A group of genetic, infectious, or sporadic degenerative human and animal nervous system disorders associated with abnormal PRIONS. These diseases are characterized by conversion of the normal prion protein to an abnormal configuration via a post-translational process. In humans, these conditions generally feature DEMENTIA; ATAXIA; and a fatal outcome. Pathologic features include a spongiform encephalopathy without evidence of inflammation. The older literature occasionally refers to these as unconventional SLOW VIRUS DISEASES. (From Proc Natl Acad Sci USA 1998 Nov 10;95(23):13363-83)
Small proteinaceous infectious particles which resist inactivation by procedures that modify NUCLEIC ACIDS and contain an abnormal isoform of a cellular protein which is a major and necessary component. The abnormal (scrapie) isoform is PrPSc (PRPSC PROTEINS) and the cellular isoform PrPC (PRPC PROTEINS). The primary amino acid sequence of the two isoforms is identical. Human diseases caused by prions include CREUTZFELDT-JAKOB SYNDROME; GERSTMANN-STRAUSSLER SYNDROME; and INSOMNIA, FATAL FAMILIAL.
Abnormal isoform of prion proteins (PRIONS) resulting from a posttranslational modification of the cellular prion protein (PRPC PROTEINS). PrPSc are disease-specific proteins seen in certain human and animal neurodegenerative diseases (PRION DISEASES).
Normal cellular isoform of prion proteins (PRIONS) encoded by a chromosomal gene and found in normal and scrapie-infected brain tissue, and other normal tissue. PrPC are protease-sensitive proteins whose function is unknown. Posttranslational modification of PrPC into PrPSC leads to infectivity.
A rare transmissible encephalopathy most prevalent between the ages of 50 and 70 years. Affected individuals may present with sleep disturbances, personality changes, ATAXIA; APHASIA, visual loss, weakness, muscle atrophy, MYOCLONUS, progressive dementia, and death within one year of disease onset. A familial form exhibiting autosomal dominant inheritance and a new variant CJD (potentially associated with ENCEPHALOPATHY, BOVINE SPONGIFORM) have been described. Pathological features include prominent cerebellar and cerebral cortical spongiform degeneration and the presence of PRIONS. (From N Engl J Med, 1998 Dec 31;339(27))
A fatal disease of the nervous system in sheep and goats, characterized by pruritus, debility, and locomotor incoordination. It is caused by proteinaceous infectious particles called PRIONS.
An enzyme that catalyzes the hydrolysis of keratin, and of other proteins with subtilisin-like specificity. It hydrolyses peptide amides. Endopeptidase K is from the mold Tritirachium album Limber. (Enzyme Nomenclature, 1992) EC 3.4.21.64.
An autosomal dominant disorder characterized by degeneration of the THALAMUS and progressive insomnia. It is caused by a mutation in the prion protein (PRIONS).
An autosomal dominant familial prion disease with a wide spectrum of clinical presentations including ATAXIA, spastic paraparesis, extrapyramidal signs, and DEMENTIA. Clinical onset is in the third to sixth decade of life and the mean duration of illness prior to death is five years. Several kindreds with variable clinical and pathologic features have been described. Pathologic features include cerebral prion protein amyloidosis, and spongiform or neurofibrillary degeneration. (From Brain Pathol 1998 Jul;8(3):499-513; Brain Pathol 1995 Jan;5(1):61-75)
A transmissible spongiform encephalopathy (prion disease) of DEER and elk characterized by chronic weight loss leading to death. It is thought to spread by direct contact between animals or through environmental contamination with the prion protein (PRIONS).
A transmissible spongiform encephalopathy of cattle associated with abnormal prion proteins in the brain. Affected animals develop excitability and salivation followed by ATAXIA. This disorder has been associated with consumption of SCRAPIE infected ruminant derived protein. This condition may be transmitted to humans, where it is referred to as variant or new variant CREUTZFELDT-JAKOB SYNDROME. (Vet Rec 1998 Jul 25;143(41):101-5)
A prion disease found exclusively among the Fore linguistic group natives of the highlands of NEW GUINEA. The illness is primarily restricted to adult females and children of both sexes. It is marked by the subacute onset of tremor and ataxia followed by motor weakness and incontinence. Death occurs within 3-6 months of disease onset. The condition is associated with ritual cannibalism, and has become rare since this practice has been discontinued. Pathologic features include a noninflammatory loss of neurons that is most prominent in the cerebellum, glial proliferation, and amyloid plaques. (From Adams et al., Principles of Neurology, 6th ed, p773)
The family Cervidae of 17 genera and 45 species occurring nearly throughout North America, South America, and Eurasia, on most associated continental islands, and in northern Africa. Wild populations of deer have been established through introduction by people in Cuba, New Guinea, Australia, New Zealand, and other places where the family does not naturally occur. They are slim, long-legged and best characterized by the presence of antlers. Their habitat is forests, swamps, brush country, deserts, and arctic tundra. They are usually good swimmers; some migrate seasonally. (Walker's Mammals of the World, 5th ed, p1362)
A fibrous protein complex that consists of proteins folded into a specific cross beta-pleated sheet structure. This fibrillar structure has been found as an alternative folding pattern for a variety of functional proteins. Deposits of amyloid in the form of AMYLOID PLAQUES are associated with a variety of degenerative diseases. The amyloid structure has also been found in a number of functional proteins that are unrelated to disease.
The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.
The amount time between exposure to an infectious agent and becoming symptomatic.
A genus of the family Muridae having three species. The present domesticated strains were developed from individuals brought from Syria. They are widely used in biomedical research.
Processes involved in the formation of TERTIARY PROTEIN STRUCTURE.
Any of the ruminant mammals with curved horns in the genus Ovis, family Bovidae. They possess lachrymal grooves and interdigital glands, which are absent in GOATS.
A subfamily in the family MURIDAE, comprising the hamsters. Four of the more common genera are Cricetus, CRICETULUS; MESOCRICETUS; and PHODOPUS.
Laboratory mice that have been produced from a genetically manipulated EGG or EMBRYO, MAMMALIAN.
An acridine derivative formerly widely used as an antimalarial but superseded by chloroquine in recent years. It has also been used as an anthelmintic and in the treatment of giardiasis and malignant effusions. It is used in cell biological experiments as an inhibitor of phospholipase A2.
Protease-resistant core of PrPSC, the abnormal isoform of prion proteins (PRIONS). PrP 27-30 is produced by limited proteolysis of the N-terminus of PrPSc.
Disorders caused by imbalances in the protein homeostasis network - synthesis, folding, and transport of proteins; post-translational modifications; and degradation or clearance of misfolded proteins.
Hereditary and sporadic conditions which are characterized by progressive nervous system dysfunction. These disorders are often associated with atrophy of the affected central or peripheral nervous system structures.
The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).
Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.
A colloidal, hydrated aluminum silicate that swells 12 times its dry size when added to water.
Non-hematopoietic cells, with extensive dendritic processes, found in the primary and secondary follicles of lymphoid tissue (the B cell zones). They are different from conventional DENDRITIC CELLS associated with T-CELLS. They are derived from MESENCHYMAL STEM CELLS and are negative for class II MHC antigen and do not process or present antigen like the conventional dendritic cells do. Instead, follicular dendritic cells have FC RECEPTORS and C3B RECEPTORS that hold antigen in the form of ANTIGEN-ANTIBODY COMPLEXES on their surfaces for long periods for recognition by B-CELLS.
A suborder of the order ARTIODACTYLA whose members have the distinguishing feature of a four-chambered stomach, including the capacious RUMEN. Horns or antlers are usually present, at least in males.
Changes in the amounts of various chemicals (neurotransmitters, receptors, enzymes, and other metabolites) specific to the area of the central nervous system contained within the head. These are monitored over time, during sensory stimulation, or under different disease states.
Identification of proteins or peptides that have been electrophoretically separated by blot transferring from the electrophoresis gel to strips of nitrocellulose paper, followed by labeling with antibody probes.
Proteins that form the core of amyloid fibrils. For example, the core of amyloid A is formed from amyloid A protein, also known as serum amyloid A protein or SAA protein.
A country in northern Africa, bordering the Mediterranean Sea, between Egypt, Tunisia, and Algeria, having southern border with Chad, Niger, and Sudan. Its capital is Tripoli.
Inbred C57BL mice are a strain of laboratory mice that have been produced by many generations of brother-sister matings, resulting in a high degree of genetic uniformity and homozygosity, making them widely used for biomedical research, including studies on genetics, immunology, cancer, and neuroscience.
The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.
A heavy metal trace element with the atomic symbol Cu, atomic number 29, and atomic weight 63.55.
Different forms of a protein that may be produced from different GENES, or from the same gene by ALTERNATIVE SPLICING.
Diseases of viral origin, characterized by incubation periods of months to years, insidious onset of clinical manifestations, and protracted clinical course. Though the disease process is protracted, viral multiplication may not be unusually slow. Conventional viruses produce slow virus diseases such as SUBACUTE SCLEROSING PANENCEPHALITIS, progressive multifocal leukoencephalopathy (LEUKOENCEPHALOPATHY, PROGRESSIVE MULTIFOCAL), and AIDS. Diseases produced by unconventional agents were originally considered part of this group. They are now called PRION DISEASES.
Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.
Naturally occurring or experimentally induced animal diseases with pathological processes sufficiently similar to those of human diseases. They are used as study models for human diseases.
A set of three nucleotides in a protein coding sequence that specifies individual amino acids or a termination signal (CODON, TERMINATOR). Most codons are universal, but some organisms do not produce the transfer RNAs (RNA, TRANSFER) complementary to all codons. These codons are referred to as unassigned codons (CODONS, NONSENSE).
A sulfated pentosyl polysaccharide with heparin-like properties.
Histochemical localization of immunoreactive substances using labeled antibodies as reagents.
Compounds containing carbohydrate or glycosyl groups linked to phosphatidylinositols. They anchor GPI-LINKED PROTEINS or polysaccharides to cell membranes.
The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species.
Loss of functional activity and trophic degeneration of nerve axons and their terminal arborizations following the destruction of their cells of origin or interruption of their continuity with these cells. The pathology is characteristic of neurodegenerative diseases. Often the process of nerve degeneration is studied in research on neuroanatomical localization and correlation of the neurophysiology of neural pathways.
Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.
The level of protein structure in which regular hydrogen-bond interactions within contiguous stretches of polypeptide chain give rise to alpha helices, beta strands (which align to form beta sheets) or other types of coils. This is the first folding level of protein conformation.
A sequential pattern of amino acids occurring more than once in the same protein sequence.
A common neoplasm of early childhood arising from neural crest cells in the sympathetic nervous system, and characterized by diverse clinical behavior, ranging from spontaneous remission to rapid metastatic progression and death. This tumor is the most common intraabdominal malignancy of childhood, but it may also arise from thorax, neck, or rarely occur in the central nervous system. Histologic features include uniform round cells with hyperchromatic nuclei arranged in nests and separated by fibrovascular septa. Neuroblastomas may be associated with the opsoclonus-myoclonus syndrome. (From DeVita et al., Cancer: Principles and Practice of Oncology, 5th ed, pp2099-2101; Curr Opin Oncol 1998 Jan;10(1):43-51)
The third type of glial cell, along with astrocytes and oligodendrocytes (which together form the macroglia). Microglia vary in appearance depending on developmental stage, functional state, and anatomical location; subtype terms include ramified, perivascular, ameboid, resting, and activated. Microglia clearly are capable of phagocytosis and play an important role in a wide spectrum of neuropathologies. They have also been suggested to act in several other roles including in secretion (e.g., of cytokines and neural growth factors), in immunological processing (e.g., antigen presentation), and in central nervous system development and remodeling.
The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
Elements of limited time intervals, contributing to particular results or situations.
Proteins prepared by recombinant DNA technology.
The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.
A change from planar to elliptic polarization when an initially plane-polarized light wave traverses an optically active medium. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
The chemical or biochemical addition of carbohydrate or glycosyl groups to other chemicals, especially peptides or proteins. Glycosyl transferases are used in this biochemical reaction.

