Poly C
Poly A
Poly I-C
Poly I
Polyribonucleotides
Poly U
Polynucleotides
Rutin
Deoxycytidine Monophosphate
Complement C9
Poly(ADP-ribose) Polymerases
Cytosine Nucleotides
Interferon Inducers
Encephalomyocarditis virus
Complement Membrane Attack Complex
Poly dA-dT
Poly(A)-Binding Proteins
Interferons
Poly Adenosine Diphosphate Ribose
Poly G
Enterovirus Infections
Poly T
Cations
Polydeoxyribonucleotides
Poly(A)-Binding Protein I
Polynucleotide Adenylyltransferase
Polyesters
Poly(A)-Binding Protein II
Polymers
Nucleoside Diphosphate Sugars
RNA, Messenger
Polyadenylation
Polyethylene Glycols
Action of partially thiolated polynucleotides on the DNA polymerase alpha from regenerating rat liver. (1/217)
The effects of partially thiolated polynucleotides on the DNA polymerase alpha from regenerating rat liver were investigated. The enzyme was isolated from the nuclear fraction essentially according to the method of Baril et al.; it was characterized as the alpha polymerase on the basis of its response to synthetic templates and its inhibition with N-ethylmaleimide. Although polycytidylic acid had no effect on the DNA polymerase alpha either as a template or as an inhibitor, partially thiolated polycytidylic acid (MPC) was found to be a potent inhibitor, its activity being directly related to its extent of thiolation (percentage of 5-mercaptocytidylate units in the polymer). In comparison, the DNA polymerase beta which was purified from normal rat liver nuclear fraction, was much less sensitive to inhibition by MPC. Analysis of the inhibition of the alpha polymerase by the method of Lineweaver and Burk showed that the inhibitory action of MPC was competitively reversible with the DNA template, but the binding of the 7.2%-thiolated MPC to the enzyme was much stronger than that of the template (Ki/Km less than 0.03). Polyuridylic acid as such showed some inhibitory activity which increased on partial thiolation, but the 8.4%-thiolated polyuridylic acid was less active than the 7.2% MPC. When MPC was annealed with polyinosinic acid, it lost 80% of its inhibitory activity in the double-stranded configuration. However, 1 to 2%-thiolated DNA isolates were significantly more potent inhibitors than were comparable (1.2%-thiolated) MPC and showed competitive reversibility with the unmodified (but "activated") DNA template. These results indicate that the inhibitory activities of partially thiolated polynucleotides depend not only on the percentage of 5-mercapto groups but also on the configuration, base composition, and other specific structural properties. (+info)Identifying the bicyclomycin binding domain through biochemical analysis of antibiotic-resistant rho proteins. (2/217)
Mutations M219K, S266A, and G337S in transcription termination factor Rho have been shown to confer resistance to the antibiotic bicyclomycin (BCM). All three His-tagged mutant Rho proteins exhibited similar Km values for ATP; however, the Vmax values at infinite ATP concentrations were one-fourth to one-third that for the His-tagged wild-type enzyme. BCM inhibition kinetics of poly(C)-dependent ATPase activity for the mutant proteins were non-competitive with respect to ATP (altering catalytic function but not ATP binding) and showed increased Ki values compared with His-tagged wild-type Rho. M219K and G337S exhibited increased ratios of poly(U)/poly(C)-stimulated ATPase activity and lower apparent Km values for ribo(C)10 in the poly(dC).ribo(C)10-dependent ATPase assay compared with His-tagged wild-type Rho. The S266A mutation did not show an increased poly(U)/poly(C) ATPase activity ratio and maintained approximately the same Km for ribo(C)10 in the poly(dC). ribo(C)10-dependent ATPase assay. The kinetic studies indicated that M219K and G337S altered the secondary RNA binding domain in Rho whereas the S266A mutation did not. Transcription termination assays for each mutant showed different patterns of Rho-terminated transcripts. Tyrosine substitution of Ser-266 led to BCM sensitivity intimating that an OH (hydroxyl) moiety at this position is needed for BCM (binding) inhibition. Our results suggest BCM binds to Rho at a site distinct from both the ATP and the primary RNA binding domains but close to the secondary RNA-binding (tracking) site and the ATP hydrolysis pocket. (+info)The formation of DNA interstrand cross-links by a novel bis-[Pt2Cl4(diminazene aceturate)2]Cl4.4H2O complex inhibits the B to Z transition. (3/217)
