An extremely high dose of losartan affords superior renoprotection in the remnant model

An extremely high dose of losartan affords superior renoprotection in the remnant model.BackgroundRats subjected to 5/6 renal ablation (NX) exhibit large renal amounts of angiotensin II (Ang II) and of its main receptor, AT-1R. At previously used doses, AT-1R blockers (ARB) offer only partial renal protection. A possible explanation for this limited effect is that these doses are insufficient to block most of the abnormally expressed AT-1R. We investigated whether extremely high doses of the ARB, losartan (L), offer better protection than conventional doses in the NX model.MethodsThirty days after NX, tail-cuff pressure (TCP), albuminuria (UalbV, mg/day), glomerulosclerosis index (GSI), fractional interstitial area (%INT), and macrophage infiltration (MØ) were evaluated in a separate group (NXpre). The remaining rats were then subdivided among 4 groups: NX+V, receiving vehicle; NX+L50, treated with L, at the “conventional” dose of 50 mg/kg/day; NX+L500, receiving L, 500 mg/kg/day; and NX+HH, receiving hydrochlorothiazide and hydralazine to lower blood pressure to a similar extent as in group L500.ResultsAfter a month of treatment, blood pressure and renal vascular resistance were lowest in group L500. Glomerular pressure was lowered by a similar extent by L50 and L500, while GFR was similar among groups. UalbV, TCP, and renal injury were only partially reduced by L50 120 days after renal ablation. By contrast, L500 arrested renal inflammation and glomerular/interstitial injury at pretreatment levels, and promoted regression of hypertension and UalbV, causing no apparent untoward effects.ConclusionThe renal protection afforded by ARB in NX is dose dependent. Maximal protection may require doses several fold higher than those currently employed

Hipertensão persistente e lesão renal progressiva induzidas por sobrecarga de sal após inibição temporária do óxido nítrico

INTRODUCTION: Administration of the NO inhibitor Nwð-nitro-L-arginine methyl ester (NAME) and a high-salt diet (HS) promotes severe albuminuria and renal injury, which regresses upon discontinuation of treatments. OBJECTIVE: We investigated whether these changes reappear after reinstitution of HS, and whether they are prevented by treatment with the antilymphocyte agent mycophenolate mofetil (MMF) or the AT-1 receptor blocker losartan (L). Adult male Munich-Wistar rats received NAME and HS. A control Group (C) received only HS. After 20 days, rats receiving HS and NAME exhibited severe hypertension and albuminuria. After a 30-day recovery period, hypertension was attenuated and albuminuria had virtually disappeared. MATERIAL AND METHODS: Rats were then distributed among the following groups: HS, receiving HS; NS, receiving a normal salt (NS) diet; HS-MMF, receiving HS and MMF; HS-LOS, receiving HS and L; HS-HDZ, receiving HS and hydralazine (HDZ). Sixty days later, NS rats showed only slight albuminuria and renal damage or inflammation. In contrast, HS rats developed severe hypertension, marked glomerulosclerosis with interstitial expansion and renal infiltration by macrophages and angiotensin II-positive cells. The group treated with losartan had lowered blood pressure and a lack of albuminuria or renal injury. MMF provided similar protection without altering blood pressure, suggesting a nonhemodynamic effect, a hypothesis reinforced by the finding that HDZ lowered blood pressure without preventing renal injury. RESULTS: These results indicate that treatment with HS and NAME predisposes to the development of hypertension and renal injury upon salt overload, characterizing a new model of chronic nephropathy. CONCLUSION: The response to MMF or L, but not HDZ, suggests a key role for inflammatory rather than hemodynamic factors.INTRODUÇÃO: A administração de Nômega-nitro-L-arginina metiléster (NAME), um inibidor da produção de NO, com dieta rica em sal (HS) promove albuminúria e dano renal graves, reversíveis ao interromperem-se os tratamentos. OBJETIVO: Investigamos se tais alterações recrudescem ao reinstituir-se a HS e se são prevenidas pelo micofenolato mofetil (MMF), um agente antilinfócito, ou losartan, um bloqueador do receptor AT-1. MATERIAL E MÉTODOS: Ratos Münich-Wistar machos adultos receberam NAME e HS. Um grupo controle (C) recebeu apenas HS. Após 20 dias, os ratos que receberam HS e NAME exibiam hipertensão e albuminúria graves. Após recuperação de 30 dias, a hipertensão atenuou-se e a albuminúria praticamente desapareceu. Formaram-se então os grupos: HS, recebendo HS; NS, recebendo dieta normal em sal (NS); HS-MMF, recebendo HS e MMF; HS-LOS, recebendo HS e losartan; HS-HDZ, recebendo HS e hidralazina. Após sessenta dias os ratos NS tinham albuminúria e dano/inflamação renal apenas discretos. Já os ratos HS desenvolveram hipertensão e glomerulosclerose acentuadas, expansão intersticial e infiltração renal por macrófagos e células positivas para angiotensina II. Losartan baixou a pressão arterial e preveniu albuminúria e lesão renal. MMF proporcionou proteção semelhante sem alteração pressórica, sugerindo a ação de mecanismos não hemodinâmicos, hipótese reforçada pelo achado de que a HDZ baixou a pressão arterial sem prevenir a nefropatia. RESULTADOS: Esses resultados indicam que o tratamento com HS e NAME predispõe ao desenvolvimento de hipertensão e lesão renal induzidos por excesso de sal, caracterizando um novo modelo de nefropatia crônica. CONCLUSÃO: A resposta ao MMF ou losartan, mas não à hidralazina, sugere o predomínio de fatores inflamatórios

