Weight a minute: The smaller and more immature, the more predictable the autonomic regulation?

AIM: To investigate the relation between autonomic regulation, measured using heart rate variability (HRV), body weight and degree of prematurity in infants. Further to assess utility to include body weight in a machine learning-based sepsis prediction algorithm. METHODS: Longitudinal cohort study including 378 infants hospitalised in two neonatal intensive care units. Continuous vital sign data collection was performed prospectively from the time of NICU admission to discharge. Clinically relevant events were annotated retrospectively. HRV described using sample entropy of inter-beat intervals and assessed for its correlation with body weight measurements and age. Weight values were then added to a machine learning-based algorithm for neonatal sepsis detection. RESULTS: Sample entropy showed a positive correlation with increasing body weight and postconceptual age. Very low birth weight infants exhibited significantly lower HRV compared to infants with a birth weight >1500 g. This persisted when reaching similar weight and at the same postconceptual age. Adding body weight measures improved the algorithm's ability to predict sepsis in the overall population. CONCLUSION: We revealed a positive correlation of HRV with increasing body weight and maturation in infants. Restricted HRV, proven helpful in detecting acute events such as neonatal sepsis, might reflect prolonged impaired development of autonomic control.

Vital sign-based detection of sepsis in neonates using machine learning.

AIM: Sepsis is a leading cause of morbidity and mortality in neonates. Early diagnosis is key but difficult due to non-specific signs. We investigate the predictive value of machine learning-assisted analysis of non-invasive, high frequency monitoring data and demographic factors to detect neonatal sepsis. METHODS: Single centre study, including a representative cohort of 325 infants (2866 hospitalisation days). Personalised event timelines including interventions and clinical findings were generated. Time-domain features from heart rate, respiratory rate and oxygen saturation values were calculated and demographic factors included. Sepsis prediction was performed using Naïve Bayes algorithm in a maximum a posteriori framework up to 24 h before clinical sepsis suspicion. RESULTS: Twenty sepsis cases were identified. Combining multiple vital signs improved algorithm performance compared to heart rate characteristics alone. This enabled a prediction of sepsis with an area under the receiver operating characteristics curve of 0.82, up to 24 h before clinical sepsis suspicion. Moreover, 10 h prior to clinical suspicion, the risk of sepsis increased 150-fold. CONCLUSION: The present algorithm using non-invasive patient data provides useful predictive value for neonatal sepsis detection. Machine learning-assisted algorithms are promising novel methods that could help individualise patient care and reduce morbidity and mortality.

Auxilin is a novel susceptibility gene for congenital heart block which directly impacts fetal heart function.

OBJECTIVE: Neonatal lupus erythematosus (NLE) may develop after transplacental transfer of maternal autoantibodies with cardiac manifestations (congenital heart block, CHB) including atrioventricular block, atrial and ventricular arrhythmias, and cardiomyopathies. The association with anti-Ro/SSA antibodies is well established, but a recurrence rate of only 12%-16% despite persisting maternal autoantibodies suggests that additional factors are required for CHB development. Here, we identify fetal genetic variants conferring risk of CHB and elucidate their effects on cardiac function. METHODS: A genome-wide association study was performed in families with at least one case of CHB. Gene expression was analysed by microarrays, RNA sequencing and PCR and protein expression by western blot, immunohistochemistry, immunofluorescence and flow cytometry. Calcium regulation and connectivity were analysed in primary cardiomyocytes and cells induced from pleuripotent stem cells. Fetal heart performance was analysed by Doppler/echocardiography. RESULTS: We identified DNAJC6 as a novel fetal susceptibility gene, with decreased cardiac expression of DNAJC6 associated with the disease risk genotype. We further demonstrate that fetal cardiomyocytes deficient in auxilin, the protein encoded by DNAJC6, have abnormal connectivity and Ca2+ homoeostasis in culture, as well as decreased cell surface expression of the Cav1.3 calcium channel. Doppler echocardiography of auxilin-deficient fetal mice revealed cardiac NLE abnormalities in utero, including abnormal heart rhythm with atrial and ventricular ectopias, as well as a prolonged atrioventricular time intervals. CONCLUSIONS: Our study identifies auxilin as the first genetic susceptibility factor in NLE modulating cardiac function, opening new avenues for the development of screening and therapeutic strategies in CHB.

