Liquid Plasticine Integrated with Isoelectric Focusing for Miniaturized Protein Analysis.

Developing miniaturized and rapid protein analytical platforms is urgently needed for on-site protein analysis, which is important for disease diagnosis and monitoring. Liquid marbles (LMs), a kind of particle-coated droplets, as ideal microreactors have been used in various fields. However, their application as analytical platforms is limited due to the difficulty of pretreating complex samples in simple LMs. Herein, inspired by the microfluidic chip, we propose a strategy through fabricating fluid channels using deformable LM, termed liquid plasticine (LP), to achieve sample pretreatment function. Through combining isoelectric focusing (IEF) with an LP channel, an LP-IEF platform with simultaneous protein separation and concentration functions is realized. The pretreatment capability of the LP-IEF system for proteins in physiological samples is proven using standard proteins and human serum with the results of a clear separation, 10-fold concentration, and a resolution of 0.03 pH. Through cutting the LP after IEF to LMs and transiting isolated LMs containing target proteins for further downstream colorimetric and mass spectrometry measurements, the quantitative analysis of clinical microalbuminuria and identification of α-1-microglobulin/bikunin precursor in clinical diabetic urine samples are achieved. This work proposes a strategy to develop LMs/LPs as a multifunctional integrated analytical platform and the miniaturized LP-IEF device as a rapid protein analytical platform.

Pancreatic cancer biomarker detection by two support vector strategies for recursive feature elimination.

AIM: Pancreatic cancer is one of the worst malignant tumors in prognosis. Therefore, to reduce the mortality rate of pancreatic cancer, early diagnosis and prompt treatment are particularly important. RESULTS: We put forward a new feature-selection method that was used to find clinical markers for pancreatic cancer by combination of Support Vector Machine Recursive Feature Elimination (SVM-RFE) and Large Margin Distribution Machine Recursive Feature Elimination (LDM-RFE) algorithms. As a result, seven differentially expressed genes were predicted as specific biomarkers for pancreatic cancer because of their highest accuracy of classification on cancer and normal samples. CONCLUSION: Three (MMP7, FOS and A2M) out of the seven predicted gene markers were found to encode proteins secreted into urine, providing potential diagnostic evidences for pancreatic cancer.

Discovery and Qualification of Candidate Urinary Biomarkers of Disease Activity in Lupus Nephritis.

Lupus nephritis (LN) is a severe clinical manifestation of systemic lupus erythematosus (SLE) associated with significant morbidity and mortality. Assessment of severity and activity of renal involvement in SLE requires a kidney biopsy, an invasive procedure with limited prognostic value. Noninvasive biomarkers are needed to inform treatment decisions and to monitor disease activity. Proteinuria is associated with disease progression in LN; however, the composition of the LN urinary proteome remains incompletely characterized. To address this, we profiled LN urine samples using complementary mass spectrometry-based methods:  protein gel fractionation, chemical labeling using tandem mass tags, and data-independent acquisition. Combining results from these approaches yielded quantitative information on 2573 unique proteins in urine from LN patients. A multiple-reaction monitoring (MRM) method was established to confirm eight proteins in an independent cohort of LN patients, and seven proteins (transferrin, α-2-macroglobulin, haptoglobin, afamin, α-1-antitrypsin, vimentin, and ceruloplasmin) were confirmed to be elevated in LN urine compared to healthy controls. In this study, we demonstrate that deep mass spectrometry profiling of a small number of patient samples can identify high-quality biomarkers that replicate in an independent LN disease cohort. These biomarkers are being used to inform clinical biomarker strategies to support longitudinal and interventional studies focused on evaluating disease progression and treatment efficacy of novel LN therapeutics.

Differentiation of protein species of alpha-2u-globulin according to database entries: A half-theoretical approach.

