Calcium kinetics are altered in clinically stable girls with cystic fibrosis

The role of NMT induction on odontogenic proliferation and differentiation of dental pulp stem cells

This study was conducted to investigate the odontogenic proliferation and differentiation of dental pulp stem cells (DPSCs) after induction by nanoparticle mineral trioxide (NMT). DPSCs were isolated from permanent teeth and placed in tubes containing Dulbecco's modified Eagle's medium, followed by immunocytochemistry analysis. The viability of DPSCs exposed to NMT was measured using MTT assay with trypan blue dye exclusion. Alkaline phosphatase (ALP) activity was evaluated using ALP colorimetric reactions by reacting NMT supernatants with fluorescent-specific ALP substrates. The concentration of osteocalcin was determined using an instant human osteocalcin enzyme-linked immunosorbent assay (ELISA) kit. A human dentin sialophosphoprotein (DSPP) ELISA kit coated with anti-human DSPP antibody was employed to measure DSPP levels. There was a significant difference between ALP activity after exposing the cells to NMT and trioxide mineral aggregate on days 3, 7, and 21. Osteocalcin activity showed a significant difference on days 3, 7, 14, and 21. There was a significant difference in DSPP levels on days 7 and 21. DPSCs exposed to NMT and to trioxide mineral aggregate showed extracellular matrix formation on day 7 and 14, respectively. Furthermore, NMT may effectively increase the proliferation and differentiation of DPSCs as well as their maturation toward odontoblasts.

Using stable isotope tracers to study bone metabolism in children

Skeletal mineralization is initiated in utero and continues throughout childhood and adolescence. During these key periods of the life cycle, calcium retention must increase significantly to provide sufficient mineral for bone deposition and skeletal growth. Stable calcium isotopes have served as a fundamental tool to non-invasively characterize the dynamic changes in calcium physiology that occur from infancy through adolescence. These approaches have helped define the dynamics of calcium absorption and utilization in healthy children and in children with chronic diseases. As data in this area have accumulated, new areas of emphasis are beginning to characterize the determinants of variability in mineral retention, the genetic determinants of bone turnover and calcium flux and the impact of the gut microbiome on whole body and niche specific calcium dynamics. Advances in these areas will help define calcium utilization in paediatric populations and provide information that may be useful in maximizing bone acquisition across this critical phase of the life cycle.

Inflammatory Bowel Disease: Effects on Bone and Mechanisms

Inflammatory bowel disease (IBD) is associated with decreased bone mass and alterations in bone geometry from the time of diagnosis, before anti-inflammatory therapy is instituted. Deficits in bone mass can persist despite absence of symptoms of active IBD. The effects of IBD on the skeleton are complex. Protein-calorie malnutrition, inactivity, hypogonadism, deficits in calcium intake and vitamin D consumption and synthesis, stunted growth in children, decreased skeletal muscle mass, and inflammation all likely play a role. Preliminary studies suggest that the dysbiotic intestinal microbial flora present in IBD may also affect bone at a distance. Several mechanisms are possible. T cells activated by the gut microbiota may serve as "inflammatory shuttles" between the intestine and bone. Microbe-associated molecular patterns leaked into the circulation in IBD may activate immune responses in the bone marrow by immune cells and by osteocytes, osteoblasts, and osteoclasts that lead to decreased bone formation and increased resorption. Finally, intestinal microbial metabolites such as H₂S may also affect bone cell function. Uncovering these mechanisms will enable the design of microbial cocktails to help restore bone mass in patients with IBD.

