The Prognostic Role of Serum β-Trace Protein Levels among Patients on Maintenance Hemodialysis

Cardiovascular (CV) diseases are the most commonly encountered etiology of mortality in patients having kidney failure. β-Trace protein (BTP) is a biomarker of glomerular filtration function as well as a potential predictor of adverse CV outcomes. This study aimed to determine the prognostic value of BTP in patients on chronic hemodialysis (HD). A total of 96 patients undergoing HD were enrolled. Baseline variables were collected, and the patients were tracked for 3 years. Twenty-five patients died at 3 years. Those who experienced mortality were noted to have higher serum concentrations of BTP and a higher incidence of diabetes mellitus (DM). The area under the receiver operating characteristic curve for serum BTP distinguishing mortality from survival was 0.659 (95% confidence interval [CI], 0.555-0.752; p = 0.027). After the adjustment of variables potentially affecting survival rates, BTP levels above the median (adjusted hazard ratio [aHR]: 2.913, 95% CI, 1.256-6.754; p = 0.013), the presence of DM (aHR: 2.474, 95% CI, 1.041-5.875; p = 0.040), and low serum albumin (aHR: 0.298, 95% CI, 0.110-0.806; p = 0.017) independently correlated with survival in HD patients. Serum BTP is a novel biomarker for predicting overall outcomes in HD patients.

Plasma proteomics of diabetic kidney disease among Asians with younger-onset type 2 diabetes

CONTEXT

Patients with younger onset of type 2 diabetes (YT2D) have increased risk for kidney failure compared to those with late onset. However, the mechanism of diabetic kidney disease (DKD) progression in this high-risk group is poorly understood.

OBJECTIVES

To identify novel biomarkers and potential causal proteins associated with DKD progression in patients with YT2D.

DESIGN AND PARTICIPANTS

Among YT2D (T2D onset age ≤ 40 years), 144 DKD progressors (cases) were matched for T2D onset age, sex, and ethnicity with 292 non-progressors (controls) and divided into discovery and validation sets. DKD progression was defined as decline of estimated glomerular filtration rate (eGFR) of 3ml/min/1.73m2 or greater or 40% decline in eGFR from baseline. 1472 plasma proteins were measured through a multiplex immunoassay that uses a proximity extension assay technology. Multivariable logistic regression was used to identify proteins associated with DKD progression. Mendelian randomization (MR) was used to evaluate causal relationship between plasma proteins and DKD progression.

RESULTS

42 plasma proteins were associated with DKD progression, independent of traditional cardio-renal risk factors, baseline eGFR and urine albumin-to-creatinine ratio (uACR). The proteins identified were related to inflammatory and remodelling biological processes. Our findings suggested angiogenin as one of the top signals (odds ratio =5.29, 95% CI 2.39-11.73, P = 4.03 × 10-5). Furthermore, genetically determined plasma angiogenin level was associated with increased odds of DKD progression.

CONCLUSION

Large-scale proteomic analysis identified novel proteomic biomarkers for DKD progression in YT2D. Genetic evidence suggest a causal role of plasma angiogenin in DKD progression.

Biological variation data for kidney function related parameter: serum beta trace protein, creatinine and cystatin C from 22 apparently healthy Turkish subjects

OBJECTIVES

Biological variation is defined as the variation in analytical concentration between and within individuals, and being aware of this biological variation is important for understanding disease dynamics. The aim of our study is to calculate the within-subject (CV_I) and between-subject (CV_G) biological variations of serum creatinine, cystatin C and Beta trace protein (BTP), as well as the reference change value (RCV) and individuality indexes (II), which are used to calculate the glomerular filtration rate while evaluating kidney damage.

METHODS

Blood samples were collected from 22 healthy volunteers for 10 consecutive weeks and stored at -80 °C until the day of analysis. While the analysis for serum creatinine was performed colorimetrically with the kinetic jaffe method, the nephelometric method was employed for cystatin C and BTP measurements. All analyses were carried out in a single session for each test.

RESULTS

Analytical coefficient of variation (CV_A) for serum creatinine, cystatin C and beta trace protein was 5.56, 3.48 and 5.37%, respectively. CV_I and CV_G: for serum creatinine: 3.31, 14.50%, respectively, for cystatin C: 3.15, 12.24%, respectively, for BTP: 9.91, 14.36%, respectively. RCV and II were calculated as 17.94%, 0.23 for serum creatinine, 13.01%, 0.26 for cystatin C, 31.24%, 0.69 for BTP, respectively.

CONCLUSIONS

According to the data obtained in our study, serum creatinine and cystatin C show high individuality, therefore we think that the use of RCV instead of reference ranges would be appropriate. Although II is found to be low for BTP, more studies are needed to support this finding.

