Effects of Sensory Behavioral Tasks on Pain Threshold and Cortical Excitability

Background/Objective

Transcutaneous electrical stimulation has been proven to modulate nervous system activity, leading to changes in pain perception, via the peripheral sensory system, in a bottom up approach. We tested whether different sensory behavioral tasks induce significant effects in pain processing and whether these changes correlate with cortical plasticity.

Methodology/Principal Findings

This randomized parallel designed experiment included forty healthy right-handed males. Three different somatosensory tasks, including learning tasks with and without visual feedback and simple somatosensory input, were tested on pressure pain threshold and motor cortex excitability using transcranial magnetic stimulation (TMS). Sensory tasks induced hand-specific pain modulation effects. They increased pain thresholds of the left hand (which was the target to the sensory tasks) and decreased them in the right hand. TMS showed that somatosensory input decreased cortical excitability, as indexed by reduced MEP amplitudes and increased SICI. Although somatosensory tasks similarly altered pain thresholds and cortical excitability, there was no significant correlation between these variables and only the visual feedback task showed significant somatosensory learning.

Conclusions/Significance

Lack of correlation between cortical excitability and pain thresholds and lack of differential effects across tasks, but significant changes in pain thresholds suggest that analgesic effects of somatosensory tasks are not primarily associated with motor cortical neural mechanisms, thus, suggesting that subcortical neural circuits and/or spinal cord are involved with the observed effects. Identifying the neural mechanisms of somatosensory stimulation on pain may open novel possibilities for combining different targeted therapies for pain control.     

Handedness preference and switching of peptide helices. Part I: Helices based on protein amino acids

In this article, we review the relevant results obtained during almost 60 years of research on a specific aspect of stereochemistry, namely handedness preference and switches between right‐handed and left‐handed helical peptide structures generated by protein amino acids or appropriately designed, side‐chain modified analogs. In particular, we present and discuss here experimental and theoretical data on three categories of those screw‐sense issues: (i) right‐handed/left‐handed α‐helix transitions underwent by peptides rich in Asp, specific Asp β‐esters, and Asn; (ii) comparison of the preferred conformations adopted by helical host–guest peptide series, each characterized by an amino acid residue (e.g. Ile or its diastereomer aIle) endowed with two chiral centers in its chemical structure; and (iii) right‐handed (type I)/left‐handed (type II) poly‐(Pro)_n helix transitions monitored for peptides rich in Pro itself or its analogs with a pyrrolidine ring substitution, particularly at the biologically important position 4. The unique modular and chiral properties of peptides, combined with their relatively easy synthesis, the chance to shape them into the desired conformation, and the enormous chemical diversity of their coded and non‐coded α‐amino acid building blocks, offer a huge opportunity to structural chemists for applications to bioscience and nanoscience problems. Copyright © 2014 European Peptide Society and John Wiley & Sons, Ltd.     

Rotavirus Viroplasm Proteins Interact with the Cellular SUMOylation System: Implications for Viroplasm-Like Structure Formation

Posttranslational modification by SUMO provides functional flexibility to target proteins. Viruses interact extensively with the cellular SUMO modification system in order to improve their replication, and there are numerous examples of viral proteins that are SUMOylated. However, thus far the relevance of SUMOylation for rotavirus replication remains unexplored. In this study, we report that SUMOylation positively regulates rotavirus replication and viral protein production. We show that SUMO can be covalently conjugated to the viroplasm proteins VP1, VP2, NSP2, VP6, and NSP5. In addition, VP1, VP2, and NSP2 can also interact with SUMO in a noncovalent manner. We observed that an NSP5 SUMOylation mutant protein retains most of its activities, such as its interaction with VP1 and NSP2, the formation of viroplasm-like structures after the coexpression with NSP2, and the ability to complement in trans the lack of NSP5 in infected cells. However, this mutant is characterized by a high degree of phosphorylation and is impaired in the formation of viroplasm-like structures when coexpressed with VP2. These results reveal for the first time a positive role for SUMO modification in rotavirus replication, describe the SUMOylation of several viroplasm resident rotavirus proteins, and demonstrate a requirement for NSP5 SUMOylation in the production of viroplasm-like structures.     

