Selective retinoid X receptor agonism promotes functional recovery and myelin repair in experimental autoimmune encephalomyelitis.

Evidence that myelin repair is crucial for functional recovery in multiple sclerosis (MS) led to the identification of bexarotene (BXT). This clinically promising remyelinating agent activates multiple nuclear hormone receptor subtypes implicated in myelin repair. However, BXT produces unacceptable hyperlipidemia.

Inhibition of apoptosis by p26: implications for small heat shock protein function during Artemia development.

p26, an abundantly expressed small heat shock protein, is thought to establish stress resistance in oviparously developing embryos of the crustacean Artemia franciscana by preventing irreversible protein denaturation, but it might also promote survival by inhibiting apoptosis. To test this possibility, stably transfected mammalian cells producing p26 were generated and their ability to resist apoptosis induction determined. Examination of immunofluorescently stained transfected 293H cells by confocal microscopy demonstrated p26 is diffusely distributed in the cytoplasm with a minor amount of the protein in nuclei.

A 49 kDa microtubule cross-linking protein from Artemia franciscana is a coenzyme A-transferase.

Embryos and larvae of the brine shrimp, Artemia franciscana, were shown previously to possess a protein, now termed p49, which cross-links microtubules in vitro. Molecular characteristics of p49 were described, but the protein's identity and its role in the cell were not determined. Degenerate oligonucleotide primers designed on the basis of peptide sequence obtained by Edman degradation during this study were used to generate p49 cDNAs by RT-PCR and these were cloned and sequenced.

Microanatomical changes in alveolar type II cells in juvenile mice intratracheally exposed to Stachybotrys chartarum spores and toxin.

Stachybotrys chartarum is an important environmental fungus. We have shown recently that alveolar type II cells are sensitive to exposure to Stachybotrys chartarum spores and to the trichothecene, isosatratoxin-F, both in vitro and in vivo, in a juvenile mouse model. This sensitivity is manifest as significant changes in the composition and normal metabolic processing of pulmonary surfactant.

Comparative effects of chronic exposure to glucose or sodium butyrate on surfactant development in fetal rabbits.

Background: Infants of diabetic mothers (IDM) often have delayed lung development and are thus at an increased risk of Respiratory Distress Syndrome (RDS). Both hyperglycemia and/or hyperinsulinemia have been implicated in this delay but the precise mechanism has not been clarified. Another metabolite, sodium butyrate, which is increased in IDM has been shown to decrease surfactant production in vitro but its effects on the development of the fetal lung surfactant system in vivo have not been studied.

Effects of Stachybotrys chartarum on surfactant convertase activity in juvenile mice.

We have shown recently that alveolar type II cells are sensitive to exposure to Stachybotrys chartarum spores, both in vitro and in an in vivo juvenile mouse model. In mice, this sensitivity is manifest in part as a significant increase in the newly secreted, biologically active, heavy aggregate form of alveolar surfactant (H) and the accumulation of the lighter, "metabolically used", biologically inactive alveolar surfactant forms (L(vivo)) in the interalveolar space. Conversion of the heavy, surface-active alveolar surfactant to the light metabolically used, nonsurface active forms is believed to involve the activity of an enzyme, namely convertase, which is thought to be derived from lamellar bodies (LB) in alveolar type II cells.

Analysis of pulmonary surfactant by Fourier-transform infrared spectroscopy following exposure to Stachybotrys chartarum (atra) spores.

Lung cells are among the first tissues of the body to be exposed to air-borne environmental contaminants. Consequently the function of these cells may be altered before other cells are affected. As gas exchange takes place in the lungs, changes in cellular function may have serious implications for the processes of oxygen uptake and carbon dioxide elimination.

Alveolar metabolism of natural vs. synthetic surfactants in preterm newborn rabbits.

We compared the recoveries of four surfactant preparations: two natural [term fetal rabbit surfactant (FRS) and adult rabbit surfactant (ARS)] and two commercially available preparations [apoprotein-based Survanta (S) and synthetic Exosurf (E)] from 27-day gestation rabbit pups treated at birth and ventilated up to 120 min. At 5, 60, and 120 min, we measured the recovery of the heavy-aggregate, metabolically active form (H) and the light-aggregate, nonsurface active metabolic breakdown form (L) of alveolar surfactant and determined the phospholipid content and composition of the intracellularly stored lamellar body (LB) pool. Pups treated with FRS had <15% loss of H by 2 h.

Calcium-PS-dependent protein kinase C and surfactant protein A in isolated fetal rabbit type II alveolar cells and surfactant-related material.

