Clinical characterization of new-onset chronic musculoskeletal pain in Long COVID: a cross-sectional study (preprint)

Purpose: New-onset chronic musculoskeletal (MSK) pain is one of the common persistent symptoms in Long COVID (LC). This study investigated its clinical characteristics, underlying mechanisms, and impact on function, psychological health, and quality of life. Patients and methods: 30 adults (19 female, 11 male) with LC and new-onset chronic MSK pain underwent clinical examination, Quantitative Sensory Testing (QST), and blood tests for inflammatory markers, and completed the following outcome measures: Timed Up and Go test (TUG), handgrip strength test, COVID-19 Yorkshire Rehabilitation Scale (C19-YRS), Brief Pain Inventory (BPI), Pain Self-Efficacy Questionnaire (PSEQ), Pain Catastrophizing Scale (PCS), International Physical Activity Questionnaire - short form (IPAQ-sf), Generalized Anxiety Disorder (GAD-7), Patient Health Questionnaire (PHQ-9), and EuroQol Five Dimensions health-related quality of life (EQ-5D-5L). Results: New-onset chronic MSK pain was widespread and continuous in nature, and worse in the joints. When compared to normative values reported in the literature: a) QST revealed mechanical hyperalgesia, heightened temporal summation of pain, and hypoesthesia to vibration stimuli, which is strongly suggestive of central sensitization; b) Plasma cytokine assays indicated distinct pro- inflammatory profiles; c) TUG time indicated reduced balance and mobility; d) handgrip strength revealed general weakness; e) physical activity was lower ; and f) there were moderate levels of depression and anxiety with lower self-efficacy scores and lower levels of pain catastrophizing. LC symptoms were of moderate severity (44.8/100), moderate functional disability (22.8/50) and severely compromised overall health (2.6/10) when compared to pre-COVID scores. Conclusion: New-onset chronic MSK pain in LC tends to be widespread, constant, and associated with weakness, reduced function, depression, anxiety, and reduced quality of life. There is associated central sensitization and proinflammatory state in the condition. Further research is essential to explore the longitudinal progression and natural evolution of the new-onset chronic MSK pain in LC.

Structure-Activity Relationship (SAR) Study of Rigid Guanidine and Guanidino-mimetic Analogues of the Neuropeptide FF Receptor Antagonist MES304 (preprint)

The Neuropeptide FF (NPFF) receptor system has been implicated in mediating opioid-induced hyperalgesia and tolerance. Understanding the structural features that contribute to high binding affinity of ligands to the NPFF receptors could help in identifying potent and selective NPFF-R probes. We conducted a structure-activity relationship (SAR) study targeting the guanidine functionality of our previously identified lead molecule MES304 in order to probe the guanidine binding site of the NPFF receptors. By applying several rigidifying modifications and substitutions on the guanidine moiety, we concluded that while the guanidine group is optimal for strong binding affinity at both receptor subtypes (NPFF1-R/NPFF2-R), other groups may be tolerated. Compound 17b, in which the guanidine was replaced with a piperidine ring, displayed robust binding affinity at both receptor subtypes (Ki < 300 nM) despite lacking a guanidine group. This indicated that strong binding to the NPFF receptors can be achieved with analogues devoid of guanidine.

Inhibition of Monoacylglycerol Lipase by NSD1819 as an Effective Strategy for the Endocannabinoid System Modulation against Neuroinflammation-Related Disorders.

