Natural killer cell-mediated contact dermatitis-like reaction induced by treatment with TLR3 ligand poly(I:C)

INTRODUCTION

Poly(I:C) is recognised by endosomal Toll-like receptor 3 (TLR3) and activates cytotoxic CD8(+) lymphocytes and natural killer (NK) cells. It has been shown that the viral TLR3 agonist induces robust and long-lasting T-cell-mediated responses. In addition, TLR3 modulates the contact hypersensitivity reaction.

OBJECTIVE

This study aimed to determine whether poly(I:C) injection can induce NK-mediated hapten reactivity in mice.

METHODS

Mice were treated with poly(I:C), and their response to dinitrofluorobenzene hapten was measured by assessing ear swelling and serum interferon gamma (IFN-γ) production. Adoptive cell transfer and cell sorting were used to investigate the mechanism of the reaction, and the phenotype of poly(I:C)-activated liver NK cells was determined by flow cytometry analysis.

RESULTS

The results showed that poly(I:C) administration increased ear swelling, serum IFN-γ levels and the response to hapten in both immunocompetent and T- and B-cell-deficient mice. Only liver poly(I:C)-activated DX5(+) NK cells were able to transfer reactivity to hapten into a naive recipient. Induction of liver NK cells after poly(I:C) administration was TLR3/TRIF- and IFN-γ-dependent, interleukin 12-independent, and not modulated by MyD88.

CONCLUSION

This study provides new insights into how poly(I:C) stimulates NK-mediated reactivity to hapten and suggests that liver NK cells may modulate the immune response to non-pathogenic factors during viral infection.

Obesity aggravates contact hypersensitivity reaction in mice

BACKGROUND

Obesity is associated with chronic, low-grade inflammation in tissues and predisposes to various complications, including inflammatory skin diseases. However, the link between obesity and contact hypersensitivity (CHS) is not fully understood.

OBJECTIVES

We sought to determine the influence of obesity on T helper 1 (Th1)-mediated CHS.

METHODS

The activity/phenotype/cytokine profile of the immune cells was tested in vivo and in vitro. Using quantitative polymerase chain reaction (qPCR) and fecal microbiota transplantation (FMT), we tested the role of a high-fat diet (HFD)-induced gut microbiota (GM) dysbiosis in increasing the effects of CHS.

RESULTS

Exacerbated CHS correlates with an increased inflammation-inducing GM in obese mice. We showed a proinflammatory milieu in the subcutaneous adipose tissue of obese mice, accompanied by proinflammatory CD4+ T cells and dendritic cells in skin draining lymph nodes and spleen. Obese interleukin (IL)-17A-/-B6 mice are protected from CHS aggravation, suggesting the importance of IL-17A in CHS aggravation in obesity.

CONCLUSIONS

Obesity creates a milieu that induces more potent CHS-effector cells but does not have effects on already activated CHS-effector cells. IL-17A is essential for the pathogenesis of enhanced CHS during obesity. Our study provides novel knowledge about antigen-specific responses in obesity, which may help with the improvement of existing treatment and/or in designing novel treatment for obesity-associated skin disorders.

MEDB-26. Outcomes of children with standard-risk and high-risk medulloblastoma treated with pre-irradiation chemotherapy and risk-adapted craniospinal irradiation: a report on patients from the Polish Pediatric Neuro-oncology Group

