Exploring the Lipid World Hypothesis: A Novel Scenario of Self-Sustained Darwinian Evolution of the Liposomes

According to the Lipid World hypothesis, life on Earth originated with the emergence of amphiphilic assemblies in the form of lipid micelles and vesicles (liposomes). However, the mechanism of appearance of the information molecules (ribozymes/RNA) accompanying that process, considered obligatory for Darwinian evolution, is unclear. We propose a novel scenario of self-sustained Darwinian evolution of the liposomes driven by ever-present natural phenomena: solar UV radiation, day/night cycle, gravity, and the formation of liposomes in an aqueous media. The central tenet of this scenario is the liposomes' encapsulation of the heavy solutes, followed by their gravitational submerging in the water. The submerged liposomes, being protected from the damaging UV radiation, acquire the longevity necessary for autocatalytic replication of amphiphiles, their mutation, and the selection of those amphiphilic assemblies that provide the greatest membrane stability. These two sets of adaptive compositional information (heavy content and amphiphilic assemblies design) generate a population of liposomes with self-replication/reproduction properties, which are amendable to mutation, inheritance, and selection, thereby establishing Darwinian progression. Temporary and spatial expansion of this liposomal population will provide the basis for the next evolutionary step-a transition of accidentally entrapped RNA precursor molecules into complex functional molecules, such as ribozymes/RNA.

Development and characterisation of an irradiation device for biomedical studies covering the solar spectrum with individual regulated spectral bands

To understand the importance of terrestrial solar exposure on human skin, not only individual spectral components need to be considered in biomedical studies, but also the relevance of the combined action profile of the complete solar spectrum (cSS) must be established. We therefore developed a novel irradiation device that combines the emission of four individual lamps (UVB, UVA, VIS and nIR) to achieve exposure from 280 to 1400 nm with individual controllable lamps. The integrated irradiance of each spectral band is similar to the solar spectrum. The lamps can be utilised individually or in any desired combination. Here we present the design, realisation, and validation of this irradiation device as well as biological results on cellular metabolism (MTT assay), cell cycle alterations, and clonogenic growth in HaCaT cells after exposures to the individual spectral bands as well as their simultaneous combinations. Thereby, we demonstrate that UVB combined with UVA is the main determinant for the metabolic activity within cSS. Also, UVB-dependent effects dominate cell cycle regulation in cSS, whilst UVA and nIR have little influence. Lastly, also clonogenic growth is dominated by the UVB action profile in cSS, despite nIR showing modulatory activity when applied in combination with UVB. Together, this highlights the regulatory influence of the different spectral bands on the three biological endpoints and demonstrates their modulation when being part of the complete solar spectrum.

A Case Study of UV Exposure Risk in Sydney during the 2019/2020 New South Wales Bushfires

During summer 2019/2020, Sydney, Australia, experienced several days of extreme air pollution and low visibility due to bushfires. This research presents a case study that investigates the erythemal UV irradiance and resulting one-hour erythemal and 8-hour actinic exposures during the worst of these days. Air quality, meteorological and UV data used in the analysis was readily available online or by request from governmental agencies. Analysis showed that even for the lowest visibility day (which had a minimum visibility of less than a kilometre) on 10^th December 2019, there was a cumulative one-hour erythemal UV exposure of over 4 SED (Standard Erythema Dose) and a cumulative 8-hour exposure of 17 SED by the late afternoon. The one-hour exposure exceeded that for a minimum erythemal dose. Even on this extremely hazy day, these cumulative exposures are enough to exceed the recommended daily exposure limit for actinic exposures weighted with the health sensitivity spectrum for the skin and eyes set by the International Commission of Non-Ionizing Radiation Protection.

Topical hypochlorous acid (HOCl) blocks inflammatory gene expression and tumorigenic progression in UV-exposed SKH-1 high risk mouse skin

Hypochlorous acid (HOCl) is the active oxidizing principle underlying drinking water disinfection, also delivered by numerous skin disinfectants and released by standard swimming pool chemicals used on a global scale, a topic of particular relevance in the context of the ongoing COVID-19 pandemic. However, the cutaneous consequences of human exposure to HOCl remain largely unknown, posing a major public health concern. Here, for the first time, we have profiled the HOCl-induced stress response in reconstructed human epidermis and SKH-1 hairless mouse skin. In addition, we have investigated the molecular consequences of solar simulated ultraviolet (UV) radiation and HOCl combinations, a procedure mimicking co-exposure experienced for example by recreational swimmers exposed to both HOCl (pool disinfectant) and UV (solar radiation). First, gene expression elicited by acute topical HOCl exposure was profiled in organotypic human reconstructed epidermis. Next, co-exposure studies (combining topical HOCl and UV) performed in SKH-1 hairless mouse skin revealed that the HOCl-induced cutaneous stress response blocks redox and inflammatory gene expression elicited by subsequent acute UV exposure (Nos2, Ptgs2, Hmox1, Srxn1), a finding consistent with emerging clinical evidence in support of a therapeutic role of topical HOCl formulations for the suppression of inflammatory skin conditions (e.g. atopic dermatitis, psoriasis). Likewise, in AP-1 transgenic SKH-1 luciferase-reporter mice, topical HOCl suppressed UV-induced inflammatory signaling assessed by bioluminescent imaging and gene expression analysis. In the SKH-1 high-risk mouse model of UV-induced human keratinocytic skin cancer, topical HOCl blocked tumorigenic progression and inflammatory gene expression (Ptgs2, Il19, Tlr4), confirmed by immunohistochemical analysis including 3-chloro-tyrosine-epitopes. These data illuminate the molecular consequences of HOCl-exposure in cutaneous organotypic and murine models assessing inflammatory gene expression and modulation of UV-induced carcinogenesis. If translatable to human skin these observations provide novel insights on molecular consequences of chlorination stress relevant to environmental exposure and therapeutic intervention.

