Causal inference in medical records and complementary systems pharmacology for metformin drug repurposing towards dementia.

Metformin, a diabetes drug with anti-aging cellular responses, has complex actions that may alter dementia onset. Mixed results are emerging from prior observational studies. To address this complexity, we deploy a causal inference approach accounting for the competing risk of death in emulated clinical trials using two distinct electronic health record systems. In intention-to-treat analyses, metformin use associates with lower hazard of all-cause mortality and lower cause-specific hazard of dementia onset, after accounting for prolonged survival, relative to sulfonylureas. In parallel systems pharmacology studies, the expression of two AD-related proteins, APOE and SPP1, was suppressed by pharmacologic concentrations of metformin in differentiated human neural cells, relative to a sulfonylurea. Together, our findings suggest that metformin might reduce the risk of dementia in diabetes patients through mechanisms beyond glycemic control, and that SPP1 is a candidate biomarker for metformin's action in the brain.

Clinical outcomes of severe COVID-19 patients receiving early VV-ECMO and the impact of pre-ECMO ventilator use.

Acute respiratory distress syndrome (ARDS) in COVID-19 patients is associated with poor clinical outcomes and high mortality rates, despite the use of mechanical ventilation. Veno-Venous Extracorporeal membrane Oxygenation (VV-ECMO) in these patients is a viable salvage therapy. We describe clinical outcomes and survival rates in 52 COVID-19 patients with ARDS treated with early VV-ECMO at a large, high-volume center ECMO program. Outcomes included arterial blood gases, respiratory parameters, inflammatory markers, adverse events, and survival rates. Patients' mean age was 47.8 ± 12.1 years, 33% were female, and 75% were Hispanic. At the end of study period, 56% (n = 29) of the patients survived and were discharged and 44% (n = 23) of the patients expired. Survival rate was 75.0% (9 out of 12) in patients placed on ECMO prior to mechanical ventilation. Longer duration on mechanical ventilation prior to ECMO intervention was associated with a 31% (aOR = 1.31, 95% CI, 1.00-1.70) increased odds of mortality after adjusting for age, gender, BMI, number of comorbid conditions, and post-ECMO ventilator days. Early and effective ECMO intervention in critical ill COVID-19 patients might be a valuable strategy in critical care settings to increase their odds of survival.

Machine learning identifies candidates for drug repurposing in Alzheimer's disease.

Clinical trials of novel therapeutics for Alzheimer's Disease (AD) have consumed a large amount of time and resources with largely negative results. Repurposing drugs already approved by the Food and Drug Administration (FDA) for another indication is a more rapid and less expensive option. We present DRIAD (Drug Repurposing In AD), a machine learning framework that quantifies potential associations between the pathology of AD severity (the Braak stage) and molecular mechanisms as encoded in lists of gene names. DRIAD is applied to lists of genes arising from perturbations in differentiated human neural cell cultures by 80 FDA-approved and clinically tested drugs, producing a ranked list of possible repurposing candidates. Top-scoring drugs are inspected for common trends among their targets. We propose that the DRIAD method can be used to nominate drugs that, after additional validation and identification of relevant pharmacodynamic biomarker(s), could be readily evaluated in a clinical trial.

Comparison of long-acting and oral antipsychotic treatment effects in patients with schizophrenia, comorbid substance abuse, and a history of recent incarceration: An exploratory analysis of the PRIDE study.

