Myoclonic status epilepticus following repeated oral ingestion of colloidal silver

Seizures Following Self-Medication With Colloidal Silver: A Case Report

Silver-containing products have been used for medicinal purposes since antiquity. Throughout the ages and indeed up until the present time, silver has been employed with the hopes of treating a myriad of diseases including the common cold, skin problems, infections, and even cancer. However, silver has no known biological role in human physiology, and taking silver may lead to adverse reactions. The better-known adverse reactions of silver include argyria, or a gray-blue cutaneous discoloration, which is a known effect of silver accumulation. Additionally renal or hepatic injury may also be experienced. Reports of neurological adverse reactions are rare, however, and the extant medical literature contains very few descriptions of such cases. We report herein a case of a 70 year old man who presented with seizures as the sole manifestation of silver toxicity after self-medicating with colloidal silver.

Metal-Based Nanoparticles and Their Relevant Consequences on Cytotoxicity Cascade and Induced Oxidative Stress

Emerging nanoscience allows us to take advantage of the improved evolutionary components and apply today’s advanced characterization and fabrication techniques to solve environmental and biological problems. Despite the promise that nanotechnology will improve our lives, the potential risks of technology remain largely uncertain. The lack of information on bio-impacts and the absence of consistent standards are the limitations of using metal-based nanoparticles (mNPs) for existing applications. To analyze the role played by the mNPs physicochemical characteristics and tactics to protect live beings, the field of nanotoxicology nowadays is focused on collecting and analyzing data from in vitro and in vivo investigations. The degree of reactive oxygen species (ROS) and oxidative stress caused by material nanoparticles (NPs) depends on many factors, such as size, shape, chemical composition, etc. These characteristics enable NPs to enter cells and interact with biological macromolecules and cell organelles, resulting in oxidative damage, an inflammatory response, the development of mitochondrial dysfunction, damage to genetic material, or cytotoxic effects. This report explored the mechanisms and cellular signaling cascades of mNPs-induced oxidative stress and the relevant health consequences.

Chemical Synthesis of Innovative Silver Nanohybrids with Synergistically Improved Antimicrobial Properties

Background

The wide use of antibiotics has created challenges related to antibiotic-resistant bacteria, which have been increasingly found in recent decades. Antibiotic resistance has led to limited choices of antibiotics. Multiple old antimicrobial agents have high antimicrobial properties toward bacteria, but they unfortunately also possess high toxicity toward humans. For instance, silver (Ag) compounds were frequently used to treat tetanus and rheumatism in the 19th century and to treat colds and gonorrhea in the early 20th century. However, the high toxicity of Ag has limited its clinical use.

Purpose

We aimed to reformulate Ag to reduce its toxicity toward human cells like osteoblasts and to optimize its antimicrobial properties.

Results

Ag, an old antimicrobial agent, was reformulated by hybriding nanomaterials of different dimensions, and silver nanoparticles (AgNPs) of controllable sizes (95-200 nm) and varying shapes (cube, snowflake, and sphere) were synthesized on carbon nanotubes (CNTs). The obtained AgNP-CNT nanohybrids presented significantly higher killing efficacy against Staphylococcus aureus (S. aureus) compared to AgNPs at the same molar concentration and showed synergism in killing S. aureus at 0.2 and 0.4 mM. AgNPs presented significant osteoblast toxicity; in contrast, AgNP-CNT nanohybrids demonstrated significantly enhanced osteoblast viability at 0.04-0.8 mM. The killing of S. aureus by AgNP-CNT nanohybrids was fast, occurring within 15 min.

Conclusion

Ag was successfully reformulated and Ag nanohybrids with various AgNP shapes on CNTs were synthesized. The nanohybrids presented significantly enhanced antimicrobial properties and significantly higher osteoblast cell viability compared to AgNPs, showing promise as an innovative antimicrobial nanomaterial for a broad range of biomedical applications.

Exogenous pigmentation by silver nitrate: Dermatological and toxicological aspects, case report

La pigmentación exógena por nitrato de plata es una enfermedad poco frecuente, cuyas manifestaciones clínicas pueden aparecer años después del contacto, lo que en ocasiones dificulta su diagnóstico. Se caracteriza por la presencia de máculas o placas azul-grisáceas en la piel o las mucosas de la zona de contacto que, en ocasiones, son muy similares a las lesiones melanocíticas y al melanoma, sus principales diagnósticos diferenciales.

Se reporta el caso de un paciente de Medellín, Colombia, con antecedentes familiares de melanoma y presencia de estas lesiones en todo el cuerpo.

