Ultrasound propagation characteristics within the bone tissue of miniature ultrasound probes: implications for the spinal navigation of pedicle screw placement.

Background: The accuracy of pedicle screw fixation is crucial for patient safety. Traditional navigation methods based on computed tomography (CT) imaging have several limitations. Therefore, this study aimed to investigate the ultrasonic propagation characteristics of bone tissue and their relationship with CT imaging results, as well as the potential application of ultrasound navigation in pedicle screw fixation. Methods: The study used three bovine spine specimens (BSSs) and five human vertebral allograft bones (HABs) to progressively decrease the thickness of the cancellous bone layer, simulating the process of pedicle screw perforation. Five unfocused miniature ultrasound probes with frequencies of 2.2, 2.5, 3, 12, and 30 MHz were employed for investigating the ultrasonic propagation characteristics of cancellous and cortical bone through ultrasound transmission and backscatter experiments. The CT features of the bone tissue was obtained with the Skyscan 1174 micro-CT scanner (Bruker, Billerica, MA, USA). Results: The experimental results demonstrated that low-frequency (2-3 MHz) ultrasound effectively penetrated the cancellous bone layer up to a depth of approximately 5 mm, with an attenuation coefficient below 10 dB/cm. Conversely, high-frequency (12 MHz) ultrasound exhibited significant signal attenuation in cancellous bone, reaching up to 55.8 dB/cm. The amplitude of the backscattered signal at the cancellous bone interface exhibited a negative correlation with the bone sample thickness (average r=-0.84), meaning that as the thickness of the cancellous bone layer on the cortical bone decreases, the backscattered signal amplitude gradually increases (P<0.05). Upon reaching the cortical bone interface, there was a rapid surge in echo signal amplitude, up to 8 times higher. Meanwhile, the statistical results indicated a significant correlation between the amplitude of the echo signal and the micro-CT scanning results of bone trabecular structure. Conclusions: Theoretically, using multiple ultrasonic probes (≥3) and regions of interest (ROIs) (≥5) has the potential to provide surgeons with early warning signals for pedicle perforation based on three or more successive increases in echo signal amplitude or a sudden substantial increase. The statistical results indicate a significant correlation between the amplitude of the echo signal and the micro-CT scanning results of bone trabeculae, suggesting the potential use of ultrasound as opposed to CT for real-time intraoperative bone navigation.

Quality of Root Canal Filling in Curved Canals Utilizing Warm Vertical Compaction and Two Different Single Cone Techniques: A Three-Dimensional Micro-Computed Tomography Study.

Statement of the Problem: Successful endodontic treatment depends on three-dimensional (3D) root canal filling to prevent the leakage of residual bacteria. Different obturation techniques with different sealers should be compared by employing advanced assessment tools. Purpose: This study compared the obturation quality of warm vertical compaction (WVC) and two different single-cone (SC) techniques using micro-computed tomography (micro-CT). Materials and Method: Thirty-three extracted maxillary molars with mesial root canal curvature of 20‒40º were prepared in vitro with One-Curve files and randomly assigned to three groups (n=11) for root canal obturation with WVC, SC technique with AH Plus sealer (SC-AH), or SC technique with SureSeal bioceramic (BC) sealer (SC-Su). The root canals underwent micro-CT examinations before and after obturation to determine the volume percentages (VPs) of voids and gaps at different distances from the apex (coronal, middle, and apical thirds). Data were analyzed by Kruskal-Wallis and Mann-Whitney U tests. Results: The highest VP of voids and gaps was recorded in the SC-Su group, with no significant difference from other groups (p> 0.05). There were significant differences in VP of gaps at different distances from the apex (p<0.05). The VPs of gaps in the apical third of all the samples were significantly higher than in the coronal and middle thirds. However, the difference in VP of voids was not significant at different distances from the apex (p>0.05). Conclusion: None of the tested techniques could provide a void-free and gap-free filling. The apical third of the canals showed the highest VP of gaps in all obturation techniques.

Exploring the diversity of galls on Artemisia indica induced by Rhopalomyia species through morphological and transcriptome analyses.

