Pectin chemistry and cellulose crystallinity govern pavement cell morphogenesis in a multi-step mechanism

Author Posting. ©American Society of Plant Biologists, 2019. This article is posted here by permission of [publisher] for personal use, not for redistribution. The definitive version was published in Altartouri, B., Bidhendi, A. J., Tani, T., Suzuki, J., Conrad, C., Chebli, Y., Liu, N., Karunakaran, C., Scarcelli, G., & Geitmann, A. Pectin chemistry and cellulose crystallinity govern pavement cell morphogenesis in a multi-step mechanism. Plant Physiology, 181(1), (2019): 127-141, doi:10.1104/pp.19.00303.Simple plant cell morphologies, such as cylindrical shoot cells, are determined by the extensibility pattern of the primary cell wall, which is thought to be largely dominated by cellulose microfibrils, but the mechanism leading to more complex shapes, such as the interdigitated patterns in the epidermis of many eudicotyledon leaves, is much less well understood. Details about the manner in which cell wall polymers at the periclinal wall regulate the morphogenetic process in epidermal pavement cells and mechanistic information about the initial steps leading to the characteristic undulations in the cell borders are elusive. Here, we used genetics and recently developed cell mechanical and imaging methods to study the impact of the spatio-temporal dynamics of cellulose and homogalacturonan pectin distribution during lobe formation in the epidermal pavement cells of Arabidopsis (Arabidopsis thaliana) cotyledons. We show that nonuniform distribution of cellulose microfibrils and demethylated pectin coincides with spatial differences in cell wall stiffness but may intervene at different developmental stages. We also show that lobe period can be reduced when demethyl-esterification of pectins increases under conditions of reduced cellulose crystallinity. Our data suggest that lobe initiation involves a modulation of cell wall stiffness through local enrichment in demethylated pectin, whereas subsequent increase in lobe amplitude is mediated by the stress-induced deposition of aligned cellulose microfibrils. Our results reveal a key role of noncellulosic polymers in the biomechanical regulation of cell morphogenesis.Natural Sciences and Engineering Research Council of Canada Canada Research Chair Program Marine Biological Laboratory NIH R01GM100160 Canada Foundation for Innovation University of Saskatchewan Government of Saskatchewan Western Economic Diversification Canada National Research Council (Canada) Canadian Institutes of Health Researc

Spin State Differentiated [3Fe-4S] Cluster Electrocatalyzes Water Oxidation Efficiently.

Though there are many synthetic iron-sulfur clusters that have been reported to show catalytic activity mimicking the natural cofactors in metalloenzymes, the influence of the spin state on the catalytic property is seldom touched. Here, a disulfide-bridged triiron(II) complex is shown, namely [Fe3(Sip)4][CF3SO3]2 (Fe3(Sip)4, HSip = sulfanylpropyliminomethyl-pyridine), can efficiently electrocatalyze water oxidation with a turnover frequency of 932 s-1 and Faraday efficiency of 86%, better than many iron-based catalysts. More importantly, the terminal low-spin (S = 0) iron(II) sites possessing a N4S2 first coordination environment, along with the synergetic catalysis of ligands, play a crucial role in the catalytic process. This research highlights the unconventional applications of iron-sulfur clusters in electrocatalytic water oxidation and underlines a promising avenue for developing innovative catalysts

Optimizing treatment persistence in epilepsy: a comparative analysis of combined antiseizure medications with different mechanisms of action

