Lateral Fibers Research Articles

Anatomical Features in Lower-Lip Depressor Muscles for Optimization of Myectomies in Marginal Mandibular Nerve Palsy.

Myectomies of the lower-lip depressor muscles, with the aim to improve facial balance in unilateral facial paralysis, have unexplained high recurrence rates. A potential explanation is that these recurrences are due to inadequate resection through the muscle width, leaving lateral muscle fibers intact. Revisit the anatomy of the lower-lip depressor muscles and suggest an optimization of the surgical technique. Perform a literature review to identify recurrence rates and surgical technique of the procedure. Ten fresh hemifaces were dissected. The following measurements of depressor labii inferioris and depressor anguli oris were made: the widths of the muscles, the distance from the mandibular midline to the lateral borders of the muscles, and the intraoral distance from the lateral canine to the lateral border of depressor anguli oris. A literature review was performed. The width of depressor labii inferioris was 20 ± 4 mm and depressor anguli oris 14 ± 3 mm. The distance from the midline to the lateral border of depressor labii inferioris was 32 ± 4 mm and 54 ± 4 mm for depressor anguli oris. The literature review revealed a mean recurrence rate of 21%. A potential optimization of the surgical technique in lower-lip depressor myectomies is to extend the muscle resection laterally. To ensure inclusion of the whole width of the depressor muscles and decrease the recurrence rates of the procedure, the measurements presented in this study should be kept in mind during surgery.

The Dystrophin Node as Integrator of Cytoskeletal Organization, Lateral Force Transmission, Fiber Stability and Cellular Signaling in Skeletal Muscle.

The systematic bioanalytical characterization of the protein product of the DMD gene, which is defective in the pediatric disorder Duchenne muscular dystrophy, led to the discovery of the membrane cytoskeletal protein dystrophin. Its full-length muscle isoform Dp427-M is tightly linked to a sarcolemma-associated complex consisting of dystroglycans, sarcoglyans, sarcospan, dystrobrevins and syntrophins. Besides these core members of the dystrophin–glycoprotein complex, the wider dystrophin-associated network includes key proteins belonging to the intracellular cytoskeleton and microtubular assembly, the basal lamina and extracellular matrix, various plasma membrane proteins and cytosolic components. Here, we review the central role of the dystrophin complex as a master node in muscle fibers that integrates cytoskeletal organization and cellular signaling at the muscle periphery, as well as providing sarcolemmal stabilization and contractile force transmission to the extracellular region. The combination of optimized tissue extraction, subcellular fractionation, advanced protein co-purification strategies, immunoprecipitation, liquid chromatography and two-dimensional gel electrophoresis with modern mass spectrometry-based proteomics has confirmed the composition of the core dystrophin complex at the sarcolemma membrane. Importantly, these biochemical and mass spectrometric surveys have identified additional members of the wider dystrophin network including biglycan, cavin, synemin, desmoglein, tubulin, plakoglobin, cytokeratin and a variety of signaling proteins and ion channels.

Auditory attentional filter in the absence of masking noise.

Signals containing attended frequencies are facilitated while those with unexpected frequencies are suppressed by an auditory filtering process. The neurocognitive mechanism underlying the auditory attentional filter is, however, poorly understood. The olivocochlear bundle (OCB), a brainstem neural circuit that is part of the efferent system, has been suggested to be partly responsible for the filtering via its noise-dependent antimasking effect. The current study examined the role of the OCB in attentional filtering, particularly the validity of the antimasking hypothesis, by comparing attentional filters measured in quiet and in the presence of background noise in a group of normal-hearing listeners. Filters obtained in both conditions were comparable, suggesting that the presence of background noise is not crucial for attentional filter generation. In addition, comparison of frequency-specific changes of the cue-evoked enhancement component of filters in quiet and noise also did not reveal any major contribution of background noise to the cue effect. These findings argue against the involvement of an antimasking effect in the attentional process. Instead of the antimasking effect mediated via medial olivocochlear fibers, results from current and earlier studies can be explained by frequency-specific modulation of afferent spontaneous activity by lateral olivocochlear fibers. It is proposed that the activity of these lateral fibers could be driven by top-down cortical control via a noise-independent mechanism. SIGNIFICANCE: The neural basis for auditory attentional filter remains a fundamental but poorly understood area in auditory neuroscience. The efferent olivocochlear pathway that projects from the brainstem back to the cochlea has been suggested to mediate the attentional effect via its noise-dependent antimasking effect. The current study demonstrates that the filter generation is mostly independent of the background noise, and therefore is unlikely to be mediated by the olivocochlear brainstem reflex. It is proposed that the entire cortico-olivocochlear system might instead be used to alter the hearing sensitivity during focus attention via frequency-specific modulation of afferent spontaneous activity.

