Speckle-correlation imaging through a kaleidoscopic multimode fiber.

Speckle-correlation imaging techniques are widely used for noninvasive imaging through complex scattering media. While light propagation through multimode fibers and scattering media share many analogies, reconstructing images through multimode fibers from speckle correlations remains an unsolved challenge. Here, we exploit a kaleidoscopic memory effect emerging in square-core multimode fibers and demonstrate fluorescence imaging with no prior knowledge on the fiber. Experimentally, our approach simply requires to translate random speckle patterns at the input of a square-core fiber and to measure the resulting fluorescence intensity with a bucket detector. The image of the fluorescent object is then reconstructed from the autocorrelation of the measured signal by solving an inverse problem. This strategy does not require the knowledge of the fragile deterministic relation between input and output fields, which makes it promising for the development of flexible minimally invasive endoscopes.

Optical memory effect in square multimode fibers.

We demonstrate experimentally the existence of a translational optical memory effect in square-core multimode fibers. We found that symmetry properties of square-core waveguides lead to speckle patterns shifting along four directions at the fiber output for any given shift direction at the input. A simple theoretical model based on a perfectly reflective square waveguide is introduced to predict and interpret this phenomenon. We report experimental results obtained with 532-nm coherent light propagating through a square-core step-index multimode fiber, demonstrating that this translational memory effect can be observed for shift distances up to typically 10 µm after propagation through several centimeters of fiber.

Single-shot hybrid photoacoustic-fluorescent microendoscopy through a multimode fiber with wavefront shaping.

We present a minimally-invasive endoscope based on a multimode fiber that combines photoacoustic and fluorescence sensing. From the measurement of a transmission matrix during a prior calibration step, a focused spot is produced and raster-scanned over a sample at the distal tip of the fiber by use of a fast spatial light modulator. An ultra-sensitive fiber-optic ultrasound sensor for photoacoustic detection placed next to the fiber is combined with a photodetector to obtain both fluorescence and photoacoustic images with a distal imaging tip no larger than 250 µm. The high signal-to-noise ratio provided by wavefront shaping based focusing and the ultra-sensitive ultrasound sensor enables imaging with a single laser shot per pixel, demonstrating fast two-dimensional hybrid in vitro imaging of red blood cells and fluorescent beads.

Minimally invasive multimode optical fiber microendoscope for deep brain fluorescence imaging.

A major open challenge in neuroscience is the ability to measure and perturb neural activity in vivo from well defined neural sub-populations at cellular resolution anywhere in the brain. However, limitations posed by scattering and absorption prohibit non-invasive multi-photon approaches for deep (>2mm) structures, while gradient refractive index (GRIN) endoscopes are relatively thick and can cause significant damage upon insertion. Here, we present a novel micro-endoscope design to image neural activity at arbitrary depths via an ultra-thin multi-mode optical fiber (MMF) probe that has 5-10X thinner diameter than commercially available micro-endoscopes. We demonstrate micron-scale resolution, multi-spectral and volumetric imaging. In contrast to previous approaches, we show that this method has an improved acquisition speed that is sufficient to capture rapid neuronal dynamics in-vivo in rodents expressing a genetically encoded calcium indicator (GCaMP). Our results emphasize the potential of this technology in neuroscience applications and open up possibilities for cellular resolution imaging in previously unreachable brain regions.

Thermal expansion feedback for wave-front shaping.

Focusing inside scattering media is a challenging task with a variety of applications in biomedicine. State of the art methods mostly require invasive feedback inside or behind the sample, limiting practical use. We present a technique for dynamic control and focusing inside scattering media that combines two powerful methods: optical coherence tomography (OCT) and wave-front shaping (WFS). We use OCT as a non-invasive feedback for WFS optimization of a separate, penetrating laser. Energy absorbed in the sample, creates thermal expansions that are used for the feedback mechanism. By maximizing thermal deformations within a selected focal region, we demonstrate enhanced focusing of light through scattering media beyond the ballistic regime and within the penetration range of OCT.

Single multimode fiber endoscope.

