Microalbuminuria in diabetes mellitus: review and recommendations for the measurement of albumin in urine

Investigating the Serum Albumin Binding Behavior of Naphthalimide Based Fluorophore Conjugates: Spectroscopic and Molecular Docking Approach

In the present study, naphthalimide-pyrazole-benzothiazole based fluorescent analogs were synthesized by substituting different primary and secondary amines on the naphthalimide nucleus and were evaluated for their sensitivity and selectivity towards serum albumin. Among various synthesized analogues compound 25 showed the most significant change with serum albumin and was further studied for selective detection and mode of interaction with serum albumin. Here, we compared the binding interaction of fluorescent probe 25 for variation/detection of two 76 % structurally resembling proteins HSA and BSA, by spectroscopic experiments. The compound shows more selectivity for HSA and BSA with a higher binding constant and evident visible change in the emission spectra of two serum albumins among different bioanalytes. The mode of interaction of 25 with human serum albumin and bovine serum albumin was investigated by FT-IR, circular dichroism, and DLS techniques to find out the change in the microenvironment and variation in the structure of serum albumin proteins. Higher binding affinity and specific selectivity of 25 with a limit of detection of 0.69 μM and 1.4 μM towards HSA and BSA compared to other bioanalytes make it a significant fluorescent probe for quantitatively detecting serum albumins at the very early stage of many fatal diseases.

SGLT2 inhibitors: from glucose-lowering to cardiovascular benefits

An increasing number of individuals are at high risk of type 2 diabetes (T2D) and its cardiovascular complications, including heart failure (HF), chronic kidney disease (CKD), and eventually premature death. The sodium-glucose co-transporter-2 (SGLT2) protein sits in the proximal tubule of human nephrons to regulate glucose reabsorption and its inhibition by gliflozins represents the cornerstone of contemporary T2D and HF management. Herein, we aim to provide an updated overview of the pleiotropy of gliflozins, provide mechanistic insights and delineate related cardiovascular (CV) benefits. By discussing contemporary evidence obtained in preclinical models and landmark randomized controlled trials, we move from bench to bedside across the broad spectrum of cardio- and cerebrovascular diseases. With landmark randomized controlled trials confirming a reduction in major adverse CV events (MACE; composite endpoint of CV death, non-fatal myocardial infarction, and non-fatal stroke), SGLT2 inhibitors strongly mitigate the risk for heart failure hospitalization in diabetics and non-diabetics alike while conferring renoprotection in specific patient populations. Along four major pathophysiological axes (i.e. at systemic, vascular, cardiac, and renal levels), we provide insights into the key mechanisms that may underlie their beneficial effects, including gliflozins' role in the modulation of inflammation, oxidative stress, cellular energy metabolism, and housekeeping mechanisms. We also discuss how this drug class controls hyperglycaemia, ketogenesis, natriuresis, and hyperuricaemia, collectively contributing to their pleiotropic effects. Finally, evolving data in the setting of cerebrovascular diseases and arrhythmias are presented and potential implications for future research and clinical practice are comprehensively reviewed.

Urine protein quantification in human urine on boron-doped diamond electrodes based on the electrochemical reaction of Coomassie brilliant blue

Urinalysis is attracting interest in personal healthcare management as part of a general move to improve quality of life. Urine contains various metabolites and the protein level in urine is an indicator of kidney function. In this study, a novel electrochemical sensing system based on boron-doped diamond (BDD) electrodes was developed for the detection of protein concentrations in human urine. BDD electrodes have the advantages of a wide electrochemical potential window and low non-specific adsorption, making them ideal for simple, rapid, and compact devices for home detection of bio-relevant substances. Coomassie brilliant blue (CBB), a dye that selectively and strongly binds to urine proteins, was found to be a redox-active indicator to show a decrease in its redox currents in relation to the concentration of protein in urine samples. Our detailed studies of BDD electrodes showed their limit of detection to be 2.57 μg mL-1 and that they have a linear response that ranges from 0 to 400 μg mL-1 in urine samples. We also investigated the detection of urine protein in different urine samples. Our results agreed with those obtained using conventional colorimetric analysis. We believe this to be the first study of electrochemical detection of urine protein in urine samples on BDD electrodes, which is of great significance to be able to obtain results with electrical signals rapidly compared to conventional colorimetric analysis. This CBB-BDD technique has the potential to assist healthcare management in the form of a rapid daily diagnostic test to judge whether a more detailed examination is needed.

A BODIPY-O-glycoside based near-infrared fluorescent sensor for serum albumin

Highly sensitive and selective near-infrared fluorescent bioprobes for serum albumin detection and quantification are in high demand for biomedical applications. Herein, we report a near-infrared emitting BODIPY-O-glycoside dye as a turn-on emission sensor for serum albumin. To the best of our knowledge, this is the first report of NIR-emitting BODIPY dyes for serum albumin sensing. Despite the various outstanding photophysical properties of the BODIPY dyes, their insolubility in water/biological media restricts their real biomedical applications. To overcome this issue, highly stable unadulterated BODIPY-O-glycoside nanoparticles (BDP-Glu-NPs) were prepared in aqueous solution by self-assembly of amphiphilic BODIPY-O-glycoside dyes. The BDP-Glu-NPs were characterized by spectroscopic, NMR, DLS and TEM studies. The ability of the BDP-Glu-NPs for the detection and quantification of serum albumin was demonstrated. It showed a 150-fold fluorescence enhancement in the presence of serum albumin, with excellent selectivity over other amino acids, porphyrin, proteins and various inorganic salts. Detection of human serum albumin (HSA) in urine samples showed that the bioprobe is applicable to a clinically significant range of the analytes with very low detection limit. These results suggested that the BDP-Glu-NPs can act as potential bioprobe to quantify albumin in biochemical and clinical samples.

Fluorescent chameleon labels for bioconjugation and imaging of proteins, nucleic acids, biogenic amines and surface amino groups. a review

Chameleon labels (ChLs) possess the unique property of changing (visible) color and fluorescence on binding to amino groups of biomolecules. MostChLs react with primary aliphatic amino groups such as those in lysine or with amino groups artificially introduced into polynucleic acids or saccharides, but someothers also react with secondary amino groups. Under controlled circumstances, the reactions are fairly specific. The review is subdivided into the following sections: (1) An introduction and classification of fluorescent labels; (2) pyrylium labels that undergo shortwave color changes upon labelling, typically from blue to red; (3) polymethine type of labels (that also undergo shortwave color changes, typically from green to blue; (4) various other (less common) chromogenic and fluorogenic systems; (5) hemicyanine labels that undergolongwavecolor changes, typically from yellow to purple; (6) the application of ChLs to labeling of proteins and oligonucleotides; (7) applications to fluorometric assays and sensing; (8) applications to fluorescence imaging of biomolecules; (9) applications in studies on affinity interactions (receptor-ligand binding); (10) applications in surface and interface chemistry; and (11) applications in chromatography, electrophoresis and isotachophoresis of biomolecules.

