Alterations of Neuromuscular Function after the World's Most Challenging Mountain Ultra-Marathon.

We investigated the physiological consequences of the most challenging mountain ultra-marathon (MUM) in the world: a 330-km trail run with 24000 m of positive and negative elevation change. Neuromuscular fatigue (NMF) was assessed before (Pre-), during (Mid-) and after (Post-) the MUM in experienced ultra-marathon runners (n = 15; finish time  = 122.43 hours ±17.21 hours) and in Pre- and Post- in a control group with a similar level of sleep deprivation (n = 8). Blood markers of muscle inflammation and damage were analyzed at Pre- and Post-. Mean ± SD maximal voluntary contraction force declined significantly at Mid- (-13±17% and -10±16%, P<0.05 for knee extensor, KE, and plantar flexor muscles, PF, respectively), and further decreased at Post- (-24±13% and -26±19%, P<0.01) with alteration of the central activation ratio (-24±24% and -28±34% between Pre- and Post-, P<0.05) in runners whereas these parameters did not change in the control group. Peripheral NMF markers such as 100 Hz doublet (KE: -18±18% and PF: -20±15%, P<0.01) and peak twitch (KE: -33±12%, P<0.001 and PF: -19±14%, P<0.01) were also altered in runners but not in controls. Post-MUM blood concentrations of creatine kinase (3719±3045 Ul·(1)), lactate dehydrogenase (1145±511 UI·L(-1)), C-Reactive Protein (13.1±7.5 mg·L(-1)) and myoglobin (449.3±338.2 µg·L(-1)) were higher (P<0.001) than at Pre- in runners but not in controls. Our findings revealed less neuromuscular fatigue, muscle damage and inflammation than in shorter MUMs. In conclusion, paradoxically, such extreme exercise seems to induce a relative muscle preservation process due likely to a protective anticipatory pacing strategy during the first half of MUM and sleep deprivation in the second half.

Bucket-handle tear of the triangular fibrocartilage complex : case report of a complex peripheral injury with separation of the distal radioulnar ligaments from the articular disc.

Palmer previously proposed a classification system of triangular fibrocartilage complex (TFCC) injuries that proved to be useful in directing clinical management. However, dorsal peripheral tears (variants of class 1C) were not described and have rarely been reported in the literature since. We herewith present a rare case of bucket-handle tear of the TFCC. To our knowledge, this is the first case demonstrating partial separation of both the palmar and dorsal distal radioulnar ligaments (DRULs) from the articular disc. The particular wrist magnetic resonance (MR) arthrographic findings of this unusual complex peripheral TFCC tear (a variant of both class 1B and 1C) were nicely appreciated upon sagittal reformatted images.

Revisión de resultados en el tratamiento de las fracturas distales de radio

Es presenta un estudi de l’avaluació dels resultats en el tractament de les fractures distals de radi durant el període de temps 2008-2010 a l’Hospital Sant Joan de Reus. A partir del estudi radiogràfic i biomecànic de les fractures i mitjançant la classificació de Fernández s’avalua el tractament realitzat, en termes de funcionalitat i resultat radiogràfic posterior. Els tractament utilitzats van ser: la reducció tancada i immobilització amb guix antebraquiopalmar (ABP), la reducció tancada i fixació percutánia amb agulles de Kirchner, la reducció oberta per abordatge palmar i fixació amb placa volar DVR (Distal Volar Radius). Els resultat s’avaluen amb l’escala de valoració de Gartland modificada. Fent una revisió actualitzada de la literatura i l’evidencia que existeix pel tractament de cada tipus de fractura.

Ambulatory measurement of ankle kinetics for clinical applications.

