Mechanistic characterization of disulfide bond reduction of an ERAD substrate mediated by cooperation between ERdj5 and BiP.

Endoplasmic reticulum (ER)-associated degradation (ERAD) is a protein quality control process that eliminates misfolded proteins from the ER. DnaJ homolog subfamily C member 10 (ERdj5) is a protein disulfide isomerase family member that accelerates ERAD by reducing disulfide bonds of aberrant proteins with the help of an ER-resident chaperone BiP. However, the detailed mechanisms by which ERdj5 acts in concert with BiP are poorly understood. In this study, we reconstituted an in vitro system that monitors ERdj5-mediated reduction of disulfide-linked J-chain oligomers, known to be physiological ERAD substrates. Biochemical analyses using purified proteins revealed that J-chain oligomers were reduced to monomers by ERdj5 in a stepwise manner via trimeric and dimeric intermediates, and BiP synergistically enhanced this action in an ATP-dependent manner. Single-molecule observations of ERdj5-catalyzed J-chain disaggregation using high-speed atomic force microscopy, demonstrated the stochastic release of small J-chain oligomers through repeated actions of ERdj5 on peripheral and flexible regions of large J-chain aggregates. Using systematic mutational analyses, ERAD substrate disaggregation mediated by ERdj5 and BiP was dissected at the molecular level.

A non-cell-autonomous circadian rhythm of bioluminescence reporter activities in individual duckweed cells.

The circadian clock is responsible for the temporal regulation of various physiological processes in plants. Individual cells contain a circadian oscillator consisting of a clock gene circuit that coordinates physiological rhythms within the plant body in an orderly manner. The coordination of time information has been studied from the perspective of cell-cell local coupling and long-distance communication between tissues based on the view that the behavior of circadian oscillators represents physiological rhythms. Here, we report the cellular circadian rhythm of bioluminescence reporters that are not governed by the clock gene circuit in expressing cells. We detected cellular bioluminescence rhythms with different free-running periods in the same cells using a dual-color bioluminescence monitoring system in duckweed (Lemna minor) transfected with Arabidopsis CIRCADIAN CLOCK ASSOCIATED 1::luciferace+ (AtCCA1::LUC+) and Cauliflower mosaic virus 35S::modified click-beetle red-color luciferase (CaMV35S::PtRLUC) reporters. Co-transfection experiments with the two reporters and a clock gene-overexpressing effector revealed that the AtCCA1::LUC+ rhythm, but not the CaMV35S::PtRLUC rhythm, was altered in cells with a dysfunctional clock gene circuit. This indicated that the AtCCA1::LUC+ rhythm is a direct output of the cellular circadian oscillator, whereas the CaMV35S::PtRLUC rhythm is not. After plasmolysis, the CaMV35S::PtRLUC rhythm disappeared, whereas the AtCCA1::LUC+ rhythm persisted. This suggests that the CaMV35S::PtRLUC bioluminescence has a symplast/apoplast-mediated circadian rhythm generated at the organismal level. The CaMV35S::PtRLUC-type bioluminescence rhythm was also observed when other bioluminescence reporters were expressed. These results reveal that the plant circadian system consists of both cell-autonomous and noncell-autonomous rhythms that are unaffected by cellular oscillators.

Living donor liver transplantation for myocerebrohepatopathy spectrum due to POLG mutations.

BACKGROUND: POLG is one of several nuclear genes associated with mitochondrial DNA maintenance defects and is a group of diseases caused by mitochondrial DNA deficiency that results in impaired adenosine triphosphate production and organ dysfunction. Myocerebrohepatopathy spectrum (MCHS) is the most severe and earliest presentation of POLG mutations, and liver transplantation (LT) for MCHS has never been reported. CASE PRESENTATION: The patient was a 3-month-old boy with acute liver failure and no neurological manifestations (e.g., seizures). We performed a living donor LT using a left lateral segment graft from his father. The postoperative course was uneventful. Subsequently, a homozygous POLG mutation (c.2890C>T, p. R964C) was identified by multigene analysis of neonatal/infantile intrahepatic cholestasis. Moreover, respiratory chain complex I, II, and III enzyme activities and the ratio of mtDNA to nuclear DNA in the liver were reduced. Therefore, we considered that these clinical manifestations and examination findings met the definition for MCHS. During meticulous follow-up, the patient had shown satisfactory physical growth and mental development until the time of writing this report. CONCLUSION: We presumed that the absence of remarkable neurologic manifestations prior to LT in patients with MCHS is a good indication for LT and contributes to a better prognosis in the present case.