Relationship between urinary albumin and albumin/creatinine ratio during normal pregnancy and pre-eclampsia

Pre-eclampsia is a serious complication of pregnancy and it is important to detect the condition as early as possible. Albuminuria is an important symptom of pre-eclampsia and repeated urine analyses to screen for the condition are part of the standard antenatal care. The purpose of this study was to investigate whether measurement of the urine albumin/creatinine ratio in spot samples could be a complement to the dipstick method and could reduce the need for 24-h urine collections. Urine samples were collected for 24 h in weeks 12, 24 and 36 of pregnancy from both normotensive women and women who developed hypertension or who had pregnancy-induced hypertension (PIH) when they entered the study. The 24-h albumin excretion was significantly correlated to the albumin/creatinine ratio in all measurements (Pearson correlation coefficient). In week 12, the values were: n = 44, r = 0.964, p < 0.001 (normotensive group) and in the PIH group: n = 8, r = 0.789, p < 0.05. In week 24, the correlation values were r = 1.0 and p < 0.001 in both the normotensive group (n = 41) and in the PIH group (n = 11). In week 36 the correlation values were r = 0.791 and p < 0.001 in the normotensive group (n = 39) and r = 1.0 and p < 0.001 in the PIH group (n = 16). Microalbuminuria was defined as urine albumin excretion higher than 30 mg/24 h and this corresponded to an albumin/creatinine ratio of 2.9. Microalbuminuria was found in three persons in the PIH group and in two persons in the normotensive group. Overt albuminuria (> 300 mg/24 h) was found in one of the 46 normotensive women (2%) and in 3 of the 19 PIH women (16%). In all these women the high albumin values had been detected by using the albumin/creatinine ratio method. In conclusion, it has been found that the albumin excretion in urine correlates significantly to the albumin/creatinine ratio during pregnancy. The urinary albumin/creatinine ratio appears to be a good alternative to the dipstick method and to 24-h urine collections.

Development of Human Serum Albumin Selective Fluorescent Probe Using Thieno[3,2-b]pyridine-5(4H)-one Fluorophore Derivatives

The level of human serum albumin (HSA) in biological fluids is a key health indicator and its quantitative determination has great clinical importance. In this study, we developed a selective and sensitive fluorescent HSA probe by fluorescence-based high-throughput screening of a set of fluorescent thieno[3,2-b]pyridine-5(4H)-one derivatives against major plasma proteins: HSA, bovine serum albumin (BSA), globulin, fibrinogen, and transferrin. The fluorophore chosen finally (4) showed noticeable fluorescence enhancement in the presence of HSA (160-fold increase), and it exhibited rapid response, high sensitivity (detection limit 8 nM), and the ability to clearly distinguish HSA from BSA in pH 9 buffer condition. Moreover, the probe could be applicable to detect trace amounts of HSA in an artificial urine sample; further, it might be applied to the determination of the HSA concentration in complex biological samples for pre-clinical diagnosis.

Renal Consequences of Gestational Diabetes Mellitus in Term Neonates: A Multidisciplinary Approach to the DOHaD Perspective in the Prevention and Early Recognition of Neonates of GDM Mothers at Risk of Hypertension and Chronic Renal Diseases in Later Life

Fetal exposure to gestational diabetes mellitus (GDM) seems to stimulate a negative impact on the kidneys. Renal volumes and urinary biomarkers of renal function and tubular impairment and injury were evaluated in 30–40-day old newborns of GDM mothers (n = 139) who needed insulin therapy during pregnancy. We found that neonates of mothers who maintained strict control over normoglycemia (n = 65) during pregnancy and fulfilled the other criteria of the GDM management program showed no differences compared to control (n = 55). Conversely, those (n = 74), whose mothers did not maintain glycemic control and were not compliant to the management program, exhibited significantly lower levels of renal volumes and higher activity of N-acetyl-β-d-glucosaminidase and cathepsin B. Differences due to maternal pre-gestational and gestational body mass index (BMI) as well as to maternal weight gain were demonstrated. Our findings indicate that a multidisciplinary approach, which involves an appropriate management of GDM, prevents the negative effects of GDM on the kidneys at 30–40 days of postnatal age, indicating the fundamental role of glycemic control, as well as of an adequate range of maternal weight gain. Total renal volume, cortical volume, and urinary activity of N-acetyl-β-d-glucosaminidase and cathepsin B may be suggested as indicators for the early recognition of GDM neonates at long-term risk of hypertension and kidney disease.

Hydrogen sulfide modulates SIRT1 and suppresses oxidative stress in diabetic nephropathy

DN is recognized as not only a leading cause of end stage renal disease (ESRD) but also an independent risk factor for cardiovascular disease (CVD). Novel therapeutic approaches to diabetic nephropathy (DN) are needed, or else, healthcare resources will be overwhelmed by the expected worldwide increase in associated cases of ESRD and CVD. Reactive oxygen species (ROS) and advanced glycation end product (AGE) are implicated in the development of DN. Hydrogen sulfide (H₂S) is known for its antioxidant and antiapoptotic characteristics. Simultaneously diabetics have lower H₂S levels. Thus, it is worth investigating the use of H₂S in treatment of DN. To investigate the potential therapeutic role of H₂S in DN. Sixty male rats were divided into four groups: control, DN, DN+NaHS30 µmol/kg/day and DN+NaHS100 µmol/kg/day. Fasting blood sugar (FBS), kidney function tests, SIRT1 activity, superoxide dismutase activity (SOD), malondialdehyde (MDA) and expression of caspase3 and p53 in renal tissues were assessed. Kidney was examined histopathologically. DN rats had higher FBS, renal dysfunction, decreased SIRT1 and SOD activity levels, increased caspase3 and p53 relative expression and increased MDA in renal tissues. NaHS increased SIRT1 and reversed biochemical, apoptotic, oxidant and pathologic parameters characteristic of DN, with better results using a dose of 100 µmol/kg/day. H₂S has a protective role against DN through decreasing FBS, ROS, apoptosis and upregulating SIRT1, thus preserving renal cells from further damage caused by DM.

Relations between dairy product intake and blood pressure: the INTERnational study on MAcro/micronutrients and blood Pressure

BACKGROUND

Epidemiologic evidence suggests that low-fat dairy consumption may lower risk of hypertension. Dairy products may be distinctly linked to health, because of differences in nutritional composition, but little is known about specific nutrients that contribute to the dairy-blood pressure (BP) association, nor to underlying kidney function.

METHODS

We examined cross-sectional associations to BP of dairy product intakes, total and by type, from the INTERnational study on MAcro/micronutrients and blood Pressure (INTERMAP) including 2694 participants aged 40-59 years from the UK and the USA. Eight BP, four 24-h dietary recalls and two 24-h urine samples were collected during four visits. Linear regression models adjusted for lifestyle/dietary factors to estimate BP differences per 2SD higher intakes of total-and-individual-types of dairy were calculated.

RESULTS

Multivariable linear regression coefficients were estimated and pooled. In contrast to total and whole-fat dairy, each 195 g/1000 kcal (2SD) greater low-fat dairy intake was associated with a lower SBP -2.31 mmHg and DBP -2.27 mmHg. Significant associations attenuated with adjustment for dietary phosphorus, calcium, and lactose, but strengthened with urinary calcium adjustment. Stratification by median albumin-creatinine ratio (ACR; high ACR indicates impaired kidney function) showed strong associations between low-fat dairy and BP in participants with low ACR (SBP: -3.66; DBP: -2.15 mmHg), with no association in participants with high ACR.

