Toxicity of hexachlorobenzene in Meriones unguiculatus: effects on thyroid and liver

The effect of in vivo administered hexachlorobenzene (HCB) on liver and thyroid was studied on Meriones unguiculatus. HCB (1.6, 4, and 16 mg/kg of body weight) has been administered orally to meriones for 30 days. At the end of the experiment, the body weight of the animals did not show significant change. However, the higher dose of HCB treatment led to a pronounced hepatic hypertrophy comparatively to controls. Histological observations revealed many cytomorphological alterations. Cellular necrosis, periportal, and centrolobular vein congestion and cytoplasmic vacuolisation were noted and correlated with the administered doses of HCB. The higher dose of HCB induced modifications in the activities of hepatic transaminases and on thyroid hormones levels: ALAT activity level was more pronounced in males (170+/-24.7 U/l vs. 52.66+/-8.29 U/l in controls) than in females (120+/-12.47 U/l vs. 56+/-5 U/l in controls). However, ASAT activity increased significantly only in females (259+/-29 U/l vs. 244.66+/-18 U/l in controls). Plasma total triiodothyronine (TT3) and total thyroxine (TT4) levels seemed to be sex-dependent in intoxicated animals, since TT4 decreased significantly in males (21.95+/-7.46 nmol/l vs. 40.59+/-1.08 nmol/l in controls) and TT3 in females (1.42+/-0.11 nmol/l vs. 3.96+/-0.48 nmol/l in controls).     

Role of PAR2 in murine pulmonary pseudomonal infection

Proteinases can influence lung inflammation by various mechanisms, including via cleavage and activation of protease-activated receptors (PAR) such as PAR2. In addition, proteinases such as neutrophil and/or Pseudomonas-derived elastase can disarm PAR2 resulting in loss of PAR2 signaling. Currently, the role of PAR2 in host defense against bacterial infection is not known. Using a murine model of acute Pseudomonas aeruginosa pneumonia, we examined differences in the pulmonary inflammatory response between wild-type and PAR2(-/-) mice. Compared with wild-type mice, PAR2(-/-) mice displayed more severe lung inflammation and injury in response to P. aeruginosa infection as indicated by higher bronchoalveolar lavage fluid neutrophil numbers, protein concentration, and TNF-alpha levels. By contrast, IFN-gamma levels were markedly reduced in PAR2(-/-) compared with wild-type mice. Importantly, clearance of P. aeruginosa was diminished in PAR2(-/-) mice. In vitro testing revealed that PAR2(-/-) neutrophils killed significantly less bacteria than wild-type murine neutrophils. Further, both neutrophils and macrophages from PAR2(-/-) mice displayed significantly reduced phagocytic efficiency compared with wild-type phagocytes. Stimulation of PAR2 on macrophages using a PAR2-activating peptide resulted in enhanced phagocytosis directly implicating PAR2 signaling in the phagocytic process. We conclude that genetic deletion of PAR2 is associated with decreased clearance of P. aeruginosa. Our data suggest that a deficiency in IFN-gamma production and impaired bacterial phagocytosis are two potential mechanisms responsible for this defect.     

Protective effects of taxifolin on pazopanib-induced liver toxicity: an experimental rat model

Pazopanib is a tyrosine kinase inhibitor that is generally used for the treatment of metastatic renal cell cancer and advanced soft tissue sarcoma. It can cause various degrees of hepatotoxicity. Our study aimed to investigate the effect of taxifolin on pazopanib-induced liver toxicity. A total of 18 rats were divided into three groups: the pazopanib (PP), pazopanib plus taxifolin (TPP), and control (C) group. Taxifolin was administered to the TPP (n=6) group with a dose of 50 mg/kg. Distilled water was orally admnistered to the C (n=6) and PP (n=6) groups as a solvent. Subsequently, pazopanib 200 mg/kg was administered to the TPP and PP groups via the stomach. This procedure was repeated once a day for four weeks. Then, all rats were sacrificed, and their livers were removed. Malondialdehyde (MDA), total glutathione (tGSH), total oxidant status (TOS), and total antioxidant status (TAS) levels were evaluated. MDA and TOS levels were higher in the PP group compared with the levels of the other parameters (P<0.001). tGSH and TAS levels were lower in the PP group than in the TPP and C groups (P<0.001), and the aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) levels were higher. Furthermore, liver tissue damage, including hemorrhage, hydropic degeneration, and necrosis was observed in the PP group. Administration of taxifolin before pazopanib significantly improved degenerative changes. Our study demonstrated that the administration of taxifolin is significantly effective in preventing pazopanib-induced hepatotoxicity in rats.     

