The Roles of Phosphorylation and SHAGGY-Like Protein Kinases in Geminivirus C4 Protein Induced Hyperplasia

Even though plant cells are highly plastic, plants only develop hyperplasia under very specific abiotic and biotic stresses, such as when exposed to pathogens like Beet curly top virus (BCTV). The C4 protein of BCTV is sufficient to induce hyperplasia and alter Arabidopsis development. It was previously shown that C4 interacts with two Arabidopsis Shaggy-like protein kinases, AtSK21 and 23, which are negative regulators of brassinosteroid (BR) hormone signaling. Here we show that the C4 protein interacts with five additional AtSK family members. Bikinin, a competitive inhibitor of the seven AtSK family members that interact with C4, induced hyperplasia similar to that induced by the C4 protein. The Ser49 residue of C4 was found to be critical for C4 function, since: 1) mutagenesis of Ser49 to Ala abolished the C4-induced phenotype, abolished C4/AtSK interactions, and resulted in a mutant protein that failed to induce changes in the BR signaling pathway; 2) Ser49 is phosphorylated in planta; and 3) plant-encoded AtSKs must be catalytically active to interact with C4. A C4 N-myristoylation site mutant that does not localize to the plasma membrane and does not induce a phenotype, retained the ability to bind AtSKs. Taken together, these results suggest that plasma membrane associated C4 interacts with and co-opts multiple AtSKs to promote its own phosphorylation and activation to subsequently compromise cell cycle control.     

Explore the Functional Connectivity between Brain Regions during a Chemistry Working Memory Task

Previous studies have rarely examined how temporal dynamic patterns, event-related coherence, and phase-locking are related to each other. This study assessed reaction-time-sorted spectral perturbation and event-related spectral perturbation in order to examine the temporal dynamic patterns in the frontal midline (F), central parietal (CP), and occipital (O) regions during a chemistry working memory task at theta, alpha, and beta frequencies. Furthermore, the functional connectivity between F-CP, CP-O, and F-O were assessed by component event-related coherence (ERCoh) and component phase-locking (PL) at different frequency bands. In addition, this study examined whether the temporal dynamic patterns are consistent with the functional connectivity patterns across different frequencies and time courses. Component ERCoh/PL measured the interactions between different independent components decomposed from the scalp EEG, mixtures of time courses of activities arising from different brain, and artifactual sources. The results indicate that the O and CP regions’ temporal dynamic patterns are similar to each other. Furthermore, pronounced component ERCoh/PL patterns were found to exist between the O and CP regions across each stimulus and probe presentation, in both theta and alpha frequencies. The consistent theta component ERCoh/PL between the F and O regions was found at the first stimulus and after probe presentation. These findings demonstrate that temporal dynamic patterns at different regions are in accordance with the functional connectivity patterns. Such coordinated and robust EEG temporal dynamics and component ERCoh/PL patterns suggest that these brain regions’ neurons work together both to induce similar event-related spectral perturbation and to synchronize or desynchronize simultaneously in order to swiftly accomplish a particular goal. The possible mechanisms for such distinct component phase-locking and coherence patterns were also further discussed.     

Feasibility and Clinical Outcomes of Peripheral Drug-Coated Balloon in High-Risk Patients with Femoropopliteal Disease

Background

Clinical outcomes of the drug-coated balloon (DCB) procedure in high-risk patients with femoropopliteal (FP) disease have not been investigated sufficiently.

Methods

This retrospective, single-center study analyzed 87 patients (39% dialysis) and 97 affected legs (64% critical limb ischemia [CLI]) that underwent DCB for symptomatic FP disease from March 2013 to September 2014. Risk stratification was based on FeDCLIP (female, diabetes, dialysis, CLI, lesion length >150 mm and poor runoff) score. The DCB outcomes among the different risk groups were compared and factors predicting restenosis were analyzed during follow-up.

Results

Most of study participants (84%) were moderate to high-risk patients. The procedural success rate was 100% and the 30-day major adverse vascular event rate was 2.1%. The mean lesion length was 178 ± 106 mm and the mean follow-up time was 428 ± 145 (range 50–782) days. The binary restenosis-free and clinically driven target lesion revascularization (CD-TLR)-free rates at 12 months were 77.5% and 84.3%, respectively, for all participants. No significant differences were observed in 1-year binary restenosis and CD-TLR rates in the low-, moderate-, and high-risk groups (60%, 84%, and 73%: p = 0.396; 78%, 89%, and 80%: p = 0.635, respectively). In multivariate analysis, lesion length >150 mm (Hazard ratio [HR]: 8.00, 95% confidence interval (CI) 1.12 to 55.6, p = 0.038) and Rutherford class 6 (HR: 7.09, 95% CI, 1.15 to 43.5, p = 0.034) were identified as independent predictors of binary restenosis.

