Effect of desialylation of highly purified isoforms of human luteinizing hormone on their bioactivity in vitro, radioreceptor activity and immunoactivity

1997 ◽  
Vol 9 (5) ◽  
pp. 501 ◽  
Author(s):  
Patrick G. Burgon ◽  
Peter G. Stanton ◽  
Kim Pettersson ◽  
David M. Robertson
Keyword(s):  
Sialic Acid ◽  
Luteinizing Hormone ◽  
Acid Content ◽  
Specific Activity ◽  
Sialic Acid Residue ◽  
In Vitro Bioactivity ◽  
Human Pituitary ◽  
Sialic Acid Content ◽  
Before And After

To establish whether sialic acid content is responsible for an observed 7–8-fold variability in bioactivity in vitro of highly purified human pituitary luteinizing hormone (hLH) isoforms, the bioactivity in vitro, radioreceptor activity and immunoactivity of hLH isoforms were determined before and after enzymatic desialylation. Three immunofluorometric assays with different hLH specificities allowed characterization of 13–24 pituitary hLH isoform preparations of pI 7·03–8·98 in terms of sialic acid content (1–5 sialic acid residues per LH molecule), bioactivity in vitro (4030–30 000 I.U. mg-1), radioreceptor activity (6420–25 400 I.U. mg-1) and hLH immunoactivity (2900–4400 to 18 300–27 300 I.U. mg-1). Significant positive correlations between sialic acid content and either immunoactivity or in vitro bioactivity were observed, whereas radioreceptor activity showed a curvilinear response. Following more than 90% removal of sialic acid, both in vitro bioactivity and radioreceptor activity were increased, although specific activity still differed between isoforms; immunoactivities were unaffected. It is concluded that the presence of the sialic acid residue(s) on hLH isoforms does partially contribute to the in vitro bioactivity and radioreceptor activity of the isoforms, but that hLH immunoactivity is independent of sialic acid content.

Partial resialylation of human asialotransferrin types 1 and 2 in the rat

1984 ◽  
Vol 62 (9) ◽  
pp. 853-858 ◽  
Author(s):  
Erwin Regoeczi ◽  
Paul A. Chindemi ◽  
Maria T. Debanne
Keyword(s):  
Sialic Acid ◽  
Electrophoretic Mobility ◽  
Acid Content ◽  
Sialic Acid Content ◽  
Small Doses ◽  
Type 3 ◽  
Time Type

125I-labeled asialotransferrin types 1 and 2 were administered in small doses to rats. The protein still in the plasma after 1–12 h was partially repurified and electrophoresed at pH 8.1, together with a transferrin standard that is composed of all six forms of the protein with respect to sialic acid content. The electrophoretic mobility of both asialotransferrins increased with time, type 2 being affected sooner than type 1. The changed mobility was due to increased electronegativity that was fully reversible by treatment of the samples with neuraminidase, thus identifying the underlying cause as partial resialylation. Asialotransferrin incubated in vitro with serum, plasma, or whole blood for 16 h exhibited no change in electrophoretic mobility. In conjunction with an earlier study on asialotransferrin type 3, it was found that the apparent speeds of resialylation of the three asialotransferrins were in the same order as their affinities for the asialoglycoprotein-binding hepatic lectin. This suggests the involvement of an endo- rather than of an ecto-transferase. Transfer of 59Fe from asialotransferrins to the liver was used to monitor the frequency of hepatocyte–asialotransferrin interactions. Iron deposition in the liver took place much more rapidly than the appearance of detectable quantities of partially resialylated asialotransferrin molecules in the circulation. It is concluded that each asialotransferrin molecule probably undergoes several passages through the hepatocyte before its glycans become modified.

