Thiostrepton is an antibiotic and antiproliferative agent that is derived from the bacterium Streptomyces azureus. It belongs to the family of thiostreptons, which are cyclic oligopeptides with unique structures and various biological activities. Thiostrepton has been used primarily in veterinary medicine for the treatment of infections caused by gram-positive bacteria, such as mastitis in cows.

In addition to its antibacterial properties, thiostrepton has also been found to have antiproliferative and proapoptotic effects on various cancer cells, including breast, ovarian, and colon cancer cells. These effects are thought to be mediated by the inhibition of protein synthesis and the regulation of gene expression. However, its use as a therapeutic agent in humans is still being investigated due to its potential toxicity and limited bioavailability.

It's worth noting that thiostrepton is not commonly used in clinical practice, and its medical definition is mainly related to its chemical structure, antibacterial properties, and potential anticancer effects.

Peptide Elongation Factor G is a term used in the field of molecular biology, specifically in the process of protein synthesis. It is a bacterial enzyme that plays a crucial role in the elongation stage of translation, which is the process by which genetic information encoded in messenger RNA (mRNA) is converted into a polypeptide chain or protein.

More specifically, Peptide Elongation Factor G (also known as EF-G or Translocase) is responsible for the translocation step during translation. After each amino acid is added to the growing peptide chain, the mRNA and tRNAs must move relative to the ribosome so that the next codon in the mRNA can be read. EF-G facilitates this movement by using energy from GTP hydrolysis to cause a conformational change in the ribosome, resulting in the translocation of the mRNA and tRNAs by one codon.

In summary, Peptide Elongation Factor G is a bacterial enzyme that plays an essential role in the elongation stage of protein synthesis by facilitating the movement of mRNA and tRNAs relative to the ribosome during translation.

23S Ribosomal RNA (rRNA) is a type of rRNA that is a component of the large ribosomal subunit in both prokaryotic and eukaryotic cells. In prokaryotes, the large ribosomal subunit contains 50S, which consists of 23S rRNA, 5S rRNA, and around 33 proteins. The 23S rRNA plays a crucial role in the decoding of mRNA during protein synthesis and also participates in the formation of the peptidyl transferase center, where peptide bonds are formed between amino acids.

The 23S rRNA is a long RNA molecule that contains both coding and non-coding regions. It has a complex secondary structure, which includes several domains and subdomains, as well as numerous stem-loop structures. These structures are important for the proper functioning of the ribosome during protein synthesis.

In addition to its role in protein synthesis, 23S rRNA has been used as a target for antibiotics that inhibit bacterial growth. For example, certain antibiotics bind to specific regions of the 23S rRNA and interfere with the function of the ribosome, thereby preventing bacterial protein synthesis and growth. However, because eukaryotic cells do not have a 23S rRNA equivalent, these antibiotics are generally not toxic to human cells.

Ribosomes are complex macromolecular structures composed of ribonucleic acid (RNA) and proteins that play a crucial role in protein synthesis within cells. They serve as the site for translation, where messenger RNA (mRNA) is translated into a specific sequence of amino acids to create a polypeptide chain, which eventually folds into a functional protein.

Ribosomes consist of two subunits: a smaller subunit and a larger subunit. These subunits are composed of ribosomal RNA (rRNA) molecules and proteins. In eukaryotic cells, the smaller subunit is denoted as the 40S subunit, while the larger subunit is referred to as the 60S subunit. In prokaryotic cells, these subunits are named the 30S and 50S subunits, respectively. The ribosome's overall structure resembles a "doughnut" or a "cotton reel," with grooves and binding sites for various factors involved in protein synthesis.

Ribosomes can be found floating freely within the cytoplasm of cells or attached to the endoplasmic reticulum (ER) membrane, forming part of the rough ER. Membrane-bound ribosomes are responsible for synthesizing proteins that will be transported across the ER and ultimately secreted from the cell or inserted into the membrane. In contrast, cytoplasmic ribosomes synthesize proteins destined for use within the cytoplasm or organelles.

In summary, ribosomes are essential components of cells that facilitate protein synthesis by translating mRNA into functional polypeptide chains. They can be found in various cellular locations and exist as either free-floating entities or membrane-bound structures.