Evaluation of novel indices of walking performance taking oxygen desaturation into account during six-minute walk test in cardiovascular disease patients.

In pulmonary disease patients since oxygen desaturation during 6-min walk test (6MWT) affects walk distance (6MWD), some novel indices such as desaturation/distance ratio [DDR, oxygen desaturation area (DAO2)/6MWD] and distance-saturation product [DSP, 6MWD × minimum peripheral oxygen saturation (SpO2)] are evaluated. However, there has been no study examining these indices that consider exercise-induced desaturation (EID) in patients with cardiovascular disease. In 94 cardiovascular disease patients without pulmonary complications, 6MWT and echocardiography were performed at the entry of cardiac rehabilitation. SpO2 was measured during 6MWT using a continuously monitorable pulse oximeter, and DSP and DDR were calculated using minimum SpO2 and DAO2 [sum of (100-SpO2) per second during 6MWT], respectively. EID was defined as SpO2 decrease of ≥ 4% or minimum SpO2 of < 90% during 6MWT. DSP was slightly lower and DDR was markedly higher in patients with EID than in those without. When examining correlations of DSP and DDR with their components, DSP was correlated with 6MWD much closely than minimum SpO2, while DDR was correlated as closely with DAO2 as 6MWD. Furthermore, DAO2, but not minimum SpO2, had a direct correlation with 6MWD. As for associations with cardiac function, DSP was correlated with several cardiac parameters, but DDR was not correlated with any of these parameters. Our findings suggest that oxygen desaturation during 6MWT affects walking distance in cardiovascular disease patients even without pulmonary complications and that DDR is more appropriate than DSP as an index of walking performance that takes EID into consideration, independently of cardiac function.

Low nitrogen conditions accelerate flowering by modulating the phosphorylation state of FLOWERING BHLH 4 in Arabidopsis.

Nitrogen (N) is an essential nutrient that affects multiple plant developmental processes, including flowering. As flowering requires resources to develop sink tissues for reproduction, nutrient availability is tightly linked to this process. Low N levels accelerate floral transition; however, the molecular mechanisms underlying this response are not well understood. Here, we identify the FLOWERING BHLH 4 (FBH4) transcription factor as a key regulator of N-responsive flowering in Arabidopsis Low N-induced early flowering is compromised in fbh quadruple mutants. We found that FBH4 is a highly phosphorylated protein and that FBH4 phosphorylation levels decrease under low N conditions. In addition, decreased phosphorylation promotes FBH4 nuclear localization and transcriptional activation of the direct target CONSTANS (CO) and downstream florigen FLOWERING LOCUS T (FT) genes. Moreover, we demonstrate that the evolutionarily conserved cellular fuel sensor SNF1-RELATED KINASE 1 (SnRK1), whose kinase activity is down-regulated under low N conditions, directly phosphorylates FBH4. SnRK1 negatively regulates CO and FT transcript levels under high N conditions. Together, these results reveal a mechanism by which N levels may fine-tune FBH4 nuclear localization by adjusting the phosphorylation state to modulate flowering time. In addition to its role in flowering regulation, we also showed that FBH4 was involved in low N-induced up-regulation of nutrient recycling and remobilization-related gene expression. Thus, our findings provide insight into N-responsive growth phase transitions and optimization of plant fitness under nutrient-limited conditions.

An endogenous basis for synchronisation characteristics of the circadian rhythm in proliferating Lemna minor plants.

