Physiological and toxicological changes in the skin resulting from the action and interaction of metal ions

Geochemical fractionation of iron in paper industry and municipal landfill soils: Ecological and health risks insights

Industrial processes and municipal wastes largely contribute to the fluctuations in iron (Fe) content in soils. Fe, when present in unfavorable amount, causes harmful effects on human, flora, and fauna. The present study is an attempt to evaluate the composition of Fe in surface soils from paper mill and municipal landfill sites and assess their potential ecological and human health risks. Geochemical fractionation was conducted to explore the chemical bonding of Fe across different fractions, i.e., water-soluble (F1) to residual (F6). Different contamination factors and pollution indices were evaluated to comprehend Fe contamination extent across the study area. Results indicated the preference for less mobile forms in the paper mill and landfill, with 26.66% and 43.46% of Fe associated with the Fe-Mn oxide bound fraction (F4), and 57.22% and 24.78% in the residual fraction (F6). Maximum mobility factor (MF) of 30.65% was observed in the paper mill, and 80.37% in the landfill. The enrichment factor (EF) varied within the range of 20 < EF < 40, signifying a high level of enrichment in the soil. The individual contamination factor (ICF) ranged from 0 to >6, highlighting low to high contamination. Adults were found to be more vulnerable towards Fe associated health risks compared to children. The Hazard Quotient (HQ) index showed the highest risk potential pathways as dermal contact > ingestion > inhalation. The study offers insights into potential Fe contamination risks in comparable environments, underscoring the crucial role of thorough soil assessments in shaping land use and waste management policies.

Relation Between Reactive Oxygen Species Production and Transient Receptor Potential Vanilloid1 Expression in Human Skin During Aging

Skin sensitivity and impaired epidermal barrier function are associated with aging and are at least partly due to increased production of reactive oxygen species (ROS). Transient receptor potential vanilloid1 (TRPV1) is expressed in keratinocytes, fibroblasts, mast cells, and endothelial cells in skin. We investigated in skin biopsies of adult and elderly donors whether TRPV1 expression is involved in the skin aging process. We found that aging skin showed a strongly reduced epidermal thickness, strongly increased oxidative stress, protease expression, and mast cell degranulation and strongly increased TRPV1 expression both in epidermis and dermis. Based on our findings, the aging-related changes observed in the epidermis of the skin level are associated with increased ROS production, and hypothesized alterations in TRPV1 expression are mechanistically linked to this process.

Exposure to low-dose arsenic caused teratogenicity and upregulation of proinflammatory cytokines in zebrafish embryos

Arsenic is currently ranked as the most toxicant on the ATSDR 2015 substance priority list and is categorised as a Group 1 human carcinogen. Biota that are subjected to inorganic arsenicals through food, water, occupational or medical exposure pose a risk to the environment and to human health. The present study was carried out to investigate the toxicity caused by inorganic arsenic. After fertilisation, zebrafish embryos were exposed to sodium arsenite at several concentrations (100 nM to 600 nM) for 24 to 96 hpf. The indicators of teratogenicity (hatchability, morphological abnormalities, mortality), behavioural modifications (touch induced escape response (TIER), startle response (SR) and turning behaviour (TB)), biochemical testing (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), and glutathione S transferase (GST)) and the expressions of tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6) and cyclooxygenase-2 (COX-2) were investigated. The aforementioned parameters were found to be altered in embryos exposed to sodium arsenite. According to the findings of the current study, even a low dose of inorganic arsenic compound caused teratogenicity, behavioural abnormalities, altered enzyme activities and the expression of proinflammatory cytokines in zebrafish embryos.

Silver Nanoparticles and Its Mechanistic Insight for Chronic Wound Healing: Review on Recent Progress

Wounds are structural and functional disruptions of skin that occur because of trauma, surgery, acute illness, or chronic disease conditions. Chronic wounds are caused by a breakdown in the finely coordinated cascade of events that occurs during healing. Wound healing is a long process that split into at least three continuous and overlapping processes: an inflammatory response, a proliferative phase, and finally the tissue remodeling. Therefore, these processes are extensively studied to develop novel therapeutics in order to achieve maximum recovery with minimum scarring. Several growth hormones and cytokines secreted at the site of lesions tightly regulates the healing processes. The traditional approach for wound management has been represented by topical treatments. Metal nanoparticles (e.g., silver, gold and zinc) are increasingly being employed in dermatology due to their favorable effects on healing, as well as in treating and preventing secondary bacterial infections. In the current review, a brief introduction on traditional would healing approach is provided, followed by focus on the potential of wound dressing therapeutic techniques functionalized with Ag-NPs.

