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Impaired rate-dependent depression (RDD) of the Hoffman reflex is associated with reduced dorsal spinal cord potassium chloride cotransporter expression and impaired spinal γ-aminobutyric acid type A receptor function, indicative of spinal inhibitory dysfunction. We have investigated the pathogenesis of impaired RDD in diabetic rodents exhibiting features of painful neuropathy and the translational potential of this marker of spinal inhibitory dysfunction in human painful diabetic neuropathy. Impaired RDD and allodynia were present in type 1 and type 2 diabetic rats but not in rats with type 1 diabetes receiving insulin supplementation that did not restore normoglycemia. Impaired RDD in diabetic rats was rapidly normalized by spinal delivery of duloxetine acting via 5-hydroxytryptamine type 2A receptors and temporally coincident with the alleviation of allodynia. Deficits in RDD and corneal nerve density were demonstrated in patients with painful diabetic neuropathy compared with healthy control subjects and patients with painless diabetic neuropathy. Spinal inhibitory dysfunction and peripheral small fiber pathology may contribute to the clinical phenotype in painful diabetic neuropathy. Deficits in RDD may help identify patients with spinally mediated painful diabetic neuropathy who may respond optimally to therapies such as duloxetine.

Background: Epidemiological and toxicological studies indicate that increased exposure to air pollutants can lead to neurodegenerative diseases. To further confirm this relationship, we evaluated the association between exposure to ambient air pollutants and corneal nerve measures as a surrogate for neurodegeneration, using corneal confocal microscopy. Methods: We used population-based observational cross-sectional data from The Maastricht Study including N = 3635 participants (mean age 59.3 years, 51.6% were women, and 19.9% had type 2 diabetes) living in the Maastricht area. Using the Geoscience and hEalth Cohort COnsortium (GECCO) data we linked the yearly average exposure levels of ambient air pollutants at home address-level [particulate matter with diameters of ≤ 2.5 µm (PM2.5), and ≤ 10.0 µm (PM10), nitrogen dioxide (NO2), and elemental carbon (EC)]. We used linear regression analysis to study the associations between Z-score for ambient air pollutants concentrations (PM2.5, PM10, NO2, and EC) and Z-score for individual corneal nerve measures (corneal nerve bifurcation density, corneal nerve density, corneal nerve length, and fractal dimension). Results: After adjustment for potential confounders (age, sex, level of education, glucose metabolism status, corneal confocal microscopy lag time, inclusion year of participants, smoking status, and alcohol consumption), higher Z-scores for PM2.5 and PM10 were associated with lower Z-scores for corneal nerve bifurcation density, nerve density, nerve length, and nerve fractal dimension [stβ (95% CI): PM2.5 -0.10 (-0.14; -0.05), -0.04 (-0.09; 0.01), -0.11 (-0.16; -0.06), -0.20 (-0.24; -0.15); and PM10 -0.08 (-0.13; -0.03), -0.04 (-0.09; 0.01), -0.08 (-0.13; -0.04), -0.17 (-0.21; -0.12)], respectively. No associations were found between NO2 and EC and corneal nerve measures. Conclusions: Our population-based study demonstrated that exposure to higher levels of PM2.5 and PM10 are associated with higher levels of corneal neurodegeneration, estimated from lower corneal nerve measures. Our results suggest that air pollution may be a determinant for neurodegeneration assessed in the cornea and may impact the ocular surface health as well. [ABSTRACT FROM AUTHOR]

Aims: To develop a standardised, automated protocol for detecting protein gene product 9.5 (PGP9.5) positive intra‐epidermal nerve fibres (IENFs) in skin biopsies, transitioning from the established manual technique to an automated platform. This automated method, although currently intended for research applications, may improve the accessibility of this diagnostic test for small fibre neuropathy in clinical settings. Methods: Skin biopsies (n = 274) from 100 participants (fibromyalgia syndrome n = 62; idiopathic small fibre neuropathy: n = 16; healthy volunteers: n = 22) were processed using an automated immunohistochemistry platform. IENF quantification was performed by blinded examiners, with reliability assessed via a two‐way mixed‐effects model to evaluate inter‐ and intra‐observer variability. Results: The automated staining system reproduced intra‐epidermal nerve fibre density (IENFD) counts consistent with free‐floating sections (mean ± standard deviation: free‐floating: 5.6 ± 3.4 fibres/mm; automated: 5.9 ± 3.2 fibres/mm). A median difference of 0.3 with a lower bound 95% Confidence Interval (CI) at −0.00005 established non‐inferiority against a margin of −0.4 (p =.08). Specifically, the inter‐class correlation coefficient (class denotes consistency in measured observations) was 99% (95% CI: 0.9–1), indicating excellent agreement between free‐floating and automated methods. The inter‐ and intra‐class coefficient between examiners were both 99% (95% CI: 0.9–0.1) for IENFD, demonstrating high reliability using sections stained using the automated method. Interpretation: Automated immunohistochemistry provides high‐throughput reliable and reproducible intra‐epidermal nerve fibre quantification. This method, although currently proof‐of‐concept, for research use only, may be more widely deployed in histopathology laboratories to increase the adoption of IENFD assessment for the diagnosis of peripheral neuropathies. [ABSTRACT FROM AUTHOR]

