The CD16-/CD56bright subset of NK cells is resistant to oxidant-induced cell death

Phagocyte-derived reactive oxygen species ("oxygen radicals") have been ascribed a suppressive role in immunoregulation by inducing dysfunction and apoptotic cell death in lymphocytes. Earlier studies show that human NK cells are exceptionally sensitive to oxygen radical-induced apoptosis and functional inhibition. Two subsets of human CD56(+) NK cells have been identified: the highly cytotoxic CD56(dim) cells which constitute >90% of NK cells in peripheral blood, and the less cytotoxic but efficiently cytokine-producing CD56(bright) cells. In this study, we demonstrate that the CD56(bright) subset of NK cells, in contrast to CD56(dim) cells, remains viable and functionally intact after exposure to phagocyte-derived or exogenously added oxygen radicals. The resistance of CD56(bright) cells to oxidative stress was accompanied by a high capacity of neutralizing exogenous hydrogen peroxide, and by a high cell-surface expression of antioxidative thiols. Our results imply that CD56(bright) NK cells are endowed with an efficient antioxidative defense system that protects them from oxygen radical-induced inactivation.     

On the possibility for computing the transmembrane potential in the heart with a one shot method: an inverse problem

We analyze the possibility for using body surface potential maps (BSPMs), a priori information about the voltage distribution in the heart and the bidomain equations to compute the transmembrane potential throughout the myocardium. Our approach is defined in terms of an inverse problem for elliptic partial differential equations (PDEs). More precisely, we formulate it in terms of an output least squares framework in which a goal functional is minimized subject to suitable PDE constraints. The problem is highly unstable and, even under optimal recording conditions, it does not have a unique solution. We propose a methodology for stabilizing and enforcing uniqueness for this inverse problem. Moreover, a fully implicit method for solving the involved minimization problem is presented. In other words, we show how one may solve it in terms of a system consisting of three linear elliptic PDEs, i.e. we derive a so-called one shot method (also commonly referred to as an all-at-once method). Finally, our theoretical findings are illuminated by a series of numerical experiments. These examples indicate that, in the presence of regional ischemia, it might be possible to approximately recover the transmembrane potential during the resting and plateau phases of the heart cycle. This is probably due to the fact that rather accurate a priori information is available during these time intervals. The problem of computing the transmembrane potential at an arbitrary time instance during a heart beat is still an open problem.     

Novel and potent small-molecule urotensin II receptor agonists

A series of analogs of the non-peptidic urotensin II receptor agonist N-[1-(4-chlorophenyl)-3-(dimethylamino)propyl]-4-phenylbenzamide (FL104) has been synthesized and evaluated pharmacologically. The enantiomers of the two most potent racemic analogues were obtained from the corresponding diastereomeric mandelic amides. In agreement with previously observed SAR, most of the agonist potency resided in the (S) enantiomers. The most potent UII receptor agonist in the new series was (S)-N-[3-dimethylamino-1-(2-naphthyl)propyl]-4-(4-chlorophenyl)benzamide (EC₅₀ = 23 nM at the urotensin II receptor).     

Substrate Utilization by the Failing Human Heart by Direct Quantification Using Arterio-Venous Blood Sampling

Metabolic substrate utilization of the human failing heart is an area of controversy. The purpose of this study is to directly quantify myocardial substrate utilization in moderately severe heart failure, type 2 diabetes and healthy controls using simultaneous coronary sinus and arterial blood sampling. Patients with heart failure (n = 9, mean NYHA 2.7±0.5), with type 2 diabetes (n = 5) and with normal heart function (n = 10) were studied after an overnight fast in connection with electrophysiological investigations/treatments.A systemic infusion of [²H₂]palmitate allowed for the calculation of absolute palmitate extraction across the heart. Blood samples were analysed for non-esterified fatty acids, triacylglycerol, glycerol, glucose, pyruvate, lactate, 3-hydroxybutyrate, and blood gases after simultaneous sampling of arterial and coronary sinus blood. Arterio-coronary sinus metabolite concentration differences and fractional extractions for all substrates were similar between the groups. The absolute NEFA uptakes assessed by [²H₂]palmitate extraction were also similar between the groups. Using direct measurements of metabolic substrate uptake by arterio-venous difference technique, the compensated human failing heart does not appear to have reduced myocardial fatty acid uptake.     

