Prion (PrPS), also known as vein viruses, dirty toxin, is a class of host cell genes encoded by the structural abnormalities of the protein, which does not contain nucleic acids, strong resistance, self-replication and infectious, can cause a variety of mammals to develop transmissible spongiform encephalopathies (TSEs, such as sheep itchy disease, Creutzfeldt-Jakob disease, Kuru disease, mad cow disease, etc.), such as sheep itchy disease, Kayah disease, Kuru disease, mad cow disease. It is self-replicating and infectious and can cause transmissible spongiform encephalopathies (TSEs) in many mammals, such as scrapie, Creutzfeldt-Jakob disease, Crohn's disease and mad cow disease. More than 10 naturally occurring or infectious spongiform encephalopathies have been identified in humans and more than 20 species of animals.
Principle
Transmissible spongiform encephalopathies (TSEs), or dirty granulomas, are chronic degenerative and fatal diseases of the central nervous system. Different sources of TSEs may exhibit distinct "strain" differences in terms of incubation period, clinical features, neuropathologic manifestations, and molecular characterization of the TSEs. In general, the common features of dirty granulomas include:
① long incubation period, up to several years or decades;
② The onset of chronic, progressive development, mortality rate of 100%;
③ clinical manifestations of dementia, tremor, ataxia and other central nervous system symptoms;
④ Pathological characteristics of the central nervous system neuronal death, diffuse neuronal loss, astrocyte hyperplasia, spongy degeneration and amyloid plaque formation of cortical laxity, no inflammatory reaction of brain tissue.
Operation method
Clinical manifestations and specimen collection in prion disease
Principle
(I) Common human dirty granulomatous diseases 1. Creutzfeldt-Jakob disease (CJD) has a long incubation period of 10-15 years, or more than 40 years. Patients present with rapidly progressive dementia with myoclonus, cortical blindness, cerebellar ataxia, motor aphasia, hemiparesis, epilepsy, and even coma, and most cases have significant electroencephalogram (EEG) abnormalities with periodic synchronized slow waves. About 90% of the patients die of infection or autonomic failure within one year. Some cases lack typical clinical manifestations and need to be differentiated from other neurodegenerative diseases. 2. variant CJD (vCJD) Compared with typical CJD, this disease differs from typical CJD in terms of age of onset, clinical symptoms, duration of the disease, electroencephalogram (EEG), imaging, and pathological changes. vCJD is characterized by a young age group with clinical features such as progressive neurological disturbances and psychiatric disorders. Patients with vCJD are young and characterized by progressive neurological and psychiatric disorders resulting in ataxia, dementia, and involuntary movements; there is no electroencephalogram (EEG) as in typical CJD, and magnetic resonance imaging (MRI) reveals high intensity images in the posterior thalamic nuclei bilaterally. (II) Common animal chorioretinopathies 1. scrapie of sheep and goat (scrapie of sheep and goat) The incubation period of this disease is 1~3 years, and the onset of the disease is mostly seen in sheep aged 2~5 years, which is named because the affected sheep feel itchy, and rub their bodies against the fences of the sheep pens or the trunks of the trees (which can cause loss of sheep skin and skin ulcers). Clinical manifestations are mainly itching. Wasting, hair loss, water metabolism disorder (frequent drinking and frequent urination), unsteady gait, ataxia, paralysis, etc. 2. bovine spongiform encephalopathy (BSE), also known as mad cow disease (mad cow disease, MCD), most of the diseased cows are infected within Ⅰ year, with an average incubation period of 60 months. The average incubation period is 60 months, and the age of onset is usually between 4 and 6 years old, and the course of the disease is usually from 14 days to 6 months. Clinical manifestations mainly include ataxia, unsteady gait, high sensitivity, tremor, dementia, fear and frenzy.
Materials and Instruments
Material: Cadaveric brain tissue Move The general experimental procedure for the clinical presentation and specimen collection of prion disease is as follows: At present, the gold standard for the diagnosis of dirty granulomas is the detection of PrP~ which is tolerant to proteinase K. The specimens for dirty granulomas are mainly taken from cadaveric brain tissues. Brain tissue collection is synchronized with autopsy and should be performed within 48-72 hours after death. After the head is fixed, the brain is exposed by a chainsaw, the meninges are cut open with scissors, and the blood vessels and nerves connecting with the brain are cut off, and the whole brain is taken out and immediately frozen in dry ice, and then quickly put into -80 ℃ for freezing after being sent back to the laboratory.
Measurement of PrP in peripheral tissues such as lymph nodes and tonsils is expected to be a screening tool for asymptomatic vCJD patients, while screening for dirty biomarkers in body fluids such as cerebrospinal fluid, blood, and urine may also enable early warning and risk assessment.
Cerebrospinal fluid collection: Cerebrospinal fluid is collected by lumbar spinal puncture. The first 2 ml of cerebrospinal fluid collected should be discarded, followed by 2-5 ml to avoid bleeding. The fluid should be quickly frozen at -70 ℃ for examination.
The collection of biopsy tissue, blood, urine and other body fluids is described in the relevant sections.
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