Fiber Tracing Research Articles

Quantitative Analysis of CGRP-IR Afferent Axons in the Mouse Stomach Using Zeiss Arivis Vision4D for Automated Tracing

Gastric nociceptive afferents detect and respond to noxious stimuli by transmitting signals from the stomach to the brain. Calcitonin gene-related peptide (CGRP) is a marker for nociceptive afferents and is crucial to gastric functions, including gastric acid secretion, gut motility, and inflammation. However, the topographical quantitative analysis of CGRP-immunoreactive (CGRP-IR) axons in the whole stomach is challenging due to the large amount of axon innervation in various targets within the tissue. Manual tracing of axons is time-consuming, labor-intensive, and extremely tedious, while currently existing automatic neuron tracing programs often need help with large file sizes or tracing inaccuracies. In this study, we used Zeiss Arivis Vision4D, a novel and sophisticated software with a user-guided machine learning capability, for automated tracing of CGRP-IR axons in flat-mounts of the whole mouse stomach muscular layers and thick serial sections of the antrum-pylorus region (C57BL/6J, male, 2-3 months old, n=7). We utilized a combination of techniques, including the Zeiss M2 Imager for automated scanning, Zen 3.3 (blue edition) for image processing, and Vision4D for stitching the entire stomach flat-mounts and sections, 3D fiber tracing, and density analysis. Our results demonstrated that: 1) Vision4D detected and traced almost all CGRP-IR axons of different gastric targets (blood vessels, muscles, myenteric neurons) in different regions (fundus, corpus, antrum) of the stomach. 2) The x-y-z tracing allowed the visualization of axons in space, portraying its continuous trajectory across layers in the muscular flat mounts (longitudinal muscle, myenteric plexus, circular muscle) and cross sections (muscles, submucosa, mucosa). 3) Vision4D also enabled quantitative morphological and laminar analysis based on target and layer separations. The axon density heatmap generated from the tracing data showed high CGRP-IR axon innervation in the blood vessels. After the removal of blood vessels, dense innervation was seen in the upper fundus and antrum-pylorus followed by corpus, indicating the abundance of CGRP in these regions. 4) Vision4D is a powerful tool in handling large data sizes (hundreds of gigabytes of optical sections in more than 300 image frames per stomach) and outstanding in its capability to track nerve fibers in a highly accurate and time effcient manner. This has paved the way for data batch processing to be accessible, as well as shown that multi-marker tracing of the same tissue sample is attainable. 5) The tracing data will be integrated into a stomach scaffold for a 3D map of CGRP-IR afferent axons. This study represents, for the first time, the automatically traced CGRP-IR axons using whole stomach preparations and highlights the potential of Vision4D in creating axon tracing models in other organs and species. This study is supported by NIH 1 U01 NS113867-01, NIH R15 1R15HL137143-01A1 and Carl ZEISS Company. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

A controlled method for the identification of forensic traces from clandestine grave fill

Deceased human remains are often buried as a forensic countermeasure or method of disposal by homicide perpetrators. Owing to this, the excavation of clandestine grave sites is a task that forensic crime scene teams may only encounter a few times a year. Not all crime scene units have specialised teams for this task, and even those that do, may not have specific protocols for the optimal recovery of forensic traces retained within grave fill as procedures such as sieving require optimisation for the specific soil conditions of the jurisdiction. This study aimed to define the optimal sieving conditions for a sandy environment when searching for minute traces of paint, glass, hair and fibres. Furthermore, this study justifies the practice of retaining grave fill and examining it under controlled laboratory conditions, rather than in-situ adjacent to the grave site. The results demonstrate that using sieve mesh sizes as fine as 0.1 mm can recover up to 82% of the deposited traces and almost all paint, hair and glass traces. The processing of grave fill in the laboratory lead to increased yield of forensic evidence, which on a case-basis may warrant the increased time needed. These findings merit consideration for clandestine grave crime scenes where evidence is scarce or the case is likely to become cold.

