Leaf surface wax is a source of plant methane formation under UV radiation and in the presence of oxygen.

The terrestrial vegetation is a source of UV radiation-induced aerobic methane (CH4 ) release to the atmosphere. Hitherto pectin, a plant structural component, has been considered as the most likely precursor for this CH4 release. However, most of the leaf pectin is situated below the surface wax layer, and UV transmittance of the cuticle differs among plant species. In some species, the cuticle effectively absorbs and/or reflects UV radiation. Thus, pectin may not necessarily contribute substantially to the UV radiation-induced CH4 emission measured at surface level in all species. Here, we investigated the potential of the leaf surface wax itself as a source of UV radiation-induced leaf aerobic CH4 formation. Isolated leaf surface wax emitted CH4 at substantial rates in response to UV radiation. This discovery has implications for how the phenomenon should be scaled to global levels. In relation to this, we demonstrated that the UV radiation-induced CH4 emission is independent of leaf area index above unity. Further, we observed that the presence of O2 in the atmosphere was necessary for achieving the highest rates of CH4 emission. Methane formation from leaf surface wax is supposedly a two-step process initiated by a photolytic rearrangement reaction of the major component followed by an α-cleavage of the generated ketone.

Metabolic outcomes of matched patient populations initiating exenatide BID vs. insulin glargine in an ambulatory care setting.

AIM: This observational study evaluated the clinical effectiveness of exenatide BID (exenatide) vs. insulin glargine (glargine) in patients with type 2 diabetes mellitus in ambulatory clinical practice. METHODS: Retrospective analyses were conducted using an electronic medical record (EMR) database among adult patients with type 2 diabetes mellitus initiating exenatide or glargine between 1 November 2006 and 30 April 2009. The cohorts were propensity-score matched to control baseline demographics, clinical measures, health status and medication use. The changes from baseline to a 12-month follow-up period for A1C (primary outcome), weight, body mass index (BMI), blood pressure and lipid levels were compared between the matched cohorts using paired tests. RESULTS: Propensity-score matching between the exenatide (n = 4494) and glargine (n = 5424) cohorts led to 2683 matched pairs with comparable characteristics, including age, gender and baseline clinical values. The exenatide cohort achieved a greater mean reduction in A1C (-0.6% vs. -0.4%, p < 0.01), weight (-2.6 kg vs. -0.2 kg, p < 0.01), BMI (-0.8 kg/m(2) vs. -0.04 kg/m(2) , p < 0.01) and systolic blood pressure (SBP) (-1.8 mmHg vs. -0.1 mmHg, p < 0.01) in the follow-up period. The changes in diastolic blood pressure and lipid levels were not significantly different between cohorts. CONCLUSIONS: Compared to glargine, exenatide-treated patients experienced significant reductions in A1C, weight, BMI and SBP. Acknowledging the limitations of observational research, exenatide showed greater clinical effectiveness than glargine from a large EMR database in the ambulatory care setting.

Patient perspectives on once-weekly medications for diabetes.

AIM: to examine patient beliefs, preferences and concerns regarding a once-weekly (QW) glucose-lowering medication option. METHODS: a total of 1516 adults with type 2 diabetes drawn from a national Chronic Illness Panel completed an anonymous online survey that assessed perceived attributes of QW therapy, willingness to take an injectable QW medication and patient characteristics that might influence their willingness, such as current perceived glycaemic control and diabetes quality of life (DQOL). RESULTS: positive attitudes regarding QW medication were common, with current injection users significantly more likely than non-injection users to view beneficial aspects: greater convenience, better medication adherence, improved quality of life (QOL) and a less overwhelming sense of treatment (in all cases, p < 0.001). In all, 46.8% reported that they would likely take an injectable QW medication if recommended by their physician, with current injection users more than twice as likely as non-injection users (73.1 vs. 31.5%; p < 0.001). Greater willingness to take QW medications was associated with poorer DQOL [injection users only; odds ratio (OR) = 1.37, p < 0.01] and poorer perceived glycaemic control (non-injection users only; OR = 1.24, p < 0.05). Concerns arose about consistency of dosage over time, potential forgetfulness and cost. CONCLUSIONS: QW glucose-lowering medications are viewed positively by patients with type 2 diabetes, especially if they are current injection users or are dissatisfied with their current treatments or outcomes. Greater convenience, better medication adherence and improved QOL are commonly endorsed attributes. Clinicians may need to review both the positive attributes of QW medications as well as common patient concerns, when considering this option.

Effects of temperature, ultraviolet radiation and pectin methyl esterase on aerobic methane release from plant material.

This study examines the effects of different irradiance types on aerobic methane (CH(4)) efflux rates from terrestrial plant material. Furthermore, the role of the enzyme pectin methyl esterase (PME) on CH(4) efflux potential was also examined. Different types of plant tissue and purified pectin were incubated in glass vials with different combinations of irradiation and/or temperature. Purified dry pectin was incubated in solution, and with or without PME. Before and after incubation, the concentration of CH(4) was measured with a gas chromatograph. Rates of CH(4) emission were found to depend exponentially on temperature and linearly on UV-B irradiance. UV-B had a greater stimulating effect than UV-A, while visible light had no effect on emission rates. PME was found to substantially reduce the potential for aerobic CH(4) emissions upon demethylation of pectin.