The alpha-2u-globulin protein, the main subject of this study, is the most abundant protein in adult male rat urine. In this investigation there are 19 spots identified as alpha-2u-globulin by 2-DE and MALDI-TOF/TOF-MS. All of them are in the low molecular weight region, at approximately 15-25kDa. Searches within both, SwissProt and NCBI databases gave different from each other, but on the majority the same database entry as the highest ranked result for all spots. For this half-theoretical approach all entries from the NCBI database for the protein alpha-2u-globulin were considered in more detail. The sequences and the masses of the theoretically resulting tryptic peptides were compared with the PMF spectra of the spots identified as alpha-2u-globulin. This study presents a trial to distinguish between different protein species of that protein, only on the amino acid level. Other modifications like phosphorylation, glycosylation or any other group modification could not be considered here. Different protein species can be predicted for groups of closer positioned spots. Statements about which spot contains which peptide variant can be done, too. But it was found that several spots contain more than one protein species. BIOLOGICAL SIGNIFICANCE: In this investigation a half-theoretically approach was shown to differentiate between protein species of different spots identified as the same protein. Different positions of spots in 2-DE gels mean different contents of protein species. Here, peptide masses from sequences of protein database entries were searched in the PMF spectra of alpha-2u-globulin. Different peptide variants could be assigned to different spots. It was also found that several spots contain more than one peptide variant and therefore more than one protein species. In addition, the insufficiency of the database has been demonstrated.

Low-grade proteinuria is highly prevalent in HIV-positive patients on antiretroviral treatment.

OBJECTIVES: HIV-positive patients are at an increased risk for chronic kidney disease. However, these data mainly derive from cohorts with a high percentage of African-American patients, representing a specific ethnical risk group for chronic kidney disease. The aim of this study was to estimate the prevalence and risk factors specifically for early signs of kidney dysfunction in a large, predominantly white cohort of HIV patients. DESIGN: Cross-sectional study. METHODS: Prevalence of low-grade proteinuria was measured by quantitative analysis of urinary protein-to-creatinine ratio (cutoff >70 mg/g) and further differentiated by assessing α1-microglobulin (tubular proteinuria) and albumin-to-creatinine ratio (glomerular proteinuria) of HIV patients attending the University Hospital in Cologne, Germany. Together with standard and HIV-related laboratory findings and medical history, risk factors for each form of proteinuria were identified using multivariate forward selection. RESULTS: Of 945 enrolled patients, 55% were identified with low-grade proteinuria, 41% with tubular proteinuria, and 20% with glomerular proteinuria. Older age was a risk factor for all forms of proteinuria in multivariate analysis. Low-grade proteinuria was also associated with concomitant diabetes and exposure to nucleoside reverse transcriptase inhibitor [anytime during HIV infection, not tenofovir (TDF)-specific], whereas tubular proteinuria was linked to current and any exposure to nucleoside reverse transcriptase inhibitor (TDF-specific). Further risk factors for glomerular proteinuria were hypertension and diabetes in this cohort. CONCLUSION: Low-grade, glomerular and tubular proteinuria are highly prevalent in this large white HIV cohort. Older age represents a nonmodifiable risk factor for all forms of proteinuria. Glomerular proteinuria is associated with modifiable cardiovascular, but not HIV-related risk factors, whereas tubular proteinuria is linked to TDF exposure.

Urine protein biomarkers for the diagnosis and prognosis of necrotizing enterocolitis in infants.

OBJECTIVES: To test the hypothesis that an exploratory proteomics analysis of urine proteins with subsequent development of validated urine biomarker panels would produce molecular classifiers for both the diagnosis and prognosis of infants with necrotizing enterocolitis (NEC). STUDY DESIGN: Urine samples were collected from 119 premature infants (85 NEC, 17 sepsis, 17 control) at the time of initial clinical concern for disease. The urine from 59 infants was used for candidate biomarker discovery by liquid chromatography/mass spectrometry. The remaining 60 samples were subject to enzyme-linked immunosorbent assay for quantitative biomarker validation. RESULTS: A panel of 7 biomarkers (alpha-2-macroglobulin-like protein 1, cluster of differentiation protein 14, cystatin 3, fibrinogen alpha chain, pigment epithelium-derived factor, retinol binding protein 4, and vasolin) was identified by liquid chromatography/mass spectrometry and subsequently validated by enzyme-linked immunosorbent assay. These proteins were consistently found to be either up- or down-regulated depending on the presence, absence, or severity of disease. Biomarker panel validation resulted in a receiver-operator characteristic area under the curve of 98.2% for NEC vs sepsis and an area under the curve of 98.4% for medical NEC vs surgical NEC. CONCLUSIONS: We identified 7 urine proteins capable of providing highly accurate diagnostic and prognostic information for infants with suspected NEC. This work represents a novel approach to improving the efficiency with which we diagnose early NEC and identify those at risk for developing severe, or surgical, disease.