Effectiveness of polyene antibiotics in treatment of transmissible spongiform encephalopathy in transgenic mice expressing Syrian hamster PrP only in neurons. (1/996)

To date very few drugs have favorably influenced the course of transmissible spongiform encephalopathies. In previous studies, the polyene antibiotics amphotericin B (AmB) and MS-8209 prolonged the incubation time in Syrian hamsters of the 263K strain of scrapie, but AmB had no effect against other scrapie strains in Syrian hamsters. In the present experiments using transgenic mice expressing Syrian hamster PrP in neurons only, MS-8209 extended the life spans of animals infected with the 263K strain but not the DY strain. AmB was effective against both 263K and DY and prevented death in 18% of DY-infected animals. The AmB effect against strain 263K was more prominent in mice whose endogenous PrP gene had been inactivated by homologous recombination. It was unclear whether this difference was due to a change in the duration of the disease or to possible interactive effects between the mouse PrP gene and the drugs themselves. The effectiveness of treatment after intracerebral scrapie infection in transgenic mice expressing PrP only in neurons suggested that neurons are important sites of action for these drugs.  (+info)

Modelling charge interactions in the prion protein: predictions for pathogenesis. (2/996)

Calculations are presented for the pH-dependence of stability and membrane charge complementarity of prion protein fragments. The theoretical results are compared with reported characterisations of prion protein folding in vitro. Discussion of models for conformational change and pathogenesis in vivo leads to the prediction of amino acids that could mediate sensitivity to the endosomal pH and to a design strategy for recombinant prion proteins with an increased susceptibility to prion proteinSc-like properties in vitro. In this model, the protective effect of certain basic polymorphisms can be interpreted in terms of oligomerisation on a negatively-charged surface.  (+info)

Brain injury does not modify transmissible spongiform encephalopathy caused by intraperitoneal inoculation with Fukuoka-1 strain. (3/996)

The pathogenesis of neuroinvasion in Creutzfeldt-Jakob disease and other transmissible spongiform encephalopathies following the peripheral uptake of a disease agent is still not fully understood. The possibility of neuroinvasion either being established or being accelerated by an insult to the brain has not previously been tested. The experiment described herein was designed to examine this possibility by wounding the brain following an intraperitoneal challenge with a mouse-adapted strain of human transmissible spongiform encephalopathy, Fukuoka-1 strain. The results showed that brain injury introduced in any period before the appearance of cerebral abnormal prion protein deposition modified neither the clinical features, including the incubation period, nor the histopathology of the mice. Our findings suggest that neurovirulence of the agent may not be sufficiently promoted by brain injury.  (+info)

Fatal familial insomnia: clinical features and molecular genetics. (4/996)

Fatal familial insomnia (FFI) is an autosomal dominant prion disease clinically characterized by inattention, sleep loss, dysautonomia, and motor signs and pathologically characterized by a preferential thalamic degeneration. FFI is linked to a missense mutation at codon 178 of the prion protein gene, PRNP, coupled with the presence of the codon methionine at position 129, the locus of a methionine-valine polymorphism. Homozygotes at codon 129, expressing methionine also in the nonmutated allele, have a shorter disease course (often less than 1 year), prominent sleep and autonomic disturbances at disease onset, and pathology restricted to the thalamus. Heterozygotes at codon 129, expressing valine in the nonmutated allele, have a longer disease course (often longer than 1 year), ataxia and dysarthria at disease onset, and lesions widespread to cerebral cortex. Both in the thalamus and in the cortex, the limbic structures are those most consistently and severely involved: the anterior ventral and mediodorsal thalamic nuclei, the cingulate gyrus, and the orbitofrontal cortex. FFI is thus a prion disease selectively damaging the thalamocortical limbic structures. Loss of sleep, sympathetic hyperactivity, and flattening of vegetative and hormonal circadian oscillations characterize FFI and result from a homeostatic imbalance caused by the interruption of the thalamocortical limbic circuits, the phylogenetically most advanced structures involved in the control of the sleep-wake cycle and the body's homeostasis. The selective atrophy of the limbic thalamus that characterizes FFI might be due to the binding of FFI toxic PrP or PrPres to specific receptors on thalamolimbic neurons.  (+info)

Cellular biology of prion diseases. (5/996)

Prion diseases are fatal neurodegenerative disorders of humans and animals that are important because of their impact on public health and because they exemplify a novel mechanism of infectivity and biological information transfer. These diseases are caused by conformational conversion of a normal host glycoprotein (PrPC) into an infectious isoform (PrPSc) that is devoid of nucleic acid. This review focuses on the current understanding of prion diseases at the cell biological level. The characteristics of the diseases are introduced, and a brief history and description of the prion hypothesis are given. Information is then presented about the structure, expression, biosynthesis, and possible function of PrPC, as well as its posttranslational processing, cellular localization, and trafficking. The latest findings concerning PrPSc are then discussed, including cell culture systems used to generate this pathogenic isoform, the subcellular distribution of the protein, its membrane attachment, proteolytic processing, and its kinetics and sites of synthesis. Information is also provided on molecular models of the PrPC-->PrPSc conversion reaction and the possible role of cellular chaperones. The review concludes with suggestions of several important avenues for future investigation.  (+info)