Multimode fibers can guide thousands of modes capable of delivering spatial information. Unfortunately, mode dispersion and coupling have so far prevented their use in endoscopic applications. To address this long-lasting challenge, we present a robust scanning fluorescence endoscope. A spatial light modulator shapes the input excitation wavefront to focus light on the distal tip of the fiber and to rapidly scan the focus over the region of interest. A detector array collects the fluorescence emission propagated back from the sample to the proximal tip of the fiber. We demonstrate that proper selection of the multimode fiber is critical for a robust calibration and for high signal-to-background ratio performance. We compare different types of multimode fibers and experimentally show that a focus created through a graded-index fiber can withstand a few millimeters of fiber distal tip translation. The resulting scanning endoscopic microscope images fluorescent samples over a field of view of 80µm with a resolution of 2µm.

Super-resolution photoacoustic imaging through a scattering wall.

The use of wavefront shaping to compensate for scattering has brought a renewed interest as a potential solution to imaging through scattering walls. A key to the practicality of any imaging through scattering technique is the capability to focus light without direct access behind the scattering wall. Here we address this problem using photoacoustic feedback for wavefront optimization. By combining the spatially non-uniform sensitivity of the ultrasound transducer to the generated photoacoustic waves with an evolutionary competition among optical modes, the speckle field develops a single, high intensity focus significantly smaller than the acoustic focus used for feedback. Notably, this method is not limited by the size of the absorber to form a sub-acoustic optical focus. We demonstrate imaging behind a scattering medium using two different imaging modalities with up to ten times improvement in signal-to-noise ratio and five to six times sub-acoustic resolution.

Analgesic effectiveness of prophylactic therapy and continued therapy with naproxen sodium post simple extraction / Efectividad analgésica post exodoncia simple de la terapia profiláctica y la terapia continuada con naproxeno sódico

To compare the analgesic effectiveness of the prophylactic therapy and continued therapy with naproxen sodium after a simple dental extraction. Material and methods: This prospective randomized, parallel, single blind clinical trial was developed in the Dental Clinic of the Universidad Alas Peruanas in Trujillo (Peru). The patients, who required simple extraction due to dental caries, were randomly distributed into three groups: 30 of them took 550mg naproxen sodium in the preoperative period and then every 12 hours, other 30 took 550mg naproxen sodium in the postoperative period and then every 12 hours, and 30(control group), received 400mg ibuprofen in the postoperative period and then every 8 hours, depending on the established criteria. The procedure was standardized, analgesic effectiveness was assessed by visual analog scale and the presence of adverse drug reactions was evaluated as well. Data were analyzed using ANOVA and Duncan’s test using IBM SPSS 22 with a significance level of 5 percent. Results: Continued therapy with naproxen sodium showed greater analgesic effectiveness after a simple extraction at 1, 8 and 24 hours (p<0.005). Conclusion: Continued therapy with naproxen sodium presented greater effectiveness than prophylactic therapy with naproxen sodium after a simple extraction...

Comparar la efectividad analgésica post exodoncia simple entre la terapia profiláctica y la terapia continuada con naproxeno sódico. Material y métodos: Ensayo clínico, prospectivo aleatorizado, paralelo y simple ciego, se desarrolló en la Clínica Estomatológica de la Universidad Alas Peruanas Filial Trujillo (Perú). Los pacientes, quienes requerían exodoncia simple por caries dental, fueron distribuidos aleatoriamente en tres grupos: 30 recibieron naproxeno sódico 550 mg en el preoperatorio y luego cada 12 horas, 30 recibieron naproxeno sódico de 550 mg en el postoperatorio y luego cada 12 horas y, 30, ibuprofeno (grupo testigo) de 400 mg en el posoperatorio y luego cada 8 horas, según los criterios establecidos. El procedimiento fue estandarizado, evaluándose la eficacia analgésica, mediante la escala visual analógica, y la presencia de reacciones adversas medicamentosas. Los datos fueron analizados mediante el ANOVA y el test de Duncan empleando IBM SPSS Statistics 22. Resultado: La terapia continuada con naproxeno sódico presentó mayor efectividad analgésica post exodoncia simple a las 1, 8 y 24 horas (p<0,005). Conclusión: la terapia continuada con naproxeno sódicopresentó mayor efectividad que la terapia profiláctica con naproxeno sódico post exodoncia simple...

