In-depth characterization revealed polymer type and chemical content specific effects of microplastic on Dreissena bugensis

In aquatic ecosystems, filter feeders like mussels are particularly vulnerable to microplastics (MP). However, little is known about how the polymer type and the associated properties (like additives or remaining monomers) of MP impact organisms, as the predominant type of MP used for effect studies on the organismic level are micron grade polystyrene spheres, without considering their chemical composition. Therefore, we exposed the freshwater mussel Dreissena bugensis (D. bugensis) to in-depth characterized fragments in the same concentration and size range (20-120 µm): recycled polyethylene terephthalate from drinking bottles, polyamide, polystyrene, polylactic acid, and mussel shell fragments as natural particle control. Real-time valvometry, used to study behavioral responses via the movement of the mussels' valves, showed that mussels cannot distinguish between natural and MP particles, and therefore do not cease their filtration, as when exposed to dissolved pollutants. This unintentional ingestion led to polymer type-dependent adverse effects (activity of antioxidant enzymes and proteomic alterations), related to chemicals and residual monomers found in MP. Overall, recycled PET elicited the strongest negative effects, likely caused by anthranilamide, anthranilonitrile and butylated hydroxytoluene, contained in the fragments, which are toxic to aquatic organisms. As PET is among the most abundant MP in the environment, sublethal effects may gradually manifest at the population level, leading to irreversible ecosystem changes.

Sensitive skin: an epidemiological study

BACKGROUND

There is a growing awareness that some individuals exhibit heightened skin sensitivity, particularly on the face, and have a high incidence of adverse reactions to cosmetics and toiletries.

OBJECTIVES

To carry out an epidemiological study to assess the prevalence of sensitive skin and cosmetic-related adverse events in a U.K. population, and to examine possible factors that may be associated with sensitive skin.

METHODS

Self-assessment questionnaires were sent out to 3300 women and 500 men, randomly selected, who were over the age of 18 years and lived within a 10-mile radius of High Wycombe (Bucks.). Fifty non-responder women were also questioned by telephone to ensure that the postal responders were representative of the population as a whole.

RESULTS

The response rates were 62% for women and 52% for men, with the incidence of self-reported skin sensitivity being 51.4% and 38.2%, respectively. Ten per cent of women and 5.8% of men described themselves as having very sensitive skin. Fifty-seven per cent of women and 31.4% of men had experienced an adverse reaction to a personal product at some stage in their lives, with 23% of women and 13.8% of men having had a problem in the last 12 months. Among the women, symptoms of cosmetic-induced subjective sensory skin discomfort (burning, stinging, itching etc.) occurred more commonly in the sensitive skin cohort (53%) than in those who regarded themselves as non-sensitive (17%). An atopic diathesis in women did not appear to be a predictive factor for sensitive skin, the incidence of self-perceived sensitive skin being equivalent for atopics (49%) and non-atopics (51%). Furthermore, some 34% of atopic women described themselves as being non-sensitive. Nevertheless, the incidence of atopy was higher among the women in the sensitive skin group (49%) than among those in the non-sensitive group (27%). Dry skin and a predilection for blushing/flushing were associated factors for sensitive skin.

CONCLUSIONS

Our survey indicates that sensitive facial skin is a common problem for women and men in the U.K. and points to the need for the development of personal products designed for this skin phenotype.

Reduced levels of glutathione S-transferases in patch test reactions to dithranol and sodium lauryl sulphate as demonstrated by quantitative immunocytochemistry: evidence for oxidative stress in acute irritant contact dermatitis

There is increasing evidence that oxidative stress plays a role in the pathogenesis of acute irritant contact dermatitis. As part of on-going studies into the effect of irritant chemicals on the anti-oxidant enzyme systems in the skin, we have examined the changing levels of two classes of glutathione S-transferase in patch test reactions to dithranol and sodium lauryl sulphate, using quantitative immunocytochemistry. Although no changes were evident after 6 hrs, significant reductions in the density of staining for glutathione S-transferase alpha were seen with both irritants after 48 hrs and 96 hrs. Glutathione S-transferase pi levels were reduced to a lesser degree, reaching significance for dithranol at the 96 hrs time point only, and for sodium lauryl sulphate at 48 hrs only. The results support the hypothesis that oxidative stress plays a role in chemically-induced inflammation, not only in the case of irritants such as dithranol which are known to directly generate reactive oxygen species, but also with chemicals not generally associated with free radical generation.

