Rickets and soil strontium

Natural High Strontium Mineral Water Might Reduce Liver Protein Synthesis: A Non-Targeted Metabolomics Study in Rats

Strontium-rich mineral water (strontium > 0.20 mg/L) is the second largest type of mineral water on commercial drinking water market. Exposure to high levels of strontium through drinking water or soil may interfere with calcium metabolism and increase the risk of cardiovascular and skeletal diseases, but no in-depth mechanism has been disclosed to date. Data on liver metabolic alterations in rats resulted from drinking natural high strontium mineral water (strontium 26.06 mg/L, SrHW) or tap water (filtered by activated carbon, strontium 0.49 mg/L, TW) for 3 months were obtained and analyzed with non-targeted metabolomics strategy. Compared with rats drinking TW, those drinking SrHW showed a significant change in 36 liver metabolites. Among them, 33 liver metabolites (including 14 amino acids, 6 carbohydrates, 4 short-chain fatty acids, 4 organic acids, 2 phenylpropanoic acids, 1 fatty acid, 1 peptide, and 1 bile acid) were down-regulated, and 3 (hydroxyphenyllactic acid, propionylcarnitine and S-adenosine homocysteine) were up-regulated. Metabolic pathway analysis showed that aminoacyl-tRNA biosynthesis, valine, leucine and isoleucine biosynthesis, and alanine, aspartate and glutamate metabolism are most impacted. Furthermore, the serum prealbumin content also significantly decreased in rats drinking SrHW. Therefore, changes in liver metabolites and serum protein levels suggested that high concentration of strontium in water was associated with decreased liver protein synthesis; changes in liver metabolites suggested that high strontium was associated with decreased lipid levels. In conclusion, high strontium in water may exert a negative effect on protein synthesis, and further study on the dose-response relationship is necessary.

Trace element pollution tracking in the complex multi-aquifer groundwater system of Al-Hassa oasis (Saudi Arabia) using spatial, chemometric and index-based techniques

In a global context, trace element pollution assessment in complex multi-aquifer groundwater systems is important, considering the growing concerns about water resource quality and sustainability worldwide. This research addresses multiple objectives by integrating spatial, chemometric, and indexical study approaches, for assessing trace element pollution in the multi-aquifer groundwater system of the Al-Hassa Oasis, Saudi Arabia. Groundwater sampling and analysis followed standard methods. For this purpose, the research employed internationally recognized protocols for groundwater sampling and analysis, including standardized techniques outlined by regulatory bodies such as the United States Environmental Protection Agency (USEPA) and the World Health Organization (WHO). Average values revealed that Cr (0.041) and Fe (2.312) concentrations surpassed the recommended limits for drinking water quality, posing serious threats to groundwater usability by humans. The trace elemental concentrations were ranked as: Li < Mn < Co < As < Mo < Zn < Al < Ba < Se < V < Ni < Cr < Cu < B < Fe < Sr. Various metal(loid) pollution indices, including degree of contamination, heavy metal evaluation index, heavy metal pollution index, and modified heavy metal index, indicated low levels of groundwater pollution. Similarly, low values of water pollution index and weighted arithmetic water quality index were observed for all groundwater points, signifying excellent groundwater quality for drinking and domestic purposes. Spatial distribution analysis showed diverse groundwater quality across the study area, with the eastern and western parts displaying a less desirable quality, while the northern has the best, making water users in the former more vulnerable to potential pollution effects. Thus, the zonation maps hinted the necessity for groundwater quality enhancement from the western to the northern parts. Chemometric analysis identified both human activities and geogenic factors as contributors to groundwater pollution, with human activities found to have more significant impacts. This research provides the scientific basis and insights for protecting the groundwater system and ensuring efficient water management.

Microelement strontium and human health: comprehensive analysis of the role in inflammation and non-communicable diseases (NCDs)

Strontium (Sr), a trace element with a long history and a significant presence in the Earth's crust, plays a critical yet often overlooked role in various biological processes affecting human health. This comprehensive review explores the multifaceted implications of Sr, especially in the context of non-communicable diseases (NCDs) such as cardiovascular diseases, osteoporosis, hypertension, and diabetes mellitus. Sr is predominantly acquired through diet and water and has shown promise as a clinical marker for calcium absorption studies. It contributes to the mitigation of several NCDs by inhibiting oxidative stress, showcasing antioxidant properties, and suppressing inflammatory cytokines. The review delves deep into the mechanisms through which Sr interacts with human physiology, emphasizing its uptake, metabolism, and potential to prevent chronic conditions. Despite its apparent benefits in managing bone fractures, hypertension, and diabetes, current research on Sr's role in human health is not exhaustive. The review underscores the need for more comprehensive studies to solidify Sr's beneficial associations and address the gaps in understanding Sr intake and its optimal levels for human health.

Global Health Disparities in Childhood Rickets

Nutritional rickets is a global health problem reflecting both historical and contemporary health disparities arising from racial, ethnic, environmental, and geopolitical circumstances. It primarily affects marginalized populations and can contribute to long-term morbidity. Deficits in bone health in childhood may also contribute to osteomalacia/osteoporosis. Solutions require a global public health approach.

Time regularities of strontium concentration in drinking groundwater distant from the sea coast

This paper confirms the regularities of the formation of increased concentrations of strontium (Sr) in fresh groundwater used for drinking water supply, depending on the time they are residen in the carbonate deposits of the aquifer. On average, every thousand years, the Sr concentration increases by 2.1-3.5 mg L-1. In addition, high strontium content is positively correlated with altitude and well depth and negatively correlated with redox conditions in the aquifer. Large relief elevations are associated with the development of marginal moraine deposits from the Last Glacial Period composed predominantly of clay, which contributes to a decrease in water exchange. The high Sr content is associated with the dissolution of significant formations of celestite and strontianite, up to their ore occurrences. For this reason, the saturation indices (SIs) for celestite and strontianite correlate with TDS and rise to - 1.42 and 2.05, respectively. Low Sr values do not correlate with the residence time of groundwater in the aquifer or the depth of wells and tend to depressions in the relief, with a virtual absence of overlying sediments and positive Eh values, which indicates an active water exchange. The low level of Sr is associated with the dissolution of gypsum, calcite, and dolomite containing strontium as an impurity. This causes the SIs for gypsum, calcite, and dolomite to correlate with TDS, while for celestite and strontianite, the SI drops to - 5.02 and - 0.92, respectively. The established patterns make it possible to more reasonably choose places for the construction of water wells to obtain drinking water of standard quality.

