Feeding biomechanics of the cownose ray, Rhinoptera bonasus, over ontogeny.

Growth affects the performance of structure, so the pattern of growth must influence the role of a structure and an organism. Because animal performance is linked to morphological specialization, ontogenetic change in size may influence an organism's biological role. High bite force generation is presumably selected for in durophagous taxa. Therefore, these animals provide an excellent study system for investigating biomechanical consequences of growth on performance. An ontogenetic series of 27 cownose rays (Rhinoptera bonasus) were dissected in order to develop a biomechanical model of the feeding mechanism, which was then compared with bite forces measured from live rays. Mechanical advantage of the feeding apparatus was generally conserved throughout ontogeny, while an increase in the mass and cross-sectional area of the jaw adductors resulted in allometric gains in bite force generation. Of primary importance to forceful biting in this taxon is the use of a fibrocartilaginous tendon associated with the insertion of the primary jaw adductor division. This tendon may serve to redirect muscle forces anteriorly, transmitting them within the plane of biting. Measured bite forces obtained through electrostimulation of the jaw adductors in live rays were higher than predicted, possibly due to differences in specific tension of actual batoid muscle and that used in the model. Mass-specific bite forces in these rays are the highest recorded for elasmobranchs. Cownose rays exemplify a species that, through allometric growth of bite performance and morphological novelties, have expanded their ecological performance over ontogeny.

Massage-induced morphological changes of dense connective tissue in rat's tendon.

The aim of the experiment was to determine if possible changes in connective tissue induced by massage could have a positive effect justifing the use of massage in all post-traumatic connective tissue conditions, e.g. tendon injuries. The investigations were performed in a group of 18 Buffalo rats. The rats were divided into two groups (experimental and control). To standardize the massage procedure, it was performed with an algometer probe of 0.5 cm2 with constant pressure force of 1 kG (9,81 N). To analyse the number and diameter of collagen fibrils, two electron micrographs were performed for each rat of the collected segments of tendons of rat tail lateral extensor muscle. After image digitalization and calibration, the measurements were carried out using iTEM 5.0 software. The number of fibrils, their diameter and area were measured in a cross-sectional area. An increase of the number of collagen fibrils was observed in the tendons of massaged animals compared to the control group. Our study demonstrated that massage may cause a beneficial effect on metabolic activity of tendon's fibroblasts and, in consequence, may be applied for more effective use of massage for the prevention of tendon injury as well as after the injury has occurred. (Folia Histochemica et Cytobiologica 2013, Vol. 51, No. 1, 103-106).

Doppler ultrasound-based measurement of tendon velocity and displacement for application toward detecting user-intended motion.

The motivation of this research is to non-invasively monitor the wrist tendon's displacement and velocity, for purposes of controlling a prosthetic device. This feasibility study aims to determine if the proposed technique using Doppler ultrasound is able to accurately estimate the tendon's instantaneous velocity and displacement. This study is conducted with a tendon mimicking experiment consisting of two different materials: a commercial ultrasound scanner, and a reference linear motion stage set-up. Audio-based output signals are acquired from the ultrasound scanner, and are processed with our proposed Fourier technique to obtain the tendon's velocity and displacement estimates. We then compare our estimates to an external reference system, and also to the ultrasound scanner's own estimates based on its proprietary software. The proposed tendon motion estimation method has been shown to be repeatable, effective and accurate in comparison to the external reference system, and is generally more accurate than the scanner's own estimates. After establishing this feasibility study, future testing will include cadaver-based studies to test the technique on the human arm tendon anatomy, and later on live human test subjects in order to further refine the proposed method for the novel purpose of detecting user-intended tendon motion for controlling wearable prosthetic devices.

A fluorescence lifetime imaging scanning confocal endomicroscope.

We describe a fluorescence lifetime imaging endomicroscope employing a fibre bundle probe and time correlated single photon counting. Preliminary images of stained pollen grains, eGFP-labelled cells exhibiting Förster resonant energy transfer and tissue autofluorescence are presented.

Mineralized soft-tissue structure and chemistry in a mummified hadrosaur from the Hell Creek Formation, North Dakota (USA).

An extremely well-preserved dinosaur (Cf. Edmontosaurus sp.) found in the Hell Creek Formation (Upper Cretaceous, North Dakota) retains soft-tissue replacement structures and associated organic compounds. Mineral cements precipitated in the skin apparently follow original cell boundaries, partially preserving epidermis microstructure. Infrared and electron microprobe images of ossified tendon clearly show preserved mineral zonation, with silica and trapped carbon dioxide forming thin linings on Haversian canals within apatite. Furthermore, Fourier transform infrared spectroscopy (FTIR) of materials recovered from the skin and terminal ungual phalanx suggests the presence of compounds containing amide groups. Amino acid composition analyses of the mineralized skin envelope clearly differ from the surrounding matrix; however, intact proteins could not be obtained using protein mass spectrometry. The presence of endogenously derived organics from the skin was further demonstrated by pyrolysis gas chromatography mass spectrometry (Py-GCMS), indicating survival and presence of macromolecules that were in part aliphatic (see the electronic supplementary material).

