Beta-lactam-associated hypokalemia.

The aim of this narrative review was to discuss the literature on ß-lactam antibiotic-associated hypokalemia, a potentially life-threatening electrolyte disorder. The PubMed, Web of Science, Cochrane Library, and Scopus databases were searched for articles published between 1965 and 2023, using the following terms: 'hypokalemia' OR 'potassium loss' OR 'potassium deficiency' AND 'beta-lactams' OR 'penicillin' OR 'penicillin G' OR 'cephalosporins' OR 'ceftazidime' OR 'ceftriaxone' OR 'flucloxacillin' OR 'carbapenems' OR 'meropenem' OR 'imipenem' OR 'cefiderocol' OR 'azlocillin' OR 'ticarcillin'. Additional search terms were 'hypokalemia' AND 'epidemiology' AND 'ICU' OR 'intensive care unit' OR 'ER' OR 'emergency department' OR 'ambulatory' OR 'old' OR 'ageing population', and experimental (animal-based) studies were excluded. A total of eight studies were selected and discussed, in addition to nine case reports and case series. Both older and currently used ß-lactam antibiotics (e.g., ticarcillin and flucloxacillin, respectively) have been associated with therapy-related hypokalemia. The incidence of ß-lactam antibiotic-associated hypokalemia may be as high as 40%, thus, the issue of ß-lactam-associated hypokalemia remains clinically relevant. Although other causes of hypokalemia are likely to be diagnosed more frequently (e.g., due to diuretic therapy or diarrhea), the possibility of ß-lactam-induced renal potassium loss should always be considered in individuals with so-called 'unexplained hypokalemia'.

Clinically Evident Cardiopulmonary Congestion Does Not Significantly Impact the Prognosis of Patients With Septic Acute Kidney Injury.

Background: Acute kidney injury (AKI) is a common issue among in-hospital patients, with high mortality rates. Sepsis is a primary cause of AKI, particularly in the intensive care unit. Patients with septic AKI often experience cardiovascular congestion, leading to the formal classification of cardiorenal syndrome type 5. The study aimed to evaluate the prognosis of septic AKI patients with and without clinical evidence of cardiovascular congestion. Methods: This was a retrospective observational study. AKI patients were identified using the in-hospital AKI alert system. Sepsis was diagnosed based on laboratory, clinical, and hemodynamic characteristics, with additional consideration of the quickSOFA score. Cardiovascular congestion was diagnosed by assessing clinical (edema), radiographic (pulmonary congestion), echocardiographic (e.g., wall motion abnormalities), and laboratory variables (e.g., N-terminal pro-B-type natriuretic peptide). Endpoints included in-hospital survival, the need for kidney replacement therapy (KRT), and recovery of kidney function (ROKF). Results: In total, 102 patients were included, and cardiopulmonary congestion was diagnosed in 78.4%. Individuals with congestion did not differ from patients without congestion in any of the pre-defined endpoints. Conclusions: It is justified not to consider clinically apparent cardiovascular congestion in septic AKI patients as a risk factor for death per se. Rather, especially in the case of sepsis, clinically apparent positive fluid balance does not seem to be a disadvantage in terms of survival, KRT, and ROKF.

Electronic Acute Kidney Injury Alert at the Brandenburg Medical School: Implementation and Follow-Up.

