Machine Learning-Assisted Raman Spectroscopy for pH and Lactate Sensing in Body Fluids.

This study presents the combination of Raman spectroscopy with machine learning algorithms as a prospective diagnostic tool capable of detecting and monitoring relevant variations of pH and lactate as recognized biomarkers of several pathologies. The applicability of the method proposed here is tested both in vitro and ex vivo. In a first step, Raman spectra of aqueous solutions are evaluated for the identification of characteristic patterns resulting from changes in pH or in the concentration of lactate. The method is further validated with blood and plasma samples. Principal component analysis is used to highlight the relevant features that differentiate the Raman spectra regarding their pH and concentration of lactate. Partial least squares regression models are developed to capture and model the spectral variability of the Raman spectra. The performance of these predictive regression models is demonstrated by clinically accurate predictions of pH and lactate from unknown samples in the physiologically relevant range. These results prove the potential of our method to develop a noninvasive technology, based on Raman spectroscopy, for continuous monitoring of pH and lactate in vivo.

aEEG and neurologic exam findings correlate with hypoxic-ischemic brain damage severity in a piglet survival model.

BACKGROUND: Newborn pigs offer theoretical advantages for studying newborn hypoxic-ischemic (HI) brain damage because of a development and structure similar to the human brain. However, the correlation between functional features and actual HI brain damage has not been reported. METHODS: Newborn pigs were examined daily for 3 days after a HI insult using amplitude-integrated EEG (aEEG), and a neurobehavioral score enriched with stress and social and object interaction-driven activity evaluation. Brain damage was then assessed using histologic, immunohistochemical, and proton magnetic resonance spectroscopy studies. Brain concentration of several neurotransmitters was determined by HPLC. RESULTS: HI insult led to aEEG amplitude decrease, muscle tone and activity impairment, eating disorders, poor environmental interaction, and increased motionless periods. Basal aEEG amplitude, muscle tone, and general behavior were the best predictive items for histological and biochemical (lactate/N-acetylaspartate ratio) brain damage. Hyperexcitable response to stress correlated inversely with brain damage. Motionless time, which correlated with brain damage severity, was inversely related to brain concentration of dopamine and norepinephrine. CONCLUSION: Standard neurologic examination of brain activity and motor and behavioral performance of newborn pigs is a valuable tool to assess HI brain damage, thus offering a powerful translational model for HI brain damage pathophysiology and management studies.

Cannabidiol reduces lung injury induced by hypoxic-ischemic brain damage in newborn piglets.

BackgroundBrain hypoxic-ischemic (HI) damage induces distant inflammatory lung damage in newborn pigs. We aimed to investigate the effects of cannabidiol (CBD) on lung damage in this scenario.MethodsNewborn piglets received intravenous vehicle, CBD, or CBD+WAY100635 (5-HT1A receptor antagonist) after HI brain damage (carotid flow interruption and FiO2 0.10 for 30 min). Total lung compliance (TLC), oxygenation index (OI), and extravascular lung water content (EVLW) were monitored for 6 h. Histological damage, interleukin (IL)-1ß concentration, and oxidative stress were assessed in brain and lung tissue. Total protein content was determined in bronchoalveolar lavage fluid (BALF).ResultsCBD prevented HI-induced deleterious effects on TLC and OI and reduced lung histological damage, modulating inflammation (decreased leukocyte infiltration and IL-1 concentration) and reducing protein content in BALF and EVLW. These effects were related to CBD-induced anti-inflammatory changes in the brain. HI did not increase oxidative stress in the lungs. In the lungs, WAY100635 blunted the beneficial effects of CBD on histological damage, IL-1 concentration, and EVLW.ConclusionsCBD reduced brain HI-induced distant lung damage, with 5-HT1A receptor involvement in these effects. Whether the effects of CBD on the lungs were due to the anti-inflammatory effects on the brain or due to the direct effects on the lungs remains to be elucidated.

Hypoxic-ischemic brain damage induces distant inflammatory lung injury in newborn piglets.