A comprehensive summary of disease variants implicated in metal allergy

Allergic disease represents one of the most prominent global public health crises of the 21^st century. Although many different substances are known to produce hypersensitivity responses, metals constitute one of the major classes of allergens responsible for a disproportionately large segment of the total burden of disease associated with allergy. Some of the most prevalent forms of metal allergy - including allergic contact dermatitis - are well-recognized; however, to our knowledge, a comprehensive review of the many unique disease variants implicated in human cases of metal allergy is not available within the current scientific literature. Consequently, the main goal in composing this review was to (1) generate an up-to-date reference document containing this information to assist in the efforts of lab researchers, clinicians, regulatory toxicologists, industrial hygienists, and other scientists concerned with metal allergy and (2) identify knowledge gaps related to disease. Accordingly, an extensive review of the scientific literature was performed - from which, hundreds of publications describing cases of metal-specific allergic responses in human patients were identified, collected, and analyzed. The information obtained from these articles was then used to compile an exhaustive list of distinctive dermal/ocular, respiratory, gastrointestinal, and systemic hypersensitivity responses associated with metal allergy. Each of these disease variants is discussed briefly within this review, wherein specific metals implicated in each response type are identified, underlying immunological mechanisms are summarized, and major clinical presentations of each reaction are described.Abbreviations: ACD: allergic contact dermatitis, AHR: airway hyperreactivity, ASIA: autoimmune/ autoinflammatory syndrome induced by adjuvants, BAL: bronchoalveolar lavage, CBD: chronic beryllium disease, CTCL: cutaneous T-cell lymphoma, CTL: cytotoxic T-Lymphocyte, DRESS: drug reaction with eosinophilia and systemic symptoms, GERD: gastro-esophageal reflux disease, GI: gastrointestinal, GIP: giant cell interstitial pneumonia, GM-CSF: granulocyte macrophage-colony stimulating factor, HMLD: hard metal lung disease, HMW: high molecular weight, IBS: irritable bowel syndrome, Ig: immunoglobulin, IL: interleukin, LMW: low molecular weight, PAP: pulmonary alveolar proteinosis, PPE: personal protective equipment, PRR: pathogen recognition receptor, SLE: systemic lupus erythematosus, SNAS: systemic nickel allergy syndrome, Th: helper T-cell, UC: ulcerative colitis, UV: ultraviolet.

Skin Minerals: Key Roles of Inorganic Elements in Skin Physiological Functions

As odd as it may seem at first glance, minerals, it is what we are all about…or nearly. Although life on Earth is carbon-based, several other elements present in the planet’s crust are involved in and often indispensable for functioning of living organisms. Many ions are essential, and others show supportive and accessory qualities. They are operative in the skin, supporting specific processes related to the particular situation of this organ at the interface with the environment. Skin bioenergetics, redox balance, epidermal barrier function, and dermal remodeling are amongst crucial activities guided by or taking advantage of mineral elements. Skin regenerative processes and skin ageing can be positively impacted by adequate accessibility, distribution, and balance of inorganic ions.

Assessment of dermal absorption of beryllium and copper contained in temple tips of eyeglasses

Dermal exposure to hazardous substances such as chemicals, toxics, metallic items and other contaminants may present substantial danger for health. Beryllium (Be) is a hazardous metal, especially when inhaled and/or in direct contact with the skin, associated with chronic beryllium disease (CBD) and Be sensitization (BeS). The objective of this study was to investigate the percutaneous penetration of beryllium and copper contained in metallic items as eyeglass temple tips (specifically BrushCAST® Copper Beryllium Casting Alloys containing Be 0.35 < 2.85%; Cu 95.3-98.7%), using Franz diffusion cells. This work demonstrated that the total skin absorption of Cu was higher (8.86%) compared to Be (4.89%), which was expected based on the high percentage of Cu contained in the eyeglass temple tips. However, Be accumulated significantly in the epidermis and dermis (up to 0.461 µg/cm²) and, to a lesser extent, in the stratum corneum (up to 0.130 µg/cm²) with a flux of permeation of 3.52 ± 4.5 µg/cm²/hour and lag time of 2.3 ± 1.3 h, after cutaneous exposure of temple tip into 1.0 mL artificial sweat for 24 h. Our study highlights the importance of avoiding the use of Be alloys in items following long-term skin contact.

Arsenic Toxicity on Metabolism and Autophagy in Adipose and Muscle Tissues

Arsenic, a naturally occurring metalloid derived from the environment, has been studied worldwide for its causative effects in various cancers. However, the effects of arsenic toxicity on the development and progression of metabolic syndrome, including obesity and diabetes, has received less attention. Many studies suggest that metabolic dysfunction and autophagy dysregulation of adipose and muscle tissues are closely related to the development of metabolic disease. In the USA, arsenic contamination has been reported in some ground water, soil and grain samples in major agricultural regions, but the effects on adipose and muscle tissue metabolism and autophagy have not been investigated much. Here, we highlight arsenic toxicity according to the species, dose and exposure time and the effects on adipose and muscle tissue metabolism and autophagy. Historically, arsenic was used as both a poison and medicine, depending on the dose and treatment time. In the modern era, arsenic intoxication has significantly increased due to exposure from water, soil and food, which could be a contributing factor in the development and progression of metabolic disease. From this review, a better understanding of the pathogenic mechanisms by which arsenic alters metabolism and autophagy regulation could become a cornerstone leading to the development of therapeutic strategies against arsenic-induced toxicity and metabolic disease.

Inorganic ions in the skin: Allies or enemies?