Persistent hypertension and progressive renal injury induced by salt overload after short term nitric oxide inhibition

INTRODUCTION: Administration of the NO inhibitor Nwð-nitro-L-arginine methyl ester (NAME) and a high-salt diet (HS) promotes severe albuminuria and renal injury, which regresses upon discontinuation of treatments. OBJECTIVE: We investigated whether these changes reappear after reinstitution of HS, and whether they are prevented by treatment with the antilymphocyte agent mycophenolate mofetil (MMF) or the AT-1 receptor blocker losartan (L). Adult male Munich-Wistar rats received NAME and HS. A control Group (C) received only HS. After 20 days, rats receiving HS and NAME exhibited severe hypertension and albuminuria. After a 30-day recovery period, hypertension was attenuated and albuminuria had virtually disappeared. MATERIAL AND METHODS: Rats were then distributed among the following groups: HS, receiving HS; NS, receiving a normal salt (NS) diet; HS-MMF, receiving HS and MMF; HS-LOS, receiving HS and L; HS-HDZ, receiving HS and hydralazine (HDZ). Sixty days later, NS rats showed only slight albuminuria and renal damage or inflammation. In contrast, HS rats developed severe hypertension, marked glomerulosclerosis with interstitial expansion and renal infiltration by macrophages and angiotensin II-positive cells. The group treated with losartan had lowered blood pressure and a lack of albuminuria or renal injury. MMF provided similar protection without altering blood pressure, suggesting a nonhemodynamic effect, a hypothesis reinforced by the finding that HDZ lowered blood pressure without preventing renal injury. RESULTS: These results indicate that treatment with HS and NAME predisposes to the development of hypertension and renal injury upon salt overload, characterizing a new model of chronic nephropathy. CONCLUSION: The response to MMF or L, but not HDZ, suggests a key role for inflammatory rather than hemodynamic factors.INTRODUÇÃO: A administração de Nômega-nitro-L-arginina metiléster (NAME), um inibidor da produção de NO, com dieta rica em sal (HS) promove albuminúria e dano renal graves, reversíveis ao interromperem-se os tratamentos. OBJETIVO: Investigamos se tais alterações recrudescem ao reinstituir-se a HS e se são prevenidas pelo micofenolato mofetil (MMF), um agente antilinfócito, ou losartan, um bloqueador do receptor AT-1. MATERIAL E MÉTODOS: Ratos Münich-Wistar machos adultos receberam NAME e HS. Um grupo controle (C) recebeu apenas HS. Após 20 dias, os ratos que receberam HS e NAME exibiam hipertensão e albuminúria graves. Após recuperação de 30 dias, a hipertensão atenuou-se e a albuminúria praticamente desapareceu. Formaram-se então os grupos: HS, recebendo HS; NS, recebendo dieta normal em sal (NS); HS-MMF, recebendo HS e MMF; HS-LOS, recebendo HS e losartan; HS-HDZ, recebendo HS e hidralazina. Após sessenta dias os ratos NS tinham albuminúria e dano/inflamação renal apenas discretos. Já os ratos HS desenvolveram hipertensão e glomerulosclerose acentuadas, expansão intersticial e infiltração renal por macrófagos e células positivas para angiotensina II. Losartan baixou a pressão arterial e preveniu albuminúria e lesão renal. MMF proporcionou proteção semelhante sem alteração pressórica, sugerindo a ação de mecanismos não hemodinâmicos, hipótese reforçada pelo achado de que a HDZ baixou a pressão arterial sem prevenir a nefropatia. RESULTADOS: Esses resultados indicam que o tratamento com HS e NAME predispõe ao desenvolvimento de hipertensão e lesão renal induzidos por excesso de sal, caracterizando um novo modelo de nefropatia crônica. CONCLUSÃO: A resposta ao MMF ou losartan, mas não à hidralazina, sugere o predomínio de fatores inflamatórios

