Hypertension after kidney donation: Incidence, predictors, and correlates.

Incidence of postdonation hypertension, risk factors associated with its development, and impact of type of treatment received on renal outcomes were determined in 3700 kidney donors. Using Cox proportional hazard model, adjusted hazard ratios (HRs) for cardiovascular disease (CVD); estimated glomerular filtration rate (eGFR) <60, <45, <30 mL/min/1.73m2 ; end stage renal disease (ESRD); and death in hypertensive donors were determined. After a mean (standard deviation [SD]) of 16.6 (11.9) years of follow-up, 1126 (26.8%) donors developed hypertension and 894 with known antihypertensive medications. Hypertension developed in 4%, 10%, and 51% at 5, 10, and 40 years, respectively, and was associated with proteinuria, eGFR < 30, 45, and 60 mL/min/1.73m2 , CVD, and death. Blood pressure was <140/90 mm Hg at last follow-up in 75% of hypertensive donors. Use of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (compared to other antihypertensive agents) was associated with a lower risk for eGFR <45 mL/min/1.73m², HR 0.64 (95% confidence interval [CI] 0.45-0.9), P = .01, and also less ESRD; HR 0.03 (95% CI 0.001-0.20), P = .004. In this predominantly Caucasian cohort, hypertension is common after donation, well controlled in most donors, and factors associated with its development are similar to those in the general population.

Weight gain after kidney donation: Association with increased risks of type 2 diabetes and hypertension.

In the general population, obesity is associated with an increased risk of developing hypertension (HTN), type 2 diabetes mellitus (DM), and end-stage renal disease (ESRD). Therefore, most transplant centers have a body mass index (BMI) threshold for accepting living kidney donors. But there have been no studies of postdonation weight gain trends and any associated risks. We tracked serial BMIs in 940 donors for a median (IQ range) follow-up of 22.3 (15.4-35.8) years. We studied the impact of postdonation weight gain in a model adjusted for family history of HTN or DM. Donor characteristics included age, sex, smoking, fasting blood glucose, eGFR, systolic and diastolic BP, and BMI at time of donation and time postdonation. Postdonation weight gain was associated with a significant increase in the relative risk of developing HTN RR 1.93 (95% CI 1.51-2.46) (P < 0.001) and/or DM RR 4.18 (95% CI 2.05-8.5) (P < 0.0001), but not (to date) cardiovascular disease (CVD), reduced eGFR or death. Like the general population, donors gained weight as they aged; a higher BMI was associated with higher incidence of DM and HTN. Postdonation care should include ongoing counseling on the risks of substantial weight gain.

Intermuscular Adipose Tissue and Subclinical Coronary Artery Calcification in Midlife: The CARDIA Study (Coronary Artery Risk Development in Young Adults).

OBJECTIVE: Excess deposition of fat within and around vital organs and nonadipose tissues is hypothesized to contribute to cardiovascular disease (CVD) risk. We evaluated the association of abdominal intermuscular adipose tissue (IMAT) volume with coronary artery calcification in the CARDIA study (Coronary Artery Risk Development in Young Adults) participants. APPROACH AND RESULTS: We measured IMAT in the abdominal muscles, visceral adipose tissue and pericardial adipose tissue, and coronary artery calcification using computed tomography in 3051 CARDIA participants (56% women) at the CARDIA year 25 examination (2010-2011). Mean IMAT volume and mean IMAT/total muscle volume (IMAT normalized for muscle size) were calculated in a 10-mm block of slices centered at L3-L4. Multivariable analyses included potential confounders and traditional cardiovascular disease risk factors. Compared with the lowest quartile, the upper quartile of abdominal IMAT volume was associated with higher coronary artery calcification prevalence (odds ratio [95% confidence interval], 1.6 [1.2-2.1]) after adjusting for cardiovascular disease risk factors. Results were similar for highest versus lowest quartile of IMAT normalized to total muscle volume (odds ratio [95% confidence interval], 1.5 [1.1-2.0]). Significant associations of higher IMAT and normalized IMAT with coronary artery calcification prevalence persisted when body mass index, visceral adipose tissue, or pericardial adipose tissue were added to the models. CONCLUSIONS: In a large, community-based, cross-sectional study, we found that higher abdominal skeletal muscle adipose tissue volume was associated with subclinical atherosclerosis independent of traditional cardiovascular disease risk factors and other adipose depots.

