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Biomedical subjects

M Hallman

Publications and source records attributed to M Hallman.

At least 199 records · Page 11Linked to original sources
PubMed1976

Phosphatidylinositol and phosphatidylglycerol in amniotic fluid: indices of lung maturity.

The minor phospholipids in amniotic fluid from normal pregnancies were correlated with the well-established index of lung maturity, the lecithin/sphingomyelin (L/S) ratio. When the L/S ratio was less than 1.0, the acidic phospholippids phosphatidylglycerol (PG) and phosphatidylinositol (PI) were absent or low in concentration (0.0 to 2.5 per cent of lipid phosphorus). Parallel to the increase in the L/S ratio to 2.0, the content of PI increased 6.0 to 8.5 per cent of lipid phosphorus. PG, the unique phospholipid of lung surfactant, first appeared and PI concomitantly decreased when the L/S ratio exceeded 2.0, indicating the secretion of mature lung surfactant. Analysis of PI and PG in amniotic fluid as markers of surfactant seems to be of value as an additional index of prenatal evaluation of lung maturity and may be particularly useful when the specimen is contaminated with blood.

Amniotic Fluid↗
PubMed1976

Phosphatidylglycerol in lung surfactant. III. Possible modifier of surfactant function.

Lamellar bodies and alveolar lavage from adult mammalian lung contain unusually high concentrations of phosphatidylglycerol that could serve as a sensitive indicator of surfactant. Phosphatidylglycerol was absent and phosphatidylinositol was correspondingly prominent in surfactant from the preterm rabbit fetus. Phosphatidylglycerol rapidly appeared and phosphatidylinositol decreased following the delivery. Surfactant isolated from the prematurely born rabbit or from humans with respiratory distress syndrome never contained phosphatidylglycerol. Comparison between lamellar bodies from fetal and postnatal rabbits revealed remarkably similar composition except for the acidic phospholipids; however, the physico-chemical properties were different. The compressibility of the surface film (i.e. the ratio of the fractional decrease in surface area and the corresponding decrease in surface tension) at low surface tensions was higher with fetal than with postnatal surfactant, whereas the difference in minimum surface tensions was small. These data suggest that phosphatidylglycerol is not an essential component required for the formation of the complex, but it improves the properties of surfactant in stabilizing the alveoli.

Aging↗
PubMed1976

Isolated lamellar bodies from rat lung: correlated ultrastructural and biochemical studies.

Lamellar bodies isolated from rat lung homogenates were prepared for electron microscopy by two methods: OsO4 fixation followed by dehydration either with acetone or ethanol. Electron microscopy revealed that the acetone-dehydrated fraction contained many well preserved lamellar bodies with intact outer membrane, and the high retention of a material of low electron density between the fine and closely spaced concentric lamellae. This appearance was contrasted by the increased loss of this interlamellar material and coarse and irregularly spaced lamellae in the ethanol-dehydrated fraction. The supernatants from each respective fixation and dehydration were collected for lipid and protein analyses in an attempt to correlate any detected biochemical difference with a correspondingly modified ultrastructural appearance. Thin layer chromatography on the supernatant from the ethanol-dehydrated fraction revealed the extraction of 40 per cent lecithin and 4 per cent phosphatidylglycerol as compared to 1 per cent lecithin and an undeterminably small percentage of phosphatidylglycerol extracted by acetone dehydration. The effect of fixation and dehydration upon the extraction of chemical components of the lamellar bodies was compared to extraction by those of the following treatments: (1) freezing and thawing (a loss of 7 per cent lecithin, undetectably small losses of phosphatidylglycerol and protein); (2) incubation at 37 degrees C. with magnetic stirring (losses of 35 per cent lecithin, 5 per cent phosphatidylglycerol, and 4 percent protein, respectively); (3) sonication (loss of 57 per cent lecithin, 31 per cent phosphatidylglycerol, and 27 per cent protein, respectively). Further lipid analyses of the supernatants from dehydration and those obtained from the mechanical treatments revealed dipalmitoyl lecithin as the most readily extracted lipid. These data indicate that OsO4 fixation followed by acetone dehydration improves the preservation of the lamellar body ultrastructure by retaining an amorphous material between the lamellae, thus preserving the spatial relationship between the lamellae, and further that this improved morphologic preservation correlates well with retention of disaturated lecithin.

