Vascular reactivity stimulated by TMA and TMAO: Are perivascular adipose tissue and endothelium involved?

Trimethylamine (TMA), formed by intestinal microbiota, and its Flavin-Monooxygenase 3 (FMO3) product Trimethylamine-N-Oxide (TMAO), are potential modulators of host cardiometabolic phenotypes. High circulating levels of TMAO are associated with increased risk for cardiovascular diseases. We hypothesized that TMA/TMAO could directly change the vascular tone. Perivascular adipose tissue (PVAT) helps to regulate vascular homeostasis and may also possess FMO3. Thoracic aorta with(+) or without(-) PVAT, also + or - the endothelium (E), of male Sprague Dawley rats were isolated for measurement of isometric tone in response to TMA/TMAO (1nM-0.5 M). Immunohistochemistry (IHC) studies were done to identify the presence of FMO3. TMA and TMAO elicited concentration-dependent arterial contraction. However, at a maximally achievable concentration (0.2 M), contraction stimulated by TMA was of a greater magnitude (141.5 ± 16% of maximum phenylephrine contraction) than that elicited by TMAO (19.1 ± 4.03%) with PVAT and endothelium intact. When PVAT was preserved, TMAO-induced contraction was extensively reduced the presence (19.1 ± 4.03%) versus absence of E (147.2 ± 20.5%), indicating that the endothelium plays a protective role against TMAO-induced contraction. FMO3 enzyme was present in aortic PVAT, but the FMO3 inhibitor methimazole did not affect contraction stimulated by TMA in aorta + PVAT. However, the l-type calcium channel blocker nifedipine reduced TMA-induced contraction by ∼50% compared to the vehicle. Though a high concentration of these compounds was needed to achieve contraction, the findings that TMA-induced contraction was independent of PVAT and E and mediated by nifedipine-sensitive calcium channels suggest metabolite-induced contraction may be physiologically important.

Hydrocarbon decomposition kinetics on the Ir(111) surface.

The kinetics of the thermal decomposition of hydrocarbons on the Ir(111) surface is determined using kinetic Monte Carlo (kMC) and rate equations simulations, both based on the density functional theory (DFT) calculated energy barriers of the involved reaction processes. This decomposition process is important for understanding the early stages of epitaxial graphene growth where the deposited hydrocarbon acts as a carbon feedstock for graphene formation. The methodology of the kMC simulations and the rate equation approaches is discussed and a comparison between the results obtained from both approaches is made in the case of the temperature programmed decomposition of ethylene for different initial coverages. The theoretical results are verified against experimental data from in situ X-ray photoelectron spectroscopy (XPS) experiments. Both theoretical approaches give reasonable results; however we find that, as expected, rate equations are less reliable at high coverages. We find that the agreement between experiment and theory can be improved in all cases if slight adjustments are made to the energy barriers in order to account for the intrinsic errors in DFT. Finally we extend our approach to the case where hydrocarbon species are dosed onto the substrate continuously, as in the chemical vapour deposition (CVD) graphene growth method. For ethylene and methane the thermal decomposition mechanism is determined, and it is found that in both cases the formation of C monomers is to be expected, which is limited by the presence of hydrogen atoms.

Human nail plate modifications induced by onychomycosis: implications for topical therapy.

PURPOSE: Through the characterisation of the human onchomycotic nail plate this study aimed to inform the design of new topical ungual formulations. METHODS: The mechanical properties of the human nail were characterised using a Lloyd tensile strength tester. The nail's density was determined via pycnometry and the nail's ultrastructure by electron microscopy. Raman spectroscopy analysed the keratin disulphide bonds within the nail and its permeability properties were assessed by quantifying water and rhodamine uptake. RESULTS: Chronic in vivo nail plate infection increased human nailplate thickness (healthy 0.49 ± 0.15 mm; diseased 1.20 ± 0.67 mm), but reduced its tensile strength (healthy 63.7 ± 13.4 MPa; diseased 41.7 ± 5.0 MPa) and density (healthy 1.34 ± 0.01 g/cm(3); diseased 1.29 ± 0.00 g/cm(3)). Onchomycosis caused cell-cell separation, without disrupting the nail disulfide bonds or desmosomes. The diseased and healthy nails showed equivalent water uptake profiles, but the rhodamine penetration was 4-fold higher in the diseased nails using a PBS vehicle and 3 -fold higher in an ethanol/PBS vehicle. CONCLUSIONS: Onchomycotic nails presented a thicker but more porous barrier, and its eroded intracellular matrix rendered the tissue more permeable to topically applied chemicals when an aqueous vehicle was used.