Clinical and Forensic Aspects of the Different Subtypes of Argyria

Argyria encompasses the different cosmetic alterations that can develop if enough silver particles deposit in a specific tissue, typically in the skin, ranging from localized dark-blue macules to a generalized slate-gray/bluish tinge following systemic absorption. This work aims to fully review the state of the art regarding pathophysiology, diagnosis, treatment, and relevant clinical and forensic features of argyria. Argyria has been diagnosed in a wide range of ages, both sexes and varied ethnicities, with no known individual predisposing factors. Ultraviolet radiation with subsequence increases of melanin production aggravates the discoloration due to a reduction in the silver deposits. Physical examination and silver exposure in the anamnesis can be highly suggestive of the diagnosis, but a histopathological analysis with Energy-Dispersive X-ray Spectroscopy is required to unequivocally determine the discoloration etiology. Safe and effective treatment has only been accomplished with laser techniques, though only a few cases have been reported and with limited follow-up time. In conclusion, argyria typically has an occupational or iatrogenic etiology. It should be suspected when a patient presents with typical skin or eye lesions. A seemingly viable treatment modality, with laser technology, is finally within the horizon.

Synthesis, Spectroscopy, Single-Crystal Structure Analysis and Antibacterial Activity of Two Novel Complexes of Silver(I) with Miconazole Drug

In a previous article, we reported on the higher toxicity of silver(I) complexes of miconazole [Ag(MCZ)₂NO₃ (1)] and [Ag(MCZ)₂ClO₄ (2)] in HepG2 tumor cells compared to the corresponding salts of silver, miconazole and cisplatin. Here, we present the synthesis of two silver(I) complexes of miconazole containing two new counter ions in the form of Ag(MCZ)₂X (MCZ = 1-[2-(2,4-dichlorobenzyloxy)-2-(2,4-dichlorophenyl)ethyl]-1H-imidazole]; X = BF₄⁻ (3), SbF₆⁻ (4)). The novel silver(I) complexes were characterized by elemental analysis, ¹H NMR, ¹³C NMR and infrared (IR) spectroscopy, electrospray ionization (ESI)-MS spectrometry and X-ray-crystallography. In the present study, the antimicrobial activity of all obtained silver(I) complexes of miconazole against six strains of Gram-positive bacteria, five strains of Gram-negative bacteria and yeasts was evaluated. The results were compared with those of a silver sulfadiazine drug, the corresponding silver salts and the free ligand. Silver(I) complexes exhibited significant activity against Gram-positive bacteria, which was much better than that of silver sulfadiazine and silver salts. The highest antimicrobial activity was observed for the complex containing the nitrate counter ion. All Ag(I) complexes of miconazole resulted in much better inhibition of yeast growth than silver sulfadiazine, silver salts and miconazole. Moreover, the synthesized silver(I) complexes showed good or moderate activity against Gram-negative bacteria compared to the free ligand.

Hazard characterization of silver nanoparticles for human exposure routes

Silver nanoparticles (AgNPs) have been widely used for a multitude of applications without full comprehensive knowledge regarding their safety. In particular, lack of data on hazard characterization may lead to uncertainties regarding potential human health risk. To provide the foundation for human health risk assessment of AgNPs, this study evaluates existing hazard characterization data, including reported pharmacokinetics, symptoms, and their corresponding dose-response relationships. Human equivalent relationships are also provided by extrapolation from animal dose-response relationships. From the data analyzed, it appears that AgNPs may persist for long periods (from days to years) in the human body. It was found that AgNP toxicity on traditional major targets of exogenous substances were generally underestimated. Some omissions of toxicity on sensitive systems in the AgNP toxicity assessment require attention, such as reprotoxicity and neurotoxicity. The necessity of the establishment of toxicity tests specifically for nanomaterials is highlighted. The scientific basis of a toxicity testing strategy is advised by this study, which paves the way for the monitoring and regulation of the ENP utilization in various industries.

Anemia and leukopenia following intravenous colloidal silver infusions-Clinical and hematological features, unique peripheral blood film appearance and effective therapy with supplemental oral copper and apheresis

Alternative medical therapy with multiple intravenous colloidal silver infusions may cause severe illness, including profound copper deficiency-induced anemia and hepatic toxicity. No chelating agent for silver poisoning exists and effective therapy requires apheresis in combination with continuous administration of oral copper.

