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Local differences in structural properties of biological specimens pose a major limitation to quantitative X-ray fluorescence imaging. This is because both the various tissue compartments of different density and variation in the sample thickness upon frequently used freeze-drying come up with the different values of the sample mass per unit area to be taken into account. Even though several solutions to tackle this problem based on the home-made standards for quantification in terms of thickness- and density-independent elemental mass fractions have been proposed, this issue is not addressed enough due to the samples' heterogeneity. In our recent study, we propose a calculation scheme based on combined external-standard micro X-ray fluorescence (micro-XRF) imaging and internal-standard total reflection X-ray fluorescence (TXRF) analysis to determine the corrected elemental mass fraction distributions in commonly analysed rat tissues: kidney, liver and spleen. The results of TXRF analysis of digested large tissue sections together with the mean values of elemental masses per unit area obtained with micro-XRF were employed to determine the average masses per unit area of the samples. The correction for variation of the tissue thickness and density was done through with the use of Compton intensities. Importantly, by its versatility, our novel approach can be used to produce elemental contrast in a variety of biological specimens where local variations in either the sample density or thickness are no longer the issue., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Most studies have focused on the biodistribution of titanium(IV) oxide as nanoparticles or crystals in organism. But several reports suggested that titanium is released from implant in ionic form. Therefore, gaining insight into toxicokinetics of Ti ions will give valuable information, which may be useful when assessing the health risks of long-term exposure to titanium alloy implants in patients. A micro synchrotron radiation-induced X-ray fluorescence (µ-SRXRF) was utilized to investigate the titanium distribution in the liver, spleen and kidneys of rats following single intravenous or 30-days oral administration of metal (6 mg Ti/b.w.) in ionic form. Titanium was mainly retained in kidneys after both intravenous and oral dosing, and also its compartmentalization in this organ was observed. Titanium in the liver was non-uniformly distributed-metal accumulated in single aggregates, and some of them were also enriched in calcium. Correlation analysis showed that metal did not displace essential elements, and in liver titanium strongly correlated with calcium. Two-dimensional maps of Ti distribution show that the location of the element is characteristic for the route of administration and time of exposure. We demonstrated that µ-SRXRF can provide information on the distribution of titanium in internal structures of whole organs, which helps in enhancing our understanding of the mechanism of ionic titanium accumulation in the body. This is significant due to the popularity of titanium implants and the potential release of metal ions from them to the organism.

Background: Previous results proved that simultaneous effect of tobacco smoke constituents and alcohol consumption may change toxicity of these substances and have a greater effect on hepatic and pancreatic disease and cancer risk. The aim of this study was to investigate hepatocyte and pancreatic cells regeneration after tobacco and/or ethanol treatment., Methods: In the study, four groups of rats were used - alcohol non-addicted and addicted male and female rats. The animals from each group were exposed to tobacco smoke, to ethanol or tobacco smoke and ethanol. After the exposure, pancreas and liver were collected at two time-points--5 and 24 h. Biochemical methods were used to measure concentration of ethanol and cotinine in blood and plasma. Additionally, proliferating cell nuclear antigen labeling index (PCNA-LI), an S-phase marker was assessed by immunohistochemical staining and morphometric method., Results: Our experimental results showed that the exposure of rats to tobacco smoke does not have influence on ethanol concentration in blood of non-addicted (male, female) and addicted (male and female) animals. The results also proved that alcohol addiction did not influence nicotine metabolism in all animals exposed to tobacco smoke. Morphological studies of tissues display significant damage in liver of addicted males, including fatty degradation, fibrosis and slight inflammatory infiltrate. Immunohistochemical studies revealed at first, significant increase of PCNA-LI and, thus, increased cell proliferation activity and damage in tissues were observed in hepatic and pancreatic cells of addicted males when compared with non-addicted males. Secondly, comparison between addicted males and addicted females revealed that PCNA-LI in females is significantly lower, both in hepatic and pancreatic tissues. And finally, animals exposed only to ethanol and to tobacco smoke plus ethanol were characterized by higher percentage of PCNA positive cells in relation to animals exposed only to tobacco smoke., Conclusion: From the preliminary study one can conclude that the influence of ethanol and simultaneous influence of ethanol and tobacco smoke impairs liver and pancreatic functions to a greater degree than tobacco abuse.

Diabetes is considered a group of diseases with chronic hyperglycemia caused by various organ disorders, failure or damage as a common feature. Hyperglycemia exerts toxic effect on endothelium, promotes oxidative stress, inhibits bioavailability of nitrogen monoxide (NO) and leads to formation of advanced glycation end products. Moreover, hyperglycemia induces production of reactive oxygen specimens (ROS) through several distinct mechanisms, such as: glucose autoxydation activation of polyol (sorbitol-aldose reductase) pathway, non-enzymatic glycation and neutrophil granulocyte's stimulation. These changes lead to uncontrolled oxidation and peroxidation of lipids, nucleic acids, certain enzymes and most of all--oxidative protein damage (OPD) in many tissues. The aim of this study was to evaluate influence of exposure to tobacco smoke on lipid peroxidation and liver function in experimentally induced diabetes. The research showed that the protein level in blood serum did not change neither in case of induced diabetes nor after tobacco smoke exposure. However a statistically significant increase of lipid peroxidation was observed in rats with pharmacologically induced diabetes. In animals exposed to tobacco smoke only lipid peroxidation increasing trend was demonstrated, while in animals with induced diabetes and exposed to tobacco smoke a statistically significant decrease of lipid peroxidation was noticed. In the adopted experimental model basically no alterations of hepatic aminotranspherases were observed, with exception of AIAT in the group of diabetic animals compared to rats in the control group. Results of the study do not explicitly explain the influence of tobacco smoking in experimentally induced diabetes on lipid peroxidation and liver functions.

