A pharmaco-EEG study on antipsychotic drugs in healthy volunteers

RATIONALE: Both psychotropic drugs and mental disorders have typical signatures in quantitative electroencephalography (EEG). Previous studies found that some psychotropic drugs had EEG effects opposite to the EEG effects of the mental disorders treated with these drugs (key-lock principle). OBJECTIVES: We performed a placebo-controlled pharmaco-EEG study on two conventional antipsychotics (chlorpromazine and haloperidol) and four atypical antipsychotics (olanzapine, perospirone, quetiapine, and risperidone) in healthy volunteers. We investigated differences between conventional and atypical drug effects and whether the drug effects were compatible with the key-lock principle. METHODS: Fourteen subjects underwent seven EEG recording sessions, one for each drug (dosage equivalent of 1 mg haloperidol). In a time-domain analysis, we quantified the EEG by identifying clusters of transiently stable EEG topographies (microstates). Frequency-domain analysis used absolute power across electrodes and the location of the center of gravity (centroid) of the spatial distribution of power in different frequency bands. RESULTS: Perospirone increased duration of a microstate class typically shortened in schizophrenics. Haloperidol increased mean microstate duration of all classes, increased alpha 1 and beta 1 power, and tended to shift the beta 1 centroid posterior. Quetiapine decreased alpha 1 power and shifted the centroid anterior in both alpha bands. Olanzapine shifted the centroid anterior in alpha 2 and beta 1. CONCLUSIONS: The increased microstate duration under perospirone and haloperidol was opposite to effects previously reported in schizophrenic patients, suggesting a key-lock mechanism. The opposite centroid changes induced by olanzapine and quetiapine compared to haloperidol might characterize the difference between conventional and atypical antipsychotics.

The role of macrophages in the clearance of inhaled ultrafine titanium dioxide particles

The role of macrophages in the clearance of particles with diameters less than 100 nm (ultrafine or nanoparticles) is not well established, although these particles deposit highly efficiently in peripheral lungs, where particle phagocytosis by macrophages is the primary clearance mechanism. To investigate the uptake of nanoparticles by lung phagocytes, we analyzed the distribution of titanium dioxide particles of 20 nm count median diameter in macrophages obtained by bronchoalveolar lavage at 1 hour and 24 hours after a 1-hour aerosol inhalation. Differential cell counts revealing greater than 96% macrophages and less than 1% neutrophils and lymphocytes excluded inflammatory cell responses. Employing energy-filtering transmission electron microscopy (EFTEM) for elemental microanalysis, we examined 1,594 macrophage profiles in the 1-hour group (n = 6) and 1,609 in the 24-hour group (n = 6). We found 4 particles in 3 macrophage profiles at 1 hour and 47 particles in 27 macrophage profiles at 24 hours. Model-based data analysis revealed an uptake of 0.06 to 0.12% ultrafine titanium-dioxide particles by lung-surface macrophages within 24 hours. Mean (SD) particle diameters were 31 (8) nm at 1 hour and 34 (10) nm at 24 hours. Particles were localized adjacent (within 13-83 nm) to the membrane in vesicles with mean (SD) diameters of 592 (375) nm at 1 hour and 414 (309) nm at 24 hours, containing other material like surfactant. Additional screening of macrophage profiles by conventional TEM revealed no evidence for agglomerated nanoparticles. These results give evidence for a sporadic and rather unspecific uptake of TiO(2)-nanoparticles by lung-surface macrophages within 24 hours after their deposition, and hence for an insufficient role of the key clearance mechanism in peripheral lungs.

Transgenic system for conditional induction and rescue of chronic myocardial hibernation provides insights into genomic programs of hibernation

A key energy-saving adaptation to chronic hypoxia that enables cardiomyocytes to withstand severe ischemic insults is hibernation, i.e., a reversible arrest of contractile function. Whereas hibernating cardiomyocytes represent the critical reserve of dysfunctional cells that can be potentially rescued, a lack of a suitable animal model has hampered insights on this medically important condition. We developed a transgenic mouse system for conditional induction of long-term hibernation and a system to rescue hibernating cardiomyocytes at will. Via myocardium-specific induction (and, in turn, deinduction) of a VEGF-sequestering soluble receptor, we show that VEGF is indispensable for adjusting the coronary vasculature to match increased oxygen consumption and exploit this finding to generate a hypoperfused heart. Importantly, ensuing ischemia is tunable to a level at which large cohorts of cardiomyocytes are driven to enter a hibernation mode, without cardiac cell death. Relieving the VEGF blockade even months later resulted in rapid revascularization and full recovery of contractile function. Furthermore, we show that left ventricular remodeling associated with hibernation is also fully reversible. The unique opportunity to uncouple hibernation from other ischemic heart phenotypes (e.g., infarction) was used to determine the genetic program of hibernation; uncovering hypoxia-inducible factor target genes associated with metabolic adjustments and induced expression of several cardioprotective genes. Autophagy, specifically self-digestion of mitochondria, was identified as a key prosurvival mechanism in hibernating cardiomyocytes. This system may lend itself for examining the potential utility of treatments to rescue dysfunctional cardiomyocytes and reverse maladaptive remodeling.