INTRODUCTION: Acute kidney injury (AKI) substantially worsens the prognosis of hospitalized patients worldwide. In order to optimize early AKI recognition and therapeutic intervention, AKI alert systems have been implemented and evaluated in the past. Herein, we aimed to analyze outcome variables of AKI patients under the conditions of a de novo-established AKI alert system at the Brandenburg Hospital of the Brandenburg Medical School. METHODS: Automated e-mail messages were generated and sent to the nephrologist with responsibility based on an electronic algorithm. The message was exclusively generated if one of the two first KDIGO criteria was fulfilled. During period 1, all alerts were ignored. During the second period, every alert was followed up, coupled with therapeutic management of respective individuals according to an AKI care bundle. Endpoints were in-hospital death, need for dialysis, and renal recovery. RESULTS: In periods 1 and 2, 200 and 112 patients were included. In period 1, 150 out of 200 AKI alerts were identified as correct (75%); in the second period, 93 out of 112 AKI alerts were accepted as correct (83%) (p = 0.16). Kidney replacement therapy was initiated in 21 (14%) of all period 1 patients and in 32 (34.4%) of the period 2 patients (p = 0.017). In-hospital mortality of affected patients was 24 (16%) in period 1 and 21 (22.5%) in period 2 (p = 0.4). Restoration of kidney function was 69 (46%) in period 1 and 45 (48.3%) in period 2 (p = 0.71). CONCLUSIONS: We finally conclude that an AKI alert system, as implemented and followed-up in our study, did not significantly improve clinically relevant endpoints in AKI patients. Potential weaknesses were the lack of documentation of the time between receiving the alert and patient contact, and physicians in responsibility were not particularly informed about the alert system.

Assessing kidney development and disease using kidney organoids and CRISPR engineering.

The differentiation of human pluripotent stem cells (hPSCs) towards organoids is one of the biggest scientific advances in regenerative medicine. Kidney organoids have not only laid the groundwork for various organ-like tissue systems but also provided insights into kidney embryonic development. Thus, several protocols for the differentiation of renal progenitors or mature cell types have been established. Insights into the interplay of developmental pathways in nephrogenesis and determination of different cell fates have enabled the in vitro recapitulation of nephrogenesis. Here we first provide an overview of kidney morphogenesis and patterning in the mouse model in order to dissect signalling pathways that are key to define culture conditions sustaining renal differentiation from hPSCs. Secondly, we also highlight how genome editing approaches have provided insights on the specific role of different genes and molecular pathways during renal differentiation from hPSCs. Based on this knowledge we further review how CRISPR/Cas9 technology has enabled the recapitulation and correction of cellular phenotypes associated with human renal disease. Last, we also revise how the field has positively benefited from emerging technologies as single cell RNA sequencing and discuss current limitations on kidney organoid technology that will take advantage from bioengineering solutions to help standardizing the use of this model systems to study kidney development and disease.

Dissecting nephron morphogenesis using kidney organoids from human pluripotent stem cells.

During kidney development the emergence of complex multicellular shapes such as the nephron (the functional unit of the kidney) rely on spatiotemporally coordinated developmental programs. These involve gene regulatory networks, signaling pathways and mechanical forces, that work in concert to shape and form the nephron(s). The generation of kidney organoids from human pluripotent stem cells now represent an unprecedented experimental set up to study these processes. Here we discuss the potential applications of kidney organoids to advance our knowledge of how mechanical forces and cell fate specification spatiotemporally interact to orchestrate nephron patterning and morphogenesis in humans. Progress in innovative techniques for quantifying and perturbing these processes in a controlled manner will be crucial. A mechanistic understanding of the multicellular dynamic processes occurring during nephrogenesis will pave the way to unveil new mechanisms of human kidney disease.

Macrophage migration inhibitory factor is regulated by HIF-1α and cAMP and promotes renal cyst cell proliferation in a macrophage-independent manner.

