Use of laser flaremetry to measure aqueous humor protein concentration in dogs.

The blood-aqueous barrier in dogs is compromised by uveitis, surgery, and limbal paracentesis. Breakdown of the blood-aqueous barrier allows protein into the aqueous humor and results in mild to severe inflammation. Diagnosis of protein in the aqueous humor is traditionally a subjective measurement. Laser flaremetry was used for noninvasive quantitation of aqueous humor protein concentration in dogs. Flaremetry data were compared with aqueous humor protein concentrations obtained from aqueous humor paracentesis and slit-lamp flare evaluations. Results from clinically normal eyes and those with uveitis and cataracts were compared. Subjective evaluations of flare were correlated with a range of flaremetry readings and aqueous humor protein concentrations. Clinically normal eyes had a range of flaremetry readings of 1.4 to 7.0 photon counts (PC)/ms, with a mean of 3.8 PC/ms. Corresponding aqueous humor protein concentrations ranged from 5 to 28 mg/dl, with a mean of 15.1 mg/dl. Eyes with uveitis or cataracts had a range of aqueous protein concentrations of 13 to 729 mg/dl. Flaremetry readings accurately and sensitively measured total protein concentrations in the aqueous humor of dogs.

The scale of demographic heterogeneity in a population of Peromyscus leucopus.

The patterns of spatial heterogeneity in density and demography were studied in a population of Peromyscus leucopus inhabiting a deciduous forest in west-central Indiana. A series of 9 live-trapping grids sampled densities from 3 spatial scales: 3 ha, 80 ha and 350 km2. We found high levels of variation within all three spatial scales. There was as much variation within a single, large grid as within the entire Sugar Creek Valley (350 km2). The patterns of density variation were not temporally stable and thus represent variation in demographic processes rather than simply differences in habitat quality. We suggest that the Sugar Creek Valley represents a metapopulation of Peromyscus leucopus composed of a number of temporally unstable subpopulations. This structure provides considerable demographic variation that dispersing animals can exploit.