Intracortical and interhemispheric excitability changes in arm amputees: A TMS study

Objective: To evaluate cortical circuits and excitability of the motor cortex in the hemisphere contralateral to the affected (AH) and to the unaffected arm (UH), in upper limb amputees. Methods: Motor evoked potentials (MEP) were recorded in 17 subjects who had upper limb amputation: 11 trans-radial (TR) and 6 trans-humeral (TH). Motor thresholds (MT), short interval intracortical inhibition (SICI), and interhemispheric inhibition (IHI) in the available arm muscles of the stump were evaluated. Results: There was no significant difference in MT between hemispheres. SICI was preserved in TR but not in TH group. Additionally, in the TR group, the MEP amplitudes in AH were higher than in UH. A significant IHI was observed in the whole sample but not in each hemisphere or patient group. Conclusions: In our population of TR amputees, we found increased corticospinal excitability in the AH with preserved intracortical inhibition. This finding was not observed in the TH population. Significance: Understanding the changes in intracortical excitability in amputees may enhance knowledge of the functional reorganization of the brain in the post-amputation phase, bringing useful information for prosthetic rehabilitation

Recurrent Subarachnoid Bleeding and Superficial Siderosis in a Patient with Histopathologically Proven Cerebral Amyloid Angiopathy

A 68-year-old man with a history of hypertension presented with recurrent subarachnoid bleeding. Brain MRI showed superficial siderosis, and diagnostic cerebral angiograms did not show any intracranial vascular malformation or arterial aneurism. Post mortem neuropathological examination of the brain was consistent with a diagnosis of cerebral amyloid angiopathy. Clinicians should be aware that cerebral amyloid angiopathy should be considered in patients with unexplained recurrent subarachnoid bleeding, even in cases without familial clustering or transthyretin variant

In vivo emergence of colistin resistance in Klebsiella pneumoniae producing KPC-type carbapenemases mediated by insertional inactivation of the PhoQ/PhoP mgrB regulator

Colistin is one of the few agents that retain activity against extensively drug-resistant strains of Klebsiella pneumoniae producing KPC-type carbapenemases (KPC-KP). However, resistance to colistin is increasingly reported among KPC-KP. Comparative genomic analysis of a pair of sequential KPC-KP isolates from the same patient including a colistin-susceptible isolate (KKBO-1) and a colistin-resistant isolate (KKBO-4) selected after colistin exposure revealed that insertional inactivation of the mgrB gene, encoding a negative regulator of the PhoQ/PhoP signaling system, is a genetic mechanism for acquired colistin resistance. The role of mgrB inactivation in acquired colistin resistance was confirmed by complementation experiments with wild-type mgrB, which restored colistin susceptibility in KKBO-4, and by construction of an mgrB deletion mutant from KKBO-1, which exhibited a colistin-resistant phenotype. Insertional mgrB inactivation was also detected in 60% of colistin-resistant mutants selected from KKBO-1 in vitro, following plating on colistin-containing medium, confirming the role (although not unique) of this mechanism in the emergence of acquired colistin resistance. In colistin-resistant mutants carrying insertional inactivation or deletion of the mgrB gene, upregulated transcription of phoP, phoQ, and pmrK (which is part of the pmrHFIJKLM operon) was detected. These findings confirmed the MgrB regulatory role in K. pneumoniae and were in agreement with the known association between upregulation of the PhoQ/PhoP system and activation of the pmrHFIJKLM operon, which eventually leads to resistance to polymyxins by modification of the lipopolysaccharide target

In vitro time-kill kinetics of dalbavancin against Staphylococcus spp. biofilms over prolonged exposure times

Abstract Staphylococcus aureus and Staphylococcus epidermidis are leading pathogens of biofilm-related infections and represent the most common cause of osteomyelitis and biomedical implants infections. Biofilm-related infections usually require long-term antibiotic treatment, often associated to surgical interventions. Dalbavancin is a newer lipoglycopeptide approved for the treatment of acute skin and skin-structure infections caused by Gram-positive pathogens. In addition, dalbavancin has recently been considered as a potential option for the treatment of staphylococcal osteomyelitis and orthopedic implant infections. In this study, time-kill kinetics of dalbavancin against S. aureus and S. epidermidis biofilms were determined over prolonged exposure times (up to 7 days), using both a standardized biofilm susceptibility model and biofilms grown onto relevant orthopedic biomaterials (i.e. titanium and cobalt-chrome disks). Dalbavancin (at concentrations achievable in bone and articular tissue) showed a potent activity against established staphylococcal biofilms in both tested models, and was overall superior to the comparator vancomycin