Skin constitutes a barrier protecting the organism against physical and chemical factors. Therefore, it is constantly exposed to the xenobiotics, including inorganic ions that are ubiquitous in the environment. Some of them play important roles in homeostasis and regulatory functions of the body, also in the skin, while others can be considered dangerous. Many authors have shown that inorganic ions could penetrate inside the skin and possibly induce local effects. In this review, we give an account of the current knowledge on the effects of skin exposure to inorganic ions. Beneficial effects on skin conditions related to the use of thermal spring waters are discussed together with the application of aluminium in underarm hygiene products and silver salts in treatment of difficult wounds. Finally, the potential consequences of dermal exposure to topical sensitizers and harmful heavy ions including radionuclides are discussed.

Correlation between Elemental Composition/Mobility and Skin Cell Proliferation of Fibrous Nanoclay/Spring Water Hydrogels

Inorganic hydrogels formulated with spring waters and clay minerals are used to treat musculoskeletal disorders and skin affections. Their underlying mechanism of action for skin disorders is not clear, although it is usually ascribed to the chemical composition of the formulation. The aim of this study was to assess the composition and in vitro release of elements with potential wound healing effects from hydrogels prepared with two nanoclays and natural spring water. In vitro Franz cell studies were used and the element concentration was measured by inductively coupled plasma techniques. Biocompatibility studies were used to evaluate the potential toxicity of the formulation against fibroblasts. The studied hydrogels released elements with known therapeutic interest in wound healing. The released ratios of some elements, such as Mg:Ca or Zn:Ca, played a significant role in the final therapeutic activity of the formulation. In particular, the proliferative activity of fibroblasts was ascribed to the release of Mn and the Zn:Ca ratio. Moreover, the importance of formulative studies is highlighted, since it is the optimal combination of the correct ingredients that makes a formulation effective.

The Efficacy of Five Different Wound Dressings on Some Histological Parameters in Children With Partial-Thickness Burns

An ideal dressing should ensure that the wound remains moist with exudates but not macerated. Currently, there is no dressing available to suit all wounds, at all stages of the healing process. Although silver-containing dressings are the gold standard for burn wound care, few high-level trials have been completed comparing the clinical utilities of these dressings. In our study, five different types of wound dressings: carboxymethyl cellulose hydrofiber dressing with ionized silver (CMCH-Ag), polyethylene-polyethylene terephthalate aqua fiber dressing with elementary silver (PPAF-Ag), calcium alginate (CA), calcium + zinc alginate (CZA), and 0.2% nitrofurazone-embedded (NF) gauze dressings were compared in regard to histopathological parameters. Children aged between 0 and 18 years with small or middle-sized partial-thickness burns that affected less than 30% of the total body surface area were included in this study. The study groups (CMCH-Ag, PPAF-Ag, CA, and CZA) and the control group (NF) were randomly attained. Wound healing was evaluated by punch biopsies on the 21st day. The thickness of the stratum corneum and the epithelium, the number of papillae, and the papillary length were calculated and compared. The histological parameters of healing, except the stratum corneum thickness, did not show any statistical significance among the groups (P &gt; .05). The dressings that included silver, calcium, or zinc showed useful and similar effects in noninfective burn wounds when compared with nitrofurazone-only dressings. Thus, it may be concluded that silver-containing wound dressings should not be considered as the gold standard in noninfective partial-thickness burn wounds in children.

Cysteine-Capped Hydrogels Incorporating Copper as Effective Antimicrobial Materials against Methicillin-Resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (S. aureus) (MRSA) has become an alarming threat to public health, and infected soft tissue. Antibiotics are commonly used to treat skin infection with MRSA, but the inappropriate use of antibiotics runs a considerable risk of generating resistant S. aureus. In this study, we created a cysteine-capped hydrogel able to absorb and release copper, an ion with the capability of suppressing the growth of USA300, a community-acquired MRSA. The results of analysis of Fourier transform infrared spectroscopy (FTIR) revealed the binding of copper to a cysteine-capped hydrogel. The topical application of a cysteine-capped hydrogel binding with copper on USA300-infected skin wounds in the dorsal skin of Institute of Cancer Research (ICR) mice significantly enhanced wound healing, hindered the growth of USA300, and reduced the production of pro-inflammatory macrophage inflammatory protein 2-alpha (MIP-2) cytokine. Our work demonstrates a newly designed hydrogel that conjugates a cysteine molecule for copper binding. The cysteine-capped hydrogel can potentially chelate various antimicrobial metals as a novel wound dressing.

Metal nanomaterials: Immune effects and implications of physicochemical properties on sensitization, elicitation, and exacerbation of allergic disease

The recent surge in incorporation of metallic and metal oxide nanomaterials into consumer products and their corresponding use in occupational settings have raised concerns over the potential for metals to induce size-specific adverse toxicological effects. Although nano-metals have been shown to induce greater lung injury and inflammation than their larger metal counterparts, their size-related effects on the immune system and allergic disease remain largely unknown. This knowledge gap is particularly concerning since metals are historically recognized as common inducers of allergic contact dermatitis, occupational asthma, and allergic adjuvancy. The investigation into the potential for adverse immune effects following exposure to metal nanomaterials is becoming an area of scientific interest since these characteristically lightweight materials are easily aerosolized and inhaled, and their small size may allow for penetration of the skin, which may promote unique size-specific immune effects with implications for allergic disease. Additionally, alterations in physicochemical properties of metals in the nano-scale greatly influence their interactions with components of biological systems, potentially leading to implications for inducing or exacerbating allergic disease. Although some research has been directed toward addressing these concerns, many aspects of metal nanomaterial-induced immune effects remain unclear. Overall, more scientific knowledge exists in regards to the potential for metal nanomaterials to exacerbate allergic disease than to their potential to induce allergic disease. Furthermore, effects of metal nanomaterial exposure on respiratory allergy have been more thoroughly-characterized than their potential influence on dermal allergy. Current knowledge regarding metal nanomaterials and their potential to induce/exacerbate dermal and respiratory allergy are summarized in this review. In addition, an examination of several remaining knowledge gaps and considerations for future studies is provided.

