Short-term synaptic plasticity in chronic migraine with medication overuse

The International Classification of Headache Disorders defines medication overuse headache (MOH) as headaches occurring ≥ 15 days per month for a period of at least 3 months as the result of excessive intake of acute medications such as non-steroidal analgesic drugs (NSAIDs) and triptans. Several electrophysiological studies have investigated the pathophysiology of MOH and demonstrated that patients with MOH exhibit characteristic neurophysiological abnormalities. For example, patients with MOH show response sensitisation of the somatosensory cortex in response to different repetitive sensorial stimulations, demonstrated by an initial increase in the amplitude of evoked potentials. Patients with MOH also exhibit impaired amplitude habituation, defined as the absence of a decrease in amplitude in response to repeated stimulation. Since habituation is a basic form of learning, these findings suggested that patients with MOH experience alterations in neural plasticity and learning processes. We recently assessed neural plasticity in the motor cortex of chronic migraineurs with and without medication overuse using low- and high-frequency repetitive transcranial magnetic stimulation (rTMS). We found that, depending on the duration of overuse headache, patients did not show short-term potentiation of motor evoked potentials in response to facilitatory trains of rTMS. In contrast, chronic migraineurs without medication overuse showed normal responses to inhibitory/facilitatory trains of rTMS. These observations led us to hypothesise that medication overuse induces a dysfunctional state of brain plasticity. On this premise, we further speculated that medication-induced alterations in short-term plasticity would normalise after the discontinuation of medication overuse. Withdrawal from acute medication is the first-choice strategy in the management of MOH patients, but the mechanisms involved in clinical improvement after detoxification are not clear, even though numerous structural and functional neuroimaging studies showed that detoxification is associated to normalization of gray matter volume and connectivity of several brain areas involved in pain processing, cognition and planning strategies. The aim of this study was to examine responses of patients with MOH to both low- and high-frequency rTMS over the motor cortex before and after drug withdrawal in comparison to normal subjects in order to understand the characteristics of short-term plasticity dysfunction in MOH. We found that the dysfunctions in short term potentiation mechanisms in MOH are fully reversible after withdrawal, indicating that this strategy may achieve clinical improvement by restoring the physiological brain plasticity. This finding adds to the importance of starting a withdrawal treatment as early as possible in patients with MOH in order to facilitate normalisation of brain plasticity mechanisms

Excitability of the motor cortex in patients with migraine changes with the time elapsed from the last attack

BACKGROUND: Motor-evoked potentials (MEPs) produced by single-pulse transcranial magnetic stimulation (TMS) of the motor cortex can be an objective measure of cortical excitability. Previously, MEP thresholds were found to be normal, increased, or even reduced in patients with migraine. In the present study, we determined whether the level of cortical excitability changes with the time interval from the last migraine attack, thereby accounting for the inconsistencies in previous reports. METHODS: Twenty-six patients with untreated migraine without aura (MO) underwent a MEP study between attacks. Their data were then compared to the MEP data collected from a group of 24 healthy volunteers (HVs). During the experiment, the TMS figure-of-eight coil was positioned over the left motor area. After identifying the resting motor threshold (RMT), we delivered 10 single TMS pulses (rate: 0.1 Hz, intensity: 120% of the RMT) and averaged the resulting MEP amplitudes. RESULTS: The mean RMTs and MEP amplitudes were not significantly different between the MO and HV groups. In patients with MO, the RMTs were negatively correlated with the number of days elapsed since the last migraine attack (rho = -0.404, p = 0.04). CONCLUSION: Our results suggest that the threshold for evoking MEPs is influenced by the proximity of an attack; specifically, the threshold is lower when a long time interval has passed after an attack, and is higher (within the range of normative values) when measured close to an attack. These dynamic RMT variations resemble those we reported previously for visual and somatosensory evoked potentials and may represent time-dependent plastic changes in brain excitability in relation to the migraine cycle

Antimicrobial Resistant Staphylococcus Species Colonization in Dogs, Their Owners, and Veterinary Staff of the Veterinary Teaching Hospital of Naples, Italy

