Light-dependent chloroplast relocation in wild strawberry (Fragaria vesca)

Chloroplast photorelocation is a vital organellar response that optimizes photosynthesis in plants amid fluctuating environmental conditions. Chloroplasts exhibit an accumulation response, in which they move toward weak light to enhance photoreception, and an avoidance response, in which they move away from strong light to avoid photodamage. Although chloroplast photorelocation has been extensively studied in model plants such as Arabidopsis thaliana, little is known about this process in the economically important crop strawberry. Here, we investigated chloroplast photorelocation in leaf mesophyll cells of wild strawberry (Fragaria vesca), a diploid relative of commercially cultivated octoploid strawberry (F. × ananassa). Microscopy observation revealed that the periclinal area of leaf mesophyll cells in F. vesca is considerably smaller than that of A. thaliana. Given this small cell size, we investigated chloroplast photorelocation in F. vesca by measuring light transmittance in leaves. Weak blue light induced the accumulation response, whereas strong blue light induced the avoidance response. Unexpectedly, strong red light also induced the accumulation response in F. vesca. These findings shed light on chloroplast photorelocation as an intracellular response, laying the foundation for enhancing photosynthesis and productivity in Fragaria.

Ascorbic acid potentiates photodynamic inactivation mediated by octyl gallate and blue light for rapid eradication of planktonic bacteria and biofilms

This study reported for the first time that Ascorbic acid (AA) could appreciably boost the efficiency of Octyl gallate (OG)-mediated photodynamic inactivation (PDI) on Escherichia coli and Staphylococcus aureus in planktonic and biofilm states. The combination of OG (0.075 mM) and AA (200 mM) with 420 nm blue light (212 mW/cm2) led to a >6 Log killing within only 5 min for E. coli and S. aureus and rapid eradication of biofilms. The mechanism of action appears to be the generation of highly toxic hydroxyl radicals (•OH) via photochemical pathways. OG was exposed to BL irradiation to generate various reactive oxygen radicals (ROS) and the addition of AA could transform singlet oxygen (1O2) into hydrogen peroxide (H2O2), which could further react with AA to generate enormous •OH. These ROS jeopardized bacteria and biofilms by nonspecifically attacking various biomacromolecules. Overall, this PDI strategy provides a powerful microbiological decontamination modality to guarantee safe food products.

Blue-light irradiation induced partial nitrification

The role of ray radiation from the sunlight acting on organisms has long-term been investigated. However, how the light with different wavelengths affects nitrification and the involved nitrifiers are still elusive. Here, we found more than 60 % of differentially expressed genes (DEGs) in nitrifiers were observed under irradiation of blue light with wavelengths of 440-480 nm, which were 13.4 % and 20.3 % under red light and white light irradiation respectively. Blue light was more helpful to achieve partial nitrification rather than white light or red light, where ammonium oxidization by ammonia-oxidizing archaea (AOA) with the increased relative abundance from 8.6 % to 14.2 % played a vital role. This was further evidenced by the enhanced TCA cycle, reactive oxygen species (ROS) scavenge and DNA repair capacity in AOA under blue-light irradiation. In contrast, nitrite-oxidizing bacteria (NOB) was inhibited severely to achieve partial nitrification, and the newly discovered encoded blue light photoreceptor proteins made them more sensitive to blue light and hindered cell activity. Ammonia-oxidizing bacteria (AOB) expressed genes for DNA repair capacity under blue-light irradiation, which ensured their tiny impact by light irradiation. This study provided valuable insights into the photosensitivity mechanism of nitrifiers and shed light on the diverse regulatory by light with different radiation wavelengths in artificial systems, broadening our comprehension of the nitrogen cycle on earth.

Hazards associated with blue light emitted during gas metal arc welding of mild steel using various shielding gases and currents

Blue light emitted during arc welding is known to potentially cause photoretinopathy. To help prevent retinal injury, it is important to identify the hazards associated with various welding conditions. The present work conducted experiments involving gas metal arc welding of mild steel under various conditions, and measured the spectral radiance of the arcs. The effective radiance values, as used by the American Conference of Governmental Industrial Hygienists (ACGIH) to quantify exposure level of blue light, were subsequently calculated from the data. The resulting values were in the range of 5.0-118 W/cm2/sr, corresponding to hazardous levels according to ACGIH guidelines. The effective radiance was increased at higher welding currents and when pulsed currents were used rather than steady currents. The blue light hazard was also affected by the type of shielding gas employed. These data confirm that it is very hazardous to stare at arcs during gas metal arc welding of mild steel. As such, appropriate eye protection is necessary during arc welding, and directly staring at the arc should be avoided.

Lutein and Zeaxanthin Supplementation Improves Dynamic Visual and Cognitive Performance in Children: A Randomized, Double-Blind, Parallel, Placebo-Controlled Study

INTRODUCTION

Supplementation with dietary neuro-pigments lutein (L) and zeaxanthin (Z) has been shown to improve many aspects of visual and cognitive function in adults. In this study, we tested whether a similar intervention could improve such outcomes in preadolescent children.

METHODS

Sixty children (age range 5-12 years) were randomized in a 2:1 ratio in this double-blind, placebo-controlled clinical trial. Subjects were supplemented with gummies containing either a combination of 10 mg lutein and 2 mg zeaxanthin (LZ) or placebo for 180 days. Macular pigment optical density (MPOD) was the primary endpoint. The secondary endpoints included serum levels of L and Z, and brain-derived neurotrophic factor (BDNF), critical flicker fusion (CFF), eye strain and fatigue using visual analogue scales (VAS), Children's Sleep Habits Questionnaire-Abbreviated (CSHQ-A), and Creyos Health cognitive domains like attention, focus/concentration, episodic memory and learning, visuospatial working memory, and visuospatial processing speed. Safety was assessed throughout the study on the basis of physical examination, vital signs, clinical laboratory tests, and monitoring of adverse events.

RESULTS

The LZ group showed significant increases in MPOD at all visits post-supplementation, with significant increases as early as day 42 compared to placebo. The LZ group showed significant increases in serum lutein levels, reduced eye strain and fatigue, and improved cognitive performance (focus, episodic memory and learning, visuospatial working memory) at days 90 and 180 compared to placebo. Further, the LZ group showed significant increases in processing speed (CFF), attention, visuospatial processing, and serum Z and BDNF levels on day 180 compared to placebo. No safety concerns were observed.

CONCLUSIONS

Supplementing LZ resulted in increased MPOD levels, along with increased serum levels of L, Z, and BDNF. These changes were associated with improved visual and cognitive performances and reduction in eye strain and eye fatigue in the children receiving LZ gummies. The investigational product was safe and well tolerated.

TRIAL REGISTRATION

http://ctri.nic.in/ Identifier CTRI/2022/05/042364.

Antiviral and synergistic effects of photo-energy with acyclovir on herpes simplex virus type 1 infection

This experimental study aimed to evaluate the antiviral and synergistic effects of photoenergy irradiation on human herpes simplex virus type I (HSV-1) infection. We assessed viral replication, plaque formation, and relevant viral gene expression to examine the antiviral and synergistic effects of blue light (BL) with acyclovir treatment. Our results showed that daily BL (10 J/cm2) irradiation inhibited plaque-forming ability and decreased viral copy numbers in HSV-1-infected monkey kidney epithelial Vero cells and primary human oral keratinocyte (HOK) cells. Combined treatment with the antiviral agent acyclovir and BL irradiation increased anti-viral activity, reducing viral titers and copy numbers. In particular, accumulated BL irradiation suppressed characteristic viral genes including UL19 and US6, and viral DNA replication-essential genes including UL9, UL30, UL42, and UL52 in HOK cells. Our results suggest that BL irradiation has anti-viral and synergistic properties, making it a promising therapeutic candidate for suppressing viral infections in clinical trials.

An Experimental Phototherapy Device for Studying the Effects of Blue Light on Patients with Raynaud's Phenomenon

Raynaud's phenomenon (RP) is a condition that causes decreased blood flow to areas perfused by small blood vessels (e.g., fingers, toes). In severe cases, ulceration, gangrene, and loss of fingers may occur. Most treatments focus on inducing vasorelaxation in affected areas by the way of pharmaceuticals. Recently, animal studies have shown that vasorelaxation can be induced by non-coherent blue light (wavelength ~ 430-460 nm) through the actions of melanopsin, a photoreceptive opsin protein encoded by the OPN4 gene. To study this effect in humans, a reliable phototherapy device (PTD) is needed. We outline the construction of a PTD to be used in studying blue light effects on Raynaud's patients. Our design addresses user safety, calibration, electromagnetic compatibility/interference (EMC/EMI), and techniques for measuring physiological responses (temperature sensors, laser Doppler flow sensors, infrared thermal imaging of the hands). We tested our device to ensure (1) safe operating conditions, (2) predictable, user-controlled irradiance output levels, (3) an ability for measuring physiological responses, and (4) features necessary to enable a double-blinded crossover study for a clinical trial. We also include in the Methods an approved research protocol utilizing our device that may serve as a starting point for clinical study. We introduced a reliable PTD for studying the effects of blue light therapy for patients suffering from Raynaud's phenomenon and showed that our device is safe and reliable and includes the required measurement vectors for tracking treatment effects throughout the duration of a clinical study.

