Francisco J. Alvarez

Lung Hypoplasia and Surfactant System Immaturity Induced in the Fetal Rat by Prenatal Exposure to Nitrofen

We studied the biochemical maturity of the lungs of fetuses born to rats exposed to nitrofen on day 9.5 of gestation. In comparison with controls, nitrofen-treated fetuses had pulmonary hypoplasia (decreased lung/body weight), lung hypocellularity (low DNA content) and cellular atrophy (low protein/DNA and phospholipid/DNA) on gestational days 19 and 21. Treated animals with congenital diaphragmatic hernia (CDH) also had cell atrophy and surfactant immaturity (decreased disaturated phosphatidylcholine/DNA) near term. Our data demonstrate that nitrofen causes lung hypoplasia and some degree of surfactant system immaturity that is particularly prominent in fetuses with CDH.

Cerebral blood flow and morphological changes after hypoxic-ischaemic injury in preterm lambs

AIM To evaluate the effect of cerebral hypoxia-ischaemia induced by partial occlusion of the umbilical cord on the relationship of the regional cerebral blood flow and the cerebral cell death in near-term fetal lambs. METHODS Fifteen near-term lambs were assigned to two hypoxic-ischaemic groups with or without life support (3 h), and a healthy one. Hypoxia-ischaemia was induced by partial occlusion of the umbilical cord (60 min). Routine light and electron microscopy, and the TUNEL method for apoptosis were performed. Regional cerebral blood flow was measured by coloured microspheres. Cardiovascular, gas exchange and pH parameters were also evaluated. RESULTS Both hypoxic-ischaemic groups produced a transient acidosis and a decrease of base excess in comparison to the healthy group. Cortical and cerebellar zones, where the regional cerebral blood flow values were similar to baseline, showed an increased number of oligodendrocyte-like apoptotic cells. In contrast, in the inner zones, where regional cerebral blood flow was increased, the number of apoptotic cells did not increase. Necrotic neurons were observed in the basal nuclei, mesencephalon, pons and deep cerebellar nuclei. CONCLUSION Our results suggest that regional cerebral blood flow and the presence of apoptotic cells, 3 h after hypoxic-ischemic injury, are correlated.

Pulmonary Surfactant Dysfunction in Congenital Diaphragmatic Hernia: Experimental and Clinical Findings

Experimental and clinical findings indicate immaturity of pulmonary surfactant in congenital diaphragmatic hernia (CDH). Lung histology has shown a decreased amount of lamellar bodies. A low lecithin/sphingomyelin ratio in the amniotic fluid, and decreased concentrations of surfactant protein A and disaturated phosphatidylcholine in the pulmonary tissue and the amniotic fluid have been reported. Furthermore, low compliance and high surface tension have also been found. Evidence of clinical and experimental findings of structural, biochemical and functional pulmonary immaturity in CDH is reviewed. Prenatal administration of corticosteroids to accelerate fetal pulmonary maturation, and the use of early surfactant therapy, should be further evaluated in the clinical management of CDH.

Procion orange tracer dye technique vs. identification of intrafibrillar fibronectin in the assessment of sarcolemmal damage

Background The use of Procion orange dye (POD) is one of the most widely accepted techniques to assess sarcolemmal damage. This phenomenon has been related to functional adaptation in skeletal muscles. The POD method includes intravenous injection of this colorant in vivo, enabling its identification inside those fibres with membrane leaks (fluorescence). However, the safety of the use of POD has not been proven.

Estructura básica de los músculos respiratorios y periféricos en el perro beagle

Fundamento Entre los modelos animales mas utilizados en estudios de fisiopatologia respiratoria se hallan los caninos, debido fundamentalmente a las caracteristicas fisiologicas del perro. Sin embargo, consideraciones eticas y legales restringen su utilizacion en nuestro medio a unas pocas especies Objetivo Hemos estudiado las caracteristicas estructurales basicas de musculos respiratorios y perifericos en el perro beagle, con el fin de aproximar sus valores de referencia para futuros estudios Metodo Se han incluido 14 animales jovenes de esa raza, en los que se tomaron muestras musculares del diafragma costal (DFG), intercostal externo (IE) y musculo de una extremidad (vasto interno) (PF). Se analizaron los porcentajes y tamanos fibrilares (inmunohistoquimica, anticuerpos anti-cadenas pesadas de miosina o MyHC), porcentaje y cantidad de las isoformas de MyHC (electroforesis y ELISA), y grado de dano de membrana (inmunohistoquimica, anti-cuerpos antifibronectina) Resultados Las fibras eran mayores en el IE, sobre todo a expensas de las de tipo II (un 20% mayores). Las fibras resistentes a la fatiga (tipo I) predominaban ampliamente sobre las de contraccion rapida (tipo II) en los 3 musculos analizados (DFG, 57 ± 11 frente a 45 ± 12; IE, 58 ± 5 frente a 43 ± 5, y PF, 70 ± 8 frente a 34 ± 7%). La cantidad de fi-bras hibridas (coexpresion de MyHC rapidas y lentas) era minima y similar en los tres musculos. La expresion absoluta de MyHC era mayor en el PF que en los musculos respiratorios, con predominio relativo de la isoforma I en DFG y PF, y tendencia similar en el IE. El dano de membrana era muy reducido en los tres musculos Conclusiones Las caracteristicas fenotipicas de los musculos respiratorios y PF en el perro beagle responden a lo es-perable funcionalmente en una raza seleccionada inicialmente para la caza, con minimos grados de lesion en circunstancias normales, predominio de fibras y proteinas resistentes a la fatiga y fibras mayores en el IE, un musculo que desempena un papel relevante en la respiracion de los perros