BACKGROUND: The last two decades have witnessed several efforts to minimize the adverse sequelae of craniospinal irradiation (CSI), a standard of care treatment modality in medulloblastoma. This has been accomplished by adding chemotherapy to the treatment backbone. The use of pre-irradiation chemotherapy has also been previously reported. In one of the largest studies to date, we analyze treatment outcomes in children with standard and high-risk medulloblastoma treated with pre-irradiation chemotherapy followed by reduced-dose radiotherapy in SR and maintenance chemotherapy. METHODS: Data from the Polish Pediatric Neuro-oncology Group (PPNG) was analyzed in patients greater than 3 years of age with newly-diagnosed medulloblastoma. RESULTS : Among 138 patients, median age at diagnosis was 7.9 years and median follow-up was 5.5 years. Comprehensive molecular subgrouping was not available for all patients at the time of data collection. Of 60 standard-risk patients, there was pre-irradiation disease recurrence in one patient. One patient expired prior to radiation due to metastatic disease. Of 78 high-risk patients, one had pre-irradiation recurrence. Overall survival (OS) for high-risk patients at 3 and 5 years (± standard error) was 89.2 ± 4.0% and 81.3 ± 5.8%, respectively. OS for standard-risk patients at 3 and 5 years was 92.5 ± 3.8% and 88.2 ± 5.1%, respectively. Among high-risk patients, event-free survival (EFS) at 3 and 5 years was 82.5 ± 5.3% and 81.0 ± 5.6%. Among standard-risk patients, 3-year EFS was 89.2 ± 4.6% and 5-year EFS was 86.8 ± 5.3%. CONCLUSION : This study demonstrates promising survival outcomes in pediatric medulloblastoma patients treated with pre-irradiation chemotherapy followed by reduced-dose CSI and adjuvant chemotherapy. Such an approach may be helpful if delays in starting radiotherapy are expected, which is usually the case in many institutions around the globe.

Diet-induced obesity aggravates NK cell-mediated contact hypersensitivity reaction in Rag1-/- mice

BACKGROUND

Previous studies showed that natural killer (NK) cells mediate contact hypersensitivity (CHS) reaction. Many reports are showing that obesity promotes several inflammatory diseases. It was shown that diet-induced obesity (DIO) aggravates classical T cell-mediated CHS in mice.

OBJECTIVES

To determine whether the high-fat diet (HFD)-induced obesity modulates antigen-specific NK cell-mediated response.

METHODS

We evaluated the effect of DIO on NK cell-mediated CHS reaction using a model of dinitrofluorobenzene (DNFB)-induced CHS in Rag1-/- mice.

RESULTS

Rag1-/- mice fed HFD for 8 but not for 4 weeks developed aggravated CHS reaction determined by ear swelling measurement when compared to animals kept on normal diet (ND) prior to DNFB sensitization. The obese Rag1-/- mice presented the adipose tissue inflammation. Furthermore, in vitro analysis showed that feeding with HFD significantly increases interferon γ (IFN-γ) and interleukin (IL)-12p70 and decreases adiponectin concentration in liver mononuclear cell (LMNC) culture supernatants. The flow cytometry analysis of LMNC revealed that HFD treatment prior to DNFB sensitization increases the percentage of NK1.1+ IFN-γ+ cell population and affects the development and maturation of NK1.1+ cells.

CONCLUSIONS

In summary, current results suggest that the DIO significantly modulates the local and systemic inflammatory response, contributing to exacerbation of the CHS response mediated by liver NK cells.

Biosorption as a method of biowaste valorization to feed additives: RSM optimization

The aim of this work was to prepare an innovative microelemental feed additive for laying hens, based on waste biomass from the agricultural sector (alfalfa and goldenrod after CO₂ extraction in supercritical state). The process was optimized by Response Surface Methodology (RSM) and the most favourable enrichment conditions were selected for Cu(II), Mn(II) and Zn(II) ions: pH - 5, sorbate concentration of Cu(II), Mn(II), Zn(II) - 10.0 mg/L for alfalfa and 10.7 mg/L for goldenrod and biomass dose - 0.1 g/L. Physicochemical properties of biomass were studied and functional groups involved in the binding of Cu(II), Mn(II), Zn(II) ions were determined (mainly carboxylic and hydroxylic groups). An interesting and unique element of this work is the verification of the properties of prepared feed additives in conditions simulating the digestive tract of animals. The release of components in solutions simulating conditions in the intestine and stomach (pH 11 and pH 1) was tested (in vitro tests). The best desorption results were achieved at a strongly acidic pH which corresponds to the stomach environment: 9.80, 14.4% Cu(II), 69.0, 66.9% (Zn), 46.5, 31.9 Mn(II) for alfalfa and goldenrod, respectively. It was concluded that the biomass enriched with micronutrients in biosorption has the potential as a feed additive for sustainable agriculture.

1,2,3,4,6-Penta-O-galloyl-β-d-glucose modulates perivascular inflammation and prevents vascular dysfunction in angiotensin II-induced hypertension

Background and Purpose

Hypertension is a multifactorial disease, manifested by vascular dysfunction, increased superoxide production, and perivascular inflammation. In this study, we have hypothesized that 1,2,3,4,6‐penta‐O‐galloyl‐β‐d‐glucose (PGG) would inhibit vascular inflammation and protect from vascular dysfunction in an experimental model of hypertension.