SIALIC ACID CONTENT AND SPERM RECEPTIVITY OF CERVICAL MUCUS IN RELATION TO OESTROGEN EXCRETION FOLLOWING ADMINISTRATION OF FSH

1969 ◽  
Vol 62 (4) ◽  
pp. 711-720 ◽  
Author(s):  
L. Carlborg ◽  
C. Gemzell
Keyword(s):  
Sialic Acid ◽  
Acid Content ◽  
Cervical Mucus ◽  
Human Pituitary ◽  
Sialic Acid Content ◽  
Oestrogen Level

ABSTRACT The cervical mucus was studied with regard to changes in sialic acid content and sperm receptivity. The data were correlated with the urinary total oestrogen excretion in anovulatory women treated with human pituitary gonadotrophins (HPG). With increasing total oestrogen excretion the sialic acid content decreased and the sperm receptivity increased. At a total oestrogen level of about 60 μg/24 h the respective patterns of the curves were reversed and higher values for total oestrogen were actually associated with a decrease in sperm receptivity and an increase in sialic acid content. The possible significance of these observations is discussed.

A comparison of preparations of highly purified human pituitary luteinizing hormone: differences in the luteinizing hormone potencies as determined by in vivo bioassays, in vitro bioassay and immunoassay

1982 ◽  
Vol 101 (3) ◽  
pp. 339-347 ◽  
Author(s):  
P. L. Storring ◽  
A. A. Zaidi ◽  
Y. G. Mistry ◽  
Monica Lindberg ◽  
Bridget E. Stenning ◽  
...  
Keyword(s):  
Luteinizing Hormone ◽  
In Vitro Bioactivity ◽  
In Vitro Bioassay ◽  
Response Curves ◽  
Human Pituitary ◽  
International Reference ◽  
Reference Preparation ◽  
In Vivo Bioassay

Abstract. The LH potencies of 12 preparations of highly purified human pituitary LH, from 6 laboratories, were estimated by 2 in vivo bioassays and an in vitro bioassay in terms of the International Reference Preparation of Human Pituitary Gonadotrophins (FSH and LH) for Bioassay (coded 69/104); and by immunoassay in terms of the International Reference Preparation of Human Pituitary Luteinizing Hormone for Immunoassay (IRP; coded 68/40). The LH potencies varied between preparations, including the IRP (68/40), from 864 to 5740 IU/mg by seminal vesicle weight gain (SVW) assay; from 1510 to 11500 IU/mg by ovarian ascorbate depletion (OAAD) assay; from 4490 to 14500 IU/mg by in vitro (testicular interstitial-cell testosterone production) bioassay; and from 2030 to 9180 IU/mg by immunoassay. Estimates of protein content were based on the assumption that the absorbance of LH at 280 nm (A 1% 1 cm) was 6.0. The LH potency of most preparations was highest by in vitro bioassay and lowest by SVW assay. The correlation between activities determined by SVW and OAAD assays was more marked than that between estimates by OAAD assay and in vitro bioassay; there was no correlation between estimates by SVW assay and in vitro bioassay. The slopes of the log dose-response curves of preparations in the OAAD assay were positively correlated with their potencies by OAAD assay and negatively correlated with the slopes of their log dose-response curves in the SVW assay. The qualitative differences between preparations are considered to be a reflection of the heterogeneity of LH and of its modification by different purification procedures. The present data, together with the different patterns of heterogeneity found in some of these preparations by isoelectric focusing in a separate study, suggest that the more basic molecular forms of LH, which are preferentially purified during the isolation of LH free from FSH and TSH, have shorter plasma survival times than the more acidic forms. The LH immunoreactivities of all preparations were significantly correlated with their potencies estimated by each of the in vivo bioassays but not with those estimated by in vitro bioassay. The ratios of in vitro bioactivity (in terms of IRP (68/40)): immunoreactivity varied between preparations from 0.53–1.5. The FSH content of each preparation was less than 2% (w/w) by bioassay and immunoassay. Most preparations were more potent by in vitro bioassay than by in vivo bioassay, which contrasted with, and complemented, findings for purified FSH preparations. This indicated that, as in the case of LH, the more basic molecular species of FSH are associated with lower ratios of in vivo: in vitro bioactivity than are the more acidic species. This study provides the most comprehensive comparison available of the activities of purified preparations of LH isolated from frozen and acetone-dried human pituitary glands in different experienced laboratories. These data are needed for selecting material for an international reference preparation of LH for immunoassay on the basis of high LH potency by in vivo bioassay, recommended by the WHO as a criterion for the identity of the hormone and for its freedom from contaminants. The consequences of the heterogeneity of LH are considered for the purification of the reference material and for the suitability of the latter for the various types of specimens which require LH assays.

