The effect of surgery and anesthetic agents on granulocyte-chemiluminescence in whole blood

The effect of anesthesia and major abdominal surgery on zymosan-induced chemiluminescence (CL) of neutrophil granulocytes was evaluated. CL was measured in diluted whole blood taken at distinct intervals within the perioperative period. In addition, blood samples from healthy volunteers were supplemented with ether and halothane to investigate the in vitro effect of these agents. The phagocytosis-induced CL was not found to be depressed by anesthesia and surgery. Only at supranarcotic concentrations was CL reduced. Surgery and anesthesia, therefore, do not appear to impair this defense system significantly under the conditions of this investigation.     

Molecular recognition of a single sphingolipid species by a protein's transmembrane domain

Functioning and processing of membrane proteins critically depend on the way their transmembrane segments are embedded in the membrane. Sphingolipids are structural components of membranes and can also act as intracellular second messengers. Not much is known of sphingolipids binding to transmembrane domains (TMDs) of proteins within the hydrophobic bilayer, and how this could affect protein function. Here we show a direct and highly specific interaction of exclusively one sphingomyelin species, SM 18, with the TMD of the COPI machinery protein p24 (ref. 2). Strikingly, the interaction depends on both the headgroup and the backbone of the sphingolipid, and on a signature sequence (VXXTLXXIY) within the TMD. Molecular dynamics simulations show a close interaction of SM 18 with the TMD. We suggest a role of SM 18 in regulating the equilibrium between an inactive monomeric and an active oligomeric state of the p24 protein, which in turn regulates COPI-dependent transport. Bioinformatic analyses predict that the signature sequence represents a conserved sphingolipid-binding cavity in a variety of mammalian membrane proteins. Thus, in addition to a function as second messengers, sphingolipids can act as cofactors to regulate the function of transmembrane proteins. Our discovery of an unprecedented specificity of interaction of a TMD with an individual sphingolipid species adds to our understanding of why biological membranes are assembled from such a large variety of different lipids.     

Detrimental effects of sanctions on human altruism

The existence of cooperation and social order among genetically unrelated individuals is a fundamental problem in the behavioural sciences. The prevailing approaches in biology and economics view cooperation exclusively as self-interested behaviour--unrelated individuals cooperate only if they face economic rewards or sanctions rendering cooperation a self-interested choice. Whether economic incentives are perceived as just or legitimate does not matter in these theories. Fairness-based altruism is, however, a powerful source of human cooperation. Here we show experimentally that the prevailing self-interest approach has serious shortcomings because it overlooks negative effects of sanctions on human altruism. Sanctions revealing selfish or greedy intentions destroy altruistic cooperation almost completely, whereas sanctions perceived as fair leave altruism intact. These findings challenge proximate and ultimate theories of human cooperation that neglect the distinction between fair and unfair sanctions, and they are probably relevant in all domains in which voluntary compliance matters--in relations between spouses, in the education of children, in business relations and organizations as well as in markets.     

Reduction of cytochrome c oxidase by a second electron leads to proton translocation

Cytochrome c oxidase, the terminal enzyme of cellular respiration in mitochondria and many bacteria, reduces O(2) to water. This four-electron reduction process is coupled to translocation (pumping) of four protons across the mitochondrial or bacterial membrane; however, proton pumping is poorly understood. Proton pumping was thought to be linked exclusively to the oxidative phase, that is, to the transfer of the third and fourth electron. Upon re-evaluation of these data, however, this proposal has been questioned, and a transport mechanism including proton pumping in the reductive phase--that is, during the transfer of the first two electrons--was suggested. Subsequently, additional studies reported that proton pumping during the reductive phase can occur, but only when it is immediately preceded by an oxidative phase. To help clarify the issue we have measured the generation of the electric potential across the membrane, starting from a defined one-electron reduced state. Here we show that a second electron transfer into the enzyme leads to charge translocation corresponding to pumping of one proton without necessity for a preceding turnover.     

Gauss's geodesy and the axiom of parallels

It is a myth that Gauss measured a certain large triangle specifically to determine its angle sum; he did so in order to link his triangulation of Hanover with contiguous ones. The sum of the angles differed from 180° by less than two thirds of a second; he is known to have mentioned in conversation that this constituted an approximate verification of the axiom of parallels (which he regarded as an empirical matter because his studies of hyperbolic trigonometry had led him to recognize the possibility of logical alternatives to Kant and Euclid). However, he never doubted Euclidean geometry in his geodetic work. On the contrary, he continually used 180° angle sums as a powerful check for observational errors, which helped him to achieve standards of precision equivalent to today's. Nor did he ever plan an empirical investigation of the geometrical structure of space.     

Interaction between an antifungal heptaene, amphotericin B and cholesterol in vitro, as detected by circular dichroism and absorption. Influence of temperature]

The polyene antibiotic "Amphotericin B" can interact with sterols, cholesterol or ergosterol in aqueous and hydroalcoholic media and a correlative striking spectral change appears between 300 and 420 nm in the CD and absorption spectra. Using these spectroscopic methods we have determined that the influence of temperature between 4 and 80 degrees C is very important. The higher the temperature the most rapid is the modification of the spectra. Thus, the "Amphotericin B"-sterol complex is more easily formed when heating. We have not found any reversibility at 80 degrees C.