Proteins Associated with Risk of Kidney Function Decline in the General Population

BACKGROUND

Proteomic profiling may allow identification of plasma proteins that associate with subsequent changesin kidney function, elucidating biologic processes underlying the development and progression of CKD.

METHODS

We quantified the association between 4877 plasma proteins and a composite outcome of ESKD or decline in eGFR by ≥50% among 9406 participants in the Atherosclerosis Risk in Communities (ARIC) Study (visit 3; mean age, 60 years) who were followed for a median of 14.4 years. We performed separate analyses for these proteins in a subset of 4378 participants (visit 5), who were followed at a later time point, for a median of 4.4 years. For validation, we evaluated proteins with significant associations (false discovery rate <5%) in both time periods in 3249 participants in the Chronic Renal Insufficiency Cohort (CRIC) and 703 participants in the African American Study of Kidney Disease and Hypertension (AASK). We also compared the genetic determinants of protein levels with those from a meta-analysis genome-wide association study of eGFR.

RESULTS

In models adjusted for multiple covariates, including baseline eGFR and albuminuria, we identified 13 distinct proteins that were significantly associated with the composite end point in both time periods, including TNF receptor superfamily members 1A and 1B, trefoil factor 3, and β-trace protein. Of these proteins, 12 were also significantly associated in CRIC, and nine were significantly associated in AASK. Higher levels of each protein associated with higher risk of 50% eGFR decline or ESKD. We found genetic evidence for a causal role for one protein, lectin mannose-binding 2 protein (LMAN2).

CONCLUSIONS

Large-scale proteomic analysis identified both known and novel proteomic risk factors for eGFR decline.

Beta-trace protein as a potential biomarker of residual renal function in patients undergoing peritoneal dialysis

Background

Residual renal function is closely linked to quality of life, morbidity and mortality in dialysis patients. Beta-trace protein (BTP), a low molecular weight protein, has been suggested as marker of residual renal function, in particular in patients on hemodialysis. We hypothesized that BTP also serves as a marker of residual renal function in pertioneal dialysis patients.

Methods

In this study 34 adult patients on peritoneal dialysis were included. BTP, creatinine, cystatin C and urea concentrations were analyzed simultaneously in serum and dialysate to calculate renal and peritoneal removal of the analytes.

Results

In peritoneal dialysis patients with residual diuresis, mean serum BTP was 8.16 mg/l (SD ± 4.75 mg/l). BTP correlated inversely with residual diuresis (r_s = − 0.58, p < 0.001), residual creatinine clearance (Cl_Cr) (r_s = − 0.69, p < 0.001) and total urea clearance (Cl_urea) (r_s = − 0.56, p < 0.001). Mean peritoneal removal of BTP was 3.36 L/week/1.73m² (SD ± 1.38) and mean renal removal 15.14 L/week/1.73m² (SD ± 12.65) demonstrating a significant renal contribution to the total removal. Finally, serum BTP inversely correlated with alterations in residual diuresis (r = − 0.41, p = 0.035) and renal creatinine clearance over time (r = − 0.79, p = p < 0.001).

Conclusion

BTP measurement in the serum may be a simple tool to assess residual renal function in peritoneal dialysis patients.

A Review of Specific Biomarkers of Chronic Renal Injury and Their Potential Application in Nonclinical Safety Assessment Studies

A host of novel renal biomarkers have been developed over the past few decades which have enhanced monitoring of renal disease and drug-induced kidney injury in both preclinical studies and in humans. Since chronic kidney disease (CKD) and acute kidney injury (AKI) share similar underlying mechanisms and the tubulointerstitial compartment has a functional role in the progression of CKD, urinary biomarkers of AKI may provide predictive information in chronic renal disease. Numerous studies have explored whether the recent AKI biomarkers could improve upon the standard clinical biomarkers, estimated glomerular filtration rate (eGFR), and urinary albumin to creatinine ratio, for predicting outcomes in CKD patients. This review is an introduction to alternative assays that can be utilized in chronic (>3 months duration) nonclinical safety studies to provide information on renal dysfunction and to demonstrate specific situations where these assays could be utilized in nonclinical drug development. Novel biomarkers such as symmetrical dimethyl arginine, dickkopf homolog 3, and cystatin C predict chronic renal injury in animals, act as surrogates for GFR, and may predict changes in GFR in patients over time, ultimately providing a bridge from preclinical to clinical renal monitoring.

The Effect of Beta-Trace Protein on Diagnosis and Prognosis in Patients with Acute Coronary Syndrome

Objective

The purpose of this study was to determine the effect of beta-trace protein (BTP) levels at the time of admission and at 8th hour on diagnosis and prognosis in patients who were under treatment and follow-up with acute coronary syndrome (ACS) diagnosis at coronary intensive care unit and emergency department.

