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Background: Creutzfeldt-Jakob disease (CJD) is a rapidly progressive neurodegenerative disorder characterized by neuronal damage. Emerging biomarkers, such as serum neurofilament light chain (sNfL), glial fibrillary acidic protein (sGFAP), and growth differentiation factor-15 (sGDF-15), are currently being studied for their potential use in this disease., Objectives: This study analyzes the levels of sNfL, sGFAP, and sGDF-15, as well as their relationships, in patients with CJD compared to healthy controls (HC)., Methods: A total of 19 CJD patients and 81 age- and sex-matched HCs were enrolled. Serum levels of sNfL and sGFAP were measured using ultrasensitive immunoassays, while sGDF-15 levels were assessed via ELISA. Statistical analyses included correlation analysis and analysis of covariance (ANCOVA) models., Results: CJD patients showed significantly higher serum levels of sNfL and sGFAP compared to HCs (p <0,001). sNfL levels were positively correlated with both sGFAP (Rho = 0,70; p < 0,001) and sGDF-15 (Rho = 0,60; p = 0,004). Interestingly, sGFAP levels were higher in female CJD patients compared to males (p = 0,001), while no significant difference in sNfL levels was observed between sexes., Conclusions: In conclusion, this study explores the potential of sNfL, sGDF-15, and sGFAP as biomarkers in CJD patients. The higher levels of sNfL and sGFAP in CJD patients compared to healthy controls, along with the observed sex differences in sGFAP, highlight the need for further research into the interaction between astroglia and neurons in CJD, with a focus on sex as a key variable., Competing Interests: Declaration of competing interest All the Authors have no competing interests in relation to this study., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

We describe the case of a 76-year-old man affected by pneumoconiosis, secondary to silica dust exposure, who was diagnosed with antineutrophil cytoplasmic antibody (ANCA)-positive microscopic polyangiitis (MPA)-related cervical myelitis. Pneumoconiosis is reported to trigger autoantibody production and the onset of different autoimmune diseases, including ANCA-associated vasculitis (AAV). MPA is an AAV of the small vessels that can often affect the nervous system, although involvement of the spinal cord in the form of myelitis is described as an anecdotal occurrence. Our experience suggests that an autoimmunity workup should be considered for patients with pneumoconiosis who present with neurological symptoms consistent with AAV.

Background: We aimed to verify the usefulness of electroencephalographic (EEG) activity recording (that is mandatory according to the Italian law), in addition to two clinical evaluations spaced 6 h, among the procedures of brain death determination (BDD) in adult individuals., Methods: The study is a monocentric, retrospective analysis of all BDDs performed in the last 10 years at Policlinico Le Scotte in Siena (Italy)., Results: Of the 428 cases revised (mean age 67.6 ± 15.03 years; range 24-92 years), 225 were males and 203 females. In total, 212 out of 428 patients (49.5%) were donors. None of the BDD procedures were interrupted due to the reappearance of EEG activity (neither for clinical reasons) at any sampling time, with the exception of one case that was considered a false negative at critical reinspection of the EEG. In 6/428 cases (1.4%), a cardiac arrest occurred during the 6 h between the first and second evaluation, thus missing the opportunity to take organs from these patients because the BDD procedure was not completed., Conclusions: Once the initial clinical examination before convening the BDD Commission has ascertained the absence of brainstem reflexes and of spontaneous breathing, and these clinical findings are supported by a flat EEG recording, the repetition of a 30-min EEG twice over a 6 h period seems not to add additional useful information to clinical findings. Current data, if confirmed in other centers and possibly in prospective studies, may help to promote a scientific and bioethical debate in Italy, as well as in other countries where the EEG is still mandatory, for eventually updating the procedures of BDD., (© 2022. The Author(s).)

The precise and accurate determination of the radionuclide inventory in radioactive waste streams, including those generated during nuclear decommissioning, is a key aspect in establishing the best-suited nuclear waste management and disposal options. Radiocarbon ([Formula: see text]) is playing a crucial role in this scenario because it is one of the so-called difficult to measure isotopes; currently, [Formula: see text] analysis requires complex systems, such as accelerator mass spectrometry (AMS) or liquid scintillation counting (LSC). AMS has an outstanding limit of detection, but only a few facilities are available worldwide; LSC, which can have similar performance, is more widespread, but sample preparation can be nontrivial. In this paper, we demonstrate that the laser-based saturated-absorption cavity ring-down (SCAR) spectroscopic technique has several distinct advantages and represents a mature and accurate alternative for [Formula: see text] content determination in nuclear waste. As a proof-of-principle experiment, we show consistent results of AMS and SCAR for samples of concrete and graphite originating from nuclear installations. In particular, we determined mole fractions of 1.312(9) F[Formula: see text] and 30.951(7) F[Formula: see text] corresponding to ∼1.5 and 36.2 parts per trillion (ppt), respectively, for two different graphite samples originating from different regions of the Adiabatic Resonance Crossing activator prototype installed on one irradiation line of an MC40 Scanditronix cyclotron. Moreover, we measure a mole fraction of 0.593(8) F[Formula: see text] ([Formula: see text] ppt) from a concrete sample originating from an external wall of the Ispra-1 nuclear research reactor currently in the decommissioning phase.

Background: Clinical presentation, electrophysiological subtype, and outcome of the Guillain-Barre' Syndrome (GBS) may differ between patients from different geographical regions. This study aims to assess clinical-neurophysiological features of an adult, Italian GBS cohort over 11 years., Methods: Retrospective (from 1 January 2011 to 31 December 2021) analysis was carried out on patients admitted to the Siena University Hospital who fulfilled the GBS diagnostic criteria. Demographic data, clinical characteristics, treatment, need of mechanical ventilation (MV), laboratory and electrophysiological tests, preceding infections/vaccination/other conditions, and comorbidities were collected for each patient., Results: A total of 84 patients (51 men, median age of 61 years), were identified. GBS subtype was classified as acute inflammatory demyelinating polyneuropathy (AIDP) in the 66.6% of patients, acute motor/sensory axonal neuropathy (AMAN/AMSAN) in 20.2%, and the Miller Fisher syndrome in 5 (5.9%). Flu syndrome and gastrointestinal infection were the most common preceding conditions. In total, five (5.9%) subjects had concomitant cytomegalovirus (CMV) infection. Cranial nerve involvement occurred in 34.5% of subjects. Differences between the axonal and AIDP forms of GBS concerned the presence of anti-ganglioside antibodies. In total, seven (8.33%) patients required MV., Discussion: The epidemiological and clinical characteristics of GBS in different countries are constantly evolving, especially in relation to environmental changes. This study provides updated clinical-epidemiological information in an Italian cohort., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Ginanneschi, Giannini, Sicurelli, Battisti, Capoccitti, Bartalini, Mignarri, Volpi, Cioncoloni, Franci, De Stefano and Rossi.)

