Characterization of bacterial diversity associated with microbial mats, gypsum evaporites and carbonate microbialites in thalassic wetlands: Tebenquiche and La Brava, Salar de Atacama, Chile.

In this paper, we report the presence of sedimentary microbial ecosystems in wetlands of the Salar de Atacama. These laminated systems, which bind, trap and precipitate mineral include: microbial mats at Laguna Tebenquiche and Laguna La Brava, gypsum domes at Tebenquiche and carbonate microbialites at La Brava. Microbial diversity and key biogeochemical characteristics of both lakes (La Brava and Tebenquiche) and their various microbial ecosystems (non-lithifying mats, flat and domal microbialites) were determined. The composition and abundance of minerals ranged from trapped and bound halite in organic-rich non-lithifying mats to aragonite-dominated lithified flat microbialites and gypsum in lithified domal structures. Pyrosequencing of the V4 region of the 16s rDNA gene showed that Proteobacteria comprised a major phylum in all of the microbial ecosystems studied, with a marked lower abundance in the non-lithifying mats. A higher proportion of Bacteroidetes was present in Tebenquiche sediments compared to La Brava samples. The concentration of pigments, particularly that of Chlorophyll a, was higher in the Tebenquiche than in La Brava. Pigments typically associated with anoxygenic phototrophic bacteria were present in lower amounts. Organic-rich, non-lithifying microbial mats frequently formed snake-like, bulbous structures due to gas accumulation underneath the mat. We hypothesize that the lithified microbialites might have developed from these snake-like microbial mats following mineral precipitation in the surface layer, producing domes with endoevaporitic communities in Tebenquiche and carbonate platforms in La Brava. Whereas the potential role of microbes in carbonate platforms is well established, the contribution of endoevaporitic microbes to formation of gypsum domes needs further investigation.

American College of Radiology Appropriateness Criteria: Advancing Evidence-Based Imaging Practice.

ACR Appropriateness Criteria (ACR AC) are evidence-based guidelines to assist referring physicians, other providers, and patients in making the most appropriate imaging or treatment decision for a specific clinical condition. The ACR AC are created by expert panels consisting of multidisciplinary physicians, using principles outlined by the Agency for Healthcare Research and Quality as designed by the Institute of Medicine. The ACR AC are qualified appropriate use criteria as designated under the Protecting Access to Medicare Act legislation of 2014. The ACR AC development process includes topic selection, literature search, evidence table development, appropriateness (risk-benefit) assessment, patient and public input, document publication and ACR AC content dissemination through clinical decision support mechanisms, and periodic review. These criteria benchmark the selection of the most appropriate imaging or treatments, as well as educating radiology, nuclear medicine, and other clinical discipline trainees.

Carboxylic acid-doped SBA-15 silica as a host for metallo-supramolecular coordination polymers.

The adsorption of a metallo-supramolecular coordination polymer (Fe-MEPE) in the cylindrical pores of SBA-15 silica with pure and carboxylic acid (CA) carrying pore walls has been studied. Fe-MEPE is an intrinsically stiff polycation formed by complexation of Fe(II)-acetate with an uncharged ditopic bis-terpyridine ligand. The adsorption affinity and kinetics of the Fe-MEPE chains is strongly enhanced when the pore walls are doped with CA, and when the pH of the aqueous medium or temperature is increased. The initial fast uptake is connected with a decrease of pH of the aqueous solution, indicating an ion-exchange mechanism. It is followed by a slower (presumably diffusion-controlled) further uptake. The maximum adsorbed amount of Fe-MEPE in the CA-doped material corresponds to a monolayer of Fe-MEPE chains disposed side-by-side along the pore walls. The stoichiometry of Fe-MEPE in the pores (determined by XPS) was found to be independent of the loading and similar to that of the starting material. The mean chain length of Fe-MEPE before and after embedding in the CA-doped matrix was studied by solid-state 15N NMR using partially 15N-labeled Fe-MEPE. It is shown that the average chain length of Fe-MEPE is reduced when the complex is incorporated in the pores.

