Deferoxamine Improves Alveolar and Pulmonary Vascular Development by Upregulating Hypoxia-inducible Factor-1alpha in a Rat Model of Bronchopulmonary Dysplasia

Fetal lung development normally occurs in a hypoxic environment. Hypoxia-inducible factor (HIF)-1alpha is robustly induced under hypoxia and transactivates many genes that are essential for fetal development. Most preterm infants are prematurely exposed to hyperoxia, which can halt hypoxia-driven lung maturation. We were to investigate whether the HIF-1alpha inducer, deferoxamine (DFX) can improve alveolarization in a rat model of bronchopulmonary dysplasia (BPD). A rat model of BPD was produced by intra-amniotic lipopolysaccharide (LPS) administration and postnatal hyperoxia (85% for 7 days), and DFX (150 mg/kg/d) or vehicle was administered to rat pups intraperitoneally for 14 days. On day 14, the rat pups were sacrificed and their lungs were removed and examined. A parallel in vitro study was performed with a human small airway epithelial cell line to test whether DFX induces the expression of HIF-1alpha and its target genes. Alveolarization and pulmonary vascular development were impaired in rats with BPD. However, DFX significantly ameliorated these effects. Immunohistochemical analysis showed that HIF-1alpha was significantly upregulated in the lungs of BPD rats treated with DFX. DFX was also found to induce HIF-1alpha in human small airway epithelial cells and to promote the expression of HIF-1alpha target genes. Our data suggest that DFX induces and activates HIF-1alpha, thereby improving alveolarization and vascular distribution in the lungs of rats with BPD.

Acute and subchronic toxicological evaluation of Echinophora platyloba DC (Apiaceae) total extract in Wistar rats

OBJECTIVE: Echinophora platyloba DC is a widely used herbal medicine and food seasoning in Iran. It is claimed to exert antimicrobial, antifungal, and antispasmodic effects. Despite the prevalent use of this plant as a food and medicine, there are no reports on its possible toxic effects. To evaluate the safety of E. platyloba, we tested its acute and sub-chronic toxicity in male and female Wistar rats. METHODS: Rats were orally treated with four different single doses of E. platyloba total extract and screened for signs of toxicity two weeks after administration. In the sub-chronic toxicity study, E. platyloba was administered for 45 days. Mortality, clinical signs, body weight changes, hematological and biochemical parameters, gross findings, organ weights, and histological markers were monitored during the study. RESULTS: We found no mortality and no abnormality in clinical signs, body weight, or necropsy findings in any of the animals in the acute study. The results of the subchronic study showed no significant difference in hematological parameters in either sex. There was a significant increase in lactate dehydrogenase in the female groups. A significant increase in the relative lung weight of female rats was noted at 500 mg/kg. Histopathological examinations revealed intra-alveolar hemorrhage in the male rats (500 mg/kg). In the females, congestion of the alveolar capillaries (at 500 mg/kg) and liver bridging necrosis (at 200 mg/kg) were significantly increased. CONCLUSION: The no observed adverse effect level of E. platyloba was determined to be 200 and 50 mg/kg for male and female rats, respectively.

Effects of Postnatal Dexamethasone or Hydrocortisone in a Rat Model of Antenatal Lipopolysaccharide and Neonatal Hyperoxia Exposure

The aim of our study was to investigate the differential effects of dexamethasone (DXM) and hydrocortisone (HCS) on somatic growth and postnatal lung development in a rat model of bronchopulmonary dysplasia (BPD). A rat model of BPD was induced by administering intra-amniotic lipopolysaccharide (LPS) and postnatal hyperoxia. The rats were treated with a 6-day (D1-D6) tapering course of DXM (starting dose 0.5 mg/kg/day), HCS (starting dose 2 mg/kg/day), or an equivalent volume of normal saline. DXM treatment in a rat model of BPD induced by LPS and hyperoxia was also associated with a more profound weight loss compared to control and LPS + O2 groups not exposed to corticosteroid, whereas HCS treatment affected body weight only slightly. Examination of lung morphology showed worse mean cord length in both LPS + O2 + DXM and LPS + O2 + HCS groups as compared to the LPS + O2 alone group, and the LPS + O2 + DXM group had thicker alveolar walls than the LPS + O2 group at day 14. The HCS treatment was not significantly associated with aberrant alveolar wall thickening and retarded somatic growth. The use of postnatal DXM or HCS in a rat model of BPD induced by intra-amniotic LPS and postnatal hyperoxia appeared detrimental to lung growth, but there was less effect in the case of HCS. These findings suggest that effect of HCS on somatic growth and pulmonary outcome may be better tolerated in neonates for preventing and/or treating BPD.

