Potential nephrotoxic effects of exposure to silver

Effect of Different Garlic Preparations on Testosterone, Thyroid Hormones, and Some Serum Trace Elements in Rats

Garlic is a house-available vegetable which is widely used for its spicy and medicinal benefits. Impact of different preparations on testosterone, thyroid hormones, and blood micro and trace elements were studied. Eight groups of male albino rats were selected including control group and other seven groups administered different doses of different garlic preparations by oral gavages for 1 month. At the end of the experiment, blood samples were collected for determination of serum hormones by radioimmunoassay, serum micro and trace elements by inductively coupled plasma-optical emission spectrometry (ICP-OES), and testes tissues for histological examination. All treated groups with different garlic preparations revealed a highly significant decrease of testosterone level in rats as compared to control which confirmed with histological changes. Increase of thyroid hormones in some groups was seen. Hypokalemia and hypernatremia effect was recorded due to garlic treatments. Calcium, magnesium, selenium, zinc, manganese, iron, cadmium, lead, silicon, molybdenum, germanium, barium, boron, niobium, and aluminum levels showed alterations in different preparations groups. On the other hand, insignificant changes of strontium, chromium, cesium, and the nickel serum levels were noted. Interestingly, although all garlic preparations have negative effects on serum testosterone level and testicular tissues, some garlic preparations have different effects on blood elements. Consequently, it infers that the usage of different garlic preparations must abide benefit/risk assessment to avoid unexpected health issues.

Microbial Community Composition Correlates with Metal Sorption in an Ombrotrophic Boreal Bog: Implications for Radionuclide Retention

Microbial communities throughout the 6.5 m depth profile of a boreal ombrotrophic bog were characterized using amplicon sequencing of archaeal, fungal, and bacterial marker genes. Microbial populations and their relationship to oxic and anoxic batch sorption of radionuclides (using radioactive tracers of I, Se, Cs, Ni, and Ag) and the prevailing metal concentrations in the natural bog was investigated. The majority of the detected archaea belonged to the Crenarchaeota, Halobacterota, and Thermoplasmatota, whereas the fungal communities consisted of Ascomycota, Basidiomycota, and unclassified fungi. The bacterial communities consisted mostly of Acidobacteriota, Proteobacteria, and Chloroflexi. The occurrence of several microbial genera were found to statistically significantly correlate with metal concentrations as well as with Se, Cs, I, and Ag batch sorption data. We suggest that the metal concentrations of peat, gyttja, and clay layers affect the composition of the microbial populations in these nutrient-low conditions and that particularly parts of the bacterial and archaeal communities tolerate high concentrations of potentially toxic metals and may concurrently contribute to the total retention of metals and radionuclides in this ombrotrophic environment. In addition, the varying metal concentrations together with chemical, mineralogical, and physical factors may contribute to the shape of the total archaeal and bacterial populations and most probably shifts the populations for more metal resistant genera.

Safety Assessment of Nanomaterials to Eyes: An Important but Neglected Issue

The production and application of nanomaterials have grown tremendously during last few decades. The widespread exposure of nanoparticles to the public is provoking great concerns regarding their toxicity to the human body. However, in comparison with the extensive studies carried out to examine nanoparticle toxicity to the human body/organs, one especially vulnerable organ, the eye, is always neglected. Although it is a small part of the body, 90% of outside information is obtained via the ocular system. In addition, eyes usually directly interact with the surrounding environment, which may get severer damage from toxic nanoparticles compared to inner organs. Therefore, the study of assessing the potential nanoparticle toxicity to the eyes is of great importance. Here, the recent advance of some representative manufactured nanomaterials on ocular toxicity is summarized. First, a brief introduction of ocular anatomy and disorders related to particulate matter exposure is presented. Following, the factors that may influence toxicity of nanoparticles to the eye are emphasized. Next, the studies of representative manufactured nanoparticles on eye toxicity are summarized and classified. Finally, the limitations that are associated with current nanoparticle-eye toxicity research are proposed.

Silver Nanomaterials in Contemporary Molecular Physiology Research

Silver nanoparticles have numerous potential applications in engineering, industry, biology and medicine. Because of their unique chemical properties, they have become the focus of many research teams all over the world. Silver nanoparticles may exhibit significant antimicrobial and anticancer effects, and they may be a valuable part of various bioassays and biosensors. However, the research on biological and medical uses of AgNPs is related with numerous potential problems and challenges that need to be overcome in the years ahead. Possible toxic effects of silver nanoparticles on living organisms represent a great concern, both in clinical medicine and public health. Nevertheless, in the future, it may be expected that all metallic nanomaterials, including the ones made from silver will greatly benefit almost all natural scientific fields. In this short review, we focus on the recent research on silver nanoparticles in experimental physiology, as well as other areas of fundamental and clinical medicine.

