Effect of electrocardiographic contamination on surface electromyography assessment of back muscles

The purpose of this study was to demonstrate the relative effect of electrocardiography (ECG) on back muscle surface electromyography (SEMG) parameters and their corresponding sensitivity in low back pain (LBP) assessment.Back muscle SEMG activities were recorded from 17 healthy subjects and 18 chronic LBP patients under static postures (straight sitting and upright standing), and dynamic action (flexion–extension). ECG cancellation based on independent component analysis (ICA) method was performed. Root mean square (RMS) and median frequency (MF) of raw and denoised SEMG data were computed respectively. Multiple comparisons were then performed.A consistent trend of change (increased MF and decreased RMS) followed ECG removal was noticed. In particular, in SEMG measurements under static postures, a significant decrease in RMS (p < 0.05) and increase in MF (p < 0.05) were found in all recording muscle groups. Level of corruption by ECG artifacts on SEMG measurements was found to be more serious and prominent in static postures than that in dynamic action. After ECG removal, significant improvements in the ability of SEMG to discriminate LBP patients from healthy subjects were seen in RMS amplitude recorded while standing (p < 0.05) and MF in all measuring conditions (p < 0.05).This study provides a more complete understanding on the relative effect of ECG contamination on back muscles SEMG parameters and LBP assessment.     

Effect of a change in step direction from a forward to a lateral target in response to a sensory perturbation

The aim of the current study was to investigate the response of healthy older and young adults to a change in step direction from a forward to a lateral target in response to a sensory perturbation. Nine healthy older (75.1 ± 6.7 years; age range, 65–81 years) and nine young adults (27 ± 3.6 years; age range, 23–31 years) participated in the study. The sensory perturbation was a visual cue presented at random times while subjects stepped over an obstacle from quiet stance. For both young and elderly subjects there was an abrupt change in the slope of both shear ground reaction forces (GRFs) of the stance limb following the perturbation. The slope and peak of the change in GRFs was greater for the young subjects and the onset significantly earlier (205 ms compared to 271 ms). Changes in the GRFs were accompanied by an increase in bilateral gluteus medius and stance limb soleus activity. A late visual cue resulted in a delayed response for elderly subjects. These data show that a stepping response to a sensory perturbation was both delayed and of less magnitude for older adults which has implications for fall risk.     

Resultados de la ventilación mecánica no invasiva en pacientes no candidatos a intubación en un hospital de subagudos. Estudio de seguimiento a un año

Elderly patients with multiple morbidity and do not intubate (DNI) orders frequently present with acute respiratory failure. There are data supporting the effectiveness of non-invasive ventilation (NIV) in this context. Our chronic disease hospital developed an integrated care clinical pathway for the use of NIV in acute respiratory failure in the emergency room and wards in 2010. The aim of this study was to assess the outcome of NIV in patients with acute respiratory failure who had a DNI order in a sub-acute care hospital.MethodsObservational, one year-follow up study. The main variables were in-hospital mortality and one year mortality. Other variables recorded were: demographics, clinical data, functional data, performance of daily life activities, dementia, arterial blood gases and re-admissions.ResultsThe study included a total of 102 patients, of which 22% were in institutions. The mean age 81 ± 7.47% males, with a Charlson index 3.7 ± 1, and Barthel index 54 ± 31. The overall mortality during the admission was 33% (34 patients). Among those patients ventilated outside the protocol indication, the mortality was significantly greater, at 71% (P > .05). Overall one-year survival rate was 46%. This survival rate was statistically higher in patients with obesity hypoventilation syndrome and a Barthel > 50.ConclusionsNIV is a useful technique in a hospital for chronic patients in an elderly population with a therapeutic ceiling. Despite their disease severity and comorbidity, acceptable survival rates are achieved. A correct case selection is needed. Obesity hypoventilation syndrome and those with Barthel index > 50 have a better prognosis.     

