Photosynthetic Reaction-Center/Graphene Biohybrid for Optoelectronics.

Photosynthetic reaction center proteins (RC) purified from purple bacterial strains were deposited on graphene layer prepared by liquid phase exfoliation and light-induced resistance change was measured. By measuring the temperature dependence of the resistance change of the bare and RC covered graphene and comparing with the one inactivated by protein unfolding, two effects were possible to separate. One of them is the resistance change due to temperature effect. The other one clearly indicates a possible electric/electronic interaction between the charge flow in the graphene and the light-induced charge pair within the protein, which is, essentially, different in the open (dark, PBPheo) and closed (light, P+BPheo-) states. These results provide useful information for designing hybrid bio-photonic devices which are able to absorb and convert light energy.

Sensing photosynthetic herbicides in an electrochemical flow cell.

Specific inhibitory reactions of herbicides with photosynthetic reaction centers bound to working electrodes were monitored in a conventional electrochemical cell and a newly designed microfluidic electrochemical flow cell. In both cases, the bacterial reaction centers were bound to a transparent conductive metal oxide, indium-tin-oxide, electrode through carbon nanotubes. In the conventional cell, photocurrent densities of up to a few µA/cm2 could be measured routinely. The photocurrent could be blocked by the photosynthetic inhibitor terbutryn (I 50 = 0.38 ± 0.14 µM) and o-phenanthroline (I 50 = 63.9 ± 12.2 µM). The microfluidic flow cell device enabled us to reduce the sample volume and to simplify the electrode arrangement. The useful area of the electrodes remained the same (ca. 2 cm2), similar to the classical electrochemical cell; however, the size of the cell was reduced considerably. The microfluidic flow control enabled us monitoring in real time the binding/unbinding of the inhibitor and cofactor molecules at the secondary quinone site.

Radiomics-based differentiation of lung disease models generated by polluted air based on X-ray computed tomography data.

BACKGROUND: Lung diseases (resulting from air pollution) require a widely accessible method for risk estimation and early diagnosis to ensure proper and responsive treatment. Radiomics-based fractal dimension analysis of X-ray computed tomography attenuation patterns in chest voxels of mice exposed to different air polluting agents was performed to model early stages of disease and establish differential diagnosis. METHODS: To model different types of air pollution, BALBc/ByJ mouse groups were exposed to cigarette smoke combined with ozone, sulphur dioxide gas and a control group was established. Two weeks after exposure, the frequency distributions of image voxel attenuation data were evaluated. Specific cut-off ranges were defined to group voxels by attenuation. Cut-off ranges were binarized and their spatial pattern was associated with calculated fractal dimension, then abstracted by the fractal dimension -- cut-off range mathematical function. Nonparametric Kruskal-Wallis (KW) and Mann-Whitney post hoc (MWph) tests were used. RESULTS: Each cut-off range versus fractal dimension function plot was found to contain two distinctive Gaussian curves. The ratios of the Gaussian curve parameters are considerably significant and are statistically distinguishable within the three exposure groups. CONCLUSIONS: A new radiomics evaluation method was established based on analysis of the fractal dimension of chest X-ray computed tomography data segments. The specific attenuation patterns calculated utilizing our method may diagnose and monitor certain lung diseases, such as chronic obstructive pulmonary disease (COPD), asthma, tuberculosis or lung carcinomas.

Using Central Composite Experimental Design to Optimize the Degradation of Tylosin from Aqueous Solution by Photo-Fenton Reaction.

The feasibility of the application of the Photo-Fenton process in the treatment of aqueous solution contaminated by Tylosin antibiotic was evaluated. The Response Surface Methodology (RSM) based on Central Composite Design (CCD) was used to evaluate and optimize the effect of hydrogen peroxide, ferrous ion concentration and initial pH as independent variables on the total organic carbon (TOC) removal as the response function. The interaction effects and optimal parameters were obtained by using MODDE software. The significance of the independent variables and their interactions was tested by means of analysis of variance (ANOVA) with a 95% confidence level. Results show that the concentration of the ferrous ion and pH were the main parameters affecting TOC removal, while peroxide concentration had a slight effect on the reaction. The optimum operating conditions to achieve maximum TOC removal were determined. The model prediction for maximum TOC removal was compared to the experimental result at optimal operating conditions. A good agreement between the model prediction and experimental results confirms the soundness of the developed model.

