Consensus statement: the development of a national Canadian Migraine Strategy.

BACKGROUND: Migraine is a significant cause of suffering and disability in the Canadian population, and imposes a major cost on Canadian Society. Based on current medical science, much more could be done to provide better comprehensive medical care to the millions of individuals with migraine in Canada. OBJECTIVE: To propose and design a national Canadian Migraine Strategy which could be implemented to reduce migraine related disability in Canada. METHODS: A multidisciplinary task force of the Canadian Headache Society met for a Canadian Migraine Summit Meeting in Halifax, Nova Scotia in June, 2009. Pertinent literature was reviewed and a consensus document was produced based upon the round table discussion at the meeting. RESULTS: The outline of a national Canadian Migraine Strategy was created. This strategy is based on the chronic disease management model, and would include: an outline of what constitutes appropriate migraine care for Canadians, educational programs (for health care professionals, individuals with migraine, and the general public), research programs, and the development of the necessary organizations and partnerships to develop further and implement the Canadian Migraine Strategy. CONCLUSIONS: Based upon the medical literature and expert discussion at the meeting, a national Canadian Migraine Strategy with a patient self-management focus has the potential to improve patient care and reduce headache related disability in Canada.

Interactions of the RNA-binding protein Hfq with cspA mRNA, encoding the major cold shock protein.

CspA, a small protein that is highly induced by cold shock, is encoded by a monocistronic mRNA of 428 nucleotides (nt) whose half-life and abundance are greatly increased following cold shock. We show here that in vitro cspA mRNA can bind multiple copies of Hfq, a hexameric Sm-like protein which promotes a variety of RNA-RNA interactions. Binding of the first Hfq hexamer occurs with an apparent K(d) (dissociation constant) of <40 nM; up to seven additional hexamers can bind sequentially at higher concentrations. Known ligands of Hfq, including the small regulatory RNA, RyhB, compete with cspA mRNA. Several experiments suggest that the first binding site to be occupied by Hfq is located at or near the 3' end of cspA mRNA. The consequences of limited Hfq binding in vitro include nearly total inhibition of RNase E cleavage at a site approximately 35 nt from the 3' end of the mRNA, stimulation of polyadenylation by poly(A) polymerase 1, and subsequent exonucleolytic degradation by polynucleotide phosphorylase. We propose that Hfq may play a facilitating role in the metabolism of cspA mRNA.

Immunostaining of peripheral nerves and other tissues in whole mount preparations from hatchling cephalopods.

Newly hatched paralarvae ("hatchlings") or late-stage embryos of Loligo opalescens were dissected and pieces of tissue removed for immunostaining as flat whole mounts. The general layout of the peripheral nervous system in the mantle and gills was investigated using antisera for tubulin and FMRFamide. Primary sensory neurons are densely distributed in the outer mantle epidermis and show strong FMRFamide immunoreactivity. Their axons form a plexus in the underlying dermis, but do not appear to innervate the chromatophore muscles, which are well visualized with anti-tubulin. Some cross the muscle layer and enter the stellate ganglia via the stellar nerves. The stellate ganglion neuropil contains a rich FMRFamide-immunoreactive mass of axons. It is suggested that these axons originate in large part from sensory neurons in the skin and that the known modulatory effects of FMRFamide-related peptides on motor output of the stellate ganglion may be a reflection of this sensory input in normal life. FMRFamide-immunoreactive primary sensory neurons are also abundant in the gills, but unlike those in the mantle, these cells lack cilia or other external projections. Anti-tubulin staining reveals a network of interstitial cells in the mantle dermis. Such networks may have been mistaken for nerve nets in older accounts. Additional results with Octopus vulgaris hatchlings and immunostaining for serotonin (5HT), small cardioactive peptide (SCP), and gonadotropin releasing hormone (GnRH) are briefly reported.

The biology of glass sponges.

