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Biomedical subjects

Sharon M Moe

Publications and source records attributed to Sharon M Moe.

At least 19 recordsLinked to original sources
PubMed2005

Long-term treatment of secondary hyperparathyroidism with the calcimimetic cinacalcet HCl.

BACKGROUND: Patients with secondary hyperparathyroidism often require therapy that provides long-term control of parathyroid hormone concentrations without increasing calcium and phosphorus concentrations. Cinacalcet modulates the calcium-sensing receptor on the parathyroid gland to reduce secretion of parathyroid hormone and lower serum calcium, phosphorus and calcium-phosphorus product in haemodialysis patients. METHODS: Dialysis patients with secondary hyperparathyroidism [parathyroid hormone (PTH) level > or =300 pg/ml] who were enrolled in one of four phase 2 placebo-controlled studies were eligible to enroll in an open-label extension study in which all patients received cinacalcet. For this extension study, cinacalcet was initiated at 30 mg in all patients and the dose was escalated to a maximum of 180 mg once daily if PTH concentrations were >250 pg/ml. Use of concomitant vitamin D sterols and phosphate binders was not restricted. RESULTS: The analysis of all patients (n = 59) completing 100 weeks of cinacalcet treatment showed long-term control of PTH and calcium-phosphorus product. Approximately 55% achieved a PTH concentration < or =300 pg/ml at the week-100 study visit, and approximately 60% had at least a 30% reduction in PTH from baseline. Serum calcium, phosphorus and the calcium-phosphorus product did not increase during the study. Concomitant vitamin D sterol and phosphate binder therapy remained stable. Cinacalcet was safe and generally well tolerated at doses up to 180 mg/day. CONCLUSIONS: In this long-term study, cinacalcet effectively sustained reductions in PTH for up to 3 years without increasing concentrations of serum calcium, phosphorus or calcium-phosphorus product.

Adult↗
PubMed2005

Prevalence of calcidiol deficiency in CKD: a cross-sectional study across latitudes in the United States.

BACKGROUND: Recent Kidney Disease Outcomes Quality Initiative guidelines have raised concerns of 25-hydroxyvitamin D, or calcidiol, insufficiency and deficiency in patients with chronic kidney disease (CKD) not yet on dialysis therapy; however, no cross-sectional study across latitudes has been performed to support this assertion. METHODS: Baseline screening data from a prospective study were used to determine calcidiol levels in subjects with moderate to severe CKD not yet on dialysis therapy from 12 geographically diverse regions of the United States. Calcidiol deficiency is defined as levels less than 10 ng/mL (< 25 nmol/L), and insufficiency, as levels of 10 to 30 ng/mL (25 to 75 nmol/L). RESULTS: Two hundred one subjects with a mean age 65 +/- 13 years and calculated glomerular filtration rate (GFR) of 27 +/- 11 mL/min (0.45 mL/s) were evaluated. Overall mean calcidiol level was 19.4 +/- 13.6 ng/mL (48 +/- 34 nmol/L), with a range of 0 to 65 ng/mL (0 to 162 nmol/L). Only 29% and 17% of subjects with moderate and severe CKD had sufficient levels, respectively. Mean calcidiol levels were less than sufficient levels in all geographic locations tested. Multivariate analysis found log calcidiol level correlated with calcium level (P = 0.016), log calcitriol level (P = 0.024), sex (P = 0.041), geographic location (P = 0.045), and inverse intact parathyroid hormone level (P = 0.013), but not calculated GFR or phosphorous level. Calcidiol levels changed modestly in 18 patients who had calcidiol levels measured in winter and late summer after confirmed exposure to sunlight, with mean calcidiol levels of 17.9 +/- 11.7 to 21.2 +/- 10.0 ng/mL (45 +/- 29 to 53 +/- 25 nmol/L; P = 0.015). CONCLUSION: This cross-sectional cohort study found a high prevalence of calcidiol deficiency and insufficiency in patients with moderate and severe CKD not on dialysis therapy regardless of geographic location.

Adult↗
PubMed2005

Role of calcification inhibitors in the pathogenesis of vascular calcification in chronic kidney disease (CKD).