Conclusions

Despite general comorbidities and advanced limb ischemia, 1-year outcomes of DCB in high-risk patients with FP disease were effective. The DCB procedure holds promise to improve vessel patency; however, lesion length >150 mm and major tissue loss were independent predictors for binary restenosis after the treatment.     

Rheumatoid Arthritis Risk Associated with Periodontitis Exposure: A Nationwide,Population-Based Cohort Study

Background

The risk of periodontitis (PD) is increased in the patient group of rheumatoid arthritis (RA). RA and PD also shared some pathological mechanism. The aim of this study is to investigate the risk of RA associated with PD exposure.

Methods and Findings

This study identified 3 mutually exclusive cohorts using the 1999–2010 Taiwanese National Health Insurance Research Database (NHIRD) to investigate the association between PD and the risk of incident RA. All patients with PD in 2000 were identified from the database of all enrollees as the PD cohort. From the representative database of 1,000,000 enrollees randomly selected in 2010 (LHID2010), individuals without any periodontal disease (PO) during 1999–2010 were selected as the non-PO cohort. Individuals who were not included in the non-PO cohort and received dental scaling (DS) no more than two times per year during 1999–2010 were selected as the DS cohort from LHID2010. Using cox proportional regression analysis, hazard ratios (HRs) with 95% confidence intervals (Cis) were calculated to quantify the association between PD exposure and RA development. In the three-group comparison using the non-PO cohort as reference, we found that the risk of RA was higher in the PD and DS cohorts (HRs, 1.89 and 1.43; 95% CIs, 1.56–2.29 and 1.09–1.87, respectively). For comparisons between two cohorts, the PD cohort had a higher risk of RA than the non-PO and DS cohorts (HRs, 1.91 and 1.35; 95% CIs, 1.57–2.30 and 1.09–1.67, respectively).

Conclusion

PD was associated with an increased risk of RA development.     

Removal of Transmissible Spongiform Encephalopathy Prion from Large Volumes of Cell Culture Media Supplemented with Fetal Bovine Serum by Using Hollow Fiber Anion-Exchange Membrane Chromatography

Cases of variant Creutzfeldt-Jakob disease in people who had consumed contaminated meat products from cattle with bovine spongiform encephalopathy emphasize the need for measures aimed at preventing the transmission of the pathogenic prion protein (PrP^Sc) from materials derived from cattle. Highly stringent scrutiny is required for fetal bovine serum (FBS), a growth-medium supplement used in the production of parenteral vaccines and therapeutic recombinant proteins and in the ex vivo expansion of stem cells for transplantation. One such approach is the implementation of manufacturing steps dedicated to removing PrP^Sc from materials containing FBS. We evaluated the use of the QyuSpeed D (QSD) adsorbent hollow-fiber anion-exchange chromatographic column (Asahi Kasei Medical, Tokyo, Japan) for the removal of PrP^Sc from cell culture media supplemented with FBS. We first established that QSD filtration had no adverse effect on the chemical composition of various types of culture media supplemented with 10% FBS or the growth and viability characteristics of human embryonic kidney (HEK293) cells, baby hamster kidney (BHK-21) cells, African green monkey kidney (Vero) cells, and Chinese hamster ovary (CHO-k1) cells propagated in the various culture-medium filtrates. We used a 0.6-mL QSD column for removing PrP^Sc from up to 1000 mL of Dulbecco’s modified Eagle’s medium containing 10% FBS previously spiked with the 263K strain of hamster-adapted scrapie. The Western blot analysis, validated alongside an infectivity assay, revealed that the level of PrP^Sc in the initial 200mL flow-through was reduced by 2.5 to > 3 log₁₀, compared with that of the starting material. These results indicate that QSD filtration removes PrP^Sc from cell culture media containing 10% FBS, and demonstrate the ease with which QSD filtration can be implemented in at industrial-scale to improve the safety of vaccines, therapeutic recombinant proteins, and ex vivo expanded stem cells produced using growth media supplemented with FBS.     

Role of Sarcoplasmic Reticulum Calcium in Development of Secondary Calcium Rise and Early Afterdepolarizations in Long QT Syndrome Rabbit Model

Background

L-type calcium current reactivation plays an important role in development of early afterdepolarizations (EADs) and torsades de pointes (TdP). Secondary intracellular calcium (Ca_i) rise is associated with initiation of EADs.