Lactose malabsorption is a risk factor for decreased bone mineral density in pancreatic insufficient cystic fibrosis patients

As decreased bone mineral density (BMD) is a common problem in cystic fibrosis (CF) and milk products may have pivotal dietary role affecting BMD, we aimed to assess the potential influence of adult-type hypolactasia (ATH) and lactose malabsorption (LM) on BMD in adolescent and young adult patients. In 95 CF pancreatic-insufficient patients aged 10-25 years (without liver cirrhosis, steatosis and cholestasis, diabetes mellitus, systemic glucocorticoid therapy), lumbar BMD, the nutritional status, pulmonary function, vitamin D3 concentration, calcium intake and single-nucleotide polymorphism upstream of the lactase gene were assessed. In subjects with the -13910 C/C genotype predisposing to ATH, the presence of LM was determined with the use of a hydrogen-methane breath test (BT). BMD and calcium intake were significantly lower in patients with the C/C genotype (P<0.028 and P<0.043, respectively). The abnormal BMD was stated more frequently in patients with the C/C genotype (P<0.042) and with LM (P<0.007). BMD, daily calcium intake and serum vitamin D concentration were significantly lower in LM subjects than in the other patients (P<0.037, P<0.000004 and P<0.0038, respectively). In logistic regression analysis, the relationship between examined parameters and BMD, was found to be statistically significant (P<0.001). However, only standardized body weight and LM were documented to influence BMD (P<0.025 and P<0.044, respectively). In conclusion, LM seems to be an independent risk factor for decreased BMD in CF patients.

A roadmap to the brittle bones of cystic fibrosis

Cystic fibrosis (CF) is an autosomal recessive disorder which despite advances in medical care continues to be a life-limiting and often fatal disease. With increase in life expectancy of the CF population, bone disease has emerged as a common complication. Unlike the osteoporosis seen in postmenopausal population, bone disease in CF begins at a young age and is associated with significant morbidity due to fractures, kyphosis, increased pain, and decreased lung function. The maintenance of bone health is essential for the CF population during their lives to prevent pain and fractures but also as they approach lung transplantation since severe bone disease can lead to exclusion from lung transplantation. Early recognition, prevention, and treatment are key to maintaining optimal bone health in CF patients and often require a multidisciplinary approach. This article will review the pathophysiology, current clinical practice guidelines, and potential future therapies for treating CF-related bone disease.

'Old' bones in young bodies: the tale of cystic fibrosis

PURPOSE OF REVIEW

Cystic fibrosis (CF) is the most common genetic disease within the white population and leads to premature respiratory failure. Approximately, 60 000 individuals are currently living with CF in North America and Europe, almost half of whom are adults.

RECENT FINDINGS

Dozens of studies across the globe indicate that CF adults have low bone density and increased rates of fractures. This genesis of the problem appears to be in late childhood to adolescence.

SUMMARY

Prevention and treatment of CF-related bone disease must address the myriad risk factors (decreased absorption of fat-soluble vitamins due to pancreatic insufficiency, altered sex hormone production, chronic lung infection with increased serum levels of proinflammatory, bone-active cytokines, malnutrition and low body weight, physical inactivity and glucocorticoid therapy) for poor bone health. This review will address the pathogenesis, diagnosis and treatment of bone disease in CF. It will also discuss best practice guidelines for optimizing bone health in patients with CF.

Relation of bone mineral density with clinical and laboratory parameters in pre-pubertal children with cystic fibrosis

To study bone mineral density (BMD) of pre-pubertal cystic fibrosis (CF) children, and its relation with clinical and laboratory parameters, we enrolled 16 CF (8 girls) (4-8 years), and 16 control children (8 girls) (4-8 years). After anthropometric measurements, BMD, serum calcium, phosphorus, total alkaline phosphatase (ALP), 25-hydroxy vitamin D (25-OHD), parathyroid hormone, osteocalcin, tumor necrosis factor (TNF)-alpha, soluble TNF-alpha receptor 2 (sTNFR2), and soluble IL-2 receptor (sIL-2R) levels, and urinary calcium and hydroxyproline excretions were assessed. Disease severity of CF patients was determined with Shwachman-Kulczycki clinical and Brasfield radiological scoring systems.The mean Shwachman-Kulczycki and Brasfield scores of CF patients were indicating well-controlled disease. The anthropometric measurements, mean BMD values, and serum calcium, phosphorus and parathyroid hormone levels were within normal range and similar in both groups. Serum osteocalcin levels were lower, and ALP and 25-OHD levels were higher in CF. Although 24-hr urinary calcium excretions was higher in CF patients, hydroxyproline excretions were similar in both groups. There was no difference between two groups for the serum levels of sIL-2R, TNF-alpha and sTNFR2. Children with low vertebral z-scores had higher serum sIL-2R levels in both groups, but the same relation could not be shown for TNF-alpha and sTNFR2.We may speculate that younger, healthier and well-nourished patients with CF may have normal BMD, but the bone disease develop as patients get older because of the other contributing factors. Future well-designed longitudinal studies with large cohorts might show a relation with BMD and cytokines in CF.

