Epaxial Research Articles

Percutaneous Ultrasound Guided Celiac Plexus Approach: Results in a Pig Cadaveric Model

Celiac plexus (CP) block (CPB) and neurolysis (CPN) are interventional techniques employed in human analgesia to control visceral pain originating from the upper abdomen. Visceral pain is common in animals and its treatment is challenging. A percutaneous ultrasound (US)-guided approach to the CP has been reported in people but not in veterinary species. The objective of this study is to describe a US-guided percutaneous approach to the CP in a porcine cadaveric model. Cadavers were positioned in right lateral recumbency. The vertebral body of the last thoracic vertebra (T15) was identified (in transverse view) with a left cranial abdominal US scan. Under US guidance, an 18 G Tuohy needle was inserted parallel and ventral to the transverse process of T15. The transducer was gently slid and tilted to have an in-plane view while introducing the needle through the epaxial muscle layer. Once the T15 body was contacted, the needle was advanced towards the ventral surface of the vertebra, and if loss of resistance was present, 2 mL of dye (China Ink) was injected. A laparotomy was performed, and the dyed tissue dissected for histological preparation from 14 cadavers. In all samples submitted for histological study, tissue belonging to the CP was found. The percutaneous ultrasound-guided approach to the CP was effective in localizing the CP in all subjects. Future studies are warranted to identify the clinical utility of this technique in veterinary species.

Axial muscle‐fibre orientations in larval zebrafish

AbstractMost teleost fish propel themselves with lateral body waves powered by their axial muscles. These muscles also power suction feeding through rapid expansion of the mouth cavity. They consist of muscle segments (myomeres), separated by connective tissue sheets (myosepts). In adult teleosts, the fast axial muscle fibres follow pseudo‐helical trajectories, which are thought to distribute strain (relative fibre length change) approximately evenly across transverse sections during swimming, thereby optimizing power generation. To achieve strain equalization, a significant angle to the longitudinal axis on the frontal plane (azimuth) is necessary near the medial plane, increasing strain. Additionally, a deviation from longitudinal orientation on the sagittal plane (elevation) is required laterally to decrease strain. Despite several detailed morphological studies, our understanding of muscle‐fibre orientations in the entire axial musculature of fish remains incomplete. Furthermore, most research has been done in post‐larval stages, leaving a knowledge gap regarding the changing axial muscle architecture during larval development. Larval fish exhibit different body size, body shape and swimming kinematics compared to adults. They experience relatively high viscous forces, requiring higher tail‐beat amplitudes to overcome increased drag. Additionally, larval fish swim with higher tail‐beat frequencies. Histological studies have shown that in larval fish, muscle fibres in the anal region transition from an almost longitudinal orientation to a pseudo‐helical pattern by 3 dpf (days post‐fertilization). However, these studies were limited to a few sections of the body and were prone to shrinkage and tissue damage. Here, we introduce a novel methodology for quantifying muscle‐fibre orientations along the entire axial muscles. We selected 4 dpf larval zebrafish for our analyses, a stage where larvae are actively swimming but not yet free‐feeding. High‐resolution confocal 3D scans were obtained from four genetically modified zebrafish expressing green fluorescent protein in fast muscle fibres. Fluorescence variation allowed segmentation of individual muscle fibres, which were then converted to fish‐bound coordinates by correcting for the fish's position and orientation in the scan, and normalized to pool results across individuals. We show that at 4 dpf, muscle‐fibre trajectories exhibit a helical pattern tapering towards the tail. Average fibre angles decrease from anterior to posterior, with azimuth varying over the dorsoventral axis and elevation varying over the mediolateral axis. Notably, only the anteriormost 20% of the body displayed higher azimuth angles near the medial plane. Angles between neighbouring fibres were substantial, particularly at the rim of the epaxial and hypaxial muscles. The revealed muscle‐fibre architecture at this age presumably contributes to the swimming performance of these larvae, but that swimming performance is probably not the only driving factor for the fibre pattern. Our methodology offers a promising avenue for exploring muscle‐fibre orientations across ontogenetic series and provides a foundation for in‐depth functional studies on the role of muscle architecture in facilitating swimming performance of larval fish.