Surface structure of Pd(111) with less than half a monolayer of Zn.

We have characterized the structural properties of submonolayer amounts of Zn on Pd(111) using scanning tunneling microscopy (STM) and spot-profile analysis low energy electron diffraction (SPA-LEED). Following room temperature deposition of ≈0.06 monolayers (ML) Zn onto Pd(111), we observe the substitution of Zn for Pd in the surface layer. At ≈0.20 ML of deposited Zn, STM reveals a locally ordered phase with a (2/√3 × 2/√3)R30° unit cell located near Zn substitutions; SPA-LEED patterns reveal the same periodicity. We attribute this phase to the metastable bonding of atoms or clusters predominantly in hollow sites surrounding Zn substitutions in the surface layer. At ≈0.4 ML, STM images reveal local (√3 × âˆš3)R30° and (2 × 1) ordering on surfaces annealed to 350 K. At coverages near 0.5 ML, both STM and SPA-LEED show the onset of the formation of the (2 × 1) ordering associated with the Zn : Pd 1 : 1 alloy phase. At all coverages, the surface is dominated by island growth; the islands' size and density is shown to depend critically on annealing at temperatures as low as 350 K. These results provide insight into the structural features of a Zn/Pd(111) coverage regime that has been much debated in recent years.

Thermal stability of corrugated epitaxial graphene grown on Re(0001).

We report on a novel approach to determine the relationship between the corrugation and the thermal stability of epitaxial graphene grown on a strongly interacting substrate. According to our density functional theory calculations, the C single layer grown on Re(0001) is strongly corrugated, with a buckling of 1.6 Å, yielding a simulated C 1s core level spectrum which is in excellent agreement with the experimental one. We found that corrugation is closely knit with the thermal stability of the C network: C-C bond breaking is favored in the strongly buckled regions of the moiré cell, though it requires the presence of diffusing graphene layer vacancies.

O- and H-induced surface core level shifts on Ru(0001): prevalence of the additivity rule.

In previous work on adsorbate-induced surface core level shifts (SCLSs), the effects caused by O atom adsorption on Rh(111) and Ru(0001) were found to be additive: the measured shifts for first-layer Ru atoms depended linearly on the number of directly coordinated O atoms. Density-functional theory calculations quantitatively reproduced this effect, allowed separation of initial- and final-state contributions, and provided an explanation in terms of a roughly constant charge transfer per O atom. We have now conducted similar measurements and calculations for three well-defined adsorbate and coadsorbate layers containing O and H atoms: (1 × 1)-H, (2 × 2)-(O+H) and (2 × 2)-(O+3H) on Ru(0001). As H is stabilized in fcc sites in the prior two structures and in hcp sites in the latter, this enables us to not only study coverage and coadsorption effects on the adsorbate-induced SCLSs, but also the sensitivity to similar adsorption sites. Remarkably good agreement is obtained between experiment and calculations for the energies and geometries of the layers, as well as for all aspects of the SCLS values. The additivity of the next-neighbor adsorbate-induced SCLSs is found to prevail even for the coadsorbate structures. While this confirms the suggested use of SCLSs as fingerprints of the adsorbate configuration, their sensitivity is further demonstrated by the slightly different shifts unambiguously determined for H adsorption in either fcc or hcp hollow sites.

Renal perivascular adipose tissue: Form and function.

