A circulating factor found in some patients with focal segmental glomerulosclerosis is associated with recurrent disease after renal transplantation and may be responsible for initiating the renal injury.

AMBP measurements were obtained at 20-min intervals during the day and at 60-min intervals during the night in 38 adolescents and young adults (12-25 yr old) with type I diabetes, and in 36 healthy, nondiabetic control subjects of comparable age. The group of patients with elevated AER (greater than 15 micrograms/min) had higher mean 24-h sBP, dBP, and BPB (defined as the prevalence of systolic readings greater than 130 mm Hg or diastolic readings greater than 85 mm Hg) compared with both the group of patients with type I diabetes and AER less than 15, and the control group. The normal diurnal variation in BP and BPB was observed in the control group and the group with type I diabetes and AER less than 15, whereas the nocturnal decrease observed in the group with type I diabetes and AER greater than 15 was not statistically significant. Elevations in AMBP of the patient group with AER greater than 15 were reflected in random BP measurements. Even though the mean random BP measurements of all groups were within the normal range for age, the mean random sBP and dBP of the type I diabetes patients with AER greater than 15 was higher than both the control group and the group with type I diabetes and AER less than 15. The GFR, determined by the clearance of 99Tc-DTPA, was associated negatively with measures of AMBP and AER in the group with AER greater than 15.(ABSTRACT TRUNCATED AT 250 WORDS)

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Para-aminohippurate (PAH) is secreted at different rates in S1, S2, and S3 segments of isolated perfused proximal tubules of rabbit kidney. To characterize PAH transport we determined the maximal rate of secretion (Vmax) and the apparent Michaelis constant (Km) for each segment by examining the relationship between bath concentration of PAH and net PAH secretion (Jb leads to lPAH) transposed for Lineweaver-Burk analysis. The passive component of secretion for all segments was estimated by slope analysis at relatively high concentrations of PAH, by the component of PAH secretion insensitive to inhibition by probenecid, and, additionally, in S2 segments, from PAH efflux from lumen to bath. Subtraction of the passive component from Jb leads to lPAH (probenecid method) gave Vmax values for S1, S2, and S3 segments of 1,097 +/- 336 (n = 6), 7,430 +/- 1,338 (n = 6), 1,647 +/- 138 (n = 8) X 10(-15) mol.min-1.mm-1 (+/- SE) and apparent Km values of 139 +/- 37 (n = 6), 195 +/- 37 (n = 6), and 113 +/- 16 (n = 6) X 10(-6) M, respectively. Thus, Vmax for S2 greater than S3 congruent to S1, whereas apparent Km was not consistently different among the segments. On the basis of these results we suggest that axial heterogeneity of PAH secretion may reflect an increased basolateral membrane density of PAH transporters of common affinity in the S2 segment of the proximal tubule.

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