Fiber-Optic Probes for Small-Scale Measurements of Scalar Irradiance.

A new method for producing fiber-optic microprobes for scalar irradiance (=fluence rate) measurements is described. Such fine-scale measurements are important in many photobiological disciplines. With the new method, it is possible to cast spherical 30-600 µm wide light integrating sensor tips onto tapered or untapered optical fibers. The sensor tip is constructed by first casting a clear polymethyl methacrylate (PMMA) sphere (~80% of the size of the final probe tip diameter) onto the optical fiber via dip-coating. Subsequently, the clear sphere is covered with light diffusing layers of PMMA mixed with TiO2 until the fiber probe exhibits a satisfactory isotropic response (typically ±5-10%). We also present an experimental setup for measuring the isotropic response of fiber-optic scalar irradiance probes in air and water. The fiber probes can be mounted in a syringe equipped with a needle, facilitating retraction of the spherical fiber tip. This makes it, e.g. possible to cut a hole in cohesive tissue with the needle before inserting the probe. The light-collecting properties of differently sized scalar irradiance probes (30, 40, 100, 300 and 470 µm) produced by this new method were compared to probes produced with previously published methods. The new scalar irradiance probes showed both higher throughput of light, especially for blue light, as well as a better isotropic light collection over a wide spectral range. The new method also allowed manufacturing of significantly smaller scalar irradiance microprobes (down to 30 µm tip diameter) than hitherto possible, and such sensors allow minimally invasive high-resolution scalar irradiance measurements in thin biofilms, leaves and animal tissues.

Effect of red light on the development and quality of mammalian embryos.

PURPOSE: To assess irradiance and total energy dose from different microscopes during the in-vitro embryonic developmental cycle in mouse and pig and to evaluate its effect on embryonic development and quality in pig. METHOD: Spectral scalar irradiance (380-1050 nm) was measured by a fiber-optic microsensor in the focal plane of a dissection microscope, an inverted microscope and a time-lapse incubation system. Furthermore, the effect of three different red light levels was tested in the time-lapse system on mouse zygotes for 5 days, and on porcine zona-intact and zona-free parthenogenetically activated (PA) embryos for 6 days. RESULTS: The time-lapse system used red light centered at 625 nm and with a lower irradiance level as compared to the white light irradiance levels on the dissection and inverted microscopes, which included more energetic radiation <550 nm. Even after 1000 times higher total energy dose of red light exposure in the time-lapse system, no significant difference was found neither in blastocyst development of mouse zygotes nor in blastocyst rates and total cell number of blastocysts of porcine PA embryos. CONCLUSIONS: Our results indicate that red light (625 nm, 0.34 W/m(2)) used in the time-lapse incubation system does not decrease the development and quality of blastocysts in both mouse zygotes and porcine PA embryos (both zona-intact and zona-free).

Decreased mucosal oxygen tension in the maxillary sinuses in patients with cystic fibrosis.

BACKGROUND: Pseudomonas aeruginosa in the sinuses plays a role in the lungs in cystic fibrosis (CF) patients, but little is known about the sinus environment where the bacteria adapt. Anoxic areas are found in the lower respiratory airways but it is unknown if the same conditions exist in the sinuses. METHODS: The oxygen tension (pO(2)) was measured, using a novel in vivo method, in the maxillary sinus in a group of 20 CF patients. RESULTS: The CF patients had a significant lower pO(2) on the mucosa but not in the sinus lumen as compared with a control group of non-CF patients. Anoxic conditions were found in 7/39 (18%) of the sinuses from where we cultured P. aeruginosa, Stenotrophomonas maltophilia and/or coagulase negative staphylococci. CONCLUSION: These findings support our hypothesis that P. aeruginosa can adapt or acclimate to the environment in the lungs, during growth in anoxic parts of the paranasal sinuses.