Efeitos da hiperóxia sobre o pulmão de ratos Wistar / Effects of hyperoxia on Wistar rat lungs

OBJETIVO: Avaliar a repercussão da elevada concentração de oxigênio (hiperóxia) em um curto período de tempo no pulmão de ratos Wistar. MÉTODOS: Os animais foram divididos em grupos O10', O30', O90', ou seja, ratos expostos à hiperóxia por 10', 30' e 90', respectivamente, e no grupo controle (GC), exposto ao ar ambiente. Os animais foram sacrificados 24 h após a exposição. O lavado broncoalveolar foi realizado e os pulmões foram retirados para análise histológica e estereológica. RESULTADOS: Observamos um aumento do número de macrófagos (2169,9 ± 118,0, 1560,5 ± 107,0 e 1467,6 ± 39,0) e neutrófilos (396,3 ± 35,4, 338,4 ± 17,3 e 388,7 ± 11,7), concomitante a um aumento do dano oxidativo (143,0 ± 7,8 por cento, 180,4 ± 5,6 por cento e 235,0 ± 13,7 por cento) nos grupos O10', O30' e O90', respectivamente, quando comparados ao GC (781,3 ± 78,3 por cento, 61,6 ± 4,2 por cento e 100,6 ± 1,7 por cento). Na análise histológica e estereológica foram observados alvéolos e septos normais no GC (83,51 ± 1,20 por cento e 15 ± 1,21 por cento), no grupo O10' (81,32 ± 0,51 por cento e 16,64 ± 0,70 por cento) e no grupo O30' (78,75 ± 0,54 por cento e 17,73 ± 0,26 por cento). Entretanto, no grupo O90' foi notado um influxo de células inflamatórias nos alvéolos e nos septos alveolares. Hemácias extravasaram do capilar para o alvéolo (59,06 ± 1,22 por cento), com evidências de congestão, hemorragia e edema de septo (35,15 ± 0,69 por cento). CONCLUSÃO: Os resultados indicam que a hiperóxia induziu uma ação lesiva no grupo O90' sobre o parênquima pulmonar, com repercussões de dano oxidativo e infiltrado inflamatório.

OBJECTIVE: To study the effects of short-term exposure to high oxygen concentrations (hyperoxia) on Wistar rat lungs. METHODS: Animals were divided into three groups exposed to hyperoxia for 10', 30' and 90' (O10', O30', O90', respectively), together with a control group (exposed to room air). The animals were sacrificed 24 h after exposure. Bronchoalveolar lavage was performed, and the lungs were removed for histological and stereological analysis. RESULTS: In the O10', O30', and O90' groups, respectively and in comparison with the controls, we observed an increase in the numbers of macrophages (2169.9 ± 118.0, 1560.5 ± 107.0, and 1467.6 ± 39.0 vs. 781.3 ± 78.3) and neutrophils (396.3 ± 35.4, 338.4 ± 17.3, and 388.7 ± 11.7 vs. 61.6 ± 4.2), concomitant with an increase in oxidative damage (143.0 ± 7.8 percent, 180.4 ± 5.6 percent, and 235.0 ± 13.7 vs. 100.6 ± 1.7 percent). The histological and stereological analyses revealed normal alveoli and alveolar septa in the controls (83.51 ± 1.20 percent and 15 ± 1.21 percent), in the O10' group (81.32 ± 0.51 percent and 16.64 ± 0.70 percent), and in the O30' group (78.75 ± 0.54 percent and 17.73 ± 0.26 percent). However, in the O90' group, inflammatory cell infiltration was observed in the alveoli and alveolar septa. Red blood cells extravasated from capillaries to the alveoli (59.06 ± 1.22 percent), with evidence of congestion, hemorrhage, and septal edema (35.15 ± 0.69 percent). CONCLUSION: Hyperoxia for 90' caused injury of the lung parenchyma, resulting in oxidative damage and inflammatory cell infiltration.

