SENSIBILIDAD DE LA GARRAPATA COMÚN DEL BOVINO Rhipicephalus (Boophilus) microplus A IVERMECTINA ESTIMADA CON EL MODELO SIGMOIDEO DE RESPUESTA MÁXIMA O DE HILL

The aim of this study was to obtain pharmacodynamics parameters to detect resistance or susceptibility of R. microplus strains to ivermectin (IVM). Two larvae samples; a susceptible strain (S) and field isolation (T) were treated with increasing concentrations of IVM using the larvae immersion technique the efficacy values measured at 24 hours were analysed with the sigmoidal maximum response so called Hill model as statistical analysis. The results obtained showed that the IVM have an all or nothing response represented by the Hill coefficient value >1 in both samples. Additionally, a low concentration effect was observed as E0 de 12.83% (S) and 9.91% (T). The field isolation larvae were susceptible to IVM in comparison with the susceptible strain by the resistance ratio (RR) which in one case was not significantly greater that one (RR50= 0.756 and RR90=1.009).

Suppression of top-down influence decreases neuronal excitability and contrast sensitivity in the V1 cortex of cat

How top-down influence affects neuronal activity and information encoding in the primary visual cortex (V1) remains elusive. This study examined changes of neuronal excitability and contrast sensitivity in cat V1 cortex after top-down influence of area 7 (A7) was modulated by transcranial direct current stimulation (tDCS). The neuronal excitability in V1 cortex was evaluated by visually evoked field potentials (VEPs), and contrast sensitivity (CS) was assessed by the inverse of threshold contrast of neurons in response to visual stimuli at different performance accuracy. We found that the amplitude of VEPs in V1 cortex lowered after top-down influence suppression with cathode-tDCS in A7, whereas VEPs in V1 did not change after sham-tDCS in A7 and nonvisual cortical area 5 (A5) or cathode-tDCS in A5 and lesioned A7. Moreover, the mean CS of V1 neurons decreased after cathode-tDCS but not sham-tDCS in A7, which could recover after tDCS effect vanished. Comparisons of neuronal contrast-response functions showed that cathode-tDCS increased the stimulus contrast required to generate the half-maximum response, with a weakly-correlated reduction in maximum response but not baseline response. Therefore, top-down influence of A7 enhanced neuronal excitability in V1 cortex and improved neuronal contrast sensitivity by both contrast gain and response gain.

Development of a method for maximum structural response prediction of a store externally carried by a jet fighter

Experimental structural response of equipment mounted in store carried externally by jet type aircraft is investigated, predicted and compared with responses suggested by military standards in this study. A representative store which is similar to Mark-83 warhead with guidance units in terms of mass and geometry is used in this study. The main scope of this study is to evaluate the structural response proposed by military standards with real test conditions and also suggest a new method with an artificial neural network to predict the maximum response. Seventy-five different flight conditions are used to train the network for low and high frequency components. Also, eight flight conditions apart from the training set of flight conditions are used to test the approach. Acceleration levels are collected in real flight conditions by the data storage system. In signal processing, vibration response is expressed as power spectral density functions in the frequency domain. Procedures to predict the maximum response from measurements are determined with statistical limits in the literature. Besides the well-known limits in literature, third-order polynomial normal and logarithmic transform is used, and the performance of the different limits is compared. It is found that the military standard vibration spectrum is conservative. Distribution-free and normal tolerance limits predicted low frequency acceleration spectral density magnitudes more accurately. Their prediction performances were better than those of the other tolerance limits and that of the military standard. Third-order polynomial transform predictions are found to be reasonable with respect to normal prediction limit and envelope approach. Finally, it can be concluded that the response prediction method proposed in this article works well for Mark-83 warheads with guidance unit carried externally by jet fighter.

Interval timing and midfrontal delta oscillations are impaired in Parkinson's disease patients with freezing of gait

Gait abnormalities and cognitive dysfunction are common in patients with Parkinson's disease (PD) and get worst with disease progression. Recent evidence has suggested a strong relationship between gait abnormalities and cognitive dysfunction in PD patients and impaired cognitive control could be one of the causes for abnormal gait patterns. However, the pathophysiological mechanisms of cognitive dysfunction in PD patients with gait problems are unclear. Here, we collected scalp electroencephalography (EEG) signals during a 7-second interval timing task to investigate the cortical mechanisms of cognitive dysfunction in PD patients with (PDFOG+, n=34) and without (PDFOG-, n=37) freezing of gait, as well as control subjects (n=37). Results showed that the PDFOG+ group exhibited the lowest maximum response density at around 7 seconds compared to PDFOG- and control groups, and this response density peak correlated with gait abnormalities as measured by FOG scores. EEG data demonstrated that PDFOG+ had decreased midfrontal delta-band power at the onset of the target cue, which was also correlated with maximum response density and FOG scores. In addition, our classifier performed better at discriminating PDFOG+ from PDFOG- and controls with an area under the curve of 0.93 when midfrontal delta power was chosen as a feature. These findings suggest that abnormal midfrontal activity in PDFOG+ is related to cognitive dysfunction and describe the mechanistic relationship between cognitive and gait functions in PDFOG+. Overall, these results could advance the development of novel biosignatures and brain stimulation approaches for PDFOG+.

