Influence of non-P region domains on selectivity filter properties in voltage-gated K+ channels

The selectivity filter in voltage-gated K+ channels is formed at the interface of the pore loops (S5-S6 loop) from four channel subunits. Whereas most K+ channels are essentially impermeable to Na+, the Kv2.1 K+ channel conducts Na+ relatively well in the absence of K+ and selects for K+ over Na+ at least partially by an affinity-based competition mechanism. To examine whether the ability of Kv2.1 to conduct Na+ reflected unique properties of either its S5-S6 loop or channel domains that held the S5-S6 loop in place (the scaffolding), we studied chimeras made from Kv1.3 (which is completely impermeable to Na+) and Kv2.1. Chimeras that contained either the S5-S6 loop from Kv1.3 inserted into the Kv2.1 scaffolding or vice versa both made highly selective K+ channels that conducted Na+ and displayed competition between Na+ and K+ for conduction through the pore: In channels that contained the S5-S6 loop from Kv2.1, concentration-dependent block of Na+ current by either external or internal K+ differed depending on whether Kv2.1 or Kv1.3 donated the scaffolding. These results indicate that neither the S5-S6 loop nor the scaffolding from Kv2.1 possess unique attributes that permit Na+ to conduct through the channel. Furthermore, these results indicate that the competitive interaction between K+ and Na+ at the selectivity filter is determined not only by the S5-S6 loop but also by the scaffolding that holds the S5-S6 loop.     

Fast and effective retrieval of medical tumor shapes

Investigates the problem of retrieving similar shapes from a large database; in particular, we focus on medical tumor shapes (finding tumors that are similar to a given pattern). We use a natural similarity function for shape matching, based on concepts from mathematical morphology, and we show how it can be lower-bounded by a set of shape features for safely pruning candidates, thus giving fast and correct output. These features can be organized in a spatial access method, leading to fast indexing for range queries and nearest-neighbor queries. In addition to the lower-bounding, our second contribution is the design of a fast algorithm for nearest-neighbor searching, achieving significant speedup while provably guaranteeing correctness. Our experiments demonstrate that roughly 90% of the candidates can be pruned using these techniques, resulting in up to 27 times better performance compared to sequential scanning     

Mass spectrometry in nutrition: understanding dietary health effects at the molecular level

In modern nutrition research, mass spectrometry has developed into a tool to assess health, sensory as well as quality and safety aspects of food. In this review, we focus on health-related benefits of food components and, accordingly, on biomarkers of exposure (bioavailability) and bioefficacy. Current nutrition research focuses on unraveling the link between dietary patterns, individual foods or food constituents and the physiological effects at cellular, tissue and whole body level after acute and chronic uptake. The bioavailability of bioactive food constituents as well as dose-effect correlations are key information to understand the impact of food on defined health outcomes. Both strongly depend on appropriate analytical tools to identify and quantify minute amounts of individual compounds in highly complex matrices--food or biological fluids--and to monitor molecular changes in the body in a highly specific and sensitive manner. Based on these requirements, mass spectrometry has become the analytical method of choice with broad applications throughout all areas of nutrition research. The current review focuses on selected areas of application: protein and peptide as well as nutrient and metabolite analysis.     

Multi-element determination of Cu,Fe, Ni and Zn content in vegetable oils samples by high-resolution continuum source atomic absorption spectrometry and microemulsion sample preparation

The aim of this work was to evaluate the microemulsification as sample preparation procedure for determination of Cu, Fe, Ni and Zn in vegetable oils samples by High-Resolution Continuum Source Flame Atomic Absorption Spectrometry (HR-CS FAAS). Microemulsions were prepared by mixing samples with propan-1-ol and aqueous acid solution, which allowed the use of inorganic aqueous standards for the calibration. To a sample mass of 0.5 g, 100 μL of hydrochloric acid and propan-1-ol were added and the resulting mixture diluted to a final volume of 10 mL. The sample was manually shaken resulting in a visually homogeneous system. The main lines were selected for all studied metals and the detection limits (3σ, n = 10) were 0.12, 0.62, 0.58 and 0.12 mg kg⁻¹ for Cu, Fe, Ni and Zn, respectively. The relative standard deviation (RSD) ranged from 5% to 11 % in samples spiked with 0.25 and 1.5 μg mL⁻¹ of each metal, respectively. Recoveries varied from 89% to 102%. The proposed method was applied to the determination of Cu, Fe, Ni and Zn in soybean, olive and sunflower oils.     