The fetal lung secretes significant quantities of surfactant during late gestation to prepare for initiation of respiration at birth. However, the mechanism by which this occurs has not been determined. Since Ca2+-phosphatidylserine (PS)-dependent protein kinase C has been implicated in surfactant secretion in adult lung, the present study was done to determine whether this enzyme is also involved in the initiation of surfactant release from fetal type II cells.

Convertase activity in alveolar surfactant and lamellar bodies in fetal, newborn, and adult rabbits.

Conversion of heavy-aggregate alveolar surfactant (H) to a light-aggregate, nonsurface active form (L) is believed to involve the activity of an enzyme, namely, convertase. This conversion can be reproduced in vitro by the surface-area cycling technique. The purpose of the present study was to use this technique to investigate the developmental aspects of convertase activity in fetal, newborn, and adult rabbits.

Effects of Stachybotrys chartarum (atra) conidia and isolated toxin on lung surfactant production and homeostasis.

This study evaluated the effects of Stachybotrys chartarum conidia and a trichothecene, isosatratoxin-F, on choline incorporation into DSPC by fetal rabbit alveolar type II cells and on alveolar surfactant subtypes in mice. Exposure of fetal rabbit type II cells to S. chartarum conidia at concentrations of 10(3) to 10(6) conidia ml(-1) significantly depressed [3H] choline incorporation after 24 h of exposure.

Methylmercury-induced alterations in lung and pulmonary surfactant properties of adult mice.

Exposure to methylmercuric chloride (MMC) has been shown to significantly affect development of the lung and pulmonary surfactant system of the fetus. Preliminary results suggest it may also affect adult lung and associated bronchoalveolar lavage (BAL), which represents the extracellular surfactant pool. To determine if mercury exposure has the potential to alter surfactant function, adult mice were treated with MMC, 15 mg/kg by intragastric intubation on 4 successive days.

Fourier-transform infrared spectroscopic analysis of rabbit lung surfactant: subfraction-associated phospholipid and protein profiles.

Surfactant obtained from bronchoalveolar lavage (BAL) can be separated into subfractions based on sedimentation characteristics. It has been suggested that the 10,000 x g, 60,000 x g and 100,000 x g subfractions isolated by this approach represent stages of surfactant extracellular processing. These three subfractions have been reported to differ in their morphology, composition and ability to lower surface tension.

Effects of smoke inhalation on alveolar surfactant subtypes in mice.

The effects of smoke inhalation on alveolar surfactant subtypes were examined in mice exposed for 30 minutes to smoke generated from the burning of a flexible polyurethane foam. At 4 or 12 hours after the exposure, three surfactant pellets, P10, P60, and P100, and a supernatant, S100, were prepared by sequential centrifugation of lavage fluids at 10,000 g for 30 minutes (P10), 60,000 g for 60 minutes (P60), and 100,000 g for 15 hours (P100 and S100). Phospholipid analysis and electron microscopy were performed on each fraction.

Mouse alveolar surfactant: characterization of subtypes prepared by differential centrifugation.

To characterize the properties of alveolar surfactant subfractions obtained from mouse lung by differential centrifugation, lavage fluid, following a preliminary centrifugation at 140 x g for 5 min to yield a cellular pellet (Pc), was sequentially centrifuged at 10,000 x g for 30 min, 60,000 x g for 60 min and 100,000 x g for 15 h; and the resultant pellets, respectively referred to as P10, P60 and P100, were harvested for electron microscopy, phospholipid analysis and surface tension measurements. Ultrastructural differences were observed, in that P10 contained large multilamellated structures which were typical of newly secreted surfactant, P100 contained small unilamellar vesicular structures, typical of catabolic end products of alveolar surfactant and P60 appeared to contain a mixture of structures present in P10 and P100 in addition to numerous, large unilamellar vesicles which were not present in either P10 or P100. Slight but significant differences were found in the phospholipid compositions of the three subfractions but not in the fatty acid composition of their phosphatidylcholine (PC) component.

Increased inorganic sulfate concentrations in amniotic fluid.

We assayed inorganic sulfate by ion chromatography in 49 amniotic fluid samples from pregnancies of 14 to 38 weeks gestation. In second trimester samples (14 to 26 weeks gestation), amniotic fluid sulfate concentrations (317 +/- 22 mumol/L, mean +/- SE; n = 32) were not different from previously reported maternal serum values but were significantly lower (p < 0.001) than in the third trimester (693 +/- 42 mumol/L; n = 16).