Evaluation of the proximate composition, minerals, and heavy metals of brown seaweeds: Sargassum wightii and Sargassum thunbergii collected from the Mandapam coastal regions, Tamil Nadu

A vital renewable resource for the marine environment, seaweed naturally supplies nutrients and has several health benefits. The nutritional properties of seaweed compounds have yet to be well investigated; much research has been done on their chemical and biological makeup. Seaweeds provide an alternate supply of these essential nutrients, including protein, fibre, and necessary and non-essential trace elements. In the present study, two brown seaweeds-Sargassum wightii and Sargassum thunbergii,collected from the Mandapam coastal region of Tamil Nadu, were assessed for their proximate composition, minerals, and heavy metals.The findings on dry weight basis showed that carbohydrates (65.1–67.9%) predominated in the proximal analysis, followed by ash content (12.5–16.3%). On a dry weight basis, the critical trace elements found in seaweeds, such as copper (Cu), zinc (Zn), and iron (Fe), were between 8.14–12.41 ppm, 3.95–4.86 ppm, and 648.92-898.45 ppm, respectively. Both seaweeds have a very high calcium (Ca) concentration, ranging from (14,805.08-16,235.62) ppm. The seaweed species did not contain any measurable levels of dangerous heavy metals such as cadmium (Cd), beryllium (Be), lead (Pb), or mercury (Hg). The results demonstrated how seaweed or marine macroalgae may be helpful for essential nutrient supply.

Fibres in the nasal cavity: A pilot study of the recovery, background, and transfer in smothering scenarios

In cases where the suspected cause of death is smothering, fibre traces recovered from the nasal cavity are hypothesised to refute or support this proposition. In order to carry out such evaluations, an efficient recovery method must first be established. This pilot study tested five different recovery methods on 3D printed models of nasal cavities. Among which, the use of the transparent AccuTrans® polyvinyl Siloxane casts demonstrated the best recovery efficiency with a median of 90% of deposited fibres recovered. The efficacy of this method was then verified on cadavers. Apart from a reliable recovery method, an understanding of the background population of fibres in nasal cavities, as well as the mechanisms of the transfer from the purported smothering textile to the nasal cavity is essential to evaluate the findings in these cases of suspected smothering. Samplings of the nasal cavities of 20 cadavers were thus carried out to gather data on the background population of fibres. Results showed that nasal cavities are not void of fibres, but the quantities are expected to be low, with a mean of 3.8 fibres per cavity recovered. Information on generic fibre class, colour, and length of these background fibres were also obtained with the use of low and high-power microscopy. The frequencies found in this population of fibres closely align with data from other population studies where black cotton was the most common. Finally, transfer experiments using the 3D printed models fitted with a respiratory pump to simulate breathing were carried out, along with testing on live volunteers in-vivo. The results demonstrated a verifiable transfer of fibres into the nasal cavity in smothering scenarios. Textiles of various shedding capacities were used in these tests and the findings suggest an influence of this variable on the quantities of fibres transferred.

Milk fat globule membrane promotes brain development in piglets by enhancing the connection of white matter fiber trace

IntroductionBrain development during infancy is crucial for later health and development. Although Milk Fat Globule Membrane (MFGM) has been demonstrated to enhance brain development, further investigation is needed to determine the optimal dose.MethodsIn this study, 80 piglets aged 2 days were randomly assigned to four groups: Control group, MFGM-L (1.74 g MFGM per 100 g diet), MFGM-M (4.64 g MFGM per 100 g diet), and MFGM-H (6.09 g MFGM per 100 g diet). Daily body weight and milk intake of the piglets were recorded until 31 days postnatal. Learning and memory abilities were evaluated using the spatial T-maze test on day 15. MRI analysis was conducted to assess functional and structural changes in brain tissues. Additionally, mRNA and protein expression of brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NTF-3) in the hippocampus and prefrontal cortex were evaluated.ResultsThe results indicated that the MFGM supplemented diet significantly improved the accuracy of the piglets in the T-maze test, with the MFGM-L group exhibiting the best performance. MRI showed no volumetric differences in the gray and white matter between the groups. However, the fractional anisotropy in the left and right hippocampus of piglets in the MFGM-L group was significantly higher than in the other three groups. Furthermore, there was a strong correlation between the accuracy of the T-maze test and hippocampal fractional anisotropy.DiscussionThe MFGM supplemented diet also increased the expression of BDNF in the cerebral cortex. However, the changes in BDNF were not consistent with the results of the T-maze test. In conclusion, adding 1.74 g MFGM per 100 g diet can significantly improve neonatal piglets’ learning and memory abilities, potentially by enhancing the connection of white matter fiber bundles in the brain.

