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Pbp1, a yeast ortholog of human ataxin-2, is important for cell growth in the medium containing non-fermentable carbon sources. We had reported that Pbp1 regulates expression of genes related to glycogenesis via transcriptional regulation and genes related to mitochondrial function through mRNA stability control. To further analyze the role of Pbp1 in gene expression, we first examined the time course of gene expression after transfer from YPD medium containing glucose to YPGlyLac medium containing glycerol and lactate. At 12 h after transfer to YPGlyLac medium, the pbp1∆ mutant showed decreased expression of genes related to mitochondrial function but no decrease in expression of glycogenesis-related genes. We also examined a role of the Pbp1-binding factor, Mkt1. The mkt1∆ mutant, like the pbp1∆ mutant, showed slow growth on YPGlyLac plate and reduced expression of genes related to mitochondrial function. Furthermore, we found that mutation of DHH1 gene encoding a decapping activator exacerbated the growth of the pbp1∆ mutant on YPGlyLac plate. The dhh1∆ mutant showed reduced expression of genes related to mitochondrial function. These results indicate that Pbp1 and Mkt1 regulate the expression of genes related to mitochondrial function and that the decapping activator Dhh1 also regulates the expression of those genes., (© 2024 Molecular Biology Society of Japan and John Wiley & Sons Australia, Ltd.)

Parameter optimization (PO) methods to determine the ionic current composition of experimental cardiac action potential (AP) waveform have been developed using a computer model of cardiac membrane excitation. However, it was suggested that fitting a single AP record in the PO method was not always successful in providing a unique answer because of a shortage of information. We found that the PO method worked perfectly if the PO method was applied to a pair of a control AP and a model output AP in which a single ionic current out of six current species, such as I Kr , I CaL , I Na , I Ks , I Kur or I bNSC was partially blocked in silico. When the target was replaced by a pair of experimental control and I Kr -blocked records of APs generated spontaneously in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs), the simultaneous fitting of the two waveforms by the PO method was hampered to some extent by the irregular slow fluctuations in the V m recording and/or sporadic alteration in AP configurations in the hiPSC-CMs. This technical problem was largely removed by selecting stable segments of the records for the PO method. Moreover, the PO method was made fail-proof by running iteratively in identifying the optimized parameter set to reconstruct both the control and the I Kr -blocked AP waveforms. In the lead potential analysis, the quantitative ionic mechanisms deduced from the optimized parameter set were totally consistent with the qualitative view of ionic mechanisms of AP so far described in physiological literature., (© 2024. The Author(s).)

Since the left ventricle (LV) has pressure (Plv) and volume (Vlv), we can define LV elastance from the ratio between Plv and Vlv, termed as "instantaneous elastance." On the other hand, end-systolic elastance (Emax) is known to be a good index of LV contractility, which is measured by the slope of several end-systolic Plv-Vlv points obtained by using different loads. The word Emax originates from the assumption that LV elastance increases during the ejection phase and attains its maximum at the end-systole. From this concept, we can define another elastance determined by the slope of isochronous Plv-Vlv points, that is Plv-Vlv points at a certain time after the ejection onset time by using different loads. We refer to this elastance as "load-dependent elastance." To reveal the relation between these two elastances, we used a hemodynamic model that included a detailed ventricular myocyte contraction model. From the simulation results, we found that the isochronous Plv-Vlv points lay in one line and that the line slope corresponding to the load-dependent elastance slightly decreased during the ejection phase, which is quite different from the instantaneous elastance. Subsequently, we analyzed the mechanism determining these elastances from the model equations. We found that instantaneous elastance is directly related to contraction force generated by the ventricular myocyte, but the load-dependent elastance is determined by two factors: one is the transient characteristics of the cardiac cell, i.e., the velocity-dependent force drops characteristics in instantaneous shortening. The other is the force-velocity relation of the cardiac cell. We also found that the linear isochronous pressure-volume relation is based on the approximately linear relation between the time derivative of the cellular contraction force and the cellular shortening velocity that results from the combined characteristics of LV and aortic compliances., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Kato et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Anthracyclines can cause cancer therapy-related cardiac dysfunction (CTRCD) that adversely affects prognosis. Despite guideline recommendations, only half of the patients undergo surveillance echocardiograms. An AI model detecting reduced left ventricular ejection fraction from 12-lead electrocardiograms (ECG) (AI-EF model) suggests ECG features reflect left ventricular pathophysiology. We hypothesized that AI could predict CTRCD from baseline ECG, leveraging the AI-EF model's insights, and developed the AI-CTRCD model using transfer learning on the AI-EF model. In 1011 anthracycline-treated patients, 8.7% experienced CTRCD. High AI-CTRCD scores indicated elevated CTRCD risk (hazard ratio (HR), 2.66; 95% CI 1.73-4.10; log-rank p < 0.001). This remained consistent after adjusting for risk factors (adjusted HR, 2.57; 95% CI 1.62-4.10; p < 0.001). AI-CTRCD score enhanced prediction beyond known factors (time-dependent AUC for 2 years: 0.78 with AI-CTRCD score vs. 0.74 without; p = 0.005). In conclusion, the AI model robustly stratified CTRCD risk from baseline ECG., (© 2024. The Author(s).)