BACKGROUND: The majority of patients with chronic kidney disease (CKD) have excessive vascular calcification; however, most studies demonstrate that a subset of CKD patients do not have, nor develop, vascular calcification despite similar exposure to the uremic environment. This suggests protective mechanisms, or naturally occurring inhibitors, of calcification may be important. METHODS: In order to determine the role of three inhibitors, fetuin-A, matrix gla protein (MGP), and osteoprotegerin (OPG) in the vascular calcification observed in patients with CKD-5, we (1) measured serum levels of these inhibitors and compared the levels to calcification assessed by computed tomography (CT); (2) examined arteries from CKD-5 patients by immunostaining for these inhibitors; and (3) examined the expression and effect of these inhibitors in cultured bovine vascular smooth muscle cells (BVSMCs) incubated in serum pooled from uremic patients compared to healthy controls. RESULTS: There was a negative correlation of coronary artery calcification scores with serum fetuin-A levels (r=-0.30, P= 0.034) and a positive association with OPG levels (r= 0.29, P= 0.045). There was increasing immunostaining for both fetuin-A and MGP in arteries with increasing calcification graded semiquantitatively (P < 0.003). In vitro, fetuin-A added to mineralizing BVSMCs inhibited mineralization (P < 0.001). Compared to normal serum, BVSMCs incubated with uremic serum had a progressive increase in MGP expression with mineralization (P < 0.001) and increased expression of OPG in BVSMCs (P < 0.04). CONCLUSION: These data demonstrate that fetuin-A, OPG, and MGP play an important role in the pathogenesis of uremic vascular calcification.

Animals↗
PubMed2005

Achieving NKF-K/DOQI bone metabolism and disease treatment goals with cinacalcet HCl.

BACKGROUND: The National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (NKF-K/DOQItrade mark) has established guidelines for treatment of secondary hyperparathyroidism (HPT). The ability of cinacalcet HCl (Sensipartrade mark) treatment to improve achievement of target levels of parathyroid hormone (PTH), calcium, phosphorus, and calcium-phosphorus product (Ca x P) was investigated in subjects on dialysis with secondary HPT. METHODS: Data were combined from three placebo-controlled, double-blind, 26-week studies with similar design that randomized 1136 subjects on dialysis to receive traditional therapy plus cinacalcet or placebo. Oral cinacalcet was titrated from 30 to 180 mg/day. Achievement of K/DOQI goals was determined for each treatment group overall and for subgroups defined by baseline intact PTH (iPTH) and Ca x P levels. RESULTS: Cinacalcet-treated subjects were more likely to achieve a mean iPTH </=300 pg/mL (31.8 pmol/L) than were control subjects on traditional therapy (56% vs. 10%, P < 0.001). Cinacalcet-treated subjects were more likely to achieve concentrations of serum calcium within 8.4 to 9.5 mg/dL (2.10-2.37 mmol/L) and serum phosphorus within 3.5 to 5.5 mg/dL (1.13-1.78 mmol/L) than were control subjects (49% vs. 24% and 46% vs. 33%, P < 0.001 for each). Cinacalcet also improved achievement of Ca x P < 55 mg(2)/dL(2) (4.44 mmol(2)/L(2)) and concurrent achievement of Ca x P < 55 mg(2)/dL(2) (4.44 mmol(2)/L(2)) and iPTH </=300 pg/mL (31.8 pmol/L) (65% vs. 36% and 41% vs. 6%, P < 0.001 for each). CONCLUSION: In subjects on dialysis with secondary HPT, cinacalcet facilitates achievement of the K/DOQI-recommended targets for PTH, calcium, phosphorus, and Ca x P.

Adult↗
PubMed2005

Inflammation and vascular calcification.

Both vascular calcification and inflammation are common in patients with chronic kidney disease (CKD). In patients on dialysis, there is increased coronary artery and peripheral artery calcification compared to the general population. Both intimal (atherosclerotic) and medial calcification in CKD patients are associated with increased morbidity and mortality. Vascular calcification is an active cell-mediated process, and likely reflects a transformation of vascular smooth muscle cells to osteoblast-like cells. Pooled uremic serum can induce this transformation, but the mechanism by which it does so is not yet clear. Several mediators of inflammation such as oxidation, carbonyl stress, C-reactive protein, and cytokines may directly stimulate vascular calcification. In addition, inflammation itself reduces fetuin-A, a naturally occurring inhibitor of vascular calcification which binds excess mineral in serum. The combination of the acceleration of vascular calcification together with impaired defense mechanisms creates a uremic milieu primed for extra-osseous calcification.

