Risk of acute kidney injury in patients with severe aortic valve stenosis undergoing transcatheter valve replacement

BACKGROUND: Transcatheter aortic valve implantation (TAVI) for high-risk and inoperable patients with severe aortic stenosis is an emerging procedure in cardiovascular medicine. Little is known of the impact of TAVI on renal function. METHODS: We analysed retrospectively renal baseline characteristics and outcome in 58 patients including 2 patients on chronic haemodialysis undergoing TAVI at our institution. Acute kidney injury (AKI) was defined according to the RIFLE classification. RESULTS: Fifty-eight patients with severe symptomatic aortic stenosis not considered suitable for conventional surgical valve replacement with a mean age of 83 +/- 5 years underwent TAVI. Two patients died during transfemoral valve implantation and two patients in the first month after TAVI resulting in a 30-day mortality of 6.9%. Vascular access was transfemoral in 46 patients and transapical in 12. Estimated glomerular filtration rate (eGFR) increased in 30 patients (56%). Fifteen patients (28%) developed AKI, of which four patients had to be dialyzed temporarily and one remained on chronic renal replacement therapy. Risk factors for AKI comprised, among others, transapical access, number of blood transfusions, postinterventional thrombocytopaenia and severe inflammatory response syndrome (SIRS). CONCLUSIONS: TAVI is feasible in patients with a high burden of comorbidities and in patients with pre-existing end-stage renal disease who would be otherwise not considered as candidates for conventional aortic valve replacement. Although GFR improved in more than half of the patients, this benefit was associated with a risk of postinterventional AKI. Future investigations should define preventive measures of peri-procedural kidney injury.

Comparison of two non-bronchoscopic methods for evaluating inflammation in patients with acute hypoxaemic respiratory failure

INTRODUCTION: The simple bedside method for sampling undiluted distal pulmonary edema fluid through a normal suction catheter (s-Cath) has been experimentally and clinically validated. However, there are no data comparing non-bronchoscopic bronchoalveolar lavage (mini-BAL) and s-Cath for assessing lung inflammation in acute hypoxaemic respiratory failure. We designed a prospective study in two groups of patients, those with acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) and those with acute cardiogenic lung edema (ACLE), designed to investigate the clinical feasibility of these techniques and to evaluate inflammation in both groups using undiluted sampling obtained by s-Cath. To test the interchangeability of the two methods in the same patient for studying the inflammation response, we further compared mini-BAL and s-Cath for agreement of protein concentration and percentage of polymorphonuclear cells (PMNs). METHODS: Mini-BAL and s-Cath sampling was assessed in 30 mechanically ventilated patients, 21 with ALI/ARDS and 9 with ACLE. To analyse agreement between the two sampling techniques, we considered only simultaneously collected mini-BAL and s-Cath paired samples. The protein concentration and polymorphonuclear cell (PMN) count comparisons were performed using undiluted sampling. Bland-Altman plots were used for assessing the mean bias and the limits of agreement between the two sampling techniques; comparison between groups was performed by using the non-parametric Mann-Whitney-U test; continuous variables were compared by using the Student t-test, Wilcoxon signed rank test, analysis of variance or Student-Newman-Keuls test; and categorical variables were compared by using chi-square analysis or Fisher exact test. RESULTS: Using protein content and PMN percentage as parameters, we identified substantial variations between the two sampling techniques. When the protein concentration in the lung was high, the s-Cath was a more sensitive method; by contrast, as inflammation increased, both methods provided similar estimates of neutrophil percentages in the lung. The patients with ACLE showed an increased PMN count, suggesting that hydrostatic lung edema can be associated with a concomitant inflammatory process. CONCLUSIONS: There are significant differences between the s-Cath and mini-BAL sampling techniques, indicating that these procedures cannot be used interchangeably for studying the lung inflammatory response in patients with acute hypoxaemic lung injury.

