The relationship of peritubular capillary density with glomerular volume and kidney function in living kidney donors.

BACKGROUND: Peritubular capillary rarefaction plays an important role in the progression of chronic kidney disease. Little is known about the relation between peritubular capillary density, glomerular volume and filtration rate in the healthy kidney. METHODS: In this single-center study, we included 69 living kidney donors who donated between 2005 and 2008 and had representative renal biopsies available. In all donors, glomerular filtration rate was measured using 125I-Iothalamate before donation and at five years after donation. Before donation, the increase in glomerular filtration rate after dopamine stimulation was measured. Glomerular volume and peritubular capillary density were determined in biopsies taken at the time of transplantation. Pearson's correlation coefficient and linear regression were used to assess relations between parameters. RESULTS: Mean donor age was 52 ± 11 years and mean measured glomerular filtration rate was 119 ± 22 mL/min before donation and 82 ± 15 mL/min at five years after donation. While peritubular capillary density (measured by either number of peritubular capillaries/50,000 µm2 or number of peritubular capillaries/tubule) was not associated with measured glomerular filtration rate before or after donation, number of peritubular capillaries/tubule was associated with the increase in measured glomerular filtration rate after dopamine stimulation (St.ß = 0.33, p = 0.004), and correlated positively with glomerular volume (R = 0.24, p = 0.047). Glomerular volume was associated with unstimulated measured glomerular filtration rate before donation (St.ß = 0.31, p = 0.01) and at five years (St.ß = 0.30, p = 0.01) after donation, independent of age. CONCLUSIONS: In summary, peritubular capillary density was not related to unstimulated kidney function before or after kidney donation, in contrast to glomerular volume. However, number of peritubular capillaries/tubule correlated with the increase in glomerular filtration rate after dopamine stimulation in healthy kidneys, and with glomerular volume. These findings suggest that peritubular capillary density and glomerular volume differentially affect kidney function in healthy living kidney donors.

OKAS-3D: optoelectronic jaw movement recording system with six degrees of freedom.

OKAS-3D is a further development of the single floating circle target tracker. This tracker consists of a cathode ray tube display, a lens in front of the display and a circular light-sensitive photocell placed in the image field of the lens. A small circular trace generated on the screen is focused around the photocell. The sinusoidal electrical output of the photocell contains all the relevant information regarding the position of the photocell relative to the image of the circular light trace. This gives the tracker the properties of a servo-controller with position feedback. In OKAS-3D three pairs of photocells are located on two lightweight frames attached to the upper and lower frontal teeth by individually adapted clutches. By using the formulas of rigid body mathematics, the motion of any point of the mandible can be reconstructed. The system permits a high sampling frequency of at least 300 Hz per photocell co-ordinate. The noise, linearity and accuracy are better than 0.08 mm, 0.07 mm and 0.13 mm for points in the lower incisal region, and better than 0.25 mm, 0.17 mm and 0.27 mm for points in the condylar region. Thus jaw movements can be recorded with a high spatial and temporal resolution.