Integrated transcriptome and metabolome analysis reveals anthocyanin biosynthesis mechanisms in pepper (Capsicum annuum L.) leaves under continuous blue light irradiation

BACKGROUND

Different metabolic compounds give pepper leaves and fruits their diverse colors. Anthocyanin accumulation is the main cause of the purple color of pepper leaves. The light environment is a critical factor affecting anthocyanin biosynthesis. It is essential that we understand how to use light to regulate anthocyanin biosynthesis in plants.

RESULT

Pepper leaves were significantly blue-purple only in continuous blue light or white light (with a blue light component) irradiation treatments, and the anthocyanin content of pepper leaves increased significantly after continuous blue light irradiation. This green-to-purple phenotype change in pepper leaves was due to the expression of different genes. We found that the anthocyanin synthesis precursor-related genes PAL and 4CL, as well as the structural genes F3H, DFR, ANS, BZ1, and F3'5'H in the anthocyanin synthesis pathway, had high expression under continuous blue light irradiation. Similarly, the expression of transcription factors MYB1R1-like, MYB48, MYB4-like isoform X1, bHLH143-like, and bHLH92-like isoform X3, and circadian rhythm-related genes LHY and COP1, were significantly increased after continuous blue light irradiation. A correlation network analysis revealed that these transcription factors and circadian rhythm-related genes were positively correlated with structural genes in the anthocyanin synthesis pathway. Metabolomic analysis showed that delphinidin-3-O-glucoside and delphinidin-3-O-rutinoside were significantly higher under continuous blue light irradiation relative to other light treatments. We selected 12 genes involved in anthocyanin synthesis in pepper leaves for qRT-PCR analysis, and the accuracy of the RNA-seq results was confirmed.

CONCLUSIONS

In this study, we found that blue light and 24-hour irradiation together induced the expression of key genes and the accumulation of metabolites in the anthocyanin synthesis pathway, thus promoting anthocyanin biosynthesis in pepper leaves. These results provide a basis for future study of the mechanisms of light quality and photoperiod in anthocyanin synthesis and metabolism, and our study may serve as a valuable reference for screening light ratios that regulate anthocyanin biosynthesis in plants.

Potential of photodynamic therapy in the management of infectious oral diseases

Photodynamic therapy (PDT) can take place in the presence of three elements: Light with an appropriate wavelength; a photosensitizer; and the presence of oxygen. This type of treatment is very effective overall against bacterial, viral and mycotic cells. In the last 10 years many papers have been published on PDT with different types of photosensitizers (e.g., methylene blue, toluidine blue, indocyanine green, curcumin-based photosensitizers), different wavelengths (e.g., 460 nm, 630 nm, 660 nm, 810 nm) and various parameters (e.g., power of the light, time of illumination, number of sessions). In the scientific literature all types of PDT seem very effective, even if it is difficult to find a standard protocol for each oral pathology. PDT could be an interesting way to treat some dangerous oral infections refractory to common pharmacological therapies, such as candidiasis from multidrug-resistant Candida spp.

Behavioral responses of cave-roosting bats to artificial light of different spectra and intensities: Implications for lighting management strategy

Artificial light at night has become an emerging environmental pollutant, posing a serious threat to biodiversity. Cave-roosting animals are vulnerable to light pollution due to long-term adaptation to nocturnal niches, and the problem is especially severe in the context of cave tourism and limestone mining. Mitigating the adverse impacts of artificial light on cave-dwelling animals presents a challenge. This study aimed to assess the relative contributions of spectral parameters and light intensity to the emergence behavior of nine cave-roosting bat species: Rhinolophus macrotis, Rhinolophus pearsonii, Rhinolophus rex, Rhinolophus pusillus, Rhinolophus siamensis, Rhinolophus sinicus, Hipposideros armiger, Myotis davidii, and Miniopterus fuliginosus. We manipulated light spectra and intensities through light-emitting diode (LED) lighting and gel filters at the entrance of bat roost. We monitored nightly passes per species to quantify bat emergence under the dark control and ten lighting conditions (blue, green, yellow, red, and white light at high and low intensities) using ultrasonic recording. Our analyses showed that the number of bat passes tended to be reduced in the presence of white, green, and yellow light, independent of light intensity. In contrast, the number of bat passes showed no pronounced differences under the dark control, blue light, and red light. The number of bat passes was primarily affected by LED light's blue component, red component, peak wavelength, and half-width instead of light intensity. These results demonstrate that spectral parameters of LED light can significantly affect emergence behavior of cave-dwelling bats. Our findings highlight the importance of manipulating light colors to reduce the negative impacts of light pollution on cave-roosting bats as a function of their spectral sensitivity. We recommend the use of gel filters to manage existing artificial lighting systems at the entrance of bat-inhabited caves.

The growth, nutrient uptake and fruit quality in four strawberry cultivars under different Spectra of LED supplemental light

An experiment was conducted in a greenhouse to determine the effects of different supplemental light spectra on the growth, nutrient uptake, and fruit quality of four strawberry cultivars. The plants were grown under natural light and treated with blue (460 nm), red (660 nm), and red/blue (3:1) lights. Results showed that the "Parous" and "Camarosa" had higher fresh and dry mass of leaves, roots, and crowns compared to the "Sabrina" and "Albion". The use of artificial LED lights improved the vegetative growth of strawberry plants. All three supplemental light spectra significantly increased the early fruit yield of cultivars except for "Parous". The red/blue supplemental light spectrum also increased the fruit mass and length of the "Albion". Supplemental light increased the total chlorophyll in "Camarosa" and "Albion", as well as the total soluble solids in fruits. The "Albion" had the highest concentration of fruit anthocyanin, while the "Sabrina" had the lowest. The use of supplemental light spectra significantly increased the fruit anthocyanin concentration in all cultivars. Without supplemental light, the "Camarosa" had the lowest concentration of K and Mg, which increased to the highest concentration with the use of supplemental light spectra. All three spectra increased Fe concentration to the highest value in the "Sabrina", while only the red/blue light spectrum was effective on the "Camarosa". In conclusion, the use of supplemental light can increase the yield and fruit quality of strawberries by elevating nutrients, chlorophyll, and anthocyanin concentrations in plants.

Just Let Me Sleep in: Identifying and Treating Delayed Sleep Phase Disorder in Adolescents

Individuals with delayed sleep phase disorder (DSPD) are unable to naturally fall asleep and awake at conventional times; for this reason, DSPD is often mistaken for insomnia. However, unlike many patients with insomnia, those with DSPD struggle to get up at appropriate times. DSPD is associated with school refusal, academic difficulties, and lower employment rate. DSPD in youth has prevalence as high as 16%, and is often comorbid with other psychiatric disorders. Treatments include appropriate light exposure during the day, melatonin use, developing an evening routine that minimizes arousal-increasing activities, and gradually shifting sleep-wake times toward more functional ones.

A numerical model for quantifying exposure to natural and artificial light in human health research

Various skin and ocular pathologies can result from overexposure to ultraviolet radiation and blue light. Assessing the potential harm of exposure to these light sources requires quantifying the energy received to specific target tissue. Despite a well-established understanding of the light-disease relationship, the quantification of received energy in diverse lighting scenarios proves challenging due to the multitude of light sources and continuous variation in the orientation of receiving tissues (skin and eyes). This complexity makes the determination of health hazards associated with specific lighting conditions difficult. In this study, we present a solution to this challenge using a numerical approach. Through the implementation of algorithms applied to 3D geometries, we created and validated a numerical model that simulates skin and ocular exposure to both natural and artificial light sources. The resulting numerical model is a computational framework in which customizable exposure scenarios can be implemented. The ability to adapt simulations to different configurations for study makes this model a potential investigative method in human health research.

Integrated transcriptome and metabolome analysis provides insights into blue light response of Flammulina filiformis

Blue light promotes primordium differentiation and fruiting body formation of mushroom. However, the blue light response mechanism of mushroom remains unclear. In this study, mycelium of Flammulina filiformis was exposed to blue light, red light and dark conditions, and then the comparative metabolome and transcriptome analysis was applied to explore metabolic regulation mechanism of F. filiformis under blue light and red light conditions. The yield of the fruiting body of F. filiformis under blue light condition was much higher than that under dark and red light conditions. Metabolome analysis showed that blue light treatment reduced the concentrations of many low molecular weight carbohydrates in the pilei, but it promoted the accumulation of some low molecular weight carbohydrates in the stipes. Blue light also decreased the accumulation of organic acids in the stipes. Blue light treatment reduced the levels of tyrosine and tryptophan in the stipes, but it largely promoted the accumulation of lysine in this organ. In the stipes of F. filiformis, blue light shifted metabolite flow to synthesis of lysine and carbohydrates through inhibiting the accumulation of aromatic amino acids and organic acids, thereby enhancing its nutritional and medicinal values. The transcriptome analysis displayed that blue light enhanced accumulation of lysine in fruiting body of F. filiformis through downregulation of lysine methyltransferase gene and L-lysine 6-monooxygenase gene. Additionally, in the stipes, blue light upregulated many hydrolase genes to improve the ability of the stipe to biodegrade the medium and elevated the growth rate of the fruiting body.