Sphingolipid depletion increases formation of the scrapie prion protein in neuroblastoma cells infected with prions. (6/996)

Sphingolipid-rich rafts play an essential role in the posttranslational (Borchelt, D. R., Scott, M., Taraboulos, A., Stahl, N., and Prusiner, S. B. (1990) J. Cell Biol. 110, 743-752)) formation of the scrapie prion protein PrP(Sc) from its normal conformer PrP(C) (Taraboulos, A., Scott, M., Semenov, A., Avrahami, D., Laszlo, L., Prusiner, S. B., and Avraham, D. (1995) J. Cell Biol. 129, 121-132). We investigated the importance of sphingolipids in the metabolism of the PrP isoforms in scrapie-infected ScN2a cells. The ceramide synthase inhibitor fumonisin B(1) (FB(1)) reduced both sphingomyelin (SM) and ganglioside GM1 in cells by up to 50%, whereas PrP(Sc) increased by 3-4-fold. Whereas FB(1) profoundly altered the cell lipid composition, the raft residents PrP(C), PrP(Sc), caveolin 1, and GM1 remained insoluble in Triton X-100. Metabolic radiolabeling demonstrated that PrP(C) production was either unchanged or slightly reduced in FB(1)-treated cells, whereas PrP(Sc) formation was augmented by 3-4-fold. To identify the sphingolipid species the decrease of which correlates with increased PrP(Sc), we used two other reagents. When cells were incubated with sphingomyelinase for 3 days, SM levels decreased, GM1 was unaltered, and PrP(Sc) increased by 3-4-fold. In contrast, the glycosphingolipid inhibitor PDMP reduced PrP(Sc) while increasing SM. Thus, PrP(Sc) seems to correlate inversely with SM levels. The effects of SM depletion contrasted with those previously obtained with the cholesterol inhibitor lovastatin, which reduced PrP(Sc) and removed it from detergent-insoluble complexes.  (+info)

Host and transmissible spongiform encephalopathy agent strain control glycosylation of PrP. (7/996)

PrP is a host-encoded glycoprotein involved in the pathogenesis of transmissible spongiform encephalopathies (TSEs) or 'prion' diseases. The normal form of the protein (PrP(C)) is heavily but incompletely glycosylated; it shows structural diversity in three neuroanatomically distinct regions of the brain. No effect of TSE infection on PrP(C) glycosylation has been detected. TSE-specific forms of PrP (PrP(Sc)) vary in their degree of glycosylation according to strain of TSE infectious agent. PrP(Sc) also varies independently in the amount and pattern of glycosylation according to brain region. This diversity shows that the glycosylation of PrP is under both host- and TSE agent-specified control, probably within the biosynthetic pathway for protein N-glycosylation. These findings challenge assumptions that PrP(Sc) is formed from the normal, mature form of PrP(Sc) but are compatible with a model in which the glycosylation phenotype of PrP(Sc) is under the control of both host cellular factors and TSE agent-specified information.  (+info)

A receptor for infectious and cellular prion protein. (8/996)

Prions are an unconventional form of infectious agents composed only of protein and involved in transmissible spongiform encephalopathies in humans and animals. The infectious particle is composed by PrPsc which is an isoform of a normal cellular glycosyl-phosphatidylinositol (GPI) anchored protein, PrPc, of unknown function. The two proteins differ only in conformation, PrPc is composed of 40% alpha helix while PrPsc has 60% beta-sheet and 20% alpha helix structure. The infection mechanism is trigged by interaction of PrPsc with cellular prion protein causing conversion of the latter's conformation. Therefore, the infection spreads because new PrPsc molecules are generated exponentially from the normal PrPc. The accumulation of insoluble PrPsc is probably one of the events that lead to neuronal death. Conflicting data in the literature showed that PrPc internalization is mediated either by clathrin-coated pits or by caveolae-like membranous domains. However, both pathways seem to require a third protein (a receptor or a prion-binding protein) either to make the connection between the GPI-anchored molecule to clathrin or to convert PrPc into PrPsc. We have recently characterized a 66-kDa membrane receptor which binds PrPc in vitro and in vivo and mediates the neurotoxicity of a human prion peptide. Therefore, the receptor should have a role in the pathogenesis of prion-related diseases and in the normal cellular process. Further work is necessary to clarify the events triggered by the association of PrPc/PrPsc with the receptor.  (+info)

Prion diseases, also known as transmissible spongiform encephalopathies (TSEs), are a group of progressive neurodegenerative disorders that affect both humans and animals. They are unique in that they are caused by prions, which are misfolded proteins rather than infectious agents like bacteria or viruses. These abnormal prions can cause other normal proteins to misfold and accumulate in the brain, leading to brain damage and neurodegeneration.

Prion diseases can be sporadic, inherited, or acquired. Sporadic forms occur without a known cause and are the most common type. Inherited prion diseases are caused by mutations in the PRNP gene and are often associated with a family history of the disease. Acquired prion diseases can result from exposure to contaminated food (as in variant Creutzfeldt-Jakob disease), medical procedures (iatrogenic Creutzfeldt-Jakob disease), or inherited forms of the disease that cause abnormal prions to be secreted in body fluids (like kuru).

Common prion diseases in humans include:

1. Creutzfeldt-Jakob disease (CJD) - sporadic, inherited, and acquired forms
2. Variant Creutzfeldt-Jakob disease (vCJD) - acquired form linked to consumption of contaminated beef products
3. Gerstmann-Sträussler-Scheinker syndrome (GSS) - inherited form
4. Fatal familial insomnia (FFI) - inherited form
5. Kuru - an acquired form that occurred in a isolated tribe due to cannibalistic practices, now eradicated

Prion diseases are characterized by rapidly progressing dementia, neurological symptoms, and motor dysfunction. There is no known cure for these diseases, and they are universally fatal.

Prions are misfolded proteins that can induce other normal proteins to also adopt the misfolded shape, leading to the formation of aggregates. These abnormal prion protein aggregates are associated with a group of progressive neurodegenerative diseases known as transmissible spongiform encephalopathies (TSEs). Examples of TSEs include bovine spongiform encephalopathy (BSE or "mad cow disease") in cattle, variant Creutzfeldt-Jakob disease (vCJD) in humans, and scrapie in sheep. The misfolded prion proteins are resistant to degradation by proteases, which contributes to their accumulation and subsequent neuronal damage, ultimately resulting in spongiform degeneration of the brain and other neurological symptoms associated with TSEs.

PrP^Sc (prion protein scrapie) is a misfolded, abnormal conformational isoform of the prion protein (PrP), which is associated with a group of progressive neurodegenerative disorders known as transmissible spongiform encephalopathies (TSEs). These diseases affect both humans and animals and include conditions like bovine spongiform encephalopathy (BSE or "mad cow disease") in cattle, scrapie in sheep, and variant Creutzfeldt-Jakob disease (vCJD) in humans.

The PrP protein is a naturally occurring, normal cellular protein found primarily in the brain and central nervous system. It has a predominantly alpha-helical structure under physiological conditions. However, during the development of prion diseases, PrP^Sc forms through a conformational change where the alpha-helical regions are replaced by beta-sheet structures. This misfolded protein can aggregate and form amyloid fibrils, which deposit in various brain regions leading to neurodegeneration, spongiform changes, gliosis, and neuronal loss.

Importantly, PrP^Sc is thought to have self-propagating properties, as it can induce the conversion of normal PrP into more PrP^Sc through a process called seeded polymerization or templated misfolding. This mechanism is believed to underlie the infectious nature and transmissibility of prion diseases.

PrPc proteins, also known as cellular prion proteins, are a type of protein found on the surface of many types of cells in the body, including neurons in the brain. The normal function of PrPc proteins is not entirely clear, but they are believed to play a role in various physiological processes such as protecting nerve cells from damage, regulating metal ion homeostasis, and participating in cell signaling pathways.

PrPc proteins are composed of 253 amino acids and have a molecular weight of approximately 35 kDa. They contain a highly conserved domain called the prion protein domain (PRD), which is rich in alpha-helices and contains a copper-binding site. The PRD is necessary for the normal function of PrPc proteins, but it is also the region that undergoes conformational changes to form the abnormal, disease-associated form of the protein called PrPSc.

