Pathophysiology of Perinatal Asphyxia in Humans and Animal Models

Clear amniotic fluid aspiration syndrome: A novel description of an old entity

BACKGROUND

Clear amniotic fluid aspiration syndrome (CAF-AS) is a very rare event occurring in 0.25% of our term clear amniotic fluids deliveries. The study's aims were: 1. to characterize the risk factors and outcomes associated with Clear Amniotic Fluid Aspiration Syndrome and 2. to compare the outcomes of Clear Amniotic Fluid Aspiration to Meconium Aspiration.

METHODS

This was an observational study over a 22-year period in a single level-3 medical center. Compared were parturient/labor characteristics and neonatal outcomes in cases with suspected Clear Amniotic Fluid Aspiration to cases suspected for Meconium Aspiration.

RESULTS

Out of 79,620 term deliveries there were 66,705 (83.8%) clear amniotic fluids and 12,915 (16.2%) meconium stained amniotic fluid (MSAF). Of neonates born with clear amniotic fluid, 166 (0.25%) were diagnosed with Clear Amniotic Fluid Aspiration Syndrome (CAF-AS), while 202 (15.7%) of those born with MSAF, were diagnosed with aspiration syndrome (MSAF-AS). Both conditions had comparable rates of mild manifestation (67.5% vs 69.2%, p = 0.63). Persistent pulmonary hypertension (PPH) occurred 5 times less in CAF-AS than MSAF-AS (4% vs 20%, OR 0.17, P< 0.0001) Both conditions presented similar rates of surfactant without PPH (11.1% vs 13.4%, p = 0.87). There was 1 postnatal death in CAF-AS vs 10 in MSAF.

CONCLUSION

CAF-AS were quantitatively quite similar in terms of need of actual active intervention of the neonatologists in the delivery room (166 vs 202, i.e. in terms of numbers of cases and not prevalence) to MSAF-AS.We identified in these cases two major specific causes: hyperkinetic explosive deliveries in multiparas and long-lasting episodes of maternal hypotension due to epidural/spinal anaesthesia during labor. Out of 140 million births per year in the world, it should be of concern that 3 million cases are neglected nowadays. Future studies should evaluate if this CAF-AS should benefit from a more active intervention such as immediate endotracheal suction at birth, this clear fluid being very easy to suction.

Additive interaction between birth asphyxia and febrile seizures on autism spectrum disorder: a population-based study

BACKGROUND

Autism Spectrum Disorder (ASD) is a pervasive neurodevelopmental disorder that can significantly impact an individual's ability to socially integrate and adapt. It's crucial to identify key factors associated with ASD. Recent studies link both birth asphyxia (BA) and febrile seizures (FS) separately to higher ASD prevalence. However, investigations into the interplay of BA and FS and its relationship with ASD are yet to be conducted. The present study mainly focuses on exploring the interactive effect between BA and FS in the context of ASD.

METHODS

Utilizing a multi-stage stratified cluster sampling, we initially recruited 84,934 Shanghai children aged 3-12 years old from June 2014 to June 2015, ultimately including 74,251 post-exclusion criteria. A logistic regression model was conducted to estimate the interaction effect after controlling for pertinent covariates. The attributable proportion (AP), the relative excess risk due to interaction (RERI), the synergy index (SI), and multiplicative-scale interaction were computed to determine the interaction effect.

RESULTS

Among a total of 74,251 children, 192 (0.26%) were diagnosed with ASD. The adjusted odds ratio for ASD in children with BA alone was 3.82 (95% confidence interval [CI] 2.42-6.02), for FS alone 3.06 (95%CI 1.48-6.31), and for comorbid BA and FS 21.18 (95%CI 9.10-49.30), versus children without BA or FS. The additive interaction between BA and FS showed statistical significance (P < 0.001), whereas the multiplicative interaction was statistically insignificant (P > 0.05).

LIMITATIONS

This study can only demonstrate the relationship between the interaction of BA and FS with ASD but cannot prove causation. Animal brain experimentation is necessary to unravel its neural mechanisms. A larger sample size, ongoing monitoring, and detailed FS classification are needed for confirming BA-FS interaction in ASD.

CONCLUSION

In this extensive cross-sectional study, both BA and FS were significantly linked to ASD. The coexistence of these factors was associated with an additive increase in ASD prevalence, surpassing the cumulative risk of each individual factor.