Administration of blue light in the morning and no blue-ray light in the evening improves the circadian functions of non-24-hour shift workers

In modern 24-hour society, various round-the-clock services have entailed shift work, resulting in non-24-hour schedules. However, the extent of behavioral and physiological alterations by non-24-hour schedules remains unclear, and particularly, effective interventions to restore the circadian functions of non-24-hour shift workers are rarely explored. In this study, we investigate the effects of a simulated non-24-hour military shift work schedule on daily rhythms and sleep, and establish an intervention measure to restore the circadian functions of non-24-hour shift workers. The three stages of experiments were conducted. The stage-one experiment was to establish a comprehensive evaluation index of the circadian rhythms and sleep for all 60 participants by analyzing wristwatch-recorded physiological parameters and sleep. The stage-two experiment evaluated the effects of an intervention strategy on physiological rhythms and sleep. The stage-three experiment was to examine the participants' physiological and behavioral disturbances under the simulated non-24-hour military shift work schedule and their improvements by the optimal lighting apparatus. We found that wristwatch-recorded physiological parameters display robust rhythmicity, and the phases of systolic blood pressures and heart rates can be used as reliable estimators for the human body time. The simulated non-24-hour military shift work schedule significantly disrupts the daily rhythms of oxygen saturation levels, blood pressures, heart rates, and reduces sleep quality. Administration of blue light in the morning and no blue-ray light in the evening improves the amplitude and synchronization of daily rhythms of the non-24-hour participants. These findings demonstrate the harmful consequences of the non-24-hour shift work schedule and provide a non-invasive strategy to improve the well-being and work efficiency of the non-24-hour shift population.

[Blue light and intraocular lenses (IOLs): Beliefs and realities]

The first intraocular lenses (IOLs) used for cataract surgery transmitted both ultraviolet (UV) radiation and visible light to the retina. Colorless UV-blocking IOLs were introduced and rapidly adopted in the 1980s. Yellow-tinted blue-blocking (also known as blue-filtering) IOLs were marketed in the early 1990s. Blue-blocking IOLs were intended to simulate age-related crystalline lens yellowing to reduce the cyanopsia that some patients experienced after cataract surgery. When blue-filtering IOLs were introduced in North America, however, blue-blocking chromophores were advocated as a way to protect patients from age-related macular degeneration (AMD) despite the lack of evidence that normal environmental light exposure causes AMD. The "blue light hazard" is a term that describes the experimental finding that acute, abnormally intense light exposures are potentially more phototoxic to the retina when short rather than long wavelengths are used. Thus, in brief exposures to intense light sources such as welding arcs, ultraviolet radiation is more hazardous than blue light, which is more hazardous than longer wavelength green or red light. International commissions have cautioned that the blue light hazard does not apply to normal indoor or outdoor light exposures. Nonetheless, the hazard is used for commercial purposes to suggest misleadingly that ambient environmental light can cause acute retinal phototoxicity and increase the risk of AMD. Very large epidemiological studies show that blue-blocking IOLs do not reduce the risk or progression of AMD. Additionally, blue-filtering IOLs or spectacles cannot decrease glare disability, because they decrease image and glare illuminance in the same proportion. Blue light is essential for older adults' scotopic photoreception needed to reduce the risk of nighttime falling and related injuries. It is also critical for circadian photoreception that is essential for good health, sleep and cognitive performance. Unfortunately, age-related pupillary miosis, retinal rod and ganglion cell photoreceptor degeneration and decreased outdoor activity all reduce the amount of healthful blue light available to older adults. Blue-restricting IOLs further reduce the available blue light at a time when older adults need it most. Patients and ophthalmologists are exposed to hypothesis-based advertisements for blue-filtering optical devices that suppress short wavelength light critical for vision in dim lighting and for good physical and mental health. Spectacle and intraocular lens selections should be based on scientific fact, not conjecture. Ideal IOLs should improve photoreception rather than limit it permanently. Practice efficiency, surgical convenience and physician-manufacturer relationships may eliminate a patient's opportunity to choose between colorless blue-transmitting IOLs and yellow-tinted, blue-restricting IOLs. Cataract surgeons ultimately determine whether their patients have the opportunity to make an informed choice about their future photoreception.

Assessing electronic device use behaviours in healthy adults: development and evaluation of a novel tool

BACKGROUND

Chronic exposure of the macula to blue light from electronic devices has been identified as a potential macular health concern. The impacts remain poorly investigated as no validated methods to capture usual device use behaviours exist.

PURPOSE

The aim of this study was to develop and validate the Electronic Device Use Questionnaire (EDUQ) against multiple 24-h electronic device use diaries in healthy Australian and United Kingdom adults.

METHODS

The EDUQ and diaries were developed to capture device use across categories (television, computer and handheld devices). Over eight weeks 56 Australian and 24 United Kingdom participants completed three questionnaires and eight diaries via online platforms. Tool validity was determined through Bland-Altman plot analysis of mean daily hours of device use between the tools.

RESULTS

The EDUQ demonstrated poor validity in both cohorts with poor agreement when compared with the diaries. When the device categories were combined, a mean difference between the tools of 1.54 h/day, and 95% limits of agreement between -2.72 h/day and 5.80 h/day was observed in the Australian cohort. Across both cohorts and all device categories the mean differences indicated individuals were more likely to report higher device use through the questionnaire rather than diaries.

CONCLUSIONS

The EDUQ is a novel tool and demonstrated the difficulty for participants of accurately recalling usual behaviour of device use. Poor agreement in reported device use occurred across all device categories. The poor agreement may be related to factors such as memory recall bias, and the number of diaries captured not being reflective of usual use. Future studies should look to address these factors to improve validity of device use capture.

Photoinactivation of the bacteriophage PhiX174 by UVA radiation and visible light in SM buffer and DMEM-F12

OBJECTIVE

It has been observed that viruses can be inactivated by UVA radiation and visible light. The aim of this study is to investigate whether a medium that contains a photosensitizer might have an influence on viral reduction under irradiation by UVA, violet or blue light. Test virus is the bacteriophage PhiX174 in the photosensitizer-free SM buffer and DMEM-F12, which contains the known photosensitizer riboflavin.

RESULTS

The determined PhiX174 D90 doses in SM buffer and DMEM were 36.8 J/cm² and 13.6 J/cm² at 366 nm, 153.6 J/cm² and 129.1 J/cm² at 408 nm and 4988 J/cm² and 2477.1 J/cm² at 455 nm, respectively. It can be concluded that the medium has a large influence on the results. This might be caused by the photosensitizer riboflavin in DMEM-F12. As riboflavin is a key component in many cell culture media, irradiation experiments with viruses in cell culture media should be avoided if the investigation of intrinsical photoinactivation properties of viruses is aimed for.

Measuring visual acuity and spherical refraction with smartphone screens emitting blue light

INTRODUCTION

A periodical self-monitoring of spherical refraction using smartphones may potentially allow a quicker intervention by eye care professionals to reduce myopia progression. Unfortunately, at low levels of myopia, the far point (FP) can be located far away from the eye which can make interactions with the device difficult. To partially remedy this issue, a novel method is proposed and tested wherein the longitudinal chromatic aberration (LCA) of blue light is leveraged to optically bring the FP closer to the eye.

METHODS

Firstly, LCA was obtained by measuring spherical refraction subjectively using blue pixels in stimuli shown on organic light-emitting diode (OLED) screens and also grey stimuli with matching luminance. Secondly, the visual acuity (VA) measured with a smartphone located at 1.0 m and 1.5 m and displaying blue optotypes was compared with that obtained clinically standard measurements. Finally, the spherical over refraction obtained in blue light with a smartphone was compared with clinical over-refraction with black and white (B&W) optotypes placed at 6 m.

RESULTS

Mean LCA of blue OLED smartphone screens was -0.67 ± 0.11 D. No significant differences (p > 0.05) were found between the VA measured with blue optotypes on a smartphone screen and an eye chart. Mean difference between spherical over-refraction measured subjectively by experienced subjects with smartphones and the one obtained clinically was 0.08 ± 0.34 D.

