Coronary Heart Disease
The
mechanism underlying the association between ABO blood group and CHD (Coronary
Health Disease) risk remain Unclear. However, several lines of evidence support
it potential cardiovascular effects. Several studies have reported that plasma
levels of factor viii vwf (von will
brand factor) complex in non-o individuals were 25% higher than in group O
individuals. The vwf has an important role in haemostatics and thrombosis by mediating
platelet adhesion to the vascular wall especially under high shear stress
conditions.
mechanism underlying the association between ABO blood group and CHD (Coronary
Health Disease) risk remain Unclear. However, several lines of evidence support
it potential cardiovascular effects. Several studies have reported that plasma
levels of factor viii vwf (von will
brand factor) complex in non-o individuals were 25% higher than in group O
individuals. The vwf has an important role in haemostatics and thrombosis by mediating
platelet adhesion to the vascular wall especially under high shear stress
conditions.
ABO blood
group has been associated with plasma lipid levels, in particular, the A blood
group has been noted to have higher levels of serum total cholesterol and low
density lipoprotein cholesterol
group has been associated with plasma lipid levels, in particular, the A blood
group has been noted to have higher levels of serum total cholesterol and low
density lipoprotein cholesterol
ABO blood group is associated with CHD risk
independent of other risk factor.
independent of other risk factor.
Vibro Cholera
Cholera
toxins (ctx) are the vibro cholera O1 and O139. Epidemiological studies
identified that individuals with blood group O (carrying the unmodified H
antigen) were more susceptible to severe cholera (cholera gravis) than other
individuals (Harris et al., 2005).
toxins (ctx) are the vibro cholera O1 and O139. Epidemiological studies
identified that individuals with blood group O (carrying the unmodified H
antigen) were more susceptible to severe cholera (cholera gravis) than other
individuals (Harris et al., 2005).
The blood group antigen is potentially misleading
as these antigens are also abundant in body fluids and tissues, such as the
gut, and therefore should rather be referred to as histo-blood group antigens’
(although we use the terms interchangeably). Of the ABH antigen, the H antigen
is the shortest and characterized by a terminal fucose residue, whereas the A
and B antigens each contain one additional saccharide residue- a terminal
2-N-acetyl galactosamine (Gal NAC) in the A antigen, or a terminal galactose
for the blood group B antigen.
as these antigens are also abundant in body fluids and tissues, such as the
gut, and therefore should rather be referred to as histo-blood group antigens’
(although we use the terms interchangeably). Of the ABH antigen, the H antigen
is the shortest and characterized by a terminal fucose residue, whereas the A
and B antigens each contain one additional saccharide residue- a terminal
2-N-acetyl galactosamine (Gal NAC) in the A antigen, or a terminal galactose
for the blood group B antigen.
The GALNAα3 residue characteristic of blood group A
antigens binds to the toxin via several hydrogen bonds, including one involving
its acetamido nitrogen. The blood group B antigen is characterized by a
terminal galatose residue and only differs from the A antigen at the
2-position, that is the acetamido group is replaced by a hydroxyl group. This
hydroxyl group should preserve most of the interactions with the toxin and
explains why the toxin does not discriminate notably between A and B epitopes.
The fucosyl residue if the H antigen, a precursor of the A and B antigens, is
also an important contributor to receptor recognition however, blood group H
determinants lack the entire terminal saccharide residue compared to blood
group A and B determinants, and would therefore be expected to have
significantly reduced binding affinities to cholera toxin. This is the reason
why the vaccine provided for this disease protect group A and B by binding to
their antigens leaving blood group O individuals comparatively less protected
because of their lack of antigen (Holmmer et
al., 2004).
antigens binds to the toxin via several hydrogen bonds, including one involving
its acetamido nitrogen. The blood group B antigen is characterized by a
terminal galatose residue and only differs from the A antigen at the
2-position, that is the acetamido group is replaced by a hydroxyl group. This
hydroxyl group should preserve most of the interactions with the toxin and
explains why the toxin does not discriminate notably between A and B epitopes.