Materials and Methods

This study was conducted between June 2014 and December 2014 at the Emergency Department of Konya Training and Research Hospital. Demographic characteristics, background, vital findings, laboratory findings, blood BTP levels, coronary angiography results, and echocardiography findings of the patients diagnosed with ACS were recorded. Risk classification was performed for patients with ACS and their mortality rates were recorded. Relation of BTP level with risk classification and mortality was evaluated.

Results

A total of 174 individuals, 138 patients and 36 control subjects, were included in the study. No significant difference was detected between BTP levels at the time of admission and at 8^th hour in the patient group (p=0.883). There was no difference between the patient and control groups in terms of the BTP level (p=0.335). Ten patients (7.2%) died in the patient group. BTP levels measured at the time of admission and at 8th hour were not different for dead and living patients (admission p=0.085, 8^th hour p=0.141).

Conclusion

We determined that there was a lack of biochemical markers that could be used for the prognosis of serum BTP levels in patients admitting to the emergency unit with ACS.

Does Beta-Trace Protein (BTP) Outperform Cystatin C as a Diagnostic Marker of Acute Kidney Injury Complicating the Early Phase of Acute Pancreatitis?

Acute pancreatitis (AP) belongs to the commonest acute gastrointestinal conditions requiring hospitalization. Acute kidney injury (AKI) often complicates moderately severe and severe AP, leading to increased mortality. Among the laboratory markers proposed for early diagnosis of AKI, few have been studied in AP, including cystatin C and neutrophil gelatinase-associated lipocalin (NGAL). Beta-trace protein (BTP), a low-molecular-weight glycoprotein proposed as an early marker of decreased glomerular filtration, has never been studied in AP. We investigated the diagnostic usefulness of serum BTP for early diagnosis of AKI complicating AP in comparison to previously studied markers. BTP was measured in serum samples collected over the first three days of hospital stay from 73 adult patients admitted within 24 h of mild to severe AP. Thirteen patients (18%) developed AKI in the early phase of AP. Serum BTP was higher in patients who developed AKI, starting from the first day of hospitalization. Strong correlations were observed between BTP and serum cystatin C but not serum or urine NGAL. On admission, BTP positively correlated with endothelial dysfunction. The diagnostic usefulness of BTP for AKI was similar to cystatin C and lower than NGAL. Increased BTP is an early predictor of AKI complicating AP. However, it does not outperform cystatin C or NGAL.

Large uremic toxins: an unsolved problem in end-stage kidney disease

Patients with end-stage kidney disease (ESKD) on maintenance hemodialysis are subject to a high burden of inflammation and cardiovascular disease, driven at least in part by retention of uremic solutes. Existing dialysis technologies using high-flux membranes offer limited clearance of solutes >15 kDa. New approaches to improve the removal of large uremic toxins include the novel medium cut-off dialysis membranes with pores larger than those in high-flux membranes. These new membranes provide the potential to improve the clearance of large middle molecules up to 50 kDa. In this review, we discuss 18 uremic toxins with molecular weights between 15 and 60 kDa that are retained in ESKD, for which there is evidence of a link to inflammation and/or cardiovascular disease. These include inflammatory proteins, cytokines, adipokines and other signaling proteins. Improved clearance of this group of difficult to remove molecules has the potential to lead to improved outcomes in dialysis patients by reducing the burden of cardiovascular disease, which now needs to be assessed in robust clinical trials.

How best to estimate glomerular filtration rate? Novel filtration markers and their application

PURPOSE OF REVIEW

Chronic kidney disease is an increasing health burden. Estimating equations using serum concentrations of creatinine and cystatin C facilitate the assessment of kidney function as reflected in estimated glomerular filtration rate (eGFR). Reduced eGFR is associated with increased risk for numerous adverse outcomes and is an important aspect in many clinical situations. However, current equations are suboptimal in some clinical settings. The review focuses on approaches to improve the estimation of GFR and aims to familiarize the reader with the underlying methodological hypotheses how new markers could contribute to improve the overall performance of estimating equations.

RECENT FINDINGS

Low molecular weight proteins such as β-trace-protein and β-2-microglobulin, as well as newly discovered metabolites, show promise as new filtration markers, as they might be beneficial in populations in which creatinine or cystatin C are inaccurate. We propose that the combination of multiple novel markers, alone or in combination with creatinine, cystatin C or demographics, can potentially improve GFR estimation. For special populations such as dialysis patients, separate equations have been developed to estimate residual kidney function.

SUMMARY

Current GFR estimating equations are an essential part of routine clinical practice but have limitations. The use of multiple markers combined in a single equation appears to be the most promising approach. Future research is required to validate proposed equations in diverse populations.