Molecular composition of human luteinizing hormone: biological and immunological profiles of highly purified preparations after electrofocusing

1982 ◽  
Vol 94 (1) ◽  
pp. 29-36 ◽  
Author(s):  
A. A. Zaidi ◽  
M. H. Qazi ◽  
E. Diczfalusy
Keyword(s):  
Biological Activity ◽  
Luteinizing Hormone ◽  
Sucrose Density Gradient ◽  
Molecular Composition ◽  
Immunological Reactivity ◽  
Human Pituitary ◽  
Before And After ◽  
Pituitary Glands ◽  
Ph Range

Five highly purified human pituitary LH preparations (candidate preparations for a new International Reference Preparation (IRP) and coded A to E) and three highly purified commercial preparations (referred to as Kabi I, II and III) were fractionated by electrofocusing on a sucrose density gradient with ampholytes in the pH range of 3·5–10·0 The LH activity was monitored in each of the eluted fractions by an in-vitro bioassay and a radioimmunoassay procedure and the profiles of biological activity and immunoreactivity were compared with those of the first IRP of Human Pituitary Luteinizing Hormone for Immunoassay (code no. 68/40). The overall recovery of the biological activity after electrofocusing of the nine preparations ranged between 75 and 92% (mean 86%) and was higher (P < 0·05) than that of the immunological reactivity which varied between 71 and 94% (mean 79%). The profiles of the biological activity and immunological reactivity were in close agreement with each other in all preparations. Significant differences were, however, observed in the distribution of various molecular species between the currently used standard and the eight other highly purified preparations. The ratios of biological activity (B) to immunoreactivity (I) of preparation B and of the three Kabi preparations were significantly higher than those of the other five preparations, both before and after electrofocusing. After electrofocusing, a slight but significant (P < 0·05) rise in the B/I ratios was observed, suggesting that some biologically inactive immunoreactive material was removed during fractionation. All purified preparations lacked the characteristic 'acidic' human LH species which accompanies FSH and which is abundant in the IRP (69/104) and is also present in aqueous extracts of postmenopausal pituitary glands. A comparison of the electrofocusing profiles of the nine highly purified preparations with those of human LH from plasma and individual pituitary glands revealed marked differences, suggesting that the methods used for the purification of the hormone significantly altered its molecular composition.

scholarly journals Daytime of Sampling, Tooth-Brushing and Ascorbic Acid Influence Salivary Thiobarbituric Acid Reacting Substances – A Potential Clinical Marker of Gingival Status

2005 ◽  
Vol 21 (4) ◽  
pp. 203-207 ◽  
Author(s):  
Július Hodosy ◽  
Peter Celec
Keyword(s):  
Ascorbic Acid ◽  
Sialic Acid ◽  
Acid Content ◽  
Thiobarbituric Acid ◽  
Tooth Brushing ◽  
Gingival Tissue ◽  
Sialic Acid Content ◽  
Modified Method ◽  
Before And After ◽  
Pre Treatment

