Does Whole-Body Hypothermia in Neonates with Hypoxic-Ischemic Encephalopathy Affect Surfactant Disaturated-Phosphatidylcholine Kinetics?

Tracing the lipidome in inborn errors of metabolism

Inborn errors of metabolism (IEM) represent a heterogeneous group of more than 1800 rare disorders, many of which are causing significant childhood morbidity and mortality. More than 100 IEM are linked to dyslipidaemia, but yet our knowledge in connecting genetic information with lipidomic data is limited. Stable isotope tracing studies of the lipid metabolism (STL) provide insights on the dynamic of cellular lipid processes and could thereby facilitate the delineation of underlying metabolic (patho)mechanisms. This mini-review focuses on principles as well as technical limitations of STL and describes potential clinical applications by discussing recently published STL focusing on IEM.

A novel deuterium-based model for measurement of exogenous surfactant using deuterium-depleted water

Stable isotope tracers, like ¹³ C, can be used for the measurement of the partition between the endogenous and exogenous pulmonary disaturated-phosphatidylcholine (DSPC). Deuterium labeling methods are still not fully explored. Our aim was to investigate the feasibility of using deuterium-depleted water (DDW) and deuterium-enriched water (DEW) to measure endogenous and exogenous pulmonary DSPC in a rabbit model of surfactant depletion. Data obtained from the ¹³ C dilution method were used as a reference. We studied 9 adult rabbits: 4 drank DDW and 5 DEW for 5 days. Lung surfactant depletion was induced at Day 5 by repeated saline bronchoalveolar lavages (BAL), which were stored as a pool (BAL pool). After endogenous surfactant depletion, rabbits received exogenous surfactant followed by a second BAL depletion procedure (End-Experiment Pool). DSPC quantity, and palmitic acid (PA)-DSPC ² H/¹ H (δ² H) and ¹³ C/¹² C ratios (δ¹³ C) of exogenous surfactant batches and of BAL pools were measured by High-Resolution Mass Spectrometry. The amount of exogenous surfactant recovered from the lungs ranged from 45% to 81% and, it was highly correlated with those obtained with the use of the ¹³ C (r = 0.9844, p < 0.0001). We demonstrated that commercially available purified DDW and even low doses of DEW can be used to modify the deuterium background of endogenous surfactants with the purpose of measuring the contribution of exogenous surfactants to the endogenous alveolar surfactant pool.

Severe Hypercapnia Requiring 48-h Whole-Body Hypothermia in an Infant with Acute Bronchiolitis

Bronchiolitis is a clinical syndrome involving the lower respiratory tract of infants and young children. The majority of patients recover using adequate hydration and oxygen (O2) therapy, while a small number of patients require ventilatory assistance. Beyond these therapeutical approaches, there are no available strategies for patients that do not improve. Hypothermia is a measure used to prevent neonatal hypoxic–ischemic encephalopathy by preventing carbon dioxide (CO2) production and subsequent tissue damage. Other medical applications of hypothermia have been proposed, such as in acute respiratory failure and necrotizing colitis. Case report: We report the case of a 50-day-old girl hospitalized with severe bronchiolitis caused by respiratory syncytial virus. On admission, the girl presented severe hypercapnic respiratory failure, requiring intubation and ventilatory support with conventional and non-conventional systems. However, the patient’s general conditions worsened with elevated O2 demand, thus whole-body hypothermia was attempted and performed for 48 h, with a gradual improvement in the respiratory function. No adverse effects were detected. Conclusions: Whole-body hypothermia could have a critical role as a rescue treatment in infants affected by severe hypercapnic respiratory failure, at the expense of few and rare side effects (bradycardia, coagulopathy, hyperglycemia). Notably, beyond reducing CO2 production, whole-body hypothermia might have an impact in restoring lung function in newborns using bronchiolitis refractory to maximal medical therapy and invasive ventilation.