We present data demonstrating that the cytotoxic compound [Pt2Cl4(diminazene aceturate)2]Cl4.4H2O (Pt-berenil) circumvents cisplatin resistance in ovarian carcinoma cells. The analysis of the interaction of Pt-berenil with linear and supercoiled DNA indicates that this compound induces the formation of a large number of covalent interstrand cross-links on DNA and that this number is significantly higher than that produced by cis-diamminedichloroplatinum(II) (cis-DDP). Renaturation experiments, interstrand cross-link assays, and electron microscopy indicate that the kinetics of DNA interstrand cross-link formation caused by Pt-berenil binding is faster than that caused by cis-DDP at similar levels of platinum bound to DNA. Furthermore, the number of DNA interstrand cross-links in Pt-berenil-DNA complexes is influenced by supercoiling. Circular dichroism experiments show that Pt-berenil strongly inhibits the B-DNA-to-Z-DNA transition of poly(dG-m5 dC). poly(dG-m5dC) at salt concentrations (3 mM MgCl2) at which the native methylated polynucleotide readily adopts the Z-DNA conformation, which suggests that the induction of interstrand cross-links by Pt-berenil inhibits the Z-DNA transition. On the basis of these results, we propose that bis(platinum) compounds with structure similar to Pt-berenil may act as blockers of DNA conformational changes and may also display activity in cisplatin-resistant cells. (+info)Preferential degradation of polyadenylated and polyuridinylated RNAs by the bacterial exoribonuclease polynucleotide phosphorylase. (4/217)
Polyadenylation of mRNA has been shown to target the RNA molecule for rapid exonucleolytic degradation in bacteria. To elucidate the molecular mechanism governing this effect, we determined whether the Escherichia coli exoribonuclease polynucleotide phosphorylase (PNPase) preferably degrades polyadenylated RNA. When separately incubated with each molecule, isolated PNPase degraded polyadenylated and non-polyadenylated RNAs at similar rates. However, when the two molecules were mixed together, the polyadenylated RNA was degraded, whereas the non-polyadenylated RNA was stabilized. The same phenomenon was observed with polyuridinylated RNA. The poly(A) tail has to be located at the 3' end of the RNA, as the addition of several other nucleotides at the 3' end prevented competition for polyadenylated RNA. In RNA-binding experiments, E. coli PNPase bound to poly(A) and poly(U) sequences with much higher affinity than to poly(C) and poly(G). This high binding affinity defines poly(A) and poly(U) RNAs as preferential substrates for this enzyme. The high affinity of PNPase for polyadenylated RNA molecules may be part of the molecular mechanism by which polyadenylated RNA is preferentially degraded in bacterial cells. (+info)Kinetic and product distribution analysis of human eosinophil cationic protein indicates a subsite arrangement that favors exonuclease-type activity. (5/217)
With the use of a high yield prokaryotic expression system, large amounts of human eosinophil cationic protein (ECP) have been obtained. This has allowed a thorough kinetic study of the ribonuclease activity of this protein. The catalytic efficiencies for oligouridylic acids of the type (Up)nU>p, mononucleotides U>p and C>p, and dinucleoside monophosphates CpA, UpA, and UpG have been interpreted by the specific subsites distribution in ECP. The distribution of products derived from digestion of high molecular mass substrates, such as poly(U) and poly(C), by ECP was compared with that of RNase A. The characteristic cleavage pattern of polynucleotides by ECP suggests that an exonuclease-like mechanism is predominantly favored in comparison to the endonuclease catalytic mechanism of RNase A. Comparative molecular modeling with bovine pancreatic RNase A-substrate analog crystal complexes revealed important differences in the subsite structure, whereas the secondary phosphate-binding site (p2) is lacking, the secondary base subsite (B2) is severely impaired, and there are new interactions at the po, Bo, and p-1 sites, located upstream of the P-O-5' cleavable phosphodiester bond, that are not found in RNase A. The differences in the multisubsites structure could explain the reduced catalytic efficiency of ECP and the shift from an endonuclease to an exonuclease-type mechanism. (+info)The reaction mechanism of ribonuclease II and its interaction with nucleic acid secondary structures. (6/217)