Wing membrane and fur samples as reliable biological matrices to measure bioaccumulation of metals and metalloids in bats

There is a growing conservation concern about the possible consequences of environmental contamination in the health of bat communities. Most studies on the effects of contaminants in bats have been focused on organic contaminants, and the consequences of bat exposure to metals and metalloids remain largely unknown. The aim of this study was to evaluate the suitability of external biological matrices (fur and wing membrane) for the assessment of exposure and bioaccumulation of metals in bats. The concentration of arsenic, cadmium, cobalt, chromium, copper, manganese, nickel, lead, selenium and zinc was measured in internal organs (liver, heart, brain), internal (bone) and external tissues (wing membrane, fur) collected from bat carcasses of four species (Hypsugo savii, Nyctalus leisleri, Pipistrellus pipistrellus, Pipistrellus pygmaeus) obtained in windfarm mortality searches. With the exception of zinc (P = 0.223), the results showed significant differences between the concentrations of metals in the analyzed tissues for all metals (P < 0.05). Significant differences were also found between organs/tissues (P < 0.001), metals (P < 0.001) and a significant interaction between organs/tissues and metals was found (P < 0.001). Despite these results, the patterns in terms of metal accumulation were similar for all samples. Depending on the metal, the organ/tissue that showed the highest concentrations varied, but fur and wing had the highest concentrations for most metals. The variability obtained in terms of metal concentrations in different tissues highlights the need to define standardized methods capable of being applied in monitoring bat populations worldwide. The results indicate that wing membrane and fur, biological matrices that may be collected from living bats, yield reliable results and may be useful for studies on bats ecotoxicology, coupled to a standardized protocol for large-scale investigation of metal accumulation.

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.

Sodium ascorbate (SA) and l-ascorbic acid (AA) as modifiers of burn affected skin - A comparative analysis

Proper functioning of living organisms requires controlling the factors which govern the level of oxidative stress in the system, that is presence of free radicals at a given, rather low, level and preventing their excess. In this work it is shown that SA and AA active antioxidants, governing the oxidative stress in the wound, modify standard serum solution as well as burn affected necrotic eschar at the molecular structure level. In the case of incubation of skin fragments in SA and AA, the following findings were reported: modification of serum, that is appearance of low molecular weight oligomer bands in AA and recreation of native serum bands in SA. In frozen serum solutions modified by AA FTIR 1759 and 1420-1053 cm^-1 bands are observed, whereas in SA FTIR 1603, 1411-1054 and 536 cm^-1 bands appear. In the case of modification of the burn affected necrotic eschar in SA and AA - frequency shifts in the fingerprint region 1780-1000 cm^-1 can be biomarkers indicating tissue regeneration process under the influence of antioxidants. 1780-1580 cm^-1 and 1418-1250 cm^-1 regions on the Raman spectra are particularly rich in spectral information. Modification of samples of skin burnt with AA activates the regions of the β-sheet aggregates whereas treatment of the samples with SA ascorbate demonstrates changes which testify to reconstruction of α-helix structure (SAXS studies).

Enhancing Skin Health: By Oral Administration of Natural Compounds and Minerals with Implications to the Dermal Microbiome

The history of cosmetics goes back to early Egyptian times for hygiene and health benefits while the history of topical applications that provide a medicinal treatment to combat dermal aging is relatively new. For example, the term cosmeceutical was first coined by Albert Kligman in 1984 to describe topical products that afford both cosmetic and therapeutic benefits. However, beauty comes from the inside. Therefore, for some time scientists have considered how nutrition reflects healthy skin and the aging process. The more recent link between nutrition and skin aging began in earnest around the year 2000 with the demonstrated increase in peer-reviewed scientific journal reports on this topic that included biochemical and molecular mechanisms of action. Thus, the application of: (a) topical administration from outside into the skin and (b) inside by oral consumption of nutritionals to the outer skin layers is now common place and many journal reports exhibit significant improvement for both on a variety of dermal parameters. Therefore, this review covers, where applicable, the history, chemical structure, and sources such as biological and biomedical properties in the skin along with animal and clinical data on the oral applications of: (a) collagen, (b) ceramide, (c) β-carotene, (d) astaxanthin, (e) coenzyme Q10, (f) colostrum, (g) zinc, and (h) selenium in their mode of action or function in improving dermal health by various quantified endpoints. Lastly, the importance of the human skin microbiome is briefly discussed in reference to the genomics, measurement, and factors influencing its expression and how it may alter the immune system, various dermal disorders, and potentially be involved in chemoprevention.