The structure and musculature of male terminalia in the Palaearctic and Indo-Australian species of the eupitheciine genera Eupithecia Curtis, Gymnoscelis Mabille, and Pasiphila Meyrick (Lepidoptera: Geometridae: Larentiinae).

Eupitheciini is a diverse cosmopolitan tribe of larentiine moths. The structure and musculature of the male terminalia were described in six Palaearctic and Indo-Australian eupitheciine species from the genera Eupithecia Curtis, Gymnoscelis Mabille, and Pasiphila Meyrick (Lepidoptera: Geometridae: Larentiinae). The tergal flexors of the valvae, muscles m4, running to the medial part of the transtilla or to the membrane dorsad of the transtilla are identified as a potential synapomorphy for the tribe Eupitheciini. The tergal extensors of the valvae, muscles m3(2), running deep into the costa valvae is a possible synapomorphy for the genus Gymnoscelis. The genus Pasiphila does not share all eupitheciine characters, with the tergal flexors of the valvae, muscles m4, extending from the dorsal parts of the vinculum. The Eupithecia haworthiata species-group differs from other species-groups by the shape of the uncus and the sternal extensors of the valvae, muscles m8(3), with lateral fibres longer than the medial ones.

Biophysical and morphological changes in inner hair cells and their efferent innervation in the ageing mouse cochlea.

Age-related hearing loss is a progressive hearing loss involving environmental and genetic factors, leading to a decrease in hearing sensitivity, threshold and speech discrimination. We compared age-related changes in inner hair cells (IHCs) between four mouse strains with different levels of progressive hearing loss. The surface area of apical coil IHCs (9-12kHz cochlear region) decreases by about 30-40% with age. The number of BK channels progressively decreases with age in the IHCs from most mouse strains, but the basolateral membrane current profile remains unchanged. The mechanoelectrical transducer current is smaller in mice harbouring the hypomorphic Cdh23 allele Cdh23ahl (C57BL/6J; C57BL/6NTac), but not in Cdh23-repaired mice (C57BL/6NTacCdh23+ ), indicating that it could contribute to the different progression of hearing loss among mouse strains. The degree of efferent rewiring onto aged IHCs, most likely coming from the lateral olivocochlea fibres, was correlated with hearing loss in the different mouse strains. Inner hair cells (IHCs) are the primary sensory receptors of the mammalian cochlea, transducing acoustic information into electrical signals that are relayed to the afferent neurons. Functional changes in IHCs are a potential cause of age-related hearing loss. Here, we have investigated the functional characteristics of IHCs from early-onset hearing loss mice harbouring the allele Cdh23ahl (C57BL/6J and C57BL/6NTac), from late-onset hearing loss mice (C3H/HeJ), and from mice corrected for the Cdh23ahl mutation (C57BL/6NTacCdh23+ ) with an intermediate hearing phenotype. There was no significant loss of IHCs in the 9-12kHz cochlear region up to at least 15months of age, but their surface area decreased progressively by 30-40% starting from ∼6months of age. Although the size of the BK current decreased with age, IHCs retained a normal KCNQ4 current and resting membrane potential. These basolateral membrane changes were most severe for C57BL/6J and C57BL/6NTac, less so for C57BL/6NTacCdh23+ and minimal or absent in C3H/HeJ mice. We also found that lateral olivocochlear (LOC) efferent fibres re-form functional axon-somatic connections with aged IHCs, but this was seen only sporadically in C3H/HeJ mice. The efferent post-synaptic SK2 channels appear prior to the establishment of the efferent contacts, suggesting that IHCs may play a direct role in re-establishing the LOC-IHC synapses. Finally, we showed that the size of the mechanoelectrical transducer (MET) current from IHCs decreased significantly with age in mice harbouring the Cdh23ahl allele but not in C57BL/6NTacCdh23+ mice, indicating that the MET apparatus directly contributes to the progression of age-related hearing loss.