Urinary IgG and α2-macroglobulin are powerful predictors of outcome and responsiveness to steroids and cyclophosphamide in idiopathic focal segmental glomerulosclerosis with nephrotic syndrome.

OBJECTIVE: To assess whether high-molecular-weight proteins excretion predicts outcome and therapy-responsiveness in patients with FSGS and nephrotic syndrome. RESEARCH DESIGN AND METHODS: Thirty-eight patients measured at biopsy fractional excretion of IgG (FEIgG) and urinary α2-macroglobulin/creatinine ratio ( α m/C). Low and high risk groups were defined by cutoffs assessed by ROC analysis. In all patients first-line therapy was with steroids alone or in combination with cyclophosphamide. RESULTS: α2m/C and FEIgG were correlated with segmental sclerosis (r = 0.546; r = 0.522). Twenty-three patients (61%) entered Remission and 9 (24%) progressed to ESRD. Comparing low and high risk groups, by univariate analysis remission was predicted by FEIgG (77% versus 25%, P = 0.016) and α2m/C (81% versus 17%, P = 0.007) and ESRD at best by FEIgG (0% versus 75%, P < 0.0001) and α2m/C (4% versus 67%, P < 0.0001). By multivariate analysis FEIgG was the only independent predictor of remission and α2m/C the most powerful predictor of ESRD. Low and high risk groups of FEIgG and α2m/C in combination had very high predictive value of sustained remission and ESRD in response to therapy. CONCLUSIONS: FEIgG and α2m/C are powerful predictors of outcome and responsiveness to steroids and cyclophosphamide; their predictive value, if validated in prospective studies, may be useful in clinical practice suggesting first-line alternative treatments in high risk patients.

[Significance of urinary biomarkers in differential diagnosis of acute tubulointerstitial nephritis].

OBJECTIVE: To find some urinary biomarkers with significance in the differentiation of drug-induced tubulointerstitial nephritis (DTIN). METHODS: Forty patients with biopsy-proven DTIN were enrolled. The urine samples of DTIN patients were collected on the day of biopsy and all urine samples were measured for the following different biomarkers as indicated, respectively: urinary TGF-beta by ELISA; urinary IL-6 by radio-immunoassay; NAG by an enzyme-substrate colorimetric assay; alpha1-MG by immune transmission turbidity method. Receiver operating characteristic curves (ROC curve) were constructed to calculate the sensitivity and specificity of those biomarkers in distinguishing acute (A-DTIN) and chronic DTIN (C-DTIN). RESULTS: Urinary NAG and alpha1-MG levels in patients with A-DTIN were as 2.5 and 2.1 times as those in C-DTIN (P<0.05), while urinary TGF-beta levels in the two groups had no statistical difference. The areas under ROC curve (AUC) of urinary NAG and alpha1-MG for differentiating A-DTIN were 0.720 (P=0.029) and 0.714 (P=0.034) respectively, while the AUCs for TGF-beta and IL-6 were 0.536 (P=0.767) and 0.150 (P=0.004) respectively. Combined measurement of NAG and alpha1-MG could make sensitivity and specificity reach 78.6% and 75.0 % respectively. CONCLUSION: Urinary alpha1-MG and NAG levels can reflect the acute lesions of DTIN, and combined measurement of both could enhance efficiency in differentiating A-DTIN.

Renal function and volume of infants born with a very low birth-weight: a preliminary cross-sectional study.