Improving corneal nerve segmentation using tolerance Dice loss function

AbstractIn vivo confocal microscopy is a technique that allows to acquire images of the corneal layers in a rapid and noninvasive way. Analysis of sub-basal nerve allows obtaining important clinical information regarding the eye and the human body’s health. To obtain that information, it is necessary to correctly identify and trace the nerve fibers. Manual analysis is time-consuming and subjective. Numerous automatic algorithms have been proposed to overcome these problems, but none have been included in clinical practice yet. In this work, we take advantage of deep learning techniques. We present an analysis of the performances obtained through UNet (baseline) to which various architectural solutions have been added to boost performance. The variation of the tracing results is also analyzed according to the use of different loss functions, one of which is introduced here: It considers a tolerance margin (Dice with tolerance). The investigated configurations have been shown to be capable of improving the tracing of corneal nerve fibers. The model with attention modules and atrous-spatial pyramid pooling modules showed the greatest improvement compared to the baseline, increasing in the evaluation score from 86.51 to 90.21%. Furthermore, the proposed loss function further increases the results (achieving 92.44%).

Visualization, modeling and analysis of salmon muscle structure: Based on micro-CT

Seafood analogs using culture cells or plant-based materials are rising for future food supply, but their bionic design is still an issue on finely simulating the multiscale structure and function of fishes. For salmon, we compared the back, belly and tail tissues via micro computed tomography (micro-CT) scanning with optimized tissue contrast and spatial resolution. The optimum staining conditions of salmon muscle tissue for micro-CT was 3.75 % IKI (iodine-potassium iodide) solution for 7 days, and the muscle could be separated well from fat and connective tissue. The results of visualization analysis were correlated with the texture profile analysis. A relatively high magnification (3 µm/pixel) was used with fiber tracing procedure to analyze the connection of muscle fiber bundles surrounded by soft tissue. Single muscle fiber (e.g., diameter 117 µm) was successfully and artificially separated from whole visualized tissue through manual division. Overall, this study showed a novel ultra-high-resolution method based on micro-CT to conduct digital analysis of muscle fascicle architecture, and constructed printable model of bionic animal/plant tissue for food design.

Structural elements promote architectural stripe formation and facilitate ultra-long-range gene regulation at a human disease locus

Enhancer clusters overlapping disease-associated mutations in Pierre Robin sequence (PRS) patients regulate SOX9 expression at genomic distances over 1.25 Mb. We applied optical reconstruction of chromatin architecture (ORCA) imaging to trace 3D locus topology during PRS-enhancer activation. We observed pronounced changes in locus topology between cell types. Subsequent analysis of single-chromatin fiber traces revealed that these ensemble-average differences arise through changes in the frequency of commonly sampled topologies. We further identified two CTCF-bound elements, internal to the SOX9 topologically associating domain, which promote stripe formation, are positioned near the domain's 3D geometric center, and bridge enhancer-promoter contacts in a series of chromatin loops. Ablation of these elements results in diminished SOX9 expression and altered domain-wide contacts. Polymer models with uniform loading across the domain and frequent cohesin collisions recapitulate this multi-loop, centrally clustered geometry. Together, we provide mechanistic insights into architectural stripe formation and gene regulation over ultra-long genomic ranges.

3D printing of short fiber reinforced composites via material extrusion: Fiber breakage