An asymmetric NFAT1 dimer on a pseudo-palindromic kappa B-like DNA site

The crystal structure of the NFAT1 Rel homology region (RHR) bound to a pseudo-palindromic DNA site reveals an asymmetric dimer interaction between the RHR-C domains, unrelated to the contact seen in Rel dimers such as NF kappa B. Binding studies with a form of the NFAT1 RHR defective in the dimer contact show loss of cooperativity and demonstrate that the same interaction is present in solution. The structure we have determined may correspond to a functional NFAT binding mode at palindromic sites of genes induced during the anergic response to weak TCR signaling.     

The anticancer drug cytarabine does not interact with the human erythrocyte membrane

Cytarabine, an analog of deoxycytidine, is an important agent in the treatment of ovarian carcinoma, acute myeloid and lymphoblastic leukemia. Its mechanism of action has been attributed to an interference with DNA replication. The plasma membrane has received increasing attention as a possible target of antitumor drugs, where the drugs may act as growth factor antagonists and receptor blockers, interfere with mitogenic signal transduction or exert direct cytotoxic effects. Furthermore, it has been reported that drugs that exert their antiproliferative effect by interacting with DNA generally cause structural and functional membrane alterations which may be essential for growth inhibition by these agents. This paper describes the studies undertaken to determine the structural effects induced by cytarabine to cell membranes. The results showed that cytarabine, at a concentration about one thousand times higher than that found in plasma when it is therapeutically administered, did not induce significant structural perturbation in any of these systems. Therefore, it can be unambiguously concluded that this widely used anticancer drug does not interact at all with erythrocyte membranes.     

Brief communication: Evolution of a specific O allele (O1vG542A) supports unique ancestry of Native Americans

In this study, we explore the geographic and temporal distribution of a unique variant of the O blood group allele called O1v^G542A, which has been shown to be shared among Native Americans but is rare in other populations. O1v^G542A was previously reported in Native American populations in Mesoamerica and South America, and has been proposed as an ancestry informative marker. We investigated whether this allele is also found in the Tlingit and Haida, two contemporary indigenous populations from Alaska, and a pre‐Columbian population from California. If O1v^G542A is present in Na‐Dene speakers (i.e., Tlingits), it would indicate that Na‐Dene speaking groups share close ancestry with other Native American groups and support a Beringian origin of the allele, consistent with the Beringian Incubation Model. If O1v^G542A is found in pre‐Columbian populations, it would further support a Beringian origin of the allele, rather than a more recent introduction of the allele into the Americas via gene flow from one or more populations which have admixed with Native Americans over the past five centuries. We identified this allele in one Na‐Dene population at a frequency of 0.11, and one ancient California population at a frequency of 0.20. Our results support a Beringian origin of O1v^G542A, which is distributed today among all Native American groups that have been genotyped in appreciable numbers at this locus. This result is consistent with the hypothesis that Na‐Dene and other Native American populations primarily derive their ancestry from a single source population. Am J Phys Anthropol 151:649–657, 2013. © 2013 Wiley Periodicals, Inc.     

A Pilot Study Identifying a Set of microRNAs As Precise Diagnostic Biomarkers of Acute Kidney Injury

In the last decade, Acute Kidney Injury (AKI) diagnosis and therapy have not notably improved probably due to delay in the diagnosis, among other issues. Precocity and accuracy should be critical parameters in novel AKI biomarker discovery. microRNAs are key regulators of cell responses to many stimuli and they can be secreted to the extracellular environment. Therefore, they can be detected in body fluids and are emerging as novel disease biomarkers. We aimed to identify and validate serum miRNAs useful for AKI diagnosis and management. Using qRT-PCR arrays in serum samples, we determined miRNAs differentially expressed between AKI patients and healthy controls. Statistical and target prediction analysis allowed us to identify a panel of 10 serum miRNAs. This set was further validated, by qRT-PCR, in two independent cohorts of patients with relevant morbi-mortality related to AKI: Intensive Care Units (ICU) and Cardiac Surgery (CS). Statistical correlations with patient clinical parameter were performed. Our results demonstrated that the 10 selected miRNAs (miR-101-3p, miR-127-3p, miR-210-3p, miR-126-3p, miR-26b-5p, miR-29a-3p, miR-146a-5p, miR-27a-3p, miR-93-3p and miR-10a-5p) were diagnostic biomarkers of AKI in ICU patients, exhibiting areas under the curve close to 1 in ROC analysis. Outstandingly, serum miRNAs estimated before CS predicted AKI development later on, thus becoming biomarkers to predict AKI predisposition. Moreover, after surgery, the expression of the miRNAs was modulated days before serum creatinine increased, demonstrating early diagnostic value. In summary, we have identified a set of serum miRNAs as AKI biomarkers useful in clinical practice, since they demonstrate early detection and high diagnostic value and they recognize patients at risk.     

