Versatile Methodology to Encapsulate Gold Nanoparticles in PLGA Nanoparticles Obtained by Nano-Emulsion Templating

Purpose

Gold nanoparticles have been proved useful for many biomedical applications, specifically, for their use as advanced imaging systems. However, they usually present problems related with stability and toxicity.

Methods

In the present work, gold-nanoparticles have been encapsulated in polymeric nanoparticles using a novel methodology based on nano-emulsion templating. Firstly, gold nanoparticles have been transferred from water to ethyl acetate, a solvent classified as class III by the NIH guidelines (low toxic potential). Next, the formation of nano-emulsions loaded with gold nanoparticles has been performed using a low-energy, the phase inversion composition (PIC) emulsification method, followed by solvent evaporation giving rise to polymeric nanoparticles.

Results

Using this methodology, high concentrations of gold nanoparticles (>100 pM) have been encapsulated. Increasing gold nanoparticle concentration, nano-emulsion and nanoparticle sizes increase, resulting in a decrease on the stability. It is noteworthy that the designed nanoparticles did not produce cytotoxicity neither hemolysis at the required concentration.

Conclusions

Therefore, it can be concluded that a novel and very versatile methodology has been developed for the production of polymeric nanoparticles loaded with gold nanoparticles.

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Graphical Abstract Schematic representation of AuNP-loaded polymeric nanoparticles preparation from nano-emulsion templating

     

Venous thromboembolism in patients with renal insufficiency: findings from the RIETE Registry

Background

Current guidelines make no specific recommendations for venous thromboembolism (VTE) treatment in patients with renal insufficiency, but some experts recommend some reduction in heparin dose.

Methods

Registro Informatizado de Enfermedad TromboEmbólica (RIETE) is an ongoing, prospective registry of consecutively enrolled patients with objectively confirmed, symptomatic, acute VTE. In this analysis we retrospectively analyzed the effect of renal insufficiency on the incidence of fatal pulmonary embolism (PE) and fatal bleeding within 15 days of diagnosis.

Results

Up to March 2005, 10,526 patients with acute VTE were enrolled in RIETE, of whom 9234 (88%) had a creatinine clearance (CrCl) greater than 60 mL/min, 704 (6.7%) had a CrCl 30 to 60 mL/min, and 588 (5.6%) had a CrCl less than 30 mL/min. The incidence of fatal PE during the study period was 1.0%, 2.6%, and 6.6%, respectively. Fatal bleeding occurred in 0.2%, 0.3%, and 1.2% of the patients, respectively. On multivariate analysis, patients with a CrCl less than 30 mL/min were independently associated with an increased risk for fatal PE and fatal bleeding. In addition, initial diagnosis of PE, immobility for 4 days or more, cancer, and initial therapy with unfractionated heparin were independent predictors of fatal PE; whereas immobility for 4 days or more and cancer were independent predictors of fatal bleeding.

Conclusions

Patients with VTE who have renal insufficiency had an increased incidence of both fatal PE and fatal bleeding, but the risk of fatal PE far exceeded that of fatal bleeding. Our data support the use of full-dose anticoagulant therapy, even in patients with a CrCl less than 30 mL/min.     

Cimetidine in acute gastric mucosal bleeding

The hemostatic effect of cimetidine has been investigated in a double-blind, randomized trial in patients bleeding from acute mucosal lesions. During a 48-hr period, hemostasis was achieved in 5 of 15 patients (33%) treated with intravenous cimetidine administered with antacid therapy and in four of 12 patients (33%) treated with antacids alone. In a second stage of the trial, the effect of oral cimetidine in preventing further bleeding was investigated. Bleeding did not recur in 18 patients receiving cimetidine and antacids while 6 out of 20 patients who were given antacids alone suffered further hemorrhage during the 14-day period of the study. It is concluded that intravenous cimetidine administered with antacids was not found more effective in obtaining hemostasis than antacids alone. When given orally to patients who had been bleeding from acute lesions but were not doing so at the beginning of treatment, cimetidine with antacids is more effective than antacids alone in the prevention of further bleeding.     

Effects of sildenafil on the human response to acute hypoxia and exercise

We examined the effects of the 5-phosphodiesterase (5-PDE) inhibitor sildenafil on pulmonary arterial pressure and some oxygen transport and cardiopulmonary parameters in humans during exposure to hypobaric hypoxia at rest and after exercise. In a double-blind study, 100 mg sildenafil or placebo was administered orally to 14 healthy volunteers 45 min before exposure to 5,000 m of simulated altitude. Arterial oxygen saturation (SaO2), heart rate (HR), tidal volume (VT), respiratory rate (RR), left ventricular ejection fraction (EF), and pulmonary arterial pressure (PAP) were measured first at rest in normoxia, at rest and immediately after exercise during hypoxia, and after exercise in normoxia. The increase in systolic PAP produced by hypoxia was significantly decreased by sildenafil at rest from 40.9 +/- 2.6 to 34.9 +/- 3.0 mmHg (-14.8%; p = 0.0046); after exercise, from 49.0 +/- 3.9 to 42.9 +/- 2.6 mmHg (-12.6%; p = 0.003). No significant changes were found in normoxia either at rest or after exercise. Measurements of the effect of sildenafil on exercise capacity during hypoxia did not provide conclusive data: a slight increase in SaO2 was observed with exercise during hypoxia, and sildenafil did not cause significant changes in ventilatory parameters under any condition. Sildenafil diminishes the pulmonary hypertension induced by acute exposure to hypobaric hypoxia at rest and after exercise. Further studies are needed to determine the benefit from this treatment and to further understand the effects of sildenafil on exercise capacity at altitude.     