Ribonuclease II is a processive 3'- to 5'-exoribonuclease in Escherichia coli with two binding sites: a catalytic site associated with the first few 3'-nucleotides and an anchor site binding nucleotides approximately 15 to 25 from the 3'-end. When RNase II degrades single-stranded helical poly(C), the enzyme-substrate complex dissociates at discrete intervals of 12 nucleotides. RNase II stalled at the last rC of single-stranded 3'-(rC)(n)(dC)(m) oligonucleotides. The more residues released, the faster the stalled complex dissociated and the less it inhibited RNase II activity, i.e. the enzyme-substrate association weakened progressively. Using phosphodiesterase I (PDE I) as a probe, a method was developed to identify cytidine residues in (32)P-oligonucleotides interacting with a protein. PAGE bands corresponding to nucleotides 1-6 from the 3'-end were consistent with interaction at the catalytic site, and following a gap, bands approximately 15 to 25 from the 3'-end, with anchor site association. Both 3' and 5' binding were necessary to maintain the complex. Of most significance, the original anchor site nucleotides remained fixed at the anchor site while the 3'-end was pulled, or threaded, through the catalytic site, i.e. the substrate did not 'slide' through the enzyme. DNA oligonucleotides with double-stranded stem-loops were good competitive inhibitors of RNase II. A 3'-single-stranded arm was essential, while optimal binding required both 5'- and 3'-arms. PDE I probing indicated that the nucleotides at the anchor site were specified by the spatial distance from the catalytic site, and on only one of the duplex strands. When degradation of a structured RNA paused or stopped, the RNase II-product commenced cycles of dissociation-reassociation. Duplex strand binding by RNase II made complex DNA or RNA structures accessible to degradation by other nucleases and further verified the PDE I footprinting method. (+info)Phase variation in Helicobacter pylori lipopolysaccharide due to changes in the lengths of poly(C) tracts in alpha3-fucosyltransferase genes. (7/217)
The lipopolysaccharide (LPS) of Helicobacter pylori expresses the Lewis x (Lex) and/or Ley antigen. We have shown previously that H. pylori LPS displays phase variation whereby an Lex-positive strain yields variants with different LPS serotypes, for example, Lex plus Ley or nonfucosylated polylactosamine. H. pylori has two alpha3-fucosyltransferase genes that both contain poly(C) tracts. We now demonstrate that these tracts can shorten or lengthen randomly, which results in reversible frameshifting and inactivation of the gene products. We provide genetic and serological evidence that this mechanism causes H. pylori LPS phase variation and demonstrate that the on or off status of alpha3-fucosyltransferase genes determines the LPS serotypes of phase variants and clinical isolates. The role of the alpha3-fucosyltransferase gene products in determining the LPS serotype was confirmed by structural-chemical analysis of alpha3-fucosyltransferase knockout mutants. The data also show that the two alpha3-fucosyltransferase genes code for enzymes with different fine specificities, and we propose the names futA and futB to designate the orthologs of the H. pylori 26695 alpha3-fucosyltransferase genes HP0379 and HP0651, respectively. The data also show that the alpha3-fucosylation precedes alpha2-fucosylation [corrected], an order of events opposite to that which prevails in mammals. Finally, the data provide an understanding at the molecular level of the mechanisms underlying LPS diversity in H. pylori, which may play an important role in adaptation to the host. (+info)The mechanism of ATP hydrolysis at the noncatalytic sites of the transcription termination factor Rho. (8/217)
Escherichia coli transcription termination factor rho is a hexamer with three catalytic subunits that turnover ATP at a fast rate and three noncatalytic subunits that turnover ATP at a relatively slow rate. The mechanism of the ATPase reaction at the noncatalytic sites was determined and was compared with the ATPase mechanism at the catalytic sites. A sequential mechanism for ATP binding or hydrolysis that was proposed for the catalytic sites was not observed at the noncatalytic sites. Pre-steady-state pulse-chase experiments showed that three ATPs were tightly bound to the noncatalytic sites and these were simultaneously hydrolyzed at a rate of 1.8 s(-1) at 18 degrees C. The apparent bimolecular rate constant for ATP binding was determined as 5.4 x 10(5) M(-1) s(-1) in the presence of poly(C) RNA. The ATP hydrolysis products dissociated from the noncatalytic sites at 0.02 s(-1). The hydrolysis of ATP at the noncatalytic sites was at least 130 times slower, and the overall ATPase turnover was 1500 times slower than that at the catalytic sites. These results from studies of the rho protein are likely to be general to hexameric helicases. We propose that the ATPase activity at the noncatalytic site is too slow to drive translocation of the protein on the nucleic acid or to provide energy for nucleic acid unwinding. (+info)I'm sorry for any confusion, but "Poly C" is not a widely recognized medical term or abbreviation in the field of medicine or biology. It might be a typographical error or a shorthand notation used in a specific context. If you could provide more context or clarify what you mean by "Poly C," I would be happy to help further.
