Tag: abióticos concepto

The two homologous genes, NIA1 and NIA2, encode nitrate reductases in Arabidopsis, which govern the reduction of nitrate to nitrite. This step is the rate-limiting step of the nitrate assimilation and utilization. Therefore, the regulation of NIA1 and NIA2 is important for plant development and growth. Although they are similar in sequence and structure, their regulations are different. Genetic analysis uncovers that NIA1, rather than NIA2, plays a predominant role in adopting to ABA stress. Although both long-term stress conditions can cause an improvement in NIA1 levels, a decrease in NIA1 levels under short-term treatments seems to be necessary for plants to switch from the growth status into the adopting status. Interestingly, the downregulation of the NR is distinct under different stress conditions. Under ABA treatment, the NR proteins are degraded via a 26S-proteasome dependent manner, while the transcriptional regulation is the main manner to rapidly reduce the NIA1 levels under nitrogen deficiency and NaCl stress conditions. These results indicate that under stress conditions, the regulation of NIA1 is complex, and it plays a key role in regulating the balance between growth and adaptation.

Introduction: Left ventricular chamber size and functional assessment by transesophageal echocardiography can be difficult if visualization is poor in the mid-esophageal views. However, the accuracy of using the Simpson’s method in the transgastric 2-chamber (TG2C) as an alternative approach has not been assessed.

Methods: The Simpson’s method was performed by 2 independent reviewers using midesophageal 2-chamber (ME2C) and TG2C views. Echocardiographic images were retrieved retrospectively for 49 adult cardiac surgical patients.

Results: Two-way random effects intraclass correlation coefficients demonstrated no significant interobserver variability. Linear mixed effects models showed no significant differences in ME2C and TG2C measurements with regard to EDV (P=.4407), ESV (P=.5113), or EF (P=.0610).Compared to the ME2C view, the TG2C view had better image quality of the LV walls (image quality score median [interquartile range]: 2.00 [.00] vs 1.00 [1.00]; P<.0001), but worse image quality of the mitral annulus (1.00 [1.00] vs 2.00 [.00]; P<.0001) and LV apex (.00 [1.00] vs 2.00 [1.00]; P<.0001).

Conclusions: This study suggests the Simpson’s method can be applied to the TG2C view as an alternative to the standard midesophageal method to estimate chamber volumes and EF.

Keywords: Simpson’s method; intraoperative assessment; left ventricular ejection fraction; monitoring; research; transesophageal echocardiography.

Background: Signet ring cell carcinoma (SRCC) is a particular histologic variant of gastric cancer (GC). However, the critical factor related to the aggressive characteristics of SRCC has not been determined.

Methods: We collected surgically resected tissues from 360 GC patients in the Kumamoto University cohort and generated survival curves via the Kaplan-Meier method. In vitro, we identified the specific transcript variant of MUC20 in SRCC cells by direct sequencing and investigated the role of MUC20 in GC progression using GC cells with MUC20 silencing and forced expression. In vivo, we examined chemoresistance using MUC20 variant 2 (MUC20v2)-overexpressing non-SRCC cells to construct a xenograft mouse model.

Results: We analyzed a comprehensive GC cell line database to identify the specifically expressed genes in gastric SRCC. We focused on MUC20 and investigated its role in GC progression. Survival analysis revealed that GC patients with high MUC20 expression exhibited a poor prognosis and that MUC20 expression was significantly correlated with SRCC histological type. Moreover, we found that gastric SRCC cells specifically expressed MUC20v2, which was dominantly expressed in the cytoplasm. Silencing MUC20v2 caused cell death with characteristic morphological changes in gastric SRCC cells. To further determine the types of cell death, we examined apoptosis, pyroptosis and ferroptosis by detecting cleaved PARP, gasdermin E-N-terminal (GSDME-N), and lipid reactive oxygen species (ROS) levels, respectively. We found that apoptosis and pyroptosis occurred in MUC20-silenced gastric SRCC cells. In addition, MUC20v2-overexpressing GC cells exhibited chemoresistance to cisplatin (CDDP) and paclitaxel (PTX). RNA sequencing revealed that the pathways involved in intracellular calcium regulation were significantly upregulated in MUC20v2-overexpressing GC cells.

Notably, forced expression of MUC20v2 in the cytoplasm of GC cells led to the maintenance of mitochondrial calcium homeostasis and mitochondrial membrane potential (MMP), which promoted cell survival and chemoresistance by suppressing apoptosis and pyroptosis. Finally, we investigated the significance of MUC20v2 in a xenograft model treated with CDDP and showed that MUC20v2 overexpression caused chemoresistance by inhibiting cell death.

Conclusion: These findings highlight the novel functions of MUC20v2, which may confer cell survival and drug resistance in GC cells.

Significance: MUC20v2 protects GC cells from apoptosis and pyroptosis by maintaining mitochondrial calcium levels and mitochondrial membrane potential and subsequently induces drug resistance.

Keywords: Drug resistance; Intracellular mucin 20; Mitochondrial calcium homeostasis; Mitochondrial membrane potential; Signet ring cell carcinoma.

Real world data on cardiometabolic diseases in U.S. adults during the SARS-CoV-2 pandemic: a decentralized registry study