Biomedical subjects

Georges Saab

Publications and source records attributed to Georges Saab.

4 recordsLinked to original sources

PubMed2007

Prevalence of vitamin D deficiency and the safety and effectiveness of monthly ergocalciferol in hemodialysis patients.

BACKGROUND: Vitamin D deficiency is common in CKD and dialysis patients. Studies suggest a physiologic autocrine and/or paracrine role for 1,25(OH)D produced via 1alpha-hydroxylase in tissues such as vascular smooth muscle, breast, prostate, and bone marrow. Studies have not yet defined the optimal dose and duration of vitamin D necessary to replete and maintain stores in dialysis patients, or whether it is safe or beneficial. METHODS: We performed a review of the prevalence of vitamin D deficiency and the safety and effectiveness of ergocalciferol oral supplementation (vitamin D(2), 50,000 IU monthly) given to hemodialysis patients during dialysis May to October 2005 in St. Louis (latitude 38 degrees ). RESULTS: Among the 119-patient cohort present for the entire 6 months, 25(OH)D was (mean +/- SD) 16.9 +/- 8.5 ng/ml, (91% < 30 ng/ml) and increased to 53.6 +/- 16.3 ng/ml (p < 0.001), (95% > 30 ng/ml, and none > 100 ng/ml). Initial versus 6 mo. serum calcium (9.1 +/- 0.56 vs. 9.2 +/- 0.70), phosphorus (5.25 +/- 1.38 vs. 5.11 +/- 1.31), Ca x P, and paricalcitol dose (10.3 +/- 9.6 vs. 11.3 +/- 9.2 mcg/week) were not significantly different. No hypercalcemia could be attributed to supplementation. Mean hemoglobin did not change significantly (11.96 +/- 1.4 vs. 11.69 +/- 1.4, p = 0.124), but most patients experienced a reduced weekly epoetin dose. Epoetin dose decreased in 64% of patients, and increased in 28%. CONCLUSIONS: We conclude that the vast majority of hemodialysis patients are vitamin D-deficient; monthly ergocalciferol 50,000 IU is safe and effective in normalizing serum 25(OH)D levels and may have an epoetin-sparing effect.

Adult↗

PubMed2005

Bone morphogenetic proteins in vascular calcification.

Vascular calcification is a common problem among the elderly and those with chronic kidney disease (CKD) and diabetes. The process of tunica media vascular calcification in CKD appears to involve a phenotypic change in the vascular smooth muscle cell (VSMC) resulting in cell-mediated mineralization of the extracellular matrix. The bone morphogenetic proteins (BMPs) are important regulators in orthotopic bone formation, and their localization at sites of vascular calcification raises the question of their role. In this review, we will discuss the actions of the BMPs in vascular calcification. Although the role of BMP-2 in vascular calcification is not proven, it has been the most studied member of the BMP family in this disease process. The role of BMP-2 may be through inducing osteoblastic differentiation of VSMCs through induction of MSX-2, or by inducing apoptosis of VSMCs, a process thought critical in the initiation of vascular calcification. Additionally, BMP-2 may be related to loss of regulation of the matrix Gla protein. A second BMP, BMP-7, less studied than BMP-2 may have opposing actions in vascular calcification. In postnatal life, BMP-7 is expressed primarily in the kidney, and expression is diminished by renal injury. BMP-7 is an important regulator of skeletal remodeling and the VSMC phenotype. BMP-7 restores skeletal anabolic balance in animal models of CKD with disordered skeletal modeling, also reducing serum phosphate in the process. BMP-7 also reverses vascular calcification in CKD, and reduction in vascular calcification is due, in part, to reduced serum phosphate, an important inducer of VSMC-mediated vascular mineralization and in part to direct actions on the VSMC.

Animals↗

PubMed2004

Kidney-bone, bone-kidney, and cell-cell communications in renal osteodystrophy.

The relationship between bone and the kidney in renal osteodystrophy is a complex interplay of kidney to bone connections, bone to kidney connections, and cell to cell connections. In addition, such interactions have a profound effect on the vasculature. In this review, we discuss the role of the bone morphogenetic proteins (BMPs) in the skeleton, kidney, and vasculature. In addition, we propose that deficiencies of these BMPs seen in chronic kidney disease (CKD) result in decreased bone remodeling and a compensatory secondary hyperparathyroidism (high turnover state). Treatment of the hyperparathyroidism blocks this compensatory arm and thus decreased bone remodeling occurs (low turnover). We review animal models of CKD in which treatment with BMP-7 resulted in normalization of both high and low turnover states. Finally, we discuss vascular calcification as it relates to bone metabolism. We discuss the roles of BMP-7 and 2 other bone regulatory proteins, osteoprotegerin (OPG) and alpha2-HS glycoprotein (AHSG, human fetuin), in the human vasculature and their implications for vascular calcification.

Bone Morphogenetic Proteins↗

PubMed2002

Acute renal failure secondary to milrinone in a patient with cardiac amyloidosis.

Milrinone is a phosphodiesterase type III inhibitor with positive inotropic and vasodilatory effects. A common side effect of milrinone is hypotension from the peripheral vasodilation. Although mild elevations in serum creatinine have been described previously in the setting of milrinone-induced hypotension, acute oligoanuric renal failure requiring renal replacement therapy has not yet been described. This case report is the first to document such a result and to report the successful use of peritoneal dialysis in this setting. Previous case reports documented vasopressin as an effective alternative to catecholamines in the treatment of milrinone-induced hypotension. This report documents the use of four vasopressor agents (including vasopressin) in this patient, with only vasopressin resulting in improvement in systemic vascular resistance and blood pressure. Vasopressin may be the most effective vasopressor agent in the treatment of milrinone-induced hypotension.

Acute Kidney Injury↗