Tryptophan metabolism and small fibre neuropathy: a correlation study.

Small nerve fibres located in the epidermis sense pain. Dysfunction of these fibres decreases the pain threshold known as small fibre neuropathy. Diabetes mellitus is accompanied by metabolic changes other than glucose, synergistically eliciting small fibre neuropathy. These findings suggest that various metabolic changes may be involved in small fibre neuropathy. Herein, we explored the correlation between pain sensation and changes in plasma metabolites in healthy Japanese subjects. The pain threshold evaluated from the intraepidermal electrical stimulation was used to quantify pain sensation in a total of 1021 individuals in the 2017 Iwaki Health Promotion Project. Participants with a pain threshold evaluated from the intraepidermal electrical stimulation index <0.20 mA were categorized into the pain threshold evaluated from the intraepidermal electrical stimulation index-low group (n = 751); otherwise, they were categorized into the pain threshold evaluated from the intraepidermal electrical stimulation index-high group (n = 270). Metabolome analysis of plasma was conducted using capillary electrophoresis time-of-flight mass spectrometry. The metabolite set enrichment analysis revealed that the metabolism of tryptophan was significantly correlated with the pain threshold evaluated from the intraepidermal electrical stimulation index in all participants (P < 0.05). The normalized level of tryptophan was significantly decreased in participants with a high pain threshold evaluated from the intraepidermal electrical stimulation index. In addition to univariate linear regression analyses, the correlation between tryptophan concentration and the pain threshold evaluated from the intraepidermal electrical stimulation index remained significant after adjustment for multiple factors (ß = -0.07615, P < 0.05). These findings indicate that specific metabolic changes are involved in the deterioration of pain thresholds. Here, we show that abnormal tryptophan metabolism is significantly correlated with an elevated pain threshold evaluated from the intraepidermal electrical stimulation index in the Japanese population. This correlation provides insight into the pathology and clinical application of small fibre neuropathy.

Diabetes can increase the prevalence of EBV infection and worsen the prognosis of nasopharyngeal carcinoma.

Epstein‒Barr virus (EBV) infection is a primary oncogenic factor of nasopharyngeal carcinoma (NPC) that elicits epithelial-mesenchymal transition (EMT). Although diabetic patients are more susceptible to various infectious diseases, the pathological association with virus-related NPC has not yet been clarified. Herein, we evaluated the influence of diabetes on the clinicopathological changes of 70 patients with NPC. Disease-specific survival (DSS) modified by viral infection was also analysed. The proportion of NPC patients with diabetes was 32.9% (23/70 cases), and 91.3% (21/23 cases) were infected with EBV detected by EBER-I in situ hybridisation. NPC with diabetes showed an effect on EMT evaluated by immunostaining for E-cadherin and vimentin, which was correlated with HbA1c levels. Receiver operating characteristic (ROC) curve analysis determined a HbA1c level of 6.5% as the cut-off value for primary disease death at 2 years [area under the curve (AUC) 0.76; sensitivity 0.64; and specificity 0.81]. High HbA1c levels (≥6.5%) significantly increased the number of lymph node metastases in NPC compared to low HbA1c levels (<6.5%, p<0.01). Diabetic NPC patients had a significantly poorer prognosis than all non-diabetic patients (DSS, 72 months vs not reached, p<0.05). Diabetic EBV-positive NPC patients had a significantly poorer prognosis than non-diabetic EBV-positive patients (DSS, 35 months vs not reached, p<0.01). Multivariate analysis using the Cox proportional hazards model also suggested that HbA1c ≥6.5% was a significant factor in poor prognosis, with a hazard ratio of 6.84 (p<0.05). Collectively, our results revealed for the first time a high prevalence of EBV infection, poor prognosis and the importance of proper glycaemic control in diabetic NPC patients.

[Binocular diplopia and ptosis due to snakebite (Agkistrodon blomhoffi "mamushi")--a case report].

We treated a patient who developed binocular diplopia and ptosis after being bitten by an Agkistrodon blomhoffi (mamushi). The patient was a 49-year-old man who presented with binocular diplopia after the snakebite on the second finger of his right hand. He experienced local pain and swelling and a few hours later, he developed diplopia. In the primary position he had no tropia. On the basis the ocular angle of deviation measured by a Hess chart test, he was diagnosed with paresis of the medial rectus muscle paresis. Binocular diplopia persisted for 2 weeks. The venom of A. blomhoffi venom mainly consists of hemolytic toxins, but it also contains 2 types of neurotoxins--an alpha-toxin and a beta-toxin. Neurotoxins affects the neuromuscular junction (NMJ). The alpha-toxin acts postsynaptic inhibition as a competitive inhibitor of acetylcholine and causes postsynaptic inhibition; these effects are similar to those of the anti-acetylcholine receptor antibody identified in patients with myasthenia gravis. The beta-toxin inhibits acetylcholine release by disrupting the presynaptic membrane, and thus, its effects cannot be blocked by the anticholinesterase edrophonium chloride. Although both antiserum and cepharanthine are widely used for the treatment of snakebites, there is no evidence of a specific effective therapy for the eye manifestation after snakebite. However, it these manifestation improves in about 2 weeks without any specific treatment. Our case suggested that the occurrence of subjective binocular diplopia without objective tropia could be caused by snakebite.