Renal sympathetic activity affects blood pressure in part by increasing renovascular resistance via release of norepinephrine (NE) from sympathetic nerves onto renal arteries. Here we test the idea that adipose tissue adjacent to renal blood vessels, i.e. renal perivascular adipose tissue (RPVAT), contains a pool of NE which can be released to alter renal vascular function. RPVAT was obtained from around the main renal artery/vein of the male Sprague Dawley rats. Thoracic aortic PVAT and mesenteric PVAT also were studied as brown-like and white fat comparators respectively. RPVAT was identified as a mix of white and brown adipocytes, because of expression of both brown-like (e.g. uncoupling protein 1) and white adipogenic genes. All PVATs contained NE (ng/g tissue, RPVAT:524 ±â€¯68, TAPVAT:740 ±â€¯16, MPVAT:96 ±â€¯24). NE was visualized specifically in RPVAT adipocytes by immunohistochemistry. The presence of RPVAT (+RPVAT) did not alter the response of isolated renal arteries to NE compared to responses of arteries without RPVAT (-RPVAT). By contrast, the maximum contraction to the sympathomimetic tyramine was ~2× greater in the renal artery +PVAT versus -PVAT. Tyramine-induced contraction in +RPVAT renal arteries was reduced by the α1-adrenoceptor antagonist prazosin and the NE transporter inhibitor nisoxetine. These results suggest that tyramine caused release of NE from RPVAT. Renal denervation significantly (>50%) reduced NE content of RPVAT but did not modify tyramine-induced contraction of +RPVAT renal arteries. Collectively, these data support the existence of a releasable pool of NE in RPVAT that is independent of renal sympathetic innervation and has the potential to change renal arterial function.

Monitoring super- and subsurface oxygen on Ag(210) by high energy resolution X-ray photoelectron spectroscopy: subsurface diffusion and segregation.

We report on a high energy resolution X-ray photoelectron spectroscopy plus supersonic molecular beam investigation of O/Ag(210). Two components are detected in the O1s spectra upon O2 adsorption, at binding energies EB=527.7 and 529.6 eV. The former peak persists up to 470 K, while the latter one decreases abruptly above 280 K. Comparison with a previous vibrational spectroscopy investigation on the same system (L. Vattuone, et al. Phys. Rev. Lett. 2003, 90, 228302) allows to assign both features to atomic oxygen. The low-energy peak is identified with adatoms, while the other is correlated to O atoms in subsurface sites. A minor contribution at the same binding energy, due to carbonates, is quantified by inspection of the C1s region and shows a different temperature behavior with respect to oxygen. Oxygen segregation into the subsurface region is observed when heating the crystal in the presence of supersurface oxygen.

Theoretical and experimental investigation of optical absorption anisotropy in ß-Ga2O3.

The question of optical bandgap anisotropy in the monoclinic semiconductor ß-Ga2O3 was revisited by combining accurate optical absorption measurements with theoretical analysis, performed using different advanced computation methods. As expected, the bandgap edge of bulk ß-Ga2O3 was found to be a function of light polarization and crystal orientation, with the lowest onset occurring at polarization in the ac crystal plane around 4.5-4.6 eV; polarization along b unambiguously shifts the onset up by 0.2 eV. The theoretical analysis clearly indicates that the shift in the b onset is due to a suppression of the transition matrix elements of the three top valence bands at Γ point.

Carlos Chagas Discoveries as a Drop Back to Scientific Construction of Chronic Chagas Heart Disease.

The scientific construction of chronic Chagas heart disease (CCHD) started in 1910 when Carlos Chagas highlighted the presence of cardiac arrhythmia during physical examination of patients with chronic Chagas disease, and described a case of heart failure associated with myocardial inflammation and nests of parasites at autopsy. He described sudden cardiac death associated with arrhythmias in 1911, and its association with complete AV block detected by Jacquet's polygraph as Chagas reported in 1912. Chagas showed the presence of myocardial fibrosis underlying the clinical picture of CCHD in 1916, he presented a full characterization of the clinical aspects of CCHD in 1922. In 1928, Chagas detected fibrosis of the conductive system, and pointed out the presence of marked cardiomegaly at the chest X-Ray associated with minimal symptomatology. The use of serological reaction to diagnose CCHD was put into clinical practice in 1936, after Chagas' death, which along with the 12-lead ECG, revealed the epidemiological importance of CCHD in 1945. In 1953, the long period between initial infection and appearance of CCHD was established, whereas the annual incidence of CCHD from patients with the indeterminate form of the disease was established in 1956. The use of heart catheterization in 1965, exercise stress testing in 1973, Holter monitoring in 1975, Electrophysiologic testing in 1973, echocardiography in 1975, endomyocardial biopsy in 1981, and Magnetic Resonance Imaging in 1995, added to the fundamental clinical aspects of CCHD as described by Carlos Chagas.

Interplay between electronic and structural properties in the Pb/Ag(1 0 0) interface.