Structural and Functional Hierarchy in Photosynthetic Energy Conversion-from Molecules to Nanostructures.

Basic principles of structural and functional requirements of photosynthetic energy conversion in hierarchically organized machineries are reviewed. Blueprints of photosynthesis, the energetic basis of virtually all life on Earth, can serve the basis for constructing artificial light energy-converting molecular devices. In photosynthetic organisms, the conversion of light energy into chemical energy takes places in highly organized fine-tunable systems with structural and functional hierarchy. The incident photons are absorbed by light-harvesting complexes, which funnel the excitation energy into reaction centre (RC) protein complexes containing redox-active chlorophyll molecules; the primary charge separations in the RCs are followed by vectorial transport of charges (electrons and protons) in the photosynthetic membrane. RCs possess properties that make their use in solar energy-converting and integrated optoelectronic systems feasible. Therefore, there is a large interest in many laboratories and in the industry toward their use in molecular devices. RCs have been bound to different carrier matrices, with their photophysical and photochemical activities largely retained in the nano-systems and with electronic connection to conducting surfaces. We show examples of RCs bound to carbon-based materials (functionalized and non-functionalized single- and multiwalled carbon nanotubes), transitional metal oxides (ITO) and conducting polymers and porous silicon and characterize their photochemical activities. Recently, we adapted several physical and chemical methods for binding RCs to different nanomaterials. It is generally found that the P(+)(QAQB)(-) charge pair, which is formed after single saturating light excitation is stabilized after the attachment of the RCs to the nanostructures, which is followed by slow reorganization of the protein structure. Measuring the electric conductivity in a direct contact mode or in electrochemical cell indicates that there is an electronic interaction between the protein and the inorganic carrier matrices. This can be a basis of sensing element of bio-hybrid device for biosensor and/or optoelectronic applications.

Thermal Effects and Structural Changes of Photosynthetic Reaction Centers Characterized by Wide Frequency Band Hydrophone: Effects of Carotenoids and Terbutryn.

Photothermal characteristics and light-induced structural (volume) changes of carotenoid-containing and noncontaining photosynthetic reaction centers (RCs) were investigated by wide frequency band hydrophone. We found that the presence of carotenoid either does not play considerable role in the light-induced conformational movements, or these rearrangements are too slow for inducing a photoacoustic (PA) signal. The kinetic component with a few tens of microseconds, exhibited by the carotenoid-less RCs, appears to be similar to that of triplet state lifetimes, identified by other methods. The binding of terbutryn to the acceptor side is shown to affect the dynamics of the RC. Our results do not confirm large displacements or volume changes induced by the charge movements and by the charge relaxation processes in the RCs in few hundreds of microseconds time scale that accompanies the electron transfer between the primary and secondary electron acceptor quinones.

Insulin resistance in heart failure: differences between patients with reduced and preserved left ventricular ejection fraction.

