Pyruvate carboxylase

Pyruvate carboxylase (PC) is an enzyme of the ligase class that catalyzes the (depending on the species) irreversible carboxylation of pyruvate to form oxaloacetate (OAA).

Pyruvic acid

Pyruvic acid

Oxaloacetic acid

Oxaloacetic acid

It is an important anaplerotic reaction that creates oxaloacetate from pyruvate. The enzyme is a mitochondrial protein containing a biotin prosthetic group, requiring magnesium or manganese and acetyl CoA.

Pyruvate carboxylase was first discovered in 1959 at Western Reserve University by M. F. Utter and D. B. Keech. Since then it has been found in a wide variety of prokaryotes and eukaryotes including fungi, bacteria, plants, and animals. In mammals, PC plays a crucial role in gluconeogenesis and lipogenesis, in the biosynthesis of neurotransmitters, and in glucose-induced insulin secretion by pancreatic islets. Oxaloacetate produced by PC is an important intermediate, which is used in these biosynthetic pathways. In mammals, PC is expressed in a tissue-specific manner, with its activity found to be highest in the liver and kidney (gluconeogenic tissues), in adipose tissue and lactating mammary gland (lipogenic tissues), and in pancreatic islets. Activity is moderate in brain, heart and adrenal gland, and least in white blood cells and skin fibroblasts.

Pyruvate carboxylase deficiency

Pyruvate carboxylase deficiency is an inherited disorder that causes lactic acid and other potentially toxic compounds to accumulate in the blood. High levels of these substances can damage the body's organs and tissues, particularly in the nervous system. Pyruvate carboxylase deficiency is a rare condition, with an estimated incidence of 1 in 250,000 births worldwide. This disorder appears to be much more common in some Algonkian Indian tribes in eastern Canada.

Classification

Researchers have identified at least three types of pyruvate carboxylase deficiency, which are distinguished by the severity of their signs and symptoms.

Type A

Type A, which has been identified mostly in people from North America, has moderately severe symptoms that begin in infancy. Characteristic features include developmental delay and a buildup of lactic acid in the blood (lactic acidosis). Increased acidity in the blood can lead to vomiting, abdominal pain, extreme tiredness (fatigue), muscle weakness, and difficulty breathing. In some cases, episodes of lactic acidosis are triggered by an illness or periods without food. Children with pyruvate carboxylase deficiency type A typically survive only into early childhood.

Medical terminology

Medical terminology is language that is used to accurately describe the human body and associated components, conditions, processes and procedures in a science-based manner. . It is to be used in the medical and nursing fields. Suffixes are attached to the end of a word root to add meaning such as condition, disease process, or procedure.

In the process of creating medical terminology, certain rules of language apply. These rules are part of language mechanics called linguistics. So, when a term is developed, some logical process is applied. The word root is developed to include a vowel sound following the term to add a smoothing action to the sound of the word when applying a suffix. The result is the formation of a new term with a vowel attached (word root + vowel) called a combining form. In English, the most common vowel used in the formation of the combining form is the letter -o-, added to the word root.

Prefixes do not normally require further modification to be added to a word root because the prefix normally ends in a vowel or vowel sound, although in some cases they may assimilate slightly and an in- may change to im- or syn- to sym-.

Streaming media

Streaming media is multimedia that is constantly received by and presented to an end-user while being delivered by a provider. The verb "to stream" refers to the process of delivering media in this manner; the term refers to the delivery method of the medium, rather than the medium itself, and is an alternative to downloading.

A client media player can begin to play the data (such as a movie) before the entire file has been transmitted. Distinguishing delivery method from the media distributed applies specifically to telecommunications networks, as most of the delivery systems are either inherently streaming (e.g. radio, television) or inherently nonstreaming (e.g. books, video cassettes, audio CDs). For example, in the 1930s, elevator music was among the earliest popularly available streaming media; nowadays Internet television is a common form of streamed media. The term "streaming media" can apply to media other than video and audio such as live closed captioning, ticker tape, and real-time text, which are all considered "streaming text". The term "streaming" was first used in the early 1990s as a better description for video on demand on IP networks; at the time such video was usually referred to as "store and forward video", which was misleading nomenclature.