PrPSc proteins are misfolded and aggregated forms of PrPc proteins that are associated with a group of neurodegenerative diseases known as transmissible spongiform encephalopathies (TSEs), including bovine spongiform encephalopathy (BSE or "mad cow disease"), scrapie in sheep, and variant Creutzfeldt-Jakob disease (vCJD) in humans. The misfolded PrPSc proteins can cause other normal PrPc proteins to also misfold and aggregate, leading to the formation of amyloid fibrils that accumulate in the brain and cause neurodegeneration.

Creutzfeldt-Jakob syndrome (CJD) is a rare, degenerative, and fatal brain disorder. It is caused by an abnormal form of protein called prion that can cause normal proteins in the brain to fold into abnormal shapes and accumulate, leading to damage and death of brain cells.

The symptoms of CJD usually develop over a period of several months and include rapidly progressing dementia, memory loss, confusion, coordination problems, muscle stiffness, twitching, and shaking. Some people may also experience visual hallucinations, changes in personality, or depression.

There are three main types of CJD: sporadic, inherited, and acquired. Sporadic CJD is the most common form and accounts for about 85% of all cases. It occurs spontaneously with no known cause. Inherited CJD is caused by a genetic mutation that is passed down from parents to their children. Acquired CJD is caused by exposure to contaminated tissue or bodily fluids, such as through a medical procedure or eating contaminated beef (variant CJD).

There is no cure for Creutzfeldt-Jakob syndrome and it is fatal, usually within a year of onset of symptoms. Treatment focuses on managing the symptoms and making the patient as comfortable as possible.

Scrapie is a progressive, fatal, degenerative disease affecting the central nervous system of sheep and goats. It is one of the transmissible spongiform encephalopathies (TSEs), also known as prion diseases. The agent responsible for scrapie is thought to be an abnormal form of the prion protein, which can cause normal prion proteins in the brain to adopt the abnormal shape and accumulate, leading to brain damage and neurodegeneration.

Scrapie is characterized by several clinical signs, including changes in behavior, tremors, loss of coordination, itching, and excessive scraping of the fleece against hard surfaces, which gives the disease its name. The incubation period for scrapie can range from 2 to 5 years, and there is no known treatment or cure for the disease.

Scrapie is not considered a significant threat to human health, but it has served as a model for understanding other prion diseases, such as bovine spongiform encephalopathy (BSE) in cattle, which can cause variant Creutzfeldt-Jakob disease (vCJD) in humans.

Endopeptidase K is a type of enzyme that belongs to the family of peptidases, which are proteins that help break down other proteins into smaller molecules called peptides or individual amino acids. Specifically, endopeptidase K is an intracellular serine protease that cleaves peptide bonds within a protein's interior, rather than at its ends.

Endopeptidase K was initially identified as a component of the proteasome, a large protein complex found in the nucleus and cytoplasm of eukaryotic cells. The proteasome plays a critical role in regulating protein turnover and degrading damaged or misfolded proteins. Endopeptidase K is one of several enzymes that make up the proteasome's catalytic core, where it helps cleave proteins into smaller peptides for further processing and eventual destruction.

Endopeptidase K has also been found to be involved in other cellular processes, such as regulating the activity of certain signaling molecules and contributing to the immune response. However, its precise functions and substrates are still being studied and elucidated.

Fatal Familial Insomnia (FFI) is a rare, inherited prion disease characterized by progressive insomnia that leads to death, typically within a year of onset. It is caused by a mutation in the PRNP gene, which encodes the prion protein. The mutation results in an abnormal form of the prion protein that accumulates in the brain and causes damage to nerve cells.

The symptoms of FFI usually begin in middle age and include progressive insomnia, rapid weight loss, hallucinations, confusion, and eventually dementia. As the disease progresses, patients may experience muscle spasms, rigidity, and difficulty swallowing. There is no cure for FFI, and treatment is focused on managing symptoms and providing supportive care.

FFI is inherited in an autosomal dominant manner, meaning that a person has a 50% chance of inheriting the mutated gene from an affected parent. The disease affects both men and women and has been reported in families worldwide.

Gerstmann-Straussler-Scheinker disease (GSS) is a rare, inherited, progressive neurodegenerative disorder characterized by cerebellar ataxia, pyramidal signs, and distinctive histopathological features in the brain. It is caused by mutations in the PRNP gene, which encodes the prion protein. The disease is transmitted in an autosomal dominant pattern, meaning that a single copy of the mutated gene from either parent is sufficient to cause the disorder.

GSS typically begins in mid-adulthood and progresses over several years to a decade, leading to severe disability and death. The symptoms of GSS include cerebellar ataxia (difficulty with coordination and balance), pyramidal signs (stiffness, spasticity, and hyperreflexia in the limbs), and various other neurological features such as dementia, visual disturbances, and speech difficulties.

Histopathologically, GSS is characterized by the accumulation of abnormal prion protein aggregates in the brain, which can be detected using special staining techniques. These aggregates are thought to be responsible for the neurodegeneration and clinical symptoms of the disease. Currently, there is no cure for GSS and treatment is focused on managing the symptoms of the disorder.

Chronic wasting disease (CWD) is a progressive, fatal neurodegenerative disorder that affects members of the cervid family, including deer, elk, and moose. It is caused by prions, abnormally folded proteins that can cause other proteins in the brain to also misfold and accumulate, leading to brain damage and death.

CWD is characterized by several symptoms, including weight loss (wasting), excessive thirst and urination, listlessness, lack of coordination, and behavioral changes such as aggression or decreased social interaction. The disease is always fatal, with no known cure or vaccine available.

CWD is transmitted through direct contact with infected animals or contaminated environments, and it can persist in the environment for years. It is important to note that CWD has not been shown to infect humans, but public health officials recommend avoiding consumption of meat from infected animals as a precautionary measure.

Bovine spongiform encephalopathy (BSE), also known as "mad cow disease," is a progressive neurodegenerative disorder that affects cattle. It is caused by prions, which are misfolded proteins that can cause other proteins in the brain to also misfold and accumulate, leading to brain damage and degeneration. The disease is named for the sponge-like appearance of the brain tissue that results from this degenerative process.

BSE is a zoonotic disease, which means that it can be transmitted from animals to humans. In humans, BSE is known as variant Creutzfeldt-Jakob disease (vCJD) and is caused by consuming contaminated beef products. The symptoms of vCJD include rapidly progressing dementia, neurological symptoms such as muscle spasms and difficulty coordinating movements, and physical deterioration leading to death.

It's important to note that the use of certain growth promoters in cattle feed and the practice of feeding cattle meat and bone meal have been banned in many countries in order to prevent the spread of BSE. Additionally, strict controls on the inspection and testing of beef products have been implemented to ensure their safety.

Kuru is a rare, fatal neurological disorder that was identified in the Fore people of Papua New Guinea. It is primarily caused by an abnormal form of protein called prion and is transmitted through cannibalistic practices where infected human tissues are consumed. The disease is characterized by progressive deterioration of the brain, leading to symptoms such as tremors, difficulty coordinating movements, slurred speech, and uncontrollable laughter. There is currently no known cure for kuru, and it has become extremely rare due to the cessation of cannibalistic rituals in the affected population.

I apologize for any confusion, but "deer" is not a medical term. It is a common name used to refer to various species of hooved mammals belonging to the family Cervidae. If you have any questions about medical terminology or health-related topics, I would be happy to help answer them.

Amyloid is a term used in medicine to describe abnormally folded protein deposits that can accumulate in various tissues and organs of the body. These misfolded proteins can form aggregates known as amyloid fibrils, which have a characteristic beta-pleated sheet structure. Amyloid deposits can be composed of different types of proteins, depending on the specific disease associated with the deposit.

In some cases, amyloid deposits can cause damage to organs and tissues, leading to various clinical symptoms. Some examples of diseases associated with amyloidosis include Alzheimer's disease (where amyloid-beta protein accumulates in the brain), systemic amyloidosis (where amyloid fibrils deposit in various organs such as the heart, kidneys, and liver), and type 2 diabetes (where amyloid deposits form in the pancreas).

It's important to note that not all amyloid deposits are harmful or associated with disease. However, when they do cause problems, treatment typically involves managing the underlying condition that is leading to the abnormal protein accumulation.

The brain is the central organ of the nervous system, responsible for receiving and processing sensory information, regulating vital functions, and controlling behavior, movement, and cognition. It is divided into several distinct regions, each with specific functions:

1. Cerebrum: The largest part of the brain, responsible for higher cognitive functions such as thinking, learning, memory, language, and perception. It is divided into two hemispheres, each controlling the opposite side of the body.
2. Cerebellum: Located at the back of the brain, it is responsible for coordinating muscle movements, maintaining balance, and fine-tuning motor skills.
3. Brainstem: Connects the cerebrum and cerebellum to the spinal cord, controlling vital functions such as breathing, heart rate, and blood pressure. It also serves as a relay center for sensory information and motor commands between the brain and the rest of the body.
4. Diencephalon: A region that includes the thalamus (a major sensory relay station) and hypothalamus (regulates hormones, temperature, hunger, thirst, and sleep).
5. Limbic system: A group of structures involved in emotional processing, memory formation, and motivation, including the hippocampus, amygdala, and cingulate gyrus.