Tacrolimus is an immunosuppressive agent used for organ transplantation. Studies were performed to examine the influence of different perfusate hematocrits and albumin concentrations on hepatic extraction of tacrolimus. In vitro binding, efflux and influx between red blood cells (RBCs) and buffer or plasma, and rabbit liver perfusion with use of human erythrocytes were studied. In the range of hematocrits from 0.05 to 0.4, plasma concentrations of tacrolimus were not affected by increased albumin content. Increased hematocrit caused decreases in whole blood:plasma (buffer) concentration ratios. The binding capacity of drug with RBCs was independent of hematocrit, with a value of 440 ng/ml of RBCs; the binding affinity was 0.876 ng/ml using plasma or buffer. Diffusion of tacrolimus from RBCs to buffer was rapid with a clearance of 0.940 ml/min, and equilibration was achieved within 2 min. Diffusion in the opposite direction (buffer-RBCs) was slower with a clearance of 0.576 ml/min. In such diffusion studies, plasma produced a greater difference between efflux (1.70 ml/min) and influx (0.276 ml/min) clearances. During liver perfusion, the major factor regulating elimination of tacrolimus was hematocrit. Both well-stirred and parallel-tube models reflected a low extraction ratio drug with values of 0.15 and 0.17 for the 0.05 and 0.2 hematocrits. Intrinsic clearances were 8.43 and 17.44 ml/min for the well-stirred and parallel-tube models. Albumin had a negligible influence on liver extraction of drug. A model-building process of characterizing nonlinear RBC binding, RBC diffusion rates, and liver perfusion parameters allows the complexities of tacrolimus hepatic clearance to be dissected and shows that strong RBC binding can be artificially perceived as causing a high clearance of the drug.

Tacrolimus is a macrolide immunosuppressive drug undergoing clinical trials for organ transplantation. Whole animal studies were undertaken to assess the rabbit as an animal model for tacrolimus pharmacokinetics. The disposition of tacrolimus in rabbits following 0.5 mg/kg iv and 2.0 mg/kg po doses is similar to man. The apparent plasma clearance 1.67 liters/hr/kg is more than 5-fold higher than blood clearance 0.31 liters/hr/kg. The steady-state volume of distribution is 30.7 liters/kg for plasma and 6.3 liters/kg for whole blood. The bioavailability after oral administration calculated from plasma and whole blood is low with a mean value of 9.7%. The in vitro studies and fitting using a nonlinear red blood cell (RBC)-plasma binding/diffusion model showed slow diffusion of drug from RBC to plasma (t1/2 = 7 min, CLD = 0.085 ml/min). In perfused liver studies, the extraction ratio of tacrolimus from blood with hematocrit of 0.1 is low (0.20). However, extraction of drug from plasma is moderate (0.42), and plasma concentrations are elevated by an average of 28% because of redistribution of tacrolimus from RBC. This creates a lower apparent plasma clearance (DO/AUC) for equilibrated (30 min at 37 degrees C) samples (15.4 ml/min) compared with samples centrifuged within 5 min (22.1 ml/min). RBC efflux was accounted for using a comprehensive perfusion/diffusion model. The intrinsic metabolic clearance averaged 29.2 ml/min. Simulations showed that the apparent plasma clearance of tacrolimus is closely correlated with RBC binding capacity (whole blood:plasma ratio). Higher ratios caused greater apparent plasma clearance (lower concentration of tacrolimus in reservoir plasma) because strong binding of drug by erythrocytes prevents tacrolimus from diffusion into plasma.(ABSTRACT TRUNCATED AT 250 WORDS)

In the present study we have examined the effect of treatment with benz(a)-anthracene (BaA), pyrene (P) and fluoranthene (Fl) on the total liver microsomal content of cytochrome P-450 and elimination of these PAH from blood in rats. The experiment was carried out on adult male rats Wistar breed. Oil solution of inducers: benz(a)anthracene, pyrene and fluoranthene in dose 20 mg/kg were administered individually one or threefold by gavage. 24 h after a single dose of PAH cytochrome P-450 content in rat liver determined by the method of Omura and Sato was the same as in control group. When PAH were administered p.o. for three consecutive days in the fourth day of experiment cytochrome P-450 content was increased from about 0.68 nM/mg protein to about 1.2 nM/mg. Since the increase of cytochrome P-450 may influence on elimination of xenobiotics we have determined affect PAH on their blood level after i.v. administration. One hour after BaA administration and two hours after Fl and P blood samples were collected. Concentration of PAH in blood was determined by gas-liquid chromatography. Pretreatment of rats with BaA decreased elimination of Fl, P, BaA from blood in comparison to the control rats. It indicated on the self-inducing effect of BaA on its own metabolism and inducing effect of metabolism other PAH. Pretreatment of rats with pyrene decreased elimination of BaA. It seemed that pyrene inhibited the oxidation of BaA in rat liver microsomes.