The MinK Potassium Channel Exists in Functional and Nonfunctional Forms When Expressed in the Plasma Membrane of \u3cem\u3eXenopus\u3c/em\u3e Oocytes

The minK protein induces a slowly activating voltage-dependent potassium current when expressed in Xenopus oocytes. In order to measure the levels of minK protein in the plasma membrane, we have modified the minK gene by inserting a 9 amino acid epitope into the N- terminal domain of the protein sequence. When intact live oocytes are injected with the modified minK RNA and subsequently incubated with an antibody to this epitope, specific binding is detected, indicating that the N-terminal domain is extracellular. We found that when oocytes are injected with amounts of minK mRNA up to 50 ng, the levels of protein at the surface are proportional to the amount of injected mRNA. In contrast, the amplitude of the minK current recorded in the oocytes saturates at 1 ng of injected mRNA. Although the amplitude of the currents is not altered by increasing mRNA levels above 1 ng, the kinetics of activation of the current differ in oocytes with high or low levels of minK RNA. In particular, activation is slower with higher levels of minK protein in the plasma membrane. Finally, we find that increasing intracellular cAMP levels, which increases the amplitude of minK currents, does not alter surface expression of the minK protein but produces a small increase in the rate of activation of the current. Our results support a model in which minK protein forms functional potassium channels by association with a factor endogenous to the oocyte

Modulation by cAMP of a Slowly Activating Potassium Channel Expressed in \u3cem\u3eXenopus\u3c/em\u3e Oocytes

When expressed in the Xenopus oocyte, the minK protein induces a slowly activating voltage-dependent potassium current (Isk). We studied the modulation of this current by altering intracellular cAMP levels and found that the amplitude of Isk is dramatically increased by treatments that raise cAMP levels and decreased by agents that lower cAMP levels. Preinjection of a protein inhibitor of the cAMP-dependent protein kinase blocked the effects of increased cAMP levels. There were no changes in the voltage dependence or kinetics of Isk. Mutations that eliminate a potential phosphorylation site on the minK protein did not block the effects of activating the kinase. In addition, the membrane capacitance of the oocyte increased and decreased in parallel with Isk. Our results fit a mechanism in which channel proteins are selectively inserted into and removed from the plasma membrane in response to changes in kinase activity

Free energies of static three quark systems

We study the behaviour of free energies of baryonic systems composed of three heavy quarks on the lattice in SU(3) pure gauge theory at finite temperature. For all temperatures above $T_c$ we find that the connected part of the singlet (decuplet) free energy of the three quark system is given by the sum of the connected parts of the free energies of $qq$-triplets (-sextets). Using renormalized free energies we can compare free energies in different colour channels as well as those of $qq$- and $qqq$-systems on an unique energy scale.Comment: 5 pages, 6 figures, Contribution to Strong and Electroweak Matter 2004 (SEWM04), Helsinki, Finland 16-19 June 200

PNJL model with a Van der Monde term

We extend the Polyakov-Nambu-Jona-Lasinio (PNJL) model for two degenerate flavours by including the effect of the SU(3) measure with a Van der Monde (VdM) term. This ensures that the Polyakov loop always remains in the domain [0,1]. The pressure, energy density, specific heat, speed of sound and conformal measure show small or negligible effects from this term. However various quark number and isospin susceptibilities are all found to approach their respective ideal gas limits around 2 $T_c$. We compare our methods with other similar approaches in PNJL model and also present a quantitative comparison with Lattice QCD data.Comment: 12 pages, 8 eps figures; extended discussion and reference added; accepted in Phys. Rev.

Er3+-to-Yb3+ and Pr3+-to-Yb3+ energy transfer for highly efficient near-infrared cryogenic optical temperature sensing

Here, the very high thermal sensing capability of Er3+,Yb3+ doped LaF3 nanoparticles, where Er3+-to-Yb3+ energy transfer is used, is reported. Also Pr3+,Yb3+ doped LaF3 nanoparticles, with Pr3+-to-Yb3+ energy transfer, showed temperature sensing in the same temperature regime, but with lower performance. The investigated Er3+,Yb3+ doped LaF3 nanoparticles show a remarkably high relative sensitivity S-r of up to 6.6092% K-1 (at 15 K) in the near-infrared (NIR) region, in the cryogenic (15-105 K) temperature region opening a whole new thermometric system suitable for advanced applications in the very low temperature ranges. To date reports on NIR cryogenic sensors have been very scarce

TeSen : tool for determining thermometric parameters in ratiometric optical thermometry

