Monitoring of renal function in cystic fibrosis (CF) patients is essential. The dosage regimen of amikacin is regularly modified according to the patient's glomerular filtration rate (GFR). The aim of the study was to evaluate the use of cystatin C (CyC) for monitoring amikacin therapy along with other markers of renal tubular and glomerular function, and damage [N-acetyl-beta-d glucosaminidase (NAG), creatinine level and creatinine clearance]. We compared the GFR, estimated from the serum concentrations of creatinine (Cockcroft-Gault formula) and CyC (Grubb's formula). Seventy-one patients (mean age 12 years; range 4-28 years) with CF were treated by intermittent intravenous infusion of amikacin. Tubular nephrotoxicity was investigated by measurement of urine NAG/urine creatinine ratio (U-NAG/U-creatinine). Concentrations of all markers were measured before starting amikacin therapy and at days 3, 5, 7, 10 and 12. Fluorescence polarization analysis, turbidimetry, enzymatic phototometric creatinine deaminase method and fluorimetry were used for determination of serum amikacin, serum CyC, creatinine and urine NAG activity. Receiver operating characteristic (ROC) analysis was performed to assess the influence of GFR estimated from serum creatinine and serum CyC for the prediction of amikacin clearance during aminoglycoside therapy. Significant differences in the rate of U-NAG/U-creatinine were noted before and after treatment with amikacin (P < 0.001). Serum creatinine levels and creatinine clearance at the end of amikacin therapy (12th day) did not show any significant differences in comparison with the levels measured before the start of therapy (0th day). At days 5, 7, 10 and 12, serum CyC levels showed a significant elevation (P < 0.001), and CyC clearance showed a significant decrease (P < 0.001) in comparison with the levels measured at day 0. The ratio of amikacin clearance/creatinine clearance decreased with therapy whereas the amikacin clearance/CyC and amikacin clearance/CyC clearance increased. We showed that the rate of U-NAG/U-creatinine is a suitable marker for monitoring tubular nephrotoxicity in CF patients. Serum creatinine and estimated creatinine clearance are modest predictors of GFR in CF patients. CyC appears to be a better marker of GFR than serum creatinine concentration or creatinine clearance in our study. Serum CyC levels and CyC clearance showed greater ability to predict amikacin clearance during therapy than creatinine clearance.

We investigated the performance of brain natriuretic peptides (BNP and NT-proBNP) in detecting various degrees of left ventricular systolic dysfunction. The NT-proBNP assay (Roche) and the BNP assay (Bayer Shionoria) were performed in 46 patie...

The α-defensins (AD) present in synovial fluid have been regarded as constituting the most accurate periprosthetic joint infection (PJI) biomarker. The methods most commonly used for estimating AD as a biomarker are the qualitative Synovasure^® PJI tests, based on the technique of lateral flow, and quantitative enzyme-linked immunosorbent assay (ELISA). Here, we propose a novel test based on detecting α-defensins in synovial fluid by high-performance liquid chromatography (HPLC). Synovial fluid was collected from 157 patients diagnosed with PJI, infectious arthritis (IA), arthrosis, reactive arthritis, and rheumatoid arthritis. AD concentrations in the fluid were determined by HPLC, and these same samples were used for additional diagnostic analyses. The results were statistically processed to calculate cutoff concentrations for PJI and IA. HPLC testing showed a sensitivity of 94% and a specificity of 92% for diagnosis of PJI, and a sensitivity of 97% and a specificity of 87% for diagnosis of IA. Using HPLC, we detected in synovial fluid a combination of three α-defensins: human neutrophil peptides HNP1, HNP2, and HNP3. All measured AD concentration values shown in this work refer to the sum of these three individual concentrations. Our study shows that the HPLC method meets the conditions for measuring precise concentrations of the sum of AD and can be recommended as part of a diagnostic array for PJI and IA diagnostics. By this method, we have verified that higher levels of AD in synovial fluid can also be seen in rheumatoid illnesses, crystal arthropathies, and reactive arthritis.