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Opis: Acute intermittent hypoxia (AIH) is an emerging technique for enhancing neuroplasticity and motor function in respiratory and limb musculature. Thus far, AIH-induced improvements in strength have been reported for upper and lower limb muscles after chronic incomplete cervical spinal cord injury (iSCI), but the underlying mechanisms have been elusive. We used high-density surface EMG (HDsEMG) to determine if motor unit discharge behaviour is altered after 15 × 60 s exposures to 9% inspired oxygen, interspersed with 21% inspired oxygen (AIH), compared to breathing only 21% air (SHAM). We recorded HDsEMG from the biceps and triceps brachii of seven individuals with iSCI during maximal elbow flexion and extension contractions, and motor unit spike trains were identified using convolutive blind source separation. After AIH, elbow flexion and extension torque increased by 54% and 59% from baseline (P = 0.003), respectively, whereas there was no change after SHAM. Across muscles, motor unit discharge rates increased by ∼4 pulses per second (P = 0.002) during maximal efforts, from before to after AIH. These results suggest that excitability and/or activation of spinal motoneurons is augmented after AIH, providing a mechanism to explain AIH-induced increases in voluntary strength. Pending validation, AIH may be helpful in conjunction with other therapies to enhance rehabilitation outcomes after incomplete spinal cord injury, due to these enhancements in motor unit function and strength.
Ključne besede: muscle strength, motoneuron function, motor unit
Objavljeno v DKUM: 02.08.2024; Ogledov: 73; Prenosov: 0

Opis: Spinal motoneuron firing depends greatly on persistent inward currents (PICs), which in turn are facilitated by the neuromodulators serotonin and noradrenaline. The aim of this study was to determine whether jaw clenching (JC) and mental stress (MS), which may increase neuromodulator release, facilitate PICs in human motoneurons. The paired motor unit (MU) technique was used to estimate PIC contribution to motoneuron firing. Surface electromyograms were collected using a 32-channel matrix on gastrocnemius medialis (GM) during voluntary, ramp, plantar flexor contractions. MU discharges were identified, and delta frequency (ΔF), a measure of recruitment–derecruitment hysteresis, was calculated. Additionally, another technique was used (VibStim) that evokes involuntary contractions that persist after cessation of combined Achilles tendon vibration and triceps surae neuromuscular electrical stimulation. VibStim measures of plantar flexor torque and soleus activity may reflect PIC activation. ΔF was not significantly altered by JC (p = .679, n = 18, 9 females) or MS (p = .147, n = 14, 5 females). However, all VibStim variables quantifying involuntary torque and muscle activity during and after vibration cessation were significantly increased in JC (p < .011, n = 20, 10 females) and some, but not all, increased in MS (p = .017–.05, n = 19, 10 females). JC and MS significantly increased the magnitude of involuntary contractions (VibStim) but had no effect on GM ΔF during voluntary contractions. Effects of increased neuromodulator release on PIC contribution to motoneuron firing might differ between synergists or be context dependent. Based on these data, the background level of voluntary contraction and, hence, both neuromodulation and ionotropic inputs could influence neuromodulatory PIC enhancement.
Ključne besede: electromyography, bistability, HD-EMG, input–output function, motor neuron
Objavljeno v DKUM: 22.05.2024; Ogledov: 100; Prenosov: 6
Celotno besedilo (3,22 MB)
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Opis: Immunosenescence is the adverse change in the human immune function during aging, leaving older people more prone to an increased risk of infections and morbidity. Acute upper respiratory tract infections (URTIs) are very common among older people, often resulting in continued morbidity and mortality. Therefore, approaches, such as consuming probiotics, that shorten the duration or even reduce the incidence of URTIs in older people are being studied. The aim of this study was to determine the effects of a multi-strain probiotic OMNi-BiOTiC® Active, which contains 11 live probiotic strains, on the incidence, duration, and severity of URTIs in older people. In this randomized double-blinded placebo-controlled study, 95 participants, with an average age of 70.9 years in the probiotic group and 69.6 years in the placebo group, were randomly allocated to two groups: 1010 cfu per day of the multi-strain probiotic intervention OMNi-BiOTiC® Active (49) or placebo (46). The incidence of URTIs in older people after 12 weeks supplementation with OMNi-BiOTiC® showed no statistically significant difference between the two groups (p = 0.5244). However, the duration of the URTI infections was statistically significantly different between the groups (p = 0.011). The participants that consumed the probiotic had an average duration of illness of 3.1 ± 1.6 days, whilst participants that received the placebo had symptoms for an average of 6.0 ± 3.8 days (p = 0.011). Statistically significant differences in lymphocyte counts in both groups after supplementation (p = 0.035 for the probiotic group and p = 0.029 for the placebo group) and between both groups were found (p = 0.009). Statistically significant differences in eosinophil (p = 0.002) and basophil counts (p = 0.001) in the probiotic groups before and after supplementation with probiotics were also found. Supplementation with the multi-strain probiotic OMNi-BiOTiC® Active may benefit older people with URTIs. Larger randomised controlled clinical trials are warranted. Clinical Trial Registration; identifier NCT05879393.
