Lower bone turnover and relative bone deficits in men with metabolic syndrome: a matter of insulin sensitivity? The European Male Ageing Study

Summary We examined cross-sectional associations of metabolic syndrome and its components with male bone turnover, density and structure. Greater bone mass in men with metabolic syndrome was related to their greater body mass, whereas hyperglycaemia, hypertriglyceridaemia or impaired insulin sensitivity were associated with lower bone turnover and relative bone mass deficits. Introduction Metabolic syndrome (MetS) has been associated with lower bone turnover and relative bone mass or strength deficits (i.e. not proportionate to body mass index, BMI), but the relative contributions of MetS components related to insulin sensitivity or obesity to male bone health remain unclear. Methods We determined cross-sectional associations of MetS, its components and insulin sensitivity (by homeostatic model assessment-insulin sensitivity (HOMA-S)) using linear regression models adjusted for age, centre, smoking, alcohol, and BMI. Bone turnover markers and heel broadband ultrasound attenuation (BUA) were measured in 3129 men aged 40–79. Two centres measured total hip, femoral neck, and lumbar spine areal bone mineral density (aBMD, n = 527) and performed radius peripheral quantitative computed tomography (pQCT, n = 595). Results MetS was present in 975 men (31.2 %). Men with MetS had lower β C-terminal cross-linked telopeptide (β-CTX), N-terminal propeptide of type I procollagen (PINP) and osteocalcin (P < 0.0001) and higher total hip, femoral neck, and lumbar spine aBMD (P ≤ 0.03). Among MetS components, only hypertriglyceridaemia and hyperglycaemia were independently associated with PINP and β-CTX. Hyperglycaemia was negatively associated with BUA, hypertriglyceridaemia with hip aBMD and radius cross-sectional area (CSA) and stress–strain index. HOMA-S was similarly associated with PINP and β-CTX, BUA, and radius CSA in BMI-adjusted models. Conclusions Men with MetS have higher aBMD in association with their greater body mass, while their lower bone turnover and relative deficits in heel BUA and radius CSA are mainly related to correlates of insulin sensitivity. Our findings support the hypothesis that underlying metabolic complications may be involved in the bone’s failure to adapt to increasing bodily loads in men with MetS

Enrichment of megabase-sized DNA molecules for single-molecule optical mapping and next-generation sequencing

Next-generation sequencing (NGS) has caused a revolution, yet left a gap: long-range genetic information from native, non-amplified DNA fragments is unavailable. It might be obtained by optical mapping of megabase-sized DNA molecules. Frequently only a specific genomic region is of interest, so here we introduce a method for selection and enrichment of megabase-sized DNA molecules intended for single-molecule optical mapping: DNA from a human cell line is digested by the NotI rare-cutting enzyme and size-selected by pulsed-field gel electrophoresis. For demonstration, more than 600 sub-megabase- to megabase-sized DNA molecules were recovered from the gel and analysed by denaturation-renaturation optical mapping. Size-selected molecules from the same gel were sequenced by NGS. The optically mapped molecules and the NGS reads showed enrichment from regions defined by NotI restriction sites. We demonstrate that the unannotated genome can be characterized in a locus-specific manner via molecules partially overlapping with the annotated genome. The method is a promising tool for investigation of structural variants in enriched human genomic regions for both research and diagnostic purposes. Our enrichment method could potentially work with other genomes or target specified regions by applying other genomic editing tools, such as the CRISPR/Cas9 system