Chronic Pain in Children and Adolescents: Diagnosis and Treatment of Primary Pain Disorders in Head, Abdomen, Muscles and Joints

Primary pain disorders (formerly “functional pain syndromes”) are common, under-diagnosed and under-treated in children and teenagers. This manuscript reviews key aspects which support understanding the development of pediatric chronic pain, points to the current pediatric chronic pain terminology, addresses effective treatment strategies, and discusses the evidence-based use of pharmacology. Common symptoms of an underlying pain vulnerability present in the three most common chronic pain disorders in pediatrics: primary headaches, centrally mediated abdominal pain syndromes, and/or chronic/recurrent musculoskeletal and joint pain. A significant number of children with repeated acute nociceptive pain episodes develop chronic pain in addition to or as a result of their underlying medical condition “chronic-on-acute pain.” We provide description of the structure and process of our interdisciplinary, rehabilitative pain clinic in Minneapolis, Minnesota, USA with accompanying data in the treatment of chronic pain symptoms that persist beyond the expected time of healing. An interdisciplinary approach combining (1) rehabilitation; (2) integrative medicine/active mind-body techniques; (3) psychology; and (4) normalizing daily school attendance, sports, social life and sleep will be presented. As a result of restored function, pain improves and commonly resolves. Opioids are not indicated for primary pain disorders, and other medications, with few exceptions, are usually not first-line therapy

A general screening strategy for peptide-based fluorogenic ligands

A systematic and general approach for identifying efficient probes for class I PDZ domains based on environment-sensitive chromophores is presented. A series of peptides derived from the C-terminal sequence of Stargazin was first used with PDZ domains of PSD-95 and Shank3 to identify the optimal position and linker length for the 4-DMAP chromophore. The results were applied to well-characterized ligand sequences for each set of domains to generate high affinity probes that retain their native sequence specificity and yield remarkable fluorescence increases upon binding. These probes constitute efficient tools to study the dynamics and regulatory mechanisms of PDZ domain-mediated interactions.Human Frontier Science Program (Strasbourg, France) ((RGP0007/2006)National Institutes of Health (U.S.) (NIH Cell Migration Consortium (GM064346))Marie Curie (Postdoctoral Fellowship (PICK-CPP)

Control of AMPA receptor activity by the extracellular loops of auxiliary proteins

At synapses throughout the mammalian brain, AMPA receptors form complexes with auxiliary proteins, including TARPs. However, how TARPs modulate AMPA receptor gating remains poorly understood. We built structural models of TARP-AMPA receptor complexes for TARPs γ2 and γ8, combining recent structural studies and de novo structure predictions. These models, combined with peptide binding assays, provide evidence for multiple interactions between GluA2 and variable extracellular loops of TARPs. Substitutions and deletions of these loops had surprisingly rich effects on the kinetics of glutamate-activated currents, without any effect on assembly. Critically, by altering the two interacting loops of γ2 and γ8, we could entirely remove all allosteric modulation of GluA2, without affecting formation of AMPA receptor-TARP complexes. Likewise, substitutions in the linker domains of GluA2 completely removed any effect of γ2 on receptor kinetics, indicating a dominant role for this previously overlooked site proximal to the AMPA receptor channel gate

Deuterium exchange and mass spectrometry reveal the interaction differences of two synthetic modulators of RXRα LBD

Protein amide hydrogen/deuterium (H/D) exchange was used to compare the interactions of two antagonists, UVI 2112 and UVI 3003, with that of the agonist, 9-cis-retinoic acid, upon binding to the human retinoid X receptor alpha ligand-binding domain (hRXRα LBD) homodimer. Analysis of the H/D content by mass spectrometry showed that in comparison to 9-cis-retinoic acid, the antagonists provide much greater protection toward deuterium exchange-in throughout the protein, suggesting that the protein–antagonist complex adopts a more restricted conformation or ensemble of conformations in which solvent accesses to amide protons are reduced. A comparison between the two antagonists shows that UVI 3003 is more protective in the C-terminal region due to the extra hydrophobic interactions derived from the atoms in the benzene ring of the carboxylic acid chain. It was less protective within regions comprising peptides 271–278 and 326–330 due to differences in conformational orientation, and/or shorter carboxylic acid chain length. Decreased deuterium exchange-in in the segment 234–239 where the residues do not involve interactions with the ligand was observed with the two antagonists, but not with 9-cis-RA. The amide protons of helix 12 of the agonist- or antagonist-occupied protein in solution have the same deuterium exchange rates as the unliganded protein, supporting a suggestion made previously that helix 12 can cover the occupied binding cavity only with the cofactor present to adjust its location