Adverse effects of nanosilver on human health and the environment

Silver and silver nanoparticles (AgNPs) exhibit antimicrobial properties against some bacteria, fungi and viruses, however, the ever-increasing application of nanosilver in consumer products, water disinfection and healthcare settings, have raised concerns over the public health/environmental safety of this nanomaterial. The current ubiquity of nanosilver may result in repeated exposure through various routes (skin, inhalation, or ingestion) which may lead to health complications. While there are a number of review articles and case studies published to date on the subject, an updated coherent review that clearly delineates thresholds and safe doses is lacking. Thus, it is plausible to have an overview of the most recent findings on the threshold limits, safe doses of silver and its related nanoscale forms, and the needed actions to ensure the safety and health of human, terrestrial and aquatic lives. This review provides an account of the effects of nanosilver in our daily lives. STATEMENT OF SIGNIFICANCE: This manuscripts is a review of the toxicity of nanosized silver. With respect to the existing literature, it goes beyond stating that there is a knowledge gap, drawing the attention of a wider readership to the ever-growing evidence of nanosilver toxicity to human and nature, and outlining the dose thresholds based on comprehensive data mining and visualisation. There are nearly 500 consumer products that claim to contain nanosilver. Thus, we trust a review of recent conclusive findings is timely. This manuscript is in line with the scope of the Journal, enabling a better understanding of the biological response to a widely-used bionanomaterial. Moreover, it provides a bigger picture of the link between surface properties and biocompatibility of nanosilver in different forms.

Neurotheranostics as personalized medicines

The discipline of neurotheranostics was forged to improve diagnostic and therapeutic clinical outcomes for neurological disorders. Research was facilitated, in largest measure, by the creation of pharmacologically effective multimodal pharmaceutical formulations. Deployment of neurotheranostic agents could revolutionize staging and improve nervous system disease therapeutic outcomes. However, obstacles in formulation design, drug loading and payload delivery still remain. These will certainly be aided by multidisciplinary basic research and clinical teams with pharmacology, nanotechnology, neuroscience and pharmaceutic expertise. When successful the end results will provide "optimal" therapeutic delivery platforms. The current report reviews an extensive body of knowledge of the natural history, epidemiology, pathogenesis and therapeutics of neurologic disease with an eye on how, when and under what circumstances neurotheranostics will soon be used as personalized medicines for a broad range of neurodegenerative, neuroinflammatory and neuroinfectious diseases.

Evolving concepts in bone infection: redefining "biofilm", "acute vs. chronic osteomyelitis", "the immune proteome" and "local antibiotic therapy"

Osteomyelitis is a devastating disease caused by microbial infection of bone. While the frequency of infection following elective orthopedic surgery is low, rates of reinfection are disturbingly high. Staphylococcus aureus is responsible for the majority of chronic osteomyelitis cases and is often considered to be incurable due to bacterial persistence deep within bone. Unfortunately, there is no consensus on clinical classifications of osteomyelitis and the ensuing treatment algorithm. Given the high patient morbidity, mortality, and economic burden caused by osteomyelitis, it is important to elucidate mechanisms of bone infection to inform novel strategies for prevention and curative treatment. Recent discoveries in this field have identified three distinct reservoirs of bacterial biofilm including: Staphylococcal abscess communities in the local soft tissue and bone marrow, glycocalyx formation on implant hardware and necrotic tissue, and colonization of the osteocyte-lacuno canalicular network (OLCN) of cortical bone. In contrast, S. aureus intracellular persistence in bone cells has not been substantiated in vivo, which challenges this mode of chronic osteomyelitis. There have also been major advances in our understanding of the immune proteome against S. aureus, from clinical studies of serum antibodies and media enriched for newly synthesized antibodies (MENSA), which may provide new opportunities for osteomyelitis diagnosis, prognosis, and vaccine development. Finally, novel therapies such as antimicrobial implant coatings and antibiotic impregnated 3D-printed scaffolds represent promising strategies for preventing and managing this devastating disease. Here, we review these recent advances and highlight translational opportunities towards a cure.

Acute myeloid leukemia with complex cytogenetic abnormalities associated with long-term use of oral colloidal silver as nutritional supplement – Case report and review of literature

We report a case of acute myeloid leukemia with complex cytogenetic abnormalities suggestive of preexisting myelodysplastic syndrome in a patient with habitual ingestion of colloidal silver as nutritional supplement for over 10 years and the medical literature is reviewed.