Progressive cyst growth leads to decline of renal function in polycystic kidney disease. Macrophage migration inhibitory factor (MIF) was found to be upregulated in cyst-lining cells in a mouse model of polycystic kidney disease and to promote cyst growth. In addition, MIF can be secreted by tubular cells and may contribute to cyst growth in an autocrine manner. However, the underlying mechanisms leading to induction of MIF in cyst-lining cells remained elusive. Here, we demonstrate that hypoxia-inducible transcription factor (HIF) 1α upregulates MIF in cyst-lining cells in a tubule-specific PKD1 knockout mouse. Pharmacological stabilization of HIF-1α resulted in significant increase of MIF in cyst epithelial cells whereas tubule-specific knockout of HIF-1α prevented MIF upregulation. Identical regulation could be found for ABCA1, which has been shown to act as a transport protein for MIF. Furthermore, we show that MIF and ABCA1 are direct target genes of HIF-1α in human primary tubular cells. Next to HIF-1α and hypoxia, we found MIF being additionally regulated by cAMP which is a strong promotor of cyst growth. In line with these findings, HIF-1α- and cAMP-dependent in vitro cyst growth could be decreased by the MIF-inhibitor ISO-1 which resulted in reduced cyst cell proliferation. In conclusion, HIF-1α and cAMP regulate MIF in primary tubular cells and cyst-lining epithelial cells, and MIF promotes cyst growth in the absence of macrophages. In line with these findings, the MIF inhibitor ISO-1 attenuates HIF-1α- and cAMP-dependent in vitro cyst enlargement. KEY MESSAGES: • MIF is upregulated in cyst-lining cells in a polycystic kidney disease mouse model. • MIF upregulation is mediated by hypoxia-inducible transcription factor (HIF) 1α. • ABCA1, transport protein for MIF, is also regulated by HIF-1α in vitro and in vivo. • MIF is additionally regulated by cAMP, a strong promotor of cyst growth. • MIF-inhibitor ISO-1 reduces HIF-1α- and cAMP-dependent cyst growth.

Infection and Predictors of Outcome of Cirrhotic Patients after Emergency Care Hospital Admission.

INTRODUCTION AND AIMS: We aimed to explore the impact of infection diagnosed upon admission and of other clinical baseline parameters on mortality of cirrhotic patients with emergency admissions. MATERIAL AND METHODS: We performed a prospective observational monocentric study in a tertiary care center. The association of clinical parameters and established scoring systems with short-term mortality up to 90 days was assessed by univariate and multivariable Cox regression analysis. Akaike's Information Criterion (AIC) was used for automated variable selection. Statistical interaction effects with infection were also taken into account. RESULTS: 218 patients were included. 71.2% were male, mean age was 61.1 ± 10.5 years. Mean MELD score was 16.2 ± 6.5, CLIF-consortium Acute on Chronic Liver Failure-score was 34 ± 11. At 28, 90 and 365 days, 9.6%, 26.0% and 40.6% of patients had died, respectively. In multivariable analysis, respiratory organ failure [Hazard Ratio (HR) = 0.15], albumin substitution (HR = 2.48), non-HCC-malignancy (HR = 4.93), CLIF-C-ACLF (HR = 1.10), HCC (HR = 3.70) and first episode of ascites (HR = 0.11) were significantly associated with 90-day mortality. Patients with infection had a significantly higher 90-day mortality (36.3 vs. 20.1%, p = 0.007). Cultures were positive in 32 patients with resistance to cephalosporins or quinolones in 10, to ampicillin/sulbactam in 14 and carbapenems in 6 patients. CONCLUSION: Infection is common in cirrhotic ED admissions and increases mortality. The proportion of resistant microorganisms is high. The predictive capacity of established scoring systems in this setting was low to moderate.

Elevated cardiac troponin T in cirrhotic patients with emergency care admissions: Associations with mortality.

