Exploiting the Features of Short Peptides to Recognize Specific Cell Surface Markers

Antibodies are the macromolecules of choice to ensure specific recognition of biomarkers in biological assays. However, they present a range of shortfalls including a relatively high production cost and limited tissue penetration. Peptides are relatively small molecules able to reproduce sequences of highly specific paratopes and, although they have less biospecificity than antibodies, they offer advantages like ease of synthesis, modifications of their amino acid sequences and tagging with fluorophores and other molecules required for detection. This work presents a strategy to design peptide sequences able to recognize the CD44 hyaluronic acid receptor present in the plasmalemma of a range of cells including human bone marrow stromal mesenchymal cells. The protocol of identification of the optimal amino acid sequence was based on the combination of rational design and in silico methodologies. This protocol led to the identification of two peptide sequences which were synthesized and tested on human bone marrow mesenchymal stromal cells (hBM-MSCs) for their ability to ensure specific binding to the CD44 receptor. Of the two peptides, one binds CD44 with sensitivity and selectivity, thus proving its potential to be used as a suitable alternative to this antibody in conventional immunostaining. In the context of regenerative medicine, the availability of this peptide could be harnessed to functionalize tissue engineering scaffolds to anchor stem cells as well as to be integrated into systems such as cell sorters to efficiently isolate MSCs from biological samples including various cell subpopulations. The data here reported can represent a model for developing peptide sequences able to recognize hBM-MSCs and other types of cells and for their integration in a range of biomedical applications.

Supplementing Low-Sodium Bicarbonate-Calcic (Lete)® Water: Effects in Women on Bone and Systemic Metabolism

Calcium (Ca) represents about 40% of the total mineral mass, mainly in the bone, providing mechanical strength to the skeleton and teeth. An adequate Ca intake is necessary for bone growth and development in children and adolescents and for maintaining bone mineral loss in elderly age. Ca deficiency predisposes to osteopenia and osteoporosis. Healthy nutrition, including an adequate intake of Ca-rich food, is paramount to prevent and cure osteoporosis. Recently, several clinical studies have demonstrated that, in conditions of Ca dysmetabolism, Ca-rich mineral water is beneficial as a valuable source of Ca to be used as an alternative to caloric Ca-rich dairy products. Although promising, these data have been collected from small groups of participants. Moreover, they mainly regard the effect of Ca-rich mineral water on bone metabolism. In contrast, an investigation of the effect of Ca supplementation on systemic metabolism is needed to address the spreading of systemic metabolic dysfunction often associated with Ca dysmetabolism. In the present study, we analyzed urine and blood sera of 120 women in perimenopausal condition who were subjected for six months to 2l daily consumption of bicarbonate-calcium mineral water marketed under ®Lete. Remarkably, this water, in addition to being rich in calcium and bicarbonate, is also low in sodium. A complete set of laboratory tests was carried out to investigate whether the specific water composition was such to confirm the known therapeutic effects on bone metabolism. Second, but not least, urine and blood sera were analyzed using NMR-based metabolomic procedures to investigate, other than the action on Ca metabolism, potential system-wide metabolic effects. Our data show that Lete water is a valid supplement for compensating for Ca dysmetabolism and preserving bone health and integrity.

Monitoring the Conformational Changes of the Aβ(25-35) Peptide in SDS Micelles: A Matter of Time

Alzheimer's disease is a neurodegenerative disease characterized by the formation of amyloid plaques constituted prevalently by amyloid peptides. Due to the well-known challenges related to the study in solution of these peptides, several membrane-mimicking systems such as micelle constituted by detergent-i.e., DPC and SDS-have been deeply investigated. Additionally, the strategy of studying short fragments instead of the full-length peptide turned out to be advantageous in exploring the structural properties of the different moieties in Aβ in order to reproduce its pathologic effects. Several studies reveal that among Aβ fragments, Aβ(25-35) is the shortest fragment able to reproduce the aggregation process. To enrich the structural data currently available, in the present work we decided to evaluate the conformational changes adopted by Aβ(25-35) in SDS combining CD and NMR spectroscopies at different times. From the solved structures, it emerges that Aβ(25-35) passes from an unordered conformation at the time of the constitution of the system to a more ordered and energetically favorable secondary structure at day 7, which is kept for 2 weeks. These preliminary data suggest that a relatively long time affects the kinetic in the aggregation process of Aβ(25-35) in a micellar system, favoring the stabilization and the formation of a soluble helix conformation.

The Metabolomic Profile in Amyotrophic Lateral Sclerosis Changes According to the Progression of the Disease: An Exploratory Study

Amyotrophic lateral sclerosis (ALS) is a multifactorial neurodegenerative pathology of the upper or lower motor neuron. Evaluation of ALS progression is based on clinical outcomes considering the impairment of body sites. ALS has been extensively investigated in the pathogenetic mechanisms and the clinical profile; however, no molecular biomarkers are used as diagnostic criteria to establish the ALS pathological staging. Using the source-reconstructed magnetoencephalography (MEG) approach, we demonstrated that global brain hyperconnectivity is associated with early and advanced clinical ALS stages. Using nuclear magnetic resonance (¹H-NMR) and high resolution mass spectrometry (HRMS) spectroscopy, here we studied the metabolomic profile of ALS patients' sera characterized by different stages of disease progression-namely early and advanced. Multivariate statistical analysis of the data integrated with the network analysis indicates that metabolites related to energy deficit, abnormal concentrations of neurotoxic metabolites and metabolites related to neurotransmitter production are pathognomonic of ALS in the advanced stage. Furthermore, analysis of the lipidomic profile indicates that advanced ALS patients report significant alteration of phosphocholine (PCs), lysophosphatidylcholine (LPCs), and sphingomyelin (SMs) metabolism, consistent with the exigency of lipid remodeling to repair advanced neuronal degeneration and inflammation.

