Publications by authors named "Carlos G Leon"

Background: Invasive fungal infections such as candidiasis constitute an increasingly important medical problem. Drugs currently used for the treatment of candidiasis include polyenes (such as Amphotericin B) and azoles. Amphotericin B (AmpB) presents several limitations such as its nephrotoxicity and limited solubility.

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Advanced prostate cancer (CaP) is often treated with androgen deprivation therapy (ADT). Despite high initial success rates of this therapy, recurrence of the cancer in a castration-resistant (CRPC) form is inevitable. It has been demonstrated that, despite the low levels of circulating androgens resulting from ADT, intratumoral androgen levels remain high and androgen receptor activation persists.

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Background: Emerging evidence suggests that androgens and the androgen receptor (AR) are important mediators of castration-resistant prostate cancer (CRPC) progression. Increased expression of several enzymes responsible for cholesterol synthesis and conversion into downstream androgens has been documented in human CRPC tumors in comparison to primary tumors. Based on these observations it is hypothesized that cholesterol and its overall regulation within the cell are altered, thus modifying precursor levels for de novo androgen synthesis within the castrate tumoral environment.

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Background: Haptoglobin is a plasma protein that scavenges haemoglobin during haemolysis. Phospholipid Transfer Protein (PLTP) transfers lipids from Low Density Lipoproteins (LDL) to High Density Lipoproteins (HDL). PLTP is involved in the pathogenesis of atherosclerosis which causes coronary artery disease, the leading cause of death in North America.

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Objectives: To assess the pharmacokinetics and biodistribution of amphotericin B (AmB) following oral administration in a novel mono/diglyceride-phospholipid formulation and to compare with intravenous (iv) administrations using commercial formulations.

Methods: Rats were allocated into the following treatment groups: oral gavage of AmB dispersed in mono/diglyceride-phospholipid formulation at doses of 4.5 and 10 mg/kg; iv bolus administration of 0.

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Aim: To investigate how different formulations of Amphotericin-B (Amp-B) affect the activity of phospholipid transfer protein (PLTP) when incubated with hyperlipidemic and normolipidemic plasma at physiological temperature (37 degrees C).

Methods: Six hyperlipidemic and six normolipidemic plasma samples were collected and tested for protein concentration. Equivalent protein levels (25 microg) were then tested for PLTP activity using an in vitro established kit at physiological temperature (37 degrees C).

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Objective: To develop an oral formulation of Amphotericin B (AmpB) with: (A) medium chain triglycerides, fatty acids and nonionic surfactants as a self-emulsifying drug delivery system (SEDDS); or (B) glyceryl mono-oleate (Peceol) with poly(ethylene glycol) (PEG)-phospholipids.

Methods: SEDDS formulations were prepared by simple mixing at 40 degrees C. Peceol/DSPE-PEG-lipid formulations were prepared by solvent evaporation.

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Sepsis remains the most common cause of death in intensive care units in the USA, with a current estimate of at least 750,000 cases per year, and 215,000 deaths annually. Despite extensive research still we do not quite understand the cellular and molecular mechanisms that are involved in triggering and propagation of septic injury. Endotoxin (lipopolysaccharide from Gram-negative bacteria, or LPS) has been implicated as a major cause of this syndrome.

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Background: The objective of this work was to determine the effect of an androgen agonist, R1881, on intracellular cholesterol synthesis and esterification in androgen-sensitive (AS) prostate cancer (LNCaP) cells.

Methods: We investigated the activity and expression of cholesterol metabolism enzymes, HMG-CoA-reductase and ACAT in the LNCaP and PC-3 (androgen-independent control) models.

Results: Microsomal PC-3 HMG-CoA-reductase activity was increased with R1881 despite having similar cholesterol levels while increased cholesterol levels in microsomes from LNCaPs treated with R1881 (L+) were associated with increased HMG-CoA reductase activity.

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