In recent years the photodynamic activity of rose bengal activated with green light against selected bacterial strains has been reported. However, according to our knowledge, the differences between the sensitivity of Gram-positive and Gram-negative bacterial strains in the presence of this photosensitizer have not been described. The aim of the conducted research was to examine the antibacterial effect of 535 nm wavelength diode laser light in the presence of rose bengal as photosensitizer on selected reference bacterial strains: Pseudomonas aeruginosa, Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus. Sterile 96-well microtiter plates were used to determine the antibacterial activity of the green light and rose bengal solutions at various concentrations. The labelled bacterial suspensions were placed to each well of the 96-well microtiter plate filled with liquid medium LB and solution of rose bengal. The plates were exposed to green diode laser light. After 24 hours of incubation at 37oC, the turbidance was read in a spectrophotometer. The irradiation in the presence of photosensitizer can act in an antibacterial manner, either bacteriostatically or bactericidally. The tested strains exhibit different sensitivity to irradiation because of the structure of the cell wall, the presence of different bacterial pigments and photoreceptor proteins in some species of bacteria. Gram-positive bacteria, Staphylococcus aureus and Enterococcus faecalis were the most photosensitive strains due to the higher possibility of rose bengal penetration into the bacterial cell, leading to the bacteriostatic effect. Our results show that rose bengal may be applied in the treatment of Gram-positive infections.

Thiohydantoin and quinolone derivatives have attracted researchers' attention because of a broad spectrum of their medical applications. The aim of our research was to synthesize and analyze the antimicrobial properties of novel 2-thiohydantoin and 2-quinolone derivatives. For this purpose, two series of hybrid compounds were synthesized. Both series consisted of 2-thiohydantoin core and 2-quinolone derivative ring, however one of them was enriched with an acetic acid group at N3 atom in 2-thiohydantoin core. Antibacterial properties of these compounds were examined against bacteria: Staphylococcus aureus, Bacillus subtilis, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae. The antimicrobial assay was carried out using a serial dilution method to obtain the MIC. The influence of blue light irradiation on the tested compounds was investigated. The relative yield of singlet oxygen (1O2*, 1Δg) generation upon excitation with 420 nm was determined by a comparative method, employing perinaphthenone (PN) as a standard. Antimicrobial properties were also investigated after blue light irradiation of the suspensions of the hybrids and bacteria placed in microtitrate plates. Preliminary results confirmed that some of the hybrid compounds showed bacteriostatic activity to the reference Gram-positive bacterial strains and a few of them were bacteriostatic towards Gram-negative bacteria, as well. Blue light activation enhanced bacteriostatic effect of the tested compounds.

Vitamins C and E and zeaxanthin are components of a supplement tested in a large clinical trial—Age-Related Eye Disease Study 2 (AREDS2)—and it has been demonstrated that they can inhibit the progression of age-related macular degeneration. The aim of this study was to determine the optimal combinations of these antioxidants to prevent the phototoxicity mediated by vitamin A aldehyde (ATR), which can accumulate in photoreceptor outer segments (POS) upon exposure to light. We used cultured retinal pigment epithelial cells ARPE-19 and liposomes containing unsaturated lipids and ATR as a model of POS. Cells and/or liposomes were enriched with lipophilic antioxidants, whereas ascorbate was added just before the exposure to light. Supplementing the cells and/or liposomes with single lipophilic antioxidants had only a minor effect on phototoxicity, but the protection substantially increased in the presence of both ways of supplementation. Combinations of zeaxanthin with α-tocopherol in liposomes and cells provided substantial protection, enhancing cell viability from ~26% in the absence of antioxidants to ~63% in the presence of 4 µM zeaxanthin and 80 µM α-tocopherol, and this protective effect was further increased to ~69% in the presence of 0.5 mM ascorbate. The protective effect of ascorbate disappeared at a concentration of 1 mM, whereas 2 mM of ascorbate exacerbated the phototoxicity. Zeaxanthin or α-tocopherol partly ameliorated the cytotoxic effects. Altogether, our results suggest that the optimal combination includes upper levels of zeaxanthin and α-tocopherol achievable by diet and/or supplementations, whereas ascorbate needs to be at a four-fold smaller concentration than that in the vitreous. The physiological relevance of the results is discussed.

