A proof-of-principle for decontamination of transplantation kidney through UV-C exposition of the perfusate solution.

Kidney transplantation is a common yet highly demanding medical procedure worldwide, enhancing the quality of life for patients with chronic kidney disease. Despite its prevalence, the procedure faces a shortage of available organs, partly due to contamination by microorganisms, leading to significant organ disposal. This study proposes utilizing photonic techniques associated with organ support machines to prevent patient contamination during kidney transplantation. We implemented a decontamination system using ultraviolet-C (UV-C) irradiation on the preservation solution circulating through pigs' kidneys between harvest and implant. UV-C irradiation, alone or combined with ultrasound (US) and Ps80 detergent during ex-vivo swine organ perfusion in a Lifeport® Kidney Transporter machine, aimed to reduce microbiological load in both fluid and organ. Results show rapid fluid decontamination compared to microorganism release from the organ, with notable retention. By including Ps80 detergent at 0.5% during UV-C irradiation 3 log10 (CFU mL-1) of Staphylococcus aureus bacteria previously retained in the organ were successfully removed, indicating the technique's feasibility and effectiveness.

Efficiency of an air circulation decontamination device for micro-organisms using ultraviolet radiation.

BACKGROUND: The concern with environmental security to avoid contamination of individuals was intensified with the crisis established by SARS-CoV-2. The COVID-19 pandemic has shown the necessity to create systems and devices capable of clearing the air in an environment of micro-organisms more efficiently. The development of systems that allow the removal of micro-droplets mainly originating from breathing or talking from the air was the motivation of this study. AIM: This article describes a portable and easy-to-operate system that helps to eliminate the droplets or aerosols present in the environment by circulating air through an ultraviolet-C (UV-C) reactor. METHODS: An air circulation device was developed, and a proof-of-principle study was performed using the device against bacteria in simulated and natural environments. The microbiological analysis was carried out by the simple sedimentation technique. In order to compare the experimental results and the expected results for other micro-organisms, the reduction rate values for bacteria and viruses were calculated and compared with the experimental results based on technical parameters (clean air delivery rate (CADR) and air changes per hour (ACH)). FINDINGS: Results showed that the micro-organisms were eliminated with high efficiency by the air circulation decontamination device, with reductions of 99.9% in the proof-of-principle study, and 84-97% in the hospital environments study, contributing to reducing contamination of individuals in environments considered to present risk. CONCLUSION: This study resulted in a low-cost and relatively simple device, which was shown to be effective and safe, and could be replicated, especially in low-income countries, respecting the standards for air disinfection using UV-C technologies.

Photonic effects in natural nanostructures on Morpho cypris and Greta oto butterfly wings.

Photonic crystals are some of the more spectacular realizations that periodic arrays can change the behavior of electromagnetic waves. In nature, so-called structural colors appear in insects and even plants. Some species create beautiful color patterns as part of biological behavior such as reproduction or defense mechanisms as a form of biomimetics. The interaction between light and matter occurs at the surface, producing diffraction, interference and reflectance, and light transmission is possible under suitable conditions. In particular, there are two Colombian butterflies, Morpho cypris and Greta oto, that exhibit iridescence phenomena on their wings, and in this work, we relate these phenomena to the photonic effect. The experimental and theoretical approaches of the optical response visible region were studied to understand the underlying mechanism behind the light-matter interaction on the wings of these Colombian butterflies. Our results can guide the design of novel devices that use iridescence as angular filters or even for cosmetic purposes.

Prophylactic Use of Laser Light and Methylene Blue on Ischemia and Liver Reperfusion Injury.

OBJECTIVE: This study aimed to evaluate the effect of hepatic preconditioning with laser light in the presence of methylene blue (MB) in the liver ischemia-reperfusion injury process. METHOD: Forty male Wistar rats were divided into 8 experimental groups (n = 5). Saline (.5 mL) or MB (15 mg/kg) was injected intravenously (inferior vena cava). After 2 minutes, 660 nm laser light was applied at a dose of 112.5 DE. Fifteen minutes after the application of saline or MB, 1 hour partial ischemia followed by 15 minutes of reperfusion was applied when the rats were sacrificed. The mitochondrial function parameters (O2 consumption rates in states 3 and 4 and the respiratory control ratio), osmotic swelling, and determination of malondialdehyde were evaluated. Hepatic function was studied using the serum determination of the alanine aminotransferase and aspartate aminotransferase enzymes. RESULTS AND CONCLUSIONS: MB therapy alone showed the capacity of preserving the rate of oxygen consumption in the mitochondrial respiratory state of the group submitted to ischemia compared to the sham group. However, when combined with low-intensity laser therapy, it failed to replicate the relevant protective effects in relation to oxidative phosphorylation or the mitochondrial membrane ischemia/reperfusion injury. Whether or not MB was combined with laser treatment, it was shown to be efficient in reducing oxidative stress. In relation to alanine aminotransferase enzymes, whether or not laser treatment was combined with MB had a protective effect on the hepatic lesion, whereas in relation to aspartate aminotransferase enzymes only laser treatment was able to provide this protection.

