[Investigation of the effect of titanium dioxide nanorods on the lungs in a subacute rat model]

INTRODUCTION

The development of nanotechnology increases the risk of occupational and population-level exposure to nanoparticles nowadays. However, scientifically based knowledge relating to the toxicity of heavy metal nanoparticles and potential health damage is insufficient.

AIM

Investigation of lung tissue damage induced by titanium dioxide (TiO₂) nanorods in subacute intratracheal instillation by morphological, chemical and biochemical methods in rat model.

METHOD

General toxicity (changes of body and organ weights), local acute and chronic cellular toxicity (in alveolar spaces and epithelium, in hilar lymph nodes) and oxidative stress were examined using light and electron microscopy, and biochemical methods (reactive oxygen species, lipid peroxidation, expression of pro-inflammatory cytokines).

RESULTS

No dose- and time-dependent alteration was found in the body weight of the treated groups; but the mass and Ti content of lungs increased with dose. Light and electron microscopy of the lung tissue verified the presence of nanoparticles, free in the alveolar space and within phagosomes of macrophages not attached to alveolar epithelium. Chronification of local acute alveolitis was supported by dose-dependent increase of macrophage count in the alveolar region, oedema and thickening of interstitium, and increased expression of certain pro-inflammatory cytokines (interleukin-1a, LIX, L-selectin, vascular endothelial growth factor). Oxidative stress and lipid peroxidation increased substantially in the treated rats' lungs, and correlation was found between Ti content and lipid peroxidation. Insufficiency of the alveolar epithelial and capillary endothelial barrier was indicated by nanoparticle-laden phagocytes in hilar lymph nodes, suggesting nanoparticles reaching systemic circulation and distant organs, inducing systemic acute inflammation.

CONCLUSION

TiO₂ nanoparticles, reaching lower airways, may be etiological factors in the causation or aggravation of pulmonary diseases with acute and chronic airways inflammation and/or progressive fibrosis and obstruction (e.g., chronic obstructive pulmonary disease or asthma). Autophagy and damaged immune response (lymphocytic activity) may have here a role. Orv Hetil. 2019; 160(2): 57-66.

[Liver bud transplantation in rats]

INTRODUCTION

Research has made progress in organ fabrication using an extracellular matrix, cell sheets, or organoids. Human liver tissue has been constructed using a 3-dimensional (3D) bioprinter and showed evidence that an in vitro generated liver bud was reformed in a rodent liver model. This study describes the stages of development of rat fetal organs and liver structure and reviews recent progress in liver organoid transplantation.

METHODS

The authors developed the procedures for creating a transected plane for use in experimental microsurgery in rats. A liver lobe was fixed vertically with gauze and it was ligated with 6-0 silk suture in the cut line; the parenchyma was cut, and major vessels were ligated to create the transected plane. The ligated tissue was carefully resected. Hemostasis was not required and hepatic components remained on the transected plane. The plane was covered by omentum.

RESULTS

Using this model, we transplanted fetal liver or a 3D bioprinted liver organoid. This microsurgical method enabled creation of an intact liver parenchyma plane. No bleeding was observed. The transplanted liver components successfully engrafted on the liver.

CONCLUSION

This method may provide an essential environment for growing liver using portal and arterial blood flow.

[Examination of liver mitochondria with respirometry]

Due to their diverse physiological functions, mitochondria can cause various acute and chronic liver diseases, thus being potential targets for therapies and diagnostics as well. In this study, the advantages of high-resolution respirometry are presented for the assessment of liver mitochondrial functions. During respitometry, the mitochondrial electron transport, the oxydative phosphorilation and the efficacy of the ADP synthesis can be calculated on the basis of oxygen consumption of freshly-taken tissue samples. Respirometry is a robust tool for the pre- or intraoperative analysis of liver mitochondrial functions and may increase the effectiveness of surgical interventions.

[Regulation of vasomotor tone of small skeletal muscle veins by intrinsic mechanisms]

In many developed countries the prevalence of venous disorders and its consequences are higher than that of arterial diseases. Thus it is very important to understand the exact physiological and pathophysiological function of small veins and their control mechanisms. Small veins and venules have an important role in the regulation of capillary fluid exchange, as well as return of the venous blood into the heart. However, there is only limited knowledge available regarding the role of local mechanisms controlling the vasomotor tone and diameter of small veins. In the last decade the authors focused on the elucidation of these mechanisms in isolated skeletal muscle venules of rats. Their results suggest that the tone of small veins is controlled by the integration of several mechanisms, activated by the intraluminal pressure and flow/wall shear stress, in addition to numerous local mediators synthesized and released from the smooth muscle and endothelium. These mechanisms are involved - in a complex manner - in the control of postcapillary resistance, thus regulation of tissue blood supply, venous return and consequently in the modulation of the cardiac output, as well.