Widespread and Indiscriminate Nanosilver Use: Genuine Potential for Microbial Resistance

In this era of increasing antibiotic resistance, the use of alternative antimicrobials such as silver has become more widespread. Superior antimicrobial activity has been provided through fabrication of silver nanoparticles or nanosilver (NAg), which imparts cytotoxic actions distinct from those of bulk silver. In the wake of the recent discoveries of bacterial resistance to NAg and its rising incorporation in medical and consumer goods such as wound dressings and dietary supplements, we argue that there is an urgent need to monitor the prevalence and spread of NAg microbial resistance. In this Perspective, we describe how the use of NAg in commercially available products facilitates prolonged microorganism exposure to bioavailable silver, which underpins the development of resistance. Furthermore, we advocate for a judicial approach toward NAg use in order to preserve its efficacy and to avoid environmental disruption.

About the Influence of Silver Nanoparticles on Living Organisms Physiology

The production and properties of silver-containing products currently attract increasing attention due to the unique properties of silver. Specific properties of silver are considerably amplified when it is dispersed to the form of nanosized particles. Silver nanoparticles are several times more active than its other forms and many antibiotic and biocidal products. At the same time nanoparticles can more easily penetrate the protective barriers of living organisms and get directly into their tissues and organs. To be assured of safety of silver nanoproducts for human health and environment, it is necessary to study the influence of silver nanoparticles on the physiology of living organisms. This paper presents experimental data on effect of two nanosilver preparations (poviargol and argovit) on laboratory mice. Investigated preparations were characterized by transmission electron microscopy. It was established that morphological express control of peripheral blood and biochemical analysis of blood serum of living organisms can serve for purposes of primary monitoring of the pathological conditions caused by silver nanoparticles.

Pauci Immune crescentic glomerulonephritis in a patient with T-cell lymphoma and argyria

BACKGROUND

Silver is a transition metal, toxic when ingested in significant amounts, causing argyria (skin deposition) and argyrosis (eye deposition). It is excreted mainly via the gastrointestinal tract with only small amounts eliminated by the kidneys, and rarely have cases of nephrotoxicity due to silver been reported. Here we present the case of a woman who used colloidal silver as an alternative remedy for a T cell lymphoma, who subsequently developed argyria and a pauci-immune crescentic glomerulonephritis with evidence of extensive glomerular basement membrane silver deposition.

CASE PRESENTATION

A 47 year old woman of Indo-Asian descent with a T-cell lymphoma who refused conventional chemotherapy for 18 months but self-medicated with a remedy containing colloidal silver, was admitted with acute dialysis-dependent kidney injury. A kidney biopsy demonstrated a pauci-immune crescentic glomerulonephritis with deposition of silver particles in the mesangium and along the glomerular basement membranes. The patient was treated with intravenous methylprednisolone and intravenous cyclophosphamide and recovered independent renal function.

CONCLUSION

Chronological evolution of the the pauci-immune glomerulonephritis suggests that a cellular immune-mediated process was induced, potentially mediated by lymphomatous T cells directed at the glomerular basement membrane, following silver deposition. Immunosuppressive therapy improved the situation and allowed cessation of haemodialysis, supporting the hypothesis of an immune-mediated process.

Intrinsic therapeutic applications of noble metal nanoparticles: past, present and future

Biomedical nanotechnology is an evolving field having enormous potential to positively impact the health care system. Important biomedical applications of nanotechnology that may have potential clinical applications include targeted drug delivery, detection/diagnosis and imaging. Basic understanding of how nanomaterials, the building blocks of nanotechnology, interact with the cells and their biological consequences are beginning to evolve. Noble metal nanoparticles such as gold, silver and platinum are particularly interesting due to their size and shape dependent unique optoelectronic properties. These noble metal nanoparticles, particularly of gold, have elicited a lot of interest for important biomedical applications because of their ease of synthesis, characterization and surface functionalization. Furthermore, recent investigations are demonstrating another promising application of these nanomaterials as self-therapeutics. To realize the potential promise of these unique inorganic nanomaterials for future clinical translation, it is of utmost importance to understand a few critical parameters; (i) how these nanomaterials interact with the cells at the molecular level; (ii) how their biodistribution and pharmacokinetics influenced by their surface and routes of administration; (iii) mechanism of their detoxification and clearance and (iv) their therapeutic efficacy in appropriate disease model. Thus in this critical review, we will discuss the various clinical applications of gold, silver and platinum nanoparticles with relevance to above parameters. We will also mention various routes of synthesis of these noble metal nanoparticles. However, before we discuss present research, we will also look into the past. We need to understand the discoveries made before us in order to further our knowledge and technological development (318 references).