Prospective cohort studies of beta-trace protein and mortality in haemodialysis patients and patients undergoing coronary angiography

Background

Beta-trace protein (BTP) is a low-molecular-weight glycoprotein, which may serve as an endogenous biomarker of kidney function and cardiovascular risk.

Methods

We examined cardiovascular and all-cause mortality according to BTP concentrations in 2962 individuals referred for coronary angiography from the Ludwigshafen Risk and Cardiovascular Health study and in 907 patients with Type 2 diabetes mellitus undergoing haemodialysis from the German Diabetes and Dialysis (4D) study.

Results

Haemodialysis patients had considerably higher median (interquartile range) BTP concentrations [6.00 (4.49-7.96) mg/L] and experienced a 4-fold increased mortality rate compared with coronary angiography patients [BTP concentration: 0.55 (0.44-0.67) mg/L]. After adjustment for age, sex, cardiovascular risk factors and creatinine, 4D patients in the highest quartile (>7.96 mg/L) had a 1.6-fold increased rate of all-cause mortality [hazard ratio (HR) 1.62, 95% confidence interval (CI) 1.19-2.20] compared with the lowest quartile (<4.49 mg/L) (P = 0.002) In patients undergoing coronary angiography, the adjusted HRs (95% CI) for all-cause and cardiovascular mortality were 1.23 (1.0-1.51) and 1.27 (0.99-1.63) in the highest (>0.67 mg/L) compared with the lowest (<0.44 mg/L) quartile (P = 0.043 and 0.062). In both cohorts, the BTP/creatinine ratio was a stronger predictor of all-cause and cardiovascular mortality compared with BTP.

Conclusion

BTP was associated with all-cause mortality independently of renal function in haemodialysis patients. The BTP/creatinine ratio was more predictive for all-cause and cardiovascular mortality in haemodialysis patients and individuals referred for angiography compared with BTP as single marker.

Lipocalin-Like Prostaglandin D Synthase but Not Hemopoietic Prostaglandin D Synthase Deletion Causes Hypertension and Accelerates Thrombogenesis in Mice

Prostaglandin (PG) D₂ is formed by two distinct PGD synthases (PGDS): lipocalin-type PGDS (L-PGDS), which acts as a PGD₂-producing enzyme and as extracellular lipophilic transporter, and hematopoietic PGDS (H-PGDS), a σ glutathione-S-transferase. PGD₂ plays an important role in the maintenance of vascular function; however, the relative contribution of L-PGDS– and H-PGDS–dependent formation of PGD₂ in this setting is unknown. To gain insight into the function played by these distinct PGDS, we assessed systemic blood pressure (BP) and thrombogenesis in L-Pgds and H-Pgds knockout (KO) mice. Deletion of L-Pgds depresses urinary PGD₂ metabolite (PGDM) by ∼35%, whereas deletion of H-Pgds does so by ∼90%. Deletion of L-Pgds, but not H-Pgds, elevates BP and accelerates the thrombogenic occlusive response to a photochemical injury to the carotid artery. HQL-79, a H-PGDS inhibitor, further depresses PGDM in L-Pgds KO mice, but has no effect on BP or on the thrombogenic response. Gene expression profiling reveals that pathways relevant to vascular function are dysregulated in the aorta of L-Pgds KOs. These results indicate that the functional impact of L-Pgds deletion on vascular homeostasis may result from an autocrine effect of L-PGDS–dependent PGD₂ on the vasculature and/or the L-PGDS function as lipophilic carrier protein.

Prostaglandins in the pathogenesis of kidney diseases

Prostaglandins (PGs) are important lipid mediators produced from arachidonic acid via the sequential catalyzation of cyclooxygenases (COXs) and specific prostaglandin synthases. There are five subtypes of PGs, namely PGE2, PGI2, PGD2, PGF2α, and thromboxane A2 (TXA2). PGs exert distinct roles by combining to a diverse family of membrane-spanning G protein-coupled prostanoid receptors. The distribution of these PGs, their specific synthases and receptors vary a lot in the kidney. This review summarized the recent findings of PGs together with the COXs and their specific synthases and receptors in regulating renal function and highlighted the insights into their roles in the pathogenesis of various kidney diseases.

Urinary beta-trace protein gene expression analysis in type 2 diabetes mellitus patients

Objective

To evaluate the gene expression of beta-trace protein in urine of diabetic patients, with no reduction in glomerular filtration rate, which was defined as below 60mL/min/1.73m².

Methods

Type 2 diabetes mellitus patients were recruited, and a group of non-diabetic individuals served as control. Beta-trace protein gene expression was analyzed by quantitative PCR. Blood samples were collected to establish glucose levels and baseline kidney function. Accuracy was analyzed using ROC curves.

