Inhibition of Atherosclerosis and Liver Steatosis by Agmatine in Western Diet-Fed apoE-Knockout Mice Is Associated with Decrease in Hepatic De Novo Lipogenesis and Reduction in Plasma Triglyceride/High-Density Lipoprotein Cholesterol Ratio.

Atherosclerosis and NAFLD are the leading causes of death worldwide. The hallmark of NAFLD is triglyceride accumulation caused by an imbalance between lipogenesis de novo and fatty acid oxidation. Agmatine, an endogenous metabolite of arginine, exerts a protective effect on mitochondria and can modulate fatty acid metabolism. In the present study, we investigate the influence of agmatine on the progression of atherosclerotic lesions and the development of hepatic steatosis in apoE-/- mice fed with a Western high-fat diet, with a particular focus on its effects on the DNL pathway in the liver. We have proved that treatment of agmatine inhibits the progression of atherosclerosis and attenuates hepatic steatosis in apoE-/- mice on a Western diet. Such effects are associated with decreased total macrophage content in atherosclerotic plaque as well as a decrease in the TG levels and the TG/HDL ratio in plasma. Agmatine also reduced TG accumulation in the liver and decreased the expression of hepatic genes and proteins involved in lipogenesis de novo such as SREBP-1c, FASN and SCD1. In conclusion, agmatine may present therapeutic potential for the treatment of atherosclerosis and fatty liver disease. However, an exact understanding of the mechanisms of the advantageous actions of agmatine requires further study.

Endothelial injury is closely related to osteopontin and TNF receptor-mediated inflammation in end-stage renal disease.

BACKGROUND: Endothelial dysfunction, inflammation and active mineralization are key processes involved in cardiovascular burden in end stage renal disease (ESRD). Serum (soluble) thrombomodulin (sTM) is an established marker of endothelial injury. PATIENTS: 80 patients in ESRD were recruited consecutively. Baseline distribution of sex, age, main comorbidities and Framingham score was similar. A biochemical panel including sTM, intact PTH (iPTH), interleukin-6 (IL-6), pentraxin 3 (PTX3), fibroblast growth factor 23 (FGF-23), osteopontin (OPN), osteoprotegerin (OPG), osteocalcin (OC), osteonectin (ON), soluble tumor necrosis factor receptor type 2 (TNFR2), transforming growth factor-ß (TGF-ß), hepatocyte growth factor (HGF), vascular endothelial growth factor receptor type 2 (sVEGFR2) and stromal cell-derived factor 1α (SDF1α) was investigated in each patient. Samples obtained while establishing haemodialysis (HD) access were stained for radial artery calcifications (RACs) with Alizarin red and examined histologically. RESULTS: After adjustment for HD status, sTM showed a significant positive correlation with serum creatinine, TNFR2, OPN, HGF, SDF1α, sVEGFR2, Pi, iPTH, FGF-23, OPG, OC and ON. In forward stepwise multiple regression, serum creatinine, TNFR2, and OPN were identified as significant, independent predictors of sTM. Grades 1-3 of RACs correlated with sTM (R = 0.50, p = 0.017), while grade 3 RACs were significantly associated with higher sTM (p = 0.02) than less advanced lesions. CONCLUSION: Among novel renal and cardiovascular biomarkers, OPN and TNFR2 are closely related to sTM. This may link endothelial damage, vascular remodeling and inflammation. Progression of RAC parallels a presumed compensatory rise in sTM, reflecting endothelial injury. sTM has an intricate role in endothelial function and potential clinical and prognostic applications.

The Influence of Trehalose on Atherosclerosis and Hepatic Steatosis in Apolipoprotein E Knockout Mice.

Atherosclerosis and nonalcoholic fatty liver disease (NAFLD) are frequent causes of death in the Western countries. Recently, it has been shown that autophagy dysfunction plays an important role in the pathogenesis of both atherosclerosis and NAFLD; thus, activators of autophagy might be useful for novel therapeutic interventions. Trehalose-a naturally occuring disaccharide present in plants, bacteria, fungi, insects, and certain types of shrimps-is a known inducer of autophagy. However, according to the literature, its anti-atherosclerotic and anti-steatotic potential seem to depend on the experimental setting. The aim of our study was to comprehensively describe the influence of a prolonged treatment with orally administered trehalose on the development of atherosclerotic lesions and hepatic steatosis in apolipoprotein E knockout (apoE-/-) mice in an experimental set up reflecting both moderate and severe proatherogenic conditions: male apoE-/- mice on a chow diet (CD) and female apoE-/- mice fed with a high-fat diet (HFD). We found that exogenous trehalose inhibited atherosclerosis and attenuated hepatic steatosis in apoE-/- mice. Such effects of trehalose were not associated with changes of plasma cholesterol, low-density lipoproteins (LDL), or high-density lipoproteins (HDL). Moreover, the anti-steatotic action of trehalose in the liver was associated with the induction of autophagy. The exact molecular mechanisms of both the anti-atherosclerotic action of trehalose and its inhibitory effect on liver steatosis require further clarification.