Background and study purpose: to describe the comorbidity of celiac disease among a large cohort of multiple sclerosis patients in Tuscany., Methods: the association of celiac disease among multiple sclerosis adult patients (n=2050) was retrospectively evaluated., Results: 13 patients were diagnosed with celiac disease, the female:male ratio was 3.3:1 and the median age at diagnosis was 34.2 years (SD 13). Seventy-seven per cent of subjects complained about gastrointestinal symptoms. IgA anti- transglutaminase was positive in 85 % of cases and there was 70 % of villous atrophy., Conclusions: the frequency of celiac disease among multiple sclerosis patients examined was lower than in the general population, 0.6 % vs 1 %)(p = 0.65).

Miniaturized frequency comb sources across hard-to-access spectral regions, i.e. mid- and far-infrared, have long been sought. Four-wave-mixing based Quantum Cascade Laser combs (QCL-combs) are ideal candidates, in this respect, due to the unique possibility to tailor their spectral emission by proper nanoscale design of the quantum wells. We demonstrate full-phase-stabilization of a QCL-comb against the primary frequency standard, proving independent and simultaneous control of the two comb degrees of freedom (modes spacing and frequency offset) at a metrological level. Each emitted mode exhibits a sub-Hz relative frequency stability, while a correlation analysis on the modal phases confirms the high degree of coherence in the device emission, over different power-cycles and over different days. The achievement of fully controlled, phase-stabilized QCL-comb emitters proves that this technology is mature for metrological-grade uses, as well as for an increasing number of scientific and technological applications.

Objective: Verify whether Percutaneous Transluminal Angioplasty (PTA) may affect neural conduction properties in Multiple Sclerosis (MS) patients, thereby modifying patients' disability, with prospective neurophysiological, urodynamic, clinical and subjective well-being evaluations., Methods: In 55 out of 72 consecutively screened MS patients, the following procedures were carried out before (T0), at 2-6 months (T1) and at 6-15 months (T2) after a diagnostic phlebography, eventually followed by the PTA intervention if chronic cerebrospinal venous insufficiency (CCSVI) was diagnosed: clinical/objective evaluation (Expanded Disability Status Scale, EDSS), ratings of subjective well-being, evaluation of urodynamic functions and multimodal EPs (visual, acoustic, upper and lower limbs somatosensory and motor evoked potentials)., Results: The number of dropouts was relatively high, and a complete set of neurophysiological and clinical data remained available for 37 patients (19 for urological investigations). The subjective well-being score significantly increased at T1 and returned close to basal values at T2, but their degree of objective disability did not change. Nevertheless, global EP-scores (indexing the impairment in conductivity of central pathways in multiple functional domains) significantly increased from T0 (7.9 ± 6.0) to T1 (9.2 ± 6.3) and from T0 to T2 (9.8 ± 6.3), but not from T1 and T2 (p > 0.05). Neurogenic urological lower tract dysfunctions slightly increased throughout the study., Conclusions: The PTA intervention did not induce significant changes in disability in the present cohort of MS patients, in line with recent evidence of clinical inefficacy of this procedure., Significance: Absence of multimodal neurophysiological and functional testing changes in the first 15 months following PTA suggests that conduction properties of neural pathways are unaffected by PTA. Current findings suggest that the short-lived (2-6 months), post-PTA, beneficial effect on subjective well-being measures experienced by MS patients is likely related to a placebo effect., (Copyright © 2018 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.)

Background: Italy is a high-risk area for multiple sclerosis with 110,000 prevalent cases estimated at January 2016 and 3400 annual incident cases. To study multiple sclerosis epidemiology, it is preferable to use population-based studies, e.g., with a registry. A valid alternative to obtain data on entire population is from administrative sources., Objective: To estimate the incidence of multiple sclerosis in Tuscany using a case-finding algorithm based on administrative data., Methods: In a previous study, we calculated the prevalence in Tuscany using a validated case-finding algorithm based on administrative data. Incident cases were identified as a subset of prevalent cases among those patients not traced in the years before the analysis period, and the date of the first multiple sclerosis-related claim was considered the incidence date of multiple sclerosis diagnosis. We examined the period 2011-2015., Results: We identified 1147 incident cases with annual rates ranged from 5.60 per 100,000 in 2011 to 6.58 in 2015., Conclusions: We found a high incidence rate, similarly to other Italian areas, especially in women, that may explain the increasing prevalence in Tuscany. To confirm this data and to calculate the possible bias caused by our inclusion method, we will validate our algorithm for incident cases.

Background: Knowledge concerning the predictors of social security benefits and the proportion of Multiple Sclerosis (MS) patients receiving these benefits is very limited., Objective: To estimate the likelihood of receiving social security benefits for Italian MS patients., Methods: From September 2014 to November 2015, we interviewed MS outpatients from two Italian MS clinics to collect information regarding their personal data, clinical and working history, and access to social security benefits. We performed both univariate and multivariable analyses to evaluate the predictors for receiving social security benefits., Results: We interviewed 297 patients, with a mean age of 49.5 (± 10.7) years; 71.4% were females. About 73% of patients had a relapsing-remitting (RR) course and the median EDSS score was 2.5 (IQR 1.5-6). About 75% of MS patients received a full exemption from co-payments, while the proportions of people who enjoyed each of the other social security benefits were lower, ranging from 8.8% (car adaptation) to 32% (disable badge). At multivariable analysis, the probability of obtaining each of the benefits was significantly associated with the EDSS score: walking aids (OR 3.9), care allowance (OR 3.6), disabled badge (OR 2.4), exemption from co-payment (OR 1.6) and allowed off work permit (OR 1.7). Only the probability of obtaining an allowed off work permit was also influenced by comorbidities (OR 2.9) and a higher education (OR 2.2)., Conclusion: Except for full exemption from co-payments, the proportions of MS patients who enjoyed social security benefits seem to be limited in our study sample. The EDSS score is the strongest predictor of the probability of receiving all the benefits. Only a small proportion of patients received care allowance and working permits, probably because such benefits are only granted to people with a high level of disability. On the other hand, the low proportion of patients who enjoyed fiscal benefits for home and car adaptations could have been influenced by the way such benefits are granted in our country., (Copyright © 2018. Published by Elsevier B.V.)

