Universal donor

The possibility that the initial degree of methyl-esterification might be controlled by the properties of the methyltransferase enzymes was examined partial characterisation of these enzymes in suspension-cultured cells of fiax. Pectin methyltransferases beii enzymes characteristic of the Golgi apparatus [22], microsomes were fiactionated daily for ten days from suspension-cultured flax cells and incubated in the presence of C-SAM, the universal donor of methyl groups. 

Type O blood contains no antigens on the cell surface. In this case, any antibodies that the transfusion recipient may produce (anti-A or anti-B antibodies) have no antigens to attack. Therefore, no immune response against this blood exists. Individuals with type O blood are referred to as universal donors because this blood is suitable for transfusion in all individuals. 

At first glance the significance of these two terms seems to be obvious. A substituent which withdraws electron density is a captor and a substituent which donates electron density is a donor. However, both properties cannot be discussed independently from a partner from which they accept, or to which they donate, electrons. This raises the question of whether it is in principle possible to define a universal donor or acceptor character for a substituent. 

Our blood type is determined by a gene that is present on chromosome 9, near the end of the long arm. There are four general blood types A, AB, B, and O. Some of these are intermixable while others are not. For instance, A blood from a person is compatible with A and AB B with B and AB AB with only AB and O blood is compatible with all of the blood types—a person with type O is then a universal donor. These compatibility scenarios are not race-related. For all but the native Americans who have almost totally type O, the rest of us have about 40% type O another 40% type A 15% type B and 5% type AB. (Some of the Eskimos are type AB or B and some Canadian tribes are type A.) A and B are codominant versions of the same gene and O is the recessive form of this gene. 

If you have type-0 blood, then you re very popular with the local hospitals and blood banks, because you re a universal donor. Approximately 45 percent of the population has type-0 blood, 40 percent has type-A blood, 11 percent has type-B blood, and 4 percent has type-AB blood. Along with the four blood types in terms of letters, you are either RH+ or RH-. So, technically, there are eight different blood types 0+, 0-, A+, A-, B+, B-, AB+, and AB-. 

There are, however, several limitations and contraindications with MSC therapy. One of the limitations is in the establishment of MSC cultures from donors, parents or siblings. Although MSC can be readily isolated and expanded in vitro, establishing the MSC cultures can be a limiting factor. Failure to establish such cell cultures in a timely manner, and in sufficient qualities and quantities, may have profound consequences on the therapy. Since MHC compatibility is not necessary for MSC immunosuppression, and because MSC immunomodulatory activity can also be observed in third-party donor cells [656550], MSCs derived from unrelated, -unmatched, healthy, third-party donors would represent a universal donor MSC product with the advantage of being a readily-available product that may provide an opportunity for multiple and higher MSC doses, potentially at a reduced cost [659019 ]. 

This review discusses the need to develop a universal donor product for MSC therapy. Such... 

The role of carbohydrates in biological communication is well illustrated by the human blood types.a b According to the ABO system first described by Landsteiner in 1900, individuals are classified into types A, B, AB, and O. Blood of individuals of the same type can be mixed without clumping of cells, but serum from a type O individual contains antibodies that agglutinate erythrocytes of persons of types A and B. Serum of persons of type B causes type A cells to clump and vice versa. Individuals of none of the four types have antibodies against type O erythrocytes. For this reason, persons with type O blood are sometimes inaccurately described as "universal donors."... 

An analogy is found in biological systems in which 5-adenosylmethionine is a universal donor of methyl groups. 

Type 0 is called the "universal donor" because the cells have no antigen to provoke a deadly antigen-antibody reaction. If the other blood factors (Rh factor, for example) are compatible, type 0 can be donated to people with the other blood types. 

Red blood cells from type O individuals can be donated to individuals with any other cells from type within the ABO system without causing agglutination. Individuals with type AB can accept red blood cells from all other types but cannot donate to individuals with other types except AB. Thus, type O individuals are known as universal donors and AB as universal acceptors. 

People with type A blood also have antibodies against type B blood (anti-B antibodies) in the blood serum. If the person with type A blood receives a transfusion of type B blood, the anti-B antibodies bind to the type B blood cells, causing clumping and destruction of those cells that can result in death. Individuals with type B blood also produce anti-A antibodies and therefore cannot receive a transfusion from a type A individual. Those with type AB blood are considered to be universal recipients because they have neither anti-A nor anti-B antibodies in their blood. (If they did, they would destroy their own red blood cells ) Thus in emergency situations a patient with type AB blood can receive blood from an individual of any blood type without serious transfusion reactions. Type O blood has no A or B antigens on the RBC but has both anti-A and anti-B antibodies. Because of the presence of both types of antibodies, type O individuals can receive transfusions only from a person who is also type O. On the other hand, the absence of A and B antigens on the red blood cell surface means that type O blood can be safely transfused into patients of any blood type. Hence type O individuals are universal donors. 

Looking at Figure 22.5, we can see why the immune system of type A people recognizes type B blood as foreign and vice versa. The immune system of people with type A, B, or AB blood does not, however, recognize type O blood as foreign, because the carbohydrate in type O blood is also a component of types A, B, and AB blood. Thus, anyone can accept type O blood, so people with type O blood are called universal donors. Type AB people can accept types AB, A, B, and O blood, so people with type AB blood are referred to as universal acceptors. 

Look at Figure 11.17 in the text, which shows the structures of the A, B, and O blood antigens. Based on the structures of the three antigens, can you suggest why type O blood is the universal donor and can be transfused into people with type A or type B without provoking an immune response ... 

The O allele has undergone a mutation causing a phase shift, and produces no active enzyme. The red blood cells of type O individuals contain neither the A nor the B antigen. This is why people with type O blood are universal donors in blood transfusions. The loss of activity of the protein does not seem to carry any adverse consequences. 

To demonstrate the power of this systan, 14 optimized modules from 8 different PKS clusters were prepared, and these modules were combined in 154 bimodular combinations. Ronarkably, 72 out of the 154 combinations produced the corresponding triketide lactone (see Figure 4.6a). This screen revealed a universal donor module, a highly promiscuous TE module and, importantly, a generic intermodular linker that was always present in aU the productive combinations. 

A person with type A blood makes antibodies that attack type B blood, forming clumps of type B cells. Similarly, a person with type B blood makes antibodies that attack type A blood, forming clumps of type A cells. However, a person with type A or type B blood does not make antibodies to type O blood. Thus, type O persons are called universal donors. They are not, however, universal acceptors because they produce antibodies to both type A and type B blood. 

Because type O blood has only the three common terminal monosaccharides, a person with type O produces antibodies against blood types A, B, and AB. However, persons with blood types A, B, and AB can receive type O blood. Thus, persons with type O blood are universal donors. Because type AB blood contains all the terminal monosaccharides, a person with type AB blood produces no antibodies to... 

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