Regional genioglossus reflex responses to negative pressure pulses in people with obstructive sleep apnea

Tongue and upper airway dilator muscle movement patterns during quiet breathing vary in people with obstructive sleep apnea (OSA). Many patients have inadequate or counterproductive responses to inspiratory negative airway pressure that likely contributes to their OSA. This may be due, at least in part, to inadequate or nonhomogeneous reflex drive to different regions of the largest upper airway dilator, genioglossus. To investigate potential regional heterogeneity of genioglossus reflex responses in OSA, brief suction pulses were applied via a nasal breathing mask and an electromyogram (EMG) was recorded in four regions (anterior oblique, anterior horizontal, posterior oblique, and posterior horizontal) using intramuscular fine wire electrodes in 15 people with OSA. Genioglossus short-latency reflex excitation amplitude had regional heterogeneity (horizontal vs. oblique regions) when expressed in absolute units but homogeneity when normalized as a percentage of the immediate (100 ms) prestimulus EMG. Regional variability in reflex morphology (excitation and inhibition) was present in one-third of the participants. The minimum cross-sectional area (CSA) of the pharyngeal airway was quantified using MRI and may be related to the amplitude of the short-latency reflex response to negative pressure as we found that people with a smaller CSA tended to have a greater reflex amplitude (e.g., horizontal region r2 = 0.41, P = 0.01). These findings highlight the complexity of genioglossus reflex control, the potential for regional heterogeneity, and the functional importance of upper airway anatomy in mediating genioglossus reflex responses to rapid changes in negative pressure in OSA

Screening, Production and Antibacterial Activity of Bacteriocin from Lactobacillus spp

ABSTRACT The intent of the study is to determine the antimicrobial activity of Lactobacillus producing bacteriocin isolated from samples like dairy product (milk, curd), meat (mutton, chicken), sea food (fish, black prawns, white prawns), and alcoholic beverages (red wine, rose wine). The isolation was carried out by using de Man Rogosa Sharpe (MRS) agar medium. Total 55 isolates were obtained from 12 samples. The isolates from samples were confirmed as Lactobacillus spp. based on their morphological and biochemical characteristics. According to research work, 10 different isolates of Lactobacillus spp. were isolated from samples under study they are Lactobacillus fermentum, Lactobacillus lactis, Lactobacillus casei, Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus alimentarius, Lactobacillus buchneri, Lactobacillus sakei, Lactobacillus curvatus, and Lactobacillus farciminis. There has been an explosion of basic and applied research on Lactobacillus spp. bacteriocins, primarily due to their potential application as biopreservatives in food and food products to inhibit the growth of food borne bacterial pathogens. Isolates were subjected to antibacterial activity test using agar well diffusion method. Escherichia coli (MTCC No.118), Staphylococcus aureus (MTCC No.737) and Bacillus cereus (MTCC No.1305) were found to be sensitive to bacteriocin produced by Lactobacillus spp. whereas, Salmonella typhi (MTCC No.733) was found to be resistant to bacteriocin. Therefore, it has a potential for application as a biopreservative in different food product as such or in combination with other preservation methods

Transcranial Direct Current Stimulation Improves Isometric Time to Exhaustion of the Knee Extensors

Transcranial direct current stimulation (tDCS) can increase cortical excitability of a targeted brain area, which may affect endurance exercise performance. However, optimal electrode placement for tDCS remains unclear. We tested the effect of two different tDCS electrode montages for improving exercise performance. Nine subjects underwent a control (CON), placebo (SHAM) and two different tDCS montage sessions in a randomized design. In one tDCS session, the anodal electrode was placed over the left motor cortex and the cathodal on contralateral forehead (HEAD), while for the other montage the anodal electrode was placed over the left motor cortex and cathodal electrode above the shoulder (SHOULDER). tDCS was delivered for 10min at 2.0mA, after which participants performed an isometric time to exhaustion (TTE) test of the right knee extensors. Peripheral and central neuromuscular parameters were assessed at baseline, after tDCS application and after TTE. Heart rate (HR), ratings of perceived exertion (RPE), and leg muscle exercise-induced muscle pain (PAIN) were monitored during the TTE. TTE was longer and RPE lower in the SHOULDER condition (P0.05). In all conditions maximal voluntary contraction (MVC) significantly decreased after the TTE (P<0.05) while motor-evoked potential area (MEP) increased after TTE (P<0.05). These findings demonstrate that SHOULDER montage is more effective than HEAD montage to improve endurance performance, likely through avoiding the negative effects of the cathode on excitability