Plant galls generated by insects have highly organized structures, providing nutrients and shelter to the insects living within them. Most research on the physiological and molecular mechanisms of gall development has focused on single galls. To understand the diversity of gall development, we examined five galls with different morphologies generated by distinct species of Rhopalomyia (gall midge; Diptera: Cecidomyiidae) on a single host plant of Artemisia indica var. maximowiczii (Asteraceae). Vasculature developed de novo within the galls, indicating active transport of nutrients between galls and the host plant. Each gall had a different pattern of vasculature and lignification, probably due to differences in the site of gall generation and the gall midge species. Transcriptome analysis indicated that photosynthetic and cell wall-related genes were down-regulated in leaf and stem galls, respectively, compared with control leaf and stem tissues, whereas genes involved in floral organ development were up-regulated in all types of galls, indicating that transformation from source to sink organs occurs during gall development. Our results help to understand the diversity of galls on a single herbaceous host plant.

Early signs of osteoarthritis in differing rat osteochondral defects.

Preclinical models of osteochondral defects (OCDs) are fundamental test beds to evaluate treatment modalities before clinical translation. To increase the rigor and reproducibility of translational science for a robust "go or no-go," we evaluated disease progression and pain phenotypes within the whole joint for two OCD rat models with same defect size (1.5 x 0.8 mm) placed either in the trochlea or medial condyle of femur. Remarkably, we only found subtle transitory changes to gaits of rats with trochlear defect without any discernible effect to allodynia. At 8-weeks post-surgery, anatomical evaluations of joint showed early signs of osteoarthritis with EPIC-microCT. For the trochlear defect, cartilage attenuation was increased in trochlear, medial, and lateral compartments of the femur. For condylar defect, increased cartilage attenuation was isolated to the medial condyle of the femur. Further, the medial ossicle showed signs of deterioration as indicated with decreased bone mineral density and increased bone surface area to volume ratio. Thus, OCD in a weight-bearing region of the femur gave rise to more advanced osteoarthritis phenotype within a unilateral joint compartment. Subchondral bone remodeling was evident in both models without any indication of closure of the articular cartilage surface. We conclude that rat OCD, placed in the trochlear or condylar region of the femur, leads to differing severity of osteoarthritis progression. As found herein, repair of the defect with fibrous tissue and subchondral bone is insufficient to alleviate onset of osteoarthritis. Future therapies using rat OCD model should address joint osteoarthritis in addition to repair itself.

Quality of different obturation techniques to fill perforating internal root resorption: a micro-computed tomographic study.

BACKGROUND: This study aimed to assess the quality of various obturation techniques to fill perforation caused by internal root resorption using Micro-computed Tomography. METHODS: Cone-beam computed tomography images of a maxillary central incisor tooth with perforating internal resorptive defect were used to create a 3D printed model of the affected tooth. The replicas were divided into four groups based on the obturation technique used. The techniques included Group 1: a polydimethylsiloxane-based sealer (GuttaFlow-2) with gutta-percha. Group 2: same as Group 1 except for using a pre-mixed Bioceramic-based sealer (NeoSEALER Flo). Group 3: the defect was filled entirely using the NeoSealer Flo Bioceramic-based sealer. Group 4: the samples were obturated using the warm vertical compaction technique with a resin-based sealer (ADSeal). The resin models were then scanned a micro-computed scanner to evaluate the percentage of voids in each group. RESULTS: The results showed that NeoSEALER Flo groups had significantly the highest volume of voids while GuttaFlow-2 and warm vertical compaction groups had the lowest void volume. CONCLUSIONS: GuttaFlow-2 and warm vertical compaction techniques performed best in filling the internal resorptive defect.

Total Flavonoids Isolated from the Leaves of Eucommia ulmoides Augment Peak Bone Mass in Female Rats and Show no Side Effects in Other Organs.