New Aβ(1-42) ligands from anti-amyloid antibodies: Design, synthesis, and structural interaction

Alzheimer's disease (AD), is the most common neurodegenerative disorder of the aging population resulting in progressive cognitive and functional decline. Accumulation of amyloid plaques around neuronal cells is considered a critical pathogenetic event and, in most cases, a hallmark of the pathology. In the attempt to identify anti-AD drug candidates, hundreds of molecules targeting Aβ peptides have been screened. Peptide molecules have been widely explored, appreciating chemical stability, biocompatibility, and low production cost. More recently, many anti-Aβ(1-42) monoclonal antibodies have been developed, given the excellent potential of immunotherapy for treating or preventing AD. Antibodies are versatile ligands that bind a large variety of molecules with high affinity and specificity; however, their extensive therapeutic application is complex and requires huge economic investments. Novel approaches to identify alternative antibody formats are considered with great interest. In this context, taking advantage of the favorable peptide properties and the availability of Aβ-antibodies structural data, we followed an innovative research approach to identify short peptide sequences on the model of the binding sites of Aβ(1-42)/antibodies. WAibH and SYSTPGK were designed as mimics of solanezumab and aducanumab, respectively. Circular dichroism and nuclear magnetic resonance analysis reveal that the antibody-derived peptides interact with Aβ(1-42) in the soluble monomeric form. Moreover, AFM microscopy imaging shows that WAibH and SYSTPGK are capable of controlling the Aβ(1-42) aggregation. The strategy to identify WAibH and SYSTPGK is innovative and can be widely applied for new anti-Aβ antibody mimicking peptides.

A New Approach to Supramolecular Structure Determination in Pharmaceutical Preparation of Self-Assembling Peptides: A Case Study of Lanreotide Autogel

The supramolecular structure in peptides’ prolonged-released gel formulations is the most critical parameter for the determination of the pharmaceutical profile of the drug. Here, we report our investigation on lanreotide Autogel as a case study. For the first time, we describe the use of the pulsed field gradient (PFG) diffusion-ordered spectroscopy (DOSY) magic-angle spinning NMR to characterize the supramolecular self-assembly and molecular mobility of different samples of lanreotide Autogel formulations prepared according to different formulation protocols. The diffusion coefficient was used to calculate the hydrodynamic radii of supramolecular assemblies and build relative molecular models. DOSY data were integrated with NMR imaging (MRI) measurements and atomic force microscopy (AFM) imaging.

Factors affecting cognitive remediation outcome in schizophrenia: The role of treatment resistance

Introduction

Treatment-resistant schizophrenia (TRS) represents a major clinical issue, characterized by worse psychopathological outcome, a more disrupted neurobiological substrate and higher healthcare costs. Cognitive impairment is a core feature of schizophrenia, strongly associated with patients’ functional outcome. Different studies showed that TRS patients exhibit poorer neurocognitive performance, particularly on verbal domains. To date Cognitive Remediation Therapy (CRT) represents the best available tool for treating cognitive deficits in schizophrenia. However, CRT outcomes are highly heterogeneous and significant treatment predictors are still lacking.

Objectives

To investigate possible differences of CRT outcome among patients with schizophrenia, stratified according to antipsychotic response (TRSs vs. first-line responders - FLRs).

Methods

150 patients with schizophrenia, (95 FLRs, 55 TRSs) were assessed for neurocognition with BACS and WCST at baseline and after CRT. General Linear Models (GLMs) were performed to investigate possible differences between groups on basal cognition and CRT outcome (Cohen’s d Effect Size).

Results

At baseline, GLMs showed significant differences in Verbal Memory (F=4,66; p=0,03) and WCST–executive functions (F=5,59; p=0,02), both worse in TRS group. Effecr Sizes of CRT outcome resulted significantly different in domains of Verbal Memory (F=4,68; p=0,03) and WCST–executive functions (F=4,62; p=0,03), with greater improvements among TRS patients.

Conclusions

This is the first study to indicate treatment-resistance as a possible predictor of CRT outcome in schizophrenia. Moreover, we observed that CRT resulted able to fill the cognitive gap between treatment groups. Thus, these results further highlight the importance of early cognitive interventions in order to reduce the neuropsychological and functional burden associated with the disease, especially for TRS patients.

Disclosure

No significant relationships.

Prenatal and Early Postnatal Cerebral d-Aspartate Depletion Influences l-Amino Acid Pathways, Bioenergetic processes, and Developmental Brain Metabolism

d-Amino acids were believed to occur only in bacteria and invertebrates. Today, it is well known that d-amino acids are also present in mammalian tissues in a considerable amount. In particular, high levels of free d-serine (d-Ser) and d-aspartate (d-Asp) are found in the brain. While the functions of d-Ser are well known, many questions remain unanswered regarding the role of d-Asp in the central nervous system. d-Asp is very abundant at the embryonic stage, while it strongly decreases after birth because of the expression of d-aspartate oxidase (Ddo) enzyme, which catalyzes the oxidation of this d-amino acid into oxaloacetate, ammonium, and hydrogen peroxide. Pharmacologically, d-Asp acts as an endogenous agonist of N-methyl d-aspartate and mGlu5 receptors, which are known to control fundamental brain processes, including brain development, synaptic plasticity, and cognition. In this work, we studied a recently generated knockin mouse model (R26^ddo/ddo), which was designed to express DDO beginning at the zygotic stage. This strategy enables d-Asp to be almost eliminated in both prenatal and postnatal lives. To understand which biochemical pathways are affected by depletion of d-Asp, in this study, we carried out a metabolomic and lipidomic study of ddo knockin brains at different stages of embryonic and postnatal development, combining nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HRMS) techniques. Our study shows that d-Asp deficiency in the brain influences amino acid pathways such as threonine, glycine, alanine, valine, and glutamate. Interestingly, d-Asp is also correlated with metabolites involved in brain development and functions such as choline, creatine, phosphocholine (PCho), glycerophosphocholine (GPCho), sphingolipids, and glycerophospholipids, as well as metabolites involved in brain energy metabolism, such as GPCho, glucose, and lactate.

