Actions of β2-adrenoceptor agonist drug on human soleus muscle contraction.

PURPOSE: The effects of β(2)-agonists on human skeletal muscle contractile properties, particularly on slow fibers, are unclear. Moreover, it remains to be ascertained whether central motor drive (CMD) during voluntary contractions could counter for eventual contractile alterations induced by β(2)-agonists. This study investigated central and peripheral neuromuscular adjustments induced by β(2)-agonist terbutaline on a predominantly slow human muscle, the soleus. METHODS: Ten recreationally active men ingested either a single dose of 8 mg of terbutaline or placebo in a randomized double-blind order (two experimental sessions). Isometric plantarflexion torque was measured during single and tetanic (10 and 100 Hz) stimulations as well as during submaximal and maximal voluntary contractions (MVC). Twitch peak torque and half-relaxation time were calculated. CMD was estimated via soleus electromyographic recordings obtained during voluntary contractions performed at approximately 50% MVC. RESULTS: MVC and twitch peak torque were not modified by terbutaline. Twitch half-relaxation time was 28% shorter after terbutaline administration compared with placebo (P < 0.001). Tetanic torques at 10 and 100 Hz were significantly lower after terbutaline intake compared with placebo (-40% and -24% respectively, P < 0.001). Despite comparable torque of submaximal voluntary contractions in the two conditions, CMD was 7% higher after terbutaline ingestion compared with placebo (P < 0.01). CONCLUSION: These results provide evidence that terbutaline modulates the contractility of the slow soleus muscle and suggest that the increased CMD during submaximal contractions may be viewed as a compensatory adjustment of the central nervous system to counter the weakening action induced by terbutaline on the contractile function of slow muscle fibers.

Improving Transition Outcomes: CASE (Career And Self Awareness) Prototype: Basic Points

Basic Points about the CASE (Career And Self Awareness) prototype.

Lack of Smad3 signaling leads to impaired skeletal muscle regeneration.

Smad3 is a key intracellular signaling mediator for both transforming growth factor-β and myostatin, two major regulators of skeletal muscle growth. Previous published work has revealed pronounced muscle atrophy together with impaired satellite cell functionality in Smad3-null muscles. In the present study, we have further validated a role for Smad3 signaling in skeletal muscle regeneration. Here, we show that Smad3-null mice had incomplete recovery of muscle weight and myofiber size after muscle injury. Histological/immunohistochemical analysis suggested impaired inflammatory response and reduced number of activated myoblasts during the early stages of muscle regeneration in the tibialis anterior muscle of Smad3-null mice. Nascent myofibers formed after muscle injury were also reduced in number. Moreover, Smad3-null regenerated muscle had decreased oxidative enzyme activity and impaired mitochondrial biogenesis, evident by the downregulation of the gene encoding mitochondrial transcription factor A, a master regulator of mitochondrial biogenesis. Consistent with known Smad3 function, reduced fibrotic tissue formation was also seen in regenerated Smad3-null muscle. In conclusion, Smad3 deficiency leads to impaired muscle regeneration, which underscores an essential role of Smad3 in postnatal myogenesis. Given the negative role of myostatin during muscle regeneration, the increased expression of myostatin observed in Smad3-null muscle may contribute to the regeneration defects.

Principal curves and principal oriented points

Principal curves have been defined Hastie and Stuetzle (JASA, 1989) assmooth curves passing through the middle of a multidimensional dataset. They are nonlinear generalizations of the first principalcomponent, a characterization of which is the basis for the principalcurves definition.In this paper we propose an alternative approach based on a differentproperty of principal components. Consider a point in the space wherea multivariate normal is defined and, for each hyperplane containingthat point, compute the total variance of the normal distributionconditioned to belong to that hyperplane. Choose now the hyperplaneminimizing this conditional total variance and look for thecorresponding conditional mean. The first principal component of theoriginal distribution passes by this conditional mean and it isorthogonal to that hyperplane. This property is easily generalized todata sets with nonlinear structure. Repeating the search from differentstarting points, many points analogous to conditional means are found.We call them principal oriented points. When a one-dimensional curveruns the set of these special points it is called principal curve oforiented points. Successive principal curves are recursively definedfrom a generalization of the total variance.