The influence of experimental conditions on the final result of photoinhibition of Staphylococcus aureus.

BACKGROUND: By and large, phototherapies are a promising approach to promote inactivation of microorganisms using light exposure, providing an effective alternative to control multidrug-resistant bacterial infections. Considering this, intercomparison between experiments is vitally important. Most experiments are performed using multiwell plates in which the volume of the culture medium is not standardized. In such cases, light attenuation and the distance it travels, which also depends on the volume and vessel geometry, can lead to different results. This study investigated how the different volumes imply different depths that light will have to travel through in this volume and the relation of this parameter with the result that will be obtained. METHODS: Staphylococcus aureus was exposed to 460nm light with 50, 100 and 200J/cm2, in 100, 200, 500 and 1000µL of inocula in a 24-well plate to investigate pure light inactivation. RESULTS: The literature suggests that fluence is the most important light parameter to obtain a high eradication of microbial cells in phototherapies. Our results show evidence that different geometrical configurations, taking into account the volume of the vessels, clearly affect the in vitro results, risking misinterpretation of dosimetry studies. Effects, such as dose distribution and decantation, are discussed throughout the paper. CONCLUSION: The outcome strongly depends on the volume and vessel geometry used. This study aims to encourage the standardization of phototherapies in vitro in general.

Identification of skin lesions through aminolaevulinic acid-mediated photodynamic detection.

Non-melanoma skin cancer is the most common cancer lesion worldwide. In Brazil, it represents 95% of all skin cancer lesions, and 25% of all tumor types. Early diagnosis allows treatment at initial stages of the disease, improving patient's prognosis. Thus, it is of great importance the development of techniques to aid diagnosis, such as marked fluorescence, which we propose here for early detection of skin cancer lesions. In this study, we use a photosensitive substance, aminolaevulinic acid (ALA), as biomarkers, and analyze its in situ fluorescence response to light excitation. The use of ALA as a biomarker precursor is interesting because it shows selectivity for protoporphyrin IX production/concentration in abnormal cells. Protoporphyrin IX shows high fluorescence yield when excited with UV-blue light. In this study, ALA solutions (at 5% and 10% concentrations) were applied to malignant (basal cell carcinoma) and potentially malignant skin lesions (actinic and seborrheic keratoses), aiming to investigate our ability in detecting and distinguishing them by using this technique. At regular time intervals (15, 30, 45 and 60min), fluorescence images were collected with a prototype system for widefield fluorescence imaging. ALA has provided a marked fluorescence that allowed significant discrimination of normal and tumor. Potentially malignant and benign lesions were all well-identified by their autofluorescence; photodynamic detection did not improve diagnostics. This technique also provided a better delineation of the lesion margins, which is very important for an effective treatment of malignant, potentially malignant and benign skin lesions.

Autofluorescence spectroscopy in liver transplantation: preliminary results from a pilot clinical study.

The evaluation of graft function at various stages after transplantation is relevant, particularly at the moment of organ harvest, when a decision must be made whether to use the organ. Autofluorescence spectroscopy is noninvasive technique to monitor the metabolic condition of a liver graft throughout its course, from an initial evaluation in the donor, through cold ischemia transportation, to reperfusion and reoxygenation in the recipient. Preliminary results are presented in six liver transplantations spanning the periods from liver harvest to implant. The laser-induced fluorescence spectrum at 532-nm excitation was investigated before cold perfusion (autofluorescence), during cold ischemia, at the back table procedure, as well as 5 and 60 minutes after reperfusion. The results showed that the fluorescence analysis was sensitive to changes during the transplantation procedure. Fluorescence spectroscopy potentially provides a real-time, noninvasive technique to monitor liver graft function. The information could potentially be valuable for surgical decisions and transplant success.