Material extrusion (MEX) is a promising method to manufacture short fiber reinforced composites. However, the dynamic fiber flow process has not been well understood. This paper presents quantitative statistical analysis of the fiber breakage and orientation change during the MEX process and develops a simplified CFD model to understand the experimental phenomena. The PA66 polymer filaments reinforced with 20 wt% chopped carbon fibers, whose average length and diameter are 81 µm and 5.5 µm, are used in this experiment. X-ray μCT scans are used to detect the fibers inside the polymer matrix. Fiber tracing method based on three-dimensional images is used to extract the fibers’ length and orientation information. The results show that nozzle diameter has a great influence on fiber breakage, as a smaller nozzle outlet diameter induces higher shear rates and larger volume fraction of high shear rate regions inside the nozzle. A larger nozzle leads to less fiber breakage and better mechanical properties. When the layer height is set to be 0.15 mm, the average fiber length of the bead fabricated using 1.0 mm nozzle is 73.85 µm, and that of the bead fabricated with 0.4 mm nozzle is only 63.55 µm. The corresponding tensile strength and Young’s modulus of them are 88.0 MPa, 2.53 GPa and 82.5 MPa, 2.36 GPa. The fibers with different lengths have different breakage ratios in different printing stages (extrusion and deposition), and the lengths of the fibers after breakage are mostly 30–50 µm. The orientation of the fibers inside the deposited bead is related to the layer height. A larger layer height leads to better alignment in the nozzle moving direction but lower tensile strength and Young’s modulus due to the higher porosity and less bonding area between layers. When using 1.0 mm nozzle, the average fiber tensors in the nozzle moving direction of the bead fabricated with layer height of 0.10 and 0.15 mm is 0.934, and that of the bead fabricated with layer height above 0.20 mm is about 0.960. The tensile strength and Young’s modulus of the specimens fabricated with layer height of 0.10 mm are 89.3 MPa and 2.67 GPa, while that of the specimens fabricated with layer height of 0.30 mm can only reach 73.4 MPa and 2.08 GPa.

Clinically Based Automated Tracing and Tortuosity Estimation of Corneal Nerve Fibers From Confocal Microscopy Images

The purpose of this study was the development of an algorithm able to automatically trace corneal nerves and to estimate a nerve tortuosity index that is useful in clinical practice. In vivo confocal microscopy is an imaging technique that allows the clinical assessment of corneal and systemic diseases. Many studies have demonstrated a correlation between the tortuosity level of nerve fibers in the subbasal plexus layer and some pathologies. We developed an algorithm that provides fully automatic tracing of nerve fibers. It also includes a new way of dealing with bifurcations, separating the main paths from the secondary ones. Based on this automated tracing, the tortuosity was estimated as the absolute curvature, tortuosity density, and fractal dimension. These metrics were considered first individually and then as a linear combination of 2 or 3 of them. We investigated the capability of the estimated tortuosity to emulate the clinical classification into low, mid, and high tortuosity levels. Furthermore, we investigated its ability to distinguish healthy subjects from pathological subjects. Excellent agreement between manual and automated grouping of tortuosity (96.6% accuracy) was obtained. Moreover, the proposed algorithm could differentiate between healthy and pathological subjects with an accuracy of 77.1% by analyzing each image individually. The accuracy improved to 86.31% by considering 3 images of the same subject simultaneously. The proposed framework provides completely automated analysis of corneal nerve images. The results demonstrate the ability of our method to emulate the clinical classification of tortuosity levels and its potential for identifying healthy and pathological subjects.

Microstructures and electrical conductivity properties of compressed gas diffusion layers using X-ray tomography

Bulk resistance of the gas diffusion layer (GDL) plays an important role in the ohmic loss of proton exchange membrane fuel cells (PEMFCs). This work represents the first direct experimental study and comparison of the bulk resistances during the compression process of commonly used commercial GDLs, carbon paper and carbon felt, from the perspective of the microstructure mechanisms. The in-situ X-ray tomography and a fiber tracing algorithm are used to obtain the microstructure characteristics of compressed GDLs. The through-plane (T-P) and in-plane (I-P) bulk resistances of GDLs are measured by the microelectrode probe measurement method and the four-point probe method, respectively. Then, their resistivities are calculated. For the T-P direction, the arrangement of fibers gradually becomes compact during the compression, arousing the nearly linear increase of fiber contact points. Thus, more and more conductive paths are constructed, inducing a rapid decline of the T-P bulk resistivity. Since the fibers in carbon felt are entangled together, the fibers in the edge areas are arranged loosely at low compression. This uneven distribution of contact points in carbon felt results in much larger T-P bulk resistivity than that of carbon paper at low compressive strain. For carbon paper, binders contribute significantly to the smaller T-P resistivity because they tend to gather at the fiber intersections, which forms more conductive paths with better conductivity. For the I-P direction, the bulk resistivities of GDLs decrease linearly during compression. The nearly horizontal fibers are the key to the I-P bulk resistivity, and both smaller fiber density and higher fiber tortuosity lead to the increase of the I-P bulk resistivity. This study helps to understand the microstructure mechanisms of the bulk resistances of various GDLs during the compression process, which can guide the design and fabrication process of GDLs.

