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IgA nephropathy (IgAN) is a common form of glomerulonephritis that leads to end-stage renal disease at variable rates in 20% to 30% of cases. A rational approach to therapy requires an understanding of pathogenetic mechanisms that are largely unknown. Several therapeutic approaches have been used, generally in uncontrolled trials, aimed at lowering levels of circulating immune complexes, affecting cellular immunity, or removing antigens through dietary restriction. Thus far, no clear-cut beneficial effects are evident. Alternative means of changing glomerular hemodynamics through prevention of harmful mediators await exploration.

The level and average functional affinity of anti-DNA antibody were measured retrospectively in successive serum samples from 5 patients with systemic lupus erythematosus. In 2 patients, severe flares of disease activity were associated with an increase in the level and average functional affinity of anti-DNA antibodies. Three patients who did not experience significant flares in disease activity exhibited more constant levels of antibody of lower average functional affinity. The appearance of antibody of high functional affinity during disease exacerbations suggests that such antibodies may be pathogenic.

Mesangial cells have receptors for angiotensin II (AII) and contract in its presence. All is known also to increase the uptake of macromolecules by the mesangium. As a first step towards the investigation of a possible role for local disturbances of the renin-angiotensin system (RAS) in immune mediated mesangial proliferative glomerulonephritis, glomerular All receptors have been quantitated retrospectively in biopsy tissue from 20 patients with IgA nephropathy for comparison with 16 biopsies that showed only minor abnormalities by light microscopy and negative immunofluorescence. An autoradiographic technique using 125I labelled [Sar1, Ile8] All facilitated the quantitation of All receptors in frozen tissue sections. Following exposure to the treated sections, x-ray film was analyzed by computerized micro-densitometry. The data obtained were optical densities of areas corresponding to the presence of glomeruli verified by reference to adjacent sections stained with periodic acid-Schiff (PAS). There was no significant difference between patients 0.67 +/- 0.16 (mean +/- SD) and controls 0.61 +/- 0.15. Among patients there was no statistically significant correlation of glomerular All receptor density with either the degree of mesangial proliferation or the extent of hyperplasia of the juxtaglomerular apparatus (JGA). There was no apparent relationship with hypertension. The absence of an increase in glomerular All receptors despite proliferation of the glomerular mesangium may represent a local down regulation in patients with IgA nephropathy.

Thirteen patients who had in common the clinical finding of shortened forearm flexors were investigated. Additional findings were Raynaud's phenomenon, arthralgia, reduced pulmonary CO diffusion capacity, abnormal EMG, and histological evidence of myopathy. Clinical and serological features in 2 patients were consistent with features described in the mixed connective tissue disease syndrome. The remainder were regarded as having a limited connective tissue disease syndrome, in all probability, a minimal expression of systemic sclerosis. We suggest that the finding of bowed fingers is a more reliable clinical sign than the assessment of skin texture in determining the presence of minimal connective tissue disease.

Extinction coefficients k(lambda) for water at 25 degrees C were determined through a broad spectral region by manually smoothing a point by point graph of k(lambda) vs wavelength lambda that was plotted for data obtained from a review of the scientific literature on the optical constants of water. Absorption bands representing k(lambda) were postulated where data were not available in the vacuum uv and soft x-ray regions. A subtractive Kramers-Kronig analysis of the combined postulated and smoothed portions of the k(lambda) spectrum provided the index of refraction n(lambda) for the spectral region 200 nm

Relative specular reflectance R is defined as R = R(s)/R(w), where R(s) and R(w) are absolute reflectances of a sample material s and a material w for which the index of refraction n(w) and the extinction coefficient k(w) are known quantities. An algorithm was developed for computing n(s)and k(s) from the sample's R spectrum measured for radiant flux polarized perpendicular to the plane of incidence and reflected at oblique angle theta. Kramers-Kronig analysis of the R spectrum provides DeltaPhi the difference between phase shifts for electromagnetic waves reflected at the surfaces of materials s and w. Real and imaginary parts of a Fresnel equation for relative reflectivity provide equations for computing n(s) and k(s) when theta, DeltaPhi n(w), and k(w) are known quantities. Optical constants for aqueous solutions containing NaCl were computed in this manner; distilled water was the reflectance standard.