Experimental Approach

PGG was administered to mice every 2 days at a dose of 10 mg·kg⁻¹ i.p during 14 days of Ang II infusion. It was used at a final concentration of 20 μM for in vitro studies in cultured cells.

Key Results

Ang II administration increased leukocyte and T‐cell content in perivascular adipose tissue (pVAT), and administration of PGG significantly decreased total leukocyte and T‐cell infiltration in pVAT. This effect was observed in relation to all T‐cell subsets. PGG also decreased the content of T‐cells bearing CD25, CCR5, and CD44 receptors and the expression of both monocyte chemoattractant protein 1 (CCL2) in aorta and RANTES (CCL5) in pVAT. PGG administration decreased the content of TNF⁺ and IFN‐γ⁺ CD8 T‐cells and IL‐17A⁺ CD4⁺ and CD3⁺CD4⁻CD8⁻ cells. Importantly, these effects of PGG were associated with improved vascular function and decreased ROS production in the aortas of Ang II‐infused animals independently of the BP increase. Mechanistically, PGG (20 μM) directly inhibited CD25 and CCR5 expression in cultured T‐cells. It also decreased the content of IFN‐γ⁺ CD8⁺ and CD3⁺CD4⁻CD8⁻ cells and IL‐17A⁺ CD3⁺CD4⁻CD8⁻ cells.

Conclusion and Implication

PGG may constitute an interesting immunomodulating strategy in the regulation of vascular dysfunction and hypertension.

Linked Articles

This article is part of a themed section on Immune Targets in Hypertension. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.12/issuetoc

Cyclophosphamide-modified murine peritoneal macrophages induce CD4+ T contrasuppressor cells that protect contact sensitivity T effector cells from suppression

BACKGROUND

Cyclophosphamide (CY) is one of the most widely used alkylating agents in the treatment of various cancers and some autoimmune diseases. Numerous reports suggest that CY exerts immunoregulatory effects. Animal studies have shown CY affects contact sensitivity (CS) response by depleting CD4⁺CD25⁺ T regulatory cells and CD8⁺ T suppressor (Ts) cells. In a mouse model of CS, we previously showed that in vivo treatment with CY shapes the immunogenic/immunoregulatory balance of peritoneal macrophages. The aim of the current study is to verify if macrophages (Mf) from CY-treated mice are indeed able to induce immunoregulatory cells that could protect from suppression.

METHODS

Adoptive cell transfer of CS was used to examine immunomodulating properties of peritoneal Mf from CY-treated mice. Isolation of peritoneal Mf from animals that were (Mf-CY) or were not (Mf) treated with CY were cultured to identify cytokine repertoire. Further, we assessed spleen cell (SPLC) cytokine production following immunization with trinitrophenyl-conjugated Mf from donors treated (TNP-Mf-CY) or non-treated (TNP-Mf) with CY.

RESULTS

In vitro experiments identified that Mf-CY produce more IL-6, TNF-α and TGF-β than naïve Mf. Further, immunization with peritoneal TNP-Mf-CY induces CD4⁺ T contrasuppressor cells (Tcs) cells that protect CS-effector cells from suppression. Higher IL-17A secretion was observed from TNP-Mf-CY-treated mouse SPLC compared to SPLC from TNP-Mf injected mice suggesting that this cytokine might be important in mediating contrasuppression in this model.

CONCLUSIONS

Our results show that in vivo treatment with CY influences mouse peritoneal Mf to induce CD4+ Tcs cells that protect CS-effector cells from suppressive signals of Ts cells.

Regulation of contact sensitivity in non-obese diabetic (NOD) mice by innate immunity

BACKGROUND

Genetic background influences allergic immune responses to environmental stimuli. Non-obese diabetic (NOD) mice are highly susceptible to environmental stimuli. Little is known about the interaction of autoimmune genetic factors with innate immunity in allergies, especially skin hypersensitivity.

OBJECTIVES

To study the interplay of innate immunity and autoimmune genetic factors in contact hypersensitivity (CHS) by using various innate immunity-deficient NOD mice.