CONCLUSION

Low-fat dairy consumption was associated with lower BP, especially among participants with low ACR. Dairy-rich nutrients including phosphorus and calcium may have contributed to the beneficial associations with BP.

Fresh fruit consumption and risk of incident albuminuria among rural Chinese adults: A village-based prospective cohort study

Background

Recent studies showed that increased fresh fruit consumption is significantly associated with lower risks of diabetes, hypertension, and cardiovascular disease (CVD); other studies suggested that albuminuria is associated with diabetes, hypertension, and CVD. Therefore, we hypothesized that lower fresh fruit consumption is associated with higher risk of incident albuminuria among Chinese adults in rural areas, where fresh fruit consumption level is very low and prevalence of albuminuria is high.

Methods

We tested the hypothesis in a village-based cohort study of 3574 participants aged ≥ 30 years from the Handan Eye Study conducted from 2006 to 2013. Albuminuria was defined as urinary albumin-to-creatinine ratio ≥ 30 mg/g.

Results

Overall, 35.4% of the participants never or rarely consumed fresh fruits, and 33.9, 21.6, and 9.1% consumed fresh fruits 1–3 times/month, 1–2 times/week, and ≥ 3 times/week, respectively. During a median follow-up period of 5.6 years, albuminuria developed in 17.6% (n = 629) of the participants. Compared with participants who consumed fresh fruits ≥ 3 times/week, the multivariable adjustment odds ratios (ORs) for incident albuminuria associated with fruit consumption 1–2 times/week, 1–3 times/month, and no or rare consumption were 1.58 (95% confidence intervals (CI), 1.05–2.40), 1.74 (95% CI, 1.17–2.58), and 1.78 (95% CI, 1.20–2.64), respectively. After excluding participants with diabetes, the association remained significant.

Conclusions

Lower fresh fruit consumption was significantly associated with higher risk of incident albuminuria, and fresh fruit consumption frequency could be an essential intervention target to prevent albuminuria in rural China.

Evaluation of the URiSCAN 2 ACR Strip to estimate the urine albumin/creatinine ratios

BACKGROUND

The urine albumin/creatinine ratio (ACR) test is used to screen patients with chronic diseases, such as diabetes, hypertension and cardiovascular diseases that put them at an increased risk of developing kidney disease. Here, we evaluated the performance of the URiSCAN 2 ACR Strip (URiSCAN; YD diagnostics, Yongin, Korea), a semiquantitative point-of-care testing (POCT) assay, and we compared to an existing POCT assay and a quantitative assay.

MATERIALS AND METHODS

A total of 1,020 random urine specimens were analyzed using the semiquantitative URiSCAN 2 ACR Strip and semiquantitative CLINITEK Microalbumin 2 Strip (CLINITEK; Siemens, New York, USA). We evaluated the precision of the URiSCAN 2 ACR Strip and compared the results of the ACR obtained from URiSCAN to those of CLINITEK with the quantitative results of a quantitative assay as a reference.

RESULTS

The precision evaluation of the URiSCAN revealed a range between the cutoff (C50 )-20% and C50 +20% bounds, the C5 -C95 interval, with 85.8% confidence. URiSCAN and CLINITEK showed sensitivity and specificity of 87.7% and 72.2%, and 90.2% and 83.0%, respectively. The concordance rates of URiSCAN with CLINITEK and the quantitative assay were 75.6% and 79.1%, respectively. The concordance rate in the abnormal range (≥30 mg/g) between URiSCAN and the quantitative assay were higher than that between CLINITEK and the quantitative assay (78.8% vs 75.4%).

CONCLUSIONS

URiSCAN showed good precision and comparable sensitivity with lower specificity than those of CLINITEK.

A selective and sensitive fluorescent probe for the determination of HSA and trypsin

A simple fluorescent probe HBI-GR based on the combination of the fluorophore (p-HBI) in green fluorescent protein (GFP) and Guanine riboside (GR) for HSA was successfully synthesized. HBI-GR showed an obvious fluorescence enhancement toward HSA without interference from other proteins, amino acids, anions and commonly existing metal ions. HBI-GR exhibited high sensitivity towards HSA with a good linear relationship between the fluorescence intensity of HBI-GR and HSA concentration from 0 to 0.06mgmL^-1. The limit of detection, based on a signal-to-noise ratio of 3, was 15.09ngmL^-1, which was much lower than that of most other reported probes. HBI-GR was almost non-fluorescent because of the bond twisting in the exited state of chromophore HBI. After binding to the hydrophobic pocket of HSA, it showed an obvious fluorescence enhancement due to the rigidifying of the flexible chromophore HBI by the hydrophobic environment. The resulting HBI-GR/HSA system also showed a satisfactory sensing ability toward trypsin through decreased fluorescence intensity with the detection limit of 0.0282ngmL^-1. The fluorescence decreasing process was occurred as the lysine and arginine amino acids residues of HSA were cleaved by trypsin, which led to further exposure of HBI-GR to the PBS buffer phase and a concomitant decrease of the HBI-GR fluorescence intensity. Moreover, the probe HBI-GR was successfully used to detect HSA in healthy human urine and human blood serum samples. The practical application of the HBI-GR/HSA system for trypsin detection in healthy human urine also achieved satisfactory result.

Biochemical parameters of renal impairment/injury and surrogate markers of nephron number in intrauterine growth-restricted and preterm neonates at 30-40 days of postnatal corrected age

BACKGROUND

Premature and/or intrauterine growth-restricted neonates have an increased risk of developing postnatal renal injuries in later life. Studies on renal physiology in these neonates at a corrected age of 30-40 days are scarce and mostly relate to preterm infants. The data from these studies often lack the results of correlation analyses between biochemical parameters and nephron number-data which could provide additional insight and/or improve recognition of individuals at higher risk of renal failure.

METHODS

Urinary total protein and albumin levels and N-acetyl-β-D-glucosaminidase and cathepsin B activity were evaluated in preterm and intrauterine growth-restricted infants at a corrected age of 30-40 days and compared to data from a healthy control neonate population. The data were then associated with predominant susceptibility factors of renal damage related to low nephron number, such as gestational age, birth weight, total renal volume and renal cortex volume.

RESULTS

Compared to the control neonate population, we found significantly increased levels of all biochemical parameters tested in the intrauterine growth-restricted neonates, whereas in the preterm infants we observed a significant increase in cathepsin B activity, total protein level and, to a lesser extent, albumin level. Cathepsin B activity showed a significant, strong and inverse correlation with all surrogate markers of nephron number and was also strongly and positively correlated with urinary albumin level.

CONCLUSIONS

At this postnatal age, we found that lower nephron number in low birth weight neonates was associated to tubular impairment/injury that could be concurrent with a dysfunction of glomerular permeability. Urinary cathepsin B activity may be a candidate marker for the early prediction of renal susceptibility to damage in low birth weight neonates.

Prevalent Rate of Nonalbuminuric Renal Insufficiency and Its Association with Cardiovascular Disease Event in Korean Type 2 Diabetes

BACKGROUND

Nonalbuminuric renal insufficiency is a unique category of diabetic kidney diseases. The objectives of the study were to evaluate prevalent rate of nonalbuminuric renal insufficiency and to investigate its relationship with previous cardiovascular disease (CVD) event in Korean patients with type 2 diabetes mellitus (T2DM).