"Poly A" is an abbreviation for "poly(A) tail" or "polyadenylation." It refers to the addition of multiple adenine (A) nucleotides to the 3' end of eukaryotic mRNA molecules during the process of transcription. This poly(A) tail plays a crucial role in various aspects of mRNA metabolism, including stability, transport, and translation. The length of the poly(A) tail can vary from around 50 to 250 nucleotides depending on the cell type and developmental stage.
Poly(I):C is a synthetic double-stranded RNA (dsRNA) molecule made up of polycytidylic acid (poly C) and polyinosinic acid (poly I), joined by a 1:1 ratio of their phosphodiester linkages. It is used in research as an immunostimulant, particularly to induce the production of interferons and other cytokines, and to activate immune cells such as natural killer (NK) cells, dendritic cells, and macrophages. Poly(I):C has been studied for its potential use in cancer immunotherapy and as a vaccine adjuvant. It can also induce innate antiviral responses and has been explored as an antiviral agent itself.
I'm sorry for any confusion, but "Poly I" is not a recognized medical term or abbreviation in the context of human diseases or conditions. It's possible that there might be a typo or misunderstanding in your query. If you intended to ask about a specific medical condition, medication, or concept, please provide the full and correct term so I can give you an accurate and helpful response.
Polyribonucleotides are long, chain-like molecules composed of multiple ribonucleotide monomers. Ribonucleotides themselves consist of a ribose sugar, a phosphate group, and one of the four nitrogenous bases: adenine (A), uracil (U), guanine (G), or cytosine (C). In polyribonucleotides, these ribonucleotide monomers are linked together by ester bonds between the phosphate group of one monomer and the ribose sugar of another.
These molecules play crucial roles in various biological processes, such as encoding genetic information, regulating gene expression, catalyzing chemical reactions, and serving as structural components within cells. Some examples of polyribonucleotides include messenger RNA (mRNA), ribosomal RNA (rRNA), transfer RNA (tRNA), and small nuclear RNA (snRNA).
In a medical context, polyribonucleotides may be used in therapeutic applications, such as gene therapy or vaccines. For instance, synthetic mRNAs can be designed to encode specific proteins, which can then be introduced into cells to stimulate the production of those proteins for various purposes, including immunization against infectious diseases or cancer treatment.
I'm sorry for any confusion, but "Poly U" is not a recognized medical term or abbreviation in the English language. It could potentially refer to Polytechnic University or Hong Kong Polytechnic University, but it does not have a specific medical connotation. If you have more context or information, I'd be happy to help further!
Polynucleotides are long, chain-like molecules composed of repeating units called nucleotides. Each nucleotide contains a sugar molecule (deoxyribose in DNA or ribose in RNA), a phosphate group, and a nitrogenous base (adenine, guanine, cytosine, thymine in DNA or adenine, guanine, uracil, cytosine in RNA). In DNA, the nucleotides are joined together by phosphodiester bonds between the sugar of one nucleotide and the phosphate group of the next, creating a double helix structure. In RNA, the nucleotides are also joined by phosphodiester bonds but form a single strand. Polynucleotides play crucial roles in storing and transmitting genetic information within cells.
Rutin is a flavonoid, a type of plant pigment that is found in various plants and foods including citrus fruits, buckwheat, and asparagus. It has antioxidant properties and is known to help strengthen blood vessels and reduce inflammation. In medical terms, rutin may be mentioned in the context of discussing treatments for conditions related to these effects, such as varicose veins or hemorrhoids. However, it's important to note that while rutin has potential health benefits, more research is needed to fully understand its effects and proper dosages.
Deoxycytidine monophosphate (dCMP) is a nucleotide that is a building block of DNA. It consists of the sugar deoxyribose, the base cytosine, and one phosphate group. Nucleotides like dCMP are linked together through the phosphate groups to form long chains of DNA. In this way, dCMP plays an essential role in the structure and function of DNA, including the storage and transmission of genetic information.
Complement C9 is a protein that plays a crucial role in the complement system, which is a part of the immune system that helps to eliminate pathogens and damaged cells from the body. Specifically, C9 is one of the components of the membrane attack complex (MAC), which is a protein structure that forms pores in the membranes of target cells, leading to their lysis or destruction.
When activated, C9 polymerizes and inserts itself into the cell membrane, forming a transmembrane pore that disrupts the membrane's integrity and causes the cell to lyse. This process is an essential part of the complement system's ability to destroy pathogens and clear damaged cells from the body.