Natural Antioxidants Against Arsenic-Induced Genotoxicity

Arsenic is present in water, soil, and air in organic as well as in inorganic forms. However, inorganic arsenic is more toxic than organic and can cause many diseases including cancers in humans. Its genotoxic effect is considered as one of its carcinogenic actions. Arsenic can cause DNA strand breaks, deletion mutations, micronuclei formation, DNA-protein cross-linking, sister chromatid exchange, and DNA repair inhibition. Evidences indicate that arsenic causes DNA damage by generation of reactive free radicals. Nutritional supplementation of antioxidants has been proven highly beneficial against arsenic genotoxicity in experimental animals. Recent studies suggest that antioxidants protect mainly by reducing excess free radicals via restoring the activities of cellular enzymatic as well as non-enzymatic antioxidants and decreasing the oxidation processes such as lipid peroxidation and protein oxidation. The purpose of this review is to summarize the recent literature on arsenic-induced genotoxicity and its mitigation by naturally derived antioxidants in various biological systems.

In vitro investigations of a novel wound dressing concept based on biodegradable polyurethane

Non-healing and partially healing wounds are an important problem not only for the patient but also for the public health care system. Current treatment solutions are far from optimal regarding the chosen material properties as well as price and source. Biodegradable polyurethane (PUR) scaffolds have shown great promise for in vivo tissue engineering approaches, but accomplishment of the goal of scaffold degradation and new tissue formation developing in parallel has not been observed so far in skin wound repair. In this study, the mechanical properties and degradation behavior as well as the biocompatibility of a low-cost synthetic, pathogen-free, biocompatible and biodegradable extracellular matrix mimicking a PUR scaffold was evaluated in vitro. The novel PUR scaffolds were found to meet all the requirements for optimal scaffolds and wound dressings. These three-dimensional scaffolds are soft, highly porous, and form-stable and can be easily cut into any shape desired. All the material formulations investigated were found to be nontoxic. One formulation was able to be defined that supported both good fibroblast cell attachment and cell proliferation to colonize the scaffold. Tunable biodegradation velocity of the materials could be observed, and the results additionally indicated that calcium plays a crucial role in PUR degradation. Our results suggest that the PUR materials evaluated in this study are promising candidates for next-generation wound treatment systems and support the concept of using foam scaffolds for improved in vivo tissue engineering and regeneration.

Hypersensitivity from intravenous iron products

In the last several years, intravenous therapy with iron products has been more widely used. Although it has been a standard procedure in dialysis-associated anemia since the early 1990s, its use is expanding to a host of conditions associated with iron deficiency, especially young women with heavy uterine bleeding and pregnancy. Free iron is associated with unacceptable high toxicity inducing severe, hemodynamically significant symptoms. Subsequently, formulations that contain the iron as an iron carbohydrate nanoparticle have been designed. With newer formulations, including low-molecular-weight iron dextran, iron sucrose, ferric gluconate, ferumoxytol, iron isomaltoside, and ferric carboxymaltose, serious adverse events are rare.

Elemental characterisation of the medical plant Alchemilla velebitica

Alchemilla, commonly called "lady's mantle", is a genus of herbaceous perennial plants belonging to the family Rosaceae. The species Alchemilla velebitica is found only in Southern Europe, like in the Croatian National Park Northern Velebit. Its benefits, such as a astringent and emmenagogue activity as well as wound healing are correlated to the organic compounds found in the plant, but also certain trace elements are known to reduce skin lesions, such as zinc, selenium, copper, manganese, silicon and lithium. Thus the objective of the present study was the elemental characterization of leaves, blossoms and roots of A. velebitica. After acidic microwave assisted digestion the concentrations of selected essential and trace elements were determined by inductively coupled plasma--atomic emission spectrometry and inductively coupled plasma--mass spectrometry. Other minor elements, such as Al, B, Cu, Fe, Mn, Sr and Zn are also found in leaves, blossoms and roots with contents in μg/kg range. The preparation of decoctions and the extraction yields of the elements of interest are calculated.

Effects of magnesium deficiency--more than skin deep

Dead Sea and magnesium salt therapy are two of the oldest forms of treatment for skin disease and several other disorders, supported by a body of largely anecdotal evidence. In this paper we review possible pathways for penetration of magnesium ions through the epidermis to reach the circulation, in turn replenishing cellular magnesium levels. We also discuss mechanisms for intercellular movement of magnesium ions and possible mechanisms for the interaction between magnesium ions and inflammatory mediators. Upon addition of magnesium ions in vitro, the expression of inflammatory mediators such as tumour necrosis factor α (TNFα) and nuclear factor κβ (NFκβ) is down regulated. Dysregulation of these and other inflammatory mediators has been linked to several inflammatory disorders, including asthma, arthritis, atherosclerosis and neuroinflammation.