Background: The complexity of leadless pacemaker (LP) implantation varies widely. However, the predictive factors determining this difficulty are poorly understood., Objective: The purpose of this study was to evaluate the factors influencing LP implantation difficulty, specifically procedural time during right atrial (RA) and right ventricular (RV) manipulation, based on patient background, cardiac function, and anatomic characteristics., Methods: Analysis included LP implantation cases between 2017 and 2023, excluding the initial 3 implants performed by each operator. The relevance of patient background, cardiac function, and anatomic features on procedural and fluoroscopy times was evaluated., Results: Fifty-four patients (mean age 82.2 ± 10.0 years; 57.4% male) were included in the study. Median procedural and fluoroscopy time was 45.8 minutes and 16.0 minutes, respectively, with an average of 2.0 ± 1.4 device deployments. Univariate analysis showed associations between procedural time and older age, RA and RV diameter, and severity of tricuspid regurgitation (TR). After adjustment for physician and potential contributing factors, RV dilation (midventricular diameter ≥35 mm) and severe TR were identified as independent predictors of prolonged procedural time. Medical history exhibited no association with procedural time. Consistent results were observed in analyses using fluoroscopy time as the outcome., Conclusion: RV dilation and severe TR were associated with prolonged procedural time for LP implantation. Anatomic features obtained from preprocedural echocardiography could provide valuable insights into both the safety and efficiency of LP implantation, thereby enhancing tailored treatment strategies for patients undergoing pacemaker implantation., (© 2023 Heart Rhythm Society. Published by Elsevier Inc.)

We herein report a case of myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) that occurred following coronavirus disease 2019 (COVID-19) vaccination and its subsequent relapse after COVID-19 infection. A 34-year-old woman developed cortical encephalitis in the right temporoparietal lobe one week after receiving the mRNA-1273 vaccine. The cerebrospinal fluid was positive for anti-MOG antibody. Her symptoms gradually improved after three courses of intravenous methylprednisolone therapy. Six months later, she experienced a relapse of transverse myelitis following COVID-19 infection. Despite treatment with plasma exchange, the patient remained paralyzed in both lower limbs. We herein review the relationship between MOGAD and COVID-19 vaccination/infection.

Although repolarization has been suggested to propagate in cardiac tissue both theoretically and experimentally, it has been challenging to estimate how and to what extent the propagation of repolarization contributes to relaxation because repolarization only occurs in the course of membrane excitation in normal hearts. We established a mathematical model of a 1D strand of 600 myocytes stabilized at an equilibrium potential near the plateau potential level by introducing a sustained component of the late sodium current ( I NaL ). By applying a hyperpolarizing stimulus to a small part of the strand, we succeeded in inducing repolarization which propagated along the strand at a velocity of 1~2 cm/s. The ionic mechanisms responsible for repolarization at the myocyte level, i.e., the deactivation of both the I NaL and the L-type calcium current ( I CaL ), and the activation of the rapid component of delayed rectifier potassium current ( I Kr ) and the inward rectifier potassium channel ( I K1 ), were found to be important for the propagation of repolarization in the myocyte strand. Using an analogy with progressive activation of the sodium current ( I Na ) in the propagation of excitation, regenerative activation of the predominant magnitude of I K1 makes the myocytes at the wave front start repolarization in succession through the electrical coupling via gap junction channels.

To date, no effective treatment has been established for photoreceptor loss due to energy imbalances, but numerous therapeutic approaches have reported some success in slowing photoreceptor degeneration by downregulating energy demand. However, the detailed mechanisms remain unclear. This study aimed to clarify the composition of ATP consumption factors in photoreceptors in darkness and in light. We introduced mathematical formulas for ionic current activities combined with a phototransduction model to form a new mathematical model for estimating the energy expenditure of each ionic current. The proposed model included various ionic currents identified in mouse rods using a gene expression database incorporating an available electrophysiological recording of each specific gene. ATP was mainly consumed by Na + /K + -ATPase and plasma membrane Ca 2+ -ATPase pumps to remove excess Na + and Ca 2+ . The rod consumed 7 [Formula: see text] 10 7 molecules of ATP s -1 , where 65% was used to remove ions from the cyclic nucleotide-gated channel and 20% from the hyperpolarization-activated current in darkness. Increased light intensity raised the energy requirements of the complex phototransduction cascade mechanisms. Nevertheless, the overall energy consumption was less than that in darkness due to the significant reduction in ATPase activities, where the hyperpolarization-activated current proportion increased to 83%. A better understanding of energy demand/supply may provide an effective tool for investigating retinal pathophysiological changes and analyzing novel therapeutic treatments related to the energy consumption of photoreceptors., (© 2023. Springer Nature Limited.)