Muscle Proteins, Technological Properties, and Free Amino Acids of Epaxial Muscle Collected from Asian Seabass (Lates calcarifer) at Different Postmortem Durations

The aim of this study was to compare the changes in the epaxial muscle proteins of Asian seabass at two different postmortem durations. The epaxial muscles of Asian seabass were collected 1 h or 24 h postmortem (PM). Whole, ungutted fish were stored in an ice box, with the ice refilled every two hours. The results show significant increases in the MFI values and the contents of solubilized sarcoplasmic proteins, with a molecular weight of proteins of 47 kDa in the 24 h PM samples (p < 0.05). Myofibrillar and alkaline-soluble proteins in the epaxial muscle remained intact 24 h postmortem. Compared with the 1 h PM samples, the 24 h PM meat exhibited lower degrees of expressible water and hardness (p < 0.05), indicating superior water-holding capacity and meat tenderness. However, no differences in springiness or cohesiveness of the cooked meat were observed. Free L-glutamic acid, known as an umami-tasting amino acid, was significantly increased upon the extension of postmortem duration, and its level was above the taste threshold concentration. Overall, the findings indicated that the 24 h PM epaxial muscle of Asian seabass exhibited superior technological properties, along with higher contents of taste-related amino acids.

Cadaveric study of the ultrasound-guided inter-transversospinalis plane block in dogs for the cervical epaxial musculature region.

Blockage of the dorsal rami of the spinal nerves (DRSN) provides analgesia to the epaxial musculature area in dogs. However, techniques to block the DRSN at the cervical level in dogs haven't yet been investigated. This study aimed to study the anatomy of the cervical area, and to describe a new ultrasound (US)-guided inter-transversospinalis plane (ITP) block technique at the 5th cervical vertebrae (C5). Fourteen adult canine's cadavers were used in this blinded, cadaveric, experimental study. One cadaver for cryo-section, one for anatomical research and twelve to do an ITP injection using 0.3 mL/kg (HV) or 0.15 mL/kg (LV) of dye/contrast solution in each lateral at C5, followed by a computed tomography and anatomical dissection.The HV and LV groups stained a median (range) of 4.67 (3-6) and 3.67 (2-5) DRSN into the ITP, respectively (P<0.017). Stained DRSN in the splenius plane were found in nine (75%) HV and five (41.66%) LV injections, respectively. Spread in the epidural space was found in two dogs using LV. One of them was injected into the ITP (4.33 %) while the other one was done accidentally outside of this plane. The paravertebral spread was found in one injection of each group. There was no dye of the ventral rami of the spinal nerves. The US-guided ITP injection is feasible in dog cadavers. The LV injected just after the medial surface of the semispinalis capitis muscle is recommended to avoid a possible extensive epidural spread.

Investigating the etiology of ocular changes in Monodactylus argenteus housed in a shoaling ring exhibit.

To evaluate the pathologic ocular changes in a population of aquarium-housed Monodactylus argenteus and investigate potential underlying causes for the large number of affected fish in this exhibit. 11 Monodactylus argenteus were evaluated from a shoaling ring exhibit within an aquarium, and 19 control fish without ocular abnormalities were obtained from commercial fish suppliers. Physical and ocular examinations were performed antemortem. Postmortem samples of liver, heart, dorsal epaxial muscle, and lenses of affected and control fish were analyzed for amino acid profiles. The aqueous humor from affected and control fish was collected postmortem, and osmolality was analyzed. Tissues from affected and control fish were submitted for histopathology. Ocular abnormalities in affected fish included corneal lesions, cataracts, lens capsule rupture, and unilateral left-sided lens luxation and buphthalmos. Lens luxation and buphthalmos were directly correlated. Aqueous humor osmolality in control fish differed significantly compared to affected fish but was not correlated to lens abnormality score. Affected fish had significantly lower lens concentrations of arginine, asparagine, glycine, isoleucine, serine, and tyrosine than control fish. One affected fish had severe buphthalmos, cataracts, and panophthalmitis caused by gram-positive cocci. Cataracts and traumatic lesions were common in affected M argenteus. Dietary amino acid content and aqueous humor osmolality imbalances were not likely a cause of the cataracts. Differences in lens amino acid concentrations between affected and control fish may be related to cataract formation. Consideration of species-appropriate tank parameters may mitigate ocular lesions including cataracts in aquarium fish.

