Updates on the Molecular Basis of Photoaging in All Skin Types.

Photoaging is a complex, ongoing process that clinically manifests as cutaneous rhytides, atrophy, laxity, dyspigmentation, telangiectasias, roughness, and mottled appearance of the skin. There is an abundance of research establishing the mechanism of ultraviolet (UV) - induced photodamage as it is a significant source of photoaging and skin cancers. While UV damage is known to induce photoaging, it is important to understand how other forms of light radiation also contribute to this process. UV only constitutes 5 to 10% of solar radiation that reaches the earth's surface. The remaining nearly 90% is evenly split between infrared and visible light radiation. Early research shows that varied skin types may elicit different photobiologic responses to light. This article presents the mechanisms and biomarkers of photodamage induced by light from across the spectrum, including UV, visible light, and infrared to better prevent and reverse the damage of photoaging in all skin types.J Drugs Dermatol. 2024;23(7):504-509.  doi:10.36849/JDD.7438.

Effects of short-term exposure to red or near-infrared light on axial length in young human subjects.

PURPOSE: To determine whether visible light is needed to elicit axial eye shortening by exposure to long wavelength light. METHODS: Incoherent narrow-band red (620 ± 10 nm) or near-infrared (NIR, 875 ± 30 nm) light was generated by an array of light-emitting diodes (LEDs) and projected monocularly in 17 myopic and 13 non-myopic subjects for 10 min. The fellow eye was occluded. Light sources were positioned 50 cm from the eye in a dark room. Axial length (AL) was measured before and after the exposure using low-coherence interferometry. RESULTS: Non-myopic subjects responded to red light with significant eye shortening, while NIR light induced minor axial elongation (-13.3 ± 17.3 µm vs. +6.5 ± 11.6 µm, respectively, p = 0.005). Only 41% of the myopic subjects responded to red light exposure with a decrease in AL and changes were therefore, on average, not significantly different from those observed with NIR light (+0.2 ± 12.1 µm vs. +1.1 ± 11.2 µm, respectively, p = 0.83). Interestingly, there was a significant correlation between refractive error and induced changes in AL after exposure to NIR light in myopic eyes (r(15) = -0.52, p = 0.03) and induced changes in AL after exposure to red light in non-myopic eyes (r(11) = 0.62, p = 0.02), with more induced axial elongation with increasing refractive error. CONCLUSIONS: Incoherent narrow-band red light at 620 nm induced axial shortening in 77% of non-myopic and 41% of myopic eyes. NIR light did not induce any significant changes in AL in either refractive group, suggesting that the beneficial effect of red laser light therapy on myopia progression requires visible stimulation and not simply thermal energy.

Near-infrared radiation causes sebaceous gland enlargement along with an ROS-dependent augmentation of epidermal growth factor receptor expression in hamsters.

As near-infrared radiation (NIR), which is a composition of sunlight with an 780-1400 nm wavelength, is associated with skin aging such as wrinkles and slacks, the biological actions of NIR with high dermal penetration remains unclear. In the present study, we found that NIR irradiation (40 J/cm2 ) at different levels of irradiance (95-190 mW/cm2 ) using a laboratory device with a xenon flash lamp (780-1700 nm) caused sebaceous gland enlargement concomitantly with skin thickening in the auricle skin of hamsters. The sebaceous gland enlargement resulted from the proliferation of sebocytes due to an increase in the number of proliferating cell nuclear antigen (PCNA)- and lamin B1-positive cells in vivo. In addition, NIR irradiation transcriptionally augmented the production of epidermal growth factor receptor (EGFR) accompanied with an increase in the reactive oxygen species (ROS) level in hamster sebocytes in vitro. Furthermore, the administration of hydrogen peroxide increased the level of EGFR mRNA in the sebocytes. Therefore, these results provide novel evidence that NIR irradiation causes the hyperplasia of sebaceous glands in hamsters by mechanisms in which EGFR production is transcriptionally augmented through ROS-dependent pathways in sebocytes.

Association Between the 2021 Heat Wave in Portland, Oregon, and Seattle, Washington, and Emergency Department Visits.

This study used a health care claims data set of enrollees in commercial and Medicare Advantage insurance plans to assess the association between the June 2021 heat wave and the rates of emergency department visits in Portland, Oregon, and Seattle, Washington.