Identification of Somatostatin Receptor Subtype 1 (SSTR1) Gene Polymorphism and Their Association with Growth Traits in Hulun Buir Sheep

This study was conducted to evaluate SSTR1 gene polymorphisms and their association with growth traits in Hulun Buir sheep. We followed 233 Hulun Buir sheep from birth to 16 months of age, born in the same pasture and on the same year under a consistent grazing conditions. The body weight (BW), body height (BH), body length (BL), chest circumference (ChC), chest depth (ChD), chest width (ChW), hip width (HW), and cannon circumference (CaC) were measured and recorded at birth, 4 months, 9 months, and 16 months of age. The polymorphisms of the SSTR1 gene in Hulun Buir sheep were excavated using exon sequencing, and association analyses of between SNPs and growth traits at each growth stage were conducted. The results showed that there were four SNPs in Exon 2 of the SSTR1 gene, SNP1, SNP2, and SNP3 were low mutation sites, and SNP4 was a moderate mutation site. Four SNPs were consistent with Hardy–Weinberg equilibrium, and all of them were synonymous mutations. The association analyses found that the genotypes of SNP2 were significantly associated with WW and BH at 4 months of age, BW, BL, ChC, and HW at 9 months of age (p < 0.05), and extremely significantly associated with ChD at 4 and 9 months of age (p < 0.01). There were significant associations between SNP3 and BH at 9 months of age, between SNP4 and ChD, ChW, and CaC at 9 months of age, and BW and ChC at 16 months of age (p < 0.05). There were no detectable associations with growth traits among the seven haplotypes between the SNP1, 3, and 4 of a strong linkage disequilibrium (p > 0.05). These results indicated that SNP2, SNP3, and SNP4 may be used as molecular markers for growth traits of Hulun Buir sheep.

Molecular and biophysical mechanisms behind the enhancement of lung surfactant function during controlled therapeutic hypothermia

Therapeutic hypothermia (TH) enhances pulmonary surfactant performance in vivo by molecular mechanisms still unknown. Here, the interfacial structure and the composition of lung surfactant films have been analysed in vitro under TH as well as the molecular basis of its improved performance both under physiological and inhibitory conditions. The biophysical activity of a purified porcine surfactant was tested under slow and breathing-like dynamics by constrained drop surfactometry (CDS) and in the captive bubble surfactometer (CBS) at both 33 and 37 °C. Additionally, the temperature-dependent surfactant activity was also analysed upon inhibition by plasma and subsequent restoration by further surfactant supplementation. Interfacial performance was correlated with lateral structure and lipid composition of films made of native surfactant. Lipid/protein mixtures designed as models to mimic different surfactant contexts were also studied. The capability of surfactant to drastically reduce surface tension was enhanced at 33 °C. Larger DPPC-enriched domains and lower percentages of less active lipids were detected in surfactant films exposed to TH-like conditions. Surfactant resistance to plasma inhibition was boosted and restoration therapies were more effective at 33 °C. This may explain the improved respiratory outcomes observed in cooled patients with acute respiratory distress syndrome and opens new opportunities in the treatment of acute lung injury.

Nanotechnology and Early Human Development

The application of nanotechnology, molecular biotechnologies, and nano-sciences for medical purposes has been termed nanomedicine, a promising growing area of medical research. The aim of this paper is to provide an overview of and discuss nanotechnology applications in the early epochs of life, from transplacental transfer to neonatal/pediatric conditions. Diagnostic and therapeutic applications, mainly related to the respiratory tract, the neurosensory system, and infections, are explored and discussed. Preclinical studies show promising results for a variety of conditions, including for the treatment of pregnancy complications and fetal, neonatal, and pediatric diseases. However, given the complexity of the functions and interactions between the placenta and the fetus, and the complex and incompletely understood determinants of tissue growth and differentiation during early life, there is a need for much more data to confirm the safety and efficacy of nanotechnology in this field.

Effect of mild hypothermia on the expression of IL-10 and IL-18 in neonates with hypoxic ischemic encephalopathy

The effect of mild hypothermia on the expression of interleukin (IL)-10 and IL-18 in neonates with hypoxic ischemic encephalopathy was investigated. A retrospective analysis was performed on 97 neonates with hypoxic-ischemic encephalopathy (HIE) admitted to the neonatal intensive care unit of Xuzhou Children's Hospital, Xuzhou Medical University from September 2016 to August 2018. Of these patients, 54 with mild hypothermia were included in the experimental group (moderate + severe), and 43 patients who received conventional therapy were included in the control group (moderate + severe). The effect of mild hypothermia on IL-10 and IL-18 expression levels was analyzed, and the relationship between IL-10, IL-18 and disease severity in children with hypoxic ischemic encephalopathy was analyzed. The concentration of IL-10 in the experimental group was significantly lower than that in the control group at 1, 2, 3 and 5 days (P<0.05). The concentration of IL-18 in the experimental group was significantly lower than that in the control group at the 2, 3 and 5 days (P<0.05). NBNA scores of the experimental group were significantly higher than those of the control group at 14 and 28 days after birth (P<0.05). Before treatment, the expression levels of IL-10 and IL-18 in severe children were significantly higher than those in moderate children (P<0.05). IL-10 was positively correlated with the severity of the disease (r=0.521, P<0.05), and IL-18 was also positively correlated with the severity of the disease (r=0.616 P<0.05). Mild hypothermia treatment can effectively improve the neurological function of children with HIE, reduce the expression of IL-10 and IL-18 in serum, and inhibit the inflammatory response. Therefore, the expression of IL-10 and IL-18 was positively correlated with the severity of disease in children with HIE, and could be used as an indicator to judge the severity of HIE.

