What Are the Most Common Heat Syncope Symptoms?

Climbers who are weak in thermal syncope are prone to occur during summer mountaineering activities due to intense activity and excessive physical exertion, especially when they fail to replenish the lost water and salt in the body.

Thermal syncope

Climbers who are weak in thermal syncope are prone to occur during summer mountaineering activities due to intense activity and excessive physical exertion, especially when they fail to replenish the lost water and salt in the body.

Chinese name

Thermal syncope

Symptom

Feeling exhausted but restless

Prevention

Pay attention to rest rhythm and maintain strength

Measures

Drugs to prevent and treat heat stroke

The main symptoms of hot syncope are: feeling exhausted but restless, headache, dizziness or nausea. His face was pale and his skin felt damp and cold. Breathe fast and shallow, pulse fast and weak. May be accompanied by twitching of the lower limbs and abdominal muscles. Body temperature remains normal or drops.

prevention

In order to avoid thermal syncope, some weak climbers are participating in summer mountain climbing activities.

When riding on a hot, humid and windless road in summer, because the body cannot control the body temperature by sweat evaporation, people will become hot and fainted. If they are not treated in time, people may quickly lose consciousness, and the degree is very deep, which may cause accidents. Happens therefore during the summer ride

Heat syncope heat shock protein

1.Heat shock proteins (HSPs)

Almost all cells produce HSPs under heat stress, and cells can express certain HSPs under normal conditions. Normally exposing cells to 42 to 45 ° C for 20 to 60 minutes and then returning to normal temperature can induce the expression of HSPs. The induced expression of HSPs occurred within minutes after the onset of heat stress, and peaked within a few hours. Research finds that during periods of high fever

Thermal syncope

Or just released the fever, HSPs are the main synthetic proteins in the cell. Interestingly, the lack of introns in most HSPs genes is conducive to their rapid expression, and it can also explain why HSPs can still be expressed in the presence of an emergency source that can affect RNA editing. Increased intracellular HSPs will protect cells from heat, ischemia, hypoxia, endotoxin and inflammatory factors. In some patients with low expression of HSPs, such as elderly patients, people who lack heat adaptation, or people with certain genetic polymorphisms, heat stress can more easily progress to shock. The expression of HSPs is basically regulated at the gene transcription level. During heat stress, one or several heat shock factors (HSF) combine with heat shock elements (HSE), resulting in increased transcription of HSPs. With the increase of intracellular HSPs, the cell will develop a transient tolerance state to heat stress, which enables the cell to survive even a lethal amount of heat stress. Inhibition of HSPs at the level of gene transcription

The synthesis or use of specific antibodies to HSPs can make cells extremely sensitive to trace heat stress. In living experiments, cells can tolerate heat

Protect experimental animals from damage caused by high temperatures, low arterial blood pressure, and cerebral ischemia. This protective effect against heat stroke injury is consistent with the expression level of HSP72, which accumulates in the brain after heat shock treatment. The mechanism by which HSPs can protect cells may be because it can bind to partially folded or misfolded proteins as a molecular chaperone, thus preventing irreversible protein denaturation. Another possible mechanism is that HSPs act as a central regulator of the stress-emission response. In severe heat stress, they can alleviate hypotension and bradycardia, thereby protecting the cardiovascular system. HSPs can be divided into HSP100, HSP90, HSP70, HSP60, small-molecule HSPs (molecular mass: 212 to 312ku), and

Vegetarian. The above families, the most important of which is the HSP70 family, each family is composed of multiple members. With the deepening of research, newly discovered HSPs will continue to be classified into corresponding families, and may even be: can re-form families. HSPs have three basic activities.

As a molecular partner. This activity can help prevent misaggregation of the disaggregated protein, assist it in refolding, and restore its natural conformation. Even in non-stressed cells, some HSPs chaperones can make the newly formed peptides form a natural conformation during protein synthesis. In addition, it can also stabilize the special conformation of the protein through some normal cell regulatory functions, such as cell cycle regulation, processing of steroids and vitamin D receptors, and antigen presentation functions. HSP40, HSP60, HSP70 and HSP90 family proteins all have this chaperone function.

Regulate the redox state of cells. One of the best examples of this class is HSP32, which is a heme oxygenase (HO1), which catalyzes heme into bilirubin and free iron, which is converted into An effective antioxidant, bilirubin, which protects cells. The free iron catalyzed by HO1 can increase the synthesis of ferritin. Ferritin can isolate free iron from strong oxidants, thereby exerting its cytoprotective effect.