Edema pulmonar de altura: Modelo de estudio de la fisiopatología del edema pulmonar y de la hipertensión pulmonar hipóxica en humanos / High altitude pulmonary edema. An experiment of Nature to study the underlying mechanisms of hypoxic pulmonary hypertension and pulmonary edema in humans

La altura, fascinante laboratorio natural de investigación médica, provee resultados con importantes implicancias para la comprensión de enfermedades que afectan a millones de personas que viven en ella, asi como para el tratamiento de enfermedades ligadas a la hipoxemia en pacientes que viven en baja altitud. El edema pulmonar de altura (EPA) es una entidad que pone en peligro la vida y que ocurre en sujetos predispuestos pero sanos. Esto permite estudiar los mecanismos subyacentes del edema pulmonar en humanos, sin la presencia de factores que presten a la confusión como enfermedades concomitantes. El EPA resulta de la conjunción de dos defectos mayores: acumulación de líquido en el espacio alveolar debido a una hipertensión pulmonar hipóxica exagerada, y alteración en la eliminación del mismo por un defecto en el transporte transepitelial alveolar de sodio. En esta revisión, describimos brevemente las características clínicas y revisaremos este novedoso concepto. Proveemos evidencia experimental de como la síntesis alterada de óxido nítrico y/o la disminución de su biodisponibilidad representan el defecto central que predispone a la vasoconstricción pulmonar hipóxica exagerada y a la acumulación de líquido en el espacio alveolar. Mostramos que la hipertensión pulmonar hipóxica exagerada, per se, no es suficiente para producir un EPA, y que una alteración en la eliminación del fluido del espacio alveolar representa un segundo mecanismo fisiopatológico importante. Finalmente, describimos cómo los nuevos aportes obtenidos de los estudios del EPA pueden ser trasladados al manejo de otros estados patológicos ligados a la hipoxemia.

High altitude constitutes an exciting natural laboratory for medical research. Over the past decade, it has become clear that the results of high-altitude research may have important implications not only for the understanding of diseases in the millions of people living permanently at high altitude, but also for the treatment of hypoxemia-related disease states in patients living at low altitude. High-altitude pulmonary edema (HAPE) is a life-threatening condition occurring in predisposed, but otherwise healthy subjects, and, therefore, allows to study underlying mechanisms of pulmonary edema in humans, in the absence of confounding factors. Over the past decade, evidence has accumulated that HAPE results from the conjunction of two major defects, augmented alveolar fluid flooding resulting from exaggerated hypoxic pulmonary hypertension, and impaired alveolar fluid clearance related to defective respiratory transepithelial sodium transport. Here, after a brief presentation of the clinical features of HAPE, we review this novel concept. We provide experimental evidence for the novel concept that impaired pulmonary endothelial and epithelial nitric oxide synthesis and/or bioavailability may represent the central underlying defect predisposing to exaggerated hypoxic pulmonary vasoconstriction and alveolar fluid flooding. We demonstrate that exaggerated pulmonary hypertension, while possibly a condition sine qua non, may not be sufficient to cause HAPE, and how defective alveolar fluid clearance may represent a second important pathogenic mechanism. Finally, we outline how this insight gained from studies in HAPE may be translated into the management of hypoxemia related disease states in general.

new anti-rheumatic drug leflunomide [Avara] and the associated risk of pulmonary toxicity: a histological study on the alveoli of albino rats

Leflunomide [Avara] is a novel drug for the treatment of active rheumatoid arthritis. The controversy about the associated risk of respiratory infection in patients treated with leflunomide was the main drive for the present study. The present study aimed to demonstrate the histological changes that might occur in the alveolar structure of the lung in rats treated with leflunomide for 4 weeks and to investigate the effect of stoppage of drug administration for another 2 weeks. The present work was conducted on 30 adult male albino rats which were divided into 3 equal groups; group I [control group], group II [leflunomide treated group] which received leflunomide in an oral dose of 10mg/kg for 4 weeks. Group III [withdrawal group] the rats received the leflunomide treatment in a similar way to group II, then they were kept without treatment for another 2 weeks to test for possible spontaneous recovery. By the end of the experimental period, the animals were sacrificed and specimens from the lungs were taken, processed and examined by light and transmission electron microscopes. Examination of leflunomide treated group revealed marked alteration in the histological structure, as many alveoli appeared collapsed with evident thickening of the inter-alveolar septa which showed cellular infiltration and congested blood capillaries. Some red blood cells were seen extravasated in the alveolar spaces. Hyperplasia ofpneumocyte type II which appeared with empty lamellar bodies and pyknotic nuclei were depicted. Stoppage of drug administration for 2 weeks after treatment, did not succeed in restoration of the normal histological structure of the alveoli. On the contrary, severe cellular infiltration of the inter-alveolar septa were observed in the withdrawal group. The alveolar air spaces were seen obliterated surrounded with many pneumocytes type II which showed morphological changes including enlarged cells with swollen mitochondria. Plasma cells, lymphocytes, eosinophils, many degenerated ill-defined cells, multiple fibroblasts and excess collagen were seen. Trichrome stain also revealed excess collagen deposition in both leflunomide treated group and in the withdrawal group. The present results revealed that leflunomide induced lung toxicity with evident histological changes in the alveoli which mimicked that of interstitial pneumonitis. On the other hand, discontinuation of the drug for another 2 weeks did not succeed in spontaneous recovery or amelioration of these changes, most probably through its pharmacokinetics as regards the long half life of elimination of the drug and the increased risk of opportunistic infection

effect of different doses of oral tizanidine, on the minimum alveolar concentration of isoflurane and stress response

