Summary Background Although the germicidal properties of ultraviolet (UV) light have long been known, it is only comparatively recently that the antimicrobial properties of visible violet–blue 405 nm ...light have been discovered and used for environmental disinfection and infection control applications. Aim To review the antimicrobial properties of 405 nm light and to describe its application as an environmental decontamination technology with particular reference to disinfection of the hospital environment. Methods Extensive literature searches for relevant scientific papers and reports. Findings A large body of scientific evidence is now available that provides underpinning knowledge of the 405 nm light-induced photodynamic inactivation process involved in the destruction of a wide range of prokaryotic and eukaryotic microbial species, including resistant forms such as bacterial and fungal spores. For practical application, a high-intensity narrow-spectrum light environmental disinfection system (HINS-light EDS) has been developed and tested in hospital isolation rooms. The trial results have demonstrated that this 405 nm light system can provide continuous disinfection of air and exposed surfaces in occupied areas of the hospital, thereby substantially enhancing standard cleaning and infection control procedures. Conclusion Violet–blue light, particularly 405 nm light, has significant antimicrobial properties against a wide range of bacterial and fungal pathogens and, although germicidal efficacy is lower than UV light, this limitation is offset by its facility for safe, continuous use in occupied environments. Promising results on disinfection efficacy have been obtained in hospital trials but the full impact of this technology on reduction of healthcare-associated infection has yet to be determined.
Inactivation of
Escherichia coli is examined using ultra-violet (UV) radiation from a pulsed xenon flashlamp. The light from the discharge has a broadband emission spectrum extending from the UV to ...the infrared region with a rich UV content. The flashlamp provides high-energy UV output using a small number of short-duration pulses (30
μs). The flashlamp is used with a monochromator to investigate the wavelength sensitivity of
E. coli to inactivation by the pulsed UV light. Using 8
nm wide pulses of UV radiation, the most efficient inactivation is found to occur at around 270
nm and no inactivation is observed above 300
nm. A pyroelectric detector allows the energy dose to be determined at each wavelength, and a peak value for
E. coli population reduction of 0.43 log per mJ/cm
2 is measured at 270
nm. The results are compared with the published data available for continuous UV light sources.
维生素 D 水平能否影响您的黑色素瘤风险? Liyanage, U.E.; Law, M.H.; Barrett, J.H. ...
British journal of dermatology (1951),
January 2020, 20200101, Letnik:
182, Številka:
1
Journal Article
Recenzirano
Summary
黑色素瘤是一种最致命的皮肤癌形式。根据澳大利亚癌症数据库统计数据, 2018 年, 黑色素瘤的发生率(意指病例数量)为 14778 例, 死亡人数为 1684 例。
在医学文献(如期刊)中关于维生素 D 可能对黑色素瘤风险发挥的作用存在很大争议。有些研究将维生素 D 缺乏症(意指维生素 D 水平较低)与许多不同癌症的风险增加相关联。
对黑色素瘤的研究充满困难, ...这是因为虽然阳光中较高的紫外线辐射 (UVR) 水平使体内维生素 D 水平增加,但 UVR 暴露也会增加黑色素瘤的风险。
在本项目中, 作者旨在确定维生素 D 水平是否会影响黑色素瘤风险。他们进行了孟德尔随机化分析 (MR),这是一种分析不同基因变体的方法,其可用于确定因果关系(原因和效果)。这项研究使用了欧洲血统基因数据,并结合将遗传标志物与维生素 D 水平相关联的数据。
作者表明, 即使预测的维生素 D 水平变化很大(20 nmol/L 下降),也仅对黑色素瘤风险产生轻微影响。虽然有些研究表明, 改变维生素 D 水平可能会降低黑色素瘤风险, 但这项研究未提供证据证明, 基因确定的维生素 D 与黑色素瘤风险存在因果关系(相关联)。
This summary relates to the study: 维生素 D 与黑色素瘤风险之间是否存在因果关系?一项孟德尔随机化分析研究。
Linked Article: Liyanage et al. Br J Dermatol 2020; 182:97–103
This study assessed the effects of high-intensity violet light on selected yeast and mould fungi. Cell suspensions of Saccharomyces cerevisiae, Candida albicans, and dormant and germinating spores ...(conidia) of the mould Aspergillus niger were exposed to high-intensity narrow band violet light with peak output at 405 nm generated from a light-emitting diode (LED) array. All three fungal species were inactivated by the 405-nm light without a requirement for addition of exogenous photosensitiser chemicals. Of the fungal species tested, S. cerevisiae was most sensitive and dormant conidia of A. niger were most resistant to 405-nm light exposure. Five-log10 colony forming units per millilitre (CFU ml−1) reductions of the tested species required exposure doses of 288 J cm−2 for S. cerevisiae, 576 J cm−2 for C. albicans, and a much higher value of 2.3 kJ cm−2 for dormant conidia of A. niger. During germination, A. niger conidia became more sensitive to 405-nm light exposure and sensitivity increased as germination progressed over an 8 h test period. Light exposure under aerobic and anaerobic conditions, together with results obtained using ascorbic acid as a scavenger of reactive oxygen species, revealed that 405-nm light inactivation in fungi involved an oxygen-dependent mechanism, as previously described in bacteria. The inactivation results achieved with yeast cells and fungal spores together with operational advantages associated with the use of a visible (nonultraviolet (UV)) light source highlight the potential of 405-nm light for fungal decontamination applications.
