Gold

The present report evaluates the advantages of using the gold nanoparticle-mediated laser perforation (GNOME LP) technique as a computer-controlled cell optoperforation to introduce Lucifer yellow (LY) into cells in order to analyze the gap junction coupling in cell monolayers. To permeabilize GM-7373 endothelial cells grown in a 24 multiwell plate with GNOME LP, a laser beam of 88 μm in diameter was applied in the presence of gold nanoparticles and LY. After 10 min to allow dye uptake and diffusion through gap junctions, we observed a LY-positive cell band of 179 ± 8 μm width. The presence of the gap junction channel blocker carbenoxolone during the optoperforation reduced the LY-positive band to 95 ± 6 μm. Additionally, a forskolin-related enhancement of gap junction coupling, recently found using the scrape loading technique, was also observed using GNOME LP. Further, an automatic cell imaging and a subsequent semi-automatic quantification of the images using a java-based ImageJ-...

Gold nanoparticle mediated (GNOME) laser transfection is a powerful technique to deliver small biologically relevant molecules into cells. However, the transfection of larger and especially negatively charged DNA remains challenging. The efficiency for pDNA was 0.57% using parameter that does not influence the endo- and exogenous DNA. In order to gain a deeper understanding of the actual molecule uptake process, the uptake efficiency was determined using molecules of different sizes. It was evaluated that uncharged dextran molecules (2000 kDa) were delivered with an efficiency of 68%. The intracellular distribution of injected molecules was visualized and larger molecules were primary found in the cytoplasm. Patch clamp measurements suggested a permeabilization time up to 15 minutes. The uptake efficiency depended on the size and charge of the molecule to deliver as well as the cell size. A minor role for transfection plays the cell type since primary stem cells were successfully transfected. The perforation efficiency of semi-adherent and suspension cells is influenced by the cell and molecule size.

The gold mining sector plays a significant economic function in many African countries. If properly governed, this natural resource has the potential to constitute a huge opportunity for sustainable development. Currently, much of the gold production activities across the continent are legal. However, the African gold mining sector suffers from a range of challenges. This discussion paper aims to explore Africa’s gold conflict and outlines the challenges to its governance and development.

Mesoporous S,N-TiO(2) nanocomposite was prepared by a one-pot template free homogeneous coprecipitation technique using titanium oxysulfate sulfuric acid complex hydrate, thiourea, ethanol, and water. Nano gold deposition on mesoporous S,N-TiO(2) was preformed by a borohydrate reduction method. To evaluate the structural and electronic properties, these catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM), UV-vis DRS, photoluminescent (PL) spectra, Fourier transform infrared (FTIR), and TPO/TPD. CO adsorption and CO + O(2) interaction over these catalysts were investigated by in situ FTIR. Sulfur and nitrogen doping enhances the catalytic activity of Au/TiO(2.) Higher catalytic activity of Au/S,N-TiO(2) compared to Au/TiO(2) was attributed to the presence of oxygen vacancy and creation of new adsorption sites at Au/TiO(2) interfaces for the adsorption and activation of O(2) molecules.

Optically activated cavitation in a nanoemulsion contrast agent is proposed for therapeutic applications. With a 56°C boiling point perfluorohexane core and highly absorptive gold nanospheres at the oil-water interface, cavitation nuclei in the core can be efficiently induced with a laser fluence below medical safety limits (70 mJ/cm2 at 1064 nm). This agent is also sensitive to ultrasound (US) exposure and can induce inertial cavitation at a pressure within the medical diagnostic range. Images from a high-speed camera demonstrate bubble formation in these nanoemulsions. The potential of using this contrast agent for blood clot disruption is demonstrated in an in vitro study. The possibility of simultaneous laser and US excitation to reduce the cavitation threshold for therapeutic applications is also discussed.

Protein fibrillation process (e.g., from amyloid beta (Aβ) and α-synuclein) is the main cause of several catastrophic neurodegenerative diseases such as Alzheimer's and Parkinson diseases. During the past few decades, nanoparticles (NPs) were recognized as one of the most promising tools for inhibiting the progress of the disease by controlling the fibrillation kinetic process; for instance, gold NPs have a strong capability to inhibit Aβ fibrillations. It is now well understood that a layer of biomolecules would cover the surface of NPs (so called "protein corona") upon the interaction of NPs with protein sources. Due to the fact that the biological species (e.g., cells and amyloidal proteins) "see" the protein corona coated NPs rather than the pristine coated particles, one should monitor the fibrillation process of amyloidal proteins in the presence of corona coated NPs (and not pristine coated ones). Therefore, the previously obtained data on NPs effects on the fibrillation process should be modified to achieve a more reliable and predictable in vivo results. Herein, we probed the effects of various gold NPs (with different sizes and shapes) on the fibrillation process of Aβ in the presence and absence of protein sources (i.e., serum and plasma). We found that the protein corona formed a shell at the surface of gold NPs, regardless of their size and shape, reducing the access of Aβ to the gold inhibitory surface and, therefore, affecting the rate of Aβ fibril formation. More specifically, the anti-fibrillation potencies of various corona coated gold NPs were strongly dependent on the protein source and their concentrations (10% serum/plasma (simulation of an in vitro milieu) and 100% serum/plasma (simulation of an in vivo milieu)).