Multimodal information improves the rapid detection of mental fatigue

One of the major challenge in the detection of mental states is improving the accuracy of brain activity-based detectors with additional information from extracranial signals. We assessed the suitability, for real-time mental fatigue detection, of EEG, EOG and ECG measurements, taken separately or together. Thirteen subjects performed six blocks of switching tasks. For each participant, the block with the lowest error rate from the first two blocks and the block with the highest error rate from the last three blocks were discriminated with a machine learning algorithm (support vector machine). The classification scores obtained with ECG or EOG were greater than would be expected by chance (>50%) for time windows of at least 8 s. EEG was the best single mode of detection, with classification scores ranging from 80 ± 3% with a 4 s time window to 94 ± 2% with a 30 s time window. The addition of ECG and EOG features to EEG features significantly increased classification scores for short time windows (e.g., to 86 ± 3% with a 4 s time window, p < 0.001). For short time windows (up to 12 s), ECG significantly increased the discriminatory power of EEG, whereas EOG did not. These results demonstrate that mental state detection on the basis of extracerebral measurements is feasible and that a combination of EEG and ECG is particularly appropriate for the rapid detection of mental fatigue.     

Thermoregulatory responses of Holstein cows exposed to experimentally induced heat stress

Heat stress (HS) adversely influences productivity and welfare of dairy cattle. We hypothesized that the thermoregulatory mechanisms vary depending on the exposure time to HS, with a cumulative effect on the adaptive responses and thermal strain of the cow. To identify the effect of HS on adaptive thermoregulatory mechanisms and predictors of caloric balance, Holstein cows were housed in climate chambers and randomly distributed into thermoneutral (TN; n=12) or HS (n=12) treatments for 16 days. Vaginal temperature (VT), rectal temperature (Tre), respiratory rate (RR), heart rate (HR), and dry matter intake (DMI) were measured. The temperature and humidity under TN were 25.9±0.2 °C and 73.0±0.8%, respectively, and under HS were 36.3±0.3 °C and 60.9±0.9%, respectively. The RR of the HS cows increased immediately after exposure to heat and was higher (76.02±1.70bpm, p<0.001) than in the TN (39.70±0.71bpm). An increase in Tre (39.87±0.07 °C in the HS vs. 38.56±0.03 °C in the TN, p<0.001) and in VT (39.82±0.10 °C in the HS vs. 38.26±0.03 °C in the TN, p<0.001) followed the increase in RR. A decrease (p<0.05) in HR occurred in the HS (62.13±0.99bpm) compared with the TN (66.23±0.79bpm); however, the magnitude of the differences was not the same over time. The DMI was lower in HS cows from the third day (8.27±0.33 kg d⁻¹ in the HS vs. 14.03±0.29 kg d⁻¹ in the TN, p<0.001), and the reduction of DMI was strongly affected (r=−0.65) by changes in the temperature humidity index. The effect of environmental variables from the previous day on physiological parameters and DMI was more important than the immediate effect, and ambient temperature represented the most determinant factor for heat exchange. The difference in the responses to acute and chronic exposure to HS suggests an adaptive response. Thus, intense thermal stress strongly influence thermoregulatory mechanisms and the acclimation process depend critically on heat exposure time.     

The interpretation of abdominal wall muscle recruitment strategies change when the electrocardiogram (ECG) is removed from the electromyogram (EMG)

The purpose of this study was to determine the effect of the ECG artifact on low-level trunk muscle activation amplitudes and assess the effectiveness of two methods used to remove the ECG. Simulations were performed and percent error in root mean square (RMS) amplitudes were calculated from uncontaminated and contaminated EMG signals at various ECG to EMG ratios. Two methods were used to remove the ECG: (1) filtering by adaptive sampling (FAS) and (2) Butterworth high pass filter at 30 Hz (BW-30 Hz HPF). The percent error was also calculated between the ECG removed and the uncontaminated EMG RMS amplitudes. Next, the BW-30 Hz HPF method was used to remove the ECG from 3-bilateral external oblique (EO) muscle sites collected from 30 healthy subjects performing a one handed lift and replace task. Two separate ANOVA models assessed the effects of ECG on the statistical interpretation of EO recruitment strategies. One model included EMG data that contained the ECG and the other model included EMG data after the ECG was removed. Large percent errors were observed when the ECG was not removed. These errors increased with larger ECG to EMG ratios. Both removal methods reduced the errors to below 10%, but the BW-30 Hz HPF method was more time efficient in removing the ECG artifact. Different statistical findings were observed among the muscle sites for the ECG contaminated model compared to the ECG removed model, which resulted in different conclusions concerning neuromuscular control.     