CONCLUSIONS

Smartphones using blue light can be used as a tool to detect changes in visual acuity and spherical refraction and facilitate monitoring of myopia progression.

Influence of different LED wavelengths on retinal melatonin levels - A rodent study

BACKGROUND

Retinal melatonin is crucial for neuroprotection. Exposure to light-emitting diodes (LEDs) affects retinal neurons, possibly influencing retinal melatonin levels. Hence, we aimed to quantify the retinal melatonin level with different LED wavelengths.

METHOD

A total of 24 Sprague Dawley (SD) male rats were divided into four groups (n = 6 in each group) as normal controls (NC), blue light (BL), white light (WL), and yellow light (YL). The rats in the experimental groups were exposed to different wavelengths of LEDs for 28 days (12:12 h light-dark cycle) with uniform illumination of 450-500 lx. Following exposure, the rats were subjected to behavioral tests such as passive avoidance and elevated plus maze tests. Following the behavior tests, the rats were sacrificed, eyes were enucleated, and retinal tissue was stored at -80 °C. The homogenized retina was used for reactive oxygen species (ROS) and melatonin quantification using an enzyme-linked immunosorbent assay (ELISA) kit.

RESULTS

Passive avoidance test revealed a significant difference across the groups (p < 0.0004). The BL exposure group demonstrated increased latency to enter the dark compartment (DC) and impaired motor memory. The elevated plus maze test revealed a significant difference across all the groups (p < 0.012), where the time spent in the closed arm was greater in the BL exposure group. Comparison of ROS levels revealed a significant difference across the groups (p < 0.0001), with increased nitric oxide concentrations in the experimental groups. Melatonin levels were significantly decreased in the light exposure groups (p < 0.0001) compared to the NC group.

CONCLUSION

Cumulative exposure to different LED wavelengths resulted in increased anxiety with impaired motor activity. This was also complemented by the addition of oxidative stress leading to decreased melatonin levels in the retina, which might trigger retinal neuronal damage.

Photobiomodulation effects of blue light on osteogenesis are induced by reactive oxygen species

Blue light-mediated photobiomodulation (PBM) is a promising approach to promote osteogenesis. However, the underlying mechanisms of PBM in osteogenesis are poorly understood. In this study, a human osteosarcoma cell line (i.e., Saos-2 cells) was subjected to intermittent blue light exposure (2500 µM/m2/s, 70 mW/cm2, 4.2 J/cm2, once every 48 h) and the effects on Saos-2 cell viability, metabolic activity, differentiation, and mineralization were investigated. In addition, this study addressed a possible role of blue light induced cellular oxidative stress as a mechanism for enhanced osteoblast differentiation and mineralization. Results showed that Saos-2 cell viability and metabolic activity were maintained upon blue light exposure compared to unilluminated controls, indicating no negative effects. To the contrary, blue light exposure significantly increased (p < 0.05) alkaline phosphatase activity and Saos-2 cell mediated mineralization. High-performance liquid chromatography (HPLC) assay was used for measurement of reactive oxygen species (ROS) activity and showed a significant increase (p < 0.05) in superoxide (O2•-) and hydrogen peroxide (H2O2) formed after blue light exposure. Together, these results suggest that the beneficial effects of blue light-mediated PBM on osteogenesis may be induced by controlled release of ROS.

pekinensis)

The aim of this study was to investigate the impact of long-term exposure to blue light-emitting diodes (LEDs) on the accumulation of indolic glucosinolates and carotenoids, as well as the plant growth and antioxidant activities in both orange and common Chinese cabbage (Brassica rapa L. ssp. pekinensis). Blue light treatment also induced higher ferric-reducing antioxidant power and 2,2-diphenyl-1-picrylhydrazyl by 20.66 % and 30.82 % and antioxidant enzyme activities catalase, peroxidase, superoxide dismutase, and the accumulation of non-enzymatic antioxidant substances (total phenols and total flavonoids) in the orange Chinese cabbage. Furthermore, long-term exposure to blue light had negative effects on the net photosynthetic rate and chlorophyll fluorescence levels. Meanwhile, blue light promoted accumulation of Indol-3-ylmethyl glucosinolate (I3M), β-carotene, lutein and zeaxanthin due to the high expression of regulatory and biosynthetic genes of the above metabolic pathways. In particular, lycopene and β-carotene content in orange Chinese cabbage increased by 60.14 % and 65.33 % compared to the ones in common line. The accumulation of carotenoid and increasing antioxidant levels in the orange cabbage line was influenced by long-term blue light irradiation, leading to better tolerance to low temperature and drought stresses. The up-regulation of transcription factors such as BrHY5-2, BrPIF4 and BrMYB12 may also contribute to the increased tolerance in orange Chinese cabbage to extreme environmental stresses. The BrHY5-2 gene could activate carotenoid biosynthetic genes and induce the accumulation of carotenoids. These findings suggested that long-term blue light irradiation could be a promising technique for increasing the nutrition value and enhancing tolerance to low temperature and drought stresses in Chinese cabbage.

An investigation of the influence of reactive oxygen species produced from riboflavin-5'-phosphate by blue or violet light on the inhibition of WiDr colon cancer cells

Riboflavin-5'-phosphate (FMN), an innocuous product of riboflavin (RF) phosphorylation, is vital for humans. FMN is sensitive to light illumination, as indicated by reactive oxygen species (ROS) formation. This investigation was undertaken to evaluate the influence of blue light illumination (BLI) and violet light illumination (VLI) upon FMN to develop a method to inhibit WiDr colon cancer cells by FMN photolysis. When FMN is subjected to BLI and VLI, it inhibits WiDr colon cancer cells by generating superoxide radical anions (O2•-). The respective reduction rates are 42.6 and 81.9 % in WiDr colon cancer cells for FMN treated with BLI and VLI at 20 W/m2 for 0.5 h. FMN treated with VLI inhibits WiDr colon cancer cells more effectively than BLI. Propidium iodide (PI) is a fluorescent dye that is used to detect abnormal DNA due to cell death by apoptosis or necrosis. The PI-positive count for nuclei increased significantly for the WiDr colon cancer cells that were treated with FMN under VLI at 20 W/m2 for 0.5 h. FMN photolysis achieved using VLI allows efficient photodynamic therapy (PDT) by triggering the cytotoxicity of FMN on WiDr colon cancer cells.

The Impact of Blue Light Cystoscopy Use Among Nonmuscle Invasive Bladder Cancer Patients in an Equal Access Setting: Implications on Recurrence and Time to Recurrence

INTRODUCTION

Prior studies suggest that white light cystoscopy (WLC) alone can fail to detect cases of non-muscle invasive bladder cancer (NMIBC) vs. blue light cystoscopy (BLC). We describe bladder cancer outcomes and the impact of BLC among NMIBC patients in an equal access setting.

MATERIALS AND METHODS

We assessed 378 NMIBC patients within the Veterans Affairs system that had a CPT code for BLC from December 1, 2014 to December 31, 2020. We determined recurrence rates and time to recurrence prior to BLC (ie, after previous WLC if available) and following BLC. We used the Kaplan-Meier method to estimate event-free survival and Cox regression to determine association between BLC and recurrence, progression, and overall survival; and further, whether these outcomes differed by race.

RESULTS

Of 378 patients with complete data, 43 (11%) were Black and 300 (79%) White. Median follow-up was 40.7 months from bladder cancer diagnosis. Median time to first recurrence following BLC was longer vs. WLC alone (40 [33-NE] vs. 26 [17-39] months). Recurrence risk was significantly lower following BLC (Hazard Ratio [HR] 0.70; 95% Confidence Interval [CI], 0.54-0.90). There was no significant difference in recurrence (HR 0.69; 95% CI, 0.39-1.20), progression (HR 1.13; 95% CI, 0.32-3.96), and overall survival (HR 0.74; 95% CI, 0.31-1.77) following BLC by Black vs. White race.

CONCLUSION

In this study from an equal access setting in the VA, we observed significantly decreased recurrence risk and prolonged time interval to recurrence following BLC vs. WLC alone. There was no difference in bladder cancer outcomes by race.

Impact of varying light spectral compositions on photosynthesis, morphology, chloroplast ultrastructure, and expression of light-responsive genes in Marchantia polymorpha

Marchantia polymorpha is a convenient model for studying light of different spectral compositions on various physiological and biochemical processes because its photoreceptor system is vastly simplified. The influence of red light (RL, 660 nm), far-red light (FRL, 730 nm), blue light (BL, 450 nm), and green light (GL, 525 nm) compared to white light (high-pressure sodium light (HPSL), white LEDs (WL 450 + 580 nm) and white fluorescent light (WFL) on photosynthetic and transpiration rates, photosystem II (PSII) activity, photomorphogenesis, and the expression of light and hormonal signaling genes was studied. The ultrastructure of the chloroplasts in different tissues of the gametophyte M. polymorpha was examined. FRL led to the formation of agranal chloroplasts (in the epidermis and the chlorenchyma) with a high starch content (in the parenchyma), which led to a reduced intensity of photosynthesis. BL increased the transcription of genes for the biosynthesis of secondary metabolites - chalcone synthase (CHS), cellulose synthase (CELL), and L-ascorbate peroxidase (APOX3), which is consistent with the increased activity of low-molecular weight antioxidants. FRL increased the expression of phytochrome apoprotein (PHY) and cytokinin oxidase (CYTox) genes, but the expression of the phytochrome interacting factor (PIF) gene decreased, which was accompanied by a significant change in gametophyte morphology. Analysis of crosstalk gene expression, and changes in morphology and photosynthetic activity was carried out.