Hydroxyapatite Nanopowders for Effective Removal of Strontium Ions from Aqueous Solutions

Drinking water contamination has become a worldwide problem due to the highly negative effects that pollutants can have on human organisms and the environment. Hydroxyapatite (HAp) has the appropriate properties for the immobilization of various pollutants, being considered amongst the most cost-effective materials for water decontamination. The main objective of this study was to use synthesized hydroxyapatite for the elimination of Sr²⁺ ions from contaminated solutions. The hydroxyapatite used in the decontamination process was synthesized in the laboratory using an adapted method. The hydroxyapatite powder (HAp) resulting from the synthesis was analyzed both before and after the elimination of Sr²⁺ ions from contaminated solutions. The efficiency of the HAp nanoparticles in removing Sr²⁺ ions from contaminated solution was determined by batch adsorption experiments. X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to study the HAp samples before and after the removal of Sr²⁺ ions. The ability of HAp nanoparticles to eliminate strontium ions from contaminated solutions was established. Moreover, the removal of Sr²⁺ ions from the contaminated aqueous solutions was highlighted by ultrasound measurements. The value of the stability parameter calculated by ultrasonic measurements after the removal of Sr²⁺ ions from the contaminated solution was similar to that of double distilled water whose stability was used as reference. The outcomes of the batch experiments and the parameters obtained from Langmuir and Freundlich models indicated that the HAp nanoparticles had a strong affinity for the elimination of Sr²⁺ ions from polluted solutions. These results emphasized that HAp nanoparticles could be excellent candidates in the development of new technologies for water remediation. More than that, the outcomes of the cytotoxic assays proved that HAp nanoparticles did not induce any noticeable harmful effects against HeLa cells and did not affect their proliferation after 1 day and 7 days of incubation.

In vivo quantification of strontium in bone among adults using portable x-ray fluorescence

BACKGROUND AND OBJECTIVE

Bone strontium (Sr) is a reliable biomarker for studying related bone health outcomes and the effectiveness of Sr supplements in osteoporosis disease treatment. In this study, we evaluated the sensitivity of portable x-ray fluorescence (XRF) technology for in vivo bone Sr quantification among adults.

MATERIALS AND METHODS

Sr-doped bone-equivalent phantoms were used for system calibration. Using the portable XRF, we measured bone Sr levels in vivo in mid-tibia bone in 76 adults, 38-95 years of age, living in Indiana, US; we also analyzed bone data of 29 adults, 53-82 years of age, living in Shanghai, China. The same portable XRF device and system settings were used in measuring their mid-tibia bone. We compared bone Sr concentrations by sex, age, and recruitment site. We also used multiple linear regression model to estimate the association of age with bone Sr concentration, adjusting for sex and recruitment site.

RESULTS

The uncertainty of in vivo individual measurement increased with higher soft tissue thickness overlying bone, and it ranged from 1.0 ug/g dry bone (ppm) to 2.4 ppm with thickness ranging from 2 to 7 mm, with a measurement time of 5 min. Geometric mean (95% confidence interval (CI)) of the bone Sr concentration was 79.1 (70.1, 89.3) ppm. After adjustment for recruitment site and sex, an increase in five years of age was associated with a 8.9% (95% CI: 2.5%, 15.6%) increase in geometric mean bone Sr concentration.

DISCUSSION AND CONCLUSION

Sr concentrations were consistently well above detection limits of the portable XRF, and exhibited an expected increase with age. These data suggest that the portable XRF can be a valuable technology to quantify Sr concentration in bone, and in the study of Sr-related health outcomes among adults, such as bone mineral density (BMD) and bone fracture risk.

Effect of Resveratrol, L-Carnitine, and Aromatic Amino Acid Supplements on the Trace Element Content in the Organs of Mice with Dietary-Induced Obesity

Given environmental contamination with toxic metals, diets that promote the elimination of these metals from the body of individuals, including those suffering from obesity, are urgently needed. The aim of this study was to determine the effects of supplementation with resveratrol (Res), L-carnitine (L-Car), tyrosine (Tyr), and tryptophan (Trp) on the content of trace elements in the organs of mice. DBA/2J mice and DBCB tetrahybrid mice received diets high in carbohydrate and fat supplemented with Res, L-Car, Tyr, or Trp for 65 days. In the liver, kidneys, and brain, the contents of 18 elements, including Al, As, Cu, Fe, Mn, Pb, Se, and Zn, were determined by inductively coupled plasma mass spectrometry. Res, L-Car, Tyr, and Trp had minimal or no effect on the essential elements (Fe, Mg, Cu, Zn, Se) in all organs studied. The Mn content notably increased in the organs of mice consuming L-Car and Trp. Mn accumulation was stimulated by Res in organs exclusively in DBCB mice and by Tyr exclusively in livers and brains of DBA/2J mice. Al levels were significantly reduced by L-Car and Trp in all organs of the mice, by Res in only DBCB mice, and by Tyr in only kidneys and livers of DBA/2J mice. In addition, L-Car and Trp decreased Pb accumulation in most organs of mice. Res and Tyr also inhibited Pb accumulation in some cases. Thus, the studied supplements affected the metabolism of trace elements, which may contribute to dietary treatments for obese individuals.

Health risk assessment of heavy metals and strontium in groundwater used for drinking and cooking in 58 villages of Prakasam district, Andhra Pradesh, India

Groundwater is one of the most important sources of water for drinking and cooking in rural India. A total of 382 groundwater samples were collected from 58 villages and analyzed for HMs and Sr by inductively coupled plasma mass spectrometer. The average concentrations of HMs and Sr in water was in the order of strontium (Sr) > arsenic (As) > chromium (Cr) > lead (Pb) > mercury (Hg) > cadmium (Cd). Out of 58 villages, 21, 37, 35, 35, 35 and 39 villages had Cr, As, Cd, Hg, Pb and Sr higher (WHO limit) than their respectively permissible levels. Health risk assessment of HMs and Sr for humans revealed that the non-carcinogenicity hazard quotients (HQ_i+d) for HMs and Sr were higher than unity for adult and children. The hazard index (HI) was 531.066 for adult and 902.926 for children. The HI > 1 was observed in 45 villages for adults and 56 villages for children. The lifetime cancer risk in adult for As_i, As_d, and Pb_i in 36, 25 and 23 villages, whereas in children was 42, 20 and 22 villages, respectively. In conclusion, the health risks arising from consumption of groundwater containing HMs and Sr indicated that there is a significant carcinogenic risks for adult and children. This is the first attempt to provide information on the health risks of Sr in drinking water in India. The present findings can be useful for the development of potential strategies for risk control and management.

ICP-MS Analysis of Trace Element Concentrations in Cow's Milk Samples from Supermarkets in Istanbul, Turkey

Milk is a very important content of the human diet. The present study was performed to determine the concentrations of trace and toxic trace elements in 21 different milk samples in Turkish supermarkets. We aimed to evaluate the potential health risks of toxic elements to humans through ingestion. The concentrations of 19 elements lithium (Li), beryllium (Be), chromium (Cr), manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), arsenic (As), selenium (Se), strontium (Sr), molybdenum (Mo), cadmium (Cd), antimony (Sb), barium (Ba), lead (Pb), bismuth (Bi), mercury (Hg), thallium (Tl), and uranium (U) in milk samples were determined by using inductively coupled plasma-mass spectrometry (ICP-MS). The accuracy and precision of the method were verified by experiments. Nutritional trace elements were found to be below their reference intake levels. Although we found wide variation between the toxic element levels in the samples, none of the concentrations reached a health-threatening level. This is the first study presenting a wide range of elements including the toxic ones in a different variety of milk samples sold throughout the Turkish supermarkets.