Premature cardiac myocytes derived from human induced pluripotent stem cells (hiPSC-CMs) show heterogeneous action potentials (APs), probably due to different expression patterns of membrane ionic currents. We developed a method for determining expression patterns of functional channels in terms of whole-cell ionic conductance (G x ) using individual spontaneous AP configurations. It has been suggested that apparently identical AP configurations can be obtained using different sets of ionic currents in mathematical models of cardiac membrane excitation. If so, the inverse problem of G x estimation might not be solved. We computationally tested the feasibility of the gradient-based optimization method. For a realistic examination, conventional 'cell-specific models' were prepared by superimposing the model output of AP on each experimental AP recorded by conventional manual adjustment of G x s of the baseline model. G x s of 4-6 major ionic currents of the 'cell-specific models' were randomized within a range of ± 5-15% and used as an initial parameter set for the gradient-based automatic G x s recovery by decreasing the mean square error (MSE) between the target and model output. Plotting all data points of the MSE-G x relationship during optimization revealed progressive convergence of the randomized population of G x s to the original value of the cell-specific model with decreasing MSE. The absence of any other local minimum in the global search space was confirmed by mapping the MSE by randomizing G x s over a range of 0.1-10 times the control. No additional local minimum MSE was obvious in the whole parameter space, in addition to the global minimum of MSE at the default model parameter., (© 2022. The Author(s).)

Heart rate variability (HRV) is the heart beat-to-beat variation under control of the cardiovascular function of animals. Under stressed conditions, cardiac activity is generally regulated with an upregulated sympathetic tone and withdrawal of vagal tone; thus, HRV monitoring can be a non-invasive technique to assess stress level in animals especially related to animal welfare. Among several stress-induced factors, heat stress is one of the most serious causes of physiological damage to animals. The aim of this study was to assess the effects of heat stress on HRV in small ruminants under free-moving conditions. In three experimental periods (June, August, and October), inter-beat intervals in sheep and goats (three for each) in two consecutive days were measured. HRV parameters were calculated from the inter-beat interval data by three types of analyses: time domain, frequency domain, and non-linear analyses. The temperature-humidity index (THI) was used as an indicator of heat stress, and vectorial dynamic body acceleration (VeDBA) was calculated to quantify the physical activity of the animals tested. First, we investigated correlations of THI and VeDBA with HRV parameters; subsequently, THI was divided into five categories according to the values obtained (≤ 65, 65-70, 70-75, 75-80, and >80), and the effects of the THI categories on HRV parameters were investigated with and without correcting for the effects of physical activity based on the VeDBA. The results indicated that HRV significantly decreased with increasing THI and VeDBA. For non-linear HRV parameters that were corrected for the effects of physical activity, it was suggested that there would be a threshold of THI around 80 that strongly affected HRV; high heat stress can affect the autonomic balance of animals non-linearly by inducing the sympathetic nervous system. In conclusion, to assess psychophysiological conditions of unrestrained animals by HRV analysis, the confounding effect of physical activity on HRV should be minimized for a more precise interpretation of the results., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Kitajima, Oishi, Miwa, Anzai, Setoguchi, Yasunaka, Himeno, Kumagai and Hirooka.)

Background and Aim: Lenvatinib (LEN) has an antitumor effect with an early reduction in contrast enhancement for unresectable hepatocellular carcinoma (HCC). The aim of this study was to reveal the most useful radiological response evaluation for overall survival (OS) in patients treated with LEN., Methods: Patients receiving LEN therapy ( n = 80) were retrospectively recruited from April 2018 to January 2020. Enhanced computed tomography scans were performed at baseline and every 4-8 weeks. OS and radiological response were evaluated using response evaluation criteria in solid tumors (RECIST 1.1), modified RECIST (mRECIST), and Choi criteria. To be eligible for study, a minimal cumulative duration of LEN was 4 weeks. A total of 62 patients were included in the analysis., Results: The median OS was 469 days. The RECIST 1.1, mRECIST, and Choi criteria identified 14 (22.5%), 30 (48.3%), and 33 (53.2%) patients with an objective response, respectively. In the univariate analysis, Child-Pugh class B, major vascular invasion, and high alpha-fetoprotein (>200) were statistically significant poor prognostic factors. Radiological response was a significantly better prognostic factor in each criterion (RECIST, mRECIST, and Choi). In the multivariate analysis, radiological response evaluated by RECIST (hazard ratio, 0.259; 95% confidence interval, 0.0723-0.928; P = 0.038) was an independent factor. Furthermore, only RECIST significantly stratified prognosis ( P = 0.041) when limited to the first evaluation., Conclusion: RECIST 1.1 was useful even as early therapeutic evaluation for HCC patients treated with LEN. Understanding the characteristics of radiological response over time may contribute to improving the prognosis of patients with HCC., (© 2020 The Authors. JGH Open: An open access journal of gastroenterology and hepatology published by Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.)