Incidencia y factores explicativos de las caídas en ancianos que viven en la comunidad

Introductionfalls in the elderly are a significant health problem that can be prevented once risk factors have been identified. The objective of this study was to determine the rate of falls among elderly persons living in the community and their risk factors.Patients and methodstwo hundred ambulatory individuals aged 75 years or older attending an outpatient clinic were evaluated by personal interview. Demographic and social variables, health characteristics, use of healthcare resources and falls were studied. Bivariate analysis was performed and significant variables were entered into a conditional logistic regression analysis.Resultsthe rate of falls per year was 56.5% and rate of recurrent falls was 10.5%. The factors associated with falls in the logistic regression model were living with a spouse (OR = 0.37), taking three or more drugs (OR = 5.30), cardiovascular diseases (OR = 0.29), and taking nitrates (OR = 0.21). The factors associated with recurrent falls were change of home (OR = 11.10), living with a spouse (OR = 0.20), respiratory (OR = 6.44) and cardiovascular diseases (OR = 0.27), and taking laxatives (OR = 9.55).Conclusionsin our study the rate of falls and recurrent falls was similar to that described in other studies in western countries. Our results suggest that taking at least three medications and the use of laxatives were potentially preventable risk factors. Living with a spouse seemed to protect from both falls and recurrent falls in elderly people living in the community.     

Atrial flutter and atrial tachycardia detection using Bayesian approach with high resolution time–frequency spectrum from ECG recordings

Contemporary methods of atrial flutter (AFL), atrial tachycardia (AT), and atrial fibrillation (AF) monitoring, although superior to the standard 12-lead ECG and symptom-based monitoring, are unable to accurately discriminate between AF, AFL and AT. Thus, there is a need to develop accurate, automated, and comprehensive atrial arrhythmia detection algorithms using standard ECG recorders. To this end, we have developed a sensitive and real-time realizable algorithm for accurate AFL and AT detection using any standard electrocardiographic recording. Our novel method for automatic detection of atrial flutter and atrial tachycardia uses a Bayesian approach followed by a high resolution time–frequency spectrum. We find the TQ interval of the electrocardiogram (ECG) corresponding to atrial activity by using a particle filter (PF), and analyze the atrial activity with a high resolution time–frequency spectral method: variable frequency complex demodulation (VFCDM). The rationale for using a high-resolution time–frequency algorithm is that our approach tracks the time-varying fundamental frequency of atrial activity, where AT is within 2.0–4.0 Hz, AFL is within 4.0–5.3 Hz and NSR is found at frequencies less than 2.0 Hz. For classifications of AFL (n = 22), AT (n = 10) and normal sinus rhythms (NSR) (n = 29), we found that our approach resulted in accuracies of 0.89, 0.87 and 0.91, respectively; the overall accuracy was 0.88.     

Synthesis,electrochemistry and spectroscopy of lanthanide(III) homodinuclear complexes bridged by polyazine ligands

Six new complexes [Eu(tta)₃]₂bpm, [Er(tta)₃]₂bpm, [Tb(tta)₃]₂bpm, [Er(tta)₃]₂dpp, Pr(tta)₃bpm and Nd(tta)₃bpm (tta = 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione, bpm = 2,2′-bipyrimidine, dpp = 2,3-bis(2-pyridyl)pyrazine) were prepared and studied. The electronic absorption spectra of the complexes display tta π → π* transitions in the UV region. Cyclic voltammetry of the complexes show an irreversible reduction followed by a reversible reduction both associated with the tta ligand. Eu(III) reduction in the homodinuclear [Eu(tta)₃]₂bpm complex occurs as an irreversible reduction at less negative potentials than the tta-based reductions. Emission spectra of the Eu(III) and Tb(III) bimetallics are typical of this type of bonding motif with ligand centered (tta) absorptions resulting in 4f–4f transitions in the visible and near infrared region.     