Drug-induced acute liver injury mimicking autoimmune hepatitis after intake of dietary supplements containing glucosamine and chondroitin sulfate

INTRODUCTION Herbal and dietary supplements are widely used as measures to improve and preserve health and well-being. Among the bestselling preparations are dietary supplement containing glucosamine and chondroitine sulfate taken to improve symptoms of osteoarthritis. METHODS AND RESULTS We here present a case of a male patient with biopsy-proven acute and severe autoimmune hepatitis subsequent to intake of a preparation containing glucosamine and chondroitine sulfate. Response to steroids was favorable and resulted in complete remission of the patient. Diagnostic work-up of the case revealed no other possible cause of liver injury, and causality assessment using the Roussel Uclaf Causality Assessment Method (RUCAM) resulted in a possible causal relationship between intake of glucosamine and chondroitine sulfate and the adverse hepatic reaction. CONCLUSION The present case recalls that products containing glucosamine and chondroitine sulfate can occasionally cause acute liver injury mimicking autoimmune hepatitis, and reminds of the potential dangers of compounds with poor efficacy and ill-defined safety records.

THE ROLE OF A2B ADENOSINE RECEPTOR SIGNALING IN ADENOSINE DEPENDENT LUNG DISEASE

Chronic lung diseases and acute lung injuries are two distinctive pulmonary disorders that result in significant morbidity and mortality. Adenosine is a signaling nucleoside generated in response to injury and can serve both protective and destructive functions in tissues and cells through interaction with four G-protein coupled adenosine receptors: A1R, A2AR, A2BR, and A3R. However, the relationship between these factors is poorly understood. Recent findings suggest the A2BR has been implicated in the regulation of both chronic lung disease and acute lung injury. The work presented in this dissertation utilized the adenosine deaminase-deficient mouse model and the bleomycin-induced pulmonary injury model to determine the distinctive roles of the A2BR at different stages of the disease. Results demonstrate that the A2BR plays a protective role in attenuating vascular leakage in acute lung injuries and a detrimental role at chronic stages of the disease. In addition, tissues from patients with chronic obstructive pulmonary disease and idiopathic pulmonary fibrosis were utilized to examine adenosine metabolism and signaling in chronic lung diseases. Results demonstrate that components of adenosine metabolism and signaling are altered in a manner that promotes adenosine production and signaling in the lungs of these patients. Furthermore, this study provides the first evidence that A2BR signaling can promote the production of inflammatory and fibrotic mediators in patients with these disorders. Taken together, these findings suggest that the A2BR may have a bi-phasic effect at different stages of lung disease. It is protective in acute injury, whereas pro-inflammatory and pro-fibrotic at the chronic stage. Patients with acute lung injury or chronic lung disease may both benefit from adenosine and A2BR-based therapeutics.

Pre-treatment with sevoflurane attenuates direct lung injury

Background: Sevoflurane exerts effects on pulmonary cells that could protect against lung injury. We evaluated the potential of pretreatment with sevoflurane to attenuate lipopolysaccharide (LPS)-induced lung injury. Methods: LPS was administered intratracheally in Wistar rats to induce lung injury. Sevoflurane was administered for 30 min at 0.25, 0.5 or 1.0 MAC 15 min before LPS or for 30min at 0.5 MAC 24 hours before LPS. After initial analysis of bronchoalveolar lavage fluid (BALF) cells and total protein, the group of 0.5 MAC 15min before LPS was further analyzed for surfactant aggregates subfractions, plasma malondialdehyde levels and lung histology. Results: LPS instillation resulted in neutrophils sequestration in the lungs, loss of alveolar macrophages, increased BALF total protein and decreased large surfactant aggregates. Only inhalation of sevoflurane for 30min at 0.5 MAC 15min before LPS installation effectively reduced neutrophil accumulation, preserved alveolar epithelial cells and reduced total protein content in BALF. This regimen also reduced plasma malondialdehyde levels and increased large surfactant aggregates, despite the application of mechanical ventilation. This effect was preserved after LPS instillation and the favorable composition of surfactant was maintained. Conclusions: Pretreatment with sevoflurane effectively attenuates direct severe lung injury, possibly by inhibition of neutrophil accumulation and alteration of the surfactant composition.