Results

Ninety type 2 diabetes mellitus patients and 20 non-diabetic individuals were recruited. The area under the curve was 0.601, sensitivity of 20% and specificity of 89.47%. Among diabetic participants, 18% showed an expression above the cutoff point.

Conclusion

These results of accuracy of beta-trace protein gene expression in urine of diabetic patients are promising, although they did not achieve a higher area under the curve level.

Evaluating the diagnostic value of rescaled β-trace protein in combination with serum creatinine and serum cystatin C in older adults

BACKGROUND

Beta trace protein (BTP) is a novel renal biomarker that has emerged as potential alternative or addition to serum creatinine (Scr) and serum cystatin C (ScysC). We analyzed BTP's diagnostic ability to detect impaired kidney function by rescaling it and we tested whether rescaling BTP allowed us to expand the Full-Age-Spectrum (FAS)-equation to BTP.

METHODS

566 participants aged ≥70 years with measured glomerular filtration rate (mGFR), Scr, ScysC and BTP from the population-based Berlin Initiative Study (BIS) were considered. We developed a single and combined FAS-equation using rescaled BTP (BTP/0.60) and calculated its sensitivity (S) and specificity (Sp) to identify kidney disease using a fixed (60 mL/min/1.73 m²) and age-dependent threshold for mGFR.

RESULTS

Rescaled BTP shared the same reference interval with rescaled Scr and ScysC and showed acceptable diagnostic performance (S = 73.1%, Sp = 86.5%), comparable to Scr (S = 71.0%, Sp = 90.5%) and ScysC (S = 80.7%, Sp = 92.9%). Rescaled BTP can be used in the FAS-equation with comparable performance as Scr and ScysC, but the Scr/ScysC/BTP-combined FAS-eq. (P10 = 57.8%, P30 = 96.6%) did not outperform the Scr/ScysC-combined FAS-eq. (P10 = 57.1%, P30 = 96.3%).

CONCLUSIONS

Rescaled BTP is a valid alternative to Scr or ScysC to diagnose kidney function. The FAS-concept can be applied to BTP or the combination of BTP, Scr and ScysC.

Beta-trace Protein as a new non-invasive immunological Marker for Quinolinic Acid-induced impaired Blood-Brain Barrier Integrity

Quinolinic acid, a macrophage/microglia-derived excitotoxin fulfills a plethora of functions such as neurotoxin, gliotoxin, and proinflammatory mediator, and it alters the integrity and cohesion of the blood-brain barrier in several pathophysiological states. Beta-trace protein (BTP), a monomeric glycoprotein, is known to indicate cerebrospinal fluid leakage. Thus, the prior aim of this study was to investigate whether BTP might non-invasively indicate quinolinic acid-induced impaired blood-brain barrier integrity. The research hypotheses were tested in three subsamples with different states of immune activation (patients with HCV-infection and interferon-α, patients with major depression, and healthy controls). BTP has also been described as a sensitive marker in detecting impaired renal function. Thus, the renal function has been considered. Our study results revealed highest quinolinic acid and highest BTP- levels in the subsample of patients with HCV in comparison with the other subsamples with lower or no immune activation (quinolinic acid: F = 21.027, p < 0.001 [ANOVA]; BTP: F = 6.792, p < 0.01 [ANOVA]). In addition, a two-step hierarchical linear regression model showed that significant predictors of BTP levels are quinolinic acid, glomerular filtration rate and age. The neurotoxin quinolinic acid may impair blood-brain barrier integrity. BTP might be a new non-invasive biomarker to indicate quinolinic acid-induced impaired blood-brain barrier integrity.

Serum Beta-Trace Protein as a Novel Predictor of Pregnancy-Induced Hypertension

Beta-trace protein (BTP) has emerged as a novel biomarker of cardiovascular risk. However, the level of circulating BTP in pregnancy-induced hypertension (PIH) is still unknown. The aim of this study was to determine the concentration of serum BTP in healthy pregnant women and patients with PIH. No significant difference was found in the serum concentration of BTP in patients with a normal pregnancy. In contrast, serum BTP levels in women with PIH (n=46) were significantly higher than those in women with normal pregnancy (n=57). Receiver operating characteristic analysis revealed that using a serum BTP value of 321.3 ng/mL as a cutoff produced a sensitivity of 91.3% and a specificity of 89.5%. Taken together, these findings suggest that a higher serum BTP concentration in PIH patients compared with those with normal pregnancy and serum BTP might be a novel biomarker in the diagnosis of PIH.

