Faculty Bibliography

Bone morphogenic protein (BMP)-7 is a 35-kDa homodimeric protein and a member of the transforming growth factor (TGF)-beta superfamily. BMP-7 expression is highest in the kidney, and its genetic deletion in mice leads to severe impairment of eye, skeletal and kidney development. Here we report that BMP-7 reverses TGF-beta1-induced epithelial-to-mesenchymal transition (EMT) by reinduction of E-cadherin, a key epithelial cell adhesion molecule. Additionally, we provide molecular evidence for Smad-dependent reversal of TGF-beta1-induced EMT by BMP-7 in renal tubular epithelial cells and mammary ductal epithelial cells. In the kidney, EMT-induced accumulation of myofibroblasts and subsequent tubular atrophy are considered key determinants of renal fibrosis during chronic renal injury. We therefore tested the potential of BMP-7 to reverse TGF-beta1-induced de novo EMT in a mouse model of chronic renal injury. Our results show that systemic administration of recombinant human BMP-7 leads to repair of severely damaged renal tubular epithelial cells, in association with reversal of chronic renal injury. Collectively, these results provide evidence of cross talk between BMP-7 and TGF-beta1 in the regulation of EMT in health and disease.

There are about 2.5 million glomeruli in the kidneys each consisting of a barrel of glomerular basement membrane surrounded by glomerular endothelial cells on the inside and glomerular epithelial cells with established foot processes (podocytes) on the outside. Defects in this filtration apparatus lead to glomerular vascular leak or proteinuria. The role of vascular endothelial growth factor (VEGF) in the regulation of glomerular vascular permeability is still unclear. Recent studies indicate that patients receiving anti-VEGF antibody therapy may have an increased incidence of proteinuria. In a different setting, pregnancies complicated by preeclampsia are associated with elevated soluble VEGF receptor 1 protein (sFlt-1), endothelial cell dysfunction and proteinuria. These studies suggest that neutralization of physiologic levels of VEGF, a key endothelial survival factor, may lead to proteinuria. In the present study, we evaluated the potential of anti-VEGF neutralizing antibodies and sFlt-1 in the induction of proteinuria. Our studies demonstrate that anti-VEGF antibodies and sFlt-1 cause rapid glomerular endothelial cell detachment and hypertrophy, in association with down-regulation of nephrin, a key epithelial protein in the glomerular filtration apparatus. These studies suggest that down-regulation or neutralization of circulating VEGF may play an important role in the induction of proteinuria in various kidney diseases, some forms of cancer therapy and also in women with preeclampsia.

BACKGROUND:Although the methods for the appropriate management of patients with hyperkalemia are well established, no criteria for hospital admission of patients with this common electrolyte disorder have been promulgated. OBJECTIVES/OBJECTIVE:To examine the current practices regarding hospitalization of patients with hyperkalemia and to consider appropriate criteria for admission. PATIENTS AND METHODS/METHODS:We evaluated a consecutive series of patients hospitalized for hyperkalemia and excluded patients who developed hyperkalemia after admission. For comparison, we selected a series of patients with a similar degree of hyperkalemia who were treated as outpatients. Hyperkalemia was classified as minimal, moderate, or severe. The causes of hyperkalemia were identified, and the therapeutic maneuvers used were ascertained. Although the study did not have the power to determine the relative safety of the 2 therapeutic approaches, we compared the outcomes of the 2 groups of patients. RESULTS:The inpatient group consisted of 11 patients who were admitted for the treatment of hyperkalemia, and we identified 12 patients who received outpatient therapy for hyperkalemia. The patients in the 2 treatment groups were similar with respect to age and the values of serum urea nitrogen, creatinine, and potassium prior to the identification of hyperkalemia. The mean +/-SD potassium concentrations at baseline were 5.4+/-0.7 mmol/L in the inpatients and 5.5+/-0.5 mmol/L in the outpatients. The mean +/-SD potassium concentration in the inpatients was 6.7+/-0.8 mmol/L at the time of hospital admission, compared with 6.7+/-0.5 mmol/L in the outpatients at the time that hyperkalemia occurred. Similar proportions of both groups (6 of 11 inpatients and 7 of 12 outpatients) had moderate or severe hyperkalemia. CONCLUSIONS:Patients admitted to the hospital were clinically indistinguishable from patients treated as outpatients. The justification for the decision to admit patients to the hospital or to treat them as outpatients was often not evident. We suggest criteria for hospitalization, which include severe hyperkalemia (> or =8.0 mmol/L, with changes other than peaked T waves on the electrocardiogram), acute worsening of renal function, and supervening medical problems.