Jove-Journal of Visualized Experiments最新文献

The rise of renewable energy sources has underscored the significance of microgrids, particularly DC variants, which are well-suited for integrating photovoltaic panels, battery storage systems, and other DC load solutions. This paper presents the development and experimentation of a DC microgrid with hierarchical control implemented in OPAL RT-Lab, a simulator. The microgrid includes distributed energy resources (DERs) interconnected via power converters, a DC bus, and DC loads. The primary control employs a droop control mechanism and double-loop Proportional-Integral (PI) control to regulate voltage and current, ensuring stable operation and proportional power sharing. The secondary control utilizes a consensus-based strategy to coordinate DERs to restore the bus voltage and ensure accurate power sharing, enhancing system reliability and efficiency. The experimental setup detailed in this paper includes circuit modeling, hardware implementation, and control strategies. The hardware platform's circuitry and controller parameters are specified, and the results can be observed through oscilloscope measurements. Two sets of experiments demonstrating the secondary control response with and without delay are conducted to validate the effectiveness of the control strategy. The outcomes confirm the successful implementation of hierarchical control in the microgrid. This study underscores the significance of a comprehensive experimental platform for advancing microgrid technology, providing valuable insights for future research and development.

Atherosclerosis, a leading cause of cardiovascular diseases, necessitates a detailed examination of lesion development and progression. This study introduces a comprehensive protocol for the isolation and histological analysis of aortic arch and root lesions in a widely used atherosclerotic mouse model, low-density lipoprotein receptor knock-out (Ldlr^-/-) mice. The aortic arch and root are key sites for atherosclerotic lesions, and their examination is critical for assessing the onset, progression, or regression of atherosclerosis, predicting cardiovascular event risks, and identifying potential therapeutic targets. This protocol outlines methods for quantifying atherosclerotic burden in the aortic arch and root, including tissue isolation, fixation, Oil Red O staining, aortic root sectioning, Hematoxylin and Eosin (HE) staining, Verhoeff-Van Gieson (VVG) staining, and image analysis. Oil Red O staining measures plaque area in the aortic arch, evaluating the severity of atherosclerosis, while HE staining of the aortic root reveals plaque components such as the lipid core and fibrous cap, facilitating the assessment of plaque stability and rupture risk. VVG staining can stain collagen fibers within tissues, providing further insights into plaque composition and related information. This thorough analysis offers valuable insights into the mechanisms of lesion development and may guide the creation of novel therapeutic strategies for preventing and treating atherosclerosis.

Extracellular vesicles (EVs) are lipid bilayer-enclosed nanoparticles released by cells to transport bioactive cargo, such as proteins, RNAs, and DNAs, for intercellular communication. Investigating EV-mediated crosstalk among cells in muscle homeostasis and diseases offers significant potential to enhance our understanding of muscle development, regeneration, and atrophy. However, current protocols for isolating skeletal muscle-derived EVs (SkM-EVs) face challenges in achieving high purity and yield, primarily due to difficulties in releasing EVs from muscle tissues without compromising cellular membranes. This article presents an efficient protocol for SkM-EV isolation, comprising mechanical detachment, enzymatic dissociation, filtration, and ultracentrifugation. These steps are optimized to enhance EV release from muscle tissues, yielding high-purity SkM-EVs. Subsequently, nano-flow cytometry, BCA assay, and Western blot assay are performed to characterize the quantity and quality of the isolated SkM-EVs. This protocol holds promise for establishing a reliable platform to obtain tissue-derived EVs for advancing basic research, disease diagnosis, and drug delivery.

Neuronal communication is mediated by synaptic transmission, which depends primarily on the release of neurotransmitters stored in synaptic vesicles (SVs) in response to an action potential (AP). Since SVs are recycled locally at the presynaptic terminal, coordination of SV exocytosis and endocytosis is important for sustained synaptic transmission. A pH-sensitive green fluorescent protein, called pHluorin, provides a powerful tool to monitor SV exo/endocytosis by targeting it to the SV lumen. However, tracking AP-driven SV recycling with the pHluorin-based probes is still largely limited to in vitro culture preparations because the introduction of genetically encoded probes and subsequent optical imaging is technically challenging in general for in vivo animal models or tissue preparations. Zebrafish is a model system offering valuable features, including ease of genetic manipulation, optical clarity, and rapid external development. We recently generated a transgenic zebrafish that highly expresses a pHluorin-labeled probe at motor neuron terminals and developed a protocol to monitor AP-driven SV exo/endocytosis at the neuromuscular junction (NMJ), a well-established synapse model that forms in vivo. In this article, we show how to prepare larval zebrafish NMJ preparation suitable for pHluorin imaging. We also show that the preparation allows time-lapse imaging under conventional upright epifluorescence microscope, providing a cost-effective platform for analyzing NMJ function.