This study aimed to identify Staphylococcus species isolated from nasal swabs of both healthy and diseased dogs, and those of human origin, obtained from nasal swabs of both owners and veterinary staff. Firstly, pet owners were requested to complete a questionnaire relating to the care and relationship with their pets, whose results mainly showed a statistically significant higher frequency of hand washing in diseased dogs’ owners than in healthy dogs’ owners. Canine nasal swabs were obtained from 43 diseased dogs and 28 healthy dogs, while human nasal swabs were collected from the respective dogs’ owners (71 samples) and veterinary staff (34 samples). The isolation and identification of Staphylococcus spp. were followed by disk diffusion method to define the antimicrobial resistance profiles against 18 different molecules. Staphylococcus pseudintermedius was the most frequent isolated strain in both diseased (33.3%) and healthy (46.1%) dogs. Staphylococcus epidermidis was the most frequent isolated bacterium in diseased dogs’ owners (66.6%), while in nasal samples of healthy dogs’ owners, the same frequency of isolation (38.4%) was observed for both Staphylococcus epidermidis and Staphylococcus aureus. All the isolated strains showed good susceptibility levels to the tested antimicrobials; however, the carriage of oxacillin-resistant strains was significantly higher in diseased dogs than in healthy ones (71% and 7.7%, respectively). Only in three cases the presence of the same bacterial species with similar antimicrobial resistance profiles in dogs and their owners was detected, suggesting the potential bacterial transmission. In conclusion, this study suggests potential transmission risk of staphylococci from dogs to humans or vice versa, and highlights that the clinical relevance of Staphylococcus pseudintermedius transmission from dog to human should not be underestimated, as well as the role of Staphylococcus aureus from human to dog transmission

The Via Francigena Salentina as an Opportunity for Experiential Tourism and a Territorial Enhancement Tool

The essay presents the results of a 10-year archival and on-field study, carried out by a research group (bringing together archaeologists, geographers, medieval historians and art historians) of the Department of Cultural Heritage of the Salento University, who have rebuilt the Via Francigena Salentina following ancient pilgrim routes heading to the Holy Land. The researchers have mapped and catalogued natural and cultural highlights along the route, also analysing tourism services on a local scale and the environmental impact of human activities. After presenting a short assessment of the adequacy of cultural routes in meeting the new requirements imposed by the tourism demand the research analyses the Via Francigena Salentina’s main features, also taking into account goods and services provided by the territory and the capability of local professionals and administrators to drive and boost effective relationships among stakeholders, also activating enhancement processes and organic and unitary promotional initiatives and always respecting both visitors’ needs and the environment

Voluntary movement takes shape. the link between movement focusing and sensory input gating

The aim of the study was to investigate the relationship between motor surround inhibition (mSI) and the modulation of somatosensory temporal discrimination threshold (STDT) induced by voluntary movement. Seventeen healthy volunteers participated in the study. To assess mSI, we delivered transcranial magnetic stimulation (TMS) single pulses to record motor evoked potentials (MEPs) from the right abductor digiti minimi (ADM; “surround muscle”) during brief right little finger flexion. mSI was expressed as the ratio of ADM MEP amplitude during movement to MEP amplitude at rest. We preliminarily measured STDT values by assessing the shortest interval at which subjects were able to recognize a pair of electric stimuli, delivered over the volar surface of the right little finger, as separate in time. We then evaluated the STDT by using the same motor task used for mSI. mSI and STDT modulation were evaluated at the same time points during movement. mSI and STDT modulation displayed similar time-dependent changes during index finger movement. In both cases, the modulation was maximally present at the onset of the movement and gradually vanished over about 200 ms. Our study provides the first neurophysiological evidence about the relationship between mSI and tactile-motor integration during movement execution

Abnormal temporal coupling of tactile perception and motor action in Parkinson's disease