Methodological approach for trace and essential elements assessment in prostate tissue by SRIXE method.

OBJECTIVE: The goal of this contribution is to present and familiarize the medical community with the method for the assessment of trace and essentials elements in prostate tissue sections. MATERIALS AND METHODS: X-ray fluorescence based technique(namely Synchrotron Induced X-ray Emission (SRIXE)) is described in terms of methodology, sample preparation and the evaluation of the recorded results (spectral data sets). Materials for the samples were collected from the patients underwent radical prostatectomy due to Adenocarcinoma prostatae. Specimens were freeze-dried, cut by microtome (to the thickness of 15 µm), one slice was placed on Mylar foil (for SRIXE measurements) and adjacent one on microscopic glass (for histopathological assessment). RESULTS: Results presented here show the usability of SRIXE method for the evaluation of concentration of trace and essential elements in prostate tissue sections with the spatial resolution better than 15 microns. DISCUSSION: Histopathological analysis of samples, which is only focused on morphological features, is unable to reveal information about changes in biochemical signature of tissues affected by the illness. SRIXE is a powerful and promising technique to analyse even very low concentrations oat the cellular level without any labelling or separating procedures. Obtained results may be correlated with classic histopathological assessment allowing for drawing conclusions on the changes in certain elements concentrations with the progression of disease. Moreover, mentioned in this work analysis, can be performed for any type of biological tissues.

Combined orcein and martius scarlet blue (OMSB) staining for qualitative and quantitative analyses of atherosclerotic plaques in brachiocephalic arteries in apoE/LDLR-/- mice.

Numerous cellular and extracellular components should be analyzed in sections of atherosclerotic plaques to assess atherosclerosis progression and vulnerability. Here, we combined orcein (O) staining for elastic fibers and martius scarlet blue (MSB) polychrome to visualize various morphological contents of plaque in brachiocephalic arteries (BCA) of apoE/LDLR-/- mice. Elastic fibers (including broken elastic laminae and 'buried' fibrous caps) were stained purple and they could be easily distinguished from collagen fibers (blue). Orcein allowed clear identification of even the finest elastic fibers. Erythrocytes were stained yellow and they could easily be discerned from mature fibrin (red). Old fibrin tends to acquire blue color. The method of OMSB staining is simple, takes less than 1 h to perform and can be adapted to automatic stainers. Most importantly, the color separation is good enough to allow digital automatic segmentation of specific components in tissue section and quantitative analysis of the plaque constituents. OMSB was used to compare atherosclerotic plaques in proximal and distal regions of BCA in apoE/LDLR-/- mice. In conclusion, OMSB staining represents a novel staining that could be routinely used for qualitative and quantitative microscopic assessments of formaldehyde-fixed and paraffin-embedded sections of arteries with atherosclerotic lesions.

Opioid Receptors in Psoriatic Skin: Relationship with Itch.

Psoriasis is an inflammatory immunogenetic skin disease, often accompanied by itch. Opioid receptors are known regulators of itch sensation in the central nervous system. In the brain, µ-opioid receptors may potentiate itch, while activation of κ-opioid receptors may reduce or even alleviate itch; however, the role of opioid receptors in itch perception in the skin is poorly understood. To further elucidate the role of opioid receptors in the neurobiology of psoriatic itch, punch biopsies of non-lesional and lesional skin of patients with psoriasis and healthy controls were studied. Real-time polymerase chain reaction and immunofluorescence microscopy were used to detect opioid receptor genes and protein expression, respectively. The OPRK1/κ-opioid receptor pathway was found to be downregulated in lesional skin of psoriasis, correlating positively with itch sensation. In contrast, the OPRM1/µ-opioid receptor system was uniformly expressed by epidermal keratinocytes in all analysed groups. These findings suggest that imbalance of epidermal opioid receptors may result in disordered neuroepidermal homeostasis in psoriasis, which could potentiate transmission of itch.