Is urinary density an adequate predictor of urinary osmolality?

Urinary density (UD) has been routinely used for decades as a surrogate marker for urine osmolality (U-osm). We asked if UD can accurately estimate U-osm both in healthy subjects and in different clinical scenarios of kidney disease. UD was assessed by refractometry. U-osm was measured by freezing point depression in spot urines obtained from healthy volunteers (N = 97) and in 319 inpatients with acute kidney injury (N = 95), primary glomerulophaties (N = 118) or chronic kidney disease (N = 106). UD and U-osm correlated in all groups (p < 0.05). However, a wide range of U-osm values was associated with each UD value. When UD was <= 1.010, 28.4% of samples had U-osm above 350 mOsm/kg. Conversely, in 61.6% of samples with UD above 1.020, U-osm was below 600 mOsm/kg. As expected, U-osm exhibited a strong relationship with serum creatinine (S-creat), whereas a much weaker correlation was found between UD and Screat. We found that UD is not a substitute for U-osm. Although UD was significantly correlated with U-osm, the wide dispersion makes it impossible to use UD as a dependable clinical estimate of U-osm. Evaluation of the renal concentrating ability should be based on direct determination of U-osm1

Preclinical Studies with Umbilical Cord Mesenchymal Stromal Cells in Different Animal Models for Muscular Dystrophy

Umbilical cord mesenchymal stromal cells (MSC) have been widely investigated for cell-based therapy studies as an alternative source to bone marrow transplantation. Umbilical cord tissue is a rich source of MSCs with potential to derivate at least muscle, cartilage, fat, and bone cells in vitro. The possibility to replace the defective muscle cells using cell therapy is a promising approach for the treatment of progressive muscular dystrophies (PMDs), independently of the specific gene mutation. Therefore, preclinical studies in different models of muscular dystrophies are of utmost importance. The main objective of the present study is to evaluate if umbilical cord MSCs have the potential to reach and differentiate into muscle cells in vivo in two animal models of PMDs. In order to address this question we injected (1) human umbilical cord tissue (hUCT) MSCs into the caudal vein of SJL mice; (2) hUCT and canine umbilical cord vein (cUCV) MSCs intra-arterially in GRMD dogs. Our results here reported support the safety of the procedure and indicate that the injected cells could engraft in the host muscle in both animal models but could not differentiate into muscle cells. These observations may provide important information aiming future therapy for muscular dystrophies

Is urinary density an adequate predictor of urinary osmolality?