Collagen Turnover Markers in Relation to Future Cardiovascular and Noncardiovascular Disease: The Multi-Ethnic Study of Atherosclerosis.

BACKGROUND: Sustained remodeling of extracellular matrix can compromise organs and tissues. Procollagen type III N-terminal propeptide (PIIINP) and collagen type I carboxy-terminal telopeptide (ICTP) reflect collagen synthesis and degradation. We studied their predictive value for future death and disease. METHODS: A total of 3068 men and women in the Multi-Ethnic Study of Atherosclerosis who were free of cardiovascular disease (CVD) and in generally good health had a baseline blood sample taken for ICTP and PIIINP. Median follow-up was 13.0 years. Among 4 primary outcomes, CVD events (n = 697) were adjudicated, death (n = 571) was by death certificate, and chronic inflammatory-related severe hospitalization and death (ChrIRD, n = 726) and total cancer (n = 327) were classified using International Classification of Diseases codes. We used Poisson regression to study baseline ICTP and PIIINP relative to these outcomes. RESULTS: Mean (SD) PIIINP was 5.47 (1.95) µg/L and ICTP was 3.37 (1.70) µg/L. PIIINP and ICTP were highly correlated with each other and with estimated glomerular filtration rate (eGFR). Adjustment for age and eGFR attenuated relative risks, remaining 20%-30% per SD of both PIIINP and ICTP in prediction for total death and ChrIRD, and of PIIINP for cancer, with little additional attenuation by adjusting for risk factors and inflammatory biomarkers. CVD outcome was generally unrelated to PIIINP but became marginally inversely related to ICTP in the most adjusted model. CONCLUSIONS: The collagen biomarkers PIIINP and ICTP, in part through pathophysiologically parallel associations with renal function, predicted ChrIRD and total death. Moreover, PIIINP predicted future cancer. These collagen markers may help differentiate healthy from unhealthy aging.

Comparison of the Predictive Value of GlycA and Other Biomarkers of Inflammation for Total Death, Incident Cardiovascular Events, Noncardiovascular and Noncancer Inflammatory-Related Events, and Total Cancer Events.

BACKGROUND: GlycA is a biomarker that reflects integrated concentrations and glycosylation states of several acute-phase proteins. We studied the association of GlycA and inflammatory biomarkers with future death and disease. METHODS: A total of 6523 men and women in the Multi-Ethnic Study of Atherosclerosis who were free of overt cardiovascular disease (CVD) and in generally good health had a baseline blood sample taken. We assayed high-sensitivity C-reactive protein (hsCRP), interleukin-6 (IL-6), and d-dimer. A spectral deconvolution algorithm was used to quantify GlycA signal amplitudes from automated nuclear magnetic resonance (NMR) LipoProfile® test spectra. Median follow-up was 12.1 years. Among 4 primary outcomes, CVD events were adjudicated, death was by death certificate, and chronic inflammatory-related severe hospitalization and death (ChrIRD) and total cancer were classified using International Classification of Diseases (ICD) codes. We used Poisson regression to study baseline GlycA, hsCRP, IL-6, and d-dimer in relation to total death, CVD, ChrIRD, and total cancer. RESULTS: Relative risk per SD of GlycA, IL-6, and d-dimer for total death (n = 915); for total CVD (n = 922); and for ChrIRD (n = 1324) ranged from 1.05 to 1.20, independently of covariates. In contrast, prediction from hsCRP was statistically explained by adjustment for other inflammatory variables. Only GlycA was predictive for total cancer (n = 663). Women had 7% higher values of all inflammatory biomarkers than men and had a significantly lower GlycA prediction coefficient than men in predicting total cancer. CONCLUSIONS: The composite biomarker GlycA derived from NMR is associated with risk for total death, CVD, ChrIRD, and total cancer after adjustment for hsCRP, IL-6, and d-dimer. IL-6 and d-dimer contribute information independently of GlycA.

Oxidative stress, inflammation, endothelial dysfunction and incidence of type 2 diabetes.