Spider Ecophysiology

With over 43,000 species, spiders are the largest predacious arthropod group. They have developed key characteristics such as multi-purpose silk types, venoms consisting of hundreds of components, locomotion driven by muscles and hydraulic pressure, a highly evolved key-lock mechanism between the complex genital structures, and many more unique features. After 300 million years of evolutionary refinement, spiders are present in all land habitats and represent one of the most successful groups of terrestrial organisms. Ecophysiology combines functional and evolutionary aspects of morphology, physiology, biochemistry and molecular biology with ecology. Cutting-edge science in spiders focuses on the circulatory and respiratory system, locomotion and dispersal abilities, the immune system, endosymbionts and pathogens, chemical communication, gland secretions, venom components, silk structure, structure and perception of colours as well as nutritional requirements. Spiders are valuable indicator species in agroecosystems and for conservation biology. Modern transfer and application technologies research spiders and their products with respect to their value for biomimetics, material sciences, and the agrochemical and pharmaceutical industries.

NOX3-Targeted Therapies for Inner Ear Pathologies

Inner ear pathologies are associated with major morbidity and loss of life quality in affected patients. In many of these conditions, production of reactive oxygen-species (ROS) is thought to be a key pathological mechanism. While the sources of ROS are complex (including for example mitochondria), there is increasing evidence that activation of NOX enzymes, in particular NOX3, plays a key role. NOX3 is a multi-subunit NADPH oxidase, functionally and structurally closely related to NOX1 and NOX2. In both the vestibular and the cochlear compartments of the inner ear, high levels of NOX3 mRNA are expressed. In NOX3 mutant mice, the vestibular function is perturbed due to a lack of otoconia, while only minor alterations of hearing have been documented. However, there is increasing evidence that activation of NOX3 through drugs, noise and probably also aging, leads to hearing loss. Thus, NOX3 is an interesting target to treat and prevent inner ear pathologies and a few first animal models based on drug - or molecular therapy have been reported. So far however, there are no specific NOX3 inhibitors with a documented penetration into the inner ear. Nevertheless, certain antioxidants and non-specific NOX inhibitors diminish hearing loss in animal models. Development of small molecules inhibitors or molecular strategies against NOX3 could improve specificity and efficiency of redox-targeted treatments. In this review, we will discuss arguments for the involvement of NOX3 in inner ear pathologies and therapeutic approaches to target NOX3 activity.

Low serum testosterone and increased diastolic ocular perfusion pressure: a risk for retinal microvasculature

BACKGROUND Low levels of testosterone in men and changes in retinal microvascular calibre are both associated with hypertension and cardiovascular disease risk. Sex hormones are also associated with blood flow in microvascular beds which might be a key intermediate mechanism in the development of hypertension. Whether a direct association between endogenous testosterone and retinal microvascular calibre exists is currently unknown. We aimed to determine whether testosterone is independently associated with ocular perfusion via a possible association with retinal vascular calibre or whether it plays only a secondary role via its effect on blood pressure in a bi-ethnic male cohort. PROBANDS AND METHODS A total of 72 black and 81 white men (28-68 years of age) from the follow-up phase of the Sympathetic activity and Ambulatory Blood Pressure in Africans (SABPA) study were included in this sub-study. Ambulatory pulse pressure and intraocular perfusion pressures were obtained, while metabolic variables and testosterone were measured from fasting venous blood samples. Retinal vascular calibre was quantified from digital photographs using standardised protocols. RESULTS The black men revealed a poorer cardiometabolic profile and higher pulsatile pressure (>50 mm Hg), intraocular pressure and diastolic ocular perfusion pressure than the white men (p≤0.05). Only in the white men was free testosterone positively associated with retinal calibre, i.e. arterio-venular ratio and central retinal arterial calibre and inversely with central retinal venular calibre. These associations were not found in the black men, independent of whether pulse pressure and ocular perfusion pressure were part of the model. CONCLUSIONS These results suggest an independent, protective effect of testosterone on the retinal vasculature where an apparent vasodilatory response in the retinal resistance microvessels was observed in white men.