AIMS: Insulin resistance (IR) is a characteristic feature of heart failure (HF) pathophysiology that affects symptoms and mortality. Differences in the pathophysiological profile of IR in HF with preserved ejection fraction (HFpEF) and HF with reduced ejection fraction (HFrEF) are not characterized in detail. The aim of this study was to evaluate features of IR in HFpEF vs. HFrEF. METHODS AND RESULTS: We included 18 patients with HFrEF (EF 30 ± 11%, body mass index (BMI) 26.5 ± 3.3 kg/m(2)), 22 HFpEF patients (EF 63 ± 7%, BMI 28.6 ± 4.8 kg/m(2)), and 20 healthy controls of similar age, all without diabetes mellitus. Patients were in stable ambulatory condition and on stable medical regimens for HF. IR was assessed at fasting steady state by the homeostasis model assessment (HOMA) index and within the physiological range of insulin-glucose interactions by the short insulin sensitivity test (SIST). Fasting-state IR was observed in HFpEF and in HFrEF in comparison with controls (HOMA 1.9, interquartile range (IQR) 1.5-3.6 vs. HOMA 3.1, IQR 1.4-3.7 vs. controls 1.2, IQR 1.8-0.9, respectively; analysis of variance P < 0.001), but no statistical difference was observed between HFpEF and HFrEF. The dynamic test over the physiological range of insulin-glucose interactions revealed a more severe IR in HFrEF as compared with HFpEF. Thus, glucose levels remained the highest in HFrEF (76 (64-89) mg/dL) at the end of the SIST compared with HFpEF and controls (68 (58-79) and 56 (44-66) mg/dL, respectively, P < 0.001). CONCLUSION: IR is present in non-diabetic patients with HFpEF and HFrEF. However, distinct differences in the insulin sensitivity characteristics in HFpEF and HFrEF become apparent by more advanced testing. Patients with HFrEF showed more severe IR.

Structure and binding efficiency relations of QB site inhibitors of photosynthetic reaction centres.

Many herbicides employed in agriculture and also some antibiotics bind to a specific site of the reaction centre protein (RC) blocking the photosynthetic electron transport. Crystal structures showed that all these compounds bind at the secondary ubiquinone (QB) site albeit to slightly different places. Different herbicide molecules have different binding affinities (evaluated as inhibition constants, KI, and binding enthalpy values, ΔHbind). The action of inhibitors depends on the following parameters: (i) herbicide molecular structure; (ii) interactions between herbicide and quinone binding site; (iii) protein environment. In our investigations KI and ΔHbind were determined for several inhibitors. Bound herbicide structures were optimized and their intramolecular charge distributions were calculated. Experimental and calculated data were compared to those available from databank crystal structures. We can state that the herbicide inhibition efficiency depends on steric and electronic, i.e. geometry of binding with the protein and molecular charge distribution, respectively. Apolar bulky groups on N-7 atom of the inhibitor molecule (like t-buthyl in terbutryn) are preferable for establishing stronger interactions with QB site, while such substituents are not recommended on N-8. The N-4,7,8 nitrogen atoms maintain a larger electron density so that more effective H-bonds are formed between the inhibitor and the surrounding amino acids of the protein.

Photosynthetic machineries in nano-systems.

Photosynthetic reaction centres are membrane-spanning proteins, found in several classes of autotroph organisms, where a photoinduced charge separation and stabilization takes place with a quantum efficiency close to unity. The protein remains stable and fully functional also when extracted and purified in detergents thereby biotechnological applications are possible, for example, assembling it in nano-structures or in optoelectronic systems. Several types of bionanocomposite materials have been assembled by using reaction centres and different carrier matrices for different purposes in the field of light energy conversion (e.g., photovoltaics) or biosensing (e.g., for specific detection of pesticides). In this review we will summarize the current status of knowledge, the kinds of applications available and the difficulties to be overcome in the different applications. We will also show possible research directions for the close future in this specific field.

Increased catabolic activity in adipose tissue of patients with chronic heart failure.

