Burkina Faso: Dengue Fever

Burkina Faso is a country located in Africa and surrounded by Mali, Niger, Cote d’lvoire, Ghana, Benin and Togo. As of 2017, it has a human population of 17.3 million. Burkina Faso is one of the poorest countries and has one of the lowest literacy rates in the world. HIV/AIDS, malaria, yellow fever, and dengue fever affect thousands of people in Burkina Faso. Dengue Fever is a viral infection, which is spread by mosquitoes to humans. It is easily caught in highly populated areas. On November 6, 2017 it was reported that there have been 9,029 cases, and 18 deaths of Dengue Fever in the country. The virus has spread quickly all over the country. Currently, there are no treatments or vaccines available. The Center for Disease Control advises people to wear neutral colors, long sleeves, and securely locking all doors and windows, to limit mosquito contact

A Sweet Talk: The Molecular Systems of Perineuronal Nets in Controlling Neuronal Communication

Perineuronal nets (PNNs) are mesh-like structures, composed of a hierarchical assembly of extracellular matrix molecules in the central nervous system (CNS), ensheathing neurons and regulating plasticity. The mechanism of interactions between PNNs and neurons remain uncharacterized. In this review, we pose the question: how do PNNs regulate communication to and from neurons? We provide an overview of the current knowledge on PNNs with a focus on the cellular interactions. PNNs ensheath a subset of the neuronal population with distinct molecular aspects in different areas of the CNS. PNNs control neuronal communication through molecular interactions involving specific components of the PNNs. This review proposes that the PNNs are an integral part of neurons, crucial for the regulation of plasticity in the CNS

Altered Electroencephalographic Activity Associated with Changes in the Sleep-Wakefulness Cycle of C57BL/6J Mice in Response to a Photoperiod Shortening

Aim: Under natural conditions diurnal rhythms of biological processes of the organism are synchronized with each other and to the environmental changes by means of the circadian system. Disturbances of the latter affect hormonal levels, sleep-wakefulness cycle and cognitive performance. To study mechanisms of such perturbations animal models subjected to artificial photoperiods are often used. The goal of current study was to understand the effects of circadian rhythm disruption, caused by a short light-dark cycle regime, on activity of the cerebral cortex in rodents. Methods: We used electroencephalogram to assess the distribution of vigilance states, perform spectral analysis, and estimate the homeostatic sleep drive. In addition, we analyzed spontaneous locomotion of C57BL/6J mice under symmetric, 22-, 21-, and 20-h-long light-dark cycles using video recording and tracking methods. Results and Conclusions: We found that shortening of photoperiod caused a significant increase of slow wave activity during non-rapid eye movement sleep suggesting an elevation of sleep pressure under such conditions. While the rhythm of spontaneous locomotion was completely entrained by all light-dark cycles tested, periodic changes in the power of the theta- and gamma-frequency ranges during wakefulness gradually disappeared under 22- and 21-h-long light-dark cycles. This was associated with a significant increase in the theta-gamma phase-amplitude coupling during wakefulness. Our results thus provide deeper understanding of the mechanisms underlying the impairment of learning and memory retention, which is associated with disturbed circadian regulation.Peer reviewe

Effects of Inotropic Drugs on Mechanical Function and Oxygen Balance in Postischemic Canine Myocardium: Comparison of Dobutamine, Epinephrine, Amrinone, and Calcium Chloride

