Practical guide for setting up a Fourier light-field microscope.

A practical guide for the easy implementation of a Fourier light-field microscope is reported. The Fourier light-field concept applied to microscopy allows the capture in real time of a series of 2D orthographic images of microscopic thick dynamic samples. Such perspective images contain spatial and angular information of the light-field emitted by the sample. A feature of this technology is the tight requirement of a double optical conjugation relationship, and also the requirement of NA matching. For these reasons, the Fourier light-field microscope being a non-complex optical system, a clear protocol on how to set up the optical elements accurately is needed. In this sense, this guide is aimed to simplify the implementation process, with an optical bench and off-the-shelf components. This will help the widespread use of this recent technology.

Three-dimensional imaging through patterned type-1 microscopy.

We report a scanning non-confocal fluorescence microscopy scheme that provides images with optical sectioning and with a lateral resolution that surpasses by a factor of two the diffraction resolution limit. This technique is based on the type-1 microscopy concept combined with patterned illumination. The method does not require the application of phase-shifting or post-processing algorithms and provides artifact-free superresolved 3D images. We have validated the theory by means of experimental data.

Examining the utility of pinhole-type screens for lightfield display.

The use of microlens arrays for lightfield display has the drawback of providing images with strong chromatic aliasing. To overcome this problem, pinhole-type lightfield monitors are proposed. This paper is devoted to evaluating the capability for such lightfield monitors to offer the user a convincing 3D experience with images with enough brightness and continuous aspect. Thus, we have designed a psychophysical test specifically adapted for lightfield monitors, which allowed us to confirm the usability of pinhole-type monitors.

Resolution improvements in integral microscopy with Fourier plane recording.

Integral microscopes (IMic) have been recently developed in order to capture the spatial and the angular information of 3D microscopic samples with a single exposure. Computational post-processing of this information permits to carry out a 3D reconstruction of the sample. By applying conventional algorithms, both depth and also view reconstructions are possible. However, the main drawback of IMic is that the resolution of the reconstructed images is low and axially heterogeneous. In this paper, we propose a new configuration of the IMic by placing the lens array not at the image plane, but at the pupil (or Fourier) plane of the microscope objective. With this novel system, the spatial resolution is increased by factor 1.4, and the depth of field is substantially enlarged. Our experiments show the feasibility of the proposed method.

Diabetes screening by telecentric digital holographic microscopy.

Diabetes is currently the world's fastest growing chronic disease and it is caused by deficient production of insulin by the endocrine pancreas or by abnormal insulin action in peripheral tissues. This results in persistent hyperglycaemia that over time may produce chronic diabetic complications. Determination of glycated haemoglobin level is currently the gold standard method to evaluate and control sustained hyperglycaemia in diabetic people. This measurement is currently made by high-performance liquid chromatography, which is a complex chemical process that requires the extraction of blood from the antecubital vein. To reduce the complexity of that measurement, we propose a fully-optical technique that is based in the fact that there are changes in the optical properties of erythrocytes due to the presence of glucose-derived adducts in the haemoglobin molecule. To evaluate these changes, we propose to perform quantitative phase maps of erythrocytes by using telecentric digital holographic microscopy. Our experiments show that telecentric digital holographic microscopy allows detecting, almost in real time and from a single drop of blood, significant differences between erythrocytes of diabetic patients and healthy patients. Besides, our phase measurements are well correlated with the values of glycated haemoglobin and the blood glucose values.

Prescription for antiresorptive therapy in Mexican patients with rheumatoid arthritis: is it time to reevaluate the strategies for osteoporosis prevention?

Glucocorticoids are frequently used in rheumatoid arthritis (RA) in order to alleviate symptoms of joint inflammation, retard erosions and to treat extra-articular manifestations, although these drugs may increase the risk of bone mineral loss and osteoporotic fractures. To date, in Mexico there are no studies that identify the frequency of patients with RA with corticosteroids, receiving therapy for osteoporosis. Therefore, we evaluated the prevalence and factors related to the prescription of antiresorptives in 520 Mexican patients with RA. We used a multivariate model to identify variables associated with antiresorptives prescription. We identified that although 79% of patients were under treatment with glucocorticoids, only 13% received antiresorptive agents as preventive therapy for osteoporosis. The multivariate analysis identified that higher proportions of antiresorptive drugs prescriptions were associated with female patients (OR 11.40, 95% CI: 1.5-84.3, P = 0.02), an age of 40 years or more (OR 3.22, 95% CI: 1.3-8.3, P = 0.02) and to consume a lower number of cointerventions with other drugs (OR 1.09, 95% CI: 1.0-1.2, P = 0.03). Corticosteroid treatment was not associated with the prescription of antiresorptives (P = 0.31). In conclusion, a low proportion of Mexicans with RA receive antiresorptive therapy independently regardless of whether they consume or not chronically corticosteroids. Additional strategies should be evaluated to encourage the prevention and early treatment for osteoporosis in patients with RA.