The apparent temperature response of leaf respiration depends on the timescale of measurements: a study of two cold climate species.

Productivity and climate models often use a constant Q10 for plant respiration, assuming tight control of respiration by temperature. We studied the temperature response of leaf respiration of two cold climate species (the Australian tree Eucalyptus pauciflora and the subantarctic megaherb Pringlea antiscorbutica, both measured in a field setting) on a short timescale (minutes) during different times within a diel course, and on a longer timescale, using diel variations in ambient temperature. There were great variations in Q10 depending on measuring day, measuring time and measuring method. When Q10 was calculated from short-term (15 min) manipulations of leaf temperature, the resulting values were usually markedly smaller than when Q10 was calculated from measurements at ambient leaf temperatures spread over a day. While for E. pauciflora, Q10 estimates decreased with rising temperature (corroborating the concept of a temperature-dependent Q10), the opposite was the case for P. antiscorbutica. Clearly, factors other than temperature co-regulate both leaf respiration rates and temperature sensitivity and contribute to diel and seasonal variation of respiration.

Attached and unattached bacterial communities in a 120-meter corehole in an acidic, crystalline rock aquifer.

The bacteria colonizing geologic core sections (attached) were contrasted with those found suspended in the groundwater (unattached) by examining the microbiology of 16 depth-paired core and groundwater samples using a suite of culture-independent and culture-dependent analyses. One hundred twenty-two meters was continuously cored from a buried chalcopyrite ore hosted in a biotite-quartz-monzonite porphyry at the Mineral Park Mine near Kingman, Ariz. Every fourth 1.5-m core was acquired using microbiologically defensible methods, and these core sections were aseptically processed for characterization of the attached bacteria. Groundwater samples containing unattached bacteria were collected from the uncased corehole at depth intervals corresponding to the individual cores using an inflatable straddle packer sampler. The groundwater was acidic (pH 2.8 to 5.0), with low levels of dissolved oxygen and high concentrations of sulfate and metals, including ferrous iron. Total numbers of attached cells were less than 10(5) cells g of core material(-1) while unattached cells numbered about 10(5) cells ml of groundwater(-1). Attached and unattached acidophilic heterotrophs were observed throughout the depth profile. In contrast, acidophilic chemolithotrophs were not found attached to the rock but were commonly observed in the groundwater. Attached communities were composed of low numbers (<40 CFU g(-1)) of neutrophilic heterotrophs that exhibited a high degree of morphologic diversity, while unattached communities contained higher numbers (ca. 10(3) CFU ml(-1)) of neutrophilic heterotrophs of limited diversity. Sulfate-reducing bacteria were restricted to the deepest samples of both core and groundwater. 16S ribosomal DNA sequence analysis of attached, acidophilic isolates indicated that organisms closely related to heterotrophic, acidophilic mesophiles such as Acidiphilium organovorum and, surprisingly, to the moderately thermophilic Alicyclobacillus acidocaldarius were present. The results indicate that viable (but possibly inactive) microorganisms were present in the buried ore and that there was substantial distinction in biomass and physiological capabilities between attached and unattached populations.

Evaluation of a fluorescent lectin-based staining technique for some acidophilic mining bacteria.

A fluorescence-labeled wheat germ agglutinin staining technique (R. K. Sizemore et al., Appl. Environ. Microbiol. 56:2245-2247, 1990) was modified and found to be effective for staining gram-positive, acidophilic mining bacteria. Bacteria identified by others as being gram positive through 16S rRNA sequence analyses, yet clustering near the divergence of that group, stained weakly. Gram-negative bacteria did not stain. Background staining of environmental samples was negligible, and pyrite and soil particles in the samples did not interfere with the staining procedure.

An interconnected network of core-forming melts produced by shear deformation

The formation mechanism of terrestrial planetary cores is still poorly understood, and has been the subject of numerous experimental studies. Several mechanisms have been proposed by which metal--mainly iron with some nickel--could have been extracted from a silicate mantle to form the core. Most recent models involve gravitational sinking of molten metal or metal sulphide through a partially or fully molten mantle that is often referred to as a 'magma ocean'. Alternative models invoke percolation of molten metal along an interconnected network (that is, porous flow) through a solid silicate matrix. But experimental studies performed at high pressures have shown that, under hydrostatic conditions, these melts do not form an interconnected network, leading to the widespread assumption that formation of metallic cores requires a magma ocean. In contrast, here we present experiments which demonstrate that shear deformation to large strains can interconnect a significant fraction of initially isolated pockets of metal and metal sulphide melts in a solid matrix of polycrystalline olivine. Therefore, in a dynamic (non-hydrostatic) environment, percolation remains a viable mechanism for the segregation and migration of core-forming melts in a solid silicate mantle.

Responses of two provenances of Fagus sylvatica seedlings to a combination of four temperature and two CO2 treatments during their first growing season: gas exchange of leaves and roots.

