Rapid detection of apoptosis in mammalian cells by using intact cell MALDI mass spectrometry

Detection of cell death has extensive applications and is of great commercial value. However, most current high-throughput cell viability assays cannot distinguish the two major forms of cell death: apoptosis and necrosis. Many apoptosis-specific detection methods exist but they are time consuming and labour intensive. In this work, we proposed a novel approach based on Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry (MALDI-TOF-MS) for the specific detection of apoptosis in cultured mammalian cells. Buffer washed cells were directly mixed with a matrix solution and subsequently deposited onto the stainless steel target for MALDI analysis. The resulting mass spectrometric profiles were highly reproducible and can be used to reflect cell viability. Remarkably, the mass spectrometric profiles generated from apoptotic cells were distinct from those from either normal or necrotic cells. The apoptosis-specific features of the mass spectra were proportional to the percentage of apoptotic cells in the culture, but are independent of the drugs used to stimulate apoptosis. This is the first report on the utilization of intact cell MALDI mass spectrometry in detecting mammalian cell apoptosis, and can be used as a basis for the development of a reliable, fast, label-free and high-throughput method for detecting apoptotic cell death.     

Kirkman triple systems of order 21 with nontrivial automorphism group

There are 50,024 Kirkman triple systems of order 21 admitting an automorphism of order 2. There are 13,280 Kirkman triple systems of order 21 admitting an automorphism of order 3. Together with the 192 known systems and some simple exchange operations, this leads to a collection of 63,745 nonisomorphic Kirkman triple systems of order 21. This includes all KTS(21)s having a nontrivial automorphism group. None of these is doubly resolvable. Four are quadrilateral-free, providing the first examples of such a KTS(21).

     

Comparison of fluorescent stains: relative photostability and differential staining of proteins in two-dimensional gels

The fluorescence of proteins stained with Deep Purple and SYPRO Ruby was measured over a time course of UV transillumination to determine the relative photostability of each stain. Mean spot fluorescence (n = 200 matched spots) in gels stained with Deep Purple decreased 27% following 2 min of UV transillumination, compared to SYPRO Ruby, which decreased 17%. After 19 min, an 83% decrease in Deep Purple fluorescence was observed, compared to 44% for SYPRO Ruby. By interpolation, the half-life of Deep Purple fluorescence was estimated to be approximately 6 min. The half-life of SYPRO Ruby fluorescence was not reached during the 19 min time course. Further, differential staining of proteins was observed in gels stained with Deep Purple and SYPRO Ruby as compared to colloidal Coomassie Brilliant Blue and silver staining.     

Dopamine presynaptically and heterogeneously modulates nucleus accumbens medium-spiny neuron GABA synapses in vitro

Background  

The striatal complex is the major target of dopamine action in the CNS. There, medium-spiny GABAergic neurons, which constitute about 95% of the neurons in the area, form a mutually inhibitory synaptic network that is modulated by dopamine. When put in culture, the neurons reestablish this network. In particular, they make autaptic connections that provide access to single, identified medium-spiny to medium-spiny neuron synaptic connections.     

Stereoselective synthesis of N-protected pyrrolidines via Pd-catalyzed reactions of γ-(N-acylamino) alkenes and γ-(N-Boc-amino) alkenes with aryl bromides

The stereoselective synthesis of N-acyl- and N-Boc-protected pyrrolidines via Pd-catalyzed reactions of γ-(N-acylamino) alkenes and γ-(N-Boc-amino) alkenes with aryl bromides is described. These reactions effect formation of two bonds in a single operation and proceed with generally high levels of diastereoselectivity. In contrast to previously described reactions of γ-(N-arylamino) alkenes, these transformations proceed in high yield and high regioselectivity with both electron-rich and electron-deficient aryl bromides as well as vinyl bromide substrates.     

Constructing strength three covering arrays with augmented annealing

A covering arrayCA(N;t,k,v) is an N×k array such that every N×t sub-array contains all t-tuples from v symbols at least once, where t is the strength of the array. One application of these objects is to generate software test suites to cover all t-sets of component interactions. Methods for construction of covering arrays for software testing have focused on two main areas. The first is finding new algebraic and combinatorial constructions that produce smaller covering arrays. The second is refining computational search algorithms to find smaller covering arrays more quickly. In this paper, we examine some new cut-and-paste techniques for strength three covering arrays that combine recursive combinatorial constructions with computational search; when simulated annealing is the base method, this is augmented annealing. This method leverages the computational efficiency and optimality of size obtained through combinatorial constructions while benefiting from the generality of a heuristic search. We present a few examples of specific constructions and provide new bounds for some strength three covering arrays.