Bidirectional functions of arsenic as a carcinogen and an anti-cancer agent in human squamous cell carcinoma

Bidirectional cancer-promoting and anti-cancer effects of arsenic for cancer cells have been revealed in previous studies. However, each of these effects (cancer-promoting or anti-cancer) was found in different cells at different treated-concentration of arsenic. In this study, we for the first time indicated that arsenic at concentration of 3 µM, equal to average concentration in drinking water in cancer-prone areas in Bangladesh, simultaneously expressed its bidirectional effects on human squamous cell carcinoma HSC5 cells with distinct pathways. Treatment with 3 µM of arsenic promoted cell invasion via upregulation of expression of MT1-MMP and downregulation of expression of p14ARF and simultaneously induced cell apoptosis through inhibition of expression of N-cadherin and increase of expression of p21(WAF1/CIP1) at both transcript and protein levels in HSC5 cells. We also showed that inhibition of MT1-MMP expression by NSC405020 resulted in decrease of arsenic-mediated invasion of HSC5 cells involving decrease in phosphorylated extracellular signal-regulated kinases (pERK). Taken together, our biological and biochemical findings suggested that arsenic expressed bidirectional effects as a carcinogen and an anti-cancer agent in human squamous cell carcinoma HSC5 cells with distinct pathways. Our results might play an important scientific evident for further studies to find out a better way in treatment of arsenic-induced cancers, especially in squamous cell carcinoma.

Pretreatment hepatoprotective effect of the marine fungus derived from sponge on hepatic toxicity induced by heavy metals in rats

The aim of this study was to evaluate the pretreatment hepatoprotective effect of the extract of marine-derived fungus Trichurus spiralis Hasselbr (TS) isolated from Hippospongia communis sponge on hepatotoxicity. Twenty-eight male Sprague-Dawley rats were divided into four groups (n = 7). Group I served as −ve control, group II served as the induced group receiving subcutaneously for seven days 0.25 mg heavy metal mixtures, group III received (i.p.) TS extract of dose 40 mg for seven days, and group IV served as the protected group pretreated with TS extract for seven days as a protection dose, and then treated with the heavy metal-mixture. The main pathological changes within the liver after heavy-metal mixtures administrations marked hepatic damage evidenced by foci of lobular necrosis with neutrophilic infiltration, adjacent to dysplastic hepatocytes. ALT and AST measurements show a significant increase in group II by 46.20% and 45.12%, respectively. Total protein, elevated by about 38.9% in induction group compared to the −ve control group, in contrast to albumin, decreased as a consequence of metal administration with significant elevation on bilirubin level. The results prove that TS extract possesses a hepatoprotective property due to its proven antioxidant and free-radical scavenging properties.

Environmental Pathology

Humans are constantly exposed to hazardous pollutants in the environment—for example, in the air, water, soil, rocks, diet, or workplace. Trace metals are important in environmental pathology because of the wide range of toxic reactions and their potential adverse effects on the physiological function of organ systems. Exposures to toxic trace metals have been the subject of numerous environmental and geochemical investigations, and many studies have been published on the acute and/or chronic effects of high-level exposures to these types of agents; however, much fewer data are available concerning the health effects of low-dose chronic exposure to many trace metals. Chronic low-dose exposures to toxic elements such as cadmium and arsenic have been shown to cause these metals to accumulate in tissues over time, leading to multiple adverse effects in exposed individuals.

Interaction of mineral salts with the skin: a literature survey

There is growing scientific evidence that the health, well-being and the attractiveness of the skin are strongly influenced by nutrition. Consumers recognize this and have supported the creation of a global cosmeceuticals market estimated in 2010 at $27.2 billion. Early in 2011, the US Department of Health and Human Services and Department of Agriculture issued the Dietary Guidelines for Americans, 2010. Twelve vitamins and nine minerals were recognized as essential. The minerals include calcium, copper, iron, magnesium, phosphorus, selenium, zinc, potassium and sodium. Although the topical benefits of several minerals such as zinc, magnesium and iron are recognized and, in some cases, approved by the FDA, the topical benefits of the others to the skin are largely unexplored and unexploited. This review attempts to summarize what has been published in the literature on the interactions of the eight of the nine essential elements with the skin.

[Environmental exposure to silver and its health effects]

Silver (Ag) possesses a well-known antibacterial activity and has been used for medical treatment and cosmetics such as wound dressing and deodorant powders. Occupational Safety and Health Administration (OSHA) and Mine Safety and Health Administration (MSHA) proposed that the permissible exposure limit (PEL) for both metallic and most soluble Ag compounds should be 0.01 mg/m3. Argyria and argyrosis are known to be caused by deposition of insoluble Ag in the dermis and cornea/conjunctiva. However, the metabolic behavior and biological roles of Ag have not been well characterized in mammals. Ag can be absorbed into the systemic circulation from drinking water, and also through parenteral routes such as inhalation and dermal exposure. Experimental studies have demonstrated that Ag+ induces and binds to metallothionein I and II (MTs), which are cysteine-rich proteins, in cells. MTs are major cytoplasmic metal binding proteins and thereby reduce cellular damage caused by toxic heavy metals including Ag. Profiles of Ag distribution in MTs and other Ag-binding proteins can be determined using high performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS). This technique directly provides information on the intracellular behavior of Ag, which is important for elucidating the mechanism underlying Ag toxicity. Silver nanoparticles (AgNPs) are also commercially used mainly as antimicrobial agents. Despite the widespread use of AgNPs, relatively few studies have been undertaken to evaluate the health effects of AgNP exposure. In the present paper, we discuss the absorption, toxicodynamics, and metabolism of both Ag and AgNPs in mammals and their health effects.