Blockade of mGluR5 reverses abnormal firing of subthalamic nucleus neurons in 6-hydroxydopamine partially lesioned rats

Activation of metabotropic glutamate receptor 5 (mGluRs) in the subthalamic nucleus (STN) results in burst-firing activity of STN neurons, which is similar to that observed in Parkinson's disease (PD). We examined the effects of chronic and systemic treatment with 2-methyl-6-(phenylethynyl)-pyridine (MPEP), a selective mGluR5 antagonist, in firing activity of STN neurons in partially lesioned rats by 6-hydroxydopamine (6-OHDA). In 6-OHDA-lesioned rats treated with vehicle, injection of 6-OHDA (4 microg) into the medial forebrain bundle produced a partial lesion causing 36% loss of tyrosine hydroxylase-immunoreactive (TH-ir) neurons in the substantia nigra pars compacta (SNpc). The 6-OHDA lesion in vehicle-treated rats showed an increasing firing rate and a more irregular firing pattern of STN neurons. Whereas chronic, systemic treatment of MPEP (3 mg/kg/day, 14 days) produced neuroprotecive effects on the TH-ir neurons and normalized the hyperactive firing activity of STN neurons in 6-OHDA partially lesioned rats. These data demonstrate that partial lesion of the nigrostriatal pathway increases firing activity of STN neurons in the rat, and chronic, systemic MPEP treatment has the neuroprotective effect and reverses the abnormal firing activity of STN neurons, suggesting that MPEP has an important implication for the treatment of PD.     

Intercostal variation for age estimation--are the standards for the right 4th rib applicable for other ribs?

Age estimation of unknown skeletal remains is very important in forensic medicine. Morphologic methods are fast and easy to use for purpose of age determination. The sternal ends of the ribs are a reliable method of age estimation from late adolescence to old age. Iscan et al developed a phase analysis method for the right 4th rib that was sex and race specific. The purpose of this study is to determine the accuracy of the standards of age estimation from the right 4th and other rib using the phase analysis for the Turkish population. The sample consisted of right and left 3rd, 4th and 5th ribs from 34 Turkish women and 76 men. There were statistically significant variations found on the right 5th, left 3rd, 4th, and 5th ribs according to these standards in men for phases 5, 6, and 7. For women, all the right and left ribs included in this study were in concordance with right 4th rib standards in all phases.     

W323S variant of Xiap-Bir3 binds to SMAC but not caspase-9

The ability of the wild-type XIAP BIR3 domain as well as its Trp323Ser variant in inhibition of human caspase-9, binding to AVPFVASLPN (SMAC-peptide), SMAC protein, and mature caspase-9 was investigated. In order to investigate the role of W323 on these interactions, this residue was mutated to Serine. Circular dichroism as well as thermal denaturation studies showed that W323S mutation did not hamper proper folding of the protein. The dissociation constants for the interaction of the wild type BIR3 as well as its mutant to Smac-type peptide were found to be 1.8 and 27 muM, respectively. The inhibition of and binding to caspase-9 by wild-type BIR3 and its mutant were also compared. While the wild-type protein potently inhibited the enzyme, the mutant failed to do so. The lack of caspase-9 inhibition was due to absence of interaction of the mutant BIR3 with mature caspase-9. These results indicate that Trp323 of BIR3 plays a pivotal role both in maintaining necessary conformation for caspase-9 interaction and to a lesser extent, recognition of Smac-type peptide. Moreover, decreased stability of the mutant compared with the wild type indicates that W323 is essential for maintaining the stability BIR3-Smac-peptide complex.     

mtDNA and Y-chromosome variation in the Talysh of Iran and Azerbaijan

The Northern Talysh from Azerbaijan and the Southern Talysh from Iran self‐identify as one ethnic group and speak a Northwestern Iranian language. However, the Northern and Southern Talysh dialects are so different that they may actually be separate languages. Does this linguistic differentiation reflect internal change due to isolation, or could contact‐induced change have played a role? We analyzed mtDNA HVI sequences, 11 Y‐chromosome bi‐allelic markers, and 9 Y‐STR loci in Northern and Southern Talysh and compared them with their neighboring groups. The mtDNA data show a close relatedness of both groups with each other and with neighboring groups, whereas the Northern Talysh Y‐chromosome variation differs from that of neighboring groups, probably as a result of genetic drift. This genetic drift most likely reflects a founder event in the male gene pool of Northern Talysh: either fewer males than females migrated to Azerbaijan, or there was a higher degree of relatedness among the male migrants. Since we find no evidence of substantial genetic contact between either Northern or Southern Talysh and neighboring groups, we conclude that internal change, rather than contact‐induced change, most likely explains the linguistic differentiation between Northern and Southern Talysh. Am J Phys Anthropol, 2009. © 2008 Wiley‐Liss, Inc.     

