Photo-Inactivation of Staphylococcus aureus by Diaryl-Porphyrins

Photodynamic Antimicrobial Chemotherapy (PACT) has received great attention in recent years since it is an effective and promising modality for the treatment of human oral and skin infections with the advantage of bypassing pathogens' resistance to antimicrobials. Moreover, PACT applications demonstrated a certain activity in the inhibition and eradication of biofilms, overcoming the well-known tolerance of sessile communities to antimicrobial agents. In this study, 13 diaryl-porphyrins (mono-, di-cationic, and non-ionic) P1-P13 were investigated for their potential as photosensitizer anti-Staphylococcus aureus. The efficacy of the diaryl-porphyrins was evaluated through photo-inactivation tests. Crystal-violet staining combined with viable count techniques were aimed at assaying their anti-biofilm activity. Among the tested compounds, the neutral photosensitizer P4 was better than the cationic ones, irrespective of their corresponding binding rates. In particular, P4 was active in inhibiting the biofilm formation and in impairing the viability of the adherent and planktonic populations of a 24 h old biofilm. The inhibitory activity was also efficient against a methicillin resistant S. aureus strain. In conclusion, the diaryl-porphyrin family represents a reservoir of promising compounds for photodynamic applications against the pathogen S. aureus and in preventing the formation of biofilms that cause many infections to become chronic

Antimicrobial Blue Light (aBL) as a potential tool to reduce bacterial spoilage in the fishery chain

Along the fishery chain, a high amount of fish is lost for the activity of spoilage microorganisms originating from the environment, human handling and fish themselves. Different techniques are conventionally used to reduce the growth of bacteria: from cold temperature and icing to high concentration of salts, from drying to natural antimicrobial compounds. In this study, the antimicrobial Blue Light (aBL) was considered as an innovative tool. In particular, the irradiation with light at 410 nm inhibited the growth of most bacteria isolated from skin samples of anchovies and sardines chosen for their worldwide commercial importance. Bacterial strains showed a different sensitivity to light treatment: the ones isolated from anchovy were more sensitive than those from sardine. Investigations were performed on Aeromonas bestiarum, an emerging foodborne pathogen. Upon irradiation with light at 410 nm (200 J/cm2), a statistically significant decrease of 3 log units was observed. The same fluence rate successfully inhibited the biofilm formation of A. bestiarum, and disrupted 50 % of the adherent biomass of a 24-h old biofilm. The irradiation of Staphyococcus vitulinus compromised its viability and the associated proteolytic activity known to contribute to meat spoilage. In vivo experiments showed that aBL caused a remarkable decrease (at least 50 %) of viable counts of bacteria from anchovy and sardine skin samples conserved at 4 °C for one day. In conclusion, these results support the potential use of blue light in reducing the growth of skin microorganisms potentially responsible for loss of food safety, quality and decrease of storage life

Structure of the TPR Domain of AIP: Lack of Client Protein Interaction with the C-Terminal alpha-7 Helix of the TPR Domain of AIP Is Sufficient for Pituitary Adenoma Predisposition

PMCID: PMC3534021This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

The Immunophilin-Like Protein XAP2 Is a Negative Regulator of Estrogen Signaling through Interaction with Estrogen Receptor α

XAP2 (also known as aryl hydrocarbon receptor interacting protein, AIP) is originally identified as a negative regulator of the hepatitis B virus X-associated protein. Recent studies have expanded the range of XAP2 client proteins to include the nuclear receptor family of transcription factors. In this study, we show that XAP2 is recruited to the promoter of ERα regulated genes like the breast cancer marker gene pS2 or GREB1 and negatively regulate the expression of these genes in MCF-7 cells. Interestingly, we show that XAP2 downregulates the E2-dependent transcriptional activation in an estrogen receptor (ER) isoform-specific manner: XAP2 inhibits ERα but not ERβ-mediated transcription. Thus, knockdown of intracellular XAP2 levels leads to increased ERα activity. XAP2 proteins, carrying mutations in their primary structures, loose the ability of interacting with ERα and can no longer regulate ER target gene transcription. Taken together, this study shows that XAP2 exerts a negative effect on ERα transcriptional activity and may thus prevent ERα-dependent events

Autonomous IoT Monitoring Matching Spectral Artificial Light Manipulation for Horticulture