Clinical, histopathological and phylogenetic analysis of Myxobolus lentisturalis (Myxozoa: Myxobolidae) infecting the musculature of farmed population of goldfish (Carassius auratus) in Iran: 2021–2022

There is a claimed increase in the global prevalence and incidence of emerging diseases observed in many organisms. Myxozoa represents an essential group of metazoan parasites that hold both economic and ecological significance. In the current study, 1% of the fish population at two commercial goldfish (Carassius auratus) farms in Tehran and Ghom province, Iran, developed cavitating muscular lesions resembling humps in February 2021 and January 2022. Fish displaying pathological abnormalities were transported to the Ornamental Fish Clinic and subjected to clinical examination. Light microscopy was subsequently used to examine wet smears of skin and gills, as well as whitish exudate. In addition, tissue homogenates were collected for more precise identification and molecular confirmation. The study discovered that individuals from the goldfish farms were infected with the pathogenic myxozoan Myxobolus lentisuturalis, which caused significant damage to the epaxial muscles. The spores collected from the humps had a lack of uniformity and were primarily ellipsoidal in shape. Histopathological analysis also revealed parasites in various stages of development, such as plasmodia and spores, as well as inflammatory cell infiltration (macrophage, giant cell and lymphoplasmacytic infiltration) between skeletal muscle fibers. Phylogenetic analysis of M. lentisuturalis was performed by using MEGA 11 and the maximum likelihood method. M. lentisuturalis is a myxozoan parasite that has been sparsely recorded and lacks widespread recognition. The current study is the first clinical, histopathological, and molecular characterization of M. lentisuturalis isolated from the skeletal musculature of goldfish (C. auratus) in Iran.

Influence of surgical intervention at the level of the dorsal spinous processes on the biomechanics of the equine thoracolumbar spine.

Surgical treatment options for horses with overriding dorsal spinous processes include interspinous ligament desmotomy and partial spinous process ostectomy. The impact of spinal surgery on the three-dimensional biomechanics of the equine thoracolumbar spine and the epaxial musculature is unclear. To investigate the influence of interspinous ligament desmotomy and cranial wedge ostectomy on the biomechanics of the equine thoracolumbar spine and the paraspinal Musculi multifidi. Ex-vivo experiments. Twelve equine thoracolumbar spine specimens were mounted in a custom-made mechanical test rig. Based on computed tomographic imaging, distances between dorsal spinous processes and the spinal range of motion (lateral bending, axial rotation, flexion, extension) were compared before and after desmotomy and cranial wedge ostectomy performed at two or five surgical sites. Anatomical dissection was subsequently conducted to document surgical trauma to the Musculi multifidi following desmotomy. The distance between spinous processes in neutral position did not increase significantly after desmotomy (median preoperative = 7.2 mm, interquartile range [IQR] = 3.6 mm; median postoperative = 7.4 mm, IQR = 3.7 mm; p = 0.09), but increased significantly after ostectomy (median preoperative = 8.8 mm, IQR = 4.2 mm; median postoperative = 13 mm, IQR = 6.1 mm; p < 0.001). Both surgical procedures significantly increased the rotational spinal range of motion (p = 0.001), particularly at the level T14/T15 (median preoperative = 6.4°, IQR = 3.2°; median postoperative = 8.2°, IQR = 3.5°; increase = 28.1%; p = 0.02). Musculi multifidi injury was evident at all desmotomy sites. Ex-vivo study with limited sample size. Neither interspinous ligament desmotomy nor cranial wedge ostectomy resulted in an increased range of motion during flexion, extension or lateral bending but both procedures influenced the rotational component of the equine thoracolumbar spinal mobility.