As the most ancient extant metazoans, glass sponges (Hexactinellida) have attracted recent attention in the areas of molecular evolution and the evolution of conduction systems but they are also interesting because of their unique histology: the greater part of their soft tissue consists of a single, multinucleate syncytium that ramifies throughout the sponge. This trabecular syncytium serves both for transport and as a pathway for propagation of action potentials that trigger flagellar arrests in the flagellated chambers. The present chapter is the first comprehensive modern account of this group and covers work going back to the earliest work dealing with taxonomy, gross morphology and histology as well as dealing with more recent studies. The structure of cellular and syncytial tissues and the formation of specialised intercellular junctions are described. Experimental work on reaggregation of dissociated tissues is also covered, a process during which histocompatibility, fusion and syncytialisation have been investigated, and where the role of the cytoskeleton in tissue architecture and transport processes has been studied in depth. The siliceous skeleton is given special attention, with an account of discrete spicules and fused silica networks, their diversity and distribution, their importance as taxonomic features and the process of silication. Studies on particle capture, transport of internalised food objects and disposal of indigestible wastes are reviewed, along with production and control of the feeding current. The electrophysiology of the conduction system coordinating flagellar arrests is described. The review covers salient features of hexactinellid ecology, including an account of habitats, distribution, abundance, growth, seasonal regression, predation, mortality, regeneration, recruitment and symbiotic associations with other organisms. Work on the recently discovered hexactinellid reefs of Canada's western continental shelf, analogues of long-extinct Jurassic sponge reefs, is given special attention. Reproductive biology is another area that has benefited from recent investigations. Seasonality, gametogenesis, embryogenesis, differentiation and larval biology are now understood in broad outline, at least for some species. The process whereby the cellular early larva becomes syncytial is described. A final section deals with the classification of recent and fossil glass sponges, phylogenetic relationships within the Hexactinellida and the phylogenetic position of the group within the Porifera. Palaeontological aspects are covered in so far as they are relevant to these topics.

Clinical features and pharmacological treatment of migraine patients referred to headache specialists in Canada.

We set out to examine selected clinical characteristics of migraine patients referred to neurologists specializing in headache in Canada, and to document their pharmacological therapy both before and after consultation with the neurologist. Demographic, clinical and pharmacotherapy data were collected at the time of consultation for 606 patients referred to five headache clinics and who were given a migraine diagnosis by the neurologist. Data were analysed as part of the Canadian Headache Outpatient Registry and Database (CHORD) Project. The mean age of the migraine patients was 39.7 years; and 82.5% were female. The majority of patients suffered severe impact from their headaches. Prior to consultation, 48.7% were taking a triptan; after consultation, 97.2% were on a triptan. Before consultation, 30.9% were on a prophylactic drug; after consultation, 70.4% were. 20.8% of patients were medication overusers. Of these medication overusers, 42.4% were overusing an opiate, usually in combination with other analgesics; 21.6% were overusing a triptan. Medication changes made by the neurologists at consultation included a large increase in the use of both triptans and prophylactic medications. Medication overuse, particularly opiate overuse, remains a significant problem in patients with migraine in Canada.

Scintigraphic findings in synovial sarcoma with structural correlation.

Synovial sarcoma is a relatively rare malignant soft tissue tumour. It is highly aggressive, tends to occur in young adults and has a poor prognosis. The scintigraphic findings in 10 patients with histopathologically proven synovial sarcoma were reviewed. Most of the lesions occurred in the extremities and intense uptake of thallium was observed on 30-min and 4-h imaging in almost all cases. Thallium has an important role in the detection of possible metastatic disease and in monitoring response to therapy. The scintigraphic features of synovial sarcoma are presented and correlated with the radiographic findings.

Accurate localization of supernumerary mediastinal parathyroid adenomas by a combination of structural and functional imaging.

Reoperation for refractory or recurrent hyperparathyroidism following parathyroidectomy carries the potential for increased morbidity and the possibility of failure to localize and remove the lesion intraoperatively. Reported herein are three cases demonstrating the combined use of sestamibi scintigraphy, CT and MR for accurate localization of mediastinal parathyroid adenomas.

Central circuitry in the jellyfish Aglantha digitale IV. Pathways coordinating feeding behaviour.