Ključne besede: upper respiratory tract infection, URTI, duration of illness, probiotics, multi-strain, older people, immune function
Objavljeno v DKUM: 27.11.2023; Ogledov: 470; Prenosov: 13
Celotno besedilo (767,38 KB)

Opis: In the present study engine/vehicle responses from a standardized transient test cycle are estimated using 13 stationary operating regimes following a previously developed methodology. The main advantage of the methodology tested is that allows obtaining an estimation of transient parameters in a stationary test bench, which requirements are much less demanding than those of the transient test bench. The objectives are: in one hand, to demonstrate that the methodology correctly estimates engine responses regardless of the fuel tested, as it is proposed in a previous paper and, on the other hand, to improve the methodology and the accuracy of the estimated parameters. The fuels tested are renewable fuels from different raw materials (biodiesel from rapeseed, sunflower, and soybean), and diesel fuel as the reference. Biodiesels were tested neat and blended (30% v/v) with diesel fuel. The engine is a common-rail light-duty one, and the standardized testing procedure used to illustrate the implementation of the methodology is the New European Driving Cycle (NEDC). Two design of experiments (DoE) of 13 runs each were analyzed. One of the DoE tested was proposed for characterizing the NEDC, referred as to CTDoE design, while the other one is a five-level fractional factorial design (FFDoE) that adequately matches the optimality criteria of orthogonality, D-optimal criterion, rotatability, and space-filling. The original methodology was improved by the implementation of a new fitting function that simulates the cold start effect over the engine parameters and by an new definition of the boundary in the [n,M] domain. These improvements showed significantly higher accuracy of the estimated engine parameters obtained, both instantaneous and accumulated, respect to the original methodology. The results obtained based on the application of the FFDoE design support the feasibility of the methodology tested. Engine performance and regulated emissions responses, such as intake air and fuel mass flow rate, thermomechanical exergy rate, exhaust gas residual heat rate, total hydrocarbons (THC), nitrogen oxides (NOx), carbon monoxide (CO) and particulate matter (PM) emissions from a transient test were instantaneously and cumulatively predicted with high accuracy using the engine responses from 13 steady-state operating modes.
Ključne besede: simulation, light duty diesel engine, transient cycle, biodiesel, design of experiments, cold start correction function
Objavljeno v DKUM: 21.09.2023; Ogledov: 350; Prenosov: 21
Celotno besedilo (13,39 MB)
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Opis: Ganoderma lucidum is a very medicinal mushroom that has been utilized in Oriental medicine for many years. It has a wide range of pharmacological and therapeutic properties, and has been used for many years as a health promoter. It contains various biologically active compounds that improve the immune system and have antioxidant, antitumor, anti-inflammatory, antifungal, and antimicrobial properties. Active compounds include triterpenoids and polysaccharides, as well as proteins, lipids, phenolics, sterols, etc. In the following review, we summarize briefly their biological activities, such as antioxidant, anti-bacterial, anti-fungal, antitumor, anti-viral, and anti-inflammatory activity. Although Ganoderma has a number of medicinal effects that have been confirmed by the in vitro and in vivo studies summarised in this review, there are some limitations. Clinical trials face mainly a lack of pure constituents. Accurate identification of the compounds obtained is also problematic. In addition, most of the included studies were small, and there were concerns about the methodological quality of each study. Studies have shown that Ganoderma has valuable potential for the prevention and treatment of cancer. In any case, G. lucidum cannot be used as first-line therapy for cancer.
Ključne besede: Ganoderma lucidum, bioactive function, active compounds, polysaccharides, triterpenoids
Objavljeno v DKUM: 16.08.2023; Ogledov: 324; Prenosov: 31
Celotno besedilo (1,26 MB)
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