Structure and temperature behavior of metallo-supramolecular assemblies.

A detailed structural analysis of a Langmuir-Blodgett (LB) multilayer composed of a polyelectrolyte-amphiphile complex (PAC) is presented. The PAC is self-assembled from metal ions, ditopic bis-terpyridines, and amphiphiles. The vertical structure of the LB multilayer is investigated by X-ray reflectometry. The multilayer has a periodicity of 57 A, which corresponds to an architecture of flat lying metallo-supramolecular coordination polyelectrolyte (MEPE) rods and upright-standing amphiphiles (dihexadecyl phosphate, DHP). In-plane diffraction reveals hexagonal packing of the DHP molecules. Using extended X-ray absorption fine structure (EXAFS) experiments, we prove that the central metal ion is coordinated to the terpyridine moieties in a pseudo-octahedral coordination environment. The Fe-N bond distances are 1.82 and 2.0 A, respectively. Temperature resolved measurements indicate a reversible phase transition in a temperature range up to 55 degrees C. EXAFS measurements indicate a lengthening of the average Fe-N bond distance from 1.91 to 1.95 A. The widening of the coordination cage upon heating is expected to lower the ligand field stabilization, thus giving rise to spin transitions in these composite materials.

Prevalence of undiagnosed eye disease in high-risk diabetic individuals.

A total of 533 diabetic individuals using the Marshall, Minn, medical care system were identified as potential subjects for a study of unrecognized eye disease. Of these, 172 (32%) stated they had never had an ophthalmologic eye examination and subsequently were defined as being at high risk for unrecognized diabetic eye disease. Ophthalmic examination was performed on 145 (84%) of these high-risk individuals and revealed that 61% had clinical characteristics consistent with diabetic retinopathy, glaucoma, cataract, or other eye abnormalities. Twenty-five (17%) of these subjects presented with eye disease that required immediate treatment, referral, or accelerated follow-up. Of those indicating they had an ophthalmologist, approximately 35% reported a time since last visit of 2 years or greater. These findings indicate a high prevalence of ocular morbidity among diabetic individuals who are not under routine ophthalmic surveillance and suggest that improvements in patient and professional compliance with recommended guidelines for eye care are warranted.

Hippocampal neuron and synaptophysin-positive bouton number in aging C57BL/6 mice.

A loss of hippocampal neurons and synapses had been considered a hallmark of normal aging and, furthermore, to be a substrate of age-related learning and memory deficits. Recent stereological studies in humans have shown that only a relatively minor neuron loss occurs with aging and that this loss is restricted to specific brain regions, including hippocampal subregions. Here, we investigate these age-related changes in C57BL/6J mice, one of the most commonly used laboratory mouse strains. Twenty-five mice (groups at 2, 14, and 28-31 months of age) were assessed for Morris water-maze performance, and modern stereological techniques were used to estimate total neuron and synaptophysin-positive bouton number in hippocampal subregions at the light microscopic level. Results revealed that performance in the water maze was largely maintained with aging. No age-related decline was observed in number of dentate gyrus granule cells or CA1 pyramidal cells. In addition, no age-related change in number of synaptophysin-positive boutons was observed in the molecular layer of the dentate gyrus or CA1 region of hippocampus. We observed a significant correlation between dentate gyrus synaptophysin-positive bouton number and water-maze performance. These results demonstrate that C57BL/6J mice do not exhibit major age-related deficits in spatial learning or hippocampal structure, providing a baseline for further study of mouse brain aging.

Complement activation and neutropenia occurring during cardiopulmonary bypass.