BACKGROUND: Oxidative stress, inflammation and endothelial dysfunction are interrelated factors in the etiology of cardiovascular disease, but their linkage to type 2 diabetes is less clear. We examined the association of these biomarkers with incident type 2 diabetes (T2D). METHODS: Analysis of 2339 participants in the community-based coronary artery risk development in young adults (CARDIA) study. Participants (age 40.1 ± 3.6 years, 44 % Black, 58 % women) were free of diabetes, and were followed 10 years. Cox regression was used to estimate hazard ratios (HRs) for incident T2D adjusting for the other biomarkers under study, demographic and lifestyle measures, dietary biomarkers, BMI (kg/m(2)) and metabolic syndrome components. RESULTS: F2-isoprostanes and oxidized LDL (oxidative stress) were positively associated with incident T2D, but the associations were attenuated by adjustment for BMI. C-reactive protein was positively associated with T2D even with full adjustment: HR (95 % CI) = 2.21 (1.26-3.88) for quartile 4 (Q4) v. quartile 1 (Q1). The HR (95 % CI) for T2D for biomarkers of endothelial dysfunction ICAM-1 and E-selectin for Q4 v. Q1 were 1.64 (0.96-2.81) and 1.68 (1.04-2.71) respectively, with full adjustment. Including these two markers in a common risk score incorporating BMI and clinical measures improved the prediction probability of T2D: relative risk for the average person classified up compared to the average person classified down: 1.09, (1.06-1.13), P < 0.0001. CONCLUSIONS: Biomarkers of inflammation and endothelial dysfunction were positively associated with incident T2D. ICAM-1 and E-selectin add to the prediction of T2D beyond a common risk score.

Serial measurement of N-terminal pro-B-type natriuretic peptide and cardiac troponin T for cardiovascular disease risk assessment in the Multi-Ethnic Study of Atherosclerosis (MESA).

BACKGROUND: N-terminal-pro-B-type natriuretic peptide (NT-proBNP) and cardiac troponin T (TnT) predict cardiovascular disease (CVD) risk in a variety of populations. Whether their predictive value varies by ethnicity is unknown. We sought to determine whether NT-proBNP and TnT improve prediction of incident coronary heart disease (CHD) and CVD, independent of CVD risk factors, in a multiethnic population; whether NT-proBNP improves prediction compared with the Framingham Risk Score or the Pooled Cohort Risk Equation; and whether a second NT-proBNP further improves prediction. METHODS: Both NT-proBNP and TnT were measured in 5,592 MESA white, black, Hispanic, and Chinese participants (60% nonwhite; mean age 62.3 ± 10.3 years) in 2000 to 2002 and 2004 to 2005. We evaluated adjusted risk of incident CHD and CVD based on baseline and change in biomarker concentration. RESULTS: Participants were followed up through 2011 and incurred 370 CVD events (232 CHD). Concentrations of NT-proBNP and TnT varied by ethnicity. Both NT-proBNP and TnT were associated with an increased risk of events (adjusted hazard ratio [HR] for CHD [95% CI] for fifth quintile vs other 4 quintiles of NT-proBNP, 2.03 [1.50-2.76]; HR for CHD for detectable vs undetectable TnT, 3.95 [2.29-6.81]). N-terminal-pro-B-type natriuretic peptide improved risk prediction and classification compared with the Framingham Risk Score and the Pooled Cohort Risk Equation. Change in NT-proBNP was independently associated with events (HR for CHD per unit increase in ΔlogNT-proBNP, 1.95 [1.16-3.26]). None of the observed associations varied by ethnicity. CONCLUSIONS: Both NT-proBNP and TnT are predictors of incident CHD, independent of established risk factors and ethnicity, in a multiethnic population without known CVD. Change in NT-proBNP may add additional prognostic information.

Glucose autoxidation induces functional damage to proteins via modification of critical arginine residues.

