TRALI is due to pulmonary venule damage from leucocytes with cholesterol crystal formation.

BACKGROUND: There are two presumed mechanisms for the pulmonary oedema in transfusion-related acute lung injury (TRALI). One is antibodies to leucocytes while the other is biologically active lipids. We evaluated the vascular injury due to the former. METHODS: The pulmonary vasculature was studied by light microscopy (LM) and scanning electron microscopy (SEM) in three fatal cases of TRALI and compared with that of two autopsied control patients. Lung tissue from two of the TRALI cases and both controls was studied by gas chromatography-mass spectroscopy (GC-MS) to identify crystals present in the former. RESULTS: All three TRALI cases exhibited massive pulmonary oedema by weight and light microscopy and extensive defects by SEM in the endothelium of venules of the lungs. Such endothelial defects were absent in controls. Thrombi, composed of crystals, were present in venules and small veins diffusely throughout the lungs in Case 1. Similar crystals were identified in Case 2. The crystals in the lung vessels were identified morphologically as cholesterol and were proximate to the cytoplasmic defects of the endothelial surfaces. By GC-MS, there were markedly elevated levels of cholesterol and fatty acids in the two TRALI lungs tested compared with the lungs of the two controls. CONCLUSIONS: Pulmonary damage in TRALI is related to formation of cholesterol crystals that appear to pierce endothelial membranes of venules. The endothelial defects lead to plasma extravasation into the alveoli causing TRALI.

Equine sperm membrane phase behavior: the effects of lipid-based cryoprotectants.

The plasma membrane of sperm can undergo lipid phase separation during freezing, resulting in irreversible damage to the cell. The objective of our study was to examine the membrane phase behavior of equine spermatozoa in the absence and presence of lipid-based cryoprotectants. Biophysical properties of sperm membranes were investigated with Fourier-transform infrared spectroscopy. Compared to fresh untreated sperm, postthaw untreated sperm showed extensive lipid phase separation and rearrangement. In contrast, postthaw sperm that were cryopreserved in egg phosphatidylcholine (egg PC)- or soy phosphatidylcholine (soy PC)-based diluents showed similar lipid phase behavior to that of fresh, untreated sperm. Studies with a deuterium-labeled PC lipid (POPCd-31) suggest that exogenous lipid from the diluents are strongly associated with the sperm membrane, and scanning electron microscopy images of treated sperm show the presence of lipid aggregates on the membrane surface. Thus, the exogenous lipid does not appear to be integrated into the sperm membrane after cryopreservation. When compared to a standard egg-yolk-based diluent (INRA 82), the soy and egg PC media preserved viability and motility equally well in postthaw sperm. A preliminary fertility study determined that sperm cryopreserved in the soy PC-based medium were capable of fertilization at the same rate as sperm frozen in the conventional INRA 82 medium. Our results show that pure lipid-based diluents can prevent membrane damage during cryopreservation and perform as well as a standard egg-yolk-based diluent in preserving sperm viability, motility, and fertility.