Les douze points-clés de la rééducation après une prothèse totale de genou [The 12 keypoints for rehabilitation after total knee arthroplasty].

The rehabilitation process after total knee arthroplasty (TKA) relies more and more on the family doctor. Many factors contribute to this development: the constantly increasing number of TKA performed, the reduced length of stay at the hospital and the rehabilitation process after TKA requiring care for 3 to 4 months. After this time, it is also of major importance to encourage patients to take up physical activities in order to limit the negative effects of sedentarity. The goal of this paper is to give family doctors an overview of the current knowledge in the area of rehabilitation after TKA for physicians.

Record keeping by Swiss physiotherapists--a national survey of knowledge regarding legal requirements.

A national survey conducted in Switzerland aimed to evaluate the knowledge of physiotherapists regarding the legal requirements for record keeping and to collect their feedback about record keeping in general. Three physiotherapists from various professional practice groups and a lawyer specialised in health law developed a questionnaire that was sent to the 7,753 members of two existing national associations of physiotherapists. The questionnaire evaluated the participants' knowledge by calculating a score of legal knowledge, which had a maximum of 30 points. We included 825 questionnaires in the analysis. The large majority (83.4%) of participants confessed an ignorance of the legal requirements concerning record keeping prior to the survey. The average score of legal compatibility was 8 points. The younger age of the physiotherapists was a significant predictor of having knowledge of the legal requirements for record keeping (p <0.001). The participants had an appreciation of the value of records, but they did not have the relevant knowledge regarding the legal requirements for keeping records. The participants blamed a lack of time and remuneration for their failure to keep records according to known requirements. All practising allied health professionals should keep up-to-date and accurate records that conform to active legal requirements and existing international guidelines. In addition to the existing legal requirements, the emergence of e-health and the electronic era will trigger major changes in patient record management by physiotherapists.

Voyages et VIH: les points-clés [Key aspects regarding HIV and travel].

The risk of contracting a sexually transmitted infection while traveling abroad is increased in certain populations. Pre-travel consultation should include the education of travelers on the prevalence of HIV in the countries visited and on appropriate prevention measures. In patients infected with HIV (PHIV), combined antiretroviral therapy (cART) improves immunity, enabling them to travel with less risk for their health. Pre-travel consultation of PVIH has the following objectives: to determine immune status, to update immunization and to decide on anti-malaria drug prophylaxis, taking into account potential drug interactions with antiretroviral therapy. Vaccine response and duration of protection is shorter-lived in PVIH, especially if the CD4 count is below 200 cells/mm3 and the HIV viral load is detectable. Therefore cART is a cornerstone for disease prevention among patients infected with HIV who travel.

Avaliacao dos resultados cirurgicos com a tecnica da resseccao do musculo de Muller-conjuntiva no tratamento da blefaroptose. [Evaluation of the surgery results of Muller's muscle-conjunctival resection in the treatment of blepharoptosis]

OBJECTIVE: To evaluate the results of Muller's muscle-conjunctival resection for correction of blepharoptosis and to discuss the advantages of this procedure. METHODS: 38 patients (39 eyelids) were submitted to Muller's muscle-conjunctival resection. Blepharoptosis varied from 1.0 mm to 3.0 mm (mean: 2.0 mm). The amount of eyelid elevation produced by phenylephrine guided the amount of tissue to be resected. RESULT: 33 eyelids (85%) treated with this procedure were cosmetically acceptable. CONCLUSIONS: Muller's muscle-conjunctival resection procedure is a relatively simple technique for blepharoptosis, with good levator function and positive 10% phenylephrine test. The advantages are: preservation of tarsus and predictable results.

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.