Neonatal intestinal mucus barrier changes in response to maturity, inflammation, and sodium decanoate supplementation

The integrity of the intestinal mucus barrier is crucial for human health, as it serves as the body's first line of defense against pathogens. However, postnatal development of the mucus barrier and interactions between maturity and its ability to adapt to external challenges in neonatal infants remain unclear. In this study, we unveil a distinct developmental trajectory of the mucus barrier in preterm piglets, leading to enhanced mucus microstructure and reduced mucus diffusivity compared to term piglets. Notably, we found that necrotizing enterocolitis (NEC) is associated with increased mucus diffusivity of our large pathogen model compound, establishing a direct link between the NEC condition and the mucus barrier. Furthermore, we observed that addition of sodium decanoate had varying effects on mucus diffusivity depending on maturity and health state of the piglets. These findings demonstrate that regulatory mechanisms governing the neonatal mucosal barrier are highly complex and are influenced by age, maturity, and health conditions. Therefore, our results highlight the need for specific therapeutic strategies tailored to each neonatal period to ensure optimal gut health.

Decreased renal function among children born to women with obstructed labour in Eastern Uganda: a cohort study

BACKGROUND

Over two million children and adolescents suffer from chronic kidney disease globally. Early childhood insults such as birth asphyxia could be risk factors for chronic kidney disease in later life. Our study aimed to assess renal function among children aged two to four years, born to women with obstructed labour.

METHODS

We followed up 144 children aged two to four years, born to women with obstructed labor at Mbale regional referral hospital in Eastern Uganda. We used serum creatinine to calculate estimated glomerular filtration rate (eGFR) using the Schwartz formula. We defined decreased renal function as eGFR less than 90 ml/min/1.73m2.

RESULTS

The mean age of the children was 2.8 years, standard deviation (SD) of 0.4 years. Majority of the children were male (96/144: 66.7%). The mean umbilical lactate level at birth among the study participants was 8.9 mmol/L with a standard deviation (SD) of 5.0. eGFR of the children ranged from 55 to 163 ml/min/1.73m2, mean 85.8 ± SD 15.9. Nearly one third of the children (45/144) had normal eGFR (> 90 ml/Min/1.73m2), two thirds (97/144) had a mild decrease of eGFR (60-89 ml/Min/1.73m2), and only two children had a moderate decrease of eGFR (< 60 ml/Min/1.73m2). Overall incidence of reduced eGFR was 68.8% [(99/144): 95% CI (60.6 to 75.9)].

CONCLUSION

We observed a high incidence of reduced renal function among children born to women with obstructed labour. We recommend routine follow up of children born to women with obstructed labour and add our voices to those calling for improved intra-partum and peripartum care.

Correlation Study on the Prognostic Value of miR-21 and S-100B Protein Levels in Neonatal Hypoxic-Ischemic Encephalopathy Undergoing Hypothermia Therapy

OBJECTIVE

To evaluate the variations in serum levels of microRNA-21 (miR-21) and S-100B protein in neonates with hypoxic-ischemic encephalopathy (HIE) after receiving hypothermia therapy and explore the correlation of these biomarkers with the neurodevelopmental prognosis of the infants.

METHODS

This retrospective analysis included 90 neonatal HIE patients diagnosed and treated between January 2019 and December 2022. Real-time quantitative PCR and enzyme-linked immunosorbent assay (ELISA) methods were used to measure miR-21 and S-100B protein levels. Neurodevelopmental assessments were conducted at one year, and follow-up was performed using the Bayley Scales of Infant and Toddler Development third edition. Statistical analysis was carried out using SPSS software, with t-tests for continuous variables, chi-square tests for categorical data, Pearson correlation coefficient for correlation analysis, and multivariate regression analysis to adjust for confounding factors.

RESULTS

After hypothermia therapy, the observation group showed a significant decrease in miR-21 and S-100B protein levels (P < 0.001), and neurodevelopmental scores were significantly higher than the control group (P < 0.05). Correlation analysis indicated a negative correlation between miR-21 and neurodevelopmental scores (r=-0.62, P < 0.001), as well as a negative correlation between S-100B protein levels (r=-0.76, P < 0.001). Multivariate regression analysis demonstrated that miR-21 levels and S-100B protein levels maintained independent negative correlations with neurodevelopmental scores (P < 0.001).

CONCLUSION

Hypothermia therapy significantly reduces serum levels of miR-21 and S-100B protein in neonatal HIE patients and may be associated with better prognosis. miR-21 and S-100B serve as prognostic biomarkers, aiding in predicting and improving the treatment outcomes and long-term prognosis of neonatal HIE.