Nonenzymatic modification of proteins in hyperglycemia is a major mechanism causing diabetic complications. These modifications can have pathogenic consequences when they target active site residues, thus affecting protein function. In the present study, we examined the role of glucose autoxidation in functional protein damage using lysozyme and RGD-α3NC1 domain of collagen IV as model proteins in vitro. We demonstrated that glucose autoxidation induced inhibition of lysozyme activity as well as NC1 domain binding to α(V)ß(3) integrin receptor via modification of critical arginine residues by reactive carbonyl species (RCS) glyoxal (GO) and methylglyoxal while nonoxidative glucose adduction to the protein did not affect protein function. The role of RCS in protein damage was confirmed using pyridoxamine which blocked glucose autoxidation and RCS production, thus protecting protein function, even in the presence of high concentrations of glucose. Glucose autoxidation may cause protein damage in vivo since increased levels of GO-derived modifications of arginine residues were detected within the assembly interface of collagen IV NC1 domains isolated from renal ECM of diabetic rats. Since arginine residues are frequently present within protein active sites, glucose autoxidation may be a common mechanism contributing to ECM protein functional damage in hyperglycemia and oxidative environment. Our data also point out the pitfalls in functional studies, particularly in cell culture experiments, that involve glucose treatment but do not take into account toxic effects of RCS derived from glucose autoxidation.

Postmaximal contraction blood volume responses are blunted in obese and type 2 diabetic subjects in a muscle-specific manner.

The purpose of this study was to determine whether there are differences in postisometric contraction blood volume and oxygenation responses among groups of type 2 diabetes mellitus (T2DM), obese, and lean individuals detectable using MRI. Eight T2DM patients were individually matched by age, sex, and race to non-T2DM individuals with similar body mass index (obese) and lean subjects. Functional MRI was performed using a dual-gradient-recalled echo, echo-planar imaging sequence with a repetition time of 1 s and at two echo times (TE = 6 and 46 ms). Data were acquired before, during, and after 10-s isometric dorsiflexion contractions performed at 50 and 100% of maximal voluntary contraction (MVC) force. MRI signal intensity (SI) changes from the tibialis anterior and extensor digitorum longus muscles were plotted as functions of time for each TE. From each time course, the difference between the minimum and the maximum postcontraction SI (ΔSI) were determined for TE = 6 ms (ΔSI(6)) and TE = 46 ms (ΔSI(46)), reflecting variations in blood volume and oxyhemoglobin saturation, respectively. Following 50% MVC contractions, the mean postcontraction ΔSI(6) values were similar in the three groups. Following MVC only, and in the EDL muscle only, T2DM and obese participants had ∼56% lower ΔSI(6) than the lean individuals. Also following MVC only, the ΔSI(46) response in the EDL was lower in T2DM subjects than in lean individuals. These data suggest that skeletal muscle small vessel impairment occurs in T2DM and body mass index-matched subjects, in muscle-specific and contraction intensity-dependent manners.

Absence of a significant extravascular contribution to the skeletal muscle BOLD effect at 3 T.

Blood oxygenation level dependent (BOLD) contrast in skeletal may reflect the contributions of both intravascular and extravascular relaxation effects. The purpose of this study was to determine the significance of the extravascular BOLD effect in skeletal muscle at 3 T. In experiments, R(2)* was measured before and during arterial occlusion under the following conditions: (1) the leg extended and rotated (to vary the capillary orientation with respect to the amplitude of static field) and (2) with the blood's signal nulled using a multiecho vascular space occupancy experiment. In the leg rotation protocol, 3 min of arterial occlusion decreased oxyhemoglobin saturation from 67% to 45% and increased R(2)* from 34.2 to 36.6 sec(-1), but there was no difference in the R(2)* response to occlusion between the extended and rotated positions. Numerical simulations of intra- and extravascular BOLD effects corresponding to these conditions predicted that the intravascular BOLD contribution to the R(2)* change was always > 50 times larger than the extravascular BOLD contribution. Blood signal nulling eliminated the change in R(2)* caused by arterial occlusion. These data indicate that under these experimental conditions, the contribution of the extravascular BOLD effect to skeletal muscle R(2)* was too small to be practically important.

Coronary artery calcium progresses rapidly and discriminates incident cardiovascular events in chronic kidney disease regardless of diabetes: The Multi-Ethnic Study of Atherosclerosis (MESA).