BACKGROUND: We aimed to investigate whether neonatal hypoxic-ischemic (HI) brain injury induces inflammatory lung damage. METHODS: Thus, hypoxic (HYP, FiO2 10% for 30 min), ischemic (ISC, bilateral carotid flow interruption for 30 min), or HI event was performed in 1-2-d-old piglets. Dynamic compliance (Cdyn), oxygenation index (OI), and extravascular lung water (EVLW) were monitored for 6 h. Then, histologic damage was assessed in brain and lung (lung injury severity score). Total protein content (TPC) was determined in broncoalveolar lavage fluid (BALF), and IL-1ß concentration was measured in lung and brain tissues and blood. RESULTS: Piglets without hypoxia or ischemia served as controls (SHM). HI-induced brain damage was associated with decreased Cdyn, increased OI and EVLW, and histologic lung damage (interstitial leukocyte infiltration, congestive hyperemia, and interstitial edema). BALF TPC was increased, suggesting inflammatory damage. In agreement, tissue IL-1ß concentration increased in the brain and lung, in correspondence with increased IL-1ß serum concentration. Neither HYP nor ISC alone led to brain or lung damage. CONCLUSION: HI brain damage in newborn piglets led to inflammatory lung damage, suggesting an additional mechanism accounting for the development of lung dysfunction after neonatal HI encephalopathy.

Progenitor Cell Sources for 3D Bioprinting of Lymphatic Vessels and Potential Clinical Application.

The lymphatic system maintains tissue fluid homeostasis and it is involved in the transport of nutrients and immunosurveillance. It also plays a pivotal role in both pathological and regenerative processes. Lymphatic development in the embryo occurs by polarization and proliferation of lymphatic endothelial cells from the lymph sacs, that is, lymphangiogenesis. Alternatively, lymphvasculogenesis further contributes to the formation of lymphatic vessels. In adult tissues, lymphatic formation rarely occurs under physiological conditions, being restricted to pathological processes. In lymphvasculogenesis, progenitor cells seem to be a source of lymphatic vessels. Indeed, mesenchymal stem cells, adipose stem cells, endothelial progenitor cells, and colony-forming endothelial cells are able to promote lymphatic regeneration by different mechanisms, such as direct differentiation and paracrine effects. In this review, we summarize what is known on the diverse stem/progenitor cell niches available for the lymphatic system, emphasizing the potential that these cells hold for lymphatic tissue engineering through 3D bioprinting and their translation to clinical application.

Effects of Cannabidiol, Hypothermia, and Their Combination in Newborn Rats with Hypoxic-Ischemic Encephalopathy.

Therapeutic hypothermia is well established as a standard treatment for infants with hypoxic-ischemic (HI) encephalopathy but it is only partially effective. The potential for combination treatments to augment hypothermic neuroprotection has major relevance. Our aim was to assess the effects of treating newborn rats following HI injury with cannabidiol (CBD) at 0.1 or 1 mg/kg, i.p., in normothermic (37.5°C) and hypothermic (32.0°C) conditions, from 7 d of age (neonatal phase) to 37 d of age (juvenile phase). Placebo or CBD was administered at 0.5, 24, and 48 h after HI injury. Two sensorimotor (rotarod and cylinder rearing) and two cognitive (novel object recognition and T-maze) tests were conducted 30 d after HI. The extent of brain damage was determined by magnetic resonance imaging, histologic evaluation, magnetic resonance spectroscopy, amplitude-integrated electroencephalography, and Western blotting. At 37 d, the HI insult produced impairments in all neurobehavioral scores (cognitive and sensorimotor tests), brain activity (electroencephalography), neuropathological score (temporoparietal cortexes and CA1 layer of hippocampus), lesion volume, magnetic resonance biomarkers of brain injury (metabolic dysfunction, excitotoxicity, neural damage, and mitochondrial impairment), oxidative stress, and inflammation (TNFα). We observed that CBD or hypothermia (to a lesser extent than CBD) alone improved cognitive and motor functions, as well as brain activity. When used together, CBD and hypothermia ameliorated brain excitotoxicity, oxidative stress, and inflammation, reduced brain infarct volume, lessened the extent of histologic damage, and demonstrated additivity in some parameters. Thus, coadministration of CBD and hypothermia could complement each other in their specific mechanisms to provide neuroprotection.

