Contributions to nephrology
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Stroke is a leading cause of mortality and morbidity worldwide. Traditional cardiovascular risk factors - hypertension, diabetes and dyslipidemia - are related to the incidence of stroke. Chronic kidney disease has also been recognized to be a major public health problem as a cardiovascular risk factor. ⋯ Chronic kidney disease may also be associated with an increase in nontraditional risk factors such as hyperhomocysteinemia, inflammation, asymmetric dimethylarginine, oxidative stress, and anemia, and thrombogenic factors such as left ventricular hypertrophy, endothelial dysfunction, and arterial stiffness. Herein, we review the results of meta-analyses of published cohort studies for a better understanding of the precise nature of the relationship between chronic kidney disease and stroke, important to both the clinical and public health fields. Further studies are warranted to determine whether interventions to prevent the progression of kidney impairment are effective at reducing the risk of stroke.
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Chronic kidney disease and atrial fibrillation (AF) commonly coexist, and data suggest that renal patients have AF rates in excess of double that encountered in the general population. These patients are at increased risk of stroke, regardless of the presence or absence of AF. Furthermore, a lower GFR causes increased thromboembolic risk in patients with AF - independent of other risk factors. ⋯ The new oral anticoagulants have relatively little data in patients with severe renal impairment, and all have an element of renal excretion. There is a need for large randomised control trials in patients with renal insufficiency and on haemodialysis to provide a bank of high-quality scientific data on which clinicians can base their management decisions. Until then, we must adopt a pragmatic approach which involves careful consideration of the relative risk of stroke and bleeding in each individual patient.
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Various drugs have been used for the treatment of focal segmental glomerular sclerosis (FSGS) or minimal change disease (idiopathic nephrotic syndrome, INS) including methylprednisolone pulses, alkylating agents and calcineurin inhibitors, often without a strong rationale. For some drugs the rationale has been recently provided by the identification of mechanisms regulating proteinuria. The characterization of molecules acting as permeability factors, including hemopexin, soluble urokinase receptor and cardiotrophin-like cytokine-1, supports plasma exchange in severe cases of INS, particularly in patients at high risk of recurrence of FSGS after transplantation. ⋯ Using saquinavir associated with small doses of calcineurin inhibitors, we treated a small series of very difficult cases of INS with insufficient response to steroid therapy and multiple immunosuppressive drugs. Saquinavir allowed a significant reduction of steroid cumulative doses and disappearance of features of steroid toxicity. In conclusion, recent reports have allowed a new insight into the pathogenetical mechanism regulating proteinuria in INS, offering new targets for treating severe cases.
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The type II sodium-dependent Pi (NaPi) cotransporters (NaPi-IIa, NaPi-IIb and NaPi-IIc) contribute to renal and intestinal Pi absorption. 1,25-Dihydroxyvitamin D [1,25(OH)2D3] is an important factor for NaPi-II transporters in the small intestine and kidney. In a previous study, low levels of 1,25(OH)2D3 appeared to suppress the expression of renal NaPi cotransporters. We identified a functional vitamin D receptor-responsive element in the human NaPi-IIa and NaPi-IIc genes in renal epithelial cells. ⋯ Klotho functions as a co-receptor for FGF23 and is increased by 1,25(OH)2D3. Klotho induces phosphaturia by inhibiting the renal NaPi-IIa transporter. In this review, we discuss the roles of 1,25(OH)2D3/VDR in the regulation of renal type II NaPi cotransporters in the kidney and small intestine.
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Acute kidney injury (AKI) is a common but complex clinical syndrome with multiple etiologies. These etiologies target different sites and pathways within the kidney. Novel biomarkers of 'kidney damage' (which can be tubular or glomerular) can be used to diagnose AKI, even in the absence of an increase in serum creatinine or oliguria. ⋯ The presence of underlying CKD or of sepsis poses additional challenges in differential diagnosis, since these conditions alter both baseline biomarker excretion and biomarker performance. We recommend that biomarkers be validated within the clinical context in which they are to be used. Within that context, combinations of biomarkers may, in the future, allow differentiation of the site, mechanism and phase of injury.