This study aimed to design and validate the measurement of ankle kinetics (force, moment, and power) during consecutive gait cycles and in the field using an ambulatory system. An ambulatory system consisting of plantar pressure insole and inertial sensors (3D gyroscopes and 3D accelerometers) on foot and shank was used. To test this system, 12 patients and 10 healthy elderly subjects wore shoes embedding this system and walked many times across a gait lab including a force-plate surrounded by seven cameras considered as the reference system. Then, the participants walked two 50-meter trials where only the ambulatory system was used. Ankle force components and sagittal moment of ankle measured by ambulatory system showed correlation coefficient (R) and normalized RMS error (NRMSE) of more than 0.94 and less than 13% in comparison with the references system for both patients and healthy subjects. Transverse moment of ankle and ankle power showed R>0.85 and NRMSE<23%. These parameters also showed high repeatability (CMC>0.7). In contrast, the ankle coronal moment of ankle demonstrated high error and lower repeatability. Except for ankle coronal moment, the kinetic features obtained by the ambulatory system could distinguish the patients with ankle osteoarthritis from healthy subjects when measured in 50-meter trials. The proposed ambulatory system can be easily accessible in most clinics and could assess main ankle kinetics quantities with acceptable error and repeatability for clinical evaluations. This system is therefore suggested for field measurement in clinical applications.

Alteration in neuromuscular function after a 5 km running time trial.

The aim of this study was to characterize the effect of a 5 km running time trial on the neuromuscular properties of the plantar flexors. Eleven well-trained triathletes performed a series of neuromuscular tests before and immediately after the run on a 200 m indoor track. Muscle activation (twitch interpolation) and normalized EMG activity were assessed during maximal voluntary contraction (MVC) of plantar flexors. Maximal soleus H-reflexes and M-waves were evoked at rest (i.e. H (MAX) and M (MAX), respectively) and during MVC (i.e. H (SUP) and M (SUP), respectively). MVC significantly declined (-27%; P < 0.001) after the run, due to decrease in muscle activation (-8%; P < 0.05) and M (MAX)-normalized EMG activity (-13%; P < 0.05). Significant reductions in M-wave amplitudes (M (MAX): -13% and M (SUP): -16%; P < 0.05) as well as H (MAX)/M (MAX) (-37%; P < 0.01) and H (SUP)/M (SUP) (-25%; P < 0.05) ratios occurred with fatigue. Following exercise, the single twitch was characterized by lower peak torque (-16%; P < 0.001) as well as shorter contraction (-19%; P < 0.001) and half-relaxation (-24%; P < 0.001) times. In conclusion, the reduction in plantar flexors strength induced by a 5 km running time trial is caused by peripheral adjustments, which are attributable to a failure of the neuromuscular transmission and excitation-contraction coupling. Fatigue also decreased the magnitude of efferent motor outflow from spinal motor neurons to the plantar flexors and part of this suboptimal neural drive is the result of an inhibition of soleus motoneuron pool reflex excitability.

Spinal modulations accompany peripheral fatigue during prolonged tennis playing.

To examine the time course of alteration in neural process (spinal loop properties) during prolonged tennis playing, 12 competitive players performed a series of neuromuscular tests every 30 min during a 3-h match protocol. Muscle activation (twitch interpolation) and normalized EMG activity were assessed during maximal voluntary contraction (MVC) of plantar flexors. Spinal reflexes and M-waves were evoked at rest (i.e., H(max) and M(max) , respectively) and during MVC (i.e., H(sup) , V-wave, M(sup) , respectively). MVC torque declined significantly (P<0.001) across the match protocol, due to decrease (P<0.001) in muscle activation and in normalized EMG activity. The impairment in MVC was significantly correlated (r=0.77; P<0.05) with the decline in muscle activation. H(max) /M(max) (P<0.001), H(sup) /M(sup) (P<0.01) and V/M(sup) (P<0.05) ratios were depressed with fatigue and decreased by ∼80%, 46% and 61% at the end of exercise, respectively. Simultaneously, peak twitch torque and M-wave amplitude were significantly (P<0.01) altered with exercise, suggesting peripheral alterations. During prolonged tennis playing, the compromised voluntary strength capacity is linked to a reduced neural input to the working muscles. This central activation deficit partly results from a modulation in spinal loop properties.

Thyroid hormone enhances transected axonal regeneration and muscle reinnervation following rat sciatic nerve injury.