Defects in the C9 gene can lead to a rare genetic disorder called complement component 9 deficiency, which is characterized by recurrent bacterial infections and immune complex-mediated diseases. Additionally, mutations in the C9 gene have been associated with an increased risk of age-related macular degeneration (AMD), a leading cause of blindness in older adults.
Cytosine nucleotides are the chemical units or building blocks that make up DNA and RNA, one of the four nitrogenous bases that form the rung of the DNA ladder. A cytosine nucleotide is composed of a cytosine base attached to a sugar molecule (deoxyribose in DNA and ribose in RNA) and at least one phosphate group. The sequence of these nucleotides determines the genetic information stored in an organism's genome. In particular, cytosine nucleotides pair with guanine nucleotides through hydrogen bonding to form base pairs that are held together by weak interactions. This pairing is specific and maintains the structure and integrity of the DNA molecule during replication and transcription.
Interferon inducers are substances or agents that stimulate the production of interferons, which are a type of signaling protein released by host cells in response to the presence of viruses, bacteria, parasites, or other pathogens. Interferons play a crucial role in the immune system's defense against infections by inhibiting viral replication and promoting the activation of immune cells.
Interferon inducers can be synthetic or natural compounds that activate specific signaling pathways in the cell leading to the production of interferons. Examples of interferon inducers include:
1. Double-stranded RNA (dsRNA) analogs, such as polyinosinic-polycytidylic acid (Poly I:C), which mimic viral RNA and activate Toll-like receptor 3 (TLR3) and retinoic acid-inducible gene I (RIG-I) pathways.
2. Small molecule activators of cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway, such as DMXAA and c-di-GMP, which activate the production of type I interferons in response to cytosolic DNA.
3. Protein kinase R (PKR) activators, such as dsRNA and certain viral proteins, which induce interferon production through the activation of PKR and eukaryotic initiation factor 2α (eIF2α).
4. Interferon regulatory factors (IRFs) activators, such as amycin and resveratrol, which directly activate IRFs leading to the induction of interferons.
Interferon inducers have potential therapeutic applications in the treatment of various diseases, including viral infections, cancer, and autoimmune disorders. However, their use is limited by potential side effects, such as inflammation and immune activation, which may lead to tissue damage and other adverse events.
Encephalomyocarditis virus (EMCV) is a single-stranded, positive-sense RNA virus belonging to the family Picornaviridae and the genus Cardiovirus. It is a pathogen that can infect a wide range of hosts, including humans, causing encephalomyocarditis, a disease characterized by inflammation of both the brain (encephalitis) and heart (myocarditis).
EMCV infection typically occurs through the ingestion of contaminated food or water. The virus primarily targets organs with high cell turnover rates, such as the brain and heart. Infection can lead to a variety of symptoms, including fever, muscle weakness, neurological disorders, and cardiac dysfunction.
While human cases of EMCV infection are relatively rare, outbreaks have been reported in certain parts of the world, particularly in areas with poor sanitation and hygiene. In addition, EMCV has been identified as a potential bioterrorism agent due to its high virulence and ability to cause severe disease in humans.
Prevention measures include practicing good hygiene and food safety habits, such as washing hands frequently, cooking meat thoroughly, and avoiding contact with potentially contaminated water sources. There is currently no specific treatment for EMCV infection, and management typically involves supportive care to address symptoms and prevent complications.
The Complement Membrane Attack Complex (MAC), also known as the Terminal Complement Complex (TCC), is a protein structure that forms in the final stages of the complement system's immune response. The complement system is a part of the innate immune system that helps to eliminate pathogens and damaged cells from the body.
The MAC is composed of several proteins, including C5b, C6, C7, C8, and multiple subunits of C9, which assemble on the surface of target cells. The formation of the MAC creates a pore-like structure in the cell membrane, leading to disruption of the membrane's integrity and ultimately causing cell lysis or damage.
The MAC plays an important role in the immune response by helping to eliminate pathogens that have evaded other immune defenses. However, uncontrolled activation of the complement system and formation of the MAC can also contribute to tissue damage and inflammation in various diseases, such as autoimmune disorders, age-related macular degeneration, and ischemia-reperfusion injury.
"Poly A-U" is not a standard medical term. However, in biochemistry and genetics, "poly A" and "poly U" refer to repeating sequences of adenine (A) or uracil (U) nucleotides in DNA or RNA molecules, respectively.
