You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Correlates of bone microarchitectural parameters and serum sclerostin levels in men - the STRAMBO study. Sclerostin is predominantly expressed by osteocytes. Serum sclerostin levels are positively correlated with areal bone mineral density (aBMD) measured by DXA and bone microarchitecture assessed by high resolution peripheral quantitative computed tomography (HR-pQCT) in small studies. We assessed the relation of serum sclerostin levels with aBMD and microarchitectural parameters based on HR-pQCT in 1134 men aged 20-87 years using multivariable models adjusted for confounders (age, body size, lifestyle, co-morbidities, hormones regulating bone metabolism, muscle mass and strength). The apparent age-related increase in serum sclerostin levels was faster before the age of 63 than afterwards (0.43SD vs 0.20SD per decade). In 446 men aged ≤63, aBMD (spine, hip, whole body), trabecular volumetric BMD (Tb.vBMD) and trabecular number (Tb.N) at the distal radius and tibia were higher in the highest sclerostin quartile vs the three lower quartiles combined. After adjustment for aBMD, men in the highest sclerostin quartile had higher Tb.vBMD (mainly in the central compartment) and Tb.N at both skeletal sites (p<0.05-0.001). In 688 men aged >63, aBMD was positively associated with serum sclerostin levels at all skeletal sites. Cortical vBMD (Ct.vBMD) and cortical thickness (Ct.Th) were lower in the first sclerostin quartile vs the three higher quartiles combined. Tb.vBMD increased across the sclerostin quartiles which was associated with lower Tb.N and more heterogeneous trabecular distribution (higher Tb.Sp.SD) in men in the lowest sclerostin quartile. After adjustment for aBMD, men in the lowest sclerostin quartile had lower Tb.vBMD and Tb.N, but higher Tb.Sp.SD (p<0.05-0.001) at both the skeletal sites. In conclusion, serum sclerostin levels in men are strongly positively associated with better bone microarchitectural parameters, mainly trabecular architecture, regardless of the potential confounders. © 2013 American Society for Bone and Mineral Research.
{"Chemical": []}