Urinary Hypoxanthine as a Measure of Increased ATP Utilization in Late Preterm Infants

Biochemical Profiling of Urine Metabolome in Premature Infants Based on LC-MS Considering Maternal Influence

In this study, Liquid Chromatography-Mass Spectrometry (LC-MS)-based metabolomics profiling was conducted to elucidate the urinary profiles of premature infants during early and late postnatal stages. As a result, we discovered significant excretion of maternal drugs in early-stage infants and identified crucial metabolites like hormones and amino acids. These findings shed light on the maternal impact on neonatal metabolism and underscore the beneficial effects of breastfeeding on the metabolism of essential amino acids in infants. This research not only enhances our understanding of maternal-infant nutritional interactions and their long-term implications for preterm infants but also offers critical insights into the biochemical characteristics and physiological mechanisms of preterm infants, laying a groundwork for future clinical studies focused on neonatal development and health.

A pilot study on the biochemical effects of repeated administration of 24% oral sucrose vs. 30% oral dextrose on urinary markers of adenosine triphosphate degradation

OBJECTIVES

Premature neonates often receive oral sucrose or dextrose before tissue-damaging procedures (TDPs). Previous work showed that a single dose of sucrose, but not dextrose, increased cellular energy utilization and ATP degradation. This pilot study probes the effects of repeated administration of sucrose or dextrose on energy metabolism.

METHODS

Urinary markers of ATP metabolism (hypoxanthine, xanthine, uric acid) are measured in premature neonates randomized to receive: (a) standard of care, (b) 0.2 ml 24% oral sucrose, or (c) 0.2 ml 30% oral dextrose, before every painful procedure on days-of-life 3-7.

RESULTS

Standard of care is associated with highest xanthine/creatinine and uric acid/creatinine, likely because of fewer pain treatments. Benefits of repeated oral sucrose are unclear. Neonates receiving oral dextrose had lower xanthine/creatinine and uric acid/creatinine.

CONCLUSIONS

Repeated treatments of neonatal procedural pain with 30% oral dextrose are less energetically demanding. Larger clinical studies are needed for comparison with sucrose treatments.

Oxidative stress biomarkers in the preterm infant

Oxidative stress (OS) plays a key role in the pathophysiology of preterm infants. Accurate assessment of OS remains an analytical challenge that has been partially addressed during the last few decades. A plethora of approaches have been developed to assess preterm biofluids to demonstrate a link postnatally with preterm OS, giving rise to a set of widely employed biomarkers. However, the vast number of different analytic methods and lack of standardization hampers reliable comparison of OS-related biomarkers. In this chapter, we discuss approaches for the study of OS in prematurity with respect to methodologic considerations, the metabolic source of different biomarkers and their role in clinical studies.

Oxidative Stress Biomarker Decreased in Preterm Neonates Treated With Kangaroo Mother Care

OBJECTIVE

Due to physiological and metabolic immaturity, prematurely born infants are at increased risk because of maternal separation in many neonatal intensive care units (NICUs). The stress induced from maternal-infant separation can lead to well-documented short-term physiologic instability and potentially lifelong neurological, sociological, or psychological sequelae. Based on previous studies of kangaroo mother care (KMC) that demonstrated improvement in physiologic parameters, we examined the impact of KMC on physiologic measures of stress (abdominal temperature, heart rate, oxygen saturation, perfusion index, near-infrared spectrometry), oxidative stress, and energy utilization/conservation in preterm infants.

METHODS

In this randomized, stratified study of premature neonates, we compared the effects on urinary concentrations of biomarkers of energy utilization and oxidative stress of 1 hr of KMC versus incubator care on Day 3 of life in intervention-group babies (n = 26) and control-group babies (n = 25), respectively. On Day 4, both groups received 1 hr of KMC. Urinary samples were collected 3 hr before and 3 hr after intervention/incubator care on both days. Energy utilization was assessed by measures of adenosine triphosphate (ATP) degradation (i.e., hypoxanthine, xanthine, and uric acid). Oxidative stress was assessed using urinary allantoin. Mixed-models analysis was used to assess differences in purine/allantoin.

RESULTS

Mean allantoin levels over Days 3 and 4 were significantly lower in the KMC group than in the control group (p = .026).

CONCLUSIONS

Results provide preliminary evidence that KMC reduces neonatal oxidative stress processes and that urinary allantoin could serve as an effective noninvasive marker for future studies.

Mechanistic inferences on metabolic dysfunction in posttraumatic stress disorder from an integrated model and multiomic analysis: role of glucocorticoid receptor sensitivity

