Plasma proteins are covalently modified
The distribution of isomorphic forms of prolactin in the serum of pregnant women was studied by gel filtration chromatography. Using this technique we were able to resolve three peaks, detected by radioimmunoassay: they were termed 'big-big', 'big' and 'little' prolactin in order of decreasing size, with approximate molecular weights greater than 100 000, 50 000 and 21 000 respectively. They displayed a comparable immunoreactivity to the antiserum employed in the radioimmunoassay, as determined in competition experiments. The relative amount of each hormone form in serum changed during the third trimester of pregnancy. At week 33 of pregnancy, 'little' prolactin accounted for 63.2 +/- 7.7% of the total circulating hormone present in the serum of five normal pregnant women. During the progression of pregnancy, there was a gradual increase in the low molecular weight prolactin, so that, at the time of delivery, the larger forms of the hormone were present only in small amounts.
Multiple sclerosis (MS) is an inflammatory disease characterized by damage to the myelin sheath surrounding axons in the central nervous system. While the exact mechanism of this destruction is unknown, excess nitric oxide (NO) and adenosine triphosphate (ATP) have been measured in tissues and fluids obtained from people with MS. Here, incubation of interferon-beta (IFN-β), an MS drug with an unknown mechanism of action, with red blood cells (RBCs) obtained from people with MS provide evidence of a potential hypermetabolic state in the MS RBC that is decreased with IFN-β intervention. Specifically, binding of all three components of an albumin/C-peptide/Zn2+ complex to MS RBCs was significantly increased in comparison to control RBCs. For example, the binding of C-peptide to MS RBCs was significantly increased (3.4 ± 0.1 nM) compared to control RBCs (1.6 ± 0.2 nM). However, C-peptide binding to MS RBCs was reduced to a value (1.6 ± 0.3 nM) statistically equal to that of control RBCs in the presence of 2 nM IFN-β. Similar trends were measured for albumin and Zn2+ binding to RBCs when in the presence of IFN-β. RBC function was also affected by incubation of cells with IFN-β. Specifically, RBC-derived ATP and measurable membrane GLUT1 were both significantly decreased (56 and 24%, respectively) in the presence of IFN-β. Collectively, our results suggest that IFN-β inhibits albumin binding to the RBC, thereby reducing its ability to deliver ligands such as C-peptide and Zn2+ to the cell and normalizing the basal hypermetabolic state.
This study of 10 normal college-aged women was designed to clarify possible antagonist control mechanisms during the silent period of the agonist in rapid elbow extension tasks. Antagonist electromyographic temporal patterns were observed after agonist silence under various conditions to determine if antagonist activity in the rapid movement was controlled supraspinally (preprogrammed), spinally (reflexively), or by a combination of the two mechanisms. The subjects followed a velocity-controlled dot displayed on an oscilloscope. The antagonist latencies remained constant during intentionally and unintentionally terminated movements, but were altered by load conditions. This was seen as an automatic deceleration response, elucidating differences between antagonist control during ballistic and rapid movements.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.