Activation of sphingosine kinase 2 is an endogenous protective mechanism in cerebral ischemia

The two ubiquitously expressed sphingosine kinases (SphK) 1 and 2 are key regulators of the sphingolipid signaling pathway. Despite the formation of an identical messenger, i.e. sphingosine 1-phosphate (S1P), they exert strikingly different functions. Particularly, SphK2 is necessary for the phosphorylation of the sphingosine analog fingolimod (FTY720), which is protective in rodent stroke models. Using gene deficient mice lacking either SphK1 or SphK2, we investigated the role of the two lipid kinases in experimental stroke. We performed 2h transient middle cerebral artery occlusion (tMCAO) and analyzed lesion size and neurological function after 24h. Treatment groups received 1mg/kg FTY720. Neutrophil infiltration, microglia activation, mRNA and protein expression of SphK1, SphK2 and the S1P(1) receptor after tMCAO were studied. Genetic deletion of SphK2 but not SphK1 increased ischemic lesion size and worsened neurological function after tMCAO. The protective effect of FTY720 was conserved in SphK1(-/-) mice but not in SphK2(-/-) mice. This suggests that SphK2 activity is an important endogenous protective mechanism in cerebral ischemia and corroborates that the protective effect of FTY720 is mediated via phospho-FTY720.

A novel mechanism for hypofibrinolysis in diabetes: the role of complement C3

Impaired fibrin clot lysis is a key abnormality in diabetes and complement C3 is one protein identified in blood clots. This work investigates the mechanistic pathways linking C3 and hypofibrinolysis in diabetes using ex vivo/in vitro studies.

Crystal structure of the platelet glycoprotein Ib(alpha) N-terminal domain reveals an unmasking mechanism for receptor activation

Glycoprotein Ib (GPIb) is a platelet receptor with a critical role in mediating the arrest of platelets at sites of vascular damage. GPIb binds to the A1 domain of von Willebrand factor (vWF-A1) at high blood shear, initiating platelet adhesion and contributing to the formation of a thrombus. To investigate the molecular basis of GPIb regulation and ligand binding, we have determined the structure of the N-terminal domain of the GPIb(alpha) chain (residues 1-279). This structure is the first determined from the cell adhesion/signaling class of leucine-rich repeat (LRR) proteins and reveals the topology of the characteristic disulfide-bonded flanking regions. The fold consists of an N-terminal beta-hairpin, eight leucine-rich repeats, a disulfide-bonded loop, and a C-terminal anionic region. The structure also demonstrates a novel LRR motif in the form of an M-shaped arrangement of three tandem beta-turns. Negatively charged binding surfaces on the LRR concave face and anionic region indicate two-step binding kinetics to vWF-A1, which can be regulated by an unmasking mechanism involving conformational change of a key loop. Using molecular docking of the GPIb and vWF-A1 crystal structures, we were also able to model the GPIb.vWF-A1 complex.

FTY720 suppresses interleukin-1beta-induced secretory phospholipase A2 expression in renal mesangial cells by a transcriptional mechanism

BACKGROUND AND PURPOSE: FTY720 is a potent immunomodulatory prodrug that is converted to its active phosphorylated form by a sphingosine kinase. Here we have studied whether FTY720 mimicked the action of sphingosine-1-phosphate (S1P) and exerted an anti-inflammatory potential in renal mesangial cells. EXPERIMENTAL APPROACH: Prostaglandin E(2) (PGE(2)) was quantified by an enzyme-linked immunosorbent-assay. Secretory phospholipase A(2) (sPLA(2)) protein was detected by Western blot analyses. mRNA expression was determined by Northern blot analysis and sPLA(2)-promoter activity was measured by a luciferase-reporter-gene assay. KEY RESULTS: Stimulation of cells for 24 h with interleukin-1beta (IL-1beta) is known to trigger increased PGE(2) formation which coincides with an induction of the mRNA for group-IIA-sPLA(2) and protein expression. FTY720 dose-dependently suppressed IL-1beta-induced IIA-sPLA(2) protein secretion and activity in the supernatant. This effect is due to a suppression of cytokine-induced sPLA(2) mRNA expression which results from a reduced promoter activity. As a consequence of suppressed sPLA(2) activity, PGE(2) formation is also reduced by FTY720. Mechanistically, the FTY720-suppressed sPLA(2) expression results from an activation of the TGFbeta/Smad signalling cascade since inhibition of the TGFbeta receptor type I by a specific kinase inhibitor reverses the FTY720-mediated decrease of sPLA(2) protein expression and sPLA(2) promoter activity. CONCLUSIONS AND IMPLICATIONS: In summary, our data show that FTY720 was able to mimic the anti-inflammatory activity of TGFbeta and blocked cytokine-triggered sPLA(2) expression and subsequent PGE(2) formation. Thus, FTY720 may exert additional in vivo effects besides the well reported immunomodulation and its anti-inflammatory potential should be considered.