METHODS

Toll-like receptor (TLR) 2-deficient, TLR9-deficient and MyD88-deficient NOD mice were used to investigate CHS. The cellular mechanism was determined by flow cytometry in vitro and adoptive cell transfer in vivo. To investigate the role of MyD88 in dendritic cells (DCs) in CHS, we also used CD11c^MyD88+  MyD88^-/- NOD mice, in which MyD88 is expressed only in CD11c⁺ cells.

RESULTS

We found that innate immunity negatively regulates CHS, as innate immunity-deficient NOD mice developed exacerbated CHS accompanied by increased numbers of skin-migrating CD11c⁺ DCs expressing higher levels of major histocompatibility complex II and CD80. Moreover, MyD88^-/- NOD mice had increased numbers of CD11c⁺  CD207^-  CD103⁺ DCs and activated T effector cells in the skin-draining lymph nodes. Strikingly, re-expression of MyD88 in CD11c⁺ DCs (CD11c^MyD88+  MyD88^-/- NOD mice) restored hyper-CHS to a normal level in MyD88^-/- NOD mice.

CONCLUSION

Our results suggest that the autoimmune-prone NOD genetic background aggravates CHS regulated by innate immunity, through DCs and T effector cells.

Inflammation increases oxidative DNA damage repair and stimulates preneoplastic changes in colons of newborn rats

Oxidative DNA damage may be a risk factor for development of various pathologies, including malignancy. We studied inflammation triggered modulation of repair activity in the intestines of three weeks old rats injected i.p. with E.coli or S. typhimurium lipopolysaccharides (LPS) at doses of 1, 5 or 10 mg/kg. Subsequent formation in these animals of colonic preneoplastic lesions, aberrant crypt foci (ACF) was also investigated. Five days after LPS administration no differences were observed in repair rate of 1,N(6)-ethenoadenine (εA), 3,N(4)-ethenocytosine (εC) and 8-oxoguanine (8-oxoG) in intestines of these rats, as measured by the nicking assay. However a significant increase in all three repair activities was found within one and two months after S. typhimurium LPS treatment. E. coli LPS significantly increased only the 8-oxoG repair. S. typhimurium LPS stimulated mRNA transcription of pro-inflammatory proteins, lipooxygenase-12 and cyclooxygenase-2, as well as some DNA repair enzymes like AP-endonuclease (Ape1) and εC-glycosylase (Tdg). mRNA level of DNA glycosylases excising εA (MPG) and 8-oxoG (OGG1) was also increased by LPS treatment, but only at the highest dose. Transcription of all enzymes increased for up to 30 days after LPS, and subsequently decreased to the level observed before treatment, with the exception of APE1, which remained elevated even two months after LPS administration. Thus, the repair efficiency of εA, εC and 8-oxoG depends on the availability of APE1, which increases OGG1 and TDG turnover on damaged DNA, and presumably stimulates MPG. One and two months after administration of E. coli or S. typhimurium LPS, the number of aberrant crypt foci in rat colons increased in a dose and time dependent manner. Thus, inflammation stimulates the repair capacity for εA, εC and 8-oxoG, but simultaneously triggers the appearance of preneoplastic changes in the colons. This may be due to increased oxidative stress and imbalance in DNA repair.

Epicutaneous (EC) immunization with type II collagen (COLL II) induces CD4(+) CD8(+) T suppressor cells that protect from collagen-induced arthritis (CIA)

BACKGROUND

We have shown previously that epicutaneous (EC) immunization with protein antigen induces T suppressor cells that alleviate inflammatory response in contact hypersensitivity reactions, in an animal model of multiple sclerosis, and in TNBS-induced colitis.

METHODS

DBA/1 mice were EC immunized with type II collagen (COLL II) spread over a gauze patch on days 0 and 4. On day 7, patches were removed and mice were intradermally (id) immunized with COLL II in CFA to induce collagen-induced arthritis (CIA).

RESULTS

Our work shows that EC immunization with 100μg of COLL II prior to CIA induction reduces disease severity as determined by macroscopic evaluation. Reduced disease severity after EC immunization with COLL II correlates with milder histological changes found in joint sections. Experiments with the three non-cross-reacting antigens COLL II, ovalbumin (OVA) and myelin basic protein (MBP) showed that skin-induced suppression is antigen non-specific. Transfer experiments show that EC immunization with COLL II induces suppressor cells that belong to the population of CD4(+) CD8(+) double positive lymphocytes. Flow cytometry experiments showed increased percentage of CD4(+) CD8(+) RORγt(+) cells in axillary and inguinal lymph nodes isolated from mice patched with COLL II.

