Diagnostic value of PET imaging in clinically unresponsive patients

Rapid advancements in the critical care management of acute brain injuries have facilitated the survival of numerous patients who may have otherwise succumbed to their injuries. The probability of conscious recovery hinges on the extent of structural brain damage and the level of metabolic and functional cerebral impairment, which remain challenging to assess via laboratory, clinical, or functional tests. Current research settings and guidelines highlight the potential value of fluorodeoxyglucose-PET (FDG-PET) for diagnostic and prognostic purposes, emphasizing its capacity to consistently illustrate a metabolic reduction in cerebral glucose uptake across various disorders of consciousness. Crucially, FDG-PET might be a pivotal tool for differentiating between patients in the minimally conscious state and those in the unresponsive wakefulness syndrome, a persistent clinical challenge. In patients with disorders of consciousness, PET offers utility in evaluating the degree and spread of functional disruption, as well as identifying irreversible neural damage. Further, studies that capture responses to external stimuli can shed light on residual or revived brain functioning. Nevertheless, the validity of these findings in predicting clinical outcomes calls for additional long-term studies with larger patient cohorts suffering from consciousness impairment. Misdiagnosis of conscious illnesses during bedside clinical assessments remains a significant concern. Based on the clinical research settings, current clinical guidelines recommend PET for diagnostic and/or prognostic purposes. This review article discusses the clinical categories of conscious disorders and the diagnostic and prognostic value of PET imaging in clinically unresponsive patients, considering the known limitations of PET imaging in such contexts.

A novel small molecule inhibitor of p38⍺ MAP kinase augments cardiomyocyte cell cycle entry in response to direct cell cycle stimulation

BACKGROUND AND PURPOSE

Myocardial infarction (MI) is the leading cause of mortality globally due in part to the limited ability of cardiomyocytes (CMs) to regenerate. Recently, we demonstrated that overexpression of four-cell cycle factors, CDK1, CDK4, cyclin B1 and cyclin D1 (4F), induced cell division in ~20% of the post-mitotic CMs overexpressed 4F. The current study aims to identify a small molecule that augments 4F-induced CM cycle induction.

EXPERIMENTAL APPROACH, KEY RESULTS

Screening of small molecules with a potential to augment 4F-induced cell-cycle induction in 60-day-old mature human induced pluripotent cardiomyocytes (hiPS-CMs) revealed N-(4,6-Dimethylpyridin-2-yl)-4-(pyridine-4-yl)piperazine-1-carbothioamide (NDPPC), which activates cell cycle progression in 4F-transduced hiPS-CMs. Autodock tool and Autodock vina computational methods showed that NDPPC has a potential interaction with the binding site at the human p38⍺ mitogen-activated protein kinase (p38⍺ MAP kinase), a critical negative regulator of the mammalian cell cycle. A p38 MAP kinase activity assay showed that NDPPC inhibits p38⍺ with 5-10 times lower IC50 compared to the other P38 isoforms in a dose-dependent manner. Overexpression of p38⍺ MAP kinase in CMs inhibited 4F cell cycle induction, and treatment with NDPPC reversed the cell cycle inhibitory effect.

CONCLUSION AND IMPLICATIONS

NDPPC is a novel inhibitor for p38 MAP kinase and is a promising drug to augment CM cell cycle response to the 4F. NDPPC could become an adjunct treatment with other cell cycle activators for heart failure treatment.

A personalized classification of behavioral severity of autism spectrum disorder using a comprehensive machine learning framework

Autism Spectrum Disorder (ASD) is characterized as a neurodevelopmental disorder with a heterogeneous nature, influenced by genetics and exhibiting diverse clinical presentations. In this study, we dissect Autism Spectrum Disorder (ASD) into its behavioral components, mirroring the diagnostic process used in clinical settings. Morphological features are extracted from magnetic resonance imaging (MRI) scans, found in the publicly available dataset ABIDE II, identifying the most discriminative features that differentiate ASD within various behavioral domains. Then, each subject is categorized as having severe, moderate, or mild ASD, or typical neurodevelopment (TD), based on the behavioral domains of the Social Responsiveness Scale (SRS). Through this study, multiple artificial intelligence (AI) models are utilized for feature selection and classifying each ASD severity and behavioural group. A multivariate feature selection algorithm, investigating four different classifiers with linear and non-linear hypotheses, is applied iteratively while shuffling the training-validation subjects to find the set of cortical regions with statistically significant association with ASD. A set of six classifiers are optimized and trained on the selected set of features using 5-fold cross-validation for the purpose of severity classification for each behavioural group. Our AI-based model achieved an average accuracy of 96%, computed as the mean accuracy across the top-performing AI models for feature selection and severity classification across the different behavioral groups. The proposed AI model has the ability to accurately differentiate between the functionalities of specific brain regions, such as the left and right caudal middle frontal regions. We propose an AI-based model that dissects ASD into behavioral components. For each behavioral component, the AI-based model is capable of identifying the brain regions which are associated with ASD as well as utilizing those regions for diagnosis. The proposed system can increase the speed and accuracy of the diagnostic process and result in improved outcomes for individuals with ASD, highlighting the potential of AI in this area.

