Metabolism of Parathyroid Hormone by Isolated Rat Kupffer Cells and Hepatocytes

Abstract

A B S T R A C Tshowed that the dominant hormonal fragments recovered in the medium have an apparent molecular weight of -6,000, lack amino-terminal antigenic determinants, and react in assays that specifically recognize determinants in the carboxy-terminal portion of the intact hormone. Amino-terminal fragments also were detected in high concentrations, particularly after short incubation periods. Radioiodinated fragments resulting from incubation of 125I-labeled bovine parathyroid hormone with Kupffer cells had the same apparent size as fragments derived from the metabolism of unlabeled, intact hormone; when analyzed by Edman degradation, positions 34 and 37 of the intact hormone sequence were the amino-terminal amino acids of these dominant carboxy-terminal fragments. Hepatocytes did not hydrolyze the hormone. Thus, metabolism of parathyroid hormone by Kupffer cells results in the appearance of fragments in the media

Protein Bead Array for the Detection of HIV-1 Antibodies from Fresh Plasma and Dried-Blood-Spot Specimens

“…Protein Bead Array for the Detection of HIV-1 Antibodies from Fresh Plasma and Dried-Blood-Spot Specimens, Sylvie Faucher, 1* Alexandre Martel, 1 Alice Sherring, 1 Tao Ding, 1 Laurie Malloch, 2 John E. Kim, 2 Michèle Bergeron, 1 Paul Sandstrom, 3 and Francis F. Mandy 1 ( 1 National HIV Immunology Laboratory, National HIV and Retrovirology Laboratories, Centre for Infectious Disease Prevention and Control, Health Canada, Ottawa, ON, Canada; 2 National Laboratory for HIV Reference Services, National HIV and Retrovirology Laboratories, Centre for Infectious Disease Prevention and Control, Health Canada, Ottawa, ON, Canada;…”

“…The suspension array technology (SAT), which uses microfluorospheres with flow cytometry, is a multianalyte immunoassay that requires small specimen volumes, such as those obtained by lessinvasive blood sampling approaches such as heel or finger sticks, as well as those obtained in pediatric specimens. The dried-blood-spot (DBS) technology has become an important screening tool for clinical and epidemiologic testing (1)(2)(3). It is particularly convenient in rural, resource-limited settings where trained personnel and adequate facilities for blood collection, processing, transport, and storage may not be available.…”

Circulating Forms of Parathyroid Hormone: Peeling Back the Onion

“…PTH, secreted by the parathyroid glands primarily in response to changes in blood ionized calcium, undergoes rapid endopeptidic cleavage, mainly by Kupffer cells in the liver (3 ). This event generates a series of N-truncated "CPTH" fragments (the corresponding N-terminal segments are destroyed in situ) that reenter the circulation and are cleared mainly by glomerular filtration, an important route for PTH clearance as well (4 ).…”

Considerations in parathyroid hormone testing

“…These fragments are generally called C-terminal fragments because they have kept the carboxylterminal part of the peptide [7]. They are cleared from the circulation through the kidneys, as PTH itself [8], thus accumulating in the blood of patients suffering from chronic kidney diseases (CKD) [9].…”