New putative animal reservoirs of SARS-CoV-2 in Italian fauna: A bioinformatic approach

SARS-CoV-2 is a virus belonging to the betacoronavirus family, causing fatal respiratory disease in humans, which became pandemic in 2020. Italy is one of the most affected countries by COVID-19, particularly in the northern regions. Several studies consider COVID-19 a zoonotic disease and, since Italy is the repository of a high biodiversity, SARS-CoV-2 infection in animals can be considered as a reservoir of the virus or favor the spreading between animals and humans. In this work, we analyzed the amino acid sequences of ACE2 protein of the most common domestic and wild animals present in Italy. Among the latter, we focused on ACE2 of the Chiroptera species present in Italy to identify the primary reservoir in this region. First, we reproduced in silico the Chiroptera ACE2/viral spike (S) protein interactions on the human ACE2/SARS-CoV-2 S complex model and identified the critical residues for the binding. In silico molecular docking of ACE2 belonging to Chiroptera vs SARS-CoV-2 S protein pointed to Rhinolophus ferrumequinum as a bat living in Italy, that may be a potential primary reservoir of the virus. On the other hand, a sequence similarity search on ACE2 of domestic and wild animals living in Italy pointed to domestic (horses, cats, cattle and sheep) and wild (European rabbits and grizzly bears) animal species as potential SARS-CoV-2 secondary reservoirs. Molecular docking of ACE2 belonging to these species vs S protein of Bat coronavirus (Bt-CoV/Rp3/2004) suggests that the primary reservoir Rhinolophus ferrumequinum may infect the secondary reservoirs, domestic and worldwide animals living in Italy, determining a specific risk of SARS-CoV-2 infection.

NMR for screening and a biochemical assay: Identification of new FPPS inhibitors exerting anticancer activity

Farnesyl pyrophosphate synthase (FPPS) is a crucial enzyme for the synthesis of isoprenoids and the key target of nitrogen-containing bisphosphonates (N-BPs). N-BPs are potent and selective FPPS inhibitors that are used in the treatment of bone-related diseases, but have poor pharmacokinetic properties. Given the key role played by FPPS in many cancer-related pathways and the pharmacokinetic limits of N-BPs, hundreds of molecules have been screened to identify new FPPS inhibitors characterized by improved drug-like properties that are useful for broader therapeutic applications in solid, non-skeletal tumours. We have previously shown that N6-isopentenyladenosine (i6A) and its related compound N6-benzyladenosine (2) exert anti-glioma activity by interfering with the mevalonate pathway and inhibiting FPPS. Here, we report the design and synthesis of a panel of N6-benzyladenosine derivatives (compounds 2a-m) incorporating different chemical moieties on the benzyl ring. Compounds 2a-m show in vitro antiproliferative activity in U87MG glioma cells and, analogous to the bisphosphonate FPPS inhibitors, exhibit immunogenic properties in ex vivo γδ T cells from stimulated peripheral blood mononuclear cells (PBMCs). Using saturation transfer difference (STD) and quantitative ¹H nuclear magnetic resonance (NMR) experiments, we found that 2f, the N6-benzyladenosine analogue that includes a tertbutyl moiety in the para position of the benzyl ring, is endowed with increased FPPS binding and inhibition compared to the parent compounds i6A and 2. N6-benzyladenosine derivatives, characterized by structural features that are significantly different from those of N-BPs, have been confirmed to be promising chemical scaffolds for the development of non N-BP FPPS inhibitors, exerting combined cytotoxic and immunostimulatory activities.

Modifications in Coagulation Parameters Induced by Treatment Associating Urokinase (2000 u CTA/kg/h) with Heparin

Twenty-nine patients with deep venous thrombosis of the lower limbs were treated for 48 hours by intravenous infusion of urokinase (2000 u CTA/kg/h) and heparin (5 mg/kg/24 h).

Plasma coagulation parameters were measured every 12 hours. After 36 hours of therapy the following results were obtained – decrease in: fibrinogen levels (9% fall), plasminogen (40% decrease), α2-macroglobulin (9% decrease, but no change during the first 12 hours) and fast acting α2-antiplasmin (60% decrease); bidimensional electrophoresis consistently revealed 2 spikes during treatment: the first corresponded to complexed plasmin-fast acting α2-antiplasmin, the second corresponded to free, unconsumed fast acting α2-antiplasmin. Levels of α1-antitrypsin increased by 20% whereas the antithrombin III level remained stable. FDP levels increased slightly. Recalcified plasma coagulation times progressively increased.

Therapeutic results were evaluated on phlebography and showed, after 48 hours urokinase administration, improvement in 6 patients and no improvement in 17 cases. Consumption of plasminogen and production of FDP were both greater in the improved patient group.

The authors discuss these results and suggest that the dosage level of urokinase used in this study should be modified; it is concluded that a therapeutic regimen associating a loading dose with higher hourly administration levels is needed to achieve neutralization of fast acting α2-antiplasmin, a prerequisite to development of thrombolytic activity.

Targeting anxiety to improve quality of life in patients with schizophrenia

BACKGROUND

Several studies suggested that anxiety can significantly affect the outcome of schizophrenia. Despite this evidence, non-pharmacological interventions targeting anxiety are still heterogenous. This study aims to test the efficacy of a novel training specifically designed to target anxiety in patients with schizophrenia. Innovatively, this training, beyond psychoeducation and problem solving, also targets Theory of Mind, as it provides coping strategies.

