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With obesity having doubled in the last decade, hypertension is on the rise. In one-third of hypertensive patients the metabolic syndrome is present. This might be one factor for the increasing number of prescriptions for angiotensin receptor blockers and calcium-channel blockers besides a more favorable risk-to-benefit ratio. The aim of the present study was to evaluate a therapeutic drug monitoring (TDM) method for assessment of adherence based on cut-offs in inpatients and to compare it to an established urine drug screening in outpatients. A method for quantification of calcium-channel blockers and angiotensin receptor blockers using high-performance liquid chromatography-tandem mass spectrometric analysis (LC-MS/MS) was developed and validated. The method was applied to serum samples of 32 patients under supervised medication to establish cut-off values for adherence assessment based on dose-related concentrations (DRC, calculated from pharmacokinetic data). Furthermore, corresponding urine and blood samples of 42 outpatients without supervised medication were analysed and the results compared with regard to adherence assessment. All serum concentrations measured for amlodipine (n = 40), lercanidipine (n = 14), candesartan (n = 10), telmisartan (n = 4) and valsartan (n = 10) in inpatients were above the patient specific lower DRC confirming adherence. Of 42 outpatients the identification of analytes in urine as well as the quantification in serum exhibited differing results. According to urinalysis, adherence was demonstrated in only 87.0% of prescriptions, compared to 91.3% for serum analyses. Differences were observed for amlodipine, lercanidipine and candesartan which can be explained by a higher specificity of the serum analysis approach due to pharmacokinetics. The present study confirms that assessing adherence based on serum drug concentrations with individually calculated lower DRCs is more accurate than using qualitative urine analysis. In particular, drugs with low bioavailability, low renal excretion or high metabolism rate such as lercanidipine and candesartan may lead to underestimation of adherence via urine analysis.
Acute kidney injury (AKI) is one of the most important complications in hospitalized patients and its pathomechanisms are not completely elucidated. We hypothesize that signaling via toll-like receptor (TLR)-3, a receptor that is activated upon binding of double-stranded nucleotides, might play a crucial role in the pathogenesis of AKI following ischemia and reperfusion (IR). Male adult C57Bl6 wild-type (wt) mice and TLR-3 knock-out (-/-) mice were subjected to 30 minutes bilateral selective clamping of the renal artery followed by reperfusion for 30 min 2.5h and 23.5 hours or subjected to sham procedures. TLR-3 down-stream signaling was activated already within 3 h of ischemia and reperfusion in post-ischemic kidneys of wt mice lead to impaired blood perfusion followed by a strong pro-inflammatory response with significant neutrophil invasion. In contrast, this effect was absent in TLR-3-/- mice. Moreover, the quick TLR-3 activation resulted in kidney damage that was histomorphologically associated with significantly increased apoptosis and necrosis rates in renal tubules of wt mice. This finding was confirmed by increased kidney injury marker NGAL in wt mice and a better preserved renal perfusion after IR in TLR-3-/- mice than wt mice. Overall, the absence of TLR-3 is associated with lower cumulative kidney damage and maintained renal blood perfusion within the first 24 hours of reperfusion. Thus, we conclude that TLR-3 seems to participate in the pathogenesis of early acute kidney injury.
Hyponatremia is the most common and by far underestimated electrolyte disorder in clinical practice. Especially in elderly patients, treatment of symptomatic hyponatremia is challenging. Herein we describe the case of an octogenarian with recurrent symptomatic hyponatremia due to idiopathic syndrome of inappropriate antidiuretic hormone release (SIADH). Fluid restriction was insufficient to prevent repeated episodes of hyponatremia complicated by falls and coma. After introduction of a low-dose therapy with tolvaptan, serum sodium levels as well as the clinical condition were stable under vaptan therapy, without any relapse for more than six years now. This case demonstrates that long-term tolvaptan treatment for hyponatremia caused by SIADH is safe and well tolerated, even in the elderly.
Paricalcitol is approved for prevention and therapy of secondary hyperparathyroidism (sHPT) in patients with chronic kidney disease (CKD), with only short-term data in clinical routine settings. A 12-month observational study was conducted in Germany and Austria (90 centers, 761 patients) from 2008 to 2013. Laboratory values, demographical, and clinical data were documented in 629 dialysis patients and 119 predialysis patients. In predialysis patients, median intact parathormone (iPTH) was 180.0 pg/mL (n = 105) at the start of the study, 115.7 pg/mL (n = 105) at last documentation, and 151.8 pg/mL (n = 50) at month 12, with 32.4% of the last documented iPTH values in the KDOQI (Kidney Disease Outcomes Quality Initiative) target range. In dialysis patients, median iPTH was 425.5 pg/mL (n = 569) at study start, 262.3 pg/mL (n = 569) at last documentation, and 266.1 pg/mL (n = 318) at month 12, with 36.5% of dialysis patients in the KDOQI target range. Intravenous paricalcitol showed more homogenous iPTH control than oral treatment. Combined analysis of all dialysis patients indicated comparable and stable mean serum calcium and phosphate levels throughout the study. Clinical symptoms, such as itching, bone pain, and fatigue, were improved compared with study entry. The spectrum and frequency of adverse events mirrored the known pattern for patients on dialysis. Paricalcitol is efficacious and has a consistent safety profile in sHPT over 12 months.