Combination therapy with nicotinamide and tetracyclines for cicatricial pemphigoid: further support for its efficacy

We have previously reported the reduction of cicatricial pemphigoid orodynia with minocycline. Tetracycline combined with high dose nicotinamide has also been beneficial in a number of cutaneous immunological disorders. We now report a series of eight cases in whom further subjective or clinical improvement accrued in five, after the addition of high dose (2.5 or 3 g) nicotinamide to minocycline; however, one of these then discontinued the nicotinamide because of headache and nausea, another was withdrawn from the study because of progressive upper respiratory tract mucosal involvement, and two were changed from minocycline to tetracycline because they developed minocycline-induced hyperpigmentation.

Clinical morphology of sodium lauryl sulfate (SLS) and nonanoic acid (NAA) irritant patch test reactions at 48 h and 96 h in 152 subjects

In this study of 152 women, comparison of patch test responses between 2 irritants over 96 h at 2 symmetrical anatomical sites is studied. 2 irritants, each at 4 different concentrations (nonanoic acid (NAA) 80%, 40%, 20%, 10%; sodium lauryl sulfate (SLS) 3%, 2%, 1% and 0.5%) and using propan-1ol and 'water for injection' as the respective controls, were placed as 15 microl aliquots, soaked onto filter paper discs in Finn Chambers, on the volunteer's left and right lower back. The patches were removed at 47, and read at 48 and 96 h. Irritant reactions were evaluated for erythema and surface changes by degree and area affected. Statistical analysis of the results showed that erythema decreased with time for all concentrations of NAA, and at higher concentrations for SLS. Surface changes increased with time for SLS and at higher concentrations of NAA. There was no statistically significant difference comparing left and right sides. Traditionally in patch testing, reactions which fade after 48 h have been regarded as irritant rather than allergic. This study refutes that assumption. Data from our left to right comparisons, made in the same individuals at the same time, show that irritant reactions may be more reproducible than previously appreciated.

Keratin 17 is expressed during the course of SLS-induced irritant contact dermatitis, but unlike keratin 16, the degree of expression is unrelated to the density of dividing keratinocytes

The aims of this study were to utilize quantitative immunocytochemical techniques to determine the densities of keratin 16 (K16) and keratin 17 (K17) expressed by keratinocytes during the course of acute patch test reactions to sodium lauryl sulfate (SLS), and to relate these to the proliferative state of the epidermis, as assessed by Ki-67 immunolabelling. Significantly increased numbers of dividing keratinocytes were present in 48h and 96h reactions, concurrent with high levels of expression of K16 and more moderate expression of K17. Statistical analysis indicated a good correlation between K16 expression and the density of Ki-67+ keratinocytes present in the epidermis (r=0.843). This was not the case for K17 (r=0.396). The results demonstrate that both K16 and K17 expression are features of acute irritant contact dermatitis reactions, but suggest that the factors which influence and control their expression differ.

Immunocytochemical demonstration of reduced Cu,Zn-superoxide dismutase levels following topical application of dithranol and sodium lauryl sulphate: an indication of the role of oxidative stress in acute irritant contact dermatitis

Oxidative stress is known to be implicated in the inflammation induced by the anti-psoriatic irritant, dithranol. In this study, we wished to investigate whether this is reflected in the levels of the antioxidant enzyme, Cu,Zn-superoxide dismutase, as detected by quantitative immunocytochemistry, and whether similar changes also occur following exposure to an irritant not normally associated with reactive oxygen species generation, namely sodium lauryl sulphate. Analysis of biopsies from patch test sites revealed that significant reductions in the epidermal levels of Cu,Zn-superoxide dismutase were induced by both dithranol and sodium lauryl sulphate, although the time course of diminished activity was different for each irritant. Our findings suggest that oxidative stress plays a general role in the pathophysiology of acute irritant contact dermatitis.