| 1. |
- Larsson, Marcus, et al.
(författare)
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Human SP-A and a pharmacy-grade porcine lung surfactant extract can be reconstituted into tubular myelin--a comparative structural study of alveolar surfactants using cryo-transmission electron microscopy.
- 2003
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Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961. ; 23:4, s. 199-203
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Tidskriftsartikel (refereegranskat)abstract
- Cryo-transmission electron microscopy (cryo-TEM) is a rather artefact-free method, well suited to study the alveolar surfactant system. A pharmacy grade porcine lung surfactant extract (HL-10) was mixed with human SP-A and Ringer's solution (for calcium ions), and it was shown by cryo-TEM that the tubular myelin (TM) type of structure was reconstituted. These aggregates were associated to liposomal aggregates, and resulted in macroscopic phase-separation. This phase showed a weak birefringence in the polarising microscope, which is characteristic for a liquid-crystalline type of structure. TM from rabbit lung lavage was also examined, and showed the same periodic arrangement of bilayers as alveolar surface layer from freshly cut rabbit lungs deposited directly on the cryo-TEM grids. The distance between the bilayers of TM was 40-50 nm, and an electron dense material, assumed to be SP-A, was sometimes seen to occur periodically along the bilayers, oriented perpendicularly to the tubuli. The results are consistent with the surface-phase model of the alveolar lining.
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| 2. |
- Larsson, Marcus, et al.
(författare)
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Enhanced efficacy of porcine lung surfactant extract by utilization of its aqueous swelling dynamics.
- 2002
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Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961. ; 22:1, s. 39-48
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the interactions between a porcine lung surfactant (PLS) extract and distilled water, saline solution or Ringer solution. The phases which coexist in equilibrium with water or electrolyte solutions were analysed by X-ray diffraction and cryo transmission electron microscopy (cryo-TEM). A lamellar phase with a structure unit consisting of double bilayers was observed in water, whereas lamellar phases with the usual bilayer structure unit were formed in saline and in Ringer solutions. At 25 degrees C the presence of a 4.2-A peak in the X-ray diffraction wide-angle region of these three maximally swollen phases showed that most of the hydrocarbon chains were organized in a crystalline packing. At 42 degrees C the chains in all three phases were melted which, in combination with the low-angle diffraction, shows that they were liquid-crystalline. Polyhedral-like vesicles and spherically shaped multilamellar vesicles were observed in cryo-TEM. The bilayer unit structures were consistent with the periodicity seen by X-ray diffraction. The dynamic swelling behaviour was followed in the polarizing microscope. A remarkable growth of birefringent networks was seen at the air interface of samples swollen in Ringer solution and saline solution. No such interfacial growth phenomena were observed during swelling in water without electrolytes. Then, these dynamics were analysed in relation to time-dependent pulmonary administration of the surfactant extract in rats. Variation in the time of administration (20 and 60 min) after mixing the extract with saline or Ringer solution showed clear differences in physiological effects. At pulmonary administration when the swelling behaviour in vitro showed a maximum in dynamics, the arterial oxygenation was superior to that of administration at a time after a steady-state had been reached. This means that the clinical performance of mammalian lung surfactant extracts can be significantly improved by taking the time-dependent aqueous swelling of the extract into account.
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