| molecular weight ratio | The sum of the atomic weight's of all the atoms constituting a molecule; the mass of a molecule relative to the mass of a standard atom, now 12C (taken as 12.000). Relative molecular mass (Mr) is the mass relative to the dalton and has no units. See: atomic weight. Synonym: molecular mass, molecular weight ratio, relative molecular mass. (05 Mar 2000) |
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| heparin, low-molecular-weight | <chemical> Heparin fractions with a molecular weight usually between 4000 and 6000 kD. These low-molecular-weight fractions are effective antithrombotic agents. Their administration reduces the risk of haemorrhage, they have a longer half-life, and their platelet interactions are reduced in comparison to unfractionated heparin. They also provide an effective prophylaxis against postoperative major pulmonary embolism. Pharmacological action: anticoagulant, fibrinolytic agent. (12 Dec 1998) |
| directed molecular evolution | Techniques used to produce molecules exhibiting properties that conform to the demands of the experimenter. (12 Dec 1998) |
| epidemiology, molecular | The application of molecular biology to the answering of epidemiological questions. The examination of patterns of changes in DNA to implicate particular carcinogens and the use of molecular markers to predict which individuals are at highest risk for a disease are common examples. (12 Dec 1998) |
| european molecular biology lab gene bank | <molecular biology> A large database of DNA sequence data in Heidelberg, Germany, compiled from international sources. It is the European equivalent to the Genbank DNA sequence databank in the United States of America. WWW: EMbase. (09 Oct 1997) |
| evolution, molecular | Evolution at the molecular level of DNA sequences and proteins. (rieger et al., glossary of genetics: classical and molecular, 5th ed) (12 Dec 1998) |
| kinetic molecular theory | <chemistry> This theory assumes that molecules must collide in order to react. The more collisions the more likely it is for a reaction to occur. However, depending on the conditions, only a small fraction of the collisions are effective in producing a reaction. There are several constraints. In order for a reaction to occur, bonds initially are broken, which requires energy. This energy depends on the type of the reaction and comes from the kinetic energies that the molecules possess before the collision. It is called the activation energy. Increasing the temperature increases the kinetic energies and more collisions will occur. In adition, at a higher temperature a greater number of the reacting molecules might possess an energy equal to or greater than the activation energy. However the molecules must also collide in a specific orientation, called the steric factor in order for a reaction to occur. A reaction will only be successful, if the collision has enough energy to be either equal to or greater than the activation energy and if the orientation of the collision allows for correct bond formation. These factors are in the Arrhenius equation: k = zp The rate constant k is proportional to the Arrhenius factor A. A is the product of the collision frequency z, and the steric factor p. The fraction of collisions with sufficient energy to produce a reaction are in the term of the equation. (09 Jan 1998) |
| kininogen, high-molecular-weight | A plasma protein, molecular weight of 110 kD, that normally exists in plasma in a 1:1 complex with prekallikrein. Hmwk is split by plasma kallikrein to produce bradykinin. The complex is a cofactor in the activation of coagulation factor xii. The product of this reaction, xiia, in turn activates prekallikrein to kallikrein. (12 Dec 1998) |
| kininogen, low-molecular-weight | A protein, molecular weight 50 kD, located in various normal tissues. Upon cleavage by kallikrein or other kallikreins, it forms kallidin. Kallidin, in turn, is converted into bradykinin. (12 Dec 1998) |
| adenoviruses, human | Species of the genus mastadenovirus, causing a wide range of diseases in humans. Infections are mostly asymptomatic, but can be associated with diseases of the respiratory, ocular, and gastrointestinal systems. (12 Dec 1998) |
| adenovirus infections, human | Respiratory and conjunctival infections caused by 33 identified serotypes of human adenoviruses. (12 Dec 1998) |
| antigens, human platelet | Human alloantigens expressed only on platelets, specifically on platelet membrane glycoproteins. These platelet-specific antigens are immunogenic and can result in pathological reactions to transfusion therapy. (12 Dec 1998) |
| bites, human | Bites inflicted by humans. (12 Dec 1998) |
| bonding, human-pet | The emotional attachment of individuals to pets. (12 Dec 1998) |
| packed human blood cells | Whole blood from which plasma has been removed; may be prepared any time during the dating period of the whole blood from which it is derived, but not later than six days after the blood has been drawn if separation of plasma and cell's is achieved by centrifugation. (05 Mar 2000) |