COVID-19 pandemic: environmental and social factors influencing the spread of SARS-CoV-2 in São Paulo, Brazil

The new coronavirus SARS-CoV-2 has infected more than 14 million people worldwide so far. Brazil is currently the second leading country in number of cases of COVID-19, while São Paulo state accounts for 20% of total confirmed cases in Brazil. The aim of this study was to assess environmental and social factors influencing the spread of SARS-CoV-2 in the expanded metropolitan area of São Paulo, Brazil. Firstly, a spatial analysis was conducted to provide insights into the spread of COVID-19 within the expanded metropolitan area. Moreover, Spearman correlation test and sensitivity analysis were performed to assess social indicators and environmental conditions which possibly influence the incidence of COVID-19. Our results reveal that the spread of COVID-19 from the capital city São Paulo-its epicenter in Brazil-is directly associated with the availability of highways within the expanded metropolitan area of São Paulo. As for social aspects, COVID-19 infection rate was found to be both positively correlated with population density, and negatively correlated with social isolation rate, hence indicating that social distancing has been effective in reducing the COVID-19 transmission. Finally, COVID-19 infection rate was found to be inversely correlated with both temperature and UV radiation. Together with recent literature our study suggests that the UV radiation provided by sunlight might contribute to depletion of SARS-CoV-2 infectivity.

Exposure to solar UV radiation in outdoor construction workers using personal dosimetry

Occupational exposure to solar UV radiation (SUVR), a Group 1 carcinogen according to the IARC classification is at high exposure levels in outdoor construction workers, usually above the suggested occupational limits. Furthermore, there are no regulations related to this exposure in the EU, except for the artificial UVR. Also, the use of the ICNIRP exposure guideline in an outdoor setting poses problems of adequate dose assessment. In this context, the main purpose of the study was to perform direct measurements of the SUVR dose in outdoor workers from the construction sector, using individual SUVR dosimeters (GENESIS-UV system), for a period of 7 months, from April to October, in a prospective, observational study in two groups of 10 outdoor workers in Romania, located at two different geographic sites. In term of cumulative standard erythema dose (SED), our study population of outdoor construction workers received high levels of solar UV radiation, ranging from 165 SED to 453 SED during 7 months of occupational activity, from April to October. Our results, ranging from 1.28 SED (standard erythema dose) per day to 6.4 SED per day pose an alarm signal to the national and European health authorities to take preventive action for outdoor workers, as the ICNIRP suggested limit value of 1.33 SED for mean daily erythemal UV exposure is vastly exceeded. We suggest that personal dosimetry for SUVR, from simple devices to complex systems as GENESIS-UV should be regularly and mandatory used in outdoor workers, similarly to the usage of personal dosimetry in occupational exposure to ionizing radiations, which could be included in European and national legislation to reduce both, the level of exposure and the detrimental effects on outdoor workers' health.

[UV radiation in Germany: influences of ozone depletion and climate change and measures to protect the population]

Ultraviolet radiation (UV radiation) can lead to numerous skin and eye diseases, both immediately and later in life. The most serious consequence is skin cancer. The risk of skin cancer increases, among other things, with increasing UV irradiance and/or with increasing outdoor exposure times. Due to the fact that UV radiation is carcinogenic, protection of the population against harmful UV exposure is an important radiation protection and health objective.In Germany, ozone depletion and climate change can also influence the UV irradiance and outdoor exposure times to such an extent that the UV exposure of the population and thus the skin cancer risk can increase. This is why protection against harmful UV exposure is even more important. Since ozone depletion and climate change can further increase the UV exposure of humans, protection against high UV exposure is even more important. A country's adaptation strategies to the health consequences of ozone depletion and climate change should therefore also include strategies to reduce UV exposure.In this review, the health effects of UV radiation and the risk factors for UV-related skin cancer are first presented. The measurement of UV irradiance and exposure in Germany is explained. The effects of ozone depletion and climate change on UV exposure are then described and measures to protect the population are presented.