Progression of vascular calcifications is associated with greater bone loss and increased bone fractures

In this prospective study, we found a positive relationship between the prevalence of aortic calcifications and age. Aortic calcifications at baseline were positively associated with osteoporotic fractures. In addition, progression of aortic calcifications was also positively associated with the rate of decline in BMD at lumbar spine.

INTRODUCTION

The aim of this study was to analyze the relationship between the progression of abdominal aortic calcification and osteoporosis in a Spanish cohort of men and women older than 50.

METHODS

Men and women (n=624) aged 50 and over underwent two lateral X-rays of thoracic and lumbar spine and a dual X-ray absorptiometry (DXA) study at lumbar spine and hip, and were followed during 4 years. Abdominal aortic calcifications were classified as absent, mild-moderate and severe.

RESULTS

There was a positive relationship between the prevalence of aortic calcifications and age. In both sexes, prevalent severe aortic calcifications were positively associated with prevalent osteoporotic fractures [odds ratio (OR)=1.93 (1.02-3.65)]. The association was stronger when only vertebral fracture was considered [OR=2.45 (1.23-4.87)]. In addition, progression of aortic calcifications showed a positive association with the rate of decline in bone mineral density (BMD) at lumbar spine.

CONCLUSIONS

Aortic calcifications at baseline were positively associated with osteoporotic fractures. The progression of aortic calcifications was also positively associated with the rate of decline in BMD at lumbar spine.

The effect of vertebral fracture as a risk factor for osteoporotic fracture and mortality in a Spanish population

There is little data concerning the morbidity, mortality, and epidemiology of vertebral fracture. The aim of this study was to evaluate the effect of prevalent and incident vertebral fractures as risk factors for further osteoporotic fractures and mortality. The study was performed on a cohort of 316 women and 308 men older than 50 belonging to the EVOS study, randomly selected from our city register. At the beginning of the study and 4 years later, lateral dorsal and lumbar X-rays were performed. In addition, evaluation of the incidence of osteoporotic nonvertebral fractures was performed throughout 8 years. The incidence of all osteoporotic fractures was higher in women than in men (two-fold increase in vertebral fracture incidence and five-fold increase in Colles' and femur incidence). Vertebral fracture was a strong risk factor for a new vertebral fracture [RR=4.7 (1.8-11.9)], hip fracture [RR=6.7 (2.0-22.7)] and Colles' fracture [RR=3.0 (1.1-7.8)]. Prevalent and incident vertebral fractures were associated with a higher risk of having a hip fracture [RR=10.0 (2.0-50.2)] and Colles' fracture [RR=5.5 (1.3-23.4)]. In addition, in women, the vertebral fracture was associated with a higher mortality. By contrast, no association was found in men. These results demonstrate the association between a previous vertebral fracture with increments in the incidence of osteoporotic fractures of any type. In addition, we found a significantly higher mortality rate in women having vertebral fractures. These findings support the necessity of preventing the occurrence of vertebral fractures to limit their strong negative impact on mortality.

The position of strontium ranelate in today's management of osteoporosis

Osteoporosis accounts for about 3 % of total European health-care spending. The low proportion of costs for the pharmacological prevention of osteoporotic fracture means that it is highly cost saving, especially in patient with severe osteoporosis or patients who cannot take certain osteoporosis medications due to issues of contraindications or tolerability. Following recent regulatory changes, strontium ranelate is now indicated in patients with severe osteoporosis for whom treatment with other osteoporosis treatments is not possible, and without contraindications including uncontrolled hypertension, established, current or past history of ischaemic heart disease, peripheral arterial disease, and/or cerebrovascular disease. We review here today's evidence for the safety and efficacy of strontium ranelate. The efficacy of strontium ranelate in patients complying with the new prescribing information (i.e. severe osteoporosis without contraindications) has been explored in a multivariate analysis of clinical trial data, which concluded that the antifracture efficacy of strontium ranelate is maintained in patients with severe osteoporosis without contraindications and also demonstrated how the new target population mitigates risk. Strontium ranelate is therefore an important alternative in today's management of osteoporosis, with a positive benefit-risk balance, provided that the revised indication and contraindications are followed and cardiovascular risk is monitored. The bone community should be reassured that there remain viable alternatives in patients in whom treatment with other agents is not possible and protection against the debilitating effects of fracture is still feasible in patients with severe osteoporosis.