Improvement of nerve regeneration and functional recovery following nerve injury is a challenging problem in clinical research. We have already shown that following rat sciatic nerve transection, the local administration of triiodothyronine (T3) significantly increased the number and the myelination of regenerated axons. Functional recovery is a sum of the number of regenerated axons and reinnervation of denervated peripheral targets. In the present study, we investigated whether the increased number of regenerated axons by T3-treatment is linked to improved reinnervation of hind limb muscles. After transection of rat sciatic nerves, silicone or biodegradable nerve guides were implanted and filled with either T3 or phosphate buffer solution (PBS). Neuromuscular junctions (NMJs) were analyzed on gastrocnemius and plantar muscle sections stained with rhodamine alpha-bungarotoxin and neurofilament antibody. Four weeks after surgery, most end-plates (EPs) of operated limbs were still denervated and no effect of T3 on muscle reinnervation was detected at this stage of nerve repair. In contrast, after 14 weeks of nerve regeneration, T3 clearly enhanced the reinnervation of gastrocnemius and plantar EPs, demonstrated by significantly higher recovery of size and shape complexity of reinnervated EPs and also by increased acetylcholine receptor (AChRs) density on post synaptic membranes compared to PBS-treated EPs. The stimulating effect of T3 on EP reinnervation is confirmed by a higher index of compound muscle action potentials recorded in gastrocnemius muscles. In conclusion, our results provide for the first time strong evidence that T3 enhances the restoration of NMJ structure and improves synaptic transmission.

Estudi de la vegetació dels camins de ronda de Palafrugell: impacte i mesures de control de la flora introduïda

El treball consisteix en un estudi aprofundit de la vegetació que configura el veritable ecosistema mediterrani de la costa de Palafrugell (inventaris de les espècies al.lòctones i les autòctones) fent una sèrie de propostes de millora de les zones més degradades intentant evitar la colonització de les espècies no desitjables amb la posterior elaboració d’un llistat d’espècies aconsellables per plantar en espais públics enjardinats

Twitch potentia induced by two different modalities of neuromuscular electrical stimulation: implications for motor unit recruitment.

INTRODUCTION: We tested the hypothesis that twitch potentiation would be greater following conventional (CONV) neuromuscular electrical stimulation (50-µs pulse width and 25-Hz frequency) compared with wide-pulse high-frequency (WPHF) neuromuscular electrical stimulation (1-ms, 100-Hz) and voluntary (VOL) contractions, because of specificities in motor unit recruitment (random in CONV vs. random and orderly in WPHF vs. orderly in VOL). METHODS: A single twitch was evoked by means of tibial nerve stimulation before and 2 s after CONV, WPHF, and VOL conditioning contractions of the plantar flexors (intensity: 10% maximal voluntary contraction; duration: 10 s) in 13 young healthy subjects. RESULTS: Peak twitch increased (P<0.05) after CONV (+4.5±4.0%) and WPHF (+3.3±5.9%), with no difference between the 2 modalities, whereas no changes were observed after VOL (+0.8±2.6%). CONCLUSIONS: Our results demonstrate that presumed differences in motor unit recruitment between WPHF and CONV do not seem to influence twitch potentiation results.

Malaria entomological risk factors in relation to land cover in the Lower Caura River Basin, Venezuela

To explore the effects of deforestation and resulting differences in vegetation and land cover on entomological parameters, such as anopheline species composition, abundance, biting rate, parity and entomological inoculation rate (EIR), three villages were selected in the Lower Caura River Basin, state of Bolívar, Venezuela. All-night mosquito collections were conducted between March 2008-January 2009 using CDC light traps and Mosquito Magnet(r) Liberty Plus. Human landing catches were performed between 06:00 pm-10:00 pm, when anophelines were most active. Four types of vegetation were identified. The Annual Parasite Index was not correlated with the type of vegetation. The least abundantly forested village had the highest anopheline abundance, biting rate and species diversity. Anopheles darlingi and Anopheles nuneztovari were the most abundant species and were collected in all three villages. Both species showed unique biting cycles. The more abundantly forested village of El Palmar reported the highest EIR. The results confirmed previous observations that the impacts of deforestation and resulting changes in vegetation cover on malaria transmission are complex and vary locally.