Comparative effects of bronchoalveolar lavage with saline, surfactant, or perfluorocarbon in experimental meconium aspiration syndrome.

OBJECTIVE: Today, in meconium aspiration syndrome, treatment focuses on bronchoalveolar lavage, because it removes meconium and proinflammatory factors from airways. This technique might be more effective if different solutions were used such as saline solution, a protein-free surfactant, or a perfluorocarbon, because these would be less inhibited by meconium proteins. SETTING: Pulmonary physiology research unit, Cruces Hospital. DESIGN: Prospective, randomized study. SUBJECTS: We studied 24 lambs (<6 days) on mechanical ventilation for 180 mins. Catheters were placed and femoral and pulmonary arteries pressures registered (systemic and pulmonary arterial pressures). INTERVENTIONS: Lambs were instilled with 20% meconium (3-5 mL/Kg) and were randomly assigned to one of the following groups (n = 6): control: only continuous mechanical ventilation; saline bronchoalveolar lavage: bronchoalveolar lavage with 30 mL/kg of saline solution; dilute surfactant bronchoalveolar lavage: bronchoalveolar lavage with 32 mL/kg of diluted surfactant (lucinactant, 10 mg/mL); or perfluorocarbon bronchoalveolar lavage: bronchoalveolar lavage with 30 mL/kg of perfluorocarbon. MEASUREMENTS AND MAIN RESULTS: Blood gases, cardiovascular parameters, and pulmonary mechanics were assessed. Meconium instillation produced severe hypoxia, hypercapnia, acidosis, and pulmonary hypertension with impairment of pulmonary mechanics (p < .05). Lung lavage with dilute surfactant resulted in the resolution of pulmonary hypertension as well as better gas exchange and pulmonary mechanics than the control group (p < .05). Bronchoalveolar lavage with perfluorocarbon produced a transient improvement in gas exchange and ventilatory indices in comparison with control and saline bronchoalveolar lavage groups. CONCLUSIONS: In lambs with meconium aspiration syndrome, bronchoalveolar lavage with diluted lucinactant is an effective therapy producing significant improvements in gas exchange, pulmonary hypertension, and pulmonary mechanics. In addition, bronchoalveolar lavage with perfluorocarbon appears to confer some advantages over lavage with equal volumes of saline or no lavage.

Identification of Hypoxia-Ischemia by Chemometrics Considering Systemic Changes of Physiology.

Perinatal asphyxia represents a major medical disorder and is related to around a fourth of all neonatal deaths worldwide. Specific thresholds for lactate or pH levels define the gold standard for detecting hypoxic-ischemic events as physiological abnormalities. In contrast to current gold standard, we analyze the systemic picture, represented by the whole set of biochemical parameters from blood gas analysis, by multiparametric machine learning algorithms. In a swine model with 22 objects, we investigate the impact of neonatal hypoxic-ischemic encephalopathy on 18 individual physiological parameters. In a first approach, we study the statistical significance of individual parameters by univariate analysis methods. In a second approach, we take the most relevant parameters as input for the development of predictive models by different hybrid and non-hybrid classification algorithms. The predictive power of our multiparametric models outperforms by far the limited performance of pH and lactate as reliable indicators, despite strong correlation with hypoxic-ischemic events. We have been able to detect hypoxic-ischemic events even one hour after the episode, with accuracies close to 100% in contrast to pH or lactate-based diagnosis with 62% and 78%, respectively. By all machine learning algorithms, lactate is recognized as the main contributor due to its longer-term evidence of hypoxia-ischemia episodes. However, substantial improvement of the diagnosis is achieved by predictions based on a systemic picture of different physiological parameters. Our results prove the potential applicability of our method as a support tool for decision-making that will allow obstetricians to identify hypoxic-ischemic episodes more accurately during labor.

Photonic Technology for In Vivo Monitoring of Hypoxia-Ischemia.