Image Based Measurement of Individual Fiber Lengths for Randomly Oriented Short Fiber Composites

Among a wide range of fiber-reinforced composites, those with randomly oriented short fibers, which are also known as random-chopped fiber-reinforced composites (RaFCs), are the most common composites owing to its ease of manufacturing, flexibility of composite shapes, and good material properties, including light weight and high stiffness. These properties of RaFCs are involved with the lengths and distributions of fibers inside the composites. However, inspecting the fiber lengths and distribution remains a challenging problem, particularly when the lengths and locations of individual fibers need to be distinguished using only X-ray transmission images. The main difficulty arises from the variety of fiber widths and their frequent intersections. To address this problem, this paper proposes a comprehensive software system to localize fibers and measure their lengths. Our system is inspired by a previous work for tracing human hair strands. To adopt the previous method for RaFCs, our system extends classic Gabor filter to explore the locally best parameter sets to suit different fiber shapes. With this adaptive filter, we can extract the locations and orientations of local fibers more robustly for RaFCs. Then individual fibers are traced by solving an initial value problem of an ordinary differential equation. To avoid erroneous tracing which typically occurs at intersections, our method traces only the non-intersecting parts of the fibers initially. After that, we connect the fiber segments using the proximity of their endpoints and the orientations. Through experimental validations on different fiber samples, we demonstrate the stability of the fiber tracing and the robustness of the fiber length calculation. Our system works properly even for X-ray radiographic images of heavily tangled fibers in carbon-fiber-reinforced thermoplastic laminates taken by X-ray Talbot–Lau interferometer.

Application of Capillary Electromigration Methods in the Analysis of Textile Dyes-Review.

Fiber traces are one of (micro)traces that can be found at a crime scene. They are easily transferable and, like other forms of evidence, can provide a link between a suspect and a victim. The main purpose of this review is to present methods developed to examine textile dyes extracted for forensic purposes using different capillary electromigration methods (CEMs). Scientific papers, mainly from the 20th century, provide reliable methods for the separation of water-soluble dyes. However, dyes insoluble in aqueous solutions have been and still are a challenge. Another problem is the sensitivity of the developed methods, which is, in most cases, insufficient for forensic examination of dyes extracted from a single fiber preserved at the crime scene. Although the methodologies already developed and presented in this review have the potential to be applied in a comparative analysis of textile dye traces, there seems to be a lot of work to be conducted. Some ideas on how to resolve these problems are presented and discussed in the article.

Fiber tracing and microstructural characterization among audiovisual integration brain regions in neonates compared with young adults

Audiovisual integration has been related with cognitive-processing and behavioral advantages, as well as with various socio-cognitive disorders. While some studies have identified brain regions instantiating this ability shortly after birth, little is known about the structural pathways connecting them. The goal of the present study was to reconstruct fiber tracts linking AVI regions in the newborn in-vivo brain and assess their adult-likeness by comparing them with analogous fiber tracts of young adults. We performed probabilistic tractography and compared connective probabilities between a sample of term-born neonates (N = 311; the Developing Human Connectome Project (dHCP, http://www.developingconnectome.org) and young adults (N = 311 The Human Connectome Project; https://www.humanconnectome.org/) by means of a classification algorithm. Furthermore, we computed Dice coefficients to assess between-group spatial similarity of the reconstructed fibers and used diffusion metrics to characterize neonates’ AVI brain network in terms of microstructural properties, interhemispheric differences and the association with perinatal covariates and biological sex. Overall, our results indicate that the AVI fiber bundles were successfully reconstructed in a vast majority of neonates, similarly to adults. Connective probability distributional similarities and spatial overlaps of AVI fibers between the two groups differed across the reconstructed fibers. There was a rank-order correspondence of the fibers’ connective strengths across the groups. Additionally, the study revealed patterns of diffusion metrics in line with early white matter developmental trajectories and a developmental advantage for females. Altogether, these findings deliver evidence of meaningful structural connections among AVI regions in the newborn in-vivo brain.