METHOD

Twenty-seven outpatients with schizophrenia received a novel rehabilitative training targeting anxiety (Anxiety Management Group [AMG]) combined with a Computer-Assisted Cognitive Remediation (CACR), and twenty received CACR plus a control intervention (Control Newspaper discussion Group [CNG]). All patients were assessed at baseline and after treatment for quality of life, neurocognition and anxiety.

RESULTS

After training, patients treated with AMG+CACR showed significantly greater improvements on anxiety. A significant increase in quality of life was observed only for AMG+CACR group. Moreover, the participants' appraisal showed a significant difference between treatment groups with higher ratings among patients who received the AMG+CACR.

CONCLUSIONS

This study thus suggests feasibility and efficacy of the proposed intervention, that could be implemented in rehabilitative programs for patients with schizophrenia with potential benefits also on disease course and outcome.

Combined social cognitive and neurocognitive rehabilitation strategies in schizophrenia: neuropsychological and psychopathological influences on Theory of Mind improvement

BACKGROUND

Neurocognitive and social cognitive impairments represent important treatment targets in schizophrenia, as they are significant predictors of functional outcome. Different rehabilitative interventions have recently been developed, addressing both cognitive and psychosocial domains. Although promising, results are still heterogeneous and predictors of treatment outcome are not yet identified. In this study we evaluated the efficacy of two newly developed social cognitive interventions, respectively based on the use of videotaped material and comic strips, combined with domain-specific Cognitive Remediation Therapy (CRT). We also analysed possible predictors of training outcome, including basal neurocognitive performance, the degree of cognitive improvement after CRT and psychopathological variables.

METHOD

Seventy-five patients with schizophrenia treated with CRT, were randomly assigned to: social cognitive training (SCT) group, Theory of Mind Intervention (ToMI) group, and active control group (ACG).

RESULTS

ANOVAs showed that SCT and ToMI groups improved significantly in ToM measures, whereas the ACG did not. We reported no influences of neuropsychological measures and improvement after CRT on changes in ToM. Both paranoid and non-paranoid subjects improved significantly after ToMI and SCT, without differences between groups, despite the better performance in basal ToM found among paranoid patients. In the ACG only non-paranoid patients showed an improvement in non-verbal ToM.

CONCLUSION

Results showed that both ToMI and SCT are effective in improving ToM in schizophrenia with no influence of neuropsychological domains. Our data also suggest that paranoid symptoms may discriminate between different types of ToM difficulties in schizophrenia.

CaMKII inhibition rectifies arrhythmic phenotype in a patient-specific model of catecholaminergic polymorphic ventricular tachycardia

Induced pluripotent stem cells (iPSC) offer a unique opportunity for developmental studies, disease modeling and regenerative medicine approaches in humans. The aim of our study was to create an in vitro 'patient-specific cell-based system' that could facilitate the screening of new therapeutic molecules for the treatment of catecholaminergic polymorphic ventricular tachycardia (CPVT), an inherited form of fatal arrhythmia. Here, we report the development of a cardiac model of CPVT through the generation of iPSC from a CPVT patient carrying a heterozygous mutation in the cardiac ryanodine receptor gene (RyR2) and their subsequent differentiation into cardiomyocytes (CMs). Whole-cell patch-clamp and intracellular electrical recordings of spontaneously beating cells revealed the presence of delayed afterdepolarizations (DADs) in CPVT-CMs, both in resting conditions and after β-adrenergic stimulation, resembling the cardiac phenotype of the patients. Furthermore, treatment with KN-93 (2-[N-(2-hydroxyethyl)]-N-(4methoxybenzenesulfonyl)]amino-N-(4-chlorocinnamyl)-N-methylbenzylamine), an antiarrhythmic drug that inhibits Ca(2+)/calmodulin-dependent serine-threonine protein kinase II (CaMKII), drastically reduced the presence of DADs in CVPT-CMs, rescuing the arrhythmic phenotype induced by catecholaminergic stress. In addition, intracellular calcium transient measurements on 3D beating clusters by fast resolution optical mapping showed that CPVT clusters developed multiple calcium transients, whereas in the wild-type clusters, only single initiations were detected. Such instability is aggravated in the presence of isoproterenol and is attenuated by KN-93. As seen in our RyR2 knock-in CPVT mice, the antiarrhythmic effect of KN-93 is confirmed in these human iPSC-derived cardiac cells, supporting the role of this in vitro system for drug screening and optimization of clinical treatment strategies.

Effect of glutamate transporter EAAT2 gene variants and gray matter deficits on working memory in schizophrenia

Glutamate is the major excitatory neurotransmitter in the brain, with up to 40% of all synapses being glutamatergic. An altered glutamatergic transmission could play a critical role in working memory deficts observed in schizophrenia and could underline progressive changes such as grey matter loss throughout the brain. The aim of the study was to investigate if gray matter volume and working memory could be modulated by a genetic polymorphism related to glutamatergic function. Fifty schizophrenia patients underwent magnetic resonance and working memory testing outside of the scanner and were genotyped for rs4354668 EAAT2 polymorphism. Carriers of the G allele had lower gray matter volumes than T/T homozygote and worse working memory performance. Poor working memory performance was associated with gray matter reduction. Differences between the three genotypes are more relevant among patients showing poor performance at the 2-back task. Since glutamate abnormalities are known to be involved in excitotoxic processes, the decrease in cortical thickness observed in schizophrenia patients could be linked to an excess of extracellular glutamate. The differential effect of EAAT2 observed between good and poor performers suggests that the effect of EEAT2 on gray matter might reveal in the presence of a pathological process affecting gray matter.