Retinal lipofuscin accumulates with age in the retinal pigment epithelium (RPE), where its fluorescence properties are used to assess retinal health. It was observed that there is a decrease in lipofuscin fluorescence above the age of 75 years and in the early stages of age-related macular degeneration (AMD). The purpose of this study was to investigate the response of lipofuscin isolated from human RPE and lipofuscin-laden cells to visible light, and to determine whether an abundant component of lipofuscin, docosahexaenoate (DHA), can contribute to lipofuscin fluorescence upon oxidation. Exposure of lipofuscin to visible light leads to a decrease in its long-wavelength fluorescence at about 610 nm, with a concomitant increase in the short-wavelength fluorescence. The emission spectrum of photodegraded lipofuscin exhibits similarity with that of oxidized DHA. Exposure of lipofuscin-laden cells to light leads to a loss of lipofuscin granules from cells, while retaining cell viability. The spectral changes in fluorescence in lipofuscin-laden cells resemble those seen during photodegradation of isolated lipofuscin. Our results demonstrate that fluorescence emission spectra, together with quantitation of the intensity of long-wavelength fluorescence, can serve as a marker useful for lipofuscin quantification and for monitoring its oxidation, and hence useful for screening the retina for increased oxidative damage and early AMD-related changes.

Dehydrolutein accumulates in substantial concentrations in the retina. The aim of this study was to compare antioxidant properties of dehydrolutein with other retinal carotenoids, lutein, and zeaxanthin, and their effects on ARPE-19 cells. The time-resolved detection of characteristic singlet oxygen phosphorescence was used to compare the singlet oxygen quenching rate constants of dehydrolutein, lutein, and zeaxanthin. The effects of these carotenoids on photosensitized oxidation were tested in liposomes, where photo-oxidation was induced by light in the presence of photosensitizers, and monitored by oximetry. To compare the uptake of dehydrolutein, lutein, and zeaxanthin, ARPE-19 cells were incubated with carotenoids for up to 19 days, and carotenoid contents were determined by spectrophotometry in cell extracts. To investigate the effects of carotenoids on photocytotoxicity, cells were exposed to light in the presence of rose bengal or all-trans-retinal. The results demonstrate that the rate constants for singlet oxygen quenching are 0.77 × 1010, 0.55 × 1010, and 1.23 × 1010 M−1s−1 for dehydrolutein, lutein, and zeaxanthin, respectively. Overall, dehydrolutein is similar to lutein or zeaxanthin in the protection of lipids against photosensitized oxidation. ARPE-19 cells accumulate substantial amounts of both zeaxanthin and lutein, but no detectable amounts of dehydrolutein. Cells pre-incubated with carotenoids are equally susceptible to photosensitized damage as cells without carotenoids. Carotenoids provided to cells together with the extracellular photosensitizers offer partial protection against photodamage. In conclusion, the antioxidant properties of dehydrolutein are similar to lutein and zeaxanthin. The mechanism responsible for its lack of accumulation in ARPE-19 cells deserves further investigation.