Effects of smoke inhalation on surfactant phospholipids and phospholipase A2 activity in the mouse lung.

The effects of smoke inhalation on the pulmonary surfactant system were examined in mice exposed for 30 minutes to smoke generated from the burning of polyurethane foam. At 8 or 12 hours after exposure, surfactants were isolated separately from lung lavage (extracellular surfactant) and residual lung tissue (intracellular surfactant) for phospholipid analysis. Calcium-dependent phospholipase A2 (PLA2) was measured on a microsomal fraction prepared from the tissue homogenate.

Autoradiographic localization and effects of exogenous radioactively labelled surfactant in the lung of the prematurely delivered fetal rabbit.

Adult rabbit lung surfactant was radioactively labelled with [3H]palmitate and isolated by centrifugation. This material was instilled into the trachea of fetal rabbits prematurely delivered on the 27th gestational day. A similar preparation of unlabelled surfactant was used to measure the effects on pressure-volume characteristics in lungs of 27th day fetuses.

Correlation of absorbance at 650 nm with the presence of phosphatidylglycerol in amniotic fluid.

Amniotic fluid absorbance at 650 nm was correlated with the presence of phosphatidylglycerol (PG) in the isolated surfactant fraction (10,000-g pellet). Shake test results were included. Two hundred ninety-seven samples were analyzed.

Gestation-dependent effects of the combined treatment of glucocorticoids and thyrotropin-releasing hormone on surfactant production by fetal rabbit lung.

The effects of cortisol (0.1 mg per dose, administered intraperitoneally to fetal rabbits at 24 to 27 days' gestation), thyrotropin-releasing hormone (40 micrograms/kg per dose administered intravenously to the doe at 24 to 26 days' gestation), or a combination of the two on surfactant pool size (both intracellular and extracellular) at 27 or 28 days' gestation was investigated. Cortisol increased both surfactant pools only when administered on the twenty-fourth or twenty-fifth gestational day.

Pulmonary toxicity of trichloroethylene: induction of changes in surfactant phospholipids and phospholipase A2 activity in the mouse lung.

Trichloroethylene (TCE) is a common organic solvent in use as a dry cleaning agent as well as an inhalant anesthetic. Nevertheless the effects of this material on the pulmonary surfactant which prevents alveolar collapse at maximal expiration is not known. Therefore, we have examined the effect of TCE on the intra- and extracellular surfactant pools and the activity of phospholipase A2, an enzyme which controls the remodeling of phosphatidylcholine to dipalmitoylphosphatidylcholine, the primary constituent of the pulmonary surfactant.

Beta-adrenergic-induced surfactant synthesis, secretion, and reutilization in fetal rabbit lung and isolated differentiating type II alveolar cells.

In vivo and in vitro approaches were used to examine the role of beta-adrenergic agonists in the regulation of surfactant synthesis and secretion in the lung. Rabbit fetuses of either 28 or 30 gestational days were treated with isoxsuprine. Fetuses from half of the does in each group were removed and allowed to breathe for 30 minutes.

Subcellular distribution of disaturated phosphatidylcholine in developing rabbit lung.

To determine the subcellular distribution of disaturated phosphatidylcholine (DSPC) in lung tissue during perinatal development, fetal rabbits at 24, 26, 28 and 31 (term) days gestation and newborns were studied. Following alveolar lavage, fractions enriched in nuclei-cellular debris, mitochondria, microsomes, surfactant (lamellar bodies) and cytosol were prepared from the residual tissue homogenate, and their DSPC content was determined. The DSPC content of the unfractionated residual lung tissue homogenate progressively and significantly increased during fetal development, rising from 9.

Characterization and comparison of the role of beta-agonists on in vivo and in vitro surfactant-related phospholipid synthesis and secretion by fetal rabbit lung and isolated type II alveolar cells.

The role of beta-adrenergic stimulation in surfactant synthesis and secretion was investigated in the fetal lung. Fetuses were treated with isoxsuprine or saline on gestational day 24 by ip injection. Three days later the fetal lungs were lavaged and intracellular surfactant was isolated on a sucrose gradient.

Profile of phospholipase A2 activity in subcellular fractions and lamellar bodies of developing, neonatal and adult rabbit lung. Correlation with intracellular levels of disaturated phosphatidylcholine.

Phospholipase A2 activity was determined in subcellular fractions and lamellar bodies of fetal, neonatal and adult rabbit lungs. Specific activity in most fractions decreased from the 24th to the 28th day of gestation. All fractions except the mitochondrial and the nuclear fractions exhibited a sharp increase in activity in the newborn lung.