AIM: The aim of our study was to compare the function and volumes of kidneys of very low birth-weight (VLBW) and of extremely low birth-weight (ELBW) infants at pre-school ages. PATIENTS AND METHODS: We did a revision of the neonatal records of infants born in our hospital that weighed < or =1500 g at birth. The children were divided into two groups according to their weight at birth: ELBW (<1000 g) and VLBW (1000-1500 g). At the age of 5.7 +/- 1.4 years, the children underwent clinical, laboratory and ultrasound renal assessments. RESULTS: Sixty-nine children fulfilled the requirements for the study. The rate of neonatal treatment with aminoglycosides was higher in ELBW preterms. Renal function parameters, i.e. estimated glomerular filtration rate and albuminuria, did not differ between the two groups of children. Urinary alpha1-microglobulin excretion was significantly higher and kidneys were significantly smaller in the ELBW group than in the VLBW group. CONCLUSION: No impairment or differences in renal parameters were found in pre-school children born ELBW compared with those born with VLBW, except for differences in kidney volume, renal cortical thickness and urinary alpha1-microglobulin excretion. Thus, patients born with ELBW would require a longer follow-up period.

Comparative analysis of urinary biomarkers for early detection of acute kidney injury following cardiopulmonary bypass.

The purpose of this study was to compare the performance of six candidate urinary biomarkers, kidney injury molecule (KIM)-1, N-acetyl-beta-D-glucosaminidase (NAG), neutrophil gelatinase-associated lipocalin (NGAL), interleukin (IL)-18, cystatin C and alpha-1 microglobulin, measured 2 h following cardiopulmonary bypass (CPB) for the early detection of acute kidney injury (AKI) in a prospective cohort of patients undergoing cardiac surgery. A total of 103 subjects were enrolled; AKI developed in 13%. Urinary KIM-1 achieved the highest area under-the-receiver-operator-characteristic curve (AUC 0.78, 95% confidence interval 0.64-0.91), followed by IL-18 and NAG. Only urinary KIM-1 remained independently associated with AKI after adjustment for a preoperative AKI prediction score (Cleveland Clinic Foundation score; p = 0.02), or CPB perfusion time (p = 0.006). In this small pilot cohort, KIM-1 performed best as an early biomarker for AKI. Larger studies are needed to explore further the role of biomarkers for early detection of AKI following cardiac surgery.

In crescentic IgA nephropathy, fractional excretion of IgG in combination with nephron loss is the best predictor of progression and responsiveness to immunosuppression.

BACKGROUND AND OBJECTIVES: The aim of this study was to evaluate the relationship between proteinuric markers (urinary excretion of IgG, alpha2-macroglobulin, alpha1-microglobulin) and serum creatinine (sCr), histologic lesions, progression, and immunosuppression responsiveness in crescentic IgA nephropathy. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Fractional excretion of IgG (FEIgG) and of alpha1-microglobulin and urinary excretion of alpha2-macroglobulin were evaluated in 37 patients, 23 treated with steroids and cyclophosphamide. For assessment of the effective tubular load of proteins in surviving nephrons, new markers that take into account not only the absolute excretion value but also nephron loss were obtained dividing proteinuric markers for percentage of nonobsolescent glomeruli (surviving glomeruli [SG]). For each parameter, low- and high-risk groups were defined according to cutoffs with the highest sensitivity and specificity for progression (ESRD/doubling sCr) assessed by receiver operating characteristic analysis; follow up was 60 +/- 40 mo. RESULTS: FEIgG/SG is the most powerful progression predictor: 5 versus 83% in all patients; in treated patients, 0 versus 89%, increased to 0 versus 100% by sCr and FEIgG/SG in combination (low risk: both markers or only one below cutoff (n = 15); high risk: both markers above cutoff (n = 8). The nonprogressors showed at last observation 65% proteinuria reduction and 10% sCr reduction. CONCLUSIONS: In crescentic IgA nephropathy, FEIgG/SG, which evaluates altered size selectivity in relation to nephron loss, is the best progression predictor. In treated patients, progression prediction was increased by FEIgG/SG and sCr in combination. Treatment may be restricted to low-risk patients.

