Perirenal fat thickness and liver fat fraction are independent predictors of MetS in adults with overweight and obesity suspected with NAFLD: a retrospective study.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) has a multidirectional relationship with metabolic syndrome (MetS) and used to be considered a hepatic manifestation of MetS. Perirenal fat, as a part of visceral adipose tissue (VAT), was reported to be correlated with MetS components, but data for intraorgan fat are lacking. This study was undertaken to assess the value of peripheral and intraorgan fat to predict MetS in adults with overweight and obesity with suspected NAFLD. METHODS: We studied 134 sequential adults (mean age, 31.5 years; 47% female) with overweight and obesity with suspected NAFLD. All participants underwent abdominal magnetic resonance imaging (MRI) examination. Anthropometric and metabolic parameters and perirenal fat thickness (PRFT), subcutaneous adipose tissue thickness (SATT), liver fat fraction (LFF), pancreas fat fraction (PFF), and lumbar spine fat fraction (LSFF) were collected. MetS was defined according to the International Diabetes Federation (IDF) criteria. Statistical analyses included basic statistics, linear correlation and logistic regression analysis. RESULTS: A total of 63 adults with MetS and 71 adults with advanced liver steatosis (grades 2 and 3) were included in our study. Patients with MetS had greater PRFT (p = 0.026) and LFF (p < 0.001), as well as greater homeostasis model assessment of insulin resistance (HOMA-IR), alanine transaminase (ALT), aspartate transaminase (AST), and decreased SATT. MetS patients had a higher proportion of advanced steatosis than those without MetS (P < 0.001). The MetS score was associated with PRFT and LFF. Logistic regression analysis showed that the PRFT and LFF were independent predictors of MetS after adjusting for age and sex. A cutoff of 9.15 mm for PRFT and 14.68% for LFF could be predictive of MetS. CONCLUSIONS: This study shows that the absolute cutoff level of 9.15 mm for PRFT and 14.68% for LFF may be clinically important markers for identifying patients who are at high risk of MetS among adults with overweight and obesity with suspected NAFLD, irrespective of sex and age. Moreover, ectopic fat levels in pancreas and lumbar spine are positively associated with PRFT. TRIAL REGISTRATION: Not applicable.

Soluble expression and characterization of a mouse epididymis-specific protein lipocalin6.

Mouse lipocalin6 (mLcn6) was recently identified to be specifically expressed in the epididymis and speculated to may play a role in sperm maturation. However, further studies were hindered due to the bottleneck to obtain enough recombinant mLcn6 proteins. In this article, GB1 tag was successfully applied to improve the soluble expression of mLcn6. Thermal unfolding experiments demonstrate that GB1 can enhance the structural stability of mLcn6. Fluorescence spectroscopy experiments show that mLcn6 prepared according to our procedure has high affinities to both retinoic acid (K(d)=810nM) and retinol (K(d)=210nM). In conclusion, soluble, stable and active mLcn6 was recombinantly prepared with the help of the GB1 tag, which will facilitate the structural and functional studies of mLcn6.

Recombinant expression and characterization of an epididymis-specific antimicrobial peptide BIN1b/SPAG11E.

BIN1b was reported as an epididymis-specific beta-defensin antimicrobial peptide. In this paper, the recombinant BIN1b was expressed and purified by fusing with GB1-His tag. The size-exclusion gel filtration experiment indicated that the fusion protein GB1-BIN1b formed multimers at pH 7.4, and existed as monomer at pH 4.5. The oligomerization of GB1-BIN1b was only related to pH value, neither to NaCl concentration nor protein concentration. Far-UV circular dichroism (CD) spectra also showed the fusion protein had more ordered secondary structures at pH 4.5 than at pH 7.4, as a negative peak appeared around 218 nm indicative of typical beta-sheet. The 2D (15)N-(1)H heteronuclear single-quantum coherence (HSQC) spectra suggested that the fusion protein adopted a compact three-dimensional structure at pH 4.5. Colony forming unit (CFU) inhibition assay demonstrated that 25 microM fusion protein at pH 7.4 had an antimicrobial activity of 40% against E. coli K(12)D(31), which might imply the fusion protein functions as multimeric states. In conclusion, the GB1 fusion partner helps BIN1b form a stable homogenous conformation to facilitate subsequent structural determination without a significant effect on the antimicrobial activity.