BACKGROUND AND AIMS: Chronic kidney disease (CKD) is associated with high prevalence of cardiovascular disease (CVD) events. We sought to assess the prognostic utility of coronary artery calcium (CAC) scores in discriminating incident CVD events among subpopulations of CKD, particularly those without diabetes mellitus (DM). METHODS: Using the Multi-Ethnic Study of Atherosclerosis, we identified 4 groups based on present/absent CKD/diabetes (CKD-/DM-, n = 5308; CKD-/DM+, n = 586, CKD+/DM-, n = 620; CKD+/DM+, n = 266). Baseline and follow-up CAC (Agatston units) measurements, and association between CAC and incident CVD events in median follow-up of 13 years were evaluated using proportional hazards regression adjusting for demographics, clinical, biomarker variables. RESULTS: Prevalence of CKD and DM in the cohort was 13% and 12.5% respectively. Annual progression in adjusted median CAC score was 24.8%, 27.9%, 26.7%, 36.8% and unadjusted cumulative incident CVD rates were 12.6%, 22.3%, 23.1%, 39.8% for CKD-/DM-, CKD-/DM+, CKD+/DM-, CKD+/DM+, respectively. After full adjustment (CKD-/DM-referent), hazard ratios (HR, 95% CI) for incident CVD events were 1.25 (1.01-1.53) CKD-/DM+, 1.10 (0.90-1.33) CKD+/DM- and 2.18 (1.73-2.76) CKD+/DM+. Using CKD-/DM-/baseline CAC = 0 referent, adjusted HRs (95% CI) for incident CVD in CKD+/DM- were 1.30 (0.81-2.07), 2.05 (1.4-2.99), and 4.15 (2.94-5.86) for baseline CAC = 0, 1-100, and >300 Agatston units respectively while for CKD+/DM+, adjusted HRs were 3.15 (2.04-4.86), 3.56 (2.26-5.62), 7.90 (5.35-11.67), respectively. CONCLUSIONS: CAC provides incremental prognostic information to predict incident CVD events in CKD regardless of DM. Moreover, baseline CAC categories discriminate incident CVD among CKD without DM, which may have implications in individualizing approach to primary prevention in this high-risk population.

Change in NT-proBNP (N-Terminal Pro-B-Type Natriuretic Peptide) Level and Risk of Dementia in Multi-Ethnic Study of Atherosclerosis (MESA).

Cross-sectionally measured NT-proBNP (N-terminal pro-B-type natriuretic peptide) is related to incident dementia. However, data linking changes in NT-proBNP to risk of future dementia are lacking. We aimed to examine the association of change in NT-proBNP over 3.2 years with incident dementia. We included 4563 participants in MESA (Multi-Ethnic Study of Atherosclerosis) prospective cohort who were free of cardiovascular disease at enrollment, had NT-proBNP level measured at MESA exams 1 (baseline, 2000-2002) and 3 (2004-2005), and had no diagnosis of dementia before exam 3. The association of change in NT-proBNP level between MESA exams 1 through 3 and all-cause hospitalized dementia (by International Classification of Diseases, Ninth Revision, codes) after MESA exam 3 (2004-2005) through 2015 was assessed using competing-risks Cox proportional hazard regression analysis. During 45 522 person-years of follow-up, 223 dementia cases were documented. Increase in log-NT-proBNP from MESA exams 1 through 3 was positively associated with incidence of dementia (multivariable hazard ratio, 1.28 [95% CI, 1.001-1.64]; P=0.049). An increase of at least 25% in NT-proBNP level from MESA exam 1 through 3 was associated with a 55% (P=0.02) increase in the risk of dementia in multivariable analysis. Addition of temporal NT-proBNP change to a model including risk factors and baseline NT-proBNP improved the prediction of dementia (Harrell C statistic from 0.85 to 0.87, P=0.049). Increase in NT-proBNP is independently associated with future all-cause hospitalized dementia and offers a moderately better predictive performance for risk of dementia compared with risk factors and baseline NT-proBNP. Clinical Trial Registration- URL: https://www.clinicaltrials.gov. Unique identifier: NCT00005487.

N-Terminal pro-Brain Natriuretic Peptide and Associations With Brain Magnetic Resonance Imaging (MRI) Features in Middle Age: The CARDIA Brain MRI Study.