MicroRNA-124 negatively regulates STAT3 to alleviate hypoxic-ischemic brain damage by inhibiting oxidative stress

MicroRNA-124 (miR-124) is implicated in various neurological diseases; however, its significance in hypoxic-ischaemic brain damage (HIBD) remains unclear. This study aimed to elucidate the underlying pathophysiological mechanisms of miR-124 in HIBD. In our study performed on oxygen-glucose deprivation followed by reperfusion (OGD)/R-induced primary cortical neurons, a substantial reduction in miR-124 was observed. Furthermore, the upregulation of miR-124 significantly mitigated oxidative stress, apoptosis, and mitochondrial impairment. We demonstrated that miR-124 interacts with the signal transducer and activator of transcription 3 (STAT3) to exert its biological function using the dual-luciferase reporter gene assay. As the duration of OGD increased, miR-124 exhibited a negative correlation with STAT3. STAT3 overexpression notably attenuated the protective effects of miR-124 mimics, while knockdown of STAT3 reversed the adverse effects of the miR-124 inhibitor. Subsequently, we conducted an HIBD model in rats. In vivo experiments, miR-124 overexpression attenuated cerebral infarction volume, cerebral edema, apoptosis, oxidative stress, and improved neurological function recovery in HIBD rats. In summary, the neuroprotective effects of the miR-124/STAT3 axis were confirmed in the HIBD model. MiR-124 may serve as a potential biomarker with significant therapeutic implications for HIBD.

Hypothalamic Neuromodulation of Hypothermia in Domestic Animals

When an organism detects decreases in their core body temperature, the hypothalamus, the main thermoregulatory center, triggers compensatory responses. These responses include vasomotor changes to prevent heat loss and physiological mechanisms (e.g., shivering and non-shivering thermogenesis) for heat production. Both types of changes require the participation of peripheral thermoreceptors, afferent signaling to the spinal cord and hypothalamus, and efferent pathways to motor and/or sympathetic neurons. The present review aims to analyze the scientific evidence of the hypothalamic control of hypothermia and the central and peripheral changes that are triggered in domestic animals.

Prevalence of Perinatal Asphyxia Using Apgar Scores and Cord Blood pH and the Relationship between the Two Methods: A Study of FMC Umuahia

BACKGROUND

Perinatal asphyxia contributes significantly to neonatal morbidity and mortality. It occurs worldwide, and the Apgar score is the most widely used method of diagnosis. Recently, umbilical cord arterial pH has been reported as the most objective way to assess fetal acidosis at birth as it predicts the adverse outcome of perinatal asphyxia. It is imperative to establish the concordance between these two diagnostic methods to reinforce the practicality of the Apgar score as the preferred diagnostic tool for perinatal asphyxia in developing nations, such as Nigeria.

AIM

To determine the prevalence of perinatal asphyxia by using the Apgar score and arterial cord blood pH and the relationships between these methods at the Federal Medical Center (FMC), Umuahia.

MATERIALS AND METHODS

This cross-sectional study enrolled 245-term newborns. Perinatal asphyxia was diagnosed using both Apgar scoring and arterial cord blood pH measurements. Data obtained were analyzed using SPSS version 20 and a P value < 0.05 was considered significant.

RESULTS

Perinatal asphyxia was reported in 33.1% and 31.4% by using the Apgar score and arterial cord blood pH, respectively. There was a moderate agreement between the two methods for diagnosing perinatal asphyxia (κ = 0.44), and no statistically significant difference was observed in the prevalence of perinatal asphyxia between these methods (McNemar's χ2 = 0.27, P = 0.699). Furthermore, a strong positive correlation was observed between the Apgar score at 1 and 5 minutes of life and arterial cord blood pH (rs = 0.87, P ≤ 0.001 and rs = 0.80, P ≤ 0.001 respectively).

CONCLUSION

The prevalence of perinatal asphyxia by the two methods was high, and there was no significant difference between both methods of assessing perinatal asphyxia. Thus, the diagnosis of perinatal asphyxia can effectively be made using either the Apgar score or arterial cord blood pH, affirming the practicality and reliability of the Apgar score in resource-limited healthcare settings.

Neuroquantification enhances the radiological evaluation of term neonatal hypoxic-ischaemic cerebral injuries

Background

Injury patterns in hypoxic-ischaemic brain injury (HIBI) are well recognised but there are few studies evaluating cerebral injury using neuroquantification models.

Objectives

Quantification of brain volumes in a group of patients with clinically determined cerebral palsy.

Method

In this retrospective study, 297 children with cerebral palsy were imaged for suspected HIBI with analysis of various cerebral substrates. Of these, 96 children over the age of 3 years with a clinical diagnosis of cerebral palsy and abnormal MRI findings underwent volumetric analyses using the NeuroQuant® software solution. The spectrum of volumetric changes and the differences between the various subtypes (and individual subgroups) of HIBI were compared.

Results

Compared with the available normative NeuroQuant® database, the average intracranial volume was reduced to the 1st percentile in all patient groups (p < 0.001). Statistically significant differences were observed among the types and subgroups of HIBI. Further substrate volume reductions were identified and described involving the thalami, brainstem, hippocampi, putamina and amygdala. The combined volumes of five regions of interest (frontal pole, putamen, hippocampus, brainstem and paracentral lobule) were consistently reduced in the Rolandic basal ganglia-thalamus (RBGT) subtype.

