Hyperpolarization-Activated Cation Channels Shape the Spiking Frequency Preference of Human Cortical Layer 5 Pyramidal Neurons.

Discerning the contribution of specific ionic currents to complex neuronal dynamics is a difficult, but important, task. This challenge is exacerbated in the human setting, although the widely characterized uniqueness of the human brain compared with preclinical models necessitates the direct study of human neurons. Neuronal spiking frequency preference is of particular interest given its role in rhythm generation and signal transmission in cortical circuits. Here, we combine the frequency-dependent gain (FDG), a measure of spiking frequency preference, and novel in silico analyses to dissect the contributions of individual ionic currents to the suprathreshold features of human layer 5 (L5) neurons captured by the FDG. We confirm that a contemporary model of such a neuron, primarily constrained to capture subthreshold activity driven by the hyperpolarization-activated cyclic nucleotide gated (h-) current, replicates key features of the in vitro FDG both with and without h-current activity. With the model confirmed as a viable approximation of the biophysical features of interest, we applied new analysis techniques to quantify the activity of each modeled ionic current in the moments before spiking, revealing unique dynamics of the h-current. These findings motivated patch-clamp recordings in analogous rodent neurons to characterize their FDG, which confirmed that a biophysically detailed model of these neurons captures key interspecies differences in the FDG. These differences are correlated with distinct contributions of the h-current to neuronal activity. Together, this interdisciplinary and multispecies study provides new insights directly relating the dynamics of the h-current to suprathreshold spiking frequency preference in human L5 neurons.

Risk factors for cardiovascular disease in heterozygous familial hypercholesterolemia: A systematic review and meta-analysis.

BACKGROUND: Current data from individual studies present conflicting evidence about the relationship between risk factors and cardiovascular disease (CVD) in heterozygous familial hypercholesterolemia (FH). OBJECTIVES: We conducted a systematic review and meta-analysis to quantify the association between various CVD risk factors and CVD in FH. METHODS: We searched MEDLINE, EMBASE, Global Health, the Cochrane Library, and PubMed for English-language studies reporting adjusted-associations between cardiovascular, behavioral, or clinical risk factors and CVD with ≥ 100 participants. We calculated pooled odds ratios (ORs) with 95% confidence intervals (CIs) for selected risk factors with random-effects meta-analysis, from which we derived attributable risk estimates. RESULTS: We identified 27 studies representing 41,831 unique participants and 6629 CVD events. Age (OR: 1.07; 95% CI: 1.03, 1.10), male sex (OR: 1.95; 95% CI: 1.68, 2.23), hypertension (OR: 2.11; 95% CI: 1.64, 2.58), diabetes (OR: 1.95; 95% CI: 1.33, 2.57), body mass index (OR: 1.04; 95% CI: 1.03, 1.05), smoking (OR: 1.71; 95% CI: 1.30, 2.12), elevated lipoprotein(a) (OR: 1.90; 95% CI: 1.10, 2.71), low high-density lipoprotein cholesterol (OR: 1.39; 95% CI: 1.24, 1.53), and a family history of CVD (OR: 1.83, 95% CI: 1.58, 2.07) were found to be significant CVD risk factors in FH. Smoking, hypertension, and diabetes accounted for more than a quarter of CVD risk in FH individuals, whereas low-density lipoprotein cholesterol > 4.0 mmol/L accounted for 1 in 3 CVD cases. Meta-regression analyses found associations between low-density lipoprotein cholesterol (P = .045) and total cholesterol (P < .001) and CVD. Results were broadly consistent in sensitivity analyses. CONCLUSION: Several clinical risk factors are significantly and independently associated with CVD risk in patients with FH and should be targeted for modification. These data can also inform the selection of variables for prediction models to aid in risk stratifying patients.

Anxiety, depression, and health-related quality of life in heterozygous familial hypercholesterolemia: A systematic review and meta-analysis.

BACKGROUND: Heterozygous familial hypercholesterolemia (FH) is a common genetic disease predisposing affected individuals to a high risk of cardiovascular disease. Yet, considerable uncertainty exists regarding its impact on psychosocial wellbeing. OBJECTIVES: We performed a systematic review and meta-analysis of the association between FH and symptoms of anxiety and depression, and health-related quality of life (HRQL). METHODS: We searched MEDLINE, EMBASE, Global Health, the Cochrane Library, PsycINFO, and PubMed for peer-reviewed literature published in English between January 1, 1990 and January 1, 2018. Quantitative and qualitative studies were eligible if they included patients with confirmed FH and evaluated its association with symptoms of anxiety or depression, or HRQL. We performed a narrative synthesis of studies, including thematic analysis of qualitative studies, and where data permitted, random-effects meta-analysis reporting standardized mean differences (SMD) and 95% confidence intervals. RESULTS: We found 10 eligible studies measuring HRQL, depression and anxiety. Random-effects meta-analysis of 4 (n = 4293) and 5 studies (n = 5098), respectively, showed that patients with FH had slightly lower symptoms of anxiety (SMD: -0.29 [95% CI: -0.53, -0.04]) and mental HRQL (SMD: -0.10 [95% -0.20, -0.00]) relative to general population controls. No significant differences existed in depressive symptoms (SMD: 0.04 [95% CI: -0.12, 0.19]) or physical HRQL scores (SMD: 0.02 [95% CI: -0.09, 0.12]). CONCLUSIONS: Our systematic review suggests that patients with FH may report small but measurable differences in anxiety symptoms and mental HRQL.