[Evaluation of inflammatory and renal injury markers in youngest children with pyelonephritis]. / Ocena wskazników zapalenia i uszkodzenia nerek u najmlodszych dzieci chorych na odmiedniczkowe zapalenie nerek.

UNLABELLED: Pyelonephritis (PN) is frequent bacterial infections in young infants and very important because may cause parenchymal scarring. Early confirmation of bacterial infection and application the appropriate treatment before obtaining result of urine culture, reduce probability of parenchymal scarring. THE AIM OF THE STUDY: To evaluate the useful of inflammatory and renal injury markers: serum procalcitonin (PCT), tumor necrosis factor alpha (TNF-alpha) and injury renal marker alpha1--microglobulin (A1M) measurement, in comparison with C-reactive protein concentration and abnormal urinary tract, in neonates and young infants with pyelonephritis. MATERIAL AND METHODS: Investigation was performed in two groups: I group--23 children with PN (1 to 24 weeks of age), and K group--30 healthy children aged from 1 to 24 weeks. Serum concentration of CRP was measured by immunonephelometric assay, PCT by immunoluminometric assay, TNF alpha by ELISA method, and urinary A1M by nephelometric assay. RESULTS: In control group (K) medians of all investigated markers were below minimum of detection. PN patients (I) had the highest PCT TNF-alpha, A1M and CRP concentration before treatment and normal results after antibiotic treatment. Using a cut-off: of 0.5 mg/dl for CRP, 0.5 ng/ml for PCT 15 pg/ml for TNF-alpha and 10 mg/g cr for A1M, sensitivity and specificity in children with pyelonephritis were: for CRP 100% and 62.5%, for PCT 81.8% and 87.2%, for TNF alpha 77.1% and 93.1% and A1M 70.4% and 56.1%, respectively. A positive correlation between serum PCT and CRP and TNF alpha was found. Very high concentration all markers were in patients with vesicoureteral reflux and 1 patient with hydronephrosis. CONCLUSION: In early diagnostics of PN (before obtaining results of urine culture) in youngest children, determination of concentration PCT and TNF alpha, has higher value than determination of CRP, taking into concentration high sensitivity and specificity for bacterial infection.

Detection of subclinical tubular injury after renal transplantation: comparison of urine protein analysis with allograft histopathology.

BACKGROUND: Tubulointerstitial injury due to rejection leads to tubular atrophy (TA)/interstitial fibrosis (IF) followed by deterioration of allograft function. This study investigated whether urinary tubular injury biomarkers can detect subclinical tubulitis found in protocol biopsies allowing for a noninvasive screening procedure. METHODS: Four rigidly defined groups (stable transplants with normal tubular histology [n=24], stable transplants with subclinical tubulitis [n=38], patients with clinical tubulitis Ia/Ib [n=18], and patients with other clinical tubular pathologies [n=20]) were compared for differences in urinary intact/cleaved beta2-microglobulin (i/cbeta2m), retinol-binding protein (RBP), neutrophil-gelatinase-associated lipocalin (NGAL), and alpha1-microglobulin (alpha1m). RESULTS: Tubular proteinuria was present in 38% (RBP) to 79% (alpha1m) of patients in the stable transplant with normal tubular histology group. The stable transplant with subclinical tubulitis group had slightly higher levels of i/cbeta2m (P=0.11), RBP (P=0.17), alpha1m (P=0.09), and NGAL (P=0.06) than the stable transplant with normal tubular histology group with a substantial overlap. The clinical tubulitis Ia/Ib and the other clinical tubular pathology groups had significantly higher levels of RBP, NGAL, and alpha1m than stable transplants with normal tubular histology or stable transplants with subclinical tubulitis (P<0.002). CONCLUSIONS: None of the investigated biomarkers allow for clear differentiation between stable transplants with normal tubular histology and stable transplants with subclinical tubulitis. Therefore, the protocol allograft biopsy currently remains the preferred tool to screen for subclinical tubulitis. Further longitudinal studies should determine whether tubular proteinuria in stable transplants with normal tubular histology indicates a clear risk for early development of TA/IF.

Increased urinary excretion of alpha1-microglobulin at 6 months after transplantation is associated with urinary excretion of transforming growth factor-beta1 and indicates poor long-term renal outcome.