METHODS

Laboratory and clinical data of 1,067 subjects with T2DM were obtained and reviewed. Study subjects were allocated into four subgroups according to the CKD classification. Major CVD events were included with coronary, cerebrovascular, and peripheral vascular events.

RESULTS

Nonalbuminuric stage ≥3 CKD group, when compared with albuminuric stage ≥3 CKD group, had shorter diabetic duration, lower concentrations of glycated hemoglobin, high density lipoprotein cholesterol, and high-sensitivity C-reactive protein, lower prevalent rates of retinopathy and previous CVD, and higher rate of treatment with angiotensin-converting enzyme inhibitors/angiotensin II receptor blockers. Nonalbuminuric stage ≥3 CKD group showed a greater association with prior CVD events than no CKD group; however, albuminuric stage ≥3 CKD group made addition to increase prevalence of prior CVD events significantly when CKD categories were applied as covariates. Association of prior CVD events, when compared with normal estimated glomerular filtration rate (eGFR) and nonalbuminuria categories, became significant for declined eGFR, which was higher for eGFR of <30 mL/min/1.73 m², and albuminuria.

CONCLUSION

The results show that subjects with nonalbuminuric stage ≥3 CKD is significantly interrelated with occurrence of prior CVD events than those with normal eGFR with or without albuminuria. Comparing with normal eGFR and nonalbuminuria categories, the combination of increased degree of albuminuria and declined eGFR is becoming significant for the association of prior CVD events.

The impact of single versus mixed Schistosoma haematobium and S. mansoni infections on morbidity profiles amongst school-children in Taveta, Kenya

Two schistosome species--Schistosoma haematobium and S. mansoni--with two very different pathological profiles (urogenital versus intestinal), are responsible for the majority of human schistosomiasis infections across sub-Saharan Africa. The aim of this study was to determine whether coinfections have an impact on species-specific morbidity measures when compared to single species infections. Children from two neighbouring schools in Taveta, Kenya were grouped by infection status, i.e. uninfected, single species infections or coinfected. Clinical examination of the liver and spleen by palpation was performed and urinary albumin levels were recorded at baseline and at 12 months after praziquantel administration. Additional ultrasonographic profiles of the children's liver, spleen and bladder were incorporated at follow-up. It was found that S. haematobium-associated urogenital morbidity was lower in the coinfected group relative to single S. haematobium infections, even when infection intensities were taken into account. We also observed an association between S. haematobium infection and liver (intestinal-associated) morbidity regardless of coinfections. The findings reported here suggest that further research should be performed on the impact of S. haematobium infections on liver morbidity as well as to determine the impact of mixed schistosome species infections on human morbidity outcomes across different endemic settings.

Variations of CHI3L1, levels of the encoded glycoprotein YKL-40 and prediction of fatal and non-fatal ischemic stroke

Background

Polymorphisms of CHI3L1 are associated with inter-individual YKL-40 levels and YKL-40 is associated with an increased mortality and is elevated in patients with cardiovascular disease. We investigated the association between single nucleotide polymorphisms (SNPs) of CHI3L1, serum YKL-40 levels and all-cause and cardiovascular mortality and first-time incidence of myocardial infarction, ischemic heart disease (IHD) and stroke.

Methodology/Principal Findings

12 SNPs of CHI3L1 were genotyped and serum YKL-40 was measured in 2656 Danes representative of the general population. Median follow-up period was 15 (0–16) years. Admission data and deaths were ascertained from registers from the Danish National Board of Health. Fourth quartile YKL-40 levels were associated with an increased mortality risk of ischemic stroke (HR 2.44 (1.01–5.88), p = 0.041) and so were homozygotes of the minor allele of rs872129 (HR 9.35 (1.25–69.87, p = 0.022)). Both continuous YKL-40 levels and 4^th quartile YKL-40 values (>85 ng/ml) were associated with all-cause mortality (HRs 1.22 (95% CI, 1.10–1.35), p<0.0001, and 1.40 (1.15–1.71), p<0.0001), an increased risk of first-time stroke (HR 1.16 (1.01–1.33), p = 0.04, and 1.63 (1.23–2.16), p = 0.001) and a decreased risk of incidence of IHD (HR 0.77 (0.65–0.91), p = 0.002, and 0.61 (0.44–0.85), p = 0.003).

Conclusions/Signficance

High YKL-40 levels (>85 ng/ml) and rs872129 were associated with an increased mortality risk of ischemic stroke, but high YKL-40 levels were also inverse related with the risk of incidence of IHD. This could be a chance finding but could also elucidate that YKL-40 plays different roles in development of thromboembolisms versus the formation of local thrombosis.

Evaluation of the performance of urine albumin, creatinine and albumin-creatinine ratio assay on two POCT analyzers relative to a central laboratory method

BACKGROUND

The evaluation of microalbumin, creatinine and albumin-creatinine ratio is very important in patients with diabetes for the early detection of kidney disease and the identification of patients at risk for complications from diabetes or hypertension.

METHODS

A total of 88 spot urine samples previously analyzed using the Vitros 5,1 FS (creatinine) and Beckman Coulter Immage (microalbumin) located in the central laboratory and having microalbumin and creatinine values within the Afinion and DCA Vantage reportable ranges were run on 2 point of care (POC) instruments (Siemens DCA Vantage and Axis-Shield Afinion).

RESULTS

The mean values for the DCA Vantage were: 42.6 mg/l for albumin, 10.3 mol/l for creatinine, and 5.4 mg/mol for ACR. For the Afinion AS100, the mean values were: 48.5mg/l for albumin, 9.5 mol/l for creatinine, and 6.7 mg/mol for ACR. The mean values obtained for CL were: 40.8 mg/l for albumin, 10.0 mol/l for creatinine, and 5.4 mg/mol for ACR. All POC analyzers showed good correlation to the central laboratory tests for microalbumin, creatinine and albumin creatinine ratio (ACR) for Afinion (R(2)=0.954, 0.974, and 0.964, respectively) and DCA Vantage (R(2)=0.989, 0.987, and 0.991, respectively). With the exception of the DCA Vantage ACR (p=0.53), the levels of microalbumin, creatinine and ACR obtained for the Afinion and DCA Vantage instruments as compared to the CL were statistically different (p<0.05). The inter and intraday imprecision for both POC instruments was <2.9% and total imprecision <8.7%.

CONCLUSIONS

The 2 instruments evaluated in this study were in good agreement with the quantitative laboratory results and thus can be used for microalbumin, creatinine and ACR assays at the POC. However, facilities using Afinion will have to use different normal range for ACR.