Transcranial magnetic stimulation in sport science: a commentary

The aim of this commentary is to provide a brief overview of transcranial magnetic stimulation (TMS) and highlight how this technique can be used to investigate the acute and chronic responses of the central nervous system to exercise. We characterise the neuromuscular responses to TMS and discuss how these measures can be used to investigate the mechanisms of fatigue in response to locomotor exercise. We also discuss how TMS might be used to study the corticospinal adaptations to resistance exercise training, with particular emphasis on the responses to shortening/lengthening contractions and contralateral training. The limited data to date suggest that TMS is a valuable technique for exploring the mechanisms of central fatigue and neural adaptation

Modulation in voluntary neural drive in relation to muscle soreness

The aim of this study was to investigate whether (1) spinal modulation would change after non-exhausting eccentric exercise of the plantar flexor muscles that produced muscle soreness and (2) central modulation of the motor command would be linked to the development of muscle soreness. Ten healthy subjects volunteered to perform a single bout of backward downhill walking exercise (duration 30 min, velocity 1 ms−1, negative grade −25%, load 12% of body weight). Neuromuscular test sessions [H-reflex, M-wave, maximal voluntary torque (MVT)] were performed before, immediately after, as well as 1–3 days after the exercise bout. Immediately after exercise there was a −15% decrease in MVT of the plantar flexors partly attributable to an alteration in contractile properties (−23% in electrically evoked mechanical twitch). However, MVT failed to recover before the third day whereas the contractile properties had significantly recovered within the first day. This delayed recovery of MVT was likely related to a decrement in voluntary muscle drive. The decrease in voluntary activation occurred in the absence of any variation in spinal modulation estimated from the H-reflex. Our findings suggest the development of a supraspinal modulation perhaps linked to the presence of muscle soreness

Mechanomyography versus Electromyography, in monitoring the muscular fatigue

BACKGROUND: The use of the mechanomyogram (MMG) which detects muscular vibrations generated by fused individual fiber twitches has been refined. The study addresses a comparison of the MMG and surface electromyogram (SEMG) in monitoring muscle fatigue. METHODS: The SEMG and MMG were recorded simultaneously from the same territory of motor units in two muscles (Biceps, Brachioradialis) of the human (n = 18), during sustained contraction at 25 % MVC (maximal voluntary contraction). RESULTS: The RMS (root mean square) of the SEMG and MMG increased with advancing fatigue; MF (median frequency) of the PSD (power density spectra) progressively decreased from the onset of the contraction. These findings (both muscles, all subjects), demonstrate both through the SEMG and MMG a central component of the fatigue. The MF regression slopes of MMG were closer to each other between men and women (Biceps 1.55%; Brachialis 13.2%) than were the SEMG MF slopes (Biceps 25.32%; Brachialis 17.72%), which shows a smaller inter-sex variability for the MMG vs. SEMG. CONCLUSION: The study presents another quantitative comparison (MF, RMS) of MMG and SEMG, showing that MMG signal can be used for indication of the degree of muscle activation and for monitoring the muscle fatigue when the application of SEMG is not feasible (chronical implants, adverse environments contaminated by electrical noise)

Inequality in provider continuity for children by Australian general practitioners

<p>Abstract</p> <p>Background</p> <p>There is little published on provider continuity in Australian general practice and none on its effect on inequality of care for children.</p> <p>Method</p> <p>Questionnaire administered to parents of the ACT Kindergarten Health Screen asking the name of their child's usual GP and practice address between 2001 and 2008.</p> <p>Results</p> <p>Parents of 30,789 children named 433 GPs and 141 practices. In each year, an average of 77% of parents could name both the GP and the practice, an average of 11% of parents could name only the practice, and an average of 12% of parents could name neither. In each year, 25% of parents could not name a usual GP for children of Aboriginal or Torres Straight Islander descent, or children born outside of Australia, compared to 10% of all other children (p = < 0.0001). The frequency of GPs displaying continuity of care varied over time with 19% of GPs being present in the ACT in only one year and 39% of GPs being present in every year over the eight years of study. GPs displayed two different forms of transience either by working in more than one practice in each year (5% of GPs), or by not being present in the ACT region from one year to the next (15% of GPs). Fewer parents nominated transient GPs as their child's GP compared to choosing GPs who displayed continuity (p < 0.001).</p> <p>Conclusions</p> <p>Many GPs (39%) were reported to provide continuity of care for in the ACT region and some GPs (20%) displayed transient care. Indigenous children or children born outside of Australia had less equity of access to a nominated GP than all other children. Such inequity might disappear if voluntary registration of children was adopted in Australian general practice.</p