BACKGROUND: Albumin and alpha1-microglobulin (alpha1M) are absorbed by two specific receptors in tubular epithelial cells. Any cell injury will disturb the reabsorption of these proteins, The increased urinary excretions of albumin or alpha1M could thus serve as a marker of subclinical graft lesions and as an early indicator of chronic allograft dysfunction. METHODS: We measured 24-hour urinary excretions of albumin, alpha1M, and transforming growth factor (TGF)-beta1 at 6 months after transplantation in 79 renal-graft recipients and recorded the changes in 24-hour creatinine clearance an average 51 (range 14-72) posttransplant follow-up months. RESULTS: At 6 months from transplantation, 46 of 79 (58%) patients were normoalbuminuric, 25 (32%) microalbuminuric, and 8 (10%) macroalbuminuric. In normoalbuminuric patients, urinary alpha1M/creatinine ratio was 10 times, and TGF-beta1/creatinine ratio approximately 5 times, higher than in the healthy subjects but lower than in albuminuric patients. In all patients, urinary alpha1M correlated with urinary TGF-beta1 (r=0.508, P<0.001), with albumin (r=0.220, P<0.05), and with the annual changes in 24-hour creatinine clearance (r=-0.273, P<0.05). During follow-up, renal function deteriorated in 20 of 33 (60%) patients with alpha1M/creatinine ratio greater than 5 mg/mmol, but only in 1 of 46 (2%) patients whose ratio was less than 5 mg/mmol (P<0.01), giving the ratio 5 mg/mmol or greater a 95% sensitivity to detect patients with poor long-term outcome. CONCLUSIONS: We show proximal tubular injury, measured by increased urinary alpha1M, to be present even in normoalbuminuric patients and to be associated with increased excretion of TGF-beta1 and with the annual deterioration of glomerular filtration rate. These findings show increased alpha1M/creatinine ratio to be an early and sensitive indicator of poor long-term outcome in renal-transplant patients.

Compositional analyses of a human menopausal gonadotrophin preparation extracted from urine (menotropin). Identification of some of its major impurities.

Recently, a highly purified human menopausal gonadotrophin preparation (HMG) was launched. The composition and purity of this HMG (Menopur); Ferring Pharmaceuticals) with a claimed 1:1 ratio of FSH and LH was determined. Three gonadotrophins were observed: FSH, LH and human chorionic gonadotrophin (HCG). The immunoactivity for HCG was three-fold higher than the immunoactivity for LH. Because of the longer half-life of HCG as compared with LH, about 95% of the in-vivo LH-receptor-mediated bioactivity is attributable to the presence of HCG. This is substantiated by biochemical analyses. To the best of the authors' knowledge, this relatively high amount of HCG can only be explained by assuming the addition of HCG from external sources, which is a well established practice for standardization purposes. In addition to gonadotrophins, a number of other proteins were detected. The amount of these impurities, as determined by reversed-phase high-performance liquid chromatography on a peak-area basis, is at least 30%. Therefore, it is concluded that this HMG preparation contains at most 70% gonadotrophins. Via a proteomics approach three major impurities were identified: leukocyte elastase inhibitor, protein C inhibitor, and zinc-alpha(2)-glycoprotein. On the basis of the results obtained in this study, a comparison is made with recombinant FSH.

Urinary plasma protein patterns in acute prostatitis.

