Electron microscopy in human diseases: diagnostic and research perspectives

Metagenomic analysis of the ocular toxoplasmosis in children uveitis from Fayoum governorate, Egypt

Granulomatous anterior uveitis with single or numerous gelatinous nodules was found in children living in rural Egypt. All ocular diseases were originally thought to be water-born and related to digenic flukes. The current study sought to learn more about the causes of anterior granulomatous uveitis in Egyptian youngsters who used to swim in rural water canals. 50 children with eye lesions that had not responded to medical treatment were recruited. Four samples were surgically extracted and examined using real-time PCR, transmission electron microscopy (TEM), and shotgun metagenomic sequencing (SMS). Toxoplasma gondii was detected free within the syncytium's distal section, while the proximal part exhibited active synthesis of a presumably extra-polymeric material, possibly released by the microbial population. Toxoplasma gondii was found in 30 samples. Serologically, distinct anti-Toxoplasma antibodies were not found in 91.6% of patients. SMS showed that the T. gondii ME 49 strain had the greatest percentage (29-25%) in all samples within an Acinetobacter-containing microbial community. These findings suggested that these bacteria entered the body via the exterior route rather than the circulatory route. The lack of genetic evidence for subsequent parasite stages invalidates the prior findings about the assumed trematode stage.

Detecting cadmium during ultrastructural characterization of hepatotoxicity

BACKGROUND

The threat of cadmium (Cd), which is the cause of itai-itai disease in Japan, is still complicated and confusing, especially for digestive system, such as liver disease. One of the most keys of this problem is demonstrating that the hepatotoxicity is indeed induced by Cd. Therefore, we attempt detecting Cd at microscale during ultrastructural imaging of liver tissue.

METHODS

12 rats were divided randomly into two experimental groups: control and Cd-treated. Treated rats were intraperitoneal injected with 1 mg/kg body weight cadmium chloride (CdCl₂) for 4 weeks (5 P.M each day for 6 days/week). At the end of the exposure period, liver tissue samples were processed into ultrathin sections for analysis of advanced analytical transmission electron microscopy and X-ray energy dispersive spectroscopy (TEM/X-EDS) investigations. Ultrastructural images and X-ray energy dispersive spectrum were acquired at microscale.

RESULTS

Cd can cause changes in the structure of the organelle, including the collapse of the membrane structure in the cell, the destruction of the internal structure of the organelle, the mitochondrial swelling, the expansion of the endoplasmic reticulum, and the appearance of inclusions. Cadmium bioaccumulation is detected in the mitochondria at microscale by TEM/X-EDS, which is the visual evidence of morphological changes of mitochondria related to Cd.

CONCLUSION

The combination of detailed ultrastructure and microscale X-ray energy dispersive spectroscopy (X-EDS) characterization of cadmium hepatotoxicity demonstrate that cadmium indeed leads to mitochondrial damage, which is helpful for further investigation of the pathological mechanism of cadmium hepatotoxicity.

A new way to prepare gold nanoparticles by sputtering - Sterilization, stability and other properties

We have developed a novel simple method for effective preparing gold nanoparticles (AuNPs) intended for utilization in biomedicine. The method is based on gold sputtering into liquid poly(ethylene glycol) (PEG). The PEG was used as a basic biocompatible stabilizer of the AuNP colloid. In addition, two naturally occurring polysaccharides - Chitosan (Ch) and Methylcellulose (MC) - were separately diluted into the PEG base with the aims to enhance the yield of the sputtering without changing the sputtering parameters, and to further improve the stability and the biocompatibility of the colloid. The colloids were sterilized by steam, and their stability was measured before and after the sterilization process by dynamic light scattering and UV-Vis spectrophotometry. The results indicated a higher sputtering yield in the colloids containing the polysaccharides. The colloids were also characterized by atomic absorption spectroscopy (AAS) to reveal the composition of the prepared nanoparticles by transmission electron microscopy (TEM) to visualize the nanoparticles and to evaluate their size and clustering, and by rheometry to estimate the viscosity of the colloids. The zeta-potential of the AuNPs was also determined as an important parameter indicating the stability and the biocompatibility of the colloid. In addition, in vitro tests of antimicrobial activity and cytotoxicity were carried out to estimate the biological activity and the biocompatibility of the colloids. Antimicrobial tests were performed by a drip test on two bacterial strains - Gram-positive Staphylococcus epidermidis and Gram-negative Escherichia coli. AuNP with chitosan proved to possess the highest antibacterial activity, especially towards the Gram-positive S. epidermidis. In vitro tests on eukaryotic cells, i.e. human osteoblastic cell line SAOS-2 and primary normal human dermal fibroblasts (NHDF), were performed after a 7-day cultivation to determine the effect and the toxic dose of the colloids on human cells. The studied colloid concentrations were in the range from 0.6 μg/ml to 6 μg/ml. Toxicity of the colloids started to reappear at a concentration of 4.5 μg/ml, especially with chitosan in the colloid, where the colloid with a concentration of 6 μg/ml proved to be the most toxic, especially towards the SAOS-2 cell line. However, the PEG and PEG-MC containing colloids proved to be relatively non-toxic, even at the highest concentration, but with a slowly decreasing tendency of the cell metabolic activity.