A Novel Mutation in the Adult-Onset Alexander's Disease GFAP Gene

The case describes a 25-year-old Caucasian female diagnosed with Alexander's disease (AxD) as an outpatient after extensive inpatient workup. Her presenting complaints included incontinence, clumsiness, seizures, dysphagia, and dysarthria. She was also found to have pancytopenia and dysautonomia. A full neurologic and hematologic workup yielded very little results, until a thorough literature search of her presenting complaints and radiologic findings pointed to adult-onset Alexander's Disease. Alexander's disease is a rare genetic leukodystrophy with a broad variety of presentations. Despite its infrequency in adults and the difficulty in diagnosis, the prevalence of AxD has been increasing due to ease of genetic analysis and identification of key clinical and radiological findings. This case illustrates the necessity of vigilance and persistence in the face of unusual patient presentations; occasionally, the sound of hoofbeats is zebras.

Imidazolium and benzimidazolium-containing compounds: from simple toxic salts to highly bioactive drugs

The toxicity of simple imidazolium and benzimidazolium salts started to be more and more investigated in the last few years and was taken in consideration in the context of microorganisms, plants and more evolved organisms' exposure. However, the toxicity of these salts can be exploited in the development of different biological applications by incorporating them in the structure of compounds that specifically target microorganisms and cancer cells. We highlight in this minireview the way researchers became aware of the inherent problem of the stability and bioaccumulation of imidazolium and benzimidazolium salts and how they found inspiration to exploit their toxicity by incorporating them into new highly potent drugs.

Orthopaedic device-related infection: current and future interventions for improved prevention and treatment

Orthopaedic and trauma device-related infection (ODRI) remains one of the major complications in modern trauma and orthopaedic surgery.Despite best practice in medical and surgical management, neither prophylaxis nor treatment of ODRI is effective in all cases, leading to infections that negatively impact clinical outcome and significantly increase healthcare expenditure.The following review summarises the microbiological profile of modern ODRI, the impact antibiotic resistance has on treatment outcomes, and some of the principles and weaknesses of the current systemic and local antibiotic delivery strategies.The emerging novel strategies aimed at preventing or treating ODRI will be reviewed. Particular attention will be paid to the potential for clinical impact in the coming decades, when such interventions are likely to be critically important.The review focuses on this problem from an interdisciplinary perspective, including basic science innovations and best practice in infectious disease. Cite this article: Moriarty TF, Kuehl R, Coenye T, et al. Orthopaedic device related infection: current and future interventions for improved prevention and treatment. EFORT Open Rev 2016;1:89-99. DOI: 10.1302/2058-5241.1.000037.

Differential Effects of Silver Nanoparticles and Silver Ions on Tissue Accumulation, Distribution, and Toxicity in the Sprague Dawley Rat Following Daily Oral Gavage Administration for 13 Weeks

There are concerns within the regulatory and research communities regarding the health impact associated with consumer exposure to silver nanoparticles (AgNPs). This study evaluated particulate and ionic forms of silver and particle size for differences in silver accumulation, distribution, morphology, and toxicity when administered daily by oral gavage to Sprague Dawley rats for 13 weeks. Test materials and dose formulations were characterized by transmission electron microscopy (TEM), dynamic light scattering, and inductively coupled mass spectrometry (ICP-MS). Seven-week-old rats (10 rats per sex per group) were randomly assigned to treatments: AgNP (10, 75, and 110 nm) at 9, 18, and 36 mg/kg body weight (bw); silver acetate (AgOAc) at 100, 200, and 400 mg/kg bw; and controls (2 mM sodium citrate (CIT) or water). At termination, complete necropsies were conducted, histopathology, hematology, serum chemistry, micronuclei, and reproductive system analyses were performed, and silver accumulations and distributions were determined. Rats exposed to AgNP did not show significant changes in body weights or intakes of feed and water relative to controls, and blood, reproductive system, and genetic tests were similar to controls. Differences in the distributional pattern and morphology of silver deposits were observed by TEM: AgNP appeared predominantly within cells, while AgOAc had an affinity for extracellular membranes. Significant dose-dependent and AgNP size-dependent accumulations were detected in tissues by ICP-MS. In addition, sex differences in silver accumulations were noted for a number of tissues and organs, with accumulations being significantly higher in female rats, especially in the kidney, liver, jejunum, and colon.