Anti-Atherosclerotic Action of Agmatine in ApoE-Knockout Mice.

Atherosclerosis is an inflammatory disease in which dysfunction of mitochondria play an important role, and disorders of lipid management intensify this process. Agmatine, an endogenous polyamine formed by decarboxylation of arginine, exerts a protective effect on mitochondria and modulates fatty acid metabolism. We investigated the effect of exogenous agmatine on the development of atherosclerosis and changes in lipid profile in apolipoprotein E knockout (apoE-/-) mice. Agmatine caused an approximate 40% decrease of atherosclerotic lesions, as estimated by en face and cross-section methods with an influence on macrophage but not on smooth muscle content in the plaques. Agmatine treatment did not changed gelatinase activity within the plaque area. What is more, the action of agmatine was associated with an increase in the number of high density lipoproteins (HDL) in blood. Real-Time PCR analysis showed that agmatine modulates liver mRNA levels of many factors involved in oxidation of fatty acid and cholesterol biosynthesis. Two-dimensional electrophoresis coupled with mass spectrometry identified 27 differentially expressed mitochondrial proteins upon agmatine treatment in the liver of apoE-/- mice, mostly proteins related to metabolism and apoptosis. In conclusion, prolonged administration of agmatine inhibits atherosclerosis in apoE-/- mice; however, the exact mechanisms linking observed changes and elevations of HDL plasma require further investigation.

Neonatal pinealectomy in rats - a simple micro-suction technique.

To determine the role of the pineal gland and its secretory product melatonin on various aspects of the functioning of the organism, the gland can be easily surgically removed in rats within 18 hours after birth. We performed pinealectomy in rats in a state of deep hypothermia under an operating microscope, using a micro-suction device of our own construction. The rats were induced into a state of suspended animation by placing them in the freezing compartment at minus 20 Celsius degrees. The cessation of respiration and heart beat lasted for about 15 minutes. During that time the pinealectomy was performed. In some cases there was minor hemorrhage that was easily controlled. There were no major side effects or mortality following surgery. All rats recovered within 15 minutes after the end of the procedure. The pinealectomy procedure described in this study is simple, rapid, effective and safe, and can be easily performed with instruments commonly available in most laboratories.

Non-standard Hubbard models in optical lattices: a review.

Originally, the Hubbard model was derived for describing the behavior of strongly correlated electrons in solids. However, for over a decade now, variations of it have also routinely been implemented with ultracold atoms in optical lattices, allowing their study in a clean, essentially defect-free environment. Here, we review some of the vast literature on this subject, with a focus on more recent non-standard forms of the Hubbard model. After giving an introduction to standard (fermionic and bosonic) Hubbard models, we discuss briefly common models for mixtures, as well as the so-called extended Bose-Hubbard models, that include interactions between neighboring sites, next-neighbor sites, and so on. The main part of the review discusses the importance of additional terms appearing when refining the tight-binding approximation for the original physical Hamiltonian. Even when restricting the models to the lowest Bloch band is justified, the standard approach neglects the density-induced tunneling (which has the same origin as the usual on-site interaction). The importance of these contributions is discussed for both contact and dipolar interactions. For sufficiently strong interactions, the effects related to higher Bloch bands also become important even for deep optical lattices. Different approaches that aim at incorporating these effects, mainly via dressing the basis, Wannier functions with interactions, leading to effective, density-dependent Hubbard-type models, are reviewed. We discuss also examples of Hubbard-like models that explicitly involve higher p orbitals, as well as models that dynamically couple spin and orbital degrees of freedom. Finally, we review mean-field nonlinear Schrödinger models of the Salerno type that share with the non-standard Hubbard models nonlinear coupling between the adjacent sites. In that part, discrete solitons are the main subject of consideration. We conclude by listing some open problems, to be addressed in the future.

Pre-processing of Fourier transform infrared spectra by means of multivariate analysis implemented in the R environment.

Pre-processing of Fourier transform infrared (FTIR) spectra is typically the first and crucial step in data analysis. Very often hyperspectral datasets include the regions characterized by the spectra of very low intensity, for example two-dimensional (2D) maps where the areas with only support materials (like mylar foil) are present. In that case segmentation of the complete dataset is required before subsequent evaluation. The method proposed in this contribution is based on a multivariate approach (hierarchical cluster analysis), and shows its superiority when compared to the standard method of cutting-off by using only the mean spectral intensity. Both techniques were implemented and their performance was tested in the R statistical environment - open-source platform - that is a favourable solution if the repeatability and transparency are the key aspects.