Conclusion

This study determined a quantifiable reduction of intracranial volume in all subtypes of HIBI and predictable selective cerebral substrate volume reduction in subtypes and subgroups. In the RBGT subtype, a key combination of five substrate injuries was consistently noted, and thalamic, occipital lobe and brainstem volume reduction was also significant when compared to the watershed subtype.

Contribution

This study demonstrates the value of integrating an artificial intelligence programme into the radiologists' armamentarium serving to quantify brain injuries more accurately in HIBI. Going forward this will be an inevitable evolution of daily radiology practice in many fields of medicine, and it would be beneficial for radiologists to embrace these technological innovations.

Stem Cell Therapy in Neonatal Hypoxic-Ischemic Encephalopathy and Cerebral Palsy: a Bibliometric Analysis and New Strategy

The aim of this study was to identify related scientific outputs and emerging topics of stem cells in neonatal hypoxic-ischemic encephalopathy (NHIE) and cerebral palsy (CP) through bibliometrics and literature review. All relevant publications on stem cell therapy for NHIE and CP were screened from websites and analyzed research trends. VOSviewer and CiteSpace were applied to visualize and quantitatively analyze the published literature to provide objective presentation and prediction. In addition, the clinical trials, published articles, and projects of the National Natural Science Foundation of China associated with stem cell therapy for NHIE and CP were summarized. A total of 294 publications were associated with stem cell therapy for NHIE and CP. Most publications and citations came from the USA and China. Monash University and University Medical Center Utrecht produced the most publications. Pediatric research published the most studies on stem cell therapy for NHIE and CP. Heijnen C and Kavelaars A published the most articles. Cluster analyses show that current research trend is more inclined toward the repair mechanism and clinical translation of stem cell therapy for NHIE and CP. By summarizing various studies of stem cells in NHIE and CP, it is indicated that this research direction is a hot topic at present. Furthermore, organoid transplantation, as an emerging and new therapeutic approach, brings new hope for the treatment of NHIE and CP. This study comprehensively summarized and analyzed the research trend of global stem cell therapy for NHIE and CP. It has shown a marked increase in stem cell therapy for NHIE and CP research. In the future, more efforts will be made on exploring stem cell or organoid therapy for NHIE and CP and more valuable related mechanisms of action to achieve clinical translation as soon as possible.

Subcortical brain volumes in neonatal hypoxic-ischemic encephalopathy

BACKGROUND

Despite treatment with therapeutic hypothermia, hypoxic-ischemic encephalopathy (HIE) is associated with adverse developmental outcomes, suggesting the involvement of subcortical structures including the thalamus and basal ganglia, which may be vulnerable to perinatal asphyxia, particularly during the acute period. The aims were: (1) to examine subcortical macrostructure in neonates with HIE compared to age- and sex-matched healthy neonates within the first week of life; (2) to determine whether subcortical brain volumes are associated with HIE severity.

METHODS

Neonates (n = 56; HIE: n = 28; Healthy newborns from the Developing Human Connectome Project: n = 28) were scanned with MRI within the first week of life. Subcortical volumes were automatically extracted from T1-weighted images. General linear models assessed between-group differences in subcortical volumes, adjusting for sex, gestational age, postmenstrual age, and total cerebral volumes. Within-group analyses evaluated the association between subcortical volumes and HIE severity.

RESULTS

Neonates with HIE had smaller bilateral thalamic, basal ganglia and right hippocampal and cerebellar volumes compared to controls (all, p < 0.02). Within the HIE group, mild HIE severity was associated with smaller volumes of the left and right basal ganglia (both, p < 0.007) and the left hippocampus and thalamus (both, p < 0.04).

CONCLUSIONS

Findings suggest that, despite advances in neonatal care, HIE is associated with significant alterations in subcortical brain macrostructure.

IMPACT

Compared to their healthy counterparts, infants with HIE demonstrate significant alterations in subcortical brain macrostructure on MRI acquired as early as 4 days after birth. Smaller subcortical volumes impacting sensory and motor regions, including the thalamus, basal ganglia, and cerebellum, were seen in infants with HIE. Mild and moderate HIE were associated with smaller subcortical volumes.

Perinatal asphyxia and hypothermic treatment from the endocrine perspective

Introduction

Perinatal asphyxia is one of the three most important causes of neonatal mortality and morbidity. Therapeutic hypothermia represents the standard treatment for infants with moderate-severe perinatal asphyxia, resulting in reduction in the mortality and major neurodevelopmental disability. So far, data in the literature focusing on the endocrine aspects of both asphyxia and hypothermia treatment at birth are scanty, and many aspects are still debated. Aim of this narrative review is to summarize the current knowledge regarding the short- and long-term effects of perinatal asphyxia and of hypothermia treatment on the endocrine system, thus providing suggestions for improving the management of asphyxiated children.

