The role of sialic acid in determining the life-span of circulating cells and glycoproteins

Bocci, Velio

doi:10.1007/bf01937727

Cited by 70 publications

(13 citation statements)

References 80 publications

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“…Since urinary excretion of TBG accounts for less than 0.2% of the total daily clearance (26), hepatic degradation appears to be the major route of TBG catabolism. Recognition of this route of degradation and the demonstration by Zinn et al (3) that asialo-TBG, but not intact sialylated TBG, binds to rat liver membrane suggested that, as with other circulating glycoproteins, the terminal sialic acid residues protect circulating TBG from removal by the liver (27,28). 3.…”

Section: Discussionmentioning

confidence: 99%

“…The rapid disappearance of serum glycoproteins after the administration of neuraminadase to the rat (35) demonstrates the exquisite sensitivity of glycoprotein clearance to desialylation. Although the anatomical site of desialylation is not known (28,36), evidence suggests that it is a continuous process within the circulation (28) or near the site of receptor uptake (37).…”

Section: Discussionmentioning

confidence: 99%

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Reduced Clearance Rate of Thyroxine-Binding Globulin (TBG) with Increased Sialylation: A Mechanism for Estrogen-Induced Elevation of Serum TBG Concentration*

Ain

Mori

Refetoff

1987

The Journal of Clinical Endocrinology & Metabolism

279

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Hyperestrogenemic states, including pregnancy, cause an increase in serum T4-binding globulin (TBG) concentrations and an increase in the proportion of TBG molecules with greater anodal mobility on isoelectric focusing, indicating greater sialic acid content. The possible causal relationship between the degree of sialylation and accumulation of TBG in serum was explored by measuring the in vivo half-lives (t1/2) of TBGs with different isoelectric points. TBG in unfractionated serum and its major peaks, isolated by chromatofocusing and defined by their isoelectric points on isoelectric focusing were each injected iv into rats. The resulting TBG concentrations, measured by specific RIA in serum samples obtained at intervals after injection, were used for the calculation of the t1/2. TBG in serum from a pregnant woman had a significantly longer t1/2 of 17.2 +/- 1.2 h (mean +/- SD) compared to those of 13.3 +/- 1.5 and 12.9 +/- 0.9 h for TBG in serum from a man and a nonpregnant woman, respectively. TBG peaks II, III, IV, and V, with increasing anodal mobility, had progressively longer t1/2 values of 11, 13, 15, and 33 h, respectively. However, TBG peaks of the same mobility on IEF isolated from serum of pregnant or nonpregnant subjects had similar t1/2 values. Neither the TBG concentration nor estrogen had a direct effect on the rate of TBG clearance. Indeed, the t1/2 of TBG from a subject with inherited TBG excess was not different from that of TBG from a nonpregnant woman or a man. Chronic treatment of rats with estradiol did not alter the rate of clearance of injected human TBG. Finally, the more heavily sialylated anodal bands of purified but unfractionated serum TBG, analyzed by Western blots, survived longer in the circulation of a rat. These results indicate that the rate of in vivo metabolism of TBG is dependent on its sialic acid content. The increased proportion of TBG molecules with higher sialic acid content thus contributes to the increase in the serum TBG concentration in hyperestrogenemic states.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Reduced Clearance Rate of Thyroxine-Binding Globulin (TBG) with Increased Sialylation: A Mechanism for Estrogen-Induced Elevation of Serum TBG Concentration*

Ain

Mori

Refetoff

1987

The Journal of Clinical Endocrinology & Metabolism

279

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“…These high false positive rates for both tests are largely due to the high number of positive results in patients with liver dis eases and may be explained by the major role of the liver in clearance and excretion of cir culating glycoproteins [12,13].…”

Section: Discussionmentioning

confidence: 99%

Prospective Evaluation of the Diagnostic Efficacy of CA 19–9 Assay as a Marker for Gastrointestinal Cancers

et al. 1986

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Levels of a new carbohydrate antigen, CA 19–9, which is a monosialoganglioside identified by a monoclonal antibody raised against colorectal carcinoma cells, were compared to conventional CEA assays in 615 sera from healthy controls, patients with benign gastrointestinal disorders, and patients with cancers of gastrointestinal or extragastrointestinal origin. Whereas CEA levels were higher in smokers, CA 19–9 values were independent of the smoking history. CA 19–9 was undetectable in lymphoma and myeloma patients, but some patients with extraintestinal epithelial cancers expressed this antigen in serum. For benign and malignant gastrointestinal diseases, CA 19–9 displayed higher sensitivity, specificity, and predictive values than CEA. CA 19–9 was elevated as frequently as CEA in patients with metastatic pancreatic cancer, but in patients with localized disease, CA 19–9 was elevated more often than was CEA. In colorectal cancer, patients with and without metastases were detected at similar rates by both assays. It is concluded that CA 19–9 is a marker of epithelial cancers, does not vary with the smoking status, and is superior to CEA in detecting gastrointestinal malignancies, especially those arising from the pancreatic gland.

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“…Its role in various cell functions and life span determi nations has been well documented [11], De crease in sialic acid and net negative charge occurs in adhesion, aggregation and some shape changes, and removal of as little as 10% of the surface sialic acid leads to a short ened platelet life span [10]. The increased negative charge in IS could be responsible for increased calcium binding, altered perme ability and defective responses to activating agents as previously noted in IS platelets [1,2,5],…”

Section: Discussionmentioning

confidence: 99%

Negative Surface Charge on Platelets of Patients with Idiopathic Scoliosis

Yarom¹,

Meyer²,

More³

1982

Pathophysiol Haemos Thromb

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In order to assess the negative surface charge on platelets from patients with idiopathic scoliosis (IS) and suitable controls, formalin-fixed cells were examined by the two-phase aqueous polymer separation system and by binding of cationised ferritin. The results show that IS platelets have a higher negative surface charge. This could be responsible for several functional and structural abnormalities observed previously in IS platelets.

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The role of sialic acid in determining the life-span of circulating cells and glycoproteins

Cited by 70 publications

References 80 publications

Reduced Clearance Rate of Thyroxine-Binding Globulin (TBG) with Increased Sialylation: A Mechanism for Estrogen-Induced Elevation of Serum TBG Concentration*

Reduced Clearance Rate of Thyroxine-Binding Globulin (TBG) with Increased Sialylation: A Mechanism for Estrogen-Induced Elevation of Serum TBG Concentration*

Prospective Evaluation of the Diagnostic Efficacy of CA 19–9 Assay as a Marker for Gastrointestinal Cancers

Negative Surface Charge on Platelets of Patients with Idiopathic Scoliosis

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