Anu Pätäri-Sampo

Molecular basis of the glomerular filtration: Nephrin and the emerging protein complex at the podocyte slit diaphragm

For more than three decades, the molecular composition of the interpodocyte slit diaphragm of the glomerular filtration barrier has remained elusive. The first electron microscopic studies described the slit diaphragm as a porous, ‘zipper‐like’ structure, but it was not until 1998 that the first transmembrane molecule of the slit diaphragm was identified: nephrin is a cell surface receptor of the immunoglobulin superfamily participating in cell‐cell adhesion and signaling functions. Mutations in nephrin lead to the congenital nephrotic syndrome of the Finnish type, suggesting that nephrin is of pivotal importance for maintaining the filtration barrier. In recent years, the mapping of the genetic background of other inherited and acquired nephropathies and generation of transgenic animal models have led to a beginning of a new era in nephrology, possibly promising new targeted therapies and advanced diagnostics. This review article will briefly summarize the main findings that explain the molecular architecture of the glomerular filter itself and causes of some glomerular diseases that lead to proteinuria and, eventually, to renal failure.

Increase of prostate biopsy-related bacteremic complications in southern Finland, 2005-2013: a population-based analysis.

BACKGROUND:The most severe manifestations of prostate biopsy complications are bacteremic infections. These complications are increasing alarmingly.METHODS:A retrospective cohort study of 17 183 transrectal prostate biopsies performed at the Helsinki and Uusimaa hospital district in southern Finland during 2005–2013. Biopsies were linked to a database of positive blood cultures, yielding 111 bacteremic cases, and yearly bacteremia rates were determined. By multiple regression analysis, demographic risk factors of the whole biopsy cohort for developing bacteremia or fluoroquinolone (FQ)-resistant bacteremia were studied. Clinical risk factors for bacteremia caused by an FQ-resistant organism and for serious bacteremic outcomes were studied by univariate and multivariate analyzes.RESULTS:The average bacteremia rate was 0.7% (111 of 17 183 biopsies) and an increase was observed from 0.5% in 2005 (95% confidence interval (CI): 0.3–0.9) to 1.2% in 2012 (95% CI 0.8–1.8); 53.2% were caused by an FQ-resistant organism. In univariate regression analysis, previous biopsy sessions and increasing calendar year of biopsy associated with the risk of developing bacteremia (odds ratio (OR) 1.232, 95% CI: 1.020–1.488, P=0.030 and OR 1.164, 95% CI: 1.079–1.255, P<0.001, respectively), but only increasing calendar year of biopsy remained statistically significant (OR 1.155, 95% CI: 1.070–1.247, P<0.001) in multivariate analysis. Foreign travel within 3 months was associated with FQ resistance in multivariate analysis (OR 7.158, 95% CI: 1.042 to infinite, P=0.045). The study failed to show any significant clinical risk factors for serious bacteremic outcomes (requiring intensive care, developing deep infection foci or death).CONCLUSIONS:The postbiopsy bacteremia rate doubled during the study period and half of the cases were caused by FQ-resistant organisms. Recent foreign travel increased the risk for FQ resistance. Future research efforts should be aimed at better identifying risk factors, targeted prophylaxis and reducing the need for biopsies.

Amniotic fluid rapid biomarkers are associated with intra-amniotic infection in preterm pregnancies regardless of the membrane status

Objective:The objective of this study was to evaluate the association of amniotic fluid lactate dehydrogenase and glucose concentrations with microbial invasion of amniotic cavity and histologic chorioamnionitis before 37 pregnancy weeks in women with or without preterm premature rupture of membranes.Study Design:Amniocentesis was performed on 70 women with suspected intra-amniotic infection. Standard biochemical methods, molecular microbiology and culture techniques were used. Histopathological examination of the placenta was performed.Results:Thirty (48%) women had microbial invasion of the amniotic cavity (MIAC), 53 (76%) women had histological chorioamnionitis and 28 women had both. The cutoff values for MIAC and histological chorioamnionitis were 429 IU l−1 for lactate dehydrogenase and 0.7 mmol l−1 for glucose. Both end points occurred equally often regardless of the membrane status.Conclusion:Increased amniotic fluid lactate dehydrogenase and decreased glucose were associated with MIAC and histological chorioamnionitis. However, test performance was of limited value.

Identification of urinary tract pathogens after 3-hours urine culture by MALDI-TOF mass spectrometry

Complicated urinary tract infections, such as pyelonephritis, may lead to sepsis. Rapid diagnosis is needed to identify the causative urinary pathogen and to verify the appropriate empirical antimicrobial therapy. We describe here a rapid identification method for urinary pathogens: urine is incubated on chocolate agar for 3h at 35°C with 5% CO2 and subjected to MALDI-TOF MS analysis by VITEK MS. Overall 207 screened clinical urine samples were tested in parallel with conventional urine culture. The method, called U-si-MALDI-TOF (urine short incubation MALDI-TOF), showed correct identification for 86% of Gram-negative urinary tract pathogens (Escherichia coli, Klebsiella pneumoniae, and other Enterobacteriaceae), when present at >10(5)cfu/ml in culture (n=107), compared with conventional culture method. However, Gram-positive bacteria (n=28) were not successfully identified by U-si-MALDI-TOF. This method is especially suitable for rapid identification of E. coli, the most common cause of urinary tract infections and urosepsis. Turnaround time for identification using U-si-MALDI-TOF compared with conventional urine culture was improved from 24h to 4-6h.

