Arsenic poisoning and Mees' lines

Toxic Neuropathies

OBJECTIVE

The purpose of this article is to provide an overview and update on the most clinically relevant toxic neuropathies.

LATEST DEVELOPMENTS

Broadly, toxic neuropathies were previously quite rare with the notable exception of neuropathy from alcohol or older chemotherapeutics. The development of newer therapies, particularly immunotherapy to treat malignancy, has resulted in a substantial increase in the occurrence of toxic neuropathies that require timely recognition and treatment. The understanding of other toxic neuropathies continues to evolve, such as statin-induced neuropathy, which new evidence suggests is much less common than previously suspected.

ESSENTIAL POINTS

Toxic neuropathies can be caused by medications, supplements, and recreational substances that injure peripheral nerves. Medications have evolved in the past 2 decades, as have the types of neuropathies that can be seen as related toxicities. In some areas of medicine, new classes and generations of drugs are associated with a lower incidence of toxic neuropathy.

Leukonychia: What Can White Nails Tell Us?

Changes in nail color can provide important clues of underlying systemic and skin disease. In particular, white discoloration (leukonychia) has a high prevalence with a wide array of potential relevant causes, from simple manicure habits to life-threatening liver or kidney failure. Therefore, a reliable assessment of the patient with leukonychia is essential. In the past, two classifications for leukonychia have been presented. The morphological classifies the nail according to the distribution of the white lines: total, partial, transversal, and longitudinal leukonychia. Mees’ and Muehrcke’s lines are examples of transversal leukonychia, while Terry’s and Lindsay’s nails are examples of total and partial leukonychia. The anatomical classifies according to the structure responsible for the white color: the nail plate in true leukonychia, the nail bed in apparent leukonychia, and the surface only in pseudoleukonychia. In this review, both morphological and anatomical features have been combined in an algorithm that enables clinicians to approach leukonychia efficiently and effectively.

Nail Manifestations in COVID-19: Insight into a Systemic Viral Disease

Nail manifestations are 1 of the several extrapulmonary findings associated with COVID-19 caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Nail changes, however, have been largely ignored and not yet summarized. This article is intended to increase awareness of nail manifestations of SARS-CoV-2, which occur weeks to months after acute infection and the periungual pernio-like changes may occur concomitantly with infection. An electronic search was carried out in PubMed (Medline), Science Direct, and Scopus databases. The following keywords and all of their possible combinations were used to identify studies: “SARS-CoV-2,” “COVID-19,” “Coronavirus,” “2019-ncov,” “nail,” and “nails.” Six case reports were included in this study. Manifestations identified included red half-moon sign, transverse orange nail lesions, Mees' lines, and Beau's lines. Though largely nonspecific, these findings can be recognized with the onset of symptom onset or as late as 16 weeks following the disease. Some of these findings are shared with other conditions associated with a proinflammatory state. Nail changes offer unique insight into the pathophysiologic basis for SARS-CoV-2 and they may serve as diagnostic clues.

Heavy Metals in Indian Traditional Systems of Medicine: A Systematic Scoping Review and Recommendations for Integrative Medicine Practice

Introduction: Ayurveda and Siddha are two important components of the traditional Indian medicine (TIM). The regulatory mechanisms have been insufficient, and heavy metal toxicity with TIM preparations continues to be a public health nuisance, putting integrated medicine practice in jeopardy. The current study was undertaken to review the potential health hazards of the heavy metal content in the TIM and formulate patient-safety recommendations for integrative medical practice. Materials and Methods: Systematic MEDLINE searches were performed using a combination of relevant MeSH terms and keywords, and case report/series of Ayurveda or Siddha-induced heavy metal toxicity, published in the previous two decades, were included. Risk of bias was assessed with the tool by Murad et al. Results: A total of 220 cases (51 case reports and 14 case series) were found (lead, n = 156; arsenic, n = 11; mercury, n = 47; thallium, n = 1; gold, n = 1; combination of heavy metals, n = 4) after screening for the inclusion and exclusion criteria. Among them, 169 (76.8%) had a low risk of bias, 113 (out of 135 [83.7%] analyzed) contained higher-than-permissible heavy metal content in the drug samples, and the majority showed elevated biological levels of the heavy metals in the body. Conclusion: The heavy metals in TIM are often the result of adulteration or improper manufacturing and prescribing practices, despite national and international guidelines recommending quality standards and protocols for preparing and dispensing TIM. We thus propose multipronged approaches and provide recommendations at various levels, including individual, institutional, national policy decisions essential to establish patient safety of TIM.

Gas chromatography-mass spectrometry based metabolomics profile of hippocampus and cerebellum in mice after chronic arsenic exposure

Intake of arsenic (As) via drinking water has been a serious threat to global public health. Though there are numerous reports of As neurotoxicity, its pathogenesis mechanisms remain vague especially its chronic effects on metabolic network. Hippocampus is a renowned area in relation to learning and memory, whilst recently, cerebellum is argued to be involved with process of cognition. Therefore, the study aimed to explore metabolomics alternations in these two areas after chronic As exposure, with the purpose of further illustrating details of As neurotoxicity. Twelve 3-week-old male C57BL/6J mice were divided into two groups, receiving deionized drinking water (control group) or 50 mg/L of sodium arsenite (via drinking water) for 24 weeks. Learning and memory abilities were tested by Morris water maze (MWM) test. Pathological and morphological changes of hippocampus and cerebellum were captured via transmission electron microscopy (TEM). Metabolic alterations were analyzed by gas chromatography-mass spectrometry (GC-MS). MWM test confirmed impairments of learning and memory abilities of mice after chronic As exposure. Metabolomics identifications indicated that tyrosine increased and aspartic acid (Asp) decreased simultaneously in both hippocampus and cerebellum. Intermediates (succinic acid) and indirect involved components of tricarboxylic acid cycle (proline, cysteine, and alanine) were found declined in cerebellum, indicating disordered energy metabolism. Our findings suggest that these metabolite alterations are related to As-induced disorders of amino acids and energy metabolism, which might therefore, play an important part in mechanisms of As neurotoxicity.