Detection of antihypertensive drugs in biological samples is an important tool to assess the adherence of hypertensive patients. Urine and serum/plasma screenings based on qualitative results may lead to misinterpretations regarding drugs with a prolonged detectability. The aim of the present study was to develop a method that can be used for therapeutic drug monitoring (TDM) of antihypertensive drugs with focus on adherence assessment. Therefore, a method for quantification of four diuretics and four β-blockers using high-performance liquid chromatography-mass spectrometric analysis (LC-MS/MS) of combined acidic and basic serum extracts was developed and validated. The method was applied to 40 serum samples from 20 patients in a supervised medication setting (trough and peak serum samples). Literature data on therapeutic concentration ranges, as well as dose-related drug concentrations (calculated from data of pharmacokinetic studies) were used to evaluate adherence assessment criteria. Concentrations were measured for bisoprolol (n = 9 patients), metoprolol (n = 7), nebivolol (n = 1), canrenone (n = 2, metabolite of spironolactone), hydrochlorothiazide (n = 10) and torasemide (n = 8). The measured concentrations were within the therapeutic reference ranges, except for 24% of the samples (mainly β-blockers). In contrast, all measured concentrations were above the lower dose-related concentration (DRC), which appears superior in evaluating adherence. In conclusion, the quantitative analysis of antihypertensive drugs in serum samples and its evaluation on the basis of the individually calculated lower DRC is a promising tool to differentially assess adherence. This method could possibly detect a lack of adherence or other causes of insufficient therapy more reliably than qualitative methods.
Expression of kidney injury molecule-1 (Kim-1) is rapidly upregulated following tubular injury, constituting a biomarker for acute kidney damage. We examined the renal localization of Kim-1 expression in PKD/Mhm (polycystic kidney disease, Mannheim) (cy/+) rats (cy: mutated allel, +: wild type allel), an established model for autosomal dominant polycystic kidney disease, with chronic, mainly proximal tubulointerstitial alterations. For immunohistochemistry or Western blot analysis, kidneys of male adult heterozygously-affected (cy/+) and unaffected (+/+) littermates were perfusion-fixed or directly removed. Kim-1 expression was determined using peroxidase- or fluorescence-linked immunohistochemistry (alone or in combination with markers for tubule segments or differentiation). Compared to (+/+), only in (cy/+) kidneys, a chronic expression of Kim-1 could be detected by Western blot analysis, which was histologically confined to an apical cellular localization in areas of cystically-transformed proximal tubules with varying size and morphology, but not in distal tubular segments. Kim-1 was expressed by cystic epithelia exhibiting varying extents of dedifferentiation, as shown by double labeling with aquaporin-1, vimentin or osteopontin, yielding partial cellular coexpression. In this model, in contrast to other known molecules indicating renal injury and/or repair mechanisms, the chronic renal expression of Kim-1 is strictly confined to proximal cysts. Its exact role in interfering with tubulo-interstitial alterations in polycystic kidney disease warrants future investigations.
Disruption of the renal endothelial integrity is pivotal for the development of a vascular leak, tissue edema and consequently acute kidney injury. Kidney ischemia amplifies endothelial activation and up-regulation of pro-inflammatory mechanisms. After restoring a sufficient blood flow, the kidney is damaged through complex pathomechanisms that are classically referred to as ischemia and reperfusion injury, where the disruption of the inter-endothelial connections seems to be a crucial step in this pathomechanism. Focusing on the molecular cell-cell interaction, the fibrinopeptide Bβ15–42 prevents vascular leakage by stabilizing these inter-endothelial junctions. The peptide associates with vascular endothelial-cadherin, thus preventing early kidney dysfunction by preserving blood perfusion efficacy, edema formation and thus organ dysfunction. We intended to demonstrate the early therapeutic benefit of intravenously administered Bβ15–42 in a mouse model of renal ischemia and reperfusion. After 30 minutes of ischemia, the fibrinopeptide Bβ15–42 was administered intravenously before reperfusion was commenced for 1 and 3 hours. We show that Bβ15–42 alleviates early functional and morphological kidney damage as soon as 1 h and 3 h after ischemia and reperfusion. Mice treated with Bβ15–42 displayed a significantly reduced loss of VE-cadherin, indicating a conserved endothelial barrier leading to less neutrophil infiltration which in turn resulted in significantly reduced structural renal damage. The significant reduction in tissue and serum neutrophil gelatinase-associated lipocalin levels reinforced our findings. Moreover, renal perfusion analysis by color duplex sonography revealed that Bβ15–42 treatment preserved resistive indices and even improved blood velocity. Our data demonstrate the efficacy of early therapeutic intervention using the fibrinopeptide Bβ15–42 in the treatment of acute kidney injury resulting from ischemia and reperfusion. In this context Bβ15–42 may act as a potent renoprotective agent by preserving the endothelial and vascular integrity.
S1P and its receptors have been reported to play important roles in the development of renal fibrosis. Although S1P5 has barely been investigated so far, there are indications that it can influence inflammatory and fibrotic processes. Here, we report the role of S1P5 in renal inflammation and fibrosis. Male S1P5 knockout mice and wild-type mice on a C57BL/6J background were fed with an adenine-rich diet for 7 days or 14 days to induce tubulointerstitial fibrosis. The kidneys of untreated mice served as respective controls. Kidney damage, fibrosis, and inflammation in kidney tissues were analyzed by real-time PCR, Western blot, and histological staining. Renal function was assessed by plasma creatinine ELISA. The S1P5 knockout mice had better renal function and showed less kidney damage, less proinflammatory cytokine release, and less fibrosis after 7 days and 14 days of an adenine-rich diet compared to wild-type mice. S1P5 knockout ameliorates tubular damage and tubulointerstitial fibrosis in a model of adenine-induced nephropathy in mice. Thus, targeting S1P5 might be a promising goal for the pharmacological treatment of kidney diseases.
