Lipid lowering therapy with fluvastatin and pravastatin in patients with HIV infection and antiretroviral therapy: comparison of efficacy and interaction with indinavir.

BACKGROUND: Lipoprotein disorders in HIV-positive patients receiving highly active antiretroviral therapy (HAART) are becoming a major concern in HIV treatment, since there is growing evidence for an association between HAART-induced hyperlipidemia and increased cardiovascular risk. Yet relatively few data are available on the possible interactions of HAART and treatment with statins. PATIENTS AND METHODS: In this prospective study, 25 HIV-positive, treatment-experienced patients (five female, 20 male, all Caucasian) were treated with either fluvastatin or pravastatin. Total cholesterol, low density lipoprotein (LDL) and high density lipoprotein (HDL) levels, and serum triglycerides were determined at regular intervals, as well as therapeutic drug monitoring to assess possible drug interactions. RESULTS: In 13 pravastatin-treated patients, a decrease in total cholesterol levels (from 7.12 mmol/l to 6.29 mmol/l) after 12 weeks of therapy was seen. In 12 patients treated with fluvastatin, a permanent reduction of total cholesterol (from 6.46 mmol/l to 5.31 mmol/l) after 12 weeks was observed. The reduction of LDL levels was 30.2% in the fluvastatin group and 14.4% in the pravastatin group. In eight patients receiving an indinavir-containing HAART, indinavir plasma levels were not significantly influenced. No effect on triglycerides or HDL was observed. CONCLUSION: Fluvastatin and pravastatin are efficient in lowering total and LDL cholesterol levels in HIV-positive patients receiving HAART. Furthermore, no influence on indinavir plasma levels could be observed. Therefore, both compounds seem to be a viable treatment option in HAART-induced hypercholesterolemia.

Liquid chromatographic method for the determination of uridine in human serum.

To evaluate uridine levels in humans we developed a very sensitive and specific high-performance liquid chromatographic method for the determination of uridine in serum. We use techniques which are available in a standard analytical laboratory. Chromatographic analysis was carried out on a Phenomenex Aqua C18 5 micro 125A column protected by a guard cartridge system. Potassium dihydrogen phosphate buffer-acetonitrile was used as an eluent and oxypurinol as the internal standard. All sample preparation steps were done at 4 degrees C and the autosampler was cooled down to 4 degrees C. The calibration curve was linear throughout the calibration range from 0.25 to 100 micromol/l. This method was primarily established to evaluate uridine serum levels in patients with HIV infection since patients on highly active antiretroviral therapy (HAART) might develop metabolic disturbances that could lead to severe and fatal lactic acidosis due to mitochondrial toxicity. It is suggested that a limited or inadequate uridine supply is at least in part responsible for the onset of such deterioration.

Nephritogenic ochratoxin A interferes with mitochondrial function and pH homeostasis in immortalized human kidney epithelial cells.

The ubiquitous nephritogenic and carcinogenic fungal metabolite ochratoxin A (OTA) has been shown to interact with renal cell function at low nanomolar concentrations. This is possibly brought about through changes in cellular pH (pHc) homeostasis and mitochondrial function. We assessed the effect of nanomolar concentrations of OTA on pHc homeostasis and the possible involvement of mitochondria using immortalized human kidney epithelial (IHKE1) cells. Within seconds OTA evoked a decrease of pHc with a threshold concentration of 0.1 nmol/l, followed by a sustained alkalinization. Acidification was the same in bicarbonate and non-bicarbonate Ringer solution. When Ca2+ entry across the plasma membrane was prevented, virtually no OTA-induced pH changes could be observed. Inhibition of Na+/H+-exchange (NHE, Na+-free solution) and H+-ATPase (bafilomycin A1) did not reduce the OTA-induced acidification. By contrast, determination of NHE activity as a function of pHc revealed that OTA stimulates NHE (maximal flux increases) in a Ca2+-dependent manner. OTA exposure did not increase lactic acid production, indicating that anaerobic glycolysis was not enhanced. Inhibiting complexes I, III and IV of the mitochondrial electron transport chain (ETC) with rotenone, antimycin A and CN- prevented the OTA-induced acidification almost completely. Completely inhibiting F1FO-ATPsynthase with oligomycin reduced the effect of OTA by approximately equal 50%. In addition, OTA induced a hyperpolarization of the mitochondrial membrane potential (psim) in a Ca2+-dependent manner. Furthermore, OTA exposure resulted in a mitochondria-dependent increase of the cellular ATP content. We conclude that OTA activates mitochondria and NHE by interfering with cellular Ca2+ homeostasis. Stimulation of mitochondrial metabolism leads to enhanced "proton production". Anaerobic glycolysis is not enhanced.

Nephritogenic ochratoxin A interferes with hormonal signalling in immortalized human kidney epithelial cells.

The ubiquitous nephritogenic and carcinogenic fungal metabolite ochratoxin A (OTA) affects function and growth of renal epithelial cells. We studied the possible contribution of changes in cellular Ca2+ homeostasis to the effects of nanomolar concentrations of OTA on immortalized human kidney epithelial (IHKE-1) cells. The effects of OTA on cellular calcium homeostasis ([Ca2+]i), cell proliferation and viability and its interaction with angiotensin II (Ang II) and epidermal growth factor (EGF) were investigated. OTA potentiated EGF- and Ang II-induced cell proliferation Ca2+ dependently at OTA concentrations of 0.1 or 1 nmol/l. A decrease in cell viability could be observed only after 24 h exposure, with threshold concentrations greater than 10 nmol/l. This reduction of cell viability was independent of Ca2+. Within seconds, OTA evoked reversible and concentration-dependent [Ca2+]i oscillations with a threshold concentration of < or =0.1 nmol/l. These oscillations were abolished by removal of extracellular Ca2+, by the Ca(2+)-channel blocker SKF 96365 and by inhibition of phospholipase C. OTA also stimulated thapsigargin-sensitive Ca(2+)-ATPase activity and increased the filling state of thapsigargin-sensitive Ca(2+)-stores. Exposure to OTA concentration dependently increased cellular adenosine 3',5'-cyclic monophosphate (cAMP) content. In addition, OTA-induced changes of [Ca2+]i were reduced significantly by the protein kinase A inhibitor H-89. Finally, 0.1 or 1 nmol/l OTA potentiated the effects of Ang II and EGF on cellular Ca2+ homeostasis. We conclude that OTA may impair cellular Ca2+ and cAMP homeostasis already at low nanomolar concentrations, resulting in concentration-dependent [Ca2+]i oscillations. OTA interferes also with hormonal Ca2+ signalling, thereby leading to altered cell proliferation. The reduction of cell viability at higher OTA concentrations seems not to depend on Ca2+.