Fotobiomodulação sistêmica transdérmica: uma revisão de literatura / Transdermal systemic photobiomodulation: a literature review

A fotobiomodulação sistêmica (FBM-S) consiste em uma técnica que utiliza o laser de baixa intensidade no espectro vermelho da luz para irradiação sistêmica. Seus benefícios incluem efeito analgésico, antioxidante sistêmico e anti-inflamatório, ativação de células imunológicas, melhora na cicatrização, vasodilatação e aumento da microcirculação. A técnica original, que utiliza cateter e fibra óptica para irradiação sistêmica, é uma técnica invasiva, por isso a fotobiomodulação sistêmica transdérmica foi desenvolvida como uma alternativa. Assim, o objetivo dessa revisão de literatura é discutir os efeitos, aplicações, protocolos e efeitos colaterais desta terapia modificada. Para tanto, foi realizada uma busca na literatura nas bases de dados Pubmed, Bireme, Embase, Scopus, Science Direct, Web of Science e CENTRAL, sem restrição de idioma no período entre 2010 e 2021. Encontraram-se seis estudos sendo um na área da Odontologia. Os resultados desses estudos sugerem que a FBS-S pode ser utilizada para o tratamento de condições sistêmicas. Em Odontologia, no entanto, a literatura ainda é escassa e mais estudos clínicos randomizados controlados são necessários para comprovar seus efeitos e estabelecer um protocolo clínico para sua utilização.

Systemic photobiomodulation (PBM-S) is a technique that uses low-level laser in the red spectrum of light for systemic irradiation. Its benefits include analgesic, systemic antioxi-dant, and anti-inflammatory effect, activation of immune cells, improved healing, vasodilation, and increased microcirculation. The original technique, which uses catheter and optical fibers for systemic irradiation is an invasive technique. Thus, the transdermal systemic photobiomodulation was developed as an alternative. The purpose of this literature review is to discuss the effects, applications, protocols, and side effects of this modified therapy. A literature search was carried out on Pubmed, Bireme, Embase, Scopus, Science Direct, Web of Science, and CENTRAL databases, with no language restriction in the period be-tween 2010 and 2021. Six studies were found, one in the area of Dentistry. The results of these studies suggest that PBM-S can be used for the treatment of systemic conditions. In Dentistry, however, the literature is still scarce and more randomized controlled clinical trials are needed to prove its effects and establish a protocol for its use.

Heat-Related Emergency Department Visits During the Northwestern Heat Wave - United States, June 2021.

Record high temperatures are occurring more frequently in the United States, and climate change is causing heat waves to become more intense (1), directly impacting human health, including heat-related illnesses and deaths. On average, approximately 700 heat-related deaths occur in the United States each year (2). In the northwestern United States, increasing temperatures are projected to cause significant adverse health effects in the coming years (3). During June 25-30, 2021, most of Oregon and Washington were under a National Weather Service excessive heat warning.* Hot conditions persisted in parts of Oregon, Washington, or Idaho through at least July 14, 2021. The record-breaking heat had the largest impact in Oregon and Washington, especially the Portland metropolitan area, with temperatures reaching 116°F (46.7°C), which is 42°F (5.6°C) hotter than the average daily maximum June temperature.

Zebrafish heart regenerates after chemoptogenetic cardiomyocyte depletion.

BACKGROUND: Zebrafish can regenerate adult cardiac tissue following injuries from ventricular apex amputation, cryoinjury, and cardiomyocyte genetic ablation. Here, we characterize cardiac regeneration from cardiomyocyte chemoptogenetic ablation caused by localized near-infrared excited photosensitizer-mediated reactive oxygen species (ROS) generation. RESULTS: Exposure of transgenic adult zebrafish, Tg(myl7:fapdl5-cerulean), to di-iodinated derivative of the cell- permeable Malachite Green ester fluorogen (MG-2I) and whole-body illumination with 660 nm light resulted in cytotoxic damage to about 30% of cardiac tissue. After chemoptogenetic cardiomyocyte ablation, heart function was compromised, and macrophage infiltration was detected, but epicardial and endocardial activation response was much muted when compared to ventricular amputation. The spared cardiomyocytes underwent proliferation and restored the heart structure and function in 45-60 days after ablation. CONCLUSIONS: This cardiomyocyte ablation system did not appear to activate the epicardium and endocardium as is noted in other cardiac injury models. This approach represents a useful model to study specifically cardiomyocyte injury, proliferation and regeneration in the absence of whole organ activation. Moreover, this system can be adapted to ablate distinct cell populations in any organ system to study their function in regeneration.

G-quadruplex DNA structures and their relevance in radioprotection.