Tuscany (Central Italy) is a high-risk area for multiple sclerosis (MS) with a prevalence of 188 cases per 100,000 at 2011, and it is characterized by a heterogeneous geographic distribution of this disease. Our objective was to update prevalence at 2013 and to evaluate the presence of spatial clusters in Tuscany. The MS prevalence was evaluated on 31 December 2013 using a validated case-finding algorithm, based on administrative data. To identify spatial clusters, we calculated standardized morbidity ratios (SMRs) for each Tuscan administrative municipality. In addition to the classical approach, we applied the hierarchical Bayesian model to overcome random variability due to the presence of small number of cases per municipality. We identified 7330 MS patients (2251 males and 5079 females) with an overall prevalence of 195.4/100,000. The SMR for each Tuscan municipality ranged from 0 to 271.4, but this approach produced an extremely non-homogeneous map. On the contrary, the Bayesian map was much smoother than the classical one. The posterior probability (PP) map showed prevalence clusters in some areas in the province of Massa-Carrara, Pistoia, and Arezzo, and in the municipalities of Siena, Florence, and Barberino Val d'Elsa. Our prevalence data confirmed that Tuscany is a high-risk area, and we observed an increasing trend during the time. Using the Bayesian method, we estimated area-specific prevalence in each municipality reducing the random variation and the effect of extreme prevalence values in small areas that affected the classical approach.

Terahertz sources based on intracavity difference-frequency generation in mid-infrared quantum cascade lasers (THz DFG-QCLs) have recently emerged as the first monolithic electrically pumped semiconductor sources capable of operating at room temperature across the 1- to 6-THz range. Despite tremendous progress in power output, which now exceeds 1 mW in pulsed and 10 μW in continuous-wave regimes at room temperature, knowledge of the major figure of merits of these devices for high-precision spectroscopy, such as spectral purity and absolute frequency tunability, is still lacking. By exploiting a metrological grade system comprising a terahertz frequency comb synthesizer, we measure, for the first time, the free-running emission linewidth (LW), the tuning characteristics, and the absolute center frequency of individual emission lines of these sources with an uncertainty of 4 × 10 -10 . The unveiled emission LW (400 kHz at 1-ms integration time) indicates that DFG-QCLs are well suited to operate as local oscillators and to be used for a variety of metrological, spectroscopic, communication, and imaging applications that require narrow-LW THz sources.

Background: Dysfunctions of the upper limbs occur in the 66% of multiple sclerosis (MS) patients. To date, no data, about the persistence of the effects of a rehabilitation treatment and no prognostic markers of functional improvement, have been established., Aim: The aim of this study was to define clinical data supporting the efficacy of a rehabilitation treatment in MS patients with upper limb impairment and to find prognostic factors for functional improvement., Design: Pre-post comparison prospective study., Setting: Two tertiary Italian MS centres: Rome and Siena., Population: Twenty-five consecutive MS patients were tested for eligibility., Methods: We multidimensionally evaluated 25 consecutive patients with MS-related upper limbs impairment through clinical objective, patient-oriented and neurophysiological measures pre and post a16-week rehabilitation treatment on upper limb sensorimotor function., Results: We found a significant improvement in the Nine Hole Peg Test (9-HPT) at either sides, both at an immediate post-training visit (T1) (left: P=0.018, right: P=0.004) and at a 12-week postintervention assessment visit (T2) (left: P=0.033, right: P=0.022). We also found a positive correlation between the 12-week post-training changes in the 9-HPT and the N14-P20 interpeak of the somatosensory evoked potentials, (rho=0.374, P=0.008)., Conclusions: Our study demonstrates that a rehabilitation treatment can lead to an improvement of the upper limb motor performance in MS patients which continues to persist even after 3 months of treatment-discontinuation suggesting a possible role of rehabilitation in neuroplasticity changes. Moreover, we found, in the latency of the N14-P20 interpeak, a possible prognostic marker for the effects of a upper limb rehabilitation treatment in MS patients., Clinical Rehabilitation Impact: The N14-P20 interpeak could be used as a prognostic marker of the effects of rehabilitation of the upper limb.

The toxicity risk of hyperhomocysteinemia is prevented through thiol drug administration which reduces plasma total homocysteine (tHcy) concentrations by activating thiol exchange reactions. Assuming that cysteine (Cys) is a homocysteinemia regulator, the hypothesis was verified in healthy and pathological individuals after the methionine loading test (MLT). The plasma variations of redox species of Cys, Hcy, cysteinylglycine, glutathione and albumin (reduced, HS-ALB, and at mixed disulfide, XSS-ALB) were compared in patients with cerebral small vessels disease (CSVD) (n = 11), multiple sclerosis (MS) (n = 12) and healthy controls (n = 11) at 2-4-6 h after MLT. In MLT-treated subjects, the activation of thiol exchange reactions provoked significant changes over time in redox species concentrations of Cys, Hcy, and albumin. Significant differences between controls and pathological groups were also observed. In non-methionine-treated subjects, total Cys concentrations, tHcy and thiol-protein mixed disulfides (CSS-ALB, HSS-ALB) of CSVD patients were higher than controls. After MLT, all groups displayed significant cystine (CSSC) increases and CSS-ALB decreases, that in pathological groups were significantly higher than controls. These data would confirm the Cys regulatory role on the homocysteinemia; they also explain that the Cys-Hcy mixed disulfide excretion is an important point of hyperhomocysteinemia control. Moreover, in all groups after MLT, significant increases in albumin concentrations, named total albumin (tALB) and measured as sum of HS-ALB (spectrophometric), and XSS-ALB (assayed at HPLC) were observed. tALB increases, more pronounced in healthy than in the pathological subjects, could indicate alterations of albumin equilibria between plasma and other extracellular spaces, whose toxicological consequences deserve further studies.