INTRODUCTION: Eucommia ulmoides is a unique monophyletic and tertiary relict in China and is listed as a national second-class precious protected tree species. Eucommia ulmoides, recognized as a traditional Chinese medicine, can tonify the liver and kidneys and strengthen bones and muscles. Modern pharmacological research has proved that Eucommia ulmoides has multiple osteoprotective effects, including prohibiting the occurrence of osteoporosis and arthritis and enhancing the healing of bone fractures and bone defects. AIM: To check its osteotropic effects, which may provide ideas for its potential use for the development of novel drugs to treat osteoporosis, this study evaluated the effect of total flavonoids from Eucommia ulmoides leaves (TFEL) on the acquisition of Peak Bone Mass (PBM) in young female rats. MATERIALS AND METHODS: TFEL was isolated, and its purity was confirmed by using a UV spectrophotometer. TFEL with a purity of 85.09% was administered to 6-week-old female rats by oral gavage at a low (50), mid (100), or high (200 mg/kg/d) dose, and the control group was administrated only with the same volume of water. After 13 weeks of treatment, the rats were sacrificed, and serum, different organs, and limb bones (femurs and tibias) were harvested, and the bone turnover markers, organ index, Bone Mineral Density (BMD), biomechanical property, and microstructure parameters were assayed. Furthermore, molecular targets were screened, and network pharmacology analyses were conducted to reveal the potential mechanisms of action of TFEL. RESULTS: Oral administration of TFEL for 13 weeks decreased the serum level of bone resorption marker TRACP-5b. As revealed by micro-computer tomography analysis, it elevated BMD even at a low dose (50 mg/kg/d) and improved the microstructural parameters, which were also confirmed by H&E histological staining. However, TFEL showed no effects on body weights, organ index, and micromorphology in the uterus. In our network pharmacology study, an intersection analysis screened out 64 shared targets, with quercetin, kaempferol, naringenin, and apigenin regulating the greatest number of targets associated with osteoporosis. Flavonoids in Eucommia ulmoides inhibited the occurrence of osteoporosis potentially through targeting signaling pathways for calcium, VEGF, IL-17, and NF-κB. Furthermore, AKT1, EGFR, PTGS2, VEGFA, and CALM were found to be potentially important target genes for the osteoprotective effects of flavonoids in Eucommia ulmoides. CONCLUSION: The above results suggested that TFEL can be used to elevate the peak bone mass in adolescence in female individuals, which may prevent the occurrence of postmenopausal osteoporosis, and the good safety of TFEL also suggests that it can be used as a food additive for daily life to improve the bone health.

Exploring access cavity through non-carious cervical lesions: Impacts on instrumentation, obturation, and fracture resistance in mandibular incisors.

AIM: To compare the effects of Cervical Access Cavity (CervAC) and Traditional Access Cavity (TradAC) on root canal preparation, root canal filling, and fracture resistance in mandibular incisors. METHODOLOGY: Twenty recently extracted and intact mandibular incisors were initially scanned using a micro-CT device. The specimens were anatomically matched to create two groups (n = 10). A wedge-shaped non-carious cervical lesion (NCCL) was created on the buccal aspect of all teeth using a double-faced segmented diamond disc. In group 1, a TradAC was prepared, whilst in group 2, access was created through the simulated NCCL using a round diamond bur 1012. After root canal preparation with Rotate instruments sizes 15/0.04, 20/0.04, and 25/0.04, the teeth were scanned again and evaluated for root canal volume and surface area, static voxels, volume of removed dental tissue, and dentine thickness. After that, the root canals were filled using the single-cone technique, teeth were restored with composite resin, and subsequently rescanned to calculate the volume of filling materials and voids. Then, the restored teeth were subjected to fracture resistance tests using a universal testing machine. Statistical comparisons between groups were performed with the Mann-Whitney test or the Student's t-test, with a statistical significance level of 5%. RESULTS: Statistical comparisons indicated no significant differences between groups in terms of root canal volume, surface area, static voxels, removed root dentine, root canal filling volume, percentage of voids, or fracture resistance load (p > .05). Conversely, teeth prepared with TradAC showed a significantly higher percentage of dental tissue removed from the crown (p = .001) and a greater volume of filling material remnants in the pulp chamber (p < .001) compared to the CervAC group. A significantly lower percentage reduction in dentine thickness was observed only on the mesial aspect of root at Level 1 in TradAC group (p = .008). CONCLUSIONS: CervAC can be considered a viable alternative approach in the presence of NCCL in mandibular incisors.

2D vs. 3D Evaluation of Osteocyte Lacunae - Methodological Approaches, Recommended Parameters, and Challenges: A Narrative Review by the European Calcified Tissue Society (ECTS).