Transient gene therapy using cell cycle factors reverses renin-angiotensin-aldosterone system activation in heart failure rat model

The loss of cardiomyocytes after myocardial infarction (MI) leads to heart failure. Recently, we demonstrated that transient overexpression of 4 cell cycle factors (4F), using a polycistronic non-integrating lentivirus (TNNT2-4F-NIL) resulted in significant improvement in cardiac function in a rat model of MI. Yet, it is crucial to demonstrate the reversal of the heart failure-related pathophysiological manifestations, such as renin-angiotensin-aldosterone system activation (RAAS). To assess that, Fisher 344 rats were randomized to receive TNNT2-4F-NIL or control virus seven days after coronary occlusion for 2 h followed by reperfusion. 4 months after treatment, N-terminal pro-brain natriuretic peptide, plasma renin activity, and aldosterone levels returned to the normal levels in rats treated with TNNT2-4F-NIL but not in vehicle-treated rats. Furthermore, the TNNT2-4F-NIL-treated group showed significantly less liver and kidney congestion than vehicle-treated rats. Thus, we conclude that in rat models of MI, TNNT2-4F-NIL reverses RAAS activation and subsequent systemic congestion.

Abstract P1014: Cardiomyocyte Energetic Capacity Governs Responses To Cell Cycle Stimulation

Background: Induction of cardiomyocyte (CM) proliferation is a promising strategy for cardiac regeneration. We previously showed that the overexpression of four cell cycle factors (4F), i.e. cyclin B1, CDK1, cyclin D1 and CDK4, induces CM proliferation. Temporal profiling of the single cell transcriptomes of 4F- and LacZ-overexpressing CMs showed a specific population with higher levels of CD36 that was more responsive to the 4F cell cycle induction. In addition, P7 primary CMs isolated from CD36 KO mice demonstrated 50% less response to the 4F compared with the WT controls (Abouleisa et al., Circulation, 2022). These data indicate that CD36 may be required to prime CMs to proliferate. CD36 is known to internalize fatty acids to be utilized for energy production. Here, we aim to investigate the direct effect of CM energetic capacity on their response to cell cycle stimulation.

Methods and Results: Carnitine palmitoyl transferase -1 (CPT-1) is a rate limiting enzyme for the β-oxidation of fatty acids. Knockdown of CPT-1 using siRNA significantly reduced mitochondrial ATP production by 10% and led to a significant reduction in cell cycle markers (PHH3, EDU) in response to the 4F (PHH3; control siRNA+4F:24±1% vs CPT1 siRNA+4F:15±1%, EDU; control siRNA+4F:22±2% vs CPT1siRNA+4F:16±1%, P<0.01, n=4). Small molecule inhibition of CPT1 using etomoxir significantly decreased mitochondrial ATP production and suppressed CM responses to the 4F. Furthermore, overexpression of CPT-1 using viral vectors resulted in significant increase in ATP production and increased response to cell cycle stimulation using the 4F. Supplementing the culture medium with (1μmol) L-carnitine significantly increased mitochondrial ATP production and enhanced the CM response to the 4F. Finally, to increase ATP availability in CMs directly, we overexpressed a light-activated mitochondrial proton pump (MT-ON). CMs expressing MT-ON showed a significant increase in mitochondrial ATP levels and enhanced cell cycle induction in CMs transduced with 4F (PHH3; 4F:18±2% vs 4F+MT-ON:27±3%, EDU; 4F:18±1% vs 4F+MT-ON:30±4 %, P<0.01, n=4).

Conclusions: These findings suggest that an energy threshold is required for CMs to progress into the cell cycle.

Abstract P1029: Improving Cardiomyocyte Cell Cycle Entry In Response To Direct Cell Cycle Stimulation Using A Novel Small Molecule Inhibitor Of P38

Background: Myocardial infarction is the leading cause of mortality globally, due in part to the limited ability of cardiomyocytes (CMs) to regenerate. Recently, we showed that overexpression of a combination of 4 cell cycle factors, CDK1, CDK4, cyclin B1, and cyclin D1 (collectively known as 4F), induced cell division in ~15% of post-mitotic mouse, rat, and human CMs. The aim of the current study is to identify novel small molecules that further augment CM cycle induction caused by the 4F.

Methods and Results: We performed a drug screening of 30 chemical compounds with possible cell cycle regulatory activities using 60-day-old mature hiPS-CMs overexpressing the 4F and assessed the increase in EDU (DNA synthesis marker) and PHH3 (G2-M phase marker). The top hit was N-(4,6-Dimethylpyridin-2-yl)-4-(pyridin-4-yl)piperazine-1-carbothioamide (NDPPC). NDPPC showed a dose-dependent increase in the percentage of EDU and PHH3 positive nuclei in hiPS-CMs transduced with 4F. CMs transduced with 4F and treated with 1 μM NDPPC showed a significant increase in the percentage of EDU and PHH3 compared with vehicle (V)-treated CMs (PHH3; V: 20.41±2.02%, NDPPC: 33.75±3.9%, EDU; V: 18.24±1.7%, NDPPC: 30.81±2.1% n=6, p<0.001). In Silico Drug-Target prediction showed that NDPPC could interact with p38 mitogen-activated protein kinase (P38), a critical negative regulator of mammalian cell cycle. Therefore, we overexpressed P38, in the presence and absence of NDPPC and 4F. As expected, overexpression of P38 in CMs inhibited 4F cell cycle induction, and treatment with NDPPC reversed the cell cycle inhibitory effect (in presence of 4F PHH3%; V: 20.38±0.97%, P38 overexpression+V: 11.02±1.3%, P38 overexpression+NDPPC: 23.62±2.79, n=4, P<0.001). Knockdown of P38 showed a significant increase in the percentage of EDU and PHH3 positive nuclei in 4F treated CMs, and treatment with NDPPC did not show any further increase in cell cycle induction. These data indicate that NDPPC enhances the 4F cell cycle response in CMs through inhibition of P38.

Conclusions: NDPPC is a novel inhibitor for P38. NDPPC is a promising drug to promote CM cell cycle response to the 4F. Further work in vivo is needed to test whether NDPPC could improve the 4F effect on cardiac function after ischemic injury.