Thoracolumbar hydrated nucleus pulposus extrusion and intervertebral disc extrusion in dogs: Comparison of clinical presentation and magnetic resonance imaging findings

Thoracolumbar hydrated nucleus pulposus extrusion (TL-HNPE) is an increasingly recognised pathology with a substantial lack of literature describing its features. The aim of this retrospective case-control study was to analyse the clinical and magnetic resonance imaging (MRI) features of dogs with TL-HNPE compared to dogs affected with thoracolumbar intervertebral disc extrusion (TL-IVDE). Data from dogs diagnosed with TL-HNPE and TL-IVDE via MRI at two referral hospitals, were retrospectively collected and compared in terms of clinical signs and MRI features. Cases diagnosed with TL-IVDE were deemed controls. The MRI features of the affected IVD space, herniated IVD material, affected overlying spinal cord and local epaxial musculature were evaluated for each group. Fifty-one cases with TL-HNPE and 105 randomly selected cases of TL-IVDE were included. Several signalment and neurological signs were identified as statistically distinct between groups in univariate analysis. Multivariate analysis identified that dogs affected with TL-HNPE were typically older, less likely to be chondrodystrophic (62.2 % vs. 91 %), more frequently experiencing a peracute onset (90.2 % vs. 61.9 %) often attributed to a suspected trauma linked with exercise (37.3 % vs. 10.5 %), being less frequently progressive (41.2 % vs. 86.5 %) and with herniated disc material less frequently lateralised (72.6 % vs. 89.5 %) than cases with TL-IVDE. MRI-identifiable intervertebral disc degeneration was found in every TL-IVDE case but only in 60 % of TL-HNPE cases. TL-HNPEs were associated to significantly less spinal cord compression and less hyperalgesia than TL-IVDE.

Evaluation of muscle mass and intramuscular fatty infiltration in dogs with hypercortisolism and their association with prognosis.

Muscle atrophy and intramuscular fatty infiltration, as well as their association with prognosis, have not been quantified in dogs with spontaneous hypercortisolism (HC). To quantitatively evaluate muscle atrophy and IM fatty infiltration in dogs with HC and determine their prognostic impact. Fifty-three dogs with HC and 66 control dogs without HC. Retrospective cohort study. Medical records and computed tomography images obtained between 2014 and 2021 were evaluated. Kaplan-Meier curves and log-rank tests were used to analyze the effect of muscle atrophy and IM fatty infiltration on the prognosis of dogs with HC. Dogs with HC showed lower visually measured cross-sectional area (VCSA) and cross-sectional area based on attenuation (HCSA) than control dogs (median [interquartile range {IQR}]: 50.3 mm2/mm [36.2-67.8] vs 66.7 mm2/mm [48.0-85.9]; P < .001; 30.4 mm2/mm [13.7-57.2] vs 54.8 mm2/mm [39.7-71.5]; P < .001, respectively). Dogs with HC had lower epaxial muscle attenuation (L3HU) than control dogs (median [IQR]: 21.2 Hounsfield [HU] [12.4-28.2] vs 33.2 HU [22.6-43.6]; P < .001). Dogs with HC with lower HCSA or L3HU had shorter survival (median [IQR]: 670 days [222-673] vs 949 days [788-1074], P < .01; 523 days [132-670] vs 949 days [756-1074], P < .01, respectively) but not lower VCSA (median [IQR]: 673 days [132-788] vs 949 days [523 to not applicable]; P = .30). Hypercortisolism in dogs causes muscle atrophy and IM fatty infiltration and is associated with poor prognosis.

Pathologic classification of a late-onset peripheral neuropathy in a spontaneous Labrador retriever dog model.

Late-onset peripheral neuropathy (LPN) is a heritable canine neuropathy commonly found in Labrador retrievers and is characterized by laryngeal paralysis and pelvic limb paresis. Our objective was to establish canine LPN as a model for human hereditary peripheral neuropathy by classifying it as either an axonopathy or myelinopathy and evaluating length-dependent degeneration. We conducted a motor nerve conduction study of the sciatic and ulnar nerves, electromyography (EMG) of appendicular and epaxial musculature, and histologic analysis of sciatic and recurrent laryngeal nerves in LPN-affected and control dogs. LPN-affected dogs exhibited significant decreases in compound muscle action potential (CMAP) amplitude, CMAP area, and pelvic limb latencies. However, no differences were found in motor nerve conduction velocity, residual latencies, or CMAP duration. Distal limb musculature showed greater EMG changes in LPN-affected dogs. Histologically, LPN-affected dogs exhibited a reduction in the number of large-diameter axons, especially in distal nerve regions. In conclusion, LPN in Labrador retrievers is a common, spontaneous, length-dependent peripheral axonopathy that is a novel animal model of age-related peripheral neuropathy that could be used for fundamental research and clinical trials.