The circadian clock is a cell-autonomous system that functions through the coordination of time information in the plant body. Synchronisation of cellular clocks is based on coordination mechanisms; the synchronisation characteristics of proliferating plants remain unclear. The bioluminescence circadian rhythms of fronds (leaf-like plant units) of proliferating Lemna minor plants carrying a circadian bioluminescence reporter, AtCCA1:LUC, were spatiotemporally analysed at a cell-level resolution. We focused on spontaneous circadian organisation under constant light conditions for plants with light : dark treatment (LD grown) or without it (LL grown). Fronds developing even from an LL-grown parental frond showed coherent circadian rhythms among them. This allowed the maintenance of circadian rhythmicity in proliferating plants. Inside a frond, a centrifugal phase/period pattern was observed in LD-grown plants, whereas various phase patterns with travelling waves were formed in LL-grown plants. These patterns were model simulated by local coupling of heterogeneous cellular circadian oscillators with different initial synchronous states in fronds. Spatiotemporal analysis of the circadian rhythms in proliferating plants reveals spontaneous synchronisation manners that are associated with local cell-cell coupling, spatial phase patterns and developmental stages.

Interspecific divergence of circadian properties in duckweed plants.

The circadian clock system is widely conserved in plants; however, divergence in circadian rhythm properties is poorly understood. We conducted a comparative analysis of the circadian properties of closely related duckweed species. Using a particle bombardment method, a circadian bioluminescent reporter was introduced into duckweed plants. We measured bioluminescence circadian rhythms of eight species of the genus Lemna and seven species of the genus Wolffiella at various temperatures (20, 25, and 30°C) and light conditions (constant light or constant dark). Wolffiella species inhabit relatively warm areas and lack some tissues/organs found in Lemna species. Lemna species tended to show robust bioluminescence circadian rhythms under all conditions, while Wolffiella species showed lower rhythm stability, especially at higher temperatures. For Lemna, two species (L. valdiviana and L. minuta) forming a clade showed relatively lower circadian stability. For Wolffiella, two species (W. hyalina and W. repanda) forming a clade showed extremely long period lengths. These analyses reveal that the circadian properties of species primarily reflect their phylogenetic positions. The relationships between geographical and morphological factors and circadian properties are also suggested.

Kinetics of atrial and brain natriuretic peptides during hemodialysis are regulated in association with different cardiac functional changes.

The blood levels of atrial and brain natriuretic peptides (ANP and BNP) are both increased markedly in hemodialysis patients, but the kinetics of the two are not always parallel. The present study investigated the association of changes in ANP and BNP levels before and after dialysis with changes in cardiac function in hemodialysis patients. A total of 57 patients (mean age 64 years, 47 males and 10 females) on maintenance hemodialysis with sinus rhythm were enrolled. Blood samples were taken at the beginning and end of dialysis, and plasma levels of ANP and BNP were measured. Changes in cardiac function during dialysis were examined by echocardiography performed just before and after dialysis. Both plasma ANP and BNP concentrations decreased significantly after hemodialysis, but the rate of decrease in BNP [mean ± SD, 555 ± 503 to 519 ± 477 pg/mL (- 6.4%), P = 0.011] was much smaller than that in ANP [233 ± 123 to 132 ± 83 pg/mL (- 43.4%), P < 0.001]. As for the relation to the changes in echocardiographic parameters before and after dialysis, the decrease in inferior vena cava diameter had a close correlation with the decrease in ANP (r = 0.528, P < 0.001), but not BNP. In contrast, the decrease in left ventricular end-diastolic volume index was correlated only with the decrease in BNP (r = 0.297, P = 0.035). The peak velocity ratio of early diastolic to atrial filling decreased with preload reduction by dialysis, and its decrease was more strongly correlated with the decrease in BNP (r = 0.407, P = 0.002) than that in ANP (r = 0.273, P = 0.040). These results demonstrated that in hemodialysis patients, the decrease in plasma ANP by a single dialysis was essentially caused by blood volume reduction, while BNP decrease was mainly induced by the reduction of left ventricular overload. Our findings indicate that the kinetics of both peptides during dialysis are regulated by different cardiac and hemodynamic factors.

Casein kinase 1 family regulates PRR5 and TOC1 in the Arabidopsis circadian clock.