Plasma and urine neutrophil gelatinase-associated lipocalin (NGAL) in dogs with acute kidney injury or chronic kidney disease.

BACKGROUND Neutrophil gelatinase-associated lipocalin (NGAL) is a protein that is used in human medicine as a real-time indicator of acute kidney injury (AKI). HYPOTHESIS Dogs with AKI have significantly higher plasma NGAL concentration and urine NGAL-to-creatinine ratio (UNCR) compared with healthy dogs and dogs with chronic kidney disease (CKD). ANIMALS 18 healthy control dogs, 17 dogs with CKD, and 48 dogs with AKI. METHODS Over a period of 1 year, all dogs with renal azotemia were prospectively included. Urine and plasma samples were collected during the first 24 hours after presentation or after development of renal azotemia. Plasma and urine NGAL concentrations were measured with a commercially available canine NGAL Elisa Kit (Bioporto® Diagnostic) and UNCR was calculated. A single-injection plasma inulin clearance was performed in the healthy dogs. RESULTS Median (range) NGAL plasma concentration in healthy dogs, dogs with CKD, and AKI were 10.7 ng/mL (2.5-21.2), 22.0 ng/mL (7.7-62.3), and 48.3 ng/mL (5.7-469.0), respectively. UNCR was 2 × 10(-8) (0-46), 1,424 × 10(-8) (385-18,347), and 2,366 × 10(-8) (36-994,669), respectively. Dogs with renal azotemia had significantly higher NGAL concentrations and UNCR than did healthy dogs (P < .0001 for both). Plasma NGAL concentration was significantly higher in dogs with AKI compared with dogs with CKD (P = .027). CONCLUSIONS AND CLINICAL IMPORTANCE Plasma NGAL could be helpful to differentiate AKI from CKD in dogs with renal azotemia.

A novel clinical scoring system for outcome prediction in dogs with acute kidney injury managed by hemodialysis.

BACKGROUND No reliable tool to predict outcome of acute kidney injury (AKI) exists. HYPOTHESIS A statistically derived scoring system can accurately predict outcome in dogs with AKI managed with hemodialysis. ANIMALS One hundred and eighty-two client-owned dogs with AKI. METHODS Logistic regression analyses were performed initially on clinical variables available on the 1st day of hospitalization for relevance to outcome. Variables with P< or = .1 were considered for further analyses. Continuous variables outside the reference range were divided into quartiles to yield quartile-specific odds ratios (ORs) for survival. Models were developed by incorporating weighting factors assigned to each quartile based on the OR, using either the integer value of the OR (Model A) or the exact OR (Models B or C, when the etiology was known). A predictive score for each model was calculated for each dog by summing all weighting factors. In Model D, actual values for continuous variables were used in a logistic regression model. Receiver-operating curve analyses were performed to assess sensitivities, specificities, and optimal cutoff points for all models. RESULTS Higher scores were associated with decreased probability of survival (P < .001). Models A, B, C, and D correctly classified outcomes in 81, 83, 87, and 76% of cases, respectively, and optimal sensitivities/specificities were 77/85, 81/85, 83/90 and 92/61%, respectively. CONCLUSIONS AND CLINICAL RELEVANCE The models allowed outcome prediction that corresponded with actual outcome in our cohort. However, each model should be validated further in independent cohorts. The models may also be useful to assess AKI severity.

Glomerular filtration rate, urine production, and fractional clearance of electrolytes in acute kidney injury in dogs and their association with survival.

