Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.4.99.7 (sialyltransferase)
 1,534 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A reliable antemortem serum marker for Alzheimer's disease (AD) would be of great importance for the early detection and subsequent therapeutic management of the disease. We have noted a significant decrease in serum levels of the soluble form of the sialyltransferase enzyme in a group of AD patients when compared with both age-matched elderly (over 60 years) and young (under 60 years) controls. In a population of Down's syndrome patients, who develop AD pathology with increasing age, there was an age-related decrease in serum sialyltransferase activity in patients from 20 to 60 years to approach enzyme levels similar to those observed in the AD group. This significant decrease in serum sialyltransferase levels observed may both prove a useful peripheral early biochemical marker of neurodegeneration and provide an indication of the underlying cellular events that occur during the process of nerve cell death in AD.
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PMID:A decrease in serum sialyltransferase levels in Alzheimer's disease. 815 68

Human chorionic gonadotrophin (hCG) has been used as a serum biochemical marker of Down's syndrome (DS) pregnancies, and recent studies have reported an increase in a hyperglycosylated form of the protein associated with DS. In the present study, the activity of the combined soluble serum sialyltransferase (ST) enzymes was examined as a potential marker for the hyperglycosylated form of hCG. There were no changes in total ST activity during the course of the pregnancy in normal mothers and there was no difference in enzyme activity in the DS pregnancies when compared with controls. These results suggest that, although there may be an alteration in the activities of one or more of the glycosyltransferase enzymes in the placenta resulting in an alteration in hCG glycosylation, this is not reflected in the serum soluble enzyme activity.
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PMID:Serum expression of sialyltransferase in normal and Down's syndrome-affected pregnancy. 1090 68

Total human chorionic gonadotropin (hCG) is high in maternal serum at 14-18 wk of trisomy 21 (T21)-affected pregnancy, despite low placental hCG synthesis. We sought an explanation for this paradox. We first observed that, in T21-affected pregnancies, maternal serum hCG levels peaked at around 10 wk and then followed the same pattern throughout pregnancy as in controls, albeit at a higher (2.2-fold) level. After delivery, hCG clearance was not significantly different from that in controls. We isolated cytotrophoblasts from 29 T21-affected placentas (12-25 wk) and 13 gestational age-matched control placentas and cultured them for 3 d. In this large series, we confirmed that, in the culture medium of trophoblasts isolated from T21 placentas, hCG secretion was significantly lower (P < 0.003) than in controls, in contrast to the high hCG in maternal serum of the same patients. In T21 cultured trophoblasts, transcripts of sialyltransferase-1 and fucosyltransferase-1 were abnormally high. In corresponding culture medium, hCG was abnormally glycosylated; highly acidic [isoelectric points (pHi) = 4.5] as shown by isoelectric focusing, immunoblotting, and lectin binding; and weakly bioactive (46% of control) as determined using the Leydig cell model. In conclusion, T21 trophoblast cells produced hCG that was weakly bioactive and abnormally glycosylated but whose maternal clearance was unaltered.
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PMID:Trophoblast production of a weakly bioactive human chorionic gonadotropin in trisomy 21-affected pregnancy. 1476 88