High contrast three-dimensional photoacoustic imaging through scattering media by localized optical fluence enhancement.

We demonstrate enhanced three-dimensional photoacoustic imaging behind a scattering material by increasing the fluence in the ultrasound transducer focus. We enhance the optical intensity using wavefront shaping before the scatterer. The photoacoustic signal induced by an object placed behind the scattering medium serves as feedback to optimize the wavefront, enabling one order of magnitude enhancement of the photoacoustic amplitude. Using the enhanced optical intensity, we scan the object in two-dimensions before post-processing of the data to reconstruct the image. The temporal profile of the photoacoustic signal provides the information used to reconstruct the third dimension.

Real-time resilient focusing through a bending multimode fiber.

Multimode optical fibers are attractive for biomedical and sensing applications because they possess a small cross section and can bend over small radii of curvature. However, mode phase-velocity dispersion and random mode coupling change with bending, temperature, and other perturbations, producing scrambling interference among propagating modes; hence preventing its use for focusing or imaging. To tackle this problem we introduce a system capable of re-focusing light through a multimode fiber in 37ms, one order of magnitude faster than demonstrated in previous reports. As a result, the focus spot can be maintained during significant bending of the fiber, opening numerous opportunities for endoscopic imaging and energy delivery applications. We measure the transmission matrix of the fiber by projecting binary-amplitude computer generated holograms using a digital micro-mirror device controlled by a field programmable gate array. The system shows two orders of magnitude enhancements of the focus spot relative to the background.

Laser speckle contrast imaging with extended depth of field for in-vivo tissue imaging.

This work presents, to our knowledge, the first demonstration of the Laser Speckle Contrast Imaging (LSCI) technique with extended depth of field (DOF). We employ wavefront coding on the detected beam to gain quantitative information on flow speeds through a DOF extended two-fold compared to the traditional system. We characterize the system in-vitro using controlled microfluidic experiments, and apply it in-vivo to imaging the somatosensory cortex of a rat, showing improved ability to image flow in a larger number of vessels simultaneously.

Genetic algorithm optimization for focusing through turbid media in noisy environments.

We introduce genetic algorithms (GA) for wavefront control to focus light through highly scattering media. We theoretically and experimentally compare GAs to existing phase control algorithms and show that GAs are particularly advantageous in low signal-to-noise environments.

High-speed scattering medium characterization with application to focusing light through turbid media.

We introduce a phase-control holographic technique to characterize scattering media with the purpose of focusing light through it. The system generates computer-generated holograms implemented via a deformable mirror device (DMD) based on micro-electro-mechanical technology. The DMD can be updated at high data rates, enabling high speed wavefront measurements using the transmission matrix method. The transmission matrix of a scattering material determines the hologram required for focusing through the scatterer. We demonstrate this technique measuring a transmission matrix with 256 input modes and a single output mode in 33.8 ms and creating a focus with a signal to background ratio of 160. We also demonstrate focusing through a temporally dynamic, strongly scattering sample with short speckle decorrelation times.

Microparticle movements in optical funnels and pods.

Three-dimensional microparticle movements induced by laser beams with a funnel- and tubular pod-like structure, in the neighbourhood of the focal plane of an optical trapping setup, are experimentally studied. The funnel and pod beams constructed as coherent superpositions of helical Laguerre-Gaussian modes are synthesized by a computer generated hologram using a phase-only spatial light modulator. Particle tracking is achieved by in-line holography method which allows an accurate position measurement. It is experimentally demonstrated that the trapped particle follows different trajectories depending on the orbital angular momentum density of the beam. In particular applying the proposed pod beam the particle rotates in opposite directions during its movement in the optical trap. Possible applications of these single-beam traps for volumetric optical particle manipulation are discussed.

Kaposi's sarcoma in renal transplant patients: experience at the Cruces Hospital in Bilbao.