Super-relaxed state of myosin in human skeletal muscle is fiber-type dependent.

The myosin super-relaxed state (SRX) in skeletal muscle is hypothesized to play an important role in regulating muscle contractility and thermogenesis in humans but has only been examined in model organisms. Here we report the first human skeletal muscle SRX measurements, using quantitative epifluorescence microscopy of fluorescent 2'/3'-O-(N-methylanthraniloyl) ATP (mantATP) single-nucleotide turnover. Myosin heavy chain (MHC) isoform expression was determined using gel electrophoresis for each permeabilized vastus lateralis fiber, to allow for novel comparisons of SRX between fiber types. We find that the fraction of myosin in SRX is less in MHC IIA fibers than in MHC I and IIAX fibers (P = 0.008). ATP turnover of SRX is faster in MHC IIAX fibers compared with MHC I and IIA fibers (P = 0.001). We conclude that SRX biochemistry is measurable in human skeletal muscle, and our data indicate that SRX depends on fiber type as classified by MHC isoform. Extension from this preliminary work would provide further understanding regarding the role of SRX in human muscle physiology.

186. Comparison of a 3D printed truss-based lateral interbody device to an annular lateral interbody device for resistance to subsidence: a cadaveric study

BACKGROUND CONTEXT Endplate decortication, substantive physiologic loads and inappropriate cage design may contribute to subsidence. Severe subsidence can lead to nerve compression and pain that may require revision surgery. Additionally, lateral approaches may be more susceptible to subsidence due to indirect decompression. Additive (3D) manufacturing has enabled the creation of implants with advanced structural designs that differ in endplate contact surface topology and load distribution at the bone- implant interface as compared to traditional annular designs. PURPOSE The purpose of this study is to compare two commercially available lateral interbody devices of the same size for resistance to subsidence. One device had a truss endplate contact topology and the other had an annular structure. Additionally, the study is designed to compare subsidence in the presence and absence of endplate decortication. STUDY DESIGN/SETTING Cadaver testing using human vertebral bones. PATIENT SAMPLE N/A OUTCOME MEASURES Subsidence resistance of different interbody constructs. METHODS A total of 48 vertebral bones with bone mineral density > 1g/cm2, obtained from 8 fresh male human lumbar spines (L1-L5), were dissected, cleaned and randomized into 4 groups, which included short and long lateral titanium truss and carbon fiber annular cages. Both cages had dimensions of 18mm AP depth, 12mm height in 40mm (short) and 60mm (long). These were evaluated with both intact and decorticated vertebrae (n=6). The inferior endplate of each vertebral bone was fixed into bondo block and the potted vertebra were placed in a fixture gripped in a vice centered with the actuator of a MTS mechanical testing unit.To mimic clinical subsidence displacement, a compressive load was applied to the top endplate of each implant at a rate of 5mm/min. Load displacement at 1 and 2mm of subsidence was collected and recorded for each test combination. Two-way ANOVA with Sidak-Bonferroni Posthoc was used for multiple comparisons and analysis of statistical significance. RESULTS The subsidence resistance of the truss cage was significantly greater than the annular cage of corresponding length when tested with an intact or decorticated endplate. The resistance load was 670N vs 540N (P=0.004) at 1mm subsidence and 1200N vs 920N (p=0.002) at 2mm in short Truss versus short Annular cage. For long cages the resistance load at was 840N vs 630N in (P=0.001) at 1mm subsidence and 1650N vs 1235N in (P CONCLUSIONS The truss endplate topology demonstrated significantly better resistance to subsidence for vertebral bone with intact or decorticated endplates as compared to the same size annular cage. Improved subsidence resistance of the truss cage may be due to the distribution of load across a larger cross-sectional area at the bone/implant interface (increased line length contact; snowshoe effect) where the load is uniformly distributed across more of the interbody footprint. Although this study did not control for differences in material composition and stiffness, a separate controlled study using foam blocks demonstrated that the implant's surface contact topology played a greater role than the material and the structural modulus for resisting subsidence. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Type of levator ani muscle avulsion as predictor for the disappearance of avulsion.