Neurological manifestations in dogs with acute leukemia.

Canine acute leukemia is a rare hematopoietic neoplasm. Neurological abnormalities have been frequently reported in dogs with acute leukemia (AL). However, the description of the presentation and findings are limited. This study aimed to describe the clinical findings in dogs with acute leukemia presenting with neurological signs as their primary complaint. The database of a private referral hospital was searched for cases that presented to the neurological department with neurological deficits and were subsequently diagnosed with acute leukemia. Six cases were included; all had neurological clinical signs and an abnormal neurological examination. All cases had a focal neuroanatomical localisation on neurological examination (brain n = 4; spinal = 2). Out of the four dogs with a complete magnetic resonance imaging (MRI) study, there was an ill-defined infiltrative pattern with abnormal signal intensity in the central nervous system (CNS) in three dogs and the loss of grey and white matter differentiation in the brain (n = 2) and/or spinal cord (n = 2). Other MRI findings included abnormal meningeal enhancement (n = 3), changes affecting spinal nerves and epaxial muscles (n = 2), and lymphadenopathy in the field of view (n = 2). The bone marrow assessment on MRI showed evidence of signal change (n = 3), characterized by a loss of normal fat opacity and an abnormal degree of contrast enhancement. The cerebrospinal fluid (CSF) analysis of the four dogs showed an increased protein level with non-specific pleocytosis and without evidence of malignant cells. Treatment with cytotoxic medication was implemented in two dogs. The dogs diagnosed with acute leukemia had focal neuroanatomical localisation, an infiltrative CNS pattern, and bone marrow remodulation on MRI with an increase in CSF protein and negative cytology analysis.

Effects of elastic therapeutic tape on thoracolumbar epaxial muscle pain in horses

ObjectivesTo evaluate the ability of elastic therapeutic tape to modulate nociception in horses with naturally occurring thoracolumbar epaxial muscle pain. AnimalsTwenty-two horses with naturally occurring thoracolumbar epaxial muscle pain. ProceduresA randomized crossover design study was used to evaluate the efficacy of elastic therapeutic tape compared to control tape application to modulate pain in the thoracolumbar region. Mechanical nociceptive thresholds (MNT) were assessed using a pressure algometer immediately prior to and following tape removal and sequentially at 24 and 48 h after tape removal. ResultsMechanical nociceptive threshold values were significantly (P < 2e-16) different following both elastic therapeutic tape and control tape application at all sites across all time points compared to baseline values. The percent difference in MNT values for the elastic therapeutic tape application ranged from a 15–26 % difference from baseline across the time points at all sites. The percentage difference in MNT values for the control tape application ranged from (-)4–8 % from baseline across the time points at all sites. Clinical relevanceThe outcomes of this study demonstrate that the application of an elastic therapeutic tape at 30 % tension significantly modulates thoracolumbar pain in horses.

A dose characterization study evaluating the pharmacodynamics and safety of a concentrated alfaxalone solution (4%) as an intramuscular sedative in dogs.

