Intrathecal Anesthesia Prevents Ventricular Arrhythmias in Rats with Myocardial Ischemia/Reperfusion.

INTRODUCTION: Ventricular arrhythmia is commonly provoked by acute cardiac ischemia through sympathetic exaggeration and is often resistant to anti-arrhythmic therapies. Thoracic epidural anesthesia has been reported to terminate fatal ventricular arrhythmia; however, its underlying mechanism is unknown. METHODS: Rats were randomly divided into four groups: sham, sham plus bupivacaine, ischemia/reperfusion (IR), and IR plus bupivacaine groups. Bupivacaine (1 mg/mL, 0.05 mL/100 g body weight) was injected intrathecally into the L5-L6 intervertebral space prior to establishing a myocardial IR rat model. Thereafter, cardiac arrhythmia, cardiac function, myocardial injury, and electrical activities of the heart and spinal cord were evaluated. RESULTS: Intrathecal bupivacaine inhibited spinal neural activity, improved heart rate variability, reduced ventricular arrhythmia score, and ameliorated cardiac dysfunction in IR rats. Furthermore, intrathecal bupivacaine attenuated cardiac injury and myocardial apoptosis and regulated cardiomyocyte autophagy and connexin-43 distribution during myocardial IR. CONCLUSION: Our results indicate that intrathecal bupivacaine blunts spinal neural activity to prevent cardiac arrhythmia and dysfunction induced by IR and that this anti-arrhythmic activity may be associated with regulation of autonomic balance, myocardial apoptosis and autophagy, and cardiac gap junction function.

Morphology Dictated Immune Activation with Framework Nucleic Acids.

Framework nucleic acids (FNAs) of various morphologies, designed using the precise and programmable Watson-Crick base pairing, serve as carriers for biomolecule delivery in biology and biomedicine. However, the impact of their shape, size, concentration, and the spatial presentation of cytosine-phosphate-guanine oligodeoxynucleotides (CpG ODNs) on immune activation remains incompletely understood. In this study, representative FNAs with varying morphologies are synthesized to explore their immunological responses. Low concentrations (50 nM) of all FNAs elicited no immunostimulation, while high concentrations of elongated DNA nanostrings and tetrahedrons triggered strong activation due to their larger size and increased cellular uptake, indicating that the innate immune responses of FNAs depend on both dose and morphology. Notably, CpG ODNs' immune response can be programmed by FNAs through regulating the spatial distance, with optimal spacing of 7-8 nm eliciting the highest immunostimulation. These findings demonstrate FNAs' potential as a designable tool to study nucleic acid morphology's impact on biological responses and provide a strategy for future CpG-mediated immune activation carrier design.

Imaging tools for plant nanobiotechnology.

The successful application of nanobiotechnology in biomedicine has greatly changed the traditional way of diagnosis and treating of disease, and is promising for revolutionizing the traditional plant nanobiotechnology. Over the past few years, nanobiotechnology has increasingly expanded into plant research area. Nanomaterials can be designed as vectors for targeted delivery and controlled release of fertilizers, pesticides, herbicides, nucleotides, proteins, etc. Interestingly, nanomaterials with unique physical and chemical properties can directly affect plant growth and development; improve plant resistance to disease and stress; design as sensors in plant biology; and even be used for plant genetic engineering. Similarly, there have been concerns about the potential biological toxicity of nanomaterials. Selecting appropriate characterization methods will help understand how nanomaterials interact with plants and promote advances in plant nanobiotechnology. However, there are relatively few reviews of tools for characterizing nanomaterials in plant nanobiotechnology. In this review, we present relevant imaging tools that have been used in plant nanobiotechnology to monitor nanomaterial migration, interaction with and internalization into plants at three-dimensional lengths. Including: 1) Migration of nanomaterial into plant organs 2) Penetration of nanomaterial into plant tissues (iii)Internalization of nanomaterials by plant cells and interactions with plant subcellular structures. We compare the advantages and disadvantages of current characterization tools and propose future optimal characterization methods for plant nanobiotechnology.

Optical Activation of the Dorsal Horn of the Thoracic Spinal Cord Prevents Ventricular Arrhythmias in Acute Myocardial Ischemia-Reperfusion Rats.