The objective of our study was to establish whether the type of levator ani muscle (LAM) avulsion diagnosed 6 months after delivery influences the integrity of the LAM at 1 year after delivery and determine its influence on the levator hiatus area. This observational prospective cohort study included 192 primiparous women with vaginal delivery. Transperineal ultrasound examinations were performed at 6 months and 1 year postpartum. Levator hiatus measurements (anteroposterior diameter, transverse diameter, and area) were performed in the plane of minimal dimensions. Complete avulsion was defined based on maximum contraction in multislice mode. Type I LAM avulsion was present when most lateral fibers of the pubovisceral muscle were observed at its insertion at the pubic level (the arch of the elevator remained intact). Type II LAM avulsion was defined as a complete detachment of the pubovisceral muscle from its insertion at the pubic level. In total, 192 patients were recruited after delivery; 48 patients were diagnosed with complete LAM avulsion, and 13 patients with avulsion did not attend the second ultrasound follow-up at 1 year after delivery. Thirty-five patients with complete LAM avulsion were included in the study. At 6 months after delivery, 51 LAM avulsions were observed in 35 patients (including bilateral LAM avulsion in 16 cases), of which 54.9% were right avulsions and 45.1% left avulsions. Furthermore, 11 (five right and six left) were type I LAM avulsions at the 6-month assessment, and all of these had disappeared 1 year after delivery. However, none of the type II LAM avulsions (23 right and 17 left) observed at 6 months had disappeared at the second ultrasound examination. There were no differences between the LAM areas detected at the first and second ultrasound examinations (10.2 ± 3.3 vs 9.3 ± 1.8; P = .404). The type of LAM avulsion observed at 6 months after childbirth predicts LAM persistence at 1 year postpartum.

Lateral subvastus approach: A cadaveric examination of its potential for total knee arthroplasty

BackgroundLateral approaches to total knee arthroplasty (TKA) provide good surgical exposure and may provide greater ease of soft tissue balancing in patients with a valgus deformity; however, little is known about the versatility in non-valgus knees. The present study evaluated if a lateral subvastus approach can achieve adequate surgical exposure while maintaining less soft tissue damage compared with the medial parapatellar approach in knees without any significant deformity. MethodsUsing paired fresh-frozen cadaveric knees, the present study provides the first specimen-matched, side-by-side comparison of the lateral subvastus approach to the standard medial parapatellar approach to TKA. Ten knees were selected to undergo a lateral subvastus approach; the contralateral knee had a medial parapatellar approach as control. Incision length, surgical exposure and iatrogenic soft tissue damage were compared between the two approaches. ResultsThe lateral subvastus approach was successfully performed using an incision length that was not different from that used in the medial parapatellar approach (p > 0.05). The resultant surgical exposure was comparable between approaches (p > 0.05). The risk of the approach included tearing of the vastus lateralis fibers, and/or abrasion of the iliotibial tract/patellar ligament. ConclusionsThe lateral subvastus approach to TKA provided a comparable method to the standard medial parapatellar approach. Despite adequate exposure, the approach did risk soft tissue injury. Caution needs to be exercised to reduce the risk of iatrogenic injury to the vastus lateralis and surrounding ligaments. The successful implementation in this cadaveric study substantiates the need for further consideration of this approach in clinical practice.

The Impairment Of Oxidative Metabolism After 10-day Of Bed Rest Is Upstream Of Skeletal-Muscle Mitochondria