Alfaxalone is a commonly employed veterinary anaesthetic induction and sedation agent. A 4% w/v preserved, aqueous formulation of alfaxalone 'RD0387' (A4%) has recently been developed. To evaluate the sedative effects of A4%, three doses, 5 mg kg-1 (A5); 7.5 mg kg-1 (A7.5) and 10 mg kg-1 (A10) were administered intramuscularly into the epaxial musculature of six healthy adult mixed-breed dogs in an experimental, randomized, blinded, crossover study. Sedation time variables, quality of sedation (including onset of sedation and recovery), physiological variables, response to cephalic vein catheterization and frequency of undesirable events were recorded. Continuous variables were analysed between treatments (one-way ANOVA or restricted maximum likelihood modelling) and within treatments compared with baseline (Tukey's test). Categorical data were analysed between treatments (Kruskal-Wallis' test) and within treatments from baseline (Dunn's test). Significance was set at p < .05. All dogs became sedated (laterally recumbent) and sedation onset was significantly faster in groups A7.5 (9.8 ± 5.3 min) and A10 (9.1 ± 5.6 min) compared to A5 (25.6 ± 16.1 min) (p = .033, p = .027, respectively). Duration of sedation was significantly longer in A10 (168.5 ± 70.6 min) and A7.5 (143.8 ± 58 min) compared to A5 (63.8 ± 28.2 min) (p = .005 and p = .003, respectively). Dogs in A10 had a superior quality of onset of sedation compared to A5 (p = .028). Sedation scores and quality of recovery from sedation were not significantly different between doses. Two dogs (2/6) in A5 were insufficiently sedated for cephalic catheterization. Ataxia was the most frequently observed undesirable event with an overall frequency of 78% (14/18) and 89% (16/18) during sedation onset and recovery, respectively. Overall, A4% administered IM in dogs at 7.5 and 10 mg kg-1 resulted in sufficient sedation for IV catheterization in dogs. To improve the speed and quality of the sedation, it is recommended that future research focuses on combining A4% with other sedative or analgesic drugs.

The biomechanical significance of bifurcated cervical ribs in apatosaurine sauropods

Bifurcated cervical ribs have evolved infrequently in dinosaurs. Previously documented examples include those in abelisaurid theropods, leptoceratopsid ceratopsians, and turiasaurian sauropods. In apatosaurine sauropods a spectrum of cervical rib morphologies exists, from cervical ribs with small dorsal processes extending from the shafts to completely bifurcated cervical ribs. Similar dorsal processes are present in the dicraeosaurid Dicraeosaurus. The presence of dorsal processes and bifurcated cervical ribs suggests that the hypaxial neck muscles that inserted on the cervical ribs were oriented in divergent directions. In all the dinosaurian examples we have found, the cervical ribs are maximally bifurcated in the middle of the cervical series. We hypothesize that bifurcated cervical ribs are traces of diverging neck muscles that provided improved control in the middle of the neck, at some distance from both the head and the trunk.

Ultrasound-guided caudal quadratus lumborum block combined with the greater ischiatic notch plane block as motor-protective analgesia for the pelvic limb in dogs

ObjectiveTo develop an ultrasound-guided caudal quadratus lumborum block (C-QLB) technique in canine cadavers and to compare sensory and motor blockade resulting from the combination of ultrasound-guided greater ischiatic notch (GIN) plane and C-QLB approaches (GIN-CQLB group) versus a lumbosacral plexus (LSP group) approach [combination of lateral pre-iliac (LPI) and parasacral (PS) techniques] in dogs. Study designDescriptive anatomical study and prospective randomized, blinded, experimental crossover trial. AnimalsA total of six canine cadavers and six adult Beagle dogs. MethodsPhase I: following ultrasound-guided C-QLB injections of 0.3 mL kg–1 of dye, using the interfascial plane located lateral to the quadratus lumborum muscle at the level of the sixth lumbar vertebra (L6) as injection point, the spread of injectate and nerve staining was evaluated using gross anatomical dissection. Phase II: sensory and motor blockade achieved with the GIN-CQLB or LSP blocks in Beagle dogs were evaluated and compared. The assigned technique was performed with 2% lidocaine: 0.2 mL kg–1 for the GIN and PS approaches and 0.3 mL kg–1 for the C-QLB and LPI approaches. ResultsDissection revealed distribution of dye around the lumbar hypaxial musculature, extending into the paravertebral spaces, with staining of 3 (2–4) [median (interquartile range)] spinal nerves, spanning L3 to L6. The median motor blockade in the GIN-CQLB and LSP groups was 7 (7–8) versus 16 (10–16) (p = 0.026), whereas the median sensory blockade was 5 (4–5) versus 3 (3–3) (p = 0.025), respectively. Conclusion and clinical significanceThe GIN-CQLB approach desensitized the thigh dermatomes effectively. Compared with the LSP approaches, GIN-CQLB exhibits a motor-protective effect by preserving tonic muscle function.