Alpha2-ADRENERGIC receptor agonists bind to peripheral and central nervous system sites modulating autonomio nervous system function. These effects may explain the clinically observed attenuation of sympathetically mediated responses to perioperative stress. They also have an antinociceptive effect in animals in humans premedicated with oral tizanidine an alpha2-adrenoceptor agonist, attenuated the increase in blood pressure associated with laryngoscopy and intubation and the amount of midazolam required for loss of consciousness was significantly reduced. We speculated that the oral administration of tizanidine might reduce the minimum alveolar anesthetic concentration [MAC] of isoflurane. Eighty ASA physical status patients, aged 24-56 yr, were randomly allocated into 4 groups [20 for each]: a Control group and a 2mg Tizanidine group, 4mg Tizanidine group, 10mg Tizanidine group. As premedication, the Control group received a placebo, and the Tizanidine groups received oral tizanidine 70 min. before surgical skin incision. Anesthesia was induced in all patients by propofol 2-2.5 mg/kg intravenously mixed with tidocaine 0.3 mg/kg, given over 30s. until loss of eyelid reflex [determined every 15 s]. After loss of consciousness, appropriate size of laryngeal mask was introduced by Brain method. Then administration of isoflurane was begun; the patients were spontaneously ventilated using a non-rebreathing system. MAC was determined by a technique adapted from the conventional up-down method for quanta! responses. The MAC of isoflurane was 1.3 +/- 0.13in the Control group, 1.24 +/- 0.1 in group It. 0.9 +/- 0.2 in grouplll and 0 7 +/- 0.2 in group IV. In group III and IV the plasma concentrations of epinephrine and norepinephrine were statistically significantly decreased during surgery and remained decreased thereafter. The oral administration of tizanidine successfully reduced the MA C of isoflurane, decreased the release of stress hormones and decreased the postoperative analgesic requirements in human adults

Histamine induced decrease of lecithin levels in broncho-alveolar lavage fluid of rats is mediated by H2 receptor.

Lecithin, a major surface active substance of the surfactant system of the lung, was estimated in broncho-alveolar lavage (BAL) fluid in four groups of healthy adult male albino rats. Rats from group I were not administered any drug and acted as controls. Group II were administered histamine diphosphate. Group III were given H1 blocker (pyrilamine maleate) followed by histamine diphosphate. Group IV received H2 blocker (ranitidine hydrochloride) followed by histamine diphosphate. Lecithin content of BAL fluid in the control group was compared with that in the other three groups. A significant decrease in lecithin content was observed in the rats that received either histamine diphosphate or H1 blocker followed by histamine diphosphate. However, compared to control rats no significant difference in lecithin content was seen in rats that received H2 blocker followed by histamine diphosphate. The results clearly indicate that the decrease in surface active lecithin content in BAL fluid following administration of histamine diphosphate was unaffected by prior administration of H1 blocker, but was blocked by prior administration of H2 blocker. It was concluded that histamine induced decrease in lecithin content of BAL fluid is mediated through H2 receptors. Since the predominant source of intra-alveolar lecithin are Type II cells of the alveolar epithelium, It is possible that Type II cells have H2 receptors, stimulation of which resulted in decreased intraalveolar lecithin.

Interleucinas 1ß, 6 y 10 y el daño tisular post-perfusión y post-reperfusión pulmonar / Interleukins 1ß, 6 y 10 and tissue damage by pulmonary perfusion and reperfusion