Reference values for trace and ultratrace elements in human serum determined by double-focusing ICP-MS

Reference values for trace and ultratrace elements concentrations in healthy human serum, measured by double-focusing inductively coupled plasma-mass spectrometry (ICP-MS), are presented. Blood donors from Asturias (Spain) were selected as the reference population (n=59). Blood samples were collected, after donation, taking the necessary precautions to avoid contamination. All subjects analyzed had normal renal function and nutritional status, as shown from their creatinine and albumin levels. A total number of 14 elements (Al, Ca, Cr, Mn, Fe, Co, Cu, Zn, Rb, Sr, Mo, Cd, Pb, and U) were monitored almost simultaneously. Serum samples were diluted 1+4 with ultrapure water and matrix interferences were corrected using Sc, Ga, Y, and Tl as internal standards. Fe, Cu, and Zn were also determined by isotope dilution analysis (IDA). Reference trace element concentrations intervals observed containing 95% of the reference distribution after excluding outliers are presented. Fourteen serum samples from hemodialysis patients were also analyzed for comparison. High levels of Al, Cr, Sr, Mo, Mn, Pb, U, Co, and Cu and low levels of Fe, Zn, and Rb were found in the serum samples from hemodialysis patients compared to the corresponding reference values observed in this work.

Low calcidiol levels and risk of progression of aortic calcification

In this observational study, we found a positive relationship between low calcidiol levels and the risk of aortic calcification progression. A 10-ng/mL increase of calcidiol was associated with a decrease in the risk of progression by 44%. This figure was higher than that observed if we increased age by 10 years.

INTRODUCTION

The aim of this study was to investigate the relationship between serum calcidiol levels and the onset and progression of aortic calcifications in a community-based sample of ambulatory subjects.

METHODS

Three hundred two men and women aged 50 and over underwent two lateral X-rays and were followed up for 4 years. Abdominal aortic calcifications were classified as absent, mild-moderate, and severe. The biochemical measurements of serum calcium, phosphorus, parathyroid hormone, total alkaline phosphatase, tartrate-resistant acid phosphatase, creatinine, calcidiol, calcitriol, and osteocalcin were determined. Subjects who had received anti-osteoporotic treatments were excluded from the analysis.

RESULTS

Subjects with progression of aortic calcifications had significantly lower serum calcidiol levels than those without progression. In the multivariate analysis, using the agreed upon serum levels for calcidiol (>30 ng/mL) as the reference, those subjects with calcidiol levels between 10 and 20 ng/mL showed a higher risk of progression of aortic calcification (odds ratio (OR) = 3.95; 95% confidence interval (CI) = 1.16 to 13.40). An even higher OR was observed in subjects with calcidiol values <10 ng/mL (OR = 4.10; 95% CI = 1.12 to 14.99). In addition, an increase by 1 ng/mL in osteocalcin levels was associated with a 17% reduction of the risk of aortic calcification progression.

CONCLUSIONS

An increase by 10 ng/mL of calcidiol was associated with a decrease in the risk of aortic calcifications progression by 44%. This figure was even higher than that observed if we increased age by 10 years. Levels of calcidiol higher than 30 ng/mL seem to be desirable to reduce the progression of aortic calcification and to maintain bone turnover.