BACKGROUND: Kaposi's sarcoma (KS) in renal transplant recipients (RTRs) probably arises from a complex interplay of multiple factors. OBJECTIVE: In order to analyze the prevalence of KS in patients transplanted at the Cruces Hospital in Bilbao, together with their clinical features, treatment, and etiologic factors, we performed a study using the registry of RTRs in our center. METHODS: The records of 1,230 kidney transplant patients at the Cruces Hospital between 1979 and 1998 were reviewed. Immunosuppressive therapy was reduced once a diagnosis of KS was made. A nested polymerase chain reaction was used to detect human herpesvirus 8 (HHV-8) DNA in the biopsy tissue. The DNA was extracted from fresh tissue (n = 2) or from formalin-fixed, paraffin-embedded specimens (n = 5). RESULTS: Six cases of KS were diagnosed. All patients with cutaneous KS improved with a reduction in immunosuppressive drugs. HHV-8 was detected in 100% (2/2) of the frozen biopsies and 20% (1/5) of the formalin-fixed samples investigated. CONCLUSIONS: Our experience indicates that a continuous state of immunodeficiency is important for the development of KS in RTRs. The association, previously described between HHV-8 and transplant-associated KS, also exists in the studied population.

Ketorolac pharmacokinetics in experimental cirrhosis by bile duct ligation in the rat.

The purpose of the present work was to study the pharmacokinetics of ketorolac, a poorly metabolized drug, in experimental cirrhosis. Cirrhosis was induced by bile duct ligation (BDL) for four weeks in male Wistar rats. Ketorolac was given intravenously (1 mg/kg ) or orally (3.2 mg/kg) to control (sham-operated) and BDL-rats. Determination of ketorolac in plasma was carried out by HPLC and estimation of pharmacokinetic parameters was performed by non-compartmental analysis. Indicators of liver damage and liver fibrosis were significantly increased (p < 0.05) in BDL compared to control rats. Experimental cirrhosis did not induce any significant alteration in intravenous ketorolac pharmacokinetics. Volume of distribution, clearance, AUC and t1/2 were similar in BDL and control animals. Notwithstanding, oral ketorolac bioavailability was significantly altered in BDL rats. AUC and Cmax were reduced, while tmax was prolonged, suggesting that both, the extent and the rate of ketorolac absorption were decreased. Results show that liver cirrhosis may result in significant pharmacokinetic alterations, even for poorly bio-transformed drugs, but that alterations may vary with the route of administration. In conclusion, uncritical generalizations on the effect of liver damage on drug kinetics should be avoided and systematic studies for every drug and every route of administration are thus recommended.

Reacciones adversas a los medicamentos en pacientes pediátrico en dos hospitales del segundo nivel / Adverse drug reactions in pediatric patients from two second level hospital

Para determinar la frecuencia de reacciones adversas a medicamentos en niños hospitalizados, se realizó un estudio observacional de farmacovigilancia en pacientes pediátricos en dos hospitales del segundo nivel ubicados en el Distrito Federal. Se hizo un seguimiento de la estancia hospitalaria de 395 pacientes pediátricos. Para la valoración de las reacciones adversas potenciales, se utilizó el algoritmo de Kramer y colaboradores, que consta de 56 preguntas. Se consideraron con sospecha de reacción adversa a los medicamentos 13 pacientes, 10 de ellos fueron calificados con reacción adversa probable y uno con reacción adversa definitiva. La frecuencia de reacciones adversas en cuatro meses fue de 3 por ciento, lo que es comparable con otros datos publicados en la literatura especializada. Se comenta la conveniencia de incluir este algoritmo en programas de farmacovigilancia de mayor escala, al menos como discernimiento inicial para la aplicación de otras técnicas analíticas de mayor costo.

A utilizaçäo dos "preços hedônicos" na avaliaçäo social de projetos / The use of \"hedonics prices\"in social valuation of projects

Apresenta uma revisäo da literatura sobre a técnica dos "preços hedônicos", uma breve discussäo do marco conceitual no qual se baseia a técnica e uma aplicaçäo empírica desta na avaliaçäo social de projetos. Mostra como o método pode ser usado para avaliar os benefícios associados a um projeto de investimento. Apresenta como exemplo a Prefeitura da cidade de Säo Paulo. Avalia alguns projetos de investimento com importantes impactos ambientais.