Search

In premature births, deficiency and/or inactivation of surfactant and incomplete development of lung occur, leading to pulmonary complications and greater need for ventilatory interventions. Prenatal corticosteroid therapy is used to improve neonatal lung function and, thus, may reduce mortality and lower incidence and severity of lung injury. Therefore, this study aimed to assess the need for ventilatory support in preterm lambs subjected or not to prenatal betamethasone treatment, and to evaluate the effectiveness on neonatal survival. Lambing was induced and 13 premature lambs were assigned to Corticosteroid Group (n = 8; lambs from ewes subjected previously to 0.5 mg/kg betamethasone, IM, at 133 days of pregnancy) and Control Group (n = 5; non-treated lambs). Lambs were evaluated for vitality, neurologic reflexes, vital functions and birth weight. Three ventilatory modalities were preconized for critical lambs, according to specific criteria: mask oxygen therapy, self-inflating bag with tracheal tube and mechanical ventilation. Non-treated lambs had lower vitality score, muscle tonus and respiratory rate compared to Corticosteroid Group. Ventilatory support was needed for 3 Control lambs and only 1 Corticosteroid neonate. Corticosteroid lamb required significant less time-frame between birth and onset of ventilatory assistance and remained under ventilation for a shorter time. Percentage of ventilated non-treated lambs correlated negatively with birth weight, muscle tone, heart and respiratory rate. In conclusion, antenatal betamethasone treatment reduces the need for ventilatory assistance in premature lambs. Additionally, mortality is low when a protocol for inducing pulmonary maturity (maternal corticosteroid therapy) and/or ventilatory interventions are employed, ensuring the survival of premature lambs., Competing Interests: Declaration of competing interest The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Challenges of the extrauterine environment can be life threatening for a premature fetus with inadequate fetal maturity. Maternal corticosteroids therapy is widely employed to induce fetal pulmonary maturation. Nevertheless, whenever therapeutic pregnancy interruption has to be performed in a time manner insufficient to treat the dam, postnatal corticotherapy can be considered an alternative. However, it is not known if antenatal and postnatal corticotherapy can improve similarly neonatal outcomes and pulmonary function. This research aimed to analyze antenatal and postnatal corticotherapy on premature lambs vitality, pulmonary functioning, metabolic and oxidative status. Lambs were evaluated according to the mode of treatment: Prenatal Corticosteroid Group (8 lambs born after maternal betamethasone treatment 48 h prior to birth), Postnatal Corticosteroid Group (9 lambs subjected to betamethasone treatment 10 min after birth) and Control Group (5 lambs remained untreated). Lambs were medically followed-up from birth to 72 h thereafter through a complete physical examination, as well as lactatemia, glycaemia, blood acid-base balance and antioxidant status. Treated lambs had higher vitality score than the Control Group. Heart rate was higher in postnatal therapy compared to prenatal treatment. Respiratory rate and rectal temperature were higher in treated groups. Treated lambs had hyperglycemia, while the Postnatal Group had higher lactatemia than the Control Group. The Prenatal Group had lower and normal pCO 2 from 60 min onwards. The Postnatal Group had higher superoxide dismutase activity than untreated lambs. In conclusion, prenatal and postnatal betamethasone treatments favor neonatal clinical outcome, respiratory function, glucose homeostasis and oxidative balance., Competing Interests: Declaration of competing interest The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Surfactant treatment is a manner to reduce alveolar superficial tension and increase pulmonary compliance in premature neonates. Thus, we aimed to analyze the effect of exogenous surfactant treatment in combination with manual ventilation for preterm lambs. We used 15 ewes and their lambs (n = 16), prematurely born at 135 days. At birth, lambs were submitted to orotracheal intubation attached to a handheld resuscitation device and randomly allocated to: Control Group (n = 5; only manual ventilation), Single Surfactant Group (n = 5; manual ventilation coupled by intratracheal administration of 100 mg/kg surfactant) and Double Surfactant Group (n = 6; surfactant volume was divided into two doses (50 mg/kg + 50 mg/kg) administrated at birth and 30 min thereafter). A complete physical exam, arterial gas analysis, blood glucose, urea and creatinine concentration and chest radiographic assessment were performed at fixed times. All lambs had decreased body temperature until 20 min after birth. However, control and double surfactant groups reached a thermic plateau after 30 min. Regardless of the time-point, control lambs had higher heart rate in comparison to treated neonates, including bradycardia in Single Surfactant Group. Single instillation led to lower oxygenation degree, compared to the Double Surfactant Group, suggesting that surfactant treatment was not able to adequately spread within the alveoli. Lambs treated with surfactant had severe impairment of aerobic activity, leading to anaerobic metabolism. All groups had hypercapnia, which can be explained by inadequate respiratory pattern and pulmonary opacity (89% of the lambs had severe or moderate lung content). In conclusion, exogenous surfactant therapy in association with manual ventilation is ineffective in reverting pulmonary immaturity of the preterm lamb, leading to less vitality, hypoxemia, delayed pulmonary clearance and high mortality rate., Competing Interests: Declaration of competing interest The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Among prematurity complications, the most important disorder is structural immaturity and inadequate production of pulmonary surfactant. Betamethasone is the drug of choice to artificially improve pulmonary capacity, thus we aimed to verify the effect of prenatal maternal treatment on lung development of premature puppies. Pregnant bitches were allocated in Term Group (n = 7), Preterm-Treated Group (interrupted pregnancies with maternal administration of betamethasone; n = 7), Preterm-Control Group (untreated interrupted pregnancies; n = 7), Extremely-Preterm Group (interrupted pregnancies at 55d; n = 6). Puppies were subjected to chest radiographic at birth, morphometric description of pulmonary structures and immunohistochemical analysis of surfactant protein B, proliferating cell nuclear antigen and cytokeratin were performed. In Preterm-Treated Group it was possible to more clearly identify cardiac silhouette and lung parenchyma by X-Ray. Saccular formation was higher in Preterm Groups, while Term Group had higher subsaccular development. Lung septation was higher in Treated and Term Groups. Term Group had higher number of cells marked for SP-B, whereas higher proliferation was observed in Extreme-Preterm and Preterm-Control Groups. Preterm Treated and Term Groups had higher tissue differentiation. In conclusion, antenatal maternal corticotherapy in dogs acted by increasing lung morphology and development of areas of gas exchange, regulate metabolism of pulmonary fluids rather than stimulate surfactant production., (Copyright © 2020 Elsevier Inc. All rights reserved.)

During pregnancy, fetal lambs are exposed to low oxygen tension. Thus, an effective antioxidant mechanism is partially developed which sensitizes fetus to oxidative stress. Consequently, term and preterm neonates are susceptible to molecular and cellular injury caused by oxygen species (ROS). This study aimed to evaluate the development of antioxidant enzymes and oxidative profile of preterm (135 days of pregnancy) and term (145 days of pregnancy) neonatal lambs, correlating with clinical analysis. Preterm lambs had significantly (P ≤ 0.05) lower score of vitality (4.00 ± 1.10), bradycardia (99 ± 34 bpm) and bradypnea (13 ± 10 mpm). However, both groups were normothermic and euglycemic. Preterm group had low blood pH (7.07 ± 0.10) and both groups had hypercapnia, more severe in preterm group (85.52 ± 18.65 mmHg). In addition, premature newborns had lower pO 2 (10.67 ± 5.65 mmHg) and SO 2 (6.17 ± 5.85%) values. No significant difference (P ≥ 0.05) on antioxidant enzymes and oxidative stress were verified among experimental groups, although glutathione peroxidase negatively correlated with Apgar score, heart rate, SO 2 and pO 2 . Our data show that preterm neonates are less adapted to the odds of labor and to overcome the immediate changes of extra-uterine life. Furthermore, we verified an influence of glutathione peroxidase in controlling oxidative stress, which highlights mature enzymatic mechanisms of cell redox, even in premature lambs., Competing Interests: The authors report no conflicts of interest.

