Clinical and Forensic Aspects of the Different Subtypes of Argyria

NHCs silver complexes as potential antimicrobial agents

NHCs (N-heterocyclic carbenes) are generally used as organic ligands that can coordinate with metal ions like silver to form stable complexes. These complexes have shown enhanced antimicrobial properties compared to silver alone. This document provides an overview of the reported NHC-based silver derivatives (acetates, chlorides, bromides, and iodides) who possess antimicrobial activity. This review covers articles published between the first report (2006) and 2023.

Localized Cutaneous Argyria at the Site of a Prior Melanoma Excision Confirmed by Scanning Electron Microscopy With Energy Dispersive X-ray Analysis

ABSTRACT

Localized cutaneous argyria is a rare condition caused by the accumulation of silver particles in the skin, leading to blue-gray discoloration. Argyria may mimic melanoma and lead to misdiagnosis. We present a patient with a history of melanoma that developed a blue-gray nodule at a prior melanoma graft. The diagnosis was confirmed using scanning electron microscopy and energy dispersive x-ray analysis. These techniques differentiate argyria from melanoma and can be performed on formalin-fixed, paraffin-embedded, tissue sections. Health care providers should be alert that argyria may mimic recurrent melanoma in patients unaware of silver exposure.

Comparative in vivo toxicokinetics of silver powder, nanosilver and soluble silver compounds after oral administration to rats

Silver (Ag; massive, powder and nanoform) and Ag compounds are used in industrial, medical and consumer applications, with potential for human exposure. Uncertainties exist about their comparative mammalian toxicokinetic ('TK') profiles, including their relative oral route bioavailability, especially for Ag massive and powder forms. This knowledge gap impedes concluding on the grouping of Ag and Ag compounds for hazard assessment purposes. Therefore, an in vivo TK study was performed in a rat model. Sprague-Dawley rats were exposed via oral gavage for up to 28 days to silver acetate (AgAc; 5, 55, 175 mg/kg(bw)/d), silver nitrate (AgNO3; 5, 55, 125 mg/kg(bw)/d), nanosilver (AgNP; 15 nm diameter; 3.6, 36, 360 mg/kg(bw)/d) or silver powder (AgMP; 0.35 µm diameter; 36, 180, 1000 mg/kg(bw)/d). Total Ag concentrations were determined in blood and tissues to provide data on comparative systemic exposure to Ag and differentials in achieved tissue Ag levels. AgAc and AgNO3 were the most bioavailable forms with comparable and linear TK profiles (achieved systemic exposures and tissue concentrations). AgMP administration led to systemic exposures of about an order of magnitude less, with tissue Ag concentrations 2-3 orders of magnitude lower and demonstrating non-linear kinetics. The apparent oral bioavailability of AgNP was intermediate between AgAc/AgNO3 and AgMP. For all test items, highest tissue Ag concentrations were in the gastrointestinal tract and reticuloendothelial organs, whereas brain and testis were minor sites of distribution. It was concluded that the oral bioavailability of AgMP was very limited. These findings provide hazard assessment context for various Ag test items and support the prediction that Ag in massive and powder forms exhibit low toxicity potential.

Ocular argyrosis

The absorption of silver presents as a grayish coloration in different locations as the skin and eye. Corneal argyrosis is characterized by micro-deposits in the stroma, Bowman or Descemt membranes. This metal could also affect other structures as the retina. We describe the case of a male jeweler with corneal argyrosis. Small whitish-grayish predescemetic depositis were observed by biomicroscopy, which were described as punctate and extra-cellular by in vivo confocal microscopy. Our patient presented a significative impairment of contrast sensitivity under scotopic conditions which could not be attributed to other condition. This test could be helpful in detecting retinal functional alteration before the structural anatomical alteration are visible.

One image is worth more than a thousand words: producing an atlas of medical signs for teaching clinical and forensic toxicology

Clinical and forensic toxicology are critically involved in the acquisition of basic skills to correctly suspect intoxication, collect biological and non-biological materials for toxicological analysis, comprehend the complexities inherent to laboratory activity, and understand the fundamentals of toxicokinetics and toxicodynamics that underlie the interpretation of results. This works presents a pedagogical innovation proposal for the teaching of clinical and forensic toxicology based on a compilation of more than 3 000 cases where the image was fulcra for suspicion. The experience in this article follows the model practiced in bachelors, masters, and PhD degrees, as well as in other continuing training courses, where we are teaching toxicology for more than 15 years. All these levels of education are considered fundamental to the sound development of this science. This approach aims also to offer strength to the intervention of the true toxicologist in all the toxicological phases, besides the classic analytical chemistry. Indeed, it is impossible to provide effective clinical and forensic toxicological interpretations without a proper and broad education, and not thinking exclusively in terms of laboratory techniques. In the future, it will be interesting to evaluate knowledge retention and to propose a database of videos of signs related to intoxications.

A Case Study of Argyria of the Nails Secondary to Colloidal Silver Ingestion

This case report documents the rare finding of argyria limited to the nails secondary to colloidal silver ingestion. We highlight the significance of early detection of argyria secondary to colloidal silver ingestion and offer photos of the subtle changes in the nails that indicate the development of argyria. With the popularity of over-the-counter supplementation, it is important for medical providers to be aware of early signs of argyria, prior to progressive, permanent pigmentary changes.

Hypothetical Mechanism of Skin Argyria

Introduction. Argyria is an acquired skin condition that appears after the exposure or consumption of silver, leading to blue or grey coloration of the skin and mucosa. The aim of the present work was to draw researchers’ attention to two aspects of the argyria that until now have not received enough consideration. They are: (1) the process of delivering silver compound from the gastrointestinal tract to the skin and (2) the possibility for silver chloride to participate in this process along with the silver proteinates. Methodology. Illustrative experiments included the observation of color change (visual and using UV-Vis spectrometry) under different light exposure conditions of silver chloride sol in a sweat-simulating solution, in vials and under pig skin (in direct contact). Results and Discussion. A hypothetical mechanism based on a perspiration system for delivering the silver compounds from the gastrointestinal tract to the skin for argyria was proposed. It was also proposed not to completely exclude the partial participation of silver chloride along with the silver proteinates in this process.