The contribution of sulphur (S)-induced responses to chromium (Cr) tolerance of rice plants is not yet fully elucidated. It is hypothesised that S nutrition mitigates the accumulation and toxicity of Cr through enhanced formation of iron plaque (IP) and S-containing chelators. This study aimed to investigate the responses of iron (Fe) and Cr availability and transfer in the hydroponic rice system to added S levels. We explored the influence of S nutrition on Cr accumulation in rice under a combination of Cr (VI) (+Cr, –Cr) and S (0, 1.75, 3.5, 7 mM) treatments. S additions at rates of 1.75 and 3.5 mM gave the least decline in root and shoot growth of rice seedlings under Cr stress. Fe concentration in shoots was consistent with the level of Cr uptake. The subcellular distribution of Cr in roots and shoots differed with varying S supply levels. Our results also revealed that S treatment at a moderate level (3.5 mM) was more effective in suppressing the bioavailability of Cr in rice shoots than were the other levels. S-induced reduction in shoot Cr concentration, particularly from 1.75 to 3.5 mM, was likely attributed to the enhanced biosynthesis of glutathione (GSH) and phytochelatins (PCs) in roots than the enhanced physical resistance of IP induced by S. The poor barrier capacity of IP to Cr absorption in rice plants primarily ascribed to the level of applied Cr concentration and partly to the competition between Cr and S at the absorbing sites.

Retinal lipofuscin which accumulates with age in the retinal pigment epithelium (RPE) is subjected to daily exposures to high fluxes of visible light and exhibits potent photosensitising properties; however, the molecules responsible for its photoreactivity remain unknown. Here, we demonstrate that autooxidation of docosahexaenoate (DHE) leads to the formation of products absorbing, in addition to UVB and UVA light, also visible light. The products of DHE oxidation exhibit potent photosensitising properties similar to photosensitising properties of lipofuscin, including generation of an excited triplet state with similar characteristics as the lipofuscin triplet state, and photosensitised formation of singlet oxygen and superoxide. The quantum yields of singlet oxygen and superoxide generation by oxidised DHE photoexcited with visible light are 2.4- and 3.6-fold higher, respectively, than for lipofuscin, which is consistent with the fact that lipofuscin contains some chromophores which do contribute to the absorption of light but not so much to its photosensitising properties. Importantly, the wavelength dependence of photooxidation induced by DHE oxidation products normalised to equal numbers of incident photons is also similar to that of lipofuscin—it steeply increases with decreasing wavelength. Altogether, our results demonstrate that products of DHE oxidation include potent photosensitiser(s) which are likely to contribute to lipofuscin photoreactivity.

The aim of the study was to investigate the effect of red radiation emitted by helium-neon laser (He-Ne) with a wavelength λ = 632.8 nm and trace elements: cadmium (Cd) and lead (Pb), as cadmium nitrate and lead nitrate solutions, at 30 ppm concentrations, on the cell cycle of root-tip meristem cells in maize. Red light stimulated the mitotic activity of the meristemic cells of the maize root-tip meristem growth after irradiation of seed samples with simultaneous treatment in the presence of Cd or Pb. The mitotic index was inhibited when the seeds were treated with distilled water with the addition of Cd or Pb salts. Seeds treated with laser had significantly the highest mitotic index. Results revealed that maize seed pre-treatment with the red light protects the root-tip meristem cells against the mitodepressive effect of Cd and Pb ions. Seed biomodulation using red light emitted by He-Ne laser can positively effect the germination and plant growth.

Antecedentes: Extraer un diente del maxilar da como resultado la aparicion de una comunicacion oroantral en condiciones anatomicas beneficiosas o en el caso de un efecto iatrogenico. Los tratamientos popularizados de la comunicacion oroantral tienen numerosos fallos. Un defecto oseo grande elimina la posibilidad de introducir un implante. El proposito de este trabajo fue evaluar la utilidad del injerto oseo autologo y PRF en la regeneracion osea normal en el lugar de la comunicacion oroantral. Material y metodos: La regeneracion osea en el lugar de la comunicacion oroantral fue evaluada en 20 pacientes. Los defectos oseos se suplementaron con injerto de hueso autologo de la protuberancia mentoniana en 14 casos y de la linea oblicua en 6 casos. El injerto se cubrio con una membrana PRF. Resultados: En el grupo de estudio en todos los casos se observo el cierre de la comunicacion oroantral. La anchura media alveolar fue 13 mm y la altura media de 12.5 mm. En 3 pacientes se observo un aumento promedio de la altura alveolar de 1.5 mm. Conclusiones: Este metodo puede ser la mejor opcion para preparar el hueso alveolar para un nuevo implante y las soluciones protesicas.