Malignant cells derived from 3T3 fibroblast feeder layer in cell culture for nasopharyngeal carcinoma

In this study, we discovered a subpopulation of 3T3 feeder cells were malignantly transformed by nasopharyngeal carcinoma (NPC) tumor cells during co-culture. The transformed 3T3 cells acquired an accelerated growth rate, displayed loosely attached multilayer growth in vitro and highly tumorigenic in vivo. Most strikingly, instead of forming sarcomas, they developed into carcinoma-like tumors somewhat resembling the original NPC. We further demonstrated the transformation is not a single isolated event, rather a common reproducible, cell contact dispensable phenomena among NPC tumor cells. However, NPC tumor cells alone were not sufficient to confer the transformed characteristics onto normal human cells.     

Quantification of PtdInsP3 molecular species in cells and tissues by mass spectrometry

Class I phosphoinositide-3-kinase (PI3K) isoforms generate the intracellular signaling lipid, phosphatidylinositol(3,4,5)trisphosphate (PtdIns(3,4,5)P(3)). PtdIns(3,4,5)P(3) regulates major aspects of cellular behavior, and the use of both genetic and pharmacological intervention has revealed important isoform-specific roles for PI3Ks in health and disease. Despite this interest, current methods for measuring PtdIns(3,4,5)P(3) have major limitations, including insensitivity, reliance on radiolabeling, low throughput and an inability to resolve different fatty-acyl species. We introduce a methodology based on phosphate methylation coupled to high-performance liquid chromatography-mass spectrometry (HPLC-MS) to solve many of these problems and describe an integrated approach to quantify PtdIns(3,4,5)P(3) and related phosphoinositides (regio-isomers of PtdInsP and PtdInsP(2) are not resolved). This methodology can be used to quantify multiple fatty-acyl species of PtdIns(3,4,5)P(3) in unstimulated mouse and human cells (≥10(5)) or tissues (≥0.1 mg) and their increase upon appropriate stimulation.     

Characterization of a proton pumping transmembrane protein incorporated into a supported three-dimensional matrix of proteoliposomes

A highly sensitive assay based on new internally quenched fluorogenic peptide substrates has been developed for monitoring protease activities. These novel substrates comprise an Edans (5-(2-aminoethylamino)-1-naphthalenesulfonic acid) group at the C terminus and a Dabsyl (4-(dimethylamino)azobenzene-4'-sulfonyl chloride) fluorophore at the N terminus of the peptide chains. The Edans fluorescence increases upon peptide hydrolysis by Pseudomonas aeruginosa proteases, and this increase is directly proportional to the amount of substrate cleaved, i.e., protease activity. The substrates Dabsyl-Ala-Ala-Phe-Ala-Edans and Dabsyl-Leu-Gly-Gly-Gly-Ala-Edans were used for testing the peptidasic activities of P. aeruginosa elastase and LasA protease, respectively. Elastase and LasA kinetic parameters were calculated and a sensitive assay was designed for the detection of P. aeruginosa proteases in bacterial supernatants. The sensitivity and the small sample requirements make the assay suitable for high-throughput screening of biological samples. Furthermore, this P. aeruginosa protease assay improves upon existing assays because it is simple, it requires only one step, and even more significantly it is enzyme specific.     

Sex ratio of leopards taken in trophy hunting: genetic data from Tanzania

The sex ratio of leopards, Panthera pardus, taken by trophyhunters in Tanzania is examined. We used sex specific molecularmarkers to analyze 77 samples collected from animals shot betweenthe years 1995–1998 and found that 28.6% were females, despitethe fact that only males are allowed on licenses and all skinswere tagged as males. The model used for quota setting assumesthat only males are shot, but the effect of this violation ofquotas is unknown. Off-take in Tanzania does not currently fillquotas, but when off-take approach maximum levels, compliancewith set quotas and regulations will be critical for sustainableharvest.     

The phylogenetic position of Siboglinidae (Annelida) inferred from 18S rRNA, 28S rRNA and morphological data

We assess the phylogenetic position of Siboglinidae (previously known as the phyla Pogonophora and Vestimentifera, but now referred to Annelida) in parsimony analyses of 1100 bp from 18S rRNA, 320 bp from the D1 region of 28S rRNA, and 107 morphological characters, totaling 667 parsimony informative characters. The 34 terminal taxa, apart from six siboglinids, include polychaete members of Sabellida, Terbelliformia, Cirratuliformia and Spionida, plus two Aciculata polychaetes as outgroups. Our results contradict most recent hypotheses in showing a sistergroup relationship between Siboglinidae and Oweniidae, and in that the latter taxon is not a member of Sabellida. Furthermore, our results indicate that Sabellariidae is not closely related to Sabellida, that Serpulidae may be nested within Sabellidae, and that Alvinellidae is nested within Ampharetidae. © The Willi Hennig Society 2004.