Pixelation with concentration-encoded effective photons for quantitative molecular optical sectioning microscopy.

Irreproducibility in molecular optical sectioning microscopy has hindered the transformation of acquired digital images from qualitative descriptions to quantitative data. Although numerous tools, metrics, and phantoms have been developed, accurate quantitative comparisons of data from different microscopy systems with diverse acquisition conditions remains a challenge. Here, we develop a simple tool based on an absolute measurement of bulk fluorophore solutions with related Poisson photon statistics, to overcome this obstacle.

Stratification of fluoride uptake among enamel crystals with age elucidated by atom probe tomography.

Dental enamel is subjected to a lifetime of de- and re-mineralization cycles in the oral environment, the cumulative effects of which cause embrittlement with age. However, the understanding of atomic scale mechanisms of dental enamel aging is still at its infancy, particularly regarding where compositional differences occur in the hydroxyapatite nanocrystals and what underlying mechanisms might be responsible. Here, we use atom probe tomography to compare enamel from a young (22 years old) and a senior (56 years old) adult donor tooth.

Large field-of-view metabolic profiling of murine brain tissue following morphine incubation using label-free multiphoton microscopy.

Background: Although the effects on neural activation and glucose consumption caused by opiates such as morphine are known, the metabolic machinery underlying opioid use and misuse is not fully explored. Multiphoton microscopy (MPM) techniques have been developed for optical imaging at high spatial resolution. Despite the increased use of MPM for neural imaging, the use of intrinsic optical contrast has seen minimal use in neuroscience.

Programmable hyperspectral coherent anti-Stokes Raman scattering microscopy.

Hyperspectral coherent Raman scattering microscopy provides a significant improvement in acquisition time compared to spontaneous Raman scattering yet still suffers from the time required to sweep through individual wavenumbers. To address this, we present the use of a pulse shaper with a 2D spatial light modulator for phase- and amplitude-based shaping of the Stokes beam to create programmable spectrally tailored excitation envelopes. This enables collection of useful spectral information in a more rapid and efficient manner.

High throughput automated characterization of enamel microstructure using synchrotron tomography and optical flow imaging.

The remarkable damage-tolerance of enamel has been attributed to its hierarchical microstructure and the organized bands of decussated rods. A thorough characterization of the microscale rod evolution within the enamel is needed to elucidate this complex structure. While prior efforts in this area have made use of single particle tracking to track a single rod evolution to various degrees of success, such a process can be both computationally and labor intensive, limited to the evolution path of a single rod, and is therefore prone to error from potentially tracking outliers.

Temporally optimized and spectrally shaped hyperspectral coherent anti-Stokes Raman scattering microscopy.

Coherent anti-Stokes Raman scattering (CARS) microscopy offers label-free chemical contrasts based on molecular vibrations. Hyperspectral CARS (HS-CARS) microscopy enables comprehensive microscale chemical characterization of biological samples. Various HS-CARS methods have been developed with individual advantages and disadvantages.

Characterizing the microstructures of mammalian enamel by synchrotron phase contrast microCT.

The enamel of mammalian teeth is a highly mineralized tissue that must endure a lifetime of cyclic contact and is inspiring the development of next-generation engineering materials. Attempts to implement enamel-inspired structures in synthetic materials have had limited success, largely due to the absence of a detailed understanding of its microstructure. The present work used synchrotron phase-contrast microCT imaging to evaluate the three-dimensional microstructure of enamel from four mammals including Lion, Gray Wolf, Snow Leopard, and Black Bear.

Simultaneous label-free autofluorescence multi-harmonic microscopy driven by the supercontinuum generated from a bulk nonlinear crystal.

Nonlinear microscopy encompasses several imaging techniques that leverage laser technology to probe intrinsic molecules of biological specimens. These native molecules produce optical fingerprints that allow nonlinear microscopes to reveal the chemical composition and structure of cells and tissues in a label-free and non-destructive fashion, information that enables a plethora of applications, e.g.

Supercontinuum intrinsic fluorescence imaging heralds free view of living systems.

Optimal imaging strategies remain underdeveloped to maximize information for fluorescence microscopy while minimizing the harm to fragile living systems. Taking hint from the supercontinuum generation in ultrafast laser physics, we generated supercontinuum fluorescence from untreated unlabeled live samples before nonlinear photodamage onset. Our imaging achieved high-content cell phenotyping and tissue histology, identified bovine embryo polarization, quantified aging-related stress across cell types and species, demystified embryogenesis before and after implantation, sensed drug cytotoxicity in real-time, scanned brain area for targeted patching, optimized machine learning to track small moving organisms, induced two-photon phototropism of leaf chloroplasts under two-photon photosynthesis, unraveled microscopic origin of autumn colors, and interrogated intestinal microbiome.

Phase-sensitive detection of anomalous diffusion dynamics in the neuronal membrane induced by ion channel gating.

Non-ergodicity of neuronal dynamics from rapid ion channel gating through the membrane induces membrane displacement statistics that deviate from Brownian motion. The membrane dynamics from ion channel gating were imaged by phase-sensitive optical coherence microscopy. The distribution of optical displacements of the neuronal membrane showed a Lévy-like distribution and the memory effect of the membrane dynamics by the ionic gating was estimated.

