Trypanosoma evansi: Adenosine deaminase activity in the brain of infected rats

The study was undertaken to evaluate changes in the activity of adenosine deaminase (ADA) in brains of rats infected by Trypanosoma evansi. Each rat was intraperitoneally infected with 10⁶ trypomastigotes either suspended in fresh (group A; n = 13) and cryopreserved blood (group B; n = 13). Thirteen animals were used as control (group C). ADA activity was estimated in the cerebellum, cerebral cortex, striatum and hippocampus. No differences (P > 0.05) in ADA activity were observed in the cerebellum between infected and non-infected animals. Significant (P < 0.05) reductions in ADA activity occurred in cerebral cortex in acutely (day 4 post-infection; PI) and chronically (day 20 PI) infected rats. ADA activity was significantly (P < 0.05) decreased in the hippocampus in acutely infected rats, but significantly (P < 0.05) increased in the chronically infected rats. Significant (P < 0.05) reductions in ADA activity occurred in the striatum of chronically infected rats. Parasites could be found in peripheral blood and brain tissue through microscopic examination and PCR assay, respectively, in acutely and chronically infected rats. The reduction of ADA activity in the brain was associated with high levels of parasitemia and anemia in acute infections. Alterations in ADA activity of the brain in T. evansi-infected rats may have implications for pathogenesis of the disease.     

Essential residues in the H-NS binding site of Hha, a co-regulator of horizontally acquired genes in Enterobacteria

Proteins of the Hha/YmoA family co-regulate with H-NS the expression of horizontally acquired genes in Enterobacteria. Systematic mutations of conserved acidic residues in Hha have allowed the identification of D48 as an essential residue for H-NS binding and the involvement of E25. Mutations of these residues resulted in deregulation of sensitive genes in vivo. D48 is only partially solvent accessible, yet it defines the functional binding interface between Hha and H-NS confirming that Hha has to undergo a conformational change to bind H-NS. Exposed acidic residues, such as E25, may electrostatically facilitate and direct the approach of Hha to the positively charged region of H-NS enabling the formation of the final complex when D48 becomes accessible by a conformational change of Hha.     

Genetic panmixia and demographic dependence across the North Atlantic in the deep-sea fish,blue hake (Antimora rostrata)

The efficient investment of resources and effort into conservation strategies depends on the accurate identification of management units. At the same time, understanding the processes by which population structure evolves requires an understanding of the conditions under which panmixia may exist. Here, we study a species with an unusual, apparently sex-biased pattern of distribution, and test the hypothesis that distribution processes associated with this pattern (for example, congregating at a single dominant spawning site or periodic mixing during reproduction) could lead to panmixia over a large geographic range. Using 13 microsatellite markers, we compared 393 blue hake (Antimora rostrata) from 11 sample sites across a geographic range of over 3000 km, and found no evidence of population structure. We estimated current effective population size and found it to be large (∼15 000) across the sampled area. In addition, we used simulation models to test expectations about demographic correlation among populations and our ability to detect relevant levels of gene flow. All data were consistent with the interpretation of long-range panmixia.     

Androgenic hormones and aging--the link with female sexual function

In women, sexual function, hormones and aging are inextricably related. Sexual activity in women involves interest and motivation, the ability to become aroused and achieve orgasm, the pleasure of the experience and subsequent personal satisfaction. Androgens, as endogenous hormones or given as a therapy, potentially influence female sexual function, with research into the effects of exogenous androgens in women mostly devoted to effects on sexual desire. Some studies have been conducted to delineate the effects of testosterone on arousal, however arousal determined by laboratory measures does not always correlate with subjective reporting of a sensation of arousal. Overall large randomised controlled trials of exogenous testosterone show benefits over placebo on sexual desire, arousal, orgasm, pleasure and satisfaction. The aspects of consideration of androgen therapy for women that continue to stimulate debate in this therapeutic area include whether female sexual dysfunction is a condition that merits pharmacotherapy, how effective is such treatment and whether testosterone therapy is safe.     

Supramolecular architectures of metal-oxalato complexes containing purine nucleobases

The reaction of purine nucleobases (adenine, 3-methyladenine and 9-methylguanine) with a metallic salt in the presence of potassium oxalate yields three compounds with formulae {[Cd(μ-ox)(H₂O)(Hade)]·H₂O}_n (1), {[Cu(μ-ox)(H₂O)(3Meade)]·H₂O}_n (2) and [Cu(ox)(H₂O)₂(9Megua)]·2.5H₂O (3). Crystal structures of compounds 1-2 consist of 1D zig-zag chains in which cis-[M(H₂O)(nucleobase)]²⁺ fragments are linked by bis-bidentate oxalato ligands. In compound 1, the nucleobase is coordinated through the minor groove N3 atom, and the resulting non-canonical 7H-adenine tautomer is stabilized by non-covalent interactions involving more basic N9 and N7 sites. In compound 2, the mutagenic 3-methyladenine is attached to the metal atoms by means of the imidazole N7 atom. The dissimilar binding pattern of the nucleobases produces significant differences in the supramolecular architectures of compounds 1 and 2 which are essentially governed by an extensive network of non-covalent interactions such as hydrogen bonded adenine-adenine base pairs, hydration of the nucleobases, carboxylato-nucleobase associations, and face-to-face π-π stacking. The model 9-methylguanine nucleobase of compound 3 exhibits its usual coordination mode through the major groove N7 atom to form two monomeric [(Cu(ox)(H₂O)₂(9Megua)] units which are held together by means of Watson-Crick like hydrogen bonds between the guanine moieties and the inorganic frameworks generating almost planar tetrameric metal-organic aggregates. The 3D packing of the complex entities affords an open structure containing voids which are filled by decameric (H₂O)₁₀ clusters. Variable-temperature magnetic susceptibility measurements of compound 2 show the occurrence of antiferromagnetic intrachain interactions in good agreement with the structural features of its 1D metal-oxalato framework.     