The brain is composed of billions of interconnected neurons that communicate through electrical and chemical signals. It is protected by the skull and surrounded by three layers of membranes called meninges, as well as cerebrospinal fluid that provides cushioning and nutrients.

The incubation period of an infectious disease is the time interval between when a person is infected with a pathogen and when they start showing symptoms of the disease. This period can vary widely depending on the specific type of infectious agent, ranging from just a few hours to several weeks or even months.

The incubation period is an important factor in understanding the epidemiology of infectious diseases, as it can influence the strategy for diagnosis, treatment, and prevention measures such as quarantine and contact tracing. It's also worth noting that not all infected individuals will develop symptoms, and some may still be able to transmit the infection to others during the incubation period or even after symptoms have resolved.

"Mesocricetus" is a genus of rodents, more commonly known as hamsters. It includes several species of hamsters that are native to various parts of Europe and Asia. The best-known member of this genus is the Syrian hamster, also known as the golden hamster or Mesocricetus auratus, which is a popular pet due to its small size and relatively easy care. These hamsters are burrowing animals and are typically solitary in the wild.

Protein folding is the process by which a protein molecule naturally folds into its three-dimensional structure, following the synthesis of its amino acid chain. This complex process is determined by the sequence and properties of the amino acids, as well as various environmental factors such as temperature, pH, and the presence of molecular chaperones. The final folded conformation of a protein is crucial for its proper function, as it enables the formation of specific interactions between different parts of the molecule, which in turn define its biological activity. Protein misfolding can lead to various diseases, including neurodegenerative disorders such as Alzheimer's and Parkinson's disease.

I apologize, but "sheep" is not a term that has a medical definition. It is a common animal with the scientific name Ovis aries. If you have any medical or health-related questions, I would be happy to try and help answer those for you.

Cricetinae is a subfamily of rodents that includes hamsters, gerbils, and relatives. These small mammals are characterized by having short limbs, compact bodies, and cheek pouches for storing food. They are native to various parts of the world, particularly in Europe, Asia, and Africa. Some species are popular pets due to their small size, easy care, and friendly nature. In a medical context, understanding the biology and behavior of Cricetinae species can be important for individuals who keep them as pets or for researchers studying their physiology.

Transgenic mice are genetically modified rodents that have incorporated foreign DNA (exogenous DNA) into their own genome. This is typically done through the use of recombinant DNA technology, where a specific gene or genetic sequence of interest is isolated and then introduced into the mouse embryo. The resulting transgenic mice can then express the protein encoded by the foreign gene, allowing researchers to study its function in a living organism.

The process of creating transgenic mice usually involves microinjecting the exogenous DNA into the pronucleus of a fertilized egg, which is then implanted into a surrogate mother. The offspring that result from this procedure are screened for the presence of the foreign DNA, and those that carry the desired genetic modification are used to establish a transgenic mouse line.

Transgenic mice have been widely used in biomedical research to model human diseases, study gene function, and test new therapies. They provide a valuable tool for understanding complex biological processes and developing new treatments for a variety of medical conditions.

Quinacrine is a medication that belongs to the class of drugs called antimalarials. It is primarily used in the treatment and prevention of malaria caused by Plasmodium falciparum and P. vivax parasites. Quinacrine works by inhibiting the growth of the malarial parasites in the red blood cells.

In addition to its antimalarial properties, quinacrine has been used off-label for various other medical conditions, including the treatment of rheumatoid arthritis and discoid lupus erythematosus (DLE), a type of skin lupus. However, its use in these conditions is not approved by regulatory authorities such as the US Food and Drug Administration (FDA) due to limited evidence and potential side effects.

Quinacrine has several known side effects, including gastrointestinal disturbances, skin rashes, headache, dizziness, and potential neuropsychiatric symptoms like depression, anxiety, or confusion. Long-term use of quinacrine may also lead to yellowing of the skin and eyes (known as quinacrine jaundice) and other eye-related issues. It is essential to consult a healthcare professional before starting quinacrine or any other medication for appropriate dosage, duration, and potential side effects.

PrP 27-30 protein is the protease-resistant core fragment of the prion protein (PrP), which is associated with transmissible spongiform encephalopathies (TSEs), also known as prion diseases. PrP is a normal cellular protein found in many tissues, including the brain, but in TSEs, it undergoes a conformational change and forms aggregates of an abnormal isoform called PrP scrapie (PrPSc). The PrP 27-30 fragment is resistant to protease digestion and has been used as a biochemical marker for prion diseases. It is typically detected in brain tissue from infected individuals or animals, and its presence is indicative of the accumulation of PrPSc in the central nervous system.

Proteostasis is the process by which cells regulate the proper functioning and folding of proteins within the body to maintain cellular homeostasis. A deficiency in proteostasis refers to an impairment in this regulatory process, leading to the accumulation of misfolded or aggregated proteins. This can result in various diseases, such as neurodegenerative disorders, cancer, and metabolic conditions.

Proteostasis deficiencies can occur due to genetic mutations, environmental factors, or aging, which can affect the function of protein quality control systems, including chaperones, the ubiquitin-proteasome system, and autophagy. These systems are responsible for recognizing and disposing of misfolded proteins, preventing their accumulation and subsequent toxicity.

In summary, proteostasis deficiencies refer to impairments in the regulation of protein homeostasis within cells, leading to the accumulation of misfolded or aggregated proteins and contributing to various diseases.

Neurodegenerative diseases are a group of disorders characterized by progressive and persistent loss of neuronal structure and function, often leading to cognitive decline, functional impairment, and ultimately death. These conditions are associated with the accumulation of abnormal protein aggregates, mitochondrial dysfunction, oxidative stress, chronic inflammation, and genetic mutations in the brain. Examples of neurodegenerative diseases include Alzheimer's disease, Parkinson's disease, Huntington's disease, Amyotrophic Lateral Sclerosis (ALS), and Spinal Muscular Atrophy (SMA). The underlying causes and mechanisms of these diseases are not fully understood, and there is currently no cure for most neurodegenerative disorders. Treatment typically focuses on managing symptoms and slowing disease progression.

Protein conformation refers to the specific three-dimensional shape that a protein molecule assumes due to the spatial arrangement of its constituent amino acid residues and their associated chemical groups. This complex structure is determined by several factors, including covalent bonds (disulfide bridges), hydrogen bonds, van der Waals forces, and ionic bonds, which help stabilize the protein's unique conformation.

Protein conformations can be broadly classified into two categories: primary, secondary, tertiary, and quaternary structures. The primary structure represents the linear sequence of amino acids in a polypeptide chain. The secondary structure arises from local interactions between adjacent amino acid residues, leading to the formation of recurring motifs such as α-helices and β-sheets. Tertiary structure refers to the overall three-dimensional folding pattern of a single polypeptide chain, while quaternary structure describes the spatial arrangement of multiple folded polypeptide chains (subunits) that interact to form a functional protein complex.

Understanding protein conformation is crucial for elucidating protein function, as the specific three-dimensional shape of a protein directly influences its ability to interact with other molecules, such as ligands, nucleic acids, or other proteins. Any alterations in protein conformation due to genetic mutations, environmental factors, or chemical modifications can lead to loss of function, misfolding, aggregation, and disease states like neurodegenerative disorders and cancer.

"Cattle" is a term used in the agricultural and veterinary fields to refer to domesticated animals of the genus *Bos*, primarily *Bos taurus* (European cattle) and *Bos indicus* (Zebu). These animals are often raised for meat, milk, leather, and labor. They are also known as bovines or cows (for females), bulls (intact males), and steers/bullocks (castrated males). However, in a strict medical definition, "cattle" does not apply to humans or other animals.

Bentonite is not a medical term, but a geological one. It refers to a type of clay that is composed primarily of montmorillonite, a soft phyllosilicate mineral. Bentonite has a wide range of uses, including as a binding agent in the manufacture of medicines, as an absorbent in cat litter and personal care products, and as a component in drilling muds and cement mixtures.

