Diabetes
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12503/21681
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Browsing Diabetes by Author "Deodhar, Sneha"
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Item Benchtop NMR Relaxometry in Clinical Diagnostics: Whole Human Blood(2017-03-14) Deodhar, Sneha; Mishra, Ina; Cistola, David; Patel, VipulkumarPurpose: Benchtop NMR relaxometry is a promising technology for metabolic heath screening and assessment. Unlike spectrometry and imaging, NMR relaxometry uses compact and inexpensive devices, making it practical for clinical laboratories and point-of-care settings. In previous work, we reported that the water transverse relaxation time (T2) of human blood plasma is a sensitive and specific marker for early insulin resistance syndrome. Here, we investigated whether whole human blood could be analyzed directly, thus avoiding the centrifugation step and saving time and expense. During sample equilibration, anticoagulated whole blood sediments spontaneously inside the NMR tube, creating a cell pellet and a plasma supernatant. We exploited this phenomenon and designed experiments to measure the T2 values of the pellet and supernatant simultaneously. The goal of this study was to quantify the association of whole blood T2 values with over 200 established blood biomarkers in order to assess information content of the T2 data. Methods: We recruited 45 asymptomatic, non-diabetic human volunteers through an IRB-approved protocol. Blood samples were collected after an overnight fast, and NMR relaxation times were measured using a Bruker Minispec mq20 and a modified Carr-Purcell-Meiboom-Gill pulse scheme. The exponential decay curves were analyzed using a discrete inverse Laplace transform algorithm, as implemented in XpFIT (Alango, Ltd.), to extract T2 values. In addition, diagnostic testing was performed on each blood sample, mostly by Quest Diagnostics, Inc. and Atherotech, Inc. Results: The settled blood gives two distinct T2 values corresponding to supernatant (T2S) and cell pellet (T2P). Surprisingly, supernatant T2S correlates with red blood cell and hemoglobin markers, even though it lacks both red blood cell and hemoglobin after sedimentation. Therefore, we hypothesized that the paramagnetic deoxyhemoglobin from the cell pellet exerts a long-range influence on the plasma supernatant. This hypothesis was tested by a simulated hematocrit experiment that varied the height of the blood cell pellet, and a gadolinium experiment that altered the relaxation of samples that were physically separated. The cell pellet T2P correlates with insulin and lipid biomarkers from the blood. Conclusions: The results demonstrate that whole blood T2 values report on insulin resistance status, as well as hematocrit and hemoglobin levels.Item Unveiling the Factors Driving Plasma Water T2 as a Biomarker for Early Insulin Resistance Syndrome(2017-03-14) Deodhar, Sneha; Cistola, David; Mishra, InaBackground: Approximately 86 million US adults have prediabetes, putting them at high risk for type 2 diabetes mellitus and cardiovascular disease. Prediabetes is a state of impaired glucose tolerance or moderate hyperglycemia where up to 70% of pancreatic β-cell capacity has been lost irreversibly. It is preceded by an often-undetected phase, early insulin resistance syndrome (EIRS), which consists of compensatory hyperinsulinemia, dyslipidemia, subclinical inflammation and electrolyte abnormalities. Early identification is important to preserve pancreatic function and prevent diabetes and pre-diabetes. In previous work, we showed that plasma water transverse relaxation time T2, measured using benchtop NMR relaxometry, provides a sensitive measure of EIRS in asymptomatic, normoglycemic subjects. Plasma water T2 detected EIRS in 15% of this cohort, which was undetected by fasting glucose or HbA1c. Our hypothesis is that shifts in the levels of specific acute phase proteins and lipoproteins drive plasma water T2 values lower in EIRS. Purpose: To quantify the contributions from the most abundant plasma proteins and lipoproteins to plasma water T2 by determining relaxivity values (r, slope of 1/T2 vs. concentration). Higher relaxivity means greater influence on water T2. Methods: Purified plasma protein fractions were obtain from Millipore-Sigma, Inc. and Athens, Inc., and lipoprotein fractions were prepared from human plasma using density-gradient ultracentrifugation. Two sets of serial dilutions were made for each protein and lipoprotein fraction: (1) in phosphate-buffered saline, to determine r value in buffer alone, and 2) in a mixture of human serum albumin and gamma globulin, to determine r in a background that mimics human plasma. Protein concentrations were quantified using a Pierce BCA assay, and total cholesterol and triglyceride concentrations, using kits from Wako Diagnostics. Linear regression was used to quantify and compare r values. Results: The highest relaxivity values were observed for ceruloplasmin, haptoglobin, apo-transferrin and complement C3, whereas surprisingly low values were observed for triglyceride-rich lipoproteins. Albumin, IgG and α2-macroglobulin yielded intermediate r values. Conclusions: This study unveils the factors driving plasma water T2 as a biomarker for early insulin resistance syndrome. Plasma water T2 is a promising tool for population screening and metabolic health assessment for diabetes and prediabetes prevention.Item Use of Frozen vs. Fresh Plasma to Assess Early Insulin Resistance Syndrome(2017-03-14) Patel, Vipulkumar; Mishra, Ina; Deodhar, Sneha; Cistola, David; Jones, ClintBackground: Insulin resistance is defined as the blunted response to insulin by tissues and can progress to prediabetes and type 2 diabetes. About 86 million US adults were identified with pre-diabetes in 2012. By the time prediabetes develops, approximately 70% of β-cell secretory function has been lost irreversibly. Thus, it is imperative to detect insulin resistance at an earlier stage in order to preserve pancreatic function and prevent progression to diabetes. Prior work revealed that water proton transverse relaxation time (T2) measured by NMR relaxometry using fresh human plasma samples provides a sensitive and specific biomarker for early insulin resistance syndrome. Purpose: The objective of this study was to compare T2 values of frozen plasma samples with those from fresh plasma to assess the feasibility of analyzing bio-banked samples from longitudinal population studies. Hypothesis: Freezing at -80oC will have little or no impact on measured T2 values and their correlation with insulin resistance markers. Methods: We recruited 45 asymptomatic, non-diabetic human volunteers though an IRB approved protocol. Blood samples were collected after an overnight fast and were processed and analyzed immediately, with the remaining samples stored at -80oC. In addition, over 200 blood biomarkers were measured on each fresh blood sample – many by outside laboratories including Quest Diagnostics, Inc. and Atherotech, Inc. After several months in the freezer, the NMR measurements were performed on the once-frozen, once-thawed samples. All NMR measurements were performed at 37oC using a Bruker mq20 Minispec instrument and a modified CPMG pulse scheme. The associations between frozen and fresh T2 values and metabolic biomarkers were quantified using the Pearson’s product moment and concordance correlation coefficients. Results: Plasma water T2 from frozen samples showed a strong, statistically significant correlation with fresh plasma water T2 values (Pearson r=0.85, Concordance correlation coefficient=0.74). However, the frozen plasma water T2 were 5% lower, on average, than fresh samples. Nevertheless, this difference did not impact the overall pattern of association between T2 and metabolic biomarkers of early insulin resistance syndrome. Conclusions: These findings establish the feasibility of using frozen bio-banked specimens for the validation of plasma water T2 as a metabolic biomarker and screening tool for diabetes risk assessment.