Acute pulmonary toxicity and body distribution of inhaled metallic silver nanoparticles

The purpose of this study was to determine the acute pulmonary toxicity of metallic silver nanoparticles (MSNPs, 20.30 nm in diameter). Acute pulmonary toxicity and body distribution of inhaled MSNPs in mice were evaluated using a nose-only exposure chamber (NOEC) system. Bronchoalveolar lavage (BAL) fluid analysis, Western blotting, histopathological changes, and silver burdens in various organs were determined in mice. Mice were exposed to MSNPs for 6 hrs. The mean concentration, total surface area, volume and mass concentrations in the NOEC were maintained at 1.93 × 10(7) particles/cm(3), 1.09 × 10(10) nm(2)/cm(3), 2.72 × 10(11) nm(3)/cm(3), and 2854.62 μg/m(3), respectively. Inhalation of MSPNs caused mild pulmonary toxicity with distribution of silver in various organs but the silver burdens decreased rapidly at 24-hrs post-exposure in the lung. Furthermore, inhaled MSNPs induced activation of mitogen-activated protein kinase (MAPK) signaling in the lung. In summary, single inhaled MSNPs caused mild pulmonary toxicity, which was associated with activated MAPK signaling. Taken together, our results suggest that the inhalation toxicity of MSNPs should be carefully considered at the molecular level.

Acute and subchronic dermal toxicity of nanosilver in guinea pig

Silver has been used as an antimicrobial agent for a long time in different forms, but silver nanoparticles (nanosilver) have recently been recognized as potent antimicrobial agents. Although nanosilver is finding diverse medical applications such as silver-based dressings and silver-coated medical devices, its dermal and systemic toxicity via dermal use has not yet been identified. In this study, we analyzed the potential toxicity of colloidal nanosilver in acute and subchronic guinea pigs. Before toxicity assessments, the size of colloidal nanosilver was recorded in sizes <100 nm by X-ray diffraction and transmission electron microscopy. For toxicological assessments, male guinea pigs weighing 350 to 400 g were exposed to two different concentrations of nanosilver (1000 and 10,000 μg/mL) in an acute study and three concentrations of nanosilver (100, 1000, and 10,000 μg/mL) in a subchronic study. Toxic responses were assessed by clinical and histopathologic parameters. In all experimental animals the sites of exposure were scored for any type of dermal toxicity and compared with negative control and positive control groups. In autopsy studies during the acute test, no significant changes in organ weight or major macroscopic changes were detected, but dose-dependent histopathologic abnormalities were seen in skin, liver, and spleen of all test groups. In addition, experimental animals subjected to subchronic tests showed greater tissue abnormalities than the subjects of acute tests. It seems that colloidal nanosilver has the potential to provide target organ toxicities in a dose- and time-dependent manner.

A pharmacological and toxicological profile of silver as an antimicrobial agent in medical devices

Silver is used widely in wound dressings and medical devices as a broad-spectrum antibiotic. Metallic silver and most inorganic silver compounds ionise in moisture, body fluids, and secretions to release biologically active Ag(+). The ion is absorbed into the systemic circulation from the diet and drinking water, by inhalation and through intraparenteral administration. Percutaneous absorption of Ag(+) through intact or damaged skin is low. Ag(+) binds strongly to metallothionein, albumins, and macroglobulins and is metabolised to all tissues other than the brain and the central nervous system. Silver sulphide or silver selenide precipitates, bound lysosomally in soft tissues, are inert and not associated with an irreversible toxic change. Argyria and argyrosis are the principle effects associated with heavy deposition of insoluble silver precipitates in the dermis and cornea/conjunctiva. Whilst these changes may be profoundly disfiguring and persistent, they are not associated with pathological damage in any tissue. The present paper discusses the mechanisms of absorption and metabolism of silver in the human body, presumed mechanisms of argyria and argyrosis, and the elimination of silver-protein complexes in the bile and urine. Minimum blood silver levels consistent with early signs of argyria or argyrosis are not known. Silver allergy does occur but the extent of the problem is not known. Reference values for silver exposure are discussed.

Impact of silver(I) on the metabolism of Shewanella oneidensis

Anaerobic cultures of Shewanella oneidensis MR-1 reduced toxic Ag(I), forming nanoparticles of elemental Ag(0), as confirmed by X-ray diffraction analyses. The addition of 1 to 50 microM Ag(I) had a limited impact on growth, while 100 microM Ag(I) reduced both the doubling time and cell yields. At this higher Ag(I) concentration transmission electron microscopy showed the accumulation of elemental silver particles within the cell, while at lower concentrations the metal was exclusively reduced and precipitated outside the cell wall. Whole organism metabolite fingerprinting, using the method of Fourier transform infrared spectroscopy analysis of cells grown in a range of silver concentrations, confirmed that there were significant physiological changes at 100 microM silver. Principal component-discriminant function analysis scores and loading plots highlighted changes in certain functional groups, notably, lipids, amides I and II, and nucleic acids, as being discriminatory. Molecular analyses confirmed a dramatic drop in cellular yields of both the phospholipid fatty acids and their precursor molecules at high concentrations of silver, suggesting that the structural integrity of the cellular membrane was compromised at high silver concentrations, which was a result of intracellular accumulation of the toxic metal.

Formation of nanoscale elemental silver particles via enzymatic reduction by Geobacter sulfurreducens

Geobacter sulfurreducens reduced Ag(I) (as insoluble AgCl or Ag(+) ions), via a mechanism involving c-type cytochromes, precipitating extracellular nanoscale Ag(0). These results extend the range of metals known to be reduced by Geobacter species and offer a method for recovering silver from contaminated water as potentially useful silver nanoparticles.