In medical contexts, bentonite is sometimes used as a bulk-forming laxative to treat constipation or irregularity. It works by absorbing water and increasing the size and weight of stool, which stimulates bowel movements. However, it's important to note that bentonite should only be used under the guidance of a healthcare professional, as it can interfere with the absorption of certain medications and may cause side effects such as bloating, gas, and diarrhea.

Follicular dendritic cells (FDCs) are a specialized type of dendritic cell that reside in the germinal centers of secondary lymphoid organs, such as the spleen, lymph nodes, and Peyer's patches. They play a critical role in the adaptive immune response by presenting antigens to B cells and helping to regulate their activation, differentiation, and survival.

FDCs are characterized by their extensive network of dendrites, which can trap and retain antigens on their surface for extended periods. They also express a variety of surface receptors that allow them to interact with other immune cells, including complement receptors, Fc receptors, and cytokine receptors.

FDCs are derived from mesenchymal stem cells and are distinct from classical dendritic cells, which are derived from hematopoietic stem cells. They are long-lived cells that can survive for months or even years in the body, making them important players in the maintenance of immune memory.

Overall, follicular dendritic cells play a critical role in the adaptive immune response by helping to regulate B cell activation and differentiation, and by contributing to the development of immune memory.

Ruminants are a category of hooved mammals that are known for their unique digestive system, which involves a process called rumination. This group includes animals such as cattle, deer, sheep, goats, and giraffes, among others. The digestive system of ruminants consists of a specialized stomach with multiple compartments (the rumen, reticulum, omasum, and abomasum).

Ruminants primarily consume plant-based diets, which are high in cellulose, a complex carbohydrate that is difficult for many animals to digest. In the rumen, microbes break down the cellulose into simpler compounds, producing volatile fatty acids (VFAs) that serve as a major energy source for ruminants. The animal then regurgitates the partially digested plant material (known as cud), chews it further to mix it with saliva and additional microbes, and swallows it again for further digestion in the rumen. This process of rumination allows ruminants to efficiently extract nutrients from their fibrous diets.

Brain chemistry refers to the chemical processes that occur within the brain, particularly those involving neurotransmitters, neuromodulators, and neuropeptides. These chemicals are responsible for transmitting signals between neurons (nerve cells) in the brain, allowing for various cognitive, emotional, and physical functions.

Neurotransmitters are chemical messengers that transmit signals across the synapse (the tiny gap between two neurons). Examples of neurotransmitters include dopamine, serotonin, norepinephrine, GABA (gamma-aminobutyric acid), and glutamate. Each neurotransmitter has a specific role in brain function, such as regulating mood, motivation, attention, memory, and movement.

Neuromodulators are chemicals that modify the effects of neurotransmitters on neurons. They can enhance or inhibit the transmission of signals between neurons, thereby modulating brain activity. Examples of neuromodulators include acetylcholine, histamine, and substance P.

Neuropeptides are small protein-like molecules that act as neurotransmitters or neuromodulators. They play a role in various physiological functions, such as pain perception, stress response, and reward processing. Examples of neuropeptides include endorphins, enkephalins, and oxytocin.

Abnormalities in brain chemistry can lead to various neurological and psychiatric conditions, such as depression, anxiety disorders, schizophrenia, Parkinson's disease, and Alzheimer's disease. Understanding brain chemistry is crucial for developing effective treatments for these conditions.

Western blotting is a laboratory technique used in molecular biology to detect and quantify specific proteins in a mixture of many different proteins. This technique is commonly used to confirm the expression of a protein of interest, determine its size, and investigate its post-translational modifications. The name "Western" blotting distinguishes this technique from Southern blotting (for DNA) and Northern blotting (for RNA).

The Western blotting procedure involves several steps:

1. Protein extraction: The sample containing the proteins of interest is first extracted, often by breaking open cells or tissues and using a buffer to extract the proteins.
2. Separation of proteins by electrophoresis: The extracted proteins are then separated based on their size by loading them onto a polyacrylamide gel and running an electric current through the gel (a process called sodium dodecyl sulfate-polyacrylamide gel electrophoresis or SDS-PAGE). This separates the proteins according to their molecular weight, with smaller proteins migrating faster than larger ones.
3. Transfer of proteins to a membrane: After separation, the proteins are transferred from the gel onto a nitrocellulose or polyvinylidene fluoride (PVDF) membrane using an electric current in a process called blotting. This creates a replica of the protein pattern on the gel but now immobilized on the membrane for further analysis.
4. Blocking: The membrane is then blocked with a blocking agent, such as non-fat dry milk or bovine serum albumin (BSA), to prevent non-specific binding of antibodies in subsequent steps.
5. Primary antibody incubation: A primary antibody that specifically recognizes the protein of interest is added and allowed to bind to its target protein on the membrane. This step may be performed at room temperature or 4°C overnight, depending on the antibody's properties.
6. Washing: The membrane is washed with a buffer to remove unbound primary antibodies.
7. Secondary antibody incubation: A secondary antibody that recognizes the primary antibody (often coupled to an enzyme or fluorophore) is added and allowed to bind to the primary antibody. This step may involve using a horseradish peroxidase (HRP)-conjugated or alkaline phosphatase (AP)-conjugated secondary antibody, depending on the detection method used later.
8. Washing: The membrane is washed again to remove unbound secondary antibodies.
9. Detection: A detection reagent is added to visualize the protein of interest by detecting the signal generated from the enzyme-conjugated or fluorophore-conjugated secondary antibody. This can be done using chemiluminescent, colorimetric, or fluorescent methods.
10. Analysis: The resulting image is analyzed to determine the presence and quantity of the protein of interest in the sample.

Western blotting is a powerful technique for identifying and quantifying specific proteins within complex mixtures. It can be used to study protein expression, post-translational modifications, protein-protein interactions, and more. However, it requires careful optimization and validation to ensure accurate and reproducible results.

Amyloidogenic proteins are misfolded proteins that can form amyloid fibrils, which are insoluble protein aggregates with a characteristic cross-beta sheet quaternary structure. These amyloid fibrils can accumulate in various tissues and organs, leading to the formation of amyloid deposits. The accumulation of amyloidogenic proteins and the resulting amyloid deposits have been associated with several neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, and Huntington's disease, as well as systemic amyloidoses.

In Alzheimer's disease, for example, the amyloidogenic protein is beta-amyloid, which is produced from the proteolytic processing of the amyloid precursor protein (APP). In Parkinson's disease, the amyloidogenic protein is alpha-synuclein, which forms the main component of Lewy bodies.

It's important to note that not all misfolded proteins are necessarily amyloidogenic, and not all amyloid fibrils are associated with disease. Some amyloid fibrils can have functional roles in normal physiological processes.

I'm sorry for any confusion, but "Libya" is not a medical term. It is a country located in North Africa, known officially as the "State of Libya." If you have any questions about medical terms or concepts, I would be happy to help answer those for you!

C57BL/6 (C57 Black 6) is an inbred strain of laboratory mouse that is widely used in biomedical research. The term "inbred" refers to a strain of animals where matings have been carried out between siblings or other closely related individuals for many generations, resulting in a population that is highly homozygous at most genetic loci.

The C57BL/6 strain was established in 1920 by crossing a female mouse from the dilute brown (DBA) strain with a male mouse from the black strain. The resulting offspring were then interbred for many generations to create the inbred C57BL/6 strain.

C57BL/6 mice are known for their robust health, longevity, and ease of handling, making them a popular choice for researchers. They have been used in a wide range of biomedical research areas, including studies of cancer, immunology, neuroscience, cardiovascular disease, and metabolism.

One of the most notable features of the C57BL/6 strain is its sensitivity to certain genetic modifications, such as the introduction of mutations that lead to obesity or impaired glucose tolerance. This has made it a valuable tool for studying the genetic basis of complex diseases and traits.

Overall, the C57BL/6 inbred mouse strain is an important model organism in biomedical research, providing a valuable resource for understanding the genetic and molecular mechanisms underlying human health and disease.

Neurons, also known as nerve cells or neurocytes, are specialized cells that constitute the basic unit of the nervous system. They are responsible for receiving, processing, and transmitting information and signals within the body. Neurons have three main parts: the dendrites, the cell body (soma), and the axon. The dendrites receive signals from other neurons or sensory receptors, while the axon transmits these signals to other neurons, muscles, or glands. The junction between two neurons is called a synapse, where neurotransmitters are released to transmit the signal across the gap (synaptic cleft) to the next neuron. Neurons vary in size, shape, and structure depending on their function and location within the nervous system.

Copper is a chemical element with the symbol Cu (from Latin: *cuprum*) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. Copper is found as a free element in nature, and it is also a constituent of many minerals such as chalcopyrite and bornite.