Effects of blue light exposure on ocular parameters and choroidal blood perfusion in Guinea pig

PURPOSE

To investigate the impact of different duration of blue light exposure on ocular parameters and choroidal blood perfusion in guinea pigs with lens-induced myopia.

METHOD

Three-week-old Guinea pigs were randomly assigned to different light-environment groups. All groups were subjected to 12-h light/dark cycle. The control (NC) group was conditioned without intervention. While lens-induced myopia (LIM) groups had a -10D lens placed in the right eye and 0D in the left eye. The guinea pigs were exposed to increasing periods of blue-light (420 nm) environment for 3,6,9,12 h per day. Changes in refraction, axial length (AL), the radius of corneal curvature (CCR), choroidal thickness (ChT), and choroidal blood perfusion (ChBP)were measured in both LIM-eye and fellow-eye during the second and fourth week of LIM duration.

RESULTS

During the first two weeks of the experiment, blue light exposure raised ChBP and ChT, and the effect of suppressing myopia was proportional to the duration of blue light exposure. However, in the fourth week of the experiment, prolonged blue light (12BL) exposure led to a reduction in retinal thickness and the increase in ChT and ChBP ceased. Shorter blue light exposure had a better effect on myopia suppression, with all blue light groups statistically different from the LIM group.

CONCLUSION

Exposure to blue-light appears to have the potential to improve ChBP and ChT, thereby inhibiting the development of myopia. we speculate that blue-light inhibits the development of myopia for reasons other than longitudinal chromatic aberration (LCA). However,long-term exposure to blue-light may have adverse effects on ocular development. The next step is to investigate in depth the mechanisms by which the rational use of blue light regulates choroidal blood flow, offering new hope for the treatment of myopia.

Using photon disinfection technologies for reducing bioburden in hospitals

BACKGROUND

Environmental cleaning and disinfection is the basis of the prevention of healthcare-acquired infections (HAIs).

AIM

This study aimed to describe photon disinfection technologies (PDTs), report their impact on inactivating micro-organisms and preventing HAIs and to create recommendations for their implementation in hospital settings.

METHODS

An integrated literature review was completed to evaluate and report the impact of PDTs in hospital settings. The quality of 23 articles were assessed, their contents analysed and results reported according to the PICOT model.

FINDINGS

The microbiological impact of the PDT varied by micro-organism, settings and according to the used devices. It was crucial that environmental cleaning was completed before the disinfection.

CONCLUSION

The implementation of PDT in the hospital setting requires inquiry from the viewpoints of microbiological, environmental, occupational, technical and human safety. To enhance the safe implementation of PDTs, the construction and use of evidence-based global standards for PDT are crucial.

Increased ocular dopamine levels in rabbits after blue light stimulation of the optic nerve head

The purpose was to quantify ocular dopamine in rabbits after stimulation of the optic nerve head with short-wavelength (blue) light to activate melanopsin expressed in the axons of intrinsically photosensitive retinal ganglion cells (ipRGCs). Dopamine levels in tears, aqueous humor, vitreous body, and retina (including choroid) were quantified after blue light stimulation of the optic nerve head of 15 rabbits with an optical fiber for 1 min, 10 min, or no stimulation (n = 5, each group). The left eye of all rabbits was operated on to introduce the optical fiber and stimulate the optic nerve, while the contralateral eye served as internal control. One minute of blue light stimulation significantly increased dopamine concentration in the vitreous body of the treated eyes compared to the contralateral ones (P = 0.015). Stimulation for 10 min significantly increased dopamine concentration in the vitreous body, as well as the aqueous humor (P < 0.05). Therefore, using an optical fiber approach to stimulate the optic nerve head with blue light significantly increased dopamine concentration in the aqueous humor and the vitreous body. This likely reflects an upregulation of retinal dopamine synthesis that could be attributed to ipRGC activation. However, the data provided in this study fell short of establishing a definitive link between dopamine release and ipRGC activation, mainly due to the lack of evidence supporting the expression of the melanopsin photopigment in the optic nerve.

Induced skin aging by blue-light irradiation in human skin fibroblasts via TGF-β, JNK and EGFR pathways

BACKGROUND

Studies indicate that blue light (BL) irradiation can damage human skins, but the impact of BL irradiation on skin aging is unknown.

OBJECTIVES

This study aimed to give an insight to phenotypic characteristics and molecular mechanism of blue light-induced skin aging, and thus provide a theoretical basis for the precise protection of photodermatosis.

METHODS

The effect of BL on skin photoaging in mice was evaluated by non-invasive measurement equipment and histopathology analysis. The effect of BL irradiation on the proliferation of HFF-1 cells was detected by the Real-Time Cell Analyzer. The expression and protein levels of genes associated with skin aging were examined.

RESULTS

Our studies indicated photoaging caused by BL irradiation, including collagen disorder and increased MMP1. BL irradiation also inhibited cell proliferation and collagen expression in human skin fibroblasts by inhibiting TGF-β signaling pathway, based on in vitro experiments. Importantly, BL irradiation promoted the degradation of collagen by increasing MMP1 activated by the JNK/c-Jun and EGFR pathways. Moreover, ROS levels were significantly increased after BL irradiation in human skin fibroblasts. Yet, the transcriptional change in human skin fibroblasts caused by BL irradiation was unable to be completely restored by ROS scavenger.

CONCLUSION

BL irradiation down-regulated expression of type I collagen genes and up-regulated MMP1 expression to inhibit the proliferation of human skin fibroblasts. Multiple key pathways including TGF-β, JNK, and EGFR signaling were involved in BL-induced skin aging. Our results provide theoretical bases for the protection of photoaging caused by BL irradiation.

Blue light promotes vitamin C-mediated ferroptosis of melanoma through specifically upregulating transporter SVCT2 and generating Fe2

Vitamin C (VC)-based cancer therapy is a promising therapeutic approach for a variety of cancers due to its profound effects on redox reactions and metabolic pathways. However, high administration dosage of VC for necessary therapeutic efficacy for cancers increases the risk of overt side effects and limits its clinical use. Here, we show cutaneous blue light irradiation can specifically upregulate the sodium-dependent vitamin C transporter 2 (SVCT2) of the tumor and increase effectively the VC concentration at the tumor sites by an overall low dosage administration. In the mouse melanoma model, blue light stimulates the SVCT2 expression through the nuclear factor-kappa B (NF-κB) signaling pathway both in vitro and in vivo. The increased cellular VC together with Fe2+ generated by blue light simultaneously elevate cellular oxidative stress and trigger the ferroptosis of melanoma. With this revealed mechanism, the synergistic actions of blue light on the VC transporter and Fe2+ generation lead to a ca. 20-fold reduction in the administration dosage of VC with an effective melanoma elimination and prolonged survival. The work defines the killing mechanism of blue light on VC-based cancer therapy and provides a practical approach for promoting VC uptake. This light-assisted VC therapy is not only highly efficient for melanoma but also considerable for a broad clinical utility.

Two types of GLR channels cooperate differently in light and dark growth of Arabidopsis seedlings

BACKGROUND

GLutamate Receptor-like (GLR) channels are multimeric, ionotropic, ligand-gated plant transmembrane receptors. They are homologous to mammalian glutamate receptors, iGLuRs, which are critical to neuronal function. GLRs have been reported several times to play a role in photomorphogenesis. However, to date, no study has looked at the mechanism of their involvement in this process. Here we focused on examining the impact of GLRs on the regulation of early seedling growth in blue light, red light, and in the dark.

RESULTS

Wild type and six photoreceptor mutant seedlings were grown on media supplemented with known iGLuR/GLR channel antagonists: MK-801, which non-competitively blocks NMDA channels in mammalian cells, and CNQX, known for competitive blocking of AMPA channels in mammalian cells. The lengths of hypocotyls and roots were measured in seedlings of phyA, phyB, phot1, phot2, cry1, and cry2 mutants after 7 days of in vitro culture. Changes in growth parameters, both in light and in darkness upon application of chemical antagonists, show that both types of GLR channels, NMDA-like and AMPA-like, are involved in the regulation of seedling growth irrespective of light conditions. Analysis of seedling growth of photoreceptor mutants indicates that the channels are influenced by signaling from phot1, phot2, and cry1. To extend our analysis, we also evaluated the elicitation of a calcium wave, which is likely to be partially driven by GLRs, in Arabidopsis seedlings. The changes in cellobiose-induced calcium waves observed after applying GLR inhibitors suggest that both types of channels likely cooperate in shaping Arabidopsis seedling growth and development.

