Apoptosis, also known as Programmed Cell Death, refers to the process by which a cell ends its life under certain physiological or pathological conditions, following its own procedures. It is an active, highly ordered, genetically controlled, and enzymatically involved process. The concept of apoptosis has been proposed for less than 30 years, but because it plays a key role in ensuring the healthy survival of multicellular organisms, the role of normal development and apoptosis in individuals in pathological research It has caused people to study extensively and deeply on its mechanisms and components, and has become one of the hottest topics in the life sciences. It is also a research field that the life sciences and even the society are vying for. From the recent SCI rankings we can see that the signal transmission article far exceeds the second human genome, and an important frontier in signal transduction is the study of apoptosis. As research in this area continues to heat up, a number of new techniques and methods have emerged to detect apoptosis, many of which have already appeared in commercial products, greatly accelerating the research process. Specifically, there are several methods for different stages of apoptosis:
     1. Early detection:
1) Detection of PS (phosphatidylserine) on the outer cell membrane:
The transfer of PS from the medial side of the cell membrane to the outside occurs shortly after induction of apoptosis by the cells, possibly as a marker of the immune system. Annexin V, a calcium-dependent phospholipid-binding protein, specifically binds PS exposed to the outside of the membrane and is detected by a simple color or luminescence system. Since this is a live cell assay for early apoptosis (both for both suspended and adherent cells), it can be combined with DNA dyes or other advanced assays to label the stage of apoptosis.
Based in California, BioVision is the world's leading company specializing in apoptosis and cell signaling research. Its products are of high quality, low price and convenient packaging. BioVision offers a wide range of labeled Annexin V products and a complete early apoptosis assay kit with nuclear dye PI.
BMS (Bender Medsystems) owns the patent for Annexin V and offers a wide range of Annexin V apoptosis assay kits. The Annexin V FITC kit contains Annexin V and nuclear dye PI, and is available in small packages for customers who are testing small samples.
In addition, Biovision and the German company Mei Tianni provide magnetic beads coated with Annexin V, which can be used to screen for apoptotic cells by magnetic sorting.
2) Detection of changes in intracellular redox status:
Under normal conditions, glutathione (GSH) acts as an important redox buffer for cells. The toxic oxides in the cells are periodically removed by reduction by GSH, and the oxidized GSH can be rapidly reduced by GSH reductase. This reaction is particularly important in mitochondria, where many oxidative damage in by-products from respiration is removed. In Jurcat and some other types of cells, there is an ATP-dependent GSH transfer system in the cell membrane that can be activated by an apoptotic signal. When the elimination of GSH in cells is very active, the cell fluid changes from a reducing environment to an oxidizing environment, which may lead to a decrease in mitochondrial membrane potential in early apoptosis, thereby making cytochrome C (an important component in the tricarboxylic acid cycle). Transferring from the mitochondria to the cell fluid initiates a cascade of apoptotic effector caspase.
Because GSH is closely related to redox and mitochondrial function, this test is useful for the study of diseases such as heart disease and stroke, in addition to being very useful for studying the initiation of apoptosis. However, some cells such as HeLa and 3T3 cells have no obvious changes in GSH levels when they are apoptotic and cannot be detected by this method.
3) Localization detection of cytochrome C
As a signal substance, cytochrome C plays an important role in apoptosis. Normally, it exists in the lumen between the mitochondrial inner membrane and the outer membrane. The apoptotic signal stimulates its release from the mitochondria to the cytosol, and initiates the caspase cascade after binding to Apaf-1 (apoptotic protease activating factor-1). : The cytochrome C/Apaf-1 complex activates caspase-9, which in turn activates caspase-3 and other downstream caspase.
The cytochrome c oxidase subunit IV (COX4) is a membrane protein localized on the inner mitochondrial membrane. When apoptosis occurs, it remains in the mitochondria, so it is a very useful part of the mitochondria-rich fraction. symbols of. The Cytochrome c Apoptosis Assay Kit is an effective way to detect the release of cytochrome c during apoptosis.