In the human body, copper is an essential trace element that plays a role in various physiological processes, including iron metabolism, energy production, antioxidant defense, and connective tissue synthesis. Copper is found in a variety of foods, such as shellfish, nuts, seeds, whole grains, and organ meats. The recommended daily intake of copper for adults is 900 micrograms (mcg) per day.

Copper deficiency can lead to anemia, neutropenia, impaired immune function, and abnormal bone development. Copper toxicity, on the other hand, can cause nausea, vomiting, abdominal pain, diarrhea, and in severe cases, liver damage and neurological symptoms. Therefore, it is important to maintain a balanced copper intake through diet and supplements if necessary.

Protein isoforms are different forms or variants of a protein that are produced from a single gene through the process of alternative splicing, where different exons (or parts of exons) are included in the mature mRNA molecule. This results in the production of multiple, slightly different proteins that share a common core structure but have distinct sequences and functions. Protein isoforms can also arise from genetic variations such as single nucleotide polymorphisms or mutations that alter the protein-coding sequence of a gene. These differences in protein sequence can affect the stability, localization, activity, or interaction partners of the protein isoform, leading to functional diversity and specialization within cells and organisms.

Slow virus diseases, also known as persistent viral infections or chronic viral infections, are characterized by a lengthy incubation period and a slow progression of symptoms. These viruses can remain dormant in the body for extended periods, sometimes even years, before they start causing damage to cells and tissues.

The term "slow virus" is somewhat misleading because it does not necessarily mean that the virus itself is slow-replicating. Instead, it refers to the fact that the disease progression is slow and can take a long time to manifest symptoms. The immune system may have difficulty recognizing and eliminating these viruses, allowing them to persist in the body and cause ongoing damage over time.

Examples of slow virus diseases include:

1. Progressive multifocal leukoencephalopathy (PML): A rare and serious brain infection caused by the JC virus that primarily affects people with weakened immune systems, such as those with HIV/AIDS or those taking immunosuppressive drugs.
2. Subacute sclerosing panencephalitis (SSPE): A progressive neurological disorder caused by a measles virus infection that has become persistent in the brain. It primarily affects children and young adults who had measles during their early childhood.
3. Kuru: A rare, fatal degenerative neurological disorder that was once prevalent among the Fore people of Papua New Guinea. It is caused by an infectious protein called a prion, which can be transmitted through cannibalistic practices.
4. Creutzfeldt-Jakob disease (CJD): A rare and fatal brain disorder caused by prions. There are several types of CJD, including sporadic, hereditary, and acquired forms. The acquired form is a slow virus disease that can be transmitted through contaminated surgical instruments or dura mater grafts.
5. Human T-lymphotropic virus type 1 (HTLV-1) infection: A retrovirus that can cause adult T-cell leukemia/lymphoma and a progressive neurological disorder called HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP).
6. Progressive multifocal leukoencephalopathy (PML): A rare, often fatal demyelinating disease of the central nervous system caused by the JC polyomavirus. It primarily affects individuals with weakened immune systems, such as those with HIV/AIDS or those receiving immunosuppressive therapy for organ transplantation.

A mutation is a permanent change in the DNA sequence of an organism's genome. Mutations can occur spontaneously or be caused by environmental factors such as exposure to radiation, chemicals, or viruses. They may have various effects on the organism, ranging from benign to harmful, depending on where they occur and whether they alter the function of essential proteins. In some cases, mutations can increase an individual's susceptibility to certain diseases or disorders, while in others, they may confer a survival advantage. Mutations are the driving force behind evolution, as they introduce new genetic variability into populations, which can then be acted upon by natural selection.

Animal disease models are specialized animals, typically rodents such as mice or rats, that have been genetically engineered or exposed to certain conditions to develop symptoms and physiological changes similar to those seen in human diseases. These models are used in medical research to study the pathophysiology of diseases, identify potential therapeutic targets, test drug efficacy and safety, and understand disease mechanisms.

The genetic modifications can include knockout or knock-in mutations, transgenic expression of specific genes, or RNA interference techniques. The animals may also be exposed to environmental factors such as chemicals, radiation, or infectious agents to induce the disease state.

Examples of animal disease models include:

1. Mouse models of cancer: Genetically engineered mice that develop various types of tumors, allowing researchers to study cancer initiation, progression, and metastasis.
2. Alzheimer's disease models: Transgenic mice expressing mutant human genes associated with Alzheimer's disease, which exhibit amyloid plaque formation and cognitive decline.
3. Diabetes models: Obese and diabetic mouse strains like the NOD (non-obese diabetic) or db/db mice, used to study the development of type 1 and type 2 diabetes, respectively.
4. Cardiovascular disease models: Atherosclerosis-prone mice, such as ApoE-deficient or LDLR-deficient mice, that develop plaque buildup in their arteries when fed a high-fat diet.
5. Inflammatory bowel disease models: Mice with genetic mutations affecting intestinal barrier function and immune response, such as IL-10 knockout or SAMP1/YitFc mice, which develop colitis.

Animal disease models are essential tools in preclinical research, but it is important to recognize their limitations. Differences between species can affect the translatability of results from animal studies to human patients. Therefore, researchers must carefully consider the choice of model and interpret findings cautiously when applying them to human diseases.

A codon is a sequence of three adjacent nucleotides in DNA or RNA that specifies the insertion of a particular amino acid during protein synthesis, or signals the beginning or end of translation. In DNA, these triplets are read during transcription to produce a complementary mRNA molecule, which is then translated into a polypeptide chain during translation. There are 64 possible codons in the standard genetic code, with 61 encoding for specific amino acids and three serving as stop codons that signal the termination of protein synthesis.

I'm sorry for any confusion, but "Pentosan Sulfuric Polyester" is not a recognized medical term or a substance used in medicine. It seems to be a non-existent term. You might have made a mistake while typing or it could be a specific chemical compound not related to medical field. If you meant "Pentosan Polysulfate," I can provide its definition:

Pentosan Polysulfate is a semi-synthetic drug with properties similar to heparin. It is used in the treatment of osteoarthritis and interstitial cystitis due to its anti-inflammatory and analgesic effects. The chemical structure consists of a polyanionic, polydisperse molecule made up of repeating pentosan units linked by sulfuric ester bonds.

Immunohistochemistry (IHC) is a technique used in pathology and laboratory medicine to identify specific proteins or antigens in tissue sections. It combines the principles of immunology and histology to detect the presence and location of these target molecules within cells and tissues. This technique utilizes antibodies that are specific to the protein or antigen of interest, which are then tagged with a detection system such as a chromogen or fluorophore. The stained tissue sections can be examined under a microscope, allowing for the visualization and analysis of the distribution and expression patterns of the target molecule in the context of the tissue architecture. Immunohistochemistry is widely used in diagnostic pathology to help identify various diseases, including cancer, infectious diseases, and immune-mediated disorders.

Glycosylphosphatidylinositols (GPIs) are complex glycolipids that are attached to the outer leaflet of the cell membrane. They play a role in anchoring proteins to the cell surface by serving as a post-translational modification site for certain proteins, known as GPI-anchored proteins.

The structure of GPIs consists of a core glycan backbone made up of three mannose and one glucosamine residue, which is linked to a phosphatidylinositol (PI) anchor via a glycosylphosphatidylinositol anchor addition site. The PI anchor is composed of a diacylglycerol moiety and a phosphatidylinositol headgroup.

GPIs are involved in various cellular processes, including signal transduction, protein targeting, and cell adhesion. They have also been implicated in several diseases, such as cancer and neurodegenerative disorders.

Species specificity is a term used in the field of biology, including medicine, to refer to the characteristic of a biological entity (such as a virus, bacterium, or other microorganism) that allows it to interact exclusively or preferentially with a particular species. This means that the biological entity has a strong affinity for, or is only able to infect, a specific host species.

For example, HIV is specifically adapted to infect human cells and does not typically infect other animal species. Similarly, some bacterial toxins are species-specific and can only affect certain types of animals or humans. This concept is important in understanding the transmission dynamics and host range of various pathogens, as well as in developing targeted therapies and vaccines.

Nerve degeneration, also known as neurodegeneration, is the progressive loss of structure and function of neurons, which can lead to cognitive decline, motor impairment, and various other symptoms. This process occurs due to a variety of factors, including genetics, environmental influences, and aging. It is a key feature in several neurological disorders such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and multiple sclerosis. The degeneration can affect any part of the nervous system, leading to different symptoms depending on the location and extent of the damage.