Increased urinary protein excretion in the "normal" range is associated with increased renin-angiotensin system activity

Increased levels of albuminuria and proteinuria, both linked to augmented renin-angiotensin system (RAS) activity, are associated with adverse kidney and cardiovascular events. However, the relationship between variations in urinary albumin excretion (UAE) and total protein excretion (UTPE) in the normal range and RAS activity is unclear. We examined the association between UAE and UTPE and the hemodynamic response to angiotensin II (ANG II) challenge, a well-accepted indirect measure of RAS activity, in healthy individuals with normal UAE and UTPE. Forty subjects (15 men, 25 women; age 38 ± 2 yr; UAE, 3.32 ± 0.55 mg/day; UTPE, 56.8 ± 3.6 mg/day) were studied in high-salt balance. Blood pressure (BP), arterial stiffness determined by applanation tonometry, and circulating RAS components were measured at baseline and in response to graded ANG II infusion. The primary outcome was the BP response to ANG II challenge at 30 and 60 min. UAE was associated with a blunted diastolic BP response to ANG II infusion (30 min, P = 0.005; 60 min, P = 0.17), a relationship which remained even after adjustment (30 min, P < 0.001; 60 min, P = 0.035). Similar results were observed with UTPE (30 min, P = 0.031; 60 min, P = 0.001), even after multivariate analysis (30 min, P = 0.008; 60 min, P = 0.001). Neither UAE nor UTPE was associated with systolic BP, circulating RAS components, or arterial stiffness responses to ANG II challenge. Among healthy individuals with UAE and UTPE in the normal range, increased levels of these measures were independently associated with a blunted diastolic BP response to ANG II, indicating increased vascular RAS activity, which is known to be deleterious to both renal and cardiac function.

Urine analysis in microfluidic devices

Microfluidics has attracted considerable attention since its early development in the 1980s and has experienced rapid growth in the past three decades due to advantages associated with miniaturization, integration and automation. Urine analysis is a common, fast and inexpensive clinical diagnostic tool in health care. In this article, we will be reviewing recent works starting from 2005 to the present for urine analysis using microfluidic devices or systems and to provide in-depth commentary about these techniques. Moreover, commercial strips that are often treated as chips and their readers for urine analysis will also be briefly discussed. We start with an introduction to the physiological significance of various components or measurement standards in urine analysis, followed by a brief introduction to enabling microfluidic technologies. Then, microfluidic devices or systems for sample pretreatments and for sensing urinary macromolecules, micromolecules, as well as multiplexed analysis are reviewed, in this sequence. Moreover, a microfluidic chip for urinary proteome profiling is also discussed, followed by a section discussing commercial products. Finally, the authors' perspectives on microfluidic-based urine analysis are provided. These advancements in microfluidic techniques for urine analysis may improve current routine clinical practices, particularly for point-of-care (POC) applications.

Urinary peptides as a diagnostic tool for renal failure detected by matrix-assisted laser desorption/ionisation mass spectrometry: an evaluation of their clinical significance

The development of new analytical methodologies related to the proteome for the evaluation of renal physiology and pathology is surely of wide interest for physicians, giving them new tools for monitoring complications associated with diabetes, such as end-stage renal disease. In the present study, the clinical significance of the urinary abundance of two peptides, SGSVIDQSRVLNLGPITR (the uromodulin precursor, m/z 1912) and IGPHypGPHypGLMGPP [present in the collagen-α-5(IV) chain precursor, m/z 1219], detected by matrix- assisted laser desorption/ionisation mass spectrometry (MALDI/MS) in microalbuminuric or nephropathic diabetic patients and in non-diabetic nephropathic patients was evaluated. A progressive increase in the abundance of the ion at m/z 1219 and a decrease in the abundance of the ion at m/z 1912 have been found in diabetic microalbuminuric, diabetic-nephropathic and nephropathic patients. Linear correlations are present between serum creatinine values and the abundances of the ions at m/z 1219 (positive correlation, r=0.3645, P<0.0001) and at m/z 1912 (negative correlation, r=-0.3053, P<0.0005). Correlations between the MALDI data and the estimated glomerular filtration rate were also found, while relationships with urinary albumin excretion were found only in sub-sets of patients. Analysis of receiver operating characteristic curves showed a sensitivity up to 96% and a specificity of up to 84% for the two ionic species, or their ratio, for distinguishing diabetic patients with different degrees of nephropathy from healthy subjects, proving that the urinary abundance of the two peptides at m/z 1219 and m/z 1912, determined with MALDI/MS, may be considered as a possible diagnostic tool for the determination of progression toward renal failure, also with the aim of monitoring kidney function, in diabetic patients.

Plasma selenoproteins concentrations in type 2 diabetes mellitus--a pilot study

The association between the concentration/activity of selenium/selenoproteins in plasma and type 2 diabetes mellitus is still a matter of debate. This cross-sectional pilot study evaluates whether patients with diabetes present a different plasma selenoproteins status than a healthy control group and examines whether the introduction of clinical parameters allows the detection of correlations and further grouping criteria. For this purpose, the levels of plasma glutathione peroxidase (GPx), selenoprotein P (SelP), and seleno-albumin (SeAlb) present in 40 patients affected by type 2 diabetes mellitus were determined simultaneously and accurately by a newly developed analytical method. The results show that patients with diabetes demonstrate significantly lower levels of GPx and SeAlb with respect to healthy subjects (11 ± 3 ng/mL and 9 ± 2 ng/mL vs 18 ± 8 ng/mL and 11 ± 2 ng/mL, respectively). Significant negative correlations were revealed among GPx, SeAlb, and clinical parameters including fasting plasma glucose, hemoglobin A1c, and the albumin-to-creatinine ratio. Our findings suggest an association between the individual selenoproteins concentration and the presence of diabetes, including associated clinical parameters. It currently cannot be ascertained whether the altered selenoproteins status is a consequence or a causative factor for diabetes. This study demonstrates the potential of a method for individual selenoproteins determination for investigating the biochemical relationship between selenium and diabetes.

Risk stratification with the risk chart from the European Society of Hypertension compared with SCORE in the general population

OBJECTIVE

The risk chart from the European Society of Hypertension (ESH) and Systemic Coronary Risk Evaluation (SCORE) from the European Society of Cardiology (ESC) are equally recommended tools for risk stratification. However, ESH risk chart recommends measuring subclinical organ damage, whereas SCORE is based on traditional risk factors. We wanted to compare the predictive performance of the two charts.

METHODS

In a Danish population sample of 1344 individuals aged 41, 51, 61 and 71 years without known diabetes, prior stroke or myocardial infarction, not receiving cardiovascular, antidiabetic or lipid-lowering medications and with higher than optimal blood pressure (> or =120/80 mmHg), we measured traditional risk factors and subclinical organ damage. The endpoints were cardiovascular death and a composite of cardiovascular death, nonfatal myocardial infarction and stroke (CEP).

RESULTS

During the following 12.8 years cardiovascular death and CEP occurred in 71 and 132 patients, respectively. Forty-two percent had unrecognized hypertension. The sizes and characteristics of the populations in the different risk categories of the charts varied considerably as ESH risk chart allocated 368 patients to higher-risk categories than SCORE (P < 0.001). These patients were younger, with higher blood pressure and less frequently male smokers. However, ESH risk chart agreed with ESC guidelines for antihypertensive treatment using SCORE in 89% (634/713) of the patients recommended treatment and produced similar sensitivities (79 vs. 79%), specificities (46 vs. 50%), positive (14 vs. 15%) and negative (95 vs. 96%) predictive values for CEP.

CONCLUSION

Although SCORE did not use subclinical organ damage, the guidelines by ESH and ESC using SCORE recommended antihypertensive treatment in almost the same patients.

Risk prediction is improved by adding markers of subclinical organ damage to SCORE

AIMS

It is unclear whether subclinical vascular damage adds significantly to Systemic Coronary Risk Evaluation (SCORE) risk stratification in healthy subjects.