A constitutive expression system for <Emphasis Type="Italic">Pichia pastoris</Emphasis> based on the <Emphasis Type="Italic">PGK1</Emphasis> promoter

Objectives

To develop a new vector for constitutive expression in Pichia pastoris based on the endogenous glycolytic PGK1 promoter.

Results

P. pastoris plasmids bearing at least 415 bp of PGK1 promoter sequences can be used to drive plasmid integration by addition at this locus without affecting cell growth. Based on this result, a new P. pastoris integrative vector, pPICK2, was constructed bearing some features that facilitate protein production in this yeast: a ~620 bp PGK1 promoter fragment with three options of restriction sites for plasmid linearization prior to yeast transformation: a codon-optimized α-factor secretion signal, a new polylinker, and the kan marker for vector propagation in bacteria and selection of yeast transformants.

Conclusions

A new constitutive vector for P. pastoris represents an alternative platform for recombinant protein production and metabolic engineering purposes.

     

Homogeneous Canine Chest Phantom Construction: A Tool for Image Quality Optimization

Digital radiographic imaging is increasing in veterinary practice. The use of radiation demands responsibility to maintain high image quality. Low doses are necessary because workers are requested to restrain the animal. Optimizing digital systems is necessary to avoid unnecessary exposure, causing the phenomenon known as dose creep. Homogeneous phantoms are widely used to optimize image quality and dose. We developed an automatic computational methodology to classify and quantify tissues (i.e., lung tissue, adipose tissue, muscle tissue, and bone) in canine chest computed tomography exams. The thickness of each tissue was converted to simulator materials (i.e., Lucite, aluminum, and air). Dogs were separated into groups of 20 animals each according to weight. Mean weights were 6.5 ± 2.0 kg, 15.0 ± 5.0 kg, 32.0 ± 5.5 kg, and 50.0 ± 12.0 kg, for the small, medium, large, and giant groups, respectively. The one-way analysis of variance revealed significant differences in all simulator material thicknesses (p < 0.05) quantified between groups. As a result, four phantoms were constructed for dorsoventral and lateral views. In conclusion, the present methodology allows the development of phantoms of the canine chest and possibly other body regions and/or animals. The proposed phantom is a practical tool that may be employed in future work to optimize veterinary X-ray procedures.     

The Adaptor Protein Myd88 Is a Key Signaling Molecule in the Pathogenesis of Irinotecan-Induced Intestinal Mucositis

Intestinal mucositis is a common side effect of irinotecan-based anticancer regimens. Mucositis causes cell damage, bacterial/endotoxin translocation and production of cytokines including IL–1 and IL–18. These molecules and toll-like receptors (TLRs) activate a common signaling pathway that involves the Myeloid Differentiation adaptor protein, MyD88, whose role in intestinal mucositis is unknown. Then, we evaluated the involvement of TLRs and MyD88 in the pathogenesis of irinotecan-induced intestinal mucositis. MyD88-, TLR2- or TLR9-knockout mice and C57BL/6 (WT) mice were given either saline or irinotecan (75 mg/kg, i.p. for 4 days). On day 7, animal survival, diarrhea and bacteremia were assessed, and following euthanasia, samples of the ileum were obtained for morphometric analysis, myeloperoxidase (MPO) assay and measurement of pro-inflammatory markers. Irinotecan reduced the animal survival (50%) and induced a pronounced diarrhea, increased bacteremia, neutrophil accumulation in the intestinal tissue, intestinal damage and more than twofold increased expression of MyD88 (200%), TLR9 (400%), TRAF6 (236%), IL–1β (405%), IL–18 (365%), COX–2 (2,777%) and NF-κB (245%) in the WT animals when compared with saline-injected group (P<0.05). Genetic deletion of MyD88, TLR2 or TLR9 effectively controlled the signs of intestinal injury when compared with irinotecan-administered WT controls (P<0.05). In contrast to the MyD88^-/- and TLR2^-/- mice, the irinotecan-injected TLR9^-/- mice showed a reduced survival, a marked diarrhea and an enhanced expression of IL–18 versus irinotecan-injected WT controls. Additionally, the expression of MyD88 was reduced in the TLR2^-/- or TLR9^-/- mice. This study shows a critical role of the MyD88-mediated TLR2 and TLR9 signaling in the pathogenesis of irinotecan-induced intestinal mucositis.