Results

Involvement of the endocrine system (especially glucose and electrolyte disturbances, adrenal hemorrhage, non-thyroidal illness syndrome) can occur in a variable percentage of subjects with perinatal asphyxia, potentially affecting mortality as well as neurological outcome. Hypothermia may also affect endocrine homeostasis, leading to a decreased incidence of hypocalcemia and an increased risk of dilutional hyponatremia and hypercalcemia.

Conclusions

Metabolic abnormalities in the context of perinatal asphyxia are important modifiable factors that may be associated with a worse outcome. Therefore, clinicians should be aware of the possible occurrence of endocrine complication, in order to establish appropriate screening protocols and allow timely treatment.

A hypothermia mimetic molecule (zr17-2) reduces ganglion cell death, gliosis, and electroretinogram distortion in male rats subjected to perinatal asphyxia

Introduction: Perinatal asphyxia (PA) represents a major problem in perinatology and may cause visual losses, including blindness. We, and others, have shown that hypothermia prevents retinal symptoms associated to PA. In the present work, we evaluate whether a hypothermia mimetic small molecule, zr17-2, has similar effects in the context of PA. Methods: Four experimental groups were studied in male rats: Naturally born rats as controls (CTL), naturally born rats injected s.c. with 50 µL of 330 nmols/L zr17-2 (ZR), animals that were exposed to PA for 20 min at 37°C (PA), and rats that were exposed to PA and injected with zr17-2 (PA-ZR). Forty-five days after treatment, animals were subjected to electroretinography. In addition, morphological techniques (TUNEL, H&E, multiple immunofluorescence) were applied to the retinas. Results: A reduction in the amplitude of the a- and b-wave and oscillatory potentials (OP) of the electroretinogram (ERG) was detected in PA animals. Treatment with zr17-2 resulted in a significant amelioration of these parameters (p < 0.01). In PA animals, a large number of apoptotic cells was found in the GCL. This number was significantly reduced by treatment with the small molecule (p < 0.0001). In a similar way, the thickness of the inner retina and the intensity of GFAP immunoreactivity (gliosis) increased in PA retinas (p < 0.0001). These parameters were corrected by the administration of zr17-2 (p < 0.0001). Furthermore, injection of the small molecule in the absence of PA did not modify the ERG nor the morphological parameters studied, suggesting a lack of toxicity. Discussion: In conclusion, our results indicate that a single s.c. injection of zr17-2 in asphyctic neonates may provide a novel and efficacious method to prevent the visual sequelae of PA.

Decreased renal function among children born to women with obstructed labour in Eastern Uganda: a cohort study

Background

Over two million children and adolescents suffer from chronic kidney disease globally. Early childhood insults such as birth asphyxia could be risk factors for development of chronic kidney disease in infancy. Our study aimed to assess renal function among children aged two to four years, born to women with obstructed labour.

Methods

We followed up 144 children aged two to four years, born to women with obstructed labor at Mbale regional referral hospital in Eastern Uganda. We used estimated glomerular filtration rate (eGFR) by the Schwartz formula to calculate eGFR (0.413*height)/ serum creatinine as a measure of renal function. eGFR less than 90 ml/min/1.73m2 was classified as decreased renal function.

Results

The mean age of the children was 2.8 years, standard deviation (SD) of 0.4 years. Majority of the children were male (96/144: 66.7%). The mean umbilical lactate level at birth among the study participants was 8.9 mmol/L with a standard deviation (SD) of 5.0. eGFR values ranged from 55 to 163ml/min/1.72m2, mean 85.8 ± SD 15.9. One third (31.3%) 45/144 had normal eGFR (> 90 ml/Min/1.72m2), two thirds (67.4%) 97/144 had a mild decrease of eGFR (60-89 ml/Min/1.72m2), and only 2/144 (1.4%) had a moderate decrease of eGFR. Overall incidence of reduced eGFR was 68.8% (99/144).

Conclusion

We observed a high incidence of impaired renal function among children born to women with obstructed labour. We recommend routine follow up of children born to women with obstructed labour and add our voices to those calling for improved intra-partum and peripartum care.

The Role of Brown Adipose Tissue and Energy Metabolism in Mammalian Thermoregulation during the Perinatal Period

Hypothermia is one of the most common causes of mortality in neonates, and it could be developed after birth because the uterus temperature is more elevated than the extrauterine temperature. Neonates use diverse mechanisms to thermoregulate, such as shivering and non-shivering thermogenesis. These strategies can be more efficient in some species, but not in others, i.e., altricials, which have the greatest difficulty with achieving thermoneutrality. In addition, there are anatomical and neurological differences in mammals, which may present different distributions and amounts of brown fat. This article aims to discuss the neuromodulation mechanisms of thermoregulation and the importance of brown fat in the thermogenesis of newborn mammals, emphasizing the analysis of the biochemical, physiological, and genetic factors that determine the distribution, amount, and efficiency of this energy resource in newborns of different species. It has been concluded that is vital to understand and minimize hypothermia causes in newborns, which is one of the main causes of mortality in neonates. This would be beneficial for both animals and producers.