This paper aims at demonstrating the energy self‐sufficiency of a LoRaWAN‐based sensor node for monitoring environmental parameters exploiting energy harvesting directly coming from the artificial light used in indoor horticulture. A portable polycrystalline silicon module is used to charge a Li‐Po battery, employed as the power reserve of a wireless sensor node able to accurately monitor, with a 1‐h period, both the physical quantities most relevant for the application, i.e., humidity, temperature and pressure, and the chemical quantities, i.e., O2 and CO2 concentrations. To this aim, the node also hosts a power‐hungry NDIR sensor. Two programmable light sources were used to emulate the actual lighting conditions of greenhouses, and to prove the effectiveness of the designed autonomous system: a LED‐based custom designed solar simulator and a commercial LED light especially thought for plant cultivation purposes in greenhouses. Different lighting conditions used in indoor horticulture to enhance different plant growth phases, obtained as combinations of blue, red, far‐red and white spectra, were tested by field tests of the sensor node. The energy self‐sufficiency of the system was demonstrated by monitoring the charging/discharging trend of the Li‐Po battery. Best results are obtained when white artificial light is mixed with the far‐red component, closest to the polycrystalline silicon spectral response peak

Effect of blue light at 410 and 455 nm on Pseudomonas aeruginosa biofilm

Pseudomonas aeruginosa is an opportunistic pathogen resistant to many antibiotics, able to form biofilm and causes serious nosocomial infections. Among anti-Pseudomonas light-based approaches, the recent antimicrobial Blue Light (aBL) treatment seems very promising. The aim of this study was to evaluate the efficiency of blue light in inhibiting and/or eradicating P. aeruginosa biofilm. Light at 410 nm has been identified as successful in inhibiting biofilm formation not only of the model strain PAO1, but also of CAUTI (catheter-associated urinary tract infection) isolates characterized by their ability to form biofilm. Results of this work on 410 nm light also demonstrated that: i) at the lowest tested radiant exposure (75 J cm 122) prevents matrix formation; ii) higher radiant exposures (225 and 450 J cm 122) light impairs the cellular components of biofilm, adherent and planktonic ones; iii) light eradicates with a good rate young and older biofilms in a light dose dependent manner; iv) it is also efficient in inactivating catalase A, a virulence factor playing an important role in pathogenic mechanisms. Light at 455 nm, even if at a lower extent than 410 nm, showed a certain anti-Pseudomonas activity. Furthermore, light at 410 nm caused detrimental effects on enzyme activity of \u3b2-galactosidase and catalase A, and changes on plasmid DNA conformation and ortho-nitrophenyl-\u3b2-D-galactopyranoside structure. This study supports the potential of blue light for anti-infective and disinfection applications

Modeling Approach to Capture the Effect of High Frequency Flashing Light in Steady-State Microalgae Cultures

With the advent of efficient artificial light systems, the possibility of exploiting pulsed light (PL) in microalgal cultivation is gaining renewed attention. In this work, a model was developed to describeArthrospira maxima production in continuous cultivation systems, under both continuous and high-frequency pulsed light regimes. The model is based on the one originally developed by Camacho-Rubio, modified to link photosynthetic units activation to biomass growth, accounting also for maintenance. The modified model, calibrated in continuous light regime, was found to properly predict steady-state microalgal growth at different light intensities and residence times. The model was then validated on experimental data carried out under extreme PL conditions (high frequencies up to 3700 Hz and duty cycles as low as 0.01). Remarkably, it was able to account for the flashing light effect (FLE, i.e., increased biomass production with respect to continuous light supply) measured under such conditions and can therefore be a valuable tool to optimize the energetic efficiency of algal cultivation

Light at 410 nm controls the growth of skin bacteria from Chelidonichthys lucerna (Osteichthyes: Triglidae)

Fish microbiota represents a community to be considered in fishery world for two main reasons: the occurrence of potential pathogens dangerous for human health and/or degraders of flesh. The most used techniques to control fish spoilage are icing and freezing. Furthermore, UV treatment and chemical disinfection are also considered. However, these treatments often compromise the quality of food, worsen the taste, smell, appearance in addition to loss of nutritional quality. In this scenario, the use of blue light in antimicrobial field opens new and interesting considerations.In this study, we focused the attention on the tub gurnard (Chelidonichthys lucerna L., 1758), a demersal teleost fish that was chosen as a model to irradiate with LED at 410 nm. The approach was efficient in greatly reducing the microbial community colonizing the skin of the fish. Furthermore, microorganisms isolated from C. lucerna, belonging to different Gram-negative (Aeromonas sp., Exiguobacterium undae, Acinetobacter sp., Acinetobacter baumannii) and Gram-positive species (Bacillus thuringiensis, Listeria sp.) showed a different sensitivity to blue light. However, the bacterial photoinactivation was light-dose dependent. Indeed, blue irradiation could slow down the spoilage of fish with food quality maintenance, help preserving human health and bring, in addition, economic advantage