Background: Combination therapy with antiseizure medications (ASMs) is a rational strategy if monotherapy cannot effectively control seizures, thereby aiming to improve tolerance and treatment persistence. Objectives: To compare the efficacy of different ASM combinations among patients. Design: Patients with epilepsy on monotherapy who had a second ASM added as concomitant two-drug therapy from January 2009 to May 2019 in the Chang Gung Research Database, Taiwan, were included in the analysis. Methods: ASM combinations were compared based on their primary mechanism of action (MoA) which are as follows: gamma-aminobutyric acid receptor (G), sodium channel blocker (SC), synaptic vesicle protein 2A (SV2), calcium channel blocker (C), and multiple mechanisms (M). Treatment persistence was compared, and the predictors of persistence were analyzed. Results: In total, 3033 patients were enrolled in this study. Combined ASMs with different MoAs had significantly longer treatment persistence than ASMs with similar MoAs, specifically SC and M combinations. Patients receiving combined ASMs with different MoAs were less likely to discontinue treatment [adjusted hazards ratio: 0.83 (95% CI: 0.75–0.93), p  < 0.001]. Among all combinations, the SC + SV2 combination had the longest treatment persistence (mean ± SD: 912.7 ± 841.6 days). Meanwhile, patients receiving the G combination had a higher risk of treatment discontinuation than those receiving the SC + SV2 combination. Underlying malignancies were associated with an increased risk of treatment discontinuation across all MoA categories. Male patients receiving the SC, SV2, and M combinations were more likely to discontinue treatment than female patients. Moreover, patients with renal disease were more likely to discontinue treatment with the SV2 combinations. Conclusion: ASM combinations with different MoAs had superior efficacy and tolerability to ASM combinations with similar MoAs, particularly SC and M combinations. In our cohort, factors associated with treatment discontinuation included underlying malignancy, male sex, and renal disease. These findings may provide valuable insights into the use of ASM combinations if monotherapy cannot adequately control seizures

sj-docx-1-tan-10.1177_17562864231207161 – Supplemental material for Optimizing treatment persistence in epilepsy: a comparative analysis of combined antiseizure medications with different mechanisms of action

Supplemental material, sj-docx-1-tan-10.1177_17562864231207161 for Optimizing treatment persistence in epilepsy: a comparative analysis of combined antiseizure medications with different mechanisms of action by Chun-Wei Chang, Wei-En Johnny Tseng, Wey-Ran Lin, Po-Chuan Ko, Chun-Jing Liu and Siew-Na Lim in Therapeutic Advances in Neurological Disorders</p

Preliminary Asian experience of using perampanel in clinical practice

Background: To analyze the efficacy and safety of perampanel over a 3-month period in a sample of Asian people with epilepsy. Methods: The efficacy and safety of perampanel as an adjunctive therapy for patients with epilepsy were retrospectively reviewed and analyzed. Patients were categorized according to seizure type, concomitant antiepileptic drug usage, and perampanel dosage. Results: A total of 210 patients were included in the study and 131 patients completed 3 months of perampanel treatment. The average dosage of perampanel was 5.31 mg/day, and the 50% responder rate (≥50% seizure frequency reduction) in all patients was 45.8%, with a 27.5% seizure-free rate. For focal seizures, focal to bilateral tonic-clonic seizures, and primary generalized seizures, the 50% responder rates were respectively 29.4%, 49.5%, and 36.4%. In total, 39.5% of patients experienced adverse events within 3 months of observation period, and the rate of drug withdrawal due to adverse events was 8.6%. Dizziness, ataxia, irritability/aggression were the most common adverse events. Conclusions: The efficacy and safety of perampanel in a real-world setting with Asian patients is comparable to that in clinical trials that have included fewer Asian patients

Reduced Sleep Quality Is Related to Poor Quality of Life in Patients with Juvenile Myoclonic Epilepsy, a Case-Control Study

Juvenile myoclonic epilepsy (JME) is a primary generalized epilepsy which is closely related to the sleep-wake cycle. This study aimed to investigate whether sleep disturbance is more common among patients with JME and the impact this may have on their quality of life (QOL). Thirty-four patients with JME and age- and gender-matched controls were recruited into this case control study, and assessed using validated sleep questionnaires including the Epworth Sleepiness Scale (ESS), Pittsburgh Sleep Quality Index (PSQI), and Stanford Sleepiness Scale (SSS). QOL was assessed using the Quality of Life in Epilepsy Inventory (QOLIE-31). The patients had a significantly higher PSQI score and higher proportion of abnormal PSQI scores than the controls. They also had higher ESS and SSS scores, but without statistical significance. The patients with poor sleep quality had significantly lower overall QOL, emotional well-being, and energy/fatigue subscale scores. The use of a higher number of antiseizure medications, dosage of levetiracetam, and usage of antiseizure medication polytherapy were associated with sleep disorders. Our results showed that sleep disturbance is common in patients with JME, and also that it has an impact on their QOL.</jats:p