Accuracy and reproducibility of two scales in causality assessment of unexpected hepatotoxicity.

WHAT IS KNOWN AND OBJECTIVE: There is almost no published information about reliability of scales for causality assessment in hepatotoxicity at pharmacovigilance centres. The aim of this study was to compare two commonly used scales in cases of unexpected hepatotoxicity, in evaluating their accuracy and reproducibility at pharmacovigilance centres (in signal detection). METHODS: Two scales [Council for International Organizations of Medical Sciences or Rousel Uclaf Causality Assessment Method (CIOMS/RUCAM) and NARANJO] were compared in 19 cases of unexpected hepatotoxicity reported during 2004-2009. Data of the cases (with initial clinical assessments) were collected by a network of medical specialists using a structured reporting form. Later, two independent observers assessed each case using both scales. The accuracy and reproducibility of the scales were analysed by Kappa weighted (Kw) test. RESULTS: Both scales (CIOMS/RUCAM vs. NARANJO) showed moderate agreement with the initial clinical assessments (accuracy) for observer A (Kw: 0·56 vs. 0·60) and substantial agreement for observer B (Kw: 0·72 vs. 0·70), with high agreement between observers (Kw: 0·84 vs. 0·67). Both observers (A vs. B) found low agreement between scales (Kw: 0·21 vs. 0·50), with lower scores for the CIOMS/RUCAM scale in 11 and nine cases, respectively. For an early perception of unexpected serious reactions, the scale is more useful if it is not asked for 'previous knowledge' and if it gives higher causality score. WHAT IS NEW AND CONCLUSION: The CIOMS/RUCAM scale showed similar accuracy, but better reproducibility (agreement between observers) than the NARANJO scale, and therefore is recommended for use at pharmacovigilance centres. Fine-tuning of the CIOMS/RUCAM method could contribute to better detection of unexpected hepatotoxicity.

The efficacy of selenium, WR-2721, and their combination in the prevention of adriamycin-induced cardiotoxicity in rats.

It is known that the antineoplastic drug adriamycin (ADR) can cause cardiotoxic effects. Some data imply that pretreatment with selenium (Se) and the radio- and chemoprotector, amifostine (WR-2721), may confer a protective effect. The aim of this study was to evaluate the efficacy of single doses of Se and WR-2721, alone or in combination, in the prevention of acute ADR-induced cardiotoxicity in male Wistar rats. Se, in the form of sodium selenite (1.6 mg/kg i.p.), and WR-2721 (300 mg/kg i.p.) were given 24 hours and 20 minutes, respectively, before ADR (6 mg/kg i.v.). The cardiotoxicity of ADR was recorded 48 hours after its administration because earlier studies revealed that structural damage of the myocardium occurs within this period. Evaluation of these toxic effects, as well as of the cardioprotective efficacy of the administered drugs, was performed using (1) ECG-records before and during the infusion of the proarrhythmogenic compound, aconitine (8 microg/kg/min i.v.) and (2) the serum activity of creatine kinase (CK), aspartate aminotransferase-(AST), lactate dehydrogenase (LDH), and its isoenzyme alpha-hydroxybutyrate dehydrogenase (alpha-HBDH). The results showed that the arrhythmogenic dose of aconitine was significantly reduced in ADR-treated rats (57.22 vs. 99.65 microg/kg in control; p < 0.05) and that this proarrhythmogenic compound caused a significant increase in heart rate in such animals compared to controls. Pretreatment with Se, WR-2721, and their combination partly reversed the arrhythmogenic dose of aconitine to control (72.09, 82.1, and 88.99 microg/kg, respectively). Se failed to prevent an aconitine-induced increase in heart rate, whereas WR-2721 and their combination successfully counteracted this effect. In addition, ADR produced a significant increase in the serum activity of all monitored enzymes. Pretreatment with Se failed to prevent this increase, whereas pretreatment with WR-2721 did. The best result was obtained with their combination. We conclude that the radio- and chemoprotector, WR-2721, particularly in combination with Se, may provide a significant protective effect against acute ADR-induced cardiotoxicity in rats.

Influence of a radioprotector WR-638 on the lymphoid compartment of the irradiated rat thymus: a flow cytometric analysis.

The T cell composition of the thymus of X-ray irradiated (3.5 Gy) Wistar rat protected with WR-638 was analyzed by flow cytometry using monoclonal antibodies directed to the Thy 1.1, CD43, CD2, CD5, CD4, CD8 and class I and II MHC antigens. It was shown that this dose of X-rays caused cyclic changes in thymic cellularity manifested as: primary involution (until day 2), primary regeneration (from days 2 to 14), secondary involution (from days 14 to 21) and secondary regeneration (from days 21 to 30). WR-638 reduced the magnitude of thymocyte depletion in the primary involutive phase of the irradiated thymi, primarily as a result of protection of Thy 1.1high+ CD2low+ CD5high+ CD4+ CD8+ class I antigen high+ subpopulations of thymocytes. In the early regenerative phase, WR-638 accelerated the regeneration of CD4-CD8- and CD4-CD8+ thymocyte subsets, followed by subsequent increase of CD4+CD8+ and CD4+CD8- thymocyte subsets. Secondary involutive and regenerative phases in protected animals were characterized by higher absolute cell number of almost all thymocyte subpopulations in comparison with those in irradiated, non-protected animals.