CONCLUSIONS

Our work provides the first experimental evidence that two types of GLR channels function in plants: NMDA-like and AMPA-like. We also demonstrate that the channels are involved in seedling growth and development, at least partially through modulation of calcium signaling, but they are unlikely to play a major role in photomorphogenesis.

Integration of blue light with near-infrared irradiation accelerates the osteogenic differentiation of human dental pulp stem cells

Blue light is used less in photobiomodulation than red or near-infrared light because of concerns about its high energy. However, some reports have suggested that blue light releases NO from nitrosated proteins, affects cell signal regulation, and promotes stem cell differentiation. Because blue and red lights could have different mechanisms of action, their combination is expected to have new consequences. In this study, human dental pulp stem cells (hDPSCs) were sequentially exposed to blue and near-infrared light to study their effects on proliferation, osteogenic differentiation, and immunomodulation. We found that NIR irradiation applied after blue light can reduce blue light toxicity improving the cell viabiltiy. Delayed luminescence and transmission electron microscopy studies showed that this combination excited hDPSCs and activated mitochondrial biogenesis. Those modulations accelerated hDPSC differentiation, as shown by an increase of about 1.3-fold in alkaline phosphatase activity in vitro and an about 1.5-fold increase in the osteocalcin-positive regions in cells implanted in nude mice compared with mice exposed to near-infrared alone.

The effects of short term blue light treatment on promoting nutrition value in Chinese cabbage

Chinese cabbage is a nutrients-rich vegetable with diverse leaf colors. Here, we used widely-targeted metabolomics technology to study the metabolic responses of three Chinese cabbage varieties with representative leaf colors after blue light treatment. The inner leaf color of orange varieties 20S530 and 15S1094 changed from yellow to golden yellow, while no visible color change occurred in the common variety 14S23 after the treatment. A total of 844 metabolites were measured from the leaf samples of these three varieties in a time course study after short term blue light treatment, with kaempferol-4'-O-glucoside, isoquercitrin, hyperin, arbutin, sulforaphane as enriched nutritional metabolites. Orange Chinese cabbage varieties showed additional nutrition enhancement after the treatment. This study is the first to explore the global metabolic responses of Chinese cabbage after blue light treatment, and our findings provided valuable insights on how to effectively use lighting conditions to enhance specific groups of nutrients in vegetables.

The inhibitory and inactivating effects of visible light on SARS-CoV-2: A narrative update

Prior to the coronavirus disease-19 (COVID-19) pandemic, the germicidal effects of visible light (λ = 400 - 700 nm) were well known. This review provides an overview of new findings that suggest there are direct inactivating effects of visible light - particularly blue wavelengths (λ = 400 - 500 nm) - on exposed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virions, and inhibitory effects on viral replication in infected cells. These findings complement emerging evidence that there may be clinical benefits of orally administered blue light for limiting the severity of COVID-19. Possible mechanisms of action of blue light (e.g., regulation of reactive oxygen species) and important mediators (e.g., melatonin) are discussed.

Molecular characterization of a flavanone 3-hydroxylase gene from citrus fruit reveals its crucial roles in anthocyanin accumulation

BACKGROUND

Flavanone 3-hydroxylase (F3H), a key enzyme in the flavonoid biosynthetic pathway, plays an important role in the regulation of flavonols and anthocyanidins accumulation. Citrus fruit is a rich source of flavonoids with varied flavonoid compositions among different varieties. To date, the study on F3H is limited in citrus, and its roles in regulating flavonoid accumulation in citrus fruit are still unclear.

RESULTS

In this study, we isolated a CitF3H from three different citrus varieties, Satsuma mandarin (Citrus unshiu Marc.), Ponkan mandarin (C. reticulata Blanco) and blood orange 'Moro' (C. sinensis Osbeck). Functional analysis showed that CitF3H encoded a functional flavanone 3-hydroxylase. It catalyzed the hydroxylation of naringenin to yield dihydrokaempferol, which was a precursor of anthocyanins in flavonoid biosynthetic pathway. In the juice sacs, CitF3H was differentially expressed among the three citrus varieties, and its expression level was positively correlated with the accumulation of anthocyanins during the ripening process. In the juice sacs of Satsuma mandarin and Ponkan mandarin the expression of CitF3H kept constant at an extremely low level, and no anthocyanin was accumulated during the ripening process. In contrast, the expression of CitF3H increased rapidly along with the accumulation of anthocyanin in the juice sacs of blood orange 'Moro' during the ripening process. In addition, we found that blue light irradiation was effective to up-regulate the expression of CitF3H and improve anthocyanin accumulation in the juice sacs of blood orange 'Moro' in vitro.

CONCLUSION

CitF3H was a key gene regulating anthocyanin accumulation in the juice sacs of citrus fruit. The results presented in this study will contribute to elucidating anthocyanin biosynthesis in citrus fruit, and provide new strategies to improve the nutritional and commercial values of citrus fruit.

Blue light exposure collapses the inner blood-retinal barrier by accelerating endothelial CLDN5 degradation through the disturbance of GNAZ and the activation of ADAM17

Blue light is part of the natural light spectrum that emits high energy. Currently, people are frequently exposed to blue light from 3C devices, resulting in a growing incidence of retinopathy. The retinal vasculature is complex, and retinal vessels not only serve the metabolic needs of the retinal sublayers, but also maintain electrolyte homeostasis by forming the inner blood-retinal barrier (iBRB). The iBRB, which is primarily composed of endothelial cells, has well-developed tight junctions. However, with exposure to blue light, the risks of targeting retinal endothelial cells are currently unknown. We found that endothelial claudin-5 (CLDN5) was rapidly degraded under blue light, coinciding with the activation of a disintegrin and metalloprotease 17 (ADAM17), even at non-cytotoxic lighting. An apparently broken tight junction and a permeable paracellular cleft were observed. Mice exposed to blue light displayed iBRB leakage, conferring attenuation of the electroretinogram b-wave and oscillatory potentials. Both pharmacological and genetic inhibition of ADAM17 remarkably alleviated CLDN5 degradation induced by blue light. Under untreated condition, ADAM17 is sequestered by GNAZ (a circadian-responsive, retina-enriched inhibitory G protein), whereas ADAM17 escapes from GNAZ by blue light illuminance. GNAZ knockdown led to ADAM17 hyperactivation, CLDN5 downregulation, and paracellular permeability in vitro, and retinal damage mimicked blue light exposure in vivo. These data demonstrate that blue light exposure might impair the iBRB by accelerating CLDN5 degradation through the disturbance of the GNAZ-ADAM17 axis.

Clinical Evaluation of a Modified Light Transmission Short-Wavelength Filtering Intraocular Lens Compared to a Colorless Control

INTRODUCTION

The aim of this study was to evaluate the safety and efficacy of a violet-light filtering intraocular lens (IOL) compared to a colorless IOL control.

METHODS

This was a prospective, bilateral, randomized, comparative, patient/evaluator-masked multi-center clinical trial at 12 sites in the USA. Patients underwent standard small-incision phacoemulsification cataract extraction. Visual acuity, contrast sensitivity, and color vision were tested 12 months postoperatively. Patient satisfaction and vision-related quality of life were evaluated based on directed patient responses obtained from a binocular subjective questionnaire.

RESULTS

A total of 250 subjects were bilaterally implanted with the violet-light filtering TECNIS monofocal ZV9003 (n = 126) and colorless TECNIS monofocal ZA9003 (n = 124). Mean uncorrected distance visual acuity (UDVA) was 0.123 LogMAR for ZV9003 and 0.116 LogMAR for the ZA9003 group. Mean corrected distance visual acuity (CDVA) was 0.00 LogMAR for both groups. No significant difference was found between the groups for 22/25 questionnaire categories, including color perception. A significant difference was found in favor of the ZV9003 group for day driving, night driving, and frustration with vision. Contrast sensitivity mean difference was < 0.05 log units across all lighting conditions and spatial frequencies.

CONCLUSION

No difference was found between groups for visual acuity, contrast sensitivity, color testing, and adverse events as well as with the majority of optical/visual symptoms. A statistical difference was noted in driving and frustration with eyesight that may be related to benefits of using a violet-light filtering chromophore. Overall, the violet-light filtering ZV9003 showed excellent visual acuity and contrast sensitivity results with a low incidence of optical/visual symptoms.