Background: Removing a tooth from the jaw results in the occurrence of oroantral communication in beneficial anatomic conditions or in the case of a iatrogenic effect. Popularized treatments of the oroantral communication have numerous faults. Large bone defect eliminates the chance to introduce an implant.Purpose of this work was assessment of the usefulness of autogenous bone graft and PRF in normal bone regeneration in the site of oroantral communication.Material and Methods: Bone regeneration in the site of oroantral communication was assessed in 20 patients. Bone defects were supplemented autogenous bone graft from mental protuberance in 14 cases and from oblique line in 6 cases. The graft was covered with a PRF membrane.Results: In the study group in all cases closure of the oroantral communication was observed. The average width of the alveolar was 13 mm and the average height was 12.5 mm. In 3 patients an average increase of alveolar height of 1.5 mm was observed.Conclusions: This method may be the best option to prepare alveolar for new implant and prosthetic solutions.

Maintenance of proper oral hygiene by dental plaque elimination is one of the most important factors affecting the healing process in postoperative oral wounds. Propolis is a substance produced by bees. Ethanolic extract of propolis has bactericidal, fungicidal, anti-inflammatory, and antioxidative properties. Moreover, it can scavenge free radicals. The purpose of this paper is to demonstrate the efficacy of a gel containing 3% of ethanolic extract of Brazilian green propolis (EEP-B) when used for maintaining oral hygiene in patients with postoperative oral mucosal wounds. The hygiene was assessed using API, OHI, and SBI followed by microbiological examinations. The patients were divided into two groups. Group 1 consisted of those who used a gel containing EEP-B for oral hygiene, and group 2 consisted of those who used a gel without EEP-B. Although improved oral hygiene was noted in both groups, the improvement was markedly greater in the group using gel containing EEP-B. Summing up the results of microbiological examinations, EEP-B has beneficial effect on mouth microflora in postoperative period. Propolis preparations used for oral hygiene allow eliminating microorganisms of pathogenic character and physiological flora microorganisms considered as being opportunistic, with no harmful influence on physiological microflora in oral ecosystem.

All‐trans‐retinal (AtRal) can accumulate in the retina as a result of excessive exposure to light. The purpose of this study was to compare cytotoxicity of AtRal and photodegraded AtRal (dAtRal) on cultured human retinal pigment epithelial cells in dark and upon exposure to visible light. AtRal was degraded by exposure to visible light. Cytotoxicity was monitored by imaging of cell morphology, propidium iodide staining of cells with permeable plasma membrane and measurements of reductive activity of cells. Generation of singlet oxygen photosensitized by AtRal and dAtRal was monitored by time‐resolved measurements of characteristic singlet oxygen phosphorescence. Photodegradation of AtRal resulted in a decrease in absorption of visible light and accumulation of the degradation products with absorption maximum at ∼330 nm. Toxicity of dAtRal was concentration‐dependent and was greater during irradiation with visible light than in dark. DAtRal was more cytotoxic than AtRal both in dark and during exposure to visible light. Photochemical properties of dAtRal indicate that it may be responsible for the maximum in the action spectra of retinal photodamage recorded in animals. In conclusion, photodegradation products of AtRal may impose a significant threat to the retina and therefore their roles in retinal pathology need to be explored.