Absorption of strontium by foods prepared in drinking water

Strontium (Sr) is a natural element, ubiquitous in the environment and known to occur in water, food, air, and soils. Strontium is present in media as a salt or an ionized divalent cation. The Sr ion (dissociated) is toxicokinetically important because it is easily absorbed into systemic circulation when inhaled with particulates or ingested with water or foods. Dietary exposure can be influenced by using tap water containing dissolved Sr in food preparation. Research was conducted to determine the amount of Sr transferred from water to individual foods during preparation. Strontium transferred to broccoli, lentils, and spaghetti at all levels tested (1.5, 10, and 50 mg/L) as evidenced by the residual Sr in the pour-off water following food preparation (33-64%). The data from the cooking study support the hypothesis that cooking of foods with water containing Sr adds to total dietary exposure. This information can inform the determination of the relative source contribution (RSC) that is typically used in developing drinking water advisory guidelines. These cooking study results indicate that food prepared in water containing Sr should be considered as part of the food in a dietary exposure assessment.

Measurements of Strontium Levels in Human Bone In Vivo Using Portable X-ray Fluorescence (XRF)

Measurement of bone strontium (Sr) is vital to determining the effectiveness of Sr supplementation, which is commonly used for the treatment of osteoporosis. Previous technology uses radioisotope sources and bulky equipment to measure bone Sr. This study demonstrates the effectiveness of portable X-ray fluorescence (XRF) for bone Sr measurement and validates it using data from a population of 238 children. We identified correlations between bone Sr and age in our participants.

Cesium and strontium tolerant Arthrobacter sp. strain KMSZP6 isolated from a pristine uranium ore deposit

Arthrobacter sp. KMSZP6 isolated from a pristine uranium ore deposit at Domiasiat located in North-East India exhibited noteworthy tolerance for cesium (Cs) and strontium (Sr). The strain displayed a high minimum inhibitory concentration (MIC) of 400 mM for CsCl and for SrCl2. Flow cytometric analysis employing membrane integrity indicators like propidium iodide (PI) and thiazole orange (TO) indicated a greater sensitivity of Arthrobacter cells to cesium than to strontium. On being challenged with 75 mM of Cs, the cells sequestered 9612 mg Cs g(-1) dry weight of cells in 12 h. On being challenged with 75 mM of Sr, the cells sequestered 9989 mg Sr g(-1) dry weight of cells in 18 h. Heat killed cells exhibited limited Cs and Sr binding as compared to live cells highlighting the importance of cell viability for optimal binding. The association of the metals with Arthrobacter sp. KMSZP6 was further substantiated by Field Emission-Scanning Electron Microscopy (FE-SEM) coupled with Energy dispersive X-ray (EDX) spectroscopy. This organism tolerated up to 1 kGy (60)Co-gamma rays without loss of survival. The present report highlights the superior tolerance and binding capacity of the KMSZP6 strain for cesium and strontium over other earlier reported strains and reveals its potential for bioremediation of nuclear waste.

Vitamin D supplementation for preventing infections in children under five years of age

BACKGROUND

Vitamin D is a micronutrient important for bone growth and immune function. Deficiency can lead to rickets and has been linked to various infections, including respiratory infections. The evidence on the effects of supplementation on infections in children has not been assessed systematically.

OBJECTIVES

To evaluate the role of vitamin D supplementation in preventing pneumonia, tuberculosis (TB), diarrhoea, and malaria in children under five years of age. This includes high-, middle-, and low-income countries.

SEARCH METHODS

We searched the Cochrane Infectious Diseases Group Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), the Cochrane Library, MEDLINE, EMBASE, LILACS, the WHO International Clinical Trials Registry Platform (ICTRP; http://www.who.int/ictrp/en/) , ClinicalTrials.gov and the ISRCTN registry (http://www.isrctn.com/) up to 16 June 2016.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that evaluated preventive supplementation of vitamin D (versus placebo or no intervention) in children under five years of age.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the titles and abstracts, extracted the data, and assessed the risk of bias of included trials.

MAIN RESULTS

Four trials met the inclusion criteria, with a total of 3198 children under five years of age, and were conducted in Afghanistan, Spain, and the USA. Prevalence of vitamin D deficiency varied widely in these populations (range: 73.1% in Afghanistan, 10 to 12% in USA, and 6.2% in Spain). The included trials evaluated mortality (two trials), pneumonia incidence (two trials), diarrhoea incidence (two trials), hospitalization (two trials), and mean serum vitamin D concentrations (four trials).We do not know whether vitamin D supplementation impacts on all-cause mortality because this outcome was underpowered due to few events (risk ratio (RR) 1.43, 95% confidence interval (CI) 0.54 to 3.74; one trial, 3046 participants, low quality evidence).For pneumonia, episodes of 'radiologically confirmed' first or only episode of pneumonia were little different in the supplemented and unsupplemented group (Rate Ratio: 1.06, 95% confidence interval (CI) 0.89 to 1.26; two trials, 3134 participants, moderate quality evidence), and similarly for children with confirmed or unconfirmed pneumonia (RR 0.95, 95% CI 0.87 to 1.04; one trial, 3046 participants). In these two trials there were no obvious differences between supplemented and unsupplemented children regarding episodes of diarrhoea.In the single large trial from Afghanistan, the trial authors reported that vitamin D supplementation was associated with an increase in repeat episodes of pneumonia confirmed by chest radiograph (RR 1.69, 95% CI 1.28 to 2.21; one trial, 3046 participants), but not reflected in the outcome of confirmed or unconfirmed pneumonia (RR 1.06, 95% CI 1.00 to 1.13; one trial, 3046 participants).For hospital admission measured in one small trial, there was no difference detected (RR 0.86, 95% CI 0.20 to 3.62; one trial, 88 participants; very low quality evidence).The mean serum vitamin D concentrations were higher in supplemented compared to unsupplemented children at the end of supplementation (MD 7.72 ng/mL, 95% CI 0.50 to 14.93; four trials, 266 participants, low quality evidence). These results were driven primarily by two smaller trials with large magnitudes of effect. In the other two bigger trials, serum vitamin D concentrations were elevated in the intervention group for most of the trial duration but not at the end of supplementation. This may be due to time elapsed at measurement from the last dose, incomplete compliance, or increased need of vitamin D with infant age.We did not find any trial that reported on the incidence of TB, malaria or febrile illness, duration of pneumonia, duration of diarrhoea, severity of infection, and cause-specific mortality (due to TB, diarrhoea, or malaria).

AUTHORS' CONCLUSIONS

Evidence from one large trial did not demonstrate benefit of vitamin D supplementation on the incidence of pneumonia or diarrhoea in children under five years. To our knowledge, trials that evaluated supplementation for preventing other infections, including TB and malaria, have not been performed.