Regulation of protein turnover. For example, ubiquinone, which can be expressed in unstressed cells, is upregulated during heat shock, and serves as a molecular marker to label proteins and degrade them by proteases. HSPs also have some other important biochemical activities. For example, HO1 can produce carbon monoxide (CO) through the degradation of heme, and it plays an important role in signal transduction of nerve tissue and vascular smooth muscle; CO can interact with the guanosine ring. Enzymes interact to produce cyclic guanosine monophosphate (cGMP), which has the effect of dilating vascular smooth muscle. This may be another mechanism by which stressed tissues can regulate local blood flow. Other studies have found that exogenous HSP70 can trigger the release of human monocyte CD14 receptor-mediated TNFA, IL1B and IL6, suggesting that HSP70 may be a pro-inflammatory factor.

HSF Thermal syncope HSF

HSF is a transcription factor that can bind to a specific sequence (HSE) of the promoter region of genes to regulate the expression of HSPs. HSE is a DNA sequence located in the promoter region and contains multiple consecutive repeats 5'nGAAn3 '. HSPs and many other genes contain HSE. It has been found that there are four types of HSF: HSF1, HSF2, HSF3, and HSF4. Among them, mammalian genes include three types: HSF1, HSF2, and HSF4. HSF3 exists in bird genes and is not available to humans. HSF1 is involved in the stress response of heat shock. Although other factors participate in the regulation of multiple responses, it is generally considered not to participate in the heat stress response. However, recent studies have shown that shock can reversibly inactivate HSF2. Before the occurrence of heat stress, HSF1 was present in the cytoplasm of unstressed cells in the form of monomers, and HSF1 combined with HSP70 and HSP90 to form precipitates and inactivate them. When a thermal stress response occurs, the protein undergoes thermal denaturation and exposes hydrophobic regions. Because denatured proteins are more likely to bind to HSPs, it is inferred that when cellular thermal stress occurs, heat-denatured proteins competitively bind HSPs, release HSF1, and activate it. After being activated by heat stress, HSF1 enters the nucleus to form a trimer and is concentrated to form small particles. The HSF1 trimer binds to HSE and increases the expression of HSP genes.

HSF1 and HSE do not always induce transcription. For example, by stimulating human monocytes with lipopolysaccharide, HSF1 inhibits the transcription of IL1. In addition, the overall effect of HSF1 binding to DNA (inhibition or induction of gene expression) is regulated by its own phosphorylation. However, usually monomeric HSF1 is phosphorylated, so the trimer HSF1 can bind to DNA unless heat shock Make HSF go

Thermal syncope

Phosphorylation and hyperphosphorylation were performed several times. In other cases, HSF1 hyperphosphorylation reduces the transcriptional activity of cells at normal temperatures. HSF1 serine residues can be hyperphosphorylated by mitotic protein kinase (MAP), protein kinase CA, protein kinase CF, glycogen synthase kinase 3A, etc., all of which can inhibit cell transcriptional activity. HSF1 can also be hyperphosphorylated by cJunNH2 terminal kinase (JNK), which can activate transcription in some cases and inhibit transcription in some cases. Recent studies have shown that heat stress can induce the end of HSF1 to be labeled with a small ubiquitin-modified factor 1 (SUMO1). SUMO1 is a special protein that can be used by cells to modify the protein to enter different parts of the cell. Play different functions. In these studies, HSF1 was unable to bind DNA in vitro unless the lysine 298 at its terminus was modified by SUMO1. HSF1 can also affect gene transcription without binding to the promoter of the gene. In mouse ovarian fibroblasts, heat shock can inhibit serum-induced cfos expression. The mechanism is that Ras can induce activation of the cfos promoter, and HSF1 can inhibit this response. Interestingly, Ras-mediated activation of cfos can be suppressed by a mutant of HSF1 that does not bind DNA. Another gene was also found in the urokinase promoter region to be regulated by the Ras gene with a similar effect. These results indicate that HSF1 can counteract Ras-mediated activation of cfos gene transcription without binding to DNA. In addition to positive regulation of gene expression through HSF1, HSE can also negatively regulate gene expression through a constant expression protein, HSE binding factor (HSFBF).

Therefore, in addition to phosphorylated HSF1 with positive regulatory activity, it can also activate transcription by affecting the binding of HSEBF to HSE.

Changes in expression of other genes in heat syncope and heat stress

In addition to HSF1, there are other regulatory mechanisms that can regulate gene expression at the transcriptional level during heat stress. At present, at least three sets of mechanisms are known to regulate the expression of heat-stressed genes at the transcription level: Changes in the expression level of transcription factors themselves: for example, the protein expression levels and mRNA expression levels of fos and Jun are up-regulated in heat shock ; The expression level of cmyc is down-regulated due to the enhanced degradation of cytoplasmic mRNA; the expression of the egr1 gene in mouse fibroblasts NIH & ouml; 3T3 is up-regulated under heat stress induction, which is similar to the cell stress induced by arsenite, It mediates the phosphorylation of the transcription factor elk1 through p38 and JNK; heat shock affects the expression of C & ouml; EBPA and C & ouml; EBPB and changes in DNA binding activity, thus affecting mRNA expression levels and relative expression levels of different protein isomers .

