Nephrology in Brief

Abstract

The bone morphogenic protein (BMP) antagonist gremlin was highly expressed in the cellular and fibrocellular crescents of 30 renal biopsies of patients with pauciimmune glomerulonephritis—as well as in renal tubular and infiltrating interstitial cells. It correlated with tubulointerstitial fibrosis and co-localized with transforming growth factor beta (TGF-β), suggesting that it may be important in mediating some of its pathological effects (Nephrol Dial Transpl 22: 1882). Soluble F11 receptor (F11R) is elevated in dialysis patients and may be yet another marker of increased cardiovascular risk. It is a cell adhesion molecule expressed on the membrane surface of platelets and related to the murine protein present in the tight junctions of the vascular endothelium. In activated platelets F11R becomes phosphorylated and causes cell adhesion and aggregation—the initial step of thrombus formation in the pathogenesis of atherosclerotic plaques (J Invest Med 55:115). In order to study the mechanism of renal injury from light chains, cell cultures of human proximal cells were incubated with light chains derived from the urine of patients with multiple myeloma. This resulted in the cells producing hydrogen peroxide and monocyte chemo-attractant protein-1, both inherently nephrotoxic (J Am Soc Nephrol 18:1239). The use of estimated glomerular filtration rate (GFR) derived from the serum creatinine concentration is fraught with pitfalls. It tends to undererestimate renal function in persons with no known kidney disease and overestimate it in emaciated patients with low muscle mass and reduced creatinine production. Also problematic is its use in acute renal failure, where the change in serum creatinine is more important (BMJ 334:1198, Nephrol Dial Transplant 22:2391). Subjects in the Framingham study who had both microalbuminuria and reduced eGFR had worse cardiovascular outcomes than those with only one of these abnormalities (Arch Int Med 167:1386 2007). A study of type II diabetics with nephropathy found that simvastatin, unlike cholestyramine, appears to stabilize GFR, possibly by increasing messenger RNA expression of slit diaphragm associated proteins and reducing the albumin excretion rate (Kidney Int 70:177–186). The administration of iodine containing contrast media to a hemodialysis patient resulted in so-called iodine gout, an acute and dramatic swelling of the thyroid and salivary glands. This rare idiosyncratic complication may be related to toxic accumulation of iodide in the salivary gland ducts. The patient improved dramatically within 48 h of high-dose prednisolone therapy (Nephrol Dial Transpl 22: 1250)