The hydromedusan jellyfish Aglantha digitale feeds on small planktonic organisms carried to the margin by tentacle flexions. During feeding, the manubrium bends across ("points") and seizes the prey with flared lips. In immobilized preparations, pointing to a source of electrical stimulation was accurate, 70% of the time, to within 15 degrees. Cutting experiments showed that the conduction pathways concerned with pointing and lip flaring are located in eight radial strands consisting of a radial canal, a giant nerve axon and a bundle of small axons with FMRFamide-like immunoreactivity. Application of food juices to sites on the margin and tentacles evoked trains of impulses in the axon bundles (F events; conduction velocity 15.5+/-3.7 cm s(-1)) and in the epithelium lining the radial canals (E events; conduction velocity 28.5+/-3.5 cm s(-1)). Impulses were conducted circularly in the outer nerve ring (F events) or in the ring canal (E events). Unilateral flexions of the manubrium during pointing arise from preferential excitation of one or more of eight longitudinal "muscle bands" in the wall of the manubrium and peduncle. Lip flaring represents symmetrical contraction of all eight bands. Cutting experiments revealed that F events mediate pointing; E events mediate lip flaring. Thus the endodermal radial canals, which in other hydromedusae mediate protective 'crumpling', provide the conduction pathway for manubrial lip flaring. Aglantha's alternative protective response--escape swimming--makes crumpling unnecessary, releasing the pathway for use in feeding. Trains of E events, generated in the manubrium during ingestion, propagate to the margin and inhibit rhythmic (slow) swimming with a duration that depended on their number and frequency. Inhibition of swimming appeared to facilitate transfer of food from the margin to the mouth, but how it comes about is unclear.

The capsular organ of Chelyosoma productum (Ascidiacea: Corellidae): a new tunicate hydrodynamic sense organ.

Chelyosoma has about 200 sense organs in the atrial wall of the branchial sac that show structural features suggestive of a role in hydrodynamic sensing. They consist of a fluid-filled capsule with an acellular diaphragm spanning an opening in the top. The floor of the capsule is a sensory macula, with 5-6 primary sensory neurons whose cilia project into the capsular cavity and whose axons go to the brain. Animals were tested for vibrational sensitivity using a loudspeaker probe. They responded by muscular contractions of the siphons and/or arrests of the branchial cilia, both of which caused changes in water flow velocity through the siphons, which were monitored non-invasively using a thermistor flow meter. The animals showed peak sensitivity at 240-260 Hz. Subsequent calibration of the loudspeaker probe indicated that the animals could detect 104 decibels re 1 microPa from a source 80 cm away. The majority of axons leaving the capsular organs go to the brain via the visceral nerve. Cutting this nerve abolished or greatly reduced responses. Electrophysiological recordings from the distal nerve stump showed bursts of electrical events following vibrational stimulation. No such records could be obtained from other major nerves and cutting them did not affect responsivity. Corella inflata, a close relative of Chelyosoma, lacks capsular organs and failed to show any responses when the source was more than 3.5 cm away. We conclude that Chelyosoma's vibration-sensing ability is due to its capsular organs and is adaptive in terms of detecting the movements of objects in the vicinity. The findings are discussed in relation to the evolution of hydrodynamic mechanoreceptors in tunicates, amphioxus and craniates.

Preferential cleavage of degradative intermediates of rpsT mRNA by the Escherichia coli RNA degradosome.

RNase E, the principal RNase capable of initiating mRNA decay, preferentially attacks 5'-monophosphorylated over 5'-triphosphorylated substrates. Site-specific cleavage in vitro of the rpsT mRNA by RNase H directed by chimeric 2'-O-methyl oligonucleotides was employed to create truncated RNAs which are identical to authentic degradative intermediates. The rates of cleavage of two such intermediates by RNase E in the RNA degradosome are significantly faster (2.5- to 8-fold) than that of intact RNA. This verifies the preference of RNase E for degradative intermediates and can explain the frequent "all-or-none" behavior of mRNAs during the decay process.