BACKGROUND Acute kidney injury (AKI) is common in dogs. Few studies have assessed sequential changes in indices of kidney function in dogs with naturally occurring AKI. OBJECTIVE To document sequential changes of conventional indices of renal function, to better define the course of AKI, and to identify a candidate marker for recovery. ANIMALS Ten dogs with AKI. METHODS Dogs were prospectively enrolled and divided into surviving and nonsurviving dogs. Urine production was measured with a closed system for 7 days. One and 24-hour urinary clearances were performed daily to estimate solute excretion and glomerular filtration rate (GFR). Solute excretion was calculated as an excretion ratio (ER) and fractional clearance (FC) based on both the 1- and 24-hour urine collections. RESULTS Four dogs survived and 6 died. At presentation, GFR was not significantly different between the outcome groups, but significantly (P = .03) increased over time in the surviving, but not in the nonsurviving dogs. Fractional clearance of Na decreased significantly over time (20.2-9.4%, P < .0001) in the surviving, but not in the nonsurviving dogs. The ER and FC of solutes were highly correlated (r, 0.70-0.95). CONCLUSION AND CLINICAL IMPACT Excretion ratio might be used in the clinical setting as a surrogate marker to follow trends in solute excretion. Increased GFR, urine production, and decreased FC of Na were markers of renal recovery. The FC of Na is a simple, noninvasive, and cost-effective method that can be used to evaluate recovery of renal function.

Alveolar derecruitment and collapse induration as crucial mechanisms in lung injury and fibrosis.

Idiopathic pulmonary fibrosis (IPF) and bleomycin-induced pulmonary fibrosis are associated with surfactant system dysfunction, alveolar collapse (derecruitment), and collapse induration (irreversible collapse). These events play undefined roles in the loss of lung function. The purpose of this study was to quantify how surfactant inactivation, alveolar collapse, and collapse induration lead to degradation of lung function. Design-based stereology and invasive pulmonary function tests were performed 1, 3, 7, and 14 days after intratracheal bleomycin-instillation in rats. The number and size of open alveoli was correlated to mechanical properties. Active surfactant subtypes declined by Day 1, associated with a progressive alveolar derecruitment and a decrease in compliance. Alveolar epithelial damage was more pronounced in closed alveoli compared with ventilated alveoli. Collapse induration occurred on Day 7 and Day 14 as indicated by collapsed alveoli overgrown by a hyperplastic alveolar epithelium. This pathophysiology was also observed for the first time in human IPF lung explants. Before the onset of collapse induration, distal airspaces were easily recruited, and lung elastance could be kept low after recruitment by positive end-expiratory pressure (PEEP). At later time points, the recruitable fraction of the lung was reduced by collapse induration, causing elastance to be elevated at high levels of PEEP. Surfactant inactivation leading to alveolar collapse and subsequent collapse induration might be the primary pathway for the loss of alveoli in this animal model. Loss of alveoli is highly correlated with the degradation of lung function. Our ultrastructural observations suggest that collapse induration is important in human IPF.

Acute kidney injury in three dogs after ingestion of a descaling agent containing maleic acid

Maleic acid (MA) is a common component of descaling products and is widely used in daily life. Accidental ingestion in relevant amounts does not play a major role in human beings; however, it seems to be highly toxic for dogs. It has been commonly used experimentally to induce Fanconi syndrome in dogs or small rodents. Two dogs were presented for acute kidney injury (AKI) after accidental ingestion of a descaling agent containing MA at an estimated amount of 70 mg/kg each. The third dog involved was euthanased by the referring veterinarian, and postmortem pathological analysis revealed severe acute tubular necrosis consistent with toxic nephropathy. The other dogs received symptomatic therapy for AKI including treatment with haemodialysis and showed complete normalisation of serum creatinine at a follow-up after five months. Renal damage can be very severe, but seems to be at least partially reversible and an attempt to treatment is warranted.