4-Alkylated Silver-N-Heterocyclic Carbene (NHC) Complexes with Cytotoxic Effects in Leukemia Cells

Computational chemistry has shown that backbone-alkylated imidazoles ought to be efficient ligands for transition metal catalysts with improved carbene-to-metal donation. In this work, such alkylated imidazoles were synthesized and complexed with silver(I) by means of an eight/nine-step synthetic pathway we devised to access a new class of biologically active silver complexes. The synthesis involves selective iodination of the imidazole backbone, followed by Sonogashira coupling to replace the backbone iodine. The installed alkyne moiety is then subjected to reductive hydrogenation with Pearlman's catalyst. The imidazole N1 atom is arylated by the palladium-catalyzed Buchwald N-arylation method. The imidazole N3 position was then methylated with methyl iodine, whereupon the synthesis was terminated by complexation of the imidazolium salt with silver(I) oxide. The synthetic pathway provided an overall yield of ≈20 %. The resulting complexes were tested in vitro against HL60 and MOLM-13 leukemic cells, two human-derived cell lines that model acute myeloid leukemia. The most active compounds exhibiting low IC50 values of 14 and 27 μM, against HL60 and MOLM-13 cells, respectively. The imidazole side chain was found to be essential for high cytotoxicity, as the imidazole complex bearing a C7 side chain at the 4-position was four- to sixfold more potent than the corresponding imidazole elaborated with a methyl group.

Analyses of the modulatory effects of antibacterial silver doped calcium phosphate-based ceramic nano-powder on proliferation, survival, and angiogenic capacity of different mammalian cells in vitro

In this study, the antibacterial, cytotoxic, and angiogenic activities of silver doped calcium phosphate-based inorganic powder (ABT or PAG) were systematically investigated. ABT powders containing varying silver content were fabricated using a wet chemical manufacturing method. Antibacterial efficiencies of the ABT powders were investigated using a standard test with indicator bacteria and yeast. The cytotoxic effects of ABT on three different fibroblast cells and human umbilical vein endothelial cells (HUVECs) were assessed using MTT assay. ABT powder exhibits concentration-related cytotoxicity characteristics. Apoptotic activity, attachment capability, and wound healing effects were examined on fibroblasts. The angiogenic activity of ABT was investigated by tube formation assay in HUVECs; 10 μg ml(-1) and 100 μg ml(-1) concentrations of the highest metal ion content of ABT did not disrupt the tube formation of HUVECs. All these tests showed that ABT does not compromise the survival of the cells and might impose regeneration ability to various cell types. These results indicate that silver doped calcium phosphate-based inorganic powder with an optimal silver content has good potential for developing new biomaterials for implant applications.

Effects of particle size and coating on toxicologic parameters, fecal elimination kinetics and tissue distribution of acutely ingested silver nanoparticles in a mouse model

Consumer exposure to silver nanoparticles (AgNP) via ingestion can occur due to incorporation of AgNP into products such as food containers and dietary supplements. AgNP variations in size and coating may affect toxicity, elimination kinetics or tissue distribution. Here, we directly compared acute administration of AgNP of two differing coatings and sizes to mice, using doses of 0.1, 1 and 10 mg/kg body weight/day administered by oral gavage for 3 days. The maximal dose is equivalent to 2000× the EPA oral reference dose. Silver acetate at the same doses was used as ionic silver control. We found no toxicity and no significant tissue accumulation. Additionally, no toxicity was seen when AgNP were dosed concurrently with a broad-spectrum antibiotic. Between 70.5% and 98.6% of the administered silver dose was recovered in feces and particle size and coating differences did not significantly influence fecal silver. Peak fecal silver was detected between 6- and 9-h post-administration and <0.5% of the administered dose was cumulatively detected in liver, spleen, intestines or urine at 48 h. Although particle size and coating did not affect tissue accumulation, silver was detected in liver, spleen and kidney of mice administered ionic silver at marginally higher levels than those administered AgNP, suggesting that silver ion may be more bioavailable. Our results suggest that, irrespective of particle size and coating, acute oral exposure to AgNP at doses relevant to potential human exposure is associated with predominantly fecal elimination and is not associated with accumulation in tissue or toxicity.

Central nervous system toxicity of metallic nanoparticles

Nanomaterials (NMs) are increasingly used for the therapy, diagnosis, and monitoring of disease- or drug-induced mechanisms in the human biological system. In view of their small size, after certain modifications, NMs have the capacity to bypass or cross the blood–brain barrier. Nanotechnology is particularly advantageous in the field of neurology. Examples may include the utilization of nanoparticle (NP)-based drug carriers to readily cross the blood–brain barrier to treat central nervous system (CNS) diseases, nanoscaffolds for axonal regeneration, nanoelectromechanical systems in neurological operations, and NPs in molecular imaging and CNS imaging. However, NPs can also be potentially hazardous to the CNS in terms of nano-neurotoxicity via several possible mechanisms, such as oxidative stress, autophagy, and lysosome dysfunction, and the activation of certain signaling pathways. In this review, we discuss the dual effect of NMs on the CNS and the mechanisms involved. The limitations of the current research are also discussed.