The need for highly performing and stable methods for mid-IR molecular sensing and metrology pushes towards the development of more and more compact and robust systems. Among the innovative solutions aimed at answering the need for stable mid-IR references are crystalline microresonators, which have recently shown excellent capabilities for frequency stabilization and linewidth narrowing of quantum cascade lasers with compact setups. In this work, we report on the first system for mid-IR high-resolution spectroscopy based on a quantum cascade laser locked to a CaF₂ microresonator. Electronic locking narrows the laser linewidth by one order of magnitude and guarantees good stability over long timescales, allowing, at the same time, an easy way for finely tuning the laser frequency over the molecular absorption line. Improvements in terms of resolution and frequency stability of the source are demonstrated by direct sub-Doppler recording of a molecular line.

Background: Multiple Sclerosis (MS) epidemiology in Italy is mainly based on population-based prevalence studies. Administrative data are an additional source of information, when available, in prevalence studies of chronic diseases such as MS. The aim of our study is to update the prevalence rate of MS in Tuscany (central Italy) as at 2011 using a validated case-finding algorithm based on administrative data., Methods: The prevalence was calculated using an algorithm based on the following administrative data: hospital discharge records, drug-dispensing records, disease-specific exemptions from copayment to health care, home and residential long-term care and inhabitant registry. To test algorithm sensitivity, we used a true-positive reference cohort of MS patients from the Tuscan MS register. To test algorithm specificity, we used another cohort of individuals who were presumably not affected by MS., Results: As at December 31, 2011, we identified 6,890 cases (4,738 females and 2,152 males) with a prevalence of 187.9 per 100,000. The sensitivity of algorithm was 98% and the specificity was 99.99%., Conclusions: We found a prevalence higher than the rates present in literature. Our algorithm, based on administrative data, can accurately identify MS patients; moreover, the resulting cohort is suitable to monitor disease care pathways., (© 2015 S. Karger AG, Basel.)

Coherent imaging in the THz range promises to exploit the peculiar capabilities of these wavelengths to penetrate common materials like plastics, ceramics, paper or clothes with potential breakthroughs in non-destructive inspection and quality control, homeland security and biomedical applications. Up to now, however, THz coherent imaging has been limited by time-consuming raster scanning, point-like detection schemes and by the lack of adequate coherent sources. Here, we demonstrate real-time digital holography (DH) at THz frequencies exploiting the high spectral purity and the mW output power of a quantum cascade laser combined with the high sensitivity and resolution of a microbolometric array. We show that, in a one-shot exposure, phase and amplitude information of whole samples, either in reflection or in transmission, can be recorded. Furthermore, a 200 times reduced sensitivity to mechanical vibrations and a significantly enlarged field of view are observed, as compared to DH in the visible range. These properties of THz DH enable unprecedented holographic recording of real world dynamic scenes.

We report on the realization and characterization of two different designs for resonant THz cavities, based on wire-grid polarizers as input/output couplers, and injected by a continuous-wave quantum cascade laser (QCL) emitting at 2.55 THz. A comparison between the measured resonators parameters and the expected theoretical values is reported. With achieved quality factor Q ≈ 2.5 × 10(5), these cavities show resonant peaks as narrow as few MHz, comparable with the typical Doppler linewidth of THz molecular transitions and slightly broader than the free-running QCL emission spectrum. The effects of the optical feedback from one cavity to the QCL are examined by using the other cavity as a frequency reference.

In ten healthy subjects and in ten patients suffering from Multiple Sclerosis (MS), we investigated the cortical functional changes induced by a standard fatiguing repetitive tapping task. The Cortical Silent Period (CSP), an intracortical, mainly GABAB-mediated inhibitory phenomenon, was recorded by two different hand muscles, one acting as prime mover of the fatiguing index-thumb tapping task (First Dorsal Interosseous, FDI) and the other one not involved in the task but sharing largely overlapping central, spinal, and peripheral innervation (Abductor Digiti Minimi, ADM). At baseline, the CSP was shorter in patients than in controls. As fatigue developed, CSP changes involved both the "fatigued" FDI and the "unfatigued" ADM muscles, suggesting a cortical spread of central fatigue mechanisms. Chronic therapy with amantadine annulled differences in CSP duration between controls and patients, possibly through restoration of more physiological levels of intracortical inhibition in the motor cortex. These inhibitory changes correlated with the improvement of fatigue scales. The CSP may represent a suitable marker of neurophysiological mechanisms accounting for central fatigue generation either in controls or in MS patients, involving corticospinal neural pools supplying not only the fatigued muscle but also adjacent muscles sharing an overlapping cortical representation.

Background: Individual factors in multiple sclerosis (MS) patients may modify the reliability of health-related quality of life (HRQOL) assessment. Knowledge of these effects may enable physicians to identify patients at risk for poor perceived health., Objective: To investigate what individual factors may interact with MS symptoms and their severity to modify the reliability of HRQOL assessment; to explore the predictive values of the significant variables identified., Methods: HRQOL was assessed in 57 patients by the 36-Item Short Form Health Survey (SF-36). The Physical Component Summary and Mental Component Summary were dichotomized and applied as dependent variables for logistic regression analysis. The Functional Independence Measure (FIM), Expanded Disability Status Scale (EDSS), Fatigue Severity Scale (FSS), Cognitive Behavioral Assessment (CBA) and specific individual factors were tested as independent variables. Two-way contingency tables were used to calculate the predictive values., Results: Unemployment, smoking, and night waking were the most significant individual factors. Introversion, physical pain and difficulty falling asleep were also significant. EDSS-total ≥2, EDSS-pyramidal ≥2, FIM ≤123, FSS ≥5, depressive manifestations and bowel/bladder dysfunction were significant MS-related determinants. Sensitivity and specificity differed widely for each variable., Conclusions: Individual factors have relevance in HRQOL assessment. Their identification may help physicians construct the patient's risk profile. Sensitivity and specificity add weight to the significance of variables., (Copyright © 2014 Elsevier B.V. All rights reserved.)

