Rabbit reticulocyte initiation factor 2 contains two polypeptide chains of molecular weights 48,000 and 38,000.

Eukaryotic initiation factor 2 (eIF-20) purified from rabbit reticulocyte lysates consists of equimolar amounts of two polypeptide chains of Mr 48,000 and 38,000. Determination of the molecular weight of the native factor gave a value which is consistent with a Mr of 86,000 indicating that the factor is composed of one Mr 48,000 and one Mr 38,000 polypeptide. The purified factor exhibited all the binding activities characteristic of eIF-2. The factor formed ternary complexes with Met-tRNAfMet and GTP; it bound GDP to form a binary complex; and it also possessed the property of binding a wide variety of RNA species, including reoviral mRNA, phage T3 mRNA, rRNAs, and tRNA. Furthermore, the ternary complex formed by purified eIF-2 interacted with the 40S ribosomal subunit in the presence of AUG codon to form a 40S initiation complex. These results indicate that all binding activities attributed to eIF-2 are contained in the 48,000- and 38,000-dalton polypeptides.     

Effect of Two Types of Active Recovery on Fatigue and Climbing Performance

Performing intra-session recovery is important in rock climbing due to the multiple efforts that climbers are required to make in competitions, as well as repeated climbing trials that they carry out during training sessions. Active recovery has been shown to be a better option than passive recovery. However, the type of active recovery that should be done and the influence of the type and quantity of muscle mass activated are not clear. The aim of this study was to compare the effects of recovering with easy climbing (CR) or walking (WR) on markers of fatigue and climbing performance. For this purpose, 14 subjects participated in this randomly assigned crossover protocol completing three two-minute climbing trials separated by two minutes of active recovery with the assigned method. Seven days later participants carried out the same protocol with the other recovery method. Blood lactate (La^-), rating of perceived exertion (RPE), and heart rate (HR) were analyzed as markers of fatigue and recovery, while meters climbed (MC) and handgrip force (HF) were analyzed for performance. La- values before the last climbing trial (p < 0.05; d = 0.69) and Peak La- values (p < 0.05; d = 0.77) were lower for CR than for WR. Climbers were able to ascend more meters in the set time when following the CR protocol (p < 0.01; d = 0.6), which shows the important role of the active recovery method carried out on climbing performance. There were no differences in HR, HF or RPE between protocols. A more sport-specific recovery protocol, in addition to moving great muscle mass (e.g. lower limbs), seems to enhance recovery and to facilitate lactate removal. For this reason, CR appears to be a more effective active recovery method than WR in sport rock climbing.

Key points

• Climbing recovery improved lactate removal in comparison with walking recovery.
• Subjects were able to climb more meters in a determined time when easy climbing instead of walking during recoveries.
• Activating both great muscle mass like that of the lower limbs as well as the main fatigue producing muscles (forearms in climbing) seems more effective for recovering than activating just great muscle mass.

Key words: Blood lactate, rock climbing, handgrip force, active recovery, fatigue, performance     

Mixing real and virtual components in automated manufacturing systems using PLM tools

The automation of manufacturing systems is one of the most important aspects that need to be taken care of during a design process. The Product Lifecycle Management (PLM) tools allow for the designing of automated systems even before acquiring all the hardware and/or software. This paper shows the use of this PLM kind of tools for mixing virtual and real components on an automated manufacturing system through the implementation of four different case scenarios: using the real process/real controller to the virtual process/virtual controller, real process/real controller to real process/virtual controller and finally, virtual process/real controller to virtual process/virtual controller. These scenarios will be described along with their purposes and the tools used to achieve them. Dassault Systemes DELMIA Automation is used as a PLM tool and is combined with the hardware and software required to achieve each case scenario. The case study used is the Flexible Manufacturing System in the Mechatronics laboratory at the Tecnológico de Monterrey; it’s also presented an implementation of these scenarios in a Manufacturing Systems Automation laboratory class. This study examines students’ use of technology for learning compared to more traditional learning methods. Results suggest that there is more than one good way to learn.     

Excitation of rat cerebellar Golgi cells by ethanol: further characterization of the mechanism