Dynamic responses of clearance-type non-linear systems subjected to base harmonic excitation and their experimental verification

Realistic joints in a spacecraft structure have clearances at the interfacing parts. Many such systems can be considered to be having bilinear stiffness. A typical example is the propellant tank assembled with the structure of a spacecraft. However, it is seen that the responses of such systems subjected to base excitation are rarely reported. In this work, mathematical expressions for theoretically estimating the amplitude of its response, the frequency at which the response is the maximum and the maximum response when it is subjected to base sine excitation are derived. Several experiments are conducted on a typical such system subjecting it to different levels of base sine excitation. The frequency at which the response is the maximum reduces with the magnitude of excitation. The expressions derived in this work can be used in estimating the amplitudes of responses and their characteristics reasonably well.

The Optimal Valine to Lysine Ratio for Performance Parameters in Weaned Piglets

The optimal digestible (d) Valine (Val) to d Lysine (Lys) ratio (dVal:dLys) in weaned piglets was determined using two different regression models. A total of 200 piglets were allotted to five feeding groups and fed a corn-soybean meal based basal diet supplemented with consecutive increasing amounts of crystalline L-valine in order to reach dVal:dLys of 0.59, 0.63, 0.67, 0.71, 0.75 in the pre-starter (0–13 days) and 0.57, 0.62, 0.66, 0.70, 0.75 in the starter phase (13–43 days). In the starter phase and during the whole period, supplementing the basal diet with L-valine resulted in an improvement in body weight gain and feed intake. An exponential asymptotic (EA) and a curvilinear-plateau (CLP) regression model were fit to feed intake and body weight gain data. The estimated dVal:dLys for body weight gain was found to be 0.68 (EA, 95% of maximum response) and 0.67 (CLP) in the starter phase and 0.65 (EA, 95% of maximum response and CLP) in the total trial period. It is concluded that the supplementation of a valine-deficient basal diet for weaned piglets with L-valine improves the piglet’s weight gain and feed intake and that a dVal:dLys of 0.68 is recommended to optimize body weight gain.

Characterization of Potency of the P2Y13 Receptor Agonists: A Meta-Analysis

P2Y13 is an ADP-stimulated G-protein coupled receptor implicated in many physiological processes, including neurotransmission, metabolism, pain, and bone homeostasis. Quantitative understanding of P2Y13 activation dynamics is important for translational studies. We systematically identified PubMed annotated studies that characterized concentration-dependence of P2Y13 responses to natural and synthetic agonists. Since the comparison of the efficacy (maximum response) is difficult for studies performed in different systems, we normalized the data and conducted a meta-analysis of EC50 (concentration at half-maximum response) and Hill coefficient (slope) of P2Y13-mediated responses to different agonists. For signaling events induced by heterologously expressed P2Y13, EC50 of ADP-like agonists was 17.2 nM (95% CI: 7.7–38.5), with Hills coefficient of 4.4 (95% CI: 3.3–5.4), while ATP-like agonists had EC50 of 0.45 μM (95% CI: 0.06–3.15). For functional responses of endogenously expressed P2Y13, EC50 of ADP-like agonists was 1.76 μM (95% CI: 0.3–10.06). The EC50 of ADP-like agonists was lower for the brain P2Y13 than the blood P2Y13. ADP-like agonists were also more potent for human P2Y13 compared to rodent P2Y13. Thus, P2Y13 appears to be the most ADP-sensitive receptor characterized to date. The detailed understanding of tissue- and species-related differences in the P2Y13 response to ADP will improve the selectivity and specificity of future pharmacological compounds.

Oral Methotrexate Monotherapy for Severe Alopecia Areata: A Single Center Retrospective Case Series

Background Although several therapeutic options have been suggested for alopecia areata (AA), none of them are consistently effective, thus making the management of severe or refractory cases challenging. Several studies have recently reported the usage of methotrexate (MTX) in AA; however, the pure effect of MTX monotherapy remains elusive. Objective To evaluate efficacy and safety of oral methotrexate monotherapy for AA. Methods We retrospectively reviewed the clinical course of AA patients including pediatric cases treated with MTX monotherapy. Their detailed clinical data including original severity of AA, final treatment outcome, the duration until the maximum response, and side effects, were assessed. Statistical analysis was performed to evaluate if the clinical factors including the duration of current alopecia, age, the presence of body hair loss, and sex were associated with treatment response. Results All included patients had severe AA and failed standard therapies. Thirteen out of 15 cases demonstrated improvement during the monotherapy, and all responders demonstrated the maximum response within 1 year. Female patients had significantly better outcomes than male patients. Other factors did not significantly influence on the treatment outcome. None of the patients experienced side effects that were severe enough to terminate the treatment. Conclusions Our results support MTX monotherapy as a feasible option for severe AA patients who fail other standard therapies or for whom systemic corticosteroids are contraindicated.