Patterns of glomerular reaction to injury. A teaching syllabus

The thickness of the glomerular basement membrane in irradiated and unirradiated Wistar rats and C-57 BL mice of different age groups

In both Wistar rats and C-57 BL mice, the thickness of the glomerular basement membrane increases progressively with age. This change, which can be measured in cohorts of manageable size, produces a measurement of biological age--if one accepts the assumption that it correlates with the viability of the organism that exhibit it. Whole-body exposure to x-rays has no observable influence on this age-related change.

The measurement of biological age

One of the objectives of gerontological research is to achieve, reproducibly and at will, a verifiable discrepancy between the chronological and biological age of organisms. To accomplish this, the experimenter must be in a position to measure biological age independently. In theory, this can be done in the three ways: by actuarial analysis of large populations, assessment of overall morbidity, or observation of chronic degenerative changes that can be actually measured or graded according to a scale. Of these three approaches, only the last appears to be promising in experimental research. However, not all progressive degenerative changes represent practically useful parameters of biological age. Criteria for their evaluation are presented, and their theoretical prerequisites as well as concrete applications discussed. In a more general way, one has to be aware that biological age is a statistical entity. It cannot be directly observed but only inferred from quantifiable epiphenomena, and is, as such, not measurable like temperature or weight.

Early pathologic features of hereditary nephritis: a clinicopathologic correlation

The histologic, immunofluoresence and electron microscopic features of renal biopsies from twelve patients having hereditary nephritis were examined and correlated with the clinical data. In ten patients with normal renal function, light microscopy showed similar but nonspecific glomerular abnormalities consisting of mild focal and segmental hypercellularity and thickening of capillary walls. Biopsies from two patients with azotemia had diffuse lesions of the glomeruli and associated interstitial fibrosis. There were no characteristic findings on immunofluorescence. Electron microscopy revealed alterations in thickness and density of the glomerular capillary basal lamina in all patients. However, lamellation of the basement membrane and the presence of electron dense granules were present only in the two patients with renal functional impairment. These findings support the view that hereditary nephritis is a form of glomerular disease in which ultrastructural changes in the basal lamina of glomerula capillaries are the earliest and most consistent lesions. However, the morphologic spectrum of these ultrastructural abnormalities is broader than previously recognized.