Mechanisms of nanosilver-induced toxicological effects: more attention should be paid to its sublethal effects

Due to its unique physicochemical properties and remarkable antimicrobial activity, nanosilver (nAg) is increasingly being used in a wide array of fields, including medicine and personal care products. Despite substantial progress being made towards the understanding of the acute toxicity of nAg, large knowledge gaps still exist on the assessment of its chronic toxicity to humans. Chronic effects of nAg, typically at low doses (i.e. sublethal doses) should be different from the acute toxicity at high doses (i.e., lethal doses), which is analogous to other environmental pollutants. Although a few review papers have elaborated the findings on nAg-mediated toxicity, most of them only discussed overt toxicity of nAg at high-level exposure and failed to evaluate the chronic and cumulative effects of nAg at sublethal doses. Therefore, it is necessary to more stringently scrutinize the sublethal toxicity of nAg under environmentally relevant conditions. Herein, we recapitulated recent findings on the sublethal effects of nAg toxicity performed by our groups and others. We then discussed the molecular mechanisms by which nAg exerts its toxicity under low concentrations and compared that with nAg-induced cell death.

Synthesis of two new silver(I) complexes with 3-bromoquinoline: Molecular structure, spectroscopic characterizations and DFT studies

Two new Ag(+) complexes with 3-bromoquinoline (3BrQ) have been synthesized and characterized using elemental analysis, FTIR, NMR and mass spectra. The studied complexes have the formula [Ag(3BrQ)(OAC)]; 1 and [Ag(3BrQ)3(TCA)]; 2 where OAC and TCA are acetate and trichloroacetate, respectively. Based on the DFT calculations, 1 and 2 showed distorted trigonal planar and distorted tetrahedral coordination geometry. The electronic properties such as dipole moment (μ), polarizability (α0), HOMO and LUMO energies are calculated using the same level of theory. These electronic parameters were used to predict the nonlinear optical properties of the studied compounds. The studied silver complexes were predicted to be better nonlinear optical materials than urea. The electronic spectra of these complexes are calculated using the TD-DFT calculations. The infrared vibrational spectra were assigned based on the potential energy distribution (PED) analysis. The calculated (1)H NMR chemical shift values using GIAO approach showed good agreement with the experimental data. The intramolecular charge transfer interactions of the title molecules were studied by natural bond orbital (NBO) analysis.

Argyria resulting from chronic use of colloidal silver in a patient presenting for colonoscopy

An elderly male with a history of argyria caused by chronic ingestion of colloidal silver presented for elective colonoscopy. The patient's skin was a profound blue-gray color that caused concern among staff until his condition was identified through his medical and medication history. Colonoscopy and anesthesia proceeded without incident. The anesthetic management concerns include differentiating argyria from hypoxemia and other pathologies with similar appearance and clearly communicating the patient's history of argyria to follow-on caregivers to prevent unneeded diagnostic or interventional procedures. It is also important for caregivers to understand that the altered skin pigmentation of argyria does not interfere with pulse oximetry.

Synthesis and Anticancer Properties of Silver(I) Complexes Containing 2,6-Bis(substituted)pyridine Derivatives

Several new 2,6-bis(substituted)pyridine ligands and 2,6-bis(substituted)pyridine Ag(I) nitrate complexes were synthesized and characterized spectroscopically. The newly synthesized ligands include pyridine-2,6-bis(3-oxopropanenitrile) (1), pyridine-2,6-bis(2-cyano-N-phenyl-3-oxopropanethioamide) (2), and pyridine-2,6-bis((E)-2-(2-phenylhydrazono)-3-oxopropanenitrile) (3). The newly synthesized ligands and silver(I) complexes were evaluated for their in vitro anticancer activity against four human cancer cell lines including hepatocellular carcinoma (HePG2), lung adenocarcinoma (A549), colon carcinoma (HT29), and breast adenocarcinoma (MCF7). Most of the newly synthesized silver(I) complexes exhibited better activity than the ligands, and the results have been compared with doxorubicin as a reference drug.

Argyria -- case report

A 70-year-old male rural worker was referred to our clinic with widespread grey pigmentation of the skin and nails. The condition had been asymptomatic for its entire duration (5 years). He reported past intranasal application of 10% Silver Vitellinate. A skin biopsy was performed and histology corroborated the clinical diagnosis of Argyria. This case represents a currently rare dermatological curiosity. Although silver colloids and salts have been withdrawn and/or banned by some drug surveillance agencies, they continue to be freely sold and unregulated as food supplements and as ingredients in alternative medicines, thereby risking the emergence of new cases of silver poisoning.