INTRODUCTION: Comorbid substance abuse is known to blunt response to treatment for underlying psychiatric disorders, but it has not been investigated in schizophrenia when comparing the effects of long-acting injectable antipsychotics with those of oral antipsychotics. METHODS: This exploratory analysis compared once-monthly paliperidone palmitate (PP1M) with daily oral antipsychotics on time to treatment failure in patients with schizophrenia and a history of incarceration. Subjects were stratified into substance abuse (reported substance or alcohol misuse in the past 30days on the baseline Addiction Severity Index-Lite Version and/or met criteria for a current MINI diagnosis of a substance abuse disorder) and nonabuse cohorts. RESULTS: In the substance abuse cohort, treatment failure was observed in 56.2% (73/130) and 64.2% (86/134) of subjects in the PP1M and oral antipsychotic groups, respectively. For the nonabuse cohort, treatment failure was observed in 36.5% (35/96) and 53.6% (45/84) of subjects in the PP1M and oral antipsychotic groups, respectively. Median (95% confidence interval [CI]) time to first treatment failure was 291 (179-428) days and 186 (94-296) days in the PP1M and oral antipsychotic groups, respectively. Median (95% CI) time to first treatment failure was >450 and 284 (147 to >450) days in the respective treatment groups. CONCLUSION: Greater treatment effects were evident with PP1M compared with oral antipsychotics in both cohorts. The observed beneficial effect of PP1M was attenuated in the substance-abuse cohort, further reinforcing both the need for and value of continued research to optimize patient care in these complex patient populations.

Aß alters the connectivity of olfactory neurons in the absence of amyloid plaques in vivo.

The amyloid beta peptide aggregates into amyloid plaques at presymptomatic stages of Alzheimer's disease, but the temporal relationship between plaque formation and neuronal dysfunction is poorly understood. Here we demonstrate that the connectivity of the peripheral olfactory neural circuit is perturbed in mice overexpressing human APPsw (Swedish mutation) before the onset of plaques. Expression of human APPsw exclusively in olfactory sensory neurons also perturbs connectivity with associated reductions in odour-evoked gene expression and olfactory acuity. By contrast, olfactory sensory neuron axons project correctly in mice overexpressing wild-type human amyloid precursor protein throughout the brain and in mice overexpressing M671V human APP, a missense mutation that reduces amyloid beta production, exclusively in olfactory sensory neurons. Furthermore, expression of Aß40 or Aß42 solely in the olfactory epithelium disrupts the olfactory sensory neuron axon targeting. Our data indicate that altering the structural connectivity and function of highly plastic neural circuits is one of the pleiotropic actions of soluble human amyloid beta.

The precision of axon targeting of mouse olfactory sensory neurons requires the BACE1 protease.

The ß-site amyloid precursor protein cleaving enzyme 1 (BACE1) is necessary to generate the Aß peptide, which is implicated in Alzheimer's disease pathology. Studies show that the expression of BACE1 and its protease activity are tightly regulated, but the physiological function of BACE1 remains poorly understood. Recently, numerous axon guidance proteins were identified as potential substrates of BACE1. Here, we examined the consequences of loss of BACE1 function in a well-defined in vivo model system of axon guidance, mouse olfactory sensory neurons (OSNs). The BACE1 protein resides predominantly in proximal segment and the termini of OSN axons, and the expression of BACE1 inversely correlates with odor-evoked neural activity. The precision of targeting of OSN axons is disturbed in both BACE1 null and, surprisingly, in BACE1 heterozygous mice. We propose that BACE1 cleavage of axon guidance proteins is essential to maintain the connectivity of OSNs in vivo.

Notch2 is required for maintaining sustentacular cell function in the adult mouse main olfactory epithelium.

Notch receptors are expressed in neurons and glia in the adult nervous system, but why this expression persists is not well-understood. Here we examine the role of the Notch pathway in the postnatal mouse main olfactory system, and show evidence consistent with a model where Notch2 is required for maintaining sustentacular cell function. In the absence of Notch2, the laminar nature of these glial-like cells is disrupted. Hes1, Hey1, and Six1, which are downstream effectors of the Notch pathway, are down-regulated, and cytochrome P450 and Glutathione S-transferase (GST) expression by sustentacular cells is reduced. Functional levels of GST activity are also reduced. These disruptions are associated with increased olfactory sensory neuron degeneration. Surprisingly, expression of Notch3 is also down-regulated. This suggests the existence of a feedback loop where expression of Notch3 is initially independent of Notch2, but requires Notch2 for maintained expression. While the Notch pathway has previously been shown to be important for promoting gliogenesis during development, this is the first demonstration that the persistent expression of Notch receptors is required for maintaining glial function in adult.