Changes in transcription factor activity: For example, in human glioblastoma A172 cell line, heat-shock altered DNA-binding activity did not pass through HSF1 but p53, but in mouse thymocytes, Oct1 and cyclic adenosine monophosphate response element binding protein (CREB) reduced binding activity; Another example of heat shock-induced changes in transcription factor activity is the AP1 system. In mouse 3T3 cells, heat shock can induce cJun phosphorylation through JNK, which is usually accompanied by AP1 that specifically binds DNA. Enhanced capabilities. Changes in the location of transcription factors in the cell (such as being shifted into the nucleus or remaining in the cytoplasm): For example, in colon cancer cell lines, heat shock causes the Y-box transcription factor to transfer from the cytoplasm to the cell Nuclear, leading to increased expression of the multidrug resistance genes MDR1 and MRP1. Nearly 50 genes traditionally thought not to belong to HSP changed their expression during heat stress. Molecules encoded by several heat-responsive genes can regulate the MAP kinase pathway, which plays an important role in the cell's response to various environmental stresses. Among the most interesting are MAP phosphatase bispecific phosphatase 1 (DUSP1) and DUSP5, which play a role in dephosphorylation in the MAP pathway. MAP kinases are known to be activated when heat stress begins. In principle, the subsequent expression of DUSP readjusts the MAP signaling pathway, allowing it to respond to subsequent stress responses after the initial thermal stress. This hypothesis may be used in the physiological mechanism of cells to obtain heat tolerance, of course, it needs further experimental verification. Another effect of heat shock is the ability to block the cell cycle, which is mediated by gene expression and the activity of expressed proteins.

Both genes p53 and p21, which are known to affect the cell cycle, can be affected by heat shock. It seems that p53's inhibition of cell cycle progression is critical because cell cycle inhibition has not been found in p53 gene-deficient cell lines. To some extent, the effect of heat shock on non-HSP genes is tissue-specific. For example, in vivo and in vitro experiments, heat stress can increase the expression of manganese peroxide dismutase (MnSOD) in rat cardiac muscle cells. However, it does not induce MnSOD expression in mouse alveolar cells, and even inhibits it. The mechanism is still unclear. However, the existence of this difference suggests that there is a tissue-specific mechanism to regulate the cell's response to heat stress. For example, myocardium has higher oxygen consumption than other tissues, and its redox state is different from other low oxygen consumption tissues. Heat shock response may stimulate MnSOD expression through the effect on redox state.

In addition, the enzyme-linked immunosorbent assay (ELISA) myocardial MnSOD activity does not have a one-to-one relationship with its protein level. With the deepening of research on heat shock, more and more genes are considered to play an important role in it. In addition, the gene chip enables researchers to study the expression of thousands of genes at the same time, so it also enables people to understand more genes in heat stress. These studies have revealed that gene expression changes in heat stress far exceed what was previously known, and it involves every major functional classification. Understanding the genesis and genetic relationship of thermal syncope provides new ideas for prevention and treatment. For example, reducing body temperature to normal does not prevent inflammatory reactions, the formation of thrombus, and the occurrence of multiple organ dysfunction. Therefore, it is necessary to study new methods to regulate inflammatory reactions in animals. Immunomodulators such as interferon receptor antagonists, endotoxin antibodies, and corticosteroids can improve animal survival, but similar studies have not been performed in humans, and it is still unclear what the resistance in the treatment of sepsis is. Whether endotoxin and anti-cytokine strategies work equally well in thermal syncope. In an inflammation-related injury model (such as a mouse model of sepsis), it may be more effective to use new interventions to suppress the nuclear transcription factor JB (NFJB). NFJB is a key in regulating acute inflammatory responses. The role of transcription factors, studies have shown that inhibition of NFJB activity can improve survival, but also promote apoptosis of liver cells. During thermal syncope, activation of the coagulation and fibrinolytic systems often results in diffuse intravascular coagulation. Recombinant activated protein C can reduce coagulation and inflammation, and its replacement therapy can reduce the mortality of patients with sepsis, so it may be effective in treatment. Elucidating the molecular mechanisms that trigger coagulation may lead to more effective and specific treatments, such as tissue factor pathway inhibitors. More importantly, potential treatments are based on knowledge of stress response proteins. Logically the next generation of immune modulators is pharmacologically selective in the expression of HSPs. Salicylate and non-steroidal anti-inflammatory drugs activate HSF in mammals and induce the transcription and translation of HSPs. This response can increase the thermal tolerance of cells. And protect cells from heat stress. Although overexpression of HSP can suppress some important functions of cells, partial up-regulation of HSP has proven to be beneficial, especially as a precautionary measure at high temperatures. Future research will require determining to what extent the regulation of inflammation and stress responses will not affect basic immune function.

Scraping after thermal syncope is beneficial for rapid relief