Blue LED light induces cytotoxicity via ROS production and mitochondrial damage in bovine subcutaneous preadipocytes

The purpose of this study was to investigate the effect and mechanism of blue light irradiation on bovine subcutaneous preadipocytes. In this study, preadipocytes were divided into dark group (control) and blue light group. Results show that blue light exposure time-dependently reduced the viability of preadipocytes and induced mitochondrial damage, in accompaniment with the accumulation of intracellular reactive oxygen species (ROS). Meanwhile, blue light caused oxidative stress, as evidenced by the increased MDA level, the reduced T-AOC contents, as well as the decreased activities of antioxidant enzymes. Additionally, blue light treatment induced apoptosis and G2/M phase arrest via Bcl-2/Bax/cleaved caspase-3 pathway and P53/GADD45 pathway, respectively. Protein expressions of LC3-II/LC3-I and P62 were up-regulated under blue light exposure, indicating blue light initiated autophagy but impeded autophagic degradation. Moreover, blue light caused an increase in the secretion of pro-inflammatory factors (TNF-α, IL-1β, and IL-6). Pretreatment with N-acetylcysteine (NAC), a potent ROS scavenger, restored the loss of mitochondrial membrane potential (Δψ) and reduced excess ROS. Additionally, the above negative effects of blue light on cells were alleviated after NAC administration. In conclusion, this study demonstrates blue light induces cellular ROS overproduction and Δψ depolarization, resulting in the decrease of cell viability and the activation of apoptosis, autophagy, and inflammation, providing a reference for the application of blue light in the regulation of fat cells in the future.

Response of genes related to iron and porphyrin transport in Porphyromonas gingivalis to blue light

BACKGROUND

Antimicrobial blue light (aBL) kills a variety of bacteria, including Porphyromonas gingivalis. However, little is known about the transcriptomic response of P. gingivalis to aBL therapy. This study was designed to evaluate the selective cytotoxicity of aBL against P. gingivalis over human cells and to further investigate the genetic response of P. gingivalis to aBL at the transcriptome level.

METHODS

Colony forming unit (CFU) testing, confocal laser scanning microscopy (CLSM), and scanning electron microscopy (SEM) were used to investigate the antimicrobial effectiveness of blue light against P. gingivalis. The temperatures of the irradiated targets were measured to prevent overheating. Multiple fluorescent probes were used to quantify reactive oxygen species (ROS) generation after blue-light irradiation. RNA sequencing (RNA-seq) was used to investigate the changes in global gene expression. Following the screening of target genes, real-time quantitative polymerase chain reaction (RT-qPCR) was performed to confirm the regulation of gene expression.

RESULTS

A 405 nm aBL at 100 mW/cm² significantly killed P. gingivalis within 5 min while sparing human gingival fibroblasts (HGFs). No obvious temperature changes were detected in the irradiated surface under our experimental conditions. RNA-seq showed that the transcription of multiple genes was regulated, and RT-qPCR revealed that the expression levels of the genes RgpA and RgpB, which may promote heme uptake, as well as the genes Ftn and FetB, which are related to iron homeostasis, were significantly upregulated. The expression levels of the FeoB-2 and HmuR genes, which are related to hydroxyl radical scavenging, were significantly downregulated.

CONCLUSIONS

aBL strengthens the heme uptake and iron export gene pathways while reducing the ROS scavenging pathways in P. gingivalis, thus improving the accumulation of endogenous photosensitizers and enhancing oxidative damage to P. gingivalis.

Blue Light Exposure: Ocular Hazards and Prevention-A Narrative Review

INTRODUCTION

Exposure to blue light has seriously increased in our environment since the arrival of light emitting diodes (LEDs) and, in recent years, the proliferation of digital devices rich in blue light. This raises some questions about its potential deleterious effects on eye health. The aim of this narrative review is to provide an update on the ocular effects of blue light and to discuss the efficiency of methods of protection and prevention against potential blue light-induced ocular injury.

METHODS

The search of relevant English articles was conducted in PubMed, Medline, and Google Scholar databases until December 2022.

RESULTS

Blue light exposure provokes photochemical reactions in most eye tissues, in particular the cornea, the lens, and the retina. In vitro and in vivo studies have shown that certain exposures to blue light (depending on the wavelength or intensity) can cause temporary or permanent damage to some structures of the eye, especially the retina. However, currently, there is no evidence that screen use and LEDs in normal use are deleterious to the human retina. Regarding protection, there is currently no evidence of a beneficial effect of blue blocking lenses for the prevention of eye diseases, in particular age-related macular degeneration (AMD). In humans, macular pigments (composed of lutein and zeaxanthin) represent a natural protection by filtering blue light, and can be increased through increased intake from foods or food supplements. These nutrients are associated with lower risk for AMD and cataract. Antioxidants such as vitamins C, E, or zinc might also contribute to the prevention of photochemical ocular damage by preventing oxidative stress.

CONCLUSION

Currently, there is no evidence that LEDs in normal use at domestic intensity levels or in screen devices are retinotoxic to the human eye. However, the potential toxicity of long-term cumulative exposure and the dose-response effect are currently unknown.

Long-term blue light rearing does not affect in vivo retinal function in young rhesus monkeys

PURPOSE

Exposure to blue light is thought to be harmful to the retina. The purpose of this study was to determine the effects of long-term exposure to narrowband blue light on retinal function in rhesus monkeys.

METHODS

Young rhesus monkeys were reared under short-wavelength "blue" light (n = 7; 465 nm, 183 ± 28 lx) on a 12-h light/dark cycle starting at 26 ± 2 days of age. Age-matched control monkeys were reared under broadband "white" light (n = 8; 504 ± 168 lx). Light- and dark-adapted full-field flash electroretinograms (ERGs) were recorded at 330 ± 9 days of age. Photopic stimuli were brief red flashes (0.044-5.68 cd.s/m²) on a rod-saturating blue background and the International Society for Clinical Electrophysiology of Vision (ISCEV) standard 3.0 white flash on a 30 cd/m² white background. Monkeys were dark adapted for 20 min and scotopic stimuli were ISCEV standard white flashes of 0.01, 3.0, and 10 cd.s/m². A-wave, b-wave, and photopic negative response (PhNR) amplitudes were measured. Light-adapted ERGs in young monkeys were compared to ERGs in adult monkeys reared in white light (n = 10; 4.91 ± 0.88 years of age).

RESULTS

For red flashes on a blue background, there were no significant differences in a-wave (P = 0.46), b-wave (P = 0.75), and PhNR amplitudes (P = 0.94) between white light and blue light reared monkeys for all stimulus energies. ISCEV standard light- and dark-adapted a- and b-wave amplitudes were not significantly different between groups (P > 0.05 for all). There were no significant differences in a- and b-wave implicit times between groups for all ISCEV standard stimuli (P > 0.05 for all). PhNR amplitudes of young monkeys were significantly smaller compared to adult monkeys for all stimulus energies (P < 0.05 for all). There were no significant differences in a-wave (P = 0.19) and b-wave (P = 0.17) amplitudes between young and adult white light reared monkeys.

CONCLUSIONS

Long-term exposure to narrowband blue light did not affect photopic or scotopic ERG responses in young monkeys. Findings suggest that exposure to 12 h of daily blue light for approximately 10 months does not result in altered retinal function.

microgreens

Ligusticum chuanxiong Hort. (Chuanxiong) is an important Chinese medicinal herb, whose rhizomes are widely used as raw materials for treating various diseases caused by blood stasis. The fresh tender stems and leaves of Chuanxiong are also consumed and have the potential as microgreens. Here, we investigated the effect of light spectra on yield and total flavonoid content of Chuanxiong microgreens by treatment with LED-based white light (WL), red light (RL), blue light (BL), and continuous darkness (DD). The results showed that WL and BL reduced biomass accumulation but significantly increased total flavonoid content compared to RL or DD treatments. Widely targeted metabolomics analysis confirmed that BL promoted the accumulation of flavones and flavonols in Chuanxiong microgreens. Further integration of transcriptomics and metabolomics analysis revealed the mechanism by which BL induces the up-regulation of transcription factors such as HY5 and MYBs, promotes the expression of key genes targeted for flavonoid biosynthesis, and ultimately leads to the accumulation of flavones and flavonols. This study suggests that blue light is a proper light spectra to improve the quality of Chuanxiong microgreens, and the research results lay a foundation for guiding the de-etiolation of Chuanxiong microgreens to obtain both yield and quality in production practice.