Abstract\ud \ud Background\ud Urinary density (UD) has been routinely used for decades as a surrogate marker for urine osmolality (Uosm). We asked if UD can accurately estimate Uosm both in healthy subjects and in different clinical scenarios of kidney disease.\ud \ud \ud Methods\ud UD was assessed by refractometry. Uosm was measured by freezing point depression in spot urines obtained from healthy volunteers (N = 97) and in 319 inpatients with acute kidney injury (N = 95), primary glomerulophaties (N = 118) or chronic kidney disease (N = 106).\ud \ud \ud Results\ud UD and Uosm correlated in all groups (p < 0.05). However, a wide range of Uosm values was associated with each UD value. When UD was ≤ 1.010, 28.4% of samples had Uosm above 350 mOsm/kg. Conversely, in 61.6% of samples with UD above 1.020, Uosm was below 600 mOsm/kg. As expected, Uosm exhibited a strong relationship with serum creatinine (Screat), whereas a much weaker correlation was found between UD and Screat.\ud \ud \ud Conclusion\ud We found that UD is not a substitute for Uosm. Although UD was significantly correlated with Uosm, the wide dispersion makes it impossible to use UD as a dependable clinical estimate of Uosm. Evaluation of the renal concentrating ability should be based on direct determination of Uosm

Pivotal Role of Toll-Like Receptors 2 and 4, Its Adaptor Molecule MyD88, and Inflammasome Complex in Experimental Tubule-Interstitial Nephritis

Tubule-interstitial nephritis (TIN) results in decreased renal function and interstitial inflammation, which ultimately leads to fibrosis. Excessive adenine intake can cause TIN because xanthine dehydrogenase (XDH) can convert this purine into an insoluble compound, which precipitates in the tubuli. Innate immune sensors, such as Toll-like receptors (TLR) and inflammasome complex, play a crucial role in the initiation of inflammation. The aim of this study was to evaluate the roles of TLR-2 and -4, Myd88 and inflammasome complex in an experimental model of TIN. Here, we show that wild-type (WT) mice fed adenine-enriched food exhibited significant renal dysfunction and enhanced cellular infiltration accompanied by collagen deposition. They also presented higher gene and protein expression of pro-inflammatory cytokines. In contrast, TLR-2, -4, MyD88, ASC and Caspase-1 KO mice showed renoprotection associated with expression of inflammatory molecules at levels comparable to controls. Furthermore, treatment of WT animals with allopurinol, an XDH inhibitor, led to reduced levels of uric acid, oxidative stress, collagen deposition and a downregulation of the NF-kB signaling pathway. We concluded that MyD88 signaling and inflammasome participate in the development of TIN. Furthermore, inhibition of XDH seems to be a promising way to therapeutically target the developing inflammatory process

Análise das dosagens e concentrações séricas da ciclosporina A em cães da raça Golden Retriever normais ou afetados pela distrofia muscular

A distrofia muscular dos cães Golden Retriever (GRMD), uma miopatia degenerativa causada pela ausência da distrofina é geneticamente homóloga à distrofia muscular de Duchenne que acomete humanos, portanto, estes cães são considerados modelos experimentais para estudos em terapia celular. Seu sucesso depende da imunossupressão adequada. A ciclosporina A (CsA) é indicada para tal e a monitorização de suas concentrações sangüíneas e efeitos adversos são essenciais para viabilizar a terapia. Foram estudados cães GRMD, e normais da mesma raça, submetidos a terapia com CsA, associada, nos GRMD, ao transplante de células tronco. Foram avaliados as concentrações sangüíneas do fármaco através de amostras coletadas a cada dois ou três dias e analisadas pelo método do imunoensaio por fluorescência (FPIA). Como resultado observamos que as concentrações de CsA oscilaram muito, em seis dos oito animais. Concluímos que as doses variam individualmente sendo de maior importância avaliar a concentração do fármaco no sangue e sua viabilização no uso da terapia celular.The muscular dystrophy of Golden Retriever (GRMD) is a degenerative miopaty caused by the absence of dystrophy and it is genetically homologue of the Duchenne muscular dystrophy in humans, so, these dogs are considerably experimental models for studies on cellular therapy. Their successful depends of the adequate immunosuppression. Cyclosporin A (CsA) is indicated for that and the monitoring of the blood concentration and adverse effects are essential to viabilise the therapy. It was studied GRMD dogs, and normal dogs from the same breed, submitted for therapy with CsA, associated, on GRMD, of cell transplantation. It was evaluated blood concentration of the drug, between two or tree days using the method of FPIA. In our results we found that the CsA blood concentrations oscillated too much on six than eight of our animals. We concluded that the doses varieties individually and the correct dosage as to important as the evaluation of the blood concentration of the drug and became viable for cell therapy