Cardiovascular risk in chronic kidney disease patients: intima-media thickness predicts the incidence and severity of histologically assessed medial calcification in radial arteries.

BACKGROUND: The objective of the study was to determine the relationship between common carotid artery intima-media thickness (CCA-IMT) and histologically assessed calcification of radial artery in relation to clinical features and laboratory markers of bone and mineral metabolism, inflammation, and oxidative stress in patients with stage 5 chronic kidney disease (CKD). METHODS: The study comprised 59 patients (36 hemodialyzed, 23 predialysis). CCA-IMT was measured by ultrasonography; the biochemical parameters examined were assessed using routine laboratory methods, ELISA micro-plate immunoassays and spectrophotometry. Fragments of radial artery obtained during creation of hemodialysis access were cryosectioned and stained for calcifications using von Kossa method and alizarin red. RESULTS: Glucose, osteoprotegerin, pentraxin 3 and Framingham risk score significantly correlated with CCA-IMT. In multiple regression analysis, OPG positively predicted CCA-IMT. Radial artery calcifications were found in 34 patients who showed higher CCA-IMT (0.98 ± 0.13 vs 0.86 ± 0.14 mm; P = 0.006). Higher CCA-IMT values were also associated with more advanced calcifications. CCA-IMT and the presence of plaques in common carotid artery were positive predictors of radial artery calcifications, independent of dialysis status, Framingham risk score, CRP and Ca x Pi [OR for calcifications 2.19 (1.08-4.45) per 0.1 mm increase in CCA-IMT]. The presence of radial artery calcifications was a significant predictor of mortality, independent of dialysis status and Framingham risk score [HR 3.16 (1.03-9.64)]. CONCLUSIONS: In CKD patients, CCA-IMT examination can be used as a surrogate measure to assess the incidence and severity of arterial medial calcification which is associated with poor clinical outcome in these patients.

Sodium Hydrosulfide Exerts a Transitional Attenuating Effect on Spermatozoa Migration in Vitro.

Hydrogen sulfide (H2S) has been shown to have a prominent role in the regulation of reproductive system function and fertility. The aim of the study was to assess the effect of a H2S donor, sodium hydrosulfide (NaHS), on mouse sperm migration in vitro. Special plates with 4 corner wells filled with balanced salt solution (control) and various NaHS solutions in concentrations of 2.5 mmol/l, 5 mmol/l or 10 mmol/l were applied. Spermatozoa from each male mouse were injected (the experiment was repeated with ten BALB/c 5-month old males) into the central pocket, connected with the wells with ducts. After 1 h, 2 h and 4 h of incubation, the number of spermatozoa in each well was determined using Bürker's counting chambers. The number ofspermatozoa in all corner wells were summed and the number of the cells in each well was treated as the percentage share of all the migrated spermatozoa. At the time points of 1 hour and 4 hours, no differences regarding chemotactic features of spermatozoa to the utilized solutions were observed. After two hours of incubation the attenuating effect of NaHS medium and high level solutions on spermatozoa migration was observed, but not for the low concentration mixture: H(3, N = 40) = 9.65, P = 0.022; control group vs 5 mmol/l NaHS solution: 36.0% vs 18.5%, P = 0.023; control group vs 10 mmol/l NaHS solution group: 36.0% vs 17.0%, P 0.011. In conclusion, NaHS has a transitional attenuating effect on spermatozoa migration in vitro.

Performance assessment and beamline diagnostics based on evaluation of temporal information from infrared spectral datasets by means of R Environment for statistical analysis.

Assessment of the performance and up-to-date diagnostics of scientific equipment is one of the key components in contemporary laboratories. Most reliable checks are performed by real test experiments while varying the experimental conditions (typically, in the case of infrared spectroscopic measurements, the size of the beam aperture, the duration of the experiment, the spectral range, the scanner velocity, etc.). On the other hand, the stability of the instrument response in time is another key element of the great value. Source stability (or easy predictable temporal changes, similar to those observed in the case of synchrotron radiation-based sources working in non top-up mode), detector stability (especially in the case of liquid nitrogen- or liquid helium-cooled detectors) should be monitored. In these cases, recorded datasets (spectra) include additional variables such as time stamp when a particular spectrum was recorded (in the case of time trial experiments). A favorable approach in evaluating these data is building hyperspectral object that consist of all spectra and all additional parameters at which these spectra were recorded. Taking into account that these datasets could be considerably large in size, there is a need for the tools for semiautomatic data evaluation and information extraction. A comprehensive R archive network--the open-source R Environment--with its flexibility and growing potential, fits these requirements nicely. In this paper, examples of practical implementation of methods available in R for real-life Fourier transform infrared (FTIR) spectroscopic data problems are presented. However, this approach could easily be adopted to many various laboratory scenarios with other spectroscopic techniques.

