Matching Items (5)

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The application of multiple reaction monitoring to assess ApoA-I methionine oxidations in diabetes and cardiovascular disease

Description

The oxidative modification of apolipoprotein A-I’s methionine148 (M148) is associated with defective HDL function in vitro. Multiple reaction monitoring (MRM) is a mass spectrometric technique that can be used to

The oxidative modification of apolipoprotein A-I’s methionine148 (M148) is associated with defective HDL function in vitro. Multiple reaction monitoring (MRM) is a mass spectrometric technique that can be used to quantitate post-translational modifications. In this study, we developed an MRM assay to monitor the abundance ratio of the peptide containing oxidized M148 to the native peptide in ApoA-I. Measurement of the oxidized-to-unoxidized-M148 ratio was reproducible (CV < 5%). The extent of methionine M148 oxidation in the HDL of healthy controls, and type 2 diabetic participants with and without prior cardiovascular events (CVD) were then examined. The results suggest a significant increase in the relative ratio of the peptide containing oxidized M148 to the unmodified peptide in the HDL of participants with diabetes and CVD (p < 0.001), compared to participants without CVD. Monitoring the abundance ratio of the peptides containing oxidized and unoxidized M148 by MRM provides a means of examining the relationship between M148 oxidation and vascular complications in CVD.

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Agent

Created

Date Created
  • 2014-10-11

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Serum Amyloid A Truncations in Type 2 Diabetes Mellitus

Description

Serum Amyloid A (SAA) is an acute phase protein complex consisting of several abundant isoforms. The N- terminus of SAA is critical to its function in amyloid formation. SAA is

Serum Amyloid A (SAA) is an acute phase protein complex consisting of several abundant isoforms. The N- terminus of SAA is critical to its function in amyloid formation. SAA is frequently truncated, either missing an arginine or an arginine-serine dipeptide, resulting in isoforms that may influence the capacity to form amyloid. However, the relative abundance of truncated SAA in diabetes and chronic kidney disease is not known.
Methods
Using mass spectrometric immunoassay, the abundance of SAA truncations relative to the native variants was examined in plasma of 91 participants with type 2 diabetes and chronic kidney disease and 69 participants without diabetes.
Results
The ratio of SAA 1.1 (missing N-terminal arginine) to native SAA 1.1 was lower in diabetics compared to non-diabetics (p = 0.004), and in males compared to females (p<0.001). This ratio was negatively correlated with glycated hemoglobin (r = −0.32, p<0.001) and triglyceride concentrations (r = −0.37, p<0.001), and positively correlated with HDL cholesterol concentrations (r = 0.32, p<0.001).
Conclusion
The relative abundance of the N-terminal arginine truncation of SAA1.1 is significantly decreased in diabetes and negatively correlates with measures of glycemic and lipid control.

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Agent

Created

Date Created
  • 2015-01-21

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The association of plasma cystatin C proteoforms with diabetic chronic kidney disease

Description

Background
Cystatin C (CysC) is an endogenous cysteine protease inhibitor that can be used to assess the progression of kidney function. Recent studies demonstrate that CysC is a more specific

Background
Cystatin C (CysC) is an endogenous cysteine protease inhibitor that can be used to assess the progression of kidney function. Recent studies demonstrate that CysC is a more specific indicator of glomerular filtration rate (GFR) than creatinine. CysC in plasma exists in multiple proteoforms. The goal of this study was to clarify the association of native CysC, CysC missing N-terminal Serine (CysC des-S), and CysC without three N-terminal residues (CysC des-SSP) with diabetic chronic kidney disease (CKD).
Results
Using mass spectrometric immunoassay, the plasma concentrations of native CysC and the two CysC truncation proteoforms were examined in 111 individuals from three groups: 33 non-diabetic controls, 34 participants with type 2 diabetes (DM) and without CKD and 44 participants with diabetic CKD. Native CysC concentrations were 1.4 fold greater in CKD compared to DM group (p = 0.02) and 1.5 fold greater in CKD compared to the control group (p = 0.001). CysC des-S concentrations were 1.55 fold greater in CKD compared to the DM group (p = 0.002) and 1.9 fold greater in CKD compared to the control group (p = 0.0002). CysC des-SSP concentrations were 1.8 fold greater in CKD compared to the DM group (p = 0.008) and 1.52 fold greater in CKD compared to the control group (p = 0.002). In addition, the concentrations of CysC proteoforms were greater in the setting of albuminuria. The truncated CysC proteoform concentrations were associated with estimated GFR independent of native CysC concentrations.
Conclusion
Our findings demonstrate a greater amount of CysC proteoforms in diabetic CKD. We therefore suggest assessing the role of cystatin C proteoforms in the progression of CKD.