Predicting residual kidney function in hemodialysis patients using serum β-trace protein and β2-microglobulin

Residual kidney function (RKF) contributes significant solute clearance in hemodialysis patients. Kidney Diseases Outcomes Quality Initiative (KDOQI) guidelines suggest that hemodialysis dose can be safely reduced in those with residual urea clearance (KRU) of 2 ml/min/1.73 m(2) or more. However, serial measurement of RKF is cumbersome and requires regular interdialytic urine collections. Simpler methods for assessing RKF are needed. β-trace protein (βTP) and β2-microglobulin (β2M) have been proposed as alternative markers of RKF. We derived predictive equations to estimate glomerular filtration rate (GFR) and KRU based on serum βTP and β2M from 191 hemodialysis patients based on standard measurements of KRU and GFR (mean of urea and creatinine clearances) using interdialytic urine collections. These modeled equations were tested in a separate validation cohort of 40 patients. A prediction equation for GFR that includes both βTP and β2M provided a better estimate than either alone and contained the terms 1/βTP, 1/β2M, 1/serum creatinine, and a factor for gender. The equation for KRU contained the terms 1/βTP, 1/β2M, and a factor for ethnicity. Mean bias between predicted and measured GFR was 0.63 ml/min and 0.50 ml/min for KRU. There was substantial agreement between predicted and measured KRU at a cut-off level of 2 ml/min/1.73 m(2). Thus, equations involving βTP and β2M provide reasonable estimates of RKF and could potentially be used to identify those with KRU of 2 ml/min/1.73 m(2) or more to follow the KDOQI incremental hemodialysis algorithm.

Effects of Traumatic Amputation on β-Trace Protein and β2-Microglobulin Concentrations in Male Soldiers

BACKGROUND

Serum creatinine (SCr) levels are decreased following traumatic amputation, leading to the overestimation of glomerular filtration rate (GFR). β-Trace protein (BTP) and β2-microglobulin (B2M) strongly correlate with measured GFR and have not been studied following amputation. We hypothesized that BTP and B2M would be unaffected by traumatic amputation.

METHODS

We used the Department of Defense Serum Repository to compare pre- and post-traumatic amputation serum BTP and B2M levels in 33 male soldiers, via the N Latex BTP and B2M nephelometric assays (Siemens Diagnostics, Tarrytown, N.Y., USA). Osterkamp estimation using DEXA scan measurements was used to establish percent estimated body weight loss (%EBWL). Results were analyzed for small (3-5.9% EBWL), medium (6-13.5%), and large (>13.5%) amputation subgroups; and for a control group matched 1:1 to the 12 large amputation subjects. Paired Student's t test was used for comparisons.

RESULTS

Mean serum BTP levels were unchanged in controls, all amputees, and the small and medium amputation subgroups. BTP appeared to decrease following large %EBWL amputation (p = 0.05). Mean serum B2M levels were unchanged in controls, all amputees, and the small and medium amputation subgroups. B2M appeared to increase following large %EBWL amputation (p = 0.05).

CONCLUSIONS

BTP and B2M levels are less affected than SCr by amputation, and should be considered for future study of GFR estimation. BTP and B2M changes following large %EBWL amputation require validation and may offer insight into non-GFR BTP and B2M determinants as well as increased cardiovascular disease and mortality following amputation.

The impact of lipocalin-type-prostaglandin-D-synthase as a predictor of kidney disease in patients with type 2 diabetes

Hypertension and diabetes are clinical conditions which contribute to the development of chronic kidney disease as well as risk factors for cardiovascular events. In recent years, lipocalin-type-prostaglandin-D-synthase (beta trace protein; BTP) has increasingly been studied as an alternative to creatinine for the evaluation of renal function as well as for being a possible biomarker for cardiovascular disease. It is expected that the levels of BTP in patients with cardiovascular disease are elevated, as is the case with patients with renal dysfunction. The objective of this study is to realize a systematic review of the pertinent literature in respect to BTP as a biomarker of renal dysfunction in diabetic patients. Using the database MEDLINE, a search up to year 2014 was conducted using the follow descriptors: "lipocalin type prostaglandin d synthase" AND "diabetes"; "lipocalin type prostaglandin d synthase" and "diabetic nephropathy"; "beta trace protein" AND "diabetes"; "beta trace protein" AND "diabetic nephropathy". The criteria used for inclusion were the presence of the referring to terms in title or abstract and study conducted in humans. About 17 articles were selected, of which six articles were duplicates, and of which six articles did not investigate any possible relationship between the protein (BTP) and either diabetes or nephropathy. The final result yielded five articles to be analyzed. This review found BTP is not influenced by race, by body mass index nor by patient's sex. BTP can be considered as a reliable early biomarker of renal dysfunction in diabetics. BTP is associated with metabolic syndrome and is also associated with greater cardiovascular risk. Prospective data establishing a correlation between BTP and mortality would have been of great interest, but such articles were not found in this review.

Proteomic analysis of cerebrospinal fluid in canine cervical spondylomyelopathy

STUDY DESIGN

Prospective study.