METHODS AND RESULTS

In a population-based sample of 1968 subjects without cardiovascular disease or diabetes not receiving any cardiovascular, anti-diabetic, or lipid-lowering treatment, aged 41, 51, 61, or 71 years, we measured traditional cardiovascular risk factors, left ventricular (LV) mass index, atherosclerotic plaques in the carotid arteries, carotid/femoral pulse wave velocity (PWV), and urine albumin/creatinine ratio (UACR) and followed them for a median of 12.8 years. Eighty-one subjects died because of cardiovascular causes. Risk of cardiovascular death was independently of SCORE associated with LV hypertrophy [hazard ratio (HR) 2.2 (95% CI 1.2-4.0)], plaques [HR 2.5 (1.6-4.0)], UACR > or = 90th percentile [HR 3.3 (1.8-5.9)], PWV > 12 m/s [HR 1.9 (1.1-3.3) for SCORE > or = 5% and 7.3 (3.2-16.1) for SCORE < 5%]. Restricting primary prevention to subjects with SCORE > or = 5% as well as subclinical organ damage, increased specificity of risk prediction from 75 to 81% (P < 0.002), but reduced sensitivity from 72 to 65% (P = 0.4). Broaden primary prevention from subjects with SCORE > or = 5% to include subjects with 1% < or = SCORE < 5% together with subclinical organ damage increased sensitivity from 72 to 89% (P = 0.006), but reduced specificity from 75 to 57% (P < 0.002) and positive predictive value from 11 to 8% (P = 0.07).

CONCLUSION

Subclinical organ damage predicted cardiovascular death independently of SCORE and the combination may improve risk prediction.

Valsartan Reduces Serum Cystatin C and the Renal Vascular Resistance in Patients with Essential Hypertension

A high level of albuminuria and increased renal vascular resistance are associated with hypertensive renal damage. In this study, the authors investigated the effect of the angiotensin II receptor blocker, valsartan, on renal function and intrarenal hemodynamics in non-diabetic patients with essential hypertension. A prospective three-month study of the effects of valsartan, 40-80 mg/day, was performed in 30 hypertensive patients. As an assessment of renal function, serum creatinine, urine albumin/creatinine (Alb/Cr) ratio, and serum cystatin C levels were evaluated. Doppler ultrasonography of the kidney was performed for the evaluation of renal hemodynamics. Peak-systolic, end-diastolic, and mean velocities of interlobar arteries were evaluated, and the pulsatility index (PI) and resistive index (RI) were calculated. It was determined that patients with microalbuminuria had higher levels of serum cystatin C, PI, and RI compared to patients without microalbuminuria. Valsartan treatment significantly reduced systolic and diastolic blood pressure and decreased the Alb/Cr ratio. Serum creatinine was not changed, whereas serum cystatin C levels were significantly reduced. Valsartan treatment significantly decreased the PI in all patients and both PI and RI in patients with microalbuminuria. These results suggest that the angiotensin II receptor blocker, valsartan, is able to improve renal function by reducing renal vascular resistance in hypertensive patients, especially in patients with microalbuminuria, and may prevent future renal failure in patients with essential hypertension.

Relationship between glyco-oxidation, antioxidant status and microalbuminuria in type 2 diabetic patients

AIMS/HYPOTHESIS

This study examined the relationship, if any, between glucose-induced oxidative stress, antioxidant status and microalbuminuria in patients with type 2 diabetes.

METHODS

The study involved 99 consecutive type 2 diabetic patients (57 men, 42 women). Patients with persistent microalbuminuria were identified and the following variables evaluated: fasting plasma glucose, HbA(1c), malonyldialdehyde (MDA), pentosidine, AGE, the total radical-trapping antioxidant parameter (TRAP), vitamin E, creatinine, estimated GFR and lipid profile.

RESULTS

Patients were divided into two groups, i.e. 37 individuals without microalbuminuria (AER <20 microg/min) and 62 with microalbuminuria (AER > or =20 microg/min). The following variables were significantly higher in patients with microalbuminuria than in those without microalbuminuria (mean +/- SD): fasting plasma glucose 9.41 +/- 2.88 vs 8.19 +/- 1.93 mmol/l, p < 0.05; HbA(1c) 7.97 +/- 1.51 vs 7.39 +/- 1.03%, p < 0.05; MDA 1.18 +/- 0.35 vs 1.02 +/- 0.29 micromol/l, p < 0.05; pentosidine 98.5 +/- 24.6 vs 82.9 +/- 20.9 pmol/ml, p < 0.005; and AGE 13.2 +/- 4.8 vs 10.6 +/- 3.8 microg/mg protein, p < 0.01. However, vitamin E and TRAP did not differ between the two groups. Serum creatinine values and estimated GFR were similar in the two groups. Only in patients with microalbuminuria were significant linear correlations seen between AER and both oxidation (HbA(1c) r = 0.33, p < 0.01; MDA r = 0.59, p < 0.001; pentosidine r = 0.48, p < 0.001; and AGE r = 0.44, p < 0.001) and antioxidation variables (vitamin E r = -0.55, p < 0.001; TRAP r = -0.49, p < 0.001). Considering all variables together, multiple regression revealed a correlation between microalbuminuria and vitamin E, TRAP, HbA(1c) and MDA, but not pentosidine or AGE.

CONCLUSIONS/INTERPRETATION

Our data suggest that microalbuminuria in type 2 diabetic patients might be promoted by an insufficient counter-regulation of the antioxidant system in the event of increased glyco-oxidation/glycation.

Alkalinization of urine samples preserves albumin concentrations during prolonged frozen storage in patients with diabetes mellitus

BACKGROUND

In epidemiological studies in patients with diabetes, urine samples are often stored frozen prior to assessment of urinary albumin concentration (UAC). However, prolonged frozen storage may result in a falsely low UAC. In the current study, we investigated whether adjustment of urinary pH to alkaline values prior to frozen storage can prevent this problem.

METHODS

Urine samples were collected in 90 patients from our diabetes outpatient clinic and divided into two portions. One portion was first adjusted to pH > 8.0 with 0.1 m sodium hydroxide, the other was left unprocessed. Both portions were divided into aliquots. UAC was assessed in fresh samples and after 7 days, 1, 6 and 12 months of storage at -20 and -80 degrees C.

RESULTS

Until 1 month of storage there were no significant changes in UAC. After longer storage, UAC fell significantly in pH unadjusted samples stored at -20 degrees C, with a -7.6% (27.8) and -13.6% (31.7) change after 6 and 12 months storage, respectively. No significant change in UAC occurred in pH adjusted samples stored at -20 degrees C or when samples were stored at -80 degrees C, both with and without pH adjustment. Variation in UAC assessed after 12 months of storage was larger for samples stored at -20 degrees C without adjustment of pH than for the samples stored with pH adjustment or stored at -80 degrees C.

CONCLUSIONS

Urine alkalinization to pH > 8.0 prevents the decline in UAC associated with 12 months of frozen storage at -20 degrees C and results in lower variation between samples after storage.