Inclusion complex of 2-chlorobenzophenone with cyclomaltoheptaose (β-cyclodextrin): temperature, solvent effects and molecular modeling

A thermodynamic study of the inclusion process between 2-chlorobenzophenone (2ClBP) and cyclomaltoheptaose (β-cyclodextrin, β-CD) was performed using UV–vis spectroscopy, reversed-phase liquid chromatography (RP-HPLC), and molecular modeling (PM6). Spectrophotometric measurements in aqueous solutions were performed at different temperatures. The stoichiometry of the complex is 1:1 and its apparent formation constant (K_c) is 3846 M⁻¹ at 30 °C. Temperature dependence of K_c values revealed that both enthalpy (ΔH° = −10.58 kJ/mol) and entropy changes (ΔS° = 33.76 J/K mol) are favorable for the inclusion process in an aqueous medium. Encapsulation was also investigated using RP-HPLC (C18 column) with different mobile-phase compositions, to which β-CD was added. The apparent formation constants in MeOH–H₂O (K_F) were dependent of the proportion of the mobile phase employed (50:50, 55:45, 60:40 and 65:35, v/v). The K_F values were 419 M⁻¹ (50% MeOH) and 166 M⁻¹ (65% MeOH) at 30 °C. The thermodynamic parameters of the complex in an aqueous MeOH medium indicated that this process is largely driven by enthalpy change (ΔH° = −27.25 kJ/mol and ΔS° = −45.12 J/K mol). The results of the study carried out with the PM6 semiempirical method showed that the energetically most favorable structure for the formation of the complex is the ‘head up’ orientation.     

Bim-mediated apoptosis and PD-1/PD-L1 pathway impair reactivity of PD1(+)/CD127(-) HCV-specific CD8(+) cells targeting the virus in chronic hepatitis C virus infection

PD-1 molecule promotes anergy and IL-7 receptor (CD127) induces an anti-apoptotic effect on T cells. Correlation between PD-1/CD127 phenotype and hepatitis C virus (HCV)-specific CD8⁺ cell reactivity in resolved infection (RI) after treatment and persistent HCV-infection (PI) was analysed. Directly ex vivo, PD-1 and CD127 expression on HCV-specific CD8⁺ cells displayed a positive and negative correlation, respectively with viraemia. Proliferation after stimulation on PD-1⁻/CD127⁺ cells from RI cases was preserved, while it was impaired on PD-1⁺/CD127⁻ cells from PI patients. PD1⁺/CD127⁺ population was observed in PI, and these maintained expansion ability but they did not target the virus. Frequency of PI cases with HCV-specific CD8⁺ cell proliferation increased after anti-PD-L1 and anti-apoptotic treatment. Bim expression on HCV-specific CD8⁺ cells from PI patients was enhanced. In conclusion, during chronic HCV infection non-reactive HCV-specific CD8⁺ cells targeting the virus are PD-1⁺/CD127⁻/Bim⁺ and, blocking apoptosis and PD-1/PD-L1 pathway on them enhances in vitro reactivity.     

The role of gap junction communication and oxidative stress in the propagation of toxic effects among high-dose α-particle-irradiated human cells

We investigated the roles of gap junction communication and oxidative stress in modulating potentially lethal damage repair in human fibroblast cultures exposed to doses of α particles or γ rays that targeted all cells in the cultures. As expected, α particles were more effective than γ rays at inducing cell killing; further, holding γ-irradiated cells in the confluent state for several hours after irradiation promoted increased survival and decreased chromosomal damage. However, maintaining α-particle-irradiated cells in the confluent state for various times prior to subculture resulted in increased rather than decreased lethality and was associated with persistent DNA damage and increased protein oxidation and lipid peroxidation. Inhibiting gap junction communication with 18-α-glycyrrhetinic acid or by knockdown of connexin43, a constitutive protein of junctional channels in these cells, protected against the toxic effects in α-particle-irradiated cell cultures during confluent holding. Upregulation of antioxidant defense by ectopic overexpression of glutathione peroxidase protected against cell killing by α particles when cells were analyzed shortly after exposure. However, it did not attenuate the decrease in survival during confluent holding. Together, these findings indicate that the damaging effect of α particles results in oxidative stress, and the toxic effects in the hours after irradiation are amplified by intercellular communication, but the communicated molecule(s) is unlikely to be a substrate of glutathione peroxidase.