Chronic pain: not only a matter of time

The term "chronic" is often used in daily clinical practice to indicate a type of pain that lasts over time and is accompanied by diagnostic and therapeutic difficulties. The common feeling is that in this category are actually collected many different clinical cases with the unique characteristic that the pain lasts a long time. It follows that treatment failures are common and patients roam from doctor to doctor in search of an effective care program. At the same time the health spending for the treatment of these patients is becoming increasingly high. In clinical practice we meet many patients with obscure pain syndromes which are classified as "chronic" and untreatable only because persist for long time and that obtain a complete pain relief after a right diagnosis and a specific treatment. In this review the Authors want to argue that the term chronic should not be used only when the pain persists for some time or just when signs and symptoms of mechanisms in the central nervous systems are present. The authors suggest that there is a clear difference between acute and chronic pain but also that in chronic pain patients there are three different painful conditions: 1) patients with a chronic disease (or sequelae) and with chronic pain in which the pain mechanisms are closely related to the underlying chronic disease (e.g., rheumatoid arthritis) or to previous injury that has generated other unsolvable mechanisms (e.g., deafferentation pain after plexus avulsion); 2) patients with a chronic disease and chronic pain in which new mechanisms overlap those related to the underlying disease; 3) patients with chronic pain in whom the correlation between pain and the initial tissue injury is lost and the persistence of pain is due to new developed mechanisms. According to this classification we can distinguish patients with "painful chronic disease" by patients with "independent chronic pain". In these latter cases the complexity of the clinical picture is to be found in a maladaptative response to pain, in emergence of central nervous system mechanisms and in behavioral changes that, in turn, can cause long-term social, psychological and physical sequelae. Differences among patients in developing chronic pain can be related to differences in the ability of the brain to continuously adapt its functional and structural organization. It is obvious that the care plan for these complex patients is profoundly different from that needed for patients with pain linked to a chronic disease or stabilized pain mechanisms. The purpose of the present article is to provide a review of the most noteworthy developments in this field and to propose some observations that may help to understand this pain condition and the patients.

Inhibition of somatosensory evoked potentials during spinal cord stimulation and its possible role in the comprehension of antalgic mechanisms of neurostimulation for neuropathic pain

BACKGROUND

Spinal cord stimulation (SCS) has been widely used for pain relief of patients with neuropathic chronic pain, frequently with only partial efficacy. Further advancements probably need a better understanding of SCS mechanisms, yet largely unknown. Aims of this paper were to answer the question if the lumbar SCS inhibits the tibial nerve somatosensory evoked potentials (SEPs) and to discuss the role of lemniscal afferents modulation in the antalgic mechanism of SCS.

METHODS

Ten consecutive patients successfully treated with implanted SCS devices for chronic pain in the lower limbs (four males, six females, age range 42-72 years) were enrolled. All the patients had an implanted system with an epidural lead connected to a pulse generator. The vertebral level ranged from T9 to T12. The cortical SEPs complex P39-N50-P60 was recorded at the basal (T0) evaluation, during the stimulation (T1) and immediately after the stimulation (T2).

RESULTS

In two of ten patients (20%) the complex P39-N50-P60 became unrelievable at the T1 control (stimulator on). In the remaining eight patients statistical analysis showed a significant reduction of the P39/N50 amplitude at T1 recording. In all patients considered, T0 and T2 recordings were not significantly different, suggesting a fast recovery of the SCS effect on SEPs.

CONCLUSION

The results obtained in the present study show an inhibitory effect of SCS on SEPs and support the hypothesis that in some forms of neuropathic pain the antalgic effect of SCS could be attributed to the collision of action potentials travelling in opposite direction on peripheral large diameter fibres.

Regional pattern of white matter microstructural changes in normal aging, MCI, and AD

OBJECTIVE

To cross-sectionally compare the regional white matter fractional anisotropy (FA) of cognitively normal (CN) older individuals and patients with mild cognitive impairment (MCI) and Alzheimer disease (AD), separately focusing on the normal-appearing white matter (NAWM) and white matter hyperintensities (WMH), and to test the independent effects of presumed degenerative and vascular process on FA differences.

METHODS

Forty-seven patients with AD, 73 patients with MCI, and 95 CN subjects received diffusion tensor imaging and vascular risk evaluation. To properly control normal regional variability of FA, we divided cerebral white matter into 4 strata as measured from a series of young healthy individuals (H1 = highest; H2 = intermediate high; H3 = intermediate low; H4 = lowest anisotropy stratum).

RESULTS

For overall cerebral white matter, patients with AD had significantly lower FA than CN individuals or patients with MCI in the regions with higher baseline anisotropy (H1, H2, and H3), corresponding to long corticocortical association fibers, but not in H4, which mostly includes heterogeneously oriented fibers. Vascular risk showed significant independent effects on FA in all strata except H1, which corresponds to the genu and splenium of the corpus callosum. Similar results were found within NAWM. FA in WMH was significantly lower than NAWM across all strata but was not associated with diagnosis or vascular risk.

CONCLUSIONS

Both vascular and Alzheimer disease degenerative process contribute to microstructural injury of cerebral white matter across the spectrum of cognitive ability and have different region-specific injury patterns.

Increase of the heat pain threshold during and after high-frequency transcutaneous peripheral nerve stimulation in a group of normal subjects

AIM

Transcutaneous electrical nerve stimulation (TENS) is used worldwide for pain relief, but its mechanisms of action are not completely understood. High frequency transcutaneous peripheral nerve stimulation (HF-TPNS) is a term describing a type of TENS where a peripheral nerve is stimulated transcutaneously. The aim of the investigation was to verify the hypothesis that HF-TPNS increases the heat pain threshold in the skin territory of the stimulated nerve, during and after stimulation.

METHODS

Eighteen volunteers (8 men, 10 women) participated in 2 sessions conducted on different days. In each session their heat pain thresholds were measured in basal conditions and after 5, 10, 15, 25, 40, 70 min. In one session, HF-TPNS was delivered for 10 min immediately after basal evaluation (HF-TPNS session). In the other session the heat pain thresholds only were measured (control session). The superficial radial nerve was stimulated at the wrist (frequency of 100 Hz, pulse duration of 0.1 ms). The heat pain threshold was studied using a contact thermode (surface of 12.5 cm(2)) placed in the cutaneous area of the stimulated nerve at the site where the paresthesia evoked by electrical stimulation could be felt.