AIMS: Patients with chronic heart failure (CHF) have an increased catabolic state that affects both muscle and adipose tissue (AT), and may ultimately result in cardiac cachexia. Increased plasma levels of ANP might contribute to increased lipid mobilization and oxidation in CHF. We tested the hypothesis that increased plasma ANP levels are associated with an increased catabolic (lipolytic) state of white AT in patients with CHF. METHODS AND RESULTS: After an overnight fast, AT metabolism was studied by microdialysis in patients with CHF and healthy controls of a similar age and body composition (both n = 8). AT glycolytic and lipolytic activities were assessed at rest (fasting) and after an oral glucose load (oGL). Fasting and post-prandial profiles of serum glucose, insulin, and free fatty acids and of dialysate glucose did not differ significantly between patients and controls. In contrast, fasting dialysate lactate and glycerol levels were two-fold higher in patients vs. controls (lactate, 0.51 ± 0.10 and 0.26 ± 0.06 mmol/L, P < 0.01; glycerol, 116 ± 18 and 50 ± 8 µmol/L, P < 0.001), indicating increased AT glycolytic and lipolytic rates in patients. After an oGL, dialysate lactate increased ∼2- and 2.5-fold, whereas dialysate glycerol decreased by ∼60% and 50% in patients vs. controls, but metabolite levels were always significantly higher in patients vs. controls (all P < 0.05). Plasma ANP levels were increased in patients and significantly correlated with adipose tissue dialysate glycerol. CONCLUSION: In patients wiuth CHF, there is a direct correlation between plasma ANP levels and increased AT catabolic (lipolytic) state. This might contribute to AT wasting and the development of cardiac cachexia in patients with CHF.

Assessment of serum cotinine in patients with chronic heart failure: self-reported versus objective smoking behaviour.

BACKGROUND: Smoking is a major risk factor in the development of coronary artery disease and thus chronic heart failure (HF). The value of self-reported smoking behaviour has not been validated in patients with HF. We sought to assess serum cotinine levels, a marker of recent tobacco exposure, in a cohort of clinically stable patients with chronic HF. METHODS AND RESULTS: We analysed serum cotinine values in 75 patients with chronic HF [mean age ± SD 64 ± 16 years, 85 % male, left ventricular ejection fraction 30 ± 1 %, New York Heart Association class (I/II vs. III/IV) 73 %/27 %, haemoglobin (Hb) 13.4 ± 1.5 g/dL, serum creatinine 1.21 ± 0.51 mg/dL] and 30 control subjects of similar age (63 ± 11 years, 43 % male, Hb 14.1 ± 1.5 g/dL, creatinine 1.12 ± 0.92 mg/dL) using a chemiluminescence immunoassay. Patients were interviewed about their smoking habits, and routine laboratory parameters were analysed. In patients with HF, cotinine values ranged from undetectable to 829 µg/L (mean 110 ± 208 µg/L). Similar findings were evident in healthy subjects with cotinine ranging from undetectable to 860 µg/L (mean 105 ± 208 µg/L). Serum cotinine levels correlated with leukocyte count and haemoglobin concentration (both p < 0.05). Self-reported smoking behaviour did not correspond to serum cotinine level in serum in 16.9 % of the patients with chronic HF. No such finding was evident in control subjects. CONCLUSIONS: Serum cotinine measurement provides an easily applicable means to analyse smoking behaviour in patients with chronic HF. Its assessment may permit analysis of smoking deception in daily clinical routine.

Interaction of SSR161421, a novel specific adenosine A(3) receptor antagonist with adenosine A(3) receptor agonists both in vitro and in vivo.

A novel adenosine A(3) receptor antagonist (SSR161421) was characterized by both receptor binding assays and pharmacological tests. Binding studies on cloned human adenosine receptors showed that SSR161421 has high affinity for adenosine hA(3) receptors (K(i)=0.37 nM) with at least 1000-fold selectivity compared to hA(1), hA(2A) and hA(2B) receptors. The receptor antagonist nature of SSR161421 was determined in a functional study on Chinese hamster ovarian cells (CHO) cells expressing human adenosine A(3) receptors. SSR161421 competitively antagonized the effect of 2-chloro-N6-(3-iodobenzyl)-adenosine-5'-N-methylcarboxamide (Cl-IB-MECA) on cAMP production with a pA2 value in a luciferase reporter gene construct. In mice, intravenously administered SSR161421 inhibited the N6-(4-aminobenzyl)-adenosine-5'-N-methyl-uronamide dihydrochloride (AB-MECA) induced increase in plasma histamine levels (ED(50)=2.0mg/kg) and the Cl-IB-MECA evoked plasma extravasation (ID(50)=2.9 mg/kg) and oedema formation (ID(50)=4.6 mg/kg) in mouse ear.