CONCLUSION

Maneuver of EC immunization with a protein antigen that induces suppressor cells to inhibit inflammatory responses may become an attractive, noninvasive, needle-free therapeutic method for different clinical situations.

GABA system as a target for new drugs

4-Aminobutyric acid is an inhibitory neurotransmitter involved in the control of neuronal activity in the mammalian central nervous system. There is considerable direct and indirect evidence that impaired activity of GABAmediated inhibitory synapses may be an important causative factor in experimental and clinical seizure disorders. This review is focused on the recent development of compounds which can influence GABA neurotransmission by affecting the GABA receptors, the plasma-membrane GABA transporters (GATs) and catabolic enzyme GABA-transaminase (GABAT). These compounds have been primarily investigated in relation to epilepsy, but it has also been found that a decrease in GABA neurotransmission appears to be involved in the aetiology of several neurological disorders such as insomnia, spasticity, neuropathic pain, anxiety and other mental disorders.

Analysis of microstructured optical fibers using compact macromodels

In this paper a new technique for numerical analysis of microstructured optical fibers is proposed. The technique uses a combination of model order reduction method and discrete function expansion technique. A significant reduction of the problem size is achieved (by about 85%), which results in much faster simulations (up to 16 times) without affecting the accuracy.

Experimental investigation of electronic states of LiCs dissociating to Li(2(2)S) and Cs(5(2)D) atoms

Polarization labeling spectroscopy technique was used to measure excitation spectra of LiCs molecule in the spectral range of 16,000-18,500 cm(-1). Four band systems were observed and assigned to transitions from the ground X(1)Σ(+) state to excited states (4)Ω = 0(+), (5)Ω = 0(+), (5)Ω = 1, and (6)Ω = 1 (in Hund's case (c) notation proper here), the latter three states being fine structure components of the states d(3)Π and e(3)Σ(+), nominally of triplet symmetry. The observed states are characterized spectroscopically and the experimental results are compared with predictions of theoretical calculations, showing accuracy of the theoretical electronic term values better than 100 cm(-1) and of the ω(e) and R(e) constants within 5%.

Boundary-equilibrium bifurcations in piecewise-smooth slow-fast systems

In this paper we study the qualitative dynamics of piecewise-smooth slow-fast systems (singularly perturbed systems) which are everywhere continuous. We consider phase space topology of systems with one-dimensional slow dynamics and one-dimensional fast dynamics. The slow manifold of the reduced system is formed by a piecewise-continuous curve, and the differentiability is lost across the switching surface. In the full system the slow manifold is no longer continuous, and there is an O(ɛ) discontinuity across the switching manifold, but the discontinuity cannot qualitatively alter system dynamics. Revealed phase space topology is used to unfold qualitative dynamics of planar slow-fast systems with an equilibrium point on the switching surface. In this case the local dynamics corresponds to so-called boundary-equilibrium bifurcations, and four qualitative phase portraits are uncovered. Our results are then used to investigate the dynamics of a box model of a thermohaline circulation, and the presence of a boundary-equilibrium bifurcation of a fold type is shown.

The potential energy barrier of the 2(1)Pi state in KLi

The polarisation labelling spectroscopy technique has provided detailed information about the shape of the potential barrier to dissociation of the 2(1)Pi state in KLi. The potential curve of the 2(1)Pi state is constructed using the Inverted Perturbation Approach method. Our analysis shows that the barrier height is DeltaE=20.8+/-1.0 cm(-1) relative to the dissociation limit and the barrier maximum is located at Rbar=8.2+/-0.1 A.

Polarization labeling spectroscopy of highly excited 1Pi and 1Sigma+ states in NaLi

Two previously unknown (1)Pi states and one (1)Sigma(+) state of NaLi are experimentally investigated in the energy region of 34,000-36,000 cm(-1) above the bottom of the molecular ground state potential well by using polarization labeling spectroscopy technique. Potential energy curves are deduced for all three states from the observed rovibrational levels. The identity of the observed states is discussed in relation with the recently published theoretical calculations on electronic structure of NaLi by Petsalakis et al. [J. Chem. Phys. 129, 054306 (2008)] and Mabrouk and Berriche [J. Phys. B41, 155101 (2008)].