PURPOSE OF REVIEW: Quantification of the morphology of osteocyte lacunae has become a powerful tool to investigate bone metabolism, pathologies and aging. This review will provide a brief overview of 2D and 3D imaging methods for the determination of lacunar shape, orientation, density, and volume. Deviations between 2D-based and 3D-based lacunar volume estimations are often not sufficiently addressed and may give rise to contradictory findings. Thus, the systematic error arising from 2D-based estimations of lacunar volume will be discussed, and an alternative calculation proposed. Further, standardized morphological parameters and best practices for sampling and segmentation are suggested. RECENT FINDINGS: We quantified the errors in reported estimation methods of lacunar volume based on 2D cross-sections, which increase with variations in lacunar orientation and histological cutting plane. The estimations of lacunar volume based on common practice in 2D imaging methods resulted in an underestimation of lacunar volume of up to 85% compared to actual lacunar volume in an artificial dataset. For a representative estimation of lacunar size and morphology based on 2D images, at least 400 lacunae should be assessed per sample.

High resolution imaging of human development: shedding light on contrast agents.

BACKGROUND: Visualizing (micro)vascular structures remains challenging for researchers and clinicians due to limitations in traditional radiological imaging methods. Exploring the role of vascular development in craniofacial malformations in experimental settings can enhance understanding of these processes, with the effectiveness of high-resolution imaging techniques being crucial for successful research in this field. Micro-CT imaging offers 3D microstructural insights, but requires contrast-enhancing staining agents (CESAs) for visualizing (micro)-vascular tissues, known as contrast-enhanced micro-CT (CECT). As effective contrast agents are crucial for optimal visualization, this review focuses on comparative studies investigating such agents for micro-vascular tissue imaging using micro-CT. Furthermore, we demonstrate the utilization of B-Lugol solution as a promising contrast agent for acquiring high-quality micro-CT images of (micro)vascular structures in human embryonic samples. METHOD: This scoping review followed Preferred Reporting Items for Systematic Reviews and Meta-analysis Protocols. PubMed database provided relevant articles, screened initially by title and abstract. Inclusion and exclusion criteria defined outcomes of interest. RESULTS: From an initial search, 273 records were identified, narrowed down to 9 articles after applying our criteria. Additionally, two articles were added through citation searching. This, a total of 11 articles were incorporated in this study. CONCLUSION: This micro-CT contrast agent review underscores the need for tailored choices based on research goals. Both Barium sulfate and Iodine-based agents showing excellent results, providing high resolution (micro) vascular content, especially in ex-vivo specimens. However, careful consideration of protocols and tissue characteristics remains imperative for optimizing the effectiveness of micro-CT imaging for the study of cranio-facial vascular development.

Comparative osteology of the skull of cowbirds (Icteridae: Molothrus).

Detailed osteological descriptions of the craniomandibular complex of passerine birds are lacking for most species, limiting our understanding of their diversity and evolution. Cowbirds (genus Molothrus) are a small but widespread group of New World nine-primaried songbirds, well-known for their unique brooding parasitic behavior. However, detailed osteological data for cowbirds and other Icteridae are currently scarce and several features of their skulls remain undescribed or poorly known. To address this issue, a detailed comparative osteology of cowbird skulls is presented here for the first time based on data from x-ray microcomputed tomography, dry skeletal data, and multivariate analyses of linear morphometric data. Cowbird skulls offer some functional insights, with many finch-like features probably related to a seed-rich diet that distinguishes them from most other icterids. In addition, features previously overlooked in earlier studies might provide valuable phylogenetic information at different levels of passerine phylogeny (Passerida, Emberizoidea, Icteridae, and Agelaiinae), including some of the otic region and nasal septum. Comparisons among cowbirds show that there is substantial cranial variation within the genus, with M. oryzivorus being the most divergent cowbird species. Within the genus, distantly related species share similar overall skull morphology and proportions, but detailed osteological data allow species identification even in cases of strong convergence. Further efforts are warranted to furnish baseline data for future studies of this iconic group of Neotropical birds and to fully integrate it into phylogenetic comparative frameworks.

Predicting ecology and hearing sensitivities in Parapontoporia-An extinct long-snouted dolphin.