Thorough understanding of magnetic nanoparticle (MNP) properties is essential for developing new theranostics. In this study, we provide evidence that non-modified magnetic iron oxide nanoparticles and their functionalized derivatives may be used to restrict growth and capture different pathogens. Coprecipitation of Fe(2+) and Fe(3+) ions in an alkaline solution was used to synthesize MNPs that subsequently were functionalized by gold and aminosilane coating. Transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR) were used to assess their physicochemical properties. A significant decrease of Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans outgrown from medium after addition of MNPs or their derivatives was observed during 24h culture. Measurement of optical density revealed that using MNPs, these pathogens can be quickly captured and removed (with efficiency reaching almost 100%) from purposely infected saline buffer and body fluids such as human blood plasma, serum, abdominal fluids and cerebrospinal fluids. These effects depend on nanoparticle concentration, surface chemistry, the type of pathogen, as well as the surrounding environment.

We hypothesized that rapid presentation may be a general feature of tuberculosis (TB) associated with human immunodeficiency virus (HIV) that limits the impact of HIV on the point prevalence of TB. To investigate this, we performed a cross-sectional HIV and TB disease survey with retrospective and prospective follow-up. HIV prevalence among 1,773 systematically recruited miners was 27%. TB incidence was

Cytomegalovirus (CMV) viremia has been shown to be an independent risk factor for increased mortality among HIV-infected individuals in the developing world. While CMV infection is nearly ubiquitous in resource-poor settings, few data are available on the role of subclinical CMV reactivation on HIV. Using a cohort of mineworkers with stored plasma samples, we investigated the association between CMV DNA concentration and mortality prior to antiretroviral therapy availability. Among 1341 individuals (median CD4 count 345 cells/µl, 70% WHO stage 1 or 2, median follow-up 0.9 years), 70 (5.2%) had CMV viremia at baseline; 71 deaths occurred. In univariable analysis CMV viremia at baseline was associated with a three-fold increase in mortality (hazard ratio [HR] 3.37; 95% confidence intervals [CI] 1.60, 7.10). After adjustment for CD4 count, WHO stage and HIV viral load (N = 429 with complete data), the association was attenuated (HR 2.27; 95%CI 0.88, 5.83). Mortality increased with high...

To determine the efficacy of secondary preventive therapy against tuberculosis (TB) among gold miners working in South Africa. An observational study. Health service providing comprehensive care for gold miners. The incidence of recurrent TB was compared between two cohorts of HIV-infected miners: one cohort (n = 338) had received secondary preventive therapy with isoniazid (IPT) and the other had not (n = 221). The overall incidence of recurrent TB was reduced by 55% among men who received IPT compared with those who did not (incidence rates 8.6 and 19.1 per 100 person-years, respectively; incidence rate ratio, 0.45; 95% confidence interval 0.26-0.78). The efficacy of isoniazid preventive therapy was unchanged after controlling for CD4 cell count and age. The number of person-years of IPT required to prevent one case of recurrent TB among individuals with a CD4 cell count < 200 x 106 cells/l, and > or = 200 x 106 cells/l was 5 and 19, respectively. Secondary preventive therapy reduces TB recurrence: the absolute impact appears to be greatest among individuals with low CD4 cell counts. International TB preventive therapy guidelines for HIV-infected individuals need to be expanded to include recommendations for secondary preventive therapy in settings where TB prevalence is high.

Alveolar macrophages of hamsters have a cell surface antigen not found on other pulmonary cells or macrophages from other sites. A specific mouse monoclonal antibody and protein A-colloidal gold were used to study the distribution of this antigen at the ultrastructural level. By quantitating the number of antigenic sites per unit linear distance of membrane of the total cell surface, it was established that this antigen is randomly distributed on the plasma membrane. Cell-to-cell heterogeneity in antigen density was correlated with other ultrastructural features of lung macrophages studied morphometrically. A strong correlation (r = 0.77) between antigen density and secondary lysosome content was found, supporting the thesis that expression of this antigen increases with macrophage age. No apparent topographic relationship of surface antigen to any cytoplasmic organelles could be inferred from the ultrastructural morphology. This study also used immuno-ultrastructural techniques to visualize stages of the internalization of labeled antigen in live cells. While some cells retained a random distribution of antigen at 0 degrees C, most showed movement of antigenic sites away from pseudopodia to clusters on more linear (less ruffled) portions of cell surface. At 37 degrees C, the antigen was internalized and could be visualized within coated pits and endocytic vacuoles. Definition of the anatomic distribution of this antigen under various conditions provides a baseline for further ultrastructural investigations of the function of this antigen.

Alveolar macrophages of hamsters have a cell surface antigen not found on other pulmonary cells or macrophages from other sites. A specific mouse monoclonal antibody and protein A-colloidal gold were used to study the distribution of this antigen at the ultrastructural level. By quantitating the number of antigenic sites per unit linear distance of membrane of the total cell surface, it was established that this antigen is randomly distributed on the plasma membrane. Cell-to-cell heterogeneity in antigen density was correlated with other ultrastructural features of lung macrophages studied morphometrically. A strong correlation (r = 0.77) between antigen density and secondary lysosome content was found, supporting the thesis that expression of this antigen increases with macrophage age. No apparent topographic relationship of surface antigen to any cytoplasmic organelles could be inferred from the ultrastructural morphology. This study also used immuno-ultrastructural techniques to ...