Brief ischemic episodes that induce myocardial and coronary endothelial dysfunction may alter the responses to inotropic drugs. To determine the effects of inotropic drugs in stunned myocardium, the coronary blood flow (CBF), myocardial oxygen consumption (MVO2), and regional mechanical function in response to intracoronary dobutamine, epinephrine, amrinone, and calcium chloride (CaCl2) were measured before (normal) and 30 min after a 15-min-period occlusion of the left anterior descending artery (stunned) in an open-chest canine model. Percent segment shortening (%SS) and post-systolic shortening (%PSS) were determined. Myocardial extraction of oxygen (EO2) and lactate (Elac) was calculated. The inotropic drugs increased %SS, CBF, and MVO2 in normal myocardium. Epinephrine and amrinone decreased, while dobutamine and CaCl2 did not affect EO2. The ischemia and reperfusion itself significantly reduced %SS and Elac, and increased %PSS. In stunned myocardium, the responses to inotropic drugs were not significantly altered, except that they progressively reduced %PSS and epinephrine did not affect EO2. These findings indicate that a brief episode of ischemia does not affect the mechanical and metabolic coronary flow responses to inotropic drugs, although it abolishes direct vasodilator responses to epinephrine

Transient 23–30 Hz oscillations in mouse hippocampus during exploration of novel environments

The hippocampus is a key brain structure for the encoding of new experiences and environments. Hippocampal activity shows distinct oscillatory patterns, but the relationships between oscillations and memory are not well understood. Here we describe bursts of hippocampal ∼23–30 Hz (beta2) oscillations in mice exploring novel, but not familiar, environments. In marked contrast to the relatively invariant ∼8 Hz theta rhythm, beta2 power was weak during the very first lap of the novel environment, increased sharply as the mice reencountered their start point, then persisted for only a few minutes. Novelty-evoked oscillations reflected precise synchronization of individual neurons, and participating pyramidal cells showed a selective enhancement of spatial specificity. Through focal viral manipulations, we found that novelty-evoked oscillations required functional NMDA receptors in CA3, a subregion critical for fast oscillations in vitro. These findings suggest that beta2 oscillations indicate a hippocampal dynamic state that facilitates the formation of unique contextual representations. © 2008 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58576/1/20435_ftp.pd

Effects of pH on Vascular Tone in Rabbit Basilar Arteries

Effects of pH on vascular tone and L-type Ca2+ channels were investigated using Mulvany myograph and voltage-clamp technique in rabbit basilar arteries. In rabbitbasilar arteries, high K+ produced tonic contractions by 11±0.6 mN (mean±S.E., n=19). When extracellular pH (pHo) was changed from control 7.4 to 7.9 ([alkalosis]o), K+-induced contraction was increased to 128±2.1% of the control (n=13). However, K+-induced contraction was decreased to 73±1.3% of the control at pHo 6.8 ([acidosis]o, n=4). Histamine (10 µM) also produced tonic contraction by 11±0.6 mN (n=17), which was blocked by post-application of nicardipine (1 µM). [alkalosis]o and [acidosis]o increased or decreased histamine-induced contraction to 134±5.7% and 27±7.6% of the control (n=4, 6). Since high K+- and histamine-induced tonic contractions were affected by nicardipine and pHo, the effect of pHo on voltage-dependent L-type Ca2+ channel (VDCCL) was studied. VDCCL was modulated by pHo: the peak value of Ca2+ channel current (IBa) at a holding of 0 mV decreased in [acidosis]o by 41±8.8%, whereas that increased in [alkalosis]o by 35±2.1% (n=3). These results suggested that the external pH regulates vascular tone partly via the modulation of VDCC in rabbit basilar arteries

What Electrophysiology Tells Us About Alzheimer’s Disease::A Window into the Synchronization and Connectivity of Brain Neurons

Electrophysiology provides a real-time readout of neural functions and network capability in different brain states, on temporal (fractions of milliseconds) and spatial (micro, meso, and macro) scales unmet by other methodologies. However, current international guidelines do not endorse the use of electroencephalographic (EEG)/magnetoencephalographic (MEG) biomarkers in clinical trials performed in patients with Alzheimer’s disease (AD), despite a surge in recent validated evidence. This Position Paper of the ISTAART Electrophysiology Professional Interest Area endorses consolidated and translational electrophysiological techniques applied to both experimental animal models of AD and patients, to probe the effects of AD neuropathology (i.e., brain amyloidosis, tauopathy, and neurodegeneration) on neurophysiological mechanisms underpinning neural excitation/inhibition and neurotransmission as well as brain network dynamics, synchronization, and functional connectivity reflecting thalamocortical and cortico-cortical residual capacity. Converging evidence shows relationships between abnormalities in EEG/MEG markers and cognitive deficits in groups of AD patients at different disease stages. The supporting evidence for the application of electrophysiology in AD clinical research as well as drug discovery pathways warrants an international initiative to include the use of EEG/MEG biomarkers in the main multicentric projects planned in AD patients, to produce conclusive findings challenging the present regulatory requirements and guidelines for AD studies