Cardiomyocytes and myocardial sleeves dissociated from pulmonary veins (PVs) potentially generate ectopic automaticity in response to noradrenaline (NA), and thereby trigger atrial fibrillation. We developed a mathematical model of rat PV cardiomyocytes (PVC) based on experimental data that incorporates the microscopic framework of the local control theory of Ca 2+ release from the sarcoplasmic reticulum (SR), which can generate rhythmic Ca 2+ release (limit cycle revealed by the bifurcation analysis) when total Ca 2+ within the cell increased. Ca 2+ overload in SR increased resting Ca 2+ efflux through the type II inositol 1,4,5-trisphosphate (IP 3 ) receptors (InsP 3 R) as well as ryanodine receptors (RyRs), which finally triggered massive Ca 2+ release through activation of RyRs via local Ca 2+ accumulation in the vicinity of RyRs. The new PVC model exhibited a resting potential of -68 mV. Under NA effects, repetitive Ca 2+ release from SR triggered spontaneous action potentials (APs) by evoking transient depolarizations (TDs) through Na + /Ca 2+ exchanger (AP TD s). Marked and variable latencies initiating AP TD s could be explained by the time courses of the α1- and β1-adrenergic influence on the regulation of intracellular Ca 2+ content and random occurrences of spontaneous TD activating the first AP TD . Positive and negative feedback relations were clarified under AP TD generation.

Heart rate variability (HRV) analysis is a widely used technique to assess sympatho-vagal regulation in response to various internal or external stressors. However, HRV measurements under free-moving conditions are highly susceptible to subjects' physical activity levels because physical activity alters energy metabolism, which inevitably modulates the cardiorespiratory system and thereby changes the sympatho-vagal balance, regardless of stressors. Thus, researchers must simultaneously quantify the effect of physical activity on HRV to reliably assess sympatho-vagal balance under free-moving conditions. In the present study, dynamic body acceleration (DBA), which was developed in the field of animal ecology as a quantitative proxy for activity-specific energy expenditure, was used as a factor to correct for physical activity when evaluating HRV in freely moving subjects. Body acceleration and heart inter-beat intervals were simultaneously measured in cattle and sheep, and the vectorial DBA and HRV parameters were evaluated at 5-min intervals. Next, the effects of DBA on the HRV parameters were statistically analyzed. The heart rate (HR) and most of the HRV parameters were affected by DBA in both animal species, and the inclusion of the effect of DBA in the HRV analysis greatly influenced the frequency domain and nonlinear HRV parameters. By removing the effect of physical activity quantified using DBA, we could fairly compare the stress levels of animals with different physical activity levels under different management conditions. Moreover, we analyzed and compared the HRV parameters before and after correcting for the mean HR, with and without inclusion of DBA. The results were somewhat unexpected, as the effect of DBA was a highly significant source of HRV also in parameters corrected for mean HR. In conclusion, the inclusion of DBA as a physical activity index is a simple and useful method for correcting the activity-specific component of HRV under free-moving conditions.

A new glucose transport model relying upon diffusion and convection across the capillary membrane was developed, and supplemented with tissue space and lymph flow. The rate of glucose utilization (J util ) in the tissue space was described as a saturation function of glucose concentration in the interstitial fluid (C glu,isf ), and was varied by applying a scaling factor f to J max . With f = 0, the glucose diffusion ceased within ~20 min. While, with increasing f, the diffusion was accelerated through a decrease in C glu,isf , but the convective flux remained close to resting level. When the glucose supplying capacity of the capillary was measured with a criterion of J util /J max  = 0.5, the capacity increased in proportion to the number of perfused capillaries. A consistent profile of declining C glu,isf along the capillary axis was observed at the criterion of 0.5 irrespective of the capillary number. Increasing blood flow scarcely improved the supplying capacity.

Key Points: The cardiac energy metabolites such as ATP, phosphocreatine, ADP and NADH are kept relatively constant during physiological cardiac workload transition. How this is accomplished is not yet clarified, though Ca 2+ has been suggested to be one of the possible mechanisms. We constructed a detailed mathematical model of cardiac mitochondria based on experimental data and studied whether known Ca 2+ -dependent regulation mechanisms play roles in the metabolite constancy. Model simulations revealed that the Ca 2+ -dependent regulation mechanisms have important roles under the in vitro condition of isolated mitochondria where malate and glutamate were mitochondrial substrates, while they have only a minor role and the composition of substrates has marked influence on the metabolite constancy during workload transition under the simulated in vivo condition where many substrates exist. These results help us understand the regulation mechanisms of cardiac energy metabolism during physiological cardiac workload transition., Abstract: The cardiac energy metabolites such as ATP, phosphocreatine, ADP and NADH are kept relatively constant over a wide range of cardiac workload, though the mechanisms are not yet clarified. One possible regulator of mitochondrial metabolism is Ca 2+ , because it activates several mitochondrial enzymes and transporters. Here we constructed a mathematical model of cardiac mitochondria, including oxidative phosphorylation, substrate metabolism and ion/substrate transporters, based on experimental data, and studied whether the Ca 2+ -dependent activation mechanisms play roles in metabolite constancy. Under the in vitro condition of isolated mitochondria, where malate and glutamate were used as mitochondrial substrates, the model well reproduced the Ca 2+ and inorganic phosphate (P i ) dependences of oxygen consumption, NADH level and mitochondrial membrane potential. The Ca 2+ -dependent activations of the aspartate/glutamate carrier and the F 1 F o -ATPase, and the P i -dependent activation of Complex III were key factors in reproducing the experimental data. When the mitochondrial model was implemented in a simple cardiac cell model, simulation of workload transition revealed that cytoplasmic Ca 2+ concentration ([Ca 2+ ] cyt ) within the physiological range markedly increased NADH level. However, the addition of pyruvate or citrate attenuated the Ca 2+ dependence of NADH during the workload transition. Under the simulated in vivo condition where malate, glutamate, pyruvate, citrate and 2-oxoglutarate were used as mitochondrial substrates, the energy metabolites were more stable during the workload transition and NADH level was almost insensitive to [Ca 2+ ] cyt . It was revealed that mitochondrial substrates have a significant influence on metabolite constancy during cardiac workload transition, and Ca 2+ has only a minor role under physiological conditions., (© 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.)