We report an investigation of the structural and electronic properties of a Pb monolayer (ML) grown on Ag(1 0 0), by combining x-ray photoelectron diffraction (XPD) and angle resolved photoelectron spectroscopy (ARPES). The Pb atoms are found to arrange in a pseudo-hexagonal adlayer commensurate to the underlying square Ag substrate, resulting in a coincidence cell with c([Formula: see text]) periodicity. The electronic structure of the Pb ML in proximity of the Fermi level consists in three p-derived bands, which show different degrees of hybridization with the substrate for their different orbital characters. In particular, we report that the p xy states disperse without forming energy gap, in contrast to previous ARPES studies of the Pb ML on different metallic substrates. We attribute the absence of energy gap to the commensurability between substrate and adlayer, resulting in a higher two-dimensionality of the Pb ML.

Peripheral neuropathy in multiple system atrophy with autonomic failure.

Two patients with multiple system atrophy, autonomic failure, and peripheral neuropathy are reported. EMG conduction study in both muscle and sural nerve histology in one patient documented the involvement of the neuromuscular system. Morphologic study of the biopsied nerve showed marked reduction of large myelinated fibers, whereas the unmyelinated axons were totally spared. The latter finding provides evidence that the syspathetic nervous system contributes few, if any, axons to the total population of unmyelinated fibers in the human sural nerve. Peripheral nerve damage may be common in the Shy-Drager syndrome.

Prostacyclin-lipoprotein interactions. Studies on human platelet aggregation and adenylate cyclase.

The in vitro effects of different lipoprotein fractions (VLDL, LDL and HDL) on human washed platelet aggregation, induced by collagen and thrombin, were evaluated in the presence and absence of PGI2. Although VLDL and LDL increased the platelet aggregation while HDL showed an opposite effect, none of the tested lipoprotein fractions affected the potency of PGI2 as inhibitor of platelet aggregation (IC50). In addition, studies were performed to evaluate the effects of lipoproteins on adenylate cyclase activity in human platelet membranes. The three lipoprotein classes inhibited both basal and PGI2-stimulated adenylate cyclase without affecting the EC50 for PGI2. This inhibitory activity was not specifically elicited by any protein or lipid since neither bovine serum albumin nor a lipid emulsion (Intralipid) displayed any inhibition. The effect on adenylate cyclase elicited by VLDL, LDL and HDL does not seem to be correlated with the activity on platelet aggregation. It is concluded that mediators other than cAMP might be involved in the control of platelet function by lipoproteins.

Chemical shift resolved photoionization cross sections of amorphous carbon nitride

The various components in the N 1s photoemission spectra of amorphous carbon nitride are identified by measuring their photon energy dependence and comparing the experimental results with ab initio multiple scattering calculations. The intensity modulations with photon energy are due to the extended x-ray absorption fine structure effects.

Constructive feedforward ART clustering networks. I.

Part I of this paper proposes a definition of the adaptive resonance theory (ART) class of constructive unsupervised on-line learning clustering networks. Class ART generalizes several well-known clustering models, e.g., ART 1, improved ART 1, adaptive Hamming net (AHN), and Fuzzy ART, which are optimized in terms of memory storage and/or computation time. Next, the symmetric Fuzzy ART (S-Fuzzy ART) network is presented as a possible improvement over Fuzzy ART. As a generalization of S-Fuzzy ART, the simplified adaptive resonance theory (SART) group of ART algorithms is defined. Gaussian ART (GART), which is found in the literature, is presented as one more instance of class SART. In Part II of this work, a novel SART network, called fully self-organizing SART (FOSART), is proposed and compared with Fuzzy ART, S-Fuzzy ART, GART and other well-known clustering algorithms. Results of our comparison may easily extend to the ARTMAP supervised learning framework.

Constructive feedforward ART clustering networks. II.