Aluminum-induced osteogenesis in osteopenic rats with normal renal function

Previous studies have shown a different effect of aluminum (Al) on bone metabolism in animals with chronic renal failure and conversely, positive osteogenic effects in animals with normal renal function. The aim of this study was to evaluate the effect of aluminum on bone metabolism in osteopenic rats. We studied male Wistar rats with severe osteopenia induced by adding NH4Cl (2%) to the drinking water over a 6-month period. The rats were divided into two groups and followed for 4 months. The Aluminum group (G1) received AlC13 intraperitoneally (10 mg/kg/5 days/week) (n = 8); the Control group (G2) did not receive any treatment after stopping the administration of NH4Cl (n = 5). In all animals we measured biochemical markers (serum Ca, P, Cr, Al, osteocalcin, hydroxyproline) as well as bone mineral density and bone histomorphometry (BV/TV, CTh, ObS/BS, OTh, and NOc/TV). Bone aluminum content, measured by atomic absorption spectrometry, was 101.6 +/- 13 microg/g in the Al overloaded group and 1.31 +/- 0.14 in controls. Bone mineral density, evaluated by dual X-ray absorptiometry (DXA) at the proximal extremity of the tibia was significantly higher in G1 (0.292 +/- 0.01 g/cm2 versus 0. 267 +/- 0.02 g/cm2). No significant differences were found between the biochemical markers. In the histomorphometric parameters we observed significant differences in G1 compared with G2: an increase in BV/TV (18.59 +/- 5.6 versus 7.69 +/- 3.08%) and in CTh (0.52 +/- 0.06 versus 0.36 +/- 0.07 mm) with a moderate increment of the osteoid thickness (14.05 +/- 4.72 versus 5.25 +/- 0.9 microm) (P < 0. 05). Changes in others parameters and the relationship between biochemical parameters of bone remodeling, Al, and histology were analyzed. These findings indicate that in rats with normal renal function, Al is able to induce bone formation even when osteopenia is present.

Prevalence of osteoporosis in men and determinants of changes in bone mass in a non-selected Spanish population

Osteoporotic studies conducted exclusively in men have been limited by the discrepancies in defining densitometric osteoporosis and, also, because osteoporosis has traditionally been associated only with women. The aims of this study were to describe the prevalence of low bone mineral density (BMD) and osteoporotic fractures as well as the rate of bone loss. The analysis of some risk factors for accelerated bone loss was also evaluated. Men aged 50 years and over, randomly selected from the Oviedo municipal register (n = 308), completed a questionnaire regarding risk factors related to osteoporosis; they underwent two lateral radiographs of the dorsal and lumbar spine and a dual X-ray absorptiometry (DXA) study at the lumbar spine and hip. In the 4th year of the follow-up period, participants were invited to undergo repeats of the same tests that had been carried out in the initial study. The prevalence of densitometric osteoporosis in men older than 50 years, standardized by age, was 8.1% with regard to at least one of the four studied bone areas, with a slight increase with age. The prevalence of osteoporotic fracture, standardized by age, was 24.4%, with a marked increase with age. Osteoporotic prevalent fracture was independently associated only with the rate of change in lumbar spine BMD. From all the osteoporotic risk factors analyzed, only low milk consumption and regular smoking were independently associated with loss of bone mass. In summary, prevalent osteoporotic fracture was independently associated with the rate of change in the lumbar spine BMD but not in the other segments studied. Avoiding smoking and ensuring an adequate milk intake might prevent the loss of bone mass in men.

Aluminum exposure in chronic renal failure in iberoamerica at the end of the 1990s: overview and perspectives

Epidemic aluminum neurotoxicity has virtually disappeared in the dialysis population; however, sporadic toxic effects caused by contamination of water with aluminum are still reported. In this review, the current situation in Iberoamerica is analyzed. Exposure to aluminum through dialysate shows considerable geographical differences even within the same country, including seasonal variability. Sometimes the tap water showed very high aluminum content that does not permit the water treatment system to efficiently remove all the aluminum, forcing the use of water treatment systems with a double reverse-osmosis filter on line. The use of adequate water treatment systems and a correct control policy has improved the quality of the dialysate, minimizing the aluminum exposure. However, an additional problem in Iberoamerica is the difficulty to obtain aluminum-free concentrates for the preparation of the final dialysis solution. Aluminum still seems to be implicated in a great percentage of symptomatic low-bone remodeling lesions in South America compared with Europe, demonstrating that exposure to aluminum through dialysate is still a cause of concern in some areas of the world.

