动物造模,药效评价,缩窄性心包炎 z-bio 2024-07-16 415

　　(1) Method of replication: New Zealand rabbits weighing 1.5-2.0kg were immobilized in a supine position and locally anesthetized with 2% procaine. Make a small incision in the center of the upper abdomen and take about 0.5g of liver tissue to check the liver water content. Then, a midline incision of about 2cm is made in the chest, and the pectoral muscles are pushed open to 1.5cm beside the sternum, close to the sternum and left rib cage. The upper and lower ribs at the intercostal muscle incision are pulled apart to both sides, avoiding the pleura and exposing the bare pericardial area; Use a No.7 lumbar puncture needle to puncture horizontally under the xiphoid process towards the apex of the heart, and enter the pericardial cavity through the diaphragmatic surface. Inject 1ml/kg body weight of inducer (inducer preparation: 4g sterile talc powder, 1g tetracycline powder, added to 20ml 1.5% iodine tincture to prepare a suspension). After injecting the inducer, the animals were euthanized 2 weeks later. Immediately open the chest to measure the left and right pleural effusion, observe the thickening of the pericardium, and evaluate the level of pericardial thickening. Take 2 myocardial and 2 pericardial specimens for pathological examination. Open the abdominal cavity to measure ascites, take 2 liver tissue specimens, send 1 for pathological examination, and check the water content of liver tissue in 1 specimen. Assessment criteria for degree of pericardial adhesion and thickening: Grade 0: Normal pericardium: Pericardium is thin, transparent, and has no adhesion to the myocardium. The vascular network on the surface of the myocardium can be clearly seen through the pericardium; Grade 1: Thickening and whitening of the pericardium, scattered filamentous adhesions between the pericardium and myocardium, and larger blood vessels on the surface of the myocardium visible through the pericardium; Level 2: Thickening and whitening of the pericardium, adhesion between the pericardium and myocardium, no blood vessels visible through the pericardium, but myocardium visible; Grade 3: Thickening and whitening of the pericardium, making it impossible to see the myocardium through the pericardium. Determination and Calculation of Liver Moisture Content: Before and 2 weeks after model production, take 1 piece of liver tissue of 0.5g size, rinse with physiological saline, dry the water with filter paper, weigh it on an analytical balance as wet weight, place it in a 60 ℃ oven for 72 hours, and the weight at constant weight is dry weight. Then calculate according to the following formula: liver moisture content=(liver wet weight - dry weight)/wet weight × 100%. Pericardial, myocardial, and liver tissue specimens are fixed with 10% formaldehyde solution, embedded in paraffin, sliced, stained with HE, and observed under a light microscope.

　　(2) The model features a simple and feasible method of injecting inducers through the chest under local anesthesia, with minimal interference to the animal body and no need for special postoperative care. Improvements have also been made to the assessment of pericardial thickening in experimental animals. The traditional method is to make pathological sections of pericardial specimens and observe and compare them under a microscope. Due to differences in specimen collection and observer understanding, there is a lack of unified standards for determining pericardial thickening. This experiment utilized the transparent characteristics of normal rabbit pericardium and used the myocardium and its surface blood vessels as reference to evaluate the thickening of the pericardium. The thickening of the pericardium was relatively quantified, and a relatively clear objective indicator was established for judging the thickness of the pericardium. And the rabbits used in this model, which have multiple animal sources and low prices, are used as experimental animals. The operation is simple, fast, and conducive to the large-scale replication of the model. This provides a new animal model for further in-depth research on constrictive pericarditis.

　　(3) In comparative medical clinical practice, pericardial constriction restricts the relaxation and contraction of the myocardium, obstructs venous return, causes systemic venous congestion, inadequate arterial blood supply, and ischemia and hypoxia of important organs. This model showed that after injecting inducers into the pericardial cavity for 2 weeks, animals exhibited signs of pulmonary and systemic congestion, such as thickening of the pericardium, increased breathing, pleural effusion, ascites, and increased liver water content. These manifestations are similar to the clinical signs of constrictive pericarditis. Animal anatomy also shows that rabbits are different from dogs, sheep, and other animals in that the pleural fold in the chest cavity is very similar to that in humans, with a bare pleural area of about 1cm2 in front of the pericardium.