KCNE1 and KCNE3 Stabilize and/or Slow Voltage Sensing S4 Segment of KCNQ1 Channel

KCNQ1 is a voltage-dependent K+ channel whose gating properties are dramatically altered by association with auxiliary KCNE proteins. For example, KCNE1, which is mainly expressed in heart and inner ear, markedly slows the activation kinetics of KCNQ1. Whether the voltage-sensing S4 segment moves differently in the presence of KCNE1 is not yet known, however. To address that question, we systematically introduced cysteine mutations, one at a time, into the first half of the S4 segment of human KCNQ1. A226C was found out as the most suited mutant for a methanethiosulfonate (MTS) accessibility analysis because it is located at the N-terminal end of S4 segment and its current was stable with repetitive stimuli in the absence of MTS reagent. MTS accessibility analysis revealed that the apparent second order rate constant for modification of the A226C mutant was state dependent, with faster modification during depolarization, and was 13 times slower in the presence of KCNE1 than in its absence. In the presence of KCNE3, on the other hand, the second order rate constant for modification was not state dependent, indicating that the C226 residue was always exposed to the extracellular milieu, even at the resting membrane potential. Taken together, these results suggest that KCNE1 stabilizes the S4 segment in the resting state and slows the rate of transition to the active state, while KCNE3 stabilizes the S4 segment in the active state. These results offer new insight into the mechanism of KCNQ1 channel modulation by KCNE1 and KCNE3

Effect of different choices of the Boltzmannized flux operator on thermal exchange and recombination reactions

The rate constants for recombination and exchange reactions are calculated using the flux correlation approach with a general form of the Boltzmannized flux operator, which can simultaneously describe the Kubo and traditional half-split forms. First, we consider an exactly solvable model, i.e., the free particle case, in terms of a new scaling function. Next, as a non-trivial case, we study the recombination and exchange reactions at very high pressure. Since the rate constant is calculated by Laplace transform of the flux correlation function, the result depends on how the Boltzmannized flux operator is chosen. We find that a choice of the flux operator affects the rate constant considerably. For the recombination reaction, the ratio of the rate constant in the half-split form to that in the Kubo form approaches zero in the high pressure limit.Comment: 16 pages, including 8 figure

Voltage- and [ATP]-dependent Gating of the P2X2 ATP Receptor Channel

P2X receptors are ligand-gated cation channels activated by extracellular adenosine triphosphate (ATP). Nonetheless, P2X2 channel currents observed during the steady-state after ATP application are known to exhibit voltage dependence; there is a gradual increase in the inward current upon hyperpolarization. We used a Xenopus oocyte expression system and two-electrode voltage clamp to analyze this “activation” phase quantitatively. We characterized the conductance–voltage relationship in the presence of various [ATP], and observed that it shifted toward more depolarized potentials with increases in [ATP]. By analyzing the rate constants for the channel's transition between a closed and an open state, we showed that the gating of P2X2 is determined in a complex way that involves both membrane voltage and ATP binding. The activation phase was similarly recorded in HEK293 cells expressing P2X2 even by inside-out patch clamp after intensive perfusion, excluding a possibility that the gating is due to block/unblock by endogenous blocker(s) of oocytes. We investigated its structural basis by substituting a glycine residue (G344) in the second transmembrane (TM) helix, which may provide a kink that could mediate “gating.” We found that, instead of a gradual increase, the inward current through the G344A mutant increased instantaneously upon hyperpolarization, whereas a G344P mutant retained an activation phase that was slower than the wild type (WT). Using glycine-scanning mutagenesis in the background of G344A, we could recover the activation phase by introducing a glycine residue into the middle of second TM. These results demonstrate that the flexibility of G344 contributes to the voltage-dependent gating. Finally, we assumed a three-state model consisting of a fast ATP-binding step and a following gating step and estimated the rate constants for the latter in P2X2-WT. We then executed simulation analyses using the calculated rate constants and successfully reproduced the results observed experimentally, voltage-dependent activation that is accelerated by increases in [ATP]

Downsian Positions of Parties and Districts from the Numbers of Votes with Examples of Japanese Congressional Elections 1983 - 2004

This paper proposes, under assumptions of sincere voters with some additional conditions, to calculate the positions of parties and districts by “solving” a system of equations whose left hand sides are theoretical predictions and theright hand sides are the actual numbers of votes gained by the parties in the districts. The positions of parties and prefectures are calculated for the seats for the proportional representation in the Japanese congressional elections 1983 – 2004. The result reveals that the competition in these elections was not between the right and the left, but between the urban and the rural

Histological characteristics of incidentally-found growing meningiomas

Object. With the wider use of CT and MRI, many meningiomas are discovered as incidental findings during diagnostic work-up for unrelated symptoms. The majority shows no or minimal growth. The purpose of this study was to distinguish pathological features of incidentally-found growing meningiomas by comparing incidentally-found with symptomatic meningiomas. Methods. One hundred and thirty two consecutive nonrecurrent surgically-treated meningiomas treated between 2005 and 2007 were divided into three categories : 19 incidentally-found growing meningiomas (IG), 50 incidentallyfound meningiomas (I), and 63 symptomatic (S) meningiomas. The average follow-up period for the IG meningiomas was 3.7 years. Six out of 19 patients of the IG meningiomas became symptomatic during observation. Results. There is a significant difference of the incidence of WHO grades I, II, and III between all three groups (p=0.035). The incidence of WHO grades II and III in groups IG, I, and S were 26%, 2%, and 10%, respectively. We compare MIB-1 staining index between three groups : an average was 3.8% in IG, 1.3% in I, and 2.4% in S meningiomas. Conclusions. Incidentally-found meningiomas need careful follow-up. One fourth of the meningiomas that showed signs of growing belonged to the atypical or malignant grade