BACKGROUND AND AIM: Mortality of cirrhotic patients after emergency care admission is high, and prognostic factors can help in prioritizing patients. The aim of our study was to assess the association between levels of cardiac troponin T (cTnT) and 1-year mortality in patients with liver cirrhosis without known cardiac disease, who were admitted to the emergency department (ED). METHODS: All patients with cirrhosis presented to the ED from October 2009 until August 2015 who had an initial cTnT value measured with the first lab panel were retrospectively analyzed with a follow-up of 365 days. RESULTS: Of a total of 237 cirrhotic ED patients, cTnT measurements were available for 87 (63% men, mean age 58.9 ± 11.0 years, and median Model for End-stage Liver Disease score was 15 [25th-75th percentile: 10-19]). Chronic Liver Failure Consortium acute-on-chronic liver failure (CLIF-C-ACLF) score was 33. Forty-three patients (49%) had cTnT values above the normal range (14 ng/L), of which 19 (22%) had values over 30 ng/L. Two patients were lost to follow-up. In multivariable analysis, both CLIF-C-ACLF (hazard ratio 1.072 per point increase; 95% confidence interval 1.029-1.117; P < 0.001) and cTnT (hazard ratio 1.014 per ng/L increase; 95% confidence interval 1.004-1.024; P = 0.008) emerged as independently associated with mortality. CONCLUSIONS: A large proportion of cirrhotic patients in the ED have elevated levels of cTnT even if there is no evidence of cardiac disease. Elevated cTnT is associated with increased mortality during 1 year after correcting for Model for End-stage Liver Disease and CLIF-C-ACLF scores.

Differentiation of human CD14+ monocytes: an experimental investigation of the optimal culture medium and evidence of a lack of differentiation along the endothelial line.

The aim of this study was to determine the optimal culturing media for human CD14+ monocytes and to evaluate whether these cells are capable of differentiating into vascular endothelial cells. Human monocytes isolated from peripheral blood were cultured for 1, 3, 7, 10 or 14 days in different media containing either 10% fetal bovine serum (FBS), 10% autologous donor serum (Auto), 10% FBS with interleukin-3 and macrophage colony stimulating factor (FBS-WF) or 10% Auto and the same growth factors (AU-WF). The cells were differentiated using endothelial cell conditioning medium (EC). Viability was measured using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, and the cells were characterized by histology, immunohistochemistry and western blot analysis. Monocytes treated with Auto, FBS-WF or AU-WF medium generated a significant higher yield of vital cells after 7 days in culture compared with FBS-only medium (mean difference (MD)=0.318, P=0.01; MD=1.83, P=0.04; or MD=0.271, P=0.01 and MD=0.318, P=0.102). All tested media led to the differentiation of monocytes into macrophages, identified by CD68, especially in the FBS-WF medium (MD=+18.3%; P=0.04). Differentiation into ECs caused a significant decrease in cell viability in all media. Endothelial cell markers, including CD31, CD144, VEGF, VEGF-R2 and CD34, could not be detected. Autologous serum significantly increases the yield of monocyte-derived cells with a higher effectiveness than commonly used FBS-only serum. There is no further benefit in culturing monocytes longer than 7 days. The cultivation of monocytes in the tested media leads preferentially to differentiation into macrophages. Differentiation into endothelial cells did not take place.

Contrast-induced acute kidney injury in cirrhotic patients. A retrospective analysis.

BACKGROUND: The nephrotoxic potential of intravenous iodinated contrast (IC) is controversial. Cirrhotic patients are often submitted to imaging procedures involving IC and small changes in renal function may have detrimental effects. MATERIAL AND METHODS: Retrospective analysis of hospitalized patients with elective imaging by either contrast-enhanced CT or MRI. Contrast induced acute kidney injury (CI-AKI) was diagnosed if there was either an increase of SCr by 25% or by 44 µmol/L or a decrease of estimated glomerular filtration rate by 25% by day 3. RESULTS: Between 2004 and 2012 152 patients (female: 30.3%, age: 60 ± 10.8 years, MELD 13 ± 6) were included in this study of which 84 (55.3%) had received IC and 68 (44,7%), who served as controls, MRI with gadolinium based contrast (non-IC). Baseline parameters were well matched except for age (61.7 vs. 56.9) years in the IC vs. non-IC groups, p = 0.005). 15 patients (17.9%) receiving IC and 4 patients (5.9%) not receiving IC (p = 0.026) reached the composite end-point for CI-AKI. In multivariable regression analysis INR [B = 0.252 (95% CI: 0.108-0.397), p = 0.001]; IC [B = 0.136 (95% CI: 0.023-0.248), p = 0.019] and serum sodium [B = 0.011 (95% CI: 0.001-0.023); p = 0.080] were independently associated with changes of SCr. In conclusion IC may cause renal dysfunction in cirrhotic patients. Patients subjected to imaging using IC should be closely monitored.