Calcinosis↗
PubMed2004

Pathophysiology of vascular calcification in chronic kidney disease.

Patients with chronic kidney disease (CKD) on dialysis have 2- to 5-fold more coronary artery calcification than age-matched individuals with angiographically proven coronary artery disease. In addition to increased traditional risk factors, CKD patients also have a number of nontraditional cardiovascular risk factors that may play a prominent role in the pathogenesis of arterial calcification, including duration of dialysis and disorders of mineral metabolism. In histological specimens from the inferior epigastric artery of dialysis patients, we have found expression of the osteoblast differentiation factor core binding factor alpha-1 (Cbfa1) and several bone-associated proteins (osteopontin, bone sialoprotein, alkaline phosphatase, type I collagen) in both the intima and medial layers when calcification was present. In cultured vascular smooth muscle cells, the addition of pooled serum from dialysis patients (versus normal healthy controls) accelerated mineralization and increased expression of Cbfa1, osteopontin, and alkaline phosphatase to a similar magnitude as does beta-glycerophosphate alone. However, a lack of inhibitors of calcification may also be important. Dialysis patients with low levels of serum fetuin-A, a circulating inhibitor of mineralization, have increased coronary artery calcification and fetuin-A can inhibit mineralization of vascular smooth muscle cells in vitro. These data support that elevated levels of phosphorus and/or other potential uremic toxins may play an important role by transforming vascular smooth muscle cells into osteoblast-like cells, which can produce a matrix of bone collagen and noncollagenous proteins. This nidus can then mineralize if the balance of pro-mineralizing factors outweighs inhibitory factors.

Animals↗
PubMed2004

Natural history of vascular calcification in dialysis and transplant patients.

BACKGROUND: The purpose of the present study was to determine the natural history of coronary artery and aorta calcification by spiral computed tomography (CT) in patients who undergo a renal transplant and patients on haemodialysis. METHODS: Two cohorts were evaluated for the natural history of vascular calcification: (i) 23 patients who underwent a baseline CT scan at the time of renal transplant and a repeat evaluation 15-20 months later; and (ii) 33 chronic kidney disease, stage 5 haemodialysis subjects who underwent a baseline CT scan, all followed for a minimum of 15 months, and 17 of whom underwent a second CT scan. RESULTS: In the patients undergoing a renal transplant, there was no net change in CAC with time, suggesting stabilization of calcification. In the haemodialysis patients, the median CAC increased by 1.27+/-1.88 score/days, P = 0.013. There was a trend towards increasing AoC score in both groups. All patients without calcification at baseline remained calcification free at follow-up. In the 15 months following baseline, the six dialysis patients who died had a significantly greater CAC score at baseline compared with the 24 patients who remained alive. Similarly, those patients who were hospitalized had a greater baseline CAC than patients who were not hospitalized. CONCLUSION: In this preliminary study, renal transplantation appears to slow down or arrest CAC, whereas CAC progresses in haemodialysis patients. In haemodialysis patients, CAC was greater in patients who died or were hospitalized compared with those who remained alive or were not hospitalized.

Adult↗
PubMed2004

Cinacalcet for secondary hyperparathyroidism in patients receiving hemodialysis.

BACKGROUND: Treatment of secondary hyperparathyroidism with vitamin D and calcium in patients receiving dialysis is often complicated by hypercalcemia and hyperphosphatemia, which may contribute to cardiovascular disease and adverse clinical outcomes. Calcimimetics target the calcium-sensing receptor and lower parathyroid hormone levels without increasing calcium and phosphorus levels. We report the results of two identical randomized, double-blind, placebo-controlled trials evaluating the safety and effectiveness of the calcimimetic agent cinacalcet hydrochloride. METHODS: Patients who were receiving hemodialysis and who had inadequately controlled secondary hyperparathyroidism despite standard treatment were randomly assigned to receive cinacalcet (371 patients) or placebo (370 patients) for 26 weeks. Once-daily doses were increased from 30 mg to 180 mg to achieve intact parathyroid hormone levels of 250 pg per milliliter or less. The primary end point was the percentage of patients with values in this range during a 14-week efficacy-assessment phase. RESULTS: Forty-three percent of the cinacalcet group reached the primary end point, as compared with 5 percent of the placebo group (P<0.001). Overall, mean parathyroid hormone values decreased 43 percent in those receiving cinacalcet but increased 9 percent in the placebo group (P<0.001). The serum calcium-phosphorus product declined by 15 percent in the cinacalcet group and remained unchanged in the placebo group (P<0.001). Cinacalcet effectively reduced parathyroid hormone levels independently of disease severity or changes in vitamin D sterol dose. CONCLUSIONS: Cinacalcet lowers parathyroid hormone levels and improves calcium-phosphorus homeostasis in patients receiving hemodialysis who have uncontrolled secondary hyperparathyroidism.