Impact of the metabolic syndrome on the predictive values of new risk markers in the general population

Although the metabolic syndrome (MetS) is positively associated with high-sensitivity C-reactive protein (hsCRP), negatively associated with N-terminal pro-brain natriuretic peptide (Nt-proBNP) and inconsequently related to urine albumin/creatinine ratio (UACR) they are all associated with cardiovascular events. Therefore, we wanted to determine the influence of MetS on the predictive values of UACR, hsCRP and Nt-proBNP. On the basis of the definition of MetS by the International Diabetes Federation, a Danish population sample of 1983 apparently healthy subjects was divided into three groups: 530 subjects without any elements of MetS, 1093 subjects with some elements of MetS and 360 subjects with MetS. During the following 9.5 years the composite end point of cardiovascular death, non-fatal myocardial infarction or stroke (composite cardiovascular end point, CEP) occurred in 204 subjects. In Cox-regression analyses adjusting for age, gender and smoking, all three cardiovascular risk markers predicted CEP independently of MetS. Despite no significant interaction with MetS, high log(hsCRP) was associated with CEP primarily in subjects without any elements of MetS (hazard ratio (HR)=4.5 (1.5-14.0), P<0.01), log(Nt-proBNP) primarily in subjects with some elements of MetS (HR=3.0 (1.6-5.6), P<0.01), and logUACR independently of elements of MetS. Pre-specified gender-adjusted (men/women) cutoff values of hsCRP > or = 6.0/7.3 mg l(-1) predicted CEP in subjects without elements of MetS with positive and predictive values of 11.5 and 98%, respectively. UACR > or = 0.73/1.06 mg mmol(-1) predicted CEP in subjects with MetS with positive and predictive values of 23.5 and 93%, respectively. In apparently healthy subjects, high hsCRP was associated with CEP primarily in subjects without MetS, high Nt-proBNP in subjects with elements of MetS and UACR independently of MetS.

Associations between microalbuminuria and animal foods, plant foods, and dietary patterns in the Multiethnic Study of Atherosclerosis

BACKGROUND

The balance between the intake of animal and the intake of plant foods may influence renal vascular integrity as reflected by urinary albumin excretion.

OBJECTIVE

We assessed cross-sectional associations between urinary albumin excretion and dietary patterns and intake of plant and animal foods.

DESIGN

At baseline, diet (food-frequency questionnaire) and the urinary albumin-to-creatinine ratio (ACR; spot urine collection) were measured in 5042 participants in the Multi-Ethnic Study of Atherosclerosis who were aged 45-84 y and were without clinical cardiovascular disease, diabetes, or macroalbuminuria (sex-adjusted ACR >or= 250). We derived dietary patterns by principal components analysis. We also summed food groups to characterize plant food intake (fruit, fruit juice, vegetables, nuts, legumes, whole grains, and refined grains), animal food intake (red meat, processed meat, poultry, fish, high-fat dairy, and low-fat dairy), and nondairy animal food intake.

RESULTS

After adjustment for multiple demographic and lifestyle confounders, a dietary pattern characterized by high consumption of whole grains, fruit, vegetables, and low-fat dairy foods was associated with 20% lower ACR across quintiles (P for trend = 0.004). Neither total animal nor total plant food intake was associated with ACR. However, greater low-fat dairy consumption was associated with 13% lower ACR across quartiles (P for trend = 0.03). Total nondairy animal food consumption was associated with 11% higher ACR across quintiles (P for trend = 0.03).

CONCLUSIONS

A high intake of low-fat dairy foods and a dietary pattern rich in whole grains, fruit, and low-fat dairy foods were both associated with lower ACR. In contrast, collectively, nondairy animal food intake was positively associated with ACR.

The Diagnostic Value of N-Acetyl-β-D-Glucosaminidase and Microalbumin Concentrations in Rheumatoid Arthritis

The purpose of this research was to compare the diagnostic values of laboratory variables, to present quantitative evaluations of the diagnostic sifted test with reference to sensitivity and specificity, the predictive value of the positive and negative test and precision of the test for N-acetyl-β-D-glucosa-minidase (NAG), microalbumin, rheumatoid factor (RF), Creactive protein (CRP), DAS 28 index, in early diagnosis of untreated rheumatoid arthritis (RA), and to define the effect of untreated rheumatoid arthritis on glomerular and tubular function. Using a colorimetric assay for the determination of Nacetyl-β-D-glucosaminidase and an immunoturbidimetric assay for the determination of urinary albumin, the samples of serum and urine have been examined in 70 participants (35 RA who were not treated, 35 healthy controls). RF was defined with the test for agglutination (Latex RF test) in the same participants. Out of 35 examined patients with RA, in 13 we found the presence of NAG enzymuria (sensitivity of the test 37.14%), while microalbuminuria appeared in 4 patients (sensitivity of the test 11.42%). RF appeared in 17 patients (sensitivity of the test 48.57%). Four patients were NAG and RF positive, while 3 patients were microalbuminuria and RF positive. Among 18 RF negative patients, 9 patients were NAG positive, and 1 patient presented with microalbuminuria. Among 17 RF positive RA, the presence of NAG was found in 4 patients, and the presence of microalbuminuria in 3 patients. Among 18 RF negative RA, NAG enzymuria appeared in 9 patients. Microalbuminuria was present in 1 patient. In the healthy control group, 8 patients were NAG positive, 2 patients were positive for microalbuminuria. RF appeared in 2 patients. NAG has higher sensitivity than microalbuminuria in the detection of asymptomatic renal lesions in untreated RA.

N-terminal brain natriuretic peptide predicted cardiovascular events stronger than high-sensitivity C-reactive protein in hypertension: a LIFE substudy

BACKGROUND

N-terminal pro-brain natriuretic peptide (Nt-proBNP) and high-sensitivity C-reactive protein (hsCRP) are cardiovascular risk markers in various populations, but are not well examined in hypertension. Therefore, we wanted to investigate whether high Nt-proBNP or hsCRP predicted the composite endpoint of cardiovascular death, non-fatal stroke or non-fatal myocardial infarction independently of traditional cardiovascular risk factors and the urine albumin: creatinine ratio (UACR), which is a well established cardiovascular risk factor in hypertension.

METHODS

In 945 hypertensive patients from the LIFE study with electrocardiographic left ventricular (LV) hypertrophy, we measured traditional cardiovascular risk factors including electrocardiography, morning UACR, hsCRP by immunoturbidimetry assay and Nt-proBNP by immunoassay after 2 weeks of placebo treatment. During 55 months' follow-up 80 patients suffered a composite endpoint.

RESULTS

HsCRP as well as Nt-proBNP above the median values of 3.0 mg/l and 170 pg/ml, respectively, was associated with a higher incidence of composite endpoint (13.1 versus 3.8%, P < 0.01, and 11.5 versus 5.4%, P < 0.01). In Cox regression analyses, standardized log(hsCRP)/SD predicted a composite endpoint [hazard ratio (HR) 1.3 per SD = 0.47 log(mg/l), P < 0.05] after adjustment for traditional cardiovascular risk factors, but not after further adjustment for UACR. Standardized log(Nt-proBNP)/SD predicted a composite endpoint after adjustment for traditional cardiovascular risk factors [HR 1.9 per SD = 0.49 log(pg/ml), P < 0.05] as well as after further adjustment for UACR [HR 1.5 per SD = 0.49 log(pg/ml), P < 0.01]. Log(Nt-proBNP) added significantly to the Cox regression models using traditional cardiovascular risk factors with and without UACR (both P < 0.001).

CONCLUSION

Nt-proBNP predicted a composite endpoint after adjustment for traditional risk factors, UACR and a history of diabetes or cardiovascular disease and added significantly to the prediction of composite endpoint, whereas hsCRP did not.