Liquid Ventilation: From Experimental Use to Clinical Application

Despite advances in perinatal care of preterm infants, complications of prematurity are still common. If new conventional ventilatory interventions fail, ECMO is the only alternative method, but is a complex, invasive and costly technique and difficult to apply to small infants. Perfluorocarbon liquid ventilation is a promising technique. It has been demonstrated to be effective in experimental models, in mature and immature animals. However, its role in the management of human neonates, infants, older children and adults with acute respiratory failure is still not established. Both liquid ventilation strategies, total and partial, are able not only to maintain gas exchange, but also to reduce inflammatory changes. While total liquid ventilation remains as an experimental technique, partial liquid ventilation could be readily applied, but its implementation in clinical practice awaits results from ongoing and future clinical trials that may define its effectiveness.

Differential uptake of systemic fluorochrome Hoechst 33342 in lung and liver metastasis of B16 melanoma

The growth and vascularization patterns of B16 melanoma colonies in the liver and lungs were measured and compared by histological techniques and dye diffusion patterns after injection of the fluorochrome Hoechst 33342. In the liver, the fluorescent pattern of dye diffusion revealed that uninodular tumours measuring up to 146 μn in diameter were not functionally vascularized. However, when the nodules fused to give rise to multinodular tumours measuring between 256 and 366 μn in diameter, a reticular dye diffusion pattern revealed functional tumour vascularization. In the lungs, subpleural, parenchymal and peritubular (i.e. surrounding blood vessels and airways) tumours were observed. The two former classes were vascularized down to thicknesses and diameters of 49 and 24 μm respectively. In contrast, dye diffusion was never seen in peritubular tumour cuffs up to 609 μm in thickness. The results indicate differences in vascularization patterns in B16 tumours in the liver and lungs, and differences between tumours growing in different sites within the lungs. If these results are applicable to metastases in these two organs, they indicate potential diffusion-mediated resistance to chemotherapy, and potential hypoxia-mediated resistance to radiotherapy of both metastases and micrometastases.

The Newborn at High Risk of Brain Damage

Despite marked improvements in perinatal practice, perinatal brain injury remains one of the most common complications causing chronic handicapping conditions. Experimental advances have elucidated many of the cellular and vascular mechanisms of perinatal brain damage showing a correlation between the nature of the injury and the maturation of the brain. New diagnostic tools, such as quantitative three-dimensional magnetic resonance (MR) imaging, diffusion-weighted MR imaging and proton MR spectroscopy, are presented in this review article that allow to assess brain development, detect early brain injury and monitor effects of perinatal brain injury on subsequent brain development and brain plasticity. These techniques will guide future therapeutic interventions aimed at minimizing irreversible perinatal brain injury.

COMPARISON OF TOTAL (TLV) AND PARTIAL (PLV) LIQUID VENTILATION WITH PERFLUOROCARBON (PFC). 1611

COMPARISON OF TOTAL (TLV) AND PARTIAL (PLV) LIQUID VENTILATION WITH PERFLUOROCARBON (PFC). 1611

Morpho-functional study of vascular fluorochrome delivery to lung and liver metastases of Lewis lung carcinoma (3LL).

The growth of 3LL liver and lung metastases related to Its vascular organization was studied by morphological and functional methods, using the Hoechst 33342 fluorescent DNA staining technique. Experimental liver and lung metastases were produced in syngeneic C57BL/6 mice by injection of 3LL tumor cells into a lateral tail vein or into the spleen, respectively. The resulting neoplasms were composed of large cells arranged in sheets with a thin irregularly distributed stroma. Scattered blood vessels with an open or closed lumen were observed within the tumor. Functional study of H33342 diffusion showed a single and reticular fluorescent pattern in liver metastases. In contrast, in lung metastases the fluorochrome diffusion revealed two different fluorescent patterns related to the location of the metastasis. Thus, parenchymal and subpleural metastasis presented a fluorescent pattern similar to that observed in the liver whereas metastases located around blood vessels and conducting airways never displayed fluorescence. In summary, our results suggest that the target metastatic organ and/or intra-organ location modulates the characteristics of metabolic exchange of the tumor cells In relation to the vascular organization of the metastatic focus.