Long-term blue light exposure impairs mitochondrial dynamics in the retina in light-induced retinal degeneration in vivo and in vitro

Long-term light exposure, especially in the spectrum of blue light, frequently causes excessive oxidative stress in dry age-related macular degeneration (AMD). Here, to gain insight into the underlying mechanism, we focused on mitochondrial dynamics alterations under long-term exposure to blue light in mouse and retinal cells. Six-month-old C57BL/6 mice were exposed to blue light (450 nm, 800 lx) for 2 weeks. The phenotypic changes in the retina were assayed using haematoxylin-eosin staining and transmission electron microscopy. Long-term blue light exposure significantly thinned each retinal layer in mice, induced retinal apoptosis and impaired retinal mitochondria. A retinal pigment epithelial cell line (ARPE-19) was used to verify the phototoxicity of blue light. Flow cytometry, immunofluorescence and MitoSox Red probe experiments confirmed that more total and mitochondria-specific ROS were generated in the blue light group than in the control group. Mito-Tracker Green probe showed fragmented mitochondrial morphology. The western blotting results indicated a significant increase in DRP1, OMA1, and BAX and a decrease in OPA1 and Bcl-2. In conclusion, long-term exposure to blue light damaged the retinas of mice, especially the ONL and RPE cells. There was destruction and dysfunction of mitochondria in RPE cells in vivo and in vitro. Mitochondrial dynamics were disrupted with characteristics of fusion-related obstruction after blue-light irradiation.

Translational activation of ribosome-related genes at initial photoreception is dependent on signals derived from both the nucleus and the chloroplasts in Arabidopsis thaliana

Light is one of the indispensable elements that plants need in order to grow and develop. In particular, it is essential for inducing morphogenesis, such as suppression of hypocotyl elongation and cotyledon expansion, that plants undergo when they first emerge after germination. However, there is a lack of knowledge about the gene expression and, in particular, the translational levels that induce a response upon light exposure. We have investigated the translational expression of nuclear genes in Arabidopsis thaliana seedlings germinated in the dark and then exposed to blue monochromatic light. In this study, ribosome profiling analysis was performed in the blue-light-receptor mutant cry1cry2 and the light-signaling mutant hy5 to understand which signaling pathways are responsible for the changes in gene expression at the translational level after blue-light exposure. The analysis showed that the expression of certain chloroplast- and ribosome-related genes was up-regulated at the translational level in the wild type. However, in both mutants the translational up-regulation of ribosome-related genes was apparently compromised. This suggests that light signaling through photoreceptors and the HY5 transcription factor are responsible for translation of ribosome-related genes. To further understand the effect of photoreception by chloroplasts on nuclear gene expression, chloroplast function was inhibited by adding a photosynthesis inhibitor, 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), and a carotenoid synthesis inhibitor, norflurazon. The results show that inhibition of chloroplast function did not lead to an increase in the expression of ribosome-related genes at the translational level. These results suggest that signals from both the nucleus and chloroplasts are required to activate translation of ribosome-related genes during blue-light reception.

Laparoscopic fluorescence imaging technique for visualizing biliary structures using sodium fluorescein: the result of a preclinical study in a porcine model

Purpose

Near-infrared fluorescence imaging has been recently applied in the field of hepatobiliary surgery. Our objective was to apply blue-light fluorescence cholangiography during laparoscopic surgery. Therefore, we designed a preclinical study to evaluate the feasibility of using blue-light fluorescence for cholangiography in a porcine model.

Methods

Five millimeters of sodium fluorescein (SF) solution was administered into the gallbladder of 20 male 3-way crossbred (Landrace × Yorkshire × Duroc) pigs in laparoscopic approach. The biliary tree was observed under blue light (a peak wavelength of 450 nm) emitted from a commercialized light-emitting diode (LED) light source (XLS1 extreme, Chammed).

Results

In 18 of 20 porcine models, immediately after SF solution was administered into the gallbladder, it was possible to visualize the biliary tree under blue light emitted from the LED light source.

Conclusion

This study provided a preclinical basis for using blue-light fluorescence cholangiography using SF in laparoscopic surgery. The clinical feasibility of blue-light fluorescence imaging techniques for laparoscopic cholecystectomy remained to be demonstrated.

Blue light irradiation exerts anti-viral and anti-inflammatory properties against herpes simplex virus type 1 infection

The aim of this study was to investigate the antiviral and anti-inflammatory functions of blue light (BL) in cutaneous viral infections. Previously, we examined the photo-biogoverning role of 450 nm BL in SARS-CoV-2-infected cells, which showed that photo-energy could inhibit viral activation depending on the number of photons. However, the communication network between photo-energy irradiation and immune cells involved in viral infections has not been clarified. We verified viral activation, inflammatory responses, and relevant downstream cascades caused by human simplex virus type I (HSV-1) after BL irradiation. To examine the antiviral effect of BL, we further tested whether BL could disturb viral absorption or entry into host cells. The results showed that BL irradiation, but not green light (GL) exposure, specifically decreased plaque-forming activity and viral copy numbers in HSV-1-infected cells. Accumulated BL irradiation inhibited the localization of viral proteins and the RNA expression of characteristic viral genes such as UL19, UL27, and US6, thus exerting to an anti-viral effect. The results also showed that BL exposure during viral absorption interfered with viral entry or destroyed the virus, as assessed by plaque formation and quantitative PCR assays. The levels of the pro-inflammatory mediators interleukin (IL)-18 and IL-1β in M1-polarized macrophages were increased by HSV-1 infection. However, these increases were attenuated by BL irradiation. Importantly, BL irradiation decreased cGAS and STING expression, as well as downstream NF-κB p65, in M1-polarized HSV-1-infected macrophages, demonstrating anti-viral and anti-inflammatory properties. These findings suggest that BL could serve as an anti-viral and anti-inflammatory therapeutic candidate to treat HSV-1 infections.

Blue light-induced lipid oxidation and the antioxidant property of hypotaurine: evaluation via measuring ultraweak photon emission

The effects of blue light on human body have attracted attention. The human skin in contact with the outside environment is often exposed to blue light, and the effects of this exposure remain to be fully determined. Therefore, in this study, we investigated the effect of blue light, at the intensity typically found in sunlight, on lipids in the skin from an oxidation perspective. Peroxide value (POV) and ultraweak photon emission (UPE) measurements were conducted to evaluate lipid oxidation. Our results confirmed that blue light irradiation induced lipid oxidation, similar to ultraviolet A (UVA) irradiation. Also, the effects of various reagents on the blue light-induced UPE were evaluated; however, the results differed from those of the DPPH radical-scavenging ability. We speculated that this is due to the difference in the evaluation principle; nevertheless, among reagents, hypotaurine not only showed a high antioxidant effect but was also more effective against blue light-induced oxidation than UVA. Based on the difference in the antioxidant effect of the lipid sample in this study, the oxidation reaction induced by blue light may be different from the UVA-induced reaction. Our study provides new insights into the effects of blue light on lipids in the human skin, thereby promoting research regarding photooxidation.

The cutaneous effects of blue light from electronic devices: a systematic review with health hazard identification

The biologic effects of visible light, particularly blue light, on the skin at doses and irradiances representative of sunlight have been established. Recent research studies investigated the effects of blue light (BL) from electronic screen devices; however, it is unclear if the evidence can be generalized to real life. The aim of this systematic review was to evaluate available evidence regarding clinical effects of BL emitted from electronic devices on human skin using the framework established by the Office of Health Assessment and Translation (OHAT). A systematic literature search was conducted by two librarians in Ovid MEDLINE, Embase.com, and Web of Science for relevant articles published from 1946 to March 2022. In vitro and in vivo studies that investigated the effects of BL from electronic devices on skin were included. From the 87 articles gathered from database searches and 1 article identified from citation search, only 9 met the inclusion criteria (6 in vitro and 3 in vivo studies). Human and animal literature with the highest level of evidence ratings were considered with mechanistic data to form one of five human hazard identifications for each outcome category using the OHAT protocol: (1) known, (2) presumed, (3) suspected, (4) not classifiable, or (5) not identified to be a hazard to humans. Literature-based evidence integration did not identify exposure to BL from electronic devices as a hazard to skin pigmentation, redness, yellowness, or melasma exacerbation. Exposure to BL from electronic devices was not classified as a skin photoaging hazard. Low confidence in representative exposure characterization drove high OHAT risk-of-bias ratings for the majority of included studies. While these conclusions hold true for the limited existing data, a larger number of future studies with high-confidence evidence are needed to verify and strengthen hazard identification conclusions.

l-Tryptophan synergistically increased carotenoid accumulation with blue light in maize (Zea mays L.) sprouts

In the present study, l-tryptophan was applied in combination with blue light to modulate carotenoid biosynthesis in maize sprouts. The profiles of carotenoids, chlorophylls, and relative genes in carotenoid biosynthesis and light signaling pathways were studied. l-tryptophan and blue light both promoted the accumulation of carotenoids, and their combination further increased carotenoid content by 120%. l-tryptophan exerted auxin-like effects and stimulated PSY expression in blue light exposure maize sprouts, resulting in increased α- and β- carotenes. l-tryptophan could also play a photoprotective role through the xanthophyll cycle under blue light. In addition, CRY in the light signaling pathway was critical for carotenoid biosynthesis. These findings provide new insights into the regulation of carotenoid biosynthesis and l-tryptophan could be used in conjunction with blue light to fortify carotenoids in maize sprouts.