Background: Control of the extracellular fluid volume is one of the most indispensable issues for homeostasis of the internal milieu. However, complex interdependence of the pressures involved in determination of fluid exchange makes it difficult to predict a steady-state tissue volume under various physiological conditions without mathematical approaches., Methods: Here, we developed a capillary model based on the Starling's principle, which allowed us to clarify the mechanisms of the interstitial-fluid volume regulation. Three well known safety factors against edema: (1) low tissue compliance in negative pressure ranges; (2) lymphatic flow driven by the tissue pressure; and (3) protein washout by the lymph, were incorporated into the model in sequence., Results: An increase in blood pressure at the venous end of the capillary induced an interstitial-fluid volume increase, which, in turn, reduced negative tissue pressure to prevent edema. The lymphatic flow alleviated the edema by both carrying fluid away from the tissue and decreasing the colloidal osmotic pressure. From the model incorporating all three factors, we found that the interstitial-fluid volume changed quickly after the blood pressure change, and that the protein movement towards a certain equilibrium point followed the volume change., Conclusion: Mathematical analyses revealed that the system of the capillary is stable near the equilibrium point at steady state and normal physiological capillary pressure. The time course of the tissue-volume change was determined by two kinetic mechanisms: rapid fluid exchange and slow protein fluxes.

Cardiac Ca(2+)-induced Ca(2+) release (CICR) occurs by a regenerative activation of ryanodine receptors (RyRs) within each Ca(2+)-releasing unit, triggered by the activation of L-type Ca(2+) channels (LCCs). CICR is then terminated, most probably by depletion of Ca(2+) in the junctional sarcoplasmic reticulum (SR). Hinch et al. previously developed a tightly coupled LCC-RyR mathematical model, known as the Hinch model, that enables simulations to deal with a variety of functional states of whole-cell populations of a Ca(2+)-releasing unit using a personal computer. In this study, we developed a membrane excitation-contraction model of the human ventricular myocyte, which we call the human ventricular cell (HuVEC) model. This model is a hybrid of the most recent HuVEC models and the Hinch model. We modified the Hinch model to reproduce the regenerative activation and termination of CICR. In particular, we removed the inactivated RyR state and separated the single step of RyR activation by LCCs into triggering and regenerative steps. More importantly, we included the experimental measurement of a transient rise in Ca(2+) concentrations ([Ca(2+)], 10-15 μM) during CICR in the vicinity of Ca(2+)-releasing sites, and thereby calculated the effects of the local Ca(2+) gradient on CICR as well as membrane excitation. This HuVEC model successfully reconstructed both membrane excitation and key properties of CICR. The time course of CICR evoked by an action potential was accounted for by autonomous changes in an instantaneous equilibrium open probability of couplons. This autonomous time course was driven by a core feedback loop including the pivotal local [Ca(2+)], influenced by a time-dependent decay in the SR Ca(2+) content during CICR., (Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.)

A 77-year-old man previously treated with maintenance hemodialysis was admitted due to appetite loss, nausea and shortness of breath. He showed progressive heart failure and eosinophilia without any basal disorders and was diagnosed with idiopathic hypereosinophilic syndrome (HES) accompanied by eosinophilic myocarditis. Laboratory data revealed hypercalcemia, a low serum parathyroid hormone level and a high 1,25(OH)(2)D concentration in spite of renal failure and no causal medications. Steroid therapy resulted in the patient's rapid recovery from heart failure, hypereosinophilia and hypercalcemia. Since the serum 1,25(OH)(2)D level promptly and markedly decreased, the hypercalcemia complicated with HES was most likely caused by extrarenal production of 1,25(OH)(2)D.