A peptide fragment is a short chain of amino acids that is derived from a larger peptide or protein through various biological or chemical processes. These fragments can result from the natural breakdown of proteins in the body during regular physiological processes, such as digestion, or they can be produced experimentally in a laboratory setting for research or therapeutic purposes.

Peptide fragments are often used in research to map the structure and function of larger peptides and proteins, as well as to study their interactions with other molecules. In some cases, peptide fragments may also have biological activity of their own and can be developed into drugs or diagnostic tools. For example, certain peptide fragments derived from hormones or neurotransmitters may bind to receptors in the body and mimic or block the effects of the full-length molecule.

Secondary protein structure refers to the local spatial arrangement of amino acid chains in a protein, typically described as regular repeating patterns held together by hydrogen bonds. The two most common types of secondary structures are the alpha-helix (α-helix) and the beta-pleated sheet (β-sheet). In an α-helix, the polypeptide chain twists around itself in a helical shape, with each backbone atom forming a hydrogen bond with the fourth amino acid residue along the chain. This forms a rigid rod-like structure that is resistant to bending or twisting forces. In β-sheets, adjacent segments of the polypeptide chain run parallel or antiparallel to each other and are connected by hydrogen bonds, forming a pleated sheet-like arrangement. These secondary structures provide the foundation for the formation of tertiary and quaternary protein structures, which determine the overall three-dimensional shape and function of the protein.

Amino acid repetitive sequences refer to patterns of amino acids that are repeated in a polypeptide chain. These repetitions can vary in length and can be composed of a single type of amino acid or a combination of different types. In some cases, expansions of these repetitive sequences can lead to the production of abnormal proteins that are associated with certain genetic disorders. The expansion of trinucleotide repeats that code for particular amino acids is one example of this phenomenon. These expansions can result in protein misfolding and aggregation, leading to neurodegenerative diseases such as Huntington's disease and spinocerebellar ataxias.

Neuroblastoma is defined as a type of cancer that develops from immature nerve cells found in the fetal or early postnatal period, called neuroblasts. It typically occurs in infants and young children, with around 90% of cases diagnosed before age five. The tumors often originate in the adrenal glands but can also arise in the neck, chest, abdomen, or spine. Neuroblastoma is characterized by its ability to spread (metastasize) to other parts of the body, including bones, bone marrow, lymph nodes, and skin. The severity and prognosis of neuroblastoma can vary widely, depending on factors such as the patient's age at diagnosis, stage of the disease, and specific genetic features of the tumor.

Microglia are a type of specialized immune cell found in the brain and spinal cord. They are part of the glial family, which provide support and protection to the neurons in the central nervous system (CNS). Microglia account for about 10-15% of all cells found in the CNS.

The primary role of microglia is to constantly survey their environment and eliminate any potentially harmful agents, such as pathogens, dead cells, or protein aggregates. They do this through a process called phagocytosis, where they engulf and digest foreign particles or cellular debris. In addition to their phagocytic function, microglia also release various cytokines, chemokines, and growth factors that help regulate the immune response in the CNS, promote neuronal survival, and contribute to synaptic plasticity.

Microglia can exist in different activation states depending on the nature of the stimuli they encounter. In a resting state, microglia have a small cell body with numerous branches that are constantly monitoring their surroundings. When activated by an injury, infection, or neurodegenerative process, microglia change their morphology and phenotype, retracting their processes and adopting an amoeboid shape to migrate towards the site of damage or inflammation. Based on the type of activation, microglia can release both pro-inflammatory and anti-inflammatory factors that contribute to either neuroprotection or neurotoxicity.

Dysregulation of microglial function has been implicated in several neurological disorders, including Alzheimer's disease, Parkinson's disease, multiple sclerosis, and Amyotrophic Lateral Sclerosis (ALS). Therefore, understanding the role of microglia in health and disease is crucial for developing novel therapeutic strategies to treat these conditions.

A phenotype is the physical or biochemical expression of an organism's genes, or the observable traits and characteristics resulting from the interaction of its genetic constitution (genotype) with environmental factors. These characteristics can include appearance, development, behavior, and resistance to disease, among others. Phenotypes can vary widely, even among individuals with identical genotypes, due to differences in environmental influences, gene expression, and genetic interactions.

Molecular sequence data refers to the specific arrangement of molecules, most commonly nucleotides in DNA or RNA, or amino acids in proteins, that make up a biological macromolecule. This data is generated through laboratory techniques such as sequencing, and provides information about the exact order of the constituent molecules. This data is crucial in various fields of biology, including genetics, evolution, and molecular biology, allowing for comparisons between different organisms, identification of genetic variations, and studies of gene function and regulation.

In the field of medicine, "time factors" refer to the duration of symptoms or time elapsed since the onset of a medical condition, which can have significant implications for diagnosis and treatment. Understanding time factors is crucial in determining the progression of a disease, evaluating the effectiveness of treatments, and making critical decisions regarding patient care.

For example, in stroke management, "time is brain," meaning that rapid intervention within a specific time frame (usually within 4.5 hours) is essential to administering tissue plasminogen activator (tPA), a clot-busting drug that can minimize brain damage and improve patient outcomes. Similarly, in trauma care, the "golden hour" concept emphasizes the importance of providing definitive care within the first 60 minutes after injury to increase survival rates and reduce morbidity.

Time factors also play a role in monitoring the progression of chronic conditions like diabetes or heart disease, where regular follow-ups and assessments help determine appropriate treatment adjustments and prevent complications. In infectious diseases, time factors are crucial for initiating antibiotic therapy and identifying potential outbreaks to control their spread.

Overall, "time factors" encompass the significance of recognizing and acting promptly in various medical scenarios to optimize patient outcomes and provide effective care.

Recombinant proteins are artificially created proteins produced through the use of recombinant DNA technology. This process involves combining DNA molecules from different sources to create a new set of genes that encode for a specific protein. The resulting recombinant protein can then be expressed, purified, and used for various applications in research, medicine, and industry.

Recombinant proteins are widely used in biomedical research to study protein function, structure, and interactions. They are also used in the development of diagnostic tests, vaccines, and therapeutic drugs. For example, recombinant insulin is a common treatment for diabetes, while recombinant human growth hormone is used to treat growth disorders.

The production of recombinant proteins typically involves the use of host cells, such as bacteria, yeast, or mammalian cells, which are engineered to express the desired protein. The host cells are transformed with a plasmid vector containing the gene of interest, along with regulatory elements that control its expression. Once the host cells are cultured and the protein is expressed, it can be purified using various chromatography techniques.

Overall, recombinant proteins have revolutionized many areas of biology and medicine, enabling researchers to study and manipulate proteins in ways that were previously impossible.

An amino acid sequence is the specific order of amino acids in a protein or peptide molecule, formed by the linking of the amino group (-NH2) of one amino acid to the carboxyl group (-COOH) of another amino acid through a peptide bond. The sequence is determined by the genetic code and is unique to each type of protein or peptide. It plays a crucial role in determining the three-dimensional structure and function of proteins.

Circular dichroism (CD) is a technique used in physics and chemistry to study the structure of molecules, particularly large biological molecules such as proteins and nucleic acids. It measures the difference in absorption of left-handed and right-handed circularly polarized light by a sample. This difference in absorption can provide information about the three-dimensional structure of the molecule, including its chirality or "handedness."

In more technical terms, CD is a form of spectroscopy that measures the differential absorption of left and right circularly polarized light as a function of wavelength. The CD signal is measured in units of millidegrees (mdeg) and can be positive or negative, depending on the type of chromophore and its orientation within the molecule.

CD spectra can provide valuable information about the secondary and tertiary structure of proteins, as well as the conformation of nucleic acids. For example, alpha-helical proteins typically exhibit a strong positive band near 190 nm and two negative bands at around 208 nm and 222 nm, while beta-sheet proteins show a strong positive band near 195 nm and two negative bands at around 217 nm and 175 nm.

CD spectroscopy is a powerful tool for studying the structural changes that occur in biological molecules under different conditions, such as temperature, pH, or the presence of ligands or other molecules. It can also be used to monitor the folding and unfolding of proteins, as well as the binding of drugs or other small molecules to their targets.

Glycosylation is the enzymatic process of adding a sugar group, or glycan, to a protein, lipid, or other organic molecule. This post-translational modification plays a crucial role in modulating various biological functions, such as protein stability, trafficking, and ligand binding. The structure and composition of the attached glycans can significantly influence the functional properties of the modified molecule, contributing to cell-cell recognition, signal transduction, and immune response regulation. Abnormal glycosylation patterns have been implicated in several disease states, including cancer, diabetes, and neurodegenerative disorders.

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