The circadian clock provides organisms with the ability to adapt to daily and seasonal cycles. Eukaryotic clocks mostly rely on lineage-specific transcriptional-translational feedback loops (TTFLs). Posttranslational modifications are also crucial for clock functions in fungi and animals, but the posttranslational modifications that affect the plant clock are less understood. Here, using chemical biology strategies, we show that the Arabidopsis CASEIN KINASE 1 LIKE (CKL) family is involved in posttranslational modification in the plant clock. Chemical screening demonstrated that an animal CDC7/CDK9 inhibitor, PHA767491, lengthens the Arabidopsis circadian period. Affinity proteomics using a chemical probe revealed that PHA767491 binds to and inhibits multiple CKL proteins, rather than CDC7/CDK9 homologs. Simultaneous knockdown of Arabidopsis CKL-encoding genes lengthened the circadian period. CKL4 phosphorylated transcriptional repressors PSEUDO-RESPONSE REGULATOR 5 (PRR5) and TIMING OF CAB EXPRESSION 1 (TOC1) in the TTFL. PHA767491 treatment resulted in accumulation of PRR5 and TOC1, accompanied by decreasing expression of PRR5- and TOC1-target genes. A prr5 toc1 double mutant was hyposensitive to PHA767491-induced period lengthening. Together, our results reveal posttranslational modification of transcriptional repressors in plant clock TTFL by CK1 family proteins, which also modulate nonplant circadian clocks.

Detection of Uncoupled Circadian Rhythms in Individual Cells of Lemna minor using a Dual-Color Bioluminescence Monitoring System.

The plant circadian oscillation system is based on the circadian clock of individual cells. Circadian behavior of cells has been observed by monitoring the circadian reporter activity, such as bioluminescence of AtCCA1::LUC+. To deeply analyze different circadian behaviors in individual cells, we developed the dual-color bioluminescence monitoring system that automatically measured the luminescence of two luciferase reporters simultaneously at a single-cell level. We selected a yellow-green-emitting firefly luciferase (LUC+) and a red-emitting luciferase (PtRLUC) that is a mutant form of Brazilian click beetle ELUC. We used AtCCA1::LUC+ and CaMV35S::PtRLUC. CaMV35S::LUC+ was previously reported as a circadian reporter with a low-amplitude rhythm. These bioluminescent reporters were introduced into the cells of a duckweed, Lemna minor, by particle bombardment. Time series of the bioluminescence of individual cells in a frond were obtained using a dual-color bioluminescence monitoring system with a green-pass- and red-pass filter. Luminescence intensities from the LUC+ and PtRLUC of each cell were calculated from the filtered luminescence intensities. We succeeded in reconstructing the bioluminescence behaviors of AtCCA1::LUC+ and CaMV35S::PtRLUC in the same cells. Under prolonged constant light conditions, AtCCA1::LUC+ showed a robust circadian rhythm in individual cells in an asynchronous state in the frond, as previously reported. By contrast, CaMV35S::PtRLUC stochastically showed circadian rhythms in a synchronous state. These results strongly suggested the uncoupling of cellular behavior between these circadian reporters. This dual-color bioluminescence monitoring system is a powerful tool to analyze various stochastic phenomena accompanying large cell-to-cell variation in gene expression.

Role of active site arginine residues in substrate recognition by PPM1A.

Reversible protein phosphorylation is a key mechanism for regulating numerous cellular events. The metal-dependent protein phosphatases (PPM) are a family of Ser/Thr phosphatases, which uniquely recognize their substrate as a monomeric enzyme. In the case of PPM1A, it has the capacity to dephosphorylate a variety of substrates containing different sequences, but it is not yet fully understood how it recognizes its substrates. Here we analyzed the role of Arg33 and Arg186, two residues near the active site, on the dephosphorylation activity of PPM1A. The results showed that both Arg residues were critical for enzymatic activity and docking-model analysis revealed that Arg186 is positioned to interact with the substrate phosphate group. In addition, our results suggest that which Arg residue plays a more significant role in the catalysis depends directly on the substrate.