Differential binding kinetics of replication protein A during replication and the pre- and post-incision steps of nucleotide excision repair

The ability of replication protein A (RPA) to bind single-stranded DNA (ssDNA) underlines its crucial roles during DNA replication and repair. A combination of immunofluorescence and live cell imaging of GFP-tagged RPA70 revealed that RPA, in contrast to other replication factors, does not cluster into replication foci, which is explained by its short residence time at ssDNA. In addition to replication, RPA also plays a crucial role in both the pre- and post-incision steps of nucleotide excision repair (NER). Pre-incision factors like XPC and TFIIH accumulate rapidly at locally induced UV-damage and remain visible up to 4 h. However, RPA did not reach its maximum accumulation level until 3 h after DNA damage infliction and a chromatin-bound pool remained detectable up to 8 h, probably reflecting its role during the post-incision step of NER. During the pre-incision steps of NER, RPA could only be visualized at DNA lesions in incision deficient XP-F cells, however without a substantial increase in residence time at DNA damage. Together our data show that RPA is an intrinsically highly dynamic ssDNA-binding complex during both replication and distinct steps of NER.     

Neuromuscular function during drop jumps in young and elderly males

The Hoffman reflex (H-reflex), indicating alpha-motoneuron pool activity, has been shown to be task – and in resting conditions – age dependent. How aging affects H-reflex activity during explosive movements is not clear at present. The purpose of this study was to examine the effects of aging on H-reflexes during drop jumps, and its possible role in drop jump performance. Ten young (26.8 ± 2.7 years) and twenty elderly (64.2 ± 2.7 years) subjects participated in the study. Maximal drop jump performance and soleus H-reflex response (H/M jump) 20 ms after ground contact were measured in a sledge ergometer. Maximal H-reflex, maximal M-wave, Hmax/Mmax-ratio and H-reflex excitability curves were measured during standing rest. Although in young the H-reflex response (Hmax/Mmax) was 6.5% higher during relaxed standing and 19.7% higher during drop jumps (H jump/M jump) than in the elderly group, these differences were not statistically significant. In drop jumps, the elderly subjects had lower jumping height (30.4%, p < 0.001), longer braking time (32.4%, p < 0.01), lower push-off force (18.0%, p < 0.05) and longer push-off time (31.0% p < 0.01). H jump/M jump correlated with the average push-off force (r = 0.833, p < 0.05) and with push-off time (r = ?0.857, p < 0.01) in young but not in the elderly. Correlations between H-reflex response and jumping parameters in young may indicate different jumping and activation strategies in drop jumps. However, it does not fully explain age related differences in jumping performance, since age related differences in H-reflex activity were non-significant.     

Thermal environment affects hair coat development of Norway rats

Newborn rats have limited homeothermic capabilities and little insulation. Nevertheless, rats flourish in diverse thermal environments. We hypothesized that the environmental temperature influences the development of their hair coat insulation. Rats were housed from birth (0 d) in either a cool (17 °C), moderate (25 °C), or warm (33 °C) environment. Measures were recorded from young juveniles (22 d), old juveniles (43 d), and young adults (85 d). Cool-housed rats were found to develop greater body and coat mass and a higher coat mass to body mass ratio than warm-reared rats. These results indicate that thermal environment affects the growth of the hair coat insulation of developing rats.     

An electrophysiological study of the sequential water swallowing

BackgroundSequential water swallowing (SWS) was mostly investigated by the videofluoroscopic and endoscopic methods. However some physiological features of SWS was rarely evaluated by neurophysiological techniques. Our aim was to investigate some neural and muscular changes on sequences of SWS using electromyography (EMG) methods.MethodsFifty-eight normal adults were investigated. SWS was initiated voluntarily with 50 ml and 100 ml water volumes from a cup. Submental EMG, respiratory signals, heart rate, and sympathetic skin responses (SSR) were measured during SWS.Key resultsAll parameters were increased significantly during the 100 ml SWS. During swallowing apnea period, compensatory respiration cycles occurred in 24% and 48% of participants in the 50 ml and 100 ml SWS, respectively. Heart rate increased during swallowing apnea. SSR were evoked just before and just after the SWS in more than halves of participants. A foreburst EMG in SM muscles at the initiation of SWS was recorded in 86% of normal participants. Older age was associated with a prolonged duration of the apnea period.ConclusionsAll parameters of the SWS could be recorded numerically and objectively using electrphysiological methods. These are similar to those obtained by videofluoroscopic and similar methods. The foreburst activity of the initiation of SWS may represents preparatory activity from the activation of the fast cortical descending motor pathway. Increasing heart rate and the prolonged apnea urged that older people and patients could be carefully tested for respiratory and cardiac rhythm disorders.     