Photosynthetic reaction centers/ITO hybrid nanostructure.

Photosynthetic reaction center proteins purified from Rhodobacter sphaeroides purple bacterium were deposited on the surface of indium tin oxide (ITO), a transparent conductive oxide, and the photochemical/-physical properties of the composite were investigated. The kinetics of the light induced absorption change indicated that the RC was active in the composite and there was an interaction between the protein cofactors and the ITO. The electrochromic response of the bacteriopheophytine absorption at 771 nm showed an increased electric field perturbation around this chromophore on the surface of ITO compared to the one measured in solution. This absorption change is associated with the charge-compensating relaxation events inside the protein. Similar life time, but smaller magnitude of this absorption change was measured on the surface of borosilicate glass. The light induced change in the conductivity of the composite as a function of the concentration showed the typical sigmoid saturation characteristics unlike if the photochemically inactive chlorophyll was layered on the ITO. In this later case the light induced change in the conductivity was oppositely proportional to the chlorophyll concentration due to the thermal dissipation of the excitation energy. The sensitivity of the measurement is very high; few picomole RC can change the light induced resistance of the composite.

Cachexia in heart disease: highlights from the ESC 2010.

Cardiac cachexia is a co-morbidity that may develop in terminal stages of chronic heart failure (CHF). Up to 15% of ambulatory patients with heart failure are affected. Over the last decades, cardiac cachexia and alterations in muscle metabolism in heart disease have received increasing research interest. This article highlights some recent studies of cardiac cachexia that were presented at the annual meeting of the European Society of Cardiology in September 2010 in Stockholm, Sweden. Studies presented here were focused on effects of exercise training and protein degradation, particularly into the role of the ubiquitin-proteasome complex and its ubiquitin ligases MuRF-1 and MAFbx. Exercise training in patients with CHF was found to increase maximal oxygen consumption and to reduce MuRF-1 expression. Lysosomal muscle degradation does not seem to play a major role in patients with CHF, however, inflammatory cytokines such as tumor necrosis factor-a trigger muscle protein degradation. Other studies found that the serum levels of the adipokine adiponectin are elevated in patients with CHF and that these levels may be correlated with muscle mass, muscle strength in the arms, or with trunk fat mass. Another study showed that the expression of myostatin in skeletal muscle, a negative regulator of muscle growth that is essential for normal regulation of muscle mass, is decreased in spontaneously hypertensive rats with heart failure compared with control animals. This is also true for follistatin, a powerful antagonist, and its potential as a biomarker of muscle wasting. These findings may pave the way for effective treatment approaches to cardiac cachexia.

Usefulness of minimal modelling to assess impaired insulin sensitivity in patients with chronic heart failure.

BACKGROUND: In chronic heart failure (CHF), impaired insulin sensitivity (Si) is frequently observed. It is associated with symptomatic status and poor prognosis suggesting an intrinsic role of Si within CHF pathophysiology. HOmeostasis Model Assessment (HOMA), Fasting Insulin Resistance Index (FIRI), and QUick Insulin CheCK Index (QUICKI) are based on single-time fasting glucose and insulin assessment. Their value and discriminatory power in comparison to dynamic range assessment of Si by minimal modelling are not well established. METHODS AND RESULTS: In 105 patients with stable CHF (mean age 62 ± 1 years, peak VO(2) 18.2 ± 0.7 mL/kg/min, LVEF 28 ± 2%, mean ± SEM) Si was assessed by minimal modelling. HOMA, FIRI, and QUICKI were calculated from single-time point fasting glucose and insulin measurements. Detailed body composition was analyzed using dual-energy X-ray absorptiometry. All assessment methods showed impaired Si in CHF patients compared to healthy controls (n = 25). Yet, only minimal model-derived Si differentiated between NYHA classes (p = 0.0007). Further, minimal modelling was the only method to be directly associated with peak oxygen uptake and skeletal muscle strength. Model-derived Si predicted survival independently of established prognostic markers in CHF (RR 0.30 [95%CI 0.14-0.63]; p = 0.0016). In contrast, HOMA, FIRI and QUICKI did not show any of these qualities. CONCLUSION: HOMA, FIRI and QUICKI are surrogate estimates of Si with reduced discriminatory power in patients with CHF. While they are suitable to semi-quantitatively categorize impaired Si compared to normal values, the dynamic range assessment of Si by minimal modelling is superior for quantitative assessment of Si in pathophysiological studies.