OBJECTIVE

To identify proteins with differential expression in the cerebrospinal fluid (CSF) from 15 clinically normal (control) dogs and 15 dogs with cervical spondylomyelopathy (CSM).

SUMMARY OF BACKGROUND DATA

Canine CSM is a spontaneous, chronic, compressive cervical myelopathy similar to human cervical spondylotic myelopathy. There is a limited knowledge of the molecular mechanisms underlying these conditions. Differentially expressed CSF proteins may contribute with novel information about the disease pathogenesis in both dogs and humans.

METHODS

Protein separation was performed with 2-dimensional electrophoresis. A Student t test was used to detect significant differences between groups (P < 0.05). Three comparisons were made: (1) control versus CSM-affected dogs, (2) control versus non-corticosteroid-treated CSM-affected dogs, and (3) non-corticosteroid-treated CSM-affected versus corticosteroid-treated CSM-affected dogs. Protein spots exhibiting at least a statistically significant 1.25-fold change between groups were selected for subsequent identification with capillary-liquid chromatography tandem mass spectrometry.

RESULTS

A total of 96 spots had a significant average change of at least 1.25-fold in 1 of the 3 comparisons. Compared with the CSF of control dogs, CSM-affected dogs demonstrated increased CSF expression of 8 proteins including vitamin D-binding protein, gelsolin, creatine kinase B-type, angiotensinogen, α-2-HS-glycoprotein, SPARC (secreted protein, acidic, rich in cysteine), calsyntenin-1, and complement C3, and decreased expression of pigment epithelium-derived factor, prostaglandin-H2 D-isomerase, apolipoprotein E, and clusterin. In the CSF of CSM-affected dogs, corticosteroid treatment increased the expression of haptoglobin, transthyretin isoform 2, cystatin C-like, apolipoprotein E, and clusterin, and decreased the expression of angiotensinogen, α-2-HS-glycoprotein, and gelsolin.

CONCLUSION

Many of the differentially expressed proteins are associated with damaged neural tissue, bone turnover, and/or compromised blood-spinal cord barrier. The knowledge of the protein changes that occur in CSM and upon corticosteroid treatment of CSM-affected patients will aid in further understanding the pathomechanisms underlying this disease.

LEVEL OF EVIDENCE

N/A.

Emerging risk biomarkers in cardiovascular diseases and disorders

Present review article highlights various cardiovascular risk prediction biomarkers by incorporating both traditional risk factors to be used as diagnostic markers and recent technologically generated diagnostic and therapeutic markers. This paper explains traditional biomarkers such as lipid profile, glucose, and hormone level and physiological biomarkers based on measurement of levels of important biomolecules such as serum ferritin, triglyceride to HDLp (high density lipoproteins) ratio, lipophorin-cholesterol ratio, lipid-lipophorin ratio, LDL cholesterol level, HDLp and apolipoprotein levels, lipophorins and LTPs ratio, sphingolipids, Omega-3 Index, and ST2 level. In addition, immunohistochemical, oxidative stress, inflammatory, anatomical, imaging, genetic, and therapeutic biomarkers have been explained in detail with their investigational specifications. Many of these biomarkers, alone or in combination, can play important role in prediction of risks, its types, and status of morbidity. As emerging risks are found to be affiliated with minor and microlevel factors and its diagnosis at an earlier stage could find CVD, hence, there is an urgent need of new more authentic, appropriate, and reliable diagnostic and therapeutic markers to confirm disease well in time to start the clinical aid to the patients. Present review aims to discuss new emerging biomarkers that could facilitate more authentic and fast diagnosis of CVDs, HF (heart failures), and various lipid abnormalities and disorders in the future.

Novel markers and therapies for patients with acute heart failure and renal dysfunction

BACKGROUND

Acute kidney injury complicates decompensated heart failure in ∼33% of cases and is associated with morbidity and mortality; thus, we sought to systematically review this topic in order to summarize novel diagnostic and therapeutic approaches.

METHODS

Structured PubMed searches on these topics were conducted in February 2014 and relevant literature was identified. The PubMed search identified a total of 192 articles that were individually screened for inclusion in this analysis, and 58 were included.

RESULTS

Acute kidney injury, defined by substantial increases in serum creatinine, is associated consistently with prolonged length of stay, rehospitalization, and mortality. Biomarker studies suggested that natriuretic peptides are prognostic for shorter- and longer-term mortality. Novel proteins indicating kidney damage and albumin in the urine are associated with acute kidney injury. The most promising acute pharmacologic treatment appears to be serelaxin, which has been shown to improve acute heart failure symptoms, hemodynamic parameters, and renal function.