For pt.I see ibid., p.645-61 (2002). Part I of this paper defines the class of constructive unsupervised on-line learning simplified adaptive resonance theory (SART) clustering networks. Proposed instances of class SART are the symmetric fuzzy ART (S-Fuzzy ART) and the Gaussian ART (GART) network. In Part II of our work, a third network belonging to class SART, termed fully self-organizing SART (FOSART), is presented and discussed. FOSART is a constructive, soft-to-hard competitive, topology-preserving, minimum-distance-to-means clustering algorithm capable of: 1) generating processing units and lateral connections on an example-driven basis and 2) removing processing units and lateral connections on a minibatch basis. FOSART is compared with Fuzzy ART, S-Fuzzy ART, GART and other well-known clustering techniques (e.g., neural gas and self-organizing map) in several unsupervised learning tasks, such as vector quantization, perceptual grouping and 3-D surface reconstruction. These experiments prove that when compared with other unsupervised learning networks, FOSART provides an interesting balance between easy user interaction, performance accuracy, efficiency, robustness, and flexibility.

Model transitions in descending FLVQ.

Fuzzy learning vector quantization (FLVQ), also known as the fuzzy Kohonen clustering network, was developed to improve performance and usability of on-line hard-competitive Kohnen's vector quantization and soft-competitive self organizing map (SOM) algorithms. The FLVQ effectiveness seems to depend on the range of change of the weighting exponent m(t). In the first part of this work, extreme m(t) values (1 and 1, respectively) are employed to investigate FLVQ asymptotic behaviors. This analysis shows that when m(t) tends to either one of its extremes, FLVQ is affected by trivial vector quantization, which causes centroids collapse in the grand mean of the input data set. No analytical criterion has been found to improve the heuristic choice of the range of m(t) change. In the second part of this paper, two FLVQ and SOM classification experiments of remote sensed data are presented. In these experiments the two nets are connected in cascade to a supervised second stage, based on the delta rule. Experimental results confirm that FLVQ performance can be greatly affected by the user's definition of the range of change of the weighting exponent. Moreover, FLVQ shows instability when its traditional termination criterion is applied. Empirical recommendations are proposed for the enhancement of FLVQ robustness. Both the analytical and the experimental data reported seem to indicate that the choice of the range of m(t) change is still open to discussion and that alternative clustering neural-network approaches should be developed to pursue during training: 1) monotone reduction of the neurons' learning rate and 2) monotone reduction of the overlap among neuron receptive fields.

[IgD myeloma. Presentation of a case and review of the literature]. / IgD mieloma. Presentazione di un caso e revisione della letteratura.

A case of IgD myeloma that began with high paraproteinaemia, BJ proteinuria of type and 40% marrow plasmacellular infiltration is reported. These onset data suggested a large tumoral mass and hence a poor prognosis. On the other hand, after subjecting the patient to 4 polychemotherapy cycles (alkeran and prednisone) CM disappeared from serum and urine and bone lesion progression stopped. It is also stressed that this from presents clinical (frequent extra-osseous growth, presence of amyloidosis), laboratory (severe anaemia, renal insufficiency, BJ proteinuria) and particular prognostic features.

[Transcutaneous renal needle-biopsy guided with ultrasonics]. / Agobiopsia renale transcutanea "mirata" con ultrasuoni.

Authors performed percutaneous renal biopsy guided by ultrasounds in 10 patients in whom urography was dangerous or did not provided good renal images. The advantages of this method are in the directional and dimensional accuracy of ultrasound scanning, so that the exact topography of the kidney can be established. The use of ultrasonically guided renal biopsy is mainly recommended in iodine medium idiosyncrasy, in myelomas and renal failure. This method can be preferred in order to establish the exact topography of kidney, in acute anuric renal failure, in chronic failure (when high doses of iodate contrast are needed), and in the presence of cyst.

A survey of fuzzy clustering algorithms for pattern recognition. I.

Clustering algorithms aim at modeling fuzzy (i.e., ambiguous) unlabeled patterns efficiently. Our goal is to propose a theoretical framework where the expressive power of clustering systems can be compared on the basis of a meaningful set of common functional features. Part I of this paper reviews the following issues related to clustering approaches found in the literature: relative (probabilistic) and absolute (possibilistic) fuzzy membership functions and their relationships to the Bayes rule, batch and on-line learning, prototype editing schemes, growing and pruning networks, modular network architectures, topologically perfect mapping, ecological nets and neuro-fuzziness. From this discussion an equivalence between the concepts of fuzzy clustering and soft competitive learning in clustering algorithms is proposed as a unifying framework in the comparison of clustering systems. Moreover, a set of functional attributes is selected for use as dictionary entries in the comparison of clustering algorithms, which is the subject of part II of this paper.