A new conformal radiation boundary condition for high accuracy finite difference analysis of open waveguides

A highly accurate radiation boundary condition for finite difference analysis of open waveguides is introduced. The boundary condition is applicable to the structures embedded in a homogeneous medium and fitted to the cross section of the structure. The numerical tests carried out for a few types of waveguides including microstructured fibers showed that the proposed approach improves the accuracy by about an order of magnitude in comparison with the PML technique and eliminates all its disadvantages.

A full analytic potential energy curve for the a 3 Sigma+ state of KLi from a limited vibrational data set

Fourier transform spectra of near-infrared laser-induced fluorescence in (39)K(6)Li show transitions to high vibrational levels of both the X (1)Sigma(+) and a (3)Sigma(+) electronic states. These include 147 transitions into six vibrational levels of the a (3)Sigma(+) state, which lie between 7 and 88 cm(-1) below the dissociation asymptote. Unfortunately, their energies span less than 30% of the well depth. However, fitting those data to eigenvalues of analytical model potential functions whose outer limbs incorporate the theoretically predicted long-range form, V(R) approximately D-C(6)R(6)-C(8)R(8), yields complete, plausible potential curves for this state. The best fits converge to remarkably similar solutions which indicate that D(e)=287(+/-4) cm(-1) and R(e)=4.99(+/-0.09) A for the a (3)Sigma(+) state of KLi, with omega(e)=47.3(+/-1.4) and 44.2(+/-1.5) cm(-1) for (39)K(6)Li and (39)K(7)Li, respectively. Properties of the resulting potential are similar to those of a published ab initio potential and are consistent with those of the analogous states of Li(2), K(2), Na(2), and NaK.

Modulation of oxidative DNA damage repair by the diet, inflammation and neoplastic transformation

Oxidative DNA damage and DNA repair may mediate several cellular processes, like replication and transcription, mutagenesis and apoptosis and thus may be important for the organism development as well as its pathogenesis, including cancer. Activity of DNA repair enzymes can depend on many factors, such as gene polymorphism, mRNA and protein level, as well as enzymes activation and inhibition. Modulation of base excision repair pathway eliminating from DNA oxidatively formed lesions may be caused by the diet, inflammation and neoplastic transformation. Reactive oxygen species and some diet components induce transcription of several Base Excision Repair enzymes, e.g. major human AP-endonuclease, (APE1) and 8-oxoG-DNA glycosylase (OGG1). The carcinogenic process in human lung decreases repair activity for 8-oxoGin transcription independent manner, but increases repair activity of epsilon A and epsilon C, as measured in tumors and unchanged lung tissues of lung cancer patients. Thus, modulation of repair enzymes activities may be a cell response on their way to differentiation ot neoplastic transformation.

Experimental long range potential of the BΠ1 state in NaRb

The long range potential of the B 1Pi state in NaRb has been investigated by observation of rovibrational levels that it supports, including the high lying ones, with the technique of polarization labeling spectroscopy. This has allowed us to characterize the potential energy curve up to 1.9 cm(-1) from the dissociation limit. The highest observed rovibrational level v=49, J=10 has the outer turning point at R=16.48 A.

Efficient finite difference analysis of microstructured optical fibers

A new technique of numerical analysis of microstructured optical fibers is presented. The technique combines a standard 2D finite difference equations with the discrete function expansion. By doing this one gets a matrix eigenvalue problem of a smaller size and a simple formulation of radiation boundary condition. The new algorithm was tested for the microstructures of different types and excellent agreement of the obtained results with other methods was achieved.

A regularized inverted perturbation approach method: Potential energy curve of the 4 1Σu+ state in Na2

We describe a modification of the inverted perturbation approach method allowing to construct physically sensible potential energy curves for electronic states of diatomic molecules even when some parts of the potential are not adequately characterized by the experimental data. The method is based on a simple regularization procedure, imposing an additional constraint on the constructed potential curve. In the present work it is applied to the double minimum 4 (1)Sigma(u) (+) state of Na(2), observed experimentally by polarization labeling spectroscopy technique.