Neonatal sepsis prediction through clinical decision support algorithms: A systematic review.

AIM: To systematically summarise the current evidence of employing clinical decision support algorithms (CDSAs) using non-invasive parameters for sepsis prediction in neonates. METHODS: A comprehensive search in PubMed, CENTRAL and EMBASE was conducted. Screening, data extraction and risk of bias were performed by two authors. The certainty of the evidence was assessed using GRADE. PROSPERO ID: CRD42020205143. RESULTS: After abstract and full-text screening, 36 studies comprising 18,096 infants were included. Most CDSAs evaluated heart rate (HR)-based parameters. Two publications derived from one randomised-controlled trial assessing HR characteristics reported significant reduction in 30-day septicaemia-related mortality. Thirty-four non-randomised studies found promising yet inconclusive results. CONCLUSION: Heart rate-based parameters are reliable components of CDSAs for sepsis prediction, particularly in combination with additional vital signs and demographics. However, inconclusive evidence and limited standardisation restricts clinical implementation of CDSAs outside of a controlled research environment. Further experimentation and comparison of parameter combinations and testing of new CDSAs are warranted.

Astrocyte networks modulate respiration - sniffing glue.

The role of astrocytes in the modulation of breathing has emerged. Within the two major respiratory control centers, the inspiration generating preBötzinger Complex and the chemosensitive parafacial respiratory group/retrotrapezoid nucleus, rhythmically active astrocytes have been discovered. These are connected in glial subnetworks that intermingle with the neuronal network. Furthermore, astrocytes modify overall respiratory network behavior through gliotransmitter release, especially during hypoxic and hypercapnic stress. Here, we review some recent discoveries regarding astrocyte-neuronal interactions on a cellular as well as neural network level including the novel gliotransmitter PGE2.

Astrocytes release prostaglandin E2 to modify respiratory network activity.

Previously (Forsberg et al., 2016), we revealed that prostaglandin E2 (PGE2), released during hypercapnic challenge, increases calcium oscillations in the chemosensitive parafacial respiratory group (pFRG/RTN). Here, we demonstrate that pFRG/RTN astrocytes are the PGE2 source. Two distinct astrocyte subtypes were found using transgenic mice expressing GFP and MrgA1 receptors in astrocytes. Although most astrocytes appeared dormant during time-lapse calcium imaging, a subgroup displayed persistent, rhythmic oscillating calcium activity. These active astrocytes formed a subnetwork within the respiratory network distinct from the neuronal network. Activation of exogenous MrgA1Rs expressed in astrocytes tripled astrocytic calcium oscillation frequency in both the preBötzinger complex and pFRG/RTN. However, neurons in the preBötC were unaffected, whereas neuronal calcium oscillatory frequency in pFRG/RTN doubled. Notably, astrocyte activation in pFRG/RTN triggered local PGE2 release and blunted the hypercapnic response. Thus, astrocytes play an active role in respiratory rhythm modulation, modifying respiratory-related behavior through PGE2 release in the pFRG/RTN.

Functional Stem Cell Integration into Neural Networks Assessed by Organotypic Slice Cultures.

Re-formation or preservation of functional, electrically active neural networks has been proffered as one of the goals of stem cell-mediated neural therapeutics. A primary issue for a cell therapy approach is the formation of functional contacts between the implanted cells and the host tissue. Therefore, it is of fundamental interest to establish protocols that allow us to delineate a detailed time course of grafted stem cell survival, migration, differentiation, integration, and functional interaction with the host. One option for in vitro studies is to examine the integration of exogenous stem cells into an existing active neural network in ex vivo organotypic cultures. Organotypic cultures leave the structural integrity essentially intact while still allowing the microenvironment to be carefully controlled. This allows detailed studies over time of cellular responses and cell-cell interactions, which are not readily performed in vivo. This unit describes procedures for using organotypic slice cultures as ex vivo model systems for studying neural stem cell and embryonic stem cell engraftment and communication with CNS host tissue. © 2017 by John Wiley & Sons, Inc.

Rho-associated kinase is a therapeutic target in neuroblastoma.