Proximal tubule haptoglobin gene activation is an integral component of the acute kidney injury "stress response"

Haptoglobin (Hp) synthesis occurs almost exclusively in liver, and it is rapidly upregulated in response to stress. Because many of the pathways that initiate hepatic Hp synthesis are also operative during acute kidney injury (AKI), we tested whether AKI activates the renal cortical Hp gene. CD-1 mice were subjected to six diverse AKI models: ischemia-reperfusion, glycerol injection, cisplatin nephrotoxicity, myoglobinuria, endotoxemia, and bilateral ureteral obstruction. Renal cortical Hp gene induction was determined either 4-72 h or 1-3 wk later by measuring Hp mRNA and protein levels. Relative renal vs. hepatic Hp gene induction during endotoxemia was also assessed. Each form of AKI induced striking and sustained Hp mRNA increases, leading to ～10- to 100-fold renal Hp protein elevations (ELISA; Western blot). Immunohistochemistry, and isolated proximal tubule assessments, indicated that the proximal tubule was the dominant (if not only) site of the renal Hp increases. Corresponding urinary and plasma Hp elevations were surrogate markers of this response. Endotoxemia evoked 25-fold greater Hp mRNA increases in kidney vs. liver, indicating marked renal Hp gene reactivity. Clinical relevance of these findings was suggested by observations that urine samples from 16 patients with established AKI had statistically higher (～12×) urinary Hp levels than urine samples from either normal subjects or from 15 patients with chronic kidney disease. These AKI-associated urinary Hp increases mirrored those seen for urinary neutrophil gelatinase-associated lipoprotein, a well accepted AKI biomarker gene. In summary, these studies provide the first evidence that AKI evokes rapid, marked, and sustained induction of the proximal tubule Hp gene. Hp's known antioxidant, as well as its protean pro- and anti-inflammatory, actions imply potentially diverse effects on the evolution of acute tubular injury.     

Cadherin-directed actin assembly: E-cadherin physically associates with the Arp2/3 complex to direct actin assembly in nascent adhesive contacts

Cadherin cell adhesion molecules are major determinants of tissue patterning which function in cooperation with the actin cytoskeleton. In the context of stable adhesion, cadherin/catenin complexes are often envisaged to passively scaffold onto cortical actin filaments. However, cadherins also form dynamic adhesive contacts during wound healing and morphogenesis. Here actin polymerization has been proposed to drive cell surfaces together, although F-actin reorganization also occurs as cell contacts mature. The interaction between cadherins and actin is therefore likely to depend on the functional state of adhesion. We sought to analyze the relationship between cadherin homophilic binding and cytoskeletal activity during early cadherin adhesive contacts. Dissecting the specific effect of cadherin ligation alone on actin regulation is difficult in native cell-cell contacts, due to the range of juxtacrine signals that can arise when two cell surfaces adhere. We therefore activated homophilic ligation using a specific functional recombinant protein. We report the first evidence that E-cadherin associates with the Arp2/3 complex actin nucleator and demonstrate that cadherin binding can exert an active, instructive influence on cells to mark sites for actin assembly at the cell surface.     

Structural and Functional Characterization of the Redβ Recombinase from Bacteriophage λ

The Red system of bacteriophage λ is responsible for the genetic rearrangements that contribute to its rapid evolution and has been successfully harnessed as a research tool for genome manipulation. The key recombination component is Redβ, a ring-shaped protein that facilitates annealing of complementary DNA strands. Redβ shares functional similarities with the human Rad52 single-stranded DNA (ssDNA) annealing protein although their evolutionary relatedness is not well established. Alignment of Rad52 and Redβ sequences shows an overall low level of homology, with 15% identity in the N-terminal core domains as well as important similarities with the Rad52 homolog Sak from phage ul36. Key conserved residues were chosen for mutagenesis and their impact on oligomer formation, ssDNA binding and annealing was probed. Two conserved regions were identified as sites important for binding ssDNA; a surface basic cluster and an intersubunit hydrophobic patch, consistent with findings for Rad52. Surprisingly, mutation of Redβ residues in the basic cluster that in Rad52 are involved in ssDNA binding disrupted both oligomer formation and ssDNA binding. Mutations in the equivalent of the intersubunit hydrophobic patch in Rad52 did not affect Redβ oligomerization but did impair DNA binding and annealing. We also identified a single amino acid substitution which had little effect on oligomerization and DNA binding but which inhibited DNA annealing, indicating that these two functions of Redβ can be separated. Taken together, the results provide fresh insights into the structural basis for Redβ function and the important role of quaternary structure.