Kenneth E. Moyer (1919-2006).

Presents an obituary for Kenneth E. Moyer. Before becoming an internationally known expert in the field of aggressive behavior, Kenneth Evan (Keck) Moyer held jobs as an acrobat, a physical therapist, and a farmer. He served as a marine in World War II and was a consultant to the Norwegian government. The range of his life experiences amazed his friends, who wondered how he could have done all these things and still have acquired such a breadth of scholarly knowledge. Throughout his life, his scholarly pursuits had practical applications, and his practical endeavors had a scholarly basis. Keck died May 18, 2006, of an apparent heart attack. His son, Robert S. Moyer, a psychologist who recently retired from the faculty of Bates College, and his daughter, Cathy Noblick, a marriage and family counselor in New Jersey, survive him. Also surviving are five grandchildren and four great grandchildren. He was devoted to all of them and to children he supported through international programs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Process layout for driving workings in burst-prone areas

Institute of Nonferrous Metallurgy, Ust'-Kamenogorsk. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 6, pp. 81-88, November-December, 1991.     

Physiological properties of the Mauthner system in the adult zebrafish

We investigated the morphological and electrophysiological properties of the Mauthner (M-) cell and its networks in the adult zebrafish (Danio rerio) in comparison with those in the goldfish (Carassius auratus). The zebrafish M-cell has an axon cap, a high resistivity structure which surrounds the initial segment of the M-axon, and accounts for an unusual amplification of the fields generated within and around it. Second, extra- and intracellular recordings were performed with microelectrodes. The resting potential was approximately -80 mV with an input resistance of approximately 0.42 M omega. The M-cell extracellular field was large (10-20 mV), close to the axon hillock, and the latency of antidromic spikes short (approximately 0.4 milliseconds), confirming a high conduction velocity in the M-axon. The extrinsic hyperpolarizing potential (EHP), which signals firing of presynaptic cells and collateral inhibition, was markedly lower at frequencies of spinal stimulation > approximately 5/second, suggesting an organization of the recurrent collateral network similar to that in the goldfish. Inhibitory postsynaptic potentials (IPSPs) were highly voltage-dependent; their decay time constant was increased by depolarizations. The presynaptic neurons which are numerous could be identified by their passive hyperpolarizing potential (PHP) produced by the M-spike current. Auditory responses, mediated via mixed synapses (electrical and chemical), had short delays and hence are well suited to trigger the escape reaction. The similarities of their properties indicate that the wealth of information generated over decades in the goldfish can be extrapolated to the zebrafish.     

Adjacent-Channel and Quadrature-Channel Interference in Minimum Shift Keying

In this paper we present formulas for the computation of error probability in the presence of quadrature-channel or adjacentchannel interference in addition to intersymbol interference in a minimum shift keying system. The filters in the receiver and transmitter are arbitrary but with a finite number of poles. The effect of phase jitter in the main channel, phase and symbol timing misalignment in the interfering channels, and sampling time jitter is taken into account. The probability of error is averaged over the phase and symbol timing misalignment. Numerical results are presented for Butterworth filters in the receiver and transmitter with two, three, and four poles. Curves of error probability as a function of various variables (signal-to-noise ratio, bandwidth of receiver and transmitter filters, number of poles, channel frequency separation, phase jitter, sampling time, and symbol timing and phase misalignment) are presented. The method of this paper can readily be applied to other filters; hence, it can be used in the design and prediction of the performance of digital communication systems.