Anti-bacterial agents, also known as antibiotics, are a type of medication used to treat infections caused by bacteria. These agents work by either killing the bacteria or inhibiting their growth and reproduction. There are several different classes of anti-bacterial agents, including penicillins, cephalosporins, fluoroquinolones, macrolides, and tetracyclines, among others. Each class of antibiotic has a specific mechanism of action and is used to treat certain types of bacterial infections. It's important to note that anti-bacterial agents are not effective against viral infections, such as the common cold or flu. Misuse and overuse of antibiotics can lead to antibiotic resistance, which is a significant global health concern.

Streptomyces is a genus of Gram-positive, aerobic, saprophytic bacteria that are widely distributed in soil, water, and decaying organic matter. They are known for their complex morphology, forming branching filaments called hyphae that can differentiate into long chains of spores.

Streptomyces species are particularly notable for their ability to produce a wide variety of bioactive secondary metabolites, including antibiotics, antifungals, and other therapeutic compounds. In fact, many important antibiotics such as streptomycin, neomycin, tetracycline, and erythromycin are derived from Streptomyces species.

Because of their industrial importance in the production of antibiotics and other bioactive compounds, Streptomyces have been extensively studied and are considered model organisms for the study of bacterial genetics, biochemistry, and ecology.

Viomycin is an antibiotic that belongs to the class of drugs known as aminoglycosides. It works by binding to bacterial ribosomes and interfering with protein synthesis, leading to bacterial cell death. Viomycin is primarily used to treat tuberculosis and other mycobacterial infections that are resistant to other antibiotics. However, its use is limited due to its potential toxicity to the kidneys and hearing.

Here's a medical definition of Viomycin from Stedman's Medical Dictionary:

"A crystalline, basic polypeptide antibiotic produced by certain strains of Streptomyces floridae var. violaceusniger; used in the treatment of tuberculosis and other mycobacterial infections."

Ribosomal proteins are a type of protein that play a crucial role in the structure and function of ribosomes, which are complex molecular machines found within all living cells. Ribosomes are responsible for translating messenger RNA (mRNA) into proteins during the process of protein synthesis.

Ribosomal proteins can be divided into two categories based on their location within the ribosome:

1. Large ribosomal subunit proteins: These proteins are associated with the larger of the two subunits of the ribosome, which is responsible for catalyzing peptide bond formation during protein synthesis.
2. Small ribosomal subunit proteins: These proteins are associated with the smaller of the two subunits of the ribosome, which is responsible for binding to the mRNA and decoding the genetic information it contains.

Ribosomal proteins have a variety of functions, including helping to stabilize the structure of the ribosome, assisting in the binding of substrates and cofactors necessary for protein synthesis, and regulating the activity of the ribosome. Mutations in ribosomal proteins can lead to a variety of human diseases, including developmental disorders, neurological conditions, and cancer.

Fusidic Acid is a steroid antibiotic, derived from the fungus Fusidium coccineum. It is primarily used to treat skin infections and other susceptible bacterial infections. It works by inhibiting bacterial protein synthesis. In medical terms, it can be defined as:

A triterpenoid antibiotic derived from the fungus Fusidium coccineum, used primarily to treat staphylococcal and streptococcal skin infections that are resistant to other antibiotics. It inhibits bacterial protein synthesis by binding to the bacterial elongation factor EF-G, preventing translocation of peptidyl tRNA from the A site to the P site on the ribosome.

It is important to note that resistance to fusidic acid can develop and its use should be reserved for infections caused by organisms known to be susceptible to it. It is not typically used as a first-line antibiotic, but rather as a secondary option when other treatments have failed or are contraindicated.

Puromycin is an antibiotic and antiviral protein synthesis inhibitor. It works by being incorporated into the growing peptide chain during translation, causing premature termination and release of the incomplete polypeptide. This results in the inhibition of protein synthesis and ultimately leads to cell death. In research, puromycin is often used as a selective agent in cell culture to kill cells that have not been transfected with a plasmid containing a resistance gene for puromycin.

An encyclopedia is a comprehensive reference work containing articles on various topics, usually arranged in alphabetical order. In the context of medicine, a medical encyclopedia is a collection of articles that provide information about a wide range of medical topics, including diseases and conditions, treatments, tests, procedures, and anatomy and physiology. Medical encyclopedias may be published in print or electronic formats and are often used as a starting point for researching medical topics. They can provide reliable and accurate information on medical subjects, making them useful resources for healthcare professionals, students, and patients alike. Some well-known examples of medical encyclopedias include the Merck Manual and the Stedman's Medical Dictionary.