Effects of 1-year treatment with canagliflozin on body composition and total body water in patients with type 2 diabetes.

AIM: To characterize the long-term changes in body composition associated with sodium-glucose cotransporter-2 (SGLT2) inhibitors. MATERIALS AND METHODS: In this multicentre, single-arm, open-label study, 107 patients with type 2 diabetes were treated with canagliflozin 100 mg, as add-on therapy, for 12 months. Body composition was measured with a body composition analyser (T-SCAN PLUS) using the impedance method to prospectively analyse changes in body components, including percentage of body fat, body fat mass, total body water, muscle mass and mineral mass. Estimated plasma volume (PV) was calculated using the Kaplan formula. RESULTS: Body weight showed a significant decrease from 1 month to 12 months of treatment with canagliflozin, with a higher rate of decrease in body fat in body composition. A significant decrease in mineral mass was also observed, but its rate was low. Following treatment with canagliflozin, changes in total body water did not affect intracellular water, and a significant decrease in extracellular water, including plasma components, was observed early and was sustained up to 12 months. Protein mass, a component of muscle mass, was not affected, with only a slight decrease in water volume observed. CONCLUSIONS: Canagliflozin decreased extracellular fluid and PV in addition to decreasing fat in the body via calorie loss resulting from urinary glucose excretion. This study suggested that SGLT2 inhibitors might reduce body weight by regulating fat mass or water distribution in the body and might have cardiac and renal protective effects by resetting the homeostasis of fluid balance.

Long-term Outcomes of Living-donor Liver Transplantation for Progressive Familial Intrahepatic Cholestasis Type 1.

OBJECTIVES: Progressive familial intrahepatic cholestasis type 1 (PFIC-1), an autosomal recessive disorder, is characterized by cholestasis, jaundice, and refractory pruritus. In some patients with PFIC-1, liver cirrhosis and end-stage liver disease develop and lead to liver transplantation (LT). In this observational study, we sought to clarify the long-term outcomes of LT for PFIC-1 and predictors of favorable outcomes. METHODS: The study cohort constituted 12 patients with PFIC-1 who had undergone living donor liver transplantation (LDLT) during the previous 3 decades (1990-2019). We compared the clinical manifestations and type of ATP8B1 mutations between patients in whom LDLT had been successful and those in whom it had been unsuccessful. RESULTS: LDLT failed in 5 of the 12 patients and the 25-year survival rate was 58%. Comparison of physical growth after LDLT revealed significant retardation of stature in patients in whom LDLT had been unsuccessful; these patients developed severe and persistent diarrhea. ATP8B1 genotypic analysis revealed that frameshifting, splicing, and large deletion mutations occurred more commonly in successful cases, whereas missense mutations occurred more frequently in unsuccessful cases. No mutations were identical in the 2 groups. CONCLUSIONS: These results suggest an association between post-LT outcomes and extrahepatic manifestations, especially intestinal function. Further investigation of correlations between ATP8B1 genotypes and intestinal function could help to identify patients with PFIC-1 who will achieve favorable post-LT outcomes.

TCP4-dependent induction of CONSTANS transcription requires GIGANTEA in photoperiodic flowering in Arabidopsis.

Photoperiod is one of the most reliable environmental cues for plants to regulate flowering timing. In Arabidopsis thaliana, CONSTANS (CO) transcription factor plays a central role in regulating photoperiodic flowering. In contrast to posttranslational regulation of CO protein, still little was known about CO transcriptional regulation. Here we show that the CINCINNATA (CIN) clade of class II TEOSINTE BRANCHED 1/ CYCLOIDEA/ PROLIFERATING CELL NUCLEAR ANTIGEN FACTOR (TCP) proteins act as CO activators. Our yeast one-hybrid analysis revealed that class II CIN-TCPs, including TCP4, bind to the CO promoter. TCP4 induces CO expression around dusk by directly associating with the CO promoter in vivo. In addition, TCP4 binds to another flowering regulator, GIGANTEA (GI), in the nucleus, and induces CO expression in a GI-dependent manner. The physical association of TCP4 with the CO promoter was reduced in the gi mutant, suggesting that GI may enhance the DNA-binding ability of TCP4. Our tandem affinity purification coupled with mass spectrometry (TAP-MS) analysis identified all class II CIN-TCPs as the components of the in vivo TCP4 complex, and the gi mutant did not alter the composition of the TCP4 complex. Taken together, our results demonstrate a novel function of CIN-TCPs as photoperiodic flowering regulators, which may contribute to coordinating plant development with flowering regulation.

