Use of parvovirus B19-like particles in self-illuminated photodynamic therapy for solid tumors.

Bioluminescence resonance energy transfer photodynamic therapy, which uses light generated by bioluminescent proteins to activate photosensitizers and produce reactive oxygen species without the need for external irradiation, has shown promising results in cancer models. However, the characterization of delivery systems that can incorporate the components of this therapy for preferential delivery to the tumor remains necessary. In this work, we have characterized parvovirus B19-like particles (B19V-VLPs) as a platform for a photosensitizer and a bioluminescent protein. By chemical and biorthogonal conjugation, we conjugated rose Bengal photosensitizer and firefly luciferase to B19V-VLPs and a protein for added specificity. The results showed that B19V-VLPs can withstand decoration with all three components without affecting its structure or stability. The conjugated luciferase showed activity and was able to activate rose Bengal to produce singlet oxygen without the need for external light. The photodynamic reaction generated by the functionalized VLPs-B19 can decrease the viability of tumor cells in vitro and affect tumor growth and metastasis in the 4 T1 model. Treatment with functionalized VLPs-B19 also increased the percentage of CD4 and CD8 cell populations in the spleen and in inguinal lymph nodes compared to vehicle-treated mice. Our results support B19V-VLPs as a delivery platform for bioluminescent photodynamic therapy components to solid tumors.

Antimicrobial activity of topical dyes used in clinical veterinary ophthalmology.

OBJECTIVE: To evaluate in vitro the antibacterial effects of fluorescein, rose bengal, and lissamine green topical ophthalmic dyes against selected Gram-positive and Gram-negative bacteria, and to evaluate whether preserved or preservative-free fluorescein solutions are able to inhibit or potentiate bacterial growth. PROCEDURES: Susceptibility testing was performed using the Kirby-Bauer disk diffusion method plated with clinical ocular isolates of Staphylococcus aureus, Staphylococcus pseudintermedius, Streptococcus spp., Escherichia coli, and Pseudomonas aeruginosa. Bacterial growth inhibition was evaluated 24 hours following the addition of commercially available fluorescein, rose bengal, and lissamine green sterile strips. Antimicrobial effectiveness testing was performed by inoculation of compounded 1% dye solutions, both with and without preservatives (fluorescein and lissamine contained thiomersal, and rose bengal contained nipagin and nepazol), with the five previously mentioned bacteria. Growth was evaluated at days 7, 14, and 28. RESULTS: All dyes showed antibacterial activity against Gram-positive organisms. Preservative-free compounded 1% fluorescein solution inhibited growth of Gram-positive organisms but not of Gram-negative organisms. Preservative-free rose bengal and lissamine green inhibited growth of both types of organisms. CONCLUSIONS: Preferably, ocular surface samples for antimicrobial culture should be taken prior to the administration of topical dyes, due to their potential antibacterial activity, particularly if undiluted strips are applied directly or commercial fluorescein solutions are used and not immediately rinsed. Ophthalmic dye solutions containing preservative are safe from bacterial growth for up to 28 days if properly handled and stored. The use of preservative-free fluorescein solutions should be avoided and preservative-free rose bengal and lissamine green should be handled carefully.

Photodynamic therapy with rose bengal induces GroEL expression in Streptococcus mutans.

UNLABELLED: Heat-shock proteins (HSPs) are indicative of stressing conditions that may affect cell viability. In Streptococcus mutans, acid stress induces high levels of GroEL, an HSP, in addition to metabolic alterations, as shown by proteomic analysis. OBJECTIVE: We tested whether the expression of GroEL by S. mutans was enhanced after photodynamic therapy (PDT) with rose bengal. METHODS: S. mutans was grown in complete medium supplemented with 50 mmol/L glucose. The test conditions used were as follows: Rose bengal (0.1 micromol/L) with and without light treatment (500 mJ/cm(2)), light treatment alone, and 1 mol/L NaCl (as a stress condition). The extracellular pH of bacteria was monitored; HSP expression was assayed with Western blot, and possible DNA damage analyzed. RESULTS: Higher HSP expression was detected in bacteria after PDT treatment as compared with light or dye alone (negative controls). The expression of HSP after PDT was similar to that induced by osmotic stress. No DNA degradation was observed after PDT of S. mutans. CONCLUSIONS: PDT may cause effects similar to those of other stressing conditions in S. mutans, and cell death induced by this treatment reflects its incapacity to protect itself sufficiently against the deleterious effects of PDT with Rose bengal.

Olho seco / Dry eye

Os principais aspectos do ôlho seco säo descritos bem como o quadro clínico. O tratamento através de lágrimas artificiais é pouco adequado e o futuro do tratamento está em inserts que liberem quantidades adequadas de umidade, associada a lisozima, lactoferrina, vitamina A e sem preservativos