Evidence shows altered somatosensory temporal discrimination threshold (STDT) in Parkinson's disease in comparison to normal subjects. In healthy subjects, movement execution modulates STDT values through mechanisms of sensory gating. We investigated whether STDT modulation during movement execution in patients with Parkinson's disease differs from that in healthy subjects. In 24 patients with Parkinson's disease and 20 healthy subjects, we tested STDT at baseline and during index finger abductions (at movement onset "0", 100, and 200 ms thereafter). We also recorded kinematic features of index finger abductions. Fifteen out of the 24 patients were also tested ON medication. In healthy subjects, STDT increased significantly at 0, 100, and 200 ms after movement onset, whereas in patients with Parkinson's disease in OFF therapy, it increased significantly at 0 and 100 ms but returned to baseline values at 200 ms. When patients were tested ON therapy, STDT during index finger abductions increased significantly, with a time course similar to that of healthy subjects. Differently from healthy subjects, in patients with Parkinson's disease, the mean velocity of the finger abductions decreased according to the time lapse between movement onset and the delivery of the paired electrical stimuli for testing somatosensory temporal discrimination. In conclusion, patients with Parkinson's disease show abnormalities in the temporal coupling between tactile information and motor outflow. Our study provides first evidence that altered temporal processing of sensory information play a role in the pathophysiology of motor symptoms in Parkinson's disease

Effect of high level of bladder filling on spinal nociception and motoneuronal excitability

To verify whether high level of bladder distension may counteract the inhibitory effect of descending pathways on sacral spinal cord neurons and to investigate which spinal circuitries are possibly involved in such a viscero-somatic interaction. Nociceptive withdrawal reflex (NWR), cutaneous silent period (CSP), and H-reflex were recorded in both lower and upper limbs of twenty-eight healthy subjects. Subjects were examined during baseline (empty bladder, no voiding desire), high level of bladder filling (urgency desire), and control (empty bladder, no voiding desire) sessions. Results showed that the NWR and its related pain perception were reduced in the upper limbs, while only a pain perception reduction in males was observed in the lower limbs. The H-reflex was inhibited in both limbs. No effects were found on the CSP duration. The decrease in both the NWR and its related pain perception in the upper limbs confirms the presence of a bladder distension-induced descending inhibitory modulation on nociception at spinal level. The lack of a similar inhibitory effect in the lower limbs suggests that excitatory nociceptive inputs from bladder afferents counterbalance the inhibitory effect on sacral spinal cord. The lack of the descending inhibitory effect may be a mechanism aimed at forcing the micturition phase to avoid bladder damage caused by bladder sovradistension

Coronary tortuosity: normal variant or pathological condition?

HighlightsCoronary tortuosity is a common coronary angiography finding. The aetiology and the clinical significant are not well defined, generally considered a normal variant. We showed a case of marked tortuosity of all coronary arteries associated with myocardial ischemia. </p

Modification of micro-channel filling flow by poly(dimethylsiloxane) surface functionalization with fluorine—Substituted aminonaphthols

Microfluidics based on the capillarity-induced filling of elastomeric channels by a suitable liquid or solution represents a useful route for realizing portable diagnostic devices designed without additional mechanical or electrical micropumps. In this study, an elastomeric mold made of poly(dimethylsiloxane) (PDMS), containing relief patterns placed in intimate contact with a silicon substrate, is utilized to create a continuous network of rectangular micro-channels for the motion of water fluid. The immobilization on activated PDMS surface of suitable functional molecules such as hydrophilic and hydrophobic fluorine-containing aminonaphthols, obtained through a straightforward and versatile synthetic procedure, allowed us to modulate PDMS surface properties depending on the structural characteristics of the employed derivative. In this context, the incorporation of fluorine groups is important for improving biocompatibility of the resulting device, providing surfaces that could be chemically and biologically inert as well as resistant to surface adhesion phenomena. The functionalization from liquid phase of PDMS replicas, involving a covalent derivatization via silanization reaction of the above mentioned compounds to an oxidized PDMS surface, resulted in a successful modification of microfluidic motion of water in rectangular capillaries, moreover contact angle values evidence also how wettability of PDMS films could be modulated, with the fluorinated aminonaphthols fuctionalized PDMS exhibiting higher contact angles. (C) 2009 Elsevier B.V. All rights reserved