Vastus medialis: anatomical and functional considerations and implications based upon human and cadaveric studies.

OBJECTIVE: To provide an electrophysiological and functional description of the vastus medialis (VM) and contrast it to an anatomical description. METHODS: Motor points of all superficial portions of the quadriceps were identified on the dominant side of 8 human subjects and electrically stimulated to achieve a light contraction to trace and measure the orientation of the fibers. Electromyography of the VM was then recorded over 2 motor points during isometric and isokinetic maximum knee extensions. An independent laboratory dissected 39 cadaveric specimens focusing on fiber orientations and distal insertions of the VM. RESULTS: Results revealed 5 motor points for the quadriceps: 1 point for the vastus lateralis, 1 point for the rectus femoris (RF), and 3 points for the VM. The 3 VM motor points suggest 3 separate groups of fibers: proximal (pf), median (mf), distal (df). Fiber orientations ranged from 45 degrees for VMpfs to 55 degrees for VMdfs. Motor point stimulation and anatomical dissection clearly showed that the VMpfs and VMmfs were inserted on a tendon common to the RF, whereas VMdfs were attached directly to the medial aspect of the patella. Furthermore, the VMpfs were more active (P < .05) than VMdfs during maximum knee extensions. CONCLUSION: The anatomy, motor points, and electromyography clearly support an important distinction between the VMpfs and VMdfs. The role of the VMpfs would be one of assisting the RF in knee extension, whereas the VMdfs would track the patella medially without participating in knee extension. Because of these anatomical and functional differences, the VMpfs and VMdfs should be addressed very differently during quadriceps rehabilitation in patellofemoral dysfunctions.

Structural and functional characterization of a muscle tendon proprioceptor in lobster.

A morphological and electrophysiological study was made on a unique primary mechanosensory neuron, the anterior gastric receptor (AGR), previously shown to arise from power-stroke muscle gm1 of the gastric mill system in the lobster foregut. Ultrastructural analysis of horseradish peroxidase injected AGR demonstrated that its peripheral dendrites do not ramify in muscle but are confined strictly to the connective tissue/epidermal interface in the tendon of gm1. These terminals are rich in mitochondria and at their very endings are free of glial cell wrapping, suggesting that they are the site at which mechano-transduction occurs. Extracellular axonal recordings from an in vitro neuromuscular preparation consisting of the gm1 muscle still attached to the stomatogastric nervous system, revealed that AGR is activated by passive stretch of gm1. The response to ramp stimuli displays dynamic and static components, both of which increase with the amplitude of applied stretch, while the dynamic component is also velocity sensitive. AGR is also activated by muscle contraction here elicited either by application of exogenous acetylcholine, the excitatory neurotransmitter for gm1, or by electrical stimulation of the motoneurons (GM) themselves. Consistent with a receptor lying in-series with its muscle, therefore, the effective stimulus of AGR in vivo is probably an increase in tension exerted on the tendon during active muscle contraction. In neuromuscular preparations including the bilateral commissural ganglia, stretching gm1 reflexly activates GM motoneurons at low stimulus strengths but leads to an inactivation of GM motoneurons at high stimulus strengths. This is consistent with earlier findings that both responses can be elicited by direct electrical stimulation of AGR. The functional implications of AGR's anatomical relationship with muscle gm1, the receptor's response properties, and its central effects on motor output to gm1 are discussed. Comparison is also drawn between this first reported example of a true tendon receptor in invertebrates and muscle receptors of vertebrates.

Acupuncture points of the brachial plexus.

This publication is the third of a total of six papers intended to name acupuncture points following the anatomic nomenclatures. In the first publication, acupuncture points in the head are named using terminal branches of the trigeminal nerve and the muscles of facial expression. In the second publication, acupuncture points in the neck are named using the cutaneous nerves of the cervical plexus and neuromuscular attachments formed by the spinal accessory nerve on the trapezius muscle. In this third publication, acupuncture points existing on the upper limbs are described following the terminal branches of the brachial plexus.

Morphological data concerning the acupuncture points and channel network.

Through its traditional rules, the practice of acupuncture requires knowledge of the channel networks and point locations. For nearly three centuries, morphological research did not show any evidence on peripheral morphological support of the channels. Their courses appear as referred sensations, and the persistence of propogated sensations along the channels in amputees and their cessation after total section of the spinal cord implicates a neuraxial participation. The spatial sequence of the segmental centers seems to be the indispensable primary structure. Through the various centers having a topical organization, the somesthetic areas appear as the necessary structural support of the propogated sensation along the channel. Acupuncture points are less discussed as a basis of acupuncture in the West, but they do have equivalences in all medical systems. Nervous structures are necessary for acupuncture to work, and complete denervation totally suppresses the effect of the points. There is not only one type of acupuncture point but many of them, and the concomitant stimulation of multiple and clearly defined structures is necessary to obtain the acupuncture sensation, De Qi. Thus, the effect seems strictly correlated with convergence of nerve impulses on the primary centers. Lastly, accurate anatomical knowledge of the point and its correct puncture (location, direction, depth) are indispensable to get satisfactory therapeutical effects and to avoid iatrogenic incidents.