Physiological responses of two provenances of European beech (Fagus sylvatica) were studied in seedlings grown at two [CO2 ] in combination with four temperature treatments. For the local Danish provenance, the average effect of elevated [CO2 ] during growth was to increase light-saturated net photosynthesis (An ) and instantaneous water-use efficiency or transpiration efficiency (ITE). These increases were strongly related to the temperature treatment. Stomatal conductance (gs ) was reduced in seedlings in high [CO2 ], but there was no statistically significant effect of temperature treatment. Stomatal conductance was 13-26% lower at elevated [CO2 ] and ITE was 89-156% higher, depending on growth temperature. The effects of [CO2 ] on An were considerably larger than those shown for many other woody species, but similar to those in other studies on European beech. The absolute value of An for a Romanian provenance of beech was 5-18% lower than in the Danish provenance at low [CO2 ] and 14-26% lower at high [CO2 ]. There was no statistically significant interaction between the provenances and [CO2 ], or between provenance and temperature. A model of the response of An to [CO2 ] at different temperatures gave predictions close to the measured results, except at the lowest temperature treatment where the model over-predicted the effect of elevated [CO2 ]. This and measurements of An made at a common, low [CO2 ] indicated a down-regulation of photosynthesis in the lowest temperature treatment at high [CO2 ]. Root plus soil respiration on a whole-tree basis (Rtr ) was increased by elevated [CO2 ] at all but the lowest temperature, but no effect was seen of [CO2 ] on root respiration per unit root d. wt. Mean Rtr on any given date was significantly correlated with An , except at the lowest temperature treatment. It is hypothesized that low temperature limited the ability of the roots to use photosynthates resulting in a feedback inhibition of An when elevated [CO2 ] was combined with low temperature.

The arsenical resistance operon of IncN plasmid R46.

The arsenical resistance operon of the IncN plasmid R46 consists of 4696 bp and starts with predicted transcriptional control and initiation signals, followed by five genes, arsD, arsA, and arsC. The corresponding Escherichia coli chromosomal ars operon and two staphylococcal ars operons lack arsA and arsD genes. The R46 system contains only the second known versions of arsA and arsD, after those of plasmid R773. Western blot analysis identified the R46 proteins using antibodies against R773 ArsA, ArsD and ArsR.

Characterization of a new bacteriophage which infects bacteria of the genus Acidiphilium.

A novel bacteriophage, termed phi AC1, that infects strains of the genus Acidiphilium (acidophilic, heterotrophic, aerobic, Gram-negative eubacteria) most commonly isolated from acidic mine drainage environments, has been discovered and several of its properties have been determined. This is the first report of a bacteriophage infecting such cells. The virion has a lambdoid morphology and is larger than lambda, as shown by electron microscopy and sucrose gradient centrifugation. The sedimentation coefficient of the virion is approximately 615S. The nucleic acid of phi Ac1 is dsDNA, approximately 102 kb in length. Several experimental results show that phi Ac1 is a temperate phage. The plaques are turbid, and most cells isolated from plaques produced on sensitive cells by filter-sterilized phage preparations contain the phage and are resistant to further phage infection. Southern blot analysis shows that phi Ac1 prophage DNA is integrated into the bacterial genome during the temperature growth phase.

[Dynamic strength of cast endodontic post systems]. / Die dynamische Festigkeit von angussfähigen Wurzelstiften und -stiftsystemen.

Different endodontic post systems--Permador metal posts, GT posts, Para posts, and Erlangen posts--have been compared with each other in a study. After casting a Pd-Ag-Sn-In-alloy to the posts, these experimental post-retained cores were fixed with zinc phosphate cement in the prepared root canals of extracted premolars and subjected to fatigue tests. With the parameters selected, the forces could be reduced to 22.5N, thus approximating physiological conditions. This test was followed by a thorough inspection of the material (EDS analysis, metallographic preparations, SEM). The Permador post showed the highest dynamic strength, while the Erlangen post material was found to be unsuitable for casting to two different palladium-base alloys.

Selenate reduction by bacteria from a selenium-rich environment.

Samples collected from Kesterson Reservoir were screened for bacterial presence and selenate reduction capability. Selenate concentrations of 100 mg/liter were not toxic to indigenous bacteria. Of the 44 samples collected, 20 possessed microbial populations capable of reducing selenate. Reduction was observed in 4% of the water samples, 92% of the sediment samples, and 100% of the soil samples. Microbial reduction of 100 mg of selenate per liter was complete within 1 week of incubation. Up to 75 mg of selenate per liter was reduced beyond selenite to an insoluble red precipitate. Data collected indicate that indigenous bacteria have a significant role in the biogeochemical cycling of selenium.

Stillbirth. A humanistic response.

A predictable pattern of grief follows every perinatal death. Because of their lack of training in the area of death and bereavement, physicians have traditionally avoided acknowledging the grief process in patients who have experienced such a loss. Obstetricians must begin to recognize the appropriate intervention that needs to be instituted in the delivery room and postpartum period to help facilitate the normal grieving process. Physicians must also acknowledge and accept their own feelings of grief and helplessness following a perinatal death.