Although the effects of antenatal corticosteroid therapy in clinical improvement and pulmonary maturation in preterm have been described, little is known on premature newborn puppies. This study aimed to evaluate the effect of maternal administration of a single dose of prenatal betamethasone on lung function of preterm newborn puppies in the first hours of life, especially from the clinical point of view and acid-base balance. A prospective study was conducted involving 21 puppies allocated into three experimental groups: Term Group (63 days post-ovulation), Preterm-Treated Group (57 days post-ovulation and maternal administration of a single dose of 0.5 mg/kg of betamethasone) and Preterm-Control Group (57 days post-ovulation). Puppies were analyzed clinically through the Apgar score, heart rate, respiratory rate and neurological tests (muscular tone and irritability reflex) and for oximetry and blood acid-base balance in distinct experimental moments. Premature puppies had marked degree of prematurity, reversed by maternal administration of betamethasone. Prenatal corticosteroid therapy promoted better pulmonary and metabolic condition, with more efficient compensatory response to acid-base imbalance and better pulmonary gas exchange capacity. Therefore, prenatal treatment with betamethasone can be adopted as clinical lung maturation protocol for pregnancies at risk in order to prevent low vitality and increase neonatal survival., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Sperm cryopreservation generates sperm damage and reduced fertilization capacity as a consequence of reactive oxygen species formation. Identifying the critical points of the process will contribute to the development of strategies for oxidative stress prevention. Therefore, the aim of this experiment was to verify the occurrence of oxidative stress during the two-step cryopreservation process in dogs. Six healthy mature dogs were used and submitted to the two-step sperm cryopreservation protocol. The sperm analysis was done at three time points: after refrigeration, after glycerolization, and after thawing by sperm motility, measurement of spontaneous and induced oxidative stress, sperm mitochondrial activity, plasma membrane integrity, flow cytometric evaluation of plasma and acrosome membrane integrity, mitochondrial membrane potential, and sperm chromatin structure assay. There was an increase in free radical production after glycerolization (87.4 ± 15.5 ng/mL of spontaneous thiobarbituric acid reactive substances (TBARS) after refrigeration and 1226.3 ± 256.0 ng/mL after glycerolization; P < 0.05), in association with loss of sperm mitochondrial activity. However, frozen-thawed samples had lower sperm motility, lower resistance to oxidative stress (448.7 ± 23.6 ng/mL of induced TBARS after glycerolization and 609.4 ± 35.9 ng/mL after thawing; P < 0.05) and increased lipid peroxidation (4815.2 ± 335.4 ng/mL of spontaneous TBARS after thawing; P < 0.05) as well as increased damage to plasma and acrosomal membranes, compared with refrigeration and glycerolization. In conclusion, the production of free radicals by sperm cells begins during glycerolization. However, sperm oxidative damage intensifies after thawing. Despite intracellular ice formation during cryopreservation, the increased production of reactive oxygen species can be the explanation of the decrease in sperm motility, reduced mitochondrial activity, and sperm plasma membrane and acrosomal damage., (Copyright © 2016 Elsevier Inc. All rights reserved.)

The aim of this study was to compare the in vitro and in vivo efficiency of different concentrations (0, 10 and 20 mM) of reduced glutathione supplemented to the extender for canine semen cryopreservation. Six normospermic dogs were used and each ejaculate was divided in 3 experimental groups, according to GSH concentration (GSH-0, GSH-10 and GSH-20 Groups). After thawing, samples were evaluated by sperm motility by computer-assisted sperm analysis (CASA), flow cytometric evaluation of plasma and acrosome membrane integrity, mitochondrial membrane potential and activity, chromatin susceptibility to acid-induced denaturation, and measurement of spontaneous and induced production of thiobarbituric acid reactive substances (TBARS). In vivo tests were carried out with GSH-0 and GSH-10 groups, for which six bitches were inseminated with semen cryopreserved in extender without GSH or containing 10 mM GSH. Intrauterine insemination was performed by cervical catheterization on the 5th and 6th days after the LH surge, detected by serum progesterone and LH assays. In the CASA evaluation, GSH-20 group had the lowest total and progressive motility and lower percentage of sperm with rapid and slow speed. Groups treated with glutathione showed lower percentage of acrosome damage, but higher percentage of plasma membrane injury. GSH-20 group had higher percentage of sperm with low mitochondrial activity and higher concentration of induced TBARS. Both groups (GSH-0 and GSH-10) had positive pregnancies. In conclusion, 20 mM GSH supplementation to canine cryopreservation extender promoted sperm damage, especially to mitochondrial activity. However, addition of 10 mM GSH resulted in acrosome protection, preserving fertility rate., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Spermatozoa become more susceptible to the attack of reactive oxygen species during maturation. To avoid oxidative damage, the epididymis must provide the necessary antioxidant protection. The aim of this study was to compare the canine sperm profile and the enzymatic antioxidant status of the ejaculated fractions and samples collected from the different segments of the epididymis (caput, corpus and cauda). Five adult dogs were used, and after 1-3 weeks, subsequently to bilateral orchiectomy and epididymal storage, sperm samples were collected from the different segments of the epididymis. Samples were evaluated for conventional microscopy and computer-assisted motility analysis: sperm plasma membrane permeability and the activity of the antioxidant enzymes catalase, glutathione peroxidase (GPx) and superoxide dismutase (SOD). Samples collected from the caput and corpus showed lower values for most of the motility variables evaluated, indicating different levels of immaturity. Catalase activity was observed only in ejaculated samples. Conversely, GPx activity was higher in the cauda epididymidis. Correlations were found between SOD and GPx and SOD and sperm motility in the epididymal cauda and corpus, highlighting the importance of the enzymes for the protection of spermatozoa during the transit along the epididymis., (© 2013 Blackwell Verlag GmbH.)