Pancreatic polypeptide

Pancreatic Polypeptide (PP) is a 36 amino acid linear polypeptide hormone secreted by PP cells of the pancreas. PP cells are affected by protein in food after meals. Protein is the strongest factor in stimulating PP secretion, followed by fat and sugar. The release of PP is vagal-cholinergic, regulated by the vagus nerve and can be inhibited by vagus nerve resection and anticholinergics. Duodenal acidification, endogenous CCK release, can be used as the main hormone to stimulate the release of PP, so that the PP value is significantly increased. Insulin causes elevated PP to be caused by hypoglycemia and vagus nerve. Growth hormone inhibits PP release and postprandial PP levels. PP has the following physiological effects: 1 inhibits the secretion of cholecystokinin and pancreatic enzyme, relaxes the gallbladder smooth muscle, reduces the pressure in the gallbladder, strengthens the common bile duct sphincter, and inhibits the discharge of bile to the duodenum. 2 various foods into the small intestine have a stimulating effect on PP release. The physiological role of PP is to inhibit the secretion of pancreatic juice and bile after meal, and the effect of exogenous pancreatic secretion such as secretin and cholecystokinin. Inhibitor. 3PP has a wide-ranging effect on the gastrointestinal tract and inhibits gastric acid secretion caused by pentagastrin gastrin. 4PP inhibits the secretion of plasma motilin, increases the pressure of the lower esophageal sphincter, and inhibits the myoelectric activity of the stomach. Basic Information Specialist classification: growth and development examination classification: blood examination Applicable gender: whether men and women apply fasting: fasting Analysis results: Below normal: Common in vagus nerve damage. Normal value: Male: 108-184ng/L Female: 105-175ng/L Above normal: Common in diseases such as diabetes or cirrhosis. negative: Positive: Tips: Men are higher than women. Normal value Young male: (146 ± 38) ng / L. Female: (140 ± 35) ng / L. Clinical significance (1) The plasma PP level of duodenal ulcer was significantly higher than that of the normal control group. Due to its high vagal tone and gastric acid secretion level, combined with atropine inhibition reaction, PP can be used as a basic vagus nerve tension in abdominal organs. Independent quantitative indicators. If the vagus nerve is damaged or cut off during surgery, the vagus nerve is particularly damaged in the head of the pancreas (concentration of the PP cells), and the PP level and response ability are lowered. (2) The decrease of the base PP value of the gastric ulcer and the postprandial reaction value of the protein may reflect the decrease of the vagus nerve tension. (3) The level of PP in the blood of some patients with gastric cancer is significantly increased. After gastric resection, the level of PP is decreased. (4) The basic level of PP and the postprandial stimulation level of chronic pancreatitis were lower than normal. The pancreatic response to insulin and insulin was decreased, and the postprandial PP level was significantly lower than that of the normal control group. There was no significant decrease in PP cells in the early stage of chronic pancreatitis. The above reaction was still normal, and the PP response to moderate to severe chronic pancreatitis was abnormal. Plasma PP levels can be used as a means of detecting pancreatic exocrine function. (5) Pancreatic tumors, especially those of the pancreatic head, which contain more PP cells, 50% to 70% of circulating blood, and the PP value of pancreatic cancer and other adenocarcinomas (stomach, breast, colon) All are normal, so the determination of PP in blood has certain reference significance for the early detection of pancreatic endocrine cell tumor (ie APUD tumor) and malignant tumor. (6) Patients with cirrhosis and cirrhosis have elevated plasma PP levels, with an average peak of (605±105) ng/L, and a high plasma PP level for a longer period of time, which is related to the destruction or degradation process of PP in the liver. Related to obstacles. (7) The deficiency and relative deficiency of insulin in diabetes increased the basic value of PP, and the PP value of controlled diabetic patients decreased. High results may be diseases: liver cirrhosis, neuroendocrine tumors, pancreatic polypeptide tumors The basal level of pancreatic polypeptide is age-related and increases with age, a phenomenon thought to be associated with increased vagal tone. Men