Dynamic associations between glucose and ecological momentary cognition in Type 1 Diabetes

Type 1 diabetes (T1D) is a chronic condition characterized by glucose fluctuations. Laboratory studies suggest that cognition is reduced when glucose is very low (hypoglycemia) and very high (hyperglycemia). Until recently, technological limitations prevented researchers from understanding how naturally-occurring glucose fluctuations impact cognitive fluctuations. This study leveraged advances in continuous glucose monitoring (CGM) and cognitive ecological momentary assessment (EMA) to characterize dynamic, within-person associations between glucose and cognition in naturalistic environments. Using CGM and EMA, we obtained intensive longitudinal measurements of glucose and cognition (processing speed, sustained attention) in 200 adults with T1D. First, we used hierarchical Bayesian modeling to estimate dynamic, within-person associations between glucose and cognition. Consistent with laboratory studies, we hypothesized that cognitive performance would be reduced at low and high glucose, reflecting cognitive vulnerability to glucose fluctuations. Second, we used data-driven lasso regression to identify clinical characteristics that predicted individual differences in cognitive vulnerability to glucose fluctuations. Large glucose fluctuations were associated with slower and less accurate processing speed, although slight glucose elevations (relative to person-level means) were associated with faster processing speed. Glucose fluctuations were not related to sustained attention. Seven clinical characteristics predicted individual differences in cognitive vulnerability to glucose fluctuations: age, time in hypoglycemia, lifetime severe hypoglycemic events, microvascular complications, glucose variability, fatigue, and neck circumference. Results establish the impact of glucose on processing speed in naturalistic environments, suggest that minimizing glucose fluctuations is important for optimizing processing speed, and identify several clinical characteristics that may exacerbate cognitive vulnerability to glucose fluctuations.

Lipid-lowering therapy is not intensified beyond 3-months if coronary angiography with fractional flow reserve (FFR) suggests non-obstructive coronary disease: a missed opportunity for prevention?

Background/Introduction

Patients with non-obstructive CAD are at risk for future ASCVD events. Coronary angiography with FFR distinguishes obstructive from non-obstructive CAD, however, it is unknown how FFR assessment impacts subsequent lipid management in obstructive vs non-obstructive CAD.

Purpose

Examine patterns in intensification of lipid-lowering therapy after FFR assessment in those with obstructive vs non-obstructive CAD.

Methods

Records were reviewed from patients at a single institution who underwent FFR, instantaneous wave free ratio (iFR), or computed tomographic (CT)-FFR assessment between 2013–2020. Obstructive CAD was defined as presence of ≥1 lesion with FFR ≤0.8, iFR ≤0.89, or CT-FFR ≤0.8, or presence of obstructive CAD by visual assessment. The impact of obstructive vs non-obstructive CAD on the management of atherogenic lipids (LDL-C and non-HDL-C) after FFR was examined at 3, 6, and 12 months using Mann-Whitney U test.

Results

461 patients had obstructive CAD vs 338 with non-obstructive CAD. Most FFR, iFR, or CT-FFR assessments were performed for a non-ACS indication (n=628 (79%)). Mean (±SD) age was 66±11 yrs, with 248 (31%) women, and 658 (82%) white. Baseline LDL-C was similar in both groups: 2.2±1.1 mmol/L (obstructive CAD) and 2.1±0.9 mmol/L (non-obstructive CAD). Both groups had high baseline statin use (n=349 (76%) (obstructive CAD) vs n=241 (71%) (non-obstructive CAD)). At 3 months, mean LDL-C and non-HDL-C decreased in both those with obstructive (LDL-C −0.4 mmol/L, non-HDL-C −0.4 mmol/L) and non-obstructive CAD (LDL-C −0.3 mmol/L, non-HDL-C −0.4 mmol/L) (p>0.05), with a similar number of new statins initiated in each group. However, at 6 months, LDL-C and non-HDL-C increased in those with non-obstructive CAD (LDL-C +0.2 mmol/L, non-HDL-C +0.4 mmol/L), while atherogenic lipids further decreased in those with obstructive CAD (LDL-C −0.1 mmol/L (p=0.011), non-HDL-C −0.1 mmol/L (p=0.048)). Compared to non-obstructive CAD, there were more statins initiated by 6 months in those with obstructive CAD, although not statistically significant. At 12 months, LDL-C remained significantly lower in those with obstructive CAD compared to those with non-obstructive CAD (Figure, Table).

Conclusions

FFR assessment appears to prompt short-term intensification of lipid-lowering therapy in both those with obstructive and non-obstructive CAD (i.e. over 3 months), but this favorable effect on atherogenic lipids is lost in those with non-obstructive CAD by 6 and 12 months. Those with non-obstructive CAD are likely to benefit from long-term intensification of atherogenic lipid-lowering therapy to prevent ASCVD events, and therefore efforts should be made to maintain intensification of lipid-lowering therapy beyond 3 months in all patients undergoing FFR assessment.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Amgen Investigator Initiated Study

Intramolecular binding of a proximal PPII helix to an SH3 domain in the fusion protein SH3Hck : PPIIhGAP

SH3 domains are a conserved feature of many nonreceptor protein tyrosine kinases, such as Hck, and often function in substrate recruitment and regulation of kinase activity. SH3 domains modulate kinase activity by binding to polyproline helices (PPII helix) either intramolecularly or in target proteins. The preponderance of bimolecular and distal interactions between SH3 domains and PPII helices led us to investigate whether proximal placement of a PPII helix relative to an SH3 domain would result in tight, intramolecular binding. We have fused the PPII helix region of human GAP to the C-terminus of Hck SH3 and expressed the recombinant fusion protein in Escherichia coli. The fusion protein, SH3Hck : PPIIhGAP, folded spontaneously into a structure in which the PPII helix was bound intramolecularly to the hydrophobic crevice of the SH3 domain. The SH3Hck : PPIIhGAP fusion protein is useful for investigating SH3: PPII helix interactions, for studying concepts in protein folding and design, and may represent a protein structural motif that is widely distributed in nature.