Social animals, like rodents, are able to recognize and differentiate between the identity of familiar individuals. Recognizing the identity of familiar individuals is important for developing social structures such as hierarchy, kinship, and family. However, mechanisms underlying the recognition of social identity remain unclear. Most rodent studies of social recognition are based on the propensity of rodents to interact with a novel social target, a phenomenon known as social novelty. However, behavioral tasks for examining social novelty cannot reveal the recognition of familiar conspecifics based on their identities. Presented here are behavioral tasks allowing for the examination of identity recognition in C57BL/6 mice by associating two familiar mice with or without a valenced experience. Subjects had interactions with two mice either without (neutral) or with a valenced experience (negative or positive) and became familiar with these mice. The negatively valenced mouse was associated with shocks, while the positively valenced mouse was associated with a food reward. Following training, the recognition of the identity of these familiar mice can be revealed in a social discrimination test, which is represented as the preference for the positively valenced mouse and avoidance of the negatively valenced mouse compared to the neutral mouse. Behavioral tasks for identity recognition could be useful in probing social memory mechanisms and the pathophysiology of disorders with impaired social cognition, such as autism spectrum disorder or schizophrenia.

Mother's own milk (MOM) is the most complete nutritional resource for newborns. In cases where mothers are unable to produce sufficient milk or cannot breastfeed, the preferred alternative is pasteurized donor human milk (PDM), which is routinely provided by human milk banks. PDM offers a superior range of nutritional and immunological elements compared to any commercially available formula. However, to ensure biosafety, PDM undergoes pasteurization, a process that inactivates commensal microbiota and reduces certain bioactive compounds. This study presents a protocol designed to restore the microbiota of PDM using MOM as a microbial source, adapting the approach to a real-world clinical setting. The protocol was implemented in a clinical trial conducted at a maternity hospital and its associated human milk bank, with the aim of providing personalized donor milk to preterm infants whose mothers cannot produce sufficient milk. The methodology involves inoculating PDM with 10% of MOM, followed by incubation at 37 °C for 4 h. Microbiological analysis demonstrated successful bacterial growth in the inoculated milk (IM) post incubation, with the microbiota profile of the reconstituted milk (RM) closely resembling that of MOM, indicating effective microbiota restoration. These results suggest that the reconstitution protocol is feasible for implementation in neonatal care, with the potential to enhance the nutritional and immunological quality of PDM, thereby supporting the health and development of non-breastfed newborns.

Metabolic labeling techniques allow the incorporation of bioorthogonal reporters into glycans, enabling the targeted bioconjugation of molecular dyes within cells through click and bioorthogonal chemistry. Metabolic oligosaccharide engineering (MOE) has attracted considerable interest due to the essential role of glycosylation in numerous biological processes that involve molecular recognition and its impact on pathologies ranging from cancer to genetic disorders to viral and bacterial infections. Although MOE is better known for the detection of cell surface glycoconjugates, it is also a very important methodology for the study of intracellular glycans in physiological and pathological contexts. Such studies greatly benefit from high spatial resolution. However, super-resolution microscopy is not readily available in most laboratories and poses challenges for daily implementation. Expansion microscopy is a recent alternative that enhances the resolution of microscopy by physically enlarging biological specimens labeled with fluorescent markers. By embedding the sample in a swellable gel and causing it to expand isotropically through chemical treatment, subcellular structures can be visualized with enhanced precision and resolution without the need for super-resolution techniques. In this work, we illustrate the capacity of expansion microscopy to visualize intracellular sialylated glycans through the combined use of MOE and click chemistry. Specifically, we propose a procedure for bioorthogonal labeling and expansion microscopy that employs a reporter targeting sialylation, which may be associated with immunofluorescence for co-localization studies. This protocol enables localization studies of sialoconjugate biosynthesis, intracellular trafficking, and recycling.