Background. Salivary thiobarbituric acid reacting substances (TBARS) have been previously shown to correlate with the impairment of gingival tissue. Although the details on the origin and the composition of this heterogeneous group of compounds in saliva are unknown, the potential clinical usefulness makes necessary the studies of factors influencing the salivary TBARS levels. Aim. To observe the effects of daily dynamics, tooth-brushing and ascorbic acid administration on salivary TBARS levels. Subjects and methods. Self-collected samples were obtained from 10 young healthy men collecting samples in the morning, in the afternoon and in the evening during 2 consecutive days. Ascorbic acid (250 mg) was administered orally after the last sampling on day 1 and before every sampling on day 2. Additional sampling was performed before and after tooth-brushing. TBARS levels in saliva specimens were detected spectrofluorometrically. Sialic acid content was measured using a modified method of Warren. Results. Salivary TBARS levels vary significantly during a day (p< 0.001) with highest concentrations in the morning. Both, tooth-brushing (p< 0.05) and short-term antioxidative treatment with ascorbic acid (p< 0.005) decrease salivary TBARS levels. Sialic acid content of saliva is not influenced significantly by any of the investigated factors. Conclusion. TBARS levels in saliva are affected by daytime of sampling, tooth-brushing and ascorbic acid pre-treatment. These results must be considered in clinical research using salivary TBARS levels. Sialic acid seems not to be a major component of TBARS in saliva. Further studies should clarify the molecular compounds of salivary TBARS and uncover the role of oral microbial factors.

129: Sialic Acid Content of Urinary TAMM-Horsfall Protein is Reduced in Interstitial Cystitis Patients

2007 ◽  
Vol 177 (4S) ◽  
pp. 44-45
Author(s):  
C. Lowell Parsons ◽  
Mahadevan Rajasekaran ◽  
Marianne Chenoweth ◽  
Paul Stein
Keyword(s):  
Sialic Acid ◽  
Interstitial Cystitis ◽  
Acid Content ◽  
Sialic Acid Content

scholarly journals Differences in Sialic Acid Content of Human Interferons

1978 ◽  
Vol 41 (1) ◽  
pp. 175-178 ◽  
Author(s):  
J. Morser ◽  
J. P. Kabayo ◽  
D. W. Hutchinson
Keyword(s):  
Sialic Acid ◽  
Acid Content ◽  
Sialic Acid Content

scholarly journals Infection with Listeria monocytogenes impairs sialic acid addition to host cell glycoproteins.

1994 ◽  
Vol 180 (6) ◽  
pp. 2137-2145 ◽  
Author(s):  
M S Villanueva ◽  
C J Beckers ◽  
E G Pamer
Keyword(s):  
Listeria Monocytogenes ◽  
Sialic Acid ◽  
Host Cell ◽  
Mhc Class I ◽  
Acid Content ◽  
Class I ◽  
Sialic Acid Content ◽  
Infected Cells ◽  
The Impact ◽  
Glycosylation Defect

Listeria monocytogenes is a facultative intracellular bacterium that causes severe disease in neonates and immunocompromised adults. Although entry, multiplication, and locomotion of Listeria in the cytosol of infected cells are well described, the impact of such infection on the host cell is unknown. In this report, we investigate the effect of L. monocytogenes infection on MHC class I synthesis, processing, and intracellular trafficking. We show that L. monocytogenes infection interferes with normal processing of N-linked oligosaccharides on the major histocompatibility complex (MHC) class I heavy chain molecule, H-2Kd, resulting in a reduced sialic acid content. The glycosylation defect is more pronounced as the infection progresses and results from interference with the addition of sialic acid rather than its removal by a neuraminidase. The effect is found in two different cell lines and is not limited to MHC class I molecules since CD45, a surface glycoprotein, and LGP120, a lysosomal glycoprotein, are similarly affected by L. monocytogenes infection. The glycosylation defect is specific for infection by L. monocytogenes since neither Trypanosoma cruzi nor Yersinia enterocolitica, two other intracellular pathogens, reproduces the effect. The resultant hyposialylation of H-2Kd does not impair its surface expression in infected cells. Diminished sialic acid content of surface glycoproteins may enhance host-defense by increasing susceptibility to lysis and promoting clearance of Listeria-infected cells.

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