Overview of emerging pharmacotherapy in chronic heart failure.

Chronic heart failure (CHF) is of constantly growing importance regarding incidence, prevalence and social and economic burden. The classical mere hemodynamic perception of CHF pathophysiology has been expanded towards a much more complex and inclusive approach combining neuroendocrine, inflammatory, metabolic and immunological factors. With this advance, new parameters and targets have been shifted into the focus of current investigations, and new therapeutic approaches have been tested. Several recent studies have failed, however, despite intriguing pathophysiological concepts and promising pilot data. In other studies, significant benefits have been observed in certain subgroups only, suggesting a tailored approach for individual risk and co-morbidity situations. The contemporary concept of CHF treatment is designed to shield the heart from adverse (over)compensatory mechanisms particularly of neuroendocrine activation. This shield needs to be expanded on systemic effects including both immunologic and metabolic aspects within CHF pathophysiology. New and future concepts in CHF therapy may not yield a homogenous treatment option applicable for every patient, but may require a new range of diagnostic strategies to design a tailored therapy, adapted to the patient's pathophysiological fingerprint. This review will focus on recent developments and potential future candidates of pharmacological CHF therapy.

Biochemical and pharmacological characterization of 2-(9-(2-piperidinoethoxy)-4-oxo-4H-pyrido[1,2-a]pyrimidin-2-yloxymethyl)-4-(1-methylethyl)-6-methoxy-1,2-benzisothiazol-3(2H)-one-1,1-dioxide (SSR69071), a novel, orally active elastase inhibitor.

Human leukocyte elastase (HLE) is a proteinase capable of degrading a variety of proteins. Under normal circumstances, the proteolytic activity of HLE is effectively controlled by its natural inhibitors. However, an imbalance between elastase and its endogenous inhibitors may result in several pathophysiological states such as chronic obstructive pulmonary disease, asthma, emphysema, cystic fibrosis, and chronic inflammatory diseases. It is anticipated that an orally active HLE inhibitor could be useful for the treatment of these diseases. 2-(9-(2-Piperidinoethoxy)-4-oxo-4H-pyrido[1,2-a]pyrimidin-2-yloxymethyl)-4-(1-methylethyl)-6-methoxy-1,2-benzisothiazol-3(2H)-one-1,1-dioxide (SSR69071) is a potent inhibitor of HLE, with the inhibition constant (K(i)) and the constant for inactivation process (k(on)) being 0.0168 +/- 0.0014 nM and 0.183 +/- 0.013 10(6)/mol sr, respectively. The dissociation rate constant, k(off), was 3.11 + 0.37 10(-6)/s. SSR69071 displays a higher affinity for human elastase than for rat (K(i) = 3 nM), mouse (K(i) = 1.8 nM), and rabbit (K(i) = 58 nM) elastases. Bronchoalveolar lavage fluid from mice orally treated with SSR69071 inhibits HLE (ex vivo), and in this model, SSR69071 has a dose-dependent efficacy with an ED(50) = 10.5 mg/kg p.o. SSR69071 decreases significantly the acute lung hemorrhage induced by HLE (ED(50) = 2.8 mg/kg p.o.) in mice. Furthermore, SSR69071 prevents carrageenan- (ED(30) = 2.2 mg/kg) and HLE-induced (ED(30) = 2.7 mg/kg) paw edema in rats after p.o. administration. In conclusion, SSR69071 is a selective, orally active, and potent inhibitor of HLE with good penetration in respiratory tissues.