Analysing deltamethrin susceptibility and pyrethroid esterase activity variations in sylvatic and domestic Triatoma infestans at the embryonic stage

The aim of the present work was to study the deltamethrin susceptibility of eggs from Triatoma infestans populations and the contribution of pyrethroid esterases to deltamethrin degradation. Insects were collected from sylvatic areas, including Veinte de Octubre and Kirus-Mayu (Bolivia) and from domiciliary areas, including El Palmar (Bolivia) and La Pista (Argentina). Deltamethrin susceptibility was determined by dose-response bioassays. Serial dilutions of deltamethrin (0.0005-1 mg/mL) were topically applied to 12-day-old eggs. Samples from El Palmar had the highest lethal dose ratio (LDR) value (44.90) compared to the susceptible reference strain (NFS), whereas the Veinte de Octubre samples had the lowest value (0.50). Pyrethroid esterases were evaluated using 7-coumaryl permethrate (7-CP) on individually homogenised eggs from each population and from NFS. The El Palmar and La Pista samples contained 40.11 and 36.64 pmol/min/mg protein, respectively, and these values were statistically similar to NFS (34.92 pmol/min/mg protein) and different from Kirus-Mayu and Veinte de Octubre (27.49 and 22.69 pmol/min/mg protein, respectively). The toxicological data indicate that the domestic populations were resistant to deltamethrin, but no statistical contribution of 7-CP esterases was observed. The sylvatic populations had similar LDR values to NFS, but lower 7-CP esterase activities. Moreover, this is the first study of the pyrethroid esterases on T. infestans eggs employing a specific substrate (7-CP).

Free flaps in surgical dermatology. Comparison between fasciocutaneous and myocutaneous free flaps in facial reconstructions.

BACKGROUND Dermatologic surgeons routinely harvest pedicled flaps at distance with an axial or random pattern to repair facial defects. These types of skin flaps are time-consuming and have high economic, social and personal costs. These drawbacks could be avoided with the introduction of a single-step transfer of free flaps to the recipient site, with microvascular anastomosis. OBJECTIVE To demonstrate that better results are obtained with myocutaneous or fasciocutaneous free flaps and which one is more suitable in surgical dermatology. MATERIAL AND METHODS We selected two patients of opposite sexes and similar ages who had undergone Mohs surgery to remove recurrent malignant tumors that were located in the upper cheek bordering the zygomatic zone. The woman was treated with a fasciocutaneous radial free flap and the man with a rectus abdominis free flap. RESULTS Both patients had excellent immediate postoperative outcomes. Complications observed in the male patient were related to a previous pulmonary alteration. The fasciocutaneous radial free flap reconstruction was easier to perform than the rectus abdominis free flap; nevertheless, the radial free flap is very thin and, although the palmaris longus tendon is used, it does not yield enough volume, requiring later use of implants. In contrast, the rectus abdominis free flap transfers a wide flap with enough fat tissue to expand in the future. As for the cosmetic results regarding the donor site, the rectus abdominis free flap produces better-looking scars, since secondary defects of the palmar surface cannot be directly closed and usually require grafting - a situation that some patients do not accept. CONCLUSIONS In surgical dermatology, each case, once the tumor has been extirpated, requires its own reconstructive technique. The radial free flap is suitable for thin patients who are willing to cover their arm with a shirt. The rectus abdominis free flap is best suited for obese patients with deep and voluminous defects, although it is necessary to dislocate the navel from its original position.

Alteration in neuromuscular function after a 5 km running time trial

The aim of this study was to characterize the effect of a 5 km running time trial on the neuromuscular properties of the plantar flexors. Eleven well-trained triathletes performed a series of neuromuscular tests before and immediately after the run on a 200 m indoor track. Muscle activation (twitch interpolation) and normalized EMG activity were assessed during maximal voluntary contraction (MVC) of plantar flexors. Maximal soleus H-reflexes and M-waves were evoked at rest (i.e. H (MAX) and M (MAX), respectively) and during MVC (i.e. H (SUP) and M (SUP), respectively). MVC significantly declined (-27%; P < 0.001) after the run, due to decrease in muscle activation (-8%; P < 0.05) and M (MAX)-normalized EMG activity (-13%; P < 0.05). Significant reductions in M-wave amplitudes (M (MAX): -13% and M (SUP): -16%; P < 0.05) as well as H (MAX)/M (MAX) (-37%; P < 0.01) and H (SUP)/M (SUP) (-25%; P < 0.05) ratios occurred with fatigue. Following exercise, the single twitch was characterized by lower peak torque (-16%; P < 0.001) as well as shorter contraction (-19%; P < 0.001) and half-relaxation (-24%; P < 0.001) times. In conclusion, the reduction in plantar flexors strength induced by a 5 km running time trial is caused by peripheral adjustments, which are attributable to a failure of the neuromuscular transmission and excitation-contraction coupling. Fatigue also decreased the magnitude of efferent motor outflow from spinal motor neurons to the plantar flexors and part of this suboptimal neural drive is the result of an inhibition of soleus motoneuron pool reflex excitability.