RESULTS

HF-TPNS significantly increased the heat pain threshold both during and after stimulation.

CONCLUSION

This study confirms that HF-TPNS induces an important hypoalgesic effect. The prolonged duration of poststimulation hypoalgesia (60 min) indicates that continuous stimulation is probably unnecessary. Further studies are needed to test the hypothesis that intermittent HF-TPNS is able to maintain its hypoalgesic effectiveness over time.

Are hot-burning sensations produced by the axonal damage of afferent unmyelinated fibres?

AIM

Pain resulting from nerve lesions is classically referred to as a ''burning pain''. Both the axonal damage and sensitization of unmyelinated C-fibres have been considered as the possible generators of this sensation. The aim of this study was to verify the hypothesis that hot-burning sensations are produced by the axonal damage of afferent unmyelinated fibres in peripheral nerves.

METHODS

A total of 122 patients with pain localised in the distal parts of the upper limbs (hand, forearm) and lower limbs (leg or foot) were enrolled in the study. The intensity of pain and hot-burning sensations was measured using a numerical scale (range 0-10). The relationship between the presence of warm hypoesthesia (related to the loss of afferent unmyelinated fibres) and hot-burning sensations was assessed. Warm hypoesthesia was identified by Quantitative Sensory Testing employing thermal stimulation (QST-t) and the patients were divided into 2 groups: group A, with hypoesthesia and group B with normoesthesia. Patients with a central nervous impairment were excluded.

RESULTS

No significant differences in the intensity of pain and hot-burning sensations was observed between the group of patients with warm hypoesthesia and that with warm normoesthesia.

CONCLUSIONS

This study does not confirm the hypothesis that hot-burning sensations are produced by the axonal damage of afferent amyelinated fibres in peripheral nerves. It agrees with clinical evidence suggesting that patients with different clinical conditions can complain of hot-burning sensations, independently of the presence of a nerve lesion.

Improvement of muscle strenght independently of analgesic effect following spinal cord stimulation. A case report

Spinal cord stimulation (SCS) is frequently used for relief of chronic benign pain resistant to conservative therapies. Clinical practice suggests, at least in patients with failed back surgery syndrome (FBSS), the possibility that SCS significantly improves motor performances. We present here the case of a 41-years-old female patient with FBSS, who showed a clear improvement in muscle strength after SCS, persisting at 6-months follow-up. We speculate that the electrical stimulation of posterior columns could potentiate the caudal, segmental spinal reflexes resulting in a facilitation of motoneurons activation.

Preliminary evidence that estrogen protects against age-related hippocampal atrophy

Few studies have examined gender differences in hippocampal volumes, and the potential effect of estrogen on these measures has not been well studied. We used MRI to measure hippocampal volumes in elderly Mexican American men and women subjects in order to determine if there were gender differences and if estrogen replacement therapy (ERT) had an effect on hippocampal volume in postmenopausal women. MRI measures of hippocampal volumes (normalized to intracranial volume) were compared in 59 women and 38 men. Further comparisons were made between men subjects, women subjects taking ERT, and women subjects not taking ERT. There were no significant effects of gender on normalized hippocampal volumes. However, women subjects taking ERT had larger right hippocampal volumes than women subjects not taking ERT and larger anterior hippocampal volumes than men subjects and women subjects not taking ERT. These findings suggest a neuroprotective effect of estrogen.

[Validation of the Italian version of the "Neuropathic Pain Scale" and its clinical applications]

BACKGROUND

The Neuropathic Pain Scale is the first specific tool to measure and analyse pain due to a lesion in the nervous system; this kind of pain is usually difficult to describe for the patient because it is characterized by unusual qualities. Aim of this study is to evaluate a possible relation between pain descriptions and underlying pathogenetic mechanisms.

METHODS

The Italian version of the Neuropathic Pain Scale has been administered to 145 patients with neuropathic pain due to chronic radiculopathy, diabetic neuropathy, post-traumatic neuropathy, Complex Regional Pain Syndrome or postherpetic neuralgia. As it has been done in Galer's study, the predictive validity and the items' correlation have been evaluated; moreover, the structure validity of the scale has been studied.

RESULTS

Pain values were high in all pain syndromes with the prevalence of certain items in particular pathologies. The correlation of some items with "deep pain" and others with "superficial pain" was also observed.

CONCLUSIONS

The results have confirmed the statistical validity of the Italian version of the scale; they also pointed out the usefulness of the scale to distinguish between superficial pain, typical of neuropathic pain, and deep pain, typical of somatic pain.

[Neuropathic pain syndromes: from their diagnosis to the return to work. Proposal of a model for rapid evaluation and therapy based on their pathogenic mechanisms]

The therapeutic approach to neuropathic pain differs significantly among physicians. This is in large part because of the relative paucity of randomized clinical trials and the scarcity of comparative studies with different drugs. Clinical studies on the efficacy of a drug or a technique are generally referred to the pathologic diagnosis and not to the pain mechanism. We have learned from animal models the different pain mechanisms which may be involved in the peripheral nerves and the spinal cord. Unfortunately, one mechanism could be responsible for many different symptoms, while the same symptom can be caused by different mechanisms. The authors propose a simple model to evaluate the patients in order to define the mechanisms involved an to select the treatment strategy. The diagnostic model allows classification of the patient into four groups according to pain mechanism (spinal neurons sensitization due to deafferentation, ectopic discharges in peripheral nociceptive C fibers, spinal neurons sensitization due to ectopic discharges in peripheral nociceptive C fibers, spinal neurons sensitization due to nociceptors sensitization). The authors propose also a second step in which a fifth mechanism, adrenosensitivity, is evaluated. Treatment options may target any of the mechanisms discussed. Drugs and analgesic techniques can be classified according to their action on pain mechanisms. The authors identify in the literature some drugs and techniques which can be tested in each defined groups. A complementary and multidisciplinary rehabilitative approach of chronic pain patients is recommended.