Literature review of the role of hydroxyl radicals in chemically-induced mutagenicity and carcinogenicity for the risk assessment of a disinfection system utilizing photolysis of hydrogen peroxide

We have developed a new disinfection system for oral hygiene, proving that hydroxyl radicals generated by the photolysis of 1 M hydrogen peroxide could effectively kill oral pathogenic microorganisms. Prior to any clinical testing, the safety of the system especially in terms of the risk of carcinogenicity is examined by reviewing the literature. Previous studies have investigated indirectly the kinds of reactive oxygen species involved in some sort of chemically-induced mutagenicity in vitro by using reactive oxygen species scavengers, suggesting the possible involvement of hydroxyl radicals. Similarly, possible involvement of hydroxyl radicals in some sort of chemically-induced carcinogenicity has been proposed. Notably, it is suggested that the hydroxyl radical can play a role in heavy metal-induced carcinogenicity that requires chronic exposure to the carcinogen. In these cases, hydroxyl radicals produced by Fenton-like reactions may be involved in the carcinogenicity. Meanwhile, potential advantages have been reported on the use of the hydroxyl radical, being included in host immune defense by polymorphonuclear leukocytes, and medical applications such as for cancer treatment and antibiotics. From these, we conclude that there would seem to be little to no risk in using the hydroxyl radical as a disinfectant for short-term treatment of the oral cavity.

Nutrition and wound healing

Continued research and development in the field of wound healing holds the potential to affect both quality of life and incidence of mortality. For the health care provider to promote successful wound healing, an understanding of the function of nutrients in inflammation and tissue growth is helpful. The intent of this paper is to discuss the metabolic and cellular pathways crucial to wound healing and identify appropriate nutritional interventions and clinical applications.

Candidate single nucleotide polymorphism markers for arsenic responsiveness of protein targets

Arsenic is a toxic metalloid that causes skin cancer and binds to cysteine residues—a property that could be used to infer arsenic responsiveness of a target protein. Non-synonymous Single Nucleotide Polymorphisms (nsSNPs) result in amino acid substitutions and may alter arsenic binding with cysteine residues. Thus, the objective of this investigation was to identify and analyze nsSNPs that lead to substitutions to or from cysteine residues as an indication of increased or decreased arsenic responsiveness. We hypothesize that integration of data on molecular impacts of nsSNPs and arsenic-gene relationships will identify nsSNPs that could serve as arsenic responsiveness markers. We have analyzed functional and structural impacts data for 5,811 nsSNPs linked to 1,224 arsenic-annotated genes. In addition to the identified candidate nsSNPs for increased or reduced arsenic responsiveness, we observed i) a nsSNP that results in the breakage of a disulfide bond, as candidate marker for reduced arsenic responsiveness of KLK7, a secreted serine protease participate in normal shedding of the skin; and ii) 6 pairs of vicinal cysteines in KLK7 protein that could be binding sites for arsenic. In summary, our analysis identified non-synonymous SNPs that could be used to evaluate responsiveness of a protein target to arsenic. In particular, an epidermal expressed serine protease with crucial function in normal skin physiology was prioritized on the basis of abundance of vicinal cysteines for further research on arsenic-induced keratinocyte carcinogenesis.

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.

c-Jun/AP-1 pathway-mediated cyclin D1 expression participates in low dose arsenite-induced transformation in mouse epidermal JB6 Cl41 cells

Arsenic is a well-documented human carcinogen associated with skin carcinogenesis. Our previous work reveals that arsenite exposure is able to induce cell transformation in mouse epidermal cell JB6 Cl41 through the activation of ERK, rather than JNK pathway. Our current studies further evaluate downstream pathway in low dose arsenite-induced cell transformation in JB6 Cl41 cells. Our results showed that treatment of cells with low dose arsenite induced activation of c-Jun/AP-1 pathway, and ectopic expression of dominant negative mutant of c-Jun (TAM67) blocked arsenite-induced transformation. Furthermore, our data indicated that cyclin D1 was an important downstream molecule involved in c-Jun/AP-1-mediated cell transformation upon low dose arsenite exposure, because inhibition of cyclin D1 expression by its specific siRNA in the JB6 Cl41 cells resulted in impairment of anchorage-independent growth of cells induced by low dose arsenite. Collectively, our results demonstrate that c-Jun/AP-1-mediated cyclin D1 expression is at least one of the key events implicated in cell transformation upon low dose arsenite exposure.

Critical Observations on the Neurotoxicity of Silver

Silver is a xenobiotic element with no recognized trace metal value in the human body. It is absorbed into the body through the lungs, gastrointestinal tract, mucus membranes of the urinogenital tract, and through the skin, mainly in the form of silver protein complexes. Although silver is metabolized throughout the soft tissues, available evidence from experimental animal studies and human clinical reports has failed to unequivocally establish that it enters tissues of the central nervous system or is a cause of neurotoxic damage. Argyria characterized by deposition of particles of silver sulfide or silver selenide is the principle contraindication for using silver in medical devices or occupationally. This presents discoloration of the skin but is not regarded as a health risk or manifestation of toxicity. No evidence is available to demonstrate the toxic risk of silver to the peripheral nervous system, although silver sulfide deposits have been identified in the region of cutaneous nerves. Transitory silver sulfide deposits seen in the tissues of the blood-brain and blood-CSF barriers are mostly lysosomally bound or deposited on basement membranes or collagen without toxic effect. Silver is mostly excreted from the body in the urine and feces. Further research is indicated to evaluate the role of metal binding proteins including metallothioneins as cytoprotectants for neurological tissue.