BACKGROUND AND OBJECTIVES: Spinal cord stimulation can prevent myocardial ischemia and reperfusion arrhythmias, but the relevant neurons and mechanisms remain unknown. Thus, this study applied optogenetic techniques to selectively activate glutamatergic neurons at the thoracic spinal cord (T1 segment) for examining the anti-arrhythmia effects during acute myocardial ischemic-reperfusion. METHODS: Adeno-associated viruses (AAVs) carrying channelrhodopsin-2 (ChR2, a blue-light sensitive ion channel) CaMKIIα-hChR2(H134R) or empty vector were injected into the dorsal horn of the T1 spinal cord. Four weeks later, optogenetic stimulation with a 473-nm blue laser was applied for 30 min. Then, the myocardial ischemia-reperfusion model was created by occlusion of the anterior descending coronary artery for ischemia (15 min) and reperfusion (30 min). Cardiac electrical activity and sympathetic nerve activity were assessed continuously. RESULTS: CaMKIIα-hChR2 viral transfection is primarily expressed in glutamatergic neurons in the spinal cord. Selective optical stimulation of the T1 dorsal horn in the ChR2 rat reduced the ventricular arrhythmia and arrhythmia score during myocardial ischemia-reperfusion, preventing the over-activation of cardiac sympathetic nerve activity. Additionally, optical stimulation also reduced the action potential duration at the 90% level (APD90) and APD dispersion. CONCLUSION: Selective optical stimulation T1 glutamatergic neurons of dorsal horn prevent ischemia-reperfusion arrhythmias. The mechanism may be associated with inhibiting sympathetic nervous system overexcitation and increasing APD dispersion during myocardial ischemia-reperfusion.

Effects of polystyrene nanoplastics (PSNPs) on the physiology and molecular metabolism of corn (Zea mays L.) seedlings.

The effects of polystyrene nanoplastics (PSNPs) on the physiological and molecular metabolism of corn seedlings were examined by treating corn (Zea mays L.) seedlings with 100, 300, and 500 nm diameter PSNPs and examining plant photosynthetic characteristics, antioxidant enzyme systems, and molecular metabolism. After 15 days of exposure to PSNPs with different particle sizes (50 mg·L-1), the photosynthetic characteristics of the plant remained stable, and the maximum photochemical quantum yield (Fv/Fm) and non-photochemical quenching coefficient (NPQ) had no significant effects. The root microstructure was damaged and the antioxidant enzyme system was activated, and the content of malondialdehyde (MDA) was significantly increased by 2.25-4.50-fold. In addition, 100 nm and 300 nm PSNPs exposure caused root superoxide dismutase (SOD) activity to increase 1.28-fold and 1.53-fold, and glutathione-peroxidase (GSH-PX) activity increased 1.30-fold and 1.58-fold. Non-targeted metabolomics analysis identified a total of 304 metabolites. Exposure to 100, 300, and 500 nm PSNPs led to the production of 85 (upregulated: 85, downregulated: 0), 73 (upregulated: 73, downregulated: 0), and 86 (upregulated: 84, downregulated: 2) differentially expressed metabolites, respectively, in the plant roots. Co-expressed differential metabolites accounted for 38.2% of the metabolites and indicated a metabolic imbalance primarily in organic acids and derivatives in the root system. The most significant enrichment pathways were those of alanine, aspartate, and glutamate metabolism. Overall, exposure to PSNPs of different particle sizes activated the root antioxidant enzyme system and interfered with plant basic metabolism. The alanine, aspartate, and glutamate metabolic pathways appear to be closely related to plant mechanisms for tolerance/detoxification of PSNPs.

Alterations of the rhizosphere soil microbial community composition and metabolite profiles of Zea mays by polyethylene-particles of different molecular weights.

Polyethylene film is the most widely used plastic film in agricultural production activities, and its depolymerization products are mainly polyethylene-particles (PE-particles) of different molecular weights. However, the impact of the molecular weights of the PE-particles on soil-crop microenvironment has not been elucidated. In this study, a potted microcosmic simulation system was used to evaluate the impact of low, medium and high molecular weight PE-particles on soil metabolism, microbial community structure, and crop growth. There were obvious differences in the shape and surface microstructure of PE-particles with different molecular weights. Soil sucrase and peroxidase had significant responses to PE-particles of different molecular weights. In the rhizosphere, the number of microorganisms and the microbial alpha diversity index increased with increasing PE-particles molecular weight. Rhizobacter, Nitrospira, and Sphingomonas were the dominant microorganisms induced by PE-particles to regulate the metabolism of elements. Carbohydrate and amino acid contents in rhizosphere soils were the key factors affecting the species abundance of Lysobacter, Polyclovorans, Rhizobacter, and Sphingomonas. In plants, PE-particles treatment reduced the plant biomass and photosynthetic rate and disrupted normal mineral nutrient metabolism. Different molecular weight PE-particles may therefore have adverse effects on the soil-plant system.