Modeling elemental strontium in human bone based on in vivo x-ray fluorescence measurements in osteoporotic females self-supplementing with strontium citrate

An in-house custom I-125 excited in vivo x-ray fluorescence (IVXRF) system was used to perform bone strontium (Sr) measurements in individuals suffering from osteoporosis and/or osteopenia. These individuals, who were self-administering with Sr supplements of their choice, were measured frequently, ranging from weekly to biweekly to monthly, over four years, as part of the Ryerson and McMaster Sr in Bone Research Study. Based on these data collected, data from eight subjects were used to perform kinetic modeling of Sr in human bone. Power and exponential models were used to model the data based on one and two compartmental systems. Model parameters included: mean normalized baseline bone Sr signal, half-life and bone Sr uptake. A one compartmental exponential model applied to finger and ankle bone measurements gave half-lives of (508  ±  331) d and (232  ±  183) d, respectively, but did not show statistically significant differences (p  =  0.087 96). However, the values fall within literature estimates. When a two compartmental model was applied to finger bone measurements, half-lives of (300  ±  163) d and (2201  ±  1662) d were observed. Ankle bone data gave half-lives of (156  ±  117) d and (1681  ±  744) d. A two sample t-test, assuming unequal variances, showed these half-lives to be statistically different in both the finger and ankle bone measurements (p  =  0.0147 and p  =  0.00711, respectively). Common kinetic parameters amongst the different subjects could not be unambiguously identified due to the wide scatter of data, leading to an inconclusive kinetic model. The wide distribution of data is suggested to be physiological since technical and positioning factors were eliminated as possible causes. This outcome indicates the need for a more controlled study and further understanding of the physiological mechanism of Sr absorption.

Assessment of diet and recognition of nutritional deficiencies in paleopathological studies: A review

An essential part of paleopathology is the study of diet and nutrition as well as inferring aspects of diet and nutrition from the skeletal pathology. Interpretation of nutritional and metabolic disease-related pathologies often provides additional insight into the daily social and cultural practices of people. However, precise diagnoses of specific vitamin-related deficiencies in archaeological skeletal remains are still quite problematic and specific diagnoses are rarely possible. This partly stems from the fact that many nutritional or metabolic diseases do not necessarily result in an osteological response and when they do, the comorbidity and analogous osteological responses to vitamin deficiencies may hamper the definite diagnosis of nutrition-related disease. Clin. Anat. 29:862-869, 2016. © 2016 Wiley Periodicals, Inc.

Quantitative bioanalysis of strontium in human serum by inductively coupled plasma-mass spectrometry

Aim:

A bioanalytical method using inductively-coupled plasma-mass spectrometry to measure endogenous levels of strontium in human serum was developed and validated.

Results & methodology:

This article details the experimental procedures used for the method development and validation thus demonstrating the application of the inductively-coupled plasma-mass spectrometry method for quantification of strontium in human serum samples. The assay was validated for specificity, linearity, accuracy, precision, recovery and stability. Significant endogenous levels of strontium are present in human serum samples ranging from 19 to 96 ng/ml with a mean of 34.6 ± 15.2 ng/ml (SD).

Discussion & conclusion:

Calibration procedures and sample pretreatment were simplified for high throughput analysis. The validation demonstrates that the method was sensitive, selective for quantification of strontium (⁸⁸Sr) and is suitable for routine clinical testing of strontium in human serum samples.

Lay abstract: The study of strontium in human serum is useful to understand its biological function. Strontium is found naturally in the environment including drinking water and food. This alkali earth metal plays a biological role in bone and has been shown to have therapeutic properties for osteoporosis and to suppress chemically induced sensory irritation and inflammation. A technique called inductively coupled plasma mass spectrometry was used for its superior ability to measure low levels of strontium in biological matrices. Strontium was measured in normal human samples to demonstrate the method utility and correlate with age, gender and race.

The content of selected metals in muscles of the red deer (Cervus elaphus) from Poland

The aim of this study was to evaluate the concentrations of Pb, Cu, Zn, Rb, Cs, Sr and Ba in the muscles of red deer that were hunted in two regions of Poland (south-western and north-eastern). The data obtained were evaluated with regards to benefits and potential risk to consumers' health. Samples for the investigations were collected in 2008 and 2009 from 50 female red deer, and the metal concentrations were determined by using the inductively coupled plasma-mass spectrometric (ICP-MS) method. The mean concentrations of Pb did not differ statistically between regions and were equal to that permitted for farm animals. The results of this study support the conclusion that the meat of the analysed animals does not pose a risk of lead intoxication. Statistically higher mean concentrations of Cu and Zn were found in the muscles of red deer from the south-western region (namely, 2.99 and 25.78 mg kg(-1)) than those in animals from north-eastern Poland (namely, 2.61 and 23.39 mg kg(-1) wet weight). In terms of human nutritional needs, the meat of red deer can be considered as a good source of Cu and Zn. Furthermore, Rb, Cs, Sr and Ba concentrations did not differ statistically between regions. Their mean concentrations were 4.50, 0.09, 0.16 and 0.31 mg kg(-1) wet weight, respectively. Although high Cs, Sr and Ba concentrations were found, the meat of red deer does not pose a risk for adult consumers. Only high Ba content may potentially result in negative health effects for children.

Monitoring bone strontium intake in osteoporotic females self-supplementing with strontium citrate with a novel in-vivo X-ray fluorescence based diagnostic tool

Ten female volunteers were recruited as part of the Ryerson and McMaster University Strontium (Sr) in Bone Research Study to have their bone Sr levels measured as they self-supplemented with Sr supplements of their choice. Of the ten volunteers, nine were suffering from osteopenia and/or osteoporosis. Non-invasive bone Sr measurements were performed using an in vivo x-ray fluorescence (IVXRF) I-125 based system. Thirty minute measurements were taken at the finger and ankle, representing primarily cortical and trabecular bone, respectively. For analysis, the 14.2keV Sr K-alpha peak normalized to the Coherent peak at 35.5keV was used. Baseline readings, representing natural bone Sr levels were acquired since all volunteers had no previous intake of Sr based supplements or medications. Once Sr supplements were started, a 24h reading was taken, followed by frequent measurements ranging from weekly, biweekly to monthly. The longest volunteer participation was 1535days. The mean baseline Sr signal observed for the group was 0.42±0.13 and 0.39±0.07 for the finger and ankle, respectively. After 24h, the mean Sr signal rose to 1.43±1.12 and 1.17±0.51, for the finger and ankle, respectively, representing a statistically significant increase (p=0.0043 & p=0.000613). Bone Sr levels continued to increase throughout the length of the study. However the Sr signal varied widely between the individuals such that after three years, the highest Sr signal observed was 28.15±0.86 for the finger and 26.47±1.22 for the ankle in one volunteer compared to 3.15±0.15 and 4.46±0.36, for the finger and ankle, respectively in another. Furthermore, while it was previously reported by our group, that finger bone Sr levels may plateau within two years, these results suggest otherwise, indicating that bone Sr levels will continue to rise at both bone sites even after 4years of Sr intake.

Effects of soil trace elements on longevity population in China

Based on background concentrations of elements in soils and the sixth population census data of China, this study discussed the distribution characteristics of soil elements and longevity population at province level in China. Percentages of the aging population are high in Southwest China and the eastern coastal region but low in western and northwestern regions. Provinces in South and Southwest China gain a high level of longevity, while the northern part of China has a low level of longevity. The background concentration of Se in soil has a significant positive correlation with longevity index, while Ba and Ni have a significant negative correlation with longevity indexes. By regression analysis, longevity index C/100,000 can be expressed as C/100,000 = 1.679-0.205 Ni + 0.413 Co + 0.006 Se (with R (2) = 0.402 and p < 0.01), C/65+ can be expressed as C/65+=3.425-0.262 Ni + 0.435 Co + 0.006 Se (with R (2) = 0.369 and p < 0.01).

