David A. Ontjes

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BACKGROUND Osteoporosis occurs in patients with cystic fibrosis as they age, but its clinical implications are not well defined. OBJECTIVE To determine the clinical effect of decreased bone mineral density in adults with cystic fibrosis and to assess possible clinical predictors of osteoporosis. DESIGN Retrospective cohort study. SETTING Academic(More)
Lung transplantation with its attendant life-long immunosuppression contributes to bone loss and its sequelae, fractures and kyphosis, in patients with lung disease, many of whom already suffer from severe osteoporosis. Patients with cystic fibrosis (CF) are one of the most severely affected groups. We conducted a controlled, randomized, nonblinded trial of(More)
Pentagastrin is a potent stimulator of thyrocalcitonin secretion from "C" cells. Since medulllary carcinoma of the thyroid gland (MCT) is a tumor composed of "C" cells, pentagastrin was used to screen a large kindred with multiple endocrine neoplasia type II (MCT, pheochromocytoma (s), and parathyroid hyperplasia). Four children with no thyroid(More)
STUDY OBJECTIVE Osteoporosis and/or fractures have been reported as a complication of kidney, heart, liver, bone marrow, and, most recently, lung transplantation (LTx). We measured bone mineral density (BMD) before and after LTx to determine the frequency and severity of preoperative and postoperative osteoporosis. PATIENTS AND METHODS We conducted a(More)
The in vitro secretion of PTH by dispersed human parathyroid cells was examined under conditions of low and high extracellular Ca+2 using tissue from patients with primary hyperparathyroidism and hyperparathyroidism resulting from chronic renal failure (CRF). The PTH secretion rate (nanograms of PTH per 10(5) cells/h) was lower in adenomatous tissues than(More)
Cystic fibrosis (CF) patients often have low bone mineral density (BMD) and may suffer from fractures and kyphosis. The pathogenesis of low BMD in CF is multifactorial. To study bone metabolism, we collected fasting serum and urine from 50 clinically stable CF adults (mean age 28 years) and 53 matched controls to measure markers of bone formation and bone(More)
As adults with cystic fibrosis (CF) have enjoyed incremental increases in longevity over the last few decades, they have also been suffering from low bone density and its clinical manifestations, fractures and kyphosis. We conducted a placebo-controlled, randomized, double-blinded trial of alendronate (10 mg/day orally) (n = 24) compared with placebo (n =(More)
BACKGROUND Osteoporosis diminishes the quality of life in adults with cystic fibrosis (CF). Vitamin D deficiency resulting from malabsorption may be a factor in the etiology of low bone mineral density (BMD) in patients with CF. OBJECTIVE Absorption of oral ergocalciferol (vitamin D2) and the consequent response of 25-hydroxyvitamin D in 10 adults with CF(More)
To examine whether alterations in parathyroid adenylate cyclase might be associated with glandular hyperfunction, we compared enzyme activity in membranes from 7 normal glands with activity from 18 abnormal and 5 noninvolved glands from patients with primary hyperparathyroidism. Compared with the normal glands, the specific enzyme activity after full(More)
Low bone density, fractures, and kyphosis complicate the lives of adults with cystic fibrosis (CF), and inflammatory cytokines (interleukin [IL]-1beta, IL-6, and tumor necrosis factor [TNF]-alpha) that may alter bone metabolism have been previously found to be increased in the lungs and serum of CF patients. The objective of this prospective study was to(More)