Influence of cattle grazing on the density of oak seedlings and saplings in a Tabor oak forest in Israel

The effects of cattle grazing on the density of seedlings and saplings in a Tabor oak forest (Quercus ithaburensis subsp. ithaburensis) are investigated. The Tabor oak forest studied is located in a Nature Reserve in the Mediterranean region of Israel. Cattle graze at a stocking density of 0.71 head/ha for 6 months a year. The cattle grazing in the Nature Reserve is a beneficial management measure because it enhances plant species richness and reduces shrub encroachment.The impact of grazing on the densities of seedlings and young saplings was quantified in 46 large sampling plots (333 m² each) distributed over two experimental sites; the first being used as a rangeland for decades while the second is a forest patch totally free from grazing. The density and the height of Tabor oak individuals in each sampling plot were recorded. Four height categories were distinguished with a special focus on young seedlings (<0.15 m), established seedlings and young saplings (0.15 m–1 m).The density of seedlings and young sapling in the grazed Tabor oak forest were, respectively, 61% to 67% lower than in the ungrazed treatment. Implications on the continuity of the entire Tabor oak forest ecosystem are discussed. Three management measures that enable to prevent a decrease in young oak densities are proposed – reduction of stocking rate, deferment of the commencement of grazing, and fencing young seedlings.     

Muscle fibre conduction velocity and cardiorespiratory response during incremental cycling exercise in young and older individuals with different training status

We investigated the effect of ageing and training on muscle fibre conduction velocity (MFCV) and cardiorespiratory response during incremental cycling exercise. Eight young (YT; 24 ± 5 yrs) and eight older (OT; 64 ± 3 yrs) cyclists, together with eight young (YU; 27 ± 4 yrs) and eight older (OU; 63 ± 2 yrs) untrained individuals underwent to an incremental maximal test on a cycle ergometer. Ventilatory threshold (VT), respiratory compensation point (RCP) and maximal oxygen uptake (VO₂max) were identified and MFCV recorded from the vastus lateralis muscle using surface electromyography with linear arrays electrodes.In YT MFCV increased with the exercise intensity, reaching a peak of 4.99 ± 1.02 [m/s] at VT. Thereafter, and up to VO₂max, MFCV declined. In YU MFCV showed a similar trend although the peak [4.55 ± 0.53 m/s] was observed, at 75% of VO₂max an intensity higher than VT (66% of VO₂max). In both YT and YU MFCV did not decline until RPC, which occurred at 78% VO₂max in YU and at 92% VO₂max (P < 0.01) in YT. Differently from young individuals, MFCV in older subjects did not increase with exercise intensity. Moreover, maximal MFCV in OU was significantly lower [3.53 ± 0.40 m/s;] than that of YT (P < 0.005) and YU (P < 0.05).The present study shows that, especially in young individuals, MFCV reflects cardiorespiratory response during incremental dynamic cyclic exercise and hence can be used to investigate motor unit recruitment strategies.     

Visualization of cardiac health using vector cardiogram

An electrocardiogram (ECG) is an electrical recording of the heart and is used in the investigation of heart disease. It displays an apparent periodicity (of about 60–100 bpm in a healthy adult), but is not exactly periodic. The symptoms of disease may show up only during certain periods of the day, and that too may occur at random in the time scale. Visual media is a most effective tool for communication, especially when the data has subtle variations. A novel visualization technique is presented to display each ECG beat. The features like PR interval, QRS width, ST interval, are extracted from the magnitude and phase plot of different lead combinations. These features are displayed on a Cartesian quadrant as different curves, with a menu driven display strategy to visualize the ECG for a chosen interval. The scheme employed can be used to identify different types of abnormalities.     