PURPOSE: Exposure to microgravity, as simulated by bed rest (BR), leads to an impairment of oxidative metabolism. The sites of this impairment are still debated. Aim of this study was to identify markers of impaired oxidative metabolism along the O2 pathway, from ambient air to skeletal muscle mitochondria, following 10 days of BR. METHODS: Measurements were carried out on 10 recreationally active young males (age 23 ± 5 years [mean±SD]) before (PRE) and after (POST) 10 days of horizontal BR. Pulmonary O2 uptake (V̇O2) and other respiratory, cardiovascular and skeletal muscle variables were determined during an incremental exercise on a cycle ergometer. Peripheral vascular and endothelial functions were evaluated by the blood flow response (Doppler ultrasound) in the femoral artery during 1-min passive leg movement (PLM). Mitochondrial respiration was evaluated by high-resolution respirometry on permeabilized vastus lateralis fibers obtained by biopsy. RESULTS: Peak V̇O2 was lower (P=0.001) in POST (41.5 ± 6.5 ml.kg-1.min-1) vs. PRE (44.5 ± 7.4). The area under the blood flow vs. time curve during PLM was lower (P=0.038) in POST (274 ± 233 mL) vs. PRE (427 ± 291). Skeletal muscle citrate synthase activity, an estimate of mitochondrial mass, was not different (P=0.115) in POST (131.2 ± 15.9 UI.mg-1.protein) vs. PRE (137.9 ± 18.8). Maximal ADP-stimulated mitochondrial respiration (66.4 ± 17.5 pmol.s-1.mg-1 wet weight [POST] vs. 72.3 ± 14.0 [PRE], P=0.127) and oxidative phosphorylation coupling efficiency (respiratory control ratio, 4.10 ± 1.19 [PRE] vs. 3.59 ± 1.11 [POST], P=0.443) were not affected by BR. CONCLUSIONS: These preliminary data suggest that the whole-body impairment of oxidative metabolism during exercise, following 10 days of horizontal BR, is associated with an impairment of peripheral vascular and endothelial functions, whereas mitochondrial volume and respiratory function are unaffected. Data related to several other markers (pulmonary function, cardiac output, submaximal exercise tolerance, skeletal muscle fractional O2 extraction, skeletal muscle V̇O2 recovery kinetics, mitochondrial respiration sensitivity to submaximal [ADP]) are yet to be analyzed. Funding: ASI, MARS-PRE Project, n. DC-VUM-2017-006

Fiber Type and Size as Sources of Variation in Human Single Muscle Fiber Passive Elasticity.

Studies on single muscle fiber passive material properties often report relatively large variation in elastic modulus (or normalized stiffness), and it is not clear where this variation arises. This study was designed to determine if the stiffness, normalized to both fiber cross-sectional area and length, is inherently different between types 1 and 2 muscle fibers. Vastus lateralis fibers (n = 93), from ten young men, were mechanically tested using a cumulative stretch-relaxation protocol. SDS-PAGE classified fibers as types 1 or 2. While there was a difference in normalized stiffness between fiber types (p = 0.0019), an unexpected inverse relationship was found between fiber diameter and normalized stiffness (r = -0.64; p < 0.001). As fiber type and diameter are not independent, a one-way analysis of covariance (ANCOVA) including fiber diameter as a covariate was run; this eliminated the effect of fiber type on normalized stiffness (p = 0.1935). To further explore the relationship between fiber size and elastic properties, we tested whether stiffness was linearly related to fiber cross-sectional area, as would be expected for a homogenous material. Passive stiffness was not linearly related to fiber area (p < 0.001), which can occur if single muscle fibers are better represented as composite materials. The rule of mixtures for composite materials was used to explore whether the presence of a stiff perimeter-based fiber component could explain the observed results. The model (R2 = 0.38) predicted a perimeter-based normalized stiffness of 8800 ± 2600 kPa/μm, which is within the range of basement membrane moduli reported in the literature.

Improved Visualization by Central Subluxation of the Lateral Meniscus in Comminuted Lateral Tibial Plateau Fractures.

The goal of surgical reconstruction of comminuted tibial plateau fractures is an anatomical reconstruction and stable fixation of the articular surface. This can be difficult due to poor visualization of the posterolateral and central segments of the articular surface of the proximal tibia. To improve visualization, the lateral approach can be extended with an osteotomy of the femoral epicondyle. In most cases, use of the extended lateral approach allows the whole lateral plateau to be visualized. Nevertheless, in some cases, an osteotomy alone is not enough to expose the entire fracture, especially the central segments of the tibial plateau. For these specific cases, we developed an additional technical trick that significantly improves articular visualization; the lateral meniscocapsular fibers are dissected allowing for central subluxation of the lateral meniscus, while leaving the anterior and posterior roots intact. With central subluxation of the lateral meniscus in comminuted tibial plateau fractures, the joint surface can be completely visualized, allowing an anatomical reduction even in highly complex fractures.

