Paramagnetic ultrasmall gadolinium oxide (Gd(2)O(3)) nanoparticles with particle diameters (d) of approximately 1 nm were synthesized by using three kinds of Gd(III) ion precursors and by refluxing each of them in tripropylene glycol under an O(2) flow. A large longitudinal relaxivity (r(1)) of water proton of 9.9 s(-1) mM(-1) was estimated. As a result, high contrast in vivo T(1) MR images of the brain tumor of a rat were observed. This large r(1) is discussed in terms of the huge surface to volume ratio (S/V) of the ultrasmall gadolinium oxide nanoparticles coupled with the cooperative induction of surface Gd(III) ions for the longitudinal relaxation of a water proton. It is found from the d dependence of r(1) that the optimal range of d for the maximal r(1), which may be used as an advanced T(1) MRI contrast agent, is 1-2.5 nm.

We studied the role of the matrix metalloproteinase gelatinase B (gelB; MMP-9) in epithelial regeneration using the gelB-deficient mouse. We report the novel finding that, in contrast to other MMPs expressed at the front of the advancing epithelial sheet in wounds of cornea, skin, or trachea, gelB acts to inhibit the rate of wound closure. We determined this to be due to control of cell replication, a novel capacity for MMPs not previously described. We also found that gelB delays the inflammatory response. Acceleration of these processes in gelB-deficient mice is correlated with a delay in signal transduction through Smad2, a transcription factor that inhibits cell proliferation, and in accumulation of epithelial-associated interleukin-1␣, a cytokine that inhibits Smad2 signaling and promotes the inflammatory response. GelB-deficient mice also reveal defects in remodeling of extracellular matrix at the epithelial basement membrane zone, in particular, failure to effectively remove the fibrin(ogen) provisional matrix. We conclude that gelB coordinates and effects multiple events involved in the process of epithelial regeneration.

The subarctic region is highly responsive and vulnerable to climate change. Understanding the structure of subarctic soil microbial communities is essential for predicting the response of the subarctic soil environment to climate change. To determine the composition of the bacterial community and its relationship with soil properties, we investigated the bacterial community structure and properties of surface soil from the moist acidic tussock tundra in Council, Alaska. We collected 70 soil samples with 25-m intervals between sampling points from 0–10 cm to 10–20 cm depths. The bacterial community was analyzed by pyrosequencing of 16S rRNA genes, and the following soil properties were analyzed: soil moisture content (MC), pH, total carbon (TC), total nitrogen (TN), and inorganic nitrogen ( and ). The community compositions of the two different depths showed that Alphaproteobacteria decreased with soil depth. Among the soil properties measured, soil pH was the most significant factor correlating with bacterial community in both upper and lower-layer soils. Bacterial community similarity based on jackknifed unweighted unifrac distance showed greater similarity across horizontal layers than through the vertical depth. This study showed that soil depth and pH were the most important soil properties determining bacterial community structure of the subarctic tundra soil in Council, Alaska.

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