Higher Fasting and Postprandial Free Fatty Acid Levels Are Associated With Higher Muscle Insulin Resistance and Lower Insulin Secretion in Young Non-Obese Women

Associations of adipose insulin resistance index with pancreatic β cell function (inverse) and glucose excursion (positive) in young Japanese women

The relationship of adipose tissue insulin resistance (AT-IR, a product of fasting insulin and free fatty acids) and homeostasis-model assessment-insulin resistance (HOMA-IR) to β-cell function was studied cross-sectionally in the setting of subtle glucose dysregulation. Associations of AT-IR and HOMA-IR with fasting and post-glucose glycemia and β-cell function inferred from serum insulin kinetics during a 75 g oral glucose tolerance test were studied in 168 young female Japanese students. β-cell function was evaluated by disposition index calculated as a product of the insulinogenic index (IGI) and Matsuda index. AT-IR, not HOMA-IR, showed positive associations with post-glucose glycemia and area under the glucose response curve although both indices were associated with fasting glycemia. HOMA-IR, not AT-IR, was associated positively with log IGI whereas both indices were inversely associated with Matsuda index. AT-IR, not HOMA-IR, showed inverse associations with log disposition index. Associations of adipose tissue insulin resistance with β-cell function (inverse) and glucose excursion in young Japanese women may suggest that lipotoxicity to pancreatic β-cells for decades may be associated with β cell dysfunction found in Japanese patients with type 2 diabetes. Positive association of HOMA-IR with insulinogenic index may be associated with compensatory increased insulin secretion.

Quantitative Lipidomic Analysis of Serum Phospholipids Reveals Dissociable Markers of Alzheimer's Disease and Subcortical Cerebrovascular Disease

BACKGROUND

Circulating phospholipid species have been shown to predict Alzheimer's disease (AD) prognosis but the link between phospholipid disturbances and subcortical small vessel cerebrovascular disease (CeVD) common in AD patients is not known.

OBJECTIVE

This study used quantitative lipidomics to measure serum diacyl, alkenyl (ether), alkyl, and lyso phospholipid species in individuals with extensive CeVD (n = 29), AD with minimal CeVD (n = 16), and AD with extensive CeVD (n = 14), and compared them to age-matched controls (n = 27). Memory was assessed using the California Verbal Learning Test. 3.0T MRI was used to assess hippocampal volume, atrophy, and white matter hyperintensity (WMH) volumes as manifestations of CeVD.

RESULTS

AD was associated with significantly higher concentrations of choline plasmalogen 18:0_18:1 and alkyl-phosphocholine 18:1. CeVD was associated with significantly lower lysophospholipids containing 16:0. Phospholipids containing arachidonic acid (AA) were associated with poorer memory in controls, whereas docosahexaenoic acid (DHA)-containing phospholipids were associated with better memory in individuals with AD+CeVD. In controls, DHA-containing phospholipids were associated with more atrophy and phospholipids containing linoleic acid and AA were associated with less atrophy. Lysophospholipids containing 16:0, 18:0, and 18:1 were correlated with less atrophy in controls, and of these, alkyl-phosphocholine 18:1 was correlated with smaller WMH volumes. Conversely, 16:0_18:1 choline plasmalogen was correlated with greater WMH volumes in controls.

CONCLUSION

This study demonstrates discernable differences in circulating phospholipids in individuals with AD and CeVD, as well as new associations between phospholipid species with memory and brain structure that were specific to contexts of commonly comorbid vascular and neurodegenerative pathologies.

Molecular Profiling of DNA Methylation and Alternative Splicing of Genes in Skeletal Muscle of Obese Rabbits

DNA methylation and the alternative splicing of precursor messenger RNAs (pre-mRNAs) are two important genetic modification mechanisms. However, both are currently uncharacterized in the muscle metabolism of rabbits. Thus, we constructed the Tianfu black rabbit obesity model (obese rabbits fed with a 10% high-fat diet and control rabbits from 35 days to 70 days) and collected the skeletal muscle samples from the two groups for Genome methylation sequencing and RNA sequencing. DNA methylation data showed that the promoter regions of 599 genes and gene body region of 2522 genes had significantly differential methylation rates between the two groups, of which 288 genes had differential methylation rates in promoter and gene body regions. Analysis of alternative splicing showed 555 genes involved in exon skipping (ES) patterns, and 15 genes existed in differential methylation regions. Network analysis showed that 20 hub genes were associated with ubiquitinated protein degradation, muscle development pathways, and skeletal muscle energy metabolism. Our findings suggest that the two types of genetic modification have potential regulatory effects on skeletal muscle development and provide a basis for further mechanistic studies in the rabbit.