Amniotic Fluid Infection in Preterm Pregnancies with Intact Membranes

Introduction. Intra-amniotic infection (IAI) is a major cause of preterm labor and adverse neonatal outcome. We evaluated amniotic fluid (AF) proteolytic cascade forming biomarkers in relation to microbial invasion of the amniotic cavity (MIAC) and IAI in preterm pregnancies with intact membranes. Material and Methods. Amniocentesis was made to 73 women with singleton pregnancies; 27 with suspected IAI; and 46 controls. AF biomarkers were divided into three cascades: Cascade 1: matrix metalloproteinase-8 (MMP-8), MMP-9, myeloperoxidase (MPO), and interleukin-6; Cascade 2: neutrophil elastase (HNE), elafin, and MMP-9; Cascade 3: MMP-2, tissue inhibitor of matrix metalloproteinases-1 (TIMP-1), MMP-8/TIMP-1 molar ratio, and C-reactive protein (CRP). MMP-8 was measured by an immunoenzymometric assay and the others were measured by ELISA. Standard biochemical methods, molecular microbiology, and culture techniques were used. Results. MMP-8, MMP-9, MPO, elafin, and TIMP-1 concentrations were higher in IAI suspected cases compared to controls and also in IAI suspected cases with MIAC compared to those without MIAC when adjusted by gestational age at amniocentesis. All biomarkers except elafin and MMP-2 had the sensitivity of 100% with thresholds based on ROC-curve. Odd ratios of biomarkers for MIAC were 1.2-38 and 95% confidential intervals 1.0-353.6. Conclusions. Neutrophil based AF biomarkers were associated with IAI and MIAC.

Comparison of amniotic fluid matrix metalloproteinase-8 and cathelicidin in the diagnosis of intra-amniotic infection

Objective:To evaluate the association of amniotic fluid (AF) matrix metalloproteinase-8 (MMP-8) and cathelicidin concentrations with microbial invasion of the amniotic cavity (MIAC) in pregnancies with preterm prelabor rupture of the membranes or intact membranes.Study Design:Amniocentesis was performed in 54 singleton pregnancies between 22+0 and 34+2 gestational weeks with suspected intra-amniotic infection. AF-MMP-8 was analysed by immunoassay and AF-cathelicidin by commercial ELISA. Standard biochemical methods, molecular microbiology and culture techniques were used.Results:MIAC was present in 18 (33%) women. The cutoff value for the diagnosis of MIAC was 41.5 ng ml−1 for AF-MMP-8, and 11.6 ng ml−1 for AF-cathelicidin. With these cutoff values AF-MMP-8 had a sensitivity of 100%, specificity of 69%, positive predictive value of 62% and negative predictive value of 100% for MIAC. The corresponding values for AF-cathelicidin were 89, 81, 70 and 94%.Conclusion:The performance of AF-cathelicidin in the prediction of MIAC is comparable to AF-MMP-8.

Outcome of children with ESBL-E. coli acute pyelonephritis treated with cephalosporins

BACKGROUND Some reports have demonstrated surprising efficacy of cephalosporins in acute pyelonephritis (APN) caused by extended-spectrum beta-lactamase (ESBL)-producing bacteria. METHODS We analyzed clinical and microbiological data of pediatric ESBL-APN patients treated empirically with cephalosporins. APN was defined as a combination of fever, pyuria >50 × 10*6/l, bacteriuria, abnormal C-reactive protein (CRP) and no signs of other focus of infection. For a subgroup of children with no co-morbidities, we selected age- and gender-matched controls with APN caused by a non-ESBL Escherichia coli to compare outcomes. RESULTS The study group consisted of 34 children with ESBL-APN (13 boys and 21 girls, median age 1.0 years, range 0.1-9.0 years). The majority of children (88%, 30/34) recovered clinically on the empiric suboptimal antibiotic therapy, being afebrile at ≤48 hours of treatment. Microbiological recovery was documented in seven patients while on therapy with suboptimal antibiotics (64%, 7/11). CRP kinetics, duration of hospitalization, clinical recovery and recurrence rates were similar in children with no co-morbidities in ESBL-APN (n=27) and non-ESBL-APN (n=27) groups. CONCLUSIONS Most children with ESBL-APN recovered on empiric therapy with cephalosporins. Clinical recovery, duration of hospitalization and recurrence rates were similar in ESBL- and non-ESBL-APN groups of children.