Genome Wide Association Study of Age at Menarche in the Japanese Population

Age at menarche (AAM) is a complex trait involving both genetic and environmental factors. To identify the genetic factors associated with AAM, we conducted a large-scale meta-analysis of genome-wide association studies using more than 15,000 Japanese female samples. Here, we identified an association between SNP (single nucleotide polymorphism) rs364663 at the LIN28B locus and AAM, with a P-value of 5.49×10−7 and an effect size of 0.089 (year). We also evaluated 33 SNPs that were previously reported to be associated with AAM in women of European ancestry. Among them, two SNPs rs4452860 and rs7028916 in TMEM38B indicated significant association with AAM in the same directions as reported in previous studies (P = 0.0013 with an effect size of 0.051) even after Bonferroni correction for the 33 SNPs. In addition, six loci in or near CCDC85A, LOC100421670, CA10, ZNF483, ARNTL, and RXRG exhibited suggestive association with AAM (P<0.05). Our findings elucidated the impact of genetic variations on AAM in the Japanese population

Genome Wide Association Study of Age at Menarche in the Japanese Population

Age at menarche (AAM) is a complex trait involving both genetic and environmental factors. To identify the genetic factors associated with AAM, we conducted a large-scale meta-analysis of genome-wide association studies using more than 15,000 Japanese female samples. Here, we identified an association between SNP (single nucleotide polymorphism) rs364663 at the LIN28B locus and AAM, with a P-value of 5.49×10−7 and an effect size of 0.089 (year). We also evaluated 33 SNPs that were previously reported to be associated with AAM in women of European ancestry. Among them, two SNPs rs4452860 and rs7028916 in TMEM38B indicated significant association with AAM in the same directions as reported in previous studies (P = 0.0013 with an effect size of 0.051) even after Bonferroni correction for the 33 SNPs. In addition, six loci in or near CCDC85A, LOC100421670, CA10, ZNF483, ARNTL, and RXRG exhibited suggestive association with AAM (P<0.05). Our findings elucidated the impact of genetic variations on AAM in the Japanese population.</p

Dynamic FDG PET / CT in MSLs

We aimed to assess the differential diagnostic efficacy of dynamic F-18 fluorodeoxyglucose (FDG) positron emission tomography / computed tomography (PET / CT) and to evaluate the appropriate scan timings for diagnosis of musculoskeletal lesions (MSLs). Dynamic scans (5–15 [phase 1], 15–25 [phase 2], and 25–35 [phase 3] min after F-18 FDG injection) and dual-time-point scans (1 and 2 h after injection) were acquired for 23 MSLs [4 benign MSLs (BMSLs). 10 primary malignant musculoskeletal tumors (PMMSTs), and 9 metastatic musculoskeletal tumors (MMSTs)]. We compared the maximum standardized uptake values (SUVmax) and corresponding retention indices for dynamic (RI-SUVdyn) and dual-time-point (RI-SUVdual) scans and evaluated diagnostic efficacy using receiver operating characteristic (ROC) curve analyses. The SUVmax gradually decreased or was almost identical with minimal fluctuation in 3 BMSLs and 1 PMMST. SUVmax increased over time after phase 2 in 18 malignant MSLs (MMSLs). There were significant differences in SUVmax (for all time phases) and RI-SUV dual between BMSLs and MMSLs and between PMMSTs and MMSTs. In the ROC analyses, the areas under the curve for SUV in phases 2 and 3 were highest for differentiating BMSLs from MMSLs and PMMSTs from MMSTs, respectively. Dynamic F-18 FDG PET / CT is valuable for diagnosis of musculoskeletal lesions

Preliminary clinical assessment of dynamic carbon-11 methionine positron-emission tomography/computed tomography for the diagnosis of the pathologies in patients with musculoskeletal lesions : a prospective study

Background: This study prospectively assessed the diagnostic capacity of dynamic carbon-11 methionine (C-11 MET) positron-emission tomography (PET)/computed tomography for the diagnosis of pathologies in patients with primary unknown musculoskeletal lesions (MSLs). In total, 13 patients with MSLs underwent dynamic scans (5–10 [phase 1], 10–15 [phase 2], 15–20 [phase 3], 20–25 [phase 4], 25–30 [phase 5], and 30–35 [phase 6] min post-injection of C-11 MET). We statistically compared the maximum standardised uptake values (SUVmax) and corresponding retention index for dynamic scans (RI-SUV) for five benign MSLs (BMSLs), five primary malignant musculoskeletal tumours (PMMSTs), four metastatic musculoskeletal tumours (MMSTs), and three malignant lymphoma (ML) cases and explored their diagnostic capacities using receiver operating characteristic (ROC) curve analyses. Results: SUVmax gradually decreased or remained similar with minimal fluctuations in all BMSL cases and four of five PMMST cases. In contrast, SUVmax increased over time in one case of PMMST and in all cases of MMST and ML. Significant differences were observed in SUVmax for all time phases and RI-SUV between BMSLs and MMSLs, in SUVmax for all time phases between PMMSTs and BMSLs, in SUVmax for all time phases and RI-SUV between non-PMMST-malignant tumours and BMSL, and in RI-SUV between non-PMMST-malignant tumours and PMMST. In ROC analyses, the areas under the curve yielded the highest values at 1.00 for differentiating most intergroup comparisons. Conclusions: Dynamic C-11 MET PET scans have the potential to be good predictors of discriminating MSLs in patients with primary unknown MSLs in clinical practice