A novel mutation in the calcium-sensing receptor responsible for autosomal dominant hypocalcemia in a family with two uncommon parathyroid hormone polymorphisms

A novel missense activating mutation in the extracellular calcium-sensing receptor (CaSR) is reported in this work. It was identified in three related subjects with the phenotypic features of autosomal dominant hypocalcemia (ADH). The proband, a 27-year-old woman, diagnosed as having hypoparathyroidism at 7 years of age and a history of seizures, showed the highest penetrance of the mutation. The remaining two affected members presented asymptomatic chronic hypocalcemia despite severe hypoparathyroidism associated with high levels of serum phosphate and calcium urinary excretion. The missense mutation (Glu(604)Lys) affected an amino acid residue in the C terminus of the cysteine-rich domain of the extracellular amino-terminal domain, which seems to be required for the coupling of ligand binding to the activation of intracellular signaling pathways. This genetic change cosegregated with hypocalcemia in all the individuals where the mutation was found. As parathyroid hormone (PTH) secretion is the regulatory target of the CaSR, polymorphism analysis of the PTH gene was carried out. PTH polymorphisms were analyzed in the kindred studied. Affected members for the Glu(604)Lys CaSR mutation which also carried the uncommon PTH alleles showed higher penetrance of the mutation, with more severe autosomal dominant hypocalcemia. These results suggested that the PTH gene could act as a modifier locus of ADH, affecting the penetrance of the activating CaSR mutation described.

Reconsidering the importance of long-term low-level aluminum exposure in renal failure patients

Aluminum toxicity is widely considered a problem of the past. However, low-level aluminum exposure and low but abnormal body burdens of aluminum are common. Aluminon, the routinely used histochemical stain for aluminum in bone, has a low sensitivity. The role of aluminum in renal osteodystrophy needs to be reassessed using more sensitive techniques. Low-level aluminum exposure also may resu in subtle neurological dysfunction, another area that needs further investigation.

Binding of aluminium to plasma proteins: comparative effect of desferrioxamine and deferiprone (L1)

Ultramicrofiltration techniques were used to study both the binding of aluminium to high molecular weight proteins in the presence of different concentrations of desferrioxamine and deferiprone (L1) and the kinetics of aluminium release from human serum proteins. Human serum from healthy volunteers was used in all studies. The serum was spiked with aluminium (100 micrograms/l) and different concentrations of chelators. Ultramicrofiltration was performed with Amicon YMT membranes which had a nominal cut-off of 30,000 Da. Aluminium was measured by graphite furnace atomic absorption spectrometry in total serum and ultrafiltered fluid. Deferiprone shows a higher capability to displace aluminium from serum proteins (80%) than desferrioxamine (60%) at equivalent concentrations of the chelators. The kinetics of the release were also faster for deferiprone, taking 20 min to achieve its maximum effect, whereas, desferrioxamine achieved only 80% of its maximum effect after 2 h. Thus, deferiprone could be an attractive alternative to desferrioxamine, as an aluminium chelator agent.

Association of matrix Gla protein gene functional polymorphisms with loss of bone mineral density and progression of aortic calcification

Two matrix Gla protein (MGP) polymorphisms were associated with progression of aortic calcification and femoral neck bone loss in men. All these findings were also functionally corroborated in two vascular and bone in vitro systems indicating that MGP genetic variations can be partly responsible of higher risk of bone loss and vascular calcification.

INTRODUCTION

MGP plays an important role in bone and vascular mineralization as confirmed by MGP-deficient murine model. We therefore aimed to find a genetic association among -138T>C, -7G>A, and Thr83Ala MGP single-nucleotide polymorphisms (SNPs), bone loss, and progression of aortic calcification in a randomly selected general population of 296 individuals who participated in the European Vertebral Osteoporosis Study.

METHODS

To evaluate the rate of change in bone mineral density (BMD) and the progression of aortic calcification, dual X-ray absorptiometry and lateral spine X-rays were performed at baseline and after 4 years of follow-up. Genotyping for the three polymorphisms was carried out using polymerase chain reaction and restriction fragment length analysis. In addition, functional studies of MGP-7G>A and Thr83Ala SNPs were performed on transiently transfected osteoblast-like UMR-106 and vascular smooth muscle A7r5 cells.