Development of a neonatal Göttingen Minipig model for dose precision in perinatal asphyxia: technical opportunities, challenges, and potential further steps

Animal models provide useful information on mechanisms in human disease conditions, but also on exploring (patho)physiological factors affecting pharmacokinetics, safety, and efficacy of drugs in development. Also, in pediatric patients, nonclinical data can be critical for better understanding the disease conditions and developing new drug therapies in this age category. For perinatal asphyxia (PA), a condition defined by oxygen deprivation in the perinatal period and possibly resulting in hypoxic ischemic encephalopathy (HIE) or even death, therapeutic hypothermia (TH) together with symptomatic drug therapy, is the standard approach to reduce death and permanent brain damage in these patients. The impact of the systemic hypoxia during PA and/or TH on drug disposition is largely unknown and an animal model can provide useful information on these covariates that cannot be assessed separately in patients. The conventional pig is proven to be a good translational model for PA, but pharmaceutical companies do not use it to develop new drug therapies. As the Göttingen Minipig is the commonly used pig strain in nonclinical drug development, the aim of this project was to develop this animal model for dose precision in PA. This experiment consisted of the instrumentation of 24 healthy male Göttingen Minipigs, within 24 h of partus, weighing approximately 600 g, to allow the mechanical ventilation and the multiple vascular catheters inserted for maintenance infusion, drug administration and blood sampling. After premedication and induction of anesthesia, an experimental protocol of hypoxia was performed, by decreasing the inspiratory oxygen fraction (FiO₂) at 15%, using nitrogen gas. Blood gas analysis was used as an essential tool to evaluate oxygenation and to determine the duration of the systemic hypoxic insult to approximately 1 h. The human clinical situation was mimicked for the first 24 h after birth in case of PA, by administering four compounds (midazolam, phenobarbital, topiramate and fentanyl), frequently used in a neonatal intensive care unit (NICU). This project aimed to develop the first neonatal Göttingen Minipig model for dose precision in PA, allowing to separately study the effect of systemic hypoxia versus TH on drug disposition. Furthermore, this study showed that several techniques that were thought to be challenging or even impossible in these very small animals, such as endotracheal intubation and catheterization of several veins, are feasible by trained personnel. This is relevant information for laboratories using the neonatal Göttingen Minipig for other disease conditions or drug safety testing.

Importance of Monitoring Fetal and Neonatal Vitality in Bovine Practices

Prior to initiating any obstetrical intervention for anterior or posterior presentation, it is imperative to emphasize the need for a precise and accurate diagnosis of fetal viability and to select the most appropriate approach for assistance. In uncertain cases, diagnostic tools such as ultrasonography, pulse oximeter, or measurement of acid-base balance or lactate concentration may be employed to confirm the diagnosis. In situations of severe asphyxia, a cesarean section is preferred over traction, even if the duration of asphyxia is less than 60 s, to maximize the likelihood of the survival of the fetus. Postcalving, several vitality scores have been proposed to evaluate the vigor of the newborn calf. Originally, four different clinical signs were recommended for assessing the well-being of newborn calves. Subsequently, five or more different clinical signs were recommended to evaluate vitality. However, despite the efforts for devising a practical tool to assess newborn calf vitality; a user-friendly and highly accurate instrument that can be used on farms remains elusive. Measuring the acid-base balance or lactate concentration may increase the diagnostic accuracy. It is critical to emphasize the importance of reducing the incidence of dystocia to mitigate the occurrence of severe asphyxia. In instances where asphyxia is unavoidable, adequate treatments should be administered to minimize losses.

Clinical Experiences and Mechanism of Action with the Use of Oxytocin Injection at Parturition in Domestic Animals: Effect on the Myometrium and Fetuses

Oxytocin is a key hormone for parturition and maternal traits in animals. During the peripartum period, the levels of endogenous oxytocin dictate physiological events such as myometrial contractions, prostaglandin production with the subsequent increase in oxytocin receptors, and the promotion of lactation when administered immediately after birth. While this hormone has some benefits regarding these aspects, the exogenous administration of oxytocin has been shown to have detrimental effects on the fetus, such as asphyxia, meconium staining, ruptured umbilical cords, and more dystocia cases in females. This review aims to analyze the main effects of oxytocin on myometrial activity during parturition, and its potential favorable and negative administration effects reflected in the fetus health of domestic animals. In conclusion, it is convenient to know oxytocin's different effects as well as the adequate doses and the proper moment to administrate it, as it can reduce labor duration, but it can also increase dystocia.

