Wavelength-Dependent DNA Damage Induced by Single Wavelengths of UVC Light (215 to 255 nm) in a Human Cornea Model.

Scientific bodies overseeing UV radiation protection recommend safety limits for exposure to ultraviolet light in the workplace based on published peer-reviewed data. To support this goal, a 3D model of the human cornea was used to assess the wavelength dependence of corneal damage induced by UVC light. In the first set of experiments the models were exposed with or without simulated tears; at each wavelength (215-255 nm) cells with DNA dimers and their distribution within the epithelium were measured.

Extending the acute skin response spectrum to include the far-UVC.

Guidance on maximal limits for ultraviolet (UV) exposure has been developed by national and international organizations to protect against adverse effects on human skin and eyes. These guidelines consider the risk of both acute effects (i.e.

Susceptibility of extremophiles to far-UVC light for bioburden reduction in spacecraft assembly facilities.

The prevention and reduction of microbial species entering and leaving Earth's biosphere is a critical aspect of planetary protection research. While various decontamination methods exist and are currently utilized for planetary protection purposes, the use of far-UVC light (200-230 nm) as a means for microbial reduction remains underexplored. Unlike conventional germicidal ultraviolet at 254 nm, which can pose a health risk to humans even with small exposure doses, far-UVC light poses minimal health hazard making it a suitable candidate for implementation in occupied areas of spacecraft assembly facilities.

222 nm far-UVC light markedly reduces the level of infectious airborne virus in an occupied room.

An emerging intervention for control of airborne-mediated pandemics and epidemics is whole-room far-UVC (200-235 nm). Laboratory studies have shown that 222-nm light inactivates airborne pathogens, potentially without harm to exposed occupants. While encouraging results have been reported in benchtop studies and in room-sized bioaerosol chambers, there is a need for quantitative studies of airborne pathogen reduction in occupied rooms.

Proton and alpha radiation-induced mutational profiles in human cells.

Ionizing radiation is known to be DNA damaging and mutagenic, however less is known about which mutational footprints result from exposures of human cells to different types of radiation. We were interested in the mutagenic effects of particle radiation exposures on genomes of various human cell types, in order to gauge the genotoxic risks of galactic cosmic radiation, and of certain types of tumor radiotherapy. To this end, we exposed cultured cell lines from the human blood, breast and lung to fractionated proton and alpha particle (helium nuclei) beams at doses sufficient to considerably affect cell viability.

No Evidence of Induced Skin Cancer or Other Skin Abnormalities after Long-Term (66 week) Chronic Exposure to 222-nm Far-UVC Radiation.

Far-UVC radiation, typically defined as 200-235 nm, has similar or greater anti-microbial efficacy compared with conventional 254-nm germicidal radiation. In addition, biophysical considerations of the interaction of far-UVC with tissue, as well as multiple short-term safety studies in animal models and humans, suggest that far-UVC exposure may be safe for skin and eye tissue. Nevertheless, the potential for skin cancer after chronic long-term exposure to far-UVC has not been studied.

The intercellular communications mediating radiation-induced bystander effects and their relevance to environmental, occupational, and therapeutic exposures.

Purpose: The assumption that traversal of the cell nucleus by ionizing radiation is a prerequisite to induce genetic damage, or other important biological responses, has been challenged by studies showing that oxidative alterations extend beyond the irradiated cells and occur also in neighboring bystander cells. Cells and tissues outside the radiation field experience significant biochemical and phenotypic changes that are often similar to those observed in the irradiated cells and tissues. With relevance to the assessment of long-term health risks of occupational, environmental and clinical exposures, measurable genetic, epigenetic, and metabolic changes have been also detected in the progeny of bystander cells.

Inactivation Rates for Airborne Human Coronavirus by Low Doses of 222 nm Far-UVC Radiation.

Recent research using UV radiation with wavelengths in the 200-235 nm range, often referred to as far-UVC, suggests that the minimal health hazard associated with these wavelengths will allow direct use of far-UVC radiation within occupied indoor spaces to provide continuous disinfection. Earlier experimental studies estimated the susceptibility of airborne human coronavirus OC43 exposed to 222-nm radiation based on fitting an exponential dose-response curve to the data. The current study extends the results to a wider range of doses of 222 nm far-UVC radiation and uses a computational model coupling radiation transport and computational fluid dynamics to improve dosimetry estimates.

Far-UVC (222 nm) efficiently inactivates an airborne pathogen in a room-sized chamber.

Many infectious diseases, including COVID-19, are transmitted by airborne pathogens. There is a need for effective environmental control measures which, ideally, are not reliant on human behaviour. One potential solution is Krypton Chloride (KrCl) excimer lamps (often referred to as Far-UVC), which can efficiently inactivate pathogens, such as coronaviruses and influenza, in air.

Mitochondrial Damage Response and Fate of Normal Cells Exposed to FLASH Irradiation with Protons.

Radiation therapy (RT) plays an important role in cancer treatment. The clinical efficacy of radiation therapy is, however, limited by normal tissue toxicity in areas surrounding the irradiated tumor. Compared to conventional radiation therapy (CONV-RT) in which doses are typically delivered at dose rates between 0.

Wavelength-dependent DNA Photodamage in a 3-D human Skin Model over the Far-UVC and Germicidal UVC Wavelength Ranges from 215 to 255 nm.