Surveillance of physiological parameters of newborns during delivery triggers medical decision-making, can rescue life and health, and helps avoid unnecessary cesareans. Here, the development of a photonic technology for monitoring perinatal asphyxia is presented and validated in vivo in a preclinical stage. Contrary to state of the art, the technology provides continuous data in real-time in a non-invasive manner. Moreover, the technology does not rely on a single parameter as pH or lactate, instead monitors changes of the entirety of physiological parameters accessible by Raman spectroscopy. By a fiber-coupled Raman probe that is in controlled contact with the skin of the subject, near-infrared Raman spectra are measured and analyzed by machine learning algorithms to develop classification models. As a performance benchmarking, various hybrid and non-hybrid classifiers are tested. In an asphyxia model in newborn pigs, more than 1000 Raman spectra are acquired at three different clinical phases-basal condition, hypoxia-ischemia, and post-hypoxia-ischemia stage. In this preclinical proof-of-concept study, figures of merit reach 90% levels for classifying the clinical phases and demonstrate the power of the technology as an innovative medical tool for diagnosing a perinatal adverse outcome.

Cannabidiol reduces brain damage and improves functional recovery after acute hypoxia-ischemia in newborn pigs.

Newborn piglets exposed to acute hypoxia-ischemia (HI) received i.v. cannabidiol (HI + CBD) or vehicle (HI + VEH). In HI + VEH, 72 h post-HI brain activity as assessed by amplitude-integrated EEG (aEEG) had only recovered to 42 ± 9% of baseline, near-infrared spectroscopy (NIRS) parameters remained lower than normal, and neurobehavioral performance was abnormal (27.8 ± 2.3 points, normal 36). In the brain, there were fewer normal and more pyknotic neurons, while astrocytes were less numerous and swollen. Cerebrospinal fluid concentration of neuronal-specific enolase (NSE) and S100ß protein and brain tissue percentage of TNFα(+) cells were all higher. In contrast, in HI + CBD, aEEG had recovered to 86 ± 5%, NIRS parameters increased, and the neurobehavioral score normalized (34.3 ± 1.4 points). HI induced histological changes, and NSE and S100ß concentration and TNFα(+) cell increases were suppressed by CBD. In conclusion, post-HI administration of CBD protects neurons and astrocytes, leading to histological, functional, biochemical, and neurobehavioral improvements.

Cell therapy as a treatment of secondary lymphedema: a systematic review and meta-analysis.

BACKGROUND: Lymphedema, the accumulation of interstitial fluid caused by poor lymphatic drainage, is a progressive and permanent disease with no curative treatment. Several studies have evaluated cell-based therapies in secondary lymphedema, but no meta-analysis has been performed to assess their efficacy. METHODS: We conducted a systematic review and meta-analysis of all available preclinical and clinical studies, with assessment of their quality and risk of bias. RESULTS: A total of 20 articles using diverse cell types were selected for analysis, including six clinical trials and 14 pre-clinical studies in three species. The meta-analysis showed a positive effect of cell-based therapies on relevant disease outcomes (quantification of edema, density of lymphatic capillaries, evaluation of the lymphatic flow, and tissue fibrosis). No significant publication bias was observed. CONCLUSION: Cell-based therapies have the potential to improve secondary lymphedema. The underlying mechanisms remain unclear. Due to relevant heterogeneity between studies, further randomized controlled and blinded studies are required to substantiate the use of these novel therapies in clinical practice.

Neuroprotective effects of the nonpsychoactive cannabinoid cannabidiol in hypoxic-ischemic newborn piglets.