Adult tonsillectomy: anatomical differences affect postoperative transient hypernasality.

OBJECTIVE: Our purpose was to determine how anatomical conditions of the throat influence the degree and duration of posttonsillectomy transient hypernasality. PATIENTS AND METHODS: A total of 82 tonsillectomies were performed. The participants were divided into groups: 1 ­ small tonsils, high soft palate position; 4 ­ large tonsils, low soft palate position, and 2 and 3 ­ intermediate tonsil dimensions and soft palate positions. Variables studied included the diameter of vapor (DV) on the mirror positioned under the patient's nose while articulating nasal sentences before and after surgery, the distance from the uvular tip to the posterior pharyngeal wall, healing grading as well as the degree and duration of hypernasality. RESULTS: The mean hypernasality after tonsillectomy was greatest in group 4 and lowest in group 2. Before tonsillectomy, the mean DV was largest in group 2 and smallest in group 4. After tonsillectomy, the mean DV was largest in group 4 and smallest in group 3. Overall, the mean DV was significantly greater after tonsillectomy compared to the value before surgery. CONCLUSION: The degree of hypernasality after tonsillectomy depends on the soft palate position in relation to the tongue base and the size of the tonsils. Hypernasality is greatest in patients with large tonsils and a low soft palate position in relation to the tongue base.

Telocytes: new insight into the pathogenesis of gallstone disease.

The major mechanisms of gallstone formation include biliary cholesterol hypersecretion, supersaturation and crystallization, mucus hypersecretion, gel formation and bile stasis. Gallbladder hypomotility seems to be a key event that triggers the precipitation of cholesterol microcrystals from supersaturated lithogenic bile. Telocytes, a new type of interstitial cells, have been recently identified in many organs, including gallbladder. Considering telocyte functions, it is presumed that these cells might be involved in the signalling processes. The purpose of this study was to correlate the quantity of telocytes in the gallbladder with the lithogenicity of bile. Gallbladder specimens were collected from 24 patients who underwent elective laparoscopic cholecystectomy for symptomatic gallstone disease. The control group consisted of 25 consecutive patients who received elective treatment for pancreatic head tumours. Telocytes were visualized in paraffin sections of gallbladders with double immunofluorescence using primary antibodies against c-Kit (anti-CD117) and anti-mast cell tryptase. Cholesterol, phospholipid and bile acid levels were measured in gallbladder bile. The number of telocytes in the gallbladder wall was significantly lower in the study group than that in the control group (3.03 ± 1.43 versus 6.34 ± 1.66 cell/field of view in the muscularis propria, P < 0.001) and correlated with a significant increase in the cholesterol saturation index. The glycocholic and taurocholic acid levels were significantly elevated in the control subjects compared with the study group. The results suggest that bile composition may play an important role in the reduction in telocytes density in the gallbladder.

Tunneling-induced restoration of the degeneracy and the time-reversal symmetry breaking in optical lattices.

We study the ground-state properties of bosons loaded into the p band of a one-dimensional optical lattice. We show that the phase diagram of the system is substantially affected by the anharmonicity of the lattice potential. In particular, for a certain range of tunneling strength, the full many-body ground state of the system becomes degenerate. In this region, an additional symmetry of the system, namely, the parity of the occupation number of the chosen orbital, is spontaneously broken. The state with a nonvanishing staggered angular momentum, which breaks the time-reversal symmetry, becomes the true ground state of the system.

[Stem and progenitor cells in biostructure of blood vessel walls]. / Komórki macierzyste i progenitorowe w biostrukturze scian naczyn krwionosnych.