Oral toxicity of silver ions, silver nanoparticles and colloidal silver--a review

Orally administered silver has been described to be absorbed in a range of 0.4-18% in mammals with a human value of 18%. Based on findings in animals, silver seems to be distributed to all of the organs investigated, with the highest levels being observed in the intestine and stomach. In the skin, silver induces a blue-grey discoloration termed argyria. Excretion occurs via the bile and urine. The following dose-dependent animal toxicity findings have been reported: death, weight loss, hypoactivity, altered neurotransmitter levels, altered liver enzymes, altered blood values, enlarged hearts and immunological effects. Substantial evidence exists suggesting that the effects induced by particulate silver are mediated via silver ions that are released from the particle surface. With the current data regarding toxicity and average human dietary exposure, a Margin of Safety calculation indicates at least a factor of five before a level of concern to the general population is reached.

Toxicity of novel nanosized formulations used in medicine

Nanotechnology involves the creation and manipulation of materials at nanoscale levels (1-100 nm) to create products that exhibit novel properties. While this motivation has driven nanoscience and technology in physics and engineering, it is not the main reason that nanoparticles are useful for systemic applications in the human body. The application of nanotechnology to medicine, known as nanomedicine, concerns the use of precisely engineered materials at this length scale to develop novel therapeutic and diagnostic modalities. A number of nanotherapeutic formulations are already approved for medical use and more are in the approval pipeline currently. This chapter is intended to provide an overview of the toxicity of these therapeutic nanoparticles and to summarize the current state of the field. We begin with background on the sources of exposure to nanoparticles, followed by reviewing different forms of nanosized therapeutic tools as quantum dots, nanoshells, nanocapsules, echogenic bubble, and "nanoshuttles." Moreover, cytotoxic effects of nanoparticles on cell membrane, mitochondrial function, prooxidant/antioxidant status, enzyme leakage, DNA, and other biochemical endpoints were elucidated. We highlight the need for caution during the use and disposal of such manufactured nanomaterials to prevent unintended environmental impacts. Moreover, different strategies which could be used to minimize or eliminate nanotoxicity were also discussed in detail. Understanding of how to tune size and surface properties to provide safety will permit the creation of new, more effective nanomedicines for systemic use.

Short term serum pharmacokinetics of diammine silver fluoride after oral application

Background

There is growing interest in the use of diammine silver fluoride (DSF) as a topical agent to treat dentin hypersensitivity and dental caries as gauged by increasing published research from many parts of the world. While DSF has been available in various formulations for many years, most of its pharmacokinetic aspects within the therapeutic concentration range have never been fully characterized.

Methods

This preliminary study determined the applied doses (3 teeth treated), maximum serum concentrations, and time to maximum serum concentration for fluoride and silver in 6 adults over 4 h. Fluoride was determined using the indirect diffusion method with a fluoride selective electrode, and silver was determined using inductively coupled plasma-mass spectrometry. The mean amount of DSF solution applied to the 3 teeth was 7.57 mg (6.04 μL).

Results

Over the 4 hour observation period, the mean maximum serum concentrations were 1.86 μmol/L for fluoride and 206 nmol/L for silver. These maximums were reached 3.0 h and 2.5 h for fluoride and silver, respectively.

Conclusions

Fluoride exposure was below the U.S. Environmental Protection Agency (EPA) oral reference dose. Silver exposure exceeded the EPA oral reference dose for cumulative daily exposure over a lifetime, but for occasional use was well below concentrations associated with toxicity. This preliminary study suggests that serum concentrations of fluoride and silver after topical application of DSF should pose little toxicity risk when used in adults.

Clinical trials registration

NCT01664871.

The inhibitory effects of nano-Ag on voltage-gated potassium currents of hippocampal CA1 neurons

The application of the nano-sized materials continues to grow at a rapid rate in the fields of medicine, biotechnology, and environmental technology. Voltage-gated potassium currents play a key role in excitable cellular viability and function, especially in the central nervous system. The aim of this study was to investigate the actions of silver nano-particles (nano-Ag) on voltage-activated potassium currents in hippocampal CA1 neurons using whole cell patch-clamp technique. The hydrodynamic mean diameter of nano-Ag (10(-5) g mL(-1) ) was 223.9 nm in artificial cerebrospinal fluid (ACSF). Both types, transient potassium (I(A) ) and delayed rectifier potassium (I(K) ) current amplitudes were inhibited by the nano-Ag (10(-5) g mL(-1) ). The nano-Ag particles produced a hyperpolarizing shift in the activation-voltage curve of I(K) and inactivation-voltage curve of I(A) and also delayed the recovery of I(A) from inactivation. The results suggest that nano-Ag may have potential to alter the excitability of neurons by depressing the potassium channels.