Mechanisms of apoptosis in bleomycin-induced lung injury: Implications for pulmonary fibrosis

Chronic inflammation leading to pulmonary fibrosis develops in response to environmental pollutants, radiotherapy, or certain cancer chemotherapeutic agents. Studies have shown that several cell types accumulate during the inflammatory process, but little information is known about what actually triggers and stimulates persistent inflammation culminating in fibrosis. As a first step in defining the events that precipitate inflammation in the lung, the biological mechanism(s) mediating apoptosis and cellular targets must be identified. The purpose of this study was to determine the molecular mechanism(s) of bleomycin-induced apoptosis in the lung using mice deficient in genes that we hypothesized to play a key role in apoptosis. Intratracheal administration of bleomycin led to caspase-mediated DNA fragmentation characteristic of apoptosis. The effects of bleomycin were associated with translocation of p53 from the cytosol to the nucleus only in alveolar macrophages that had been exposed to the drug in vivo, suggesting that the lung microenvironment regulated p53 activation. Experiments with a thiol antioxidant (N-acetylcysteine) in vivo and nitric oxide donors in vitro confirmed that reactive oxygen species were required for p53 activation. A specific role for NO was demonstrated in experiments with iNOS−/− macrophages, which failed to demonstrate nuclear p53 localization after in vivo bleomycin exposure. Strikingly, rates of bleomycin-induced apoptosis were at least two-fold higher in iNOS−/− and p53−/− C57BL/6 mice compared to wild-type controls. Laser Scanning Cytometry (LSC) analysis revealed that bleomycin exposure resulted in a 2-fold induction in Fas and FasL expression in wild-type mice but not iNOS−/− or p53−/− mice. Experiments using gld mice confirmed that the Fas/FasL pathway was the primary mechanism of bleomycin-induced apoptosis in the lung. LSC-mediated analysis indicated that bleomycin exposure resulted in a 2-fold induction in Bax expression in iNOS−/− and P53−/− mice but not wild-type mice. Furthermore, LSC analysis revealed that bleomycin exposure induced a 3-fold increase in thrombospondin expression in wild-type mice. However, thrombospondin was not expressed in either the iNOS−/− or p53−/− mice, implicating a thrombospondin-mediated apoptotic cell clearance mechanism in the lung. Together, these results demonstrate that iNOS and p53 positively regulate apoptosis via the Fas/FasL pathway and mediate a novel apoptosis-suppressing pathway in the lung. ^

The genetic contribution of the major histocompatibility complex to bleomycin-induced lung injury

Pulmonary fibrosis (PF) is the result of a variety of environmental and cancer treatment related insults and is characterized by excessive deposition of collagen. Gas exchange in the alveoli is impaired as the normal lung becomes dense and collapsed leading to a loss of lung volume. It is now accepted that lung injury and fibrosis are in part genetically regulated. ^ Bleomycin is a chemotherapeutic agent used for testicular cancer and lymphomas that induces significant pulmonary toxicity. We delivered bleomycin to mice subcutaneously via a miniosmotic pump in order to elicit lung injury (LI) and quantified the %LI morphometrically using video imaging software. We previously identified a quantitative trait loci, Blmpf-1(LOD=17.4), in the Major Histocompatibility Complex (MHC), but the exact genetic components involved have remained unknown. ^ In the current studies, Blmpf-1 was narrowed to an interval spanning 31.9-32.9Mb on Chromosome 17 using MHC Congenic mice. This region includes the MHC Class II and III genes, and is flanked by the TNF-alpha super locus and MHC Class I genes. Knockout mice of MHC Class I genes (B2mko), MHC Class II genes (Cl2ko), and TNF-alpha (TNF-/-) and its receptors (p55-/-, p75-/-, and p55/p75-/-) were treated with bleomycin in order to ascertain the role of these genes in the pathogenesis of lung injury. ^ Cl2ko mice had significantly better survival and %LI when compared to treated background BL/6 (B6, P<.05). In contrast, B2mko showed no differences in survival or %LI compared to B6. This suggests that the MHC Class II locus contains susceptibility genes for bleomycin-induced lung injury. ^ TNF-alpha, a Class III gene, was examined and it was found that TNF-/- and p55-/- mice had higher %LI and lower survival when compared to B6 (P<.05). In contrast, p75-/- mice had significantly reduced %LI when compared to TNF-/-, p55-/-, and B6 mice as well as higher survival (P<.01). These data contradict the current paradigm that TNF-alpha is a profibrotic mediator of lung injury and suggest a novel and distinct role for the p55 and p75 receptors in mediating lung injury. ^