To clarify the mechanisms underlying the pancreatic β-cell response to varying glucose concentrations ([G]), electrophysiological findings were integrated into a mathematical cell model. The Ca(2+) dynamics of the endoplasmic reticulum (ER) were also improved. The model was validated by demonstrating quiescent potential, burst-interburst electrical events accompanied by Ca(2+) transients, and continuous firing of action potentials over [G] ranges of 0-6, 7-18, and >19 mM, respectively. These responses to glucose were completely reversible. The action potential, input impedance, and Ca(2+) transients were in good agreement with experimental measurements. The ionic mechanisms underlying the burst-interburst rhythm were investigated by lead potential analysis, which quantified the contributions of individual current components. This analysis demonstrated that slow potential changes during the interburst period were attributable to modifications of ion channels or transporters by intracellular ions and/or metabolites to different degrees depending on [G]. The predominant role of adenosine triphosphate-sensitive K(+) current in switching on and off the repetitive firing of action potentials at 8 mM [G] was taken over at a higher [G] by Ca(2+)- or Na(+)-dependent currents, which were generated by the plasma membrane Ca(2+) pump, Na(+)/K(+) pump, Na(+)/Ca(2+) exchanger, and TRPM channel. Accumulation and release of Ca(2+) by the ER also had a strong influence on the slow electrical rhythm. We conclude that the present mathematical model is useful for quantifying the role of individual functional components in the whole cell responses based on experimental findings.

Background: Pandemic influenza A(H1N1) virus infection quickly circulated worldwide in 2009. In Japan, the first case was reported in May 2009, one month after its outbreak in Mexico. Thereafter, A(H1N1) infection spread widely throughout the country. It is of great importance to profile and understand the situation regarding viral mutations and their circulation in Japan to accumulate a knowledge base and to prepare clinical response platforms before a second pandemic (pdm) wave emerges., Methodology: A total of 253 swab samples were collected from patients with influenza-like illness in the Osaka, Tokyo, and Chiba areas both in May 2009 and between October 2009 and January 2010. We analyzed partial sequences of the hemagglutinin (HA) and neuraminidase (NA) genes of the 2009 pdm influenza virus in the collected clinical samples. By phylogenetic analysis, we identified major variants of the 2009 pdm influenza virus and critical mutations associated with severe cases, including drug-resistance mutations., Results and Conclusions: Our sequence analysis has revealed that both HA-S220T and NA-N248D are major non-synonymous mutations that clearly discriminate the 2009 pdm influenza viruses identified in the very early phase (May 2009) from those found in the peak phase (October 2009 to January 2010) in Japan. By phylogenetic analysis, we found 14 micro-clades within the viruses collected during the peak phase. Among them, 12 were new micro-clades, while two were previously reported. Oseltamivir resistance-related mutations, i.e., NA-H275Y and NA-N295S, were also detected in sporadic cases in Osaka and Tokyo., (© 2011 Morlighem et al.)

The question of the extent to which cytosolic Ca(2+) affects sinoatrial node pacemaker activity has been discussed for decades. We examined this issue by analyzing two mathematical pacemaker models, based on the "Ca(2+) clock" (C) and "membrane clock" (M) hypotheses, together with patch-clamp experiments in isolated guinea pig sinoatrial node cells. By applying lead potential analysis to the models, the C mechanism, which is dependent on potentiation of Na(+)/Ca(2+) exchange current via spontaneous Ca(2+) release from the sarcoplasmic reticulum (SR) during diastole, was found to overlap M mechanisms in the C model. Rapid suppression of pacemaker rhythm was observed in the C model by chelating intracellular Ca(2+), whereas the M model was unaffected. Experimental rupturing of the perforated-patch membrane to allow rapid equilibration of the cytosol with 10 mM BAPTA pipette solution, however, failed to decrease the rate of spontaneous action potential within ∼30 s, whereas contraction ceased within ∼3 s. The spontaneous rhythm also remained intact within a few minutes when SR Ca(2+) dynamics were acutely disrupted using high doses of SR blockers. These experimental results suggested that rapid disruption of normal Ca(2+) dynamics would not markedly affect spontaneous activity. Experimental prolongation of the action potentials, as well as slowing of the Ca(2+)-mediated inactivation of the L-type Ca(2+) currents induced by BAPTA, were well explained by assuming Ca(2+) chelation, even in the proximity of the channel pore in addition to the bulk cytosol in the M model. Taken together, the experimental and model findings strongly suggest that the C mechanism explicitly described by the C model can hardly be applied to guinea pig sinoatrial node cells. The possible involvement of L-type Ca(2+) current rundown induced secondarily through inhibition of Ca(2+)/calmodulin kinase II and/or Ca(2+)-stimulated adenylyl cyclase was discussed as underlying the disruption of spontaneous activity after prolonged intracellular Ca(2+) concentration reduction for >5 min.

The action potential, once triggered in ventricular or atrial myocytes, automatically proceeds on its time course or is generated spontaneously in sinoatrial node pacemaker cells. It is induced by complex interactions among such cellular components as ion channels, transporters, intracellular ion concentrations, and signaling molecules. We have developed what is, to our knowledge, a new method using a mathematical model to quantify the contribution of each cellular component to the automatic time courses of the action potential. In this method, an equilibrium value, which the membrane potential is approaching at a given moment, is calculated along the time course of the membrane potential. The calculation itself is based on the time-varying conductance and the reversal potentials of individual ion channels and electrogenic ion transporters. Since the equilibrium potential moves in advance of the membrane potential change, we refer to it as the lead potential, V(L). The contribution of an individual current was successfully quantified by comparing dV(L)/dt before and after fixing the time-dependent change of a component of interest, such as the variations in the open probability of a channel or the turnover rate of an ion transporter. In addition to the action potential, the lead-potential analysis should also be applicable in all types of membrane excitation in many different kinds of cells.