Cathepsins: key modulators of cell death and inflammatory responses

Apoptosis is a key mechanism in the build up and maintenance of both innate and adaptive immunity as well as in the regulation of cellular homeostasis in almost every organ and tissue. Central to the apoptotic process is a family of intracellular cysteine proteases with aspartate-specificity, called caspases. Nevertheless, there is growing evidence that other non-caspase proteases, in particular lysosomal cathepsins, can play an important role in the regulation of apoptosis. In this review, the players and the molecular mechanisms involved in the lysosomal apoptotic pathways will be discussed as well as the importance of these pathways in the immune system and the pathogenesis of diseases.

Stomatal opening at elevated temperature: an underestimated regulatory mechanism?

Climate models predict more frequent and more severe extreme events (e.g. heat waves, extended drought periods) in Europe during the next decades. The response of plants to elevated temperature is a key issue in this context. Stomatal regulation is not only relevant for the diffusion of CO2 from the ambient air into the leaves, but it plays also an important role for the control of transpiration and leaf cooling. The regulation of stomatal aperture by the water status (hydroactive and hydropassive feed-back) and by internal CO2 availability (CO2 feed-back) are well documented in the literature, while the response of the stomates to elevated temperature was far less considered in the past. Photosynthesis is negatively affected by elevated temperature, but the water loss via transpiration may still be high. In the experiments reported here, bean leaf segments were incubated in darkness floating on water in the range from 20 to 50°C and then analyzed immediately by taking a photograph with a digital microscope. Stomatal aperture was measured on these pictures in order to quantify stomatal opening. After the incubation for 30 min, the opening was 0.66, 2.76 and 4.28 μm at 23, 30 and 35°C respectively. This opening at elevated temperature was fully reversible. Abscisic acid (0.1 μM) in the incubation medium shifted the temperature for stomatal opening to higher values. It can be concluded that elevated temperature stimulates stomatal opening regardless of the CO2 assimilation status and that there is a trade-off between leaf cooling on one hand and limiting water loss during drought periods on the other hand.

p62/SQSTM1 upregulation constitutes a survival mechanism that occurs during granulocytic differentiation of acute myeloid leukemia cells.

The p62/SQSTM1 adapter protein has an important role in the regulation of several key signaling pathways and helps transport ubiquitinated proteins to the autophagosomes and proteasome for degradation. Here, we investigate the regulation and roles of p62/SQSTM1 during acute myeloid leukemia (AML) cell maturation into granulocytes. Levels of p62/SQSTM1 mRNA and protein were both significantly increased during all-trans retinoic acid (ATRA)-induced differentiation of AML cells through a mechanism that depends on NF-κB activation. We show that this response constitutes a survival mechanism that prolongs the life span of mature AML cells and mitigates the effects of accumulation of aggregated proteins that occurs during granulocytic differentiation. Interestingly, ATRA-induced p62/SQSTM1 upregulation was impaired in maturation-resistant AML cells but was reactivated when differentiation was restored in these cells. Primary blast cells of AML patients and CD34(+) progenitors exhibited significantly lower p62/SQSTM1 mRNA levels than did mature granulocytes from healthy donors. Our results demonstrate that p62/SQSTM1 expression is upregulated in mature compared with immature myeloid cells and reveal a pro-survival function of the NF-κB/SQSTM1 signaling axis during granulocytic differentiation of AML cells. These findings may help our understanding of neutrophil/granulocyte development and will guide the development of novel therapeutic strategies for refractory and relapsed AML patients with previous exposure to ATRA.