We report on the experimental demonstration of the metrological and spectroscopic performances of a mid-infrared comb generated by a nonlinear downconversion process from a Ti:sapphire-based near-infrared comb. A quantum cascade laser at 4330 nm was phase-locked to a single tooth of this mid-infrared comb and its frequency-noise power spectral density was measured. The mid-infrared comb itself was also used as a multifrequency highly coherent source to perform ambient air direct comb spectroscopy with the Vernier technique, by demultiplexing it with a high-finesse Fabry-Perot cavity.

Background: Repetitive transcranial magnetic stimulation (rTMS) of the motor cortex activates corticospinal neurons mainly through the depolarization of cortico-cortical axons belonging to interneurons of superficial layers., Objective: We used single-fiber electromyography (SFEMG) to estimate the "central jitter" of activation latency of interneural pools from one pulse of TMS to another., Methods: We evaluated 10 healthy subjects and one patient with multiple sclerosis. By recording SFEMG evoked activity from the left first dorsal interosseous (FDI), we first used a standard repetitive electrical 3 Hz stimulation of the ulnar nerve at the wrist to calculate the mean consecutive difference from at least 10 different potentials. The same procedure was applied during 3 Hz repetitive TMS of the contralateral motor cortex. The corticospinal monosynaptic connection of the FDI and the selectivity of SFEMG recording physiologically justified the subtraction of the "peripheral jitter" from the whole cortico-muscular jitter, obtaining an estimation of the actual "central jitter.", Results: All subjects completed the study. The peripheral jitter was 28 μs ± 6 and the cortico-muscular jitter was 344 μs ± 97. The estimated central jitter was 343 ± 97 μs. In the patient the central jitter was 846 μs, a value more than twice the central jitter in healthy subjects., Conclusion: Current results demonstrate that the evaluation of the central component of the cumulative cortico-muscular latency variability in healthy subjects is feasible with a minimally invasive approach. We present and discuss this methodology and provide a "proof of concept" of its potential clinical applicability in a patient with multiple sclerosis., (Copyright © 2014 Elsevier Inc. All rights reserved.)

In hyperhomocysteinemic patients, after reaction with homocysteine-albumin mixed disulfides (HSS-ALB), mesna (MSH) forms the mixed disulfide with Hcy (HSSM) which can be removed by renal clearance, thus reducing the plasma concentration of total homocysteine (tHcy). In order to assess the HSS-ALB dethiolation via thiol exchange reactions, the distribution of redox species of cysteine, cysteinylglycine, homocysteine and glutathione was investigated in the plasma of healthy subjects: (i) in vitro, after addition of 35 μM reduced homocysteine (HSH) to plasma for 72 h, followed by MSH addition (at the concentration range 10-600 μM) for 25 min; (ii) in vivo, after oral treatment with methionine (methionine, 200 mg/kg body weight, observation time 2-6 h). In both experiments the distribution of redox species, but not the total amount of each thiol, was modified by thiol exchange reactions of albumin and cystine, with changes thermodynamically related to the pKa values of thiols in the corresponding mixed disulfides. MSH provoked a dose-response reversal of the redox state of aged plasma, and the thiol action was confirmed by in vivo experiments. Since it was observed that the dimesna production could be detrimental for the in vivo optimization of HSSM formation, we assume that the best plasma tHcy lowering can be obtained at MSH doses producing the minimum dimesna concentration in each individual.

We report on the generation of a frequency comb around 4330 nm with an unprecedented coherence of the single teeth. Generating the comb within a Ti:sapphire laser cavity by a difference-frequency process and using a phase-lock scheme based on direct digital synthesis, we achieve a tooth linewidth of 2.0 kHz in a 1-s timescale (750 Hz in 20 ms). The generated per-tooth power of 1 μW ranks this comb among the best ever realized in the mid-infrared in terms of power spectral density.

We report on a set of high-sensitivity terahertz spectroscopy experiments making use of QCLs to detect rotational molecular transitions in the far-infrared. We demonstrate that using a compact and transportable cryogen-free setup, based on a quantum cascade laser in a closed-cycle Stirling cryostat, and pyroelectric detectors, a considerable improvement in sensitivity can be obtained by implementing a wavelength modulation spectroscopy technique. Indeed, we show that the sensitivity of methanol vapour detection can be improved by a factor ≈ 4 with respect to standard direct absorption approaches, offering perspectives for high sensitivity detection of a number of chemical compounds across the far-infrared spectral range.

We report on the narrowing of a room-temperature mid-IR quantum cascade laser by frequency locking it to a CO2 sub-Doppler transition obtained by polarization spectroscopy. A locking bandwidth of 250 kHz has been achieved. The laser linewidth is narrowed by more than two orders of magnitude below 1 kHz, and its absolute frequency is stabilized at the same level.

A narrow-linewidth comb-linked nonlinear source is used as master radiation to injection lock a room-temperature mid-infrared quantum cascade laser (QCL). This process leads to a direct lock of the QCL to the optical frequency comb, providing the unique features of narrow linewidth, absolute frequency, higher output power, and wide mode-hop-free tunability. The QCL reproduces the injected radiation within more than 94%, with a reduction of the frequency-noise spectral density by 3 to 4 orders of magnitude up to about 100 kHz, and a linewidth narrowing from a few MHz to 20 kHz.

Optical frequency comb synthesizers have represented a revolutionary approach to frequency metrology, providing a grid of frequency references for any laser emitting within their spectral coverage. Extending the metrological features of optical frequency comb synthesizers to the terahertz domain would be a major breakthrough, due to the widespread range of accessible strategic applications and the availability of stable, high-power and widely tunable sources such as quantum cascade lasers. Here we demonstrate phase-locking of a 2.5 THz quantum cascade laser to a free-space comb, generated in a LiNbO(3) waveguide and covering the 0.1-6 THz frequency range. We show that even a small fraction (<100 nW) of the radiation emitted from the quantum cascade laser is sufficient to generate a beat note suitable for phase-locking to the comb, paving the way to novel metrological-grade terahertz applications, including high-resolution spectroscopy, manipulation of cold molecules, astronomy and telecommunications.

