Estimating the density of fluorescent nanoparticles in the primo vessels in the fourth ventricle and the spinal cord of a rat.

The primo vascular system is a novel circulatory system forming a network throughout an animal's body. Primo vessels were recently observed in the fourth ventricle of the brain and in the spinal cord of a rat by using fluorescent nanoparticles. In order to quantify the nanoparticles in the primo vessels, we measured the florescence of the nanoparticles and calibrated the measurements by using a reference suspension. We removed the noise due to autofluorescence with the technique of multispectral imaging. The line densities of nanoparticles and the contrast values of their images were, respectively, 0.5 ± 0.5 ng/mm and 0.7 ± 0.5 for primo vessels in the fourth ventricle, and 1.3 ± 0.6 ng/mm and 1.4 ± 0.2 for primo vessels in the spinal cord. The data obtained from and the procedures used in this work could be useful in evaluating the feasibility of using nanoparticles as a contrast agent during MRI or CT imaging of primo vessels in the brain or the spinal cord.

Fluorescent nanoparticles for observing primo vascular system along sciatic nerve.

The primo vascular system was found in the epineurium along the rat sciatic nerve following subcutaneous injection of fluorescent nanoparticles at the Zusanli acupoint (ST-36). Nanoparticles were injected into the primo-vessel near ST-36 and flowed along the sciatic nerve. Fluorescence revealed a structure in the epineurium that was hardly detectable. Images of the isolated sample stained with 4',6-diamidino-2-phenylindole were captured using confocal microscopy. These images showed the distinctive nuclei distribution and multi-lumen structure of primo-vessels that differentiate them from lymphatic vessels, blood capillaries and nerves. This study demonstrates a new use for nanoparticles in fluorescence reflectance imaging techniques during in vivo imaging of primo-vessels.

Hydrogen sulfide removal by immobilized Thiobacillus novellas on SiO2 in a fluidized bed reactor.

The removal of hydrogen sulfide (H2S) from aqueous media was investigated using Thiobacillus novellas cells immobilized on a SiO2 carrier (biosand). The optimal growth conditions for the bacterial strain were 30 degrees C and initial pH of 7.0. The main product of hydrogen sulfide oxidation by T. novellus was identified as the sulfate ion. A removal efficiency of 98% was maintained in the three-phase fluidized-bed reactor, whereas the efficiency was reduced to 90% for the two-phase fluidized-bed reactor and 68% for the two-phase reactor without cells. The maximum gas removal capacity for the system was 254 g H2S/m3/h when the inlet H2S loading was 300 g/m3/h (1,500 ppm). Stable operation of the immobilized reactor was possible for 20 days with the inlet H2S concentration held to 1,100 ppm. The fluidized bed bioreactor appeared to be an effective means for controlling hydrogen sulfide emissions.