Evaluation of T1ρ as a potential MR biomarker for liver cirrhosis: comparison of healthy control subjects and patients with liver cirrhosis.

OBJECTIVES: The purpose of this study was to compare mean liver T1ρ values in patients with liver cirrhosis and healthy control subjects in order to evaluate T1ρ as a potential MR biomarker for liver cirrhosis. MATERIALS AND METHODS: Ten healthy control subjects (mean age 42.7 years; 6 female, 4 male) and 21 patients with clinically diagnosed liver cirrhosis (mean age 56.5 years; 5 female, 16 male) were examined at 1.5 T (Magnetom Avanto, Siemens). T1ρ-weighted images were acquired using a 2D TurboFLASH sequence (TR/TE 3/1.31 ms, FA 8°, FoV 309 × 380 mm, resolution 2 × 2 × 6 mm, acquisition time 15s, slice thickness 6mm) with spin-lock preparation. T1ρ maps were calculated from five breath-hold measurements, performed with different spin-lock times (4, 8, 16, 32 and 48 ms). Mean liver T1ρ values of healthy control subjects and patients with liver cirrhosis were calculated and compared using Student t-test. In addition, a receiver operating characteristic (ROC) curve analysis was performed to evaluate the utility of mean liver T1ρ values for the prediction of liver cirrhosis. RESULTS: Mean liver T1ρ values in patients with liver cirrhosis (57.4 ± 7.4 ms) were significantly higher than those of healthy subjects (47.8 ± 4.2 ms; p=0.0007). According to the ROC analysis at a threshold value of 50.1 ms the sensitivity and specificity of mean liver T1ρ in predicting liver cirrhosis were 90.5% and 90%, respectively. The area under the ROC curve was 0.90. CONCLUSION: Mean liver T1ρ values in patients with liver cirrhosis were significantly higher than those in healthy subjects suggesting a potential role of liver T1ρ as a MR biomarker for liver cirrhosis.

Comparative measurement of CNP and NT-proCNP in human blood samples: a methodological evaluation.

BACKGROUND: C-type natriuretic peptide (CNP) has anti-inflammatory, anti-proliferative, and anti-migratory properties. During the past years, CNP has attained an increasing interest by many research groups, especially in the cardiovascular field. Nevertheless, still no reliable data exist on the difference of CNP concentration between serum and plasma samples. Also, the influence of delayed blood sample proceeding is unknown. The aim of this study was to investigate the difference of CNP and NT-proCNP concentrations between serum and plasma samples. In order to identify potential methodological bias, this study should also validate the stability of CNP and NT-proCNP in full blood samples stored at room temperature. FINDINGS: Triplets (serum, plasma, full blood) of fasting blood samples from 12 healthy male individuals were collected. Analysis of CNP and NT-proCNP concentration was performed immediately following sampling, and after 30 minutes or 2 hours of storage at room temperature. Mean serum concentrations at baseline were 0.997 ± 0.379 ng/ml for CNP and 58.5 ± 28.3 pg/ml for NT-proCNP. Furthermore, NT-proCNP concentration did not change significantly during the allotted time and did not differ between serum, plasma, and full blood samples. At baseline, concentrations of CNP were significantly different between samples containing either sodium-citrate or EDTA as a clotting inhibitor (1.933 ± 0.699 ng/ml vs. 0.991 ± 0.489 ng/ml, p = 0.001). CONCLUSIONS: CNP and NT-proCNP are stable for at least two hours, even when sample processing is delayed or blood probes are stored at room temperature. NT-proCNP assay demonstrated more consistent and reliable data and should therefore be preferred for usage in clinical applications. Nevertheless, as recommended for ANP and BNP, immunoassays for CNP should also be standardized or harmonized in the future.