A smart devices based secondary prevention program for cerebrovascular disease patients

BackgroundCommercially available health devices are gaining momentum and represent a great opportunity for monitoring patients for prolonged periods. This study aimed at testing the feasibility of a smart device-based secondary prevention program in a cohort of patients with cryptogenic stroke.MethodsIn this proof-of-principle study, patients with non-disabling ischemic stroke and transient ischemic attacks (TIA) in the subacute phase were provided with a smartwatch and smart devices to monitor several parameters – i.e., oxygen saturation, blood pressure, steps a day, heart rate and heart rate variability - for a 4-week period (watch group). This group was compared with a standard-of-care group. Our primary endpoint was the compliance with the use of smart devices that was evaluated as the number of measures performed during the observation period.ResultsIn total, 161 patients were recruited, 87 in the WATCH group and 74 in the control group. In the WATCH group, more than 90% of patients recorded the ECG at least once a day. In total, 5,335 ECGs were recorded during the study. The median blood pressure value was 132/78 mmHg and the median oxygen saturation value was 97%. From a clinical standpoint, although not statistically significant, nine atrial fibrillation episodes (10.3%) in the WATCH group vs. 3 (4%) in the control group were detected.ConclusionOur study suggests that prevention programs for cerebrovascular disease may benefit from the implementation of new technologies

Complete genome sequence of the first KPC-type carbapenemase-positive Proteus mirabilis strain from a bloodstream infection

Sequencing of the blaKPC-positive strain Proteus mirabilis AOUC-001 was performed using both the MiSeq and PacBio RS II platforms and yielded a single molecule of 4,272,433 bp, representing the complete chromosome. Genome analysis showed the presence of several acquired resistance determinants, including two copies of blaKPC-2 carried on a fragment of a KPC-producing plasmid previously described in Klebsiella pneumoniae

The role of neurophysiological tools in the evaluation of ischemic stroke evolution: a narrative review

Ischemic stroke is characterized by a complex cascade of events starting from vessel occlusion. The term “penumbra” denotes the area of severely hypo-perfused brain tissue surrounding the ischemic core that can be potentially recovered if blood flow is reestablished. From the neurophysiological perspective, there are local alterations—reflecting the loss of function of the core and the penumbra—and widespread changes in neural networks functioning, since structural and functional connectivity is disrupted. These dynamic changes are closely related to blood flow in the affected area. However, the pathological process of stroke does not end after the acute phase, but it determines a long-term cascade of events, including changes of cortical excitability, that are quite precocious and might precede clinical evolution. Neurophysiological tools—such as Transcranial Magnetic Stimulation (TMS) or Electroencephalography (EEG)—have enough time resolution to efficiently reflect the pathological changes occurring after stroke. Even if they do not have a role in acute stroke management, EEG and TMS might be helpful for monitoring ischemia evolution—also in the sub-acute and chronic stages. The present review aims to describe the changes occurring in the infarcted area after stroke from the neurophysiological perspective, starting from the acute to the chronic phase

Using TMS-EEG to assess the effects of neuromodulation techniques: a narrative review

Over the past decades, among all the non-invasive brain stimulation (NIBS) techniques, those aiming for neuromodulatory protocols have gained special attention. The traditional neurophysiological outcome to estimate the neuromodulatory effect is the motor evoked potential (MEP), the impact of NIBS techniques is commonly estimated as the change in MEP amplitude. This approach has several limitations: first, the use of MEP limits the evaluation of stimulation to the motor cortex excluding all the other brain areas. Second, MEP is an indirect measure of brain activity and is influenced by several factors. To overcome these limitations several studies have used new outcomes to measure brain changes after neuromodulation techniques with the concurrent use of transcranial magnetic stimulation (TMS) and electroencephalogram (EEG). In the present review, we examine studies that use TMS-EEG before and after a single session of neuromodulatory TMS. Then, we focused our literature research on the description of the different metrics derived from TMS-EEG to measure the effect of neuromodulation