Protective effect of L-arginine on hypercholesterolemia-enhanced renal ischemic injury.

The effects of hypercholesterolemia on ischemic renal failure were evaluated in rats subjected to 60 min of left renal artery clamping and contralateral nephrectomy. One group of rats (HC) was kept on a cholesterol-supplemented diet for 3 weeks before renal injury and compared to a group fed a regular diet (ND). Two days after renal ischemia, inulin clearance (C(in), ml/min per 100 g BW) was lower in HC-rats (0.033 +/- 0.011) than in ND-rats (0.227 +/- 0.037; P < 0.01). indicating that hypercholesterolemia potentiated renal ischemic injury. Twenty-one days after renal ischemia the C(in) of HC-rats did not differ from ND-rats, suggesting that hypercholesterolemia did not limit late recovery. Since nitric oxide production is impaired in HC, L-arginine (50 mg/kg BW i.v.) was administered immediately after ischemia. Two days after ischemia, L-arg did not protect ND-rats from ischemia, while the C(in) and renal blood flow were higher in L-arg-treated HC rats than in untreated HC rats (C(in) = 0.125 +/- 0.013 rats vs. 0.033 +/- 0.011; P < 0.001) (RBF = 3.96 +/- 0.64 vs. 2.40 +/- 0.20 ml/min per 100 g BW; P < 0.05), indicating that L-arg protects HC rats from renal ischemia. The administration of D-arginine to ND rats induced a significant decrease of the C(in) and a significant increase of FE H2O, FE Na and FE K compared to the L-arginine and not treated groups. Cultures of inner medullary collecting duct cells from ND rats were resistant to 24-h hypoxia. In contrast, IMCD cell cultures from HC rats showed higher LDH release after 24-h hypoxia than normoxic cells (69.2 +/- 3.4 vs. 30.9 +/- 3.6%, P < 0.001); 1 mM L-arg added to the medium attenuated LDH release (44.3 +/- 2.4%, P < 0.01). These data demonstrate that HC predisposes renal tubular cells to hypoxic injury and L-arg protects cells of HC.

Genetic variants in genes related to lipid metabolism and atherosclerosis, dyslipidemia and atorvastatin response.

OBJECTIVE: Using candidate gene approach, we have investigated the effect of single nucleotide polymorphism (SNP) in genes related to lipid metabolism and atherosclerosis on dyslipidemia and atorvastatin response. METHODS: The study included 157 patients treated with atorvastatin and 145 controls. Genomic DNA was isolated and genotyped using SNPlex technology. RESULTS: Allele and genotype disease association test revealed that APOB rs693 (OR: 2.2 [1.5-3.2], p=0.0001) and CD36 rs1984112 (OR: 3.7 [1.9-7.0], p=0.0002) SNPs were independent risk factors for hypercholesterolemia. Only APOB rs693 T variant allele was associated with increased LDL cholesterol levels (>160mg/dL). After atorvastatin treatment (10mg/day/4weeks), LIPC -514T allele was positively associated with LDL cholesterol reduction. CONCLUSION: The current study reinforces the current knowledge that carrying APOB rs693 is an independent risk factor for dyslipidemia and higher LDL levels. Furthermore, we found that a variant of CD36 was associated with dyslipidemia as a risk (rs1984112) factor. Finally, atorvastatin response could be predicted by LIPC -514C>T SNP and physical activity. In conclusion, our data evidences the contribution of genetic markers and their interaction with environmental factor in the variability of statin response.

Nephrotoxicity of amphotericin B is attenuated by solubilizing with lipid emulsion.