Radiocarbon ((14)C) concentrations at a 43 parts-per-quadrillion level are measured by using saturated-absorption cavity ringdown spectroscopy by exciting radiocarbon-dioxide ((14)C(16)O(2)) molecules at the 4.5 μm wavelength. The ultimate sensitivity limits of molecular trace gas sensing are pushed down to attobar pressures using a comb-assisted absorption spectroscopy setup. Such a result represents the lowest pressure ever detected for a gas of simple molecules. The unique sensitivity, the wide dynamic range, the compactness, and the relatively low cost of this table-top setup open new perspectives for ^{14}C-tracing applications, such as radiocarbon dating, biomedicine, or environmental and earth sciences. The detection of other very rare molecules can be pursued as well thanks to the wide and continuous mid-IR spectral coverage of the described setup.

The frequency-noise power spectral density of a room-temperature distributed-feedback quantum cascade laser emitting at λ = 4.36 μm has been measured. An intrinsic linewidth value of 260 Hz is retrieved, in reasonable agreement with theoretical calculations. A noise reduction of about a factor 200 in most of the frequency interval is also found, with respect to a cryogenic laser at the same wavelength. A quantitative treatment shows that it can be explained by a temperature-dependent mechanism governing the transport processes in resonant tunnelling devices. This confirms the predominant effect of the heterostructure in determining shape and magnitude of the frequency noise spectrum in QCLs.

Event-related repetitive transcranial magnetic stimulation (rTMS) can dynamically interfere with the memory encoding of complex visual scenes. Here, we investigated the critical time elapsing from stimulus presentation to the formation of an effective memory trace by delivering rTMS (900 ms at 20 Hz) during the encoding of visual scenes at different poststimulus delays (from 100 to 500 ms) in 28 healthy volunteers. The stimulation delay showed a robust inverse correlation with the correct retrieval of encoded images. In particular, rTMS stimulation delivered with a delay of 500 ms and lasting for 400 ms after stimulus offset resulted in a huge drop in retrieval accuracy. Such a timing suggests that rTMS affects the formation of long-term memory through interference with postperceptual executive processes, rather than with perceptual analysis of the stimuli. The effect was specific for stimulation of the left dorsolateral prefrontal cortex (DLPFC), whereas rTMS applied to the right DLPFC, vertex (active control site), as well as sham stimulation (placebo) did not affect accuracy. These results confirm the crucial role of the left DLPFC in encoding and provide novel information about the critical timing of its engagement in the formation, consolidation, and maintenance of the memory trace.

Background: Internal Jugular Veins (IJVs) are the principle outflow pathway for intracranial blood in clinostatism condition. In the seated position, IJVs collapse, while Vertebral Veins (VVs) increase the venous outflow and partially compensate the venous drainage. Spinal Epidural Veins are an additional drainage pathway in the seated position. Colour- Doppler-Sonography (CDS) examination is able to demonstrate IJVs and VVs outflow in different postural and respiratory conditions. The purpose of this study was to evaluate CDS quantification of the cerebral venous outflow (CVF) in healthy subjects and patients with multiple sclerosis (MS)., Methodology/principal Findings: In a group of 27 healthy adults (13 females and 14 males; mean age 37.8 ± 11.2 years), and 52 patients with MS (32 females and 20 males; mean age 42.6 ± 12.1 years), CVF has been measured in clinostatism and in the seated position as the sum of the flow in IJVs and VVs. The difference between CVF in clinostatism and CVF in the seated position (ΔCVF) has been correlated with patients' status (healthy or MS), and a number of clinical variables in MS patients. Statistical analysis was performed by Fisher's exact test, non-parametric Mann-Whitney U test, ANOVA Kruskal-Wallis test, and correntropy coefficient. The value of ΔCVF was negative in 59.6% of patients with MS and positive in 96.3% of healthy subjects. Negative ΔCVF values were significantly associated with MS (p<0.0001). There was no significant correlation with clinical variables., Conclusions/significance: Negative ΔCVF has a hemodynamic significance, since it reflects an increased venous return in the seated position. This seems to be a pathologic condition. In MS patients, a vascular dysregulation resulting from involvement of the autonomous nervous system may be supposed. ΔCVF value should be included in the quantitative CDS evaluation of the cerebral venous drainage, in order to identify cerebral venous return abnormalities.

A cw mid-IR coherent source based on difference-frequency generation is designed and characterized. For mid-IR generation, a periodically poled MgO:LiNbO(3) crystal is placed inside a compact Ti:sapphire laser cavity. This provides high-power pump radiation for the nonlinear process. Optical injection by an external-cavity diode laser ensures single-frequency operation of the Ti:sapphire laser, while signal radiation is provided by a fiber-amplified Nd:YAG laser. Mid-IR radiation can be generated with 3850-4540 nm tuning range, narrow linewidth, Cs-standard traceability, and TEM(00) spatial mode. 30 mW power is obtained at 4510 nm.

Increases in plasma concentrations of total homocysteine (tHcy) have recently been reported in multiple sclerosis (MS) as the alteration of the methionine cycle for the onset of autoimmune diseases. Homocysteine (Hcy) and cysteine (Cys) are generated by the methionine cycle and transsulfuration reactions. Their plasma levels are subjected to complex redox changes by oxidation and thiol/disulfide (SH/SS) exchange reactions regulated by albumin. The methionine loading test (MLT) is a useful in vivo test to assay the functionality of the methionine cycle and transsulfuration reactions. Time courses of redox species of Cys, cysteinylglycine (CGly), Hcy, and glutathione have been investigated in plasma of MS patients versus healthy subjects after an overnight fasting, and 2, 4, and 6 h after an oral MLT (100 mg/kg body weight), to detect possible dysfunctions of the methionine cycle, transsulfuration reactions and alterations in plasma distribution of redox species. After fasting, the MS group showed a significant increase in cysteine-protein mixed disulfides (bCys) and total Cys (tCys). While plasma bCys and tCys in MS group remained elevated after methionine administration when compared to control, cystine (oxCys) increased significantly with respect to control. Although increased plasma concentrations of bCys and tCys at fasting might reflect an enhance of transsulfuration reactions in MS patients, this was not confirmed by the analysis of redox changes of thiols and total thiols after MLT. This study has also demonstrated that albumin-dependent SH/SS exchange reactions are a potent regulation system of thiol redox species in plasma.

We report on a novel approach to cavity ring-down spectroscopy with the sample gas in saturated-absorption regime. This technique allows us to decouple and simultaneously retrieve the empty-cavity background and absorption signal, by means of a theoretical model that we developed and tested. The high sensitivity and frequency precision for spectroscopic applications are exploited to measure, for the first time, the hyperfine structure of an excited vibrational state of 17O12C16O in natural abundance with an accuracy of a few parts in 10{-11}.