Acetone↗
PubMed1975

Phosphatidylglycerol in lung surfactant. II. Subcellular distribution and mechanism of biosynthesis in vitro.

Lamellar inclusion bodies, apparent precursors for alveolar surfactant lining, have remarkably similar phospholipid composition to surfactant from alveolar lavage, but distinctly different from other fractions studied: mitochondria, microsomal fraction containing endoplasmic reticulum membranes, plasma membranes and nuclei. Surfactant contained (as % of total phospholipid phosphate): 75.5-77.0% lecithin, 11.0-11.2% phosphatidylglycerol, 4.2-4.6% phosphatidylethanolamine, 3.0-3.2% phosphatidylinositol, 1.5-1.7% bis-(monoacylglycerol) phosphate, 1.2-1.9% phosphatidylserine, and 0.7-1.5% sphingomyelin. Fatty acids of phosphatidylglycerol from lamellar bodies were similar to those from microsomes but different from those in mitochondria. Lung homogenate in continuous sucrose density gradient displayed two major activity peaks of phosphatidylglycerol synthesis: the heavier from mitochondria; the lighter from endoplasmic reticulum. Studies on mechanism of phosphatidylglycerol synthesis in vitro revealed (in these two fractions) CDP-diglyceride and sn-glycerol phosphate precursors to phosphatidylglycerol phosphate, that hydrolysed to phosphatidylglycerol. In microsomes disaturated CDP-diglycerides were 1.6-1.9 times more active substrates than in mitochondria, whereas CDP-diglycerides from egg lecithin were almost equally active. In contrast to lung mitochondria no cardiolipin synthesis was detected in microsomes. The highest specific activities for phosphatidate cytidyltransferase, CDP-diglyceride-inositol phosphatidyltransferase, choline phosphotransferase, and phosphatidylethanolamine methyltransferase were all found in microsomes. The present in vitro studies and additional evidence (M. Hallman and L. Gluck, (1975) Fed. Proc. 34, 274) support the hypothesis that de novo synthesis of surfactant lecithin phosphatidylinositol and phosphatidylglycerol takes place in the endoplasmic reticulum of alveolar cells.

Animals↗
PubMed1975

Formation of disaturated lecithin through the lysolecithin pathway in the lung of the developing rabbit.

The formation of disaturated lecithin in slices of developing rabbit lung was studied using 14C-CDP-choline, 3H-S-adenosylmethionine, and doubly labeled lecithin, lysolecithin and phosphatidylethanolamine as precursors. The labeling patterns suggest that some of the unsaturated lecithin becomes deacylated and subsequently reacylated to form disaturated surface-active lecithin. The rate of this pathway (lysolecithin 'loop') increases as a function of gestation and may contribute to the functional maturation of the lung.

Age Factors↗
PubMedDate not supplied

Myoinositol in small preterm infants: relationship between intake and serum concentration.

Serum myoinositol (henceforth called inositol) concentration was measured in 12 preterm infants (birth weight 800-1,700 g, gestational age 27-32 weeks) from birth to 10 postnatal weeks. The diet was analyzed for inositol concentration and the daily intake was correlated with serum inositol. There were striking differences in the inositol concentration of infant feedings: preterm colostrum 4.22 +/- 0.51 mM; term colostrum 2.91 +/- 0.21 mM; mature milk 1.81 +/- 0.20 mM; infant formulas 0.09-0.39 mM; parenteral nutrition 0.15 +/- 0.13 mM. The high fetal serum inositol often fell during the first 2 weeks. After 2 weeks, serum inositol correlated significantly with inositol intake (R = 0.601, p less than 0.004). On breast milk serum inositol concentrations (0.56 +/- 0.07 mM) were higher than on formula feedings (0.36 +/- 0.03 mM). Since according to animal studies inositol is important during prenatal growth and differentiation, the present data justify further study on importance of dietary inositol in preterm infants.

Colostrum↗