"Poly A" is a post-transcriptional modification that occurs in mRNA, where multiple adenine nucleotides are added to the 3' end of the transcript. This process is important for the stability and translation of mRNA in eukaryotic cells.
"Poly U," on the other hand, can be found in some RNA molecules such as in the 3' untranslated region (UTR) of certain mRNAs or in specific types of non-coding RNAs like U-rich small nuclear RNAs (snRNAs).
Therefore, "Poly A-U" may refer to alternating sequences of adenine and uracil nucleotides in a DNA or RNA molecule. However, it is essential to consider the context in which this term is used to provide an accurate interpretation.
"Poly dA-dT" is not a medical term, but rather a molecular biology term that refers to a synthetic double-stranded DNA molecule. It is composed of two complementary strands: one strand consists of repeated adenine (dA) nucleotides, while the other strand consists of repeated thymine (dT) nucleotides. The "poly" prefix indicates that multiple units of these nucleotides are linked together in a chain-like structure.
This type of synthetic DNA molecule is often used as a substrate for various molecular biology techniques, such as in vitro transcription or translation assays, where it serves as a template for the production of RNA or proteins. It can also be used to study the interactions between DNA and proteins, such as transcription factors, that bind specifically to certain nucleotide sequences.
Interferons (IFNs) are a group of signaling proteins made and released by host cells in response to the presence of pathogens such as viruses, bacteria, parasites, or tumor cells. They belong to the larger family of cytokines and are crucial for the innate immune system's defense against infections. Interferons exist in multiple forms, classified into three types: type I (alpha and beta), type II (gamma), and type III (lambda). These proteins play a significant role in modulating the immune response, inhibiting viral replication, regulating cell growth, and promoting apoptosis of infected cells. Interferons are used as therapeutic agents for various medical conditions, including certain viral infections, cancers, and autoimmune diseases.
Poly(ADP-ribose) (PAR) is not strictly referred to as "Poly Adenosine Diphosphate Ribose" in the medical or biochemical context, although the term ADP-ribose is a component of it. Poly(ADP-ribose) is a polymer of ADP-ribose units that are synthesized by enzymes called poly(ADP-ribose) polymerases (PARPs).
Poly(ADP-ribosyl)ation, the process of adding PAR polymers to target proteins, plays a crucial role in various cellular processes such as DNA repair, genomic stability, and cell death. In medical research, alterations in PAR metabolism have been implicated in several diseases, including cancer and neurodegenerative disorders. Therefore, understanding the function and regulation of poly(ADP-ribose) is of significant interest in biomedical sciences.
I'm sorry for any confusion, but "Poly G" does not have a specific medical definition. The term "poly" is a prefix in medicine that means many or multiple, and "G" could potentially refer to a variety of things (such as a genetic locus or a grade), but without more context it's impossible to provide an accurate medical definition for this term.
If you have a specific medical question or concern, I would be happy to try to help you with that. Please provide some additional context or clarify what you mean by "Poly G."
Enterovirus infections are viral illnesses caused by enteroviruses, which are a type of picornavirus. These viruses commonly infect the gastrointestinal tract and can cause a variety of symptoms depending on the specific type of enterovirus and the age and overall health of the infected individual.
There are over 100 different types of enteroviruses, including polioviruses, coxsackieviruses, echoviruses, and newer enteroviruses such as EV-D68 and EV-A71. Some enterovirus infections may be asymptomatic or cause only mild symptoms, while others can lead to more severe illnesses.
Common symptoms of enterovirus infections include fever, sore throat, runny nose, cough, muscle aches, and skin rashes. In some cases, enteroviruses can cause more serious complications such as meningitis (inflammation of the membranes surrounding the brain and spinal cord), encephalitis (inflammation of the brain), myocarditis (inflammation of the heart muscle), and paralysis.
Enterovirus infections are typically spread through close contact with an infected person, such as through respiratory droplets or fecal-oral transmission. They can also be spread through contaminated surfaces or objects. Preventive measures include good hygiene practices, such as washing hands frequently and avoiding close contact with sick individuals.
There are no specific antiviral treatments for enterovirus infections, and most cases resolve on their own within a few days to a week. However, severe cases may require hospitalization and supportive care, such as fluids and medication to manage symptoms. Prevention efforts include vaccination against poliovirus and surveillance for emerging enteroviruses.
Ribonucleases (RNases) are a group of enzymes that catalyze the degradation of ribonucleic acid (RNA) molecules by hydrolyzing the phosphodiester bonds. These enzymes play crucial roles in various biological processes, such as RNA processing, turnover, and quality control. They can be classified into several types based on their specificities, mechanisms, and cellular localizations.