Adsorption energy distribution from the Aranovich-Donohue lattice density functional theory

We propose a new methodology projected for the estimation of the adsorption energy distribution from the monolayer part of a single nitrogen adsorption isotherm determined at 77 K based on the lattice density functional theory (DFT) via the Aranovich-Donohue formalism. At first sight, the presented approach is computationally more difficult than a classical one. However, it is more flexible and comprehensible. Next, we developed a numerical program and used it for the estimation of the adsorption energy distribution from the experimental data on carbon black samples. The main nitrogen molecule-carbon black surface interaction energy can be estimated as approximately 7-8 kJ/mol, but the heterogeneity of the investigated materials differs significantly. Furthermore, we compare the results obtained from the lattice DFT via the Aranovich-Donohue formalism with the solution of the integral equation with the kernel represented by the classical monolayer localized Fowler-Guggenheim isotherm equation. The similarity between these two independent approaches is observed. The proposed methodology can be used for the investigation of the energetic heterogeneity of not only the carbonaceous materials but also the other "flat-surfaced" solids.

Influence of the stimulation of central chemoreceptors on the gastric mucosal blood flow in artificially ventilated and spontaneously breathing rats

Respiratory failure coincides frequently with the occurrence of gastric ulceration. In advanced respiratory insufficiency hypoxemia is often accompanied by hypercapnia, which is the stimulus for central chemoreceptors as well as for carotid body chemoreceptors. The purpose of the work was to investigate the reflex effect of stimulation of central chemoreceptors on gastric mucosal blood flow (GMBF) in the rat. Central chemoreceptors were stimulated by a gas mixture composed of 10% carbon dioxide, 50% oxide and 40% nitrogen. In artificially ventilated and spontaneously breathing animals, the stimulation of central chemoreceptors caused a significant increase in gastric mucosal vascular resistance, accompanied by a marked decline in blood flow. We hypothesize that in patients with respiratory insufficiency accompanied by hypercapnia, the reflex impairment of GMBF may contribute to gastric ulceration.

[Evaluation of effects of L-thyroxine therapy in differentiated thyroid carcinoma on the cardiovascular system --prospective study]

Patients with differentiated thyroid carcinoma are treated by thyreoidectomy, followed by radioiodine treatment. A life-time suppressive therapy with L-thyroxine is also indicated. However, it may cause cardiovascular side effects. The aim of the study was a prospective evaluation of the left ventricle hypertrophy in patients treated with suppressive doses of thyroxine. A significant rise in left ventricular mass and mass index was noted during the first year of therapy and could be prevented by a simultaneous treatment with low doses of bisoprolol.

Influence of the stimulation of carotid body chemoreceptors on the gastric mucosal blood flow in artificially ventilated and spontaneously breathing rats

The cardiovascular effects of the stimulation of arterial chemoreceptors are different in spontaneously breathing and artificially ventilated animals. Respiratory failure and long term sojourn at high altitude coincide frequently with the occurrence of gastric ulceration. In both these situations a profound stimulation of arterial chemoreceptors is present. The purpose of the paper was to investigate the reflex effect of stimulation carotid chemoreceptors on gastric mucosal blood flow in the rat. Arterial chemoreceptors were stimulated by two methods (I) substitution gas mixture of 10% oxygen in nitrogen for room air and (II) direct injection of acid saline ( 0.05 ml, pH = 6.8) into the distal part of left common carotid artery. In artificially ventilated rats stimulation of arterial chemoreceptors caused significant increase in gastric mucosal vascular resistance, accompanied by marked decline in blood flow. This effect was mediated by adrenergic mechanism. On the contrary to artificially ventilated rats, decline of gastric mucosal vascular resistance with concomitant increase in blood flow was found in spontaneously breathing animals. This effect was not abolished either by phentolamine or atropine. As vasodilatatory effect of arterial chemoreceptors stimulation was abolished by bilateral vagotomy, we postulate that non adrenergic and non cholinergic vagal fibers mediate observed vascular changes in gastric mucosa in spontaneously breathing rats. We hypothesize that in artificially ventilated patients with respiratory failure stimulation of arterial chemoreceptors by hypoxemia and or acidosis may contribute to the development of gastric mucosal lesions.