To test the neuroprotective effects of the nonpsychoactive cannabinoid cannabidiol (CBD), piglets received i.v. CBD or vehicle after hypoxia-ischemia (HI: temporary occlusion of both carotid arteries plus hypoxia). Nonhypoxic-ischemic sham-operated piglets remained as controls. Brain damage was studied by near-infrared spectroscopy (NIRS) and amplitude-integrated electroencephalography (aEEG) and by histologic assessment (Nissl and FluoroJadeB staining). In HI+vehicle, HI led to severe cerebral hemodynamic and metabolic impairment, as reflected in NIRS by an increase in total Hb index (THI) and a decrease in the fractional tissue oxygenation extraction (FTOE); in HI+CBD the increase of THI was blunted and FTOE remained similar to SHAM. HI profoundly decreased EEG amplitude, which was not recovered in HI+vehicle, indicating cerebral hypofunction; seizures were observed in all HI+vehicle. In HI+CBD, however, EEG amplitude recovered to 46.4 7.8% baseline and seizures appeared only in 4/8 piglets (both p < 0.05). The number of viable neurons decreased and that of degenerating neurons increased in HI+vehicle; CBD reduced both effects by more than 50%. CBD administration was free from side effects; moreover, CBD administration was associated with cardiac, hemodynamic, and ventilatory beneficial effects. In conclusion, administration of CBD after HI reduced short-term brain damage and was associated with extracerebral benefits.

Effects of Cannabidiol and Hypothermia on Short-Term Brain Damage in New-Born Piglets after Acute Hypoxia-Ischemia.

Hypothermia is a standard treatment for neonatal encephalopathy, but nearly 50% of treated infants have adverse outcomes. Pharmacological therapies can act through complementary mechanisms with hypothermia improving neuroprotection. Cannabidiol could be a good candidate. Our aim was to test whether immediate treatment with cannabidiol and hypothermia act through complementary brain pathways in hypoxic-ischemic newborn piglets. Hypoxic-ischemic animals were randomly divided into four groups receiving 30 min after the insult: (1) normothermia and vehicle administration; (2) normothermia and cannabidiol administration; (3) hypothermia and vehicle administration; and (4) hypothermia and cannabidiol administration. Six hours after treatment, brains were processed to quantify the number of damaged neurons by Nissl staining. Proton nuclear magnetic resonance spectra were obtained and analyzed for lactate, N-acetyl-aspartate and glutamate. Metabolite ratios were calculated to assess neuronal damage (lactate/N-acetyl-aspartate) and excitotoxicity (glutamate/Nacetyl-aspartate). Western blot studies were performed to quantify protein nitrosylation (oxidative stress), content of caspase-3 (apoptosis) and TNFα (inflammation). Individually, the hypothermia and the cannabidiol treatments reduced the glutamate/Nacetyl-aspartate ratio, as well as TNFα and oxidized protein levels in newborn piglets subjected to hypoxic-ischemic insult. Also, both therapies reduced the number of necrotic neurons and prevented an increase in lactate/N-acetyl-aspartate ratio. The combined effect of hypothermia and cannabidiol on excitotoxicity, inflammation and oxidative stress, and on cell damage, was greater than either hypothermia or cannabidiol alone. The present study demonstrated that cannabidiol and hypothermia act complementarily and show additive effects on the main factors leading to hypoxic-ischemic brain damage if applied shortly after the insult.

Effect of neonatal asphyxia on the impairment of the auditory pathway by recording auditory brainstem responses in newborn piglets: a new experimentation model to study the perinatal hypoxic-ischemic damage on the auditory system.

INTRODUCTION: Hypoxia-ischemia (HI) is a major perinatal problem that results in severe damage to the brain impairing the normal development of the auditory system. The purpose of the present study is to study the effect of perinatal asphyxia on the auditory pathway by recording auditory brain responses in a novel animal experimentation model in newborn piglets. METHOD: Hypoxia-ischemia was induced to 1.3 day-old piglets by clamping 30 minutes both carotid arteries by vascular occluders and lowering the fraction of inspired oxygen. We compared the Auditory Brain Responses (ABRs) of newborn piglets exposed to acute hypoxia/ischemia (n = 6) and a control group with no such exposure (n = 10). ABRs were recorded for both ears before the start of the experiment (baseline), after 30 minutes of HI injury, and every 30 minutes during 6 h after the HI injury. RESULTS: Auditory brain responses were altered during the hypoxic-ischemic insult but recovered 30-60 minutes later. Hypoxia/ischemia seemed to induce auditory functional damage by increasing I-V latencies and decreasing wave I, III and V amplitudes, although differences were not significant. CONCLUSION: The described experimental model of hypoxia-ischemia in newborn piglets may be useful for studying the effect of perinatal asphyxia on the impairment of the auditory pathway.