Complement activation and pulmonary leukostasis with neutropenia occur in hemodialysis and filtration leukapheresis, with attendant pulmonary dysfunction. Wondering whether similar phenomena might attend cardiopulmonary bypass (CPB), we studied 34 patients undergoing coronary artery bypass operations. As in the other extracorporeal circulation systems, neutropenia (mean 44.7% +/- 4.3% SEM of prebypass PMN count) occurred during the first half hour of bypass and then a rebound neutrophilia followed. CH50 and C3H50 fell 22% to 25% (p for CH50 less than 0.01) during bypass, but C3 conversion and C5a were not demonstrable in patient plasmas. Nonetheless, polymorphonuclear neutrophils (PMNs) harvested late in bypass showed low adherence to nylon and selective chemotactic and aggregative insensitivity to C5a--functional aberrations which are seen after exposure to activated complement. Furthermore, smaller infusions of activated complement into animals produced neutropenia than were required to achieve a detectable [C5a] in the plasma. We conclude that neutropenia during CPB probably results from complement activation below the threshold of detection; complement-stimulated PMNs deserve study as possible mediators of tissue injury occurring during CPB.

Treatment of anoestrous mares with a synthetic progestagen, allyloestrenol.

Anoestrous mares were treated with prostaglandin (n = 43) and those that did not respond to prostaglandin (n = 29) with a synthetic progestagen, allyloestrenol, at a dose of 0.05 mg/kg body mass for 12 days. After the cessation of the long-term per os gestagen blockade the animals were checked for heat and, if a preovulatory follicle could be palpated, 2000 IU hCG was administered to induce ovulation. In some animals the plasma 17 beta-oestradiol (E2) and progesterone (P4) levels were also followed up throughout the gestagen treatment and for 10-14 days thereafter. As the favourable oestrus rate (86.2%) and pregnancy rate (65.5%) indicate, the 12-day allyloestrenol treatment seems to be a reliable tool for induction of cycling in mares anoestrous early in the season. These results, supported by the E2 and P4 profiles, suggest that an important reason for anoestrus in mares is the absence of a functional corpus luteum that can be substituted for by exogenous gestagen administration. The timing of ovulation, however, should still be improved.

A route to hierarchical materials based on complexes of metallosupramolecular polyelectrolytes and amphiphiles.

Anisotropic thin film materials of metallosupramolecular polyelectrolyte-amphiphile complexes (denoted PACs) with structures at several length scales were fabricated through a multistep self-assembly process. Metal ion-mediated self-assembly of the ditopic ligand 1,4-bis(2,2':6',2"-terpyridine-4'-yl)benzene and electrostatic binding with the amphiphile dihexadecyl phosphate result in a PAC with tailored surface chemical properties, including solubility and surface activity. The PAC forms a stable monolayer at the air-water interface that is readily transferred and oriented on solid supports with the Langmuir-Blodgett technique. The presented strategy unifies colloid and metallosupramolecular chemistry and opens a versatile route to hierarchical materials with tailored structures and functions.

Functional consequence of mutating conserved residues of the yeast farnesyl-protein transferase beta-subunit Ram1(Dpr1).

Ras proteins, fungal mating pheromones, and other proteins terminating in the sequence CaaX (where C is Cys, a is any aliphatic amino acid, and X is the C-terminal residue) are posttranslationally prenylated. Farnesyl-protein transferase (FPTase) transfers the farnesyl moiety of farnesyl pyrophosphate (FPP) to the thiol of the CaaX box cysteine in a reaction that requires Zn2+ and Mg2+. We have created mutations in conserved amino acids of the yeast Ram1 protein to identify residues important for Zn2+-dependent FPTase activity. Wild-type and mutant Ram1 proteins were expressed as operon fusions in bacteria, and FPTase activity was measured. Mutations in conserved residues Glu256, His258, Asp307, Cys309, Asp360, and His363 reduce FPTase activity. Asp307, Cys309, and His363 correspond to the residues that have been shown to coordinate Zn2+ in mammalian FPTase. The H258N mutant enzyme exhibited an increased sensitivity to the Zn2+ chelator 1,10-phenanthroline, required higher concentrations of Zn2+ to restore activity to the apoenzyme, and had a 10-fold reduction in catalytic efficiency. The decreases in FPTase activity observed do not appear to be caused by major structural perturbations because the mutants were stably expressed and retained the ability to interact with Ram2p during purification. The FPTase activity of the mutants measured in vitro correlated well with their ability to complement the mating and growth defects of a ram1Delta strain in vivo.