Urinary albumin excretion and the renin-angiotensin system in cardiovascular risk management

Microalbuminuria has been shown to be a strong predictor of cardiovascular morbidity and mortality in diabetic and hypertensive patients, but also in the general population. Moreover, several reports suggest that reduction of urinary albumin excretion (UAE) is associated with improvement of cardiovascular prognosis. Reduction of UAE can be achieved by lowering arterial blood pressure, but blockers of the renin-angiotensin system (RAS) with their specific renal actions have demonstrated to be able to reduce UAE more than might be expected from reduction of blood pressure alone. Consequently, angiotensin-converting enzyme inhibitors and angiotensin receptor blockers may also provide superior cardiovascular protection, especially in subjects with higher levels of albuminuria, but evidence is still scarce. The ability of both angiotensin-converting enzyme inhibitors and angiotensin receptor blockers to reduce UAE and provide cardiovascular protection suggests that the RAS may play a central role. New developments in this area include the use of aldosterone antagonists in albuminuric/proteinuric subjects, and the development of oral renin inhibitors. Combinations of the aforementioned drugs may have the ability to fully block the RAS, potentially avoiding all detrimental effects of this hormonal cascade. However, combination therapy is expected to also increase the incidence of side effects, such as hyperkalaemia and acute renal insufficiency. The current knowledge of microalbuminuria represents the proverbial tip of the iceberg, and future studies should focus on the underlying pathophysiological mechanism of urinary albumin excretion in relation to cardiovascular protection. Only then can a better understanding of the problem be achieved and the optimal pharmacological approach be ascertained.

Does microalbuminuria predict illness severity in critically ill patients on the intensive care unit? A systematic review

CONTEXT

Studies assessing the accuracy of microalbuminuria to predict illness severity on the intensive care unit have produced inconsistent results.

OBJECTIVE

To determine the diagnostic accuracy of microalbuminuria to predict illness severity in critically ill patients on the intensive care unit.

DATA SOURCE

MEDLINE (1951 to September 2004) and EMBASE (1980 to September 2004) electronic databases were searched for relevant studies. Reference lists of all abstracts were manually searched to identify studies not included in the electronic database.

STUDY SELECTION

Studies that prospectively evaluated the accuracy of microalbuminuria to predict illness severity and/or mortality probability in adult patients on the intensive care unit were selected.

DATA EXTRACTION

We included nine studies in the review. Data to evaluate methodological quality and results were abstracted.

DATA SYNTHESIS

The methodological quality of a number of studies was poor. Significant heterogeneity in the design and conduct of the studies circumvented the data being subjected to meta-analysis. Studies also differed in the timing of the index test, in the methods of quantifying microalbuminuria, and in the cutoff values used.

CONCLUSIONS

This descriptive analysis reveals that microalbuminuria may hold promise as a predictor of illness severity and mortality on the intensive care unit. However, future epidemiologic studies need to be conducted to determine the optimal timing as well as the threshold reference value for the urine albumin creatinine ratio in the adult intensive care unit population. Thereafter, multiple-center prospective epidemiologic studies must be conducted to confirm and validate the findings of these preliminary studies. Future studies should conform to the Standards for Reporting of Diagnostic Accuracy checklist in terms of study design, conduct, and reporting. Presently there is no evidence to warrant the use of this tool on the intensive care unit.

A combination of magnetic permeability detection with nanometer-scaled superparamagnetic tracer and its application for one-step detection of human urinary albumin in undiluted urine

A rapid (6.5 min) and simple one-step magnetic immunoassay (MIA) has been developed for analysis of human urinary albumin in near patient settings. Polyclonal rabbit anti-human albumin was used as a capture antibody and monoclonal mouse anti-human albumin as a detection antibody in a two-site immunometric assay requiring no additional washing procedures. The polyclonal anti-human albumin was conjugated to silica microparticles (solid phase) and the monoclonal antibody to dextran-coated nanoscaled superparamagnetic particles (tracer). Quantification of human albumin in undiluted urine was performed by adding 2 microL urine to a measuring vial containing solid-phase, superparamagnetic tracer and reaction buffer and then inverting the vial by hand for 20 s. The measuring vial was allowed to stand for 6 min prior to detection, in order for the solid-phase sediment to form at the bottom of the vial. Lastly, the measuring vial was placed into a magnetic permeability detector, which measured the enrichment of superparamagnetic tracer in the sediment due to complex formation with human albumin. Total analysis time was 6.5 min. A linear response was obtained for 0-400 mg/L albumin with a detection limit of 5 mg/L. The total coefficient of variation (CV) was 11% calculated from four consecutive runs on a urine sample containing 11.1 mg/L human albumin during 3 consecutive days. Human urinary albumin analysis was performed on 149 patient samples using the MIA technique and the obtained results showed good correlation with the hospital immunoturbidimetric reference method (y = 1.004x + 4.01, R2 = 0.978, N = 149) and a commercially available point of care albumin analysis provided by HemoCue Inc. (y = 0.98x + 5.8, R2 = 0.833, N = 90).

High-sensitivity C-reactive protein is only weakly related to cardiovascular damage after adjustment for traditional cardiovascular risk factors

BACKGROUND

The independent prognostic value of high-sensitivity C-reactive protein (hsCRP) has been questioned, and consequently we decided to investigate whether hsCRP was associated with subclinical cardiovascular (CV) damage independently of traditional CV risk factors.

METHODS

In a population-based sample of 2028 apparently healthy individuals without prior stroke or myocardial infarction not receiving any CV, anti-diabetic or lipid-lowering treatment, aged 41, 51, 61 or 71 years, we measured in 1993 serum hsCRP, traditional CV risk factors (lifestyle, metabolic and hemodynamic) and assessed subclinical CV damage [atherosclerotic plaques in the carotid arteries, pulse wave velocity (PWV), urine albumin/creatinine ratio (UACR), left ventricular (LV) mass and ejection fraction].

RESULTS

Adjusting for age and gender in multiple regression analyses, higher log(hsCRP) was associated with higher logPWV (beta = 0.15) and log(left ventricular mass index) (LVMI) (beta = 0.09, both P < 0.001), LV relative wall thickness (beta = 0.07, P < 0.01), logUACR (beta = 0.04, P = 0.06) and more atherosclerotic plaques (beta = 0.06, P < 0.05). However, higher log(hsCRP) was only weakly associated with higher logPWV(beta = 0.06, P < 0.05) and more atherosclerotic plaques (beta = 0.04, P = 0.06) when adjusting for other significant CV risk factors, such as daily smoking (beta = 0.18), female gender (beta = -0.17), older age (beta = 0.11), lower log(high density lipoprotein cholesterol) (beta = -0.11, all P < 0.001); wider waist (beta = 0.17), higher body mass index (beta = 0.14), higher heart rate (beta = 0.06, all P < 0.01); and higher log(plasma glucose) (beta = 0.05, P < 0.05) (adj. R2 = 0.19, P < 0.001).

CONCLUSION

After adjustment for traditional CV risk factors hsCRP was only associated with PWV and atherosclerotic plaques, indicating a possible effect of low-grade inflammation on macrovascular damage. The close relationship between traditional CV risk factors and hsCRP suggested that hsCRP was an integrated CV risk marker early in the development of atherosclerosis.