Analyses of the cetacean (whale and dolphin) inner ear provide glimpses into the ecology and evolution of extinct and extant groups. The paleoecology of the long-snouted odontocete (toothed whale) group, Parapontoporia, is primarily marine with its depositional context also suggesting freshwater tolerance. As an extinct relative of the exclusively riverine Lipotes vexillifer, Parapontoporia provides insight into a transition from marine to freshwater environments. High-resolution X-ray CT scans (~3 microns or less) of three individual specimens from two species, P. sternbergi and P. pacifica, were acquired. Digital endocasts of the inner ear labyrinths were extracted non-destructively. Nine measurements of the inner ear were compared with an existing dataset covering 125 terrestrial and aquatic artiodactyls. These measurements were then subjected to a principal component analysis to interpret hearing sensitivities among other artiodactyls. Based on our analyses, Parapontoporia was likely to have been able to hear within narrow-band high frequency (NBHF) ranges. This finding indicates another convergence of NBHF-style hearing, or, more intriguingly, suggests that it may be an ancestral characteristic present among the longirostrine dolphins that dominated in the Miocene prior to the evolution of more modern lineages.

Effect of Thermal Shock Conditions on the Low-Cycle Fatigue Performance of 3D-Printed Materials: Acrylonitrile Butadiene Styrene, Acrylonitrile-Styrene-Acrylate, High-Impact Polystyrene, and Poly(lactic acid).

3D printing technology is becoming a widely adopted alternative to traditional polymer manufacturing methods. The most important advantage of 3D printing over traditional manufacturing methods, such as injection molding or extrusion, is the short time from the creation of a new design to the finished product. Nevertheless, 3D-printed parts generally have lower strength and lower durability compared to the same parts manufactured using traditional methods. Resistance to the environmental conditions in which a 3D-printed part operates is important to its durability. One of the most important factors that reduces durability and degrades the mechanical properties of 3D-printed parts is temperature, especially rapid temperature changes. In the case of inhomogeneous internal geometry and heterogeneous material properties, rapid temperature changes can have a significant impact on the degradation of 3D-printed parts. This degradation is more severe in high-humidity environments. Under these complex service conditions, information on the strength and fatigue behavior of 3D-printed polymers is limited. In this study, we evaluated the effects of high humidity and temperature changes on the durability and strength properties of 3D-printed parts. Samples made of commonly available materials such as ABS (Acrylonitrile Butadiene Styrene), ASA (Acrylonitrile-Styrene-Acrylate), HIPS (High-Impact Polystyrene), and PLA (Poly(lactic acid)) were subjected to temperature cycling, from an ambient temperature to -20 °C, and then were heated to 70 °C. After thermal treatment, the samples were subjected to cyclic loading to determine changes in their fatigue life relative to non-thermally treated reference samples. The results of cyclic testing showed a decrease in durability for samples made of ASA and HIPS. The ABS material proved to be resistant to the environmental effects of shocks, while the PLA material exhibited an increase in durability. Changes in the internal structure and porosity of the specimens under temperature changes were also evaluated using microcomputed tomography (microCT). Temperature changes also affected the porosity of the samples, which varied depending on the material used.

Study on the Occurrence Characteristics of the Remaining Oil in Sandstone Reservoirs with Different Permeability after Polymer Flooding.

After polymer flooding, the heterogeneity between different layers intensifies, forming intricate seepage channels and fluid diversions, which results in decreased circulation efficiency and lower recovery rates, leaving a significant amount of residual oil trapped within the reservoir. Understanding the characteristics of residual oil occurrence is crucial for enhancing oil recovery post-polymer flooding. This study focused on sandstone reservoirs with varying permeability in the Saertu block of the Daqing oilfield. Using cryosectioning and laser scanning confocal microscopy, the occurrence characteristics of the residual oil in these sandstone reservoirs post-polymer flooding were investigated. Additionally, micro-CT and scanning electron microscopy were employed to analyze the impact of the pore structure on the distribution characteristics of the residual oil. The results indicate that laser scanning confocal images reveal that post-polymer flooding, the residual oil in high- and low-permeability sandstone reservoirs predominantly exists in a bound state (average > 47%), mostly as particle-adsorbed oil. In contrast, the residual oil in medium-permeability reservoirs is primarily in a free state (average > 49%), mostly as intergranular-adsorbed oil. In high-permeability sandstone reservoirs, heavy oil components are mainly in a particle-adsorbed form; in medium-permeability sandstone reservoirs, residual oil predominantly consists of heavy components, with most light components occurring in a clustered form; in low-permeability sandstone reservoirs, clustered residual oil exists in a balanced coexistence of light and heavy components, while the heavy components primarily exist in a particle-adsorbed form. Post-polymer flooding, the large pore-throat structure in high-permeability sandstone reservoirs results in effective displacement and less free residual oil; medium-permeability sandstone reservoirs, with medium-large pores and throats, have preferential channels and fine particles blocking the throats, leading to some unswept pores and more free residual oil; low-permeability sandstone reservoirs, with small pores and throats, exhibit weak displacement forces and poor mobility, resulting in more bound residual oil. The distribution and content of clay particles and clay minerals, along with the complex microscopic pore structure, are the main factors causing the differences in the residual oil occurrence states in sandstones with varying permeability.