This work presents the method and numerical program along with graphical user interface (GUI) for calculating the standard parameters necessary to evaluate luminescence ratiometric thermometers - the thermometric parameter Delta, absolute sensitivity S-a, and relative sensitivity S-r. Despite the high interest in temperature sensing materials, to the best of our knowledge, no such tool has been reported up to date. This is currently usually done by researchers using a trial and error method and is a rather laborious task, with high risk of errors. The undoubtful benefit of employing an optimization technique lies in the very fast and precise determination of the parameters employing different models. The thermometric parameters Delta, S-a and S-r are calculated based on the luminescence emission spectra measured over a certain temperature range. Using the TeSen tool the thermometric parameters Delta can be calculated based both on the peak maxima and integrated surface areas under the peaks. The tool also allows testing the ratio of multiple peaks, different peak ranges, and different temperature ranges in a very convenient way. In this work TeSen tool was used to study several new sensor materials, presenting new cases of single and dual center luminescent ratiometric theremometers

Color Screening and Quark-Quark Interactions in Finite Temperature QCD

We analyze the screening of static diquark sources in 2-flavor QCD and compare results with the screening of static quark-antiquark pairs. We show that a two quark system in a fixed color representations is screened at short distances like a single quark source in the same color representation whereas at large distances the two quarks are screened independently. At high temperatures we observe that the relative strength of the interaction in diquark and quark-antiquark systems, respectively, obeys Casimir scaling. We use this result to examine the possible existence of heavy quark-quark bound states in the high temperature phase of QCD. We find support for the existence of $bb$ states up to about $2T_c$ while $cc$ states are unlikely to be formed above $T_c$.Comment: 8 pages, 6 figure

47P Dawka MTX, jego eliminacja a objawy toksyczne

W latach 1992–1997 leczenie MTX zastosowano u dzieci. Analizie poddano 92 pacjentów. Zostali oni podzieleni na 4 grupy w zależności od rozpoznania, dawki MTX oraz czasu jego podania.Grupa I: MTX 3,0 g/m2 - 24 h - 59 dzieci z ALL-LRG (236 cykli)Grupa II: MTX 3,0 g/m2 - 3 h - 8 dzieci z B-NHL gr. B (37 cykli)Grupa III: MTX 5,0 g/m2 - 24 h - 13 dzieci z NB-NHL (46 cykli)Grupa IV: MTX 5,0 g/m2 - 24 h - 9 dzieci z nawrotem ALL (27 cykli)Grupę IV wyodrębniono ze względu na stosowanie dodatkowych cytostatyków dożylnych. Analizowano wpływ dawki MTX, czasu jego infuzji i eliminacji leku oraz stotusu wirusulogicznego pacjentów (HCV) na wystąpienie i nasilenie zmian toksycznych (zmianyskórne, śluzówkowe, hepatopathia, gastroenterocolitis). Do przeprowadzenia analizy zastosowano test T-studenta do prób zależnych i niezależnych.GrupaIIIIIIIVLiczba cykli236374627Liczba cykli z upośledzonąeliminacją482114Toksyczność18121+HCV/+/9010Liczba cykli z prawidłowąeliminacją MTX188353523Toksyczność498128+HCV/+/284124Wnioski1)Brak korelacji pomiędzy eliminacją MTX a objawami toksycznymi.2)Stwierdzono statystycznie znamienną różnicę między grupą III a IV w wystąpieniu objawów toksycznych(prawdopodobnie ze względu na zasto sowanie dodatkowych dożylnych cytostatyków).3)Brak różnicy między grupą I a II, pomimo różnego czasu infuzji MTX.4)Zakażenie HCV miało istotny wpływ na wystąpienie objawów toksycznych

Emerging role of the KCNT1 Slack channel in intellectual disability

The sodium-activated potassium KNa channels Slack and Slick are encoded by KCNT1 and KCNT2, respectively. These channels are found in neurons throughout the brain, and are responsible for a delayed outward current termed IKNa. These currents integrate into shaping neuronal excitability, as well as adaptation in response to maintained stimulation. Abnormal Slack channel activity may play a role in Fragile X syndrome, the most common cause for intellectual disability and inherited autism. Slack channels interact directly with the Fragile X Mental Retardation protein (FMRP) and IKNa is reduced in animal models of Fragile X syndrome that lack FMRP. Human Slack mutations that alter channel activity can also lead to intellectual disability, as has been found for several childhood epileptic disorders. Ongoing research is elucidating the relationship between mutant Slack channel activity, development of early onset epilepsies and intellectual impairment. This review describes the emerging role of Slack channels in intellectual disability, coupled with an overview of the physiological role of neuronal IKNa currents