•Violet light shown to inactivate yeasts and dormant and germinating fungal spores.•A. niger dormant spores were most resistant to 405 nm violet light exposure.•A. niger conidia become more sensitive to 405 nm light as germination progresses.•Exposure tests demonstrated 405-nm light inactivation of fungi is oxygen-dependent.
Summary
Background
Several preclinical studies have identified the antiproliferative effects of 25‐hydroxyvitamin D 25(OH)D; vitamin D. Ultraviolet radiation (UVR) is essential for vitamin D ...synthesis yet increases the risk of melanoma. Observational studies on the association of vitamin D levels with melanoma risk have reported inconclusive results, and are difficult to interpret owing to the potential confounding from the dual role of UVR.
Objectives
To determine whether there is a causal association between genetically predicted 25(OH)D concentrations and melanoma using a Mendelian randomization (MR) approach.
Methods
We performed MR using summary data from a large genome‐wide association study (GWAS) meta‐analysis of melanoma risk, consisting of 12 874 cases and 23 203 controls. Five single nucleotide polymorphisms associated with 25(OH)D concentration – rs12785878, rs10741657, rs2282679, rs6013897 and rs116970203 – were selected as instrumental variables. An inverse variance weighted method was used to access the evidence for causality. MR results from the melanoma meta‐analysis were combined with results from an MR study based on a melanoma risk GWAS using UK Biobank data.
Results
A 20 nmol L−1 decrease in 25(OH)D was not associated with melanoma risk odds ratio (OR) 1·06, 95% confidence interval (CI) 0·95–1·19. Results from the UK Biobank were concordant with this, with meta‐analysis of our and UK Biobank‐derived MR causal estimates showing no association (OR 1·02, 95% CI 0·92–1·13 for a 20 nmol L−1 decrease).
Conclusions
The results suggest that vitamin D levels may not be causally associated with the risk of melanoma.
What's already known about this topic?
Antitumour activity of vitamin D has been identified in preclinical studies.
Observational studies link vitamin D deficiency with an increased risk of a range of cancers.
There is a growing public interest for vitamin D supplementation.
Observational studies of melanoma are fraught with difficulties because while higher ultraviolet radiation levels increase vitamin D levels, such exposure is also associated with increased melanoma risk.
Results from observational studies are inconclusive regarding the effect of vitamin D on melanoma risk.
What does this study add?
Using Mendelian randomization, an approach to causal inference, which is analogous to a natural randomized controlled trial, we found no causal association between vitamin D levels and melanoma.
Plain language summary available online
Linked Comment: Bell. Br J Dermatol 2020; 182:13–14.
Previous work has shown that a ceiling-mounted, 405 nm high-intensity narrow-spectrum light environmental decontamination system (HINS-light EDS) reduces bacterial contamination of environmental ...surfaces in a burns unit by between 27% and 75%. Examination of the efficacy of the light over extended exposure times and its probable mode of action was performed.
To ascertain the correlation between bacterial kill achieved on sampled surface sites around the burns unit and both irradiance levels of the 405 nm light, and exposure time.