Neuroblastoma is a peripheral neural system tumor that originates from the neural crest and is the most common and deadly tumor of infancy. Here we show that neuroblastoma harbors frequent mutations of genes controlling the Rac/Rho signaling cascade important for proper migration and differentiation of neural crest cells during neuritogenesis. RhoA is activated in tumors from neuroblastoma patients, and elevated expression of Rho-associated kinase (ROCK)2 is associated with poor patient survival. Pharmacological or genetic inhibition of ROCK1 and 2, key molecules in Rho signaling, resulted in neuroblastoma cell differentiation and inhibition of neuroblastoma cell growth, migration, and invasion. Molecularly, ROCK inhibition induced glycogen synthase kinase 3ß-dependent phosphorylation and degradation of MYCN protein. Small-molecule inhibition of ROCK suppressed MYCN-driven neuroblastoma growth in TH-MYCN homozygous transgenic mice and MYCN gene-amplified neuroblastoma xenograft growth in nude mice. Interference with Rho/Rac signaling might offer therapeutic perspectives for high-risk neuroblastoma.

CO2-evoked release of PGE2 modulates sighs and inspiration as demonstrated in brainstem organotypic culture.

Inflammation-induced release of prostaglandin E2 (PGE2) changes breathing patterns and the response to CO2 levels. This may have fatal consequences in newborn babies and result in sudden infant death. To elucidate the underlying mechanisms, we present a novel breathing brainstem organotypic culture that generates rhythmic neural network and motor activity for 3 weeks. We show that increased CO2 elicits a gap junction-dependent release of PGE2. This alters neural network activity in the preBötzinger rhythm-generating complex and in the chemosensitive brainstem respiratory regions, thereby increasing sigh frequency and the depth of inspiration. We used mice lacking eicosanoid prostanoid 3 receptors (EP3R), breathing brainstem organotypic slices and optogenetic inhibition of EP3R(+/+) cells to demonstrate that the EP3R is important for the ventilatory response to hypercapnia. Our study identifies a novel pathway linking the inflammatory and respiratory systems, with implications for inspiration and sighs throughout life, and the ability to autoresuscitate when breathing fails.

AngioSuite: an accurate method to calculate aneurysm volumes and packing densities.

OBJECTIVE: AngioSuite was developed to allow the easy and accurate calculation of cerebral aneurysm volumes and packing densities. The present study was undertaken to validate its accuracy. METHODS: Mathematical models and software were created to facilitate more complex aneurysm volume calculations than previously described three-dimensional geometric models. 20 phantom aneurysm clay models were created and analyzed (length, width, depth and volume) using angiographic mathematical modeling (AngioSuite), geometric modeling (AngioCalc) and three-dimensional volume reconstructions from the vendor's Leonardo workstation (Siemens). RESULTS: The mean volumes of all phantoms analyzed by the AngioSuite system differed from true volumes by an average of 2.2%. Mean volumes of all phantoms analyzed by the AngioCalc system differed from true volumes by an average of 11.3%. Mean volumes obtained from the Leonardo workstation windowed for best appearance differed by an average of 5.18%. CONCLUSIONS: The AngioSuite software system provides an accurate means of calculating aneurysm volumes. Typical packing densities (40% or less) are thus accurate within ±1%. Angiographic mathematical modeling with AngioSuite is more accurate than geometric modeling and three-dimensional volume reconstructions windowed for best appearance (Leonardo).

Functional stem cell integration assessed by organotypic slice cultures.

Re-formation or preservation of functional, electrically active neural networks has been proffered as one of the goals of stem cell-mediated neural therapeutics. A primary issue for a cell therapy approach is the formation of functional contacts between the implanted cells and the host tissue. Therefore, it is of fundamental interest to establish protocols that allow us to delineate a detailed time course of grafted stem cell survival, migration, differentiation, integration, and functional interaction with the host. One option for in vitro studies is to examine the integration of exogenous stem cells into an existing active neuronal network in ex vivo organotypic cultures. Organotypic cultures leave the structural integrity essentially intact while still allowing the microenvironment to be carefully controlled. This allows detailed studies over time of cellular responses and cell-cell interactions, which are not readily performed in vivo. This unit describes procedures for using organotypic slice cultures as ex vivo model systems for studying neural stem cell and embryonic stem cell engraftment and communication with CNS host tissue.