Post-mortem castration by a dog: a case report

A man was found dead in a room where two dogs and a cat were wandering freely. His legs were bare and his underpants presented a few small tears. The deceased exhibited a partial emasculation but with only a small amount of bleeding. No other significant injuries were found, particularly no defence lesions. Death was natural, caused by the rupture of a myocardial infarct. A small piece of connective tissue was found in the gastric contents of one of the dogs. This fragment, as well as bloodstained hairs from its jaws, were analysed for DNA.     

Clinical trials and evaluation of a mobile, robotic tele-ultrasound system

We have developed a robotic tele-ultrasound system (OTELO) that allows an expert to examine a distant patient by ultrasound. At the expert station, a sonographer controls a virtual probe. Movements are reproduced at the patient station, which may be several kilometres away, on a real probe held by a lightweight robot, which is positioned on the patient by a paramedic. Two medical teams tested the tele-ultrasound system at two different hospitals on a total of 52 patients. Except for some difficulties caused by particular conditions, the diagnosis obtained with the remote scanning system agreed in at least 80% of the cases with the diagnosis made by conventional scanning. The results demonstrate the feasibility and efficiency of the device.     

Atherogenic and inflammatory profile of human arterial endothelial cells (HUAEC) in response to LDL subfractions

BACKGROUND: Electronegative LDL (LDL(-)) is a minor modified LDL fraction present in plasma that has been demonstrated to be inflammatory in endothelial cells isolated from human umbilical vein (HUVEC). METHODS: A protein array able to measure 42 cytokines, chemokines and related compounds involved in atherogenesis was used to determine their release into the culture medium of human arterial endothelial cells (HUAEC) activated or not by two low-density lipoprotein (LDL) fractions isolated from human plasma by anion-exchange chromatography. RESULTS: The results of the protein array (confirmed using specific ELISAs for each induced factor) revealed that HUAEC in the absence of stimuli released small amounts of interleukin 8 (IL-8), monocyte chemotactic protein 1 (MCP-1) and growth-related oncogene (GRO). The major native LDL fraction (named LDL(+)) increased the release of these molecules and also those of interleukin 6 (IL-6) and GROalpha. Compared to LDL(+), the minor modified fraction, named electronegative LDL (LDL(-)), increased all these factors to a greater degree and also induced the release of granulocyte-monocyte colony-stimulating factor (GM-CSF) and platelet-derived growth factor B (PDGF-B). These results were confirmed by ELISA. CONCLUSIONS: All these results indicate that, compared to LDL(+), LDL(-) fraction promotes not only the release of proinflammatory factors but also those of atherogenic factors in endothelial cells of arterial origin, thereby suggesting a new role for LDL(-) in atherogenesis.     

A pharmacologically-based array to identify targets of cyclosporine A-induced toxicity in cultured renal proximal tubule cells

Mechanisms of cyclosporine A (CsA)-induced nephrotoxicity were generally thought to be hemodynamic in origin; however, there is now accumulating evidence of a direct tubular effect. Although genomic and proteomic experiments by our group and others provided overall information on genes and proteins up- or down-regulated by CsA in proximal tubule cells (PTC), a comprehensive view of events occurring after CsA exposure remains to be described. For this purpose, we applied a pharmacologic approach based on the use of known activities of a large panel of potentially protective compounds and evaluated their efficacy in preventing CsA toxicity in cultured mouse PTC. Our results show that compounds that blocked protein synthesis and apoptosis, together with the CK2 inhibitor DMAT and the PI3K inhibitor apigenin, were the most efficient in preventing CsA toxicity. We also identified GSK3, MMPs and PKC pathways as potential targets to prevent CsA damage. Additionally, heparinase-I and MAPK inhibitors afforded partial but significant protection. Interestingly, antioxidants and calcium metabolism-related compounds were unable to ameliorate CsA-induced cytotoxicity. Subsequent experiments allowed us to clarify the hierarchical relationship of targeted pathways after CsA treatment, with ER stress identified as an early effector of CsA toxicity, which leads to ROS generation, phenotypical changes and cell death. In summary, this work presents a novel experimental approach to characterizing cellular responses to cytotoxics while pointing to new targets to prevent CsA-induced toxicity in proximal tubule cells.     

Going high with type 1 diabetes

This review aims to identify the main issues facing a healthy and well-controlled type-1 diabetic mountaineer at high altitude. Most of the problems are self-managed by the diabetic climber although the risk of serious morbidity or even death remains. Given the scarce evidence on diabetes at altitude, an extensive search of the literature, including case reports and anecdotes was carried out to reach the recommendations.