Background: Studies with rodents suggest that acute ethanol exposure impairs information flow through the cerebellar cortex, in part, by increasing GABAergic input to granule cells. Experiments suggest that an increase in the excitability of specialized GABAergic interneurons that regulate granule cell activity (i.e., Golgi cells [GoCs]) contributes to this effect. In GoCs, ethanol increases spontaneous action potential firing frequency, decreases the afterhyperpolarization amplitude, and depolarizes the membrane potential. Studies suggest that these effects could be mediated by inhibition of the Na⁺/K⁺ ATPase. The purpose of this study was to characterize the potential role of other GoC conductances in the mechanism of action of ethanol. Methods: Computer modeling techniques and patch‐clamp electrophysiological recordings with acute slices from rat cerebella were used for these studies. Results: Computer modeling suggested that modulation of subthreshold Na⁺ channels, hyperpolarization‐activated currents, and several K⁺ conductances could explain some but not all actions of ethanol on GoCs. Electrophysiological studies did not find evidence consistent with a contribution of these conductances. Quinidine, a nonselective blocker of several types of channels (including several K⁺ channels) that also antagonizes the Na⁺/K⁺ ATPase, reduced the effect of ethanol on GoC firing. Conclusions: These findings further support that ethanol increases GoC excitability via modulation of the Na⁺/K⁺ ATPase and suggest that a quinidine‐sensitive K⁺ channel may also play a role in the mechanism of action of ethanol.     

An insight into the sialotranscriptome of Triatoma matogrossensis, a kissing bug associated with fogo selvagem in South America

Triatoma matogrossensis is a Hemiptera that belongs to the oliveirai complex, a vector of Chagas' disease that feeds on vertebrate blood in all life stages. Hematophagous insects' salivary glands (SGs) produce potent pharmacologic compounds that counteract host hemostasis, including anticlotting, antiplatelet, and vasodilatory molecules. Exposure to T. matogrossensis was also found to be a risk factor associated with the endemic form of the autoimmune skin disease pemphigus foliaceus, which is described in the same regions where Chagas' disease is observed in Brazil. To obtain a further insight into the salivary biochemical and pharmacologic diversity of this kissing bug and to identify possible allergens that might be associated with this autoimmune disease, a cDNA library from its SGs was randomly sequenced. We present the analysis of a set of 2,230 (SG) cDNA sequences, 1,182 of which coded for proteins of a putative secretory nature.     

Ventilación mecánica no invasiva en una población anciana que ingresa en una unidad de monitorización respiratoria: causas,complicaciones y evolución al año de seguimiento

Objective

To determine the usefulness of non-invasive ventilation (NIV) in elderly patients (≥75) admitted to a respiratory monitoring unit (RMU) during hospitalization and one year later in comparison with the results from the younger age group (<75).

Material and methods

Ours is a prospective observational study carried out at the Hospital Universitario La Princesa (Madrid, Spain). We recruited all patients who were ≥75 years old and were admitted to our RMU during the period 2008-2009 with respiratory acidosis (pH <7.35 and PaCO₂ >45 mmHg) requiring NIV. We gathered data for basic variables as well as sociodemographics, history of previous pathologies, reason for hospitalization and severity, analysis upon admission and the evolution of blood gases at the start of NIV (within the first hour and after 24 hours), complications and evolution at the one-year follow-up.

Results

Mean age of the sample was 80.6 years. The Charlson index was 3.27. About half of the patients had some limitation for performing daily activities. The main reasons for admission were COPD exacerbation and heart failure. There were complications in 36% of the cases (11 renal failure and 6 atrial fibrillation). The survival rate at the one-year follow-up was 63.21%.

Conclusions

NIV is a good alternative in elderly patients admitted to the hospital with respiratory acidosis. We did not detect differences in mortality during admission between the two groups. The elderly patients were more frequently re-admitted than the younger group in the 6-12 months after hospital discharge. This could be due to their poorer functional state after hospitalization requiring NIV.     

Effects of Head and Neck Inclination on Bilateral Sternocleidomastoid EMG Activity in Healthy Subjects and in Patients with Myogenic Cranio-Cervical-Mandibular Dysfunction

This study was conducted in order to determine the effect of head and neck position on bilateral electromyographic (EMG) activity of the sternocleidomastoid muscles. The study was performed on 16 patients with myogenic cranio-cervical-mandibular dysfunction (CMD) and 16 healthy subjects. EMG recordings at rest and during swallowing of saliva and maximal voluntary clenching were performed by placing surface electrodes on the right and left sternocleidomastoid muscles. EMG activity was recorded in the left lateral decubitus position, in a darkened room and with the individual's eyes closed, under the following experimental conditions: 1. Head, neck, and body horizontally aligned; 2. Head and neck upwardly inclined with respect to the body, simulating the effect of a thick pillow, 3. Head and neck downwardly inclined with respect to the body, simulating the effect of a thin pillow. Variation of head and neck positions was determined by measuring the distance from the angle of neck and shoulder and the apex of the shoulder (SND = shoulder—neck distance) of each individual. Then, head and neck were forward or downwardly inclined with respect to the body at one-third of SND. A significantly higher contralateral EMG activity and a more asymmetric EMG activity were observed in the CMD group than in the healthy subjects (Kruskal-Wallis Test).These results suggest a different behavior of bilateral sternocleidomastoid EMG activity in CMD patients than in healthy subjects depending on the positioning of the head and neck.