OBJECTIVE: As part of research on the heart-brain axis, we investigated the association of N-terminal pro-brain natriuretic peptide (NT-proBNP) with brain structure and function in a community-based cohort of middle-aged adults from the Brain Magnetic Resonance Imaging sub-study of the Coronary Artery Risk Development in Young Adults (CARDIA) Study. APPROACH AND RESULTS: In a cohort of 634 community-dwelling adults with a mean (range) age of 50.4 (46-52) years, we examined the cross-sectional association of NT-proBNP to total, gray (GM) and white matter (WM) volumes, abnormal WM load and WM integrity, and to cognitive function tests [the Digit Symbol Substitution Test (DSST), the Stroop test, and the Rey Auditory-Verbal Learning Test]. These associations were examined using linear regression models adjusted for demographic and cardiovascular risk factors and cardiac output. Higher NT-proBNP concentration was significantly associated with smaller GM volume (ß = -3.44; 95% CI = -5.32, -0.53; p = 0.003), even after additionally adjusting for cardiac output (ß = -2.93; 95% CI = -5.32, -0.53; p = 0.017). Higher NT-proBNP levels were also associated with lower DSST scores. NT-proBNP was not related to WM volume, WM integrity, or abnormal WM load. CONCLUSION: In this middle-aged cohort, subclinical levels of NT-proBNP were related to brain function and specifically to GM and not WM measures, extending similar findings in older cohorts. Further research is warranted into biomarkers of cardiac dysfunction as a target for early markers of a brain at risk.

Computerized tomography measured liver fat is associated with low levels of N-terminal pro-brain natriuretic protein (NT-proBNP). Multi-Ethnic Study of Atherosclerosis.

BACKGROUND AND AIMS: N-terminal pro B-type natriuretic peptide (NT-proBNP) is inversely associated with diabetes mellitus, obesity and metabolic syndrome. We aim to characterize the association between NT-proBNP and nonalcoholic fatty liver disease (NAFLD), a condition strongly associated with metabolic syndrome. METHODS: 4529 participants from the Multi-Ethnic Study of Atherosclerosis (MESA) free of cardiovascular disease, without self-reported liver disease and not diabetic at their baseline visit in 2000-2002 were included in this analysis. NAFLD was defined by a liver attenuation <40 HU. Relative prevalence (RP) for NAFLD was assessed adjusted for age, race, and sex, percentage of dietary calories derived from fat, total intentional exercise, alcoholic drinks per week, and interleukin-6 by quintiles of NT-proBNP. Adjusted linear spline model was used to characterize a non-linear association between NT-proBNP and liver fat. The inflection point (IP) was the NT-proBNP concentration where there was a change in slope in the association between liver attenuation and NT-proBNP. RESULTS: RP for NAFLD decreased by 30% from the lowest to the highest quintile of NT-proBNP, p=0.01. We observed an inverse linear association between NT-proBNP and liver fat, which plateaued (IP) at an NT-proBNP concentration of 45pg/mL. Linear regression coefficient (SE) per unit of NT-proBNP less than and greater than or equal to IP was of 0.05 (0.02), p=0.001 and 0.0006 (0.0008), p=0.5, respectively; differences between slopes, p<0.0001. CONCLUSIONS: In this cross-sectional study of a community based multiethnic sample of non-diabetic adults, low levels of NT-proBNP are associated with greater prevalence of NAFLD.

Effects of endurance exercise-training on single-fiber contractile properties of insulin-treated streptozotocin-induced diabetic rats.