Alcoholic polyneuropathy: a clinical and epidemiological study

In the present study, we investigated the frequency of polyneuropathy in a sample of 296 alcoholics who were admitted to the 'S. Maugeri' Medical Centre for detoxification from October 1997 to November 1999. Results revealed a high frequency of polyneuropathy in the sample under study. The disorder was often clinically asymptomatic and demonstrable only on electroneurographic investigation. Significant correlations were found between polyneuropathy, the duration of alcoholism, the type of alcoholic beverage consumed (wine) and the presence of liver disease and macrocytosis.

Myoelectric manifestations of muscle changes in stroke patients

OBJECTIVE

To evaluate the development of myoelectric fatigue in paretic and healthy tibialis anterior muscles of stroke patients.

DESIGN

Case series.

SETTING

Occupational therapy and clinical neurophysiology unit.

PARTICIPANTS

Eight patients with hemiparesis or hemiplegia 9 months to 10 years poststroke.

MAIN OUTCOME MEASURES

Current pulses of 0.1-ms width and 40-Hz repetition rate were applied for 10 seconds with a monopolar technique; myoelectric signals (M waves) were detected with surface electrodes.

RESULTS

Mean values and initial values of the median frequency (MDF) between paretic and healthy side were statistically different, with the values on the healthy side much higher than the paretic side. Changes of MDF showed a decreasing pattern for both the paretic and the healthy sides, with the downslope of the curve of the healthy side more evident.

CONCLUSIONS

In paretic muscles of stroke patients, the tendency toward atrophy of type II fibers appears to be frequent. Our study suggests this muscle rearrangement uses techniques much less invasive than muscle biopsy, and gives useful information about muscle function. This kind of information can help identify rehabilitation strategies, particularly for chronic stroke survivors.

Mild ciguatera poisoning: Case reports with neurophysiological evaluations

Ciguatera poisoning causes mainly gastrointestinal and neurological effects of variable severity. However, symptoms of peripheral neuropathy with paresthesias and paradoxical disturbance of thermal sensation are the hallmark. Electrophysiological studies are often normal, except in severe cases. We report four people who developed mild ciguatera poisoning after barracuda ingestion. Electrophysiological studies documented normocalcemic latent tetany. These findings are consistent with ciguatoxin's mechanism of toxicity, which involves inactivation of voltage-gated Na(+) channels and eventually increases nerve membrane excitability.

Somatosensory cortex: a comparison of the response to noxious thermal, mechanical, and electrical stimuli using functional magnetic resonance imaging

In the present study, functional magnetic resonance imaging (fMRI) was used to examine pain perception in humans. Three types of noxious stimuli were presented: electric shock (20.8 mA, 2 Hz), heat (48 degrees C), and mechanical, as well as a control tactile stimulus. The significance of activation at the level of the voxel was determined using correlation analysis. Significant region of interest (ROI) activation was determined by comparing the percentage of active voxels in each ROI to activation in a control ROI in the visual cortex. In response to tactile and shock stimuli, consistent activation was seen in the postcentral gyrus, parietal operculum, and ipsilateral cerebellar cortex. No significant cortical activation was detected in response to noxious heat or mechanical stimulation when compared to nonpainful intensity levels. The data did not indicate adaptation, although further study in this area is necessary. Stationary noxious thermal and mechanical stimulation are "pure" noxious stimuli, while electrical stimulation influenced nociceptive and nonnociceptive receptors. Lack of detectable activation in response to pure noxious stimuli supports the idea that nociceptive and nonnociceptive fibers are interspersed in the somatosensory cortex. Conflicting results from recent functional imaging studies of pain perception regarding cortical activation indicate that it is essential to consider both the tactile and nociceptive components of the stimuli used, the spatial extent of stimulation, and the possibility of adaptation to the response. Furthermore, these results suggest that subtractive or correlative methods may not be sufficiently sensitive to image the activity of nociceptive cells, which are sparsely distributed throughout the somatosensory cortex.

[Visual reaction times in a group of patients with single cerebrovascular lesions in rehabilitation]

Approximately fifty percent of stroke survivors have neurological deficits. The evaluation of reaction times permits a study of psychomotor performance, which could be very important for a good rehabilitation outcome.

AIM

The aim of the study was the evaluation of visual reaction times in a group of patients with cerebrovascular lesions, during inpatient hospitalisation in a rehabilitation centre.

MATERIALS AND METHODS

46 right-handed patients (34M, 12F) with unilateral cerebrovascular lesion, confirmed by CT or MRI, were enrolled in the study. In each patients visual Simple Reaction Times (SRT) and Multiple Choice Reaction Times (MCRT) were studied. The patients were asked to react by using the hand ipsilateral to the side of the cerebral lesion. Functional impairment of walking, upper limb and hand were measured by a tailored clinical scale with score ranging from 1 to 12. Depression was measured by a modified version of Hamilton scale, tailored for this kind of patient.

RESULTS

13 of 46 patients (28.2%) showed a pathologic reaction time. There was a lack of correlation between reaction times and age, aphasia, lesion size, time from stroke, functional impairment. Patients with hemorrhagic lesions had significantly lower SRT and MCRT. The subgroup of patients with pathologic reaction times were significantly more depressed than patients with normal reaction times.

CONCLUSION

Judging from the present set of results: a) patients with hemorrhagic lesions have lower reaction times; b) the prolongation of reaction times and post-stroke depression appear to be related in stroke patients. This relationship seems to suggest that post stroke depression can negatively affect functional recovery also by means of an impairment of psychomotor performance.