Tracking the binding of multi-functional fluorescent tags for Alzheimer's disease using quantitative multiphoton microscopy.

A recent theranostic approach to address Alzheimer's disease (AD) utilizes multifunctional targets that both tag and negate the toxicity of AD biomarkers. These compounds, which emit fluorescence with both an activation and a spectral shift in the presence of Aβ, were previously characterized with traditional fluorescence imaging for binary characterization. However, these multifunctional compounds have broad and dynamic emission spectra that are dependent on factors such as the local environment, presence of Aβ deposits, etc.

Ultra-parallel label-free optophysiology of neural activity.

The electrical activity of neurons has a spatiotemporal footprint that spans three orders of magnitude. Traditional electrophysiology lacks the spatial throughput to image the activity of an entire neural network; besides, labeled optical imaging using voltage-sensitive dyes and tracking Ca ion dynamics lack the versatility and speed to capture fast-spiking activity, respectively. We present a label-free optical imaging technique to image the changes to the optical path length and the local birefringence caused by neural activity, at 4,000 Hz, across a 200 × 200 μm region, and with micron-scale spatial resolution and 300-pm displacement sensitivity using Superfast Polarization-sensitive Off-axis Full-field Optical Coherence Microscopy (SPoOF OCM).

Contributions to enamel durability with aging: An application of data science tools.

Understanding aging of tooth tissues is the first step to developing robust treatments that support lifelong oral health. In this study selected nanomechanical, compositional and structural parameters of human enamel were characterized to assess the effects of aging on its durability in terms of the apparent fracture toughness (K) and brittleness (B). The interdependencies between aging and the enamel properties were assessed using a combination of traditional Pearson's correlation coefficient matrices and self-organizing maps (SOMs) via unsupervised machine learning.

Label-free metabolic and structural profiling of dynamic biological samples using multimodal optical microscopy with sensorless adaptive optics.

Label-free optical microscopy has matured as a noninvasive tool for biological imaging; yet, it is criticized for its lack of specificity, slow acquisition and processing times, and weak and noisy optical signals that lead to inaccuracies in quantification. We introduce FOCALS (Fast Optical Coherence, Autofluorescence Lifetime imaging, and Second harmonic generation) microscopy capable of generating NAD(P)H fluorescence lifetime, second harmonic generation (SHG), and polarization-sensitive optical coherence microscopy (OCM) images simultaneously. Multimodal imaging generates quantitative metabolic and morphological profiles of biological samples in vitro, ex vivo, and in vivo.

Odontoblast apoptosis and intratubular mineralization of sclerotic dentin with aging.

Objectives: The aims of the study were to evaluate the roles of odontoblast apoptosis in the progression of tubular sclerosis of teeth from donors at different ages and assess its correlation to chemical composition and mechanical properties.

Design: Healthy human teeth were obtained and divided into young (age ≤ 25, n = 12) and old (age ≥ 60, n = 12) groups. Odontoblasts were counted with standard hematoxylin and eosin staining.

A machine learning approach to investigate the materials science of enamel aging.

Unlabelled: Understanding aging of tooth tissues is critical to the development of patient-centric oral healthcare. Yet, the traditional methods for analyzing the composition-structure-property relationships of hard tissues have limitations when considering aging and other factors.

Objective: To apply unsupervised machine learning tools to pursue an understanding of relationships between the composition and mechanical behavior of aging enamel.

Mammalian enamel: A universal tissue and diverse source of inspiration.

The natural armors and weapons of the animal kingdom are serving as inspiration in the development of next-generation engineering materials. In this pursuit, seldom considered are the variations in properties across taxa that have evolved to meet their unique functional demands. Here, teeth from six different mammalian species were acquired and categorized according to their bite force quotient (BFQ), which accounts for the allometric scaling between bite force and body size.

High-speed label-free two-photon fluorescence microscopy of metabolic transients during neuronal activity.

The brain is an especially active metabolic system, requiring a large supply of energy following neuronal activation. However, direct observation of cellular metabolic dynamics associated with neuronal activation is challenging with currently available imaging tools. In this study, an optical imaging approach combining imaging of calcium transients and the metabolic co-enzyme nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) is utilized to track the metabolic dynamics in hippocampal neuron cultures.

On the regeneration of fish scales: structure and mechanical behavior.

Fish scales serve as a dermal armor that provides protection from physical injury. Owing to a number of outstanding properties, fish scales are inspiring new concepts for layered engineered materials and next-generation flexible armors. Although past efforts have primarily focused on the structure and mechanical behavior of ontogenetic scales, the structure-property relationships of regenerated scales have received limited attention.

Colombian Physiotherapists' Use of Functional Outcome Measures in Their Practice.

We examined physiotherapists' use of functional outcome measures in their practice to compare the frequency of use of functional outcome measures and impairment-based measures and to explore policies and practices related to the use of functional outcome measures in Colombia. Eligible participants were licensed physiotherapists actively practising in Colombia. They were recruited by means of a survey link sent via email by a continuing education organization to all the physiotherapists in its database and through snowball sampling.