Seventy samples were taken using contact agar plates from surfaces within an occupied side-room in the burns unit before, during, and after a seven-day use of the HINS-light EDS. This was repeated in three separate studies. Statistical analysis determined whether there was significant decrease in environmental contamination during prolonged periods of HINS-light treatment, and whether there was an association between irradiance and bacterial kill.
A decrease of between 22% and 86% in the mean number of surface bacteria was shown during the use of the HINS-light EDS. When the light ceased to be used, increases of between 78% and 309% occurred. There was no correlation between bacterial kill and irradiance levels at each sampling site but strong correlation between bacterial kill and exposure time.
Prolonged exposure to the HINS-light EDS causes a cumulative decontamination of the surfaces within a burns unit. The importance of exposure time and possible airborne effect over irradiance levels is emphasized.
Exposure to visible-light causes the photoinactivation of certain bacteria by a process that is believed to involve the photo-stimulation of endogenous intracellular porphyrins. Studies with some ...bacterial species have reported that this process is oxygen-dependent. This study examines the role of oxygen in the visible-light inactivation of
Staphylococcus aureus. Suspensions of
S. aureus were exposed to broadband visible-light under both oxygen depletion and oxygen enhancement conditions to determine whether these environmental modifications had any effect on the staphylococcal inactivation rate. Oxygen enhancement was achieved by flowing oxygen over the surface of the bacterial sample during light inactivation and results demonstrated an increased rate of staphylococcal inactivation, with approximately 3.5 times less specific dose being required for inactivation compared to that for a non-enhanced control. Oxygen depletion, achieved through the addition of oxygen scavengers to the
S. aureus suspension, further demonstrated the essential role of oxygen in the light inactivation process, with significantly reduced staphylococcal inactivation being observed in the presence of oxygen scavengers. The results of the present study demonstrate that the presence of oxygen is important for the visible-light inactivation of
S. aureus, thus providing supporting evidence that the nature of the mechanism occurring within the visible-light-exposed staphylococci is photodynamic inactivation through the photo-excitation of intracellular porphyrins.
Background Proteinuria is common and is associated with adverse patient outcomes. The optimal test of proteinuria to identify those at risk is uncertain. This study assessed albuminuria and total ...proteinuria as predictors of 3 patient outcomes: all-cause mortality, start of renal replacement therapy (RRT), and doubling of serum creatinine level. Study Design Retrospective longitudinal cohort study. Setting & Participants Nephrology clinic of a city hospital in Scotland; 5,586 patients with chronic kidney disease (CKD) and proteinuria measured in random urine samples (n = 3,378) or timed urine collections (n = 1,808). Predictors Baseline measurements of albumin-creatinine ratio (ACR), total protein–creatinine ratio (PCR), 24-hour albuminuria, and total proteinuria. Outcomes All-cause mortality, start of RRT, and doubling of serum creatinine level were assessed using receiver operating characteristic curves and Cox proportional hazards models. Measurements Blood pressure, serum creatinine level, ACR, PCR, date of death, date of starting RRT. Results Patients were followed up for a median of 3.5 (25th-75th percentile, 2.1-6.0) years. For all outcomes, adjusted HRs were similar for PCR and ACR (derived from random urine samples and timed collections): death, 1.41 (95% CI, 1.31-1.53) vs 1.38 (95% CI, 1.28-1.50); RRT, 1.96 (95% CI, 1.76-2.18) vs 2.33 (95% CI, 2.06-3.01); and doubling of serum creatinine level, 2.03 (95% CI, 1.87-2.19) vs 1.92 (95% CI, 1.78-2.08). Receiver operating characteristic curves showed almost identical performance for ACR and PCR for the 3 outcome measures. Adjusted HRs for ACR and PCR were similar when derived from random urine samples or timed collections and compared with 24-hour total protein and albumin excretion for each outcome measure. Limitations This is a retrospective study. Conclusions Total proteinuria and albuminuria perform equally as predictors of renal outcomes and mortality in patients with CKD. ACR and PCR were as effective as 24-hour urine samples at predicting outcomes and are more convenient for patients, clinicians, and laboratories. Both ACR and PCR stratify risk in patients with CKD.
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