RESULTS

The proportion of men who had lost BMD in the femoral neck was higher among homozygous -7AA and 83Ala-Ala (p = 0.039 and p = 0.009, respectively), and also featured a higher risk of progression of aortic calcifications (OR = 5.6, 95% CI = 1.2-27.8 and OR = 6.8, 95% CI = 1.4-32.3, respectively). No effect was observed in women. The MGP-7A allele produced a reduction in luciferase activity compared to MGP-7G: 47% less in vascular cells and 34% less in bone cells (p = 0.001 and 0.012, respectively). In vascular cells under calcifying conditions, the MGP 83Thr allele showed a slightly higher, although not significant, inhibition than the MGP 83 Ala allele in calcium content suggesting functional differences between both variants.

CONCLUSION

These results suggest that MGP genetic variations could predict a higher risk of bone loss and progression of vascular calcification in men.

Management of secondary hyperparathyroidism: the gap between diagnosis and treatment. The Renal Osteodystrophy Multicenter Enquiry

In mild secondary hyperparathyroidism, small daily doses of oral calcitriol represent the physiological form of replacement of this hormone, but in moderate or severe cases, higher doses of calcitriol are needed to suppress parathyroid gland overactivity. Unfortunately, in chronic renal failure, these 2 different forms of calcitriol prescription are not always adequately selected. This review will focus on the current use of calcitriol in renal failure. It includes data from a recent multicenter trial carried out in Spain in which data was gathered from dialysis patients. This trial was designed to determine the current approach to the prevention, diagnosis, and treatment of renal osteodystrophy, with a special emphasis on the gap found between diagnosis and treatment of secondary hyperparathyroidism. Our main goal should be to achieve an adequate and early management of secondary hyperparathyroidism to decrease the number of patients suffering from irreversible enlargement of the parathyroid glands.

Clinical and subclinical cardiovascular disease in female SLE patients: Interplay between body mass index and bone mineral density

BACKGROUND AND AIMS

Since accelerated atherosclerosis has been reported in systemic lupus erythematosus (SLE), predictive biomarkers of cardiovascular disease (CVD) are needed. Among non-traditional risk factors, bone mineral density (BMD) has been related to CVD. However, its role in SLE remains controversial. This study aims to analyze the associations of subclinical atherosclerosis with traditional and non-traditional CV risk factors.

METHODS AND RESULTS

In a cross-sectional study, atherosclerosis burden was compared between 112 female SLE patients and 31 controls. Plaque number and carotid intima-media wall thickness (cIMT) were assessed by ultrasonography. In a retrospective study, BMD determinations obtained 5-years before the ultrasonography assessment were analyzed in a subgroup of 62 patients. Plaque frequency was increased in SLE, even in patients without CV events or carotid wall thickening. cIMT was increased in patients with CVD, positively correlated with body mass index (BMI). Interestingly, a paradoxical effect of BMI on carotid parameters was observed. Whereas underweight patients (BMI < 20) showed increased prevalence of carotid plaques with low cIMT, those with BMI > 30 showed higher cIMT and plaque burden. Overweight patients (25 < BMI<30) exhibited both elevated cIMT and plaque number. BMI was an independent predictor of BMD. In our retrospective study, patients with either clinical or subclinical CVD exhibited lower BMD levels than their CV-free counterparts. A low lumbar spine BMD independently predicted CVD development after adjusting for confounders.

CONCLUSION

SLE was associated with a higher subclinical atherosclerosis burden, a bimodal effect being observed for BMI. Decreased BMD can be a CV risk biomarker in SLE.

Hormonal replacement therapy in an animal model with chronic renal failure and ovariectomy: biochemical and densitometric study

BACKGROUND

In spite of estrogen replacement therapy being extensively used in clinical and experimental studies without renal impairment, there are no long-term studies concerning estrogen replacement in chronic renal failure.

METHODS

In this experimental study, six groups of nephrectomized and ovariectomized animals were treated with different doses of 17beta-estradiol, alone or in combination with calcitriol, to evaluate the effect of these treatments on bone metabolism.

RESULTS

Biochemical results showed that estrogen alone did not have any effect neither on calcium nor on PTH serum levels. By contrast, in the groups treated with calcitriol, the levels of serum calcium were significantly higher, and the levels of iPTH were significantly lower than those observed in the control group. Animals receiving the combined treatment with estrogen and calcitriol showed the greater gain in uterus weight and a better bone mineral density at the lumbar site and the proximal and distal tibia sites.