Initial results of endourological treatment of renoureteral lithiasis by means of flexible ureteroscopy and percutaneous surgery in an outpatient procedure in a tertiary care center.

OBJECTIVE: Urinary lithiasis is a prevalent disease with a high socioeconomic impact, where endourological surgery has shown excellent results with minimal complications. For its part, outpatient surgery is an efficient, safe and quality care model. We present our experience in the outpatient endourological treatment of lithiasis and a review of the main series. MATERIAL AND METHODS: Prospective analysis of 85 flexible or percutaneous procedures for the treatment of lithiasis, carried out in our center between January 2021 and April 2022. The main objective was to analyze the rate of unplanned admission and the success and incidence of complications as secondary objectives. The patients were selected following the inclusion criteria of the care process. RESULTS: The mean age was 56 ± 14 years. Urine culture was positive in 13.9% of the patients, 38% had a pre-surgical double-J catheter. Median stone surface was 55 mm 2 (961 ± 323 Hounsfield Units). 73 flexible and 12 percutaneous procedures were performed. 8 patients required immediate unplanned admission and another 2 during the first month. 94% were stone-free at the third month. No intraoperative complications were detected, although 16.5% of the patients presented some type of postoperative complication. CONCLUSION: In our experience, with a strict selection of patients and following a care process with multidisciplinary participation, endourological procedures are feasible and safe in the outpatient setting. Periodic monitoring of the results is essential for the sake of a constant improvement of the process.

High-resolution far-field integral-imaging camera by double snapshot.

In multi-view three-dimensional imaging, to capture the elemental images of distant objects, the use of a field-like lens that projects the reference plane onto the microlens array is necessary. In this case, the spatial resolution of reconstructed images is equal to the spatial density of microlenses in the array. In this paper we report a simple method, based on the realization of double snapshots, to double the 2D pixel density of reconstructed scenes. Experiments are reported to support the proposed approach.

3D integral imaging display by smart pseudoscopic-to-orthoscopic conversion (SPOC).

Previously, we reported a digital technique for formation of real, non-distorted, orthoscopic integral images by direct pickup. However the technique was constrained to the case of symmetric image capture and display systems. Here, we report a more general algorithm which allows the pseudoscopic to orthoscopic transformation with full control over the display parameters so that one can generate a set of synthetic elemental images that suits the characteristics of the Integral-Imaging monitor and permits control over the depth and size of the reconstructed 3D scene.

Optical implementation of micro-zoom arrays for parallel focusing in integral imaging.

We report 3D integral imaging with an electronically tunable-focal-length lens for improved depth of field. The micro-zoom arrays are generated and implemented based on the concept of parallel apodization. To the best of our knowledge, this is the first report of parallel dynamic focusing in integral imaging based on the use of micro-zoom arrays.

Reduction of spherical-aberration impact in microscopy by wavefront coding.

In modern high-NA optical scanning instruments, like scanning microscopes, the refractive-index mismatch between the sample and the immersion medium introduces a significant amount of spherical aberration when imaging deep inside the specimen, spreading out the impulse response. Since such aberration depends on the focalization depth, it is not possible to achieve a static global compensation for the whole 3D sample in scanning microscopy. Therefore a depth-variant impulse response is generated. Consequently, the design of pupil elements that increase the tolerance to this aberration is of great interest. In this paper we report a hybrid technique that provides a focal spot that remains almost invariant in the depth-scanning processing of thick samples. This invariance allows the application of 3D deconvolution techniques to that provide an improved recovery of the specimen structure when imaging thick samples.

Digital slicing of 3D scenes by Fourier filtering of integral images.

We present a novel technique to extract depth information from 3D scenes recorded using an Integral Imaging system. The technique exploits the periodic structure of the recorded integral image to implement a Fourier-domain filtering algorithm. A proper projection of the filtered integral image permits reconstruction of different planes that constitute the 3D scene. The main feature of our method is that the Fourier-domain filtering allows the reduction of out-of-focus information, providing the InI system with real optical sectioning capacity.

Motor changes during sertraline treatment in depressed patients with Parkinson's disease*.