BACKGROUND: DNA, the genetic material of most of the organisms, is the crucial element of life. Integrity of DNA needs to be maintained for transmission of genetic material from one generation to another. All organisms are constantly challenged by the environmental conditions which can lead to the induction of DNA damage. Ionizing radiation (IR) has been known to induce DNA damage and IR sensitivity varies among different organisms. The causes for differential radiosensitivity among various organisms have not been studied in great detail. SCOPE OF REVIEW: We discuss DNA secondary structure formation, GC content of the genome, role of G-quadruplex formation, and its relationship with radiosensitivity of the genome. MAJOR CONCLUSION: In Deinococcus radiodurans, the bacterium that exhibits maximum radio resistance, multiple G-quadruplex forming motifs are reported. In human cells, G-quadruplex formation led to differential radiosensitivity. In this article, we have discussed, the role of secondary DNA structure formation like G-quadruplex in shielding the genome from radiation and its implications in understanding evolution of radio protective effect of an organism. We also discuss role of GC content and its correlation with radio resistance. GENERAL SIGNIFICANCE: This review provides an insight into the role of G-quadruplexes in providing differential radiosensitivity at different site of the genome and in different organisms. It further discusses the possibility of higher GC content contributing towards reduced radiosensitivity in different organisms, evolution of radiosensitivity, and regulation of multiple cellular processes.

Cataract Formation by Near-infrared Radiation in Rabbits.

Surveys and epidemiological studies have shown an increased prevalence of cataracts in workers in the glass and steel industries. These cataracts are associated with exposure to intense infrared radiation (IR) emitted from heated materials and industrial furnaces. Thermal model calculations predicted that near and far IR would cause cataract with different mechanisms. The present study investigated cataract formation by near IR. Eyes of pigmented rabbits were exposed to IR at a wavelength of 808 nm. Morphological changes in the anterior segment of the eye were assessed by slit-lamp microscopy, and temperature distributions in the anterior chamber of the eye were observed during IR exposure using microencapsulated thermochromic liquid crystals. Cortical cataract appeared below the exposed area of the iris in eyes that had been exposed for 6 min to an irradiance of 1.27 W cm-2 or higher. The monitored temperature in the anterior chamber began to increase in the region adjacent to the exposed area of the iris with the onset of IR exposure. These results demonstrate that 808-nm IR is absorbed and converted to heat within the iris, which is then conducted to the lens and produce a cataract, as Goldmann theory states.

Synergies between urban heat island and heat waves in Seoul: The role of wind speed and land use characteristics.

The effects of heat waves (HW) are more pronounced in urban areas than in rural areas due to the additive effect of the urban heat island (UHI) phenomenon. However, the synergies between UHI and HW are still an open scientific question and have only been quantified for a few metropolitan cities. In the current study, we explore the synergies between UHI and HW in Seoul city. We consider summertime data from two non-consecutive years (i.e., 2012 and 2016) and ten automatic weather stations. Our results show that UHI is more intense during HW periods than non-heat wave (NHW) periods (i.e., normal summer background conditions), with a maximum UHI difference of 3.30°C and 4.50°C, between HW and NHW periods, in 2012 and 2016 respectively. Our results also show substantial variations in the synergies between UHI and HW due to land use characteristics and synoptic weather conditions; the synergies were relatively more intense in densely built areas and under low wind speed conditions. Our results contribute to our understanding of thermal risks posed by HW in urban areas and, subsequently, the health risks on urban populations. Moreover, they are of significant importance to emergency relief providers as a resource allocation guideline, for instance, regarding which areas and time of the day to prioritize during HW periods in Seoul.

Heat and dehydration induced oxidative damage and antioxidant defenses following incubator heat stress and a simulated heat wave in wild caught four-striped field mice Rhabdomys dilectus.