The fucosyl residue if the H antigen, a precursor of the A and B antigens, is
also an important contributor to receptor recognition however, blood group H
determinants lack the entire terminal saccharide residue compared to blood
group A and B determinants, and would therefore be expected to have
significantly reduced binding affinities to cholera toxin. This is the reason
why the vaccine provided for this disease protect group A and B by binding to
their antigens leaving blood group O individuals comparatively less protected
because of their lack of antigen (Holmmer et
al., 2004).
Biological Implication of Blood Group Antigen
Binding Site
Binding Site
The
secretary diarrhoea typical of cholera infection originates from the human
small intestine where the cholera toxin binds to its primary receptor that is
the GMI, ganglioside. The gastrointestinal epithelium is extremely rich in glyco-conjugates
and express, in addition to GMI, glycolipids and glycoprotein’s that carry
blood group ABH antigens.
secretary diarrhoea typical of cholera infection originates from the human
small intestine where the cholera toxin binds to its primary receptor that is
the GMI, ganglioside. The gastrointestinal epithelium is extremely rich in glyco-conjugates
and express, in addition to GMI, glycolipids and glycoprotein’s that carry
blood group ABH antigens.
In individuals belonging to the secretor phenotype
(Ca 80% of the population), these blood group antigens are also present on the
mucus layer lining the epithelia cells. Hence, the blood group A, B or AB
individuals, the cholera toxin could potentially bind to blood group antigens
at the site of infection, reducing intoxication Via the GMI route. This could
help explain why people of blood group A, B, and AB phenotype experience milder
symptoms than individual only expressing the weaker-binding. H antigen i.e.
people with blood group O (Jansson et al.,
2010).
(Ca 80% of the population), these blood group antigens are also present on the
mucus layer lining the epithelia cells. Hence, the blood group A, B or AB
individuals, the cholera toxin could potentially bind to blood group antigens
at the site of infection, reducing intoxication Via the GMI route. This could
help explain why people of blood group A, B, and AB phenotype experience milder
symptoms than individual only expressing the weaker-binding. H antigen i.e.
people with blood group O (Jansson et al.,
2010).
Malaria Parasite
An
association between O blood group and lower resetting capacity has been
demonstrated. However, resetting capacities of blood group A, B or AB have
remained controversial on the erythrocyte surface, the A and B antigen are
tri-saccharides A, GalNACα1-3 (FUCα1-2) Gal1 β1 and B-Galα1-3 (Fucα1-2) Galβ1 respectively,
that are attached to different glycolipids and glycoprotein. An enzyme
glucotransferase is necessary for the production of A and B antigen. On the
other hand, blood group O carries a disaccharide H antigen (FUCα2Gal β1) due to
the absence of the enzyme glucotransferase variation in gene encoding functional
glucoteranferase have been associated with protection from severe Plasmodium
Falciparum malaria (Loscertales et al.,
2007).
association between O blood group and lower resetting capacity has been
demonstrated. However, resetting capacities of blood group A, B or AB have
remained controversial on the erythrocyte surface, the A and B antigen are
tri-saccharides A, GalNACα1-3 (FUCα1-2) Gal1 β1 and B-Galα1-3 (Fucα1-2) Galβ1 respectively,
that are attached to different glycolipids and glycoprotein. An enzyme
glucotransferase is necessary for the production of A and B antigen. On the
other hand, blood group O carries a disaccharide H antigen (FUCα2Gal β1) due to
the absence of the enzyme glucotransferase variation in gene encoding functional
glucoteranferase have been associated with protection from severe Plasmodium
Falciparum malaria (Loscertales et al.,
2007).
Trisaccharide of A and B blood group is presumed to
act as receptors and function as an important factor for resetting (Barragent
et 2000). However, RBCs of blood group O do not express trisaccharide and
resetting formed by infected O blood group RBCs are smaller and easily
disrupted compared to blood group A, B or AB (Rowe et al., 2007).
act as receptors and function as an important factor for resetting (Barragent
et 2000). However, RBCs of blood group O do not express trisaccharide and
resetting formed by infected O blood group RBCs are smaller and easily
disrupted compared to blood group A, B or AB (Rowe et al., 2007).
Non-O blood groups have a fourfold increase risk of
developing severe infection while O blood groups are significantly associated
with a decreased risk of severe malaria (Loscertales et al., 2007).
developing severe infection while O blood groups are significantly associated
with a decreased risk of severe malaria (Loscertales et al., 2007).
References
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