Posttraumatic stress disorder (PTSD) is associated with neuroendocrine alterations and metabolic abnormalities; however, how metabolism is affected by neuroendocrine disturbances is unclear. The data from combat-exposed veterans with PTSD show increased glycolysis to lactate flux, reduced TCA cycle flux, impaired amino acid and lipid metabolism, insulin resistance, inflammation, and hypersensitive hypothalamic-pituitary-adrenal (HPA) axis. To analyze whether the co-occurrence of multiple metabolic abnormalities is independent or arises from an underlying regulatory defect, we employed a systems biological approach using an integrated mathematical model and multiomic analysis. The models for hepatic metabolism, HPA axis, inflammation, and regulatory signaling were integrated to perform metabolic control analysis (MCA) with respect to the observations from our clinical data. We combined the metabolomics, neuroendocrine, clinical laboratory, and cytokine data from combat-exposed veterans with and without PTSD to characterize the differences in regulatory effects. MCA revealed mechanistic association of the HPA axis and inflammation with metabolic dysfunction consistent with PTSD. This was supported by the data using correlational and causal analysis that revealed significant associations between cortisol suppression, high-sensitivity C-reactive protein, homeostatic model assessment of insulin resistance, γ-glutamyltransferase, hypoxanthine, and several metabolites. Causal mediation analysis indicates that the effects of enhanced glucocorticoid receptor sensitivity (GRS) on glycolytic pathway, gluconeogenic and branched-chain amino acids, triglycerides, and hepatic function are jointly mediated by inflammation, insulin resistance, oxidative stress, and energy deficit. Our analysis suggests that the interventions to normalize GRS and inflammation may help to manage features of metabolic dysfunction in PTSD.

Metabolomic studies as a tool for determining the post-mortem interval (PMI) in stillborn calves

Background

Perinatal mortality may vary between herds, but the cost of deaths are always higher than value of the calf. When diagnosing the cause of a calf’s death it is important to determine when it occurred, before or after calving. Metabolomics is widely used to identify many human diseases, but quite rarely applied in veterinary science. The aim of this study was to compare the metabolic profiles of calves with different times of death and those of calves born alive. Into the study, twenty one healthy controls (singleton, normal assisted calving, born alive) and 75 stillborn (SB) calves (with a gestation length of ≥260 days, SB, or dead within 6 h of birth) were enrolled. Plasma and urine from SB and control calves were investigated by proton nuclear magnetic resonance based metabolomic methods. SB calves were divided into four PMI groups. One PMI group included calves that died after calving and the other groups - three comprised in utero deaths, based on pathophysiological changes (lung inflation, autolysis in internal organs, hemoglobin imbibition in the pleura and aortic arch). Partial Least Squares - Discriminant Analysis models based on plasma metabolites were calculated, reflecting assumed data clustering.

Results

Twenty six metabolites in plasma and 29 in urine changed significantly with PMI according to one way analysis of variance. Half the metabolites in plasma and the majority in urine increased with PMI. Six metabolites increased simultaneously in plasma and urine: acetate, sn-glycero-3-phosphocholine (GPC), leucine, valine, creatine, and alanine.

Conclusions

Post-mortem changes in calves were associated with molecular variations in blood plasma and urine, showing the greatest differences for the group in which the post-mortem pathological changes were the most advanced. The results of the study show that evaluation of calf plasma or urine may be used as a diagnostic method for the determination of the PMI. Moreover, the metabolites, which unambiguously increased or decreased, can be used as potential biomarkers of PMI.

Electronic supplementary material

The online version of this article (10.1186/s12917-019-1935-4) contains supplementary material, which is available to authorized users.

Continuous pulse oximetry and respiratory rate trends predict short-term respiratory and growth outcomes in premature infants

BACKGROUND

To examine the correlation between interval vital signs recorded by nursing staff and continuous monitor recordings, and to determine whether aggregated monitor recordings can better predict impending escalation of respiratory support in premature infants.

METHOD

Preterm infants on noninvasive respiratory support or room air (RA) were prospectively enrolled. Nursing-and monitor-recorded pulse oximetry (SpO2) and respiratory rates (RR) data were recorded daily.

RESULTS

Ninety four infants were recruited with median gestational age of 32 weeks and birth weight of 1848 g. > 3 × 10⁶ data points were analyzed over 2204 patient days. Median events/day recorded was 8 (nursing) and 1424 (monitor) per infant. We did not find a strong correlation between monitor- and nursing events of tachypnea (RR > 70) and hypoxia (SpO2 < 90%). Infants with monitor-recorded hypoxia for > 5%/day (p < 0.0001) or tachypnea for > 30%/day (p < 0.0001) were more likely to require an increase in respiratory support within next 3 days. Monitor-recorded hypoxia and tachypnea were also associated with poor weight gain.

CONCLUSIONS

Monitor-recorded trends for tachypnea and oxygen saturations < 90% were able to predict short-term respiratory outcomes, and were associated with growth outcomes. This study emphasizes the potential for monitor-recorded data to augment clinical decision making at the bedside.

The Energy Costs of Prematurity and the Neonatal Intensive Care Unit (NICU) Experience

Premature neonates are in an energy deficient state due to (1) oxygen desaturation and hypoxia events, (2) painful and stressful stimuli, (3) illness, and (4) neurodevelopmental energy requirements. Failure to correct energy deficiency in premature infants may lead to adverse effects such as neurodevelopmental delay and negative long-term metabolic and cardiovascular outcomes. The effects of energy dysregulation and the challenges that clinicians in the Neonatal Intensive Care Unit (NICU) face in meeting the premature infant's metabolic demands are discussed. Specifically, the focus is on the effects of pain and stress on energy homeostasis. Energy deficiency is a complex problem and requires a multi-faceted solution to promote optimum development of premature infants.