Corticosteroid treatment and X-ray irradiation in adult rats induce the reexpression of fetal markers in cortical thymic epithelial cells.

The phenotype of cortical thymic epithelial cells (TEC) following hydrocortisone-treatment and sublethal X-ray irradiation in adult rats was studied by immunohistochemistry. It was found that during thymic regeneration (2-16 days) a TEC subset, predominantly in the outer cortex, transiently expressed cytokeratin (CK) 19 and an antigen defined by PT13D11 monoclonal antibody (mAb). These markers are characteristic for fetal, but not adult cortical TEC. To examine whether regenerating thymocytes may influence the phenotype of cortical TEC we cultivated a rat cortical TEC line (R-TNC 1.1) with thymocytes isolated from the thymuses at day 7 after hydrocortisone treatment. The R-TNC 1.1 TEC line, although established from adult rat thymus, constitutively expresses PT13D11, but not CK19. The appearance of CK19 in the R-TNC 1.1 cells was not inducible neither by coculture of this line with thymocytes, nor by the influence of IL-1, IL-2, IL-6, TNF-alfa and IFN-gamma. These results demonstrated the phenotypic plasticity of cortical TEC in adult rats.

[Radioprotective and therapeutic modulation of thymus gland regeneration in rats after x-ray irradiation]. / Radioprotektivna i terapijska modulacija regeneracije timusa pacova nakon X-zracenja.

There have been studied effects of cystaphos, gammaphos, hydroxyurea, polyadenyl-polyuridinic acids (poly A:poly U) as well as the combination of gammaphos and poly A:poly U, that is, cystaphos and superoxide dismutase on the thymus of Wistar and AO rats irradiated by the hard X-rays in the dose of 5 or 3.5 Gy. Changes were observed up to 30 days after irradiation. The most efficacious protective effect has shown cystaphos (358 mg/kg i.p. 20 min. after irradiation) in Wistar rats irradiated by the dose of 3.5 Gy. It lowered involutive changes and accelerated thymus regeneration. On the basis of phenotypic analysis of thymocytes it can be supposed that such a favourable effect is the consequence of a larger protection of the cortical (strong OX 7+) thymocytes. Differing from cystaphos, transplantation of the syngeneic cells of the bone marrow in AO rats irradiated by the dose of 5 Gy showed favourable effect on thymus regeneration in later phase after irradiation preventing secondary thymus involution.

Immunohistochemical characterization of rat thymic non-lymphoid cells. II. Macrophages and granulocytes defined by monoclonal antibodies.

A panel of monoclonal antibodies (mAb) raised to antigens of rat thymic non-lymphoid cells (predominantly macrophages and granulocytes) was immunohistochemically characterized. Based on their staining patterns on cryostat thymic sections and double labellings using acid phosphatase activity, anti-cytokeratin mAb to exclude binding to epithelium or ED1 and ED2 mAb, specific for rat macrophages, antibodies were subdivided into four groups: (i) R-MC 39 mAb strongly reactive with macrophages in the cortex and cortico-medullary zone (CMZ) and weakly with some scattered macrophages in the medulla, blood vessels and thymocytes; (ii) R-MC 40, 41 and 42 mAb specific for cortical macrophages and most CMZ macrophages; (iii) R-MC 43 and 44 mAb predominantly recognizing CMZ and medullary macrophages; (iv) R-MC 45 mAb strongly labelling granulocytes and weakly a subset of macrophages throughout the thymus and isolated cells in the medulla. The obtained results show considerable heterogeneity within mobile thymic non-lymphoid cells and the presence of specific or common antigens in macrophages of particular topographic localization in the rat thymus.

Interspecies differences in expression of cytokeratin polypeptides within thymic epithelium: a comparative immunohistochemical study.

Cytokeratin (CK) polypeptide expression within the thymic epithelium of several mammalian species (mouse, rat, calf, pig, rabbit, and human) has been analyzed by the streptavidin-biotin immunoperoxidase method. Comparative analysis by a large panel of 17 monoclonal antibodies (mAbs) specific for individual CK polypeptides, pairs, or groups showed considerable heterogeneity of thymic epithelial cells (TEC) in each species. In addition, extreme interspecies difference in CK contents was observed. Four main phenotypic zones: the subcapsule/perivascular area, cortex, medulla, and Hassall's corpuscles (HC) were clearly identified, each characterized by different CK expression. Medullary TEC were more heterogenous and shared common CK polypeptides either with subcapsular/perivascular TEC, cortical TEC, or HC, in most species.