Stabilization of circular rpsT mRNA demonstrates the 5'-end dependence of RNase E action in vivo.

RNase E is the major intracellular endonuclease in Escherichia coli. Its ability to cleave susceptible substrates in vitro depends on both the cleavage site itself and the availability of an unstructured 5' terminus. To test whether RNase E activity is 5'-end-dependent in vivo in the presence of all the components of the RNA degradative machinery, a known substrate, the rpsT mRNA, has been embedded in a permuted group I intron to permit its efficient, precise circularization in E. coli. Circular rpsT mRNAs are 4-6-fold more stable in vivo than their linear counterparts. Even partial inactivation of RNase E activity further enhances this stability 6-fold. However, the stabilization of circular rpsT mRNAs depends strongly on their efficient translation. These results show unambiguously the importance of an accessible 5'-end in controlling mRNA stability in vivo and support a two-step ("looping") model for RNase E action in which the first step is end recognition and the second is actual cleavage.

Central circuitry in the jellyfish Aglantha digitale. III. The rootlet and pacemaker systems.

Tactile stimulation of the subumbrella of Aglantha digitale was found to evoke an escape swimming response similar to that evoked by stimulation of the outer surfaces of the margin but that does not involve the ring giant axon. Evidence is presented that conduction around the margin takes place via an interconnected system of rootlet interneurones. Confocal microscopy of carboxyfluorescein-filled axons showed that the rootlet neurones run out from the bases of the motor giant axons within the inner nerve ring and come into close contact with those of the neighbouring motor giant axons on either side. Transmission between the rootlet neurones has the properties of chemical synaptic transmission. A distinct type of fast excitatory postsynaptic potential (rootlet PSP) was recorded in motor giant axons following stimulation of nearby axons in 3-5 mmol l(-)(1) Mn(2+), which lowered the PSP below spike threshold. Immune labelling with anti-syntaxin 1 showed structures tentatively identified as synapses in the inner nerve ring, including some on the rootlet neurones. Neuromuscular junctions were not labelled. A secondary consequence of stimulating motor giant axons was the triggering of events in the pacemaker system. Triggering was blocked in 105 mmol l(-)(1) Mg(2+), indicating a synaptic link. Activity in the pacemaker system led indirectly to tentacle contractions (as described in earlier papers in this series), but the contractions were not as sudden or as violent as those seen when escape swimming was mediated by the ring giant axon. Events triggered in the pacemaker system fed back into the motor giants, producing postsynaptic potentials that appeared as humps in the spike after-potential. The conduction velocity of events propagating in the relay system was increased when the rootlet pathway was simultaneously excited (piggyback effect). With the addition of the rootlet pathway, the number of identified systems concerned with locomotion, feeding and tentacle contractions comes to fourteen, and the list is probably nearly complete.

Action of RNase II and polynucleotide phosphorylase against RNAs containing stem-loops of defined structure.

The 3'-->5' exoribonucleases, RNase II and polynucleotide phosphorylase (PNPase), play an essential role in degrading fragments of mRNA generated by prior cleavages by endonucleases. We have assessed the ability of small RNA substrates containing defined stem-loop structures and variable 3' extensions to impede the exonucleolytic activity of these enzymes. We find that stem-loops containing five G-C base pairs do not block either enzyme; in contrast, more stable stem-loops of 7, 9, or 11 bp block the processive action of both enzymes. Under conditions where enzyme activity is limiting, both enzymes stall and dissociate from their substrates six to nine residues, on average, from the base of a stable stem-loop structure. Our data provide a clear mechanistic explanation for the previous observation that RNase II and PNPase behave as functionally redundant.

Reconstitution of a minimal RNA degradosome demonstrates functional coordination between a 3' exonuclease and a DEAD-box RNA helicase.