Some common classes of ribonucleases include:
1. Endoribonucleases: These enzymes cleave RNA internally, at specific sequences or structural motifs. Examples include RNase A, which targets single-stranded RNA; RNase III, which cuts double-stranded RNA at specific stem-loop structures; and RNase T1, which recognizes and cuts unpaired guanosine residues in RNA molecules.
2. Exoribonucleases: These enzymes remove nucleotides from the ends of RNA molecules. They can be further divided into 5'-3' exoribonucleases, which degrade RNA starting from the 5' end, and 3'-5' exoribonucleases, which start at the 3' end. Examples include Xrn1, a 5'-3' exoribonuclease involved in mRNA decay; and Dis3/RRP6, a 3'-5' exoribonuclease that participates in ribosomal RNA processing and degradation.
3. Specific ribonucleases: These enzymes target specific RNA molecules or regions with high precision. For example, RNase P is responsible for cleaving the 5' leader sequence of precursor tRNAs (pre-tRNAs) during their maturation; and RNase MRP is involved in the processing of ribosomal RNA and mitochondrial RNA molecules.
Dysregulation or mutations in ribonucleases have been implicated in various human diseases, such as neurological disorders, cancer, and viral infections. Therefore, understanding their functions and mechanisms is crucial for developing novel therapeutic strategies.
I'm sorry for any confusion, but "Poly T" is not a standard medical term that I am aware of. It is possible that it could be an abbreviation or shorthand used in a specific context, such as a medical report or research study. If you have more information about where this term came from or how it is being used, I may be able to provide a more accurate and helpful response.
However, if "Poly T" is meant to refer to polycythemia vera, which is a type of blood cancer characterized by an overproduction of red blood cells, then here's the definition:
Polycythemia Vera (PV) is a myeloproliferative neoplasm (MPN), a type of blood cancer that affects the bone marrow. In PV, the body produces too many red blood cells, white blood cells, and platelets, leading to an increased risk of blood clots, enlargement of the spleen, and other complications. The exact cause of PV is not known, but it is thought to be related to genetic mutations that affect the regulation of cell growth and division in the bone marrow. Symptoms of PV can include fatigue, headache, dizziness, shortness of breath, and a bluish or reddish tint to the skin. Treatment for PV typically involves medications to reduce the production of blood cells, as well as regular monitoring to manage complications and prevent progression of the disease.
A cation is a type of ion, which is a charged particle, that has a positive charge. In chemistry and biology, cations are formed when a neutral atom loses one or more electrons during chemical reactions. The removal of electrons results in the atom having more protons than electrons, giving it a net positive charge.
Cations are important in many biological processes, including nerve impulse transmission, muscle contraction, and enzyme function. For example, sodium (Na+), potassium (K+), calcium (Ca2+), and magnesium (Mg2+) are all essential cations that play critical roles in various physiological functions.
In medical contexts, cations can also be relevant in the diagnosis and treatment of various conditions. For instance, abnormal levels of certain cations, such as potassium or calcium, can indicate specific diseases or disorders. Additionally, medications used to treat various conditions may work by altering cation concentrations or activity within the body.
I'm sorry for any confusion, but "Polydeoxyribonucleotides" is not a widely recognized or established medical term. It seems to be a made-up or very obscure term that combines "poly," meaning many, "deoxy," referring to the lack of a hydroxyl group at the 2' carbon position in the ribose sugar, and "ribonucleotides," which are the building blocks of RNA.
If you meant "Polydeoxynucleotides" instead, it would refer to long, synthetic chains of deoxynucleotides, which are the building blocks of DNA. These chains can be used in various biochemical and biological research applications, such as studying enzyme mechanisms or constructing genetic circuits.
Polynucleotide adenylyltransferase is not a medical term per se, but rather a biological term used to describe an enzyme that catalyzes the addition of adenine residues to the 3'-hydroxyl end of polynucleotides. In other words, these enzymes transfer AMP (adenosine monophosphate) molecules to the ends of DNA or RNA strands, creating a chain of adenine nucleotides.
One of the most well-known examples of this class of enzyme is terminal transferase, which is often used in research settings for various molecular biology techniques such as adding homopolymeric tails to DNA molecules. It's worth noting that while these enzymes have important applications in scientific research, they are not typically associated with medical diagnoses or treatments.