A comprehensive investigation of the frequency-noise spectral density of a free-running midinfrared quantum-cascade laser is presented for the first time. It provides direct evidence of the leveling of this noise down to a white-noise plateau, corresponding to an intrinsic linewidth of a few hundred hertz. The experiment is in agreement with the most recent theory on the fundamental mechanism of line broadening in quantum-cascade lasers, which provides a new insight into the Schawlow-Townes formula and predicts a narrowing beyond the limit set by the radiative lifetime of the upper level.

A number of cortical and spinal excitability variables have been tested in a patient with Stiff Person Syndrome (SPS), before and after immunotherapy with mycophenolate mofetil, intravenous immunoglobulin and corticosteroids, which normalized plasma levels of anti-GAD antibodies and dramatically improved the clinical picture. The overlapping time-course of neurophysiological, clinical and bio-umoral findings suggests that immunotherapy might have changed GABA/Glutamate balance at cortical level, favoring the former, as reflected by normalization of the startle reflex, lengthening of the cortical silent period and clear-cut reduction of intracortical facilitation to paired-pulse transcranial magnetic stimulation. This represents the first report investigating effects of immunotherapy on cortical excitability in SPS.

Background: The investigation of a wide set of transcranial magnetic stimulation (TMS)-related variables in both hemispheres might help to identify a pattern of cortical excitability changes in posttraumatic stress disorder (PTSD) patients, reflecting gamma-amino-butiric acid (GABA)/glutamate balance and dysfunction, and to determine whether some of these variables are related to clinical features., Methods: In 20 drug-naive PTSD patients without comorbidity and 16 matched healthy control subjects we tested bilaterally with standard TMS procedures: resting motor threshold (RMT) to single-pulse TMS (reflecting ion channel function), paired-pulse short-latency intracortical inhibition (SICI; mainly reflecting GABA(A) function) and intracortical facilitation (ICF; mainly reflecting glutamatergic function), single-pulse cortical silent period (CSP; mainly reflecting GABA(B)-ergic function), and paired-pulse short-latency afferent inhibition (SAI; reflecting cholinergic mechanisms and their presynaptic GABA(A)-mediated modulation)., Results: The PTSD patients showed widespread impairment of GABA(A)-ergic SICI, which was reversed toward facilitation in both hemispheres in one-half of the patients, marked increase of glutamatergic ICF in the right hemisphere, and right-sided impairment of SAI. Illness duration and avoidance symptoms but not anxiety correlated with right-lateralized dysfunctions of cortical excitability., Conclusions: Although the neurobiological complexity of each TMS variable makes current results theoretical, the pattern of cortical excitability accompanying PTSD symptoms suggests a bilateral decrease of the GABA(A)-ergic function. This prevails in the right hemisphere, in association with a relative prevalence of the glutamatergic tone, a new finding that current neuroimaging investigations cannot provide due to the lack of reliable glutamate tracers. Results might help to disclose new pathophysiological aspects of PTSD symptoms, providing a rationale for future neuromodulatory strategies of treatment.

We report on a new coherent source that, using a phase-lock scheme to an optical frequency-comb synthesizer, achieves a 10-Hz intrinsic linewidth, is tunable from 4 to 4.5 microm with a presettable absolute frequency and, when coupled to a high-finesse cavity, can provide a short-term absorption sensitivity of 1.3 x 10(-11) cm(-1)Hz,(-1/2). These unique spectral features make this source a precise tool for molecular physics.

We report on what we believe to be the first Doppler-free polarization spectroscopy with a quantum cascade laser. A hot-band CO(2) transition around 4.3 microm wavelength has been used to test the potential of the technique for high-resolution spectroscopy and wide-bandwidth quantum cascade laser frequency stabilization.

Objective: The aim of this multicentric study was to multidimensionally evaluate the relationship among somatosensory evoked potentials (SEPs) parameters, patient's perspective and clinical measures of the upper limb impairment in patients with multiple sclerosis (MS)., Methods: We consecutively enrolled 39 MS patients. For median nerve SEPs we acquired the N9, P14, N20 responses and the N9-P14 and P14-N20 interpeak latencies on the dominant side. We also used a validated patient-oriented questionnaire (Disabilities of the Arm, Shoulder and Hand - DASH) and a test of dexterity quantification as the 9-Hole Peg Test (9-HPT)., Results: A significant longer time to complete the 9-HPT (p<0.00006) was observed in patients with abnormal SEPs. Patients with undetectable N20 or P14 responses performed the 9-HPT in a significant longer time than patients with detectable responses (p<0.0006 and p<0.001 respectively). Concerning the perspective of patient (evaluated with the DASH questionnaire) significant differences in patients with undetectable P14 response (p<0.01) were observed., Conclusions: Our data provide further information useful for interpretation of SEPs results, being the median nerve SEPs related to the upper limb performance in MS patients., Significance: These data increase the significance of SEPs both in clinical practice and in experimental studies in MS.

The frequency of a DFB quantum cascade laser (QCL) emitting at 4.3 microm has been long-term stabilized to the Lamb-dip center of a CO2 ro-vibrational transition by means of first-derivative locking to the saturated absorption signal. Thanks to the non-linear sum-frequency generation (SFG) process with a fiber-amplified Nd:YAG laser, the QCL mid-infrared (IR) radiation has been linked to an optical frequency-comb synthesizer (OFCS) and its absolute frequency counted with a kHz-level precision and an overall uncertainty of 75 kHz.