Effect of change saliency and neural entrainment on flicker-induced time dilation.

When a visual stimulus flickers periodically and rhythmically, the perceived duration tends to exceed its physical duration in the peri-second range. Although flicker-induced time dilation is a robust time illusion, its underlying neural mechanisms remain inconclusive. The neural entrainment account proposes that neural entrainment of the exogenous visual stimulus, marked by steady-state visual evoked potentials (SSVEPs) over the visual cortex, is the cause of time dilation. By contrast, the saliency account argues that the conscious perception of flicker changes is indispensable. In the current study, we examined these two accounts separately. The first two experiments manipulated the level of saliency around the critical fusion threshold (CFF) in a duration discrimination task to probe the effect of change saliency. The amount of dilation correlated with the level of change saliency. The next two experiments investigated whether neural entrainment alone could also induce perceived dilation. To preclude change saliency, we utilized a combination of two high-frequency flickers above the CFF, whereas their beat frequency still theoretically aroused neural entrainment at a low frequency. Results revealed a moderate time dilation induced by combinative high-frequency flickers. Although behavioral results suggested neural entrainment engagement, electroencephalography showed neither larger power nor inter-trial coherence (ITC) at the beat. In summary, change saliency was the most critical factor determining the perception and strength of time dilation, whereas neural entrainment had a moderate influence. These results highlight the influence of higher-level visual processing on time perception.

New tailored approach using a revised assessment of fragmented potentials for persistent atrial fibrillation: Early area defragmentation by modified CFAE module.

INTRODUCTION: Pulmonary vein isolation (PVI) is widely performed for atrial fibrillation (AFib). However, it is insufficient to maintain sinus rhythm (SR) in persistent and long persistent atrial fibrillation (Per-AFib). Ablation of complex fractionated atrial electrograms (CFAEs) is currently classified as class IIb, However, the concept of length of potential was different between the current CFAE module of CARTO system and the definition of CFAE potential. The current CFAE module was configured in the shortest complex interval (SCI) mode, in which the meaning of length of potential was the interval of each component of fragmented potentials. That was a part of the potential. On the other hand, the meaning of the definition of CFAE potential was the length of fragmented potential itself. The purpose of this study was to essentially evaluate fragmented potentials by revisiting in interval confidence level (ICL) mode and express them on the map and prospectively investigate the efficacy and prognosis of a new tailored approach for defragmentation, which is called early area defragmentation (EADF). METHODS AND RESULTS: We acquired atrial potentials by modified CFAE module in ICL mode (K-CFAE potential) and visualized the distribution of K-CFAE potential (K-CFAE map). We performed PVI, and we ablated the fragmented areas based on the K-CFAE map. We enrolled 77 patients in this study (control group: 84 patients). After 24-month follow-up, 75.3% were able to maintain SR. CONCLUSIONS: K-CFAE mapping faithfully represented the distribution of fragmented areas. PVI, together with our new tailored approach, EADF, was successful in treating Per-AFib.

Effects of various types of anesthesia on hemodynamics, cardiac function, and glucose and lipid metabolism in rats.