Determination of reference concentrations of strontium in urine by inductively coupled plasma atomic emission spectrometry

OBJECTIVE

The aim of this study was to establish reference concentrations of urinary strontium by inductively coupled plasma atomic emission spectrometry (ICP-AES).

METHODS

For the determination of strontium, urine samples were collected from healthy Japanese (n=146; 115 males, 31 females; mean age, 33±9 years; age range, 18 to 58 years). The urine samples stored at or below -20°C were thawed with incubation at 40°C for 30 min and sediments were dissolved by vigorous shakings. Then, the samples were centrifuged at 3000 g for 5 min, and the supernatant was directly aspired into a P-5200-3600/1200 ICP-AES system from Hitachi Ltd., Tokyo, Japan.

RESULTS

A steeper increase in the S/N ratio and a good effective linearity of the calibration line was obtained at 407.771 nm in the range of 0-300 μg/L strontium standard solution. Urine samples having the same background signal as that of 18 MΩ cm ultrapure blank water, a good correspondence of the single peak pattern of the spectra, accuracy and precision of spike recovery were also confirmed. Urinary strontium concentrations showed a log-normal distribution and a geometric mean concentration of 143.9 μg/L, with 5-95% confidential interval of 40.9-505.8 μg/L.

CONCLUSION

The results of this study will be useful as guidelines for the biological monitoring of strontium in normal subjects and in individuals therapeutically or environmentally exposed to strontium.

An overview of boron, lithium, and strontium in human health and profiles of these elements in urine of Japanese

The biological, medical and environmental roles of trace elements have attracted considerable attention over the years. In spite of their relevance in nutritional, occupational and toxicological aspects, there is still a lack of consistent and reliable measurement techniques and reliable information on reference values. In this review our understandings of the urinary profilings of boron, lithium and strontium are summarized and fundamental results obtained in our laboratory are discussed.Over the past decade we have successfully used inductively coupled plasma emission spectrometry for the determination of reference values for urinary concentrations of boron, lithium and strontium. Taking into account the short biological half-life of these elements and the fact that their major excretion route is via the kidney, urine was considered to be a suitable material for monitoring of exposure to these elements. We confirmed that urinary concentrations of boron, lithium and strontium follow a lognormal distribution. The geometric mean reference values and 95% confidence intervals were 798 μg/l (398-1599 μg/l) for boron, 23.5 μg/l (11.0-50.5 μg/l) for lithium and 143.9 μg/l (40.9-505.8 μg/l) for strontium. There were no discrepancies between our values and those previously reported. Our reference values and confidential intervals can be used as guidelines for the health screening of Japanese individuals to evaluate environmental or occupational exposure to these elements.

Spatial distribution of calcium in food, water and soil and its possible influence on rickets disease in Northern Nigeria

Since the 1990s, children of the Gbagyi tribe in Northern Nigeria have been suffering severe rickets with an incidence of up to 40% in the children's generation. The disease seems to be prevalent in an area of approximately 100 km(2) south-east of Kaduna. According to broad medical studies in that area, there is no evidence for a genetic disposition but for a nutritional cause of the disease. A lack of calcium was found in blood and was calculated to originate from diet. We therefore checked parent material, soil, maize cobs (Zea mays) and drinking water for their specific Ca contents from a region with rickets problem (study area A) and compared the results to Ca amounts in similar samples from a region where rickets is unknown among the Gbagyi population (study area B). It thereby became apparent that there are no differences in mineralogical composition of the parent material between the study areas, but that Ca contents in soil, maize cobs and drinking water are 47.6%, 26.6%, respectively, 79.1% lower in study area A compared to study area B. This result suggests that there may indeed be a nutritionally and/or environmentally influence on rickets disease. Nevertheless, further research on this topic is required.

Monitoring bone strontium levels of an osteoporotic subject due to self-administration of strontium citrate with a novel diagnostic tool, in vivo XRF: a case study

A previously developed in vivo X-ray fluorescence (IVXRF) I-125 based system was used to measure bone strontium levels non-invasively in an osteoporotic female volunteer. The volunteer was recruited in December 2008, as part of the Ryerson and McMaster University Strontium in Bone Research Study and measured at twice weekly, weekly and monthly intervals. Thirty minute measurements were taken at the finger and ankle bone sites, representing primarily cortical and trabecular bone, respectively and the strontium K-alpha X-ray peak at 14.16 keV was used in the analysis. Since the volunteer had no prior history of strontium based medications or supplementation, baseline natural strontium levels were obtained followed by a 24h measurement of first intake of strontium citrate supplements (680 mg Sr/day). While the baseline levels of 0.38 ± 0.05 and 0.39 ± 0.10 for the finger and ankle, respectively, were on par with those previously reported in Caucasians among twenty-two healthy non-supplementing strontium individuals by our group, an increase began to be seen after 24 hrs of 0.62 ± 0.14 and 0.45 ± 0.12 for the finger and ankle, respectively. By 120 h, the increase was statistically significant at 0.68 ± 0.07 and 0.93 ± 0.05, respectively. Further increases occurred within an interval of 90-180 days, with the most recent, after 800 days, at the finger and ankle being 7 and 15 times higher than the initial baseline reading. The intriguing results show bone strontium incorporation and retention follow a pattern, suggesting strontium levels, at least in the ankle, do not plateau within two to three years and will continue to increase over time, as an individual takes strontium supplements. The ability of this IVXRF system to monitor and measure bone strontium levels over time provides a useful diagnostic tool to help gain insight into strontium bone kinetics.

Effects of vitamin D supplementation to children diagnosed with pneumonia in Kabul: a randomised controlled trial

OBJECTIVES

To determine whether (i) supplementation of oral 100,000 iu of vitamin D(3) (cholecalciferol) along with antibiotics will reduce the duration of illness in children with pneumonia; (ii) supplementation will reduce the risk of repeat episodes.

METHODS

Double-blind individually randomised placebo-controlled trial in an inner-city hospital in Kabul, of 453 children aged 1-36 months, diagnosed with non-severe or severe pneumonia at the outpatient clinic. Children with rickets, other concurrent severe diseases, very severe pneumonia or wheeze, were excluded. Children were given vitamin D(3) or placebo drops additional to routine pneumonia treatment.

RESULTS

Two hundred and twenty-four children received vitamin D(3;) and 229 received placebo. There was no significant difference in the mean number of days to recovery between the vitamin D(3) (4.74 days; SD 2.22) and placebo arms (4.98 days; SD 2.89; P = 0.17). The risk of a repeat episode of pneumonia within 90 days of supplementation was lower in the intervention (92/204; 45%) than the placebo group [122/211; (58%; relative risk 0.78; 95% CI 0.64, 0.94; P = 0.01]. Children in the vitamin D(3) group survived longer without experiencing a repeat episode (72 days vs. 59 days; HR 0.71; 95% CI 0.53-0.95; P = 0.02).

