A slide test for detecting neutrophil-associated complement components

Complement components deposited on neutrophils were detected by a new test that uses staphylococcal protein A and antisera against complement. Serum from three of 51 patients thought to have immune neutropenia deposited complement but not IgG on their own and normal neutrophils. Some cases of immune neutropenia may be caused primarily by complement-mediated neutrophil destruction.     

Intentions to use hypnosis to control the side effects of cancer and its treatment

Evidence suggests that hypnosis is an effective intervention for reducing distress, pain and other side effects associated with cancer and its treatment. However, hypnosis has failed to be adopted into standard clinical practice. This study (n = 115) investigated overall intentions to use hypnosis to control side effects of cancer and its treatment, as well as demographic predictors of such intentions among healthy volunteers. Results suggest that the vast majority of participants (89%) would be willing to use hypnosis to control side effects associated with cancer treatment. Mean intention levels did not differ by gender, ethnicity, education or age. These results indicate that in the general public, there is a willingness to consider the use of hypnosis, and that willingness is not determined by demographic factors. This broad acceptance of hypnosis argues for more widespread dissemination.     

Disease-associated mutant alpha-actinin-4 reveals a mechanism for regulating its F-actin-binding affinity

Alpha-actinin-4 is a widely expressed protein that employs an actin-binding site with two calponin homology domains to crosslink actin filaments (F-actin) in a Ca(2+)-sensitive manner in vitro. An inherited, late-onset form of kidney failure is caused by point mutations in the alpha-actinin-4 actin-binding domain. Here we show that alpha-actinin-4/F-actin aggregates, observed in vivo in podocytes of humans and mice with disease, likely form as a direct result of the increased actin-binding affinity of the protein. We document that exposure of a buried actin-binding site 1 in mutant alpha-actinin-4 causes an increase in its actin-binding affinity, abolishes its Ca(2+) regulation in vitro, and diverts its normal localization from actin stress fibers and focal adhesions in vivo. Inactivation of this buried actin-binding site returns the affinity of the mutant to that of the WT protein and abolishes aggregate formation in cells. In vitro, actin filaments crosslinked by the mutant alpha-actinin-4 exhibit profound changes of structural and biomechanical properties compared with WT alpha-actinin-4. On a molecular level, our findings elucidate the physiological importance of a dynamic interaction of alpha-actinin with F-actin in podocytes in vivo. We propose that a conformational change with full exposure of actin-binding site 1 could function as a switch mechanism to regulate the actin-binding affinity of alpha-actinin and possibly other calponin homology domain proteins under physiological conditions.     

Lipids of alveolar macrophages, polymorphonuclear leukocytes, and their phagocytic vesicles

Phagocytic vesicles were isolated from rabbit alveolar macrophages and guinea pig polymorphonuclear leukocytes that had ingested emulsified paraffin oil. Phospholipids and their fatty acids were determined in whole cells and in the phagocytic vesicle and pellet fractions separated from them. The cholesterol-to-phospholipid ratios in the vesicle fractions were distinctly higher than those of the respective whole cells or pellet fractions. The vesicle fractions also had higher phospholipid-to-protein ratios than did the whole cells. The phospholipids of the phagocytic vesicle fraction from macrophages contained relatively more sphingomyelin, lyso-(bis)phosphatidic acid, and phosphatidylserine and less lecithin, phosphatidylethanolamine, and phosphatidylinositol than did the whole cells or pellet fractions. The phospholipids of phagocytic vesicles from polymorphonuclear leukocytes contained significantly more phosphatidylinositol than did the pellet fractions. Lyso(bis)phosphatidic acid, which constituted 15% of the phospholipid in rabbit alveolar macrophages and 25% of that in their phagocytic vesicles, contained almost 60% oleic acid and 20% linoleic acid. This lipid was not detected in rabbit peritoneal macrophages or in rat alveolar macrophages.The polyunsaturated fatty acids of leukocyte phospholipids were chiefly linoleic, whereas in macrophages arachidonic accounted for almost 20% of the total fatty acids. The macrophages produced malondialdehyde when ingesting polystyrene beads or emulsified paraffin oil, from which it was inferred that peroxidation of endogenous lipid can occur during phagocytosis. Polymorphonuclear leukocytes in which less than 3% of phospholipid fatty acids were arachidonic did not produce malondialdehyde during phagocytosis of these inert particles, but did when ingesting an emulsion containing linolenate, thus providing evidence for peroxidation of ingested lipid. Isolated phagocytic vesicles from alveolar macrophages contained lipid peroxides and generated malondialdehyde when incubated with ADP, FeCl(3), and NADH.     

Recombinant plasma gelsolin diminishes the acute inflammatory response to hyperoxia in mice.

BACKGROUND: The acute respiratory distress syndrome remains a common and poorly understood complication of a variety of insults. Ventilation with high concentrations of inspired oxygen may further damage already compromised lungs. By scavenging extracellular actin and modulating the effects of lysophosphatidic acid, plasma gelsolin could serve a critical protective role against oxidant injury. METHODS: Mice exposed to >95% O2 for a total of 72 hours were treated with gelsolin or albumin after 24 and 48 hours. RESULTS: Neutrophil counts in bronchoalveolar fluid rose (P=0.0002) and gelsolin levels dropped (P<0.00001) in mice with acute hyperoxic lung injury. The acute inflammatory response to hyperoxia was significantly reduced in the gelsolin- compared with the bovine serum albumin-treated mice (P=0.03). CONCLUSIONS: These data imply that i) gelsolin depletion contributes to the pathogenesis of oxygen toxicity and ii) repletion of gelsolin can partially abrogate the resultant exudative response.     

How phagocytic leukocytes move

A regulated, coordinated movement of the cytoplasm is essential for the function of phagocytes. In these cells, as in muscle cells, the power unit for movement consists of the contractile proteins, actin and myosin, which are concentrated in the region of the cell cortex. In the peripheral cytoplasm, actin fibres may be in a fluid state or they may form a gel network by association with a homodimeric, actin-binding protein. The reversible transformation of the cytoplasm from gel to sol is mediated by a regulatory protein called gelsolin, which when activated by micromolar concentrations of Ca2+, causes shortening of actin fibres, leading to disintegration of the gel network. This gel network reforms if the Ca2+ concentration falls below the threshold value for the activation of gelsolin. Ca2+, acting via gelsolin, is a second component in this system; it controls the order of events that start on the plasma membrane of the phagocyte in response to a stimulus, and are then maintained by an appropriate reaction of the contractile unit. It is to be expected that the elucidation of the molecular mechanisms that release and regulate the movement of cytoplasm in the cell will permit an understanding of factors that interfere with leukocyte function.