We evaluated the diagnostic utility of urinary alpha1-microglobulin, alpha2-macroglobulin and albumin in the diagnosis of acute prostatitis. We studied 133 men (43 +/- 17 years) with, and a reference population (n=36, 41 +/- 16 years) without, urinary tract infection. Prostatectomy samples were used to study the potential interference between prostatic proteins and protein analysis. Urinary alpha2-macroglobulin/albumin ratio was significantly lower in prostatitis compared to the reference population, cystitis or acute pyelonephritis (p < 0.0001). Low alpha2-macroglobulin concentrations in prostatitis are due to inhibition (p = 0.0001) of the immune reaction between alpha2-macroglobulin in presence of polyclonal rabbit antibodies (used for immunonephelometry) by soluble prostatic proteins (+/- 60 kDa) which appear in urine in acute prostatitis. The urinary alpha1-microglobulin/creatinine ratio diagnoses acute pyelonephritis (sensitivity 100% and specificity 87%) and the urinary alpha2-macroglobulin/albumin ratio diagnoses acute prostatitis (sensitivity 100% and specificity of 90%). Stepwise multinomial logistic regression analysis reveals that urinary alpha1-microglobulin, alpha2-macroglobulin, albumin and creatinine provide optimal differentiation between acute pyelonephritis and acute prostatitis (pseudo R2=0.83; Loglikelihood -30.55, p < 0.000001). In conclusion, the combination of hematuria and absence of urinary alpha-2-macroglobulin is diagnostic for acute prostatitis. Even without hematuria, alpha2-macroglobulin remains lower compared to patients without prostatitis.

[Laboratory identification and measurement of urinary proteins]. / Identification et dosage des protéines urinaires au laboratoire d'analyses.

A permanent and quantitatively abnormal proteinuria (> 150 mg/ 24 h) found at the laboratory should be followed by an identification and quantification of all proteins present. Specific immunochemistry techniques (immunoturbidimetric or immuno-nephelometric) are almost exclusively used for measuring albumin (or microalbuminuria) in nephropathic diabetic patients. Measurement of monoclonal free light chains is not recommended due to poor accuracy. Determination of other small proteins (molecular mass, MM < 40 kDa), transferrine, immunoglobulins G (assessment of selectivity) is far less frequent and Tamm-Horsfall protein is measured in specialized laboratories. Global electrophoresis techniques are the reference methods for the study of urinary proteins. Significant progress have been made during the past ten years in terms of sensitivity (analysis down to 50 mg/L total protein with no need to concentrate urinary specimens) and separation (high resolution or according to MM). Improvement in sensitivity is a key point for the diagnostic and follow-up of low grade or treated gammapathies. Electrophoretic separation according to MM is perfectly adapted to visual typing of renal proteinuria (glomerular, tubular or mixed) and overload proteinuria, particularly by monoclonal free light chains (MM: 25 kDa, Bence Jones proteinuria) allowing their quantification by densitometry. Immunofixation combining electrophoresis and immunoprecipitation in gel has emerged as the reference technique to identify monoclonal proteins. Data obtained by urinary protein analysis need to be compared with serum results for interpretation.

Long-term monitoring of renal function in poly-traumatized intensive care patients.

INTRODUCTION: For the long-term monitoring of kidney function, polytraumatized patients were examined and routine as well as specialized parameters were compared. MATERIALS AND METHODS: 30 patients of the Surgical Intensive Care Unit (ICU) were examined daily over the entire period they stayed in the ICU. The patients were retrospectively classified as either survivors or deceased patients. Group 1 consisted of 20 patients who resided in the ICU for 11-15 (Median 14) days before they could be transferred to a normal hospital unit. Group 2 consisted of 10 patients who had passed away after 13-18 (Median 16) days in the ICU. In addition to the routine parameters diuresis, serum creatinine and serum urea, specialized parameters for kidney function including the excretion rates of alpha1-microglobulin (alpha1-MG), N-Acetyl-beta-D-glucosaminidase (NAG), angiotensinase A (ATA) and immunoglobulin G (IgG) were determined. RESULTS: Similar biometric data were shown by all patients at admission into the ICU, but differences did exist regarding the Revised Trauma Score, Injury Severity Score and the APACHE-II-Score. In the period between the 5th and 8th day of intensive treatment almost all patients showed pathological excretion rates of tubular and glomerular parameters whereby no increased frequency of unusual events could be determined at these time-points. CONCLUSION: During treatment in the ICU, all examined patients showed at times pathological excretion rates of specialized kidney function parameters. Such transient damage was only apparent in a few of the patients when the standard parameters serum creatinine and serum urea were employed. In 90% of the surviving patients the kidney parameters had normalized until the time they were transferred, indicating that such parameters reflected the general state of health of these patients.