization algorithm. The wavelength estimate method provides a high spectral precision of about 8 pm (5 · 10(-6) at 1550 nm) in the wavelength range between 1549 nm to 1553 nm. A higher precision of 5 pm (3 · 10(-6)) is achieved in the range between 1550.3 nm to 1550.8 nm, which is a factor of five improved compared to a simple lookup of data. The importance of our approach is that it strongly simplifies the optical system and enables optical integration. The approach is also of general importance, because it may be applicable to all wavelength monitoring devices which show an adjustable wavelength response.

An innovative and efficient method to control the shape of push-pull membrane deformable mirror.

We carry out performance characterisation of a commercial push and pull deformable mirror with 48 actuators (Adaptica Srl). We present a detailed description of the system as well as a statistical approach on the identification of the mirror influence function. A new efficient control algorithm to induce the desired wavefront shape is also developed and comparison with other control algorithms present in literature has been made to prove the efficiency of the new approach.

Risk factors for bleeding and clinical implications in patients undergoing liver transplantation.

INTRODUCTION: Advanced liver disease is characterized by prolonged global coagulation tests such as prothrombin time (PT). Using Model of End-stage Liver Disease (MELD) score-based allocation, many current transplant recipients show advanced end-stage liver disease with an elevated international normalized ratio (INR). The relationship between abnormalities in coagulation tests and the risk of bleeding has been recently challenged among liver disease patients. In this study we reassessed risk factors for bleeding and the clinical implications for patients who underwent orthotopic liver transplantation (OLT). METHODS: We studied OLT patients between 2005 and 2011 excluding combined transplantations, retransplantations, or cases due to acute liver failure. We collected prospectively pre-OLT, during OLT, and post-OLT clinical and biochemical data to assess the risk for bleeding using linear regression models. RESULTS: The strongest predictor of overall survival among 286 patients with a mean follow-up of 32 months was the number of blood transfusions (P = .005). The risk factor for bleeding during surgery investigated by multivariate analysis only showed the INR (P < .001) and the presence of ascites (P = .003) to independently correlate with the amount of blood transfusion. Receiver operation characteristics (ROC) analysis performed to determine the risk for massive blood transfusion (more than 6 units) revealed a cut-off value for INR ≥ 1.6. Appreciation of the operative field by the surgeon during the intervention as "wet" versus "dry", amounts of blood transfusion and fresh frozen plasma, and stay in the intensive care unit (ICU) and in the hospital were all significantly different (P < .001) for patients with INR <1.6 versus INR ≥ 1.6. CONCLUSIONS: Bleeding during OLT affects the outcome. The risk is independently influenced by the presence of ascites (probably reflecting the degree portal hypertension) and an INR ≥ 1.6. To improve survival after OLT therapeutic interventions should be further explored to reduce the need for blood transfusions.

Liver transplantation in a patient with an intraabdominally located left ventricular assist device: surgical aspects--case report.

The presence of a cardiac assist device in a liver transplantation candidate should not be considered to be an absolute contraindication to transplantation. In this first case report of liver transplantation in a patient with an intraabdominally located left ventricular assist device, we have described the surgical aspects and discussed the timing of the liver transplantation and the removal of the left ventricular assist device.

E2F1-dependent oncogenic addiction of melanoma cells to MDM2.

One of the defining features of aggressive melanomas is their complexity. Hundreds of mutations and an ever increasing list of changes in the transcriptome and proteome distinguish normal from malignant melanocytic cells. Yet, despite this altered genetic background, a long-known attribute of melanomas is a relatively low rate of mutations in the p53 gene. However, it is unclear whether p53 is maintained in melanoma cells because it is required for their survival, or because it is functionally disabled. More pressing from a translational perspective, is to define whether there is a tumor cell-selective wiring of p53 that offers a window for therapeutic intervention. Here, we provide genetic and pharmacological evidence demonstrating that p53 represents a liability to melanoma cells, which they thwart by assuming an oncogenic dependency on the E3 ligase murine double minute-2 (MDM2). Specifically, we used a combination of RNA interference and two structurally independent small molecule inhibitors of the p53-MDM2 interaction to assess the relative requirement of both proteins for the viability of normal melanocytes and a broad panel of melanoma cell lines. We demonstrated in vitro and in vivo that MDM2 is selectively required to blunt latent pro-senescence signals in melanoma cells. Notably, the outcome of MDM2 inactivation depends not only on the mutational status of p53, but also on its ability to signal to the transcription factor E2F1. These data support MDM2 as a drug target in melanoma cells, and identify E2F1 as a biomarker to consider when stratifying putative candidates for clinical studies of p53-MDM2 inhibitors.