The RNA degradosome is a multiprotein complex required for the degradation of highly structured RNAs. We have developed a method for reconstituting a minimal degradosome from purified proteins. Our results demonstrate that a degradosome-like complex containing RNase E, PNPase, and RhlB can form spontaneously in vitro in the absence of all other cellular components. Moreover, ATP-dependent degradation of the malEF REP RNA by the reconstituted, minimal degradosome is indistinguishable from that of degradosomes isolated from whole cells. The Rne protein serves as an essential scaffold in the reconstitution process; however, RNase E activity is not required. Rather, Rne coordinates the activation of RhlB dependent on a 3' single-stranded extension on RNA substrates. A model for degradosome-mediated degradation of structured RNA is presented with its implications for mRNA decay in Escherichia coli.

Impulse conduction in a sponge.

All-or-none propagated electrical impulses were recorded from the hexactinellid sponge Rhabdocalyptus dawsoni using suction electrodes attached to lumps of aggregated sponge tissue grafted onto the surface of pieces of the same sponge. Impulses were normally evoked by means of externally applied electrical shocks. Recorded externally using an a.c.-coupled amplifier, the electrical event was triphasic and lasted approximately 30 s; integration gave a diphasic waveform. A further integration to give the form of the membrane action potential produced a monophasic signal. Impulses propagated at 0.27+/-0.1 cm s-1 with an absolute refractory period of 29 s and a relative refractory period of approximately 150 s. Concurrent thermistor flow meter recordings confirmed that water flow through the sponge was arrested following the passage of an impulse, presumably as result of the cessation of beating of the flagella in the flagellated chambers. Tactile stimuli also evoked impulses, as did addition of particulate material to the incoming water stream. Impulses continued to propagate through the sponge during arrests, indicating that the conduction and effector systems were independent. Sponges lack nerves, and a variety of evidence indicates that the conducting tissues are the syncytial trabecular reticulum and pinacoderm layers. Na+-deficient solutions had little effect on the action potential, but propagation was blocked by 10 mmol l-1 Co2+, 1 mmol l-1 Mn2+ or 24 micromol l-1 nimodipine. Tetraethylammonium ions at 1-5 mmol l-1 also blocked propagation without prolonging the action potential. Impulse conduction in the sponge is discussed in relation to excitability and conduction in the protozoa and in plants and to non-nervous conduction in more advanced animals.

Gonadotropin-releasing hormone in mulberry cells of Saccoglossus and Ptychodera (Hemichordata: Enteropneusta).

Mulberry cells are epidermal gland cells bearing a long basal process resembling a neurite and are tentatively regarded as neurosecretory cells. They occur scattered through the ectoderm of the proboscis, collar, and anterior trunk regions of the acorn worms Saccoglossus, usually in association with concentrations of nervous tissue. They contain secretion granules that appear from electron micrographs to be released to the exterior. The granules are immunoreactive with antisera raised against mammalian and salmon gonadotropin-releasing hormone (GnRH). Similar results were obtained with another enteropneust, Ptychodera bahamensis, using antisera raised against tunicate-1 and mammalian GnRH. Mulberry cells were not found in either Cephalodiscus or Rhabdopleura (Hemichordata: Pterobranchia). Extracts of tissues from 4200 Saccoglossus contain an area of immunoreactive GnRH that is detected by an antiserum raised against lamprey GnRH when characterized by high-performance liquid chromatography and radioimmunoassay. This is the first report of the occurrence of GnRH in hemichordates, probably the most primitive group clearly belonging to the chordate lineage. The physiological function of GnRH in enteropneusts is unknown, but an exocrine function appears more likely than an endocrine or neurotransmitter role.

Degradation of mRNA in Escherichia coli: an old problem with some new twists.

