Glycosylation in Cancer and Oncogenic Transformation

Loci and motifs of the GalNAcα1 → 3/O related glycotopes in the mammalian glycoconjugates and their lectin recognition roles

Galα1 → and GalNAcα1 → are the two essential key sugars in human blood group AB active glycotopes, in which GalNAcα1 → related sequences are located at both sides of the nonreducing and the reducing ends of human blood group A active O-glycans. It is also found at the nonreducing ends of GlcNAc N-glycans and glycosphingolipid(GSL) of human blood group A active glycotopes (A_h) and Forssman antigen (F_p). When monosaccharides and their α, β anomers are involved in basic units to express the complex size of the combining sites of the GalNAcα1 → specific lectins, they can be divided into a cavity site to accommodate the GalNAcα → key sugar and a subsite with a wide and broad range of recognition area to adopt the rest part of sugar sequences or glycotopes. The function of the subsite is assumed to act as an enhancement factor to increase its affinity power. The following three points are the theme of this mini review: (1) the loci and distribution of the GalNAcα1 → related glycotopes in mammalian glycoconjugates are illustrated and their chemical structures are advanced by the expression of the disaccharide units and code system; (2) the sizes and motifs of GalNAcα1 → specific lectin-glycan interactions are given and (3) the role of the polyvalent blood group A_h and B_h glycotopes as blood group AB antigens are proposed. These three highlights should provide an essential background required for the advances in this field.

The effect of laparoscopy on the IGF system in patients diagnosed with acute cholecystitis

OBJECTIVE

IGFs and IGF binding proteins in the circulation are subject to modulation by a number of catabolic states including inflammation, trauma and surgery. We sought to determine the impact of laparoscopy on the IGF system in patients diagnosed with acute cholecystitis.

DESIGN

The components of the IGF system, cortisol, glucose and insulin concentration in both the serum and urine of patients were compared to those from a healthy group of subjects. An additional comparison was made between pre- and post-laparoscopically assisted patients.

PATIENTS

Thirty patients diagnosed with acute cholecystitis and 81 matched controls were included in the study.

MEASUREMENTS

Radioimmunoassays were used to determine the IGF-I, IGF-II, insulin and cortisol concentrations. The concentration of IGFBP-3 was measured using an immunoradiometric assay. The GOD-PAP method was used to determine the glucose concentration. Gel filtration chromatography was performed to calculate the IGF binary/ternary complex ratio. The amount of sialic acid in IGFBP-3 was determined by affinity chromatography. The presence of IGFBPs in serum was determined by both immunoblotting and ligandblotting.

RESULTS

The concentrations of circulating IGF-I, IGF-II and IGFBP-3 were significantly reduced in pre-operative patients compared to healthy subjects. No further reductions were observed post-laparoscopy. Immunoblotting and ligandblotting demonstrated a decreased amount of IGFBP-3 in both pre- and post-operative patients compared to healthy subjects. Increased levels of IGFBP-2 and IGFBP-1 were observed in pre-operative patients compared to healthy subjects, but laparoscopy did not cause further elevation. No alteration in the IGF binary/ternary complex ratio was witnessed between any of the study groups. A significant increase in the sialic acid content of IGFBP-3 was seen in both patient groups when compared to healthy subjects. The level of urinary cortisol was significantly increased in post-operative patients, whereas the urinary IGF-I concentration was decreased compared to healthy subjects.

CONCLUSIONS

Our results indicate that acute cholecystitis causes several significant changes in the circulating IGF system. Laparoscopy, however, does not aggravate such changes, but elevates urinary cortisol.