CONCLUSIONS

The presence of acute kidney injury results in worse clinical outcomes for patients with acute heart failure. Novel biomarkers and therapies hold the promise of improving both cardiac and renal outcomes in these patients.

Proteomic biomarkers in kidney disease: issues in development and implementation

Proteomic biomarkers offer the hope of improving the management of patients with kidney diseases by enabling more accurate and earlier detection of renal pathology than is possible with currently available biomarkers, serum creatinine and urinary albumin. In addition, proteomic biomarkers could also be useful to define the most suitable therapeutic targets in a given patient or disease setting. This Review describes the current status of proteomic and protein biomarkers in the context of kidney diseases. The valuable lessons learned from early clinical studies of potential proteomic biomarkers in kidney disease are presented to give context to the newly identified biomarkers, which have potential for actual clinical implementation. This article also includes an overview of protein-based biomarker candidates that are undergoing development for use in nephrology, focusing on those with the greatest potential for clinical implementation. Relevant issues and problems associated with the discovery, validation and clinical application of proteomic biomarkers are discussed, along with suggestions for solutions that might help to guide the design of future proteomic studies. These improvements might remove some of the current obstacles to the utilization of proteomic biomarkers, with potentially beneficial results.

Beta-trace protein as a marker of GFR--history, indications, and future research

OBJECTIVES

Recent findings suggest that beta-trace protein (BTP), a small molecular weight protein, is at least equal if not superior to serum creatinine as a marker of glomerular filtration rate (GFR), particularly since it is independent from height, gender, age, and muscle mass. The authors sought to summarize knowledge on BTP and its use as a marker of GFR using the most recent literature available.

DESIGN AND METHODS

The authors compiled key articles and all relevant recent literature on this topic. Physical and chemical features of the molecule are described, as well as factors that may affect its expression. The use of BTP in estimating GFR as a whole and in specific patient groups, including pregnant women, neonates and infants, children and adolescents, and patients who have undergone renal transplantation is discussed. The use of BTP as a marker for cardiovascular risk factors is also briefly addressed.

RESULTS

Although its performance in the general population is marginally inferior to cystatin C, studies have suggested that it may be superior in accurately estimating GFR in select patient groups such as pregnant women and neonates.

CONCLUSIONS

This novel marker shows promise, but further research is required to clarify findings from available data.

Biomarkers in atrial fibrillation: an overview

Atrial fibrillation (AF) confers a raised risk of stroke and death, and this risk of adverse events is increased by the coexistence of other cardiovascular risk factors. The pathophysiology of AF is complex, involving the role of inflammation, structural remodelling with apoptosis, inflammation or fibrosis. These changes confer a prothrombotic or hypercoagulable state in this arrhythmia. Despite being easy to use for decision-making concerning oral anticoagulant therapy in AF, clinical risk scores used for stratification have shown modest capability in predicting thromboembolic events, and biomarkers may improve our identification of 'high risk' patients. Biomarkers, whether measured in the peripheral blood, urine or imaging-based may improve our knowledge of the pathophysiology of AF. Importantly these biomarkers could help in the assessment of AF prognosis. The aim of this review was to summarise the published data about biomarkers studied in AF, with focus on data from randomised prospective clinical trials and large community-based cohorts. We will also review the application of these biomarkers to prognosis on the main schemes used to help stratify risk in AF.

The post-resuscitative urinalysis associate the survival of patients with non-traumatic out-of-hospital cardiac arrest

OBJECTIVE

To analyze whether urine output and urinalysis results are predictive of survival and neurologic outcomes in patients with non-traumatic out-of-hospital cardiac arrest (OHCA).

METHODS

Information was obtained from 1,340 patients with non-traumatic OHCA who had achieved a sustained return of spontaneous circulation (ROSC). Factors that were associated with survival in the post-resuscitative period were evaluated. The association between urine output and fluid challenge in the early resuscitative period was analyzed and compared between the survivors and the non-survivors. The results of the initial urinalysis, including the presence of proteinuria and other findings, were used to evaluate the severity of vascular protein leakage and survival. The association between proteinuria and the neurologic outcomes of the survivors was also analyzed. The clinical features of capillary leakage were examined during the post-resuscitative period.

RESULTS

Of the 1,340 patients, 312 survived. A greater urine output was associated with a higher chance of survival. The initial urine output increased in proportion to the amount of fluid that was administered during early resuscitation in the emergency department for the survivors but not for the non-survivors (p<0.05). In the initial urinalysis, proteinuria was strongly associated with survival, and severe proteinuria indicated significantly poorer neurologic outcomes (p<0.05 for both comparisons). Proteinuria was associated with a risk of developing signs of capillary leakage, including body mass index gain and pitting edema (both p<0.001).

CONCLUSION

The severity of proteinuria during the early post-resuscitative period was predictive of survival.