Mechanisms of cannabidiol neuroprotection in hypoxic-ischemic newborn pigs: role of 5HT(1A) and CB2 receptors.

The mechanisms underlying the neuroprotective effects of cannabidiol (CBD) were studied in vivo using a hypoxic-ischemic (HI) brain injury model in newborn pigs. One- to two-day-old piglets were exposed to HI for 30 min by interrupting carotid blood flow and reducing the fraction of inspired oxygen to 10%. Thirty minutes after HI, the piglets were treated with vehicle (HV) or 1 mg/kg CBD, alone (HC) or in combination with 1 mg/kg of a CB2 receptor antagonist (AM630) or a serotonin 5HT(1A) receptor antagonist (WAY100635). HI decreased the number of viable neurons and affected the amplitude-integrated EEG background activity as well as different prognostic proton-magnetic-resonance-spectroscopy (H(±)-MRS)-detectable biomarkers (lactate/N-acetylaspartate and N-acetylaspartate/choline ratios). HI brain damage was also associated with increases in excitotoxicity (increased glutamate/N-acetylaspartate ratio), oxidative stress (decreased glutathione/creatine ratio and increased protein carbonylation) and inflammation (increased brain IL-1 levels). CBD administration after HI prevented all these alterations, although this CBD-mediated neuroprotection was reversed by co-administration of either WAY100635 or AM630, suggesting the involvement of CB2 and 5HT(1A) receptors. The involvement of CB2 receptors was not dependent on a CBD-mediated increase in endocannabinoids. Finally, bioluminescence resonance energy transfer studies indicated that CB2 and 5HT(1A) receptors may form heteromers in living HEK-293T cells. In conclusion, our findings demonstrate that CBD exerts robust neuroprotective effects in vivo in HI piglets, modulating excitotoxicity, oxidative stress and inflammation, and that both CB2 and 5HT(1A) receptors are implicated in these effects.

Surfactant and perfluorocarbon aerosolization during different mechanical ventilation strategies by means of inhalation catheters: an in vitro study.

BACKGROUND: Aerosol delivery of surfactant and perfluorocarbon (PFC) is a desirable therapeutic approach for the treatment of various lung diseases in patients undergoing mechanical ventilation. However, the behavior of these substances during aerosolization differs significantly from that of aqueous solutions. In particular, the high vapor pressure of many PFCs tends to result in greater evaporation during mechanical ventilation. METHODS: Three PFCs and surfactant were aerosolized during mechanical ventilation by means of three intratracheal inhalation catheters (IC) with different air flow rates (IC-1.23, IC-1.1, and IC-1.4), with their aerosol generating tip placed at the distal end of the endotracheal tube (i.d. 4 mm). The influence of four different ventilation strategies on aerosol production rate and PFC and surfactant recovery was studied. The changes in intrapulmonary pressure produced by the air jets of each IC were measured. RESULTS: With IC-1.23 and IC-1.1, the highest rates of aerosol production were achieved using FC75 (2.27±0.18 and 0.76±0.01, respectively) followed by PFOB (1.74±0.06 and 0.56±0.04), PFD (0.82±0.01 and 0.21±0.01), and surfactant (0.42±0.05 and 0.092±0.01). With IC-1.4 modest aerosol production was obtained irrespective of the aerosolized compound. Mechanical ventilation influenced aerosol recovery, with the trend being toward recovering higher percentages of the compounds with lower peak inspiratory pressure (PIP) and lower respiratory rate (RR) settings. The highest percentages of the initial volume were recovered with IC-1.23 (between 65.43%±4.2 FC75 and 90.21%±4.71 surfactant) followed by IC-1.1 (between 46.48%±4.46 FC75 and 73.19%±2.82 PFOB) and IC-1.4 (between 4.65%±4.36 FC75 and 63.24%±9.71 surfactant). Each of three of the ICs were found to increase the intrapulmonary pressure by about 2-3 cmH2O during mechanical ventilation. CONCLUSIONS: Despite of mechanical ventilation, IC-1.23 and IC-1.1 were able to deliver significant amounts of surfactant and perfluorocarbon to the lung model. Changes in PIP and RR directly influence the percentage of surfactant and perfluorocarbon recovered.