Maintenance of CMV-specific CD8+ T cell responses and the relationship of IL-27 to IFN-γ levels with aging

We investigated whether healthy young (age ? 40) and elderly (age ? 65) people infected with cytomegalovirus (CMV) had similar levels of CD8⁺ T cell cytokine production and proliferation in response to an immunodominant CMV pp65 peptide pool given the role of CD8⁺ T cells in controlling viral infection and the association of CMV with immunosenescence. Plus, we determined the effects of aging and CMV-infectious status on plasma levels of IL-27, an innate immune cytokine with pro- and anti-inflammatory properties, as well as on its relationship to IFN-γ in that IL-27 can promote the production of IFN-γ. The results of our study show that young and elderly people had similar levels of CD8⁺ T cell proliferation, and IFN-γ and TNF-α production in response to CMV pp65 peptides. Plasma levels of IL-27 were similar between the two groups although CMV-infected young and elderly people had a trend toward increased levels of IL-27. Regardless of aging and CMV-infectious status, plasma levels of IL-27 correlated highly with plasma levels of IFN-γ. These findings suggest the maintenance of CMV pp65-specific CD8⁺ T cell proliferation and cytokine production with aging as well as the sustaining of circulatory IL-27 levels and its biological link to IFN-γ in young and elderly people irrespective of CMV infection.     

Development of a microtitre plate method for determination of phenol utilization,biofilm formation and respiratory activity by environmental bacterial isolates

Twenty-five aerobic phenol-degrading bacteria, isolated from different environmental samples on phenol agar after several subcultures in phenol broth, utilized phenol (0.2 g l⁻¹) within 24 h, but removal of phenol was more rapid when other carbon sources were also present. A microtitre plate method was developed to determine growth rate, biofilm formation and respiratory activity of the strains isolated. Pseudomonas putida strains C5 and D6 showed maximum growth (as O.D. at 600 nm), P. putida D6 and unidentified bacterial strain M1 were more stable at high concentrations of phenol (0.8 g l⁻¹), and P. putida C5 formed the greatest amount of biofilm in 0.5 g phenol l⁻¹ medium. Measurement of dehydrogenase activity as reduction of triphenyl tetrazolium chloride supported data on growth rate and biofilm formation. The microtitre plate method provided a selective method for detection of the best phenol degrading and biofilm-forming microorganisms, and was also a rapid, convenient means of studying the effect of phenol concentration on growth rate and biofilm formation.     

Effect of two-steps substrate addition on steroids 11β-hydroxylation by Curvularia lunata CL-114

In this paper, the effect of substrate 17α-hydroxypregn-4-ene-3,20-dione-21-acetate (RSA, Cortexolone-21-acetate) on the expression of cytochrome P450 and the production of hydrocortisone by Curvularia lunata CL-114 was studied. Meanwhile the effect of pH on the production of hydrocortisone was observed. Based on the effect of substrate RSA two-steps addition on cytochrome P450 expression and hydrocortisone production, a novel fermentation process was established as follows: 0.3 g/L RSA was added for the first time after 16 h of inoculation, followed by the second addition of 0.7 g/L RSA after 8 h later, then pH was regulated to constant 6.5 after another 8 h till the end of fermentation. The results showed that the novel process was much better than the original one on improving the induction of cytochrome P450 and production of hydrocortisone, and the hydrocortisone yield had achieved an improvement of 17.6% higher than that of the original process correspondingly.     

Enfermedad cardiovascular tras infección por SARS-CoV-2 en pacientes ancianos. Resultados del seguimiento anual de una cohorte de supervivientes

IntroductionAlthough the effects of SARS-CoV-2 infection on the cardiovascular system is well known in the acute phase, the cardiovascular impact of the elderly population surviving COVID-19 respiratory infection after 1 year of follow-up has not been sufficiently studied.MethodsObservational registry of 240 elderly patients (75 years or older), consecutively admitted for COVID-19 respiratory infection and survivors of the same, between March 1 and April 30, 2020, at the Hospital General Universitario de Ciudad Real. The incidence of major cardiovascular events [MACE] (cardiovascular death [CD], acute coronary syndrome [ACS], cerebrovascular disease [CVD], venous thromboembolic disease [VTE] and heart failure [HF]) was prospectively analysed.ResultsThe mean age was 83.75 ± 5.75 years. After a mean follow-up of 352.2 ± 70.4 days, 13.8% of patients died and 9.6% had MACE, the most frequent being heart failure, with no differences in severity or overall course of acute illness. In the multivariate Cox regression model, the risk of developing MACE was higher in patients with chronic obstructive pulmonary disease and (HR 4.29; 95%CI 1.62-11.39; P = .003) and loop diuretic (HR 2.99; 95%CI 1.27-7.07; P = .01).ConclusionsIn elderly COVID-19 survivors, the incidence of MACE after one year of follow-up is high, the main manifestation being heart failure.