In sepsis, understanding the interplay among white blood cells, lymphocytes, and neutrophils is crucial for assessing the immune condition and optimizing treatment strategies. Blood samples were collected from 512 patients diagnosed with sepsis and 205 healthy controls, totaling 717 samples. Data visualization analysis and three-dimensional numerical fitting were performed to establish a mathematical model describing the relationships among white blood cells, lymphocytes, and neutrophils. Self-organizing feature map (SOFM) was employed to automatically cluster the sepsis sample data in the three-dimensional space represented by the model, yielding different immune states. Analysis revealed that white blood cell, lymphocyte, and neutrophil counts are constrained within a three-dimensional plane, as described by the equation: WBC = 1.098 × Neutrophils + 1.046 × Lymphocytes + 0.1645, yielding a prediction error (RMSE) of 1%. This equation is universally applicable to all samples despite differences in their spatial distributions. SOFM clustering identified nine distinct immune states within the sepsis patient population, representing different levels of immune status, oscillation periods, and recovery stages. The proposed mathematical model, represented by the equation above, reveals a basic constraint boundary on the immune cell populations in both sepsis patients and healthy controls. Furthermore, the SOFM clustering approach provides a comprehensive overview of the distinct immune states observed within this constraint boundary in sepsis patients. This study lays the foundation for future work on quantifying and categorizing the immune condition in sepsis, which may ultimately contribute to the development of more objective diagnostic and treatment strategies.

Derived from monocytes in the bone marrow, macrophages are large, innate immune cells that play a major role in clearing dead cells, debris, tumor cells, and foreign pathogens. The phagocytic capacity of monocytes versus macrophages is a concept that is not well understood. Here, we aim to examine a difference in the phagocytosis of monocytes versus macrophages, specifically M1/M2 macrophages, against various opsonized red cells using a modified and updated version of the established monocyte monolayer assay (MMA). Peripheral blood mononuclear cells (PBMCs) were isolated from donor buffy coats. Using purified monocytes, inflammatory M1 and anti-inflammatory M2 macrophages were produced by in vitro culture and polarization. M1/M2 cells were harvested and used in an MMA-like assay, which we refer to as the M-MA, to decipher clinically significant phagocytosis of various red cell antibodies. A phagocytic index (PI) > 5 was deemed clinically significant phagocytosis with the use of monocytes. A phagocytic index (PI) > 12 was deemed clinically significant phagocytosis with the use of M1/M2 macrophages. M2 macrophages demonstrate an increased ability to phagocytose opsonized RBCs compared to monocytes and M1s. The same weak antibody (anti-S) yields significant phagocytosis with only M2 macrophages (PI=43) but not M1s (PI=2) or monocytes (PI=0), and this was demonstrated repeatedly using various antibodies. The use of M2 macrophages instead of monocytes may allow for more accurate results as these cells are more phagocytic, offering further clinical relevance to the assay. Further studies with different antibodies to red blood cells, including validation of the monocyte-macrophage assay (M-MA) with antibodies having known clinical significance, may show the M-MA more useful to help predict clinically significant red cell alloantibodies and transfusion reactions. This method will advance the field of transfusion medicine and immunology.

Optogenetics has become a fundamental technique in neuroscience, enabling precise control of neuronal activity through light stimulation. This study introduces easy-to-implement setups for applying optogenetic methods in Drosophila melanogaster. Two optogenetic tools, CsChrimson, a red-light-activated cation channel, and GtACR2, a blue-light-activated anion channel, were employed in four experimental approaches. Three of these approaches involve single-fly experiments: (1) a blue-light optogenetic thermotactic positional preference assay targeting temperature-sensitive heating cells, (2) a red-light optogenetic positional preference assay activating bitter sensing neurons, and (3) a proboscis extension response assay activating the sweet-sensing neurons. The fourth approach (4) is a fly maze setup to assess avoidance behaviors using multiple flies. The ability to manipulate neural activity temporally and spatially offers powerful insights into sensory processing and decision-making, underscoring the potential of optogenetics to advance our knowledge of neural function. These methods provide an accessible and robust framework for future research in neuroscience to enhance the understanding of specific neural pathways and their behavioral outcomes.