The purpose of this study was to characterize the contractile properties of individual skinned muscle fibers from insulin-treated streptozotocin-induced diabetic rats after an endurance exercise training program. We hypothesized that single-fiber contractile function would decrease in the diabetic sedentary rats and that endurance exercise would preserve the function. In the study, 28 rats were assigned to either a nondiabetic sedentary, a nondiabetic exercise, a diabetic sedentary, or a diabetic exercise group. Rats in the diabetic groups received subcutaneous intermediate-lasting insulin daily. The exercise-trained rats ran on a treadmill at a moderate intensity for 60 min, five times per week. After 12 wk, the extensor digitorum longus and soleus muscles were dissected. Single-fiber diameter, Ca(2+)-activated peak force, specific tension, activation threshold, and pCa(50) as well as the myosin heavy chain isoform expression (MHC) were determined. We found that in MHC type II fibers from extensor digitorum longus muscle, diameters were significantly smaller from diabetic sedentary rats compared with nondiabetic sedentary rats (P < 0.001). Among the nondiabetic rats, fiber diameters were smaller with exercise (P = 0.038). The absolute force-generating capacity of single fibers was lower in muscles from diabetic rats. There was greater specific tension (force normalized to cross-sectional area) by fibers from the rats that followed an endurance exercise program compared with sedentary. From the results, we conclude that alterations in the properties of contractile proteins are not implicated in the decrease in strength associated with diabetes and that endurance-exercise training does not prevent or increase muscle weakness in diabetic rats.

Myosin heavy chain isoform immunolabelling in diabetic rats with peripheral neuropathy.

This study evaluated mature and immature myosin heavy chain (MHC) isoform immunolocalisation in soleus muscle of diabetic rats with documented motor neuropathy. Sprague Dawley rats were assigned to one of three groups: control (C), diabetic with insulin (DI), or diabetic without insulin (DNI). Twelve weeks after diabetes induction, soleus muscles were excised and quick-frozen. Cross-sections were labelled immunohistochemically for slow, fast, developmental and neonatal MHC isoforms to determine fiber-type composition. Fiber cross-sectional areas were determined morphometrically. Results revealed that DNI and DI muscles contained greater percentages of myofibers positive for fast MHC compared with controls. DNI animals also showed a lower percentage of myofibers positive for slow MHC compared to the DI group. The number of fibers immunolabelled for developmental MHC isoforms was greater in DNI animals than in the other groups. The differences in slow and fast MHC-labelling appear to indicate a condition of altered neuromuscular activity affecting the diabetic muscles. The increase in developmental MHC-labelling in the DNI muscles could indicate myofiber regeneration or reinnervation that would be more pronounced in the DNI animals in context of their more severe neuropathy. Insulin appeared to influence muscle fiber cross-sectional area and possibly fiber-type grouping frequency; the potential mechanism for these effects was not elucidated.

Pyridoxamine protects proteins from damage by hypohalous acids in vitro and in vivo.

Diabetes is characterized, in part, by activation of toxic oxidative and glycoxidative pathways that are triggered by persistent hyperglycemia and contribute to diabetic complications. Inhibition of these pathways may benefit diabetic patients by delaying the onset of complications. One such inhibitor, pyridoxamine (PM), had shown promise in clinical trials. However, the mechanism of PM action in vivo is not well understood. We have previously reported that hypohalous acids can cause disruption of the structure and function of renal collagen IV in experimental diabetes (K.L. Brown et al., Diabetes 64:2242-2253, 2015). In the present study, we demonstrate that PM can protect protein functionality from hypochlorous and hypobromous acid-derived damage via a rapid direct reaction with and detoxification of these hypohalous acids. We further demonstrate that PM treatment can ameliorate specific hypohalous acid-derived structural and functional damage to the renal collagen IV network in a diabetic animal model. These findings suggest a new mechanism of PM action in diabetes, namely sequestration of hypohalous acids, which may contribute to known therapeutic effects of PM in human diabetic nephropathy.

Usefulness of N-terminal Pro-brain Natriuretic Peptide and Myocardial Perfusion in Asymptomatic Adults (from the Multi-Ethnic Study of Atherosclerosis).