Development of vascular and hematopoietic systems during organogenesis occurs at the same time. During vasculogenesis, a small part of cells does not undergo complete differentiation but stays on this level, "anchored" in tissue structures described as stem cell niches. The presence of blood vessels within tissue stem cell niches is typical and led to identification of niches and ensures that they are functioning. The three-layer biostructure of vessel walls for artery and vein, tunica: intima, media and adventitia, for a long time was defined as a mechanical barrier between vessel light and the local tissue environment. Recent findings from vascular biology studies indicate that vessel walls are dynamic biostructures, which are equipped with stem and progenitor cells, described as vascular wall-resident stem cells/progenitor cells (VW-SC/PC). Distinct zones for vessel wall harbor heterogeneous subpopulations of VW-SC/PC, which are described as "subendothelial or vasculogenic zones". Recent evidence from in vitro and in vivo studies show that prenatal activity of stem and progenitor cells is not only limited to organogenesis but also exists in postnatal life, where it is responsible for vessel wall homeostasis, remodeling and regeneration. It is believed that VW-SC/PC could be engaged in progression of vascular disorders and development of neointima. We would like to summarize current knowledge about mesenchymal and progenitor stem cell phenotype with special attention to distribution and biological properties of VW-SC/PC in biostructures of intima, media and adventitia niches. It is postulated that in the near future, niches for VW-SC/PC could be a good source of stem and progenitor cells, especially in the context of vessel tissue bioengineering as a new alternative to traditional revascularization therapies.

Spontaneous solitons in the thermal equilibrium of a quasi-1D Bose gas.

We show that solitons occur generically in the thermal equilibrium state of a weakly interacting elongated Bose gas, without the need for external forcing or perturbations. This reveals a major new quality to the experimentally widespread quasicondensate state, usually thought of as primarily phase-fluctuating. Thermal solitons are seen in uniform 1D, trapped 1D, and elongated 3D gases, appearing as shallow solitons at low quasicondensate temperatures, becoming widespread and deep as temperature rises. This behavior can be understood via thermal occupation of the type II excitations in the Lieb-Liniger model of a uniform 1D gas. Furthermore, we find that the quasicondensate phase includes very appreciable density fluctuations while leaving phase fluctuations largely unaltered from the standard picture derived from a density-fluctuation-free treatment.

Functional alterations in endothelial NO, PGI2 and EDHF pathways in aorta in ApoE/LDLR-/- mice.

Adequate endothelial production of nitric oxide (NO), endothelium-derived hyperpolarizing factor (EDHF), and prostacyclin (PGI2) is critical to the maintenance of vascular homeostasis. However, it is not clear whether alterations in each of these vasodilatory pathways contribute to the impaired endothelial function in murine atherosclerosis. In the present study, we analyze the alterations in NO-, EDHF- and PGI2-dependent endothelial function in the thoracic aorta in relation to the development of atherosclerotic plaques in apoE/LDLR⁻/⁻ mice. We found that in the aorta of 2-month-old apoE/LDLR⁻/⁻ mice there was no lipid deposition, subendothelial macrophage accumulation; and matrix metalloproteinase (MMP) activity was low, consistent with the absence of atherosclerotic plaques. Interestingly, at this stage the endothelium was already activated and hypertrophic as evidenced by electron microscopy, while acetylcholine-induced NO-dependent relaxation in the thoracic aorta was impaired, with concomitant upregulation of cyclooxygenase-2 (COX-2)/PGI2 and EDHF (epoxyeicosatrienoic acids, EETs) pathways. In the aorta of 3-6-month-old apoE/LDLR⁻/⁻ mice, lipid deposition, macrophage accumulation and MMP activity in the intima were gradually increased, while impairment of NO-dependent function and compensatory upregulation of COX-2/PGI2 and EDHF pathways were more accentuated. These results suggest that impairment of NO-dependent relaxation precedes the development of atherosclerosis in the aorta and early upregulation of COX-2/PGI2 and EDHF pathways may compensate for the loss of the biological activity of NO.

Modelling quantum aspects of disruption of a white dwarf star by a black hole.

We study the final stages of the evolution of a binary system consisted of a black hole and a white dwarf star. We implement the quantum hydrodynamic equations and carry out numerical simulations. As a model of a white dwarf star we consider a zero temperature droplet of attractively interacting degenerate atomic bosons and spin-polarized atomic fermions. Such mixtures are investigated experimentally nowadays. We find that the white dwarf star is stripped off its mass while passing the periastron. Due to nonlinear effects, the accretion disk originated from the white dwarf becomes fragmented and the onset of a quantum turbulence with giant quantized vortices present in the bosonic component of the accretion disk is observed. The binary system ends its life in a spectacular way, revealing quantum features underlying the white dwarf star's structure. We find a charged mass, falling onto a black hole, could be responsible for recently discovered ultraluminous X-ray bursts. The simulations show that final passage of a white dwarf near a black hole can cause a gamma-ray burst.