Neuroinflammation is a key pathological event shared by different diseases affecting the nervous system. Since the underlying mechanism of neuroinflammation is a complex and multifaceted process, current pharmacological treatments are unsatisfactory-a reason why new therapeutic approaches are mandatory. In this context, the endocannabinoid system has proven to possess neuroprotective and immunomodulatory actions under neuroinflammatory status, and its modulation could represent a valuable approach to address different inflammatory processes. To this aim, we evaluated the efficacy of a repeated treatment with NSD1819, a potent ß-lactam-based monoacylglycerol lipase inhibitor in a mouse model of neuroinflammation induced by lipopolysaccharide (LPS) injection. Mice were intraperitoneally injected with LPS 1 mg/kg for five consecutive days to induce systemic inflammation. Concurrently, NSD1819 (3 mg/kg) was daily per os administered from day 1 until the end of the experiment (day 11). Starting from day 8, behavioral measurements were performed to evaluate the effect of the treatment on cognitive impairments, allodynia, motor alterations, anhedonia, and depressive-like behaviors evoked by LPS. Histologically, glial analysis of the spinal cord was also performed. The administration of NSD1819 was able to completely counteract thermal and mechanical allodynia as highlighted by the Cold plate and von Frey tests, respectively, and to reduce motor impairments as demonstrated by the Rota rod test. Moreover, the compound was capable of neutralizing the memory loss in the Passive avoidance test, and reducing depressive-like behavior in the Porsolt test. Finally, LPS stimulation caused a significant glial cells activation in the dorsal horn of the lumbar spinal cord that was significantly recovered by NSD1819 repeated treatment. In conclusion, NSD1819 was able to thwart the plethora of symptoms evoked by LPS, thus representing a promising candidate for future applications in the context of neuroinflammation and related diseases.

Argentine Registry of neurological manifestations due to coronavirus-19 (COVID-19) (preprint)

COVID-19 disease has spread around the world since December 2019. Neurological symptoms are part of its clinical spectrum. Objective: To know the neurological manifestations in patients infected by COVID-19 in Argentina. Methods: Multicenter study conducted in adults, from May 2020 to January 2021, with confirmed COVID-19 and neurological symptoms. Demographic variables, existence of systemic or neurological comorbidities, the form of onset of the infection, alteration in complementary studies and the degree of severity of neurological symptoms were recorded. Results: 817 patients from all over the country were included, 52% male, mean age 38 years, most of them without comorbidities or previous neurological pathology. The first symptom of the infection was neurological in 56.2% of the cases, predominantly headache (69%), then anosmia / ageusia (66%). Myalgias (52%), allodynia / hyperalgesia (18%), and asthenia (6%) were also reported. 3.2% showed diffuse CNS involvement such as encephalopathy or seizures. 1.7% had cerebrovascular complications. Sleep disorders were observed in 3.2%. 6 patients were reported with Guillain Barre (GBS), peripheral neuropathy (3.4%), tongue paresthesia (0.6%), hearing loss (0.4%), plexopathy (0.3%). The severity of neurological symptoms was correlated with age and the existence of comorbidities. Conclusions: Our results, similar to those of other countries, show two types of neurological symptoms associated with COVID-19: some potentially disabling or fatal such as GBS or encephalitis, and others less devastating, but more frequent such as headache or anosmia that demand increasingly long-term care.

Facemask headache: a new nosographic entity among healthcare providers in COVID-19 era.

BACKGROUND: SARS-CoV-2 is a novel infectious agent causing coronavirus disease 2019, which has been declared as pandemic in March 2020. Personal protective equipment has been mandatory for healthcare workers in order to contain the outbreak of pandemic disease. Mild neurological disturbances such as headache have been related to the extensive utilization of facemask. This study aims to examine headache variations related to the intensive utilization of facemask among a cohort of healthcare professionals in a setting of low-medium risk of exposure to SARS-CoV-2. METHODS: This is a cross-sectional study among healthcare providers from different hospital and clinics in Italy. Each participant completed a specifically designed self-administered questionnaire. Headache features and outcome measures' change from baseline were evaluated over a 4-month period, in which wearing facemask has become mandatory for Italian healthcare workers. RESULTS: A total of 400 healthcare providers completed the questionnaire, 383 of them met the inclusion criteria. The majority were doctors, with a mean age of 33.4 ± 9.2 years old. Among 166/383 subjects, who were headache free at baseline, 44 (26.5%) developed de novo headache. Furthermore, 217/383 reported a previous diagnosis of primary headache disorder: 137 were affected by migraine and 80 had tension-type headache. A proportion (31.3%) of these primary headache sufferers experienced worsening of their pre-existing headache disorder, mainly for migraine frequency and attack mean duration. CONCLUSIONS: Our data showed the appearance of de novo associated facemask headache in previous headache-free subjects and an exacerbation of pre-existing primary headache disorders, mostly experienced by people with migraine disease.