Heat waves are known for their disastrous mass die-off effects due to dehydration and cell damage, but little is known about the non-lethal consequences of surviving severe heat exposure. Severe heat exposure can cause oxidative stress which can have negative consequences on animal cognition, reproduction and life expectancy. We investigated the current oxidative stress experienced by a mesic mouse species, the four striped field mouse, Rhabdomys dilectus through a heat wave simulation with ad lib water and a more severe temperature exposure with minimal water. Wild four striped field mice were caught between 2017 and 2019. We predicted that wild four striped field mice in the heat wave simulation would show less susceptibility to oxidative stress as compared to a more severe heat stress which is likely to occur in the future. Oxidative stress was determined in the liver, kidney and brain using malondialdehyde (MDA) and protein carbonyl (PC) as markers for oxidative damage, and superoxide dismutase (SOD) and total antioxidant capacity (TAC) as markers of antioxidant defense. Incubator heat stress was brought about by increasing the body temperatures of animals to 39-40.8°C for 6 hours. A heat wave (one hot day, followed by a 3-day heatwave) was simulated by using temperature cycle that wild four striped field mice would experience in their local habitat (determined through weather station data using temperature and humidity), with maximal ambient temperature of 39°C. The liver and kidney demonstrated no changes in the simulated heat wave, but the liver had significantly higher SOD activity and the kidney had significantly higher lipid peroxidation in the incubator experiment. Dehydration significantly contributed to the increase of these markers, as is evident from the decrease in body mass after the experiment. The brain only showed significantly higher lipid peroxidation following the simulated heat wave with no significant changes following the incubator experiment. The significant increase in lipid peroxidation was not correlated to body mass after the experiment. The magnitude and duration of heat stress, in conjunction with dehydration, played a critical role in the oxidative stress experienced by each tissue, with the results demonstrating the importance of measuring multiple tissues to determine the physiological state of an animal. Current heat waves in this species have the potential of causing oxidative stress in the brain with future heat waves to possibly stress the kidney and liver depending on the hydration state of animals.

Evaluating Mortality Response Associated with Two Different Nordic Heat Warning Systems in Riga, Latvia.

Background and objectives: Progressing climate change is accompanied by a worldwide increase in the intensity, frequency, and duration of heat wave events. Research has shown that heat waves are an emerging public health problem, as they have a significant impact on mortality. As studies exploring this relationship are scarce for Latvia, this study aims to investigate the short-term associations between heat waves and all-cause mortality as well as cause-specific mortality, during the summer months (May-September) in Riga. Materials and Methods: An ecological time series study using daily reported mortality and temperature data from Riga between 2009 and 2015 was employed. Heat waves were defined based on the categories of the Latvian and Swedish heat warning system. Using a Quasi-Poisson regression, the relationships between heat waves and all-cause as well as cause-specific mortality were investigated. Results: Heat waves in Riga were associated with a 10% to 20% increase in the risk of all-cause mortality, depending on the applied heat wave definition, compared to days with normal temperature. In addition, heat-related mortality was found to increase significantly in the ≥65 age group between 12% and 22% during heat waves. In terms of cause-specific mortality, a significant increase of approximately 15% to 26% was observed for cardiovascular mortality. No significant associations were found between heat waves and respiratory or external causes of mortality. Conclusion: These results indicate that there are short-term associations between heat waves and all-cause as well as cardiovascular mortality in Riga and that heat waves therefore represent a public health problem in this Baltic city.

DNA damage induced during mitosis undergoes DNA repair synthesis.

Understanding the mitotic DNA damage response (DDR) is critical to our comprehension of cancer, premature aging and developmental disorders which are marked by DNA repair deficiencies. In this study we use a micro-focused laser to induce DNA damage in selected mitotic chromosomes to study the subsequent repair response. Our findings demonstrate that (1) mitotic cells are capable of DNA repair as evidenced by DNA synthesis at damage sites, (2) Repair is attenuated when DNA-PKcs and ATM are simultaneously compromised, (3) Laser damage may permit the observation of previously undetected DDR proteins when damage is elicited by other methods in mitosis, and (4) Twenty five percent of mitotic DNA-damaged cells undergo a subsequent mitosis. Together these findings suggest that mitotic DDR is more complex than previously thought and may involve factors from multiple repair pathways that are better understood in interphase.

Balance between Health Risks and Benefits for Outdoor Workers Exposed to Solar Radiation: An Overview on the Role of Near Infrared Radiation Alone and in Combination with Other Solar Spectral Bands.