BACKGROUND: Pharmacological interventions to treat depressive symptoms associated with Parkinson's disease (PD) are limited. Whether selective serotonine re-uptake inhibitors increase parkinsonism or have clinically significant interactions with antiparkinsonian drugs is unresolved. PURPOSE: We used a naturalistic approach to prospectively investigate the long-term effects on motor status of adding sertraline in a large sample of community-dwelling PD patients with depressive symptoms. METHODS: Main outcome measure was the motor part of the Unified PD Rating Scale (UPDRS) at baseline and at 1-, 3-, and 6-month follow-up. Secondary measures were the change in antiparkinsonian drugs expressed as total levodopa equivalent dose and the scores of the Hospital Anxiety and Depression Scale (HADS). Of the 374 patients included, 310 (82%) completed the study. RESULTS: Treatment with sertraline (mean dose 66.0 +/- 29.8 mg) resulted in improvement in all UPDRS domains along with a significant decrease of the HADS scores. A modest but significant increase of the total dose of levodopa, without significant change of total levodopa equivalent dose, was observed. Almost 8% of patients discontinued medication for adverse events, mainly related to the gastrointestinal system. CONCLUSIONS: Although worsening of tremor was observed in some patients, active management of depression with sertraline appears to have a positive impact on parkinsonism.

Blood pressure is not associated with haematoma enlargement in acute intracerebral haemorrhage.

BACKGROUND AND PURPOSE: We performed an observational study that compared baseline and subsequent blood pressure (BP) measurements and its association with haematoma enlargement (HE) in patients with intracerebral haemorrhage (ICH). METHODS: We prospectively studied consecutive patients with supratentorial spontaneous ICH within the first 6 h after the onset of symptoms. HE was defined as an increase >or=33% in the volume of haematoma on the CT obtained 24-48 h after the onset of symptoms as compared with the CT at admission. We recorded systolic BP (SBP), diastolic BP (DBP) and mean BP (MBP) at admission and at 6, 12, 18 and 24 h after onset; the maximum SBP, DBP and MBP during the study period; the maximum SBP and DBP within intervals; the mean of all BP readings; administration of antihypertensive agents. RESULTS: We studied 60 patients whose mean age was 72.1 +/- 11.3 years. HE was observed in 27 (45%) patients. No statistically significant differences were observed in any of the analyses that compared BP parameters between the HE and non-HE groups (two-way anova). CONCLUSIONS: In an exploratory analysis, we did not find an association between BP and HE within the first 24 h after an acute ICH.

FIMic: design for ultimate 3D-integral microscopy of in-vivo biological samples.

In this work, Fourier integral microscope (FIMic), an ultimate design of 3D-integral microscopy, is presented. By placing a multiplexing microlens array at the aperture stop of the microscope objective of the host microscope, FIMic shows extended depth of field and enhanced lateral resolution in comparison with regular integral microscopy. As FIMic directly produces a set of orthographic views of the 3D-micrometer-sized sample, it is suitable for real-time imaging. Following regular integral-imaging reconstruction algorithms, a 2.75-fold enhanced depth of field and [Formula: see text]-time better spatial resolution in comparison with conventional integral microscopy is reported. Our claims are supported by theoretical analysis and experimental images of a resolution test target, cotton fibers, and in-vivo 3D-imaging of biological specimens.

Enhanced viewing-angle integral imaging by multiple-axis telecentric relay system.

One of the main limitations of integral imaging is the narrow viewing angle. This drawback comes from the limited field of view of microlenses during the pickup and display. We propose a novel all-optical technique which allows the substantial increase of the field of view of any microlens and therefore of the viewing angle of integral-imaging displays.

Axial gain resolution in optical sectioning fluorescence microscopy by shaded-ring filters.

We present a new family of pupil masks to control the axial component of the intensity distribution in the focal region of tightly focused light fields. The filters, which consist of a circular clear pupil with a single shaded ring, allow to control the width of the central lobe of the axial spot together with the residual sidelobes energy. The filters can be applied to improve the optical sectioning capacity of different scanning microscopes.

Gaussian imaging transformation for the paraxial Debye formulation of the focal region in a low-Fresnel-number optical system

The Debye formulation of focused fields has been systematically used to evaluate, for example, the point-spread function of an optical imaging system. According to this approximation, the focal wave field exhibits some symmetries about the geometrical focus. However, certain discrepancies arise when the Fresnel number, as viewed from focus, is close to unity. In that case, we should use the Kirchhoff formulation to evaluate accurately the three-dimensional amplitude distribution of the field in the focal region. We make some important remarks regarding both diffraction theories. In the end we demonstrate that, in the paraxial regime, given a defocused transverse pattern in the Debye approximation, it is possible to find a similar pattern but magnified and situated at another plane within the Kirchhoff theory. Moreover, we may evaluate this correspondence as the action of a virtual thin lens located at the focal plane and whose focus is situated at the axial point of the aperture plane. As a result, we give a geometrical interpretation of the focal-shift effect and present a brief comment on the problem of the best-focus location.

Optical sectioning by two-pinhole confocal fluorescence microscopy.

A two-pinhole axially superresolving confocal fluorescence imaging system is presented. Based on the concept of subtractive incoherent imaging, the system described here is equipped with a zero-focus complex-transmittance pupil filter in one of the collector paths. The optical sectioning capacity of the system is 25% superior to that of a free-pupil one-pinhole instrument.