This study sought to investigate the relation between myocardial perfusion and N-terminal pro-brain natriuretic peptide (NT-proBNP) in asymptomatic adults without overt coronary artery disease. NT-proBNP is a cardiac neurohormone secreted from the ventricles in response to ventricular volume expansion and pressure overload and may also be elevated in the setting of reduced myocardial perfusion. We hypothesized that reduced myocardial perfusion reserve (MPR) would be associated with elevated NT-proBNP in participants free of overt cardiovascular disease. MPR was measured by cardiac magnetic resonance, before and after adenosine infusion, in 184 MESA participants (mean age 60 ± 10.4, 58% white, 42% Hispanic, 44% women) without overt cardiovascular disease. MPR was modeled as hyperemic myocardial blood flow (MBF) adjusted for MBF at rest. A linear regression analysis, adjusted for demographics, established cardiovascular risk factors, left ventricular mass, coronary calcium score, body mass index, and medications, was used to determine the association between MPR and NT-proBNP. Participants with low hyperemic MBF were more likely to be older, male, diabetic, and have higher blood pressure and higher coronary artery calcium score. Mean hyperemic MBF was 3.04 ± 0.829 ml/min/g. MPR was inversely associated with NT-proBNP levels. In a fully adjusted model, every 1-SD decrement in MPR was associated with a 21% increment in NT-proBNP (p = 0.04). In conclusion, MPR is inversely associated with NT-proBNP level in this cross-sectional study of asymptomatic adults free of overt coronary artery disease, suggesting that higher NT-proBNP levels may reflect subclinical myocardial microvascular dysfunction.

Increasing aminoterminal-pro-B-type natriuretic peptide precedes the development of arterial hypertension: the multiethnic study of atherosclerosis.

BACKGROUND: Longitudinal associations between the aminoterminal pro-B-type natriuretic peptide (NT-proBNP) and incident hypertension are lacking. METHODS: We tested associations between baseline NT-proBNP (bNT-proBNP) and change in NT-proBNP (ΔNT-proBNP) (visit 3 NT-proBNP - bNT-proBNP, 3.2 years apart) with incident hypertension (SBP ≥ 140 and/or DBP ≥90 mmHg or taking antihypertensive medications). Incident hypertension was evaluated in 5596 individuals in the Multi-Ethnic Study of Atherosclerosis without hypertension at baseline (53% women, age range 45-84 years without overt cardiovascular disease) and follow-up for 9.5 years and in a subgroup (1550) who had bNT-proBNP less than 100 pg/ml and no hypertension at visit 3. Incident hypertension was regressed (proportional hazards) on quintiles of bNT-proBNP (range) (reference <19.2, 19.3-40.8, 40.9-70.9, 71-135.2, and >135.5) and also on ΔNT-proBNP categories (reference <-10, -10 to 10, >10 to 50, and >50 pg/ml). Hazard ratios were adjusted for age, race, sex, education, diabetes, obesity, left ventricle mass/height, SBP and DBP, interleukin-6, salt intake, estimated glomerular filtration rate, and exercise. RESULTS: Compared with the reference category, hazard ratios (95% confidence interval) for incident hypertension compared with the first quintile of bNT-proBNP were 1.47 (1.13-1.93), 1.57 (1.18-2.09), 1.52 (1.12-2.06), and 2.36 (1.62-3.41). Hazard ratios for incident hypertension by categories of ΔNT-proBNP from 3.2 to 9.5 years follow-up were 0.98 (0.62-1.56), 1.13 (0.72-1.79), and 1.82 (1.07-3.12). CONCLUSION: The development of hypertension tended to be preceded by elevated levels of bNT-proBNP or a substantial positive ΔNT-proBNP.

The association between N-terminal pro B-type natriuretic peptide and lipoprotein particle concentration plateaus at higher N-terminal pro B-type natriuretic peptide values: Multi-Ethnic Study on Atherosclerosis.

BACKGROUND: The association between N-terminal pro B-type natriuretic peptide (NT-proBNP) and blood levels of small and large LDL- and HDL- particle (P) concentration may not be linear throughout the whole range of NT-proBNP values. METHODS: Linear spline regression analysis between NT-proBNP and lipoprotein particle concentrations was performed cross-sectionally in 5597 individuals from the Multi-Ethnic Study of Atherosclerosis adjusted for age, race, sex, body mass index, % of energy from saturated fats, intentional exercise, statin use, antihypertensive medication use, diabetes, IL-6 and estimated glomerular filtration rate. Spline knots were selected as the point at which the linear slope changed in these associations. RESULTS: NT-proBNP was positively associated with large LDL-P and HDL-P, but inversely associated with small LDL-P and HDL-P, but only for NT-proBNP values below the knot (range: 100-200 pg/mL). CONCLUSION: These results suggest the presence of two distinct biological mechanisms above and below the knot determining the association between NT-proBNP and lipoprotein particle concentrations.