CONCLUSION

A single high-dose oral vitamin D(3) supplementation to young children along with antibiotic treatment for pneumonia could reduce the occurrence of repeat episodes of pneumonia.

Minerals and vitamins in bone health: the potential value of dietary enhancement

Nutrition is important to bone health, and a number of minerals and vitamins have been identified as playing a potential role in the prevention of bone diseases, particularly osteoporosis. Despite this, there is currently no consensus on maximum levels to allow in food or as dietary supplements. The benefits of supplementation of populations at risk of osteoporosis with Ca and vitamin D are well established. Prolonged supplementation of Ca and vitamin D in elderly has been shown to prevent bone loss, and in some intervention studies to prevent fragility fractures. Although P is essential to bone health, the average intake is considered to be more than sufficient and supplementation could raise intake to adverse levels. The role of vitamin K in bone health is less well defined, though it may enhance the actions of Ca and vitamin D. Sr administered in pharmacological doses as the ranelate salt was shown to prevent fragility fractures in postmenopausal osteoporosis. However, there is no hard evidence that supplementation with Sr salts would be beneficial in the general population. Mg is a nutrient implicated in bone quality, but the benefit of supplementation via foodstuffs remains to be established. A consensus on dietary supplementation for bone health should balance the risks, for example, exposure of vulnerable populations to values close to maximal tolerated doses, against evidence for benefits from randomised clinical trials, such as those for Ca and vitamin D. Feedback from community studies should direct further investigations and help formulate a consensus on dietary supplementation for bone health.

Strontium ranelate does not stimulate bone formation in ovariectomized rats

INTRODUCTION

Strontium ranelate (SrR) is suggested to function as a dual-acting agent in the treatment of postmenopausal osteoporosis with anti-resorptive and anabolic skeletal benefits. We evaluated the effects of SrR on the skeleton in ovariectomized (OVX) rats and evaluated the influence of dietary calcium.

METHODS

Three-month old virgin female rats underwent ovariectomy (OVX, n = 50) or SHAM surgery (SHAM, n = 10). Four weeks post-surgery, rats were treated daily by oral gavage with distilled water (10 ml/kg/day) or SrR (25 or 150 mg/kg/day) for 90 days. Separate groups of animals for each dose of SrR were fed a low (0.1%) or normal (1.19%) calcium (Ca) diet. Static and dynamic histomorphometry, DXA, mu-CT, mechanical testing, and serum and skeletal concentrations of strontium were assessed.

RESULTS

SrR at doses of 25 and 150 mg/kg/day did not increase bone formation on trabecular or periosteal bone surfaces, and failed to inhibit bone resorption of trabecular bone regardless of Ca intake. There were no improvements in bone mass, volume or strength with either dose of SrR given normal Ca.

CONCLUSION

These findings demonstrate that SrR at dosages of 25 and 150 mg/kg/day did not stimulate an anabolic bone response, and failed to improve the bone biomechanical properties of OVX rats.

Coherent normalization of finger strontium XRF measurements: feasibility and limitations

A non-invasive in vivo x-ray fluorescence (XRF) method of measuring bone strontium concentrations has previously been reported as a potential diagnostic tool able to detect strontium concentration in the finger and ankle bones. The feasibility of coherent normalization for (125)I-source-based finger bone strontium x-ray fluorescence (XRF) measurements is assessed here by theoretical considerations and Monte Carlo simulations. Normalization would have several advantages, among which are the correction for the signal attenuation by the overlying soft tissue, and intersubject variability in the bone size and shape. The coherent normalization of bone strontium XRF measurements presents several challenges dictated by the behaviour of the coherent cross section and mass attenuation coefficient at the energies involved. It was found that the coherent normalization alone with either 22.1 keV or 35.5 keV photons was not successful in correcting for the overlying soft tissue attenuation. However, it was found that the coherent peak at 35.5 keV was able to correct effectively for variability in the finger bone size between people. Thus, it is suggested that, if the overlying soft tissue thickness can be obtained by means of an independent measurement, the 35.5 keV peak can be used to correct for the bone size, with an overall accuracy of the normalization process of better than 10%.

In vivostudy of an x-ray fluorescence system to detect bone strontium non-invasively

An x-ray fluorescence (XRF) system using 125I as the source was developed to measure strontium in bone in vivo. As part of an in vivo pilot study, 22 people were measured at two bone sites, namely the index finger and the tibial ankle joint. Ultrasound measurements were used to obtain the soft tissue thickness at each site, which was necessary to correct the signal for tissue attenuation. For all 22 people, the strontium peak was clearly distinguishable from the background, proving that the system is able to measure Sr in vivo in people having normal bone Sr levels. Monte Carlo simulations were carried out to test the feasibility and the limitations of using the coherently scattered peak at 35.5 keV as a means to normalize the signal to correct for the bone size and shape. These showed that the accuracy of the normalized Sr signal when comparing different people is about 12%. An interesting result arising from the study is that, in the measured population, significantly higher measurements of bone Sr concentration were observed in continental Asian people, suggesting the possibility of a dietary or race dependence of the bone Sr concentration or a different bone biology between races.

Nutritional rickets around the world: causes and future directions

INTRODUCTION

Nutritional rickets has been described from at least 59 countries in the last 20 years. Its spectrum of causes differs in different regions of the world.

METHODS

We conducted a systematic review of articles on nutritional rickets from various geographical regions published in the last 20 years. We extracted information about the prevalence and causes of rickets.

RESULTS

Calcium deficiency is the major cause of rickets in Africa and some parts of tropical Asia, but is being recognised increasingly in other parts of the world. A resurgence of vitamin D deficiency has been observed in North America and Europe. Vitamin D-deficiency rickets usually presents in the 1st 18 months of life, whereas calcium deficiency typically presents after weaning and often after the 2nd year. Few studies of rickets in developing countries report values of 25(OH)D to permit distinguishing vitamin D from calcium deficiency.

CONCLUSIONS

Rickets exists along a spectrum ranging from isolated vitamin D deficiency to isolated calcium deficiency. Along the spectrum, it is likely that relative deficiencies of calcium and vitamin D interact with genetic and/or environmental factors to stimulate the development of rickets. Vitamin D supplementation alone might not prevent or treat rickets in populations with limited calcium intake.

Time-evolution and reversibility of strontium-induced osteomalacia in chronic renal failure rats

BACKGROUND

Patients with impaired renal function can accumulate strontium in the bone, which has been associated with the development of osteomalacia. A causal role for strontium in the development of the disease was presented in chronic renal failure (CRF) rats. Strontium-ranelate has been put forward as a therapeutic agent in the treatment of osteoporosis. Since the target population for strontium treatment consists mainly in postmenopausal osteoporotic women, who may have a reduced renal function, the risk for osteomalacia should be considered.

METHODS

To determine the time evolution and reversibility of the strontium-induced mineralization defect, CRF rats were loaded with strontium (2 g/L) (+/- 200 mg/kg/day) during 2, 6, and 12 weeks, followed by a washout period of 0, 2, 4, or 8 weeks.