Photoexcited melanin from retinal pigment epithelium (RPE) has been shown to induce photo-oxidation of ascorbate with concomitant generation of hydrogen peroxide. The aim of this study was to test whether the age-related changes in melanin content and distribution in the RPE affect the susceptibility of RPE cells to ascorbate-mediated photo-oxidation. Our results demonstrate that there is an age-dependent shift in the pathways with which ascorbate interacts in human RPE. In young RPE, melanin-ascorbate interactions may lead to pro-oxidant effects, but in the aged there is no net increase in photo-oxidation in the presence of ascorbate in comparison with samples without ascorbate. However, as ascorbate undergoes light-induced depletion and photogenerates ascorbyl free radical in the old RPE cells with initial yields similar to that observed for young RPE, an influence of ascorbate on oxidation pathways is revealed in the old RPE as well. Interestingly, the pro-oxidant effects of photoexcited melanolipofuscin-ascorbate interactions are greater than for photoexcited melanosomes when normalized to the same melanin content. The pro-oxidant effects of photoexcited melanin-ascorbate interactions are strongly dependent on the irradiation wavelength, this being the greatest for the shortest wavelength studied (340 nm) and steeply decreasing with increasing wavelength but still detectable even at 600 nm.

PURPOSETo determine the effects of human retinal pigment epithelial (RPE) cell pigment granules on photosensitized and iron ion-mediated oxidation and the effect of the photodegradation of melanosomes on their antioxidant properties.METHODSRPE cells were isolated from human and bovine eyes; pigmented and nonpigmented bovine retinal pigment epithelia were isolated separately. Melanosomes, melanolipofuscin, and lipofuscin granules were isolated from human RPE donors older than 60. Melanosomes were photodegraded by exposure to blue light. Oxidation of RPE cells or of linoleate was induced by iron/ascorbate in the presence and absence of pigment granules. The photosensitized oxidation of histidine was induced by blue light irradiation of cationic porphyrin. The progress of oxidation was monitored by electron spin resonance oximetry.RESULTSIron/ascorbate induced rapid oxidation in suspensions of nonpigmented bovine RPE cells. The rates of oxidation were diminished approximately four times in suspensions of pigmented bovine RPE cells. Adding bovine melanosomes or synthetic melanin to nonpigmented bovine RPE cells resulted in a concentration-dependent decrease in the rate of oxidation to levels similar to those of pigmented bovine retinal pigment epithelium. Human melanosomes exerted a concentration-dependent inhibitory effect on photosensitized and iron-mediated oxidation. Photodegradation of human melanosomes led to loss of the inhibitory effect on iron-mediated oxidation, whereas their ability to inhibit photosensitized oxidation was enhanced.CONCLUSIONSHuman melanosomes act as effective antioxidants by preventing iron ion-induced oxidation. Photodegradation of melanosomes results in the loss of these antioxidant properties while it preserves their ability to deactivate cationic photosensitizers.

The purpose of this study was to determine whether an age-related increase in photoreactivity of human retinal melanosomes (MS) can cause phototoxicity to retinal pigment epithelium (RPE) cells. MS were isolated post mortem from young (20-30 years, young human melanosomes [YHMs]) and old (60-90 years, old human melanosomes [OHMs]) human eyes and from young bovine eyes (bovine melanosomes [BMs]). Confluent cultured ARPE-19 cells were fed equivalent numbers of OHMs or BMs and accumulated similar amounts of melanin as determined by electron paramagnetic resonance assay. Cells with and without MS were either maintained in the dark or exposed to blue light for up to 96 h and assessed for alterations in cell morphology, cell viability and lysosomal integrity. Incubation of cells in dark in the presence of internalized MS or irradiation of cells with blue light in the absence or presence of BMs did not significantly affect cell viability. However, exposures to blue light in the presence of OHMs resulted in abnormal cell morphology, up to approximately 75% decrease in mitochondrial activity, loss of lysosomal pH and cell death. OHMs contained significantly less melanin than YHMs, supporting the hypothesis that melanin undergoes degradation during RPE aging. Our results demonstrate that aged MS can be phototoxic to human RPE cells and support a contributing role of MS in RPE aging and in the pathogenesis of age-related macular degeneration.