I'm sorry for any confusion, but "Polyesters" is not a medical term. It is a term used in materials science and textile industry to describe a type of synthetic fiber made from polymers characterized by the presence of ester groups in their main chain. If you have any questions related to medical terminology or concepts, I'd be happy to help with those instead!
In the context of medical definitions, polymers are large molecules composed of repeating subunits called monomers. These long chains of monomers can have various structures and properties, depending on the type of monomer units and how they are linked together. In medicine, polymers are used in a wide range of applications, including drug delivery systems, medical devices, and tissue engineering scaffolds. Some examples of polymers used in medicine include polyethylene, polypropylene, polystyrene, polyvinyl chloride (PVC), and biodegradable polymers such as polylactic acid (PLA) and polycaprolactone (PCL).
Polyglycolic acid (PGA) is a synthetic polymer of glycolic acid, which is commonly used in surgical sutures. It is a biodegradable material that degrades in the body through hydrolysis into glycolic acid, which can be metabolized and eliminated from the body. PGA sutures are often used for approximating tissue during surgical procedures due to their strength, handling properties, and predictable rate of absorption. The degradation time of PGA sutures is typically around 60-90 days, depending on factors such as the size and location of the suture.
Nucleoside diphosphate sugars (NDP-sugars) are essential activated sugars that play a crucial role in the biosynthesis of complex carbohydrates, such as glycoproteins and glycolipids. They consist of a sugar molecule linked to a nucleoside diphosphate, which is formed from a nucleotide by removal of one phosphate group.
NDP-sugars are created through the action of enzymes called nucleoside diphosphate sugars synthases or transferases, which transfer a sugar molecule from a donor to a nucleoside diphosphate, forming an NDP-sugar. The resulting NDP-sugar can then be used as a substrate for various glycosyltransferases that catalyze the addition of sugars to other molecules, such as proteins or lipids.
NDP-sugars are involved in many important biological processes, including cell signaling, protein targeting, and immune response. They also play a critical role in maintaining the structural integrity of cells and tissues.
Messenger RNA (mRNA) is a type of RNA (ribonucleic acid) that carries genetic information copied from DNA in the form of a series of three-base code "words," each of which specifies a particular amino acid. This information is used by the cell's machinery to construct proteins, a process known as translation. After being transcribed from DNA, mRNA travels out of the nucleus to the ribosomes in the cytoplasm where protein synthesis occurs. Once the protein has been synthesized, the mRNA may be degraded and recycled. Post-transcriptional modifications can also occur to mRNA, such as alternative splicing and addition of a 5' cap and a poly(A) tail, which can affect its stability, localization, and translation efficiency.
Polyadenylation is a post-transcriptional modification process in which a string of adenine (A) nucleotides, known as a poly(A) tail, is added to the 3' end of a newly transcribed eukaryotic mRNA molecule. This process is essential for the stability, export, and translation of the mRNA. The addition of the poly(A) tail is catalyzed by a complex containing several proteins and the enzyme poly(A) polymerase. The length of the poly(A) tail typically ranges from 50 to 250 nucleotides and can be shortened or lengthened in response to various cellular signals, which contributes to the regulation of gene expression.
Polyethylene glycols (PEGs) are a family of synthetic, water-soluble polymers with a wide range of molecular weights. They are commonly used in the medical field as excipients in pharmaceutical formulations due to their ability to improve drug solubility, stability, and bioavailability. PEGs can also be used as laxatives to treat constipation or as bowel cleansing agents prior to colonoscopy examinations. Additionally, some PEG-conjugated drugs have been developed for use in targeted cancer therapies.
In a medical context, PEGs are often referred to by their average molecular weight, such as PEG 300, PEG 400, PEG 1500, and so on. Higher molecular weight PEGs tend to be more viscous and have longer-lasting effects in the body.
It's worth noting that while PEGs are generally considered safe for use in medical applications, some people may experience allergic reactions or hypersensitivity to these compounds. Prolonged exposure to high molecular weight PEGs has also been linked to potential adverse effects, such as decreased fertility and developmental toxicity in animal studies. However, more research is needed to fully understand the long-term safety of PEGs in humans.
A base sequence in the context of molecular biology refers to the specific order of nucleotides in a DNA or RNA molecule. In DNA, these nucleotides are adenine (A), guanine (G), cytosine (C), and thymine (T). In RNA, uracil (U) takes the place of thymine. The base sequence contains genetic information that is transcribed into RNA and ultimately translated into proteins. It is the exact order of these bases that determines the genetic code and thus the function of the DNA or RNA molecule.