Metal and metalloid content, bioavailability and sorption processes in glitter and raw glitter materials and associations with human and ecological risk concerns.

BACKGROUND: Microplastics comprise a significant group of emerging environmental contaminants with the capacity to adsorb several contaminants. These, in turn, undergo bioaccumulation and biomagnification processes throughout aquatic trophic chains. METHODS: Glitter, a microplastic powder composed of a combination of polymers, and raw glitter materials were investigated herein concerning metal and metalloid content, bioavailability, and sorption processes by inductively coupled plasma mass spectrometry (ICP-MS). RESULTS: Metal and metalloid concentrations were higher in glitter than in raw glitter materials, but all were below the limits established by the Brazilian National Health Surveillance Agency. Elements present in glitter originate mainly from pigments and, thus, depend on glitter color. The bioavailability of the determined elements concerning human skin was assessed. Low desorbed concentrations in solution indicate that glitter does not represent a health risk through dermal contact concerning metal and metalloid contamination. However, several elements were shown to undergo significant desorption and adsorption processes. CONCLUSION: The findings reported herein indicate seemingly low human health risks from dermal glitter contact but reinforce glitter risks as aquatic environment metal and metalloid transport vectors.

Mammalian sphingoid bases: Biophysical, physiological and pathological properties.

Sphingoid bases encompass a group of long chain amino alcohols which form the essential structure of sphingolipids. Over the last years, these amphiphilic molecules were moving more and more into the focus of biomedical research due to their role as bioactive molecules. In fact, free sphingoid bases interact with specific receptors and target molecules and have been associated with numerous biological and physiological processes. In addition, they can modulate the biophysical properties of biological membranes. Several human diseases are related to pathological changes in the structure and metabolism of sphingoid bases. Yet, the mechanisms underlying their biological and pathophysiological actions remain elusive. Within this review, we aimed to summarize the current knowledge on the biochemical and biophysical properties of the most common sphingoid bases and to discuss their importance in health and disease.

Mammalian sphingoid bases: Biophysical, physiological and pathological properties.

Sphingoid bases encompass a group of long chain amino alcohols which form the essential structure of sphingolipids. Over the last years, these amphiphilic molecules were moving more and more into the focus of biomedical research due to their role as bioactive molecules. In fact, free sphingoid bases interact with specific receptors and target molecules, and have been associated with numerous biological and physiological processes. In addition, they can modulate the biophysical properties of biological membranes. Several human diseases are related to pathological changes in the structure and metabolism of sphingoid bases. Yet, the mechanisms underlying their biological and pathophysiological actions remain elusive. Within this review, we aimed to summarize the current knowledge on the biochemical and biophysical properties of the most common sphingoid bases and to discuss their importance in health and disease.

The molecular mechanism of Nystatin action is dependent on the membrane biophysical properties and lipid composition.

Nystatin (Nys) is a pore forming broad-spectrum and efficient antifungal drug with significant toxicity in mammalian organisms. In order to develop a non-toxic and more effective Nys formulation, its molecular mechanism of action at the cell membrane needs to be better understood. It is widely accepted that Nys activity and toxicity depend on the presence and type of membrane sterols. Taking advantage of multiple biophysical methodologies, we now show that the formation and stabilization of Nys aqueous pores, which are associated with Nys cytotoxicity, occur in the absence of membrane sterols. Our results suggest that the Nys mechanism of action is driven by the presence of highly ordered membrane domains capable of stabilizing the Nys oligomers. Moreover, Nys pore formation is accompanied by strong Nys-induced membrane reorganization that depends on membrane lipid composition and seems to underlie the Nys cytotoxic effect. Accordingly, in membranes enriched in a gel-phase forming phospholipid, Nys incorporates within the phospholipid-enriched gel domains, where it forms pores able to expand the gel domains. In contrast, in membranes enriched in gel domain forming sphingolipids, Nys-induced pore formation occurs through the destabilization of the gel phase. These results show that the Nys mechanism of action is complex and not only dependent on membrane sterols, and provide further insight into the molecular details governing Nys activity and toxicity.

Copper(I) complexes with phosphine derived from sparfloxacin. Part II: a first insight into the cytotoxic action mode.