ENGINEERING FOR RURAL DEVELOPMENT TRACTOR MFWD BRAKING DECELERATION RESEARCH BETWEEN DIFFERENT WHEEL DRIVE

Abstract. The article presents and analyses the reasons of the braking parameter in 4×4 tractor. It is noted that the wheeled tractors are working in transport, cargo, driving with implements and without them in the fields, etc. for most of the time. The contact area with the road surface during braking decreases when increasing the driving speed and the overall dynamic stiffness of the tire changing increases the rolling resistance. However, it is worth mentioning that the tire contact with the road surface area is also dependent on the tire air pressure and improperly selected or uneven tire air pressure to increase the vehicle rolling resistance, increasing the frontwheel lead, which reduces the braking efficiency. The change of the front-wheel lead increases kinematic discrepancy between the drive wheels. These factors have negative effect for the tractor performance parameters, the transmission is loaded heavily, the power losses are increased, tires wear faster, the fuel consumption is increased. This article shows and analyses tractor deceleration between different wheel drive (4×2 and 4×4) with different driving speed. Keywords: inflation pressure, deceleration, braking, agricultural tractor. Introduction Tractors are identified as MFWD (Mechanical Front-Wheel Drive) tractors, when the front axle is driven by a mechanical drive and the front drive wheels are smaller than the rear wheels. Today, MFWD tractors are extensively used for transportation work when connected to the tractor trailer or semi-trailer. The latter considerably increases the tractor rear wheel vertical load and the rear tire deformation, but reduces the front-wheel vertical load and tire deformation. Increasing and decreasing the rear of the front tire deformation increases the actual size of the front wheel advance. This change has no harmful effects on the tractor vehicle dynamics while working, because when running a good road and at higher speed, the front wheel drive is generally unplugged. However, front-wheel accelerates change effects of the MFWD tractor braking dynamics, since the braking front axle is always automatically enabled Brake and steering systems in vehicles are the most effective gear, which directly affects the vehicle dynamics. In general, the brake system is running in the longitudinal vehicle dynamics and driving dynamics system running side. However, their effects combine when the vehicle is braked on uneven surfaces. The yaw moment braking compensates for steering control on the road. To avoid improper steering compensation vehicles have been equipped with the wheels being driven in rotation angle of the controller, designed to mitigate the impact of asymmetric braking forces and stabilize the angular deviation in vehicles Freight transportation tractors are combined with various trailers or semi-trailers. Almost 75 % of kinetic energy of the tractor-trailer combination is acquired from the trailer, so it is very important that the brake system of the trailer is sufficient to defeat the emerging kinetic energy. The stability of the compound depends on the coordination of the tractor and trailer braking systems, and also their braking efficiency. If the tractor brake system works better than the trailer brake system, the braked tractor can be pushed, and the tractor is pulled, the trail braking efficiency is better. The braking process is the best when the tractor-trailer brake efficiency is the same [4; 8; 9]. The necessity to use the brake system can occur in various situations. However, all braking systems are divided into two categories The maximum braking force developed by the vehicle wheel depends on the wheel grip to the road and vertical road reaction affecting the wheel. Operational braking intensity is always less than the maximum possible braking efficiency. Emergency braking does not exceed 5-10 % of all braking situations. However, this is a very important condition, which is important in emergency situations