Analysis of behavioral changes in zebrafish (Danio rerio) larvae caused by aminoglycoside-induced damage to the lateral line and muscles

Zebrafish behavior is influenced by the lateral line hair cells and muscles. Drug-induced behavioral changes can serve as indicators in the evaluation of drug toxicity. The aminoglycoside family of antibiotics comprise a number of agents, including neomycin (NM) and gentamicin (GM). We hypothesized that NM and GM exert different effects on zebrafish larvae through their action on the lateral line and muscle fibers, inducing different swimming behavioral patterns such as locomotor behavior and the startle response. In this study, 125 μM NM and 5, 10, 20 μM GM induced hair cell damage in the anterior and posterior lateral lines of zebrafish larvae. However, unlike GM, 125 μM NM also caused muscle damage. Locomotor behavior was decreased in the 125 μM NM-exposed group compared to the group exposed to GM. Furthermore, 125 μM NM exposure induced significantly different patterns of various indices of startle behavior compared with the GM exposure groups. Additionally, the larvae exhibited different startle responses depending on the concentration of GM. These results suggest that GM may be the drug-of-choice for analyzing behavioral changes in zebrafish caused by damage to the lateral line alone. Our study highlights the importance of confirming muscle damage in behavioral analyses using zebrafish.

Constitutive description of skin dermis: Through analytical continuum and coarse-grained approaches for multi-scale understanding

Although there are many successful descriptions of the mechanical response of dermis at different levels of complexity and incorporating varying degrees of the physical phenomena involved in deformation, observations indicate that the unraveling of fibers involves a complex three-dimensional process in which they interact in ways that resemble a braided pattern. Here we develop two complementary treatments to gain a better understanding of the mechanical response of dermis: a) an analytical treatment incorporating fibril stiffness, interfibrillar frictional sliding, and the effect of lateral fibers on the extension of a primary fiber; b) a coarse-grained molecular dynamics model comprised of an array of parallel curved fibrils simulating a fiber. Interfibrillar frictional sliding and stiffness are also captured. Both analytical and molecular dynamics models operate at a scale compatible with the wavelength of collagen fibers (~10 µm). The constitutive description presented here incorporates important physical processes taking place during deformation of dermis and thus represents an advance in our understanding of these phenomena. Statement of SignificanceMicrostructural observations of the dermis of skin during tensile deformation indicate that the unraveling of fibers involves a complex three-dimensional process which replicates the effects of braiding. Two complementary constitutive modeling treatments were developed to gain a better understanding of the mechanical response of dermis: an analytical treatment incorporating fibril stiffness, interfibrillar sliding, and the effect of transverse fibers; and a coarse-grained molecular dynamics model describing the fibril bundling effect.An important novel aspect of the current contribution is the recognition that tridimensional collagen fiber arrangements play an important role in the mechanical response. The constitutive description presented here incorporates physical processes taking place during deformation of the dermis and thus represents an advance in our understanding of these phenomena.

Photobiostimulation activity of different low-level laser dosage on masticatory muscles and temporomandibular joint in an induced arthritis rat model.

This study aimed to investigate the anti-inflammatory effects of different dosage of low-level laser therapy (LLLT) in an experimental model of temporomandibular joint (TMJ) arthritis. One hundred male Wistar rats were used and divided into the following groups: CG, control group; AG, animals group with left TMJ arthritis induced by intra-articular injection of Complete Freund's adjuvant - CFA; LG5, LG10 and LG20 - animals with arthritis and treated with LLLT at doses 5, 10, and 20J/cm2, respectively. Morphological analysis was performed by TMJ histological sections stained with hematoxylin-eosin (HE), picrosirius (PSR), and toluidine blue (TB), as well as histomorphometric evaluation of cartilage, articular disc, and masticatory muscles. The amount of feed consumed within 3weeks was evaluated, and biochemical analysis of TMJ tissues included measurement of sulfated glycosaminoglycans (GAGs), matrix metalloproteinases (MMPs) 2 and 9 zymography, and ELISA for cytokines IL-6, TNF-α, and IL-1β. Only the 20J/cm2 dose promoted higher feed intake compared to AG. On the other hand, all LLLT doses promoted better organization of articular disc collagen fibers, greater number of proteoglycans in articular cartilage, increased area and diameter of left lateral pterygoid fibers, reduced latent and active MMP 9 and 2 activity, and lower IL-1β concentration compared to AG. Considering the study limitations, it was observed that LLLT treatments were effective in protecting and tissue cleansing joint structures, accelerating tissue repair, especially at lower doses.