The effectiveness of UVC to reduce airborne-mediated disease transmission is well established. However, conventional germicidal UVC (~254 nm) cannot be used directly in occupied spaces because of the potential for damage to the skin and eye. A recently studied alternative with the potential to be used directly in occupied spaces is far UVC (200-235 nm, typically 222 nm), as it cannot penetrate to the key living cells in the epidermis.

Exposure of Human Skin Models to KrCl Excimer Lamps: The Impact of Optical Filtering.

Far-UVC radiation is a promising technology that is potentially both effective at killing airborne microbes such as coronaviruses and influenza, and being minimally hazardous to the skin and eyes. Our previous studies on health risks from far-UVC have employed a krypton-chloride (KrCl) excimer lamp, emitting principally at 222 nm, supplemented with an optical filter to remove longer wavelength emissions inherent to these lamps. This study explores KrCl lamp health hazards by comparing filtered and unfiltered KrCl lamps using effective spectral irradiance calculations and experimental skin exposures.

Far-UVC light (222 nm) efficiently and safely inactivates airborne human coronaviruses.

A direct approach to limit airborne viral transmissions is to inactivate them within a short time of their production. Germicidal ultraviolet light, typically at 254 nm, is effective in this context but, used directly, can be a health hazard to skin and eyes. By contrast, far-UVC light (207-222 nm) efficiently kills pathogens potentially without harm to exposed human tissues.

Genetic trajectory and immune microenvironment of lung-specific oligometastatic colorectal cancer.

Genetics and immunologic dynamics pushing the evolution of colorectal cancer (CRC) from the primary tumor to the metastases are largely unknown; cancer heterogeneity makes challenging both therapy and mechanistic studies. We selected patients developing CRC with lung-limited metastatic disease as only illness during their life in order to find any relevant genotype-phenotype relationship. Analysis of 523 cancer-relevant genes and of immune cells infiltration in primary and metastatic tissues revealed atypical genomic trajectories (TMB decrease, KRAS and SMAD4 regressive mutations), specific genetic events (ERBB2 point mutations) and scarce T-cell infiltration.

Radiation-Induced Lipid Peroxidation Triggers Ferroptosis and Synergizes with Ferroptosis Inducers.

Although radiation is widely used to treat cancers, resistance mechanisms often develop and involve activation of DNA repair and inhibition of apoptosis. Therefore, compounds that sensitize cancer cells to radiation via alternative cell death pathways are valuable. We report here that ferroptosis, a form of nonapoptotic cell death driven by lipid peroxidation, is partly responsible for radiation-induced cancer cell death.

An Integrated Preprocessing Approach for Exploring Single-Cell Gene Expression in Rare Cells.

Exploring the variability in gene expressions of rare cells at the single-cell level is critical for understanding mechanisms of differentiation in tissue function and development as well as for disease diagnostics and cancer treatment. Such studies, however, have been hindered by major difficulties in tracking the identity of individual cells. We present an approach that combines single-cell picking, lysing, reverse transcription and digital polymerase chain reaction to enable the isolation, tracking and gene expression analysis of rare cells.

Predicting DNA damage foci and their experimental readout with 2D microscopy: a unified approach applied to photon and neutron exposures.

The consideration of how a given technique affects results of experimental measurements is a must to achieve correct data interpretation. This might be challenging when it comes to measurements on biological systems, where it is unrealistic to have full control (e.g.

Biological effects in normal cells exposed to FLASH dose rate protons.

Background: Radiotherapy outcomes are limited by toxicity in the healthy tissues surrounding the irradiated tumor. Recent pre-clinical studies have shown that irradiations with electrons or photons delivered at so called FLASH dose rates (i.e.

MODELLING γ-H2AX FOCI INDUCTION TO MIMIC LIMITATIONS IN THE SCORING TECHNIQUE.

An approach based on track-structure calculations has been developed to take account of artefacts occurring during γ-H2AX foci detection in 2D images of samples analyzed through immunocytochemistry. The need of this works stems from the observed saturation in foci yields measured after X-ray doses higher than few grays, hindering an unambiguous quantification of DNA damage and of radiation effectiveness. The proposed modelling approach allows to simulate the observer's point of view for foci scoring, mimicking the selection of a slice Δz of the cell nucleus due to the microscope depth of field, and applying a clustering algorithm to group together damages within a resolution parameter r.

Effect of far ultraviolet light emitted from an optical diffuser on methicillin-resistant Staphylococcus aureus in vitro.

Drug-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) are a target for new antimicrobial technologies. Far-UVC technology is an emerging disinfection method that directly kills microorganisms using light. In contrast with conventional UV sterilization, far-UVC light has antimicrobial capabilities without apparent harm to mammalian cells.

Far-UVC light prevents MRSA infection of superficial wounds in vivo.

Background: Prevention of superficial surgical wound infections from drug-resistant bacteria such as methicillin resistant Staphylococcus aureus (MRSA) currently present major health care challenges. The majority of surgical site infections (SSI) are believed to be caused by airborne transmission of bacteria alighting onto the wound during surgical procedures. We have previously shown that far-ultraviolet C light in the wavelength range of 207-222 nm is significantly harmful to bacteria, but without damaging mammalian cells and tissues.