Model-based aberration correction in a closed-loop wavefront-sensor-less adaptive optics system.

In many scientific and medical applications, such as laser systems and microscopes, wavefront-sensor-less (WFSless) adaptive optics (AO) systems are used to improve the laser beam quality or the image resolution by correcting the wavefront aberration in the optical path. The lack of direct wavefront measurement in WFSless AO systems imposes a challenge to achieve efficient aberration correction. This paper presents an aberration correction approach for WFSlss AO systems based on the model of the WFSless AO system and a small number of intensity measurements, where the model is identified from the input-output data of the WFSless AO system by black-box identification. This approach is validated in an experimental setup with 20 static aberrations having Kolmogorov spatial distributions. By correcting N=9 Zernike modes (N is the number of aberration modes), an intensity improvement from 49% of the maximum value to 89% has been achieved in average based on N+5=14 intensity measurements. With the worst initial intensity, an improvement from 17% of the maximum value to 86% has been achieved based on N+4=13 intensity measurements.

Extracting hysteresis from nonlinear measurement of wavefront-sensorless adaptive optics system.

In many scientific and medical applications wavefront-sensorless adaptive optics (AO) systems are used to correct the wavefront aberration by optimizing a certain target parameter, which is nonlinear with respect to the control signal to the deformable mirror (DM). Hysteresis is the most common nonlinearity of DMs, which can be corrected if the information about the hysteresis behavior is present. We report a general approach to extract hysteresis from the nonlinear behavior of the adaptive optical system, with the illustration of a Foucault knife test, where the voltage-intensity relationship consists of both hysteresis and some memoryless nonlinearity. The hysteresis extracted here can be used for modeling and linearization of the AO system.

Therapeutic window for melanoma treatment provided by selective effects of the proteasome on Bcl-2 proteins.

Melanoma cells depend on sustained proteasomal function for survival. However, bortezomib, the first proteasome inhibitor in clinical use, is not sufficient to improve the poor prognosis of metastatic melanoma patients. Since the proteasome is also expressed in all normal cell compartments, it is unclear how to enhance the efficacy of bortezomib without exacerbating secondary toxicities. Here, we present pharmacological and genetic analyses of mechanisms of resistance to proteasome inhibition. We focused on Bcl-2, Bcl-x(L) and Mcl-1 as main antiapoptotic factors associated with melanoma progression. Despite an efficient blockage of the proteasome, bortezomib could not counteract the intrinsically high levels of Bcl-2 and Bcl-x(L) in melanoma cells. Moreover, Mcl-1 was only downregulated at late time points after treatment. Based on these results, a combination treatment including (-)-gossypol, an inhibitor of Mcl-1/Bcl-2/Bcl-x(L), was designed and proven effective in vivo. Using a specific RNA interference approach, the survival of bortezomib-treated melanoma cells was found to rely primarily on Mcl-1, and to a lesser extent on Bcl-x(L) (but not on Bcl-2). Importantly, neither Mcl-1 nor Bcl-x(L) inactivation affected the viability of normal melanocytes. This hierarchical requirement of Bcl-2 family members for the maintenance of normal and malignant cells offers a therapeutic window to overcome melanoma chemoresistance in a tumor cell-selective manner.

Artificial disc replacement with the modular type SB Charité III: 2-year results in 50 prospectively studied patients.

The Modular Type SB Charite disc prosthesis has been developed as a device for artificial disc replacement (ADR) in patients with symptomatic discopathies. Here, we report on our first series of 50 (out of 350) patients, who had a satisfactory clinical result in 70% of cases (2 years' follow-up). Subgroup analysis revealed that patients with an isolated discopathy without previous spinal operations or other pathology at the same or other spinal level benefitted more from the surgery. However, this technique was associated with some problems: a 13% rate of permanent side-effects and/or complications was observed caused by the anterior approach. Four percent were related to poor implantation technique. There were no problems related to the material of the prosthesis. Twelve patients needed re-operation, but this was beneficial in only three of them. In one patient we had to convert to an interbody fusion. We conclude that in patients with severe isolated symptomatic discopathies that are resistant to conservative treatment, a mobile disc prosthesis is worth considering as a real alternative to a spondylodesis. However, accurate patient selection is imperative. With these criteria we were encouraged by our results to continue the implantation of this artificial disc.

Insufficiency fractures, an often unrecognized diagnosis.

Diagnosis of sacral insufficiency fractures is difficult since the onset is mild, and usually discomfort is attributed to degeneration of the lumbar spine. Computed tomography and radionuclide bone scans are helpful in making the diagnosis, as regular X-ray and magnetic resonance imaging usually fail to demonstrate the fracture.