Anesthesia can affect respiratory, circulatory, and endocrine systems but is necessary for certain experimental procedures such as echocardiography and blood sampling in small animals. We have now investigated the effects of four types of anesthesia [pentobarbital sodium (PENT), ketamine-xylazine (K/X), and low- or high-dose isoflurane (ISO)] on hemodynamics, cardiac function, and glucose and lipid metabolism in Sprague-Dawley rats. Aortic pressure, heart rate, and echocardiographic parameters were measured at various time points up to 45 min after the induction of anesthesia, and blood was then collected for measurement of parameters of glucose and lipid metabolism. Systolic aortic pressure remained constant in the PENT group, whereas it showed a biphasic pattern in the K/X group and a gradual decline in the ISO groups. Marked bradycardia was observed in the K/X group. The serum glucose concentration was increased and the plasma insulin level was reduced in the K/X and ISO groups compared with the PENT group. The concentrations of free fatty acids and norepinephrine in plasma were increased in the K/X group. Despite the metabolic effects of K/X and ISO, our results suggest that the marked bradycardic effect of K-X renders this combination appropriate for measurement of Doppler-derived indexes of left ventricular diastolic function, whereas the relative ease with which the depth of anesthesia can be controlled with ISO makes it suitable for manipulations or data collection over long time periods. On the other hand, PENT may be best suited for experiments that focus on measurement of cardiac function by M-mode echocardiography and metabolic parameters.

Cool night-time temperatures induce the expression of CONSTANS and FLOWERING LOCUS T to regulate flowering in Arabidopsis.

Day length and ambient temperature are major stimuli controlling flowering time. To understand flowering mechanisms in more natural conditions, we explored the effect of daily light and temperature changes on Arabidopsis thaliana. Seedlings were exposed to different day/night temperature and day-length treatments to assess expression changes in flowering genes. Cooler temperature treatments increased CONSTANS (CO) transcript levels at night. Night-time CO induction was diminished in flowering bhlh (fbh)-quadruple mutants. FLOWERING LOCUS T (FT) transcript levels were reduced at dusk, but increased at the end of cooler nights. The dusk suppression, which was alleviated in short vegetative phase (svp) mutants, occurred particularly in younger seedlings, whereas the increase during the night continued over 2 wk. Cooler temperature treatments altered the levels of FLOWERING LOCUS M-ß (FLM-ß) and FLM-δ splice variants. FT levels correlated strongly with flowering time across treatments. Day/night temperature changes modulate photoperiodic flowering by changing FT accumulation patterns. Cooler night-time temperatures enhance FLOWERING BHLH (FBH)-dependent induction of CO and consequently increase CO protein. When plants are young, cooler temperatures suppress FT at dusk through SHORT VEGETATIVE PHASE (SVP) function, perhaps to suppress precocious flowering. Our results suggest day length and diurnal temperature changes combine to modulate FT and flowering time.

Beneficial effects of losartan for prevention of paroxysmal atrial fibrillation in patients with sick sinus syndrome: analysis with memory function of pacemaker.

Renin-angiotensin system (RAS) inhibitors may be useful in preventing the occurrence of paroxysmal atrial fibrillation (PAF). However, evaluation of such effect is difficult because many PAF episodes are asymptomatic and not all episodes are detected by intermittent electrocardiographic monitoring. A pacemaker has been developed with dedicated functions for AF detection and electrocardiogram storage. Accordingly, we examined the effect of losartan, an angiotensin receptor blocker on PAF occurrence using this new modality. We enrolled 70 consecutive patients who had undergone dual-chamber pacemaker implantation for sick sinus syndrome. Finally, 62 patients participated in the study. Thirty patients were randomized to the losartan group (mean 43 ± 12 mg/day) and 32 patients to the control group. They were followed up for 3 months. The frequency, the maximum duration and the total duration of PAF recorded by the stored electrocardiograms for the last 1 month during the observation period and study period were compared between the two groups. The change in the frequency of PAF from the observation period in the losartan and control groups was similar (-35 ± 25 vs. -67 ± 62 times; NS). However, the change in the maximum duration and the total duration of PAF was significantly shorter in the losartan group than in the control group (-493 ± 158 vs. -10 ± 69 min; p < 0.05, and -4007 ± 2334 vs. 1119 ± 714 min; p < 0.05, respectively). Losartan suppressed the maximum duration and the total duration of PAF in patients with sick sinus syndrome without hemodynamic changes. This is the first study to show the effect of a renin-angiotensin system inhibitor on the secondary prevention of PAF using the dedicated functions of a pacemaker for PAF detection and electrocardiogram storage.