Positive chronotropy induced by beta1-adrenergic stimulation is achieved by multiple interactions of ion channels and transporters in sinoatrial node pacemaker cells (SANs). To investigate the ionic mechanisms, we updated our SAN model developed in 2003 and incorporated the beta1-adrenergic signaling cascade developed by Kuzumoto et al. (2007). Since the slow component of the delayed rectifier K+ current (IKs) is one of the major targets of the beta1-adrenergic cascade, we developed a guinea pig model with a large IKs. The new model provided a good representation of the experimental characteristics of SANs. A comparison of individual current during diastole recorded before and after beta1-adrenergic stimulation clearly showed the negative shift of the L-type Ca2+ current (ICaL) takeoff potential, enlargement of the sustained inward current (I st), and the hyperpolarization-activated nonselective cation current (Iha) played major roles in increasing the firing frequency. Deactivation of IKs during diastole scarcely contributed to the time-dependent decrease in membrane K+ conductance, which was the major mechanism for slow diastolic depolarization, as indicated by calculating the instantaneous equilibrium potential (lead potential). This was because the activation of IKs during the preceding action potential was negligibly small. However, IKs was important in counterbalancing the increase in ICaL and the Na+/Ca2+ exchange current (INaCa), which otherwise compromised the positive chronotropic effect by elongating the action potential duration. Enhanced Ca2+ release from the sarcoplasmic reticulum failed to induce an obvious chronotropic effect in our model.

A 46-year-old male with long-term treatment-resistant hypertension and past history of cerebral hemorrhage was found to have suppressed plasma renin activity (PRA) and normal plasma aldosterone concentration (PAC) with aldosterone/renin ratio of 25.3. Furosemide plus upright test did not stimulate PRA, but computed tomography scan of the abdomen revealed no abnormal lesions in either adrenal gland. Selective adrenal venous sampling (SAVS) showed that PAC in the left and the right adrenal vein were 1000 ng/dl and 230 ng/dl, respectively, which increased to 1500 ng/dl and 620 ng/dl, respectively, after ACTH stimulation. Diagnosis of primary aldosteronism due to hypersecretion of aldosterone from the left adrenal gland was made, and laparoscopic left adrenalectomy was performed. Pathological examination of the 'apparently normal' adrenal tissue resected revealed the presence of poorly encapsulated multiple adrenocortical micronodules which showed positive immunoreactivity for 3beta-hydroxysteroid dehydrogenase by immunohistochemical study, but negative immunoreactivity in the hyperplastic zona glomerulosa consistent with paradoxical hyperplasia associated with primary aldosteronism. Postoperatively, PRA was normalized and his high blood pressure was well controlled with lower doses of antihypertensive drugs than those used before surgery. The clinicopathological features of our case are consistent with the diagnosis of unilateral multiple adrenocortical micronodules (UMN), a new subset of primary aldosteronism, in which SAVS proved to be a useful diagnostic tool for its localization.

Purpose: Pancreatic cancer has a poor prognosis and few effective therapies are available. The oncolytic effect of reovirus has been observed in cancer cells with an activated Ras signaling pathway, and pancreatic cancer may be a candidate target for reovirus because K-ras mutation is frequently found in pancreatic cancer., Experimental Design: In this study, we examined the feasibility of using reovirus (serotype 3) as an antihuman pancreatic cancer agent., Results: Reovirus was able to infect five human pancreatic cancer cell lines (Panc1, MIApaca-2, PK1, PK9, and BxPC3) in vitro. We also confirmed that the Ras activity in these cancer cell lines was elevated compared with that in the normal cell line and that susceptibility to reovirus was associated with the Ras activity of these cells. In a unilateral murine xenograft model using Panc1 and BxPC3 cell lines, each tumor growth was suppressed by intratumoral injection of reovirus. Furthermore, local injection of reovirus also had systemic antitumor effects in a bilateral xenograft model using Panc1 cell line. Immunohistochemical examination revealed that reovirus replication was observed within the tumor but not in surrounding normal tissue., Conclusions: These results suggest that reovirus can be considered for a novel therapy against pancreatic cancer.