Nephrotoxicity is the major adverse effect of conventional amphotericin B (AMB/D), often limiting administration of full dosage. The new liposomal amphotericin B seems to be less toxic. The new liposomal amphotericin B seems to be less toxic. In this study, it is proposed that solubilizing the standard AMB/D preparation with 10% lipid emulsion will attenuate nephrotoxicity. Rats were injected with either AMB/D (Fungizone), AMB, AMB/D plus lipid emulsion (AMB/D/LE), or sodium deoxycholate (D). Renal function studies were performed on day 5. To assess a direct tubular toxic effect, isolated rat proximal tubule suspensions and inner medullary collecting duct cells in culture were exposed to AMB/D, AMB, AMB/D/LE, liposomal amphotericin B, and D for 60 min in normoxia. Lactate dehydrogenase (LDH) release was assessed as an index of cell injury. Creatinine clearance (ml/min per 100 g) averaged 0.79 +/- 0.04 in control rats, 0.29 +/- 0.09 in AMB rats (P < 0.001 versus control), 0.38 +/- 0.04 in AMB/D rats, 0.46 +/- 0.05 in D rats, and 0.78 +/- 0.03 in AMB/LE rats. Renal blood flow (ml/min per 100 g) was 3.45 +/- 0.31 in control, 1.29 +/- 0.28 in AMB, 1.42 +/- 0.23 in AMB/D, 3.03 +/- 0.39 in D, and 2.71 +/- 0.21 in AMB/D/LE rats. The fractional excretion of potassium (%) was 27.3 +/- 1.18 in control rats, 61.6 +/- 7.00 in AMB/D rats, 58.4 +/- 15.32 in AMB rats, and 37.9 +/- 2.06 in AMB/D/LE rats. LDH release (%) in proximal tubules incubated with AMB/D and D was 43.6 +/- 3.39 and 58.6 +/- 4.20, respectively. Addition of lipid emulsion decreased LDH release: 21.6 +/- 1.22 for AMB/D/LE and 26.4 +/- 3.03 for deoxycholate plus lipid emulsion. AMB did not demonstrate any toxic effect in proximal tubule suspensions. D was not toxic to inner medullary collecting duct cells at 0.16 mg/ml, whereas D at a higher dose and AMB induced a significant LDH release. Addition of lipid emulsion did not affect the antifungal activity as assessed by the Etest method. In conclusion, an alternative way of administering standard AMB with reduced nephrotoxicity is proposed.

Polimorfismos no receptor Scavenger classe B tipo I e sua relação com perfil lipídico sérico e resposta a atorvastatina em indivíduos brasileiros / Scavenger receptor class B type I polymorphisms and its relation with serum lipids profile and response to atorvastatin in Braszilian individuals

O receptor scavenger BI (SR-BI) é um componente chave do transporte reverso do colesterol. Polimosfismos no gene SCARB1 foram associados com variações no perfil lipídico e outros de risco cardiovascular. Os polimosfismos de nucleotídeo único In5C>T e Ex8C>T no SCARB1 e medidas de lípides e apolipoproteínas foram avaliadas em 79 hipercolesterolêmicos (HC) e 173 normolipidêmicos (NL) provenientes do Brasil. Pacientes HC foram tratados com atorvastatina (10mg/dia/4semanas). Os polimosfismos foram identificados por PCR-RFLP. Os indivíduos HC portadores dos genótipos In5CC+TT mostraram concentrações mais elevadas de LDL-C, apoB, e menores da relação apoAI/apoB. No grupo NL, os genótipos In5CC+TT foram associados com concentrações maiores de LDL-C. Os indivíduos HC portadores de genótipo Ex8CC tiveram uma variação menor da razão apoAI/apoB em resposta à atorvastatina (p<0,05). Nos Hc portadores do haplótipo Ex8CC+CT/In5CT+TT tiveram valores basais elevados de LDL-C e relação apoAI/apoB diminuída. Após o tratamento com atorvastatina, os indivíduos Hc portadores do haplótipo Ex8CC/In5CC tiveram uma variação menor na relação apoAI/apoB. Os genótipos In5CT+TT no SCANB1 conferem um perfil lipídico mais aterogênico. O genótipo Ex8CC e o haplótipo Ex8CC estão associados com uma resposta à atorvastatina menor da razão apoAI/apoB na nossa população.