Tibio-talar arthrodesis with long anterograde nail after complex open fracture-dislocation of the ankle : P17

Introduction: Posttraumatic painful osteoarthritis of the ankle joint after fracture-dislocation often has to be treated with arthrodesis. In the presence of major soft tissue lesions and important bone loss the technique to achieve arthrodesis has to be well chosen in order to prevent hardware failure, infection of bulky implants or non-union. Methods: We present the case of a 53 year-old biker suffering of a fracture-dislocation of the ankle associated with a mayor degloving injury of the heel. After initial immobilization of the lesion by external fixation in Spain the patient was transferred to our hospital for further treatment. The degloving injury of the heel with MRSA infection was initially treated by repeated débridement, changing of the configuration of the Ex Fix and antibiotic therapy with favourable outcome. Because of the bony lesions reconstruction of the ankle-joint was juged not to be an option and arthrodesis was planned. Due to bad soft-tissue situation standard open fixtion with plate and/or screws was not wanted but an option for intramedullary nailing was taken. However the use of a standard retrograde arthrodesis nail comes with two problems: 1) Risk of infection of the heel-part of the calaneus/nail in an unstable soft tissue situation with protruding nail. And 2) talo-calcaneal arthrodesis of an initially healthy subtalar joint. Given the situation of an unstable plantar/heel flap it was decided to perform anklearthrodesis by means of an anterograde nail with static fixation in the talus and in the proximal tibia. Results:This operation was performed with minimal opening at the ankle-site in order to remove the remaining cartilage and improve direct bone to bone contact. Arthrodesis was achieved by means of an anterograde T2 Stryker tibial nail.One year after the anterograde nailing the patient walks without pain for up to 4 hours with a heel of good quality and arthrodesis is achieved. Conclusion: Tibiotalar arthrodesis in the presence of mayor soft tissue lesions and bone loss can be successfully achieved with antegrade nailing.

Critical role for the lactate transporter, monocarboxylate transporter 1 (mct1), in the regeneration of peripheral nerves

Axons, and particularly regenerating axons, have high metabolic needs in order to maintain critical functions such as axon transport and membrane depolarization. Though some of the required energy likely comes form extracellular glucose and ATP generated in the soma, we and others hypothesize that some of the energy may be supplied by lactate. Unlike glucose that requires glycolytic enzymes to produce pyruvate, lactate can be converted directly to pyruvate by lactate dehydrogenase and transported into mitochondria for oxidative metabolism. In order to be transported into or out of cells, lactate requires specific monocarboxylate transporters (MCTs), the most abundant of which is MCT1. If MCT1 and lactate are critical for nerve function and regeneration, we hypothesize that MCT1 heterozygote null mice, which appear phenotypically normal despite having approximately 40% MCT1 as compared to wildtype littermate mice, would have reduced capacity for repair following nerve injury. To investigate this, adult MCT1 heterozygote null mice or wild-type mice underwent unilateral sciatic nerve crush in the proximal thigh. We found that regeneration of the sciatic nerve, as measured by recovery of compound muscle action potentials (CMAP) in the lateral plantar muscles following proximal sciatic nerve stimulation, was delayed from a median of 21 days in wildtype mice to 38.5 days in MCT1 heterozygote mice. In fact, half of the MCT1 heterozygote null mice had no recovery of CMAP by the endpoint of the study at 42 days, while all of the wild-type mice had recovered. In addition, the maximal amplitude of CMAP recovery in MCT1 heterozygote mull mice was reduced from a mean of 3 mV to 0.5 mV. As would be expected, the denervated gastrocnemius muscle of MCT1 heterozygote null mice remained atrophic at 42 days compared to wild-type mice. Our experiments show that lactate supplied through MCT1 is necessary for nerve regeneration. Experiments are underway to determine whether loss of MCT1 prevents nerve regrowth directly due to reduced energy supply to axons or indirectly by dysfunctional Schwann cells normally dependent on lactate supply through MCT1.