Background and Purpose: Renal artery lesions in moyamoya disease have been described sporadically in several case reports. The purpose of this study is to evaluate the angiographic findings of renal artery lesions in moyamoya disease and to determine the prevalence of renal artery lesions in patients with moyamoya disease., Methods: Eighty-six consecutive patients with idiopathic moyamoya disease were prospectively examined with both cerebral angiography and abdominal aortography. The findings of abdominal aortography were reviewed for the presence and appearance of renal artery lesions and compared with the clinical data and cerebral angiographic findings., Results: Of 86 patients with idiopathic moyamoya disease, 7 patients (8%) were found to have renal artery lesions. Six patients (7%) had stenosis in the renal artery, and 1 patient (1%) had a small saccular aneurysm in the renal artery. Two patients (2%) with a marked renal artery stenosis presented with renovascular hypertension, which resulted in an intraventricular hemorrhage in 1 patient. Furthermore, the renal artery stenosis in the 2 patients with renovascular hypertension was successfully treated with percutaneous transluminal angioplasty. There was no significant correlation between the presence of renal artery lesions and cerebral angiographic findings., Conclusions: Seven (8%) of 86 patients with moyamoya disease showed renal artery lesions, including 6 stenoses (7%) and 1 aneurysm (1%). Renal artery lesions are a clinically relevant systemic manifestation in patients with moyamoya disease.

A teratogenicity study of Prednisolone farnesylate (PNF), a newly synthesized corticosteroid, was conducted in Sprague-Dawley rats. This compound was administrated subcutaneously to female rats at dose levels of 0(control), 1, 5 and 25 mg/kg/day, once a day, for 11 days from day 7 to day 17 of pregnancy. In each dose group, 26 or 27 dams were killed on day 20 of pregnancy to examine their fetuses. The remaining 14 or 15 dams of each group were allowed to litter naturally, and observations were made on the postnatal growth and development of their offspring. 1. In the dams treated at doses of 1 mg/kg or more, decreased body weight gains and food consumption and retention of the substance at the injected site were noted. However, general signs, parturition, lactation and nursing behaviors were not affected by the administration of PNF. 2. In the F1 fetuses, no embryonic or fetal lethal effect, fetal retardation and teratogenic effect were noted. 3. In the F1 newborns, the postnatal growth, development, responses, behaviors, learning ability and reproductive ability were not influenced. Additionally, no embryonic or fetal abnormalities of their fetuses (F2) were detected. From these results, the no-effect dose levels of PNF on the parental general states, the parental reproductive ability and those of the F1 offspring are thought to be less than 1 mg/kg/day, 25 mg/kg/day and 25 mg/kg/day, respectively, under the experimental conditions of this study. Moreover, the F2 fetuses are not affected by doses up to 25 mg/kg/day of PNF.

A fertility study of Prednisolone farnesylate (PNF), a newly synthesized corticosteroid, was conducted in Sprague-Dawley rats. This compound was administered subcutaneously at dose levels of 0(control), 0.04, 0.2 and 1 mg/kg/day to males for 63 days before mating and during the mating period, and to females for 14 days before mating, through the mating period and until day 7 of pregnancy. Each 24 male and female rats were mated, and females were killed on day 20 of pregnancy to examine their fetuses. 1. In the parental animals, loss of fur or thin fur and incrustation of treated site occurred in male rats treated at doses of 0.2 mg/kg or more and female rats treated at dose of 1 mg/kg, and at the same dose groups, the thinning of skin, atrophy of the thymus and intention of the substance at the injected site were noted. Moreover, body weight gains and food consumption were suppressed in both sexes treated at the dose of 1 mg/kg. 2. Fertility and reproductive ability in both sexes, and estrus cycles in female rats were not affected by administration of PNF. 3. In the fetuses, no embryonic or fetal lethal effect and teratogenic effect were noted. From these results, the no-effect dose levels of PNF on the parental general states, the parental reproductive ability and those of the fetuses are thought to be 0.04 mg/kg/day, 1 mg/kg/day or more and 1 mg/kg/day or more, respectively, under the experimental conditions of this study.

To elucidate the role of oncogene expression in hepatocarcinogenesis, we examined the expression of 4 cellular oncogenes (c-myc, c-fos, Ha-ras and c-erbA) in liver tissues induced by chemical agents. Four groups of male Sprague-Dawley rats were examined in the present study. Rats of the first and second groups were given a single intraperitoneal injection of diethylnitrosamine (DEN), 200 mg/kg body weight. Two weeks later, these rats were divided into two groups; the DEN-C group received no further medication, whereas the DEN-DES group was given diethylstilbestrol (DES), 0.5 mg/day, for 12 months. The DEN group was given DEN, 100 ppm, in drinking water for five months as the hepatocellular carcinoma (HCC) group. The DES group was given DES, 0.5 mg/day, from the start for 8 months. Rats of the DEN-DES and DEN groups developed grossly visible hepatic tumors. Significantly higher levels of c-myc gene expression were observed in tissues of HCC of the DEN group and in neoplastic nodules of the DEN-DES groups than in the DES and DEN-C group. The increase of c-myc mRNA seemed to begin after 1 month of treatment and became significant at 4 months in the DEN-DES group. On the other hand, no significant differences in mRNA levels of c-fos, Ha-ras and c-erbA were observed among these four groups. Although the significance of increased c-myc gene expression in neoplastic liver is still not known, it is conceivable that the persistent elevation of c-myc gene expression in the DEN and DEN-DES groups might contribute to the development of rat chemical hepatotumorigenesis.