Structural analysis of a metallosupramolecular polyelectrolyte-amphiphile complex at the air/water interface.

A detailed analysis of a metallosupramolecular coordination polyelectrolyte-amphiphile complex (PAC) at the air/water interface is presented based on Langmuir isotherm measurements, Brewster angle microscopy as well as X-ray reflectance and diffraction measurements. The PAC is prepared in solution by metal-ion coordination of Fe(OAc)2 and 1,4-bis(2,2':6',2"-terpyridin-4'-yl)benzene followed by self-assembly with dihexadecyl phosphate (DHP). The spreading of the PAC at the air/water interface results in a Langmuir film with a stratified architecture, such that DHP forms a monolayer on the water surface, while the metallosupramolecular coordination polyelectrolyte (MEPE) is immersed in the aqueous subphase. Electrostatic interactions of MEPE and DHP force the alkyl chains into an upright, hexagonal lattice even at low surface pressures. This work illustrates how supramolecular, colloidal, and surface chemistry can be combined to create complex architectures with tailored characteristics that may not be accessible through self-organization in the liquid phase.

[Multiparity in Nicaragua]. / Multiparität in Nicaragua.

The relation between birthweight and parity of the mother was examined in Nicaraguan patients from the capital Managua. 7431 births were taken into consideration from 1989-1991. 564 (= 7.6%) of these newborns were born to mothers with more than 5 deliveries. A positive correlation between the increasing number of the parity and the birthweight can be demonstrated in our patients until parity 10, however there are decreases in the birthweight of female newborns between parity 3 to 4 and 5 to 6 and in males between parity 6 to 7 and parity 8 to 9. The average age of a Nicaraguan primipara is 20.7 years and increases by 1.9-2.4 years until parity 5. From parity 6 to parity 15 it increases only by 0.7-1.2 years.

Controlling wettability by light: illuminating the molecular mechanism.

The functionalisation of a surface with an organic monolayer containing photoactive moieties such as the azobenzene chromophore opens an elegant route for controlling its wettability by light. In this paper we investigate the microscopic origin of the macroscopic change in wettability upon photo-induced cis-trans isomerization of a copolymeric diphenyl-diazene Langmuir-Blodgett monolayer. Polarised UV-Vis and FTIR spectroscopy have been used to monitor the orientational order of various functional groups, Atomic Force Microscopy and Imaging Ellipsometry is employed for the quantification of the surface roughness and morphology, contact angle and surface potential measurements are carried out for a characterisation of the polar ordering. The data analysis is further supported by semi-empirical and ab-initio calculations of the molecular dipole moments and the normal IR-modes of the fluorinated chromophore. The combination of all these techniques provides a detailed molecular picture. The data suggest that changes in the projection of the dipole moment onto the surface normal caused by isomerization of the azobenzene are responsible for the observed changes in the surface energy. This knowledge allowed us to predict guidelines for the synthesis of molecules in order to maximize the wetting contrast upon photo-irradiation.

Full length cDNA of rat RT1.DMa and RT1.DMb and expression of RT1.DM genes in dendritic and Langerhans cells.

MHC encoded DM heterodimers and classical MHC class II complexes meet in an endosomal/lysosomal compartment where DM heterodimers support peptide loading of MHC class II. Studies on peptide loading of rat class II and on peptide persistence in cells of the dendritic lineage prompted us to establish full length cDNA clones coding for the subunits alpha and beta of rat DM molecules as well as a mAb directed against the luminal moiety of the beta subunit. Here we describe the establishment of the first full length cDNA clones of rat RT1.DMa and RT1.DMb. The mode of expression of RT1.DM at the transcript level in bone marrow culture-derived dendritic cells, in Langerhans cells and in a number of additional accessory cells is reported. The beta protein was identified in detergent lysates of RT1.DM expressing cells by Western blot analysis using a newly established monoclonal antibody directed against the luminal part of RT1.DMbeta.