Effects of hypothermia on lung inflammation in a rat model of meconium aspiration syndrome

PURPOSE

To evaluate the effects of hypothermia treatment on meconium-induced inflammation.

METHODS

Fifteen rats were instilled with human meconium (MEC, 1.5 mL/kg, 65 mg/mL) intratracheally and ventilated for 3 hours. Eight rats that were ventilated and not instilled with meconium served as a sham group. In MEC-hypothermia group, the body temperature was lowered to 33±0.5°C. Analysis of the blood gases, interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor (TNF)-α in bronchoalveolar lavage (BAL) fluid samples, and histological analyses of the lungs were performed.

RESULTS

The BAL fluid TNF-α, IL-1β, IL-6 and IL-8 concentrations were significantly higher in the MEC-hypothermia group than in the MEC-normothermia (p < 0.001, p < 0.001, p = 0.001, p < 0.001, respectively) and sham-controlled groups (p < 0.001, p < 0.001, p < 0.001, p < 0.001, respectively).

CONCLUSION

Meconium-induced inflammatory cytokine production is affected by the body temperature control.

Controlled hypothermia may improve surfactant function in asphyxiated neonates with or without meconium aspiration syndrome

Background

Whole-body hypothermia (WBH) is used to improve neurological outcomes in perinatal asphyxia. Recent studies suggested a beneficial effect of hypothermia for some types of acute respiratory failure. However, no data are available about the biophysical function of human surfactant during WBH. We investigated whether WBH improves surfactant biophysical properties in asphyxiated neonates with or without meconium aspiration syndrome (MAS).

Methods

Non-bronchoscopic bronchoalveolar lavage (BAL) has been collected from 10 asphyxiated neonates (2 with MAS, 8 with no lung disease (NLD)) at different time-points (pre-WBH, 24h, 48h, 72h of WBH and post-WBH). Surfactant was extracted and tested by captive bubble surfactometry (CBS) in triplicate, at 37°C and 33.5°C, through initial adsorption and dynamic compression-expansion cycling. Phosphatidylcholine and cholesterol were assayed using enzymatic methods. Clinical data were recorded in real-time.

Results

Minimum surface tension under dynamic testing was significantly improved as assessed at 33.5°C compared with its behavior at 37°C in NLD neonates: the difference was evident after at least 72h of WBH and remained significant at 6h after rewarming (72h: p = 0.009; rewarming: p = 0.040). Similar results were obtained in MAS patients whose surfactant activity improved already at 48h of hypothermia. Total cholesterol showed a trend to increase at the first 24-48h of hypothermia in NLD patients. Conversely, hypothermia seemed to reduce the excess of exogenous cholesterol in MAS surfactant.

Conclusions

Surfactant biophysical properties may improve after 48-72h of WBH in asphyxiated neonates and the improvement is maintained shortly after rewarming. Due to study limitations, further studies are warranted to better clarify the effects of hypothermia on surfactant activity.

Mild Hypothermia Therapy for Moderate or Severe Hypoxicischemic Encephalopathy in Neonates

BACKGROUND

To study the nursing method of mild hypothermia therapy for moderate or severe hypoxic-ischemic encephalopathy (HIE) in neonates.

METHODS

According to the inclusion and exclusion criteria, 48 patients were selected from Nanfang Hospital from December 2015 to October 2016 and randomly divided into the control group (n=24) and observation group (n=24). The control group received routine treatment and nursing, while the observation group received the same treatment as the control group combined with mild hypothermia treatment and nursing. The clinical effects were compared.

RESULTS

The total effective rate in the observation group was increased and mortality was decreased, and the differences were statistically significant (P=0.029 and 0.033, respectively). The 28 d neonatal behavioral neurological assessment and nursing satisfaction scores in the observation group were higher than those in the control group, and the differences were statistically significant (P=0.017 and 0.008, respectively).

CONCLUSION

Mild hypothermia therapy for moderate or severe HIE in neonates is safe and effective, and the correct nursing method is important for guaranteeing proper clinical treatment.