Combined use of body condition score, radiography, ultrasonography and computed tomography in body condition evaluation of crab-eating fox (Cerdocyon thous).

This study aimed to evaluate the application of radiography, ultrasonography, and computed tomography (CT) as auxiliaries in the determination of body fat and musculature in crab-eating foxes (Cerdocyon thous). Eight animals were evaluated and classified based on the body condition score (BCS) scale. The total cut volume, total visceral volume, total subcutaneous volume, visceral fat volume, subcutaneous fat volume, and total fat volume were measured. The correlation of the BCS with the other data was determined. In the ultrasound, there was a correlation of the vertebral epaxial musculature score (VEMS) with body weight, BCS, muscle mass score (MMS), animal's height, and height at the withers. In the radiographic analysis, the amount of subcutaneous fat obtained in L3 vertebrae did not present a significant correlation with BCS, as opposed to L6. In the tomographic analysis, TFV/L6, VFV/L6, and SFV/L6 correlated with BCS in L3, and only SFV /L6 in L6. When the ratios between fat volumes were correlated, the correlation with BCS occurred only in L6 in the TFV/TBV, SFV/SVC, and VFW variants. Radiography and CT were effective and had a good association with BCS. With the CT it was possible to demonstrate the distribution of total fat at the level of the L3 slice. The ratio of calculations considering the length of the L6 vertebra was more adequate, while at the level of L6 the ratio between the volumes of the compartments was more effective.

Assessing the presence, concentration, and impacts of trace element contamination in a Chesapeake Bay tributary adjacent to a coal ash landfill (Possum Point, VA)

Coal ash (CA) is an industrial waste product that has been shown to contain several neurotoxic constituents such as cadmium, selenium, mercury, lead, and arsenic. Contaminant-laced leachates enter the environment via seepage, runoff, permitted discharge, or accidental spills from CA storage ponds or landfills which may pose a risk to wildlife residing in receiving waterways. In this study, we assessed 1) the presence and concentration of thirteen trace elements (Al, Ca, Mg, Cr, Cd, As, Se, Pb, Cu, Zn, Mn, Fe, B) in surface water and sediment grab samples using ICP-OES, 2) the temporal variability of trace elements using Pb-210 dated sediment core samples, 3) differences in species diversity using environmental DNA (eDNA) analyses, and 4) the presence and concentration of trace metals in banded killifish (Fundulus diaphanus) epaxial muscle tissue collected from waterways surrounding the Possum Point Power Station (Stafford, VA). Results showed the highest concentrations of As, Cd, Cr, Cu, Fe, Mg, Se, Zn, and B in Quantico Creek (QC) adjacent to the coal ash ponds and elevated average cadmium and zinc concentrations compared to both upstream and downstream locations along the Potomac River. Sediment core profiles and Pb-210 analyses showed historical enrichment of several trace elements in QC beginning after the commissioning of the power plant in 1948. When compared to upstream and downstream sites, species diversity was drastically reduced in Quantico Creek based on eDNA identification. Muscle tissues of banded killifish collected in Quantico Creek displayed increased Al, Cd, and Zn concentrations compared to upstream and downstream sites. Collectively, our results demonstrate the potential impacts of coal ash landfills on aquatic ecosystems and suggest that further research is needed to fully inform risk assessment and remediation efforts.

Beam theory predicts muscle deformation and vertebral curvature during feeding in rainbow trout (Oncorhynchus mykiss).