Melatonin: A Potential Candidate for the Treatment of Experimental and Clinical Perinatal Asphyxia

Perinatal asphyxia is considered to be one of the major causes of brain neurodegeneration in full-term newborns. The worst consequence of perinatal asphyxia is neurodegenerative brain damage, also known as hypoxic-ischemic encephalopathy. Hypoxic-ischemic encephalopathy is the leading cause of mortality in term newborns. To date, due to the complex mechanisms of brain damage, no effective or causal treatment has been developed that would ensure complete neuroprotection. Although hypothermia is the standard of care for hypoxic-ischemic encephalopathy, it does not affect all changes associated with encephalopathy. Therefore, there is a need to develop effective treatment strategies, namely research into new agents and therapies. In recent years, it has been pointed out that natural compounds with neuroprotective properties, such as melatonin, can be used in the treatment of hypoxic-ischemic encephalopathy. This natural substance with anti-inflammatory, antioxidant, anti-apoptotic and neurofunctional properties has been shown to have pleiotropic prophylactic or therapeutic effects, mainly against experimental brain neurodegeneration in hypoxic-ischemic neonates. Melatonin is a natural neuroprotective hormone, which makes it promising for the treatment of neurodegeneration after asphyxia. It is supposed that melatonin alone or in combination with hypothermia may improve neurological outcomes in infants with hypoxic-ischemic encephalopathy. Melatonin has been shown to be effective in the last 20 years of research, mainly in animals with perinatal asphyxia but, so far, no clinical trials have been performed on a sufficient number of newborns. In this review, we summarize the advantages and limitations of melatonin research in the treatment of experimental and clinical perinatal asphyxia.

Meconium Aspiration Syndrome in Animal Models: Inflammatory Process, Apoptosis, and Surfactant Inactivation

Meconium Aspiration Syndrome is a condition that causes respiratory distress in newborns due to occlusion and airway inflammation, and surfactant inactivation by meconium. This condition has been described in animal species such as canids, sheep, cattle, horses, pigs, and marine mammals. In its pathogenesis, the pulmonary epithelium activates a limited inflammatory response initiated by cytokines causing leukocyte chemotaxis, inhibition of phagocytosis, and pathogen destruction. Likewise, cytokines release participates in the apoptosis processes of pneumocytes due to the interaction of angiotensin with cytokines and the caspase pathway. Due to these reactions, the prevalent signs are lung injury, hypoxia, acidosis, and pneumonia with susceptibility to infection. Given the importance of the pathophysiological mechanism of meconium aspiration syndrome, this review aims to discuss the relevance of the syndrome in veterinary medicine. The inflammatory processes caused by meconium aspiration in animal models will be analyzed, and the cellular apoptosis and biochemical processes of pulmonary surfactant inactivation will be discussed.

Animal Welfare Compromises Associated with Causes of Death in Neonatal Piglets

Simple Summary

The pre-weaning piglet mortality percentage is a commonly reported metric on commercial pig farms. The mortality percentage tells us how many piglets died, but not what their welfare status was as it relates to their cause of death. This pilot study aimed to evaluate the likely experience of piglets that died, following confirmation of the cause of death via postmortem investigation. The Five Domains Model was then used to collate scientific evidence of the likely experience of these piglets before death from acute disease, starvation, crushing, savaging and euthanasia, to understand the impact of different causes on their welfare. The resulting findings raised the question of differentiating ‘smothering’ as a cause of death from ‘crushing,’, and that co-morbidities (such as hypothermia) may alter the welfare experience due to their influence on consciousness before death.

Abstract

This pilot study aimed to assess the welfare impacts of different causes of pre-weaning deaths in piglets. Piglets that died between 0–7 days after birth (n = 106) were collected from two commercial pig farms and subject to post-mortem examination to confirm their cause of death as well as any contributing factors. Using the Five Domains Model, the most likely affective experiences associated with the pathological findings were carefully inferred to better understand affective experience as it related to known causes of liveborn piglet mortality. The most common causes of liveborn piglet mortality were starvation (23%), crushing (23%) and non-viable (21%). Thirty one piglets had evidence of starvation, but it was only considered the primary cause of death in 15 piglets, as cofactors such as poor viability (n = 13) were also present in many piglets with evidence of starvation. All 15 piglets that were crushed died within 24 h after birth and most had evidence of thoracic and/or abdominal internal bleeding. This study found that common causes of liveborn piglet death were associated with compromises in Domains 1 (Nutrition/hydration), 3 (Health/function), and4 (Behavioural interactions), with the most likely resulting affective states described in Domain 5 (Mental state). This highlights the interaction between physical/functional and situation-related (behavioural) aspects that influence an animals’ welfare status.