Temperature- and time-resolved X-ray scattering at thin organic films.

Multilayers of an Fe(II)-polyelectrolyte-amphiphile complex (Fe-PAC) were investigated simultaneously by energy-dispersive X-ray reflectivity and in-plane diffraction at the bending-magnet beamline at BESSY II. By recording spectra between room temperature and about 348 K with a time resolution of about 60 s, two phase transitions were identified and the respective activation energies were determined. Owing to a fixed geometrical set-up, an energy-dispersive experiment is suitable for measuring X-ray reflectivity and in-plane X-ray diffraction of thin organic films simultaneously. Installed at a bending magnet at BESSY II and using an energy range of 4 < E < 25 keV, both reflectivity and diffraction spectra can be collected within about 60 s. The performance is demonstrated by temperature- and time-resolved measurements of the phase transition behaviour of multilayers of an Fe-PAC deposited on a silicon support by means of the Langmuir-Blodgett (LB) technique. By measuring the X-ray reflectivity while increasing the temperature, it is shown that the original LB phase is not stable and transforms irreversibly into a liquid-crystalline (LC)-like phase at about 318 K. At the same temperature the in-plane diffraction signal vanishes reversibly, reflecting rotational disorder of the hexagonal arrangement of amphiphilic chains. Its activation energy is determined to be about 1.3 eV. At about 338 K a second irreversible phase transition occurs to another LC phase with smaller vertical layer spacing. This transition is reversible between 329 K and 338 K.

Surfactant-encapsulated clusters (SECs): (DODA)20(NH4)[H3Mo57V6(NO)6O183(H2O)18], a case study.

We present a comprehensive study of the partially reduced polyoxomolybdate [H3-Mo57V6(NO)6O183(H2O)18]21-encapsulated in a shell of dimethyldioctadecylammonium (DODA) surfacmolecules. Treatment of an aqueous solution of (NH4)21[H3Mo57V6-(NO)6O183(H2O)18] . 65H2O (1a) with a trichloromethane solution of the surfactant leads to instant transfer of the encapsulated complex anion into the organic phase. Results from vibrational spectroscopy. analytical ultracentrifugation, small-angle X-ray scattering, transmission electron microscopy, elemental analysis, and Langmuir compression isotherms are consistent with a single polyoxometalate core encapsulated within a shell of 20 DODA molecules. The molar mass of the supramolecular assembly is 20249 gmol(-1) and the diameter is 3.5 nm. A material with the empirical formula (DODA)20(NH4)[H3-Mo57V6NO)6O183(H2O)18] (2) was isolated as a dark violet solid, which readily dissolves in organic solvents. Slow evaporation of solutions of 2 on solid substrates forces the hydrophobic particles to aggregate into a cubic lattice. Annealing these so-formed films at elevated temperature causes de-wetting with terrace formation similar to liquid crystals and block copolymers. Compound 2 forms a stable Langmuir monolayer at the air-water interface; Langmuir-Blodgett multilayers are readily prepared by repeated transfer of monolayers on solid substrates. The films were characterized by optical ellipsometry, Brewster angle microscopy, transmission electron microscopy, and X-ray reflectance.

Patient adherence to guidelines for diabetes eye care: results from the diabetic eye disease follow-up study.

Early detection and treatment of diabetic eye disease can prevent blindness, yet many persons with diabetes lack regular eye care. This study followed 569 people with diabetes participating in blindness prevention programs during 1985 through 1987; it was found that 35% of subjects received dilated eye examinations before entering the programs, in comparison with 60% afterward. About 85% of participants referred for proliferative retinopathy treatment began such treatment, and, of these, 85% completed treatment. A lack of knowledge about the disease and limited finances were primary reasons for nonadherence. To improve the effectiveness of prevention programs, eye care providers and program staff must strive to eliminate these educational and financial barriers.