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Agent

Created

Date Created
  • 2016-03-25

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The application of multiple reaction monitoring and multi-analyte profiling to HDL proteins

Description

Background
HDL carries a rich protein cargo and examining HDL protein composition promises to improve our understanding of its functions. Conventional mass spectrometry methods can be lengthy and difficult to

Background
HDL carries a rich protein cargo and examining HDL protein composition promises to improve our understanding of its functions. Conventional mass spectrometry methods can be lengthy and difficult to extend to large populations. In addition, without prior enrichment of the sample, the ability of these methods to detect low abundance proteins is limited. Our objective was to develop a high-throughput approach to examine HDL protein composition applicable to diabetes and cardiovascular disease (CVD).
Methods
We optimized two multiplexed assays to examine HDL proteins using a quantitative immunoassay (Multi-Analyte Profiling- MAP) and mass spectrometric-based quantitative proteomics (Multiple Reaction Monitoring-MRM). We screened HDL proteins using human xMAP (90 protein panel) and MRM (56 protein panel). We extended the application of these two methods to HDL isolated from a group of participants with diabetes and prior cardiovascular events and a group of non-diabetic controls.
Results
We were able to quantitate 69 HDL proteins using MAP and 32 proteins using MRM. For several common proteins, the use of MRM and MAP was highly correlated (p < 0.01). Using MAP, several low abundance proteins implicated in atherosclerosis and inflammation were found on HDL. On the other hand, MRM allowed the examination of several HDL proteins not available by MAP.
Conclusions
MAP and MRM offer a sensitive and high-throughput approach to examine changes in HDL proteins in diabetes and CVD. This approach can be used to measure the presented HDL proteins in large clinical studies.

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Agent

Created

Date Created
  • 2014-01-08

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The Association of Human Apolipoprotein C-III Sialylation Proteoforms with Plasma Triglycerides

Description

Introduction
Apolipoprotein C-III (apoC-III) regulates triglyceride (TG) metabolism. In plasma, apoC-III exists in non-sialylated (apoC-III[subscript 0a] without glycosylation and apoC-III[subscript 0b] with glycosylation), monosialylated (apoC-III[subscript 1]) or disialylated (apoC-III[subscript 2])

Introduction
Apolipoprotein C-III (apoC-III) regulates triglyceride (TG) metabolism. In plasma, apoC-III exists in non-sialylated (apoC-III[subscript 0a] without glycosylation and apoC-III[subscript 0b] with glycosylation), monosialylated (apoC-III[subscript 1]) or disialylated (apoC-III[subscript 2]) proteoforms. Our aim was to clarify the relationship between apoC-III sialylation proteoforms with fasting plasma TG concentrations.
Methods
In 204 non-diabetic adolescent participants, the relative abundance of apoC-III plasma proteoforms was measured using mass spectrometric immunoassay.
Results
Compared with the healthy weight subgroup (n = 16), the ratios of apoC-III[subscript 0a], apoC-III[subscript 0b], and apoC-III[subscript 1] to apoC-III[subscript 2] were significantly greater in overweight (n = 33) and obese participants (n = 155). These ratios were positively correlated with BMI z-scores and negatively correlated with measures of insulin sensitivity (S[subscript i]). The relationship of apoC-III[subscript 1] / apoC-III[subscript 2] with S[subscript i] persisted after adjusting for BMI (p = 0.02). Fasting TG was correlated with the ratio of apoC-III[subscript 0a] / apoC-III[subscript 2] (r = 0.47, p<0.001), apoC-III[subscript 0b] / apoC-III[subscript 2] (r = 0.41, p<0.001), apoC-III[subscript 1] / apoC-III[subscript 2] (r = 0.43, p<0.001). By examining apoC-III concentrations, the association of apoC-III proteoforms with TG was driven by apoC-III[subscript 0a] (r = 0.57, p<0.001), apoC-III[subscript 0b] (r = 0.56. p<0.001) and apoC-III[subscript 1] (r = 0.67, p<0.001), but not apoC-III[subscript 2] (r = 0.006, p = 0.9) concentrations, indicating that apoC-III relationship with plasma TG differed in apoC-III[subscript 2] compared with the other proteoforms.
Conclusion
We conclude that apoC-III[subscript 0a], apoC-III[subscript 0b], and apoC-III[subscript 1], but not apoC-III[subscript 2] appear to be under metabolic control and associate with fasting plasma TG. Measurement of apoC-III proteoforms can offer insights into the biology of TG metabolism in obesity.

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Agent

Created

Date Created
  • 2015-12-03