Metabolic instability is a hallmark property of mRNAs in most if not all organisms and plays an essential role in facilitating rapid responses to regulatory cues. This article provides a critical examination of recent progress in the enzymology of mRNA decay in Escherichia coli, focusing on six major enzymes: RNase III, RNase E, polynucleotide phosphorylase, RNase II, poly(A) polymerase(s), and RNA helicase(s). The first major advance in our thinking about mechanisms of RNA decay has been catalyzed by the possibility that mRNA decay is orchestrated by a multicomponent mRNA-protein complex (the "degradosome"). The ramifications of this discovery are discussed and developed into mRNA decay models that integrate the properties of the ribonucleases and their associated proteins, the role of RNA structure in determining the susceptibility of an RNA to decay, and some of the known kinetic features of mRNA decay. These models propose that mRNA decay is a vectorial process initiated primarily at or near the 5' terminus of susceptible mRNAs and propagated by successive endonucleolytic cleavages catalyzed by RNase E in the degradosome. It seems likely that the degradosome can be tethered to its substrate, either physically or kinetically through a preference for monphosphorylated RNAs, accounting for the usual "all or none" nature of mRNA decay. A second recent advance in our thinking about mRNA decay is the rediscovery of polyadenylated mRNA in bacteria. Models are provided to account for the role of polyadenylation in facilitating the 3' exonucleolytic degradation of structured RNAs. Finally, we have reviewed the documented properties of several well-studied paradigms for mRNA decay in E. coli. We interpret the published data in light of our models and the properties of the degradosome. It seems likely that the study of mRNA decay is about to enter a phase in which research will focus on the structural basis for recognition of cleavage sites, on catalytic mechanisms, and on regulation of mRNA decay.

Ribonuclease E is a 5'-end-dependent endonuclease.

The selective degradation of messenger RNAs enables cells to regulate the levels of particular mRNAs in response to changes in the environment. Ribonuclease (RNase) E, a single-strand-specific endonuclease that is found in a multi-enzyme complex known as the 'degradosome', initiates the degradation of many mRNAs in Escherichia coli. Its relative lack of sequence specificity and the presence of many potential cleavage sites in mRNA substrates cannot explain why mRNA decay frequently proceeds in a net 5'-to-3' direction. I have prepared covalently closed circular derivatives of natural substrates, the rpsT mRNA encoding ribosomal protein S20 and the 9S precursor to 5S ribosomal RNA, and find that these derivatives are considerably more resistant to cleavage in vitro by RNase E than are linear molecules. Moreover, antisense oligo-deoxynucleotides complementary to the 5' end of linear substrates significantly reduce the latter's susceptibility to attack by RNase E. Finally, natural substrates with terminal 5'-triphosphate groups are poorly cleaved by RNase E in vitro, whereas 5' monophosphorylated substrates are strongly preferred. These results show that RNase E has inherent vectorial properties, with its activity depending on the 5' end of its substrates; this can account for the direction of mRNA decay in E. coli, the phenomenon of 'all or none' mRNA decay, and the stabilization provided by 5' stem-loop structures.

Reconstitution of the degradation of the mRNA for ribosomal protein S20 with purified enzymes.

Previous work has implicated poly(A) polymerase I (PAP I), encoded by the pcnB gene, in the decay of a number of RNAs from Escherichia coli. We show here that PAP I does not promote the initiation of decay of the rpsT mRNA encoding ribosomal protein S20 in vivo; however, it does facilitate the degradation of highly folded degradative intermediates by polynucleotide phosphorylase. As expected, purified degradosomes, a multi-protein complex containing, among others, RNase E, PNPase, and RhlB, generate an authentic 147-residue RNase E cleavage product from the rpsT mRNA in vitro. However, degradosomes are unable to degrade the 147-residue fragment in the presence of ATP even when it is oligoadenylated. Rather, both continuous cycles of polyadenylation and PNPase activity are necessary and sufficient for the complete decay of the 147-residue fragment in a process which can be antagonized by the action of RNase II. Moreover, both ATP and a non-hydrolyzable analog, ATPgammaS, support the PAP I and PNPase-dependent degradation of the 147-residue intermediate implying that ATPase activity, such as that which may reside in RhlB, a putative RNA helicase, is not necessarily required. Alternatively, the rpsT mRNA can be degraded in vitro by a second 3'-decay pathway which is dependent on PAP I, PNPase and ATP alone. Our results demonstrate that a hierarchy of RNA secondary structures controls access to exonucleolytic attack on 3' termini. Moreover, decay of a model mRNA can be reconstituted in vitro by a small number of purified components in a process which is more dynamic and ATP-dependent than previously imagined.