RESULTS

Histologic examination of the bone of the animals treated with strontium revealed signs of osteomalacia already after 2 weeks. Animals that received strontium during 6 and 12 weeks had a significantly higher osteoid perimeter, area and thickness as compared to CRF controls. After 12 weeks, the mineralization was significantly affected, as evidenced by a lower double-labeled surface, mineral apposition and bone formation rate in combination with an increased osteoid maturation time and mineralization lag time. The osteoblast perimeter was significantly lower in the strontium-treated animals. After the washout periods, these effects were reversed and the bone lesions evolved to the values of CRF controls. This went along with an 18% reduction of the bone strontium content. A significant rise in serum alkaline phosphatase (ALP) activity was apparent in the strontium-treated animals as compared to CRF controls. This was not only due to higher levels of the bone ALP but also to those of the liver and the intestinal isoenzymes. Serum parathyroid hormone (PTH) levels decreased during strontium treatment. After cessation of the treatment, the serum ALP activity and PTH concentration reversed to control levels.

CONCLUSION

In this study evidence is provided for the rapid development of a mineralization defect in strontium-loaded CRF rats, accompanied by a reduced osteoblast number, reduced PTH synthesis or secretion, and increased serum ALP levels. These effects can be rapidly reversed after withdrawal of the compound.

Environmental influences on the trace element content of teeth--implications for disease and nutritional status

The aim of this study was to compare the trace element content of children's primary teeth from Uganda and the UK. The Ugandan teeth were from children living in an area where endomyocardial fibrosis (EMF), a cardiac disease, is prevalent. The latter has been putatively linked to insufficient magnesium intake and excess cerium exposure. Primary teeth were collected from 21 Ugandan and 27 UK children. The crowns and roots of the teeth were separated and the former digested and analysed for several major and trace elements by inductively coupled plasma mass spectrometry (ICP-MS) and atomic emission spectrometry (ICP-AES). In addition, the enamel and dentine of eight UK and seven Ugandan primary teeth were isolated via density separation and analysed as above. The data were assessed using non-parametric statistical tests. The Ugandan teeth contained significantly (P < 0.05) greater concentrations of strontium, barium, cerium, lanthanum, praseodymium and significantly less zinc than the UK teeth. No significant difference in the concentrations of aluminium, calcium, copper, magnesium, lead and uranium were found. Analysis of enamel and dentine demonstrated that the former was enriched with several elements including cerium. It is concluded, that the environment, influences the trace element content of primary teeth and this may be useful for monitoring nutritional status. With respect to a geochemical cause for EMF, there is no positive evidence that EMF in Uganda is associated with reduced magnesium and increased cerium uptake in primary teeth. This does not, however, exclude cerium from playing a role in the aetiology of EMF.

Effects of strontium on the physicochemical characteristics of hydroxyapatite

In a previous experimental study using a chronic renal failure rat model, a dose-related multiphasic effect of strontium (Sr) on bone formation was found that could be reproduced in an in vitro set-up using primary rat osteoblasts. The results from the latter study allowed us to distinguish between a reduced nodule formation in the presence of an intact mineralization at low Sr-doses (1 microg/ml) and an interference of the element with the hydroxyapatite (HA) formation at high doses (20-100 microg/ml). To further investigate the latter effect of Sr on physicochemical bone mineral properties, an in vitro study was set up in which the UMR-106 rat osteosarcoma cell line was exposed to Sr, added to the cell culture medium in a concentration range varying between 0-100 microg/ml. Temporal growth and functionality of the culture was investigated by measurement of the alkaline phosphatase activity and calcium (Ca) concentration in the culture medium (used as an index of Ca-incorporation, i.e., HA formation) at various time points. At the end of the culture period (14 days post-confluence), samples of the mineralized cultures were taken for further analysis using X-ray diffraction (XRD) and Fourier Transform Infra-Red Spectroscopy (FTIR). Synthetic HA doped with various Sr concentrations (based on the cell culture and previous experimental studies and yielding Sr/(Sr + Ca) ratios ranging from 0-60%), was prepared and examined for crystal growth and solubility. Crystal size was assessed using scanning electron microscopy (SEM). Ca incorporation indicated a reduced mineralization in the 20 and 100 microg/ml Sr groups vs. controls. Sr-doped synthetic HA showed a significant dose-dependent reduction in crystal growth, as assessed by SEM, and an increase in solubility, apparent from 12.7% Sr/(Sr + Ca) on. Moreover, in both mineralized cultures and synthetic HA, XRD and FTIR analysis showed a reduced crystallinity and altered crystal lattice at similar concentrations. These new data support our previous in vivo and in vitro findings and point to a potential physicochemical interference of Sr with HA formation and crystal properties in vivo.

Quantification of bone strontium levels in humans by in vivo x-ray fluorescence

The need for in vivo bone strontium assessment arises because strontium may exert a number of effects on bone, which may be either beneficial or toxic. Measurements discussed here are noninvasive, no sample is taken, nor is there discomfort to patients. The developed source excited x-ray fluorescence system employs a 109Cd source to excite the strontium K x rays, with the source and detector in approximately 90 degree geometry relative to the sample position. The factors affecting the accuracy and minimal detectable limit for bone strontium in vivo measurements are discussed. A system calibration revealed a minimum detectible limit of approximately 0.25 mg Sr/g Ca, which is sufficient for the monitoring of strontium levels in healthy subjects and patients with elevated bone strontium concentrations. Preliminary in vivo measurements in ten healthy subjects at two bone sites (phalanx and tibia) indicated that this system can be applied for cumulative bone strontium estimation while delivering a low effective dose of 80 nSv during the measurement time. Future work will involve attempts to enhance system precision with alternative fluorescing sources and further optimization of the detection system.

The biological role of strontium

This review summarises old and more recent literature on the biological role of the bone-seeking trace metal strontium (Sr). It covers areas of chemistry, nutrition, toxicity, transport across biological membranes, homeostasis, general physiology, calcium-strontium interactions, and particularly the role of strontium in bone. The promoting action of strontium on calcium uptake into bone at moderate strontium supplementation, and the rachitogenic action of strontium at higher dietary strontium levels are emphasised. The literature is summarised of the novel antiosteoporotic drug strontium ranelate, which appears to act by a combination of reduced bone resorption and increased uptake of calcium into bone.

Rapid assessment of the prevalence of lower limb clinical rickets in Bangladesh

This study attempted to measure the prevalence of lower limb clinical rickets using a rapid assessment methodology in Cox's Bazaar, a coastal district of Bangladesh. The study populations were drawn from 28 random villages representing all seven 'thanas' (subdistricts) of the district. Data were collected on 25,891 children and young people aged 1-20 years in two phases. In the first phase, 30 trained, local, non-medical people listed 490 children suffering from visible signs of any physical disability. To achieve this, they demonstrated a multicolored poster showing the features of lower limb clinical rickets to key informants in the villages. In the second phase, two teams of medically trained people (physicians), each with one male and one female, validated the above cases for rickets. They verified and validated 278 cases in five thanas. Due to inclement weather and floods, they could not visit the other two thanas. Based on these data, the adjusted prevalence rates for lower limb clinical rickets were calculated to be 931 per 100,000 population (95% confidence intervals 795-1067). The prevalence was highest (1215) in children aged 1-4 years and lowest (498) amongst 17-20 year olds. Females had lower prevalence than males. Based on the study experience, a quick investigation using a similar methodology was performed in five other districts (Sunamganj, Noakhali, Bhola, Jessore and Gaibandha), and clinical signs of lower limb rickets were found in Sunamganj and Jessore. It thus indicates that rickets may be endemic, not only in Cox's Bazaar but also in some other parts of Bangladesh. The methodology used for this study was found to be rapid, simple, replicable and inexpensive.