Celebrating 50-years: the history and future of the International Society of Bone Morphometry.

The International Society of Bone Morphometry (ISBM) is dedicated to advancing research, education, and clinical practice for osteoporosis and other bone disorders by developing and improving tools for the quantitative imaging and analysis of bone. Its initial core mission was to promote the proper use of morphometric techniques in bone research and to educate and train clinicians and basic scientists in bone morphometry. This article chronicles the evolution of the ISBM and the history and development of bone morphometric techniques for the past 50-years, starting with workshops on bone morphometry in 1973, to the formal incorporation of the ISBM in 1996, to today. We also provide a framework and vision for the coming decades. This effort was led by ISBM presidents Dr Erica L. Scheller (2022-2024) and Dr Thomas J. Wronski (2009-2012) in collaboration with all other living ISBM presidents. Though the underlying techniques and questions have changed over time, the need for standardization of established tools and discovery of novel approaches for bone morphometry remains a constant. The ISBM fulfills this need by providing a forum for the exchange of ideas, with a philosophy that encourages the open discussion of pitfalls and challenges among clinicians, scientists, and industry partners. This facilitates the rapid development and adaptation of tools to meet emerging demands within the field of bone health at a high level.

Comparative Evaluation of Volume and Homogeneity of Obturation with Four Different Obturation Systems Using Micro-Computed Tomography: An In vitro Study.

Aim: To evaluate and compare volume and homogeneity of the three different root canal obturation systems. Materials and Methods: Single-rooted premolar (n = 24) teeth samples were selected, and crowns were removed for standardization. Four groups are divided randomly as (n = 6), namely: For group I (single-cone gutta-percha obturation), group II (Beefill 2 in 1 obturation), group III (GuttaCore obturation), group IV (GuttaFlow bioseal obturation) and the root canal were subjected to prepare till X3 (protaper next) and subjected to micro-CT imaging. After completion of obturation, the image was taken by using micro-CT imaging. This is to evaluate the volume of filled obturation material in the canal space and the voided area sections, viz. the apical, middle, coronal, and third sections. Results: Group III (GuttaCore obturation) showed the least significant mean of the difference in relation to the volume of the canal obturation (81.148). The least mean significant difference in area of voids in the canal region for apical (0.00133), middle (0.00233), and coronal thirds (0.00533). The most statistically significant difference is in the apical and middle thirds root canal space. Conclusion: All the experimental groups showed significant differences in volume and voids in the obturation at three different levels, and the GuttaCore obturation systems occupied more of the volume with less voids in the prepared root canal space.

The Hox code responsible for the patterning of the anterior vertebrae in zebrafish.

The vertebral column is a characteristic structure of vertebrates. Genetic studies in mice have shown that Hox-mediated patterning plays a key role in specifying discrete anatomical regions of the vertebral column. Expression pattern analyses in several vertebrate embryos have provided correlative evidence that the anterior boundaries of Hox expression coincide with distinct anatomical vertebrae. However, because functional analyses have been limited to mice, it remains unclear which Hox genes actually function in vertebral patterning in other vertebrates. In this study, various zebrafish Hox mutants were generated for loss-of-function phenotypic analysis to functionally decipher the Hox code responsible for the zebrafish anterior vertebrae between the occipital and thoracic vertebrae. We found that Hox genes in HoxB- and HoxC-related clusters participate in regulating the morphology of the zebrafish anterior vertebrae. In addition, medaka hoxc6a was found to be responsible for anterior vertebral identity, as in zebrafish. Based on phenotypic similarities with Hoxc6 knockout mice, our results suggest that the Hox patterning system, including at least Hoxc6, may have been functionally established in the vertebral patterning of the common ancestor of ray-finned and lobe-finned fishes.

Is the mouse nose a miniature version of a rat nose? A computational comparative study.