Carbon Fiber Traces in Cracked Surfaces of Mortar Prisms

The traces of carbon fibers along the cracked surfaces of mortar prisms, being 40 mm x 40 mm x 160 mm in size, are studied, assuming that the cracked surfaces in the prisms are the places with the lowest resistance to the stresses they are exposed to. This is to explain why the prisms with 1.0% carbon fibers in volume reveal higher flexural strength than those with 0.5%, 1.5% and 2.0% of fibers. Five distinctive traces of carbon fibers, such as uprootedness, avulsion, separation, overlay and dividedness are observed in the cracked surfaces. As the percentage increases by more than 1.0%, the number of the uprooted fibers reduces, while the numbers of the divided, avulsed and separated fibers increase. The percentage increase induces more fibers to be clustered together and overlap each other to make more divided, avulsed and separated fiber traces. At the same time, the fiber strands are mixed with the mortar to a greater extent. Consequently, the crack surfaces of the prisms with fiber percentages of 1.5% and 2.0% become mostly covered with fiber-laden mortar and cemented fiber clusters. Since the cemented fiber clusters work as air pockets of various volumes and act as the inhomogeneities together with the fiber-laden mortar, the cohesiveness of the mortar is greatly reduced. The deteriorating cohesiveness of the mortar and the increased inhomogeneity cause the reduction in the flexural strength of the prisms in comparison with those with 1.0% carbon fibers.

A Roadmap to Reconstructing Muscle Architecture from CT Data.

Skeletal muscle is responsible for voluntary force generation across animals, and muscle architecture largely determines the parameters of mechanical output. The ability to analyze muscle performance through muscle architecture is thus a key step towards better understanding the ecology and evolution of movements and morphologies. In pennate skeletal muscle, volume, fiber lengths, and attachment angles to force transmitting structures comprise the most relevant parameters of muscle architecture. Measuring these features through tomographic techniques offers an alternative to tedious and destructive dissections, particularly as the availability of tomographic data is rapidly increasing. However, there is a need for streamlined computational methods to access this information efficiently. Here, we establish and compare workflows using partially automated image analysis for fast and accurate estimation of animal muscle architecture. After isolating a target muscle through segmentation, we evaluate freely available and proprietary fiber tracing algorithms to reconstruct muscle fibers. We then present a script using the Blender Python API to estimate attachment angles, fiber lengths, muscle volume, and physiological cross-sectional area. We apply these methods to insect and vertebrate muscle and provide guided workflows. Results from fiber tracing are consistent compared to manual measurements but much less time-consuming. Lastly, we emphasize the capabilities of the open-source three-dimensional software Blender as both a tool for visualization and a scriptable analytic tool to process digitized anatomical data. Across organisms, it is feasible to extract, analyze, and visualize muscle architecture from tomography data by exploiting the spatial features of scans and the geometric properties of muscle fibers. As digital libraries of anatomies continue to grow, the workflows and approach presented here can be part of the open-source future of digital comparative analysis.

Multiple indicators metrological analysis for 5 kinds of tea produced in Yunnan, China

Five kinds of tea, including camphor-scented palace tea, fossil glutinous rice tea, old tree white tea, Brown Mountain ancient tree tea, and pure Banzhang tea, from Yunnan Province, China, were selected as the samples for analysis. The combustion heat, differential thermal-thermogravimetric, fat content, crude fiber content, ash content, and trace element content data of the teas we selected were determined, and quality evaluation and classification were carried out by the stoichiometric method from the perspective of food nutrition. In this paper, according to the combustion heat, differential thermal-thermogravimetric, fat content, crude fiber, ash content, and trace element content data of the teas we selected, systematic multi-index comprehensive evaluation systems were constructed through gray pattern recognition, factor analysis, the entropy method and entropy cluster analysis. The multi-index comprehensive evaluation system established in this study provides a new concept for the quantitative control of the quality of tea, a powerful method for research on the large-scale development and classification of tea and basic support for the selection of raw tea materials and the application of a quantitative control mode for assessing the contributions of multi-index ingredients to tea quality.

Precision Capsular Infarct Modeling to Produce Hand Motor Deficits in Cynomolgus Macaques.