Ultrasound measurements of overlying soft tissue thickness at four skeletal sites suitable for in vivo x-ray fluorescence

Due to signal attenuation in overlying soft tissue, development of x-ray fluorescence systems to measure low atomic number elements, such as strontium, in human bone required a search for a skeletal site with thin overlying tissue. This paper reports ultrasound measurements of overlying tissue on 10 subjects, at four anatomical sites. The average tissue thickness at the finger was (2.9+/-0.7) mm. The average tissue thicknesses were (3.6+/-0.7) mm, (4.8+/-2.0) mm, and (8.4+/-1.7) mm at forehead, tibia and heel, respectively. Additionally, both parametric and nonparametric approaches to the relationship between body mass index (BMI) and tissue thickness suggest that there is a significant linear correlation between the subject's BMI and overlying tissue at the finger and heel bone. These correlations might be used as a criterion to perform XRF measurements, however a larger data set is required to address these correlations more clearly.

Renal osteodystrophy in developing countries

There are distinct differences between developing and developed countries regarding the pathogenesis and management of renal osteodystrophy. Such differences are due to ethnic factors, dialysis quality, types of membranes, dialysate water, lack of technical facilities to perform bone biopsies, beta2-microglobulin, aluminium and strontium toxicity, and iron overload as well as economic factors hampering the use of effective yet more expensive phosphate binders and active vitamin D. The prevalence of renal osteodystrophy in developing countries is higher than in developed countries. It ranges from 24.4% to 63%. Aluminium related bone disease is a common cause. High strontium levels and iron overload in developing countries play a major role in the development of renal bone disease among dialysis patients.

Increased bone strontium levels in hemodialysis patients with osteomalacia

BACKGROUND

In this study, we report on the association between increased bone strontium levels and the presence of osteomalacia in end-stage renal failure patients treated by hemodialysis.

METHODS

We performed a histologic examination and determined the strontium content and strontium/calcium ratios in bone biopsies of 100 hemodialysis patients recruited from various centers all over the world. Aside from the bone strontium concentration, the bone aluminum content was assessed. The bone zinc concentration, a nonrelevant element for bone toxicity, was also measured.

RESULTS

Bone strontium levels and bone strontium/calcium ratios were increased in subjects with osteomalacia when compared with those with the other types of renal osteodystrophy. Bone strontium and bone calcium levels correlated with each other. The slope of the linear regression curve correlating these parameters was much steeper in the osteomalacic group (Y = 2.22X - 120) as compared with the other types of renal osteodystrophy (Y = 0.52X - 5.7). Within the group of patients with osteomalacia, bone strontium levels also significantly correlated with the bone aluminum content (r = 0.72, P = 0.018). No such correlation was found for the other types of renal osteodystrophy. The bone zinc concentration of subjects with normal renal function did not differ significantly from the values noted for the various types of renal osteodystrophy taken as separate groups, nor could increased bone zinc concentrations be associated with a particular bone lesion.

CONCLUSIONS

Our data demonstrate an association between osteomalacia and increased bone strontium concentrations in dialysis patients. Further studies are warranted to establish whether strontium plays either a primary, secondary, or contributive role in the development of the latter type of renal osteodystrophy.

Low bone turnover in patients with renal failure

Renal failure inevitably leads to metabolic bone disease. Low turnover disease or adynamic bone disease (ABD) is characterized by a low number of osteoblasts with normal or reduced numbers of osteoclasts. Mineralization proceeds at a normal rate, resulting in normal or decreased osteoid thickness. Recently, it became clear that the relative contribution of the various types of renal osteodystrophy (ROD) to the spectrum of the histologic picture in renal failure patients underwent profound changes during the last 25 years. At the moment, the exact physiopathological mechanisms behind ABD are not yet elucidated, and thus the reason(s) for its increasing prevalence remains poorly understood. A number of epidemiological and experimental data suggest a multifactorial pathophysiologic process, in which hypoparathyroidism and suppression of the osteoblast are the main actors. Compared to adynamic bone disease, osteomalacia has now become a much rarer disease (around 4%), at least in Western countries. On the other hand, recent studies indicate that this particular bone disease entity might still regularly occur in less developed countries. Osteomalacia originates from a direct effect on the mineralization process. With this type of renal bone disease, the effects of secondary hyperparathyroidism on bone are overridden by a number of metabolic abnormalities that finally result in a defective bone mineralization, as occurs, for instance, when the lag time between osteoid deposition and its mineralization is increased. The relationship between exogenous and endogenous vitamin D deficiency (mainly calcitriol) and the histologic finding of osteomalacia in uremic patients is well known. Recent data showed distinctly lowered 25-(OH) vitamin D3 levels in the presence of unaffected calcitriol concentrations in patients with osteomalacic lesions, as assessed radiologically by the presence of Looser's zones. Recently, we found that bone strontium levels were increased in patients with osteomalacia as compared to all other types of ROD. Strontium accumulation appeared to originate mainly from the use of strontium-contaminated dialysate, which resulted from the addition of strontium-containing acetate-based concentrates. Evidence for a causal role of the element in the development of a mineralization defect could be tested experimentally by adding strontium to drinking water in a chronic renal failure rat model.

Increased serum strontium levels in dialysis patients: an epidemiological survey

BACKGROUND

We previously reported on increased bone strontium levels in dialysis patients with osteomalacia versus those presenting other types of renal osteodystrophy. A causal role of strontium in the development of osteomalacia was established in a chronic renal failure rat model.

METHODS

To further elucidate the latter issue and to find out whether dialysis patients from particular centers/countries are at an increased risk for strontium accumulation, a worldwide multicenter study was established. In total, 834 patients from 34 dialysis centers in 23 countries were included. In each of the patients, a serum sample was taken for strontium determination, and water and dialysate samples were taken at the various steps of the water purification process. For each patient clinical data and for each center dialysis modalities were recorded.

RESULTS

Strontium levels in serum of dialysis patients showed major differences between the various centers, ranging from mean values of 25 +/- 8 microgram/liter in the center with the lowest level up to 466 +/- 90 microgram/liter in the center with the highest concentration. It is of interest that these high levels were mainly found in developing countries. Furthermore, our data point toward a role of the final dialysate in the accumulation of the element, as indicated by the strong correlation (r = 0.74, P < 0.001) between mean serum and dialysate strontium levels. As the high tap water concentration of strontium was adequately reduced during the water purification process, contamination of the final dialysis fluid occurred by the addition of concentrates contaminated with strontium. Besides the dialysate, other factors, such as duration of dialysis, vitamin D supplements, or types of phosphate binders, played a less important role in the accumulation of the element.

CONCLUSIONS

Data of this multicenter study indicate patients of particular dialysis centers to be at an increased risk for strontium accumulation, the clinical consequence of which is under current investigation.