Fiber Type Composition and Rate of Force Development in Endurance- and Resistance-Trained Individuals.

Methenitis, S, Spengos, K, Zaras, N, Stasinaki, A-N, Papadimas, G, Karampatsos, G, Arnaoutis, G, and Terzis, G. Fiber type composition and rate of force development in endurance- and resistance-trained individuals. J Strength Cond Res 33(9): 2388-2397, 2019-The purpose of the study was to investigate the relationship between muscle fiber composition and the rate of force development (RFD) in well-trained individuals with different training background. Thirty-eight young men with different training background participated: 9 endurance runners, 10 power-trained individuals, 9 strength-trained individuals, and 10 sedentary individuals. They performed maximal isometric leg press for the measurement of RFD. Body composition (dual x-ray absorptiometry) and vastus lateralis fiber type composition were also evaluated. When all participants were examined as a group, moderate correlations were found between the percent of type II muscle fibers and RFD between 100 and 600 milliseconds (r = 0.321-0.497; p ≤ 0.05). The correlation coefficients were higher for the cross-sectional area (CSA) and the %CSA of type II and IIx muscle fibers (r = 0.599-0.847; p < 0.001). For the power group, RFD up to 250 milliseconds highly correlated with % type IIx muscle fibers and type IIx fiber CSA (r = 0.670-0.826; p ≤ 0.05), as well as with %CSA of type IIx fibers (r = 0.714-0.975; p ≤ 0.05). Significant correlations were found between the relative RFD (·kg lower extremities lean mass) and CSA-%CSA of type II and IIx fibers for the power group (r = 0.676-0.903; p ≤ 0.05). No significant correlations were found between muscle morphology and RFD for the other groups. In conclusion, the present data suggest that there is a strong link between the type IIx muscle fibers and early RFD and relative RFD in power-trained participants. Type II fibers seem to be moderately linked with RFD in non-power-trained individuals.

Sagittal Alignment With Downward Slope of the Lower Lumbar Motion Segment Influences Its Modes of Failure in Direct Compression: A Mechanical and Microstructural Investigation.

Microstructural investigation of compression-induced herniation of ovine lumbar discs with and without added component of anterior-inferior slope. Does increased shear arising from a simulated component of motion segment slope imitating sacral slope weaken the lateral annulus and increase risk of overt herniation at this same region. An increase in sacral slope secondary to lordosis and pelvic incidence increases shear stresses at the lumbosacral junction and has been associated with an increase in spondylolisthetic disorders and back injury. The small component of forward shear induced when a segment is compressed in flexion is suggested to cause differential recruitment of the lateral annular fibers leading to its early disruption followed by intra-annular nuclear tracking to the posterolateral/posterior regions. However, the influence of even greater forward shear arising from the added component of slope seen where pelvic incidence and lumbar lordosis are increased in the lower lumbar spine is less understood. Ovine motion segments were compressed at 40 mm/min up to failure; 9 with a horizontal disc alignment and 26 with a segment slope of 15° and then analyzed structurally. All the horizontal discs failed (11.8 ± 2.4 kN) via vertebral fracture without any evidence of soft tissue failure even in the lateral aspects of the discs. The increased forward shear resulting from the slope decreased the failure load (6.4 ± 1.6 kN). The sloping discs mostly suffered mid-span, noncontinuous disruption of the lateral annulus with some extruding nuclear material directly from these same lateral regions. The increased level of forward shear generated in moderately sloping lumbar segments when compressed was abnormally damaging to the lateral regions of the disc annulus. This is consistent with the view that shear differentially loads the oblique-counter oblique fiber sets in the lateral annulus, increasing its vulnerability to early disruption and overt herniation. N/A.

