Age-dependent telomere attrition as a potential indicator of racial differences in renal growth patterns.

BACKGROUND: Racial differences in the predilection to salt sensitivity may arise from different renal growth patterns. To test this idea, we monitored age-dependent telomere attrition rate, reflecting largely the replicative history of somatic cells, in the outer renal cortex and the inner renal medulla of African Americans and Caucasians. METHODS: Telomere length, determined by the mean length of the terminal restriction fragments (TRF), was measured in specimens from 58 African-American and 63 Caucasian males, ages 1 day to 71 years. RESULTS: In the outer renal cortex, TRF length attrition rate was significantly slower in African Americans (-0.021 +/- 0.0064 kb/year) than in Caucasians (-0.060 +/- 0.0094 kb/year) (p = 0.0007). In both ethnic groups the TRF length attrition rate was slower in the inner medulla than in the outer renal cortex, but without significant racial differences. CONCLUSIONS: The proximal tubule is the most abundant nephron structure in the outer renal cortex. Less proliferative growth of proximal tubular cells in kidneys from African Americans may be one factor explaining the slower age-dependent telomere attrition rate in the outer renal cortex of African Americans than in Caucasians.

Polyarteritis nodosa: a report from Israel.

BACKGROUND: The clinical manifestations and outcome of all adult patients with polyarteritis nodosa (PAN), allocated during a 15-year period in the largest medical center in Israel, were examined. METHODS: A retrospective analysis of patients with PAN who fulfilled the American College of Rheumatology (ACR) 1990 Classification Criteria and were either biopsy- or angiography-proven. RESULTS: Nine patients were included in the report. The clinical and laboratory manifestations were similar to those in previous studies. All patients were treated with combinations of cyclophosphamide and corticosteroids. There were two (22%) deaths, 2 and 5 months after initiation of treatment in patients who probably had microscopic polyangiitis (MPA) rather than classical PAN. Considering the patients with a complete follow-up, 71% had a complete and long-term remission. Moreover, by exclusion of the two patients with probable MPA who died, all of the five patients with classical PAN were alive and well as of this writing. Two patients (22%) had a long history, since childhood, of familial Mediterranean fever (FMF). CONCLUSIONS: The clinical presentation and course of PAN in Israeli patients is comparable with reports elsewhere. However, a distinction should be made between PAN and MPA. The present report emphasizes the good long-term prognosis of patients with typical PAN who are treated adequately. In addition, a possible association of PAN with FMF in Israeli patients is suggested.