Analgesia during Parturition in Domestic Animals: Perspectives and Controversies on Its Use

This article analyzes the physiological role of pain during parturition in domestic animals, discusses the controversies surrounding the use of opioids, non-steroidal anti-inflammatory drugs (NSAIDs), and local analgesics as treatments during labor, and presents the advantages and disadvantages for mother and offspring. Labor is a potentially stressful and painful event, due to the contractions that promote expulsion of the fetus. During labor, neurotransmitters such as the prostaglandins contribute to the sensitization of oxytocin receptors in the myometrium and the activation of nociceptive fibers, thus supporting the physiological role of pain. Endogenously, the body secretes opioid peptides that modulate harmful stimuli and, at the same time, can inhibit oxytocin's action in the myometrium. Treating pain during the different stages of parturition is an option that can help prevent such consequences as tachycardia, changes in breathing patterns, and respiratory acidosis, all of which can harm the wellbeing of offspring. However, studies have found that some analgesics can promote myometrial contractility, increase expulsion time, affect fetal circulation, and alter mother-offspring recognition due to hypnotic effects. Other data, however, indicate that reducing the number of uterine contractions with analgesics increases their potency, thus improving maternal performance. Managing pain during labor requires understanding the tocolytic properties of analgesics and their advantages in preventing the consequences of pain.

Early Blood Analysis and Gas Exchange Monitoring in the Canine Neonate: Effect of Dam’s Size and Birth Order

Simple Summary

The complications that are observed during parturition are events that affect the vitality of the newborn and can also compromise their health by predisposing them to fetal hypoxia, increasing newborn mortality. Blood gas analysis to measure the main biomarkers associated with hypoxia evaluates the physiological and metabolic alterations derived from this state, and these could help identify if said markers respond to maternal or neonatal causes. This study aimed to assess the effect of the dam’s size, the birth order, and the presentation of blood gas alterations. Recognizing if these elements are intertwined may enhance newborns’ life expectancy by enabling the planning of a perinatal protocol to avoid serious metabolic consequences that are derived from prolonged hypoxia.

Abstract

In canines, size at birth is determined by the dam’s weight, which would probably affect the newborn’s viability due to litter size and birth order. Fetal hypoxia causes distress and acidemia. Identifying physiological blood alterations in the puppy during the first minute of life through the blood gas exchange of the umbilical cord could determine the puppy’s risk of suffering asphyxiation during labor. This study aimed to evaluate the effect of the birth order and dam’s size during spontaneous labor and the alterations during the first minute of life. The results indicate that the dam’s size and the birth order have considerable physiological and metabolic effects in the puppies, mainly in birth order 1 (BO1) in small-size dogs, while in the medium size, the last puppy presented more alterations, probably because of a prolonged whelping which could have fostered hypoxic processes and death. Likewise, with large-size dogs, intrapartum asphyxiation processes were registered during the first minute of life in any birth order.

Defining longer term outcomes in an ovine model of moderate perinatal hypoxia-ischemia

Hypoxic-ischemic encephalopathy (HIE) is the leading cause of neonatal morbidity and mortality worldwide. Approximately 1 million infants born with HIE each year survive with cerebral palsy (CP) and/or serious cognitive disabilities. While infants born with mild and severe HIE frequently result in predictable outcomes, infants born with moderate HIE exhibit variable outcomes that are highly unpredictable. Here, we describe an umbilical cord occlusion (UCO) model of moderate HIE with a 6-day follow-up. Near term lambs (n=27) are resuscitated after the induction of 5 minutes of asystole. Following recovery, lambs are assessed to define neurodevelopmental outcomes. At the end of this period, lambs are euthanized, and brains harvested for histological analysis. Compared with prior models that typically follow lambs for 3 days, the observation of neurobehavioral outcomes for 6 days enables identification of animals that recover significant neurological function. Approximately 35 % of lambs exhibited severe motor deficits throughout the entirety of the 6-day course and, in the most severely affected lambs, developed spastic diparesis similar to that observed in infants who survive severe neonatal HIE (severe, UCOs). Importantly, and similar to outcomes in human neonates, while initially developing significant acidosis and encephalopathy, the remainder of the lambs in this model recovered normal motor activity and exhibited normal neurodevelopmental outcomes by 6 days of life (improved, UCOi). The UCOs group exhibited gliosis and inflammation in both white and gray matter, oligodendrocyte loss, and neuronal loss and cellular death in the hippocampus and cingulate cortex. While the UCOi group exhibited more cellular death and gliosis in the parasagittal cortex and demonstrated more preserved white matter markers, along with reduced markers of inflammation and lower cellular death and neuronal loss in Ca3 of the hippocampus compared with UCOs lambs. Our large animal model of moderate HIE with prolonged follow-up will help further define pathophysiologic drivers of brain injury while enabling identification of predictive biomarkers that correlate with disease outcomes and ultimately help support development of therapeutic approaches to this challenging clinical scenario.