Calcium↗
PubMed2004

Uremic vasculopathy.

Recent evidence suggests that uremic vascular calcification is an active cell-mediated process resembling osteogenesis in bone rather than passive precipitation. We have identified increased expression of bone-associated proteins (osteopontin, bone sialoprotein, alkaline phosphatase, type I collagen), and the bone-specific transcription factor core-binding factor alpha-1 (Cbfa1) in histologic sections of inferior epigastric arteries obtained from patients with end-stage renal disease (ESRD) or calcific uremic arteriolopathy. In in vitro experiments, the addition of uremic serum to cultured vascular smooth muscle cells up-regulated osteopontin and Cbfa1 expression and accelerated mineralization. This implies that the uremic milieu may lead to dedifferentiation of vascular smooth muscle cells with subsequent mineralization. Further understanding of the pathophysiology of uremic vascular calcification is needed to design effective therapeutic strategies to intervene with this devastating condition in ESRD patients.

Calcinosis↗
PubMed2004

Vascular calcification in chronic kidney disease.

Dialysis patients have increased cardiovascular morbidity, mortality, and vascular calcification, and the latter appears to impact the former. Recent evidence indicates that vascular calcification is an active, cell-mediated process. Osteoblast differentiation factor Cbfa1 and several bone-associated proteins (osteopontin, bone sialoprotein, alkaline phosphatase, type I collagen) are present in histologic sections of arteries obtained from patients with end-stage renal disease (chronic kidney disease stage V [CKD-V]). This supports the theory that vascular smooth muscle cells can dedifferentiate or transform to osteoblast-like cells, possibly by up-regulation of Cbfa1. In in vitro experiments, addition of pooled serum from dialysis patients (versus normal healthy controls) accelerated mineralization and increased expression of Cbfa1, osteopontin, and alkaline phosphatase in cultured vascular smooth muscle cells. Clinically, the pathogenesis of vascular calcification is not completely understood, although increased levels of phosphorus and/or other potential uremic toxins may play an important role by transforming vascular smooth muscle cells into osteoblast-like cells. Presumably, once this process begins, increased serum calcium X phosphorus product, or calcium load from binders, accelerates this process. In addition, it is likely that circulating inhibitors of calcification are also important. Further understanding of the pathophysiology of vascular calcification is needed to intervene appropriately.

Calcinosis↗
PubMed2003

Management of secondary hyperparathyroidism: the importance and the challenge of controlling parathyroid hormone levels without elevating calcium, phosphorus, and calcium-phosphorus product.

Secondary hyperparathyroidism (HPT) is a common complication of chronic kidney disease (CKD) that can lead to clinically significant bone disease. Additional consequences of secondary HPT, such as soft-tissue and vascular calcification, cardiovascular disease, and calcific uremic arteriolopathy, may contribute to the increased risk of cardiovascular morbidity and mortality among CKD patients. Secondary HPT arises from disturbances in calcium, phosphorus, vitamin D and parathyroid hormone metabolism, which develop early in the course of CKD and become more prominent as kidney function declines. The standard therapies currently recommended to correct mineral metabolism and bone disease in these patients include calcium supplementation, dietary phosphorus restriction, phosphate-binding agents, and treatment with vitamin D sterols. However, such medications often have significant effects on the serum levels of calcium and phosphorus, which result in exacerbation of the disease and significant extraskeletal morbidity and mortality. Thus, there is a need to identify more effective treatment approaches. This review discusses the pathophysiology of secondary HPT, the challenges faced in the management of this disorder, and the impact of current treatment options on patients' risks of morbidity and mortality. In addition, the development of new, more physiologically relevant therapies, which may lead to successful management of secondary HPT, is reviewed.

Calcitriol↗