Surfactant and perfluorocarbon aerosolization by means of inhalation catheters for the treatment of respiratory distress syndrome: an in vitro study.

BACKGROUND: The aerosolization of perfluorocarbons or surfactant has emerged as a feasible alternative to instillation, for the treatment of experimental respiratory distress syndrome. However, the biophysical properties that make these compounds useful in such therapies, significantly affect the performance of nebulizers. Therefore, in vitro studies are required to assess the suitability of new aerosolization technologies for use with these compounds. METHODS: The aim of the present in vitro study was to investigate the influence of the biophysical properties of perfluorocarbons (PFD, FC75, and PFOB) and a natural porcine surfactant, Curosurf®; on aerosolization and to assess the suitability of three intratracheal inhalation catheters (IC) with different air flow rates (IC-1.23, IC-1.1, IC-1.4) coupled to a jet nebulizer, for aerosol delivery of these compounds. RESULTS: With IC-1.23 significantly higher aerosol production rates were achieved (p < 0.0001), ranging between 6.05 ± 0.17 mL/min (FC75) and 1.94 ± 0.09 mL/min (Curosurf®), and lower percentage losses of the compound (5-21%), compared to IC-1.1 and IC-1.4 catheters. The lowest aerosolization rates were produced with IC-1.4 ranging from 0.58 ± 0.02 mL/min (FC75) to 0.14 ± 0.01 mL/min (Curosurf®), and this catheter also resulted in the highest percentage losses (25-60%). The mass median aerodynamic diameter (MMAD) ranged between 0.77 µm (PFD) and 8.29 µm (Curosurf®) with IC-1.1, whereas higher MMAD values, of between 4.84 µm (FC75) and 13.42 µm (PFOB), were observed with IC-1.23. Regardless of the catheter used during aerosolization, the perfluorocarbon with the highest kinematic viscosity showed the lowest aerosolization and emission rates and vice versa, which reveals the substantial contribution of this parameter that should accordingly be considered in the design of perfluorocarbon aerosol drug delivery systems. CONCLUSIONS: Jet aerosolization of perfluorocarbons or surfactant with the intratracheal inhalation catheters seems to be a suitable method for treating experimental respiratory distress syndrome, because it delivers relatively high doses of perfluorocarbons and surfactant to the lungs in a respirable size droplets.

Early Cerebral Hemodynamic, Metabolic, and Histological Changes in Hypoxic-Ischemic Fetal Lambs during Postnatal Life.

The hemodynamic, metabolic, and biochemical changes produced during the transition from fetal to neonatal life may be aggravated if an episode of asphyxia occurs during fetal life. The aim of the study was to examine regional cerebral blood flow (RCBF), histological changes, and cerebral brain metabolism in preterm lambs, and to analyze the role of oxidative stress in the first hours of postnatal life following severe fetal asphyxia. Eighteen chronically instrumented newborn lambs were randomly assigned to either a control group or the hypoxic-ischemic (HI) group, in which case fetal asphyxia was induced just before delivery. All the animals were maintained on intermittent positive pressure ventilation for 3 h after delivery. During the HI insult, the injured group developed acidosis, hypoxia, hypercapnia, lactic acidosis, and tachycardia (relative to the control group), without hypotension. The intermittent positive pressure ventilation transiently improved gas exchange and cardiovascular parameters. After HI injury and during ventilatory support, there continued to be an increased RCBF in inner regions among the HI group, but no significant differences were detected in cortical flow compared to the control group. Also, the magnitude of the increase in TUNEL positive cells (apoptosis) and antioxidant enzymes, and decrease of ATP reserves was significantly greater in the brain regions where the RCBF was not higher. In conclusion, our findings identify early metabolic, histological, and hemodynamic changes involved in brain damage in premature asphyxiated lambs. Such changes have been described in human neonates, so our model could be useful to test the safety and the effectiveness of different neuroprotective or ventilation strategies applied in the first hours after fetal HI injury.