Percent true calcium absorption, mineral metabolism, and bone mineralization in children with cystic fibrosis: effect of supplementation with vitamin D and calcium

OBJECTIVE

To assess whether percent true calcium absorption (alpha) is normal in children with cystic fibrosis (CF) and to assess whether supplementation with 2,000 IU vitamin D(3), 1 g calcium, or both will alter alpha, mineral metabolism, and/or bone mass in children with CF.

STUDY DESIGN

Fifteen children ages 7-13 were randomly assigned to one of four different orders to receive all four 6-month treatments including placebos. Change in 25-hydroxyvitamin D (25-OHD), 1,25-dihydroxyvitamin D (1,25(OH)(2)D), PTH, bone turnover markers, and minerals after 6 months, and bone mineral content (Hologic 1000W) after 9 months was measured. alpha was measured by a dual stable isotope method using (48)Ca intravenously and (46)Ca orally and measuring (48)Ca, (46)Ca, and (42)Ca in a 24-hr urine using High Resolution Inductively Coupled Mass Spectroscopy (HR-ICP-MS). Analysis used Wilcoxon Sign Ranks.

RESULTS

alpha was in the normal range and did not differ by treatment (P 35 +/- 10%, Ca 38 +/- 23%, D 36 +/- 11%, D + Ca 46 +/- 21%). One gram calcium did not increase serum or urine calcium. Two thousand IU D(3) did not increase 25-OHD or change 1,25(OH)(2)D. Serum and urine minerals, markers of bone turnover and bone mineral gains did not differ by treatment.

CONCLUSIONS

alpha is normal in children with CF. One gram calcium and/or 2,000 IU D(3) does not change alpha or increase 25-OHD, serum calcium, or mineralization. Longer trials of a significantly higher dose of vitamin D(3) shown to increase serum 25-OHD are needed to assess effects on mineral metabolism and bone mass accrual. However, study of therapeutic options other than calcium and vitamin D should be encouraged.

Chronic pediatric inflammatory diseases: effects on bone

In children, chronic inflammatory diseases present a significant challenge to long-term skeletal health. These conditions are often associated with poor appetite and suboptimal overall nutrition, altered nutrient utilization, delayed puberty, inactivity, and reduced muscle mass, all of which can alter bone metabolism. In addition, bone cell activity is susceptible to the effects of the immune response that characterizes these diseases. Moreover, drugs used to treat these maladies, notably glucocorticoids, may have negative effects on bone formation and on linear growth in developing children. As a result, predicted peak bone mass may not be achieved, and fracture risk may be increased in the short term or in the future. Studies using primarily dual energy X-ray absorptiometry have documented that deficits in bone mass are common in these diseases. However, there are wide variations in the prevalence of low bone mass, largely due to differences in the characteristics of each study population. Recent studies provide insight into the pathogenesis of decreased bone mass in these conditions. In this paper we will provide an overview of the effects of chronic inflammatory conditions on bone mass in children. We will also present relevant data from adult patients, when pediatric data are scant or not available.