Objective

To test whether inhibition of sarcoplasmic reticulum (SR) Ca²⁺ cycling suppresses secondary Ca_i rise and genesis of EADs.

Methods

Langendorff perfusion and dual voltage and Ca_i optical mapping were conducted in 10 rabbit hearts. Atrioventricular block (AVB) was created by radiofrequency ablation. After baseline studies, E4031, SR Ca²⁺ cycling inhibitors (ryanodine plus thapsigargin) and nifedipine were then administrated subsequently, and the protocols were repeated.

Results

At baseline, there was no spontaneous or pacing-induced TdP. After E4031 administration, action potential duration (APD) was significantly prolonged and the amplitude of secondary Ca_i rise was enhanced, and 7 (70%) rabbits developed spontaneous or pacing-induced TdP. In the presence of ryanodine plus thapsigargin, TdP inducibility was significantly reduced (2 hearts, 20%, p = 0.03). Although APD was significantly prolonged (from 298 ± 30 ms to 457 ± 75 ms at pacing cycle length of 1000 m, p = 0.007) by ryanodine plus thapsigargin, the secondary Ca_i rise was suppressed (from 8.8 ± 2.6% to 1.2 ± 0.9%, p = 0.02). Nifedipine inhibited TdP inducibility in all rabbit hearts.

Conclusion

In this AVB and long QT rabbit model, inhibition of SR Ca²⁺ cycyling reduces the inducibility of TdP. The mechanism might be suppression of secondary Ca_i rise and genesis of EADs.     

Thyroid Fine-Needle Aspiration Biopsy and Thyroid Cancer Diagnosis: A Nationwide Population-Based Study

Background

Thyroid cancer is the most common endocrine gland malignancy and fine-needle aspiration biopsy is widely used for thyroid nodule evaluation. Repeated aspiration biopsies are needed due to plausible false-negative results. This study aimed to investigate the overall relationship between aspiration biopsy and thyroid cancer diagnosis, and to explore factors related to shorter diagnostic time.

Methods

This nationwide retrospective cohort study retrieved data from the Longitudinal Health Insurance Database in Taiwan. Subjects without known thyroid malignancies and who received the first thyroid aspiration biopsy after 2004 were followed-up from 2004 to 2009 (n = 7700). Chi-square test, Kaplan-Meier survival analysis, and Cox proportional hazards model were used for data analysis.

Results

Of 7700 newly-aspirated patients, 276 eventually developed thyroid cancer (malignancy rate 3.6%). Among the 276 patients with thyroid cancer, 61.6% underwent only one aspiration biopsy and 81.2% were found within the first year after the initial aspiration. Cox proportional hazards model revealed that aspiration frequency (HR 1.07, 95% CI 1.06–1.08), ultrasound frequency (HR 1.02, 95% CI 1.01–1.03), older age, male sex, and aspiration biopsies arranged by surgery, endocrinology or otolaryngology subspecialties were all associated with shorter time to thyroid cancer diagnosis.

Conclusions

About 17.4% of thyroid cancer cases received more than two aspiration biopsies and 18.8% were diagnosed one year after the first biopsy. Regular follow-up with repeated aspiration or ultrasound may be required for patients with clinically significant thyroid nodules.     

Identification of lipocalin-2 as a PKCδ phosphorylation substrate in neutrophils

Background

PKCδ expressed in neutrophils is implicated in promoting reperfusion injury after ischemic stroke. To understand the molecular and cellular actions of PKCδ, we employed a chemical-genetics approach to identify PKCδ substrates in neutrophils.

Results

We recently generated knock-in mice endogenously expressing analog-specific PKCδ (AS-PKCδ) that can utilize ATP analogs as phosphate donors. Using neutrophils isolated from the knock-in mice, we identified several PKCδ substrates, one of which was lipocalin-2 (LCN2), which is an iron-binding protein that can trigger apoptosis by reducing intracellular iron concentrations. We found that PKCδ phosphorylated LCN2 at T115 and this phosphorylation was reduced in Prkcd^−/− mice. PKCδ colocalized with LCN2 in resting and stimulated neutrophils. LCN2 release from neutrophils after cerebral ischemia was reduced in PKCδ null mice.

Conclusions

These findings suggest that PKCδ phosphorylates LCN2 and mediates its release from neutrophils during ischemia-reperfusion injury.