Study Objectives: To verify the existence of a symptomatic form of restless legs syndrome (RLS) secondary to multiple sclerosis (MS) and to identify possible associated risk factors., Design: Prospective, multicenter, case-control epidemiologic survey., Settings: Twenty sleep centers certified by the Italian Association of Sleep Medicine., Patients: Eight hundred and sixty-one patients affected by MS and 649 control subjects., Interventions: N/A., Measures and Results: Data regarding demographic and clinical factors, presence and severity of RLS, the results of hematologic tests, and visual analysis of cerebrospinal magnetic resonance imaging studies were collected. The prevalence of RLS was 19% in MS and 4.2% in control subjects, with a risk to be affected by RLS of 5.4 (95%confidence interval: 3.56-8.26) times greater for patients with MS than for control subjects. In patients with MS, the following risk factors for RLS were significant: older age; longer MS duration; the primary progressive MS form; higher global, pyramidal, and sensory disability; and the presence of leg jerks before sleep onset. Patients with MS and RLS more often had sleep complaints and a higher intake of hypnotic medications than patients with MS without RLS. RLS associated with MS was more severe than that of control subjects., Conclusions: RLS is significantly associated with MS, especially in patients with severe pyramidal and sensory disability. These results strengthen the idea that the inflammatory damage correlated with MS may induce a secondary form of RLS. As it does in idiopathic cases, RLS has a significant impact on sleep quality in patients with MS; therefore, it should be always searched for, particularly in the presence of insomnia unresponsive to treatment with common hypnotic drugs.

Background: Converging evidence indicates that action observation and action-related sounds activate cross-modally the human motor system. Since olfaction, the most ancestral sense, may have behavioural consequences on human activities, we causally investigated by transcranial magnetic stimulation (TMS) whether food odour could additionally facilitate the human motor system during the observation of grasping objects with alimentary valence, and the degree of specificity of these effects., Methodology/principal Findings: In a repeated-measure block design, carried out on 24 healthy individuals participating to three different experiments, we show that sniffing alimentary odorants immediately increases the motor potentials evoked in hand muscles by TMS of the motor cortex. This effect was odorant-specific and was absent when subjects were presented with odorants including a potentially noxious trigeminal component. The smell-induced corticospinal facilitation of hand muscles during observation of grasping was an additive effect which superimposed to that induced by the mere observation of grasping actions for food or non-food objects. The odour-induced motor facilitation took place only in case of congruence between the sniffed odour and the observed grasped food, and specifically involved the muscle acting as prime mover for hand/fingers shaping in the observed action., Conclusions/significance: Complex olfactory cross-modal effects on the human corticospinal system are physiologically demonstrable. They are odorant-specific and, depending on the experimental context, muscle- and action-specific as well. This finding implies potential new diagnostic and rehabilitative applications.

Somatosensory inputs to the primary sensory cortex (S1) after median nerve stimulation include temporally overlapping parallel processing, as reflected by standard low-frequency somatosensory-evoked potentials (LF-SEPs) and high-frequency SEPs (HF-SEPs), the latter being more sensitive to arousal and to other rapid adaptive changes. Experimental data suggest that cortical HF-SEPs are formed by two successive pre- and postsynaptic components, respectively, generated in the terminal part of thalamo-cortical radiation (early burst) and in specialized neuronal pools within S1 (later burst). In eight healthy subjects, slow (1 Hz) or rapid (10 Hz) repetitive transcranial magnetic stimulations (rTMS), which are known to induce opposite changes on cortical excitability, applied on S1 did not modify LF-SEPs, while HF-SEPs showed a series of dissociate changes in the early and later high-frequency burst, moreover occurring with a different time-course. Slow rTMS caused an immediate and lasting decrease of the later burst activity, coupled with an immediate increase of the earlier part of the burst, suggesting that inhibition of cortical excitability triggered opposite, compensatory effects at subcortical levels; rapid rTMS induced a delayed increase of later HF-SEPs, leaving unaltered the earlier subcortical burst. Findings causally demonstrate that LF- and HF-SEPs reflect two distinct functional pathways for somatosensory input processing, and that early and late high-frequency burst do actually reflect the activity of different generators, as suggested by experimental data. Possible underlying neurophysiological phenomena are discussed.

Background: Chronic tinnitus is a disabling, almost untreatable, condition, usually accompanied by psychiatric distress. In patients with complex neuropsychiatric diseases, such as chronic pain, with which tinnitus shares pathophysiological similarities, placebo effects may be pronounced. Moreover, it may be difficult to distinguish actual repetitive transcranial magnetic stimulation (rTMS) induced clinical benefits beyond placebo effects in neuropsychiatric patients., Methods: 16 patients with chronic tinnitus underwent a randomised, double blind, crossover, placebo controlled trial of 1 Hz rTMS (120% of motor threshold; 1200 stimuli/day for 5 days) of the left temporoparietal region. Patients were screened for psychiatric comorbidity; additionally, anxiety and depression were monitored throughout the study. Moreover, an original placebo rTMS procedure produced the same activation of ipsilateral face muscles (a condition which may per se change the subjective rating of tinnitus) as the real rTMS., Results: There were 8 out of 14 responders. Two patients dropped out for transient worsening of tinnitus. Active rTMS induced an overall significant, but transient, improvement (35% of the basal score) of subjective tinnitus perception that was independent of either tinnitus laterality or mood or anxiety changes. No correlations were found between response to rTMS and tinnitus duration, initial subjective score or patient age. When asked after the study was over, 71.4% of patients failed to identify the temporal sequence of the real or sham rTMS interventions., Conclusion: The beneficial effects of rTMS on tinnitus are independent of mood changes. Moreover, they appear in the context of an original placebo stimulation designed to more closely replicate the somatic sensation of active stimulation. Because of the limited temporal duration of the clinical benefit, these neuromodulatory effects could be mediated by transient functional changes taking place in the neural circuits underlying tinnitus processing.

In this paper, we used repetitive transcranial magnetic stimulation (rTMS) in 18 normal subjects to investigate whether the ventral posterior parietal cortex (PPC) plays a causal role on visuospatial attention and primary consciousness and whether these 2 functions are linearly correlated with each other. Two distinct experimental conditions involved a similar visual stimuli recognition paradigm. In "Consciousness" experiment, number of consciously perceived visual stimuli was lower by about 10% after rTMS (300 ms, 20 Hz, motor threshold intensity) on left or right PPC than after sham (pseudo) rTMS. In "Attentional" Posner's experiment, these stimuli were always consciously perceived. Compared with sham condition, parietal rTMS slowed of about 25 ms reaction time to go stimuli, thus disclosing effects on endogenous covert spatial attention. No linear correlation was observed between the rTMS-induced impairment on attention and conscious perception. Results suggest that PPC plays a slight but significant causal role in both visuospatial attention and primary consciousness. Furthermore, these high-level cognitive functions, as modulated by parietal rTMS, do not seem to share either linear or simple relationships.