BACKGROUND AND OBJECTIVE: Although the mouse is a widely used animal model in biomedical research, there are few published studies on its nasal aerodynamics, potentially due to its small size. It is not appropriate to assume that mice and rats' nasal structure and airflow characteristics are the same because the ratio of nasal surface area to nasal volume and body weight is much higher in a mouse than in a rat. The aim of this work is to use anatomically accurate image-based computational fluid dynamic modeling to quantitatively reveal the characteristics of mouse nasal airflow and mass transport that haven't been detailed before and find key differences to that of rat nose, which will deepen our understanding of the mouse's physiological functions. METHODS: We created an anatomically accurate 3D computational nasal model of a B6 mouse using postmortem high-resolution micro-CT scans and simulated the airflow distribution and odor transport patterns under restful breathing conditions. The deposition pattern of airborne particles was also simulated and validated against experimental data. In addition, we calculated the gas chromatograph efficiency of odor transport in the mouse employing the theoretical plate concept and compared it with previous studies involving cat and rat models. RESULTS: Similar to the published rat model, respiratory and olfactory flow regimes are clearly separated in the mouse nasal cavity. A high-speed dorsal medial (DM) stream was observed, which enhances the delivery speed and efficiency of odor to the ethmoid (olfactory) recess (ER). The DM stream split into axial and secondary paths in the ER. However, the secondary flow in the mouse is less extensive than in the rat. The gas chromatograph efficiency calculations suggest that the rat may possess a moderately higher odorant transport efficiency than that of the mouse due to its more complex ethmoid recess structure and extensive secondary flow. However, the mouse's nasal structure seems to adapt better to varying airflow velocity. CONCLUSIONS: Due to the inherent structural disparities, the rat and mouse models exhibit moderate differences in airflow and mass transport patterns, potentially impacting their olfaction and other behavioral habits.

Technologies to Study Genetics and Molecular Pathways.

Over the last few decades, the study of congenital heart disease (CHD) has benefited from various model systems and the development of molecular biological techniques enabling the analysis of single gene as well as global effects. In this chapter, we first describe different models including CHD patients and their families, animal models ranging from invertebrates to mammals, and various cell culture systems. Moreover, techniques to experimentally manipulate these models are discussed. Second, we introduce cardiac phenotyping technologies comprising the analysis of mouse and cell culture models, live imaging of cardiogenesis, and histological methods for fixed hearts. Finally, the most important and latest molecular biotechniques are described. These include genotyping technologies, different applications of next-generation sequencing, and the analysis of transcriptome, epigenome, proteome, and metabolome. In summary, the models and technologies presented in this chapter are essential to study the function and development of the heart and to understand the molecular pathways underlying CHD.

[Application of micro-computed tomography (µCT)in quantifying xylem vessels of broadleaved trees]. / 计算机显微断层扫描技术(µCT)åœ¨é‡åŒ–é˜”å¶æ ‘ç§å¯¼ç®¡ä¸­çš„åº”ç”¨.

Quantitative analysis of vessel characteristics at the cellular scale is of great significance for understan-ding plant adaptation strategies to environment. The direct grinding combined with stereo-microscope imaging is one of the main approaches to examine the anatomical structure of xylem (conifer tracheid and hardwood vessel) wood structure, which inevitably damages xylem cells, hindering the accurate understanding of anatomical structures. In this study, we applied X-ray micro-computed tomography (µCT) and stereo-microscope technology to quantitatively measure the diameter and area of vessels of seven Canadian broadleaved tree species (Acer saccharum, Betula papyrifera, Fraxinus americana, Ostrya virginiana, Populus grandidentata, Quercus rubra, and Carya cordiformis). We fitted the results by linear model and tested the feasibility of µCT technology in quantifying the vessel size of broadleaved species. We found that the results of the two methods for measuring vessel size were highly similar (R2=0.98). The goodness of fit of the vessel diameter results measured by the two methods for the ring-porous wood species (C. cordiformis, R2=0.98; F. americana, R2=0.96; Q. rubra, R2=0.99) was higher than that of the diffuse-porous wood species (B. papyrifera, R2=0.88; O. virginiana, R2=0.73; A. saccharum, R2=0.68; P. grandiden-tata, R2=0.88). The goodness of fit of small vessels (diameter≤200 µm, R2=0.94) measured by the two methods was higher than that of large vessels (diameter>200 µm, R2=0.92). Thus, the µCT technique provided a new non-destructive detection method for quantifying xylem vessels of broadleaved tree species.