Long non-coding RNAs: Fine-tuning the developmental responses in plants

Plant developmental biology is associated with various gene regulatory pathways involved in different phases of their life cycle. In course of development, growth and differentiation of different organs in plants are regulated by specific sets of gene expression. With the advances in genomic and bioinformatic techniques, particularly high-throughput sequencing technology, many transcriptional units with no protein-coding potential have been discovered. Previously thought to be the dark matters of genome, long non-coding RNAs (lncRNAs) are gradually gaining importance as crucial players in gene regulation during different developmental phases. Some lncRNAs, showing complementarity to microRNAs (miRNAs), are used as endogenous target mimics of specific miRNA family. A number of lncRNAs can also act as natural antisense transcripts to attenuate the expression of coding genes. Although lncRNA-mediated regulations have extensively been studied in animals, plant lncRNA research is still in its initial phase. The present review highlights the regulatory mechanism and different physiological aspects of lncRNAs in plant development. In plants, lncRNAs are found to be associated with a number of plant developmental functions such as lateral root development, vernalization, photomorphogenesis, pollen development, fiber development and nodulation. Understanding these potent roles of lncRNAs in plant development can further provide novel tools for crop improvement programs in future.

Understanding gamma ventral capsulotomy: Potential implications of diffusion tensor image tractography on target selectivity.

Background:The role of tractography in gamma ventral capsulotomy (GVC) planning is still unclear. This paper aims to describe the spatial distribution of medial orbitofrontal cortex (OFC) and lateral OFC fibers passing through the anterior limb of the internal capsule (ALIC) and analyze quantitative tractography parameters that differentiate obsessive-compulsive disorder (OCD) individuals from other neurosurgery functional patients (morbid obesity and Parkinson’s disease [PD]).Methods:Twenty patients undergoing functional stereotactic procedures, between 2013 and 2016, were included in this study. OCD patients underwent GVC (single shot 150 Gy and 4-mm collimators). PD and morbid obesity patients were submitted to deep brain stimulation implants. Diffusion tensor image tractography was reconstructed using Brainlab Elements software (Brainlab AG, Munich, Germany).Results:Nine PD, six morbid obesity, and five OCD patients were included with a mean age of 65.4 ± 9.1, 41.0 ± 8.2, and 31.2 ± 5.5, respectively, which are statistically different from each other (P < 0.001). Fourteen patients (70%) were men. A total of 40 cerebral hemispheres were analyzed. Medial OFC fibers are localized more inferior in the ALIC than the lateral OFC fibers in all hemispheres, but the level of intersection and exact topography of fiber bundles are variable among individuals. Both medial and lateral OFC fiber tracts of PD and morbid obesity patients have lower volume than, respectively, medial and lateral counterparts of OCD patients (P < 0.001).Conclusions:Medial and lateral OFC tract fibers have a general standard distribution in the anterior internal capsule (lateral OFC higher than medial OFC fibers). There are differences between obesity, Parkinson, and OCD patients regarding fiber tract statistics.

Dorsal component of the superior longitudinal fasciculus revisited: novel insights from a focused fiber dissection study.

The aim of this study was to investigate the anatomical consistency, morphology, axonal connectivity, and correlative topography of the dorsal component of the superior longitudinal fasciculus (SLF-I) since the current literature is limited and ambiguous. Fifteen normal, adult, formalin-fixed cerebral hemispheres were studied through a medial to lateral fiber microdissection technique. In 5 specimens, the authors performed stepwise focused dissections of the lateral cerebral aspect to delineate the correlative anatomy between the SLF-I and the other two SLF subcomponents, namely the SLF-II and SLF-III. The SLF-I was readily identified as a distinct fiber tract running within the cingulate or paracingulate gyrus and connecting the anterior cingulate cortex, the medial aspect of the superior frontal gyrus, the pre-supplementary motor area (pre-SMA), the SMA proper, the paracentral lobule, and the precuneus. With regard to the morphology of the SLF-I, two discrete segments were consistently recorded: an anterior and a posterior segment. A clear cleavage plane could be developed between the SLF-I and the cingulum, thus proving their structural integrity. Interestingly, no anatomical connection was revealed between the SLF-I and the SLF-II/SLF-III complex. Study results provide novel and robust anatomical evidence on the topography, morphology, and subcortical architecture of the SLF-I. This fiber tract was consistently recorded as a distinct anatomical entity of the medial cerebral aspect, participating in the axonal connectivity of high-order paralimbic areas.