CONCLUSION

The combination of estrogen and calcitriol is the most effective therapy to prevent bone mass loss in animals with chronic renal failure and estrogen deprivation.

Use of ultrafiltration and chromatography to assess aluminum speciation in serum after deferoxamine administration

Deferoxamine effectively chelates aluminum by forming aluminoxamine, a low-molecular-weight compound removable by dialysis. However, aluminum-bound species other than aluminoxamine might be present in serum after the administration of deferoxamine. To study aluminum speciation after the administration of deferoxamine, high-performance liquid chromatography (HPLC) and ultrafiltration techniques were used. Samples of serum were obtained from six dialysis patients 44 hours after the administration of a single dose of deferoxamine. HPLC and ultrafiltration studies were performed. In the HPLC studies, samples underwent ultrafiltration, the filtrate was injected into the chromatographic system, and detection was performed by UV light and atomic absorption spectrometry. Unknown species of aluminum other than aluminoxamine were found in the early elution fractions. In the ultrafiltration studies, the same samples of serum from the six patients underwent ultrafiltration using membranes with different molecular-weight cutoff values from 1 to 30 kd. The percentages of aluminum found by ultrafiltration using membranes with cutoff values of 5, 10, and 30 kd were greater (64.4% +/- 2.5%, 63.5% +/- 3.7%, and 65.6% +/- 4.3%, respectively) than the percentages obtained with membranes with a 1-kd cutoff value (38.7%), suggesting that the unknown species of aluminum have a molecular weight between 1 and 5 kd. The unknown species of aluminum cannot be aluminoxamine because they behaved in a different way with HPLC.

Bone aluminum uptake in uremic rats receiving intraperitoneal iron

To assess the effect of concomitant iron and aluminum loads on bone aluminum accumulation and on the response to the deferoxamine test in rats with the same aluminum surcharge, Wistar rats with chronic renal failure were divided into three groups: iron-overloaded rats (N = 6) (intraperitoneal iron); iron-depleted rats (N = 6) (blood withdrawal two to three times per week); control rats (N = 4) (no manipulation). All groups received intraperitoneal aluminum simultaneously. After 6 wk, a deferoxamine challenge test was performed. Thereafter, bone aluminum and iron were measured. The iron-overloaded rats showed higher bone iron content (iron overloaded: 147.7+/-55.4 microg/g; iron depleted: 7.9+/-1.0, and controls 13.3+/-9.9 microg/g, p < 0.010) and lower bone aluminum content (iron overloaded: 14.2+/-4.0 microg/g; iron depleted: 70.9+/-35.1 microg/g; controls: 72.7+/-28.3 microg/g p < 0.005). No differences were found between the iron-depleted and control rats. After the deferoxamine infusion, the iron-depleted rats tended to have higher serum aluminum increments (p = NS) and higher urinary aluminum excretion (p < 0.012, p < 0.020) than control rats despite similar amounts of aluminum in bone of the two groups. Aluminum bone accumulation was minor if iron and aluminum loads were given concomitantly. The iron depletion influenced the results of the deferoxamine challenge test in rats with similar bone aluminum burden.

Low percentage of aluminoxamine and ferrioxamine in uremic serum after desferrioxamine administration

HPLC was used to study the effectiveness of two different desferrioxamine (DFO) administration strategies (15 mg/kg DFO, 1 h or 44 h before dialysis) on generation of aluminoxamine and ferrioxamine in five hemodialysis patients. The percentage of ultrafilterable aluminum and iron in these patients was also investigated by electrothermal atomic absorption spectrometry. The administration of DFO in both schemes increased the ultrafilterable serum aluminum concentrations from a mean of 17.1 +/- 1.6% to a mean of 75.7 +/- 14.1%. However, 1 h after DFO infusion, only 38.8 +/- 7.7% of the total serum aluminum was bound to DFO; 44 h after DFO infusion, only 15.8 +/- 8.0% was bound. Similar results were obtained for ferrioxamine. These results suggest that the ultrafilterable serum fraction contains aluminum and iron chelated by DFO and by DFO metabolites, which retain similar metal-chelating abilities.