Sodium arsenite affects Na+ transport in the isolated skin of the toad Pleurodema thaul

Arsenic, applied as sodium arsenite (As(III)) to either inner or outer surfaces of the isolated toad skin, dose-dependently decreased the short-circuit current (Isc), potential difference (PD) and sodium conductance (G(Na)) in the concentration range 1-1000 microM, with effects often lasting over 3 h. Maximal inhibitory effect was over 90% with an IC(50) of about 34 microM. Applied during amiloride block, As(III) did not change this effect. However, an increase in electric parameters was noted during the initial 30 min in 22 experiments, indicating a possible translocation of cytosolic protein kinase C (PKC) to the membrane within 15 min, thus stimulating sodium transport; this is followed by a progressive inhibition of kinase activity. Comparative effects of amiloride (8 microM), As(III) (100 microM, outer surface) and noradrenaline (NA, 10 microM, inner surface) showed a significant increase in the stimulatory effect of NA on the electric parameters, which could be the result of arsenite clustering of cell surface receptors and activation of ensuing cellular signal transduction pathways. Ouabain 5 microM, followed by As(III) 100 microM, also stimulated the skin response to NA (10 microM), although the duration of the two phases of the response was markedly shortened. The exact mechanism is still in doubt: however, As(III) increases cerebral metabolites of NA and ouabain can increase NA efflux from tissue slices. The amiloride test, performed with As(III) in the outer surface, confirmed significant decrease in all the parameters: the driving force (E(Na)), sodium conductance (G(Na)), and importantly, shunt conductance (G(sh)), due to the known fact that arsenic inhibits gap junctional intercellular communication.

Arsenic-induced genotoxic and cytotoxic effects in human keratinocytes, melanocytes and dendritic cells

Arsenical keratosis and skin cancer are among the most common health effects associated with acute and chronic exposures to arsenic. This study examines the acute and chronic dose-responses of arsenic in established human cell lines using keratinocytes (HaCaT), melanocytes (CRL1675) and dendritic cells (THP-1 + A23187). Chronic conditions were established by treating the three cell lines with at least 8 passages in 0.2 microg/mL arsenic trioxide. Cytotoxicity was assessed using the fluorescein diacetate assay after 72 hrs of exposure. Single cell gel electrophoresis (Comet assay) was used to measure DNA damage. Acute exposure to arsenic had LD10 and LD25 values of 0.38 microg/mL and 3.0 microg/mL for keratinocytes; 0.19 microg/mL and 0.38 microg/mL for melanocytes; and 0.38 microg/mL and 0.75 microg/mL for dendritic cells. Cytotoxicity assays for chronically exposed cells resulted in LD10, and LD25 values of 0.4 microg/mL and 0.8 microg/mL for keratinocytes; 0.10 microg/mL and 0.20 microg/mL for melanocytes; and 0.10 microg/mL and 1.0 microg/mL for dendritic cells. The Comet assay showed that arsenic was highly genotoxic to the three cell lines. No significant differences (p > 0.05) in DNA cleavage were observed between acute and chronic exposures. In acute exposure arsenic genotoxicity was more severe with dendritic cells while melanocytes were more sensitive to arsenic cytotoxicity. Similarly, chronically exposed dendritic cells showed the maximum genotoxic damage while melanocytes were more sensitive to arsenic cytotoxicity. In conclusion, this research shows that arsenic is dermatotoxic, showing a high degree of genotoxicity and cytotoxicity to skin cells.

Heat shock protein 70 as an indicator of early lung injury caused by exposure to arsenic

Heat shock proteins (HSPs) are a family of highly conserved proteins that are induced by a number of stresses including toxic metals. Heat shock proteins expression has been reported to be an early and sensitive biomarker of cell stress. Arsenic is a naturally occurring metal that exists widely in the environment and is used in several industries. Exposure to arsenic is associated with the development of pulmonary cancers. We monitored changes in Hsp70 and markers of oxidative injury induced by arsenic in human pulmonary epithelial cells (BEAS-2B). Hsp70 protein, mRNA and reactive oxygen species (ROS) generation were measured after exposing cells to arsenic as markers of injury. Hsp70 protein expression showed significant 7.9-fold and 31.5-fold increase using Western blotting and ELISA assay, respectively, at a 50 microM As(III) with a 12 h exposure and an 12 h recovery time. Hsp70A and Hsp70B mRNA expression showed a two-fold increase and Hsp70C mRNA expression showed a six-fold increase. As(III)-induced Hsp70 protein expression was inhibited significantly by catalase and NAC, indicating mediation of ROS in Hsp70 expression. Intracellular glutathione (GSH) was significantly depleted by As(III) exposure. Lipid peroxidation by-product, 8-isoprostane, was increased six-fold at 24 h exposure to 20 microM As(III). Electron spin resonance and confocal microscope studies also showed As(III)-stimulated ROS generation. These results suggest that cellular injury by arsenic is mediated through ROS generation resulting in the expression of Hsp70. It is possible that Hsp70 may prove to be a sensitive biomarker for arsenic exposure with other markers of oxidative stress in human serum.