Stroke research in non-human primates (NHPs) with gyrencephalic brains is a critical step in overcoming the translational barrier that limits the development of new pharmaceutical and rehabilitative strategies for stroke. White-matter stroke (WMS) has a unique pathophysiology from gray-matter stroke and is not well understood because of a lack of pertinent animal models. To create a precise capsular infarct model in the cynomolgus macaque, we first used electrical stimulation to map hand movements, followed by viral tracing of the hand motor fibers (hMFs). This enabled us to identify stereotactic targets in the posterior limb of the internal capsule (PLIC). Neural tracing showed that hMFs occupy the full width of the PLIC, owing to overlap with the motor fibers for the leg. Furthermore, the hMFs were distributed in an oblique shape, requiring coronal tilting of the target probe. We used the photothrombotic infarct lesioning technique to precisely destroy the hMFs within the internal capsule. Double-point infarct lesioning that fully compromised the hMFs resulted in persistent hand motor and walking deficits whereas single-point lesioning did not. Minor deviations in targeting failed to produce persistent motor deficits. Accurate stereotactic targeting with thorough involvement of motor fibers is critical for the production of a capsular infarct model with persistent motor deficits. In conclusion, the precision capsular infarct model can be translated to the NHP system to show persistent motor deficits and may be useful to investigate the mechanism of post-stroke recovery as well as to develop new therapeutic strategies for the WMS.

Application of Diffusion Tensor Imaging in Obstructive Nephropathy

Background: Obstructive nephropathy is a common clinical disease. Objectives: To explore the value of diffusion tensor imaging (DTI) in obstructive nephropathy. Materials and Methods: Forty healthy Sprague-Dawley (SD) rats were examined in this study. Thirty-two animals underwent complete obstruction of the left ureter, while eight animals underwent a sham surgery. Magnetic resonance imaging (MRI) was performed before surgery and within different intervals after surgery. Eight rats from the experimental group and two rats from the sham group were used in each interval. Following MRI, the animals were sacrificed and sent for medical examinations. The scanning sequences included positioning, transverse T2-weighted (T2W), coronal, and coronal DTI sequences. Image postprocessing was performed after DTI to measure DTI parameters, including apparent diffusion coefficient (ADC) and fractional anisotropy (FA), and to reconstruct DTI fiber traces. One-way analysis of variance was used to compare the parameters between the cortex and medulla and between different intervals. Results: The fiber tracing showed that the obstructed renal fiber bundles were sparse and disordered. The ADC and FA values of the renal cortex, extrarenal medulla, and inner medulla decreased with prolonged hydrops and were negatively correlated with the expression of alpha-smooth muscle actin (α-SMA) and the renal tubulointerstitial lesion grade (r < 0, P < 0.001). Comparison of the cortex, extrarenal medulla, and inner medulla showed the following trends for the ADC and FA values: cortex > extrarenal medulla > inner medulla and cortex < extrarenal medulla < inner medulla, respectively. Conclusions: DTI in obstructive nephropathy not only can reflect the degree of renal interstitial fibrosis and accurately indicate the renal function, but also can provide information regarding renal blood perfusion, water metabolism, and ultrastructural changes.

ExplantAnalyzer: An advanced automated neurite outgrowth analysis evaluated by means of organotypic auditory neuron explant cultures

BackgroundNeuronal outgrowth assays using organotypic explant cultures are commonly utilized to study neuroregenerative and -protective effects of drugs such as neurotrophins. While this approach offers higher organized tissue compared to single cell cultures and less experimental effort than in-vivo studies, quantitative evaluation of the neuronal network is often time consuming. Thus, we developed ExplantAnlayzer, a time-saving high-throughput evaluation method, yielding numerous metrics to objectively describe neuronal outgrowth. New methodSpiral ganglion explants were cultured in 24-well plates, mechanically fixed in a collagen matrix and immunolabeled against beta-III-tubulin. The explants were imaged using a fluorescent tile-scan microscope and resulting images were stitched. The evaluation was developed as an open-source MATLAB routine and involves several image processing steps, including adaptive thresholding. The neurite network was eventually converted to a graph to track neurites from their terminals back to the explant body. Comparison with existing method(s)We compared ExplantAnlayzer quantitatively and qualitatively to common existing methods, such as Sholl analyses and manual fiber tracing, using representative explant images. ExplantAnlayzer is able to achieve similar and as detailed results as manual tracing while decreasing manual interaction and required time dramatically. ResultsAfter an initial setup phase, the explant images could be batch-processed altogether. Bright bundles as well as faint fibers were reliably detected. Several metrics describing the outgrowth morphology, including total outgrowth, neurite numbers and length estimations, as well as their growth directions, were computed. ConclusionsExplantAnalyzer is a time-saving and objective method for an in-depth evaluation of organotypic explant outgrowth.