Toxic and essential metal concentrations in four tissues of red deer ( Cervus elaphus ) from Baranja,Croatia

Kidney (n =?297), liver (n =?52), jawbone (n =?80) and muscle (n =?48) samples collected from red deer (Cervus elaphus) from north-eastern Croatia in the 2002–05 hunting season were analysed for cadmium (Cd), copper (Cu), iron (Fe), mercury (Hg), lead (Pb), selenium (Se) and zinc (Zn) using atomic absorption spectrometry. Statistical evaluation of results showed age-related accumulations of renal cortex Cd and Zn, bone Pb, and muscle Zn. Renal cortex Cd and Zn were significantly associated. In addition, concentrations of Cd and Pb in muscle tissue were significantly correlated with Fe content. Found levels of toxic metals were not likely to affect the health status of animals. A total of 49% of the muscle, 60% of the kidney and 6% of the liver samples were unsuitable for human consumption according to Croatian regulations for Cd in food. However, the calculated intake of Cd through deer meat consumption is small and represents no health risk when consumption is moderate.     

The dynamics of mercury and cadmium uptake into different organs of Anodonta cygnea L.

The bioaccumulation of Hg and Cd into various organs of the freshwater mussel Anodonta cygnea was investigated during an 840 h experimental period. Parallel with the metal concentrations the periodicity of activity and the body weight of the animals were also checked.The accumulation of Hg in all of the investigated organs, and that of the Cd into the kidney have two phases, up to 24 h it was non linear, between 24 and 72 h it became linear in most organs up to 840 h, and could be characterized by a regression line. For Hg accumulation the gills while for Cd accumulation the kidney and viscera were exceptions, here saturation was observed after 504 and 672 h, respectively.The speed of Hg and Cd uptake was different in various organs of Anodonta cygnea. Into the kidney the accumulation of Hg was six times faster than that of Cd. As compared to the adductor muscles the Hg and Cd uptake of the kidney was 20 and 10 times faster, respectively.The factor of concentration was in all organs except adductor muscles over 1000, in case of the kidney the rate of bioconcentration for Hg reached nearly 100,000.The dry weight of organs dropped during the metal uptake by 20–60%, but no mortality was observed up to 840 h.In the presence of Hg and Cd the filtering activity of the mussels became reduced as a result of increase of inactive rest periods. Nevertheless, the decrease of activity did not prevent the linear uptake of metals into the animal     

Long-term patency of arteriovenous fistulas for hemodialysis: A decade's experience in a transplant unit

Background

The heterogeneous quality of studies on arteriovenous fistulas outcome, with variable clinical settings and large variations in definitions of patency and failure rates, leads to frequent misinterpretations and overestimation of arteriovenous fistula patency. Hence, this study aimed to provide realistic and clinically relevant long-term arteriovenous fistula outcomes.

Methods

We retrospectively analyzed all autologous arteriovenous fistulas at our center over a 10-year period (2012–2022). Primary and secondary patency analysis was conducted using the Kaplan–Meier method; multivariate analysis of variance was used to detect outcome predictors. Vascular access-specific endpoints were defined according to the European guidelines on vascular access formation.

Findings

Of 312 arteriovenous fistulas, 57.5% (n = 181) were radio-cephalic (RC_AVF), 35.2% (n = 111) brachio-cephalic (BC_AVF), and 6.3% (n = 20) brachio-basilic (BB_AVF). 6, 12, and 24 months follow-up was available in 290 (92.1%), 282 (89.5%), and 259 (82.2%) patients, respectively. Primary patency rates at 6, 12, and 24 months were 39.5%, 34.8%, and 27.2% for RC_AVF, 58.3%, 44.4%, and 27.8% for BC_AVF, and 40.0%, 42.1%, and 22.2% for BB_AVF (p = 0.15). Secondary patency rates at 6, 12, and 24 months were 65.7%, 63.8%, and 59.0% for RC_AVF, 77.7%, 72.0%, and 59.6% for BC_AVF, and 65.0%, 68.4%, and 61.1% for BB_AVF (p = 0.29). Factors associated with lower primary and secondary patency were hemodialysis at time of arteriovenous fistula formation (p = 0.037 and p = 0.024, respectively) and higher Charlson Comorbidity Index (p = 0.036 and p < 0.001, respectively). Previous kidney transplant showed inferior primary patency (p = 0.005); higher age inferior secondary patency (p < 0.001).

Discussion

Vascular access care remains challenging and salvage interventions are often needed to achieve maturation or maintain patency. Strict adherence to standardized outcome reporting in vascular access surgery paints a more realistic picture of arteriovenous fistula patency and enables reliable intercenter comparison.     

Atmospheric scanning electron microscopy and its applications for biological specimens

Scanning electron microscopy in ambient conditions (Air‐SEM) was developed recently and has been used mainly for industrial applications. We assessed the potential application of Air‐SEM for the analysis of biological tissues by using rat brain, kidney, human tooth, and bone. Hard tissues prepared by grinding and frozen sections were observed. Basic cytoarchitecture of bone and tooth was identified in the without heavy metal staining. Kidney tissue prepared using routine SEM methodology yielded images comparable to those of field emission (FE)‐SEM. Sharpness was lower than that of FE‐SEM, but foot process of podocytes was observed at high magnification. Air‐SEM observation of semithin sections of kidney samples revealed glomerular basement membrane and podocyte processes, as seen using conventional SEM. Neuronal structures of soma, dendrites, axons, and synapses were clearly observed by Air‐SEM with STEM detector and were comparable to conventional transmission electron microscopy images. Correlative light and electron microscopy observation of zebrafish embryos based on fluorescence microscopy and Air‐SEM indicated the potential for a correlative approach. However, the image quality should be improved before becoming routine use in biomedical research.     

Indoxyl sulfate‐induced calcification of vascular smooth muscle cells via the PI3K/Akt/NF‐κB signaling pathway

Vascular calcification (VC) is highly prevalent in patients with chronic kidney disease (CKD) and contributes to their high rate of cardiovascular mortality. Indoxyl sulfate (IS) is a representative protein‐bound uremic toxin in CKD patients, which has been recognized as a major risk factor for VC. Recent studies have demonstrated that nuclear factor‐kappa B (NK‐κB) is highly activated in the chronic inflammation conditions of CKD patients and participated in the pathogenesis of VC. However, whether NK‐κB is involved in the progression of IS‐induced VC remains without elucidation. Here, we showed that NK‐κB activity was increased in the IS‐induced calcification of human aortic smooth muscle cells (HASMCs). Blocking the NK‐κB with a selective inhibitor (Bay‐11‐7082) significantly relieved the osteogenic transdifferentiation of HASMCs, characterized by the downregulation of early osteogenic‐specific marker, core‐binding factor alpha subunit 1 (Cbfα1), and upregulation of smooth muscle α‐actin (α‐SMA), a specific vascular smooth muscle cell marker. Besides, IS stimulated the activation of PI3K/Akt signaling. Furthermore, LY294002, a specific inhibitor of PI3K/Akt pathway, attenuated the activation of NK‐κB and osteogenic differentiation of HASMCs. Together, these results suggest that PI3K/Akt/NK‐κB signaling plays an important role in the pathogenesis of osteogenic transdifferentiation induced by IS.