Two methods for the measurement of voluntary contraction torque in the biceps brachii muscle

Appropriate measurement of maximal voluntary contraction force of a single limb muscle or of a muscle group is important in clinical and research situations. To measure muscle force, one segment of an isometric measuring brace is fixed to a support and force is applied to the other. The output of this arrangement is affected by additional contributions such as pushing or pulling with the whole body. This paper quantifies the differences between measurements of torque produced by the biceps brachii with the brace fixed versus those produced when the elbow joint was isolated by suspending the brace from cables. No statistically significant differences were found between MVC values observed with the two methods within subjects. However, a statistically significant difference in EMG fatigue indices was observed and attributed to a different sharing of force production among different muscles in the two conditions. We conclude that different brace arrangements may lead to the same maximal force but to different rates of myoelectric manifestations of muscle fatigue since the effort may be shared differently among the muscles of synergic or stabilizing groups.

HCV genotypes in Northern Italy: a survey of 1368 histologically proven chronic hepatitis C patients

BACKGROUND/AIMS

Hepatitis C virus (HCV) easily undergoes genomic changes, thus accounting for the presence of different genotypes, with different geographic distributions and different outcomes of chronic hepatitis. Type 1b is frequently found in advanced diseases; however, since this genotype is the most prevalent in older patients, the association with advanced age and severity of the disease is confounding. The aim of this study was to assess changes in the prevalence of HCV genotypes by surveying a large population of chronic hepatitis C patients in Northern Italy, and to assess if the high prevalence of genotype 1b in older patients with advanced diseases simply reflects the duration of HCV infection, rather than intrinsic biological properties of HCV.

METHODS

We studied 1368 HCV-RNA positive patients, with histologically proven chronic hepatitis. Drug addiction, blood transfusions and sporadically acquired infections represented the risk factors.

RESULTS

Genotype 1b, the most prevalent isolate, and genotype 2a were associated with older age, cirrhosis, sporadically-acquired infections and blood transfusion, while types 1a, 3a, and 4 were associated with younger age, chronic persistent hepatitis and drug addiction. Patients with a history of transfusions were divided into four groups depending on the period of transfusion. The prevalence of genotype 1b decreased with time. Type 3a appeared only after 1979.

CONCLUSION

The severity of chronic hepatitis C could be related more to the duration of the infection rather than to the intrinsic pathogenicity of HCV genotypes.

[The clinical evaluation of conservative treatment in patients with the thoracic outlet syndrome]

Conservative treatment of thoracic outlet syndrome is frequently recommended but few studies reporting conservative management are present in literature. Thirteen out-patients with thoracic outlet syndrome (4 males, 9 females) were admitted to a conservative treatment (massage and kinesitherapy) involving the cervical spine and shoulder girdle. All the patients were satisfied with the outcome of the treatment. In particular rest symptoms completely disappeared after treatment in all patients. This study confirms the efficacy of physical therapy in the conservative treatment of patients with thoracic outlet syndrome. Further studies on long-term outcome are needed.

Early development of EMG localized muscle fatigue in hand muscles of patients with chronic heart failure

BACKGROUND

Patients with chronic heart failure (CHF) frequently complain of fatigue and exercise intolerance that are not directly related to the severity of cardiac failure. A not well-defined muscle function impairment is generally considered the cause of such symptoms. The frequency compression of electromyographic (EMG) signal power spectrum during isometric contractions is commonly accepted as an index of the fatigue occurring in the muscle (localized muscle fatigue).

PURPOSE AND METHODS

The purpose of the study was to evaluate muscle fatigue development in a selected group of CHF patients by studying the compression of the EMG signal power spectrum. The first dorsal interosseus of the right, dominant hand was investigated at two levels of contraction: 40% and 80% of the maximal voluntary contraction (MVC).

RESULTS

In CHF patients there was early development of localized muscle fatigue during the high level of contraction (80% of MVC).

CONCLUSION

This study demonstrates the presence of an early development of localized muscle fatigue in CHF patients and confirms the possibility of an increased glycolytic metabolism. Moreover, the changes seem to show that muscle impairment is not limited to large muscles, but also occurs in small muscles of the hands, frequently used during daily activities. Finally, this study confirms the validity of EMG spectral analysis techniques in evaluating muscle fatigue of CHF patients, suggesting a possible use in the rehabilitation of such patients when the technique is correctly used.

Somatosensory cortex: a comparison of the response to noxious thermal, mechanical, and electrical stimuli using functional magnetic resonance imaging

In the present study, functional magnetic resonance imaging (fMRI) was used to examine pain perception in humans. Three types of noxious stimuli were presented: electric shock (20.8 mA, 2 Hz), heat (48 degrees C), and mechanical, as well as a control tactile stimulus. The significance of activation at the level of the voxel was determined using correlation analysis. Significant region of interest (ROI) activation was determined by comparing the percentage of active voxels in each ROI to activation in a control ROI in the visual cortex. In response to tactile and shock stimuli, consistent activation was seen in the postcentral gyrus, parietal operculum, and ipsilateral cerebellar cortex. No significant cortical activation was detected in response to noxious heat or mechanical stimulation when compared to nonpainful intensity levels. The data did not indicate adaptation, although further study in this area is necessary. Stationary noxious thermal and mechanical stimulation are "pure" noxious stimuli, while electrical stimulation influenced nociceptive and nonnociceptive receptors. Lack of detectable activation in response to pure noxious stimuli supports the idea that nociceptive and nonnociceptive fibers are interspersed in the somatosensory cortex. Conflicting results from recent functional imaging studies of pain perception regarding cortical activation indicate that it is essential to consider both the tactile and nociceptive components of the stimuli used, the spatial extent of stimulation, and the possibility of adaptation to the response. Furthermore, these results suggest that subtractive or correlative methods may not be sufficiently sensitive to image the activity of nociceptive cells, which are sparsely distributed throughout the somatosensory cortex.