Muscle shortening underpins most skeletal motion and ultimately animal performance. Most animal muscle generates its greatest mechanical output over a small, homogeneous range of shortening magnitudes and speeds. However, homogeneous muscle shortening is difficult to achieve for swimming fish because the whole body deforms like a bending beam: as the vertebral column flexes laterally, longitudinal muscle strain increases along a medio-lateral gradient. Similar dorsoventral strain gradients have been identified as the vertebral column flexes dorsally during feeding in at least one body location in one fish. If fish bodies also deform like beams during dorsoventral feeding motions, this would suggest the dorsal body (epaxial) muscles must homogenize both dorsoventral and mediolateral strain gradients. We tested this hypothesis by measuring curvature of the anterior vertebral column with XROMM and muscle shortening in 14 epaxial subregions with fluoromicrometry during feeding in rainbow trout (Oncorhynchus mykiss). We compared measured strain to the predicted strain based on beam theory's curvature-strain relationship. Trout flexed the vertebrae dorsally and laterally during feeding strikes, yet when flexion in both planes was included, the strain predicted by beam theory was strongly and significantly correlated with measured strain (p <0.01, R2=0.60). Beam theory accurately predicted strain (slope=1.15, compared to ideal slope=1) across most muscle subregions, confirming that epaxial muscles experience dorsoventral and mediolateral gradients in longitudinal strain. Establishing this deformation-curvature relationship is a crucial step to understanding how these muscles overcome orthogonal strain gradients to produce powerful feeding and swimming behaviours.

Purine Biosynthesis Pathways Are Required for Myogenesis in Xenopus laevis.

Purines are required for fundamental biological processes and alterations in their metabolism lead to severe genetic diseases associated with developmental defects whose etiology remains unclear. Here, we studied the developmental requirements for purine metabolism using the amphibian Xenopus laevis as a vertebrate model. We provide the first functional characterization of purine pathway genes and show that these genes are mainly expressed in nervous and muscular embryonic tissues. Morphants were generated to decipher the functions of these genes, with a focus on the adenylosuccinate lyase (ADSL), which is an enzyme required for both salvage and de novo purine pathways. adsl.L knockdown led to a severe reduction in the expression of the myogenic regulatory factors (MRFs: Myod1, Myf5 and Myogenin), thus resulting in defects in somite formation and, at later stages, the development and/or migration of both craniofacial and hypaxial muscle progenitors. The reduced expressions of hprt1.L and ppat, which are two genes specific to the salvage and de novo pathways, respectively, resulted in similar alterations. In conclusion, our data show for the first time that de novo and recycling purine pathways are essential for myogenesis and highlight new mechanisms in the regulation of MRF gene expression.

Histological and morphometric analysis of skeletal muscle in some vertebrates

The skeletal system is primarily driven by the skeletal muscles to produce kinematic movements. The study evaluates the histological and morphometric properties of skeletal muscle in Clarias gariepenus (Cl. gariepinus), Bufo bufo (B. bufo), Agama agama (A. agama), Columba livia domestica (C. domestica) and Rattus rattus (R. rattus). The study was carried in order to relate the similarities and differences of skeletal muscles in these species with evolutionary trend. The epaxial muscle of Cl. Gariepinus, the biceps femoris muscle of B. bufo, R. rattus, puboischiotibialis of A. agama, and pectoral muscle from C. domestica were removed and assessed grossly for physical appearance then processed for histological analysis. The diameters of the muscle fibers were measured and one-way analysis of variance was used to compare the differences. The muscles of Cl. gariepinus, B. bufo and A. agama appeared whitish with scanty fusiform nucleus and large intermuscular space. However, the muscles of C. domestica and R. rattus appeared red with distinct round nucleus and small intermuscular space. No significant difference (P&gt;0.05) was observed in the muscle diameter of Cl. gariepinus (8.86±0.13µm) compared to B. bufo (8.25±0.27µm). The muscle diameter of A. agama (10.18±0.25µm) was significantly higher (P&lt;0.05) relative to Cl. gariepinus (8.86±0.13µm), B. bufo (8.25±0.27µm), C. domestica (3.38±0.13µm) and R. rattus (4.66±0.15µm). Conclusively, non-tetrapod vertebrates (Cl. gariepinus, B. bufo, and A. agama) have simple, white-colored skeletal muscle with few flat-shaped nuclei and large fiber diameters while higher vertebrates (C. domestica and R. rattus) have complex, red-colored skeletal muscle with numerous oval-shaped nucleus and small fiber diameter.