Rapid onset of argyria induced by a silver-containing dietary supplement

We describe a 53-year-old man in good general health who presented with an 8-month history of progressive gray hyperpigmentation of the face. He denied using any prescription medications; however, he admitted to taking a herbal supplement. Clinically, the differential diagnosis included hemochromatosis, Wilson's disease and hyperpigmentation secondary to supplement use. Punch biopsies from the left forehead and preauricular region showed heavily sun-damaged skin with a minimal inflammatory infiltrate. Closer inspection, however, revealed minute scattered black/brown particles distributed in the basement membrane zone of eccrine and sebaceous glands. Similar particles were also present in hair follicles, blood vessels and arrector pili muscles. The particles did not stain with Gomori methenamine silver, Fontana-Masson or iron stains. Electron microscopy with energy-dispersive x-ray analysis showed numerous particles, less than 1 µm in greatest dimension, which showed peaks for silver and sulfur. This analytical result confirmed the impression of argyria. Further history revealed that the patient had indeed been taking a silver supplement for several months under the premise that it would boost his immune system. This case is unique in that the patient's hyperpigmentation developed in a short period of time as compared with other reports in the medical literature.

Myoclonus

Myoclonus can be classified as physiologic, essential, epileptic, and symptomatic. Animal models of myoclonus include DDT and posthypoxic myoclonus in the rat. 5-Hydrotryptophan, clonazepam, and valproic acid suppress myoclonus induced by posthypoxia. The diagnostic evaluation of myoclonus is complex and involves an extensive work-up including basic electrolytes, glucose, renal and hepatic function tests, paraneoplastic antibodies, drug and toxicology screens, thyroid antibody and function studies, neurophysiology testing, imaging, and tests for malabsorption disorders, assays for enzyme deficiencies, tissue biopsy, copper studies, alpha-fetoprotein, cytogenetic analysis, radiosensitivity DNA synthesis, genetic testing for inherited disorders, and mitochondrial function studies. Treatment of myoclonus is targeted to the underlying disorder. If myoclonus physiology cannot be demonstrated, treatment should be aimed at the common pattern of symptoms. If the diagnosis is not known, treatment could be directed empirically at cortical myoclonus as the most common physiology. In cortical myoclonus, the most effective drugs are sodium valproic acid, clonazepam, levetiracetam, and piracetam. For cortical-subcortical myoclonus, valproic acid is the drug of choice. Here, lamotrigine can be used either alone or in combination with valproic acid. Ethosuximide, levetiracetam, or zonisamide can also be used as adjunct therapy with valproic acid. A ketogenic diet can be considered if everything else fails. Subcortical-nonsegmental myoclonus may respond to clonazepam and deep-brain stimulation. Rituximab, adrenocorticotropic hormone, high-dose dexamethasone pulse, or plasmapheresis have been reported to improve opsoclonus myoclonus syndrome. Reticular reflex myoclonus can be treated with clonazepam, diazepam and 5-hydrotryptophan. For palatal myoclonus, a variety of drugs have been used.

The release of nanosilver from consumer products used in the home

Nanosilver has become one of the most widely used nanomaterials in consumer products because of its antimicrobial properties. Public concern over the potential adverse effects of nanosilver's environmental release has prompted discussion of federal regulation. In this paper, we assess several classes of consumer products for their silver content and potential to release nanosilver into water, air, or soil. Silver was quantified in a shirt, a medical mask and cloth, toothpaste, shampoo, detergent, a towel, a toy teddy bear, and two humidifiers. Silver concentrations ranged from 1.4 to 270,000 microg Ag g product(-1). Products were washed in 500 mL of tap water to assess the potential release of silver into aqueous environmental matrices (wastewater, surface water, saliva, etc.). Silver was released in quantities up to 45 microg Ag g product(-1), and size fractions were both larger and smaller than 100 nm. Scanning electron microscopy confirmed the presence of nanoparticle silver in most products as well as in the wash water samples. Four products were subjected to a toxicity characterization leaching procedure to assess the release of silver in a landfill. The medical cloth released an amount of silver comparable to the toxicity characterization limit. This paper presents methodologies that can be used to quantify and characterize silver and other nanomaterials in consumer products. The quantities of silver in consumer products can in turn be used to estimate real-world human and environmental exposure levels.