Near infrared or infrared A (IRA) accounts for over 40% of the solar spectrum (SS) and is able to reach subcutaneous tissue as well as the retina. Outdoor workers are occupationally exposed to solar radiation (SR), but the level of exposure may differ widely depending on the job performed, time spent outdoors, latitude, altitude, season, personal protection, etc. Until now, risk assessment and management for outdoor workers has focused on the prevention of both acute and long-term effects on the eye and the skin due to solar ultraviolet radiation (UVR) with little consideration of the other components of the SS (a possible exception is represented by visible radiation with reference to the eye). A growing body of evidence coming from in vitro studies indicates that IRA is involved in cellular reactive oxygen species (ROS) production and may interfere with the respiratory chain in the mitochondria. Moreover, it can modulate gene expression and some metabolic pathways. The biological action of IRA is only partly attributable to a thermal mechanism, should it be also involved in photochemical ones. The cellular and molecular pathways affected by IRA are partly similar and partly different with respect to those involved in the case of visible ultraviolet A (UVA) and ultraviolet B (UVB) radiation. Consequently, the net effect of the SS is very difficult to predict at different levels of the biological organization, making more difficult the final balance of health risk and benefits (for the skin, eye, immune system, blood pressure, etc.) in a given exposure situation. Moreover, few in vivo studies and no epidemiological data are presently available in this regard. Investigating this topic may contribute to better defining the individual exposome. More practically, it is expected to bring benefits to the risk assessment and management for outdoor workers exposed to SS, contributing to: (1) better definition of the individual profiles of susceptibility, (2) more focused preventive and protective measures, (3) better implementation of the health surveillance and (4) a more effective information and training.

Development and clinical study of the use of infrared radiation to accelerate the dissolution rate of a microneedle array patch (MAP).

The dissolution rate of a microneedle array patch (MAP) determines how long a MAP must remain attached to the skin (often called "wear time"). In this study, the dissolution rate of a MAP was increased, not by changing the drug formulation but by employing an infrared (IR) device that is widely used for hospital treatment and in-home therapy. A MAP with microneedles 480 µm in height was prepared using hyaluronic acid (HA). Changes in transepidermal water loss (TEWL), the surface temperature of the skin, and the dissolution rate of the MAP tips with IR irradiation were evaluated on human skin in vivo. Time for recovery from erythema that occurred after MAP attachment and IR irradiation was also evaluated. TEWL increased more than fourfold with IR irradiation. Water that evaporated as a result of IR irradiation was trapped in the skin layer by the patch, resulting in the increased dissolution rate of the MAP tips. After 10 min of IR irradiation, the height of the dissolving tips compared with their initial height increased from 41 to 56%, and the dissolved volume of the tips compared with their initial volume increased from 7 to 18%. During the 10 min of irradiation, the skin surface temperature rose from 32 to 40 °C. Erythema occurred in the early stage of treatment with IR irradiation and MAP attachment, but it abated within 2 h after removal of the MAP and cessation of IR irradiation. Through this study, it was possible to shorten the administration time of MAPs by using an IR device that could be easily accessed. This method can be applied to various types of MAPs in order to reduce the time that the MAPs must remain attached to the skin without changing the drug formulation. Graphical abstract The increase in dissolution rate of dissolving microneedle array patch (MAP) as a result of infrared radiation. a Water-soluble tips of MAP dissolved in water in skin without infrared irradiation. Dotted line indicates the initial dissolving microneedles. b Water in skin and subcutaneous layer evaporated actively with infrared irradiation and was stored under patch of MAP. Increased amount of water in skin induced faster dissolution of MAP tips.

Sunscreen claims, risk management and consumer confidence.

This essay is a personal reflection on how the concept of risk is impacting on the development of sunscreen products and claims, and whether these developments are jeopardizing consumer confidence. In order to estimate the risk of harm, we need not only to identify a hazard but, as importantly, determine the degree of exposure to the hazard and understand the health of impact of consequent exposure. A practice by many manufacturers is simply to market a product that claims to be protective against a hazard with little, or no, regard to exposure or consequence. The inherent danger with this approach is to undermine trust in product efficacy and in so doing to put at risk consumer confidence in both product and manufacturer. An example of this approach using infrared radiation as the hazard will be discussed.

Cet essai est une réflexion personnelle sur la façon dont le concept de risque influe sur le développement de produits solaires adaptés et leurs allégations, et si ces développements compromettent la confiance des consommateurs. Afin d'estimer le risque de préjudice, nous avons besoin non seulement d'identifier un risque mais, et c'est tout aussi important, de déterminer le degré de l'exposition au risque et de comprendre l'impact sur la santé d'une exposition conséquente. La pratique de nombreux fabricants consiste simplement à commercialiser un produit qui prétend avoir un effet protecteur contre un danger, avec peu ou aucun égard vis-à-vis de l'exposition ou des conséquences. Le risque inhérent à cette approche est de compromettre la confiance dans l'efficacité des produits et ce faisant, de mettre en péril la confiance des consommateurs envers les produits et les fabricants. Un exemple de cette approche utilisant les rayons infrarouges comme risque fera l'objet de la discussion.