Vitamin D status in gastrointestinal and liver disease

PURPOSE OF REVIEW

The purpose of this review is to report on the vitamin D status and its relationship with bone health in individuals with gastrointestinal and liver disorders. In addition, recommendations regarding replacement and maintenance of optimal vitamin D stores, as well as the state of knowledge regarding its effect on the disease through its actions on the immune system, will be reviewed.

RECENT FINDINGS

The scientific community has revised upward the serum levels of vitamin D considered optimal, and doses of vitamin D much larger than those currently recommended may be needed to maintain these levels, especially in individuals with gastrointestinal and liver disorders. The relationship between vitamin D and bone health in this population is controversial. The role of vitamin D in the regulation of the immune system continues to be elucidated.

SUMMARY

Hypovitaminosis D is prevalent among individuals with gastrointestinal and liver disease. Although replacement and supplementation guidelines have not been well defined, practitioners should aim for a serum 25-hydroxyvitamin D level of at least 32 ng/ml. The contribution of vitamin D to the bone health of these individuals and its role in altering disease course through its actions on the immune system remain to be elucidated.

Update on maintaining bone health in cystic fibrosis

PURPOSE OF REVIEW

The high prevalence of decreased bone density in adults with cystic fibrosis is now well recognized, and guidelines for screening and treatment of cystic fibrosis-related bone disease have recently been published. This review summarizes the current best practices for optimizing bone health in cystic fibrosis and highlight recent findings that provide insight into the etiology of cystic fibrosis-related bone disease.

RECENT FINDINGS

Recent research suggests that cystic fibrosis-related bone disease actually starts during childhood, when individuals with cystic fibrosis fail to demonstrate normal bone calcium accretion. The failure to reach peak bone mass is made worse by increased osteoclast activity and bone resorption. This combination results in decreased bone density and an increased risk of fracture. Recent clinical studies suggest that multiple contributing factors need to be addressed in cystic fibrosis to optimize bone health: malnutrition, vitamin and mineral malabsorption, recurrent infections, inadequate sex hormones, and lack of exercise. Oral bisphosphonates have been demonstrated to be effective in cystic fibrosis and should be used when osteoporosis or progressive osteopenia is present.

SUMMARY

Research suggests cystic fibrosis-related bone disease actually begins during childhood, and guidelines now exist to aid in identifying and treating those with decreased bone density.

Calcium acquisition rates do not support age-appropriate gains in total body bone mineral content in prepuberty and late puberty in girls with cystic fibrosis

Few longitudinal data are available characterizing bone development in adolescents with cystic fibrosis (CF) although this is a critical time for bone mineralization. Dual energy X-ray absorptiometry (DXA) scans were obtained at 1- to 4-year intervals in 18 prepubertal and pubertal girls (age 7-18 years) with CF to determine calcium (Ca) accretion rates and changes (Delta) in total body bone mineral content (TBBMC) and lumbar spine bone mineral density (LS BMD) Z-scores. Daily Ca acquisition rates were calculated assuming TBBMC was composed of 32.2% Ca. Bone Ca accretion averaged 82 mg/day (2.05 mmol/day) [(range:-38 to +197 mg/day (-0.95 to 4.9 mmol/day)] on approximately 1,200 mg/day (30 mmol/day) Ca intakes. Estimated mean peak Ca accretion was 160 mg/day (4 mmol/day) at age 13 years; losses of bone Ca occurred in late puberty. Gains in insulin-like growth factor 1 (IGF-1) predicted Ca accretion (p<0.06). Body mass index (BMI) Z-score predicted LS BMD and TBBMC Z-score cross-sectionally but did not predict DeltaTBBMC Z-score. Changes in TBBMC Z-score paralleled Ca accretion rates with age. Bone Ca accretion in girls with CF fell below rates in healthy girls during prepuberty and late puberty despite Ca intakes approaching recommendations. IGF-1 and BMI Z-scores may identify children with CF at risk of compromised bone accretion, and more data are required to elucidate roles of lung function and glucocorticoid use in compromised bone health.