are higher than women, and the basic and postprandial values ​​of PP are lower than normal. Inspection process The method is divided into three steps, namely antigen-antibody reaction, B and F separation, and radioactivity determination. (1) Reaction of antigen with antibody: The specimen (non-labeled antigen), labeled antigen and antiserum are sequentially dosed into a small test tube, and allowed to stand at room temperature (15 to 30 ° C) for 24 hours to fully compete for binding. (2) Separation of B and F: There are various separation techniques, and the precipitation method is commonly used. 1 second antibody precipitation method: also known as diabody method, after the test antigen specifically reacts with the first antibody, the corresponding second antibody is added, so that the formed antigen-first antibody-second antibody complex is co-precipitated. The labeled antigen B is separated from the free antigen F by centrifugation. This method is a specific precipitation, complete separation, low non-specific binding. However, the amount of the second antibody is large and the cost is high. In addition, the serum concentration and the presence or absence of anticoagulants can affect the results to some extent. 2 Polyethylene glycol (PEG) precipitation method: the protein is in an isoelectric point state, and the hydration layer is destroyed to cause protein precipitation. The advantage of this method is that PEG is convenient to prepare, inexpensive, and rapid to separate. The disadvantage is that there are many non-specific precipitates and the separation is incomplete. 3Second antibody-polyethylene glycol precipitation method: This method not only has the advantage of rapid precipitation of PEG method, but also maintains the effect of specific precipitation of second antibody, reduces the amount of second antibody, and reduces the concentration of PEG, so that non-specific precipitation Reduced material. 4 Activated carbon adsorption method: the free part of small molecules is adsorbed by the surface activity of activated carbon. For example, a layer of dextran is coated on the surface of the activated carbon to make a mesh having a certain pore diameter on the surface, thereby allowing small molecules of free antigen or hapten to escape and being adsorbed, while the macromolecular complex is excluded. After the antigen and the antibody are reacted, the dextran-activated carbon is added and allowed to stand for 5 to 10 minutes, so that the free antigen is adsorbed on the activated carbon particles, and the particles are precipitated by centrifugation, and the supernatant contains the labeled antigen. (3) Determination of radioactivity: After separation of B and F, the radioactivity can be measured. There are two types of measuring instruments: a liquid scintillation counter (measuring beta rays) and a crystal scintillation counter (measuring gamma rays). The unit of counting is the number of electrical pulses output by the detector in units of cpm (number of pulses/min). A standard curve is required for each measurement, and the different concentrations of the standard antigen are plotted on the abscissa, and the corresponding radioactivity measured is plotted on the ordinate. The radioactivity may be optionally B or F, and the calculated values ​​B/B+F, B/F or B/B0 may also be used. Specimens should be determined in duplicate, the average value is taken, and the corresponding antigen concentration is detected on the standard curve. Not suitable for the crowd 1. Patients who have taken contraceptives, thyroid hormones, steroid hormones, etc., may affect the results of the examination and prohibit patients who have recently taken the drug history. 2, special diseases: patients with hematopoietic function to reduce disease, such as leukemia, various anemia, myelodysplastic syndrome, etc., unless the examination is essential, try to draw less blood. Adverse reactions and risks 1, subcutaneous hemorrhage: due to pressing time less than 5 minutes or blood draw technology is not enough, etc. can cause subcutaneous bleeding. 2, discomfort: the puncture site may appear pain, swelling, tenderness, subcutaneous ecchymosis visible to the naked eye. 3, dizzy or fainting: in the blood draw, due to emotional overstress, fear, reflex caused by vagus nerve excitement, blood pressure decreased, etc. caused by insufficient blood supply to the brain caused by fainting or dizziness. 4. Risk of infection: If you use an unclean needle, you may be at risk of infection.