4) Detection of changes in mitochondrial membrane potential:
In the early stages of apoptosis studies, there was no significant change in mitochondria from morphological observations. With the deepening of the research on apoptosis mechanism, it is found that mitochondrial apoptosis is also an important component of apoptosis, and many physiological and biochemical changes occur. For example, the mitochondrial transmembrane potential changes after induction of apoptosis, resulting in a change in membrane permeability. MitoSensorTM, a cationic stain, is very sensitive to this change and exhibits different fluorescent staining. In normal cells, it forms aggregates in the mitochondria and emits intense red fluorescence. In apoptotic cells, due to changes in the mitochondrial transmembrane potential, it is present in the cell fluid as a monomer, emitting green fluorescence. These two different fluorescent signals can be clearly distinguished by fluorescence microscopy or flow cytometry. Biovision's MitoCaptureTM Mitochondrial Apoptosis Detection Kit provides easy, sensitive, in vitro analysis of changes in mitochondria during apoptosis.
  2. Late detection:
In advanced stages of apoptosis, endonucleases (the substrates of certain Caspase) cleave nuclear DNA between nucleosomes, producing a large number of DNA fragments 180-200 bp in length.
1) Apoptotic DNA Ladder Test Kit
After the cells were treated, the DNA was isolated and purified by a conventional method, and subjected to agarose gel and ethidium bromide staining, and a typical DNA ladder was observed in the apoptotic cell population. The Quick Apoptotic DNA Ladder Detection Kit allows sensitive detection of DNA fragments in apoptotic cells quickly (approximately 1-2 hours).
2) TUNEL-based DNA Fragment Analysis Kit
In apoptosis, chromosomal DNA double-strand breaks or single-strand breaks produce a large number of viscous 3'-OH ends, which can deoxyribonucleotides and fluorescence under the action of deoxyribonucleotide terminal transferase (TdT). A derivative formed by a hormone, a peroxidase, an alkaline phosphatase or biotin is labeled to the 3'-end of the DNA, thereby enabling detection of apoptotic cells. Apo-BrdUTM analysis The DNA bands in apoptotic cells were detected by flow cytometry using two color TUNEL methods. The BrdU used is more sensitive than the biotinylated or digoxigenylated labeling method. The new ApoBrdU-IHCTM is a complete kit for two-color immunohistochemistry (IHC) detection of DNA fragments. Apo-DIRECTTM is a very simple one-step labeling of apoptotic cells for flow cytometry analysis.
3) Caspase analysis reagents and kits
Caspase plays an important role in apoptosis and belongs to aspartic protease. Among them, caspase-3 is a key executive molecule that functions in many pathways of apoptotic signaling. Under normal conditions, the caspase family is expressed as an inactive zymogen (30-50 kD), which consists of the original domain, large subunit (~20 kD) and small subunit (~10 kD). When cells undergo apoptosis, caspase can be cleaved by proteases, and large subunits and small subunits form activated caspase. After activation of some caspase, other caspase can be sequentially activated to form a caspase cascade, which promotes apoptosis.
As the world's leading developer and supplier of apoptotic agents, Biovision offers comprehensive, high-quality caspase-related detection reagents.
Hearing aid manufacturers strive to optimize their wireless hearing aid offerings both in terms of connection reliability as well as power efficiency. Variance across patients and listening conditions can make optimizing wireless hearing aid systems a complex process.
Factors such as connection distance, proximity of reflective surfaces, interference from other wireless devices, and energy loss through body absorption must all be factored into the hearing aid design. For example, indoor wireless performance may be very different from wireless performance experienced outdoors, where the only reflective surface may be the ground on which the hearing aid user is standing. Furthermore, individual differences in body geometry increase the variability that wireless engineers must account for when designing a system that provides each user with a consistent and reliable experience.
As awareness of wireless hearing technology grows, hearing healthcare professionals may notice an uptick in long-term safety concerns. Consumers should be confident knowing that wireless hearing aids are safe and strictly regulated medical devices that meet governmental wireless communication standards in addition to those set forth for medical devices.
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