In this paper we present a first insight into the cytotoxic action mode of copper(I) iodide or copper(I) thiocyanate complexes with a phosphine derivative of sparfloxacin (a 3rd generation fluoroquinolone antibiotic agent) and 2,9-dimethyl-1,10-phenanthroline or 2,2'-biquinoline as auxiliary ligands. The in vitro cytotoxic activity of the new complexes was tested against two cancer cell lines (CT26--mouse colon carcinoma and A549--human lung adenocarcinoma). An ICP-MS study revealed a marked time-dependent intracellular copper accumulation of the tested compounds. In addition, confocal microscopy imaging showed accumulation of the complexes inside whole cells and their emission of blue light. The complexes generate reactive oxygen species in the cancer cells, which was examined by using two different fluorescent probes. Moreover, (I) DNA intercalation studied by luminescence spectroscopy, circular dichroism and molecular docking, and (II) plasmid DNA damage also demonstrate their significant cytotoxicity. All these observed biological effects contribute to the induction of apoptosis, observed at a great predominance.

Phospholipid/cholesterol/decanethiol mixtures for direct assembly of immunosensing interfaces.

In this work, a simple yet robust method to prepare lipid-based biosensing interfaces on gold using common lipids (a phospholipid and cholesterol) and an alkanethiol is reported. The lipids were carefully chosen to tailor the biophysical properties of the bilayer. The simplicity of the method relies on the incorporation of a small percentage of decanethiol in the lipid vesicles for a direct formation of a thiol-linked supported lipid bilayer, which is advantageous in several respects. It prevents the use of specially synthesized thiolipids and preserves the natural fluidity and dynamics of the lipids. As a consequence the whole arrangement is extremely stable regarding ionic strength changes and solution flow during surface plasmon resonance experiments. Moreover, we show that this interface is very effective on suppressing the nonspecific adsorption of proteins on the surface, and enables the covalent attachment of the recognition antibody. The subsequent detection of specific interaction toward antigen was monitored in real-time by SPR and confirmed by ellipsometric measurements. This lipid-based biosensing platform is versatile and can be adapted to the biorecognition reaction of interest.

Anne Frank's headache.

There are a significant number of famous people who suffered from frequent headaches during their lifetime while also exerting an influence of some kind on politics or the course of history. One such person was Anneliese Marie Frank, the German-born Jewish teenager better known as Anne Frank, who was forced into hiding during World War II. When she turned 13, she received a diary as a present, named it 'Kitty' and started to record her experiences and feelings. She kept the diary during her period in hiding, describing her daily life, including the feeling of isolation, her fear of being discovered, her admiration for her father and her opinion about women's role in society, as well as the discovery of her own sexuality. She sometimes reported a headache that disturbed her tremendously. The 'bad' to 'terrifying' and 'pounding' headache attacks, which were accompanied by vomiting and during which she felt like screaming to be left alone, matched the International Headache Society criteria for probable migraine, whereas the 'more frequent headaches' described by Anne's father are more likely to have been tension-type headaches than headaches secondary to ocular or other disorders.

Interaction of alpha-melanocyte stimulating hormone with binary phospholipid membranes: structural changes and relevance of phase behavior.

The interaction of alpha-melanocyte stimulating hormone (alpha-MSH) with negatively charged binary membrane systems composed of either 1,2-dimyristoyl-sn-glycero-3-phosphocholine/1,2-dimyristoyl-sn-glycero-3-[phospho-rac-(1-glycerol)], (DMPC/DMPG) or DMPC/1,2-dimyristoyl-sn-glycero-3-phosphate (DMPC/DMPA), both at a 3:1 ratio, was studied using complementary techniques (differential scanning calorimetry, infrared and ultraviolet absorption spectroscopy, and steady-state and time-resolved fluorescence). The peptide structure in buffer, at medium to high concentrations, is a mixture of aggregated beta-strands and random coil, and upon increasing the temperature the random coil configuration becomes predominant. At low concentrations (micromolar) there are essentially no aggregates. When in interaction with the lipidic systems this transition is prevented and the peptide is stabilized in a specific conformation different from the one in solution. The incorporation of alpha-MSH into phosphatidic acid-containing systems produced a significant alteration of the calorimetric data. Lateral heterogeneity can be induced by the peptide in the DMPA-containing mixture, at variance with the one of DMPG. In addition, the lipid/water partition coefficient for the peptide in the presence of DMPC/DMPA is greater in the gel phase as compared to the fluid phase. From the high values of limiting anisotropies it can be concluded that the peptide presents a very reduced rotational dynamics when in interaction with the lipids, pointing out to a strong interaction. Overall, these results show that the structure and stability of alpha-MSH in a negatively charged membrane environment are substantially different from those of the peptide in solution, being stabilized in a specific conformation that could be important to eliciting its biological activity.