Deep hypothermic circulatory arrest in cyanotic piglets is associated with increased neuronal necrosis

Normoxic Management during Cardiopulmonary Bypass Does Not Reduce Cerebral Mitochondrial Dysfunction in Neonatal Swine

Optimal oxygen management during pediatric cardiopulmonary bypass (CPB) is unknown. We previously demonstrated an increase in cortical mitochondrial reactive oxygen species and decreased mitochondrial function after CPB using hyperoxic oxygen management. This study investigates whether controlled oxygenation (normoxia) during CPB reduces cortical mitochondrial dysfunction and oxidative injury. Ten neonatal swine underwent three hours of continuous CPB at 34 °C (flow > 100 mL/kg/min) via cervical cannulation targeting a partial pressure of arterial oxygen (PaO2) goal < 150 mmHg (normoxia, n = 5) or >300 mmHg (hyperoxia, n = 5). The animals underwent continuous hemodynamic monitoring and serial arterial blood sampling. Cortical microdialysate was serially sampled to quantify the glycerol concentration (represents neuronal injury) and lactate-to-pyruvate ratio (represents bioenergetic dysfunction). The cortical tissue was analyzed via high-resolution respirometry to quantify mitochondrial oxygen consumption and reactive oxygen species generation, and cortical oxidized protein carbonyl concentrations were quantified to assess for oxidative damage. Serum PaO2 was higher in hyperoxia animals throughout CPB (p < 0.001). There were no differences in cortical glycerol concentration between groups (p > 0.2). The cortical lactate-to-pyruvate ratio was modestly elevated in hyperoxia animals (p < 0.03) but the values were not clinically significant (<30). There were no differences in cortical mitochondrial respiration (p = 0.48), protein carbonyls (p = 0.74), or reactive oxygen species generation (p = 0.93) between groups. Controlled oxygenation during CPB does not significantly affect cortical mitochondrial function or oxidative injury in the acute setting. Further evaluation of the short and long-term effects of oxygen level titration during pediatric CPB on cortical tissue and other at-risk brain regions are needed, especially in the presence of cyanosis.

The effect of birth weight and time of day on the thermal response of newborn water buffalo calves

During the 1st days of life, water buffalo calves, especially those with low birth weight, are susceptible to hypothermic mortality due to scarce energy reserves provided by fats. This means that monitoring the thermal state of newborns is essential. The objectives of the present study were to apply infrared thermography (IRT) in 109 buffalo calves to detect differences in the surface temperatures of six thermal windows -lacrimal gland, lacrimal caruncle, periocular region, nostrils, ear canal, pelvic limbs-, and determine their association to birth weight during the first 6 days of life. The calves were divided into four categories according to their weight (Q₁, 37.8-41.25 kg; Q₂, 41.3-46.3 kg; Q₃, 46.4-56.3 kg; Q₄, 56.4-60.3 kg). The thermographic images were recorded in the morning and afternoon. Results showed that the animals in Q₄ registered the highest temperatures in all the thermal windows, and that these were higher in the afternoon (p < 0.0001). When considering the thermal windows, those located in the facial region recorded the highest temperatures; in contrast, the temperatures at the pelvic limbs remained below the average values of the other windows (33.41 and 33.76°C in the morning and afternoon, respectively). According to these results, the birth weight of water buffaloes is a factor that alters their thermoregulation during the 1st days of life, a condition that can be partially compensated by colostrum intake to promote development of an efficient thermoregulatory mechanism in water buffalo calves.

Neonatal infrared thermography images in the hypothermic ruminant model: Anatomical-morphological-physiological aspects and mechanisms for thermoregulation

Hypothermia is one factor associated with mortality in newborn ruminants due to the drastic temperature change upon exposure to the extrauterine environment in the first hours after birth. Ruminants are precocial whose mechanisms for generating heat or preventing heat loss involve genetic characteristics, the degree of neurodevelopment at birth and environmental aspects. These elements combine to form a more efficient mechanism than those found in altricial species. Although the degree of neurodevelopment is an important advantage for these species, their greater mobility helps them to search for the udder and consume colostrum after birth. However, anatomical differences such as the distribution of adipose tissue or the presence of type II muscle fibers could lead to the understanding that these species use their energy resources more efficiently for heat production. The introduction of unconventional ruminant species, such as the water buffalo, has led to rethinking other characteristics like the skin thickness or the coat type that could intervene in the thermoregulation capacity of the newborn. Implementing tools to analyze species-specific characteristics that help prevent a critical decline in temperature is deemed a fundamental strategy for avoiding the adverse effects of a compromised thermoregulatory function. Although thermography is a non-invasive method to assess superficial temperature in several non-human animal species, in newborn ruminants there is limited information about its application, making it necessary to discuss the usefulness of this tool. This review aims to analyze the effects of hypothermia in newborn ruminants, their thermoregulation mechanisms that compensate for this condition, and the application of infrared thermography (IRT) to identify cases with hypothermia.

Syringic acid protects against thioacetamide-induced hepatic encephalopathy: Behavioral, biochemical, and molecular evidence

The objective of this study was to elucidate the effects of syringic acid on thioacetamide-induced hepatic encephalopathy which is a complex serious syndrome with neuropsychiatric abnormalities related to acute liver dysfunctions like cirrhosis. Rats were treated with syringic acid (50 and 100 mg/kg, p.o.) for 14 days in treatment groups. Hepatic encephalopathy was induced by three doses of (200 mg/kg i.p.) thioacetamide injection. Syringic acid effectively alleviated thioacetamide-induced hepatic injury via reduction in ammonia, AST, ALT, ALP, LDH and decrease in oxidative stress (decreased MDA, ROS and increased SOD and GSH). Syringic acid also attenuated inflammatory injury by suppressing TNF-α, IL-1β, and NF-κB and increasing IL-10. The caspase-3 expression was also down-regulated in both liver and brain tissues. Immunohistochemical results confirmed the recovery with syringic acid by downregulation of iNOS, 8-OHdG and GFAP expression. Syringic acid decreased the deteriorating effects of thioacetamide as seen by reduced ammonia concentration and also preserved astrocyte and hepatocyte structure. The behavioral test results from elevated plus maze test, similar to the open-field locomotor test results, confirmed that syringic acid can reverse behavioral impairments. In conclusion, syringic acid exerted hepatoprotective and neuroprotective effects against hepatic encephalopathy by mitigating hepatotoxicity biomarkers, exerting antioxidant, anti-inflammatory effects in addition to suppressing hyperammonemia.