Melanocortin 4 receptor (MC4R) mutations are the commonest cause of monogenic obesity through dysregulation of neuronal pathways in the hypothalamus and prefrontal cortex that regulate hunger and satiety. MC4R also regulates neuropathic pain pathways via JNK signaling after nerve injury. We show evidence of corneal small fiber degeneration in 2 siblings carrying a heterozygous missense variant c.508A>G, p.Ille170Val in the MC4R gene. Both children were treated with once weekly semaglutide for 6 months with no change in weight, and only a minor improvement in HbA1c and lipid profile. However, there was evidence of nerve regeneration with an increase in corneal nerve fiber density (CNFD) [child A (13.9%), child B (14.7%)], corneal nerve branch density (CNBD) [child A (110.2%), child B (58.7%)] and corneal nerve fiber length (CNFL) [child A (21.5%), child B (44.0%)]. [ABSTRACT FROM AUTHOR]

Aim: To assess the impact of insulin glargine (100 U/mL) and lixisenatide (iGlarLixi) fixed‐ratio combination therapy on the overall management of glycaemia in patients with type 2 diabetes (T2D), previously inadequately controlled with oral antidiabetic drugs ± basal insulin or glucagon‐like peptide‐1 receptor agonists (GLP‐1 RAs). Materials and Methods: This 12‐month, international, multicentre, prospective, observational study included patients (age ≥ 18 years) with T2D who had initiated iGlarLixi within 1 month prior to study inclusion. Data were collected at study inclusion, month 3, month 6 and month 12 from patient diaries, self‐measured plasma glucose, and questionnaires. The primary endpoint was change in HbA1c from baseline to month 6. Results: Of the 737 eligible participants (mean age: 57.8 [standard deviation: 11.2] years; male: 49%), 685 had baseline and post‐baseline HbA1c data available. The least squares mean change in HbA1c from baseline to month 6 was −1.4% (standard error [95% confidence interval (CI)]: 0.05 [−1.5, −1.3]). The absolute change from baseline at month 12 was −1.7% ± 1.9% (95% CI: −1.9, −1.5). There were 72 hypoglycaemia events reported during the study period, with a very low incidence of severe hypoglycaemia (two participants [rate: 0.003 events per patient‐year]). Conclusions: This real‐world observational study shows that initiation of iGlarLixi in people with T2D inadequately controlled on oral antidiabetic drugs ± basal insulin or GLP‐1 RAs improves glycaemic control with a low incidence of hypoglycaemia. [ABSTRACT FROM AUTHOR]

Corneal confocal microscopy (CCM) is an ophthalmic imaging technique that enables the identification of corneal nerve fibre degeneration and regeneration. To undertake a systematic review and meta‐analysis of studies utilizing CCM to assess for corneal nerve regeneration after pharmacological and surgical interventions in patients with peripheral neuropathy. Databases (EMBASE [Ovid], PubMed, CENTRAL and Web of Science) were searched to summarize the evidence from randomized and non‐randomized studies using CCM to detect corneal nerve regeneration after pharmacological and surgical interventions. Data synthesis was undertaken using RevMan web. Eighteen studies including 958 patients were included. CCM identified an early (1–8 months) and longer term (1–5 years) increase in corneal nerve measures in patients with peripheral neuropathy after pharmacological and surgical interventions. This meta‐analysis confirms the utility of CCM to identify nerve regeneration following pharmacological and surgical interventions. It could be utilized to show a benefit in clinical trials of disease modifying therapies for peripheral neuropathy. [ABSTRACT FROM AUTHOR]