Introducción: La síntesis y la liberación de citocinas se afectan por efecto de la perfusión y de la reperfusión de órganos. Objetivo: En este trabajo, se obtuvo un índice numérico para cada una de las interleucinas detectadas 1b, 6 y 10 en la solución de perfusión y en el tejido pulmonar de bloques pulmonares perfundidos y reperfundidos para correlacionarlo con los hallazgos microscópicos encontrados en dichos bloques. Material y Métodos: Se utilizaron los bloques pulmonares de 21 ratones Balb-C divididos al azar en tres grupos de estudio (n = 7 en cada grupo). Grupos 1: Los bloques fueron perfundidos in situ a través de la arteria pulmonar con solución de Krebs-Henseleit a 4ºC con un flujo de perfusión de 0.2 mL/min únicamente durante el tiempo necesario para exanguinarlos; Grupo 2: Los bloques fueron perfundidos in situ durante 30' a través de la arteria pulmonar con solución de Krebs-Henseleit a 4ºC con un flujo de perfusión de 0.2 mL/min y Grupo 3: Los bloques fueron exanguinados mediante perfusión in situ a través de la arteria pulmonar con solución de Krebs-Henseleit a 4ºC con un flujo de perfusión de 0.2 mL/min, se preservaron durante 24 horas a 4ºC sumergidos en la misma solución y transcurrido el tiempo de isquemia, fueron reperfundidos ex vivo durante 30' con solución de Krebs-Henseleit a 4ºC con un flujo de perfusión, la solución de perfusión se recolectó a través de un catéter conectado en el ventrículo izquierdo. Concluidas las perfusiones y las reperfusiones se disecó el bloque pulmonar, utilizando el resto de los lóbulos para la preparación de homogeneizados. La concentración de las interleucinas en la solución de perfusión y en el homogeneizado tisular, fue determinada mediante la técnica de ELISA. Se realizaron estas concentraciones, calculando un índice para cada interleucina y correlacionando con los hallazgos microscópicos. Resultados: No existen correlaciones importantes entre los índices calculados para cada una de las interleucinas con la mayoria de los hallazgos histológicos, con exepción de que parece existir una correlación negativa entre el índice calculado para la interleucina 10 y la ruptura alveolar por daño mecánico (-0.35), enfisema (-0.38) e inflamación (-0.68, p <0.01)

Enfisema pulmonar experimental en la rata: fenómenos inflamatorios y progresión del daño pulmonar / Experimental pulmonary emphysema in the rat: inflammatory phenomena and progression of lung damage

Background: Although the hamster model of elastase induced emphysema is well characterized, the rat model has received less attention. Aim: To evaluate the effect of a single intratracheal elastase dose on lung pathological changes of Sprague-Dawley rats. Material and methods: Rats were injected with a single intratracheal elastase dose of 28 U/100 g body weight or saline and studied 7, 15, 30 and 365 days after injection. Results: Forty percent of rats died in the first 48 hours after injection, six were sacrificed at 7 days, 6 at 15 days, 7 at 30 days and 12 at 365 days. Progressive centroacinar emphysema was found from day 7 after elastase, with a persistent inflammatory reaction in the vicinity of emphysematous areas. Conclusions: Present findings differ from the panacinar emphysema described in the hamster using a similar elastase dose

Proteínas pulmonares asociadas a sustancias con actividad surfactante7 / Pulmonary proteins associated to substances with surfactant activity

La ausencia de surfactantes pulmonares trae como consecuencia el incremento de la tensión superficial a lo largo del epitelio alveolar, provocando un colapso alveolar y la lisis de las células epiteliales. Este proceso culmina con la aparición de un síndrome de insuficiencia respiratoria, que es la causa principal de morbimortalidad en niños prematuros. Recientemente, la aplicación de mezclas de agentes surfactantes con fines terapéuticos ha constituido un gran apoyo para la terapia respiratoria, ya que permite una evolución más rápida de los niños que padecen este síndrome. Por todo esto, resulta de gran importancia el conocimiento más detallado de la función, el metabolismo y la regulación de la expresión genética de las proteíinas surfactantes, para el diseño de nuevas y mejores estrategias terapéuticas para combatir este síndrome

Fundamentos técnicos y físicos para la administración de óxido nitroso en la Ciudad de México / Rationale for use of nitrous oxide

Siempre se ha especulado que a una altura de 2 200 metros sobre el nivel del mar la presión parcial alveolar del óxido nitroso es insuficiente para permitir su difusión a través de la membrana alvéol-capilar y, por tanto, hay imposibilidad para lograr las concentraciones sanguíneas necesarias para el estado anestésico sin trastornar seriamente el aporte de oxígeno a la célula. En el Hospital Central Militar, desde el decenio de 1970, previa eliminación del nitrógeno alveolar mediante flujos altos, se ha administrado con resultados excelentes óxido nitroso en combinación con otros fármacos ya sea por vía parenteral o pulmonar. Después, al reducir el flujo total y aplicar óxido nitroso a través de un circuito semicerrado o semiabierto evitan las pérdidas excesivas de agua, temperatura y bióxido de carbono, a la vez que se abate el grado de contaminación ambiental, y de esta forma aumenta el ahorro de anestésicos halogenados